Attention swimmers and others who use Seneca Creek for recreation: As we've noted in the past, E. coli levels are often high enough to be considered unsafe for swimming in Seneca Creek, especially after rain events. Please use caution and avoid contact with the water for 48 hours after rainfall in our area.

Potomac Riverkeepers does a daily E. coli check on Seneca Creek at Riley's Lock from May 4 to September 30. On average, more than 60% of the time the E. coli levels are too high to meet water quality standards for swimming. In July the water quality standards were met about 50% of the days. https://www.theswimguide.org/beach/10338