North Carolina environmental regulators say Duke Energy will pay for new water lines or filtration systems for 1,000 households near coal ash storage pits.

The Department of Environmental Quality announced Wednesday that letters were sent this week to owners of drinking wells within a half-mile of the facilities that store coal ash. The byproduct from burning coal for energy can contain toxic chemicals.

A new state law requires Duke Energy to pay for a new water line or filtration system for each house. Duke must submit plans for the new water supplies this year and complete the work by late 2018.

North Carolina officials began pursuing stronger regulations and enforcement of coal ash after a spill along a river at Duke Energy's power plant in Eden in 2014.