Somerville Combined Sewer Overflow (CSO) Public Meeting #6 – January 2026

The Somerville Combined Sewer Overflow (CSO) Public Meeting #6 focused on presenting and discussing the updated CSO control plan involving the Massachusetts Water Resources Authority (MWRA), the cities of Cambridge and Somerville, and other partners. The meeting detailed the challenges of managing combined sewer systems built in the 19th and early 20th centuries, the impacts of climate change on stormwater volumes, and the complexity of alternatives to reduce CSO discharges. Various control alternatives were evaluated, including sewer separation, storage tanks, micro tunnels, and regional tunnels, with considerations of construction impacts, costs, timelines, and community disruption. The financial analysis highlighted the significant costs ranging from $1.4 billion to nearly $12 billion, with implications for ratepayers across multiple municipalities. Public comments emphasized concerns about environmental justice, health impacts from sewage flooding, the need for transparency, equitable funding, and the urgency of effective solutions. The meeting concluded with plans for further public engagement and a forthcoming MWRA board decision on recommended control levels.