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With Bacteria Tests Having Returned to Normal Levels, DEM Lifts Advisory Placed on Blackstone River

PROVIDENCE The Rhode Island Department of Environmental Management (DEM) is lifting the advisory it placed March 23 on the stretch of the Blackstone River from the Woonsocket Regional Wastewater Treatment Facility located at 11 Cumberland Hill Road, Woonsocket, to the Slater Mill Dam in Pawtucket.

DEM and the Rhode Island Department of Health (RIDOH) issued the advisory recommending that residents temporarily refrain from wading, swimming, canoeing, kayaking, or fishing and from eating any fish caught in the river after an anonymous complaint March 21 led to a DEM investigation into the causes and impacts of a discharge of partly treated wastewater into the Blackstone River. As part of its initial investigation, DEM required the city and its vendor to increase sampling and testing of final effluent to ensure a return to permit compliance.

Engineers from DEM's Office of Water Resources inspected the treatment plant March 21, March 22, March 23, and today. Initial tests performed by a state-certified lab on March 21 showed elevated levels of fecal coliforms and enterococci, which are known as "indicator" bacteria because they indicate the possible presence of pathogens. Subsequent testing for those parameters taken on March 22 and March 23 came back to DEM late yesterday, March 24, and were compliant with the facility's permit limits. These results corroborated DEM findings that facility operators have stabilized treatment processes.

DEM continues to investigate the causes of the plant upset and the response by the city and its contractor operations firm.

For more information about DEM divisions and programs, visit or follow us on Facebook, Twitter (@RhodeIslandDEM), or Instagram (@rhodeisland.dem) for timely updates.

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  • Department or agency: Department of Environmental Management
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  • Release date: 03-25-2022

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