PROVIDENCE — Rhode Attorney General Peter Neronha is suing the city of Woonsocket and two contractors over their mismanagement of the municipality’s wastewater treatment facility and for polluting the Blackstone River.

The civil complaint, recently filed in Providence Superior Court, alleges numerous violations of the Clean Water Act, the state’s Freshwater Wetlands and Environmental Rights acts, and impairment of public trust resources by Woonsocket’s wastewater treatment facility.

The legal action comes just weeks after the facility was found to be illegally discharging partially treated sewage — also known as effluent — into the Blackstone River, the third such instance in 12 months. The state Department of Environmental Management announced the leak March 1, after it received a social-media complaint. DEM placed a no-contact advisory on the river, lifting the order two weeks later once it was satisfied the wastewater plant was in compliance.

The wastewater facility, along the Blackstone River at 11 Cumberland Road, is partially privatized. While Woonsocket owns and oversees the facility, the daily operations are outsourced to two out-of-state companies. Jacobs Engineering, which is based in Dallas, runs the main treatment facility. A sludge incinerator adjacent to the main plant is run by Baltimore-based Synagro. Its state permit only allows the facility to discharge fully treated sewage into the Blackstone River.

At a March 15 press conference, DEM director Terry Gray said non-compliance from the facility was no longer acceptable in the current environment.

“All those entities have to work together effectively to get the right effluent limits, and they have not done that,” he said.

State officials said they expect no long-term impacts from the discharged effluent, but described the repeated instances as “amazingly frustrating.”

“It’s clear to me that if we don’t take action on this today, this problem will not be solved,” Neronha said.

The Woonsocket facility has had a growing trend of violations during the past year and a half, with DEM inspecting the plant 36 times since February 2022. The plant was cited 12 times between July 2021 and March 2022 for violations of its Rhode Island Pollutant Discharge Elimination System (RIPDES) permit. Facility officials told state inspectors the violations stemmed from issues with sand filters or because of extreme weather events.

DEM officials were notified of a major partially treated sewage leak on March 23 of last year, but the leak started at least two days prior, according to state officials. Test results found elevated levels of fecal coliforms and enterococci, key indicators of bacterial contamination in the water. The first of three no-contact advisories for activities downstream of the plant was issued that day; DEM lifted the order two days later, on March 25.

On June 5 of last year, DEM was notified of another major leak of partially treated sewage being discharged into the Blackstone River. In the space of a week, state inspectors visited the wastewater plant four times, finding six permit violations, and its superintendent, following 10 odor complaints from residents, was given a notice of noncompliance for odors extending beyond the property lines.

A report prepared by environmental consultants Weston & Sampson on behalf of DEM indicated the discharge problems at the plant were institutional, citing the lack of communication and cooperation between Jacobs and Synagro during daily operations, and the plant continually running at or near capacity of system limits.

In rebuttal comments submitted to DEM, Synagro said the issue was a build-up of solid waste and inadequate primary wasting, concluding that the appropriate solution was to pump primary solids into a storage tank to relieve the load on the facility’s gravity thickeners.

Synagro did not respond to a request for comment. Woonsocket Mayor Lisa Baldelli-Hunt also did not immediately respond to request for comment.

The discharges are a stark reminder of the Blackstone River’s transformation from dumping ground to national park. The 48-mile-long river, which starts in Worcester, Mass., before traveling south toward Narragansett Bay, birthed the Industrial Revolution, hosting a number of water-powered mills attached to factories and settlements up and down the Blackstone.

But that industrial legacy came at a stiff price. By the 1970s, the Audubon Society described the Blackstone as “one of America’s most polluted rivers” and the Environmental Protection Agency later labeled it as “the most polluted river in the country with respect to toxic sediments.”

It’s comeback started 50 years ago, in 1972 with the passage of the Clean Water Act and the Woodstoock of cleanups. While the river continues to be a mainstay on Rhode Island’s list of impaired waters — thanks to cesspools/poorly maintained septic systems, agricultural runoff and nutrient-laden stormwater — the river’s watershed is much healthier than it used to be.

Today the river is used for fishing, kayaking, and other recreational activities that would have been unthinkable half a century ago. In 2021, the National Parks Service established the river as part of the Blackstone River Valley Historic Park.