It took three days, but workers at New York City's North River Wastewater Treatment Plant finally succeeded in stopping raw sewage from flowing into the Hudson River after a fire shuttered the plant on July 20. On average, the plant, located in Harlem west of the West Side Highway, treats 20 million gallons per day of wastewater. The plant has been in operation since 1986.

The four-alarm blaze began in the engine room at about 11:45 a.m., shutting down pumps and causing millions of gallons of sewage to spill into the river. Dept. of Environmental Protection workers and contractors stopped the discharge at about 9:30 p.m. on July 22, a few hours after two of five pumps were restarted, DEP says. Only two engines need to be operational during dry weather to handle the wastewater flow into the plant, the agency says. But the next morning, an electricity feeder that supplies power to the plant went offline because of a manhole fire, causing sewage to once again flow into the river. For several hours, about 15 million to 25 million gpd of untreated sewage was discharged into the river; it was stopped at about 3:30 p.m., DEP says.

In a statement, DEP said it would install an additional pumping system in case further issues with the existing system arise.

On July 21, DEP began performing small “pump-arounds,” routing wastewater flow out of an 84-in. sewer—which usually transports influent westward to the plant—into a 42-in. sewer that flows across Manhattan to the Wards Island Wastewater Treatment Plant in the East River.

To reduce bacteria, DEP is using chlorine to treat some sewer outfalls near the plant. The agency says it continues to work around the clock to stabilize operations that have been restored.

Both New York and New Jersey authorities are monitoring water quality, and New York City officials issued pollution advisories for several area beaches.