July 30, 2023

Avoid Contact with the Alewife Brook and Charles River in Cambridge Due to Potential Harmful Bacteria and Other Pollutants

Public Health Warning in effect until July 31, 2023

People and pets should avoid contact with the Alewife Brook and parts of the Mystic River and the lower Charles River from July 29-31 due to the release of stormwater mixed with sewage into the brook.

The release of mixed stormwater and sewage—known as a “combined sewer overflow (CSO)”—is needed to prevent contaminated water from backing up into homes, businesses and city streets. 

State regulations require local public health departments to provide notice to the public when these discharges may create a risk to public health, including when a discharge lasts for more than two hours.

Five CSO releases occurred in/near Cambridge on Saturday evening, July 29 that lasted more than two hours. Another CSO also occurred, but lasted less than two hours.

Two CSO releases occurred in the Little River/Alewife Brook from CAM401A beginning at 6:09 p.m. and ending at 9:14 p.m. and from SOM01A beginning at 6:15 p.m. and ending at 8:20 p.m.  This warning is in effect until 9:14 p.m., Monday, July 31, 2023.

  • CAM401A is located upstream of the confluence with the Little River and upstream of the Route 2 Bridge.
  • SOM01A is located downstream of the Massachusetts Ave Bridge north of Foch Street.

Impacted areas may include Arlington, Cambridge, Somerville, and Medford.

Three CSO releases occurred in the Charles River from CAM005 beginning at 6:19 p.m. and ending at 8:53 p.m.; MWR201 (Cottage Farm) beginning at 6:32 p.m. and ending at 11:11 p.m.; and from MWR023 beginning at 5:15 p.m. and ending at 10:03 p.m. The warning is in effect until 11:11 p.m. Monday, July 31, 2023.

  • CAM005 is located downstream of the Eliot Bridge across from Mount Auburn Hospital.
  • MWR201 is located at Magazine Beach.
  • MWR023 is located on the Boston side of the river near Fenway exit from Storrow Drive.

Impacted areas may include Boston and Cambridge. 

The public should avoid contact with impacted areas of the Alewife Brook and Mystic River and the lower Charles River for 48 hours from the time the overflow ends because of increased health risks due to bacteria or other pollutants carried by the stormwater, such as fertilizers or pesticides.  Contact with this water can make you and your pets sick.  Avoid paddle boarding, boating, fishing, or other activities that can bring you in close contact with this water. 

Information about Cambridge CSO events are posted on the Cambridge Department of Public Works (www.cambridgema.gov/CSOReport) website.  Additional information is available on the Massachusetts Water Resources Authority (https://bit.ly/MWRA-CSO-Notifications) and City of Somerville’s websites (https://www.somervillema.gov/cso). Translations of the web pages are available using the translate box along the top of the websites. 

The City of Cambridge continues to make major improvements to the city’s sewer and stormwater systems.  As a result, there are fewer CSO events than in the past, but they still occur after heavy rain.  To learn more, please visit: www.cambridgema.gov/csoPlanning  

The state law requiring public notification of sewage discharges into waterways took effect in 2022. Environmental groups advocated for the law because they were concerned that Massachusetts had no system in place to alert residents when sewage discharges occurred and what people could do to avoid illness. The new law requires municipalities to alert residents in multiple ways when discharges occur and to make the information available in other languages.

If you have questions about potential health risks from contaminated water, contact Sam Lipson at the Cambridge Public Health Department at [email protected] or 617-665-3838.

Translated Information

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ለበለጠ መረጃ፣ እባክዎን ድህረ ገጾቹን ይጎብኙ። በቀኝ በኩል በላይኛው ጥግ ላይ ያለውን “Translate” የሚለውን ሳጥን ይፈልጉ እና ቋንቋዎን ይምረጡ




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