CHARLESTON, W.Va. — The Environmental Protection Agency has announced an agreement to address dioxin contamination in the Kanawha River by constructing a cap over nine acres of sediment containing the toxic substance.

According to the EPA, the Superfund cleanup in West Virginia’s Putnam and Kanawha counties will focus on a 14-mile (22.53-kilometer) stretch beginning at the Kanawha’s confluence with the Coal River.

The capping is intended to keep concentrations of the known carcinogen contained and protect fish.

The agency says the most significant human health risks are from eating fish.

Pharmacia, formerly Monsanto Co., manufactured an herbicide in Nitro from 1948 to 1969 that was a principal component of the defoliant Agent Orange used by the U.S. military in Vietnam.

The dioxin in the river was a waste byproduct.