In the 1990s, urban land in Ohio, Illinois, and Indiana increased by about 10 percent. Currently, Ohio and Illinois are among the 10 most populous states in the nation, while Indiana is 16th. Over 31 million people live in these three states. Large cities such as Chicago, Indianapolis, Cincinnati, and Cleveland, as well as the suburban sprawl throughout the region, have created large areas of impervious surfaces and urban pollution near the rivers and lakes. These factors are known to degrade fish habitat by changing water flow (hydrology) and by adding excessive amounts of nutrients, pollutants and sediment into the waters in this region.
