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Connections of a River - Connectivity
Temporal connections (pg 2 of 3)

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Throughout most of the east and midwest, free-flowing rivers experience high water in spring, falling flows in summer, moderate flows in fall, and base flows in winter. Throwing these patterns out of synch may harm many of the organisms in the stream.

On many large reservoirs, for example, water may be stored during high water in spring (to reduce floods downstream) and released during summer (when demand for electricity for air-conditioning is high) or during the winter to make room for high spring flows. Such reservoir management turns the flow downstream of the dam on its head.

On the Cloquet River north of Duluth, the local power utility routinely drew down the Island Lake reservoir each winter to make room for spring flows, causing the Cloquet to run bankfull during the middle of winter, when natural streams are at their lowest. The sudden burst of high water probably caused stress to aquatic organisms, including fish, that had evolved to overwinter in a dormant state in quiet pools.

To protect aquatic life and also to provide more ample flows for canoeists during the spring and summer, the Minnesota DNR, Minnesota Power, and the Federal Energy Regulatory Commission negotiated an agreement in 1995 to manage the flow from reservoirs on the Cloquet, St. Louis, and other streams in the area to more closely mimic natural streamflows.

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