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 and rearing.
