FOSC Chem/Bio WQ Monitoring Summary
December 2016

This is a brief summary of our December 2016 results from chemical and bacterial monitoring at various locations along Sligo Creek.

At Bennington Drive storm water outfalls, salinity and conductivity levels were all substantially elevated in the right pipe (whenever we refer to a left or right outfall, we mean left and right as you face downstream, i.e., in the same direction that the water is flowing). The water from both pipes was relatively low in chlorine and showed essentially no ammonia-N (which is often an indicator of biological matter or waste in water). Coliform levels, however, were much higher than last month’s reading, and detergent levels in the right pipe remain high.

Ammonia-N levels at Wayne Avenue’s outfall tripled from last month’s reading and were quite high. While this storm water outfall pipe showed a large decrease in the amount of chlorine present, it continued to see extremely high levels of both detergent and Coliform bacteria. The Fleetwood Terrace location – in the middle of the Sligo Creek channel near the parking lot on Sligo Creek Parkway between Wayne Avenue and Piney Branch Road – saw lower levels of Coliform in the water as compared to last month’s readings, though these numbers are still at or above EPA’s skin contact guideline levels. Chlorine levels dropped, but detergent levels remained high and conductivity and salinity levels almost tripled.

In Takoma Park, the Maple Avenue storm water outfalls had lower-than-usual levels of ammonia-N and chlorine levels declined. The right pipe’s Coliform levels remain very high, while the left pipe saw its salinity and conductivity readings rise slightly. Because of the Coliform levels we are finding at our monitoring sites, we would not recommend that you or your pets enter the Creek near these outfalls or the main channel near the Fleetwood Terrace at this time or, if you do, that you wash thoroughly with soap and water after any contact.

Results from
Periodic Outfall Monitoring
Along Sligo Creek

FoSC and the Center for Watershed Protection (CWP) Apply Scientific Testing to Improve Sligo Creek

Several outfalls into Sligo Creek are tested periodically by volunteer Pat Ratkowski. Pat tests for ammonia, temperature, and pH to discover illicit discharge problems which may then be reported to the County. An illicit discharge detection and elimination (IDDE) program is a requirement of the County’s Municipal Separate Storm Sewer (MS4) permit. Recent research conducted by the Center for Watershed Protection (CWP) in Sligo Creek and Baltimore City has indicated that illicit discharges are a much greater contributor of nutrient and bacteria pollution than was previously known. Their elimination can help make significant progress towards meeting local and Bay-wide total maximum daily loads (TMDLs). CWP has produced national guidance for developing and implementing IDDE programs, which includes identification of the most appropriate parameters to detect illicit discharges, many of which have sewage components. Volunteers can test for these recommended parameters at outfalls to help find illicit discharges and monitor problematic outfalls over time.

Outfall Photos December 2014

Map of Outfall Monitoring Sites