The Nyanza Chemical Waste Dump is a 35-acre site located adjacent to an active industrial complex. Historical industrial operations at the site from 1917 to 1978 released large volumes of wastewater contaminated with acids, organic chemicals and inorganic chemicals. Of particular concern among the released hazardous substances is the chromium and mercury that were used as catalysts in the production of textile dyes. Over 45,000 tons of chemical sludges, together with spent solvents and other chemical wastes, were buried on the site. Some of these wastes were discharged to the Sudbury River. As a result, groundwater, soils, sediments and surface waters are contaminated with heavy metals and chlorinated organic compounds. The U.S. Environmental Protection Agency placed the Nyanza Chemical Waste Dump on the National Priorities List in 1983.