Hawaiʻi attorney general, conservation groups challenge EPA rejection of state’s regional haze plan

Attorney General Anne Lopez and a coalition of conservation and public health organizations have each filed separate legal challenges to a US Environmental Protection Agency decision that partially rejected Hawaiʻi’s plan to curb pollution from power plants blamed for haze over Haleakalā National Park, including Hawaiian Electric Co.’s Kahului and Māʻalaea generating stations on Maui.

The state Department of Health identified the two Maui plants, along with two Hawaiian Electric plants on Hawaiʻi Island, as the leading human-caused sources of haze pollution affecting visibility at Haleakalā and Hawaiʻi Volcanoes national parks.

The Clean Air Act requires states to submit Regional Haze State Implementation Plans every 10 years to reduce pollution that obscures views in national parks and wilderness areas. State officials say haze-forming pollutants have been linked to health and environmental harm, and the coalition’s filing cited nearly 8,000 tons of sulfur dioxide and nitrogen oxides that will continue entering the air around the plants without the state’s plan in place, along with resulting fine particulate matter.

Hawaiian Electric had proposed retiring older, inefficient oil-burning units at the Kahului and Māʻalaea plants rather than install pollution-control equipment. Responding to a Maui Now request for comment on Wednesday, Mike DeCaprio, the utility’s vice president of power supply, said that installing controls on the aging units would have been prohibitively expensive and would have shown up in customers’ bills.

The utility’s retirement plan was intended to keep costs down while maintaining reliable service, DiCaprio said. The company still intends to retire the units, but wants to wait until replacement power sources are online first, he said, noting that an island grid has no backup if the utility can’t meet demand.

“We’re still committed to retiring these plants in a timeframe close to our original plans,” he said. “On an island, there’s no backup if we can’t meet demand. We’re still committed to retiring these plants in a timeframe close to our original plans as new renewable projects come online.”

DeCaprio disputed the state’s assessment that pollution controls were economically feasible, saying that conclusion assumed the units would keep running for another 30 years, which the company never intended. He put the cost of controls at $32 million for the Kahului plant, based on 2020 figures.

Hawaiian Electric reversed its earlier commitment to the retirement dates after the EPA changed administrations in 2025, according to state officials.

DeCaprio said the change in administration created uncertainty around utility-scale renewable projects that were expected to replace some of the retiring units’ generating capacity. He also pointed to recurring reliability issues on Hawaiʻi Island as a separate reason the company wanted flexibility to keep some units running longer if needed. Given those concerns, DeCaprio said, Hawaiian Electric contacted the EPA to explain the situation and to reiterate that it still intended to retire the units — just not on a fixed timeline that didn’t account for the delays.

The Department of Health was copied on that correspondence but never responded or engaged with the company’s concerns, DiCaprio said.

According to the coalition, the utility notified EPA in an August 2025 letter — more than a year after the state finalized its plan — that it no longer supported the retirements, citing grid reliability concerns the coalition described as speculative. On May 29, the EPA issued a final rule partially disapproving Hawaiʻi’s plan.

DeCaprio also said regional haze rules are not health-based and apply solely to visibility in national parks, adding that visibility impacts from ongoing volcanic eruptions far exceed those linked to power plant emissions in the state. Generator emissions will decrease as more renewable energy comes online toward the state’s 100% renewable portfolio standard, an effect he said the state’s plan does not account for.

State officials pushed back on the EPA’s characterization of the utility’s earlier commitment, saying the agency wrongly described the voluntary retirements as “unconsented” closures despite years of negotiation that led to those commitments being written into the state plan.

Isaac Moriwake, managing attorney for Earthjustice’s Mid-Pacific office, said in a statement that the EPA sided with Hawaiian Electric’s request to unwind the pollution controls, which he said would leave Hawaiʻi ratepayers continuing to cover the cost of imported fossil fuels.

Haleakalā National Park drew more than 850,000 visitors in 2025, part of visitor spending the coalition said supports thousands of jobs statewide, and research cited in the coalition’s filing shows park visitation can drop by as much as 8% when air quality declines.

“Hawaiʻi will fight to protect our people and our environment,” Kathleen Ho, the Department of Health’s deputy director for environmental health, said in a statement, adding that the state’s plan was tailored to Hawaiʻi’s circumstances and developed over years of collaboration.

Lopez said in a statement that Haleakalā and Hawaiʻi Volcanoes national parks hold cultural and environmental significance and are home to species found nowhere else, and that residents and visitors deserve the natural air quality and visibility the plan was meant to protect. The state is challenging the EPA’s action because it conflicts with the goals of the regional haze plan and relies on what she called an unlawful reading of the Clean Air Act, she said.

More information on the state’s regional haze program is available at health.hawaii.gov/cab/regional-haze.