Hydrologic data from the lower Cedar River Basin, Iowa, 1989-91

Hydrologic data were collected from May 1989 through July 1991 from the Cedar River and the adjacent alluvial aquifer. The data were collected during various flow regimes of the river to evaluate the movement of agricultural chemicals between surface water and ground water. Water-quality samples from 34 surface-water sites and 95 ground-water sites were analyzed for 11 herbicides, 2 dealkylated atrazine metabolites, and nitrate. Specific conductance, pH, water temperature, and dissolved oxygen were measured at the time of sampling. Discharge and water-quality data from two seepage investigations were collected to identify gaining and losing reaches of the river and to help delineate where agricultural chemicals enter the river. Ancillary data on ground-water levels and river stage also were collected.