High sediment oxygen demand in a reservoir behind a dam contributed to low dissolved oxygen levels in Michigan’s Thornapple River. Therefore, in 2010 the Michigan Department of Environmental Quality (DEQ) added a 27-mile reach of the Thornapple River to the state’s Clean Water Act section 303(d) list of impaired waters for low dissolved oxygen concentrations.
After the dam was removed, dissolved oxygen concentrations improved; the waterbody now meets water quality standards and supports its designated use as a warmwater fishery. DEQ intends to remove dissolved oxygen as a cause of impairment for the Thornapple River in the state’s 303(d) list. The segment remains listed for polychlorinated biphenyls and mercury.
Source: US EPA
