This report presents stream-discharge and water-quality data collected at five sites in the lower Horse Creek drainage of southeastern Wyoming, May through November, 1985. Data include stream-discharge measurements; field measurements of specific conductance, pH, and water temperature; and computer changes in stream discharge. Measured discharge in Horse Creek ranged from 0.91 to 172 cu ft/sec. Values of pH averaged 8.4. Water temperature ranged from 0 to 27 C. The data are presented in graphs and tables. A map of the study reach shows the location of the data collection sites. (USGS)