Non-point source pollution is currently the primary threat to riverine water quality in both urban and agricultural settings. Nevertheless, our ability to make better predictions on the fate of urbanized/agriculturally impacted aquatic ecosystems is greatly hindered by our lack of understanding of the relationship between land use change, hydrology and water quality. Here we present water chemistry data from the Clear Fork River, which drains a mixed urban-agricultural watershed in north-central Ohio. The watershed has experienced an increase in urbanization associated with a decrease in farmland. Between 1982 and 1997, urban land increased 22%, while 16% of farmland was lost. At the center of the watershed is the Clear Fork reservoir, [...]