Executive summary – a lake in change

Over the past 15 years, Ontario and its partners have taken a wide range of actions to help protect and improve the ecological health of the Lake Simcoe watershed.

Protecting and restoring Lake Simcoe and its watershed is a key part of the Lake Simcoe Protection Plan (the plan). The Lake Simcoe Protection Plan aims to protect the health of the Lake Simcoe watershed through various ecological indicators and targets, along with policies for monitoring and research.

This report combines the Minister’s 15-Year Progress Report and Minister’s 2024 Annual Progress Report on Lake Simcoe into one document and builds on the Minister’s 10-Year Report on Lake Simcoe up to 2024. It addresses the five-year progress report and the 2024 annual report requirements under the Lake Simcoe Protection Act and describes the collaborative efforts taken to implement the Lake Simcoe Protection Plan and progress towards its objectives. A complementary Lake Simcoe 15-Year Monitoring Report provides a detailed description of the results of monitoring programs and research up to 2022.

This report covers:

  • actions taken under the key priority areas to address the issues most critical to the health of Lake Simcoe, supported by data and trends from monitoring programs:
    • the health of aquatic life for coldwater and warmwater fish
    • protection and rehabilitation efforts for shorelines and natural heritage
    • water quality
    • agricultural trends in Lake Simcoe
    • invasive species
    • understanding variability in a changing climate
  • actions taken in 2024 to protect Lake Simcoe
  • key considerations moving forward
  • advice from the Minister's Lake Simcoe Coordinating and Science Committees (see appendix)

Lake Simcoe has been shaped by a long history of interrelated pressures. Changes to the natural landscape and stressors, such as nutrient inputs, invasive species, and climate change, caused significant impairment to the lake, resulting in fisheries collapse, poor water quality, and degraded habitats. Since these environmental changes were first observed in the 1970s, Ontario has consistently collected data on important indicators of lake and watershed health – setting the foundation for many policies and targets outlined in the plan. Ontario continues to use a collaborative approach to implement the plan, and cooperative actions are being taken by watershed partners, including all levels of government, First Nations and Métis communities, local conservation authorities, Ontario universities, local non-governmental organizations, as well as property owners and visitors to the watershed.

Three provincial ministries collaborate to guide the plan’s implementation and monitor changes in the environment that indicate progress from our efforts:

  • The Ministry of the Environment, Conservation and Parks (MECP) continues to coordinate the adaptive management of the plan and deliver work related to the management, conservation, and protection of water resources, as well as climate change mitigation and adaptation. They also lead the long-term water quality monitoring in the lake and collaborate with the Lake Simcoe Region Conservation Authority to monitor the tributaries of the watershed and to research key water quality topics.
  • The Ministry of Natural Resources (MNR) leads monitoring and research, and delivers on-the-ground work related to fisheries management, natural heritage (for example, woodlands, wetlands), and important ecological areas (such as shorelines), and biodiversity. They also coordinate and support partners to address invasive species, including the regulation of high-risk threats, and the implementation of prevention and response actions.
  • The Ministry of Agriculture, Food and Agribusiness (OMAFA) continues to lead work related to the preservation and enhancement of agricultural lands, nutrient-management planning, soil conservation, and local agricultural production in the watershed. They also monitor data on agricultural trends in the watershed using Statistics Canada products such as the Census of Agriculture.

The current programs are adaptable to changing conditions in the watershed and new information, to ensure we take the best action to manage threats. These ministries regularly review monitoring requirements and priorities to ensure that the right data is being collected to inform the adaptive management process and that monitoring efforts continue to be complimentary.

Progress to date

Building on the Minister’s 10-Year Report on Lake Simcoe, Ontario has continued its monitoring programs to track improvements and changes in the key indicators of the plan and assess set targets.

The province’s monitoring continues to show encouraging signs of improvement for the lake:

  • overall total phosphorus has decreased significantly, which means less nutrients available to contribute to excessive plant and algae growth
  • oxygen levels have improved, which is beneficial to aquatic life
  • Lake Simcoe continues to support a thriving warm/cool water recreational fishery
  • some cold-water fish communities, such as Lake Whitefish, are showing more stability, and Cisco (Lake Herring) are showing signs of recovery

In addition to the signs of recovery, some challenges remain:

  • stressors such as climate change and invasive species have altered how the lake functions
  • Lake Trout populations are declining

Priority: restoring the health of aquatic life within the Lake Simcoe watershed

The health of aquatic life and fish communities are a key indicator of the overall health of aquatic ecosystems. The Lake Simcoe Protection Plan sets out priorities to improve the health of Lake Simcoe and restoring aquatic life is one of its main objectives.

In response to results from the fisheries monitoring program on Lake Simcoe, the Ministry of Natural Resources (MNR) has increased the number of Lake Trout being stocked in Lake Simcoe and has added an additional strain of Lake Trout being stocked. MNR has established new stocking locations for Lake Trout and Lake Whitefish that are close to deep water and known spawning shoals to increase the chance of survival of stocked fish.

