Pennsylvania's top environmental regulator says he's confident the natural gas industry is ending one of its more troubling environmental practices as gas drillers tap the lucrative Marcellus Shale formation.
On Tuesday, the state's new Republican administration called on drillers to stop sending contaminated wastewater to treatment plants that discharge into rivers and streams.
Some researchers have gathered evidence the plants were contributing to rising levels of a pollutant that could affect drinking water.
Acting environmental protection secretary Michael Krancer says industry leaders assure him they plan to stop sending waste to the plants by May 19. He says they'll send the waste to deep disposal wells mostly in Ohio or recycle it in new well projects.
Some drilling companies say they've been working to halt the use of rivers as wastewater disposal sites for years.
Associated Press writer Marc Levy contributed to this report.