A dam near the confluence of the Saint Joseph and Elkhart Rivers had long harmed the Elkhart River by blocking fish migration, isolating populations such as the state endangered greater redhorse, degrading habitat and water quality, disrupting sediment transport, and contributing to declines in invertebrates, mussels, and native fish. Migratory river fish including greater redhorse, shorthead redhorse, silver redhorse, muskellunge, greenside darter, longnose gar, spotted gar, and logperch were significantly affected. The barrier also created dangerous conditions because low head dams can trap people in a turbine-like current, and it contributed to channel incision below the dam that damaged the City's Riverwalk. Built originally in 1832 by Abner S. Simonton, and later rebuilt in a different location in the early 1900's after changes to downtown Elkhart's waterways, the most recently removed dam had been constructed to improve water pressure for mills downriver. Eight feet high and 147 feet wide, it was removed in February 2020 by the U.S. Army Corps of Engineers because of major structural problems and hazards to kayakers and fish. After removal, sediment could again move downstream, a rock riffle replaced the dam, and fish sampling showed rapid upstream recolonization, with species above the former dam increasing from about 37 to 47 by late spring 2020 and some fish traveling many miles upstream.