HomeMy WebLinkAboutPLN 16-20Cfy �t
DICKERING
Report to
Planning & Development Committee
Report Number: PLN 16-20
Date: September 14, 2020
From: Kyle Bentley
Director, City Development & CBO
Subject: The Draft Carruthers Creek Watershed Plan 2020-2030
Prepared by Toronto and Region Conservation Authority
- City of Pickering Recommendations to the Draft Watershed Plan
File: D-8100-028
Recommendation:
1. That the Toronto and Region Conservation Authority (TRCA) be requested to revise the
Draft Carruthers Creek Watershed Plan (CCWP), as follows:
(a) Providing greater clarity about the "77%" figure identified as the potential increase in
downstream peak flows under the hypothetical land use Scenario 3 modelling analysis
including: explaining that it is a "worst case" scenario and why; identifying the rainfall
and storm duration parameters for a Hurricane Hazel type event; and relating the
modelled increases in peak flows to the proposed management recommendations;
(b) Revising Management Recommendation 3.1.1 respecting the protection, expansion and
restoration of the Natural Heritage System (NHS) in the watershed, to reflect discussion
in the introductory text that precedes Table 8: NHS Management Recommendations, to
allow consideration of alternative configurations, size and composition for an enhanced
NHS to that identified on Map 2 of the Draft CCWP; and
(c) Adding a new Management Recommendation 1.3.6 stating that TRCA continues to support
and enhance the existing flood model by increasing the number of rainfall monitoring
stations and stream flow gauges on all tributaries including the most minor; and
2. That a copy of this Report and Council's resolution be forwarded to the TRCA, the Region of
Durham and the Town of Ajax.
Executive Summary: On March 16, 2020, the Toronto and Region Conservation Authority
(TRCA) released the Draft Carruthers Creek Watershed Plan (CCWP) for public review. The new
CCWP has been developed by the TRCA in collaboration with the Region of Durham, the City of
Pickering and the Town of Ajax. The watershed plan process included an assessment of the
current health of the watershed, revisiting its vision and management philosophy, detailed
fieldwork, developing scenarios, recommending management actions focused on the protection,
restoration, enhancement, and long-term management of the watershed, as well as a proposed
monitoring and evaluation program to track the implementation of the Watershed Plan.
The work on the Watershed Plan commenced in 2015, and included various stakeholder and public
engagement opportunities. The Draft CCWP is provided as Attachment #1, and can also be
accessed via the following hyperlink:
https://trca.ca/conservation/watershed-management/carruthers-creek/watershed-plan/.
Report PLN 16-20 September 14, 2020
Subject: The Draft Carruthers Creek Watershed Plan Page 2
Comments on the Draft CCWP were initially due June 16, 2020, but the deadline was indefinitely
postponed in view of the COVID-19 pandemic. Council is requested to endorse the
recommendations of Report PLN 16-20 derived from staff's review of the draft CCWP.
This report was prepared in collaboration with City Engineering Services staff.
Financial Implications: Not Applicable.
Discussion:
1. Structure of the Report
Section 2 of this report provides background on watershed planning. Section 3 provides
background on the Carruthers Creek watershed. Section 4 explains why an update to the
Watershed Plan was required. Section 5 provides comments and recommendations on the
Draft Carruthers Creek Watershed Plan (CCWP) for Council's consideration. Appendix I
provides an overview of the CCWP, and Attachment #1 is a full copy of the Draft CCWP.
2. What is the Purpose of Watershed Planning?
The purpose of a watershed plan is to understand the current conditions of a watershed
and identify measures and actions to protect, enhance and restore the health of a
watershed. Watershed planning is aimed at maintaining the ecological integrity of a
watershed, which consists of two integrated systems — the water resources system and the
natural heritage system, and to inform decisions on planning for water, wastewater and
stormwater infrastructure, and the allocation of growth.
Watershed planning integrates natural systems into land use and infrastructure
decision-making by identifying natural features to protect and by recommending how to
mitigate impacts from land use and infrastructure development on natural systems.
The main policy drivers for watershed planning are the Provincial Policy Statement
(PPS, 2020), A Place to Grow: Growth Plan for the Greater Golden Horseshoe, 2020,
(Growth Plan), and the Greenbelt Plan, 2017 (Greenbelt Plan). PPS policies encourage a
coordinated approach to planning and recognize that watersheds provide an ecologically
meaningful scale for integrated and long-term planning. The polices also direct the
protection, improvement or restoration of the quality and quantity of water by minimizing
potential negative impacts. Similarly, Growth Plan and Greenbelt Plan policies require
watershed planning to be undertaken to support the protection, enhancement or restoration
of the quality and quantity of water within a watershed. Municipalities are required to
conform to the PPS and applicable provincial plans when updating their official plans and
making planning decisions.
3. Where is the Carruthers Creek Watershed?
Carruthers Creek is a small watershed located west of Lake Ridge Road, extending from
the Eighth Concession Road in the north to Lake Ontario in the south. The watershed
covers rural lands in northeast Pickering, and rural and urban areas in the eastern parts of
the Town of Ajax (see Figure 2: Carruthers Creek Watershed, and Figure 3: Carruthers
Creek Subwatersheds, pages 10 and 16 of Attachment #1).
Report PLN 16-20 September 14, 2020
Subject: The Draft Carruthers Creek Watershed Plan Page 3
The watershed is bordered to the east by the Lynde Creek watershed and to the west by
the Duffins Creek watershed. Rural lands in the Carruthers Creek watershed located
between Highway 7 and Taunton Road are identified as Protected Countryside in the
Greenbelt Plan.
In the south part of the Carruthers Creek watershed in the Town of Ajax, there is an area
identified as a "Flood Vulnerable Cluster" where existing structures are located in the flood
plain (see Figure 2, page 10 of Attachment #1). There has been historical and recent
flooding events in the Carruthers Creek watershed due to extreme precipitation events.
4. Why was the Carruthers Creek Watershed Plan Updated?
Firstly, the previous watershed plan for this area, the Duffins and Carruthers Creek
Watershed Plan, dates back to 2003. Many changes have taken place in the watershed
since 2003, partly as a result of climate change and urbanization. Also, provincial policy
regarding watershed plans have evolved, and science has become more advanced in
monitoring and modelling the impact on, and the conditions and functions within, watersheds.
In view of the evolving planning regime and the science advancements, and since many of
the issues identified in the 2003 watershed plan are still prevalent, an updated watershed
plan was considered necessary in 2015.
The Region of Durham engaged the Toronto and Region Conservation Authority (TRCA) in
a consulting capacity to develop the new watershed plan for Carruthers Creek. At the
request of the Region, a small area of the East Duffins Creek subwatershed, that are
immediately adjacent to the Carruthers Creek watershed, was included in the watershed
plan study area to provide a more complete analysis of lands in the area.
Secondly, policy 7.3.11 p) of the Durham Regional Official Plan (ROP) requires a
watershed plan update for the East Duffins and Carruthers Creek watersheds where a
"Municipal Comprehensive Review" of the ROP includes consideration of an urban area
expansion into lands in northeast Pickering.
The Region is undertaking a municipal comprehensive review of its Official Plan. Through
that review process, the Region has received two requests to expand the urban area into
northeast Pickering: one from Pickering Council to enable age friendly and more affordable
housing residential development (Resolution #140/19, dated September 19, 2019); and the
other from Dorsay (Pickering) Limited (Dorsay')1, dated October 17, 2019. Dorsay's
request would facilitate the development of a proposed new community, known as
"Veraine"2, on lands that include the northern third of the Carruthers Creek watershed.
1 Dorsay (Pickering) Limited owns approximately 25 percent of the lands in the Veraine Master Planning Area. On
their own initiative, Dorsay put together an interdisciplinary consulting team to undertake a planning study on the
Veraine lands. A Vision and Guiding Community Planning Principles have been prepared as well as a number of
background reports in support of their request to be included in the urban area.
2Veraine is the name given to a proposed new community on lands in northeast Pickering. The Veraine lands are
generally bounded by Westney Road to the west; the Eighth Concession Road to the north; Lake Ridge Road to
the east; and the Sixth Concession Road/Highway 7 to the south. The lands are outside of the Greenbelt and are
currently rural.
Report PLN 16-20 September 14, 2020
Subject: The Draft Carruthers Creek Watershed Plan Page 4
5. Staff Comments
Overall, staff congratulates the TRCA in bringing the long process to a conclusion and
producing an updated comprehensive watershed plan. It is evident that significant effort
went into producing a document that uses plain language, defines most terms, is generally
easy to read (use of infographics, for example), and logically laid out in accordance with the
process followed.
This is especially important because readers do not always read a document from front to
back, or comprehend what terms mean if they do not have background knowledge in
watershed planning and the many sciences it involves.
Staff generally agrees with the majority of the Management Recommendations, but through
the detailed review of the Draft CCWP, have identified a number of matters that need
clarification. These concerns relate to the following:
• The lack of clarity around the presentation of a "77%" increase in downstream flooding
under land use Scenario 3 with a Hurricane Hazel event;
• The lack of clarity regarding the proposed enhanced Natural Heritage System shown in
the central and northern sections of the Carruthers Creek watershed, and reflected in
land use Scenarios 2 and 3; and
• The lack of clarity about whether rainfall and stream flow data will continue to be
collected for the current watershed flood model.
These concerns are discussed in more detail below.
5.1 The lack of clarity around the study findings of a "77%" increase in downstream
flooding under Scenario 3
As described in Appendix I to this report, and shown on Figure 5: Future Scenarios
Mapping, page 33 of Attachment #1, the Draft CCWP developed 3 hypothetical land use
scenarios to model the impact on the natural systems. Scenario 1 reflected development in
accordance with the existing official plan designations. Scenario 2 added an enhanced
natural heritage system to this development. Scenario 3 then added urban development to
lands in northeast Pickering. Urban development assumes an increase in imperviousness,
and a faster rate of stormwater run-off than natural or rural land use.
The natural hazard conditions for each land use scenario, and two storm events, were
modelled. The results are shown on the Table 4 infographic on page 38 of Attachment #1.
The change in conditions, measured relative to Scenario 1, indicates that under Scenario 3
with a Hurricane Hazel type storm, peak flows downstream would increase by 77%, which
would cause significant impact to flood levels throughout the watershed.
The use of an infograph in this case, as a way to simplify complex modelling, assumptions
and inferring potential impacts, produced a single number ("77%") that is easily
misunderstood by readers without the context of how the management recommendations
address this finding.
Report PLN 16-20 September 14, 2020
Subject: The Draft Carruthers Creek Watershed Plan Page 5
In this regard, City staff found that the background Hydrological Assessment, prepared for
the CCWP in November 2019, provided a better discussion of the implications of the
modelling results and recommendations to address the potential increase in peak flows
(see Extract of Hydrological Assessment, pages 10-14, Attachment #2). The discussion
immediately follows the presentation of the modelling results. It is quite possible that
readers of the Draft CCWP didn't read the text of the Plan in detail, and/or read no further
than the page 38 infographic, and the Summary of Implications on page 39.
Review of the Hydrological Assessment and discussions between the City's Division Head,
Water Resources & Development Services and TRCA engineering staff, revealed that an
increase in downstream flooding by 77% is an inaccurate presentation of the Assessment's
findings. The 77% figure does not appear in the Hydrological Assessment. The "77%"
represents an average of the change at 2 measurement points in the watershed, (Taunton
Road and Shoal Point Road), and could not be relied upon as an average for the whole
watershed. The figure overstates the increase in peak flows at Shoal Point Road and
understates the increase in peak flows north of Taunton Road.
The TRCA is receiving comments that indicate readers are drawing the conclusion that no
urban development can occur northeast Pickering on the basis of the 77% figure. This is
not the case. The Draft CCWP identifies potential impacts of development and proposes a
series of mitigation measures to manage those impacts, should development be
considered within the headwaters area. Mitigation measures could include improving
downstream conveyance, flood protection options and/or on-site controls. As a result of the
general public misunderstanding about the meaning of the 77% figure, the Chief Executive
Officer of the TRCA issued a letter of clarification on July 20, 2020 (see Letter from John
MacKenzie, Attachment #3).
The natural hazard modelling simulates a Hurricane Hazel type event. But the Plan
contains no details on the assumptions used to model a Hurricane Hazel storm. The
Hurricane Hazel modelling scenario is a "worst case" scenario. For those who are not
aware, after a very wet fall, Hurricane Hazel struck Southern Ontario on October 15, 1954,
dropping 285 millimeters (11.22 inches) of rain in 48 hours. In those conditions, it is
assumed that all existing stormwater infrastructure has failed or is overflowing. Thus, the
modelling did not factor in modern stormwater management facilities. Although Hurricane
Hazel struck the western part of the Greater Toronto Area, the TRCA uses that rainfall
amount and duration to calculate the flood plain for each of its watersheds.
As a "worst case" scenario", the modelling of Hurricane Hazel type storm becomes the
benchmark against other urban land use scenarios would be compared. However, the
comparison would have to be made in the context of the additional studies that would need
to be completed and proposed mitigations measures to manage the impacts as identified in
the Management Recommendations of the Draft CCWP (see Management
Recommendations for the Carruthers Creak Headwaters Area, pages 54 and 55 of
Attachment #1).
Staff recommends that greater clarity be provided about the "77%" figure including:
explaining that it is a "worst case" scenario and why; identifying the rainfall and storm
duration parameters for a Hurricane Hazel type event; and relating the modelled increases
in peak flows to the proposed management recommendations.
Report PLN 16-20 September 14, 2020
Subject: The Draft Carruthers Creek Watershed Plan Page 6
5.2 The lack of clarity regarding the proposed enhanced Natural Heritage System shown
in northeast Pickering, and reflected in Modelling Scenarios 2 and 3
Scenarios 2 and 3 reflect an enhanced Natural Heritage System (NHS) in the central and
northern parts of the watershed (north of Taunton Road, up to the headwaters) (see
Scenarios Mapping, page 33 of Attachment #1). The enhanced NHS increases the area of
natural cover from its current 25 percent to 36 percent (which equals an increase in natural
cover of approximately 415 hectares (1,030 acres) of land). This would create a NHS that is
significantly larger than the NHS reflected on Schedule IIIA of the Pickering Official Plan,
and the Regional NHS for the Growth Plan, completed by the Ministry of Natural Resources
in 2019.
It is stated on page 49 of the Draft CCWP that it will be up to municipalities to adopt a NHS
that is consistent with provincial policy and informed by the goals and objectives of the
CCWP. The Draft CCWP also points out that the exact size and configuration of the NHS
could fluctuate due to other factors, assuming the analysis is comparable to the one that
resulted in the proposed enhanced NHS recommended in the Plan. However, the language
in the narrative is not carried into the management recommendations. Management
Recommendation 3.1.1 regarding the protection, enhancement and restoration of a NHS
refers to the recommended NHS as set out in Map 2: Carruthers Creek Watershed Plan:
Enhanced Natural Heritage System (see page 64 of Attachment #1). Accordingly, the
enhanced NHS as reflected in the Draft CCWP could be misconstrued as being the only
possible option for the headwaters.
A watershed plan seeks the best possible outcomes to improve and restore the conditions
of, and functions within, a watershed. The inclusion of large tracks of farmland into an
enhanced NHS as shown in hypothetical Scenarios 2 and 3, may present a best -case
scenario from a watershed planning perspective. However, the proposed NHS represents a
poor scenario from a land development perspective (significantly reducing and fragmenting
potential development areas and jeopardizing coherent urban development on lands in
northeast Pickering). The Draft CCWP does not address the possibility of whether the
municipality may adopt and implement an enhanced NHS with an alternative configuration,
size or composition in the headwaters, subject to studies demonstrating that it is consistent
with provincial policy and the goals and objectives of the CCWP.
It is recommended that the Draft Management Recommendation 3.1.1 respecting the
protection, expansion and restoration of the NHS in the watershed be revised to reflect the
discussion in the text that precedes Table 8: NHS Management Recommendations, to
allow consideration of alternative configurations, size and composition for an enhanced
NHS to the existing recommended NHS on Map 2.
Staff further note that should development not be considered in northeast Pickering, a
significant land acquisition program would be required to secure additional lands in public
ownership and rehabilitate them to a natural condition. While selected owners may be
willing to enter into a management agreement and convert the land to natural cover, it is
unlikely any amount close to the required 415 hectares would be secured.
Report PLN 16-20 September 14, 2020
Subject: The Draft Carruthers Creek Watershed Plan Page 7
5.3 The need to continually gather data to calibrate the flood model
Land Use Management Recommendation 1.3.5 states that TRCA complete comprehensive
floodplain mapping based on new models and best available information to inform land use
and infrastructure decisions. Although new flood models may be developed, there has been
significant background work completed as part of this Draft Watershed Plan using the
existing flood model. The model was used to evaluate a land use scenario in 2012.
If a decision is made that development will be permitted in northeast Pickering, it is clear
that much more detailed modelling will be required to assess the impacts on the watershed
of both the proposed NHS and the proposed development. The modelling would need to
address both the "usual" subdivision level stormwater controls plus an evaluation of
upstream and downstream mitigation measures to ensure downstream flooding does not
increase.
The Draft CCWP is silent of the importance of ensuring the watershed model is continually
updated to be as accurate as possible. Should the decision be made to consider urban
development in northeast Pickering, the most up-to-date calibrated model should be
available based on ongoing collection of rainfall and stream flow on each tributary, no
matter how minor. This was particularly important in Seaton as the stormwater model was
calibrated on updated data to allow the effect on the tiniest tributary to be modelled.
Accordingly, it is recommended that a new Management Recommendation 1.3.6 be
included stating that TRCA continue to support and enhance the existing flood model by
increasing the number of rainfall monitoring stations and stream flow gauges on all
tributaries. Adding this Recommendation would allow both the development of new models,
if feasible, and the ongoing refinement and calibration of the current flood model in the
watershed at a very detailed level.
6.0 Conclusion
A watershed plan is not a land use plan. However, the recommendations from this new
watershed plan will help shape future decisions regarding land uses and infrastructure by
identifying natural features to protect and recommending how to mitigate impacts from
development.
It is therefore important that any potential for misinterpretation of the information in the Draft
CCWP is clarified. It is recommended that the TRCA clarify the study findings of a "77%"
increase in downstream flooding under Scenario 3, revise Management Recommendation
3.1.1 respecting the protection, expansion and restoration of the Natural Heritage System
in the watershed, and add a new Management Recommendation 1.3.6 indicating that
TRCA continues to support and enhance the existing flood model.
Report PLN 16-20 September 14, 2020
Subject: The Draft Carruthers Creek Watershed Plan Page 8
Appendix
Appendix I Overview of Draft Carruthers Creek Watershed Plan, 2020-2030
Attachments
1. Draft Carruthers Creek Watershed Plan, 2020-2030 (released March 16, 2020)
2. Extract of Hydrological Assessment, 2019 (pages 10 to 14)
3. Letter from John MacKenzie, Chief Executive Officer, of the TRCA, dated July 20, 2020
Prepared By: Approved/Endorsed By:
Dean Jacobs, MCIP, RPP
Manager, Policy & Geomatics
DJ:CR:Id
Catherine Rose, MCIP, RPP
Chief Planner
x
Kyle Bentley, P. Eng.
Director, City Development & CBO
Recommended for the consideration
of Pickering City Council
Marisa Carpino, M.A.
Interim Chief Administrative Officer
Appendix I to
Report PLN 16-20
Overview of the Draft Carruthers Creek Watershed Plan
Overview of the Draft Carruthers Creek Watershed Plan
Process, Findings and Recommendations
1. The Development of the Draft CCWP
The main components of the Draft CCWP are listed below, and then described in more
detail in the following sections that follow:
(a) a communication and engagement strategy;
(b) developing a new vison for the watershed;
(c) characterizing the watershed (to understand the current state of the watershed);
(d) assessing future conditions based on potential land use scenarios; and
(e) developing a management framework consisting of proposed management
recommendations and a monitoring and evaluation program.
2. The Communication and Engagement Strategy
The project team consulted with the Mississaugas of Scugog Island, as well as numerous
stakeholders including watershed residents, developers, farmers, golf course operators,
and residents from Ajax and Pickering. Additionally, the communication and engagement
strategy involved:
• reports and presentations to Councils and Committees of the Region of Durham, the
City of Pickering, and Town of Ajax;
• municipal working group sessions with staff from the Region, City of Pickering, and the
Town of Ajax through the duration of the study;
• the launch of an interactive website to promote participation and notify the public and
stakeholders of events, and posting study materials for comments, including on an
on-line survey; and
• public open houses have been held in both Ajax and Pickering, one in each of phases
1 and 2 of the study.
The third and final open house, which has been postponed due to the Covid-19 pandemic,
has not yet been held.
3. A new vision for the Carruthers Creek Watershed (CCW)
The following new vision for the CCW was developed through stakeholder and municipal
working group inputs:
Carruthers Creek watershed is a healthy and resilient natural system that is
managed through partnerships to balance resource protection with human
activity. Sound science and best management practices will protect and restore
ecosystem functions, protect watershed residents from natural hazards like
flooding, and maintain our natural heritage and water resources for present and
future generations (see page 11 of the Draft CCWP, Attachment #1).
4. Watershed Characterization
Watershed characterization determines the current state of the watershed and consists of
assessing the water resources system and natural heritage system in the watershed.
Toronto and Region Conservation Authority's (TRCA) characterization of the CCW included
the preparation of eight peer-reviewed technical reports that assessed the following aspects:
Overview of the Draft Carruthers Creek Watershed Plan Page 2
(a) hydrogeology (groundwater conditions);
(b) fluvial geomorphology (the creek's flow and sediment movement process, drainage
patterns and erosion risks);
(c) aquatic crossings and barriers;
(d) aquatic habitat (e.g., fish community richness and composition, stream temperature,
etc.);
(e) headwater drainage features (small streams in the upper portions of the watershed
that may not flow year round);
(f) water quantity;
(g) surface water quality; and
(h) terrestrial (land based) features (habitat, species, and natural cover).
The four key issues that were identified through the watershed characterization process are
as follows:
1. The aquatic ecosystem is sensitive and near the level of land use development it can
sustain long-term.
2. There is not enough natural cover, or good quality habitat, needed to maintain
ecosystem resilience (i.e., capacity to respond to change) due to changing land use
patterns and climate change.
