January 10, 2024

Avoid Contact with the Alewife Brook and the Charles River in Cambridge Due to Potential Harmful Bacteria and Other Pollutants Until January 12, 2024

Public Warning in effect until January 12, 2024

People and pets should avoid contact with the Alewife Brook and parts of the Mystic River and the lower Charles River from January 10-12 due to the release of stormwater mixed with sewage into the 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. An SSO is an unintentional discharge of wastewater to the environment prior to reaching a treatment facility. SSOs occur infrequently, when the capacity of the sewer system is exceeded—usually due to extreme conditions such as heavy rainfall or an obstruction or break in sewer lines.

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. For discharges that lasted less than two hours in the Cambridge area, please visit Cambridge Department of Public Works, City of Somerville, and Massachusetts Water Resources Authority’s websites.

Six CSO releases occurred in/near Cambridge on Wednesday morning, January 10 that lasted more than two hours. 

There were four CSO releases in the Little River/Alewife Brook on Wednesday morning, January 10. This warning is in effect until 7:29 a.m., Friday, January 12, 2024. Impacted areas may include Arlington, Cambridge, Somerville, and Medford.

  • CAM401A beginning at 12:46 a.m. and ending at 6:11 a.m. CAM401A is located upstream of the confluence with the Little River and upstream of the Route 2 Bridge.
  • CAM401B beginning at 3:36 a.m. and ending at 7:29 a.m. CAM401B is located upstream of the Massachusetts Ave Bridge.
  • SOM-001A beginning at 3:45 a.m. and ending at 5:45 p.m. SOM-001A is located downstream of the Massachusetts Ave Bridge north of Foch Street.
  • MWR003 beginning at 3:43 a.m. and ending at 7:00 a.m. MWR003 is located on the Alewife Brook Reservation near the Alewife T Station.

Two CSO releases occurred in the Charles River on Wednesday morning, January 10. This warning is in effect until 7:50 a.m., January 12, 2024. The impacted areas of the Charles River may include the Cambridge and Boston sides of the river just upstream of the Boston University Bridge to the Massachusetts Ave Bridge. 

  • MWR023 beginning at 4:00 a.m. and ending at 6:10 a.m. MWR023 is located upstream of the Harvard Bridge (Mass Ave) to the Science Museum.
  • MWR201 beginning at 3:41 a.m. and ending at 7:50 a.m. MWR201 is located between Magazine Park and the Boston University Bridge.

Please note that a SSO discharge occurred on January 10, 2024 from Bradeen Street/North Gate (Boston/Roslindale – Bradeen Street). It began at 7:12 a.m. and at the time of this alert is currently ongoing. Once the stop time has been announced, the warning will be updated. The impacted areas of the Charles River may include the Cambridge and Boston sides of the river between the Esplanade and Science Museum.

The public should avoid contact with impacted areas of the rivers 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 and City of Somerville’s websites. 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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