Accelerated erosion due to mineral exploration and production in southwestern Wyoming has caused concern that the streams will transport excess sediment in these areas. Two adjacent drainage basins with different levels of development were studied to determine the effects of minerals development on water quality. A high level of minerals development was occurring in the Thief Creek drainage basin; little or no development was occurring in the Chicken Creek drainage basin. Streamflow, suspended sediment , water temperature, and specific conductance data were collected at each creek from May through September, 1984. Water samples were analyzed for common characteristics and constituents, and for trace metals, iron, and manganese. (USGS)