3. Water quality is impaired (i.e., degraded), requiring improvements to stormwater
management.
4. The flow of water through the watershed is out of balance from natural conditions,
resulting in flooding and erosion issues.
In order to better understand the conditions of the watershed, TRCA included a summary of
the benchmarks and associated targets in relation to each of the key issues listed above in
the Plan (see Table 2: Current Watershed Conditions Benchmarks, pages 27 to 29 of
Attachment #1).
The benchmarks are key reference points for understanding how watershed conditions can
change over time in order to evaluate the success of the watershed plan. The targets (or
rating scales) show the ideal state of each particular watershed component, including
aquatic health, groundwater recharge, habitat quality, etc. The targets are informed by
relevant TRCA strategies, federal or provincial guidance materials, and established
conservation science.
5. Scenario Development
Understanding how a watershed will respond to potential future changes requires an
analysis of alternate scenarios that reflect a difference composition of possible land use
conditions. Accordingly, the following three hypothetical future scenarios were used and
compared to 2015 land use conditions (the baseline) as part of the CCW planning process
(see Figure 5: Future Scenarios Mapping, page 33 of Attachment #1) and as described
below:
• Scenario 1 (+OP) assumes all lands south of the Greenbelt are developed as planned in
approved Official Plans up to the year 2031.
Overview of the Draft Carruthers Creek Watershed Plan Page 3
• Scenario 2 (+NHS) assumes the same development as Scenario 1 but includes a
proposed enhanced Natural Heritage System (NHS) that includes natural features and
areas, such as forests, meadows, wetlands, and potential natural cover enhancement
areas. The proposed enhanced NHS was informed by new and updated information
from natural heritage science and practices and is intended to identify a more expanded
and integrated NHS consisting of existing natural cover and potential areas for additional
natural cover that would improve ecosystem functions and services in the watershed.
• Scenario 3 (+Potential Urban) assumes post -2031 urban development in the
headwaters of Carruthers Creek (northeast Pickering lands) outside the proposed
enhanced Natural Heritage System.
It is important to note that scenario analysis does not result in decisions about the type and
configuration of land uses. Instead, scenario analysis helps to inform decisions through the
municipal planning process (e.g., Official Plans). It is the responsibility of the applicable
municipality to determine the ultimate land use configuration for any future changes within
the watershed.
Key components of watershed health were assessed in terms of each of the three future
scenarios, to identify whether the watershed responds positively, neutrally, or negatively to
the potential future scenarios in comparison to identified benchmarks. Climate change was
incorporated into the scenario analysis where possible. For example, storm events
considered to be more frequent under climate change scenarios were included in the
hydrologic modelling in the watershed planning process.
The main results of the scenario assessment process are as follows:
• The condition of the aquatic habitat and functions in the watershed will deteriorate
overall from current conditions by 6% under Scenario 1, and by 12% under Scenario 3,
likely resulting in the loss of Redside Dace (endangered fish species) within the
watershed. Implementing the management recommendations identified in this
watershed plan, especially limiting impervious cover and undertaking restoration
activities will help Redside Dace habitat.
• The condition of the NHS, which includes terrestrial habitat and their functions, will
improve overall from current conditions by 1% under Scenario 1, by 7% in Scenario 2,
but will slightly decrease by 6% under Scenario 3 due to the impacts of surrounding
urban development.
• Water quality within the watershed is likely to continue deteriorating with increased
urbanization unless improved land use practices, and salt and stormwater management
are implemented.
• The existing flooding issues in the watershed will increase marginally (by 2%) under
Scenario 1 but that increase will be neutralized under Scenario 2 (the flood risk would in
essence be the same as current conditions). However, flooding issues will significantly
increase (by 77%) under Scenario 3, unless considerable mitigation measures are
implemented.
Overview of the Draft Carruthers Creek Watershed Plan Page 4
6. Management Framework
In order to address the four main results of the scenario assessment process (listed
above), the Draft CCWP contains a Management Framework that consists of goals
(outcomes to achieve) and corresponding objectives (statements about desired results/steps
to undertake to achieve goals); indicators (how the progress of implementing the objective
is going to be measured); and management recommendations (explanation of what should
be done) to protect, restore and enhance the health of the watershed. The proposed
Framework, consisting of three goals, nine objectives and eleven indicators, is contained in
Figure 6: Overview of Management Framework (see page 42 of Attachment #1).
The 3 goals that have been set for the CCW are as follows:
• achieve sustainable land use and infrastructure development patterns to protect,
enhance and restore water quality and maintain stable water balance;
• protect, enhance and restore the areas and features that make up the Water Resource
System (including aquatic habitat) for ecosystem resilience and sustainability; and
• protect, enhance and restore the Natural Heritage System and urban forest within the
watershed to improve ecosystem resilience and sustainability.
The Management Recommendations (MRs) in relation to each of the above 3 goals and
their associated objectives are contained in Tables 6, 7, and 8 respectively of the Plan
(see pages 43, 47 and 50 of Attachment #1). The MRs apply to the entire watershed. MRs
specific to the Headwaters are contained in Table 9 (see page 54 of Attachment #1).
The MRs in relation to the Land Use/Infrastructure, Water Resource System, and Natural
Heritage System Goals speak mostly to proposed actions to be taken by the Region of
Durham, or the Town of Ajax or City of Pickering, and/or to collaboration between all three
municipalities and/or TRCA to achieve associated objectives. The majority of the MRs are
"encouraging" in nature, acknowledging that the implementation of many recommendations
is dependent upon factors such as available resources, level of collaboration, local context
and decision making.
Attachment #1 to Report #PLN 16-20
Carruthers Creek
WATERSHED PLAN
2020 - 2030
Developed in collaboration with
the Town of Ajax and City of Pickering
DURHAM
REGION
elkToronto and Region
Conservation
Authority
Executive Summary
A watershed is an area that is drained by a river and its tributaries. Healthy watersheds provide
numerous ecosystem services; from sustaining drinking water, supporting biodiversity,
reducing flood and erosion hazards, protecting the quality and quantity of water, and
replenishing aquifers. Due to the importance of healthy watersheds, they merit collaborative
efforts to ensure their long-term sustainability.
The purpose of a watershed plan is to understand the current conditions of the watershed,
and identify measures to protect, enhance and restore the health of the watershed. Watershed
planning integrates natural systems into land use and infrastructure decision-making by
identifying natural features to protect and by recommending how to mitigate impacts from
land use and infrastructure development on natural systems. Ontario's provincial planning
framework recognizes that watershed planning is important to informing land use and
infrastructure planning decisions.
The development of this watershed plan has been a collaborative effort between the Toronto
and Region Conservation Authority (TRCA), the Region of Durham, the Town of Ajax and the
City of Pickering. Additional stakeholders and members of the public have been involved
throughout the watershed planning process.
Carruthers Creek is a small watershed that crosses rural and urban lands, including portions
of the provincial Greenbelt, before entering Lake Ontario. Urbanization and the impacts of
climate change will continue to stress the health and resiliency of the watershed. Watershed
planning is a means to identify opportunities to mitigate and adapt to potential changes in
watershed health arising from land use and infrastructure development patterns.
Carruthers Creek Watershed Plan
The development of the Carruthers Creek Watershed Plan was a
multi-year process that consisted of:
0 Watershed characterization, which involves the identification of current conditions
in the watershed.
The key issues with Carruthers Creek were identified to be:
a. The aquatic ecosystem is sensitive and near the level of land use development it can
sustain long-term (without additional and improved mitigation).
b. There is not enough natural cover, or good quality habitat, needed to maintain
ecosystem resilience (i.e. capacity to respond to change) due to changing land use
patterns and climate change.
c. Water quality is impaired (i.e. degraded), requiring improvements to stormwater
management.
d. The flow of water through the watershed is out of balance from natural conditions
resulting in flooding and erosion issues.
0 Understanding future conditions through the analysis of potential land use scenarios.
Three potential future scenarios were compared to 2015 land use conditions as part of the
Carruthers Creek watershed planning process.
a. Scenario 1 (+OP) — assumes all lands south of the Greenbelt are developed as planned in
approved Official Plans up to the year 2031.
b. Scenario 2 (+NHS) — assumes the same development as scenario 1 but includes the
proposed enhanced Natural Heritage System (includes natural features and areas, such
as forests, meadows, wetlands, and potential natural cover enhancement areas).
c. Scenario 3 (+Potential Urban) — assumes post -2031 development in the headwaters of
Carruthers Creek outside the proposed enhanced Natural Heritage System.
These three potential future scenarios help determine how the watershed would react to
these potential land use changes, which can help inform future land use and infrastructure
planning decisions. In other words, would these potential changes have a positive, neutral,
or negative effect on the health of the Carruthers Creek watershed? Scenario analysis does
not result in decisions about the type and configuration of land uses. Instead, scenario
analysis helps to inform decisions through the municipal planning process (e.g. Official
Plans, secondary plans).
0
The development of a management framework to provide recommendations on how
to protect, enhance and restore the watershed. The management framework consists
of goals, objectives, indicators and management recommendations. This management
framework is designed to address existing issues in the watershed and mitigate impacts
from potential future land uses, while recommending appropriate actions to protect,
enhance and restore the watershed. Decisions on the configuration of future growth
and land use throughout the watershed are the purview of the applicable municipality
(e.g. Region of Durham for decisions such as settlement area boundary expansions and
local municipalities for site-specific decisions).
0 A monitoring and evaluation program to track implementation progress and ensure
mechanisms are in place to adjust approaches as needed. The indicators identified as
part of the management framework will help determine if actions taken in the watershed
are having the desired benefit. Adaptive management will be used to adjust the
management framework as needed.
Through the implementation of the Carruthers Creek Watershed Plan, TRCA and its municipal
partners, can improve the health of the watershed and ensure integrated long-term planning
for land use and infrastructure decision-making. Protecting, enhancing and restoring the natural
systems within the watershed; accompanied by sustainable land use and infrastructure planning
of redevelopments and future growth is essential for a healthy Carruthers Creek watershed.
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WHAT IS A WATERSHED?
An area that is drained by a river and its tributaries.
Wherever you are right now, you are in a watershed.
WATERSHEDS DELIVER IMPORTANT BENEFITS
Human - provide safe drinking water and food, and
help to reduce flooding and erosion.
Economic - produce energy, and supply water for
agriculture, industry and homes.
Environment - promote a healthy water cycle,
and provide vital habitat for wildlife and plants.
What is the Natural Heritage System?
Consists of natural features and areas,
including wetlands, forests, meadows and
valleylands, that are needed to maintain
biodiversity and healthy ecosystems.
io 44° 14 r
What is the Water Resource System?
Consists of groundwater and surface water
features and areas, including streams, lakes,
groundwater recharge areas and springs,
needed to sustain healthy aquatic and
terrestrial ecosystems, and human
water supply.
How can salt impact a watershed?
Chlorides can contaminate drinking
water and negatively affect the health
of aquatic species.
What causes flooding?
Rivers naturally flood with heavy rain or
snowmelt, but flooding can become a
problem when buildings and other
structures are placed in floodplains.
Climate change and urbanization can
make flooding worse.
r
What is stormwater?
Rain and melting snow rushes off roofs,
sidewalks and parking lots into pipes and
pours into streams and lakes. Without proper
stormwater control and treatment, flooding and
erosion can increase, waterways can become
polluted and local ecosystems can be damaged.
FIGURE 1
Understanding a Watershed
How can agriculture impact a watershed?
Agricultural areas provide valuable greenspace and reduce stormwater,
since precipitation can penetrate the soil. On the other hand, agricultural
fields can release harmful contaminants into waterways as excess nutrients
(e.g. phosphorus) and pesticides. Soil erosion from fields can increase the
amount of sediment in waterways negatively affecting aquatic ecosystems.
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How can urbanization impact a watershed?
Since impervious surfaces (roads, buildings, parking lots)
prevent water from penetrating into soil, stormwater
runoff can carry contaminants into waterways and
increase the likelihood of flooding. Infrastructure and land
use development can degrade habitat, reducing the quality
and quantity of natural systems and their connectivity.
0 0
Surface and Groundwater Interaction
Rain and melting snow penetrate the soil
in permeable areas draining into an aquifer
(i.e. groundwater recharge areas).
That groundwater can then discharge at
springs into streams, wetlands or other
surface water features.
Groundwater
recharge
JIIIJ 11[11.1111
Benefits of the Urban Forest
All trees in a city collectively help to remove
pollutants from air and water, reduce
stormwater runoff, cool communities,
save energy, and improve human health
and well-being.
Table of Contents
1. Introduction and Background
1.1 Rationale and Policy Basis
1.2 Local Context and Considerations
1.3 Partners and Stakeholders
2. Water Resource and Natural
Heritage Systems
3. Existing Watershed Conditions
3.1 Context and Background
3.2 Historical and Current Land Uses
3.3 Current State of the Watershed
4. Future Watershed Conditions
4.1 Future Stressors
4.2 Future Scenarios
4.3 Scenario Analysis
5. Management Framework
5.1 Land Use / Infrastructure Goal
5.2 Water Resource System Goal
5.3 Natural Heritage System Goal
5.4 Carruthers Creek Headwaters Management
6. Monitoring and evaluation
7. Maps
8. Glossary
9. References
11 LIST OF FIGURES
12 FIGURE 1: Understanding a Watershed
15 FIGURE 2: Carruthers Creek Watershed
17 FIGURE 3: Carruthers Creek Subwatersheds
FIGURE 4: Comparing Urban Forest and Natural Cover
18 FIGURE 5: Future Scenarios Mapping
FIGURE 6: Overview of Management Framework
FIGURE 7: Monitoring Stations Map
FIGURE 8: Adaptive Management Cycle
FIGURE 9: Subwatershed Quality Due to
Changes in Impervious Cover
21
22
23
23
LIST OF TABLES
30 TABLE 1: Description of the Water Resource
System and Natural Heritage System
TABLE 2:Current Watershed Conditions
Benchmarks
TABLE 3: Potential Future Land Use Scenarios
TABLE 4: Scenario Analysis Implications
TABLE 5: Management Framework Explanation
43 TABLE 6: Land Use Management
47 Recommendations
49 TABLE 7: WRS Management Recommendations
54 TABLE 8: NHS Management Recommendations
TABLE 9: Headwaters Specific Management
56 Recommendations
TABLE 10: Carruthers Creek Monitoring Program
62 TABLE 11: Restoration Opportunity Summaries
74
79
30
31
34
40
6
10
16
25
33
42
57
61
73
19
27
32
35
41
43
47
50
54
58
68
Carruthers Creek Watershed Plan
'"CRONYMS
ANSI Areas of Natural and Scientific Interest
CCME Canadian Council of Ministers of the Environment
CTC Credit Valley, Toronto and Region and Central Lake Ontario
DFO Department of Fisheries and Oceans
ESGRAs Ecologically Significant Groundwater Recharge Areas
FBI Family Biotic Index
FVC Flood Vulnerable Cluster
GIS Geographic Information System
Growth Plan Growth Plan for the Greater Golden Horseshoe, 2019
GTA Greater Toronto Area
IBI Index of Biotic Integrity
IRP Integrated Restoration Prioritization
LAM Landscape Analysis Model
MECP Ministry of the Environment, Conservation and Parks
MNRF Ministry of Natural Resources and Forestry
NHS Natural Heritage System
PPS Provincial Policy Statement
PWQO Provincial Water Quality Objectives
ROP Regional Official Plan
TRCA Toronto and Region Conservation Authority
TSS Total Suspended Solids
WRS Water Resource System
Indigenous Land Acknowledgement
As we strive to develop a comprehensive watershed plan for the Carruthers Creek watershed, Toronto
and Region Conservation Authority (TRCA) acknowledges that this watershed planning was undertaken
within the traditional territory and treaty lands of the Anishinaabeg of the Williams Treaty First Nations,
and the traditional territory of the Huron-Wendat Nation. As stewards of land and water resources within
the Greater Toronto Area (GTA), TRCA appreciates and recognizes the history and diversity of the land, as
well as our shared values and interests and is respectful of working in this territory.
Toronto and Region
Conservation
Atriiwd
A
Date: September 2019
Created by: TRCA Information Services/Information Technologies
Disclaimer:
The Data used to create this map was compiled from a variety sources
and dates. The TRCA takes no responsibility for errors or omissions
in the data and retains the right to make c anges and corrections
at anytime without notice. For further information about the
data on this map, please contact the TRCA
GIS Department. (416) 661-6600.
Carruthers Creek
Watershed Plan:
2015 Land Use
Conditions
0 0.5 1 2 3
KM
Municipal Boundary co Flood Vulnerable
Cluster
Watercourse
Land Use
Ile Natural
Rural
4 Urban
Greenbelt Boundary
Carruthers Creek
Watershed Boundary
Carruthers Creek
Watershed Plan
Study Area
1. Introduction and Background
Carruthers Creek is a small, yet important watershed that crosses rural and urban areas before
entering Lake Ontario. This watershed plan represents a collaborative effort to determine the current
state of the watershed, assess potential future land use scenarios, and determine an appropriate
management framework to ensure the long-term sustainability and resiliency of the watershed.
See Figure 2 for a map of the Carruthers Creek watershed and its land use conditions as of 2015.
This watershed plan has a ten-year time frame. However, regular monitoring and evaluation,
including adaptive management, will ensure that the watershed plan is updated, or refined, as
needed on an ongoing basis.
Vision for the Carruthers Creek watershed:
Carruthers Creek watershed is a healthy and resilient natural system that is managed through
partnerships to balance resource protection with human activity. Sound science and best management
practices will protect and restore ecosystem functions, protect watershed residents from natural hazards
like flooding, and maintain our natural heritage and water resources for present and future generations.
11
1.1 RATIONALE AND POLICY BASIS
Watershed planning is important because it helps to understand the current conditions of the
watershed (i.e. watershed characterization), and identify measures to protect, enhance and
restore the health of a watershed. Watershed plans provide a comprehensive understanding
of the ecological forms and functions of the various features and areas that comprise the water
resource and natural heritage systems. Additionally, watershed planning helps to inform how
land use and infrastructure planning influence and affect the natural ecology of the watershed.
This subsection will explain the provincial policy basis for watershed planning and the roles of
municipalities and TRCA in implementing that policy framework.
Provincial Watershed Planning Policy Basis
Ontario's planning policy framework recognizes the importance of watershed planning to
inform land use and infrastructure decision-making. The key policy driver for watershed
planning is applicable provincial policy direction in the Provincial Policy Statement (PPS, 2014)
and provincial plans such as the Growth Plan for the Greater Golden Horseshoe, 2019 (Growth
Plan) and the Greenbelt Plan, 2017 (Greenbelt Plan)'.
PPS policies encourage a coordinated approach to planning that recognizes the watershed as
the ecologically meaningful scale for integrated and long-term planning. The PPS also directs
the protection, improvement or restoration of the quality and quantity of water by minimizing
potential negative impacts. Growth Plan and Greenbelt Plan policies require watershed planning
to be undertaken to support the protection, enhancement or restoration of the quality and
quantity of water within a watershed2.
Furthermore, watershed planning is to be used to identify the Water Resource System (WRS),
inform decisions on allocation of growth and planning for water, wastewater and stormwater
infrastructure3.
Provincial policies also recognize the importance of protecting, enhancing and restoring the
Natural Heritage System (NHS) to maintain long-term ecological and hydrologic functions
of the features and areas'', and demonstrating that there will be no negative impacts from
development and site alteration. The integrated nature and importance of the natural heritage
and water resource systems is discussed in greater detail in Section 2.
'There are other geographically specific provincial plans that do not apply to the Carruthers Creek watershed (e.g. Lake Simcoe
Protection Plan, Oak Ridges Moraine Conservation Plan and Niagara Escarpment Plan).
2Growth Plan policy 4.2.1.1 and Greenbelt Plan policy 3.2.3.2
'Growth Plan policy 4.2.1.3 and Greenbelt Plan policies 3.2.3.3 and 3.2.3.4.
'Natural Heritage System policies for the Growth Plan are 4.2.2 and the Greenbelt Plan are 3.2.2.
12
Municipalities are required to conform to the
PPS and applicable provincial plans through the
municipal planning process and when updating
their Official Plans. This Carruthers Creek Watershed
Plan identifies management recommendations
necessary to demonstrate conformity with
provincial policies related to watershed planning.
By implementing the recommendations included
in this watershed plan, municipalities will be able
to demonstrate how the features and areas that
comprise the natural heritage and water resource
systems, as well as water quality and quantity, will
be protected, enhanced and restored.
Ontario's Clean Water Act, 2006 is designed to
protect existing and future sources of drinking
water. Under the Clean Water Act, 2006, source
protection plans were developed by source
protection committees representing municipal,
Indigenous, public and business interests. The
Credit Valley — Toronto and Region — Central Lake
Ontario (CTC) Source Protection Plan applies in
the Carruthers Creek watershed. The CTC Source
Protection Plan is a strategy and suite of policies
developed by residents, businesses and the
municipalities, which outlines how water quality
and quantity for municipal drinking water systems
will be protected. The CTC Source Protection Plan
includes its own set of policies and compliance
mechanisms, in accordance with the Clean Water
Act, 2006, that are not repeated in this watershed
plan. The management recommendations
identified in this watershed plan are broader than
drinking water and complement the requirements
of the applicable source protection plan.
Carruthers Creek Watershed Plan
Reducing Natural Cover Losses in the
Carruthers Creek Watershed
There have been losses and impacts to natural
cover in the watershed, including parts of the
Greenbelt. These changes have continued since the
enactment of the Greenbelt Act, 2005.
POLICY FRAMEWORK
As discussed in this section, the Greenbelt Plan is
one part of Ontario's land use planning framework.
One vital policy tool for maintaining natural cover
in both the Growth Plan and the Greenbelt Plan is
the NHS policies. Once a NHS is designated in a
municipal Official Plan, any development or site
alteration must meet certain policy requirements
in the applicable provincial Plan.
Observed land use changes within the Carruthers
Creek portion of the Greenbelt include fill sites,
road widenings, land clearing on existing lots,
farming and non-farm business operations and
vehicle and other storage.
MOVING FORWARD
This watershed plan identifies recommendations to
strengthen municipal policies to protect the NHS,
in accordance with provincial policy, and identifies
opportunities for restoration programs.