A shift has been made from the Offshore Benthic Index Netting method to the standard North American Index Netting, which is the standard used to monitor all aquatic inland lake fishery resources.

Ontario has continued to research the recovery of Lake Simcoe’s Cisco (Lake Herring) population, using fisheries sonar (hydroacoustic) surveys to estimate numbers and size of Cisco as well as other open water (pelagic) species. The ministry has been surveying newly hatched (larval) fish and their food source, zooplankton, to better understand factors impacting the survival of young Cisco.

The province is tracking the movements of important coldwater species to understand how stressors are impacting these populations.

In 2024, MNR took the following actions to protect and restore the health of aquatic life:

  • Conducted research and monitoring to improve understanding of aquatic health and the status of fish populations, including:
    • Continued to evaluate the recovery status of the cold-water fish community of Lake Simcoe using hydroacoustics and studying the diet and growth of larval fish. A hydroacoustic survey and data analysis were conducted to assess pelagic fish populations. The analysis of larval fish data included a comparison to results from Lake Huron.
  • Assessed the survival rates of stocked Lake Trout and lake-wide movement patterns of stocked and wild Lake Trout and Lake Whitefish through ongoing telemetry research. Additionally, adult Lake Whitefish were tagged. Analyses of lake-wide fish movement data were conducted. Further details are provided below:
    • Conducted monitoring of fish and fisheries to support management actions, including Small Fish Biodiversity sampling, Summer Recreational Angler Survey, Winter Recreational Angler Survey, Broad-scale Monitoring Survey, and Lake Whitefish Egg Collections.
  • Continued implementing actions related to the Lake Simcoe Fish Community (LSFC) Objectives and the plan, including keeping the coldwater fish community healthy. Supported partners like LSRCA by giving technical advice and approvals for monitoring.
  • Maintained communication with the Lake Simcoe Fisheries Stakeholder Committee (LSFSC) and the Lake Simcoe Fisheries Management Committee (LSFMC) and have held regular meetings with both committees. MNR has utilized meetings with the LSFSC and the LSFMC to provide advice and inform fisheries management decisions on Lake Simcoe.
  • New stocking locations were utilized for Lake Trout and Lake Whitefish. These sites are close to deep water and known spawning shoals.
  • MNR continues to use current fish data (for example, mapped spawning shoals) when reviewing approvals under the Public Lands Act to protect fish from the impacts of work in and around the water during spawning and other critical life stages.

Priority: improve the health of the ecosystem by protecting and rehabilitating important areas, such as shorelines and natural heritage

Building on the Minister’s 10-Year report on Lake Simcoe, Ontario has continued to fund projects to protect and improve key natural heritage features such as woodlands and wetlands and their functions, which are important to the overall health of the Lake Simcoe watershed. Some examples from the past 15 years include:

  • Invested $31 million through the Wetlands Conservation Partner Program (WCPP) to restore and enhance wetlands across the province. Launched eight projects in the Lake Simcoe watershed, including the 435-acre Holland Marsh South Restoration led by Ducks Unlimited Canada, improving water quality and biodiversity within the Lake Simcoe watershed.
  • MNR collaborated with Ducks Unlimited Canada through the Eastern Habitat Joint Venture to restore over 100 acres in Holland Marsh and protect more than 60 acres in the Township of Eldon.

Furthermore, the ministry, in partnership with the Orillia Museum of Art and History and Lake Simcoe Region Conservation Authority (LSRCA), provided funding to support enhanced ecological resilience and community engagement initiatives to protect, improve, and restore natural heritage features within the Lake Simcoe watershed.

  • The Orillia Museum of Art and History received over $200,000 in 2021 and 2023 to run youth stewardship programs that combined art and science to teach students about caring for the environment.
  • LSRCA advanced its Natural Heritage System and Restoration Strategy, conducting geo-spatial analyses and working with the University of Toronto to develop a web-based platform for tracking natural cover.

In 2024, MECP took the following actions to protect and rehabilitate natural heritage areas:

  • Supported the Orillia Museum of Art and History with $67,560 for their stewardship project that taught local youth and community members about the value of natural shorelines and the benefits of growing native plants. With support from Parklane Landscapes, the museum encouraged people to participate in activities to protect and restore the health of Lake Simcoe.
  • Provided $199,708 to LSRCA to study how natural land cover in the watershed, including forests, wetlands, agricultural areas, and paved surfaces has changed over time This information will be made available in a public-friendly format, which will enable the public to understand how the watershed is changing over time and learn what they can do to improve the health of local forests, wetlands, grasslands and streams.
  • Provided $72,044 to LSRCA to support local stewardship actions by creating public friendly web-based tools to help people connect with information about the health of local shorelines, streams and wetlands.

Priority: improving water quality, including reducing loadings of phosphorus to the lake

The Lake Simcoe 15-year Monitoring Report shows that there has been improvement overall in deepwater dissolved oxygen concentrations, although there has been substantial year-to-year variation.

Degraded water quality continues to be a significant concern in Lake Simcoe and its watershed. Stresses from both urban and rural activities continue to change the landscape of the lake and increase the inputs of nutrients and pollutants to the lake, impairing the ecological functions of the watershed.

