July 25, 2026 - The EPA reversed itself on Thursday by allowing Salt River Project to keep using a clay liner on a coal ash evaporation pond at its 780-megawatt Coronado Generating Station in St. Johns near the New Mexico border.

According to an EPA statement on the decision, SRP closed a separate, ash slurry settling pond in accordance with federal law. The utility still operates one ash landfill site at the plant.

A plastic liner has been required for coal ash evaporation ponds since 2018. In November 2020, SRP sought a federal exception, provided it could show the clay liner would not leak chemicals in nearby groundwater or surface water supplies.

The EPA issued a tentative denial in 2023 and made it official last year. At the time, the EPA said the site’s soil characteristics, engineering quality, groundwater and pond monitoring were not in compliance.

Three months after being denied, SRP submitted a request to extend closure of the evaporation pond, citing grid reliability and resource adequacy concerns, according to the EPA. 

SRP asked to reopen the clay liner application soon after that. The EPA says it received additional technical information, which informed its approval on July 23.

But Sandy Bahr with the Sierra Club says nothing has changed in this new application process other than the administration that’s in charge.

“SRP didn’t demonstrate anything more about their monitoring, didn’t demonstrate anything more that it wasn’t contaminating, and they certainly didn’t have a different liner,” Bahr said.

In a statement, SRP says that technical analysis shows the 200 to 250 feet of natural clay beneath the pond functions the same as a synthetic liner and is an effective barrier for the area’s groundwater.

SRP says it would have been required to spend more than $90 million and commit another 94 acres of land to waste disposal if it had not requested reconsideration of the application.

The July 23 approval allows SRP to continue operating the existing pond as is during the review process, and a final demonstration report will be submitted in mid 2027.

Background on Coal Ash Rule and later amendments

According to the Environmental Integrity Project and Earth Justice, a series of severe coal ash contamination events in 2015 led the EPA to pass its first-ever rules on the disposal of coal combustion residuals.

There are at least six neurotoxins and five known carcinogens contained in coal ash. If ingested by humans or animals through water sources, it can lead to cancer, kidney damage and reproductive or developmental harms.

In 2018, the Circuit Court of Appeals ruled that coal ash ponds that did not have a plastic liner were harmful to the environment and needed to be closed or retrofitted.

But many coal plants can still dump coal ash directly onto land if they can demonstrate that existing soil or clay liners won’t leak. That’s due to a 2020 EPA ruling, which gave utilities an alternate path — known as an alternate liner demonstration — and an option for extending the closure of unlined ponds.

Environmental advocates like Bahr are against clay or soil lined ponds given the risks.

“We want to see strong protections in place requiring those liners,” Bahr said. “Even from a basic, common sense perspective, having ponds that have high levels of pollution without a lining is just a bad idea.”

A Duke University study concludes that ash ponds or landfills that forgo a plastic liner, and instead rely on compacted soil or clay, raise the risk of water supply contamination across the U.S.