Hannah Claggett, ShoreRivers’ Chesapeake Conservation and Climate Corps Member for 2024–205 shows off a water sample collected in order to be tested for bacteria.
ShoreRivers hosted its second annual Bacteria Blitz last month, engaging community members across the Eastern Shore to collect water samples from their properties or favorite swimming spots. These samples were brought back to our Easton, Chestertown, or Galena offices and tested for Enterococci, a bacteria used to indicate fecal contamination in waterways.
This community-wide effort empowers both ShoreRivers members and non-members to better understand local water quality and provides our Riverkeepers with valuable data from areas not routinely monitored through the Swimmable ShoreRivers program, which sees the testing of nearly 50 sites across our watersheds between Memorial Day and Labor Day. Results from this weekly testing are posted every Friday on social media and at shorerivers.org/swim in an effort to provide the public with the information they need to make educated decisions about their contact with the water.
The timing of this year’s Blitz followed several significant rain events, which likely contributed to the elevated bacteria levels observed. Out of 40 sampling sites, only nine passed the State of Maryland’s recommended standard for safe swimming (less than 104 CFU/100mL of Enterococci), meaning that 78% of the tested sites did not meet safe swimming standards.
Results of ShoreRivers’ annual Bacteria Blitz showed a high fail rate this year, with just nine passing the State of Maryland’s standard for safe swimming.
Of the rivers sampled, the Chester River showed the highest number of passing sites, with six out of 13 locations meeting safe swimming standards. In comparison, the Choptank River had only one passing site out of 16 samples. The Sassafras River and Bayside Creeks had one passing site out of four samples, while the Miles-Wye and Eastern Bay region also had just one passing site out of seven total locations. The lowest colony-forming unit (CFU) reading recorded was less than 10 CFUs and found at two Chester River sampling locations, while the highest readings exceeded 24,196 CFUs, and were found in two Choptank River and one Chester River sample.
"The high rate of failing results from this year's Bacteria Blitz — which represent a common theme on our waterways this summer — are a reminder of how vulnerable our rivers are to pollution triggered by storm events" says Chester Riverkeeper Annie Richards. "When it rains, stormwater flows across roads, farm fields, septic systems, habitats with wildlife scat. These events can significantly raise bacteria counts — especially in areas with aging infrastructure or limited natural buffers like wetlands and forested stream banks.
Pass and fail percentages from this year’s Bacteria Blitz by watershed.
"What is more, excessively warm, turbid waters create ideal conditions for bacteria to thrive and grow. So, while there are acute bacteria pollution sources that need both government action and funding to address, we need those actions to take into account the role climate change is playing to exacerbate the impacts of stormwater runoff."
As always, ShoreRivers recommends the following best practices when recreating in local waterways: rinse off after swimming, avoid swimming for 24–48 hours after a rain event, and stay out of the water with open cuts or wounds to minimize exposure to potentially harmful bacteria.
For more information about ShoreRivers’ water quality monitoring programs or to get involved, visit shorerivers.org/swim. Though the seasonal Swimmable ShoreRivers testing has wrapped up for this year, keep an eye out for a full report on each regularly monitored site in October and ShoreRivers’ ongoing work to protect and restore our local rivers and creeks.