Community Science Volunteer Water Quality Monitoring Program



Every year, thousands of people enjoy kayaking, paddleboarding, wading, or even swimming in the Potomac River. Our goal is for everyone to be able to use and enjoy the river safely. Many years ago when it was pretty much always unsafe to swim because of sewage pollution, swimming was banned in the Potomac River in Washington, DC.  When it rains, sewage combines with polluted stormwater in the city’s outdated Combined Sewer Overflow (CSO) stormwater system discharging raw sewage, pet waste, road runoff, and other contaminants directly into the Potomac River, posing public health risks.  Today, because of the infrastructure investments by DC Water, those overflows occur much less frequently, and the Potomac often meets public health standards for swimming. 

Our goal is to stop the sewer overflows so that the Potomac River is safe for swimming and other water-based recreation. To achieve our goal of a swimmable Potomac, in 2019 we began our Water Quality Monitoring Program to test the waters and let people know when it is safe to swim. We started by organizing a dedicated team of volunteers who received rigorous training from Potomac Riverkeeper and other skilled and knowledgeable professionals from our watershed. From May through September, our volunteers collect water samples weekly from sites along the river, analyze them, and report the results to the public.

Water Testing Volunteers

The program has been so successful that, over time, we have been able to expand to 29 sites along the Potomac in DC, Maryland, and Virginia! Click on the map below for the monitoring locations. We are especially happy that we have, thanks to our super volunteers, expanded in 2023 to include waters in and around Colonial Beach.

To see which public access points generally meet public health standards, check out our Swimmable Potomac Report, which summarized results and findings on the health of the river.

We also release current water quality results and information on the safety of the public access sites that we monitor on SwimGuide and Facebook every Friday between May and the end of September. We let you and other river users know when and where direct contact with the water is likely to be safe.

As we continue to add more water quality monitoring sites, we need more volunteers to help us with collecting and testing samples. This is your opportunity to participate directly in gathering the water quality data that we need to inform the public about when and where it is safe to recreate in the Potomac River and to drive investment in stopping sewage and stormwater pollution.

Please join us for training and learn how you can help to make the Potomac Swimmable again!

  • If you’d like to participate, please contact our volunteer coordinator at Then take our online training. We have developed three training modules, which we would ask you to do in order:
    1. Module one
    2. Module two
    3. Module three
  • Once you have successfully completed all three modules, let us know, and we’ll send you the online test that you must pass to be certified.
  • Please fill out and sign our waiver, too.
  • Once you get word that you’ve passed the test, we will arrange for an in-person session to certify you as a trained volunteer scientist and we welcome you to our dedicated and knowledgeable group!

Volunteers collect and analyze water samples on Wednesday mornings where people frequently recreate, to provide up-to-date information on the water quality near you! The E.coli bacteria for which we sample serves as a water quality parameter for human health in recreational waters. This monitoring initiative is one step towards our ultimate goal of making the river swimmable for all to use and enjoy!

Sample analysis is done on our research vessel, the Sea Dog, which is outfitted with an onboard laboratory to measure E.coli and turbidity. The water quality monitoring data is shared with other groups working to protect the Chesapeake through the Chesapeake Monitoring Cooperative and the Chesapeake Data Explorer. Data will be compared with the Virginia, Maryland and DC water quality standards to determine whether the E.coli levels at each site pass the threshold for public health standards.


Part of Potomac Riverkeeper Network’s mission is to improve recreation access. For years it has been illegal to swim in the Potomac River in Washington, DC because high levels of bacteria sometimes make it unsafe. When it rains, pollution from many sources runs into our river, including:

  • polluted stormwater
  • raw sewage
  • pet waste
  • road runoff
  • litter
  • other contaminants that foul the Potomac River.

With thousands of people interacting with and recreating on and in D.C., Maryland, and Virginia waters each year, it’s essential for members of the public to have current information about pollution that may directly affect their health.

We are also working to lift the ban on swimming – sign our petition to Mayor Bowser. We have submitted our Swimmable Potomac Report to DC’s Department of Energy and Environment to show that the river is frequently safe for swimming, especially with our weekly notifications to the public.


Our program relies on a dedicated team of volunteer community scientists who are trained and certified by Potomac Riverkeeper Network and other skilled and knowledgeable professionals. The volunteers conduct weekly water quality sampling for E.coli from a host of sites throughout D.C., Maryland, & Virginia. These samples are then brought to our Tier III certified “floating lab”, Sea Dog, where they are processed and analyzed. The results of our water quality monitoring are then posted on SwimGuide, the smartphone app for recreational users, as well as on our social media. This allows the public to know when and where it is safe for recreation along our river.

Our program runs in partnership with Alliance for the Chesapeake Bay, Waterkeeper Alliance and other local non-profit organizations. The monitoring effort in Virginia and Maryland waters is generously supported by the Virginia Environmental Endowment, National Harbor Marina, Peterson Companies, SP Marine Management, Hunting Creek Garden Club, the Town of Colonial Beach, and the Interstate Commission on the Potomac River Basin. Monitoring in District of Columbia waters is supported by the DC Department of Energy and Environment.


We test the water in areas of frequent recreational use and are collecting data that will accurately reflect the health of the river. Currently we monitor 29 sites throughout the D.C. Maryland, and Virginia waters, but our program is quickly growing and we are working hard to accommodate more sites in the future. Check out our current site map, or check SwimGuide for more information about water quality sampling near you!