WASHINGTON, S.D. (WNAX) – Ethanol backers are unhappy with new rules from the Environmental Protection Agency that could reduce the gallons of ethanol required to be used by oil companies.

South Dakota Senator Mike Rounds says he wants to know why the EPA changed the formula.

Rounds says the law should work in favor of ethanol.

Rounds says it looks like the EPA wants to use a different formula than was in a earlier agreement.

A hearing on the proposed rule will be held next week and the comment period is open through November before it is finalized.