FOSR’s Summer E. coli Test Results for Wednesday, July 20, 2022

Of the 14 sites tested on Wednesday, July 20, 2022, two exceeded the 235 E. coli CFU/100 mL threshold for recreational use. The sites that exceeded were:

  • FW36 – Manassas Run, Warren County, VA, above the confluence with Main-stem of Shenandoah River @ Morgan’s Ford public boat landing, E. coli 461.1 MPN CFU per 100 mL of sample
  • FW35 – Main-stem of Shenandoah River, Warren County, VA @ Morgan’s Ford public boat landing, below the confluence with Manassas Run, E. coli 387.3 MPN CFU per 100 mL of sample

As a reference point, the FOSR uses the Virginia water-quality standard prior to October 2019 which was a single sample threshold of 235 E. coli colony-forming units per 100 mL of water sample for primary recreational use. Meaning that if a single freshwater grab sample had E. coli levels that exceed 235 CFU per 100mL of water sample then the water was considered unsafe for primary recreational use.

The FOSR is providing these data for you to make an informed decision regarding recreation in the Shenandoah River watershed based on the sites tested.

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