Water Quality Information

Potomac River Basin Drinking Water Source Protection Partnership

Local Resources

Water Quality Data Inventory

Members of the Water Quality workgroup have been working with the Interstate Commission on the Potomac River Basin to maintain a list of water quality monitoring efforts underway in the basin. Both a list and an interactive map with monitoring locations are available.

Harmful Algal Bloom (HAB) Monitoring

The workgroup collected HAB monitoring information from Maryland Department of Natural Resources, Maryland Department of Environment, and Virginia Department of Environmental Quality. This information is published as an interactive web map with the complete data list available for download here.


In 2014, the workgroup had a special focus on alkalinity levels in the mainstem Potomac River. This included an information session on the issue and culminated in a report documenting the trend in alkalinity at a few utility intakes.

National Resources

  • EPA has a Discharge Monitoring Report (DMR) Pollutant Loading Tool that is designed to help you determine who is discharging, what pollutants they are discharging and how much, and where they are discharging. The tool calculates pollutant loadings from permit and DMR data from EPA‘s Permit Compliance System (PCS) and Integrated Compliance Information System for the National Pollutant Discharge Elimination System (ICIS-NPDES).
  • The USGS collects and analyzes chemical, physical, and biological properties of water, sediment and tissue samples from across the Nation. The National Water Information System (NWIS) includes current and historical water-quality data and related summary statistics.
  • The USGS Cooperative Water Program, the largest of the 28 USGS Bureau Programs, is the Water Mission Area’s “bottom-up, on-the-ground” program that is designed to bring local, State, and Tribal water science needs and decision-making together with USGS national capabilities related to USGS nationally consistent methods and quality assurance; innovative monitoring technology, models, and analysis tools; and robust data management and delivery systems.
  • The Enforcement Compliance History Online (ECHO) EPA and State Annual Enforcement Actions Map is an interactive map that tracks federal enforcements. The Map represents facilities with enforcement actions under the Clean Air Act, Clean Water Act, and resource Conservation and Recovery Act.
  • The EPA ECHO Exporter provides summary information that can be used for third-party application development. The ECHO Exporter is a monthly file update that provides one line of data for Clean Air Act, Clean Water Act, and Resource Conservation and Recovery Act facilities in EPA’s databases.