Feb. 22—New Hampshire officials on Tuesday announced the terms of a $25 million settlement with agrochemical giant Monsanto — and two other entities previously part of the company — over alleged widespread contamination in local waterways and lands of toxic industrial chemicals.

The chemicals are known as polychlorinated biphenyls, or PCBs. Monsanto manufactured, marketed, sold and distributed PCBs from approximately 1929 to 1977 — often under the trade name Aroclor, according to the suit filed in Merrimack Superior Court in October 2020.

The companies listed in the suit include Solutia Inc. and Pharmacia LLC.

Production of most PCBs was prohibited in the U.S. in 1979 under the Toxic Substance Control Act. Although no longer commercially produced, PCBs were used in hundreds of industrial and commercial applications, including paints, coolants and hydraulic fluids.

The state alleged in its lawsuit that Monsanto "knew or should have known" that PCBs were highly toxic and harmful to humans, animals and the environment. The lawsuit covered contamination of public property, surface water, sediment, fish, wildlife, marine resources and other natural resources.

The company internally acknowledged as early as 1937 that PCBs "produce systemic toxic effects upon prolonged exposure," according to the suit. The chemicals do not easily break down and can remain for decades without remediation, the suit reads.

"Despite its early knowledge of the dangers associated with PCBs, Monsanto embarked on a decades-long campaign of misinformation and deception to prolong the manufacture, sale, and use of its commercial PCB mixtures, under trade names including Aroclor as well as Pydraul, Turbinol, and others, in New Hampshire and elsewhere," the suit alleged.

PCB contamination costs New Hampshire millions each year, according to the suit, and contamination impacts 81 square miles of the Atlantic Ocean and approximately 46 other water bodies, including Squam Lake and stretches of the Souhegan River.

Monsanto has agreed to pay $25 million to resolve the case. The state will receive $20 million after deductions for attorneys' fees and costs, officials said Tuesday.

"New Hampshire has a long and proud tradition of protecting our precious natural resources," Gov. Chris Sununu said in a statement. "As an environmental engineer, I spent many years cleaning up PCB contamination, and I know firsthand the costs these efforts can place on individuals and communities. We are holding polluters accountable."

Sununu said the settlement ensures the state will have the "financial resources necessary to remedy the harm that PCBs have caused to our environment."

"We challenged Monsanto to step up and address the contamination that they caused in the 1970s," said Attorney General John Formella in a statement. "We are pleased that we were able to efficiently resolve this case in a way that will provide tremendous benefits to the state."