Since 2018, MECP has supported research and monitoring projects with the LSRCA and other conservation partners to monitor phosphorus loads entering the watershed, and better understand the changing relationship between phosphorus and dissolved oxygen to assess continued progress towards water quality targets. The ministry has supported projects to improve phosphorus loading estimates deposited from septic tanks, impervious buildings, urban riverine systems, and agricultural practices in the Holland Marsh polders. These projects have helped MECP and its partners bridge knowledge gaps and better understand the current state of water quality in the watershed and its tributaries.

Highlights of projects funded in 2024 to improve water quality include:

  • Provided $84,000 to the University of Guelph to support improving the estimates of how much septic systems contribute to phosphorus loads in the Lake Simcoe watershed.
  • Supported LSRCA with $231,925 to continue monitoring the amount of phosphorus and other nutrients entering the lake by conducting water sampling throughout the watershed and calculating phosphorus loads. This information will be made available in a public-friendly format. This will enable the public to understand how water quality is changing over time and learn what they can do to help improve water quality.
  • Provided the University of Toronto $130,200 to study how water temperature, light, and dissolved oxygen vary in space and time to better understand what affects oxygen levels in the lake.

The Lake Simcoe 15-Year Monitoring Report shows that oxygen and phosphorus levels have improved, even in years with high phosphorus loads. The findings suggest Lake Simcoe no longer appears to be functioning as previously understood. There appears to have been dramatic changes in the delivery to and cycling of phosphorus in the lake that have been largely driven by changes in the climate and new invasive species. MECP is working with LSRCA, the University of Toronto, and York University to better understand these changes in the lake

In 2024, the end-of-summer deepwater dissolved oxygen level in Lake Simcoe was 5.5 milligrams per litre (mg/L), which was not at the Lake Simcoe Protection Plan target of 7 mg/L. However, phosphorus concentrations in the lake have improved over time, with a lake-wide springtime average in 2024 of 6.64 micrograms per litre (ug/L).

Lake Simcoe Phosphorus Reduction Project

The Lake Simcoe Phosphorus Reduction Project (LSPRP) aims to improve water quality conditions in Lake Simcoe and create healthier, stronger communities across the region. Building on the Minister’s 10-Year report on Lake Simcoe, the province is continuing to take action to protect the watershed by reconfirming its investment of $24 million in this project in the 2024 Ontario Budget. The federal government also committed $16 million, for a combined total of $40 million dedicated to supporting the project.

In 2023, the minister requested that the Ontario Clean Water Agency complete a research study to provide key information to advance the LSPRP and to fill in gaps on how much phosphorus is available for removal through the project. Substantially completed in 2024, the study found that over the last 10 years, an average of 4.3 tonnes of phosphorus passed through the Art Janse Pumping Station each year, ranging from 2 to 8 tonnes depending on situations such as weather conditions.

While reducing phosphorus remains our focus, there is growing attention being given to other contaminants that affect water quality, such as road salt, pharmaceuticals, bacteria like E. coli, and microplastics.

Road salt and chloride

The Lake Simcoe 15-Year Monitoring Report reveals rising chloride levels in the lake. In 2024, the lake wide average was 61.2 milligrams per litre (mg/L), over double the lakewide average in 2000 of 29.8 mg/L.

For the past 10 years, Ontario has worked with LSRCA, Smart About Salt Council, and local municipalities to address this issue. MECP has supported capacity-building projects to develop and continuously improve technical salt application education modules, such as the Smart About Salt Council’s Essentials about Salt Program and best management practices for winter maintenance professionals and facility operators. This has resulted in:

  • reduced technical barriers such as language and technological barriers
  • improved end user education experiences for salt application professionals (such as bilingual and online courses)
  • improved design guidelines for institutional and commercial parking lots
  • optimized salt application practices in the winter through salt application technique best practices, improved equipment use
  • salt management guidelines for local municipalities to mandate for developers
  • increased use of alternative salt application methods, such as de-icers, to enhance environmental benefits
  • increased awareness of the rising chloride levels and Lake Simcoe’s vulnerability which has led to efforts to reduce long-term road salt run-off into the watershed and tributaries

Highlights from Ontario’s actions to reduce road salt runoff in 2024 include:

  • Provided Toronto Metropolitan University with $90,000 to study chloride levels in Lake Simcoe in the near and far futures and assess what further reductions of chloride are needed to protect aquatic life in the lake.
  • Continued supporting the Smart About Salt Council’s training and certification program to encourage the adoption of leading winter maintenance practices. The program promotes improved safe snow and ice control practices on parking lots and sidewalks to reduce the amount of road salt entering the environment.

Reducing water pollution from urban runoff

Since 2020, Ontario has supported a range of capacity-building and public awareness campaign projects led by the LSRCA and local municipalities to improve stormwater management and water quality within the Lake Simcoe watershed.

