DES MOINES, Iowa (AP) — The U.S. Environmental Protection Agency has told Iowa environmental regulators that changes made to state clean water standards last year violate federal regulations. The Iowa Environmental Protection Commission approved changes in August that eliminated a rigorous environmental assessment before allowing new contaminants to be introduced to streams, rivers or lakes by city wastewater treatment plants or industry.

The new so-called anti-degradation standards allowed a focus on cost when evaluating introduction of new contaminants into waterways. Environmental groups opposed the change saying it weakened Iowa’s clean water protections and commended the EPA Tuesday for rejecting the changes.

The Iowa Department of Natural Resources, which enforces state environmental rules, did not immediately respond to a message. It’s not immediately clear if the EPA determination will withstand scrutiny of the new Trump administration.