The U.S. Environmental Protection Agency has approved Salt River Project’s application to keep operating the unlined coal ash pond at its Coronado Generating Station in Apache County, Arizona, accepting the utility’s demonstration that the impoundment does not pollute groundwater. The decision, announced July 23, effectively grants an exception to the liner requirement that the federal Coal Combustion Residuals (CCR) rule has applied to surface impoundments since 2015. It is also the most concrete signal yet of how the current EPA intends to treat the CCR program: not as a cleanup mandate, but as an administrative process in which utilities can win approval to continue operating legacy infrastructure.
What the EPA decision actually changes at Coronado
The CCR rule, finalized in 2015, required unlined coal ash ponds to either close or demonstrate that they are not causing groundwater contamination. That demonstration – formally a “no migration” petition – was designed as a narrow exception for sites that could prove, with site-specific hydrogeological data, that contaminants were not leaving the impoundment boundary. In practice, the EPA has historically granted these sparingly and with conditions attached.
SRP’s Coronado Generating Station is a coal-fired plant in eastern Arizona, on the Colorado Plateau near the Navajo Nation, that has operated since the late 1970s. The pond in question is an unlined surface impoundment holding coal combustion residuals – the ash, slag, and scrubber waste left over from burning coal. The application SRP submitted, and the EPA has now approved, was supposed to demonstrate that the pond does not pollute groundwater. The agency’s approval means the pond can continue operating without a liner, at least for now.
The decision lands in a specific regulatory moment. The EPA under the current administration has been rolling back elements of the CCR rule since 2025 – extending compliance deadlines, narrowing groundwater monitoring requirements, and signaling a more permissive posture on enforcement. This approval is consistent with that trajectory, but it is also more than a policy signal: it is a binding administrative decision on a specific facility, which means it carries legal weight that guidance documents do not.
The source article, published by CleanTechnica, frames the decision critically – the headline calls it approval to “recklessly dump toxic waste.” That framing reflects a broader concern among environmental groups that the CCR program, as now administered, is failing to protect groundwater at the hundreds of coal ash sites across the country. Coal ash contains arsenic, lead, selenium, and hexavalent chromium, among other constituents; whether those are migrating into groundwater is precisely what the no-migration demonstration is supposed to answer.
Coal ash liability is migrating from balance sheets to groundwater
The Coronado decision connects to a much larger trend: the slow, expensive, and legally contested cleanup of coal ash at retired and retiring coal plants nationwide. Roughly 300 coal-fired units have retired since 2010, and the vast majority left behind ash ponds and landfills. The EPA’s own estimates from earlier in the CCR program’s life put the total cleanup cost in the tens of billions of dollars – a liability that utilities have been reluctant to book and that regulators have been reluctant to force.
The pattern here is familiar. Duke Energy’s coal ash settlements in North Carolina, which ran into the billions, established that groundwater contamination from unlined ponds can persist for decades and that utilities will ultimately pay for it, whether through litigation or through mandated closure. The Coronado approval suggests a different path: rather than forcing closure, the agency is willing to accept the utility’s own data showing no migration. If this becomes the norm, the economic logic flips – utilities can defer closure costs, keep the pond operating, and push the environmental risk into the future.
That points to a significant cost shift. If SRP had been required to close the pond, it would have faced costs on the order of tens of millions of dollars – excavation, transport, and disposal of the ash, plus groundwater monitoring and remediation if contamination is found. By securing approval to continue operating, SRP defers that expense. But the deferral is not a cancellation: coal ash ponds do not stop leaking because an EPA application was approved. The question is whether the no-migration demonstration was accurate – and that is a question only independent monitoring data can answer.
There is also a political economy dimension. Coronado sits in Apache County, on the edge of the Navajo Nation, in a state where coal has been a political and economic pillar for decades. The plant’s future is tied to the broader decline of coal in the Southwest – the nearby Navajo Generating Station closed in 2019, and Coronado itself has long been slated for retirement. Approving continued operation of the ash pond is, in effect, a way of managing the plant’s tail risk without confronting the closure cost head-on. That may be politically convenient, but it leaves the groundwater question unresolved.
Who the Coronado approval hits first
- Utility planners and generation owners: The approval establishes a precedent that no-migration demonstrations can succeed under the current EPA – meaning closure of unlined ponds may be deferrable, but only if you can produce hydrogeological data the agency accepts. Plan for the possibility that your own ponds face the same test, and budget for the monitoring that demonstration requires.
- Environmental compliance and legal teams: Expect legal challenges from environmental groups to this decision, and expect those challenges to test the evidentiary basis of the no-migration finding. If you hold a similar application in process, watch whether the litigation succeeds – it will shape how the agency handles yours.
- Investors and credit analysts: The decision defers, rather than eliminates, a large environmental liability at SRP. Factor the risk that groundwater contamination is later confirmed – and that cleanup costs, plus potential litigation, land on the utility’s balance sheet anyway.
- Water utilities and local communities: If you draw from aquifers near a coal ash pond, this decision is a reminder that the regulatory gatekeeping on unlined ponds has loosened. Independent groundwater monitoring may be the only reliable check on whether contamination is actually occurring.
What to track after the EPA’s approval
- Litigation timeline: Environmental groups – including the organizations that have sued the EPA over CCR rollbacks before – are likely to challenge this approval in federal court. The filing window and the court’s response will be the first concrete test of the decision’s durability.
- Groundwater monitoring data: SRP is required to keep monitoring the pond’s perimeter wells. Whether that data is released publicly, and what it shows in the coming quarters, will tell you whether the no-migration finding holds up in practice.
- Copycat applications: Watch whether other utilities with unlined ponds – particularly in the Southwest and the Powder River Basin states – file similar no-migration petitions in the wake of this approval. The volume of filings will indicate whether this is a one-off or a policy shift.
- Coronado’s retirement schedule: SRP has long signaled plans to retire Coronado; the timing of that retirement will determine how long the pond remains in service and whether closure is eventually forced by the plant’s own shutdown.
Bottom line
The EPA has traded a certain cleanup cost for an uncertain contamination risk. By accepting SRP’s no-migration demonstration, the agency has deferred tens of millions of dollars in closure expense – but it has also placed the burden of proof on groundwater monitoring data that the public cannot independently verify. If that data later shows contamination, the decision will look not like regulatory relief but like a liability transfer from the utility to the surrounding community.
Read the full report at CleanTechnica.
Note: facts and figures attributed above to reflect that outlet's original reporting. Broader context, cross-sector connections, and forward-looking scenarios reflect independent analysis by our editorial team.
About this article: Drafted by Energy Ai with AI-assisted research and writing based on public reporting, then reviewed under our editorial process before publication.
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