Reductions in phosphorus loads to Lake Winnipeg
Lake Winnipeg is the sixth largest freshwater lake in Canada, with its drainage basin stretching across 4 provinces and 4 US states. The land in the basin is mainly used for agriculture and is home to nearly 7 million people.
Phosphorus is a key nutrient for plant and algal growth that supports the lake's food web, including fish populations that sustain local fisheries. However, when phosphorus levels are too high, it can degrade water quality, as observed in Lake Winnipeg. Lake Winnipeg’s water quality has declined mainly due to excess nutrients and other pollutants from many sources throughout the basin. Since the mid 1990s, increased rainfall, runoff and flooding have contributed to higher nutrient concentrations and more frequent algal blooms.Footnote 1
Investments through the Canada Water Agency’s Lake Winnipeg Freshwater Ecosystem Initiative contribute to achieving Manitoba’s long-term goal of reducing phosphorus concentrations in the lake to 0.05 milligrams per litre (mg/L). This indicator shows the extent to which the projects completed in 2025 with funding through the Lake Winnipeg Freshwater Ecosystem Initiative have reduced the amount of phosphorus entering rivers and streams that flow into Lake Winnipeg.
Key results
Key results
- Projects completed in 2025Footnote 2 have prevented an estimated 1,810 kilograms of phosphorus from entering rivers and streams that flow into Lake Winnipeg
Estimated reductions in phosphorus loading in rivers and streams flowing into Lake Winnipeg Basin from Lake Winnipeg Freshwater Ecosystem Initiative projects, 2025
Data table for the long description
| Year | Estimated new phosphorus removal (kilograms of phosphorus per year) |
Total estimated phosphorus per user, including projects still effective at removing phosphorus from previous years (kilograms of phosphorus) |
|---|---|---|
| 2024 (baseline) | N/A | N/A |
| 2025 | 1,810 | 1,810 |
Note: N/A = not applicable. This table shows the estimated reduction in phosphorus loading to rivers and streams that flow into Lake Winnipeg resulting from projects completed through the Canada Water Agency’s Lake Winnipeg Freshwater Ecosystem Initiative in 2025. Year refers to fiscal year, which runs from April to March. The year 2025 therefore refers to April 1, 2024 to March 31, 2025. A baseline was established in 2024, following a change in methodology, including reduction calculation methods. For more information on the methodology, please consult the Data sources and methods section.
Download data file (Excel/CSV; 1.43 kB)
How this indicator was calculated
Note: This figure shows the estimated reduction in phosphorus loading to rivers and streams flowing into Lake Winnipeg resulting from projects completed through the Canada Water Agency’s Lake Winnipeg Freshwater Ecosystem Initiative in 2025. Year refers to fiscal year, which runs from April to March. The year 2025 therefore refers to April 1, 2024 to March 31, 2025. Asterisk indicates the baseline established in 2024, following a change in methodology, including reduction calculation methods. For more information on the methodology, please consult the Data sources and methods section.
Source: Canada Water Agency (2025) Lake Winnipeg Freshwater Ecosystem Initiative.
In the absence of human development, levels of phosphorus in Lake Winnipeg are high when compared to lakes around the world, due to naturally elevated phosphorus levels in the watershed originating from prairie soils. However, lake sediments tell a story of dramatic increases in lake phosphorus starting in the mid-1990s from human-related factors such as agricultural and urban runoff and wastewater. Reducing the amount of phosphorus that enters Lake Winnipeg helps to improve water quality and the ecosystem health of the lake.
The amount of phosphorus entering rivers and streams in the Lake Winnipeg basin is being reduced by actions such as:
- building retention ponds that intercept water flow across the landscape and capture nutrients
- stabilizing riverbanks and lake shorelines
- restoring and conserving wetlands
- advancing innovative technologies related to small-scale wastewater and effluent treatment
- implementing management practices that prevent livestock from accessing rivers and streams
About the indicator
About the indicator
What the indicator measures
The Reductions in phosphorus loads to Lake Winnipeg indicator shows the estimated extent to which projects initiated in 2024 and completed in 2025 with funding through the Lake Winnipeg Freshwater Ecosystem Initiative reduced the amount of phosphorus entering rivers and streams flowing into Lake Winnipeg.
Why the indicator is important
Clean fresh water is an essential resource as it sustains aquatic plant and animal biodiversity. We rely on it for economic activities such as agriculture, energy production, tourism, commercial fishing and manufacturing, and for domestic use such as drinking and washing. Degraded water quality damages the health of freshwater ecosystems and can disrupt recreational activities such as swimming, boating, fishing, and can negatively impact Indigenous traditional uses.
When phosphorus levels in water become too high, aquatic plant growth can become excessive and harmful to the ecosystem health of the lake. The decay of excess plant material can reduce the amount of oxygen available for fish and other aquatic animals. High nutrient levels can also lead to harmful algal blooms, which can kill animals that live in or use the water and affect human health. Addressing human-related sources of excess nutrients, including phosphorus, are critical steps toward improving the overall health of Lake Winnipeg.
Related initiatives
This indicator contributes to the Sustainable Development Goals of the 2030 Agenda for Sustainable Development. It is linked to Goal 6, Clean Water and Sanitation and Target 6.3, "By 2030, improve water quality by reducing pollution, eliminating dumping and minimizing release of hazardous chemicals and materials, halving the proportion of untreated wastewater and substantially increasing recycling and safe reuse globally."
