Stephen P. Opsahl
Concentrations of selected constituents in surface-water and streambed-sediment samples collected from streams in and near an area of oil and natural-gas development, South-Central Texas, 2011-13- Detections, concentrations, and distributional patterns of compounds of emerging concern in the San Antonio River basin, Texas, 2011-12
- Detections, concentrations, and distributional patterns of compounds of emerging concern in the San Antonio River basin, Texas, 2011-2012
- Quality of surface-water runoff in selected streams in the San Antonio segment of the Edwards aquifer recharge zone, Bexar County, Texas, 1997-2012