The EPA partially denied Hawaiʻi’s 2024 Regional Haze State Implementation Plan, leaving in place some pollution-reduction steps but jettisoning the plan’s core strategy: shutting down at least two Hawaiian Electric Company oil-fired units at Kanoelehua-Hill a
For years, Hawaiʻi’s visibility campaign has been built around a promise that doesn’t belong to politics: protect the air in two places that are legally entitled to the highest level of protection.
Those two places—Hawaiʻi Volcanoes National Park on the Big Island and Haleakalā National Park on Maui—are designated as “Class I” under the Clean Air Act. Under Hawaiʻi’s 2024 Regional Haze State Implementation Plan. the state mapped out how it intended to comply with federal law and reduce haze and fine particulates in the skies visitors see and residents breathe.
On Friday, the U.S. Environmental Protection Agency stepped in and partially denied the state plan. The agency said its decision would leave some parts intact. but would discard the plan’s main thrust: Hawaiʻi’s long-term strategy that 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 is a relic. It was commissioned in 1948—like the oldest “dinosaurs of the industry” within the proposal’s scope.
In its press release, the EPA referred to the closures as “unconsented.” The agency also warned that the shift 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.”
Hawaiian Electric’s Kahului generating station on Maui was commissioned in 1948.
“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, said.
The EPA’s decision isn’t being treated as an isolated administrative move. It comes as part of a broader direction the agency has taken under Administrator Lee Zeldin. tied to President Donald Trump’s executive orders to promote what Zeldin has called “energy dominance.” And advocates say the practical impact will land on the same air that carries health risks and reshapes day-to-day life—especially around places protected for visibility.
Hawaiʻi’s haze plan was built for more than scenic clarity. In many parts of the state, hazy skies can impact tourism and public health.
Earthjustice is part of a group of 10 national environmental advocacy organizations—The National Parks Conservation Association. Earthjustice. Natural Resources Defense Council. and Center for Biological Diversity among them—preparing to respond to the EPA decision. Their message is direct: the EPA move will harm Hawaiʻi communities and result in dirtier air in the parks.
The argument now turns on what the EPA says it can’t allow—and what the advocates say the agency is trying to do instead.
HECO frames the move as a reliability trade-off. Mike DeCaprio, vice president of power supply at HECO, said the company still plans to retire the aging plants, but to do so by the end of 2028, more biofuel plants, 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,” DeCaprio said. “Making sure that the lights stay on is the most important part.”
In the middle of those competing claims—health and visibility versus reliability and replacement timelines—legal language is doing heavy lifting.
The EPA’s explanation relies on takings.
A 67-page comment submitted on an earlier draft accused HECO of exploiting the Trump administration’s fossil fuel agenda. The environmental advocates said the Clean Air Act was written in a way that already allowed for contingency plans if renewable energy wasn’t available. They also said HECO 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 the technology to improve air quality.
“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 saying the company had been “forced under the SIP to accept enforceable retirement deadlines.” 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. Those projects, she added, had slowed down due to permitting challenges, changes in tax incentives, and supply chain changes.
The EPA press office, in an emailed statement, said “Following this notification, 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 added that “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. but it pointed to the omission in its own letter to the EPA in April—after it became clear that EPA was responding to HECO’s request by shutting down the plan. In that letter. the state’s director of health. Kenneth Fink. said 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.
The company has also signaled it is raising customers’ rates, at least in part to compensate for the plant closures, Moriwake said. “HECO has a pending request right now,” he said. “It’s sitting in front of the PUC to increase customer rates by $45 million a year for this purpose.”
Even supporters of the state’s renewables push acknowledge the headwinds. Jeff Mikulina. executive director of Climate Hawai‘i. said renewable energy in Hawaiʻi faces obstacles. thanks in large part to the Trump administration’s tariffs and its choice to cut tax credits and other federal support. Still, he believes Hawaiʻi will continue to lead on renewables.
Mikulina pointed to what’s happening on Kauaʻi: local lawmakers approved two new solar+storage projects that could help the island reach 90% renewable energy by 2030. He said the long-term signal matters more than the near-term noise.
“It’s important to look at the long-term signal as opposed to the near-term noise. 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% renewable energy future. ” Mikulina said.
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.”
But advocates say the bigger concern may be how the EPA is building its legal reasoning.
They argue the EPA’s logic doesn’t just affect Hawaiʻi’s haze plan. In the agency’s legal rationale, it said the haze plan would unfairly restrict HECO’s use of its private property, described as “a total regulatory taking.”
“By asserting that the retirement deadlines in the 2024 SIP are now ‘forced. ’ EPA opens a massive loophole in the Act’s requirements. allowing facilities to entirely evade compliance with the Regional Haze Program. ” advocates wrote in their comments in April. They said they were concerned the agency could dismantle other parts of the Clean Air Act. including the National Ambient Air Quality Standards Program.
“They are signaling that they want to overhaul this entire regulatory scheme,” Moriwake said.
And even beyond the takings fight, the haze rule’s central technical question—how much of what people see in the sky is driven by natural sources versus man-made pollution—has become part of the dispute.
When the Kīlauea volcano is erupting. 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—such as the Mauna Loa processing facility named in the state’s 2024 SIP—also emit sulfur dioxide as well as nitrogen oxides, which has been shown to aggravate lung and heart conditions.
Determining the contribution of natural and man-made emissions requires complex, evolving math equations. EPAs under previous administrations used specific tools to calculate the region’s “natural visibility conditions” while accounting for episodic volcanic events.
But 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 disagreed. In their comments, they called the agency’s assertions “arbitrary and capricious.”
The fight over Hawaiʻi’s air—especially in Class I parks built to preserve visibility—now rests not only on emissions and reliability timelines, but on the interpretation of what the Clean Air Act can compel and what the EPA says it cannot force.
For communities watching the policy unfold. the stakes are plain: whether the plan’s teeth survive. whether the parks remain protected in practice. and whether the legal precedent created here stays contained within Hawaiʻi’s coastline—or spreads to the wider structure of air protection across the country.
EPA Hawaiʻi Regional Haze Clean Air Act Hawaiian Electric HECO Kanoelehua-Hill Kahului Haleakalā Hawaiʻi Volcanoes National Park Class I Takings Clause Earthjustice Department of Health Kenneth Fink Lee Zeldin energy dominance