The emergency waiver issued by the EPA prevents retailers in most states from having to stop selling E15 gasoline on May 1. While the waiver remains in effect only through May 20, EPA Administrator Lee Zeldin signaled that he plans to keep issuing waivers through Sept. 15, the date when the federal government typically would allow E15 sales in all states again.

Most gasoline sold across the U.S. is blended with 10% ethanol, but 15% blends are becoming increasingly common, particularly in the Midwest, where most of the nation’s corn is grown. E15 gasoline generally costs at least 10 cents less a gallon than E10 gasoline, but the EPA had previously prohibited its sale during the summer over concerns that its use during the summer driving season could increase smog.

But the EPA has relaxed restrictions on E15, granting a series of short-term waivers in 2022, 2023 and 2024 to allow its sale nationwide through the summer. And last year, the EPA issued a rule allowing year-round sales in eight Midwestern states — Iowa, usually the nation’s top corn producer, as well as Illinois, Minnesota, Missouri, Nebraska, Ohio, South Dakota and Wisconsin.

Trump administration officials said Monday’s action will lower consumers’ costs and give them more choices at the pump while also increasing the demand for corn. They also described it as reducing America’s reliance on imported energy.

“Our nation’s great corn growers are critical to helping the U.S. achieve energy independence, which is essential to national security,” Agriculture Secretary Brooke Rollins said in a statement.

While the ethanol industry and Iowa officials praised the EPA’s action, the Renewable Fuels Association, a trade group for ethanol producers, argued that Congress should approve legislation allowing year-round E15 sales across the U.S.

“For the economic and energy security benefits of E15 to be fully realized, the marketplace needs long-term certainty,” President and CEO Geoff Cooper said.

The biofuels industry and politicians in both major parties argue that ethanol helps farmers, lowers prices at the pump and reduces greenhouse gas because the fuel burns more cleanly than straight gasoline.

But ethanol consumes about 40% of the nation’s corn crop, and environmentalists argue that higher corn production leads to higher use of fertilizers that are a leading source of water pollution.

Zack Pistora, Kansas lobbyist for the Sierra Club, said ethanol plants also use high amounts of water, and states like Kansas are worried about the depletion of aquifers. He said it’s “hypocritical” to portray ethanol as environmentally friendly and said the Trump administration should promote renewable energy, electric vehicles, public transportation and sustainable agriculture.

“We need to dramatically reduce our fossil fuel dependence, but relying on corn-based ethanol doesn’t put our country on the path it needs,” Pistora said in an interview.