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Water levels on the Great Lakes

5 | Effects of lake level fluctuations

Collapsed structure on Lake Michigan in the 1970s.Stretching more than 9,500 miles, the shores of the Great Lakes are constantly reshaped by the effects of wind, waves and moving water. Erosion is a natural process that occurs under all water level conditions, although it is often magnified during periods of high water or storms. In areas of high-density development, minor deviations from long-term average water levels can produce pronounced economic losses. In less developed areas, impacts can be less noticeable.

Click to see larger image.Low levels, too, can have negative impacts on how people use the lakes, ranging from forcing shippers to lighten their loads to causing problems at drinking-water intakes. Boaters must be careful when navigating in non-dredged marinas and other shallow water areas. Boaters should be familiar with and make it a regular practice to use navigation charts for the waters they expect to navigate. These charts are published by the National Oceanic and Atmospheric Administration (NOAA) and Canada's Department of Fisheries and Oceans. When navigating unfamiliar waters, using caution and reducing speeds is advised.

Click to see larger image.Low water levels have other effects, too. Shoreline property owners enjoy wider beaches, and new vegetation springs up farther from shore, which, in the long run, will provide new habitat for fish when water levels rise again. And while there are new navigation hazards to negotiate, explorers often find reefs, wrecks and old piers they never knew existed until the water fell.

Water levels are only one of the complex physical processes exerted upon our Great Lakes shorelines. Whether you live on one of the Great Lakes or simply enjoy boating or visiting the region's beaches, being aware of water level changes and their potential impacts can save you considerable time, money and worry.

Graphics: Collapsed structure on Lake Michigan in the 1970s; marina on Lake St. Clair; new beaches exposed on the north shore of Lake Michigan (April 2000).

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