Updated Combined Sewer Overflow Control Plan Public Meeting June 2

The Cities of Cambridge and Somerville, together with the Massachusetts Water Resources Authority (MWRA), are holding an informational meeting on their $1.29 billion Draft Updated Combined Sewer Overflow (CSO) Control Plan, which is a legal requirement. 

A Combined Sewer Overflow is an overflow of stormwater and sewage into nearby rivers and streams that can happen during heavy rain. The draft plan, which is the first in the nation to account for long-range climate impacts, outlines a series of recommendations to protect local waterways from pollution by eliminating combined sewer overflows during a typical 2050 year, which climate models indicate will include heavier and more intense flooding and storms. Despite this larger capability to control overflows that would be the first in the nation to go beyond EPA guidance, atypical larger storms in 2050 are still predicted to result in CSOs within the proposed system.  

From now until September 30, 2026, community members, advocacy groups, and organizations are invited to review the Draft Updated CSO Control Plan and share feedback. To help inform the public feedback process, community members are invited to attend a public meeting to learn more about the plan and its recommendations for eliminating CSOs in the Mystic River, Charles River, and Alewife Brook in a typical 2050 year. This is an informational session only. Official public comment will be accepted via other methods. 

The plan will have long-ranging impacts on both the ecological health of the impacted waterways and the water and sewer customers of Somerville and Cambridge, as well as the 41 additional cities and towns served by the MWRA, which will see rate increases to cover the cost of the project.  

About the Meeting 

Members of the project team will present an overview of the plan and the expected outcomes of the recommended work.   

When: Tuesday, June 2, 6 p.m. 

Where: The meeting will be held via Zoom. Register to attend at tinyurl.com/CSOJune2026. 

Community members will have the opportunity to ask questions during the meeting. Public comment will not be accepted at the meeting but rather through the methods detailed below.  

More About the Plan 

The plan is the result of more than four years of detailed analysis, engineering evaluation, and broad public engagement. It recommends a set of projects -- including new storage tanks, sewer separation, and upgraded conveyance systems -- that together are projected to eliminate CSO discharges during a typical 2050 year in the Alewife Brook, Charles River, and the Mystic River. The plan is the first in the nation to go beyond EPA guidance and prepare for climate change. Learn more and see the full plan at voice.somervillema.gov/joint-cso-planning. 

Public Feedback Period and How to Submit Comment  

From now until September 30, 2026, community members, advocacy groups, and organizations are invited to review the Draft Updated CSO Control Plan and share feedback.

The public can provide feedback through: 

• An online comment portal 
• Email 
• Mail  
• Or verbally at two virtual public meetings to be held in September. 

Visit voice.somervillema.gov/joint-cso-planning for details on how to submit comments and more information and additional details on the plan.  

Persons with disabilities who need auxiliary aids and services for effective communication (i.e., CART, ASL), written materials in alternative formats, or reasonable modifications in policies and procedures in order to access the programs, activities, and meetings of the City of Somerville should contact the ADA Coordinator in advance at 617-625-6600 x 2059 or ADA@somervillema.gov. 

The City of Somerville can provide you with an interpreter in your language for free. To request an interpreter, please contact us at languageaccess@somervillema.gov or call 311 (617-666-3311) at least 7 days in advance of this event.