Community Science Water Quality Monitoring

Check out this week’s water quality results on:

Every year, thousands of river enthusiasts 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; the Potomac River and its tributaries, however, are not always safe to enjoy. When it rains, sewage is mixed with polluted stormwater in the city’s outdated Combined Sewer Overflow (CSO) stormwater system. This toxic concoction discharges containments—such as raw sewage, pet waste, road runoff, and others—directly into the Potomac River, posing public health risks.

The dangers of runoff and sewage led the DC government to ban swimming in the Potomac River decades ago. Today, thanks to the infrastructure investments made by DC Water, sewage overflows occur much less frequently in the Anacostia River, and the Potomac River often meets public health standards for swimming.

Our goal through our Swimmable Potomac Campaign is to stop sewer overflows, lift the swim ban in DC and provide a good public notification system so that the residents can safely swim and recreate in the Potomac River.

To keep our community informed and safe while on the Potomac, in 2019 PRKN founded its Community Science Water Quality Monitoring Program to test the waters and inform our community when and where it’s safe to swim. We started by organizing a dedicated team of volunteers who received rigorous training provided by PRKN and other skilled professionals working throughout our watershed. From May through September, our volunteers collect water samples weekly on Wednesdays from public access sites along the river, analyze them, and report the results every Friday so weekend river users know if it is safe to swim or recreate on the river. This is a free public health notification system for river users, spanning over one hundred river miles from Paw Paw, WV to Colonial Beach, VA.

The program has been so successful that, we have been able to expand to 50+ sites along the Potomac River in DC, Maryland, Virginia and West Virginia! Click on the maps below to explore all current monitoring sites. All three of our labs are Tier III certified to analyze our samples collected by over 100 trained volunteers.

Explore our real-time water quality data in partnership with Xylem and the Reservoir Center here!

Monitoring Sites

To see if your local public access point is safe to swim in, check out SwimGuide and Facebook/Instagram/BlueSky/LinkedIn every Friday between May and the end of September. We release new site results each week, as the safety of access points may change from week to week. For more general trends in site passing standards, check out our Swimmable Potomac Report, which summarized results and findings on the health of the river.

EXPLORE THIS WEEK’S RESULTS

WHY MONITOR WATER QUALITY?

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.

Yet, thousands of people are recreating on the river in D.C., Maryland, Virginia and West Virginia waters each year. Unfortunately, there was little to no data for river users to determine if it was safe to use the river until PRKN started our Community Science Water Quality Monitoring Program. We feel it is 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. We are now working with DC DOEE and city officials to make DC a Swimmable City.

ABOUT OUR Potomac PROGRAM

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 labs at National Harbor and Colonial Beach, where they are processed and analyzed. The results of our water quality monitoring are 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.

The water quality monitoring data is also shared with other groups working to protect the Chesapeake through the Chesapeake Monitoring Cooperative and the Chesapeake Data Explorer.

ABOUT OUR Upper Potomac PROGRAM

Brent Walls, Upper Potomac Riverkeeper, is a real leader in the use of technology to identify pollution problems in his watershed. Since 2022, Brent has been managing his own volunteer community scientist based water quality monitoring program. Through a valuable cooperative relationship with the Center for Coastal & Watershed Studies at Hood College, the IDEXX system used to analyze this bacteria data has its very own lab space. In Spring of 2025, the UPRK Water Quality Monitoring Program achieved a Tier III water quality certification through the Maryland Department of the Environment.

Each Wednesday from Memorial Day through September, Upper Potomac Riverkeeper, Brent Walls and several dozen volunteers collect samples from several sites in the Upper Potomac River: Antietam Creek, Conococheague Creek, and Monocacy River. The goal of the program is to assess the E. coli bacteria levels at the water’s edge for each location tested. The results are posted on the Upper Potomac Facebook page and on the mobile app, Swim Guide. The UPRK Water Quality Monitoring program has led to other monitoring projects.

Addressing the issues

The Antietam Creek in the Upper Potomac has been on the Maryland Impaired waters list for bacteria for the past 2 decades. In 2022, our bacteria monitoring identified a stream in the Antietam Creek with consistently high levels of bacteria. These excessive levels prompted a more focused monitoring project for Marsh Run, a tributary of the Antietam Creek.

The Marsh Run monitoring project identified the source of E.coli bacteria as human through DNA testing. Through a grant from Foundation of Pennsylvania Watersheds, The Marsh Run monitoring project was expanded to the entire Antietam Creek watershed. Our Upper Potomac Riverkeeper has been working with DNA experts at John Hopkins University to test samples for various DNA and identify a source. The following map identifies the sample locations where DNA is being assessed to find the dominant source.

Research projects, like Antibiotic Resistance and toxic algae identification, conducted by Hood College have also been useful in our assessment of water quality in our streams.

Get Trained and help make the Potomac Swimmable again!

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. You can help not only provide a public service to your community, but also drive investment in stopping sewage and stormwater pollution.

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! We sample for the E.coli bacteria, which 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!

If you have Wednesday mornings free and are interested in participating in our program, please complete the following steps:

Watch our three training modules below in order.

Once you have successfully completed all three modules, contact our lab manager, Lisa Wu ()
and Staff Scientist, Evan Quinter () to request our Water Quality Monitoring Certification Exam. After completing our certification exam, you will be a certified water quality monitor and will receive all of the materials and information you need to get started!
Please fill out and sign our waiver, too.
After completing our certification exam, we will arrange for an in-person session to certify you as a Water Quality Monitor and you will receive all of the materials and information you need to get started!

Adopt a WQM SITE

Potomac Riverkeeper Network’s Community Science Water Quality Monitoring is our most underfunded program, despite thousands of people using our rivers for fishing, paddling, boating, and more! By adopting one of our water quality monitoring sites, you will help us continue to provide consistent and independent water quality data to our communities so they can stay informed and recreate safely.

VIEW ADOPTABLE SITES I WANT TO ADOPT A SITE!