A U.S. district judge has rebuffed Trump-era limits on the scope of the Clean Water Act (CWA), vacating a rule that the Biden administration had already targeted for revision as part of broader efforts to strengthen federal environmental protections.

Environmental Protection Agency

An order handed down by the U.S. District Court for the District of Arizona Monday vacated and remanded the 2020 Navigable Waters Protection Rule (NWPR), sending the Environmental Protection Agency (EPA) and U.S. Army Corp of Engineers back to the drawing board.

The NWPR, finalized by the Trump administration last year to narrow the definition of what constitutes “waters of the United States,” or what bodies of water fall under CWA jurisdiction, had been seen as favorable for Lower 48 oil and gas operators.

District Judge Rosemary Marquez concluded that allowing the NWPR to remain in effect could lead to serious environmental harm. The EPA and Army Corps “have identified 333 projects that would have required Section 404 permitting under the CWA prior to the NWPR but no longer do,” the judge wrote.

The agencies, and tribal groups named as plaintiffs in the case, raised concerns that “involve fundamental, substantive flaws that cannot be cured without revising or replacing the NWPR’s definition of ‘waters of the United States,’” Marquez found.

The NWPR was part of Trump-era efforts to roll back the Obama administration’s 2015 Clean Water Rule. Following a Biden executive order issued earlier this year, the EPA and Army Corps had already signaled their intent to revise or replace the Trump team’s changes to what waterbodies are regulated under the CWA.

“The seriousness of the agencies’ errors in enacting the NWPR, the likelihood that the agencies will alter the NWPR’s definition of ‘waters of the United States,’ and the possibility of serious environmental harm if the NWPR remains in place upon remand, all weigh in favor” of vacating the rule, Marquez wrote.

Another Trump-era change to water quality regulation, an effort to streamline CWA Section 401 certification, was targeted for revision earlier this year by Biden’s EPA. State-level CWA Section 401 procedures have provided a regulatory pathway for stalling natural gas pipelines.