Water Quality: Discharge Permit for MWRA Outfall - Protection of Massachusetts and Cape Cod Bays, May 2023

Massachusetts and Cape Cod Bays are key environmental resources, and the 2000 discharge permit for the MWRA outfall took an aggressive approach to their protection. The 2023 draft permit continues to protect Massachusetts and Cape Cod Bays through limits that meet state water quality standards, continue ambient monitoring of the Bays and establish rapid response monitoring for harmful and nuisance algal blooms initiated by species-specific thresholds based on current science.

Stringent Requirements

• The discharge must meet "secondary treatment" standards set by EPA.
• The discharge must not interfere with fish or other aquatic life.
• The discharge must not contribute to eutrophication (e.g. algae growth or a change in species due to excessive nutrients).

Extensive Monitoring

• The discharge will be monitored three times daily for bacteria and chlorine; once per day for solids concentration, oxygen-demanding material, and pH; and once per quarter for numerous other potential pollutants.
• The draft permit continues to include an ambient monitoring program that has been revised to focus on the changing conditions of Massachusetts and Cape Cod Bays. Monitoring data will continue to be available to the public through MWRA's website and extensive online technical library.

• The draft permit establishes revised thresholds and procedures for MWRA to respond to harmful and nuisance algal blooms.