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Lake Ontario

Lake Ontario serves as a source of freshwater for millions of people. The lake receives water from many sources, including streams and storm drains, as well as industrial and municipal outflow. 

No matter where you live, your actions have an impact on the health of the lake. The actions of a single user might seem trivial compared to the vast size of the lake, but our combined actions have an enormous impact.  

Algae in our Lake

Many communities along the western shore of Lake Ontario from Durham to Niagara are affected each summer by attached algae (Cladophora) that accumulates on-shore and in the near shore waters, and the noxious odours given off as it decays. Algae is a plant. Like all plants, it grows in the presence of sunlight and nutrients such as phosphorus.

Halton Region created the Lake Ontario Shoreline Algae Action Advisory Committee (LOSAAAC) in July 2002 to gather information and monitor research activities towards possible solutions to reduce the nuisance algae issues in Lake Ontario. LOSAAAC has concluded that a combination of factors cause nuisance algae in Halton Region:

  • There is more than enough phosphorus in lake water to support algal growth.
  • Strong east winds drive detached algae and other debris to Halton shorelines. These winds are also partly responsible for driving phosphorus from urban sources east of Halton.
  • A thermal bar inhibits polluted water that flows into the lake from mixing with cleaner water in deeper, colder areas of the lake.
  • Zebra mussels on the lake bottom contribute to algal growth by providing an anchor on which to grow, contributing to nutrient levels, and clarifying water to allow sunlight to penetrate.

Algae on the Lake Ontario Shoreline Halton Region's optimization program (Adobe Portable Document Format (PDF)80KB) has been very successful at minimizing the phosphorus discharged from our wastewater treatments plants. 

The Conservation Halton Water Quality Study suggests that the watershed from Halton to Lake Ontario contributes a significant amount of phosphorus through non-point-source pollution - the water that runs off our urban streets, lawns and buildings. 

In fact, that study found that land-based non-point-sources contribute about the same amount of nutrient as the wastewater treatment plants.

For more information related to algae, see Research Results.

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