E.coli and Bacteria
A sample on its way for testing
Bacterial Monitoring Campaign in the Upper Potomac Watershed
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 a Volunteer based bacteria 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.
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. In Spring of 2025, the UPRK Bacteria Monitoring Program achieved a Tier III water quality certification through the Maryland Department of the Environment.
Upper Potomac Water Testing
Each Wednesday from Memorial Day through September, Upper Potomac Riverkeeper, Brent Walls and about a 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. This bacteria monitoring program has led to other monitoring projects.
Addressing the Issues
The Antietam Creek 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.
Thank you to all of our Upper Potomac Water Quality Monitoring Partners who support our program!
