EPA Reverses Course, Allows Salt River Project to Keep Dumping Coal Ash in Unlined Pond

EPA Greenlights Continued Coal Ash Dumping at Arizona Plant

The U.S. Environmental Protection Agency has authorized Salt River Project (SRP) to continue dumping toxic coal ash into an unlined pond at its Coronado Generating Station in Apache County, Arizona. The decision, announced in July 2026, allows SRP to keep using the pond while it prepares additional documentation for the agency’s review, sidestepping a previous denial issued in January 2025.

That earlier denial had cited violations of federal standards for coal combustion residuals (CCR), including evidence that the unlined pond was leaking contaminants into groundwater. In February of this year, however, the Trump EPA reversed course and proposed granting SRP’s request to ignore wastewater regulations and extend the pond’s closure deadline. Today’s approval makes that reversal final.

The pond contains a mixture of mercury, cadmium, chromium, and arsenic, all known to cause cancer and neurological harm. Unlined coal ash ponds have a long history of polluting groundwater and nearby waterways, posing serious health risks to surrounding communities. SRP’s facility sits near Navajo Nation lands, where residents have long raised concerns about water quality.

Environmental organizations and tribal advocates — including the Sierra Club’s Grand Canyon Chapter, Earthjustice, Tó Nizhóní Ání, and the Diné Water Rights Coalition — had submitted comments urging the EPA to uphold its initial denial, arguing the utility’s plan fails to protect public health. With the agency’s stamp of approval, the fight now shifts to the courts and community action.

Why the EPA’s Reversal Matters for Arizona’s Water and Regulatory Oversight

From Denial to Approval: A Regulatory Policy Swing

The EPA’s turnaround mirrors the broader deregulatory push under the Trump administration. In January 2025, under the previous administration, the agency found SRP’s application insufficient to demonstrate that the ash pond would not pollute groundwater. By February, new leadership at the EPA had already proposed overturning that finding. The final approval reveals a clear policy choice: prioritize utility operational flexibility over strict enforcement of coal ash disposal rules.

Legal and Public Pressure Mount Across Tribal Lands

The Coronado plant’s proximity to Navajo communities makes the decision especially contentious. Groups like Tó Nizhóní Ání and the Diné Water Rights Coalition argue that continued dumping threatens drinking water sources already strained by industrial activity. Sandy Bahr of the Sierra Club condemned the move, stating the agency is “enabling polluters to continue poisoning communities with toxic waste.” These organizations are expected to launch legal challenges, arguing the EPA has violated its duty to protect water quality and public health under the Resource Conservation and Recovery Act.

Long-Term Cleanup and Industry Signal

While SRP can now keep disposing of ash, the underlying dispute is far from resolved. The utility must still submit additional data to the EPA, and any future change in administration could reverse today’s decision again. The case also sends a signal to other operators of unlined coal ash ponds: the current EPA is less likely to enforce closure mandates, potentially slowing industry-wide cleanup efforts. For Navajo and environmental advocates, the immediate priority is documenting contamination and pressuring elected officials to intervene.

What Comes Next for SRP, Navajo Communities, and Legal Opponents

• For SRP: The utility must provide EPA with further documentation on groundwater monitoring and pond integrity, but can continue operations in the interim. Legal exposure remains high; a court ruling against the EPA could force accelerated closure and remediation costs.
• For Affected Navajo Communities: Residents can demand independent water testing from tribal and state health authorities to quantify contamination levels. Public pressure and congressional inquiries may compel oversight even if the EPA is unwilling to act.
• For Environmental and Tribal Groups: A lawsuit is highly probable. The coalition of Sierra Club, Earthjustice, Tó Nizhóní Ání, and Diné Water Rights Coalition has already detailed legal objections and is well positioned to challenge the EPA’s approval under the Administrative Procedure Act.
• For Other Utilities: Operators with similar unlined ash ponds should watch this case closely. The EPA’s leniency may not be permanent, and any reversal in court or by a future administration could reestablish stricter enforcement nationwide.