The U.S. Geological Survey National Water Quality Network—Surface Water, 2024

The U.S. Geological Survey (USGS) National Water Quality Network for surface water (NWQN-SW) was established in 2013 to develop long-term, comparable assessments of surface-water quality in support of national, regional, State, and local needs related to water-quality management and policy. Water-quality samples are collected at each site and measured for a variety of constituents. In 2024, the NWQN-SW consisted of 105 sites, each of them paired with a streamgage, operated by the USGS or other agencies that provide continuous information on streamflow conditions. The water-quality data and the streamflow information from the NWQN-SW are then used to assess the status and trends of water-quality conditions and potential impacts on human and aquatic health.