These projects developed technical support, educational tools and training for local municipalities and professionals to manage existing municipal stormwater systems and promote low impact development (LID) practices through educational resources, updating planning tools, and sharing best management practices that can be implemented into planning and design. Ontario also supported projects that engaged homeowners through shoreline naturalization campaigns and landscaping workshops on practices such as rain gardens, permeable pavements, and green roofs – all aimed at reducing urban and stormwater runoff, sediment transport, and pollutant loads from entering the Lake.

Furthermore, the province supported site-specific restoration projects in urban and rural areas to address flooding, soil erosion, and pollutant loads through specific plants in key tributaries - Kidd’s Creek, Scanlon Creek, Ramara Creeks and the Talbot River - reducing peak flows and total suspended solids from entering the watershed and its tributaries. Other initiatives include the development of a Receiver Monitoring Pilot Program to assess the effectiveness of stormwater infrastructure on local tributaries and the creation of a system-wide stormwater management strategy for the East Holland River watershed.

Other aquatic pollutants and nutrients

The province continued to support watershed partners in their work to reduce the amount of pollutants entering the lake and improve water quality in Lake Simcoe and its tributaries. Trends in other nutrients in the lake have not changed since the previous reporting. However, in a peer-reviewed study, MECP showed significant changes in the atmospheric deposition of many nutrients and chemicals to the Lake Simcoe watershed from 1995 to 2021.

Other aquatic pollutants have recently been monitored by MECP in Lake Simcoe and are reported in the 15-year monitoring report. Measured per- and polyfluorinated alkyl substances (PFAS) concentrations in 2023 were lower than in 2008 and were similar or slightly higher than in Lake Ontario. The sum of 16 PFAS compounds tested were all below Health Canada’s Drinking Water Objective. Additional contaminant sampling was performed in 2024 using passive samplers for the occurrence of pharmaceuticals and personal care products, and current-use pesticides. Analyses of the 2024 sampling are underway. These efforts support the Lake Simcoe Protection Plan’s objectives to protect, improve and/or restore water quality and reduce the discharge of pollutants into Lake Simcoe and its tributaries.

Highlights from Ontario’s 2024 actions to improve water quality include:

  • Continued to support research and data collection to examine the relationships between phosphorus, dissolved oxygen, water quality and aquatic life. Water quality and quantity monitoring information were used to track changes over time. Monitoring water quality, while supporting research in key areas, helps inform our adaptive management approach.
  • MECP carried out its 45th year of monitoring the water quality of Lake Simcoe in 2024. Since 1980, measurements of the physical, chemical, and biological condition of the lake have been collected and used to track changes in the lake and watershed over time, support research in key areas, and help inform the adaptive management of Lake Simcoe. These data are available at Lake Simcoe Monitoring - Dataset - Ontario Data Catalogue and Lake Water Quality at Drinking Water Intakes - Dataset - Ontario Data Catalogue. This work supports the plan’s objective to provide ongoing scientific research and monitoring related to the ecological health of the Lake Simcoe watershed.
  • Data reported in the Lake Simcoe 15-Year Monitoring Report, which presents a comprehensive overview of the collaborative efforts by various ministries, organizations, and academic partners to monitor and understand the complex changes occurring in Lake Simcoe and its watershed.

Agriculture in Lake Simcoe

Approximately 44 % of the Lake Simcoe watershed is agricultural land. footnote 1  Since the implementation of the plan, agriculture in the region has undergone significant changes. The number of farms is decreasing, while the average farm size is increasing. Land use is also changing as communities grow. Ontario and local farmers know that protecting soil health is critical for agricultural productivity and environmental protection. There are increasingly more fields with cover crops and crop residues on the soil surface in the fall to reduce soil erosion, retain nutrients, and add organic matter back into the soil.

  • OMAFA works closely with the agriculture and food sectors to promote sustainable food production and environmental protection. Farmers and food processors in the watershed may apply to the province-wide stewardship programs to support a range of best management practices on their farms and in their businesses that are made available under the Sustainable Canadian Agricultural Partnership agreement.

Over the past 15 years, OMAFA has supported projects that largely focus on soil health, water quality (especially phosphorus reduction), and water management.

Highlights from Ontario’s 2024 actions:

