The Trump administration has taken a significant step toward undoing a controversial 2015 rule that aimed to clarify the scope of federal authority over rivers, wetlands and other bodies of water. Critics contend the rule too broadly defined federally regulated “waters of the United States” and praised the administration’s plan. Environmentalists supported the 2015 rule and are gearing up to fight the administration’s action.

The U.S. Environmental Protection and the Army Corps of Engineers on June 27 announced a two-part proposal that seeks to rescind the 2015 Clean Water Rule, which brings smaller, state- regulated waterways and wetlands under federal pollution-control jurisdiction.

The issue is important to construction firms because the rule determines when they must get a federal permit for dredging or depositing fill in tracts near water bodies.

Repealing the 2015 rule would re­instate clean-water regulations applied since the mid-1980s. Further, it would set the stage for a second federal rule-making that will revise the “waters of the U.S.” definition in line with an executive order Trump signed in February, the agencies say. That directive cites the shared national interest of keeping navigable waters free of pollution “while … promoting economic growth, minimizing regulatory uncertainty, and showing due regard for the roles of Congress and the states under the Constitution.”

Roundly criticized by construction and other business groups as regulatory overreach by the federal government, the 2015 Clean Water Rule has been on hold since October 2015, when the 6th U.S. Circuit Court of Appeals issued a nationwide stay of the regulation. The court said that stay would permit “a more deliberate determination” of whether it is allowable under federal law. The U.S. Supreme Court is scheduled to hear arguments this fall on whether the appellate court has jurisdiction over the challenges.

The pending court case is one reason why construction groups, such as the Associated General Contractors of America, favor the Trump administration’s two-phase repeal plan. If the courts strike down the stay and allow the 2015 Clean Water Rule to go forward, “more sites would need certain kinds of federal permits, which would increase time and cost,” says Scott Berry, director of AGC utility infrastructure, environment and trade. Repealing the regulation “gets that rule out of the way, and the industry isn’t stuck with a sword of Damocles over its head,” he observes.

Nick Goldstein, American Road & Transportation Builders Association vice president for regulatory affairs, says the two-step plan provides regulatory certainty and “lets us start on a rule that provides a proper balance between federal and state jurisdiction.”

The process of rescinding the 2015 Clean Water Rule is expected to be as contentious as the regulation’s own earlier path. Environmental groups and congressional lawmakers who support that rule say implementing the repeal-and-replace plan could result in substantially revising the Clean Water Act itself. Trip Van Noppen, president of environmental law organization Earthjustice, is taking a stand against the administration’s plan. In a statement issued the day of the EPA-Corps announcement, he said his group “will continue to use the full strength of our bedrock environmental laws to protect communities and the environment.”

Environmental groups contend that, following the proposal’s publication in the Federal Register, the planned 30-day comment period is too short. Nearly 20 environmental organizations are seeking a comment period of at least six months­­, “approximately the amount of time that the agencies provided to comment on the 2015 Clean Water Rule” in 2014, states the groups’ letter to the EPA and the Dept. of the Army. More than one million comments were filed on that rule, of which “the vast majority” supported the regulation, the letter avers.

Even if the comment period stays “short,” Goldstein expects the overall rule-making process to be lengthy and fraught with litigation. But he adds, “We’ve got to do it right.”