If community members are concerned about any
development, large scale tree cutting or fill activities,
please contact your local municipality, Region of
Durham, or conservation authority for assistance.
13
Ontario's provincial planning policies recognize the importance of the Great Lakes'. Carruthers
Creek flows into Lake Ontario. The series of Great Lakes agreements, legislation and policies set
binational, national and provincial commitments to protect and restore the Great Lakes. This
watershed plan is intended to improve the conditions within the Carruthers Creek watershed,
thereby reducing negative impacts to Lake Ontario from this single watershed.
Role of Municipalities
Within the Greater Golden Horseshoe, most municipalities in Ontario are organized into two-
tier systems. Upper -tier municipalities, such as the Region of Durham, are comprised of several
lower -tier municipalities. The role of regional government is to address issues and concerns that
apply to broader geographic areas, crossing the borders of lower -tier municipalities.
For land use planning, regional government's primary planning tool is a Regional Official Plan
(ROP). The ROP implements the requirements of any relevant provincial legislation, provincial
plans, and the PPS. Area municipalities develop their own, more detailed Official Plans (and may
include more detailed secondary plans, Part II Plans, or tertiary plans as the case may be), as well
as implementing zoning by-laws. While the ROP is required to implement provincial policy, area
municipal planning tools are required to conform with both Regional and provincial policy.
Municipalities are granted decision-making powers through the Municipal Act and Planning Act.
Watershed planning helps municipalities to make informed decisions on where and how to
grow, while identifying opportunities to improve natural watershed conditions (e.g. restoration
opportunities).
Role of TRCA
Conservation authorities were established and granted responsibilities under the Conservation
Authorities Act. Conservation authorities play an important role in land use planning and
environmental protection processes in partnership with municipalities, but are not the
decision -makers in land use and infrastructure planning. Conservation authorities deliver programs
and services related to natural hazard protection and management (i.e. flooding), conservation
and management of conservation authority lands, drinking water source protection (as prescribed
under the Clean Water Act, 2006), and conserving natural resources. Through its watershed
expertise, TRCA, in partnership with the Region of Durham, Town of Ajax, and City of Pickering,
has developed this watershed plan to help inform land use and infrastructure planning decisions.
'The PPS identifies the importance of considering the priorities identified in various agreements related to the protection or
restoration of the Great Lakes — St. Lawrence River Basin. The Growth Plan and Greenbelt Plan require the consideration of the
Great Lakes Strategy and the Great Lakes Protection Act, 2015, and any applicable Great Lakes agreements as part of watershed
planning.
14
Carruthers Creek Watershed Plan
1.2 LOCAL CONTEXT AND CONSIDERATIONS
Carruthers Creek is a relatively small watershed with a drainage area of approximately 38 km2,
ranging from 2-3 km in width and 18 km in length, and occurs within the South Slope and glacial
Lake Iroquois physiographic regions. It is the easternmost watershed in TRCA's jurisdiction and
is bordered by the Duffins Creek watershed to the west and the Lynde Creek watershed in the
east. The watershed has approximately 41,000 residents and is located entirely within the Region
of Durham. Carruthers Creek's headwaters form to the south of the Oak Ridges Moraine, in the
City of Pickering, and the creek enters Lake Ontario in the Town of Ajax. The watershed is mainly
rural north of Highway 7 and urbanized south of Taunton Road to the Lakeshore. From Highway 7
south to Taunton Road, most lands are in the protected countryside designation of the provincial
Greenbelt Plan.
Carruthers Creek watershed consists of four subwatersheds, for the purposes of this watershed plan.
Subwatersheds are defined as areas drained by a tributary, or portion of the stream, and are a more
geographically specific scale than watersheds. Some of the technical analyses conducted as part of
this watershed planning process used the four subwatersheds identified in Figure 3 to evaluate the
conditions of the watershed from a more refined geographic location.
The previous 2003 Duffins and Carruthers Creek Watershed Plan evaluated existing watershed
conditions and identified recommendations to protect, restore, and enhance the natural systems
and water quality of Carruthers Creek. The issues identified in the 2003 plan are still prevalent in
the Carruthers Creek watershed, such as the need to protect and restore natural areas, improve
stormwater management and address water quality concerns. Since 2003, the Carruthers Creek
watershed has undergone significant changes associated with urbanization and the impacts of
climate change (See Section 3 for more information). Since many of the issues identified in the
previous watershed plan are still occurring, an updated watershed plan using the latest advancements
in watershed science, monitoring programs and computer modelling was necessary.
Periodic reviews of watershed plans are an integral component of the watershed planning process
and allow for adaptive management to incorporate new scientific approaches and to address
emerging initiatives. This watershed plan update is also more reflective of current provincial policies
around watershed planning, which have evolved since the 2003 plan. At the request of the Region of
Durham, a small section of lands in the East Duffins Creek subwatershed, which are immediately adjacent
to Carruthers Creek watershed and outside of the provincial Greenbelt, were included in the study area
to provide a more complete analysis of lands in the area. However, only watershed planning processes
that occur at the regional, rather than the watershed scale, were assessed (i.e. NHS planning and
groundwater modelling), as these processes extend beyond the watershed boundary.
15
FIGURE 3:
Carruthers Creek Subwatersheds
-4
0,006'
044 AI'
i
NW
5ry
50,
Toronto and Region
1' Conservation
Aut6odtp
Date: Janurary 2019
Created by: TRCA Information Services/Information Technologies
Disclaimer:
The Data used to create this map was compiled from a variety sources
and dates. The TRCA takes no responsibility for errors or omissions
in the data and retains the right to make changes and corrections
at anytime without notice. For further information about the
data on this map, please contact the TRCA
GIS Department. (416) 661-6600.
16
N
s
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KT,
ti'r'`� ile
6-
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Central
Carruthers Creek
Watershed Plan:
Subwatersheds
0 0.5 1 2
3
KM
� trst
t^'
South
Subwatershed Boundary
Central
NE
NW
South
— Intermittent Streams
— Permanent Streams
IZ'Carruthers Watershed Boundary
MCarruthers Watershed Plan Study Area
The development of this Carruthers Creek Watershed
Plan was a multi-year process completed in the
following sequence:
• Field work on existing watershed conditions (2015-2016)
• Watershed characterization technical reports completed
(2017) — See Section 3 for the results of watershed
characterization.
• Potential future scenarios modelling and analysis
undertaken (2018)
• Scenario analysis technical reports completed (2019)
— See Section 4 for information on the potential future
scenarios and results
• Water Resource and Natural Heritage Systems identified
(2019) — See Section 2 for more information on these
systems
• Management framework for Carruthers Creek
developed (2019) — See Section 5 for the Carruthers
Creek management framework
1.3 PARTNERS AND STAKEHOLDERS
In 2015, the Region of Durham engaged TRCA to develop
a watershed plan for Carruthers Creek. The key partners
involved in the process to develop this watershed plan
are TRCA, the Region of Durham, the Town of Ajax and
the City of Pickering.
Throughout the multi-year process discussed in
Subsection 1.2, TRCA engaged the Mississaugas of
Scugog Island, stakeholders and the public to raise
awareness of the watershed planning process and
solicit feedback on components of this watershed plan.
Stakeholders engaged include watershed residents,
landowners, farmers, developers, golf course operators
and environmental non-governmental organizations.
Carruthers Creek Watershed Plan
Stakeholders were engaged at various points during
this watershed planning process, as follows:
LATE 2015 — LATE 2017
Promoted and raised awareness of the watershed
planning process for Carruthers Creek through reports
and presentations to Councils and Committees of the
Region of Durham, Town of Ajax, and City of Pickering.
LATE 2017 — EARLY 2019
Continued to raise awareness of the watershed
planning process for Carruthers Creek and gathered
feedback from the public on a vision for the watershed
plan. This was completed by launching an interactive
website and hosting information booths at various
events across the watershed.
MID 2019 — LATE 2019
Gathered feedback on the draft management
framework for the Carruthers Creek Watershed Plan
from partners and stakeholders. Two public open
houses were held in October 2019.
Feedback received from partners and stakeholders
was invaluable in the development of this watershed
plan. The Carruthers Creek Watershed Plan reflects
the diversity of issues and concerns raised throughout
the planning process and represents a realistic and
manageable plan to improve the overall health of the
Carruthers Creek watershed.
All the partners and stakeholders engaged as
part of this process play a key role in the effective
implementation of the management recommendations
identified in Section 5.
17
2. Water Resource and Natural
Heritage Systems
The aquatic and terrestrial features and areas that maintain the ecological integrity of a watershed
consist of two integrated systems, the WRS and NHS. Together, these two systems provide essential
ecosystem services, including water storage and filtration, cleaner air, support to biodiversity and
habitats, carbon storage, as well as resiliency to climate change. Maintaining extensive, connected
and high-quality ecological and hydrological features and areas of both systems is essential for the
long-term health and sustainability of Carruthers Creek, as shown in Figure 1.
As mentioned in Subsection 1.1, identifying and protecting both systems is a key policy requirement
in the Growth Plan and Greenbelt Plan.
18
Carruthers Creek Watershed Plan
The features and areas that comprise both systems are explained in Table 1 below.
TABLE 1:
Description of the Water Resource System and Natural Heritage System
Water Resource System
Natural Heritage System
A system consisting of groundwater features and areas
A system made up of natural heritage features and
and surface water features (including shoreline areas),
and hydrologic functions, which provide the water
areas, and linkages identified to provide connectivity
(at the regional or site level) and support natural
resources necessary to sustain healthy aquatic and
processes which are necessary to maintain biological
terrestrial ecosystems and human water consumption.
and geological diversity, natural functions, viable
populations of indigenous species, and ecosystems.
The WRS consists of:
The NHS consists of*:
Key Hydrologic Areas
• Significant Wetlands*
• Significant Groundwater Recharge Areas (including
• Significant Coastal Wetlands
Ecologically Significant Groundwater Recharge Areas)
• Other Coastal Wetlands in Ecoregions 5E, 6E and 7E
• Highly Vulnerable Aquifers
• Fish habitat*
• Significant Surface Water Contribution Areas
• Significant Woodlands
• Significant Valleylands in Ecoregions 6E and 7E
Key Hydrologic Features
(excluding islands in Lake Huron and the St. Mary's
• Permanent Streams
River)
• Intermittent Streams
• Habitat of Endangered Species and Threatened
• Inland Lakes and their Littoral Zones
Species
• Seepage Areas and Springs
• Significant Wildlife Habitat
• Wetlands*
• Significant Areas of Natural and Scientific Interest
(ANSIs)
• Sand barrens, savannahs, tallgrass prairies and alvars
• Federal or provincial parks, and conservation reserves
*Notes:
Wetlands are important features in both systems. For the purposes of mapping in Section 7, wetlands are shown separately in
Map 1A for the WRS and included as natural cover in Map 2 for the NHS. Fish habitat in the NHS overlaps with features and areas in
the WRS.
The majority of these terms are defined in the Growth Plan, 2019. Some, but not all definitions, have been included in the Glossary
(Section 8) of this watershed plan.
Not all of the NHS features or areas identified in this table are part of the proposed enhanced NHS for Carruthers Creek, since
some of these features do not exist in this watershed (e.g. sand barrens, savannahs, etc.), or are not distinguished specifically from
natural cover areas (e.g. significant woodlands and significant wildlife habitat).
Due to the importance of both systems, the protection, enhancement and restoration of the WRS and NHS are goals
of this watershed plan (Section 5).
See Section 7 for maps of the WRS and the recommended NHS.
19
How the WRS was delineated?
The key hydrologic areas and key hydrologic features
that comprise the WRS were delineated using various
techniques and methodologies.
Highly Vulnerable Aquifers and Significant Groundwater
Recharge Areas were determined through Technical
Rules established under the Clean Water Act, 2006 for the
purposes of regional source water protection planning.
Ecologically Significant Groundwater Recharge Areas
(ESGRAs) were determined using a model developed
by the Oak Ridges Moraine Groundwater Program to
optimize the protection of groundwater dependent
ecosystems. The model results for ESGRAs were assessed
to minimize the land area covered by these key hydrologic
areas while maintaining a high degree of hydrological
function protection for these ecosystems. Significant
Surface Water Contribution Areas include many of the
intermittent streams in the headwaters (northern portion)
of Carruthers Creek.
Each of the five key hydrologic features were delineated
using a combination of satellite imagery, ArcHydro GIS
and field site verification.
Protecting the WRS and NHS
The WRS provides habitat for aquatic life (e.g. fish). The
conditions of aquatic habitat in Carruthers Creek were
assessed as part of this watershed planning process.
How the NHS was delineated?
The components of the NHS were delineated using a
robust methodology that incorporated ecological models
(e.g. Landscape Analysis Model), information from satellite
imagery, monitoring data, field site verification and expert
based knowledge.
The components of the NHS were identified for their
ecological value as existing and potential natural cover
(i.e. areas targeted for restoration and enhancement), to:
• Increase natural cover (e.g. forests, wetlands, meadows,
etc.) quantity and quality by improving habitat size, shape,
and connectivity in and around existing natural areas, as
well as in areas for potential restoration;
• Protect and restore species and vegetation communities
by incorporating diverse habitat types, mitigating the
impacts of urban development, and improving the
ecological connectivity across the watershed; and
• Incorporate natural system vulnerabilities to climate
change in planning processes to build a more
resilient NHS.
As mentioned in Subsection 1.2, provincial policies recognize the importance of protecting the WRS and NHS.
Municipalities are required to demonstrate how these systems will be protected. Through its technical and
scientific expertise, TRCA delineated both systems as part of this watershed planning process.
For the recommended NHS, the areas identified as potential natural cover (enhancement areas) should be
restored to maintain the long-term resiliency and sustainability of terrestrial ecosystems, in addition to protecting
the existing natural cover. TRCA's Terrestrial Natural Heritage System Strategy has a minimum target of 30% natural
cover across the entire jurisdiction, while recognizing there will be variability among TRCA's nine watersheds due
to existing land uses. The Carruthers Creek watershed is currently below that target (see Subsection 3.3 for more
information).
The management framework (Section 5) of this watershed plan, recognizes that land use and/or infrastructure
decisions may impact, or occur, within the WRS or NHS, and establishes recommendations to avoid these
features and areas, mitigate impacts, or when impacts are unavoidable, provide for ecosystem compensation.
Municipalities are responsible for designating a NHS that is consistent with provincial policies and informed by
the goals and objectives of this watershed plan.
20
3. Existing Watershed Conditions
Watershed characterization is a vital part of watershed planning, which helps to determine the
current conditions of the watershed. As part of this watershed plan, TRCA produced technical reports
on different components of the watershed, which are summarized in this section.
21
3.1 CONTEXT AND BACKGROUND
Since the previous watershed plan is from 2003, the existing conditions of the watershed were evaluated using more
recent data and science. TRCA produced eight peer-reviewed technical reports as part of watershed characterization.
These technical reports helped determine the current state of the watershed, as discussed in Subsection 3.3.
Watershed characterization includes the following topics (see full technical reports listed in Section 9):
Aquatic Crossing and Barrier Assessment
Involved the assessment of existing structures in
Carruthers Creek that represent barriers to fish passage,
such as perched culverts and online ponds.
Aquatic Habitat and Community
Characterization
Involved the assessment of aquatic habitat conditions,
stream temperature, fish community richness and
composition, and benthic invertebrate richness and
composition.
Fluvial Geomorphology
Involved the assessment of the creek's flow and
sediment movement processes, drainage patterns,
and potential erosion risks.
Headwater Drainage Features
Involved the assessment of small streams in the
upper portions of the watershed that may not flow
year-round (i.e. intermittent and ephemeral). These
features provide hydrologic and ecological functions
to maintain downstream watershed conditions.
22
Hydrogeology
Involved the assessment of groundwater conditions
within the watershed, such as groundwater recharge and
discharge, and groundwater flow and quality.
Surface Water Quality Characterization
Involved the assessment of current and past water
quality conditions to determine trends and factors
influencing water quality.
Terrestrial Natural Heritage
Involved the assessment of natural cover, terrestrial
habitat and species across the watershed.
Water Quantity Characterization
Involved the assessment of the volume, velocity, spatial
distribution and timing of water moving through the
stream network (i.e. streamflow).
3.2 HISTORICAL AND CURRENT
LAND USES
Ongoing urbanization in the Greater Toronto Area
continues to convert natural and agricultural lands
to other uses. This is true in the Carruthers Creek
watershed as well. In 1999, the watershed consisted
of 28% natural cover, 53% agricultural lands, and
12% urban area6. As of 2015, natural cover had
dropped to 25% and agricultural lands to 34%.
Urban land use increased to approximately 37%
during that time period. See Figure 2 for a map of
2015 land use conditions. This historical context is
important for characterizing the current conditions
of the watershed as it helps to understand the rate of
change within the watershed and provides a useful
benchmark for comparison.
3.3 CURRENT STATE OF THE
WATERSHED
Based on the technical assessments conducted
as part of watershed characterization (discussed
in Subsection 3.1), there are four key issues in
Carruthers Creek:
0 WATER RESOURCE SYSTEM: the aquatic
ecosystem is sensitive and near the level of land
use development it can sustain long-term (without
additional and improved mitigation).
The current state of the WRS includes assessments
of headwater drainage features, fish communities,
instream barriers to fish movement and groundwater.
The analysis of the small stream features north
of Highway 7 (i.e. headwater drainage features),
showed that 67% of the features have been altered
(i.e. reducing hydrologic connectivity and increasing
surface runoff) in some way by human activities,
primarily through tile drainage.
Carruthers Creek Watershed Plan
Tile Drainage
Tile drainage is a common and important land
management practice in many agricultural parts of
Ontario. Tile drains are corrugated plastic tubing, clay
or concrete drains installed beneath the surface of
fields to drain excess water from the crop root zone.
Working with the agricultural community is
important to identify opportunities to mitigate the
potential impacts of tile drainage.
Consult the Ontario Ministry of Agriculture, Food
and Rural Affairs, or the Ontario Soil and Crop
Improvement Association for more information.
6Additional land use categories such as water, recreational, golf courses,
cemeteries and hydro corridors make up the remaining percentages not
included in the categories of natural, agricultural and urban land uses.
23
Currently, the fish communities within the watershed
are dominated by cool water native species. Redside
Dace, an endangered species, is currently found within
the watershed.
Urbanization results in impervious land cover (i.e.
pavement, or areas where water cannot penetrate the
ground). Imperviousness can increase the severity and
duration of peak flows during storm events, cause
erosion and sedimentation, and increase stream
temperatures, which impacts aquatic habitat for all
species. Some areas of the watershed are impacted
by poor water quality, which negatively impacts the
aquatic ecosystem (see key issue number three, water
quality for more information).
Existing instream barriers to fish movement associated
with development and infrastructure adversely impacts
the aquatic system in Carruthers Creek by limiting
access to feeding and spawning areas, increasing water
temperature, and affecting sediment transport. Instream
structures that act as barriers to fish passage include
dams, weirs, road and rail crossings, and some culverts.
From a groundwater perspective, there are three aquifer
systems present in the watershed. These aquifer systems
include one shallow system (Oak Ridges Moraine/
Mackinaw Interstadial aquifer complex) and two deep
systems (Thorncliffe and Scarborough aquifer complexes).
Long-term groundwater quality information for specific
sites within the Carruthers Creek watershed
are unavailable, but there have been a number of
studies conducted in adjacent watersheds to provide
an indication of background groundwater quality.
The available information from Duffins Creek and Rouge
River indicate elevated levels of nitrates and chlorides in
groundwater attributed to road salts and fertilizer use.
Maintaining the flow between groundwater and surface
water (i.e. recharge and discharge) is essential for a
healthy watershed.
24
0 NATURAL HERITAGE SYSTEM: there is not enough
natural cover, or good quality habitat, needed to maintain
ecosystem resilience (i.e. capacity to respond to change)
due to changing land use patterns and climate change.
As of 2015, approximately 25% of the watershed consisted
of natural cover. Approximately 9% of that natural cover is
forest, 7% wetland, 4% successional (transitioning to forest),
and 3% meadow'. Current habitat conditions are overall
poor in terms of patch size, shape and influences from
surrounding land uses.
In addition to this assessment of natural cover within the
watershed, TRCA also conducted terrestrial inventories of
plants and animals. These inventories found 845 vascular
plant species, of which only 57% are native species. These
results indicate a significant presence of invasive species,
such as dog -strangling vine, garlic mustard, and common
buckthorn. The inventory also identified 153 flora species of
regional conservation concern including four species that
have not been found anywhere else in TRCA's jurisdiction.
Inventories documented a total of 133 breeding vertebrate
fauna species over the past decade comprised of 106
breeding birds, 18 mammals, and 9 herpetofauna (i.e.
reptiles and amphibians).
The urban forest within the Carruthers Creek watershed
contains 94 types of woody plant species, with over 270
varieties. Maples make up the most common type of tree
within the watershed. In 2017, approximately 23% of the
watershed consisted of tree and shrub canopy.
7The remaining natural cover percentages are around, or less than, one percent,
consisting of water, hydro corridors, and beach/bluff.
Urban Forest
(tree cover)
•motip
o
r 1 r
11111.11111111118
1r
MI. r
1
11
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11
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hui )r41r A
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FIGURE 4
Comparing Urban Forest and Natural Cover
Natural cover
Forest cover
1
Difference between urban forest and natural cover
The term urban forest is used to describe the trees and woody shrubs located on all private
and public property within a watershed, including urbanized spaces (e.g. along roads) and in
forests. The percentage of urban forest within a watershed is determined by the area covered by
the canopies of all trees and shrubs.
Natural cover, expressed in hectares, or as a percentage of the overall watershed area, is the area
of the watershed covered by natural habitats including forests, meadows, and wetlands.
Natural cover includes habitats with varying degrees of trees and shrubs. Meadows for example
are open habitats that do not contain trees. Although meadows, and other non -treed habitats,
are natural cover, they are not part of the urban forest. Similarly, the urban forest includes trees
located within built portions of the watershed, outside of natural habitats. For these reasons,
the amount of natural cover and the amount of urban forest in a watershed will not be equal as
is the case of the Carruthers Creek Watershed.
