FOSC Chem/Bio WQ Monitoring Summary
February 2017

This is a brief summary of our February 2017 results from chemical and bacterial monitoring at various locations along Sligo Creek.

In Silver Spring at Bennington Drive storm water outfalls, salinity and conductivity levels all declined slightly, while the chlorine levels nudged up a bit. The water from both pipes contained more ammonia-N (which is often an indicator of biological matter or waste in the water) than December’s reading. Coliform levels more than tripled at the left pipe (facing up stream), and also rose slightly in the right pipe. and detergent levels both pipes remain high, though slightly lower than our last readings.

Ammonia-N levels at Wayne Avenue’s fell by almost 85% from December’s remarkably high levels (1.14 mg/L). Conductivity, TDS and salinity all held steady, surfactants declined somewhat but remain very high, and chlorine edged up slightly. Coliform levels declined to “only” 30,000 cfus/100mL from the usual “too numerous too count” level. Wayne Avenue’s outfall pipe is consistently quite high for E. Coli and Total Coliform ¬ - far above recommended skin contact levels.

Downstream, 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 – also saw high levels of Coliform in the water (three to six times December’s readings). Chlorine levels quadrupled and surfactants (essentially, detergents, cleaners, soap) remained stable but high. Most of the rocks on the bottom of the stream in this stretch are now covered with a long, dark gray algae.

In Takoma Park, the Maple Avenue storm water outfalls continue to see visible pollutant discharges of detergents. Ammonia-N levels were low in the left pipe, but almost tripled in the right pipe to 0.29 mg/L. The right pipe also saw a ten-fold increase in its Coliform levels as compared to December’s readings. Conductivity, TDS and salinity readings essentially held steady near recent lows.

The CSO overflow pools behind the Park Ritchie apartments had their lowest water levels that we have seen. All pollutants rose when compared to December’s readings, in some cases by five to ten times. In particular, the southwest pool had a chlorine reading of 0.5 ppm, more than ten times its prior level. These high levels are not unexpected because of the lack of rain and concentration of pollutants in a small bodies of standing water. Coliform levels were lower than normal. Because of the Coliform levels we are finding at our flowing monitoring sites, we would not recommend that you or your pets enter the Creek near these outfalls or the main channel near Fleetwood Terrace at this time or, if you do, we recommend 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