With the political winds at their backs, farm groups and irrigation districts are seeking to ensure the Clean Water Act definition of “waters of the United States” excludes irrigation canals and ditches.

Irrigation districts have not fallen under the act’s jurisdiction in the past, and the U.S. Supreme Court’s Sackett v. EPA decision supports keeping it that way, said Greg Morrison, executive vice president of the National Water Resources Association, whose members include irrigation districts in Washington, Oregon and other Western states.

“We think that irrigation infrastructure is exempt now, but we see these see-saw interpretations depending on the administration,” he said. “Ideally, it would be wonderful to get it codified in statute by Congress, but that’s a huge lift.”

The EPA announced in March it will scrap the Biden administration’s WOTUS rule and adopt a definition that follows Sackett. The court ruled that only “relatively permanent” water bodies and wetlands with a surface connection to navigable waters were covered.

Justice Samuel Alito’s controlling opinion didn’t explicitly address ditches, canals and other manmade features. But he warned an “unchecked definition” would expose “a staggering array of landowners” to civil penalties and criminal prosecution and force prudent landowners to ask permission from the federal government before doing anything with their land.

The Biden administration responded to the Sackett decision with a rule that left “relatively permanent” and “continuous surface connection” undefined. “We believe that the agencies may have intentionally left these terms undefined to expand their regulatory reach,” American Farm Bureau public policy vice president Samuel Kieff stated in comments to the EPA in April.

Although irrigation districts have not been subject to Clean Water Act enforcement, there has been a bit of unease, Washington State Water Resources Association executive director John Stuhlmiller said.

“We need it cemented in a rule,” he said. “Everybody waits for the other shoe to fall.”

The Washington Department of Ecology estimates the Sackett decision took federal protection away from about 50% of the state’s wetlands and 14% of its streams, Ecology spokesman Curt Hart said.

The EPA should only exclude from WOTUS excavated ditches that drain land away from water bodies, according to Ecology.

Whether the Clean Water Act applies to other ditches, including ones that carry irrigation water, should be determined on a case-by-case basis, Ecology argues.

If all ditches are excluded, landowners will underestimate the importance of ditches to clean water, according to Ecology. “This would result in more confusion, more water quality violations, and adverse impacts to fish and wildlife,” Ecology stated in comments to the EPA.

The California Farm Bureau said farmers and ranchers rely on ditches and a case-by-case analysis is a problem.

“Farmers and ranchers cannot overstate the importance of a rule that draws clear lines of jurisdiction that can be understood without the need to hire an army of consultants and lawyers,” the Farm Bureau told EPA.