Stamford Sewage Bacteria

Location: Stamford, Connecticut | Status: Active


During the summer of 2019, water sampling in Stamford Harbor indicated high levels of bacteria, initiating a legal review of the Stamford Water Pollution Control Authority’s (WPCA) compliance with the effluent limitations set forth in its National Pollutant Discharge Elimination System (NPDES) permit for operations at its wastewater treatment plant. Stamford’s compliance record shows an extensive history of violations of their ultraviolet (UV) minimum requirements. Stamford uses UV to disinfect treated sewage prior to discharging it into Stamford Harbor. A UV violation means that the dosage of UV was less than the amount required to properly disinfect the effluent. The violations were often brief, but still resulted in significant effluent being discharged with no disinfection—often well over 20,000 gallons. These outages might be contributing to high bacteria counts in the Harbor; however, direct correlation is not known, and the high bacteria contribution would likely be diluted fairly quickly. These issues were a result of mechanical problems requiring significant UV system upgrades (including a new UV channel), as was indicated by documents released in response to Save the Sound’s Freedom of Information Act (FOIA) request. At the time of our investigation, Stamford had begun contracting for these upgrades. As of August 2020, the upgrades had been completed, yet UV violations continue to recur as some issues remain unresolved. However, the frequency of such violations has significantly decreased.

Latest step:

Review of all monthly operating reports to determine extent of ongoing UV violations since the completion of UV system upgrades. Ongoing outreach to Stamford WPCA and DEEP staff.

Next step:

Continue to track UV compliance and correspond with DEEP and Stamford WPCA staff when violations occur.

Action Opportunities:

Last Updated: March 24, 2022

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