Native fishes that should benefit include Atlantic salmon and sturgeon on the Kennebec, smallmouths on the Baraboo, and shad and striped bass on the Naugatuck. He cites Colorado's dammed Gunnison River, once home to cutthroat trout. Silt accumulates behind dams, smothering prime spawning grounds for both native and transplanted fish. During summers, Stanford says, dammed waters are unseasonably cool, and when released kill the invertebrates and insects that downstream fish need for forage. But dismantle a dam, Stanford says, and a river should return to its old self within two years.
Native fish can recover on their own or be reintroduced.
Yet dams are also responsible for good fishing opportunity. Pete Rafle, communications director for Trout Unlimited, says dams have helped create first-class trout fisheries, including New York's Delaware River and the White River in Arkansas. Economic and environmental factors also make dam removal difficult. Hydroelectric dams, for example, produce 10 percent of America's electricity. Pollution of another sort is a stumbling block, too.