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The Northeastern States contain over 17,000 dams with most built before 1910 for agricultural and industrial water power uses. A few have been built more recently for flood control, recreation, water supply, and energy generation. In many cases, the dams have outlived their expected life expectancy and use, but continue to block the passage of migratory fish species, such as American Shad, river herring, American Eel, Rainbow Smelt, and Atlantic Salmon, to and from their historic upstream spawning grounds. Additionally, the fragmentation of stream systems by dams have reduced Brook Trout populations in some locations. Progress is being made on this impairment as over 67 dams were removed during 2010 to 2014 in...
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A significant number of dams are located in Iowa (> 4,000), Illinois (> 1,759), Indiana (> 1,088) and Ohio (> 2,600). Dams in the Central Midwest were built to provide mechanical power for mills, hydropower, recreation, water supplies, and water retention for urban and agricultural use. Nearly all of these dams impede fish movements in the region and particularly in the Mississippi River drainage and in the watershed of lakes Erie and Michigan. Some communities are removing dams to deal with obsolete infrastructure issues and to improve water quality, flow, and stream connectivity. For example, the removal of Black Berry Creek Dam near Aurora, Illinois in 2013 opened up 32 miles of the Fox River for fish spawning...
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Water projects that include large dams and water withdrawal systems alter seasonal and daily water flows (hydrology) and water temperatures, adversely affecting desert species that are adapted to the natural cycles in this region. Combined with water diversions for domestic and agricultural use, drought conditions from 2010 to 2015 in the Southwest adversely affected all desert aquatic habitats. Large rivers in the Southwest states, such as the Colorado River and the Rio Grande, have been greatly affected by the construction of dams and diversions that: interfere with fish migration; alter in-stream habitat characteristics including sediment and woody debris movement; change water quality and temperature; reduce...
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There are more than 9,800 regulated dams in the Mountain States and 69 percent are in Colorado and Montana. This does not include a large number of dams that are not regulated under dam safety codes, in particular the large number of water withdrawal structures. Dams and irrigation diversion structures provide power and flood control along the rivers of the mountain states, as well as supply water to the farms, ranches, and cities in these states. The reduced flows from water diversions result in less water in the streams for fish, and these altered flows change river habitat by changing sediment and woody debris recruitment and transport, a key factors that control fish habitat that could only be partly examined...
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Over 10,000 dams impound rivers and streams in the three Southeast Atlantic states. North Carolina has over 5,600 dams and barriers on 17,000 stream miles, many of which are old and obsolete structures. There is an average of one barrier structure every three miles. The state also ranks second in the number of high-hazard dams, which can negatively affect the safety of the citizens of North Carolina and aquatic species. These dams impede movements of many native river resident species, such as Brook Trout and Shoal Bass, but also restrict migrations of marine fish that rely on rivers for various life stages, including Striped Bass, Atlantic Sturgeon, American Shad, American Eels, and river herring. In many cases,...
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Dams and other barriers are having a significant effect on fish habitat in the Upper Midwest. More than 3,700 dams have been constructed on Wisconsin’s warm water streams. Similarly, there are 2,500 listed dams in Michigan and likely a similar number that are not in the dam safety database for that state. In the Lake Michigan watershed alone, dams, culverts, and road crossings that impede fish migration have reduced nearly 19,000 miles of accessible stream habitat to only 3,300 miles. With many Great Lakes fish species using tributaries as spawning and nursery habitats, these barriers are a significant factor impairing the full recovery of fish populations in the Great Lakes. Similar fragmentation occurs on other...
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There are over 9,000 dams in the Mid-Atlantic States. The great majority of these dams are small (i.e., less than 15 feet high), old, and obsolete mill dams that are in disrepair. Dams, as well as many poorly designed culverts and road crossings, fragment habitat and stop fish migrations for a range of species. Fish species, such as American Shad, river herring, Atlantic and Shortnose Sturgeon, Rainbow Smelt, American Eel, Striped Bass, and many other fish species must migrate for spawning or require unobstructed access throughout watersheds to complete their life-cycles. Most fish that require migrations in this region have populations that are only a fraction of what they were historically. During 2010 to 2014,...


    map background search result map search result map Description of dams and other barriers as a human activity affecting fish habitat in Northeastern States Description of Dams and Other Barriers as a Human Activity Affecting Fish Habitat in Mountain States Description of Dams and Other Barriers as a Human Activity Affecting Fish Habitat in Southwestern States Description of Dams and Other Barriers as a Human Activity Affecting Fish Habitat in Southeast Atlantic States Description of Dams and Other Barriers as a Human Activity Affecting Fish Habitat in Upper Midwest States Description of Dams and Other Barriers as a Human Activity Affecting Fish Habitat in Central Midwest States Description of Dams and other Barriers as a Human Activity Affecting Fish Habitat in Mid-Atlantic States Description of Dams and other Barriers as a Human Activity Affecting Fish Habitat in Mid-Atlantic States Description of Dams and Other Barriers as a Human Activity Affecting Fish Habitat in Southeast Atlantic States Description of dams and other barriers as a human activity affecting fish habitat in Northeastern States Description of Dams and Other Barriers as a Human Activity Affecting Fish Habitat in Central Midwest States Description of Dams and Other Barriers as a Human Activity Affecting Fish Habitat in Upper Midwest States Description of Dams and Other Barriers as a Human Activity Affecting Fish Habitat in Southwestern States Description of Dams and Other Barriers as a Human Activity Affecting Fish Habitat in Mountain States