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Friends of Cabin John Creek volunteers monitor critters, chemicals, and bacteria in the Cabin John Creek and its tributaries. This allows us to keep an eye on the overall health of the creek and report this critical data up the chain.

Clean water plays a vital role in the health of our community for people and the ecosystem. Cabin John Creek flows into the Potomac River which flows into the Chesapeake Bay.


The primary threat to local streams is storm water runoff from our neighborhoods. Runoff carries pollutants into the stream and causes unnaturally high flows of water that erode streambanks and degrade this fragile ecosystem.


Macroinvertebrate Program

We sample creek critters quarterly in Cabin John Creek. The counts and diversity provide an indicator of the biological health of the creek. We partner with and follow the protocols of Nature Forward who tracks stream conditions in metro DC. The data is collected and uploaded into the Chesapeake Data Explorer.

Although we have many different types of critters are hanging in there, they were mostly the somewhat-pollution-tolerant and very-pollution-tolerant kind. We are happy to see some pollution-sensitive darner dragonflies and fingernet caddis fly larvae still surviving.

If interested in helping? 

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Our creek and creek life is stressed with Fair to Poor ratings.

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Chemical Monitoring Program

Our teams test chemicals monthly in our watershed. The tests include dissolved oxygen, pH, chloride, phosphate, nitrate, transparency (sedimentation), and temperature.

We partner with the Izaak Walton League of America (IWLA) who manages a water quality program (WQM) to report chemical levels in watersheds across the country. Our data is reported in the Clean Water Hub and will help to identify issues and trends for lobbying local leaders to take action on water quality in the Cabin John Creek watershed. IWLA submits chemical results to the EPA Water quality exchange and the Chesapeake Monitoring Cooperative and the Chesapeake Data Explorer.


Creek Keepers get trained on monitoring chemicals

Photo by Creek Keeper Tamzin Smith.


Bacterial Monitoring Program

We started our E-Coli monitoring program in the summer of 2023 in Cabin John Creek. This bi-weekly monitoring runs June through mid-September and will allow us to notify residents, the county and WSSC of any dangerous levels of E-Coli in Cabin John Creek.


This program trains volunteers to collect samples at 3 monitoring sites located in Cabin John Creek (Goya Dr, Locust Grove Nature Center, Cabin John Local Park).  To help us test E-Coli each summer, sign up at 


Check out our results on our bacteria results page.

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Scoop it! Bag it! Trash it!

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Salt Watch Program

Want to help keep our creeks clean? Be a citizen scientist and help us and our partner Izaak Walton league of America monitor harmful salts in our streams. Go to to order a free test kit and get out there!


Salt Watch is a community science program aimed at identifying salt pollution hot spots and raising awareness on smart salting practices. Salt keeps our roads and sidewalks safe in the winter months, but too much can harm our streams and our water supply.

If you see piles of salt, call 311 to have excess salt cleaned up!


Initial Creek Health Monitoring in the 2000s


In October 2000, Friends of Cabin John Creek began a six-year water quality monitoring program in which volunteers collected and analyzed stream samples from sites throughout the watershed.  Water quality monitoring data can be used to establish a baseline measurement of ecosystem health, identify and prioritize pollution problems, and gauge whether restoration efforts are successful. 


At its peak, the program collected data four times annually at 10 sites with approximately 50 volunteers participating.  Most of the sampling and analysis was conducted using the Izaac Walton League’s Save Our Streams Benthic Macro Invertebrate (BMI) Protocol. Additional measurements included turbidity, pH, temperature, dissolved oxygen, vegetation, and erosion. Monitoring results were submitted to the Montgomery County Department of Environmental Protection (DEP), to supplement their monitoring program, and FoCJC also participated in the Maryland State Department of Natural Resources (DNR) Stream Waders monitoring program.


Monitoring sessions were held on one day during the first three full weekends of the month in May, July, and September,  and optionally in December-February.  Training sessions were once or twice a year for new monitors, but the knowledge can be picked up relatively easily during the sessions themselves.  Data collected by the monitoring program was used to evaluate the health of the creek and to determine whether the County's stormwater runoff control program was working.  Much of the adverse impacts on local streams comes from stormwater runoff.


Powerpoint Presentation on FOCJC Monitoring Program, presented by Roy Seidenstein at the October 27, 2007 Montgomery County Watershed Conference.


Creek Health Monitoring Data

2011-2015 Watershed Health

2000-2006 Monitoring Site Map

2003-2006 Water Quality Data

2000-2003 Monitoring Data Tables


For details or to sign up, contact




Funding provided by: Montgomery County Department of Environmental Protection, Montgomery County Water Quality Protection Fund

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