There are thousands of dams in the Great Lakes basin, many of which alter river flows, disrupt the movement of sediment and nutrients and isolate fish and other aquatic life from valuable habitat.
Many states are working to remove or modify obsolete dams to permit fish passage and restore a more natural flow of water.
One such project was completed recently on Drummond Island, in Michigan’s portion of northern Lake Huron. Learn more here.
The Michigan Department of Natural Resources worked with federal officials and a local conservation group to modify the Potagannissing Dam. Built in 1947, the dam blocked fish passage in the Potagannissing River and contributed to a decline of the northern pike population in northern Lake Huron.
The Michigan DNR installed a fish ladder in 1999, but northern pike were unable to navigate the structure. So the state removed three feet from the top of the dam and built a series of four rock-ramp structures, which allowed all species of fish to swim over the dam and reach 800 acres of prime spawning habitat areas upstream.
The Potagannissing Dam modification was one of a growing number of projects that are reconnecting the Great Lakes to more of their tributaries. Projects like these are systematically restitching the biological fabric of the sprawling Great Lakes ecosystem.