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Home My WebLink AboutOPS 18-22Report to Council Report Number: OPS 18-22 Date: December 5, 2022 From: Brian Duffield Director, Operations Subject: Mechanical Harvesting of Eurasian Watermilfoil Weeds in Frenchman’s Bay - Review of Results of 2022 Pilot Project - File: A-1440 Recommendation: 1. That Report OPS 18-22 from the Director, Operations regarding the mechanical harvesting of Eurasian watermilfoil weeds in Frenchman’s Bay 2022 pilot project be received for information; and, 2. That the appropriate City of Pickering officials be authorized to take the necessary action to give effect hereto. Executive Summary: In 2021, Council approved $50,000.00 in the Current Budget to fund a pilot project to remove invasive weeds from Frenchman’s Bay to enhance opportunities for recreational water activities. The City was prepared to hire a specialist contractor to harvest weeds in Frenchman’s Bay; however, the City was advised by the Pickering Harbour Company Ltd. (PHC) that by the Charter of 1853, prior to Confederation, Frenchman’s Bay’s waterbed and lands are owned and operated exclusively by PHC and are under their care and control. As a result, PHC was contracted to deliver a pilot project for the mechanical harvesting of Eurasian watermilfoil weeds in Frenchman’s Bay. The pilot project commenced on August 31, 2021 and was completed on September 24, 2021—later than the cutting window required by Fisheries and Oceans Canada. It should be noted that the method of mechanical harvesting performed by PHC for the 2021 pilot project used specialized equipment that emulsified the weeds, returning the material into the water rather than cutting and removing the weeds from the Bay. The results of the 2021 pilot project were inconclusive due to only a single cut, the late start of the cutting, and the emulsification method used. Therefore, staff recommended submitting a request for funding to the 2022 Current Budget to repeat the pilot project and suggested that it start as early as permitted by Fisheries and Oceans Canada. This request also included a revised harvesting methodology. As a result, on March 28, 2022, Council approved the 2022 Current Budget which included a total of $100,000.00 to continue with the pilot project. The City met with PHC and Toronto Region and Conservation Authority (TRCA) to discuss the method of weed harvesting used in 2021 and recommendations for the continuation of the 2022 pilot project. As a result of this meeting, it was determined that the best method of weed control in Frenchman’s Bay was the mechanical harvesting and removal of the weeds, rather than the previous year’s emulsification method. Report OPS 18-22 December 5, 2022 Subject: Mechanical Harvesting of Eurasian Watermilfoil Weeds Page 2 in Frenchman’s Bay The City consulted with stakeholders who use Frenchman’s Bay for recreational purposes to determine the most appropriate areas to cut during the 2022 pilot project. It was determined that cutting one lane of five acres oriented north to south would best benefit the Dragon Boat Club, Pickering Rouge Canoe Club, and small watercraft users. PHC agreed to cut an additional five acres, in a triangular pattern at their expense to accommodate the needs of small sail boat programming for the Yacht Club. The areas to be cut were marked appropriately with buoys for easy visual identification and follow up inspections to evaluate the pilot project. Discussion: On an annual basis, PHC completes weed harvesting, without weed removal, around the docks of Frenchman’s Bay Marina, Frenchman’s Bay Yacht Club, and an East/West oriented channel linking the two to the harbor entrance. The harvesting is normally undertaken twice during the growing season, but it may be completed up to five times per season if lower water levels accelerate weed growth. In 2022, PHC was contracted by the City to continue with a pilot project for the mechanical harvesting and removal of Eurasian watermilfoil and other weeds in the areas of Frenchman’s Bay as identified in the contract. An inspection by boat of the areas to be cut was completed on July 25, 2022. The purpose was to document and determine the density and height of the weeds to be cut. An aerial drone video was taken of the areas prior to the first cut to document and assist in determining the effectiveness of the cut method. The first cut was completed on July 30, 2022, and a video of the same areas were taken for comparison. The weeds were cut, harvested and stocked piled on PHC lands to dry and reduce the overall weight for disposal at a later date. The City conducted an inspection by boat of the