The Lake Simcoe Region Conservation Authority

Riverine Flood Status
Lake Simcoe Shoreline Status
Low Water Status



Stormwater is a relatively simple concept; it refers to precipitation (rainwater, melting snow) that accumulates after a storm.

Stormwater runoff, the result of what happens to stormwater once it hits the ground, particularly when it falls on paved and other hardened surfaces, is a significant environmental concern.

Stormwater runoff in natural areas is generally of minor environmental consequence. In natural areas, stormwater runoff soaks relatively quickly and easily into the ground, is absorbed by trees and plants and evaporates into the air. A small amount runs along the ground and ends up going directly in streams, rivers and the lake. 

The same is not true in urban areas. Hardened surfaces do not let stormwater runoff seep into the ground, so instead it travels over roofs, roads, parking lots, as well as lawns. The stormwater picks up pollutants like dirt, oil, heavy metals, bacteria, fertilizer, grass-clippings, pet waste, litter etc. and carries substantially more polluted runoff to our rivers and waterways.

After heavy rains or snow melts, river levels can rise and cause flooding. Even in areas not necessaril​y prone to flooding, high intensity storms can result in localized flooding because the water can’t get into the ground fast enough. 

While both rural and urban stormwater runoff eventually ends up in our streams, rivers, and ultimately Lake Simcoe, urban stormwater is more problematic, not only because of the much larger volumes of runoff, but because of the pollutants captured and then carried in that runoff.​

Two cars are partially submerged on a significantly flooded street in Aurora, Ontario after a heavy rain event. A firetruck is on scene providing emergency services.

Stormwater man​agement is the practice of addressing stormwater runoff.​

water-quality-icon   Soil Filters Water

Did you know that soil is an important natural water filter? Soil removes many substances from water, some of which are taken back up by plants. 

light-bulb  A New Way to Manage Stormwater

We’re engaged in a ground-breaking research study in an effort to improve stormwater management, introduce savings, and address the impacts of urbanization, degraded water quality and climate change.

Read more about the Stormwater Economic Optimization Study

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