HomeMy WebLinkAboutENG 01-13 C11,14 Report to
Executive Committee
PICKERIN Report Number: ENG 01-13
Date: October 7, 2013
From: Richard W. Holborn
Director, Engineering & Public Works
Subject: Eurasian Water-Milfoil Weed — Frenchman's Bay
- File: A-1440
Recommendation:
1. That Report ENG 01-13 of the Director, Engineering & Public Works regarding
Eurasian Water-Milfoil Weed on Frenchman's Bay be received for information;
2. That staff be directed to include funding requests during the preparation of the 2014
to 2016 budgets for continued support for this initiative; and
3. That staff report back to Council annually regarding the status of the Milfoil weed
presence in Frenchman's Bay.
Executive Summary: Over the past few years, Eurasian Water-Milfoil, an invasive
aquatic weed, has been quickly re-colonizing Frenchman's Bay. During the summer of
2012, its growth began to cause problems for the boaters and paddlers by binding up
propellers, keels and paddles.
Members of the boating community and residents around the bay formed the Allies of
Frenchman's Bay Association with the focus of jointly combating the Milfoil weed
problem. The group researched the various control methods and recommended an
integrated management plan through the use of the Milfoil Weevil, herbicide treatment
and dredging. They obtained quotations for the said works and prepared a contribution
plan which included some funding from the City of Pickering over a four year period.
In early August 2013, approximately 20,000 Milfoil Weevil eggs and larvae were stocked
in the bay, in an area where the Eurasian Water-Milfoil growth was the thickest adjacent
to Bruce Hanscombe Park.
Financial Implications: As part of the 2013 Current Budget, Council approved a grant
up to $30,000 as the City's share for the first year of the program. Requests for future
funding requirements will be considered during the annual budget approval process as
follows: $20,000 for year 2 (2014), $10,000 for year 3 (2015) and $750 for year 4 (2016)
for a total of$60,750 over the four year period.
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Eurasian Water-Milfoil Weed — Frenchman's Bay Page 2
Due to this year's cooler weather and higher water levels the Milfoil weed growth was
not as extreme. As such, fewer weevils were introduced into the bay than originally
proposed, thus reducing the City's share of the cost to $8,325.00 for 2013.
Discussion: For a number of years the Toronto and Region Conservation
Authority have been monitoring the growth of aquatic vegetation on Frenchman's Bay.
Over the summers of 2011 and 2012, they witnessed the complete re-colonization of
aquatic plants over the bay. This was due to the improvement of water clarity, low
water levels and hot, sunny summers. The positive aspect of this re-colonization was
that the aquatic plants provided excellent fish and wildlife habitat. The problem was that
20 percent of the bay was being re-colonized with the invasive Eurasian Water-Milfoil.
The spread of this weed needed to be kept in check before populating the entire bay.
The spring and early summer of 2013 were colder and wetter than the previous years
and the bay water levels were higher. As such, the Eurasian Water-Milfoil growth was
slower to start and less aggressive this year than in 2011 and 2012. In light of this, a
smaller test pilot site using the Milfoil Weevil was introduced in an area where the
Eurasian Water-Milfoil growth was the thickest, adjacent to Bruce Hanscombe Park, to
assess its suitability in combating the Eurasian Water-Milfoil on Frenchman's Bay.
Eurasian Water-Milfoil
Eurasian Water-Milfoil (Myriophyllum spicatum) is an aquatic plant native to Europe,
Asia and Northern Africa that was introduced to North America in the 1940's and is
believed to have been introduced to Frenchman's Bay in the 1960's. This plant is
problematic due to its aggressive growth, forming large floating mats that prevent light
penetration for the native aquatic plants, depleting oxygen levels and adding nutrients to
the water during plant decay. This in turn displaces the natural aquatic vegetation
impacting fish and wildlife, increases algae growth and degrades the water quality. Due
to its density, Eurasian Water-Milfoil impedes navigation of both large and small boats
by binding up propellers, keels and paddles. It increases threat to public safety and
may eventually have an economic impact, affecting property values around the bay,
tourism and retail services.
