USGS National Water Information System (NWIS)

Comprehensive USGS database providing real-time and historical streamflow, groundwater, and water quality data for sites nationwide.

The USGS National Water Information System (NWIS) is the primary federal portal for accessing water data nationwide. It includes real-time streamflow gauges, groundwater levels, water quality samples, and historical records dating back decades. Pennsylvania has hundreds of active USGS gauges providing free public data.Watershed groups can use NWIS to track flood conditions, characterize baseline hydrology, monitor pollution events, and document long-term trends. Data is downloadable in multiple formats and accessible via API for custom dashboards.Essential reference data for any watershed group conducting monitoring or assessment work.