Willett Branch Bethesda Pool

Source Information

Little Falls Watershed Alliance has trained volunteers monitor water quality at several locations in the Little Falls Watershed, a sub-watershed of the Potomac. Monitoring occurs every other week from July through mid-September. Parameters to be monitored include levels of E.Coli, pH, and temperature. The samples are processed by the Anacostia Riverkeeper water quality lab. The primary parameter of concern is E. coli, a fecal coliform. E. coli is measured in terms of the Most Probable Number /100 ml water and high levels are an indicator of fecal contamination by warm-blooded animals like birds and mammals. The MD Primary Contact Water Quality Standards are as follows: • E. coli single sample value = 410 MPN/100mL • E. coli geometric mean = 126 MPN/100mL The Little Falls and Willett Branch are rated against these values. PASS indicates the E. coli single sample value is less than or equal to 410 MPN/100mL. FAIL indicates bacteria counts of over 410 MPN/100mL.