This report reviews the environmental impacts of hydrologic modification projects in the Midwest. Hydrologic modification projects include activities such as stream channelization and relocation. These projects frequently include construction activities that remove riparian vegetation, remove in-stream cover, disrupt riffle-pool sequences, decrease stream sinousity, alter substrate composition, increase stream velocity and decrease habitat area. Reviewed articles report impacts on fisheries including reduced population, standing crop, diversity and altered community structure. Impacts on stream hydrology include increased stream bank erosion, bed scour, tributary erosion and altered riffle-pool sequence. Impacts on water quality include increased suspended sediment, water temperature and stream length effected by pollutants.