Gunpowder Riverkeeper is proud to provide weekly water quality information to residents of Baltimore and Harford counties along the Gunpowder and Bush River Watersheds.
Our water monitoring results help inform the public on where they can recreate safely along the River and provide indicators for possible stormwater or point-source pollution.
When our samples indicate E.Coli counts over the EPA’s criteria, it is recommended that the public avoid contact with the water within that area of the Gunpowder River until further sampling is conducted. For more advised precautions, see the Department’s tips for swimmers.
Outlined below is E.coli values measured in MPN (Most Probable Number) from a single sample for each individual date and location during the sampling period (Memorial day-Labor day). The values outlined in red indicate that the E.coli levels surpassed the EPA threshold of 235MPN for a single sample in a waterbody designated for swimming. For more information on how we monitor for bacteria levels you can view our monitoring page linked below.
Safe Swimming guidelines
The EPA’s Safe Swimming Criteria for Maximum Probable Number (MPN) of E. Coli is 126 MPN (geometric mean) and 235 MPN (single sample).
According to the Maryland Department of the Environment’s fact sheet on the EPA’s water quality criteria, at the EPA’s Safe Swimming threshold of 126 MPN (geometric mean) / 235 MPN (single sample), it is estimated that 36 individuals out of 1000 swimmers may contract a water-borne gastroenteritis illness.
Conditions are considered wet when there has been more than 1″ of rainfall measured at each location in the previous 48 hours. MDE advises against swimming in the river within 48 hours of a 1 inch rainfall event.
We test for E.Coli levels at five locations across the basin. Our results are a snapshot of water conditions at the time the sample was taken. MDE advises against swimming in the river within 48 hours of a 1 inch rainfall event. We do not currently monitor other health risks such as:
For additional water quality monitoring in the Gunpowder, Little Gunpowder, Bird, Middle River and Bush Watersheds:
Harford County Health Department Recreational Water Sampling