DES MOINES, Iowa (AP) — As ethanol producers see some of their most profitable months ever, the federal government is considering whether to lower the amount of the corn-based fuel that must be blended into gasoline.

If the EPA approves a proposal reducing the required amount of ethanol that must be used nationally from about 14 billion gallons to 13 billion gallons, it would hurt a biofuels industry that built plants and spent billions on research based on the standard Congress approved in 2007.

University of Illinois professor Scott Irwin estimates a model Iowa ethanol plant would have hit a record profit of $4.50 per bushel of corn processed at the end of March. The average profit was 20 cents per bushel from 2007 to 2013.

The EPA’s decision is expected in June.