About Lake Champlain

Lake Champlain and landscape

Lake Champlain is one of the region’s most treasured natural resources. Residents and visitors enjoy the lake for drinking water, swimming, fishing, and scenery. It supports a complex freshwater ecosystem with diverse plant and animal species, and it is critical to the region’s economy.

While much of the lake is generally in excellent condition, a number of environmental  challenges pose a threat to the lake’s water quality and ecosystem. Chief among these threats is phosphorus. Phosphorus is a nutrient that exists naturally in the environment, but too much of it can contribute to the formation of cyanobacteria (blue-green algae) blooms that are sometimes toxic.

The Lake Champlain Basin

Phosphorus is washed off of all areas of the landscape that surround the lake—its watershed—including farms, urban areas and other developed lands, and even forests. At 8,234 square miles, this watershed is remarkably large, measuring 19 times larger than the surface area of the Lake itself.

This large ratio of land to lake surface area (by comparison, Lake Tahoe has a ratio of only 2 to 1) means that human activity on the landscape has a tremendous impact on water quality. Developed lands—including lawns and yards—account for 16% of the phosphorus that goes into Lake Champlain, and contribute nearly twice as much phosphorus as farmland on a per-acre basis.

Phoshporus and land cover graphic

Annual Phosphorus loading and land cover in the Lake Champlain Basin (Source: 2018 State of the Lake and Ecosystem Indicators Report)

This means that the care and management of our lawns and yards has a direct impact on water quality. By reducing the amount of phosphorus we apply to our yards and raising our lawn mower blades to increase the amount of precipitation that can soak into the ground rather than running off, we can all help to ensure clean water in Lake Champlain and in all the lake and rivers in the Basin!