Stamford Sewage Bacteria

Location: Stamford, Connecticut | Status: Active


During the summer of 2019, Save the Sound received reports of extremely high bacteria results from samples collected in Stamford Harbor, initiating both a subsequent sampling effort and 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 uses ultraviolet technology (UV) to disinfect treated sewage prior to discharging it into Stamford Harbor. Stamford’s compliance record shows an extensive history of violations of their UV minimum requirements. 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—ranging from 1,500 gallons to 25,000 gallons of effluent that was not disinfected. These outages might be contributing to high bacteria counts in the harbor; however, direct correlation is not known, as this effluent is not sampled to determine the actual level of pollutants discharged when UV outages occur, and any high bacteria contribution could be diluted fairly quickly. Even with some uncertainty as to the long-term environmental harm, acute direct contact with these discharges might be harmful, and a remedy was long overdue. Between January 2015 and December 2019, Stamford WPCA reported at least 43 violations (violations nearly every month). 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 and correspondence with WPCA staff.

At the time our investigation began, 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. In 2020, there were 15 UV violations, and in 2021 there were 32 UV violations. The WPCA has since completed troubleshooting efforts, and UV violations significantly decreased. In 2022, two years after the upgrades were complete, there have only been 2 UV violations from January through June (both violations were in January). Therefore, it appears that the new UV system is now operating properly. Given the long history of noncompliance, and relatively short period of compliance, Save the Sound will continue tracking compliance for a period of time to ensure that these remedies have yielded a permanent fix.

Latest step:

Stamford completed UV system upgrades and troubleshooting; there have been no UV violations since January 2022.

Next step:

Save the Sound will conduct a semi-annual compliance review of EPA ECHO compliance data and exceedance reports to ensure that this problem is resolved. 

Action Opportunities:

Last Updated: November 17, 2022

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