Cambridge is actively addressing the longstanding issue of combined sewer overflows (CSOs), which occur when heavy rainfall overwhelms the city’s aging sewer system, leading to the discharge of untreated sewage into local waterways such as the Alewife Brook, Charles River, and Mystic River. These overflows pose significant environmental and public health risks, particularly during storm events.
Current Challenges
Despite efforts that have reduced CSOs by 88% over the past 36 years, the Massachusetts Water Resources Authority (MWRA) reported that Alewife Brook received 19 million gallons of sewage overflow in 2024 alone. Projections indicate that, without further action, future storm events could continue to cause millions of gallons of overflows, exacerbating the problem.
Proposed Solutions
In response, the MWRA has proposed a $1.28 billion plan that includes the construction of storage tanks and partial sewer separation to manage sewage discharges. However, this plan stops short of a full overhaul to separate sewage and stormwater pipes, citing cost and disruption concerns. Critics, including grassroots organizations like Save the Alewife Brook and the Charles River Watershed Association, advocate for complete sewer separation to eliminate CSOs entirely, arguing that the current plan is a missed opportunity to fully address the issue.
Community Involvement
Local residents and environmental activists are actively engaged in this issue, pushing for more robust solutions to protect Cambridge’s waterways. The city has conducted a Climate Change Vulnerability Assessment to identify key physical and social vulnerabilities, including those related to increased precipitation and its impact on the sewer system. This assessment informs neighborhood climate resilience plans for areas like Alewife and The Port, aiming to prepare the community for the unavoidable impacts of climate change.
Looking Ahead
As Cambridge continues to grapple with the challenges posed by CSOs, the city remains committed to finding balanced solutions that protect the environment and public health while considering financial feasibility. Ongoing community engagement and advocacy play a crucial role in shaping the future of Cambridge’s sewer infrastructure and its resilience to climate change.