Allies of Frenchman's Bay Association
During the fall of 2012, the following organizations and businesses were invited to be
part of the Allies of Frenchman's Bay Association (formerly the Frenchman's Bay
Eurasian Water-Milfoil Steering Committee):
• Pickering East Shore Community Association (PESCA)
• West Shore Community Association (WSCA)
• Frenchman's Bay Yacht Club
• Pickering Harbour Company
• Pickering Auxiliary Rescue Association (PARU)
• Swan's Marina
• DSCC No. 185 (Dock ominium)
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Report ENG 01-13 October 7, 2013
Eurasian Water-Milfoil Weed — Frenchman's Bay Page 3
• Pickering Dragon Boat Club
• Pickering Rouge Canoe Club
The Toronto and Region Conservation Authority and City of Pickering were also invited
to attend as stakeholders of the Bay.
A number of the Allies of Frenchman's Bay Association members have spent a
significant amount of time researching Eurasian Water-Milfoil and the various
management tools that have been used to control the plant historically. They have
spoken with other municipalities that have been combating this issue to get an
understanding of what has been tried and what methods have been successful. Some
of the methods being used include:
• Mechanical Harvesting
• Rotovation (underwater rototilling)
• Continuous Laminar Flow Aeration System
• Hydraulic dredging
• Herbicide
• Biological weevils
Through the research done, they are recommending that an integrated management
plan approach be used. This includes the use of biological weevils in areas not affected
by boat traffic and adjacent to natural shorelines. Areas along hard shorelines and
around docks could be treated with a Ministry of Environment approved aquatic
herbicide (Reward). Hydraulic or pneumatic dredging is recommended along key
navigation channels as a means to deepen the channel and remove the problematic
aquatic vegetation. The Continuous Laminar Flow Aeration System is being further
researched to confirm its costs and suitability for use in dock areas.
Milfoil Weevil
The milfoil weevil (Euhrychiopsis lecontei) is a marine insect which is native to North
America that specifically feeds on Eurasian Water-Milfoil. The weevil, which is fully
aquatic, spends the summer submersed on plants, producing 3 to 4 generations over
that time. The last generation of adult weevils develop wing muscles which enables
them to migrate to shore to overwinter in dry soil and leaf litter. An adult weevil grows to
be 2 to 3 millimeters in length.
The milfoil weevil destroys the water-milfoil plant by `mining' into the stem and eating it
from the inside out, disrupting the flow of carbohydrates and nutrients that give the plant
the ability to grow in the summer and survive in the winter. The plant also loses its
buoyancy and will sink to the bottom of the water as it dies, leaving an opening for the
desirable aquatic plants to re-establish. Milfoil Weevils are naturally found in the area
and have no known negative impacts on people, animals, fish or other vegetation.
In order to combat the Eurasian Water-Milfoil, a company called Milfoil Solution Inc.
recommended stocking the bay with a significantly higher number of milfoil weevil than
97
Report ENG 01-13 October 7, 2013
Eurasian Water-Milfoil Weed — Frenchman's Bay Page 4
what is naturally found in the water, starting with 40,000 in the first year, and 35,000 and
10,000 in the following two years. The weevil stocking occurs in June to early July. An
initial survey is conducted prior to stocking with a follow-up survey 6 to 8 weeks later
after the weevils have established multiple generations in order to track progress.
Reward Herbicide
One of the herbicides being considered is Reward Landscape and Aquatic Herbicide.
This herbicide is non-selective and as such will kill the milfoil as well as other native
plants such as Coontail and Duckweed. As such, it should only be used around dock
areas and hard shorelines where it is not suitable to stock the milfoil weevil. Reward
herbicide has been approved for use by the Ministry of Environment though permits will
still be required from the Ministry of Natural Resources for each application.
2012 Estimated Costs for Milfoil Weevil and Herbicide Treatments
The Allies of Frenchman's Bay Association obtained quotations during the summer of
2012, for treatments using weevils and herbicides for a total estimated cost of $169,521
over four years. Based on these estimated costs, they were proposing a four-year
funding contribution plan that included funding from the City of Pickering for
approximately 35% of the cost. The balance of the costs would be covered through
funds provided by the other stakeholders and fundraising. The amount requested from
the City was $30,000 for year 1 (2013), with projected costs of$20,000 for year 2
(2014), $10,000 for year 3 (2015) and $750 for year 4 (2016) for a total of$60,750. The
cost for dredging would be borne solely by the boat clubs and dock owners.
