Key members in Iowa’s congressional delegation are expressing frustration about how the Environmental Protection Agency is managing the mandatory ethanol production target.

The Environmental Protection Agency has proposed a slight increase in the amount of biofuels that must be blended into gasoline and diesel fuel next year. However, Republican Senator Chuck Grassley suggested EPA Administrator Scott Pruitt may be violating the law by granting waivers to oil refineries so they don’t have to blend ethanol into gasoline.

Republican Senator Joni Ernst said Iowa farmers aren’t getting the “honesty and transparency” they deserve from the EPA because Pruitt is handing out “an unprecedented number” of waivers. Congressman Dave Loebsack, a Democrat from Iowa City, said those waivers were intended for small refiners in danger of going bankrupt. Instead, Loeback and others in Iowa’s congressional delegation complain Pruitt has been granting waivers to huge companies that are making huge profits.

Trade groups are raising the same issue. According to the Iowa Corn Growers Association, the EPA administrator is granting oil refiners a “back-door” option that has already cost farmers and the ethanol industry more than five billion dollars. One ethanol industry executive said the EPA’s proposed ethanol production mandate for 2019 “isn’t a real number” because of the waivers Pruitt is granting the oil industry.