Environmental Protection Agency (EPA) Administrator Scott Pruitt testifies about the fiscal year 2018 budget during a Senate Appropriations Subcommittee on Interior, Environment, and Related Agencies hearing on Capitol Hill in Washington D.C., June 27, 2017.

(SAUL LOEB/AFP/Getty Images)

At a Glance

The EPA plans to roll back an Obama-era measure that limited water pollution from coal-fired power plants.EPA Administrator Scott Pruitt has been working to revoke the measure since April.The wastewater contains several highly toxic heavy metals when it is flushed into rivers and lakes.

The Environmental Protection Agency said it will roll back a measure implemented by former President Barack Obama that limits water pollution from coal-fired power plants.

In a letter released Monday as part of a legal appeal, EPA Administrator Scott Pruitt said he'll work to revise the 2015 guidelines that mandated increased treatment for wastewater from steam electric power-generating plants.

At the urging of electric utility leaders who opposed the stricter standards, Pruitt started the process by delaying implementation of the new guidelines in April. When the wastewater is flushed from the coal-fired plants into rivers and lakes, it typically contains traces of lead, arsenic, mercury and selenium – all of which are highly toxic heavy metals.

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"After carefully considering your petitions, I have decided that it is appropriate and in the public interest to conduct a rulemaking to potentially revise (the regulations)," Pruitt wrote in the letter addressed to the pro-industry Utility Water Act Group and the U.S. Small Business Administration.

Pruitt's letter, dated Friday, was filed Monday with the Fifth Circuit U. S. Court of Appeals in New Orleans, which is hearing legal challenges of the wastewater rule. With Pruitt now moving to rewrite the standards, EPA has asked to court to freeze the legal fight.

While that process moves ahead, EPA's existing guidelines from 1982 remain in effect. Those standards were set when far less was known about the detrimental impacts of even tiny levels of heavy metals on human health and aquatic life.

"Power plants are by far the largest offenders when it comes to dumping deadly toxics into our lakes and rivers," said Thomas Cmar, a lawyer for the legal advocacy group Earthjustice. "It's hard to believe that our government officials right now are so beholden to big business that they are willing to let power plants continue to dump lead, mercury, chromium and other dangerous chemicals into our water supply."

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EPA estimates that the 2015 rule, if implemented, would reduce power plant pollution by about 1.4 billion pounds a year. Only about 12 percent of the nation's steam electric power plants would have to make new investments to meet the higher standards, according to the agency.

Utilities would need to spend about $480 million on new wastewater treatment systems, resulting in about $500 million in estimated public benefits, such as fewer incidents of cancer and childhood developmental defects.