2013 Treatments and Associated Costs
Due to the spring and early summer of 2013 having cooler temperatures and more rain
and the bay having higher water levels, the milfoil weed had a late start and its growth
was not as extreme as the previous two years. As such, it was decided that a test pilot
site would be established in an area where the Eurasian Water-Milfoil growth was the
thickest adjacent to Bruce Hanscombe Park. In early August, 20,000 Milfoil Weevil
eggs and larvae were stocked in this area, to weaken the standing milfoil population
over the remainder of the 2013 season and to build an overwintering population of
weevils that will return to the water early in 2014. Milfoil Solutions, who provided the
treatment will monitor their success and provide further recommendations in 2014,
depending on the future growth of the milfoil. The cost for the treatment for 2013 was
$23,600 with the City's share being $8,325.00.
Frenchman's Bay Yacht Club dredged the area around their docks and a channel to the
harbour entrance during the spring of 2013. Pickering Harbour Company are proposing
to dredge around their docks during the fall of 2013.
TRCA has advised that they will also continue to monitor the plant growth within
Frenchman's Bay.
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Report ENG 01-13 October 7, 2013
Eurasian Water-Milfoil Weed — Frenchman's Bay Page 5
.=.
_ _.....rte y 410*s ," •
F.. -rte. �_.,e„C '.r•�`i"° _ - J.--------�^'' "`"""'"` _ ;
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View looking north across the ba with Eurasian Water-Milfoil in foreground (2012)
*1,
!grit': -n k. n n .m • nti�` i -1
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Eurasian Water-Milfoil around boat docks (2012)
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Report ENG 01-13 October 7, 2013
Eurasian Water-Milfoil Weed — Frenchman's Bay Page 6
Attachments:
1. Frenchman's Bay Eurasian Water-Milfoil Management Plan (November 30, 2012)
2. EWM 101 Eurasian Water-Milfoil —The Basics
3. Milfoil Weevil —Questions and Answers
4. Frenchman's Bay Eurasian Water-Milfoil Steering Committee - Funding
Contribution Plan
5. Frenchman's Bay Aquatic Vegetation Survey 2012
Prepared By: Approved/Endorsed By:12fit _
er
Arnold Mostert OALA Richa Holborn, P. Eng.
Senior Coordinator, Landscape &Parks Di or, Engineering & Public Works
Development
AM:Ir
Recommended for the consideration
of Pickering Ci Council
• .z3 /2O!3
Tony Prevedel, P.Eng.
Chief Administrative Officer
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A 1ACkMEN7 1.:.. 2 v,r_[J P,EP3RT# EN G, 1 -1
EW M 101 Eurasian Wa#c
r-Milton
THE BASICS
What is it? Eurasian water-milfoil(Myriophyllum spicatum) is an
aggressive, invasive,rooted aquatic perennial plant.
What is its origin? Eurasian water-milfoil(EWM) is native to Europe, Asia,
and Northern Africa, and it was likely introduced to North
America in the 1940s. EWM has spread to 45 U.S. states
and three Canadian provinces(Ontario,Quebec, and British
Columbia).
Why is it a AN ECOLOGICAL THREAT
problem? EWM:
• Forms large, floating mats of vegetation preventing light
penetration for native aquatic plants.
• Displaces natural aquatic vegetation,negatively
impacting fish and wildlife habitat.
• Depletes aquatic oxygen levels and adds nutrients to the
water during plant decay which can potentially
increase algae growth and degrade water quality.
• Plant fragments can travel long distances out of water(if
kept moist) by boat,boat trailers, bait buckets, etc.
A HUMAN HEALTH CONCERN
EWM:
• Can increase threats to public health and safety.
A RECREATIONAL IMPEDIMENT
EWM:
• Impairs recreational use such as swimming, boating,
and fishing.
AN ECONOMIC FACTOR
EWM:
• Reduces waterfront property values and impacts real
estate sales.
• Impacts water related tourism,hospitality, and retail
services.
• Increases expenditures on prevention and control if
proactive action not taken.
