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Massachusetts Water Resources Authority


May 5, 2020


Ria Convery
(617) 788-1105,

CSO Public Briefing Notice for May 28, 2020

The Massachusetts Water Resources Authority (MWRA) will hold a virtual public briefing on its Combined Sewer Overflow (CSO) Post-Construction Monitoring and Performance Assessment.

The public briefing will address the progress of the MWRA study as reported in semiannual progress reports, including progress reports issued on October 31, 2019 and April 30, 2020, copies of which can be reviewed at The briefing will include opportunity for questions and comments.

This hearing will be held on:

Thursday, May 28, 2020
10:00 AM

The virtual meeting site link and login information are below:

Link to virtual meeting site:

Access Code:622 105 608

Password: CSObriefing

For additional information, contact Jeremy Hall, MWRA Project Manager, at 617-570-5461 or

In November 2017, MWRA commenced a multi-year study to measure the performance of its CSO Long-term Control Plan (the “LTCP”). MWRA is conducting the study in accordance with the final milestone in the nearly 35-year-old Federal District Court Order in the Boston Harbor Case (U.S. v. M.D.C., et al, No. 85-0489 MA). The milestone requires MWRA to submit to the U.S. Environmental Protection Agency and the Massachusetts Department of Environmental Protection by December 2021 the results of CSO post-construction monitoring and performance assessments demonstrating whether the levels of CSO control including frequencies of activation and discharge volumes specified in the LTCP have been achieved. MWRA’s study includes the following key elements:

• Inspections at all CSO regulators/outfalls addressed in the LTCP to confirm closed or active status and confirm or update physical understanding of overflow structures
• Collection of extensive meter/overflow data at remaining active CSO regulators/outfalls
• Configuration updates and recalibration of MWRA’s hydraulic model of the wastewater system using recent inspection information and meter/overflow data
• Assessments of system performance for CSO control against the LTCP levels of control
• Assessments of the water quality impacts of remaining CSOs and compliance with Massachusetts Water Quality Standards, with emphasis on the CSO variance waters of Lower Charles River/Charles Basin and Alewife Brook/Upper Mystic River.


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Updated May 5, 2020