Why Rescue Lake Simcoe?

The lake and the watershed’s wild inhabitants need clean water, forests, wetlands and streams to stay healthy. We benefit too from a clean environment and swimmable water.

What’s wrong?

Too much of the nutrient Phosphorus reaches the watershed’s streams, and the lake itself. This can cause excessive algae, weeds, and is the trigger for low oxygen levels in the lake’s deep water, which harms fish. There are many sources of Phosphorus and consequently, there are lots of solutions. The efforts made to improve the lake’s health are paying off, but the threats remain.

What does the Lake Need?

A sustained and coordinated effort. We need to bring down phosphorus from all of its sources, protect forests and wetlands, curb the spread of invasive species, and reduce the impacts of development.

Healthy, Connected Forests

Today we have almost enough forests and wetlands to buffer the watershed from the impacts of climate change and the stress of phosphorus pollution. But we are losing, not gaining, forests and wetlands.

Improved Water Quality

Development pressures on the watershed are huge, and where development and urbanization occur, lower water quality tends to result. Urban runoff called stormwater is the largest source of Phosphorus to Lake Simcoe, at 31% of the annual load.

Science and Policy

The Lake Simcoe Protection Plan is one of the policies that help steer our actions in the right direction. Its science-based targets drive municipalities, farmers, individuals, developers, the Lake Simcoe Region Conservation Authority and others toward the Plan’s objective of protecting, improving or restoring the ecological health of the Lake Simcoe watershed.

Where does the excess Phosphorus come from?

Urban Runoff & Stormwater
Phosphorus (P) loading to Lake Simcoe from existing urban areas is very high. Urban P loads are expected to increase in accordance with the population growth targets in the Growth Plan for the Greater Golden Horseshoe (Lake Simcoe Science Committee, 2012).
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Atmospheric Deposition
The downwards movement of phosphorus (P) from the atmosphere to Lake Simcoe and its watershed is a major contributor to the overall P load. It comes from agricultural areas, unpaved roads, aggregate extraction and construction sites (Lake Simcoe Science Committee, 2012)
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Rural & Agriculture Sources
Water runs across croplands and exposed soils, into streams that flow into the lake. The phosphorus (P) load from hay, pasture and cropland accounts for 17 T/yr of the 20 T/yr load from agricultural sources (Lake Simcoe Phosphorus Reduction Strategy, 2017).
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Sewage Treatment Plants
Sewage treatment plants, 14 municipal and one industrial, account for an average annual phosphorus load of approximately 5 T/yr to Lake Simcoe (Lake Simcoe Phosphorus Reduction Strategy, 2017).
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Septic Systems
The current phosphorus load from the residential and industrial septic systems located within 100 metres of Lake Simcoe is estimated at 4.4 T/yr, representing 6% of the total P load to the lake (Lake Simcoe Phosphorus Reduction Strategy, 2017).
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Holland Marsh & Polders
The Holland Marsh is the largest of four farm polders located within the Lake Simcoe Watershed. Polders are home to very fertile, organic rich soils where high-value vegetable crops are grown. Fertilizer inputs and other agriculture activities have resulted in an estimated P load of 3 T/yr (Lake Simcoe Phosphorus Reduction Strategy, 2017).
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