From October 1, 1994 through December 31, 1995, four combined-sewer discharging to the Detroit River in Detroit, Michigan were monitored to characterize storm-related water quantity and quality. Water velocity, stage, discharge, and precipitation were measured continuously and recorded at 5-minute intervals. Water-quality samples were collected at discrete times during each storm and analyzed for inorganic and organic pollutants. This report includes the sampling approach, field collection and processing techniques, and methods of chemical analysis, as well as a compilation of combined sewer discharge volumes, chemical data, and quality control data. These data may be used by resource managers and scientists (1) to describe temporal variation for pollutant concentrations in combined-sewage for various overflow events; (2) to describe spatial distribution of selected pollutants in the four combined-sewer overflows discharging to the Detroit River; (3) to calculate pollutant loads to the Detroit River from the four overflow sites for the monitored storm events; (4) to estimate pollutant loadings form other overflow sites; and, (5) to provide data and information which can be used to define appropriate management methods to reduce or eliminate untreated combined-sewer overflows.

Selected combined-sewers were sampled between 30 and 82 times for inorganic pollutants, and between 14 and 22 times for organic pollutants, depending on the site. These samples represented between 8 and 17 storms during which one or more combined-sewers overflowed. The monitored pollutants included fecal coliform, fecal streptococci, and Escherichia coli; antimony, arsenic, beryllium, cadmium, hexavalent chromium, total chromium, cobalt, copper, iron, lead, manganese, mercury, nickel, silver, thallium and zinc; and polychlorinated biphenyl congeners, volatile organic compounds, and polynuclear aromatic hydrocarbons. In general, metal and non-metal inorganic pollutants were detected at all sites. Many organic pollutants were not detected at all.