DES MOINES, Iowa (AP) — Drivers in eight Midwestern states will be able to fuel up with a higher blend of ethanol throughout the year under a final rule announced Thursday by the Environmental Protection Agency.

The biofuels industry and farming groups, with support of Midwest governors, sought the end of a summertime ban on sales of gasoline blended with 15% ethanol for years. The higher blend has been prohibited because of concerns it could worsen smog during warm weather.

The move reflects the importance of ethanol to agriculture. The fuel additive consumes roughly 40% of the nation’s corn crop, so higher sales of ethanol could mean greater profits for corn farmers.

The rule, which takes effect in April 2025, will apply in Illinois, Iowa, Minnesota, Missouri, Nebraska, Ohio, South Dakota and Wisconsin. Those states grow the bulk of the U.S. corn crop and are home to much of the nation’s ethanol production.

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The EPA said it delayed implementation of the new rule because of concerns there wasn’t enough supply to meet demand this summer. Ethanol producers welcomed the change but criticized the EPA for that delay.

“While we are pleased to see EPA has finally approved year-round E15 in these eight states, we are extremely disappointed by the agency’s needless decision to delay implementation until 2025,” the Renewable Fuels Association, a trade group, said in a statement. “It’s helpful to finally have some certainty about 2025 and beyond, but what happens this summer?”

Most gasoline sold across the country is blended with 10% ethanol, though 15% blends are becoming increasingly common, especially in the Midwest. E15 summer sales still will not be allowed in most of the country during summer, though agricultural groups are pushing for a nationwide policy change.

The biofuels industry and politicians of both parties have portrayed ethanol as a product that helps farmers, reduces prices at the pump and lessens greenhouse gas releases because the fuel burns more cleanly than straight gasoline. However, environmentalists and others have said increased ethanol production can increase carbon releases because it results in more corn production, leading to increased use of fertilizer and greater releases of nitrate. Synthetic and natural fertilizers also are a leading source of water pollution.

The EPA has approved sales of E15 for cars and trucks manufactured after 2000. Grow Energy, another bioenergy trade association, estimates the higher blend will cost consumers 15 cents a gallon less than 10% ethanol.

Petroleum refiners have opposed the Midwest-specific rules, saying a special blend in one region would increase costs and could lead to tighter fuel supplies.

The American Petroleum Institute, a trade group, said a national standard was needed.

“We are concerned this piecemeal approach could weaken the resiliency of the region’s fuel supply chain,” Will Hupman, a vice president at the group said in a statement. “We continue to call on Congress to pass the bipartisan Nationwide Consumer and Fuel Retailer Choice Act, which would bring much needed consistency to the marketplace by allowing for the year-round sale of E15 nationwide, preserving access to E10 and eliminating the need for regional or state-specific waiver petitions.”