Water Quality Monitoring Programs

Friends of Sligo Creek’s Water Quality Monitoring program includes measurements designed to evaluate and track the Creek’s biological, physical, and chemical health. We post the results of these monitoring efforts, or links to them, here on our website, and regularly share them with government agencies such as Montgomery County Department of Environmental Protection (DEP) and the Maryland-National Capital Park and Planning Commission (MNCPPC) or Parks.

Our Water Quality volunteer team conducts monthly sampling at seven sites along the Creek’s middle reach, measuring physical parameters like temperature, pH and conductivity, as well as pollutants like ammonia-N, Coliform and chlorine. See the Testing Parameters and Equipment table at the bottom of this page for details. In the summer of 2020, we began sampling for turbidity, Coliform, and dissolved oxygen levels as part of a regional consortium, the ARK/FOSC Volunteer Water Quality Monitoring Program, led by Anacostia Riverkeeper.

In addition, we partner with the Audubon Naturalist Society to help track Sligo’s biological state, keeping track of macroinvertebrates, insects, fish and other animals at our sampling sites on quarterly basis.

Finally, our Water WatchDogs program allows citizens to report suspected water pollution or other unusual water quality issues directly to DEP and Friends of Sligo Creek via the Water WatchDogs link and at [email protected].

Related program links

Sampling Program Objectives

  1. To monitor the water quality chemistry of Sligo Creek and provide data to the general public and the government.
  2. To bring awareness to Montgomery County and Maryland State governments that we are watching the creek regularly.
  3. To report to the government when there are illicit discharges to the creek and to bring awareness of the need for budget monies to take action.
  4. To accumulate water quality data on Sligo Creek to know if it is becoming better or worse over time.

Water Quality Monitoring Sites
Sligo and NW Branch

Testing Parameters and Equipment

See An explanation of the testing parameters for the definitions of the parameters used in this table.

Parameter Equipment Used
Temperature YSI 85 from 2/2/2008 to present; before 2/2/2008, taken from the pH or conductivity testing instruments
pH ExStik pH (pH 100) waterproof series pen from Extech Instruments
Turbidity Smart 2 Colorimeter from LaMotte
Specific Conductance YSI 85 from 2/2/2008 to present; before 2/2/2008, ExStik Conductivity tester from Extech Instruments
Dissolved Oxygen YSI 85 from 2/2/2008 to present; before 2/2/2008, AW3011 Dissolved Oxygen Meter from Hanna Instruments
Nitrate RQ Flex 10 from EMD from 7/19/2008 to present; Smart 2 Colorimeter from LaMotte from 2004 to 7/5/2008.
Phosphate discontinued after 7/5/2008 because of unreliability; Smart 2 Colorimeter from LaMotte from 2004 to 2008.