After five days of rainfall, E. coli bacteria levels in the North Fork, South Fork, and Main-stem of the Shenandoah River have risen significantly since our tests on May 19.
Out of 14 sites monitored along these river stretches, 10 exceeded the U.S. Environmental Protection Agency’s (EPA) recommended freshwater Beach Action Value (BAV).
The Data at a Glance:
The Surge: Heavy runoff from the multi-day rain event has driven bacteria levels past acceptable thresholds across the watershed compared to the clearer conditions observed last week.
The Threshold: The EPA’s precautionary “do not exceed” early alert value is set at 235 CFU of E. coli bacteria per 100mL of a water sample.
The Risk: This value serves as a critical warning system to protect recreators, especially families with children, from potential waterborne illness.




