WASHINGTON (Reuters) - The U.S. Supreme Court on Thursday rejected arguments by President Donald Trump’s administration seeking to limit the reach of a landmark water pollution law in a Hawaii dispute over wastewater indirectly discharged into the Pacific Ocean - a ruling hailed by environmentalists.

FILE PHOTO: The Supreme Court building exterior seen in Washington, U.S., January 21, 2020.REUTERS/Sarah Silbiger

The case involves whether Hawaii’s Maui County can be sued by environmentalists for allowing discharges from a sewage facility to reach the Pacific without a federal permit under the Clean Water Act. The wastewater was not directly discharged into the Pacific but rather into groundwater that ended up in the ocean.

The justices in a 6-3 decision threw out a 2018 ruling by the San Francisco-based 9th U.S. Circuit Court of Appeals that had allowed the lawsuit by the Hawaii Wildlife Fund and other environmental groups to proceed, saying it was too broad. They sent the case back to the 9th Circuit to apply a new test to decide whether the lawsuit can move forward, leaving the door open for the litigation to proceed.

“It’s a huge victory for environmentalists,” said David Henkin, a lawyer with environmental group Earthjustice who argued the case for the challengers.

Henkin voiced confidence that Maui County ultimately will be required to obtain a permit.

The Supreme Court adopted a middle ground, saying permits can be required under the Clean Water Act when the discharge into groundwater is the “functional equivalent” of the discharge from a pipe or other “point source.”

The ruling, authored by liberal Justice Stephen Breyer, was joined by the court’s three other liberals and two conservatives, Chief Justice John Roberts and Justice Brett Kavanaugh, appointed to the court by Trump in 2018.

The new interpretation would allow environmentalists to file lawsuits in certain circumstances when water is discharged into groundwater, an outcome Trump’s administration opposed. The administration, which has rolled back numerous environmental regulations, sided with the county in the case.

‘TIME AND DISTANCE’

The Supreme Court ruling avoids a situation, discussed by the justices during arguments in the case in November, in which entities could evade the permit requirement by simply building a pipe that terminates a few feet (meters) before reaching a river, knowing full well the discharge would end up in the waterway.

“Time and distance are obviously important,” Breyer wrote.

“Where a pipe ends a few feet from navigable waters and the pipe emits pollutants that travel those few feet through groundwater ... the permitting requirement clearly applies,” Breyer added.

The U.S. Environmental Protection Agency, which oversees Clean Water Act enforcement, said in a statement that the ruling “unfortunately leaves some uncertainty for the public, including private property owners.”

Timothy Bishop, a lawyer who filed a brief backing Maui County on behalf of agricultural industry groups, said the decision will lead to more litigation over the scope of the act.

“Fuzzy tests that encourage wasteful litigation really are not helpful to anyone except lawyers,” Bishop said.

The 9th Circuit had found that a Clean Water Act program - one that requires property owners responsible for polluted water discharged from pipes, drains or other “point sources” to obtain federal permits - should apply to discharges from the Maui County wastewater facility that end up in the Pacific.

The environmental groups accused the county of violating the Clean Water Act because several million gallons of treated wastewater from the Lahaina Wastewater Reclamation Facility ends up in the Pacific every day.

The Trump administration this week finalized a separate regulation that limits federal jurisdiction over certain bodies of water, a move that also face a legal challenge.