The Science Behind Lake George's Water Quality

Lake George is a 32-mile-long, oligotrophic lake located in northern New York, in the southeastern corner of the Adirondack Park. The very high water quality of the lake supports a broad range of native plants, fish, wildlife, and recreational activities in the Lake and watershed.  The geography and ecology of Lake George interact to support this high water quality. However, they also affect how the Lake responds to water quality threats, particularly from stormwater runoff and invasive species.

Geography of Lake George

topographical map showing lake george and its watershed
The Lake George watershed — all the area around the Lake where water can flow downhill — is 233 square miles, or 2/3 the size of New York City.

Formed by earthquakes and glaciers, Lake George is long, narrow and deep. The widest part of the Lake is about two miles across, while the average width is 1.33 miles. The maximum depth of the Lake is just under 200 feet, with an average depth of about 70 feet. Over 170 islands dot the Lake’s surface. There are 176 miles of shoreline on Lake George, including about 40 miles of island shoreline.

Learn more about the formation of Lake George.

The watershed surrounding the lake is 233 square miles, which is about five times the area of the Lake’s surface. It is relatively steep, which results in smaller wetland areas around Lake George than around lakes in flatter terrain.  The steepness also results in more concentrated development in the watershed, often near locations where streams feed into Lake George.

Learn more about the watershed and wetlands of Lake George.

Flow of Water in Lake George

Lake George flows from the south to the north and drops 226 feet into Lake Champlain through the LaChute River in Ticonderoga. The depth of the lake contributes to strong thermal stratification.

Learn more about the thermal stratification of Lake George.

Streams provide Lake George with just over half of its water; the rest comes from precipitation directly on the Lake’s surface and groundwater. There are over 100 streams in the watershed, with just eight major streams providing about 2/3 of the total stream flow going into the lake.  Water stays in Lake George an average of six to eight years. This is a very long retention rate relative to other lakes and is an important factor in the effectiveness of activities to manage water quality in Lake George.

Learn more about the hydrologic budget of Lake George.

Ecology of Lake George

Lake George supports a rich multi-level food web.  Lake George has a “two-story” fishery, and a wide variety of plants, fish, and wildlife in the water and watershed.

Learn more about the food web, and the plants, fish, and wildlife of Lake George.

Lake George Water Quality

The characteristics of the Lake, watershed, and food web result in its current oligotrophic state. The Lake has generally low phosphorus, low algae growth, limited plant growth, and adequate dissolved oxygen throughout the lake.  New York State classifies Lake George water as Class AA-Special.  Many people around the lake use it for drinking water.

Learn more about the oligotrophic state and water quality of Lake George.

Water Quality Threats

The high water quality of Lake George is sensitive to the introduction of new elements. Stormwater runoff is of particular concern for Lake George, due to the Lake’s watershed geography and long water retention time. Another key concern is invasive species, which can change the Lake’s current ecological balance. Other factors that threaten the sustainability of Lake George water quality include phosphorus runoff and road salt.

Learn more about stormwater runoff, invasive species, and other threats to the water quality of  Lake George.

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All the money raised by the Lake George Association goes to projects and programs that benefit the Lake and the watershed, protecting Lake George water quality now and in the future.
Lake George Association

Lake George Association