EPA blocks key Hawaii haze closures over “unconsented” units

EPA partially – On May 15, the U.S. Environmental Protection Agency partially denied Hawaiʻi’s 2024 Regional Haze State Implementation Plan—plans meant to clear the air around Hawaiʻi Volcanoes and Haleakalā national parks. The agency kept some parts of the rule but walked ba

For years, Hawaiʻi’s haze plan had been designed around a simple promise: clearer skies for parks and people. The EPA’s decision this month punctured that promise at the point where the state’s long-term air strategy depended on retiring some of the grid’s oldest oil-fired power—units that have long been treated as the “dinosaurs” of Hawaiʻi electricity.

On May 15, the U.S. Environmental Protection Agency announced it had partially denied Hawaiʻi’s 2024 Regional Haze State Implementation Plan. The proposal was built to reduce haze and fine particulates and other man-made pollutants in two places protected under the federal Clean Air Act: Hawaiʻi Volcanoes National Park on the Big Island and Haleakalā National Park on Maui. Because both parks are designated as Class I under the Clean Air Act. their air quality is legally entitled to the highest level of protection.

Even though the EPA said it would leave some parts of the haze plan intact. it jettisoned the plan’s main thrust. Hawaiʻi’s long-term strategy included shutting down at least two Hawaiian Electric Co. oil-fired electricity generating units in the Kanoelehua-Hill and Kahului power plants by 2028. The Kahului unit was commissioned in 1948. The EPA called those closures “unconsented” and warned they could make Hawaiʻi’s grid less reliable and “violate the Takings Clause of the U.S. Constitution for the taking of private property without just compensation.”.

That legal framing landed hard on advocates and defenders of the original approach alike, because the decision reaches beyond air and into what the rule would have demanded of the power system.

“This is one of the biggest bombs to drop in Hawaiʻi so far from the EPA,” Isaac Moriwake, managing attorney of Earthjustice’s mid-Pacific office, told Civil Beat.

Earthjustice is part of a group of 10 national environmental advocacy groups—also including the National Parks Conservation Association. Natural Resources Defense Council. and Center for Biological Diversity—preparing to respond to the decision. The groups say it will harm Hawaiʻi communities and result in dirtier air in the parks.

For HECO, the dispute is not about whether the plants are aging. It’s about timing and the mechanics of replacement on small island grids.

Mike DeCaprio, vice president of power supply at HECO, said the company still plans to retire the aging plants. But to do it by the end of 2028, he said more biofuel plants and more solar farms and battery storage have to come online first.

“We felt that having a contingency to run these units longer if needed was in our interest, and in our customers’ interest, so that we don’t end up in a grid reliability issue,” DeCaprio said.

“Reliability on an island grid is a really tough issue, right? They’re very small grids. With size comes stability, and they don’t have size,” he said. “Making sure that the lights stay on is the most important part.”

The fight quickly broadened into a question that can be harder to settle than engineering schedules: what counts as a permissible requirement under the Clean Air Act when renewable energy timelines shift.

In a detailed 67-page comment filed on an earlier draft of the EPA’s decision. the environmental advocacy groups accused HECO of exploiting the Trump administration’s fossil fuel agenda. They asserted that the Clean Air Act was written to allow contingency plans if renewable energy wasn’t available. The advocates also said HECO had previously agreed to retire three of its oldest oil-fired generating units in the Hill. Kahului. and Māʻalaea plants after it was asked by the health department to submit a plan to upgrade technology to improve air quality.

Moriwake described the earlier deal in a way that points to the tension between obligations and costs.

“HECO was the one coming to Department of Health and saying. ‘Hey. we will commit to shutting down these plants in lieu of having to spend all kinds of money. which the ratepayers are going to pay for at the end of the day. to upgrade these plants to try to clean them up. It’s cheaper. it’s more reliable. it’s more affordable for our ratepayers to just shut them down. ’” Moriwake said.

Then. last August. Karin Kimura. director of the environmental division at HECO. sent a letter to the EPA’s regional administrator. In that letter. Kimura said the retirement deadlines were no longer viable because of “actual or potential cancellations and delays” in renewable energy sources coming online to replace the power plants. She added that those projects had slowed due to permitting challenges, changes in tax incentives, and supply chain changes.

In its emailed statement to Civil Beat, the EPA press office explained why it partially disapproved the state’s long-term strategy.

“Hawaii … needed to provide assurances that EPA’s approval of the unconsented source closure would not amount to a taking without just compensation under the Takings Clause of the U.S. Constitution,” the EPA press office told Civil Beat in an emailed statement. “Hawaii did not provide such assurances, and EPA was therefore required to partially disapprove the state’s long-term strategy.”.

The haze plan process had been overseen by the Department of Health, but HECO sent Kimura’s letter without the Department of Health’s involvement.