  • Provided $32,800 in funding to Holland Marsh Growers’ Association to develop a proposed 4R fertilizer management plan and standards for horticultural crops grown in soils rich in organic matter. Fertilizer Canada’s 4R program (Right Source @ Right Rate, Right Time, Right Place®) aims to improve nutrient management practices on agricultural land. 4R-Ontario is a voluntary fertilizer management program developed by Fertilizer Canada and implemented in partnership with agricultural organizations by agricultural input suppliers and farmers. Field crop producers are adopting 4R fertilizer management across Ontario, but a similar program does not yet exist for horticulture crop producers on organic soils. This could lead to a broader adoption of 4R management by horticulture crop producers and have demonstrable reductions in fertilizer losses to local water bodies.
  • Ontario College of Art and Design University received $125,000 to develop and test an innovative pilot project to bring various field data together into a new artificial intelligence and augmented reality visualization and learning tool for farmers. The system allowed farmers to see multiple sources of information for a demonstration field in a virtual visualization system so that they may better understand soil characteristics, crop production, and environmental issues. The tool is intended to enable farmers to make data-driven decisions, optimizing their farming operations and improving environmental management.
  • The Ontario Soil Network (OSN) trained 25 farmers to be Soil Leaders to share their own progressive farming practices with other farmers. OSN received $115,500 primarily for training the farmers to be expert communicators and to host education events. OSN seeks to improve Ontario's soils by connecting and supporting farmers across the province through training, access to research, and networking opportunities. The Soil Leaders and OSN also used social media, podcasts, and Let’s Talk Soil ads and videos to normalize soil health practices. Promoting “soil health influencers”, including to women farmers, supports lasting adoption of environmentally and financially sustainable agricultural practices. This model was employed across Ontario with an emphasis on the Lake Simcoe watershed.
  • University of Guelph received $137,500 for research to review and recommend improved and consistent laboratory methods so that farmers have more reliable soil fertility analysis to avoid over-fertilizing their crops. The agricultural lands of the Lake Simcoe watershed range from upland mineral soils to lowland organic soils and are capable of producing high quality crops. Farmers send soil samples to Ontario accredited laboratories to determine the soil fertility concentrations and fertilizer needs. Horticultural crop producers work to manage their fertilizers responsibly and they need reliable soil fertility analysis results to accomplish this. The soil test analysis for phosphorus in organic soils has variable results depending on soil laboratory methodology. This affects the farmers’ fertilizer application rate decisions.
  • Kawartha Conservation received $43,000 in funding to promote rural farm stewardship. Best management practice promotion will foster riparian management, phosphorus load reductions, and soil and water management in the Upper Talbot River watershed. The project targeted landowners with environmental awareness information, implemented a water monitoring strategy, and evaluated the impact of these actions. The public engagement activities focused on new farmers and other traditionally underrepresented landowners, aligning with the Kawartha Conservation’s mission of building new relationships and inclusivity while retaining relationships with existing stakeholders.

Projects undertaken with Lake Simcoe partners are showing many indicators of success, including:

  • progress on nutrient management with farmers and agricultural input retailers promoting the adoption of 4R fertilizer management
  • increased attention and education to new farmers and women who are taking on more significant roles in the agricultural community
  • research is providing new information about fertilizer application, microplastic risks from agricultural soils and improved pesticide management
  • vegetable processing facilities in the Holland Marsh are reducing water use and losses of soil and phosphorus that come from vegetable wash water

Priority: addressing invasive species

The plan identifies invasive species as a significant environmental concern. Invasive species are non-indigenous species that disrupt ecosystems by impacting native fish, plants, and wildlife. – and are the second leading cause of global biodiversity loss. They also hurt the economy both locally and provincially. Aquatic invasive species like quagga mussels have already had a major impact on Lake Simcoe’s food web and ecosystem. Quagga mussels blanket the lakebed and filter out microscopic aquatic plants and animals that are essential food for native species, especially small fish.

To combat invasive species threats, Ontario has taken a proactive approach. The Invasive Species Act provides a legal framework for the province to regulate high-risk invasive species and pathways – such as watercraft -that can introduce them.  All species identified on the Lake Simcoe Watch List are now regulated (either provincially or federally) – as is the requirement for watercraft to take preventative measures – such as the “Clean, Drain, Dry” approach. These actions have strengthened prevention and control efforts throughout the Lake Simcoe watershed.

However, addressing invasive species is a challenge no single organization or government can tackle alone. Ontario’s success in protecting Lake Simcoe relies on strong collaboration among governments, conservation authorities, Indigenous communities, local businesses, researchers, and the public. These partners work together to build awareness, share expertise, and coordinate action.

Ontario continues to work with conservation partners in the Lake Simcoe watershed to coordinate prevention, control, research, and management activities to help address the threat invasive species pose.

Outreach and prevention efforts in the Lake Simcoe region include:

  • promoting with the Ontario Federation of Anglers and Hunters’ awareness of the Lake Simcoe “Watch list” to boaters, anglers, marinas, bait shops, and shoreline residents
  • partnering with marinas, bait shops, and tourism businesses to share prevention tips
  • hosting outreach events like “Operation Boat Clean” and Operation Bait Bucket – to promote “Clean, Drain, Dry” practices
  • posting educational signage and billboards and signage throughout the watershed, including messages tailored for both open water and ice fishing seasons
  • engaging local residents in monitoring events and reporting activities to support early detection

The collaborative network proved its strength in July 2024, when the invasive aquatic plant water soldier was detected in Lake Simcoe at Cook’s Bay. Thanks to strong community awareness, the plant was identified, and an inter-agency response team was immediately mobilized.  In the weeks following detection, MNR provided funding to the Invasive Species Centre to launch a Water Soldier Working Group – a coalition of partners from across the Lake Simcoe watershed. This group is coordinating efforts in 2025 to monitor the spread and develop long-term plans to help manage the species. This swift coordinated response highlights how serious the issue of invasive species is taken across all levels and the widespread support to protect Lake Simcoe from new and existing invaders.