See Figure 4 for a visual representation of this explanation.
25
0 WATER QUALITY: is impaired within the watershed,
requiring improvements to stormwater management.
The headwaters of Carruthers Creek contain elevated
concentrations of total phosphorus, phosphate, total
ammonia, E. coli, total suspended solids (TSS), turbidity,
and some trace metals. These elevated concentrations
in the headwaters were likely influenced by agricultural
practices and the construction of Highway 407. Just
upstream of urban development, concentrations were
reduced for most parameters except chloride. Chloride
levels regularly exceeded the threshold for the protection
of aquatic life in the reaches of Carruthers Creek with
urban influences. Additionally, increased concentrations
of total ammonia, nitrite, phosphate, turbidity, and trace
metals are often observed downstream of the urban area.
As expected, the concentrations of many water quality
parameters were elevated during high flow conditions
that occur during storm runoff and wet weather.
Prior to the 1980s, stormwater management focused
solely on flood control (stormwater quantity). Modern
stormwater management provides a higher level of
protection for the environment, property, and residents
by incorporating mitigation provisions for water quality,
erosion, and water balance in addition to water quantity
control. The Carruthers Creek watershed has various levels
of stormwater control that are indicative of the age of
development and the prevailing stormwater management
practices at the time.
26
0 NATURAL HAZARDS: the flow of water through
the watershed is out of balance and there are flooding
and erosion issues.
Urbanization converts formerly pervious surfaces (e.g.
forests, meadows, agricultural lands) to impervious surfaces
(e.g. roads, parking lots, rooftops). From 1999 to present day,
the increase in urban cover has greatly altered the natural
water balance. In addition, existing agricultural lands located
in the headwaters of the watershed are extensively tile
drained. Several sites with erosion issues were identified as
part of the fluvial geomorphic assessment.
During storm events, the increase in surface runoff
associated with impervious surfaces can result in excessive
riverine flooding and stream erosion. Currently, a Flood
Vulnerable Cluster (FVC) exists in the lower part of the
Carruthers Creek watershed in the Town of Ajax (see
Figure 2 or 5 for the location of this FVC). There have been
both historical and recent flooding events in the Carruthers
Creek watershed due to extreme precipitation events.
These four key issues provide the basis for the management
framework of this watershed plan, discussed in Section 5.
Table 2 summarizes benchmarks for the four key watershed
issues previously discussed. The benchmarks are important
reference points for understanding how watershed
conditions can change over time to evaluate success of this
watershed plan. Table 2 also identifies targets (or rating
scales) to show the ideal state of that particular watershed
component. The targets are informed by relevant TRCA
strategies, provincial or federal guidance, and established
conservation science. The scenario analysis, described
in Subsection 4.3, summarizes how the watershed will
respond to potential future scenarios in comparison to
the benchmarks. Section 6 uses indicators to evaluate the
success of implementation through a watershed monitoring
program. The indicators identified in Section 6 will track
watershed conditions relative to the benchmarks discussed
in Table 2. Where a monitoring station is referenced in
Table 2, see Figure 7 for the location of that monitoring
station within the watershed.
Carruthers Creek Watershed Plan
TABLE 2:
Current Watershed Conditions Benchmarks
Key Watershed Issues
Sub -Issue
Benchmarks
Targets (if applicable)
WATER RESOURCE
SYSTEM
Aquatic Health
Family Biotic Index (FBI)8- rating
of fairly poor and poor across
Carruthers Creek:
• Poor = 6.59 (Average from
2013 - 2017 at monitoring
station Aquatic 1)
• Fairly poor = 6.19 (Average
from 2013 - 2017 at
monitoring station Aquatic 2)
• Fairly poor = 6.07 (Average
from 2013 - 2017 at
monitoring station Aquatic 3)
Index of Biotic Integrity (181)9:
• Rating of poor at three sites
(2015)
Rating of fair at two sites (2015)
Rating of good at six sites (2015)
Rating scale for FBI:
Value
Rating
0 - 3.75
Excellent
3.76 - 4.25
Very good
4.26 - 5.00
Good
5.01 - 5.75
Fair
5.76 - 6.50
Fairly poor
6.51 - 7.25
Poor
7.26 -10
Very poor
Rating scale for IBI:
Value
Rating
38
Very good
28 - 37.9
Good
20 - 27.9
Fair
<_20 - 5.75
Poor
Riparian corridor
(30 m buffer
around streams)
Within the riparian corridor
natural cover is 49%.
75% of stream length is
naturally vegetated
Streamflow
(surface water)
Carruthers Creek at Achilles Road
had an average total volume of
1.14 x 10' m3 over the 2008 - 2016
period. This corresponds to a
discharge rate of 0.360 m3/s when
averaged on an annual basis.
Not applicable (should not
vary significantly from natural
fluctuations year to year)
Groundwater
Recharge
Average recharge rate is
estimated at 118 mm/year
Not applicable (should not
decrease significantly from
natural rates)
Groundwater
Discharge
Average discharge rate is
estimated at 130 mm/year
Not applicable (should not
decrease significantly from
natural rates)
'The Family Biotic Index is often used to assess the quality of water in rivers and is a scale for showing the quality of an environment by indicating the
types of organisms present in it.
'The Index of Biotic Integrity measures a chosen set of metrics (in this case number of fish species, presence of sensitive fish species, abundance and
food chain classifications) to assign a rating of very poor to excellent.
27
Key Watershed Issues
NATURAL
HERITAGE SYSTEM
WATER QUALITY
(SURFACE)
Water quality benchmarks
are based on average
concentration of 17 water
quality samples collected
monthly from June 2015
to May 2016.
28
Sub -Issue
Natural cover
Habitat quality
Animal (i.e.
fauna) species
of concern
Number and
area of sensitive
vegetation
communities
Tree and Shrub
Canopy (urban
forest)
Chlorides
Total suspended
solids
Benchmarks
Approximately 25% total natural
cover, consisting of 9% forest,
7% wetland, 4% successional
(transitioning to forest) and 3%
meadow.
Evaluated using Landscape
Analysis Model (LAM), which
assigns a score based on total
number of habitat patches,
patch size, patch shape, and
influences from surrounding land
uses. Overall patch quality in the
Carruthers Creek watershed was
found to be 'poor'.
North of Taunton Road = 39
South of Taunton Road = 56
Entire watershed number = 43
Area = approximately 54 hectares
Approximately 23% tree and
shrub canopy for the entire
watershed (2017).
• 183 mg/L at monitoring
station Water Quality 1
• 72 mg/L at monitoring station
Water Quality 2
• 35 mg/L at a no longer active
monitoring station that was
located west of Salem Road at
Hwy7
• 20 mg/L at monitoring station
Water Quality 1
• 11 mg/L at monitoring station
Water Quality 2
• 59 mg/L at a no longer active
monitoring station that was
located west of Salem Road at
Hwy7
Targets (if applicable)
Minimum 30% natural cover.
TRCA recommended NHS
for Carruthers Creek: 36%
natural cover; 16% forest,
7% wetland, 13% other
(primarily successional forest
and meadow)
Rating scale:
Patch Score
Quality
Condition
13-15
Excellent
11 - 12
Good
9-10
Fair
6-8
Poor
0-5
Very poor
Not applicable (ideally
maintained or improved)
Not applicable (ideally
maintained or improved)
Not applicable (targets
to be established
through management
recommendation 3.3.2)
The long-term water quality
guideline for the protection
of aquatic life (CCME) for
chlorides is 120 mg/L.
CCME water quality
guideline for TSS is based on
increases over background
levels. Monitoring results
show large fluctuations in
TSS in Carruthers Creek.
Key Watershed Issues
WATER QUALITY
(SURFACE)
cont'd
NATURAL
HAZARDS
Sub -Issue
E. coli
Total
phosphorus
Stormwater
management10
Peak flows
(flooding)
Flood vulnerable
roads and
structures
Benchmarks
• 706 CFU/100 ml at monitoring
station Water Quality 1
• 517 CFU/100 ml at monitoring
station Water Quality 2
• 475 CFU/100 ml at a no longer
active monitoring station that
was located west of Salem
Road at Hwy 7
• 0.044 mg/L at monitoring
station Water Quality 1
• 0.031 mg/L at monitoring
station Water Quality 2
• 0.091 mg/L at a no longer
active monitoring station that
was located west of Salem
Road at Hwy 7
As of 2003, approximately 64%
of the developed portion of
the watershed has stormwater
controls that meet TRCA criteria.
Of the remaining percentages,
29% have no stormwater controls
and 7% have water quantity
control only.
Regional Storm (i.e. Hurricane
Hazel)
• 71.61 m3/s at Taunton Road
• 140.52 m3/s at Shoal Point Road
5 -year Storm (i.e. 1 in 5
probability of flow being
exceeded in any one year)
• 7.27 m3/s at Taunton Road
• 11.00 m3/s at Shoal Point Road
Metres of impassable road
length affected:
• Average annual = 91 m
• Regulatory flood event = 2,532 m
Number of households affected:
• Average annual = 1
• Regulatory flood event = 89
Targets (if applicable)
CFU — Colony Forming Units.
Provincial Water Quality
Objective (PWQO) for E. coli is
100 CFU/100 ml. Averages for
Carruthers Creek exceed this
guideline.
PWQO to avoid excessive
plant growth in river and
stream concentrations below
0.03 mg/L. Averages for
Carruthers Creek exceed this
guideline.
Established by municipalities,
in collaboration with TRCA,
through stormwater master
planning and secondary
planning
Not applicable (peak flows
should not increase)
Not applicable (ideally a
reduction in vulnerable roads
and structures)
Notes: See Section 6 for map and description of monitoring station locations referenced in this table. Other surface water quality
parameters were characterized as part of TRCA's technical analysis, but only parameters of concern are included in this table.
10For the purposes of determining the current state of the watershed, stormwater management has been grouped with water quality. However, inadequate
stormwater management can also increase the frequency and duration of flooding (i.e. natural hazards) and impact aquatic habitat (i.e. WRS).
29
4. Future Watershed Conditions
An important part of watershed planning is assessing future conditions based on potential future
land use scenarios. The results of watershed characterization discussed in Section 3 were used
to inform the potential future land use scenarios discussed in this section. TRCA produced
peer-reviewed technical reports on different components of the watershed as part of scenario
analysis, which are referenced in Section 9.
4.1 FUTURE STRESSORS
To determine what land use scenarios to assess requires identifying potential future stressors on a
watershed. For Carruthers Creek, urbanization continues to drive land use change, converting natural
and agricultural areas to residential, commercial and industrial lands. This urbanization impacts the
health of a watershed largely through the loss of natural cover and increase in impermeable surfaces,
which alter the hydrologic regime. Despite some positive watershed management efforts to date
in Carruthers Creek, the watershed exhibits signs of stress due to the impacts of urbanization and
climate change. By 2041, the population of the Region of Durham is expected to nearly double from
682,000 to 1.2 million. Some of that growth will certainly be in the Carruthers Creek watershed.
30
Climate change is expected to increase precipitation,
annual average temperatures and the frequency
of extreme weather events, which will impact
watersheds within the Region of Durham. Some
of the implications of a changing climate include
localized flooding, violent storm damage, changes
to ecosystem composition, and changes to
agricultural conditions and production.
These stressors were evaluated as part of assessing
future watershed conditions. The management
framework in Section 5 of this watershed
plan recognizes these stressors by identifying
recommendations to mitigate potential future
watershed impacts.
4.2 FUTURE SCENARIOS
An effective way to assess how a watershed will
respond to potential future change is to develop,
analyze, and compare several alternate scenarios,
each reflecting a different composition of possible
land use conditions. In this way, land use scenario
analysis is used as a tool to compare how possible
future land uses might add to existing pressures on
the natural system, and how these pressures might
affect watershed health. Land use scenario analysis
is a technical exercise that is typically undertaken
when developing watershed plans to ensure
management recommendations are based on the
best available science. The results help guide the
development of management recommendations
and support municipalities in land use and
infrastructure planning decision-making.
Carruthers Creek Watershed Plan
Climate Change
Climate change was incorporated into the scenario
analysis for various technical components of this
watershed planning process, where possible.
For example, the terrestrial impact assessment
completed as part of the NHS planning specifically
incorporated climate change vulnerabilities as one
of its criteria for determining priority NHS sites.
The impacts of future climate change were factored
into potential stresses on the aquatic system as
part of that technical assessment. Additionally,
hydrologic modelling completed as part of this
watershed planning process incorporates storm
events considered to be more frequent under
climate change scenarios.
The management framework recognizes the
importance of climate change by prioritizing the
protection of the WRS and NHS, which can, if
properly protected and restored, improve climate
adaptation and increase ecosystem resilience.
The use of green infrastructure and low impact
development combined with improvements to
stormwater infrastructure are also important
management recommendations to adapt to a
changing climate.
TRCA, the Region of Durham, Town of Ajax and City
of Pickering all recognize the challenge of climate
change and have various strategies and action
plans to address this challenge, in addition to the
recommendations identified in this watershed
plan (e.g. Durham Community Climate Adaptation
Plan and Durham Community Climate Change Local
Action Plan).
Note:
Additional climate modelling is being completed for the
Region of Durham, in collaboration with conservation
authorities, that can be used to inform future watershed
or subwatershed studies.
31
Three potential future land use scenarios were developed and analyzed as part of this watershed planning process
to assess possible changes and impacts in both the built and natural environments. The year 2015 was used as the
baseline for this watershed planning process due to the availability of data sets at the initiation of this project.
It is worth noting that since 2015 was used as the baseline for scenario analysis, potential impacts from the extension
of Highway 407 (completed in 2016) through the headwaters of Carruthers Creek can only be assumed. Ongoing
monitoring of the Carruthers Creek watershed will help determine any potential changes to overall watershed health
arising from the construction of this highway infrastructure.
TABLE 3:
Potential Future Land Use Scenarios
Scenario 1
(+Official Plan)
This scenario assumes that all lands south of the Greenbelt are developed up to 2031
based on approved Official Plans. This scenario included municipally designated NHS's
that were part of Official Plans.
This scenario provides insight into how watershed conditions will likely change as
approved Official Plans are implemented.
This scenario assumes the same development as Scenario 1 but includes the enhanced
NHS (i.e. potential natural cover).
Scenario 2
New and updated information from natural heritage science and practice was
incorporated to identify potential areas for natural cover that would improve
(+NHS)
ecosystem functions and services in the future.
This scenario provides insights into how watershed conditions will likely change with
increased consideration of additional natural cover.
This scenario assumes post -2031 development in the headwaters of Carruthers Creek
Scenario 3
(north of the Greenbelt), outside the enhanced NHS.
(+Potential Urban)
This scenario provides insights into how watershed conditions will likely change if
potential full growth is approved in the watershed.
See Figure 5 for representative maps of each scenario.
32
6
1
4
Scenario 3
a
krona and Region
onserva Lion
Authprli
Date: September 2019
Created by: TRCA Information Services/Information Technologies
Disclaimer:
The Data used to create this map was compiled from a variety sources
and dates. The TRCA takes no responsibility for errors or omissions
in the data and retains the right to make changes and corrections
at anytime without notice. For further information about the
data on this map, please contact the TRCA
GIS Department. (416) 661-6600.
Carruthers Creek
Watershed Plan:
Future Scenarios 1-3
0 0.5 1 2 3
KM
Municipal Boundary
�r Watercourse
Land Use
dir Natural
Rural
Urban
Flood Vulnerable
Cluster
Greenbelt Boundary
Carruthers Creek
Watershed Boundary
Carruthers Creek
Watershed Plan
Study Area
33
4.3 SCENARIO ANALYSIS
As part of this watershed planning process, key
components of watershed health were assessed using the
previously discussed three future scenarios.
The results of these scenario analyses were used to:
O Understand the implications of each scenario on
overall watershed health and integrity
O Develop the management framework for this
Carruthers Creek Watershed Plan, which can be
used to inform land use and infrastructure
decisions
It is important to note that scenario analysis does not
result in decisions about the type and configuration
of land uses. Instead, scenario analysis helps to
inform decisions through the municipal planning
process (e.g. Official Plans).
It is the responsibility of the applicable municipality
to determine the ultimate land use configuration for
any future changes within the watershed.
34
Table 4 explains the implications of the three potential
future scenarios for each of the key watershed issues
as identified in Subsection 3.3. Based on the technical
assessments completed as part of this watershed
planning process, Table 4 identifies whether the
watershed responds positively (conditions improve),
neutrally (conditions remain the same), or negatively
(conditions deteriorate) to the potential future scenario
in comparison to the identified benchmark.
The colour coding in Table 4 indicates the severity of how
the watershed component reacts:
GREEN UP ARROW: >+5% change
At indicates watershed conditions improve from a
hydrologic or ecological perspective
EQUAL SIGN: 0 to +5% or 0 to -5% change
indicates a roughly equal comparison from a hydrologic
or ecological perspective
' YELLOW DOWN ARROW: -6% to -10% change
indicates watershed conditions deteriorate from a
hydrologic or ecological perspective
PURPLE DOWN ARROW: >-10%change
11 indicates watershed conditions significantly
deteriorate from a hydrologic or ecological perspective
The changes identified in Table 4 are calculated by
comparing scenario 1 to the current conditions, whereas
scenarios 2 and 3 are compared to scenario 1. Since
scenario 1 represents the currently approved Official
Plan, it represents a future scenario that will occur,
therefore it is more realistic to compare scenarios 2 and
3 to scenario 1. Some of the scenario analysis technical
reports referenced in Section 9 compare the three future
scenarios to current conditions. The numbers identified
in Table 4 have been adapted accordingly to compare
scenarios 2 and 3 to scenario 1.
TABLE 4:
Scenario Analysis Implications
WATER RESOURCE SYSTEM"
Carruthers Creek Watershed Plan
Includes: the features and areas of the WRS, including aquatic habitat, and their functions. Percent change is based
on changes to impervious cover mentioned under aquatic health. Impervious cover is a critical measure of various
factors12 that impact aquatic health.
See Figure 9 in Section 7 for an illustration of subwatershed quality.
CURRENT CONDITIONS
SCENARIO 1 (+OP) SCENARIO 2 (+NHS)
(From subsection 3.313) (Compared to Current Conditions) (Compared to Scenario 1)
SCENARIO 3
(+POTENTIAL URBAN)
(Compared to Scenario 1)
% change
-6%
+1%
♦-12%
Aquatic Health
Subwatershed quality:
NW and NE good - fair;
central and south fair - poor
Impervious cover at 24%
across the watershed
Subwatershed quality:
no change from current
conditions
Impervious cover at 30%
across the watershed
Subwatershed quality:
NW shows improvement to
good
Impervious cover at 29%
across the watershed
Subwatershed quality:
all four have fair - poor
conditions
Impervious cover at 42%
across the watershed
Riparian corridor (30 m buffer along streams)
49% natural cover along
the corridor
50% natural cover along
the corridor
65% natural cover along the
corridor
65% natural cover along the
corridor
Streamflow (average surface water discharge)
0.52 m3/s
201 mm/year
152 mm/year
0.53 m3/s
0.53 m3/s
Groundwater discharge (average rate)
197 mm/year
201 mm/year
Groundwater recharge (average rate)
147 mm/year
152 mm/year
0.56 m3/s
194 mm/year
141 mm/year
"This assessment does not consider protection measures for the WRS. For example, if impervious surfaces were minimized in groundwater recharge areas,
hydrologic function would be maintained.
1'These factors include channel stability, water quality, stream biodiversity and natural flow. See the Aquatic Impact Assessment technical report for more
information.
13The numbers for streamflow, groundwater discharge and recharge are different in table 4 from table 2 due to models used for the scenario analysis.
35
NATURAL HERITAGE SYSTEM
Includes: the the features and areas of the NHS, including terrestrial habitat and their functions. Percent change is
based on an equally weighted average of the total natural cover and habitat quality values.
CURRENT CONDITIONS
SCENARIO 1 (-i-OP) SCENARIO 2 (+NHS)
(From subsection 3.3) (Compared to Current Conditions) (Compared to Scenario 1)
SCENARIO 3
(+POTENTIAL URBAN)
(Compared to Scenario 1)
% change
25% natural cover
7.6
+1 %
♦+7%
14 G
Alk +6%
Total natural cover
25% natural cover
36% natural cover
Habitat quality (average LAM15 score)
7.5
7.9
IlkHabitat connectivity (regional at watershed-scale)16
28%
28%
45%
36% natural cover
7.6
45%
Climate vulnerabilities (average of five high vulnerabilities indicators)17
51% 51%
55%
55%
"While habitat quantity (as represented by natural cover) increases under scenario 3 relative to scenario 1, the habitat quality results require a caveat. LAM scores
are an equally rated average of patch size, shape and matrix influence. Under scenario 2, the matrix influence score increases threefold from scenario 1,
indicating improved habitat quality. Under scenario 3, the matrix influence score decreases, indicating decrease in habitat quality. So, while patch size and
shape increase under scenarios 2 and 3, scenario 3 negatively affects the matrix influence of habitat quality.
15These LAM scores, known as Landscape Analysis Model, combines the metrics of patch size (larger patches support larger populations), patch shape (habitat
fragmentation) and matrix influence (influence of surrounding land uses). A LAM score of 6 — 8 = poor. See the Terrestrial Impact Assessment technical report for
more information.
16Habitat connectivity values represent the percentage of area for connectivity priorities that overlap with the proposed enhanced NHS. Improved connectivity has
benefits for habitat quantity and quality. In other words, higher percentages indicate more habitat connectivity corridors.
17The average high vulnerability indicators are ground surface temperature, climate sensitive community, habitat patch quality, soil drainage and wetlands. The
climate vulnerabilities values represent the percentage of climate vulnerable features represented in the proposed enhanced NHS. A higher percentage indicates
more habitat included in the system, and therefore, if protected, improved resiliency to climate change.
Carruthers Creek Watershed Plan
WATER QUALITY'$
Focused on parameters of concern associated with urbanization and agricultural land uses. Amounts are based on a
comparison of 2005 to 2015 average flow.
