August 25, 2023

Avoid Contact with the Alewife Brook and Charles River in Cambridge Due to Potential Harmful Bacteria and Other Pollutants Until August 27, 2023

Public Health Warning in effect until August 27, 2023.

People and pets should avoid contact with the Alewife Brook and parts of the Mystic River and the lower Charles River from August 25-27 due to the release of stormwater mixed with sewage into the brook and rivers.

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. 

Two CSO releases occurred in/near Cambridge on Friday morning, August 25 that lasted more than two hours. 

One CSO release occurred in the Little River/Alewife Brook from CAM401A beginning at 8:50 a.m. and ending at 1:10 p.m. This warning is in effect until 1:10 p.m., Sunday, August 27, 2023. CAM401A is located upstream of the Little River/Alewife Brook and upstream of the Route 2 Bridge. Impacted areas may include Arlington, Cambridge, Somerville, and Medford.

One CSO release occurred in the Charles River from CAM005 beginning at 9:05 a.m. and ending at 11:33 a.m. The warning is in effect until 11:33 a.m., Sunday, August 27, 2023. CAM005 is located downstream of the Eliot Bridge across from Mount Auburn Hospital. 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 ( website. Additional information is available on the Massachusetts Water Resources Authority ( 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:  

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 

Haitian Kreyòl 

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