3rd supplemental CSO report delivered

The MWRA submitted a third supplement to its 2021 Final CSO Assessment Report to the EPA and MassDEP at the end of December. The purpose of the report “is to document the progress made toward meeting the Long-Term Control Plan (LTCP) at each of the 16 locations” that did not meeting LTCP goals at the end of 2021.

 

Significant progress toward compliance was achieved for 10 of the 16 outfalls, with construction of improvements completed at 8 locations and construction of recommended improvements underway at 2 locations.

 

This leaves, as the court describes, the “Incorrigible Six.” In 2021, these outfalls presented significant challenges toward finding reasonable and effective measures to meet LTCP goals. Due to reductions in CSO volumes, two of these outfalls along the Charles River are now considered to be effectively meeting their LTCP goals, though differences between meter data and model predictions led to a recalibration of the model in the area of CAM401A, bringing this outfall along Alewife Brook out of compliance.

 

Analysis and consideration of feasible remedies continues for the remaining 5 problematic outfalls. With estimated costs spanning a wide range, the MWRA and its partner communities, Cambridge and Somerville continue to investigate and deliberate possible solutions that can be effective and economically feasible. The full report can be found on here.