Sligo, Long Branch and the tributaries receive water runoff through storm drains along residential streets throughout the watershed, as well as from activity centers in Wheaton, downtown Silver Spring, and Takoma Park with significant commercial dumpsters; and from the Beltway and major streets.

E. coli bacteria levels, which is used as an indicator of the presence of other health-threatening bacteria, comes from multiple sources including pet waste, wildlife waste, and possible sewage leaks.

Sligo’s water quality varies depending on the temperature, recent rain and any potential spills, dumping, or other pollution entering the creeks.

Any place can be fine today, and terrible tomorrow.

FOSC’s monthly testing program shows great variation at some sites:

• For example, the Bennington outfall (storm drain entering Sligo Creek from the Bennington Tributary, which drains some of downtown Sliver Spring) and is a known trouble spot, tested 3,400 MPN/CFU* E. Coli on April 17 but zero on May 31.

• Dennis Ave at Sligo came in at 100 MPN/CFU on April 17 but 400 on May 31.

• Becca Lilly park readings were 1,000 on April 17, but 200 on May 31 and 1,299 on June 3.

FOSC recommends staying out of the water!

Because of this variability, we recommend that you, your children, and dog (no drinking creek water) do not come into contact with creek water. If you do, keep your hands away from your face and clean them well with soap and water as soon as possible. Be especially careful not get creek water on any open sores.

*MPN/CFU is Most Probable Number of Colony Forming Units. FOSC testing uses 410 CFU per 1ml as the maximum level for contact. Other testing uses 126 MPN as the cutoff for recreation.