In addition to outreach and prevention, ongoing research and monitoring are essential to understanding and managing invasive species in Lake Simcoe. Since 2016, Ontario has supported projects that track the spread and abundance of invasive species and their impacts across the watershed and its tributaries. Results for some of these projects are provided in the Lake Simcoe 15-Year Monitoring Report, as well as information on specialized research projects.

Research initiatives include developing an ecosystem model of the Lake Simcoe food web to address invasive species knowledge gaps, assess and monitor their impacts on aquatic food web dynamics, and determine ecosystem resilience in the watershed to ongoing pressures. This work allowed scientists and managers to simulate different scenarios and inform adaptive management approaches that are grounded in science.

In 2024, the province provided $164,121 to LSRCA to examine how invasive species and climate change may impact water quality, algae, and biological communities in Lake Simcoe. This project aims to improve understanding of how water quality and the health of the aquatic ecosystem are changing over time.

Priority: understanding variability in a changing climate

Although the amount of water in rivers and lakes naturally varies throughout the year, climate change can greatly impact the seasonality of the water cycle. Heavy rainfall and winter melting can increase contaminants runoff into the lake, while warmer summers can increase the duration of low flow conditions that impact the water available to people and aquatic ecosystems. Both high and low lake levels can contribute to increased shoreline erosion, causing sedimentation and water quality concerns.

Many changes due to climate change are outlined in the Lake Simcoe 15-Year Monitoring Report. Environment and Climate Change Canada data shows rising air temperature and shifting precipitation patterns. Lake Simcoe's surface water temperatures during ice-free months have risen, and the duration of ice cover has shortened due to later freeze and earlier thaw dates. These findings highlight the need to improve the watershed's capacity to adapt to climate change.

Over the past 15 years, the province has funded climate change projects to better understand the changes occurring in Lake Simcoe and address knowledge gaps. Researchers have investigated the effects of climate change on Lake Simcoe, focusing on how excessive nutrient loading contributes to algal growth and how climate shifts influence dissolved oxygen levels during ice cover periods. Another study linked rising dissolved organic carbon levels to changing climate patterns. These findings have enhanced understanding of climate change impacts and informed adaptive management strategies for the Lake Simcoe watershed. MECP has supported capacity-building projects, including vulnerability assessments to evaluate how sub-watersheds respond to changes in agriculture, water quality and quantity due to climate change.

The ministry has also supported First Nation communities’ projects to create climate adaptation plans that combine traditional ecological knowledge with western science. These efforts support land use planning, prioritized management actions and contribute to the Lake Simcoe Climate Change Adaptation Strategy.

Highlights from Ontario’s actions in 2024 to better understand climate change variability include:

  • Provided $100,789 LSRCA to study ways to strengthen the City of Barrie’s infrastructure against flooding caused by climate change. This information will be made available in a public-friendly format, to help residents understand how the watershed is changing over time and take actions to improve the health of local forests, wetlands, grasslands, and streams.
  • Provided $115,500 to York University to study the impact of changing winter conditions on water quality under ice. This study will improve the understanding of how climate change and other factors may affect Lake Simcoe.

Moving forward

The Ontario government recognizes the importance of Lake Simcoe and is committed to protecting the lake's ecosystem. The stressors facing the Lake Simcoe watershed continue to be complex and compounding, and climate change continues to affect the local ecosystem. The continued pressure from urbanization and growth, and the need to control the pathways for new invasive species, will require innovative solutions.

This report demonstrates that our cumulative efforts to protect the lake are making a difference. We are making progress towards the objectives of the Lake Simcoe Protection Act and Plan through ongoing scientific research and monitoring, and evidence-based decision-making. Our work to reduce pollutants and nutrients of concern entering the lake, and to promote sustainable land and water uses, are driving positive change. We are actively working to prevent new invasive species from entering the watershed and managing the adverse effects from those that are already established. By helping communities improve their ability to respond to climate change, we are also protecting the elements that contribute to ecosystem health.

The Lake Simcoe legislation enshrined a framework to protect the health of Lake Simcoe over the long term and included the “building blocks” of our approach: monitoring, research, information sharing, management action and supportive actions on the ground. There is a long history of partnership in the watershed, and we have high-quality data and expertise to guide our actions.

We look forward to continued partnership with stakeholders and engaging the public to ensure we have strong protections for Lake Simcoe and ensure the watershed can continue to sustain one of Ontario's fastest growing regions for generations to come.

Appendix: recommendations from the Lake Simcoe Coordinating and Science Committees

The Lake Simcoe Coordinating Committee and the Lake Simcoe Science Committee are publicly appointed committees under the Lake Simcoe Protection Act. These committees continue to provide advice to the Minister of the Environment, Conservation and Parks on the implementation of the Lake Simcoe Protection Plan and the ecological health of the Lake Simcoe watershed.

Recommendations from the Lake Simcoe Coordinating Committee

In 2024, the Coordinating Committee advised the minister to emphasize community-based workshops which could be held via social media to show the public the efforts being made to reduce pollution entering the lake, and how they can participate in reducing pollutants. The committee also recommended working with other agencies to encourage planting of trees in the watershed and strongly emphasized the 3Rs reduce, reuse, recycle with real world hands-on examples.

