July/August 2021 Water Quality Report (CWMN)

The rainy month of July had a big impact on the water quality in our local streams.

The following data comes from water samples taken from 41 sites by our Community Water Monitoring Network (CWMN) volunteers during July and August.

E. coli

E. coli is a bacteria that lives in the intestines of healthy animals, including humans. Its presence in water is evidence of waste contamination. Typical sources of E. coli include leaking sewer infrastructure and bird or dog feces. High levels of the bacteria associated with this waste can make people sick.

High rainfall this summer was reflected in our E. coli data from July, with less than 15 sites remaining safe for any sort of recreation. This data shows the importance of structural stormwater Best Management Practices (“BMPs”) which help to treat stormwater and clean it before it discharges to the river.

Learn more about BMPs on the Neponset River Watershed Association website.

The E. coli results are summarized in the maps and graph below.






Phosphorus is a key nutrient for proper plant growth. This means that fertilizers contain high levels of phosphorus and when it is washed off lawns via rain, the phosphorous can end up in streams and ponds. Too much phosphorus can lead to harmful algal blooms, cyanobacteria blooms, and fish kills.

Total phosphorus levels were high in July. We are still awaiting the phosphorus results for our August samples.

You can help reduce phosphorus pollution by supporting investments in green stormwater infrastructure and stormwater utilities in your neighborhood.

The phosphorus results are summarized in the graph below.

Note: samples were not collected at MMB106 and UNB002 for the month of July.

For comments, questions  — or to learn more about becoming a CWMN volunteer — please contact NepRWA’s Environmental Science Fellow, Eleanor Yeomans at yeomans@neponset.org or 781-575-0354 x 302.

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