114
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el
•
What does it EWM has delicate, feather-like leaves comprising of 12 - 16
look like? pairs of leaflets on each leaf Leaves are mostly the same
length;the tips are square with a snipped off appearance.
Leaves are arranged in whorls (circles)of three to five
leaves around each stem. The stem is thick as or thicker
than a pencil, and is long and spaghetti like in appearance.
EWM plants can grow to 9 metres(30 feet)in length with
the majority of the branching occurring at the surface.
How does it EWM grows quickly and spreads easily. It grows in depths
grow and of up to 8 metres of water....deeper depths if the water is
spread? clear...and is tolerant of many water pollutants(e.g. sodium,
chloride,etc.). It grows in any type of aquatic substrate:
it prefers sand to silt type substrates.
While EWM produces seeds, it reproduces primarily
through fragmentation,which occurs naturally
when the plant flowers at the end of its annual growing
season. Fragmentation can also occur through manmade
disturbances such as power boating and sailing.
Once fragmented,the pieces are dispersed by wind and
water movement, eventually sinking to the bottom and
taking root. Once rooted the plant is further propagated
through root division ....runners that creep along the
bottom.
EWM tends to invade disturbed areas(e.g. altered
waterways)where native plants cannot adapt to the
alteration;EWM does not spread rapidly
into undisturbed areas where native plants are well
established.
How do you Once established EWM can not be eradicated. It can only
eliminate EWM? be controlled through various management methods.
115
A TArK EN 3._. TO REPORT# E c l-'13
of
MILFOIL WEEVIL (Euhrychiopsis lecontei)
QUESTIONS AND ANSWERS
Q: How big is an adult weevil?
A: The adult weevil grows to 2—3 mm in length(about this size: • ).
Q: What is its food source?
A: The marine insect which is native to North America appears to prefer Eurasian
water-milfoil over its native host,northern water-milfoil.The milfoil weevil is
highly specific to water-milfoils.
Q: What is the life cycle of the weevil?
A: Like other insects,the weevil goes through the egg, larvae, and pupa stages before
reaching the adult stage. The weevil has the potential to cause damage to water-
milfoil plants at every stage in its life cycle.
The weevil is fully aquatic and spends the summer submersed on plants. The adult
female weevil lays approximately 2—3 eggs per day on the growing tips of
the plant.The eggs hatch into larvae after 3—6 days and the larvae begin feasting
on the plant's growing tips for several days.The larvae then burrow into the plant's
stems where they feed on the tissue within the stems for 5— 10 days. After 7-12
days in the pupal stage,the weevil emerges as an adult where it feeds on the upper
leaves of the milfoil plants while reproducing. Weevil reproduction throughout the
summer may produce 3—4 generations of weevils.The last generation of adult
weevils develops wing muscles which enable the weevil to migrate to shore where
it overwinters in dry soil and leaf litter.
Q: What effect does a weevil have on Eurasian water-milfoil?
A: The weevil destroys the whole plant by `mining' into the stem and eating it from
the inside out.The tunneling disrupts the flow of carbohydrates and nutrients,
impacting the plant's ability to grow in the summer and survive in the winter.The
plant also loses its buoyancy due to the weakened stems and will sink to the bottom
as it dies.
As a dying Eurasian water-milfoil plant sinks to the bottom an opening in the plant
canopy is created enabling other desirable aquatic plants to grow and eventually
replace the invasive species.
116
A 1 T1ACkNENT ..w'_ TO REPORT# N GI. 1-(
Q: What factors impede the reproduction of weevils?
A: Water temperature,parasites,pathogens,water depth,and other factors affect the
population of weevils. High nutrient levels in the water will accelerate Eurasian
water-milfoil growth making it difficult for weevils to control. Water bodies with
natural shorelines will achieve higher weevil densities than shorelines with
vegetation replaced by retaining walls, rip rap,mown grass,and sand.Natural
shorelines may provide better habitat for overwintering adult weevils. As the
density of Eurasian water-milfoil decreases,the weevil population will gradually
decline to a self-sustaining natural population level.
Q: Will weevils become problematic by infiltrating shoreline homes or biting
household pets when they come on land in the fall?
A: No. Milfoil weevils have no known negative impact on people,animals,fish or
desirable vegetation.
117
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