The U.S. Supreme Court on Thursday struck down the EPA's definition of wetlands, giving a victory to farmers, homebuilders and others in the decades-long fight over when and for what the environmental agency can require federal permits. (Courtesy of the Iowa Department of Natural Resources)

The U.S. Supreme Court, in a major environmental decision Thursday, overturned the Environmental Protection Agency’s definition of wetlands that fall under the agency’s jurisdiction, siding with an Idaho couple who’d said they should not be required to obtain federal permits to build on their property that lacked any navigable water.

All nine justices agreed to overturn the 9th Circuit Court of Appeals’ ruling that endorsed the Biden administration’s broad definition of waters of the United States, or WOTUS, the term for what falls under federal enforcement of the Clean Water Act.

But they published four separate opinions that showed a 5-4 split in how far they would allow federal jurisdiction to extend.

Writing for the court’s conservative majority, Justice Samuel Alito said the Clean Water Act applies only to wetlands with a “continuous surface connection” to the navigable waters like streams, lakes, oceans and rivers that are directly covered by the law.

The Biden administration’s definition — that said an area with an ecologically “significant nexus” to a navigable waterway was subject to Clean Water Act enforcement — would put nearly all waters and wetlands in the country under federal jurisdiction, with little room for state enforcement, Alito wrote.

Wetlands must be virtually indistinguishable from the navigable waters for federal jurisdiction to apply, he wrote.

But conservative Justice Brett M. Kavanaugh, with the court’s three liberals joining, wrote that a continuous surface connection to navigable waters was not strictly necessary for wetlands to fall under federal jurisdiction, but that Michael and Chantell Sackett, the Idaho property owners who challenged the federal definition, should still prevail in the case.

Kavanaugh, in a notable departure from the usual alliance on the court, said the majority rewrote the law and introduced new questions about wetlands that have long been subject to federal jurisdiction.

“The Court’s new and overly narrow test may leave long-regulated and long-accepted-to-be-regulable wetlands suddenly beyond the scope of the agencies’ regulatory authority, with negative consequences for waters of the United States,” he wrote.

Lengthy legal fight

The case is part of a decades-long legal conflict to define the reach of the Clean Water Act.

Agricultural interests, homebuilders and Republican officials have argued that the federal regulations impose an undue burden and should be applied narrowly.

“The Supreme Court just ruled that Biden’s overreaching WOTUS interpretation is unconstitutional,” Missouri Attorney General Andrew Bailey, a Republican, said on Twitter. “This is a huge win for farmers across America.”

Environmental groups and Democrats have argued for a broader definition that they say allows the federal government to offer important protections.

“Federal protections that don’t depend on local politics or regional polluter influence are essential to vulnerable and disadvantaged communities nationwide,” Jim Murphy, the director of legal advocacy for the National Wildlife Federation, said in a statement “The court’s ruling removes these vital protections from important streams and wetlands in every state.”

Murphy called on Congress and state governments to adopt stronger standards.