USGS Water Data for the Nation

National water data portal providing real-time and historical streamflow, groundwater, water quality, and reservoir data from thousands of monitoring sites.

USGS Water Data for the Nation is the authoritative source for continuous streamflow and water quality data from tens of thousands of monitoring sites across the country. Real-time gage data is updated every 15 minutes, making it invaluable for flood forecasting, drought tracking, and recreational river use. Historical data goes back over a century at some long-running stations. Pennsylvania has hundreds of active USGS gages in the Susquehanna, Delaware, and Ohio basins. Watershed groups use gage data for streamflow context in monitoring reports, grant applications, and restoration design. The USGS Water Services API allows programmatic data access for custom dashboards and analysis. Mobile alerts for flood-stage exceedances are available for many sites.