Chemical giant DuPont will pay more than $US50 million ($A68 million) in an environmental settlement after releasing toxic mercury for decades into waterways in west Virginia.
The deal would resolve state and federal litigation over pollution into the Shenandoah Valley waterway from a company factory in Waynesboro.
It amounts to the largest environmental damage settlement in Virginia history and the eighth largest in the nation, officials said on Thursday.
The money would go to wildlife habitat restoration, water quality enhancement and improvements to recreational areas.
"In bringing this settlement to a close, we are finally righting a wrong that has impacted the South River and the South Fork of the Shenandoah River for so many decades," Democratic Govenor Terry McAuliffe said at a news conference announcing the settlement.
Wilmington, Delaware-based DuPont Co. used mercury in its process of making synthetic fibre at the plant between 1929 and 1950, according to the state Department of Environmental Quality.
Strict storage and disposal regulations weren't in place at the time, and some of the mercury seeped into the South River and flowed downstream to the Shenandoah.
Officials said DuPont discovered the mercury - which accumulates in fish and is especially dangerous to pregnant or breastfeeding women and young children - in the facility's soil in 1976.
The pollution impacted over 100 miles (160km) of river and thousands of acres of flood-plain and riparian habitat, affecting fish, mussels, migratory birds and amphibians, the Department of Justice said in a statement.
DuPont will pay slightly more than $US42 million ($A57 million) toward projects including streamside plantings and erosion control to improve water quality and fish habitat.
The company will also pay for renovations at the Front Royal Fish Hatchery to improve production of warm-water fish such as smallmouth bass, at an estimated cost of up to $US10 million ($A14 million).