CURRENT CONDITIONS
SCENARIO 1 (+OP) SCENARIO 2 (+NHS)
(From subsection 3.3) (Compared to Current Conditions) (Compared to Scenario 1)
SCENARIO 3
(+POTENTIAL URBAN)
(Compared to Scenario 1)
% change -*
It is difficult to draw a conclusion on the percent change for water quality solely. As mentioned
in the WRS row of this table, water quality is one of the factors considered under the impacts of
impervious cover. Of the parameters of concern identified in Table 2, TSS and total phosphorus
were assessed as part of scenario analysis.
Total Suspended Solids"
4,602 tonnes
4,674 tonnes
4,641 tonnes
4,939 tonnes
Total Phosphorus20
9,843 tonnes : 9,864 tonnes
9,295 tonnes
8,602 tonnes
'aStream water quality in urbanized watersheds is generally degraded by increased turbidity, nutrients, metals, E. coli and other contaminants due to more
impervious surfaces and increased runoff. See the Aquatic Impact Assessment technical report for more information.
"Table 2 in Subsection 3.3 identified T55 readings at three monitoring stations in mg/L. For the purposes of scenario analysis, TSS was measured in tonnes at the
outlet of the watershed (i.e. where it drains into Lake Ontario).
2OTable 2 in Subsection 3.3 identified total phosphorus readings at three monitoring stations in mg/L. For the purposes of scenario analysis, total phosphorus was
measured in tonnes at the outlet of the watershed (i.e. where it drains into Lake Ontario).
,1111999
•
NATURAL HAZARDS
(Flooding and Erosion)
Focused on flood modelling as measured by peak flows21. Percent change is based on an average from both locations
for the regional storm only (as the worst-case scenario).
CURRENT CONDITIONS
SCENARIO 1 (+OP) SCENARIO 2 (+NHS)
(From subsection 3.3) (Compared to Current Conditions) (Compared to Scenario 1)
SCENARIO 3
(+POTENTIAL URBAN)
(Compared to Scenario 1)
% change
-2%
0%
22
-77%
Regional Storm (i.e. Hurricane Hazel)
71.61 m3/s
at Taunton Road
69.90 m3/s
at Taunton Road
68.59 m3/s
at Taunton Road
148.84 m3/s
at Taunton Road
140.52 m3/s
at Shoal Point Road
149.50 m3/s
at Shoal Point Road
147.19 m3/s
at Shoal Point Road
210.63 m3/s
at Shoal Point Road
5 -year Storm (i.e. 1 in 5 probability of flow being exceeded in any one year)
7.27 m3/s
at Taunton Road
7.18 m3/s
at Taunton Road
6.58 m3/s
at Taunton Road
6.80 m3/s
at Taunton Road
11.00 m3/s
at Shoal Point Road
11.71 m3/s
at Shoal Point Road
11.11 m3/s
at Shoal Point Road
11.83 m3/s
at Shoal Point Road
21 Peak flows are the maximum rate of discharge during the period of runoff caused by a storm. Potential erosion issues were not assessed. However, erosion is
likely to be worse with increased peak flows.
22The flood modelling completed as part of scenario analysis did not factor in potential mitigation measures (e.g. modern stormwater infrastructure).
11
INP, • • , • , • , • ,
Carruthers Creek Watershed Plan
Table 4 illustrates expected changes to watershed conditions based on available information and
assessments conducted as part of this watershed planning process. The management framework
in Section 5 identifies what is necessary to protect, enhance and restore watershed conditions. It
also identifies management recommendations to encourage more sustainable land uses.
Summary of implications:
• One of the four subwatersheds shows improved aquatic conditions under scenario 2. Conversely,
all four subwatersheds have fair — poor aquatic conditions under scenario 3, likely resulting in the
loss of Redside Dace, a listed endangered species, within the Carruthers Creek watershed.
• The amount of natural cover and habitat quality improves under scenario 2. Under scenario 3, the
amount of natural cover improves, while habitat quality decreases compared to scenario 2 due to
the influence of surrounding urban development.
• Water quality is currently impaired in the watershed for parameters like chloride, phosphorus, TSS
and E. coli. Without improvements to land use practices, salt and stormwater management, water
quality is likely to continue to deteriorate with increased urbanization (scenario 3).
• There are existing flooding issues in the watershed, which will significantly increase under scenario 3
without the implementation of considerable mitigation measures. The hydrologic assessment
shows a reduction in peak flows associated with the recommended NHS for smaller design storms
(i.e. 2 -year storm).
These hypothetical future scenarios are illustrative of potential watershed conditions. In addition
to the summary of implications, it is important to recognize the following:
• Protecting, enhancing and restoring the recommended NHS provides vital watershed benefits as
illustrated by Scenario 2 and is consistent with targets as identified in Table 2.
• Limiting impervious cover in any potential future growth areas, or through redevelopments,
provides significant benefits to aquatic biodiversity. Federal guidance recommends urbanizing
watersheds maintain less than 10% impervious land cover, while already degraded urban systems
should not exceed a second threshold of 25 to 30%. Scenario 1 shows impervious cover reaching
this 30% threshold with only a marginal improvement to 29% under Scenario 2. See Figure 9 in
Section 7 for more information.
The management framework developed as part of this watershed plan contains recommendations
to improve watershed conditions regardless of potential future land use decisions. The management
39
5. Management Framework
The management framework for the Carruthers Creek Watershed Plan represents what needs to be
done to protect, enhance and restore watershed health23. The management framework consists of
goals, objectives, indicators and management recommendations.
TRCA developed this management framework in collaboration with its municipal partners and
refined it based on feedback from stakeholders and the public.
The goals, objectives and management recommendations were developed to address the issues
identified through watershed characterization and account for potential different future land use
scenarios. Many of the management recommendations are expected to mitigate many of the potential
impacts associated with potential land use changes, as identified through the scenario analysis.
Each of the goals are complementary, with no one goal being more important than another. To
fully realize the vision for Carruthers Creek will require the implementation of each goal area.
Management recommendations were grouped under the most appropriate objective and are also
listed in no particular order.
Any recommendations contained in the scenario analysis technical reports are consolidated in this
management framework. Refer to the technical reports for detailed methodologies and findings
beyond what was summarized in Sections 3 and 4. This watershed plan is the final source for goals,
objectives, indicators and management recommendations related to Carruthers Creek. Readers are
encouraged to refer to the technical reports for more detailed implementation suggestions.
23As mentioned in Subsection 1.1, the CTC Source Protection Plan also applies in the Carruthers Creek watershed and includes policies
to protect drinking water. Implementation of this Source Protection Plan is required under the Clean Water Act, 2006. Consideration of
Great Lakes agreements and legislation is also important for effective watershed management. These requirements are in addition to,
and complementary of, the management framework identified in this watershed plan.
40
Carruthers Creek Watershed Plan
TABLE 5:
Management Framework Explanation
Management Framework
Components
Description
GOALS
Represent the outcomes to achieve.
OBJECTIVES
Are the specific statements about desired results, or steps to be undertaken, to
achieve the goal.
INDICATORS
Explain how progress on implementing the objective is going to be tracked
or measured. Some indicators are compared to the benchmarks identified in
Table 2. Other indicators are about reporting on implementation progress
as it relates to policies, best practices, or infrastructure improvements and do
not have an associated benchmark in Table 2. Where applicable, the targets
identified in Table 2 can be used as a measure to achieve.
MANAGEMENT
RECOMMENDATIONS
Specifically explain what should be done to accomplish the relevant objective.
The management framework consists of three goals,
nine objectives and 11 indicators (see Figure 6). The
management recommendations for each goal area are
described in Subsections 5.1 — 5.3.
The management recommendations apply to the
entire watershed; identifying opportunities to improve
conditions in the developed portion of the watershed
and the types of studies and best practices that should
be utilized for any potential future development,
or redevelopment. Subsection 5.4 summarizes
recommendations that would specifically apply to any
potential Settlement Area Boundary Expansion in the
headwaters of Carruthers Creek.
41
FIGURE 6:
Overview of Management Framework
Land Use
Achieve sustainable land use
and infrastructure development
patterns to protect, enhance
and restore water quality and
maintain stable water balance.
11111
111!21Il1
GOAL 2
ISI
OBJECTIVE 1
Minimize the impacts of land uses
through sustainability policies and the
use of low impact development and
green infrastructure.
Indicators:
Report on implementation of sustainable
development policies/standards
OBJECTIVE 2
Install and upgrade stormwater
infrastructure using best available
technologies to reduce runoff; resulting in
improved water balance and water quality.
Indicators:
Report on the status of stormwater
management
OBJECTIVE 3
Manage the risks of natural hazards
through appropriate mitigation
measures and restoration.
Indicators:
Reduce number of flood vulnerable
structures and roads
OBJECTIVE 4
Encourage the use of agricultural best
management practices to minimize
agricultural runoff and improve rural
land stewardship.
Indicators:
Work with the agricultural community
to track implementation of best
management practices
Water Resource System
Protect, enhance and restore the
areas and features that make up the
Water Resource System (including
aquatic habitat) for ecosytem
resilience and sustainabilty.
OBJECTIVE 1
Implement appropriate policies and
programs that protect, enhance and
restore the areas and features that
comprise the Water Resource System.
Indicator:
Appropriate policy designations are in
place for the Water Resourse System
OBJECTIVE 2
Promote aquatic habitat connectivity
to faciltate native fish movement
throughout the watershed.
Indicator:
Maintain, or improve, aquatic health
rankings
0410 rIIP
4110
dr
Natural Heritage System
Protect, enhance and restore the
Natural Heritage System and urban
forest within the watershed to
improve ecosystem resilience and
sustainability.
42
OBJECTIVE 1
Improve the quality and quantity of
the Natural Heritage System across
the watershed through ecosystem
protection, enhancement and
restoration, and implementation of
relevant policies.
Indicators:
Increase total natural cover in the
watershed
OBJECTIVE 2
Ensure habitat exists for native terrestrial
species to thrive throughout the watershed.
Indicators:
Maintain, or increase, the number
and area of species and vegetation
communities of concern
OBJECTIVE 3
Increase the urban forest cover within the
developed portion of the watershed to
improve social and environmental well-being.
Indicator:
111110,111)
Increase total tree canopy in the watershed
Appropriate policy designations are in
place for the Natural Heritage System
Carruthers Creek Watershed Plan
5.1 LAND USE / INFRASTRUCTURE GOAL
GOAL 1
Achieve sustainable land use and infrastructure development patterns to protect, enhance and restore water
quality and maintain stable water balance.
This goal area focuses on the policy, land use and infrastructure planning processes that influence the health of
the watershed. The management recommendations are numbered to correspond with their applicable goal
and objective.
TABLE 6:
Land Use Management Recommendations
43
LAND USE
OBJECTIVE 1
Minimize the impacts of land
uses through sustainability
policies and the use of low
impact development and green
infrastructure.
1.1.1
Lower -tier municipalities, in collaboration with the Region of Durham and
TRCA, to adopt green development policies, or standards, and require new
developments, and re -developments, to utilize low impact development and
green infrastructure techniques to limit the impacts of increased impervious
cover. The following should apply to any municipal policies, or standards, in
particular within ESGRAs, as identified on map lb:
a. new developments should minimize impervious cover and strive to
achieve 90th percentile volume control of annual rainfall
b. redevelopments should minimize impervious cover and strive to
achieve 75th percentile volume control of annual rainfall
1.1.2
The Region of Durham and lower -tier municipalities, in collaboration with
TRCA, to develop mechanisms to track and report on implementation of
sustainable development practices to assess the effectiveness of policies and
standards.
1.1.3
If it is determined that a Settlement Area Boundary Expansion is required in
the headwaters of Carruthers Creek, in accordance with Growth Plan policies,
the Region of Durham, in collaboration with lower -tier municipalities and
TRCA, to develop a Terms of Reference outlining requirements for further
studies in support of subwatershed planning that includes, but is not limited to:
43
1
LAND USE
OBJECTIVE 1
cont'd
a. a hydraulic assessment
b. how natural hazards will be assessed and mitigated (i.e. the risk of
flooding will not increase)
c. how the Natural Heritage System and Water Resource System will be
protected, enhanced and restored
d. how water quality and quantity will be protected.
1.1.4
During planning for transportation infrastructure improvement projects,
or new projects, the Region of Durham and lower -tier municipalities
to implement best management practices for design, expansions and
widenings in accordance with TRCA's Crossing Guideline for Valley and
Stream Corridors, and ensure consistent policies and standards are in
place to facilitate hydraulic function (e.g. prevent flooding) and ecological
connectivity (e.g. wildlife passage). See map 3 for priority crossings.
1.1.5
Lower -tier municipalities to improve the management of excess soils and
prevent fill deposition that is incompatible with the soils and hydrology of
the area by:
a. ensuring adequate policies and bylaws are in place to manage
excess soil
b. improving compliance and enforcement of policies through
collaboration between TRCA and municipalities
c. conducting education and outreach on:
i. the importance of proper soil management
ii. existing regulatory requirements
iii. regulatory responsibilities of various agencies, including who to
contact with concerns.
d. collaborating with agencies and other levels of government, including
the Region of Durham, to ensure infrastructure projects that generate,
or receive excess soil follow best management practices.
1.1.6
The Region of Durham and lower -tier municipalities, in collaboration with
other levels of government and TRCA, to work to reduce the amount of
chlorides entering the watershed by:
a. continuing to implement best management practices for winter
de-icing procedures on public property
b. continuing education and outreach on salt management for
private property.
1.1.7
TRCA, in collaboration with the Town of Ajax, to identify and promote
opportunities for sustainable community retrofits in priority planting
neighbourhoods (See map 8).
44
45
Land Use Objective
LAND USE
OBJECTIVE 2
Install and upgrade stormwater
infrastructure using best
available technologies to reduce
runoff; resulting in improved
water balance and water quality.
1.2.1
Lower -tier municipalities, in collaboration with the Region of Durham and
TRCA, through stormwater master planning continue to:
a. employ best management practices for stormwater management and
consistent design criteria to manage runoff quantity and quality
b. consider stormwater funding options for cost recovery and to reduce
impervious surfaces in the watershed
c. examine opportunities to retrofit outdated stormwater infrastructure
and install stormwater controls in areas without controls through
long-term planning and investment strategies
d. refine existing policies to ensure modern stormwater controls are required
e. adaptively manage stormwater infrastructure through operation
maintenance schedules and procedures.
1.2.2
Lower -tier municipalities, in collaboration with the Region of Durham and
TRCA, to develop mechanisms to track the status and effectiveness of
stormwater management infrastructure.
1.2.3
Lower -tier municipalities to explore opportunities to enhance stormwater
management in neighbourhoods with outdated or no stormwater facilities
by retrofitting infrastructure to meet modern stormwater design criteria,
as much as possible, given site characteristics.
1.2.4
For new developments, lower -tier municipalities to require hydrologic
analysis and erosion threshold assessments downstream of potential
stormwater management facilities that need to demonstrate no negative, or
adverse, downstream impacts, prior to municipal approvals.
LAND USE
OBJECTIVE 3
Manage the risks of natural
hazards through appropriate
mitigation measures and
restoration.
1.3.1
TRCA, in collaboration with lower -tier municipalities, to prioritize the
restoration of the erosion hazard sites identified on map 4. Additional
channel restoration, or increased stream bank protection may be required as
preventative measures in areas downstream of new developments.
1.3.2
The Region of Durham and lower -tier municipalities, in collaboration
with TRCA, to identify potential hazard risks to sewer and existing road
infrastructure associated with in -stream creek erosion and implement
strategies to eliminate identified risks.
45
46
Land Use Objective
LAND USE
OBJECTIVE 3
cont'd
1.3.3
Implement appropriate flood mitigation measures for the Flood Vulnerable
Cluster in the Town of Ajax, which could involve:
a. reopening, or initiating, a new environmental assessment to provide
a more comprehensive list of alternatives to offset impacts associated
with potential development in the headwaters
b. the application of regional control in the headwaters of Carruthers
Creek, if developed, and required by the updated flood modelling
(see management recommendation 1.3.5).
1.3.4
TRCA, in collaboration with the Region of Durham and lower-tier
municipalities, to educate property owners in high flood risk areas about
proper lot level practices (e.g. removing hydraulic impairments).
1.3.5
TRCA to complete comprehensive floodplain mapping based on new models
and best available information to inform land use and infrastructure decisions.
LAND USE
OBJECTIVE 4
Encourage the use of agricultural
best management practices to
minimize agricultural runoff and
improve rural land stewardship.
1.4.1
In collaboration with the agricultural community and provincial ministries,
TRCA, the Region of Durham and lower-tier municipalities to identify
opportunities to expand best management practices that reduce agricultural
runoff and improve water management, such as:
a. use cover crops and / or leave crop residue
b. adopt no till farm practices during non-growing season
c. conduct soil testing for nutrients and adjust fertilizer application rates,
if required.
1.4.2
In collaboration with the agricultural community, rural land owners,
and provincial ministries, TRCA, the Region of Durham and lower-tier
municipalities to identify opportunities to improve rural land stewardship
best management practices through:
a. natural buffers between agricultural lands and natural and / or water
resource features and areas
b. implementation of Environmental Farm Plans and other rural land
stewardship programs (e.g. TRCA's Rural Clean Water Programs)
c. education / outreach about the benefits of utilizing best management
practices to improve habitat (e.g. meadows for sensitive bird species).
46
Carruthers Creek Watershed Plan
5.2 WATER RESOURCE SYSTEM GOAL
GOAL 2
Protect, enhance and restore the areas and features that make up the Water Resource System (including aquatic
habitat) for ecosystem resilience and sustainability.
This goal area focuses on ensuring policies are in place for the long-term protection of the WRS and undertaking priority
restoration initiatives to benefit the long-term resiliency of the WRS. The WRS is presented in map 1A and map 1 B. The
areas and features that comprise the WRS are to be protected in accordance with the recommendations laid out in this
subsection.
TABLE 7:
WRS Management Recommendations
WRS Objective
Management Recommendations
WRS
OBJECTIVE 1
Implement appropriate policies
and programs that protect,
enhance and restore the areas
and features that comprise the
Water Resource System.
2.1.1
The Region of Durham and lower -tier municipalities, in collaboration with
TRCA, to ensure the protection of the Water Resource System (map 1A and B)
and its functions, by:
a. updating Official Plans and zoning bylaws to adequately protect the
Water Resource System
b. assessing existing standards and guidelines for land use and
infrastructure development to ensure they reflect current provincial
policy direction to protect, enhance and restore the quality and
quantity of water
c. avoiding development near key hydrologic features through the
establishment of appropriate buffers
d. requiring the implementation of appropriate mitigation measures
where avoidance of key hydrologic areas is not possible, in order to
maintain hydrologic function
2.1.2
TRCA, in collaboration with the Region of Durham and lower -tier
municipalities, to routinely update mapping data layers for all components of
the Water Resource System as new information becomes available.
47
WRS Objective
Management Recommendations
WRS
OBJECTIVE 1
cont'd
2.1.3
TRCA, in collaboration with the Region of Durham and lower -tier
municipalities, to prioritize the restoration of the aquatic sites identified on
map 4, which have been selected for contributing to the following:
a. enhancing habitat quality and watershed connectivity
b. ensuring biodiversity persists
c. improving watershed resiliency to climate change.
2.1.4
If it is determined that a Settlement Area Boundary Expansion is required in
the headwaters of Carruthers Creek, in accordance with Growth Plan policies,
the City of Pickering, in collaboration with the Region of Durham, Town of
Ajax and TRCA, as part of secondary planning to demonstrate through a
subwatershed plan (or equivalent) that:
a. key hydrologic features will be protected
b. where avoidance of key hydrologic areas is not possible, appropriate
mitigation measures are to be implemented to maintain downstream
hydrologic function, and
c. there will be no negative or adverse downstream effects, such as
increased flooding, erosion, or deteriorated water quality.
WRS
OBJECTIVE 2
Promote aquatic habitat
connectivity to facilitate native
fish movement throughout the
watershed.
2.2.1
TRCA, in collaboration with the Region of Durham and lower -tier
municipalities and landowners, to remove the six priority barriers to fish
movement identified in map 5.
2.2.2
TRCA, through its application review function, to identify and implement
avoidance, conservation, design and mitigation measures for the protection
and / or recovery of native aquatic species, including Redside Dace and its
habitat. For activities that affect Redside Dace habitat, consult the Guidance
for Development Activities in Redside Dace Protected Habitat (MNRF 2016),
MECP and DFO to determine requirements under species at risk legislation.
48
Carruthers Creek Watershed Plan
5.3 NATURAL HERITAGE SYSTEM GOAL
Protect, enhance and restore the Natural Heritage System and urban forest within the watershed to improve
ecosystem resilience and sustainability.
This goal area focuses on improving the quality and quantity of natural systems throughout the watershed. The proposed
enhanced NHS identified on map 2 is recommended by TRCA to achieve this goal. It will be up to municipalities to adopt
a NHS that is consistent with provincial policy and informed by the goals and objectives of the CCWP. The proposed
enhanced NHS includes areas with existing natural cover and areas that are targeted to be potential natural cover
through restoration. The exact configuration and size of the NHS could fluctuate due to other factors (e.g. construction
of infrastructure), assuming the analysis is comparable to the one that resulted in the proposed enhanced NHS
recommended by TRCA. The recommended NHS is designed to move towards the minimum target for natural cover
in an urban and urbanizing watershed as established in TRCA's Terrestrial Natural Heritage System Strategy (2007) and
How Much Habitat is Enough? (Environment and Climate Change Canada, 2013). Assuming that the identified potential
natural cover areas are restored, the recommended NHS achieves approximately 36% natural cover across the watershed,
including approximately 25% forests and successional forests and 7% wetlands, consistent with the minimum targets.
A large amount of the land recommended for potential natural cover occurs in the headwaters of Carruthers Creek. If
development proceeds in this area, it will be essential to restore and protect (i.e. through securement) an amount of land
consistent with the recommended NHS.
To appropriately implement a NHS will require updates to municipal Official Plans, which can then guide future land use
decisions to avoid development in the municipally adopted NHS, mitigate any impacts or, where impacts are unavoidable,
provide ecosystem compensation. The management recommendations related to the NHS in this subsection are
consistent with TRCA's protection hierarchy of avoid, minimize, mitigate and as a last resort compensate.