The health department did not respond to a request for comment from Civil Beat. but it did note the omission in its own letter to the EPA in April—after it became clear the EPA was responding to HECO’s request by shutting down the plan. In that letter. Kenneth Fink. the director of health. said the EPA’s response was “not consistent with the purpose of Clean Air Act Section 169A which was enacted to protect visibility in national parks and wilderness areas” and “directly conflicts with EPA’s previous guidance” for developing such plans.

HECO has also signaled it may raise customer rates. Moriwake said HECO has a pending request before the Public Utilities Commission to increase customer rates by $45 million a year to compensate for the plant closures.

Behind the dispute sits a broader political push. The decision is not the first time the EPA has blocked a similar plan—Colorado had seen a rejection tied to a proposal to close a coal plant. Still. this one marks a significant impact for Hawaiʻi and fits into a larger agenda tied to EPA Administrator Lee Zeldin. The EPA administrator has aimed to execute President Donald Trump’s executive orders promoting what Zeldin has called “energy dominance.”.

When Climate Hawai‘i’s Jeff Mikulina acknowledged that renewable energy in Hawaiʻi faces headwinds. he pointed to federal and policy shifts—thanks in large part. he said. to Trump administration tariffs and a move to cut tax credits and other federal support. But he also argued the state will keep leading on renewables. with attention on Kauaʻi. where local lawmakers approved two new solar-and-storage projects. Those additions, Mikulina said, could bring Kauaʻi to 90 percent renewable energy by 2030.

“It’s important to look at the long-term signal as opposed to the near-term noise,” Mikulina said. “And that long-term signal tells us that this technology is getting cheaper by the day. particularly energy storage. which is really that secret sauce that’s going to allow us to achieve our 100 percent renewable energy future.”.

In its email, the EPA press office said it is “committed to working with the state of Hawaii to revise the SIP, in order to both follow the law and achieve clean air for all in the state.”

Yet for many advocates, the legal argument isn’t the only fault line. It’s the way the EPA chose to treat the math of visibility.

To calculate how much emissions from volcanoes and human sources contribute to visibility impairment, regulators rely on complex, evolving equations. Under previous administrations. the EPA used tools to calculate the region’s “natural visibility conditions” while accounting for episodic volcanic events.

Hawaiʻi’s air is shaped by both human activity and nature. When Kīlauea erupts. vog—volcanic smog—adds sulfur dioxide and fine particulate matter to the air. particularly on the southern side of Hawaiʻi island. The Hawaiʻi Department of Health warns that even brief exposure can cause shortness of breath. chest tightness. and other respiratory problems.

Power plants and other industrial facilities—including the Mauna Loa processing facility named in the state’s 2024 SIP—also emit sulfur dioxide and nitrogen oxides, which has been shown to aggravate lung and heart conditions.

When the current EPA proposed its disapproval of the haze rule in February, it asserted that no methodology “has been developed that is able to fully screen out the volcanic impacts and thus isolate the visibility impairment caused by anthropogenic air pollution.”

The environmental groups disagree. In their comments, they called the agency’s assertions “arbitrary and capricious.”

The controversy over methodology and the controversy over what counts as a legal deadline both feed a larger concern: that the EPA might weaken not just Hawaiʻi’s specific haze rule, but the wider regulatory framework that governs visibility protection.

In their legal rationale. the federal agency argued that the haze plan would unfairly restrict HECO’s use of private property. in what it called “a total regulatory taking.” The advocacy groups said the logic opens a loophole in the Act’s requirements. They wrote that by asserting the retirement deadlines in the 2024 SIP are now “forced. ” the EPA opens “a massive loophole in the Act’s requirements. allowing facilities to entirely evade compliance with the Regional Haze Program.”.

They added that they were concerned the agency could dismantle other parts of the Clean Air Act, such as the National Ambient Air Quality Standards Program.

“They are signaling that they want to overhaul this entire regulatory scheme,” Moriwake said.

In the background of the legal filings and grid calculations, the practical stakes remain unmistakable: Hawaiʻi’s parks are legally protected as Class I areas, and the public is living with the air that protection is designed to preserve—even when nature, industry, and policy decisions intersect.

What happens next is now set in motion by the agency’s willingness to revise rather than enforce the plan as originally designed, and by the advocates’ insistence that both the methodology and the constitutional argument are being used to pull back requirements meant to reduce haze.

The EPA’s move, for now, changes the horizon of the state’s emissions retirement schedule—but it also puts a spotlight on the brittle edge of island power reliability and the difficulty of drawing a clean line between volcanic effects and man-made pollution.

EPA Hawaiʻi Regional Haze Clean Air Act visibility Hawaiian Electric oil-fired units Takings Clause Earthjustice Haleakalā National Park Hawaiʻi Volcanoes National Park vog Kīlauea biofuel solar battery storage Public Utilities Commission