Investing in Water Quality with CSOs

Once known for their “dirty water,” Boston’s beaches transformed from some of the foulest in the country to some of the cleanest, in large part due to drastic improvements to Deer Island wastewater treatment plant and the rehabilitation of combined sewer overflows (CSOs). In fact, the MWRA and CSO communities went from releasing 3.3 billion gallons from CSOs in 1988 to 0.4 billion gallons in 2016. Learn more about the CSO long term control plan, as well as next steps for monitoring its success, in our Just The FAQs overview.