The population diversity around all of Lake Simcoe is continuing to change. With that in mind, we strongly believe that in order to communicate effectively with this diverse population living in the watershed, we must communicate with them in their language. In addition, we must reach out to them using social media (i.e., Asian Television Network) to get the message across to them on the actions we all need to take to reduce pollution in Lake Simcoe.

With support from the ministry staff, social media quizzes could be used to help educate and inform the public on the health of the lake. These quizzes could provide indicators on how the public addresses and understands the work that is being done in the Lake Simcoe watershed.

We also believe that far more work needs to be done to stop invasive species from entering the lake. A good example of this is the fact that mystery snails can still be purchased on Amazon. In addition, despite legislation, oxygen weed plants are still available from gardening centers.

Recommendations from the Lake Simcoe Science Committee

The exponential increase in Dreissenid Mussel densities in the Lake Simcoe ecosystem and future modeling of integrated physical and biological processes in Lake Simcoe. This important work is vital now, given concerns over ecosystem impacts of a mussel population crash (as has happened elsewhere). The LSRCA and MECP teams are updating a Lake Simcoe ecosystem model but may need support as this is not a trivial task. Climate change is the second highest-priority research gap as local weather events have intensified. Winters are also warming, causing a significant shift in seasonal Soluble Reactive Phosphorus loads and stronger thermal stratification in summer months. The risk of resuspension of the Lake bottom sediment sources of phosphorus under anoxic conditions due to thermal and chemo stratification (due to road salts) is also a real risk and significant research gap.

A presentation by LSRCA staff to the LSSC on September 17, 2024, titled: “Lake Simcoe Water Balance & Phosphorus Load Calculation”, identified important knowledge gaps related to Total Phosphorus components for the mass balance calculation. Many physical, chemical, and biological processes in freshwater ecosystems mobilize the nutrient phosphorus from sediments, which in turn may contribute to the formation of harmful algal blooms. The partial and delayed recovery of water bodies in response to reductions in external nutrient loading is often caused by the internal cycling of phosphorus from the lake bottom sediments. A strategic area for future study should include a phosphorus mass balance within lake storage elements in the system, including the accumulated bottom sediments and biota that uptake and release nutrients at various points during their lifecycle.

The plan notes chlorides are contaminants of concern, and the monitoring data within Lake Simcoe and its tributaries show a steady increase in chloride concentration. The plan supports related research to understand the impacts of road salt and chloride on the health of Lake Simcoe and its tributaries. The MECP and LSRCA team was directed by the plan to implement an enhanced scientific water quality monitoring program, which includes chloride monitoring and reporting for tributary salt loads to Lake Simcoe. This monitoring has highlighted earlier salinization and uncontrolled non-point source discharges. Wastewater treatment plants may further intensify and prolong the lake’s summer stratification, potentially enhancing hypoxia hypolimnion and increasing internal loading, limiting nutrient phosphorus. Facilitate working group Freshwater Round Table coordinate discussion private contractors, commercial property owners, insurers, and environmental agencies. Not surprisingly primary barrier to reduce salt application in private parking areas is liability concerns challenge mitigated few northern US states. New Hampshire has the longest-standing legislation that protects contractors certified in winter ice management who can demonstrate that appropriate management practice has been followed. That legislation has been successfully defended in a court challenge. All parties in the Freshwater Round Table (contractors, property owners, insurance companies and environmental agencies) are in support of a similar approach in Ontario. The LSSC also endorses the New Hampshire approach as a major step to reduce chloride application in the Lake Simcoe watershed and across the province.

The plan refers to pharmaceuticals and personal care products and microplastics as emerging contaminants of concern. Research is recommended to better understand the impact of organic chemicals and emerging compounds, such as personal care products, pharmaceuticals and endocrine disruptors, and their effect on the health of aquatic species in Lake Simcoe. Pharmaceuticals, including hormones (estrogen), antibiotics (erythromycin), high blood pressure medicine (atenolol), stimulants (caffeine) and other bioactive contaminants are commonly detected in wastewater at high concentrations and are not adequately removed by septic systems. It is not clear to the LSSC what (if any) research has been completed to date, including cumulative loading impacts from private septic systems. Nevertheless, further investigation is recommended involving LSRCA about the stress that the growth of the population and climate change will impose on wastewater infrastructure in the watershed, and how effective effluent systems discharging to Lake Simcoe are now and in the future at removing these contaminants.

The plan raises concern about glyphosate, a widely used herbicide with known effects on soil biology. While considered environmentally safe due to rapid soil absorption and degradation by microbes, recent studies suggest that glyphosate-based herbicides can adversely affect the biology of mammals and may persist longer in the environment than previously thought. Broad glyphosate application can have unintended consequences on soil chemistry, particularly concerning the mobilization and availability of nitrogen and phosphate in the form of soluble reactive phosphorus. The long-term ecological effects on soil health and biodiversity remain areas of concern for ongoing research. Given the potential linkage between glyphosate nutrient runoff, further research is merited about the cumulative basin-wide applications, possible implications, ongoing attempts to manage phosphorus loading, and mitigating eutrophication. Lake Simcoe's proactive precision agricultural practices address this concern.

