StreamWatch Program

Since 1992, volunteers have assessed and documented water quality in the Stony Brook-Millstone Watershed through our StreamWatch water quality monitoring program. StreamWatch measures the health of our water by testing water chemistry, measuring bacteria levels, and assessing the biological and physical health of our waterways. StreamWatch data helps The Watershed Institute better assess the impacts of pollution and land use on local streams and determine actions necessary to protect and improve water quality.

How Clean is Our Water?

We use a number of parameters to determine water quality and stream health across our StreamWatch network including tests for phosphorous, nitrates, dissolved oxygen, bacteria, ph, water temperature, turbidity, and aquatic life. Click the button below to read our Clean Water Report Card.

View the tabs to see how our watershed fares across the different parameters measured by StreamWatch from 2014-2016. Sites have been assessed on a scale of “Excellent”, “Good”, “Fair”, or “Poor” for each parameter individually, then used to determine if each subwatershed meets or fails the applicable water quality standards. Click here to check out our water quality assessment framework to see how we developed these scores.

Clean Water Report Card

Join the StreamWatch Team!

Becoming a StreamWatch volunteer is an easy and fun way to contribute to the health of your watershed. We rely on about 100 volunteers to assess water quality throughout our region. Volunteering requires an initial training session and at least a one-year commitment.


Chemical Action Team (CATS)

StreamWatch gathers chemical data from over 40 monitoring sites across the watershed. StreamWatch CATS volunteers monitor one weekend per month and attend a mandatory Quality Assurance session in the Watershed Lab every year. Volunteers test six basic water quality parameters: water and air temperature, phosphates, nitrates, pH, turbidity, and dissolved oxygen. The results are analyzed and reported to the public through our quarterly subwatershed report cards, municipal report cards, and online. Data is also submitted to the EPA’s Water Quality Exchange.

CATS Field Data Sheet  |  CATS Digital PDF Form

Biological Action Team (BATS)

StreamWatch BATS monitor the populations of organisms called macroinvertebrates at 14 sites. Water quality ratings are based on the abundance of various species and their sensitivity to pollutants. If the stream is healthy, a diverse macroinvertebrate population can be found in a relatively small sample of water. A reduction in their numbers may indicate a high level of pollution. Sampling is conducted three times a year in March, July, and October and the organisms are identified to family level in the Watershed Lab. Beginning in 2017, one sample per year will be sent to a certified lab for identification to the genus level.

BATS Field Data Sheet  |  Lab Subsample Form  |  Macroinvertebrate Tally Sheet

Bacterial Action Team (BACT)

Through the StreamWatch bacterial action team, volunteers test for Escherichia coli (E. coli) levels in the water at 13 sites. E. coli is a type of bacteria that live in the intestinal tracts of animals and humans. The presence of this bacteria indicates that disease-causing bacteria, viruses, and parasites of a fecal origin may be contaminating the water. Swimming or wading in streams with highE. coli levels is considered to be a health risk. High E. coli levels can result from leaking septic or sewer systems, polluted runoff that has picked up animal (dog, goose, cow, etc.) waste en route to the stream, waterfowl in the stream, or wading cows. Monitoring is being used to keep an eye on several hot spots and to identify other bacteria problems quickly. Two five-week monitoring periods occur every summer. Volunteers can opt to participate in one or both sessions. All samples are analyzed in-house using the IDEXX/Colilert method.

BACT Field Data Sheet  |  IDEXX Bench Sheet

View Our Monitoring Schedule

StreamWatch 2021

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