WORCESTER, MA — Nearly 900,000 gallons of sewage spilled into the Blackstone River in Worcester early Thursday morning, according to the Worcester Department of Public Works and Parks.

The overflow spilled from an outfall pipe behind the Walmart along Tobias Boland Way at around 4:30 a.m. Thursday and lasted for about 40 minutes, the city reported. About 879,000 gallons spilled during the overflow.

"This overflow consists, or likely consists, of untreated or partially treated sewage and waste. Avoid contact with the affected water bodies for 48 hours after the overflow ceases due to increased health risks from bacteria and other pollutants," Worcester's public works department said in an alert Thursday morning.

The sewage spill will likely drift to communities downstream from Worcester, including Grafton, Millbury and Sutton.

Thursday's spill came from Worcester's combined sewer system, which mingles household sewage with runoff from industrial sites and street gutters. That waste typically goes to a treatment plant before reentering local waterways. Sometimes the systems overflow, leaking untreated waste into waterways.

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