Combined Sewer Overflows (CSOs) are the repugnant remnants of antiquated technology that plague older cities like Boston and threaten precious water resources like the Charles River by introducing raw sewage during wet- weather events. Solving the CSO problem means tearing up many of the streets and replacing decades-old pipes or boring large underground storage basins to contain these flows. The Massachusetts Water Resources Authority (MWRA), the largest supplier of water and sewer services in Massachusetts, developed a plan to reduce untreated CSO discharge volumes into Boston Harbor and its tributaries by ninetytwo percent, including treatment of ninety-two percent of all continuing CSO discharges. This plan came as an alternative to spending over $1 billion for a tunneled stormwater collection system. The Environmental Protection Agency (EPA) and the Massachusetts Department of Environmental Protection (DEP) concluded that MWRA's plan was sufficient given that requiring these additional measures would have a substantial economic impact on the community. However, these agencies remain at odds over how that impact should be calculated-based on a cost-effectiveness analysis or on an ability to pay.