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Habitat Assessment

Water Level Changes

Natural fluctuations in water levels are an important part of the coastal area's ecological dynamic and productivity and can result in dramatic changes within Lake St. Clair's gently sloping marshes and lakeplain. Variable water levels create greater diversity among plants and animals that adapt to and depend on a highly changeable wetland environment. However, some changes in water levels are a result of explicit human intervention and tend to disrupt natural processes.

Human-induced changes in water levels are usually part of larger efforts to control and maintain desired levels of water for specific purposes. Human control of the outflow of Lake Superior affects water levels in the lower Great Lakes, including Lake St. Clair. The marshes of Walpole Island First Nation, parts of the St. Clair Flats areas in the delta, and much of the eastern shore of Lake St. Clair have been extensively diked; pumping stations and water level gauges have been installed so that water levels can be maintained at levels that are optimal for attracting and sustaining populations of game birds. Hunting and fishing are the foundation of Walpole Island First Nation’s leading industry--recreation and tourism, and are significant revenue sources throughout the region. As such, management of these diked wetlands in a manner that can ensure their sustainability as an economic resource is of utmost importance.

In spite of their potential benefits, however, water levels that are artificially maintained at a constant level interrupt natural fluctuations that are beneficial to coastal ecosystems and result in negative impacts over the long term, particularly for natural communities such as lakeplain prairie, which require periodic flooding to persist. Water in shallow impoundments and drainage canals, when isolated from the flow of the Great Lakes, tends to have low oxygen levels and warms up rapidly, diminishing its value as habitat for fish and other aquatic organisms. Dredging in the St. Clair River is believed to have significant, yet temporary affect on water levels in the lake.

For more information, see: Habitat Assessment, Section V (PDF)