cut areas to assess the effectiveness and success of the completed areas. It was observed that the cut area was very visible and many large fish were observed within this area. Overall, City staff determined the first cut to be successful. Four weeks later, a second harvesting of the weeds commenced on August 25, 2022 and was completed on September 3, 2022. Post cut videos were taken using an aerial drone by the same vendor for the purpose of comparison. City staff conducted a final inspection on September 9, 2022 and the observations appeared to validate the revised methodology of the 2022 pilot project. TRCA had been providing their support and expertise during the pilot project and verified that the 2022 pilot project methodology was better suited for a long-term weed management program. The main takeaways from the 2022 pilot project were as follows: • It is essential to use the entire allowable cutting season from the start of July to the end of August to maximize the control benefits of a second cut. • Harvesting and removal of the weeds from the Bay reduces the reseeding of cut weed. • The harvesting vessel used in 2022 seemed to be effective and efficient in the limited cut. • Freshwater Bryozoan, an aquatic invertebrate were found in Frenchman’s Bay during the harvesting and inspection. This species is an indicator of good water quality that lacks containments such as heavy metals. Report OPS 18-22 December 5, 2022 Subject: Mechanical Harvesting of Eurasian Watermilfoil Weeds Page 3 in Frenchman’s Bay • It would appear that approximately 90 percent of the weeds harvested from Frenchman’s Bay were Ceratophyllum Demersum, also known as coontail and that only 10 percent of the weeds harvested were Eurasian milfoil. The pilot projects identified the following challenges that will need to be addressed in a sustainable weed management program: • The minimum depth of water needed to operate the harvesting vessel prevents the weeds from being cut close to shore which can hinder small watercraft access. • Fluctuations in Lake Ontario water levels can decrease the relative depth to the top of the cut weeds as the water level drops after a successful cut. • The five acres cut twice in the 2022 pilot project only allowed one North/South channel suitable for kayaks and dragon boat activities but some distance from shore and a considerable distance from Bruce Handscomb Memorial Park located on the West side of the Bay. • Cutting a significantly larger area is a more efficient removal method for the cut weeds, as frequent returns to shore to empty the cut weeds is inefficient. Next Steps The two pilot projects have allowed for the development of a weed harvesting methodology that can be used in a weed management program and permit an increased level of small watercraft use of Frenchman’s Bay. There is no indication that the trend for increased weed growth in the Bay will decline and that climate change and upstream development may be contributing to the heavy weed growth observed in the past few years. The cutting contractor noted that phosphate is likely not a contributing factor of excessive weed growth as significant algae blooms occur in phosphate rich water and none was observed in the Bay. The contractor advised that higher nitrogen sources making their way into the Bay are a more likely factor in the weed growth. Staff, with the cooperation and assistance of TRCA, need to complete a water quality sampling and investigation. This will help to understand where the nutrients are coming from in both the upstream watershed and the Hydro Marsh. Given the unique ownership rights of PHC to control access to Frenchman’s Bay for weed control, staff will assess the appropriate method to participate in a weed management program moving forward considering the rights and responsibilities of both both parties. The 2023 Current Budget will reflect staff’s recommendation for funding to address the implementation of a sustainable and effective weed management program in 2023. Attachment: 1. Before and after photographs of first and second weed cuts Report OPS 18-22 December 5, 2022 Subject: Mechanical Harvesting of Eurasian Watermilfoil Weeds Page 4 in Frenchman’s Bay Prepared/Approved/Endorsed By: Original Signed By: Brian Duffield Director, Operations BD:sv Recommended for the consideration of Pickering City Council Original Signed By: Marisa Carpino, M.A. Chief Administrative Officer Attachment #1 to Report OPS 18-22 Canoe Cut Zone – First Cut on July 30, 2022 Pre-Cut (taken on July 16) Post-Cut (taken on August 5) Canoe Cut Zone – Second Cut on August 25, 2022 Pre-Cut (taken on August 5) Post-Cut (taken on September 9)