The Trump administration on Monday weakened a 2015 regulation that would have forced coal plants to treat wastewater with more modern, effective methods in order to curb toxic metals such as arsenic and mercury from contaminating lakes, rivers and streams near their facilities.

In a statement, Environmental Protection Agency Administrator Andrew Wheeler said that the final rule’s “flexible, phased-in” approach would make it easier for the coal industry to comply while also protecting the environment. Three years ago the Trump administration delayed the Obama-era rule — which the EPA had estimated would keep 1.4 billion pounds of pollutants out of U.S. waterways each year — before replacing it with a scaled-back version.

“Newer, more affordable pollution control technologies and flexibility on the regulation’s phase-in will reduce pollution and save jobs at the same time,” Wheeler said.

Power plants represent the largest industrial source of toxic wastewater pollution around the country.

A senior EPA official on Monday said the updated rule would save the coal industry $140 million each year, and the agency estimated that the change would still reduce pollution by 1 million pounds annually compared to the 2015 rule because some plants would voluntarily adopt stricter controls than what the agency requires.

Beginning in 2018, power plants would have had to begin showing that they were using the most up-to-date technology to remove heavy metals from their wastewater and finalize these updates by 2023. But President Trump’s first EPA administrator, Scott Pruitt, said in the spring of 2017 that the agency would postpone those deadlines at the request of some energy firms.

The new rule pushes the final deadline for compliance to 2025, and it exempts several dozen plants from stricter water pollution limits entirely, on the grounds that they will be retired between now and 2028.

Environmental groups swiftly condemned the changes, calling them a gift to the power industry and a shortsighted decision focused only on potential costs to companies, rather than on the benefits to wildlife and to people living near coal plants. They argued that the Obama administration’s rule was based on years of peer-reviewed studies, input from health experts and a mountain of public comments — and that stricter oversight is needed, given the amount of pollution generated by the plants.

“The Trump administration is once again jeopardizing people’s health to give coal power industry lobbyists what they want,” Thom Cmar, an attorney with the environmental advocacy group Earthjustice, said in a statement Monday. “The Trump administration’s rollback will be responsible for hundreds of thousands of pounds of pollutants contaminating sources of drinking water, lakes, rivers and streams every year.”

Cmar said the group plans to challenge the rollback in court, as it has with numerous other Trump administration moves to cut federal regulation and oversight.

“Giving coal companies a free pass to dump more toxic heavy metals like mercury and arsenic into our waters is a travesty,” Brett Hartl, government affairs director for the Center for Biological Diversity, said in an email. “This shameless handout will allow greater amounts of these dangerous pollutants to be spewed directly into our waterways, threatening public health and pushing hundreds of aquatic endangered species, including salmon, sturgeon and hellbender salamanders, closer to extinction.”

Coal industry executives, however, said the new pollution guidelines will be less costly while still safeguarding public health.

“This new rule replaces a prime example of regulatory overreach that was specifically designed to stack the deck against the coal industry when compared with other fuels,” said Rich Nolan, president and CEO of the National Mining Association.

Quin Shea, vice president for environment, natural resources, and occupational safety and health at the Edison Electric Institute, said that power companies can meet the new standards without a problem, which is key to their “ability to continue providing reliable, affordable, and clean energy to U.S. homes and businesses.”

Coal use has continued to plummet in recent years despite Trump’s efforts to aid the industry, in large part because of the persistently cheap price of natural gas.

According to data published by the U.S. Energy Information Administration in early August, 121 U.S. coal-fired power plants were repurposed to burn other types of fuels between 2011 and 2019 — the vast majority were converted to or replaced by natural gas-fired plants. In 2019, U.S. coal production was the lowest since 1978, when a coal miners’ strike halted most of the country’s coal production for months, according to the EIA. In addition, the agency has estimated that the country’s new electric generating capacity in 2020 will come primarily from wind and solar development.

In finalizing the 2015 rule, the Obama administration noted that federal standards limiting wastewater pollution by coal-fired power plants had remained unchanged for decades, and that states had largely left the problem unregulated.

At the same time, a coalition of energy companies, known as the Utility Water Act Group, has been adamant that the Obama-era regulation would impose heavy costs. Less than two months after Trump took office, the group filed a petition with the EPA, asking the agency to consider overhauling the rule.

“It will cause negative impacts on jobs due to the excessive costs of compliance — which were grossly underestimated by EPA — and regulatory burdens forcing plant closures,” the group wrote in its March 2017 appeal. “Those impacts are being, and will be, felt in communities around the country where those industries operate.”

Separately, the U.S. Small Business Administration’s Office of Advocacy also petitioned the EPA to reconsider the rule. “These unduly stringent requirements are likely to force closures of a significant number of coal-fired utilities, and adversely affect mining and utility jobs and rural communities that depend on those plants, without concomitant environmental benefits,” the office wrote in April 2017.