Urban forests provide valuable terrestrial habitat, help manage stormwater, provide clean air and other socio-economic
benefits (e.g. regulates local temperatures, improves personal well-being). Including urban forestry under this NHS goal
recognizes the integrated nature of natural areas (i.e. NHS) and the ecological value of additional natural cover in parks,
on streets, or private property (i.e. urban forests).
49
TABLE 8:
NHS Management Recommendations
Ilimiii
NHS
OBJECTIVE 1
Improve the quality and
quantity of the Natural Heritage
System across the watershed
through ecosystem protection,
enhancement and restoration,
and implementation of relevant
policies.
3.1.1
The Region of Durham and lower -tier municipalities, in collaboration with
TRCA, to ensure the protection, enhancement and restoration of a Natural
Heritage System consistent with the goals and objectives of this watershed
plan (map 2 for recommended NHS) by:
a. updating Official Plan policies and associated zoning bylaws to protect
a municipally adopted enhanced Natural Heritage System
b. assessing existing standards and guidelines for land use and
infrastructure development to ensure they reflect current provincial
policy direction to maintain, restore or enhance the municipally
adopted Natural Heritage System
c. avoid infrastructure development (i.e. buildings and structures) and
minimize infrastructure linear feature crossings, in a municipally
adopted enhanced Natural Heritage System
d. adopting municipal policies for ecosystem compensation, in accordance
with TRCA's Guideline for Ecosystem Compensation, where
development in a municipally adopted enhanced Natural Heritage
System is unavoidable
e. applying a minimum 30 metre vegetation protection zone along
features at the boundary of a municipally adopted enhanced Natural
Heritage System to protect ecological function
f. requiring development and redevelopments be designed and
approved to prevent encroachment into a municipally adopted
enhanced Natural Heritage System.
3.1.2
TRCA, in collaboration with the Region of Durham and lower -tier
municipalities, to prioritize the restoration of the terrestrial sites identified on
map 4, which have been selected for contributing to the following:
a. increasing habitat quantity
b. enhancing habitat quality and connectivity
c. ensuring biodiversity persists
d. adapting for climate vulnerabilities.
3.1.3
TRCA, in collaboration with the Region of Durham and lower -tier
municipalities, to explore opportunities to secure the sites identified on
map 6 for ecological protection and to increase public land ownership and
connectivity along the main channel of Carruthers Creek south of Taunton
Road.
50
Carruthers Creek Watershed Plan
NHS Objective Management Recommendations
NHS
OBJECTIVE 1
cont'd
3.1.4
TRCA, the Region of Durham and lower -tier municipalities to regularly update
their trail guidelines and standards for consistency, and to ensure that any new,
or modifications to existing trails, use best practices, such as prioritizing the use
of boardwalks in sensitive areas (e.g. wetlands), and implementing methods
to ensure trail users stay on marked trails (e.g. signage, barriers to humans and
dogs, but not other species, and limited access during breeding season).
3.1.5
TRCA, in collaboration with the Region of Durham and lower -tier
municipalities, to minimize impacts to the municipally adopted Natural
Heritage System from any active recreation and human activity by:
a. ensuring proper trail management and signage
b. providing education and outreach on the importance of the municipally
adopted Natural Heritage System
c. promoting community stewardship to maintain and monitor the
municipally adopted Natural Heritage System for improper trail usage
(e.g. off -trail compaction and erosion), illegal dumping and invasive
species, while encouraging community restoration programs (e.g. tree
plantings).
3.1.6
Wetland water balance studies that demonstrate how the hydrological
function of the wetland should be protected will be undertaken by the
landowner for any potential future growth in the areas identified on map 7,
or other areas identified during subwatershed planning, prior to applicable
planning approvals.
NHS
OBJECTIVE 2
Promote terrestrial habitat
connectivity to ensure native
species thrive throughout the
watershed.
3.2.1
The Region of Durham, lower -tier municipalities, TRCA, landowners and
other agencies will collaborate to manage problematic invasive species.
3.2.2
TRCA will continue to work with landowners to restore meadow habitat
areas in support of open country bird species at risk, in accordance with the
terrestrial restoration priorities identified on map 4.
51
NHS Objective
NHS
3.3.1
OBJECTIVE 3
Lower -tier municipalities, in collaboration with the Region of Durham and
TRCA, to update existing urban forest studies and consolidate them into a
Increase the urban forest cover
comprehensive study that:
within the developed portion of
a. accounts for all public and private lands
the watershed to improve social
b. develops targets for public and private lands for inclusion in an urban
and environmental well-being.
forest strategy
c. develops indicators for the quality and quantity of the urban forest for
inclusion in an urban forest strategy.
3.3.2
The Region of Durham and lower -tier municipalities, in collaboration with
TRCA, to develop a comprehensive urban forest strategy that:
a. enhances tree and soil conservation in accordance with Preserving
and Restoring Healthy Soil: Best Practices for Urban Construction at any
new development, or redevelopment, (e.g. Carruthers Creek Business
Area), and on regional property (e.g. along Taunton Road) as depicted
on map 8
b. focuses urban forest tree planting programs in the Town of Ajax as
depicted on map 8
c. encourages an urban forest with diverse and native (or non-invasive)
tree species and class sizes
d. ensures consistent policies and bylaws for tree conservation on public
and private lands
e. explores opportunities to increase the capacity of the Region of
Durham to implement an Urban Forest Strategy consistent with this
management recommendation
f. encourages participation in knowledge -sharing and collaboration
through the Regional Public Works Commissioners of Ontario's Urban
Forestry Sub -working Group and Ontario's Municipal Arborist and
Urban Foresters Association
g. includes urban forest targets for existing developed areas and any
future development as part of the strategy.
52
•
44.00
4
+.7 • .F '' `5 i l:y' •'.fii 4j#moi94.
s
—�c
5.4 CARRUTHERS CREEK HEADWATERS MANAGEMENT
There are several management recommendations that refer to potential future studies, subwatershed planning, or potential
development in the headwaters of Carruthers Creek. The headwaters that could potentially have development in the
future are the lands outside of the Greenbelt north of Highway 7. At the moment, these lands are not designated as part of
the settlement area of the City of Pickering in their Official Plan, or the Region of Durham's urban area boundary. For any
future development to occur, a Settlement Area Boundary Expansion, in compliance with the Growth Plan, would need to
occur. The following management recommendations speak to what would be required based on provincial policy and the
recommendations in this watershed plan. These management recommendations were already discussed under their relevant
goal, but are repeated here as they are specific to the headwaters of Carruthers Creek. Should a decision be made to proceed
with a Settlement Area Boundary Expansion, the full suite of management recommendations in Subsections 5.1 — 5.3 would
apply to that area.
TABLE 9:
Headwaters Specific Management Recommendations
1.1.3
1.1.4
54
Relevant Management Recommendations
If it is determined that a Settlement Area
Boundary Expansion is required in the headwaters
of Carruthers Creek, in accordance with
Growth Plan policies, the Region of Durham, in
collaboration with lower -tier municipalities and
TRCA, to develop a Terms of Reference outlining
requirements for further studies in support of
subwatershed planning that includes, but is not
limited to:
a. a hydraulic assessment
b. how natural hazards will be assessed and
mitigated (i.e. the risk of flooding will not
increase)
c. how the Natural Heritage System and Water
Resource System will be protected,
enhanced and restored
d. how water quality and quantity will be
protected.
During planning for transportation infrastructure
improvement projects, or new projects, the
Region of Durham and lower -tier municipalities
to implement best management practices for
design, expansions and widenings in accordance
with TRCA's Crossing Guideline for Valley and
Stream Corridors, and ensure consistent policies
and standards are in place to facilitate hydraulic
function (e.g. prevent flooding) and ecological
connectivity (e.g. wildlife passage). See map 3 for
priority crossings.
Rationale and Provincial Policy Basis
Appropriate scoping of any subwatershed studies
for potential future Settlement Area Boundary
Expansions will allow those studies to build upon
work completed through this watershed planning
process in a collaborative fashion.
Growth Plan policies 2.2.8.3 (d) / (e) and 4.2.1.3 (c).
This management recommendation is intended to
ensure hydrological and ecological connectivity
by improving crossings when new transportation
infrastructure is built, or existing infrastructure is
upgraded.
This recommendation will help protect the
integrity of the WRS and NHS, consistent with
Growth Plan policies 4.2.1 and 4.2.2.
Carruthers Creek Watershed Plan
55
Relevant Management Recommendations
Rationale and Provincial Policy Basis
1.2.4
For new developments, lower -tier municipalities
to require hydrologic analysis and erosion
threshold assessments downstream of potential
stormwater management facilities that need to
demonstrate no negative, or adverse, downstream
impacts, prior to municipal approvals.
This management recommendation is intended to
identify potential changes to the functions of the
WRS arising from new development.
It is consistent with Growth Plan policies related to
stormwater management (3.2.7).
1.3.3
Implement appropriate flood mitigation measures
for the Flood Vulnerable Cluster in the Town of
Ajax, which could involve:
a. reopening, or initiating, a new environmental
assessment to provide a more
comprehensive list of alternatives to offset
impacts associated with potential
development in the headwaters
b. the application of regional control in the
headwaters of Carruthers Creek, if developed
and required by updated flood modelling.
This management recommendation is in reference
to existing flooding issues in the lower part of the
Carruthers Creek watershed in the Town of Ajax.
The exact nature of the flood mitigation measure
will depend on whether development proceeds in
the headwaters of Carruthers Creek.
2.1.4
If it is determined that a Settlement Area
Boundary Expansion is required in the headwaters
of Carruthers Creek, in accordance with Growth
Plan policies, the City of Pickering, in collaboration
with the Region of Durham, Town of Ajax
and TRCA, as part of secondary planning to
demonstrate through a subwatershed plan (or
equivalent) that:
a. key hydrologic features will be protected
b. where avoidance of key hydrologic areas is
not possible, appropriate mitigation
measures are to be implemented to maintain
downstream hydrologic function, and
c. there will be no negative or adverse
downstream effects, such as increased
flooding, erosion, or deteriorated water quality.
Similarly, to management recommendation 1.1.3,
this management recommendation identifies
what is necessary to protect the integrity of the
WRS and NHS.
Growth Plan policies 2.2.8.3 (d) / (e), 4.2.1.3 (c),
4.2.2.3 and 4.2.2.7.
3.1.6
Wetland water balance studies that demonstrate
how the hydrological function of the wetland
should be protected will be undertaken by the
landowner for any potential future growth in the
areas identified in map 7, or other areas identified
during subwatershed planning, prior to any
planning approvals.
Wetlands are vital features to both the WRS and
NHS. Any development in proximity to wetland
features should demonstrate the protection of
hydrologic functions.
Growth Plan policies 4.2.1.2, 4.2.1.4 and 4.2.2.3.
55
6. Monitoring and Evaluation
Monitoring is vital to the successful implementation of this watershed plan. Monitoring will help
evaluate trends in watershed conditions and track the implementation of plan objectives. Monitoring
will help determine what is working to maintain or improve conditions and what, if necessary, needs
to change should conditions deteriorate.
The Carruthers Creek monitoring program is designed to evaluate both watershed health and
indicators associated with objectives of this watershed plan. The monitoring stations map (Figure 7)
identifies monitoring stations by category based on what they monitor. Table 10 explains the
Carruthers Creek monitoring program in detail. The stations identified in the monitoring stations
map are cross referenced in the station's column in Table 10 (e.g. the first station listed in the table is
an aquatic station, which is the yellow number 1 on the map).
Additional monitoring stations are likely necessary to adequately track watershed health trends and
the identified indicators over time. TRCA, in collaboration with its municipal partners, will identify
opportunities to expand watershed monitoring with appropriate resourcing. It will be particularly
important to ensure monitoring stations are collecting data in all parts of the watershed. Currently,
monitoring stations are limited in the northern part of the watershed.
56
ri? Toronto and Region
€1Conserva tion
Authority
A
Date: September 2019
Created by: TRCA Information Services/Information Technologies
Disclaimer:
The Data used to create this map was compiled from a variety sources
and dates. The TRCA takes no responsibility for errors or omissions
in the data and retains the right to make changes and corrections
at anytime without notice. For further information about the
data on this map, please contact the TRCA
GIS Department. (416) 661-6600.
Carruthers Creek
Watershed Plan:
Monitoring Stations
0 0.5 1 2 3KM
0 Aquatic
• Groundwater
• Terrestrial
• Water Quality
• Water Quantity
Municipal Boundary
•••••-•Watercourse
Greenbelt Boundary
Land Use
dir Natural
Rural
is Urban
c3Carruthers Creek
Watershed Boundary
Carruthers Creek
Watershed Plan Study
57
TABLE 10:
Carruthers Creek Monitoring Program
Monitoring
Category
Stations
Monitoring
Frequency
What is
monitored?
Why do we monitor it?
WATER
ID#: CCOO1WM
Every three
Fish community,
Indicator:
RESOURCE
(Yellow #1
years
aquatic habitat
Maintain, or increase, aquatic health
SYSTEM
(aquatic
ecosystems)
on map)
and benthic
invertebrate
community
y
rankings.
Applicable to WRS Objective 2.
ID#: CCOO2WM
(Yellow #2
on map)
Monitoring these aquatic habitat
characteristics allows for the
assessments of the overall health of
the aquatic ecosystem.
ID#: CC003WM
(Yellow #3
on map)
NATURAL
ID#:
Annually
Vegetation and
Indicator:
HERITAGE
FV -18 & FV -18_1
forest birds
Maintain, or increase, the number
SYSTEM
(Orange #1
and area of species and vegetation
(terrestrial
ecosystems)
on map)
communities of concern.
Applicable to NHS Objective 2.
Monitoring these terrestrial habitat
characteristics helps to understand
how the system is functioning
and if there are changes to species
composition over time.
Note:
This indicator requires inventory
data from across the watershed to
be properly assessed. The identified
monitoring stations only collect
data at that particular location and
therefore do not assess trends across
the watershed. An inventory would
need to be conducted within the
next ten years to update information
regarding current conditions.
58
Monitoring
Category
Stations
Monitoring
Frequency
What is
monitored?
Whydo we monitor it?
SURFACE
WATER
QUALITY
ID#: 107002
(Red #1
on map)
Monthly
samples
Water chemistry
(e.g. nutrients),
metals,
bacteria and
temperature
Applicable to overall watershed
health and trends to know whether
water quality conditions are
improving or not.
Monitoring water quality helps to
understand the impacts of land
uses on local water quality that
ultimately flows into Lake Ontario.
ID#: CC005
(Red #2
on map)
SURFACE
WATER
QUANTITY
ID#: HY013
(Blue #1
on map)
Continuous
water level
data collected,
reported in
15 -minute
intervals
Stream level,
discharge and
temperature
Applicable to overall watershed
health and trends to know whether
hydrology conditions are improving
or not.
Monitoring stream level, discharge
and temperature helps to understand
the interconnections between
groundwater and surface water. This
information can be used to guide
the management and protection of
baseflow levels to protect aquatic life
and ensure sustainable human use of
surface water.
ID#: HY090
(Blue #2
on map)
ID#: HY089
(Blue #3
on map)
ID#: WO002
(Blue #4
on map)
Continuous
water level
and certain
water quality
data collected,
reported in
15 minute
intervals.
Monthly grab
samples for
full suite of
water quality
parameters.
Also takes
event -based (i.e.
heavy rainfall)
water quality
samples.
Stream level,
discharge and
temperature
Note: also
measures water
quality as part
of Lake Ontario
tributary
monitoring
Applicable to overall watershed
health and trends to know whether
hydrology and water quality
conditions are improving or not.
The primary purpose of this station
is to assess nutrient loadings to
Lake Ontario.
59
Monitoring
Category
Stations
Monitoring
Frequency
What is
monitored?
Why do we monitor it?
TBD
Continuous
Rainfall and
Applicable to overall watershed
(New in
real-time
snowfall
health and trends to know
2019)
(reporting every
amount and
whether hydrology conditions
(Blue #5
on map)
5 minutes)
temperature
are improving or not.
Precipitation monitoring
information assists with flood
forecasting and warning, event -
based sampling, and watershed
planning.
TBD
(New in
2019)
(Blue #6
on map)
GROUNDWATER
TBD
Hourly
Water level and
Applicable to overall watershed
QUANTITY AND
(New in
groundwater
water chemistry
health and trends to know
QUALITY
2019)
level and
whether hydrogeology
(Purple #1
on map)
temperature,
monthly
manual
groundwater
level
measurements
and periodic
water chemistry
conditions are improving or not.
Groundwater and surface water
interactions are essential for a
functioning WRS. Understanding
groundwater conditions is vital
to understanding the nature of
these interactions.
Note:
The following indicators are not evaluated through a particular monitoring station in Carruthers Creek, but will be periodically
assessed through GIS analyses:
• Reduce number of flood vulnerable structures and flood vulnerable roads (Land Use Objective 2)
• Increase total natural cover in the watershed (NHS Objective 1)
• Increase total tree canopy in the watershed (NHS Objective 3)
The remaining indicators are qualitative (e.g. ensuring policies are in place) and will be reported on by TRCA in collaboration
with its municipal partners.
60
Carruthers Creek Watershed Plan
Reporting
As part of the Carruthers Creek monitoring program, TRCA, in collaboration with its municipal
partners, will conduct annual reporting to communicate on the health of the watershed and
plan implementation progress.
Annual reporting will help to track watershed health trends and the indicators identified as part
of this watershed plan.
Some components of this watershed plan may not be reported on annually (e.g. aquatic
community and terrestrial species). This is due to different monitoring frequencies for certain
components (e.g. aquatic species are surveyed every three years).
Adaptive Management
Adaptive management is a systematic process (see Figure 8) for continually improving practices
by learning and applying updated knowledge to improve project outcomes. In the context of
this watershed plan, adaptive management, in combination with the monitoring program, will
allow modifications and refinements to management recommendations, and/or the monitoring
program throughout the life cycle of this watershed plan. For example, if water quality continues
to deteriorate, certain land use management recommendations may not be resulting in the
desired outcome, requiring adjustment.
FIGURE 8:
Adaptive Management Cycle
0
Implement
0
Adjust /
Refine
0
Learn
0
Monitor
0
Evaluate
61
Pickering
The Water Resource System is essential
to maintaining the long-term
ecosystem resilience and sustainability
of the Carruthers Creek watershed.
MANAGEMENT RECOMMENDATION
2.1.1 refers to this map.
Map 1A includes the key hydrologic
features that comprise the WRS. See
Map 1B for key hydrologic areas.
Notes:
For Seepage Areas and Springs, this map
only includes areas where groundwater
discharge exceeds the median discharge
rate for the watershed. In other words,
it shows areas with higher than average
groundwater discharge. There could be
other seepage areas and springs not
shown on this map.
'(P�NjoN PD VJ
• nn
Ajax
50
4
G01oNRO �. L
BPVEV"V'1
‘Pc
PO ,ES°. aos
Torortta and Region
90- Conservation
Atrthorliat
N
A
Date: September 2019
Created by: TRCA Information Services/Information Technologies
Disclaimer:
The Data used to create this map was compiled from a variety sources
and dates. The TRCA takes no responsibility for errors or omissions
in the data and retains the right to make c angel and corrections
at anytime without notice. For further information about the
data on this map, please contact the TRCA
GIS Department. (416) 661-6600.
Carruthers Creek
Watershed Plan:
Water Resource System -
Map A
0 0.5 1 2 3
KM
Key Hydrologic Features
S Inland Lakes
�— Intermittent Streams
-nom— Permanent Streams
Seepage Areas and
Springs
Wetlands
Municipal Boundary
Carruthers Creek
L) Watershed Boundary
Carruthers Creek
Watershed Plan Study
62
Pickering
Map 1B
The Water Resource System is essential
to maintaining the long-term ecosystem
resilience and sustainability of the
Carruthers Creek watershed.
MANAGEMENT RECOMMENDATION
2.1.1 refers to this map.
Map 1B includes the key hydrologic
areas that comprise the WRS. See Map 1A
for key hydrologic features.
vosl
„ESSw a0 S
Toronto and Region
411 Conservation
Authority
Date: September 2019
Created by: TRCA Information Services/Information Technologies
Disclaimer:
The Data used to create this map was compiled from a variety sources
and dates. The TRCA takes no responsibility for errors or omissions
in the data and retains the right to make changes and corrections
at anytime without notice. For further information about the
data on this map, please contact the TRCA
GIS Department. (416) 661-6600.
Carruthers Creek
Watershed Plan:
Water Resource System -
Map B
0 0.5 1 2 3
KM
Key Hydrologic Areas
Highly Vulnerable
Aquifers
Significant
Groundwater
Recharge Areas
Ecologically Significant
K Groundwater Recharge
Areas
Municipal Boundary
Carruthers Creek
Watershed Boundary
Carruthers Creek
Watershed Plan Study
63
9SN 03` 0.D
Map 2
The proposed enhanced Natural Heritage
System consists of existing natural cover
areas and potential enhancement areas
(yellow) that are necessary to maintain
the long-term ecosystem resilience and
sustainability of the Carruthers Creek
watershed.
MANAGEMENT RECOMMENDATION
3.1.1 refers to this map.
Notes:
Wetlands are shown separately on
Map 1A for the WRS and included as
part of natural cover on Map 2 for the
NHS. Wetlands are a feature of both the
WRS and NHS in provincial policy.
�p55\ANo ��
,00.55`14
„cow's.”'
• Toronto and Region
'r;• ' Conservation A
,4utk f t
Date: September 2019
Created by: TRCA Information Services/Information Technologies
Disclaimer:
The Data used to create this map was compiled from a variety sources
and dates. The TRCA takes no responsibility for errors or omissions
in the data and retains the right to make changes and corrections
at anytime without notice. For further information about the
data on this map, please contact the TRCA
GIS Department. (416) 661-6600.
Carruthers Creek
Watershed Plan:
Enhanced Natural
Heritage System
0 0.5 1 2 3
KM
OValleyland fin Carruthers Creek Watershed
F9 ANSI Boundary
Carruthers Creek Watershed
K Natural Cover (Existing) Plan Study Area
Natural Cover (Potential) Land Use
nProvincial NHS ,e Natural
Rural
Urban
Municipal Boundary
Greenbelt Boundary
rtgi
Pickering
S°LC64 RQ
Map 3
This map represents both priority
hydrological and ecological connectivity
(i.e. habitat connectivity) improvements.
