Advisory Board releases first community-level CSO cost analysis ahead of MWRA plan filing
CHELSEA, MA — The MWRA Advisory Board today unveiled a new CSO Dashboard, an interactive tool that, for the first time, shows the full long-term cost of proposed combined sewer overflow (CSO) investments at the community level through 2072.
As the MWRA prepares to file its Draft Updated CSO Control Plan by the April 30 deadline, the dashboard translates systemwide cost projections into community-specific financial obligations, reflecting how costs are actually assessed to the communities that fund the MWRA’s sewer system.
Public discussion has focused on systemwide costs or average household estimates—but not how those costs are actually distributed across communities. The Advisory Board’s analysis closes that gap by extending beyond the MWRA’s standard projection window, which ends in 2050, to reflect the full lifecycle of debt service through 2072.
Once adopted and incorporated into the Long-Term Control Plan, these investments become mandatory, non-negotiable spending that must be funded by ratepayers across the region—multi-decade financial commitments that will shape community budgets for decades to come.
In larger communities like Quincy, total costs can reach into the hundreds of millions of dollars over time, while even smaller communities like Winthrop face obligations in the tens of millions—extending decades beyond 2050.
The dashboard highlights the scale of these decisions. Under the MWRA’s recommended approach – referred to by the Advisory Board as the “Future Storm Protection Plan” – total community costs extend into the billions of dollars over time. A more expansive approach – referred to as the “Extreme Storm Protection Plan” – would increase those costs by several billion dollars systemwide, with impacts distributed across all member communities.
All scenarios in the CSO Dashboard are based on forward-looking 2050 climate projections, accounting for increased storm intensity rather than relying on historical rainfall patterns.
These decisions come as the MWRA faces major upcoming reinvestment needs in core infrastructure, including the long-term rehabilitation of the Deer Island Treatment Plant, while member communities continue to manage their own local wastewater and stormwater obligations.
“This isn’t about whether to invest—it’s about making sure those decisions are made with a full understanding of the costs, benefits, and tradeoffs,” said Matthew A. Romero, Executive Director of the MWRA Advisory Board. “There is no MWRA money—only ratepayer money. These are real dollars for real ratepayers and families. Our job is to make sure communities understand the full costs, benefits, and tradeoffs—and how those decisions translate into long-term financial commitments and on-the-ground impacts for the people they represent.”
The Advisory Board emphasized that the next phase of CSO investment differs fundamentally from earlier efforts, following decades of work that have significantly reduced and treated CSO discharges and improved water quality across the region.
Today, remaining CSO events are largely associated with infrequent, high-intensity storms, and further reductions require increasingly complex and costly infrastructure.
“We’ve already done a lot of the hard work cleaning up our rivers,” said Andrew Pappastergion, Vice Chair and longest-serving member of the MWRA Board of Directors, representing the MWRA Advisory Board. “What we’re looking at now is spending a lot more money for smaller gains. At some point, you have to ask whether that’s the right balance—or if we’re chasing a victory on paper.”
The CSO Dashboard is intended to provide policymakers, municipal officials, and the public with a clearer understanding of those tradeoffs, grounded in how costs are actually experienced at the community level.
By reframing the conversation around long-term financial impact, the Advisory Board aims to equip decision-makers with the information needed to evaluate proposed investments not only as environmental initiatives, but as binding financial commitments that will shape community budgets and ratepayer costs for decades to come.
📈 View the CSO Dashboard here📄 View CSO Dashboard methodology memo here
