Water Quality and Simulated Effects of Urban Land-Use Change in J.B. Converse Lake Watershed, Mobile County, Alabama, 1990–2003

J.B. Converse Lake, a 3,600-acre manmade reservoir in western Mobile County, Alabama, is used as a source of drinking water for the city of Mobile, and for recreational fishing. The watershed of the lake is predominantly rural. Residential and commercial development is expanding westward from the city of Mobile, however, and the potential for water-quality changes as a result of land-use change is of concern in the J.B. Converse Lake watershed.
Tributary and lake water-quality data were collected during 1998–2003 and used with previously collected (October 1990–June 1998) data to assess water-quality conditions, identify temporal trends, and calibrate the BATHTUB reservoir water-quality model. Selected stream and lake samples were analyzed for concentrations of fecal-indicator bacteria and a group of wastewater-indicator compounds to aid in identifying sites receiving wastewater contamination. The calibrated BATHTUB model was used to predict lake response to changing land use in the watershed.