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Reducing phosphorus loading is a priority issue to improve the quality of Lake Simcoe. The proposed Lake Simcoe Protection Act, among other actions, specifically targets phosphorus reduction. The LSRCA and the Ontario Ministry of the Environment are considering Phoslock, a product already used in several countries, as a way to reduce phosphorus levels.


The health of the Lake Simcoe ecosystem, especially the coldwater fishery, has been under stress due to problems associated with low dissolved oxygen concentrations. The low oxygen levels are mainly a result of phosphorus pollution within the drainage basin.

High phosphorus concentrations promote the excessive growth of aquatic plants and algae. When the plants and algae die, the decaying process consumes dissolved oxygen at the bottom of the lake. As a result, young coldwater fry may fall victim to the low oxygen levels or be forced into shallower waters, where their natural predators live. Many young are not able to survive to adulthood, and the coldwater fishery in Lake Simcoe is not sustainable.

Phoslock was invented and developed by the Commonwealth Scientific & Industrial Research Organisation (CSIRO), Australia's equivalent to Canada's National Research Council. CSIRO ranks in the top one percent of world research bodies in twelve of its twenty-two research fields. Extensive testing and usage around the world demonstrates that Phoslock both reduces phosphorus in water and is harmless to the water and its plants and animals.

Find out more:

How Phoslock Works

Testing Phoslock in the Lake Simcoe Watershed

Phoslock Toxicity Report (PDF)