Streamflow data (daily mean streamflows and annual peak flows) were retrieved from the U.S. Geological Survey (USGS) National Water Information System. The two main sources of water-quality data for streams were the Water Quality Portal (WQP) and the USGS National Water Quality Assessment (NAWQA) Western States Data Aggregation. Data on surface-water features were obtained from statewide National Wetlands Inventory (NWI) datasets acquired for Montana, North Dakota, and South Dakota. Produced-waters data were retrieved from the USGS National Produced Waters Geochemical Database.
