Abstract

Oakland County is a suburban county in southeast Michigan. Population and demand for water grew steadily in the county over the 20th century, and these trends are expected to continue in coming decades. Roughly 75 percent of current water demand is met by imported water from the Detroit Water and Sewerage Division (DWSD), but water use from ground-water sources within the county still exceeds 43 million gallons per day. Because much of the population growth is in areas beyond the DWSD system, an additional 20-25 million gallons per day of supply may be necessary to meet future demands. Managing the wastewater produced while also protecting human and ecosystem health also may present challenges.

Despite considerable expansion of urban areas, streamflow characteristics at most sites have not been affected. However, at several sites in areas of the county that are both supplied by ground water and sewered, statistically significant downward trends in low-flow stream discharges have been noted between 1970 and 2003. Stream chemistry, compared to a previous study of county water resources prepared in 1972, has generally improved, with marked decreases in concentrations of nitrogen, phosphorus, and sulfate. Chloride concentrations, however, have increased dramatically in river and lake water across the county. Detectable concentrations of personal-care products, flame retardants, and petroleum fuel compounds were identified at all river sites sampled.