The U.S. Dept. of Justice has settled a lawsuit against a New England electric utility and the Massachusetts Water Resources Authority regarding a cable under Boston Harbor that allegedly was not installed to the federally required depth.

The deal, which the agency announced on July 12, will allow a $340-million harbor dredging project to proceed. (Read text of settlement.)

DOJ filed the lawsuit in July 2016, contending that a 115-kv underwater cable that Eversource Energy had laid across two shipping channels in the harbor was not installed as deep as a U.S. Army Corps of Engineers permit required. (Eversource's corporate name is NSTAR Electric Co.)

The cable carries power from a Eversource substation in South Boston to a wastewater treatment plant on Deer Island.

Under the Corps permit, the cable had to be installed at least 25 ft below the seabed of the two channels. The Corps had found that the cable's depth probably would hamper dredging, putting the harbor deepening project at risk, Justice said.

The project's aim was to allow deeper-draft ships into the harbor.

The settlement calls for Harbor Electric Energy Co., an NSTAR/Eversource subsidiary, to lay, by Dec. 31, 2019, a new underwater cable away from the dredging project. The company then will remove the existing cable. 

Matthew Tessier, Corps project manager in the New England District, said on July 17 via email that the project's estimates cost is $340 million, of which Massport, the project's non-federal sponsor, is to contribute about $130 million.

The project involves deepening five channels and one anchorage to depths that range from 40 ft to 51 ft.

Massachusetts and national port officials say dredging has yet to begin on the project.

But Tessier noted that the Corps' fiscal 2017 work plan includes $18.2 million in its construction account for the project. He said those funds will allow the start of "final design and solicitation-preparation efforts." 

He also said the Corps' fiscal 2018 budget request, sent to Congress in May, seeks $58 million for construction of the Boston Harbor deep-draft improvements. If Congress approves that funding, "construction should start in FY 18," he added.

Tessier said the job will include removing about 500,000 cu yd of rock and 11.5 million cu yd of other material.

Michael Durand, an Eversource spokesman, said via email, "We're pleased to have reached a resolution with all parties that permits us to continue providing safe and reliable service to MWRA, while also accommodating the moving forward of the … harbor dredging project."

Ria Convery, spokesperson for MWRA, said via email, "We're pleased that we were able to reach an agreement that guarantees a reliable source of power to the Deer Island treatment plant for the next four to five decades."

The Corps had no comment on the litigation.

William D. Weinreb, acting United States Attorney for the District of Massachusetts, said in a statement that the project "is necessary to keep the Port of Boston and its shipping facilities competitive with other East Coast ports."

Weinreb added that the agreement means that electricity will continue to flow to the Deer Island wastewater treatment plant, "which is critical to keeping Boston Harbor clean.”

Story updated on July 17 with more details about the project from the Army Corps of Engineers.