Council Calls for Infrastructure Solutions to Protect Local Waterways

Protecting Boston's waterways requires infrastructure solutions that address combined sewer overflows and their impact on local communities. This week, the Council adopted a resolution opposing the current Draft Updated Combined Sewer Overflow Long-Term Control Plan and calling for stronger infrastructure solutions to protect the Charles River and other local waterways.

Combined Sewer Overflows, or CSOs, occur when wet weather overwhelms the capacity of combined sewer and stormwater systems, causing untreated wastewater, including raw human waste and harmful pathogens such as E. coli, to be discharged into local waterways. Each year, millions of gallons of untreated stormwater are discharged into the Charles and Mystic Rivers, impacting densely populated neighborhoods in Boston and surrounding municipalities, including environmental justice communities. Approximately nine CSO outfalls remain on the Charles River, and persistent discharges continue to impact water quality across Greater Boston.

The resolution also addresses the Draft Updated CSO Long-Term Control Plan for the Charles River, Alewife Brook, and Upper Mystic River basins, released in April 2026 by the Massachusetts Water Resources Authority, the City of Cambridge, and the City of Somerville. The resolution states that the current draft recommendations offer incomplete CSO control and fail to eliminate CSO outfalls and sewer overflows into local waterways. It calls for the final plan to include modern infrastructure solutions, such as tunnel storage and/or sewer separation, that would achieve effective CSO control and result in no discharges except during a 2050 25-year storm or larger.

By adopting the resolution, the Council opposed the current Draft Updated CSO Long-Term Control Plan and called on the Massachusetts Water Resources Authority, Cambridge, and Somerville to strengthen the final plan. The resolution also calls for Boston to coordinate with neighboring municipalities and state agencies to ensure future infrastructure planning prioritizes the elimination of CSOs and the total protection of the Charles River and Boston Harbor watershed.