08/02/2026
You might be noticing some intense algal blooms in our lakes and rivers, especially bright green and even blueish ones. These are blue green algae blooms which can be toxic to humans and pets.
Why are blooms happening more often?
Over many years, our land and environment have changed. Weāve developed and continue to develop more natural land, we've changed how water moves through the landscape. Wetlands have been drained, streams straightened and altered, shorelines have been armoured with rocks and retaining walls, and prairies have been replaced with roads, houses/rooftops, parking lots, and commercial buildings.
This means rain is NOT soaking into the ground and being used by plants. Instead, rain becomes stormwater, which runs quickly across these developed landscapes, carrying lots of phosphorus, nitrogen, sediment, and other nutrients into lakes and streams. This nutrient-rich runoff creates the conditions that allow algal blooms to grow exponentially.
Warmer water, hotter weather, and periods of drought can make blooms larger, last longer, and increase the chance they will produce toxins.