President Donald Trump signed an executive order Tuesday that took aim at former President Barack Obama’s Clean Water Rule. Though the exact wording of the order has not yet been released, it directed the Environmental Protection Agency and the United States Army Corps of Engineers to “reconsider” the rule.

Passed in 2015, the Clean Water Rule was essentially a clarification and addendum to the 1972 Clean Water Act. The latter bill laid out protection for waters that were “navigable” or, in layman’s terms, large, leaving America’s small bodies of water vulnerable. The Obama administration introduced the Clean Water Rule, also known as the Waters of the United States Rule, to define which of the nation’s small bodies of water would be subject to regulation.

The rule was met with significant opposition from farmers, developers and other groups, who felt it implemented excessive governmental regulations. Trump has called the legislation “a horrible, horrible rule,” adding that it “has sort of a nice name but everything else is bad.”

Environmental groups, however, said the law was necessary to keeping some of the nation’s important waters.

“This vital safeguard puts an end to over a decade of polluters taking advantage of a muddled law by restoring the Clean Water Act and putting the health of our communities and families first,” Michael Brune, the Sierra Club’s executive director, said in a statement at the time of the rule’s introduction.

Two years after its passage, the rule has never officially gone into effect thanks to a tangle of ongoing litigation and a stay issued by the 6th US Circuit Court of Appeals.

“It was a massive power grab,” Trump said Tuesday before signing the executive order. “Regulations and permits starting treating our wonderful small farmers and small businesses as if they were a major industrial polluter. They treated them horribly.”