The indicator also contributes towards reporting on Target 7 of the Canada's 2030 Nature Strategy: "Reduce pollution risks and the negative impact of pollution from all sources, by 2030, to levels that are not harmful to biodiversity and ecosystem functions and services."
Related indicators
The Phosphorus levels in the offshore waters of the Canadian Great Lakes, Nutrients in the St. Lawrence River, and Nutrients in Lake Winnipeg indicators report the status of total phosphorus and total nitrogen levels in these 3 ecosystems.
The Phosphorus loading to Lake Erie indicators report on the total phosphorus loadings flowing directly into Lake Erie or from its tributary rivers.
The Water quality in Canadian rivers indicators provide a measure of the ability of river water across Canada to support plants and animals.
Data sources and methods
Data sources and methods
Data sources
The Canada Water Agency estimated the reduction of phosphorus loads entering rivers and streams flowing to Lake Winnipeg as a part of the Lake Winnipeg Freshwater Ecosystem Initiative.
More information
The estimated phosphorus reductions are calculated using the results from projects initiated since April 2024 and completed by March 2025 with funding through the Lake Winnipeg Freshwater Ecosystem Initiative. These estimates are derived following a standard framework and set of methodologies using local data on the effectiveness of specific practices in reducing phosphorus. Project reports are collected annually, starting with projects completed in 2025.
Drainage basin of Lake Winnipeg
Source: Environment and Climate Change Canada (2017)
From April 1, 2024 to March 31, 2025, the Canada Water Agency's Lake Winnipeg Freshwater Ecosystem Initiative funded 11 projects that directly reduced phosphorus loading.
The Canada Water Agency funds partner-led projects through contribution agreements with funding recipients. Sometimes, the Agency may amend an existing project to add more activities and funding rather than initiating a new project. When this happens, the project is not counted as a new project in the annual totals. However, any phosphorus reductions from the added activities are still included in this indicator.
Methods
Phosphorus reduction for each project is calculated using a standardized overarching framework and an underlying set of methodologies, based on the best available science and site-specific information, to give an estimate of phosphorus reductions over time. This process includes the collection and reporting of project-specific information starting with projects completed in 2025, and uses calculations and information derived from regional studies.
More information
Once a project has been initiated, its continued ability to reduce phosphorus from entering rivers and streams in the Lake Winnipeg Basin is assessed and accounted for on a yearly basis. Yearly estimates of reduction in phosphorus loading indicate how much phosphorus is prevented from entering rivers and streams due to management practices that are actively reducing phosphorus that year.
Phosphorus removal estimates for each project are based on site-specific data, including
- Baseline phosphorus load estimates, which are derived from factors describing pre-project land management or land use, or that rely on data describing pre-project livestock management and related phosphorus loading
- Projected phosphorus reduction benefits, which reflect the impact of beneficial management practices adopted for the project, either by reducing sources directly or by intercepting phosphorus before it reaches downstream water bodies
Both baseline and reduction estimates depend on localized conditions and are informed by the most current, regionally relevant scientific publications and/or expert opinion.
For more information on the phosphorus reduction framework, please contact the Lake Winnipeg Freshwater Ecosystem Initiative at lakewinnipeginfo-lacwinnipeginfo@cwa-aec.gc.ca.
Recent changes
From 2011 until 2024, this indicator was based on projects funded by Environment and Climate Change Canada’s Lake Winnipeg Basin Program. With the creation of the Canada Water Agency in November 2024, this work is now being led by the Agency. Under the new Lake Winnipeg Freshwater Ecosystem Initiative, the Canada Water Agency will continue to fund actions to help Manitoba achieve its long-term goal of reducing phosphorus concentrations in the lake to 0.05 mg/L. With the new Initiative, a revised approach and consistent framework to track nutrient-reduction efforts based on best available local science is now applied to the projects funded through the Lake Winnipeg Freshwater Ecosystem Initiative.
In past reports for this indicator, phosphorus loading reductions achieved each year over the life of the Lake Winnipeg Basin Program (2011-2024) were added cumulatively each year to give the total load of phosphorus removed from the basin since nutrient reduction projects were initially funded. As of 2024, yearly totals indicate how much phosphorus is prevented from entering rivers and streams due to active projects that year. This includes the yearly amount reduced from any past project that continues to remove phosphorus from entering waters in the basin.
Caveats and limitations
This indicator does not measure how estimated phosphorus reductions through the initiative compare to the total amount of phosphorus entering Lake Winnipeg or its tributaries each year. It also does not assess these reductions in relation to landscape processes, land use or activity changes within the basin that could influence phosphorus loading. The indicator estimates the total sum of reductions in annual phosphorus load delivered locally to rivers and streams at the site of each Canada Water Agency-funded project.
The indicator relies on the most appropriate equations to estimate reductions in phosphorus loading from the implementation of the projects.
Resources
Resources
References
International Institute for Sustainable Development (2024) A phosphorus Reduction Evaluation Framework for the Lake Winnipeg Basin Program. Freshwater Management Directorate, Canada Water Agency.
Related information
Lake Winnipeg Freshwater Ecosystem Initiative
Alternative format
Download the alternative format of the Reductions in phosphorus loads to Lake Winnipeg indicator (PDF; 427 kB)