MANAGEMENT RECOMMENDATION
1.1.4 refers to this map.
The hydrological crossings are where
roads intersect with the stream network
and have been identified as needing
improved infrastructure (e.g. culverts).
The ecological crossings are road
segments that are priorities for
improved infrastructure to facilitate
wildlife crossings.
These priorities are intended for when
the identified portions of roads are
undergoing maintenance or upgrades.
illF Conservation
Ruthpdgi
A
Date: September 2019
Created by: TRCA Information Services/Information Technologies
Disclaimer:
The Data used to create this map was compiled from a variety sources
and dates. The TRCA takes no responsibility for errors or omissions
in the data and retains the right to make changes and corrections
at anytime without notice. For further information about the
data
GIStDepartm. please16) 661 6600 RCA
Carruthers Creek
Watershed Plan:
Priority Crossing
Improvements
0 05 1
2
3
• KM
Priority Hydrologic
• Crossings Improvement
Areas
Priority Ecological
Connectivity Areas
.n.w Watercourse
Greenbelt Boundary
cCarruthers Creek Watershed
W Boundary
Carruthers Creek Watershed
Plan Study Area
Land Use
41 Natural
Rural
41 Urban
Municipal Boundary
Note: Priorities shown in this map
are for regional roads only
65
Pickering
.0,13:10.14)
4•
8th Concession & Sideline 6
7th Concession & Si
5th Concession & Sideli
.s
sY
Audley Rd N
l
rµ
Map 4
This map represents priority restoration
areas.
MANAGEMENT RECOMMENDATION
1.3.1, 2.1.3, 3.1.2 and 3.2.2 refer to this
map.
These areas were prioritized based on
the ecological benefit of the restoration
opportunity, their geographic
distribution across the northern and
southern parts of the watershed, and
the range of aquatic and terrestrial
restoration opportunities.
See Table 11 for descriptions of each
restoration opportunity.
Rossland Rd E & Salem Rd N X54""
Ajax
q41
Kingston Rd E
Warbler Woods
wsw
Toronto and Re9917'i
_. Conservation
b ty
Date: September 2019
Created by: TRCA Information Services/Information Technologies
Disclaimer:
The Data used to create this map was compiled from a variety sources
and dates. The TRCA takes no responsibility for errors or omissions
in the data and retains the right to make changes and corrections
at anytime without notice. For further information about the
data on this map, please contact the TRCA
GIS Department. (416) 661-6600.
Carruthers Creek
Watershed Plan:
Restoration
Priorities
0 0.5 1 2 3
KM
OErosion Priority Restoration
Sites
OPriorRestorationityAreasOpportunity
Municipal Boundary
-n.-- Watercourse
Land Use
IP Natural
Rural
Urban
Greenbelt Boundary
) Carruthers Creek Watershed
Boundary
Carruthers Creek
Watershed Plan Study Area
Ecological Benefit
of Restoration Opportunity
Highest Benefit
66
Restoration Opportunity Planning for
Carruthers Creek
Restoration opportunity planning is TRCA's current
process for identifying and recording site -level
information for terrestrial and aquatic restoration
opportunities (e.g. wetland, riparian, forest, meadow
and stream restoration). TRCA's Integrated Restoration
Prioritization (IRP) tool is used to help select
priority restoration opportunities where ecological
impairments exist and, if restored, could contribute
most to the terrestrial natural heritage and water
resource systems.
Restoration opportunities in the Caruthers watershed
were originally identified using desktop assessment
techniques as per the restoration opportunity planning
methodology. For the Carruther's Creek Watershed
Plan, a more detailed prioritization method using
additional data identified the most important areas
to consider for restoration. This involved combining
the IRP scores with the criteria listed in management
recommendations 2.1.3 for aquatic and 3.1.2 for
terrestrial. TRCA then overlaid these scores with the
restoration opportunity planning information to
identify the highest scoring areas, which are circled
in Map 4 (Note: the Audley Road N opportunity was
selected for meadow restoration potential in support
of management recommendation 3.2.2).
Carruthers Creek Watershed Plan
67
TABLE 11:
Restoration Opportunity Summaries
Location
Restoration Opportunity
8th Concession
and Sideline 6
• Forest, wetland, stream and riparian restoration opportunities have been identified in
areas of residential and agricultural land uses.
• Forest restoration will help connect and expand existing forest to the north.
• Large-scale wetland and riparian restoration would restore headwater drainage feature
functions and benefit downstream habitat. Existing land use patterns have altered
streams, wetlands and riparian areas.
• With agriculture as the predominant land -use, the focus of restoration should be to
work with property owners to restore and maintain marginal lands that do not negatively
impact agricultural use but promote best management practices and contribute to the
potential enhanced natural heritage system.
7th Concession
and Sideline 6
• Forest, wetland, stream and riparian restoration opportunities were identified in this
largely agricultural area.
• Highest priority areas include riparian corridors and around existing forest patches.
• Portions in the north-east and along hydro corridors of this area provide meadow
restoration opportunities.
• Areas of wetland restoration will increase habitat diversity, contribute to the reduction of
run-off and increase water infiltration and storage.
5th Concession
and Sideline 6
• Forest, wetland, riparian and meadow restoration opportunities were identified in this
priority area.
• Restore large area of wetland and riparian habitat in the northern portion of this area.
• Meadow habitat can be created along the hydro corridor running east to west in this area.
• Existing forests can be expanded along the proposed enhanced NHS.
Audley Road
North
• Restore wetland and meadow habitat to the east of the stream, in collaboration with golf
course.
• Meadow restoration potential in the hydro corridor to the south of the area to support
habitat for sensitive species.
Rossland Road
East and Salem
Road North
• Restore riparian buffer to the west of the main branch of the creek and create a forest
buffer between future development and the NHS.
• Work with developer to restore wetlands and riparian corridors and encourage the use
of best management practices such as low impact development and buffers as part of
any development.
Kingston Road
East
• Restore riparian cover along the main channel of Carruthers Creek.
• Restore large wetlands to the east of this area and plant riparian and forest habitat
around the wetlands.
• Restore ponds in floodplain north of Kingston Road East to enhance wetland habitat and
connect corridor along the stream network.
Kingston Road
East
• Restore wetland habitat north of existing wetland to provide a buffer between this area
and potential development.
Warbler Woods
• Restore wetland habitat north of existing wetland to provide a buffer between this area
and potential development.
68
Pickering
a,� Luffy 4A
Map 5
This map represents priority fish barriers
for removal to restore in -stream aquatic
habitat connectivity.
MANAGEMENT RECOMMENDATION
2.2.1 refers to this map.
The red barriers are listed in order of
priority for removal.
Additional barriers should be considered
for removal after the six priority barriers
are removed.
Priority barrier types and amount of
habitat made available through the
removal of the barrier:
Barrier
Type
Habitat (km)
1
culvert
6
2
weir
2
3
log jam
0.75
4
weir
0.75
5
pipe
0.75
6
culvert
0.75
Toronto arid Region
." Conservation
Auttwd,,„
A
Date: September 2019
Created by: TRCA Information Services/Information Technologies
Disclaimer:
The Data used to create this map was compiled from a variety sources
and dates. The TRCA takes no responsibility for errors or omissions
in the data and retains the right to make changes and corrections
at anytime without notice. For further information about the
data on this map, please contact the TRCA
GIS Department. (416) 661-6600.
Carruthers Creek
Watershed Plan:
Fish Barriers
0 0.5 1 2 3
KM
• Priority Barriers
• Other Barriers
- - - Municipal Boundary
Watercourse
Greenbelt Boundary
Carruthers Creek
C„Z Watershed
Boundary
Carruthers Creek
Watershed Plan
Study Area
Land Use
f Natural
Rural
Urban
69
Map 6
This map represents priority areas for
public land securement. It is focused
south of Taunton Road due to the amount
of existing development in that area.
MANAGEMENT RECOMMENDATION
3.1.3 refers to this map.
This map does not imply the entirety
of the identified areas should become
public ownership, but rather where to
focus securement efforts when
opportunities arise.
These areas are in close proximity to
existing public land ownership and the
main channel of Carruthers Creek.
Notes:
Should development proceed north of
Taunton Rd., the priority securement areas
would be the existing and potential
natural cover areas identified as part of
the recommended NHS on map 2.
,r RC15
\NJE5';
Toronto andRegion
.'.3;1' Conservation
Apthodty.
A
Date: September 2019
Created by: TRCA Information Services/Information Technologies
Disclaimer:
The Data used to create this map was compiled from a variety sources
and dates. The TRCA takes no responsibility for errors or omissions
in the data and retains the right to make changes and corrections
at anytime without notice. For further information about the
data on this map, please contact the TRCA
GIS Department. (416) 661-6600.
Carruthers Creek
Watershed Plan:
Priority Securement
Areas
0.4 0.8 1.6
KM
Priority Securement Greenbelt Boundary - Land Use
Areas
C Inland Lakes
Watercourse
Municipal Boundary
1271
Carruthers Creek de Natural
Watershed Boundary
Carruthers Creek
Watershed Plan
Study Area
Rural
Urban
70
Pickering
Map 7
This map represents areas where wetland
water balance studies are needed for
any potential development in proximity
to the priority wetlands identified. Data
should be collected first in areas of high
risk and no data. The medium and low
risk areas would be secondary priorities.
MANAGEMENT RECOMMENDATION
3.1.6 refers to this map.
This map is focused on areas north of
Taunton Road to maintain hydrologic
function in the event of potential future
developments.
Refer to TRCA's Wetland Water Balance
Risk Evaluation (2017) for more
information.
Toronto and Regioni
Y-ifi Conservation
A
Date: September 2019
Created by: TRCA Information Services/Information Technologies
Disclaimer:
The Data used to create this map was compiled from a variety sources
and dates. The TRCA takes no responsibility for errors or omissions
in the data and retains the right to make changes and corrections
at anytime without notice. For further information about the
data on this map, please contact the TRCA
GIS Department. (416) 661-6600.
Carruthers Creek
Watershed Plan:
Wetland Water Balance
Study Priorities
0.5 1
KM
Wetland Priorities* Greenbelt Boundary
No Data C:3 Carruthers Creek Watershed Boundary
diHigh Carruthers Creek Watershed Plan Study Area
Medium Land Use
Low le Natural
Municipal Boundary
�— Watercourse
Rural
Urban
*Classifications based on TRCA Wetland Water Balance Risk Evaluation framework
71
�PUN��NRo\J
Map 8
This map represents areas to prioritize
tree conservation and tree planting
within the developed portion of the
watershed (i.e. urban forestry projects).
MANAGEMENT RECOMMENDATION
3.2.2 refers to this map.
-73c
This map is focused on areas south of
Taunton Road due to the urbanized
nature of that part of the watershed.
oposssj�N
Ajax Ajax
s
Toronto and Region
'' Conservation
Authudtp
A
Date: September 2019
Created by: TRCA Information Services/Information Technologies
Disclaimer:
The Data used to create this map was compiled from a variety sources
and dates. The TRCA takes no responsibility for errors or omissions
in the data and retains the right to make changes and corrections
at anytime without notice. For further information about the
data on this map, please contact the TRCA
GIS Department. (416) 661-6600.
Carruthers Creek
Watershed Plan:
Priority Urban Forestry
Areas
0 0.25 0.5
KM
4o Road Priorities
Parks in Priority
Neighbourhoods
GIPriority Conservation
Neighbourhood
Priority Planting
Neighbourhoods
Municipal Boundary
w�— Watercourse
Greenbelt Boundary
Carruthers Creek
- -' Watershed Boundary
Carruthers Creek
Watershed Plan Study
Area
Land Use
Natural
Rural
Urban
72
FIGURE 9
Subwatershed Quality Due to Impervious Cover
Figure 9
As discussed in Table 4 for the aquatic health of the WRS, subwatershed quality was assessed based on impervious cover
under the existing benchmark conditions and the three future scenarios. The proposed enhanced NHS benefits the
aquatic ecosystem in scenario 2 where the north-west subwatershed improves from good — fair to good. The increase
in impervious cover associated with scenario 3 results in all four subwatersheds degrading to fair — poor conditions,
and will likely result in the loss of Redside Dace, a listed endangered species, within the Carruthers Creek watershed.
Implementing the management recommendations identified in this watershed plan, especially limiting impervious
cover and undertaking restoration activities will help Redside Dace habitat.
The rating scale for subwatershed quality is based on the amount of impervious cover, with:
• Good (green) = 0 to 10% imperviousness
Good — fair (yellow) = 10 to 25% imperviousness
• Fair — poor (red) = greater than 25% imperviousness
Notes: the percent imperviousness identified in Subsection 4.3 is for the entire watershed; while the subwatersheds may have
different imperviousness values (e.g. Scenario 1 has 30% imperviousness across the entire watershed, whereas imperviousness by
subwatershed is as follows: 10% north-west, 11% north-east, 53% central and 49% south).
See Aquatic Impact Assessment technical report for more information.
73
Aquifer
A saturated permeable geologic unit that can transmit significant quantities of groundwater
under ordinary hydraulic gradients. They can be classified as confined or unconfined. In
southern Ontario, aquifers are typically comprised of sand and/or gravel, or fractured limestone.
Source: TRCA's Living City Policies, 2014
Biodiversity
The variability among organisms from all sources including terrestrial, marine and other aquatic
ecosystems and the ecological complexes of which they are part; this includes diversity within
species and ecosystems.
Source: TRCA's Living City Policies, 2014
Ecological Integrity
Which includes hydrologic integrity, means the condition of ecosystems in which,
a. the structure, composition and function of the ecosystems are unimpaired by stresses from
human activity,
b. natural ecological processes are intact and self-sustaining,
c. the ecosystems evolve naturally.
Source: Greenbelt Plan, 2017
Ecosystem Services
The benefits provided by ecosystems that are critical to the environment's life support systems
and that contribute to human welfare both directly and indirectly and therefore represent social
and economic value.
Source: TRCA's Living City Policies, 2014
Green Infrastructure
Natural and human -made elements that provide ecological and hydrologic functions and
processes. Green infrastructure can include components such as natural heritage features
and systems, parklands, stormwater management systems, street trees, urban forests, natural
channels, permeable surfaces, and green roofs.
Source: Growth Plan, 2019
74
Carruthers Creek Watershed Plan
Headwater Drainage Features
III -defined, non -permanently flowing drainage features that may not have defined beds and banks.
Source: TRCA's Living City Policies, 2014
Highly Vulnerable Aquifer
Aquifers, including lands above the aquifers, on which external sources have or are likely to have
a significant adverse effect.
Source: Growth Plan, 2019
Hydrologic Function
The functions of the hydrologic cycle that include the occurrence, circulation, distribution and
chemical and physical properties of water on the surface of the land, in the soil and underlying
rocks, and in the atmosphere, and water's interaction with the environment including its relation
to living things.
Source: Growth Plan, 2019
Hydrogeology
A science that describes the movement of groundwater, and its interaction with water that
moves on the ground surface in rivers, lakes, streams, and over land. Groundwater seeps into the
ground to varying depths and collects in aquifers. Groundwater can remain stored underground
for periods ranging from a few days to thousands of years.
Source: TRCA's Living City Policies, 2014
Hydrology
The engineering science that analyzes the different components of the hydrologic cycle, and
takes into account that the natural cycle can be altered by human and natural activities.
Source: TRCA's Living City Policies, 2014
Life Science Areas of Natural and Scientific Interest (ANSIs)
An area that has been identified as having life science values related to protection, scientific
study, or education; and further identified by the Ministry of Natural Resources and Forestry
using evaluation procedures established by that Ministry, as amended from time to time.
Source: Growth Plan, 2019
75
Low Impact Development
An approach to stormwater management that seeks to manage rain and other precipitation as
close as possible to where it falls to mitigate the impacts of increased runoff and stormwater
pollution. It typically includes a set of site design strategies and distributed, small-scale
structural practices to mimic the natural hydrology to the greatest extent possible through
infiltration, evapotranspiration, harvesting, filtration, and detention of stormwater. Low impact
development can include, for example: bio-swales, vegetated areas at the edge of paved
surfaces, permeable pavement, rain gardens, green roofs, and exfiltration systems. Low impact
development often employs vegetation and soil in its design, however, that does not always
have to be the case and the specific form may vary considering local conditions and community
character.
Source: Growth Plan, 2019
Natural Hazards (Consisting of Erosion Hazard and Flooding Hazard)
EROSION HAZARD
Means the loss of land, due to human or natural processes, that poses a threat to life and
property.
FLOODING HAZARD
Means the inundation of areas adjacent to a shoreline or a river or stream system not ordinarily
covered by water.
Source: PPS, 2014
Natural Heritage System
A system made up of natural heritage features and areas, and linkages intended to provide
connectivity (at the regional or site level) and support natural processes which are necessary to
maintain biological and geological diversity, natural functions, viable populations of indigenous
species, and ecosystems. The system can include key natural heritage features, key hydrologic
features, federal and provincial parks and conservation reserves, other natural heritage features
and areas, lands that have been restored or have the potential to be restored to a natural
state, associated areas that support hydrologic functions, and working landscapes that enable
ecological functions to continue.
Source: Growth Plan, 2019
Negative Impacts
Means:
a. in regard to policy 1.6.6.4 and 1.6.6.5 degradation to the quality and quantity of water,
sensitive surface water features and sensitive ground water features, and their related
hydrologic functions, due to single, multiple or successive development.
76
Carruthers Creek Watershed Plan
b. in regard to policy 2.2, degradation to the quality and quantity of water, sensitive surface
water features and sensitive ground water features, and their related hydrologic functions,
due to single, multiple or successive development or site alteration activities;
c. in regard to fish habitat, any permanent alteration to, or destruction of fish habitat, except
where, in conjunction with the appropriate authorities, it has been authorized under the
Fisheries Act; and
d. in regard to other natural heritage features and areas, degradation that threatens the health
and integrity of the natural features or ecological functions for which an area is identified due
to single, multiple or successive development or site alteration activities.
Source: PPS, 2014
Regional (flood) Control
Stormwater management control of flood flows from the regional storm event (Hurricane Hazel)
to mitigate increases in flood risk associated with development (urbanization).
Source: TRCA's Living City Policies, 2014
Riparian
The areas adjacent to water bodies such as streams, wetlands and shorelines. Riparian areas form
transitional zones between aquatic and terrestrial ecosystems.
Source: TRCA's Living City Policies, 2014
Seepage Areas and Springs
Sites of emergence of groundwater where the water table is present at the ground surface.
Source: Growth Plan, 2019
Significant Groundwater Recharge Area
An area that has been identified:
a. as a significant groundwater recharge area by any public body for the purposes of
implementing the PPS, 2014;
b. as a significant groundwater recharge area in the assessment report required under the Clean
Water Act, 2006; or
c. as an ecologically significant groundwater recharge area delineated in a subwatershed plan or
equivalent in accordance with provincial guidelines.
For the purposes of this definition, ecologically significant groundwater recharge areas are areas
of land that are responsible for replenishing groundwater systems that directly support sensitive
areas like cold water streams and wetlands.
Source: Growth Plan, 2019
77
Sustainable Community Retrofits
Focus on actions in older, urban neighbourhoods by retrofitting buildings and infrastructure,
regenerating habitats and urban ecology, and revitalizing a community's social fabric. TRCA's
Sustainable Neighbourhood Action Program provides examples of sustainable community
retrofits.
Source: Sustainable Neighbourhood Action Program, TRCA, 2020
Urban Forest
All trees, shrubs and understorey plants, as well as the soils that sustain them, on public and
private property within an urban setting.
Source: TRCA's Living City Policies, 2014
Vegetation Protection Zone
A vegetated buffer area surrounding a key natural heritage feature or key hydrologic feature.
Source: Growth Plan, 2019
Water Balance
The hydrologic cycle of precipitation, groundwater infiltration, evapotranspiration (into the
atmosphere and by plant interception), and surface runoff..
Source: TRCA's Living City Policies, 2014
Water Resource System
A system consisting of ground water features and areas and surface water features (including
shoreline areas), and hydrologic functions, which provide the water resources necessary to
sustain healthy aquatic and terrestrial ecosystems and human water consumption. The water
resource system will comprise key hydrologic features and key hydrologic areas.
Source: Growth Plan, 2019
78
9. References
Carruthers Creek Watershed Characterization Technical Reports
Dr. Richard Gerber and Mike Doughty, Oak Ridges Moraine Groundwater Program, 2017.
Carruthers Creek Watershed Plan: Hydrogeology. Prepared for the Toronto and Region
Conservation Authority and the Region of Durham.
Matrix Solutions Inc., 2017. Carruthers Creek Watershed Plan: Fluvial Geomorphology Assessment of
Regional Watershed Monitoring Program Data 2003 - 2016. Prepared for the Toronto and Region
Conservation Authority and the Region of Durham.
Toronto and Region Conservation Authority, 2017. Carruthers Creek Watershed Plan: Aquatic
Crossing and Barrier Assessment Report. Prepared for the Region of Durham.
Toronto and Region Conservation Authority, 2017. Carruthers Creek Watershed Plan: Aquatic
Habitat and Community Characterization. Prepared for the Region of Durham.
Toronto and Region Conservation Authority, 2017. Carruthers Creek Watershed Plan: Headwater
Drainage Features Characterization. Prepared for the Region of Durham.
Toronto and Region Conservation Authority, 2017. Carruthers Creek Watershed Plan: Preliminary
Water Quantity Characterization. Prepared for the Region of Durham.
Toronto and Region Conservation Authority, 2018. Carruthers Creek Watershed Plan: Water
Quantity Characterization. Prepared for the Region of Durham.
Toronto and Region Conservation Authority, 2017. Carruthers Creek Watershed Plan: Surface Water
Quality Characterization. Prepared for the Region of Durham.
Toronto and Region Conservation Authority, 2017. Carruthers Creek Watershed Plan: Terrestrial
Biological Inventory and Assessment. Prepared for the Region of Durham.
Carruthers Creek Watershed Scenario Analysis Technical Reports
Matrix Solutions Inc., 2019. Carruthers Creek Watershed Plan: Fluvial Geomorphic Assessment.
Prepared for the Toronto and Region Conservation Authority and the Region of Durham.