The LSSC raises concerns about Canada Goose numbers watershed increasing exponentially. Not only do Canadian geese have a total phosphorus loading effect, but they also contribute to human health concerns, economic burdens aesthetic lake portions. A workshop involving Health Units, relevant provincial ministries, First Nations, Canadian Wildlife Services, Ducks Unlimited, and other stakeholders should be convened to explore this issue and consider a Waterfowl Management Strategy.

The LSSC recommends a workshop be convened to explore Urban Sources of Nutrients, opportunities to reduce them, and justification of the need to reduce them. The topics to be explored at the workshop include sediment and erosion control practice and oversight, inspection and maintenance of LID on private property, SWM infrastructure maintenance by municipalities, managing uncontrolled urban areas, better SWM control on new development, offsetting policy effectiveness, and the effectiveness of LID.

The LSSC recommends that current agricultural best management practice programs be reviewed using strategic and targeted monitoring programs. Also, sufficient funding should be allocated immediately to complete appropriate modelling using a science-based and already validated tool(s) to help assess the effectiveness of the programs in reducing phosphorus loads to Lake Simcoe and its tributaries (which are provincial in scope) in light of climate change stressors in the watershed and seek constructive recommendations for future provincial plans that should address agricultural sustainability practices.

Remote sensing and artificial intelligence technologies to assess changes in lake water levels and changes in storage in the water balance. These new tools could also provide other value-added benefits, such as tracking the current “Water Soldier” proliferation within Cook’s Bay and serving as an early warning for harmful algal blooms, and a monitoring strategy for other vulnerable shoreline reaches of Lake Simcoe. Machine learning can be used for forecasting integrated water balance and water quality outcomes for unlimited future sub-watershed conditions; analysis of satellite imagery, filling critical gaps in historical data. These are just a few timely applications where the MECP / LSRCA team and First Nations may take a leadership role to also help facilitate growth in further developing emerging technologies with research institutions and/or private partners and implement available evidence-based tools as soon as possible.

Public involvement and education programs can support projects that educate and involve citizens in protecting water quality and biological resources. These programs can also reduce local pollution problems by connecting, preserving, and restoring habitat, mobilizing support from local environmental stewards, and collaborating with others for lasting results. LSSC recognizes and understands that active management of migratory species and protection of key jurisdictional matters do not preclude addressing multiple jurisdictional matters or making recommendations to address an issue impacting the aquatic health of Lake Simcoe. Addressing issues through these means requires planning and projects guided by monitoring. Public activities should account for planning, restoration, and monitoring activities and indicate broader community interest and understanding of the health of the Lake Simcoe basin. We understand that LSRCA is working towards specific measures of health for Lake Simcoe and its subwatersheds as part of their ongoing watershed planning program. The LSSC would like to serve as an advisory body for those efforts and select a suite of indicators from the watershed plan framework for use as a reporting tool for the plan. Coordinating with stakeholders, including the local Indigenous communities, environmental interest groups, and landowners, will ensure that the proposed management alternatives are technically and financially feasible and socially acceptable solutions.

Given that scoped research and real-time data collection activities are warranted, and to be administered by the MECP and LSRCA team, the LSSC recommends that First Nation and Métis communities (with an interest in Lake Simcoe) be engaged and provided access to future real-time (including remote sensing – satellite) data collection. This inclusivity will enable priceless opportunities for participating First Nation administrations and citizens to share insightful Traditional Ecological Knowledge and personal testimonials to further shape research programs and data collection activities involving water quality, fisheries habitat, and invasive species mitigation.

The Chippewas of Georgina Island First Nation have applied to the Federal Government to establish a connection between Georgina Island and the mainland in the Town of Georgina, Ontario. This Proposed Causeway project spanning approximately 2.6 km over land in the bed of Lake Simcoe, we submit, is a project that must have regard to the Lake Simcoe Protection Act.

The Lake Simcoe Protection Act, at Section 18(2), states that the Lake Simcoe Science Committee shall perform the following functions:

  1. Review the environmental conditions of the Lake Simcoe watershed and provide advice to the Minister with respect to:
    1. the ecological health of the Lake Simcoe watershed
    2. current significant threats and potential significant threats to the ecological health of the Lake Simcoe watershed
    3. potential strategies to deal with the threats identified under subparagraph (ii)
    4. the scientific research that needs to be pursued to support the implementation of the Lake Simcoe Protection Plan

We respectfully submit that it is incumbent upon your ministry, through the provisions of the Lake Simcoe Protection Act, specifically Section 18(2)(1), to ensure the ministry observes, monitors, and reviews all relevant studies conducted and submitted by the Proponent to maintain the ecological health of the Lake Simcoe watershed.

We look forward to working with your staff to advance our shared goal of improving the health of the Lake Simcoe watershed.