79
Oak Ridges Moraine Groundwater Program, 2019. Carruthers Creek Watershed Plan: Groundwater
Modelling. Prepared for the Toronto and Region Conservation Authority and the Region of
Durham.
Toronto and Region Conservation Authority and Environment and Climate Change Canada, 2019.
Carruthers Creek Watershed Plan: Soil Water Assessment Tool (SWAT) Modelling. Prepared for the
Region of Durham.
Toronto and Region Conservation Authority, 2019. Carruthers Creek Watershed Plan: Aquatic Impact
Assessment. Prepared for the Region of Durham.
Toronto and Region Conservation Authority, 2019. Carruthers Creek Watershed Plan: Stormwater
Management. Prepared for the Region of Durham.
Toronto and Region Conservation Authority, 2019. Carruthers Creek Watershed Plan: Hydrological
Assessment. Prepared for the Region of Durham.
Toronto and Region Conservation Authority, 2019. Carruthers Creek Watershed Plan: Terrestrial
Impact Assessment. Prepared for the Region of Durham.
Toronto and Region Conservation Authority, 2019. Carruthers Creek Watershed Plan: Urban Forest
Assessment. Prepared for the Region of Durham.
Provincial / Federal Policies / Plans / Guidance
Canadian Council of Ministers of the Environment, no date. Water Quality Guidelines for the
Protection of Aquatic Life.
CTC Source Protection Committee, 2019. Approved Source Protection Plan: CTC Source Protection
Region. Amendment (Version 2.0) effective March 25, 2019.
Environment and Climate Change Canada, 2013. How Much Habitat is Enough?Third Edition.
Ontario, 2019. A Place to Grow: Growth Plan for the Greater Golden Horseshoe.
Ontario, 2017. Greenbelt Plan.
Ontario, 2016. Guidance for Development Activities in Redside Dace Protected Habitat.
Ontario, 2016. Water Management: Policies, Guidelines, Provincial Water Quality Objectives
Ontario, 2014. Provincial Policy Statement. Under the Planning Act.
80
Carruthers Creek Watershed Plan
Great Lakes Agreements and Policiess
Government of Canada and Government of Ontario, 2014. Canada - Ontario Agreement on Great
Lakes Water Quality and Ecosystem Health.
Government of Canada and Government of the United States of America, 2012. Great Lakes Water
Quality Agreement.
Ontario, 2016. Ontario's Great Lakes Strategy.
Municipal Official Plans
City of Pickering, 2018. Pickering Official Plan: Edition 8.
Region of Durham, 2017.2017 Durham Regional Official Plan
Town of Ajax, 2016. Official Plan.
Municipal Guidelines, Reports or Strategies
Cole Engineering, 2012. Carruthers Creek Flood Management and Analysis EA. Regional Official
Plan Amendment No. 128 Impact Report. Prepared for the Town of Ajax.
Region of Durham, 2016. Towards Resilience: Durham Community Climate Adaptation Plan 2016.
Region of Durham, 2012. From Vision to Action: Region of Durham Community Climate Change
Local Action Plan 2012.
TRCA Guidelines
Credit Valley Conservation and Toronto and Region Conservation Authority, 2014. Evaluation,
Classification and Management of Headwater Drainage Features Guidelines.
Credit Valley Conservation and Toronto and Region Conservation Authority, 2010. Low Impact
Development Stormwater Management Planning and Design Guide.
Toronto and Region Conservation Authority, 2018. Guideline for Determining Ecosystem
Compensation (after the decision to compensate has been made).
Toronto and Region Conservation Authority, 2017. Wetland Water Balance Risk Evaluation.
Toronto and Region Conservation Authority, 2016. Integrated Restoration Prioritization: A Multiple
Benefit Approach to Restoration Planning.
81
Toronto and Region Conservation Authority, 2016. Wetland Water Balance Monitoring Protocol.
Toronto and Region Conservation Authority, 2015. Crossings Guideline for Valley and Stream
Corridors.
Toronto and Region Conservation Authority, 2014. The Living City Policies: for Planning and
Development in the Watersheds of the Toronto and Region Conservation Authority.
Toronto and Region Conservation Authority, 2012. Preserving and Restoring Healthy Soil: Best
Practices for Urban Construction.
Toronto and Region Conservation Authority, 2012. StormwaterManagementCriteria.
Toronto and Region Conservation Authority, 2007. Terrestrial Natural Heritage System Strategy.
82
Developed in collaboration with
the Town of Ajax and City of Pickering
-1
DURHAM
REGION
IW
Toronto and Region
S Conservation
Authority
Attachment #2 to Report #PLN 16-20
Carruthers Creek Watershed Plan -Hydrological Assessment
RESULTS AND DISCUSSION
As noted above, a comparison of Regional Storm peak flows at multiple locations through the watershed is
provided in Table 2. In addition to the Regional Storm simulations, Appendix 2 includes results for the design
storm simulations for Scenarios 1, 2 and 3. Please see Appendix 3 for the hydrographs associated with the
Regional Storm.
Although the text below refers mainly to the results from the Regional Storm simulations, the trends
observed for the Regional Storm are also observed for the design storm simulations. As such, the description
and rationale provided below are also applicable for the design storm simulations.
Please note that the peak flow values differ slightly between the 2011 update and current study for Scenario
1; this is due to the reclassification of residential land use between the two models. Specifically, Scenario 1
combined low- and medium -density residential land use, which resulted in a higher impervious value than
what was used by Cole in 2011. The increased impervious value affects the %Imp and XIMP parameters in the
model, resulting in slightly increased peak flow values over those established by Cole in 2011.
Although the modelling completed as part of this scenario analysis only looked at land use as a future
stressor, climate change is expected to increase precipitation, annual average temperatures and the
frequency of extreme weather events, which will impact watersheds within the Region of Durham. Some of
the anticipated implications of a changing climate include localized flooding, violent storm damage, changes
to ecosystem composition, and changes to agricultural conditions and production.
Scenarios 1 and 2
Generally, there is a slight reduction in peak flow values when comparing Scenario 1 and 2 (see Table 2). This
reflects the impacts associated with the enhanced NHS. From a flood mitigation and management
perspective, the proposed NHS has negligible impacts on flood flows however there are several ecological
and temperature mitigation benefits which have been documented within the CCWP.
Scenarios 1 and 3
Results at a catchment scale for Scenarios 1 and 3 indicate significant changes in peak flow values. In one
instance, peak flow values are reduced while an increase in peak flow is observed for most of the watershed.
It is important to note that the reduction in peak flow values for the East Tributary downstream of Highway 7
is the result of changes to catchment timing under Scenario 3, where the location of the potential
development area and increases in impervious surfaces results in runoff reaching the catchment outlet faster
than the land use assumptions used for Scenario 1.
Page 10 of 34
Carruthers Creek Watershed Plan -Hydrological Assessment
TABLE 2 REGIONAL STORM SIMULATION RESULTS
Regional Storm VO2 Sub- 2011 Scenario 1 (+OP)
catchment Update
IDs
Location
Peak
Flows
(m3/s)
Scenario 2 (+NHS) Scenario 3 (+Potential
Urban)
Peak 1 % Change
Flows from 2011
(m3/s) Update
Peak
Flows Change
(m3/s) from
Scenario
1
U/S Hwy. 7 (W.
Tributary)
3096
12.98
1175
7.6
3095 20.49
D/S Hwy. 7 (E.
Tributary)
D/S 5th
Concession (E.
Tributary)
1181
5.73
11.012
7.601
18.612
5.725
-15.2%
10.713
Peak I % Change
Flows from
(m3/s) Scenario 1
- 2.7%
47.347
0.0%
- 9.2%
-0.1%
7.394
18.107
- 2.7%
31.893
- 2.7% 78.605
5.539
-3.2%
3.345
330.0%
319.6%
322.3%
-41.6%
1182
7.21
7.205
-0.1%
7.005
-2.8%
30.395
321.9%
1183
7.01
7.011
0.0%
6.91
-1.4%
19.927
184.2%
3103
18.57
18.572
0.0%
18.114
- 2.5%
62.462
236.3%
U/S Taunton Rd.
(Confluence)
1179
3.68
3.678
- 0.1%
3.691
0.4%
3.691
0.4%
3102
3101
3094
23.42
23.423
0.0%
22.916
- 2.2%
61.279
161.6%
26.99
26.992
0.0%
26.505
- 1.8%
62.965
133.3%
35.13
32.702
- 6.9%
31.944
- 2.3%
78.623
140.4%
3098
33.76
34.465
2.1%
33.924
- 1.6%
67.896
97.0%
3093
68.89
67.153
- 2.5%
65.855
- 1.9%
146.519
118.2%
Taunton Rd.
3092
71.61
69.897
- 2.4%
68.593
- 1.9%
148.839
112.9%
CPR
U/S Rossland
Rd.
Hwy. 2 E.
D/S Bayly St.
3087
70.66
3082
68.988
70.51 68.863
1044 94.07 99.6
1033 105.74
- 2.4%
- 2.3% 67.941
67.689
- 1.9%
156.109
126.3%
-1.3% 160.888 133.6%
5.9% 96.468 -3.1% 193.789 94.6%
114.651 8.4% 112.25 -2.1% 190.371 66.0%
Shoal Point Rd.
1005
140.52
149.498
6.4%
147.189
-1.5%
210.632
40.9%
Lake Ontario
1000
146.92
155.952
6.1%
153.714
-1.4%
213.973
37.2%
Page 11 of 34
Carruthers Creek Watershed Plan -Hydrological Assessment
At a sub -watershed scale, significant increases in peak flows are also observed. This is also a reflection of the
location and scale of the potential development area used in Scenario 3. The significant increase in
impervious surfaces associated with the potential development will impact runoff volume and watershed
timing, increasing peak flow values at and downstream of confluence points.
At a watershed scale the change in peak flow values are not as pronounced as those at a catchment and sub -
watershed scale. This reflects the magnitude of the peak flow values being compared to one another, and the
effects of routing flows through significant downstream valley corridors.
Without proper mitigation, the increase in peak flow values observed through Scenario 3 would have
significant impacts to flood levels throughout the watershed. Of concern is the impact to flooding for the
Lower Carruthers Flood Vulnerable Cluster within the Town of Ajax. Past studies completed by the Town and
TRCA have indicated the need to implement flood remediation solutions in the form of an identified Flood
Protection Landform and improved conveyance through the valley to reduce existing flood risk.
As per TRCA's Flood Protection Land Forming Technical Guidelines, AECOM 2019:
A flood protection landform is generally defined as a non-structural measure made of earth that
provides permanent flood protection. Landforms are similar to dykes and berms, since they are man-
made barriers placed adjacent to river corridors to provide passive protection from flooding. Unlike
traditional dykes and berms, however, landforms are built on a much larger scale with very gentle
slopes. Furthermore, landforms are designed to generally require less maintenance and provide a
significantly higher lever of protection in terms of typical models of failure.
Should development within the Carruthers Creek headwaters proceed, the flood remediation solutions
proposed for the Lower Carruthers Flood Vulnerable Cluster would not meet the original design requirements
established through the EA process (i.e. provide permanent flood control for Lower Carruthers to the
Regional Storm). As such, a thorough reassessment of the Carruthers Creek Flood Management & Analysis
Municipal Class EA would be required should a Settlement Area Boundary Expansion be justified following
the Municipal Comprehensive Review process. This reassessment would involve initiating a new
environmental assessment to investigate a more comprehensive list of alternate solutions to offset any
impacts associated with potential development in the headwaters of Carruthers Creek following a Settlement
Area Boundary Expansion.
It should be noted that the intent of this assignment was to simulate the hydrologic response of several land
use scenarios to inform the CCWP. Completing a detailed hydraulic assessment to quantify the impacts to
flood levels within the watershed was outside the scope of work. Given the observed increase in peak flow
values for Scenario 3 it is recommended that, following a Settlement Area Boundary Expansion, in
accordance with the Growth Plan, and prior to municipal approval of a development proposal, a thorough
hydraulic assessment be undertaken to quantify the potential changes to flood levels prior to development
proceeding. Further, if current urban areas are susceptible to flooding under Scenario 3, then further flood
remediation assessments in the form of feasibility assessments and Environmental Assessments would need
to be undertaken by TRCA or its municipal partners in Durham.
Page 12 of 34
Carruthers Creek Watershed Plan -Hydrological Assessment
Scenario 3 and ROPA 128, 2012
The Cole report entitled Carruthers Creek Flood Management & Analysis Municipal Class EA: Regional Official
Plan Amendment No. 128 Impact Report, May 2012, simulated hydrological impacts from potential future
build -out conditions using the Natural Heritage System delineated in the current City of Pickering Official
Plan. This scenario is herein referred to as ROPA 128, 2012. There was interest amongst CCWP stakeholders
to compare the results of the ROPA 128, 2012 scenario with Scenario 3 to examine the benefits of the
Enhanced Natural Heritage System for various design storms if potential future build -out should proceed.
Because the Enhanced NHS is likely to have limited hydrologic benefit during a storm event with a magnitude
such as the Regional Storm, it is not surprising that there is no significant difference in Regional Storm flow
values between Scenario 3 and the ROPA 128, 2012 modelling results. However, benefits of the Enhanced
NHS can be observed for the smaller storms as peak flows are up to 25% higher for the ROPA 128, 2012
scenario compared to Scenario 3 (e.g. for 2 -year storm). It should be noted that TRCA did not develop a new
modelling scenario for ROPA 128. Flow values presented in Appendix 4 for the ROPA 128, 2012 scenario
were taken directly from the 2012 hydrology summary report by Cole. Please see Appendix 4 for details.
MANAGEMENT/MITIGATION RECOMMENDATIONS
The following section provides a high-level list and description of potential management recommendations
related to flood impacts for Region of Durham, Town of Ajax, and City of Pickering consideration. The
management recommendations provided are preliminary and should be confirmed and validated through
additional hydrologic and hydraulic modelling, in compliance with the Growth Plan. This will ensure that the
recommendations remain applicable should a Settlement Area Boundary Expansion in the headwaters of the
Carruthers Creek watershed be required following the Municipal Comprehensive Review and Land Needs
Assessment processes. The management recommendations will need to be reassessed at the appropriate
time (i.e. secondary planning, subwatershed planning) prior to any development being approved.
Land Use Planning
Should a Settlement Area Boundary Expansion be justified in the headwaters of Carruthers Creek watershed,
in accordance with the Growth Plan, then it must be demonstrated through subwatershed planning (or
equivalent through a secondary plan process) that the proposed expansion would be planned to avoid, or
minimize and mitigate, any potential negative impacts on watershed conditions and the Water Resource
System, including the quality and quantity of water. This approach would utilize land use planning
approaches to minimize imperviousness and maintain hydrologic processes and downstream flows. For
example, focusing potential development in smaller, higher -density development areas could maintain larger
natural areas that would limit downstream flows.
Implementation of Downstream Flood Remediation Alternatives
In combination with land use planning, a thorough reassessment of the Carruthers Creek Flood Management
& Analysis Municipal Class EA would be required should a Settlement Area Boundary Expansion be justified
following the Municipal Comprehensive Review process. This reassessment would involve initiating a new
environmental assessment to investigate a more comprehensive list of alternative solutions to offset any
impacts associated with potential development in the headwaters of Carruthers Creek following a Settlement
Area Boundary Expansion. Any reassessment of flood mitigation measures developed for the Lower
Page 13 of 34
Carruthers Creek Watershed Plan -Hydrological Assessment
Carruthers Flood Vulnerable Cluster should consider future impacts of climate change using the most up to
date climate modelling data for Durham Region in addition to a detailed analysis related to the impact on
flooding as a result of record Lake Ontario levels in 2017 and 2019.
Future Studies
As noted above, potential changes to flood levels across the watershed should be assessed following a
Settlement Area Boundary Expansion and prior to municipal approval of any development proposals (i.e. at
the Secondary Plan stage). If this assessment identifies that new areas of the watershed are susceptible to
flooding, then further flood remediation assessments, in the form of feasibility assessments and/or
environmental assessments would need to be undertaken to mitigate any potential impacts.
Regional Storm Stormwater Management Quantity Control
The application of Regional Control in the headwaters of Carruthers Creek is recommended should
development be proposed following a Settlement Area Boundary Expansion. The Ministry of Natural
Resources and Forestry (MNRF) has not accepted this approach in TRCA's jurisdiction and further
consultation including support from the MNRF would be required to apply Regional Control. Land use needs
to accommodate the required runoff volume may not comply with land use targets due to pond size.
Municipal Infrastructure Upgrades
Existing water crossings overtopped during a Regional Storm event should be upgraded to ensure safe public
and emergency response passage. Furthermore, watercourse crossings where upstream flood levels result
from insufficient crossing capacity should be replaced'.
1 A list of these structures has been provided under a separate cover and will be included in the CCWP.
Page 14 of 34
Attachment #3 to Report #PLN 16-20
Toronto and Region
Conservation
Authority
July 20, 2020
To Concerned Members of the Public:
Re: Draft Carruthers Creek Watershed Plan
Clarification of TRCA Findings and Position Related to Development Proposals
in the Watershed
The Toronto and Region Conservation Authority (TRCA) appreciates the significant public interest in
the draft Carruthers Creek Watershed Plan (CCWP) that was released for public review in March 2020,
The development of the draft CCWP has been a multi-year collaborative effort between TRCA and the
Region of Durham, in consultation with the Town of Ajax and City of Pickering. Extensive public
engagernent has occurred to develop this watershed plan. This effort has included gathering input from
watershed residents and stakeholders by using tools such as online surveys, pop-up displays at
community events, stakeholder workshops, presentations to committees and councils, and Public
Information Centres. TRCA recognizes and appreciates the concern that residents have for protecting
and restoring the health of the watershed.
Recently, concern from members of the public has been expressed to local municipal and provincial
officials on the findings of the watershed plan and how it relates to proposed development in the
headwater areas of Carruthers Creek. TRCA would like to clarify some of the findings of the watershed
plan and to offer some insights on our role in the planning process:
Flood Risk
TRCA assessed potential future scenarios as part of the watershed planning process to determine how
different land uses would impact the watershed (Section 4 of the Carruthers Creek Watershed Plan).
Scenario 3 assumed development in the headwaters of Carruthers Creek, outside the proposed
enhanced Natural Heritage System. Peak flows were identified to potentially increase by 77% for the
regional storm event, compared to current conditions. However, the flood modelling completed as part
of this watershed planning exercise did not factor in potential mitigation measures (e.g. modern
stormwater infrastructure). To address this, TRCA included a series of management recommendations
which includes additional studies to be completed prior to the consideration of any development
approvals in the headwaters of Carruthers Creek.
Headwaters Development
Some members of the public's recent correspondence relating to the watershed plan findings and
proposed development in the headwaters states "The TRCA Report makes 11 very clear that under 170
circumstances should the Carruthers Headwaters be urbanized. The cost is too great." The draft
CCCWP does not state that development in the headwaters of Carruthers Creek should not proceed.
Instead, it identifies potential impacts of development and proposes a series of mitigation measures to
manage those impacts should development be considered within the headwaters area.
The success of these mitigation measures is, however, predicated upon the establishment of an
enhanced Natural Heritage System in the headwaters, Specifically, subsection 5.4 of the draft CCWP
outlines recommendations relevant to potential development in the headwaters. These
recommendations include the need to protect adequate land in the headwaters which can be restored,
to complete a hydraulic assessment, and to implement appropriate flood mitigation measures to
mitigate downstream impacts that may exacerbate the existing Flood Vulnerable Cluster in the Town of
Ajax. This may require the consideration of Regional Flood Control (e g., offline detention systems) and
1
Op' I I k Toronto and Region
41) Conservation
Authority
updating or undertaking a new Environmental Assessment of the downstream Flood Vulnerable Cluster
in Ajax depending on the nature and configuration of any development. The detailed planning of the
proposed Natural Heritage System would be formalized through the municipally led development
approval process that would follow the Municipal Comprehensive Review (MCR) process being led by
the Region.
Planning Process
Watershed plans inform land use planning decisions and municipal decision-making processes for land
use and infrastructure planning. TRCA, in collaboration with the Region of Durham, and in consultation
with the Town of Ajax and City of Pickering, developed the management framework for the Carruthers
Creek Watershed Plan based on the MCR process envisioned in the Growth Plan for the Greater
Golden Horseshoe. It is through this MCR process that municipal decisions on potential future
development will be made.
TRCA is aware of the Ministerial Zoning Order request by Dorsay Development Corporation for the
Veraine community on privately held lands in the Carruthers Creek Watershed Plan study area. TRCA
notes that a Ministerial Zoning Order would be a departure from the current provincial land use planning
framework and the collaborative work of the Region and lower -tier municipalities. TRCA would rather
see the MCR process continue as planned to ensure all matters of provincial and municipal interest
related to TRCA's mandate are addressed. TRCA has communicated this position to the Province and
has indicated our interest in discussing the matter further with appropriate provincial staff. TRCA has
also met with Dorsay Development Corporation during the development of the draft CCWP to discuss
their concerns and will continue to do so. In addition, TRCA will continue to act as a technical advisor
and resource to the Province, Region and local municipalities by informing all parties of the findings of
the draft CCWP as the Province considers the Dorsay request.
Please visit https://trca.ca/conservation/watershed-management/carruthers-creeklwatershed-plan/ for
more information on the development of the CCWP, or contact carruthers[a?trca.ca if you have any
questions about the draft Plan or this process. As stated on the website, the public review of the draft
CCWP has been paused due to the COVID-19 situation and will resume once the state of emergencies
from all levels of government are lifted.
John MacKenzie
Chief Executive Officer
Toronto and Region Conservation Authority
cc: Hon. Rod Phillips, Minister of Finance, MPP for Ajax
Hon. Steve Clark, Minister of Municipal Affairs and Housing
Peter Bethlenfalvy, MPP for Pickering -Uxbridge
Jennifer Innis, TRCA Board Chair
John Henry, Regional Chair and CEO
Kevin Ashe, Acting Mayor of Pickering, TRCA Board of Director
Joanne Dies, Regional Councilor, TRCA Board of Director
David Ryan, Mayor of Pickering
Shaun Collier, Mayor of Ajax
Brian Bridgeman, Commissioner, Planning & Economic Development, Region of Durham
Sameer Dhalla, Director, Development & Engineering Services. TRCA
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