Maui’s multimillion-dollar appeal to the U.S. Supreme Court ended Thursday with a rejection of the county’s argument that it doesn’t need Clean Water Act compliance to inject treated sewage from its Lahaina sewer plant into ground­water that eventually winds up in the ocean.

In its 6-3 decision, the justices not only rebuffed Maui County, but rejected Trump administration and industry allies that sought to loosen water pollution requirements in what turned out to be a high-profile case that was followed across the country.

“The court sent a clear message that Maui County’s view of the law is as wrong as the day is long,” said David Henkin, the Earthjustice attorney who argued the case before the high court in November.

Henkin called the decision a huge victory for clean water for all Americans.

“I couldn’t be happier about the court’s resounding declaration for clean water and the fact they are serious about not allowing polluters to make up loopholes that don’t exist,” he said.

The court described as “unreasonable” Maui County’s argument that sewage that winds up in the ocean is exempt from the Clean Water Act because it isn’t directly dumped there.

“We hold that the statute requires a permit when there is a direct discharge from a point source into navigable waters or when there is the functional equivalent of a direct discharge,” Justice Stephen Breyer wrote for the court.

In its conclusion, the court called the 9th Circuit’s ruling in the case overly broad and sent it back to the lower court for further proceedings “consistent with this opinion.”

Mayor Michael Victorino issued a statement Thursday, saying the ruling was “a step toward the clarity we have advocated for.”

“The Supreme Court agreed with the County of Maui that the 9th Circuit ruling was too broad and could possibly affect millions of homeowners with septic systems,” Victorino said. “The Supreme Court also confirmed that discharges to groundwater are the responsibility of the states, which allows us to address this problem at a local level.”

The county began fighting the wastewater case in 2012, after four community groups — Hawai‘i Wildlife Fund, Sierra Club-Maui Group, Surfrider Foundation and West Maui Preservation Association — filed a complaint in federal District Court alleging the Lahaina sewage treatment plant was violating the Clean Water Act by injecting millions of gallons of treated wastewater into the ground daily.

Studies from at least a couple of federal agencies have shown that the treated wastewater travels in the groundwater and winds up in the ocean, where it harms coral reefs off Kahekili Beach Park.

Outside counsel costs

After losing in court twice, the county appealed to the Supreme Court, spending a cumulative $4.3 million for outside counsel.

Following an influx of new members, the Maui County Council voted last year to settle the lawsuit. But Victorino made a unilateral decision to continue with the appeal after county attorneys said the Council couldn’t drop the case on its own.

Victorino said he hoped a favorable ruling by the high court could allow Maui to continue using the injection well system until the county finds a feasible method to replace it. He also said he wanted to avoid huge costs from lawsuits and onerous regulatory mandates.

The dispute emerged as a national test case over the scope of the Clean Water Act and specifically over whether the law requires a permit when pollutants originate from a point source but end up in navigable waters via a nonpoint source such as groundwater.

Governmental and private interests across the country took sides, generally with blue states, conservation organizations and liberal-leaning groups lining up behind the Maui community groups and the Trump administration, government, industry and red states backing Maui County.

The court Thursday sided with the community groups, saying the discharge of polluted water into the ground, rather than directly into nearby rivers, oceans and other navigable waterways, does not relieve sewage treatment plants or any other kind of industrial uses of complying with the Clean Water Act.

Chief Justice John Roberts and Brett Kavanaugh joined the court’s liberal justices in the majority opinion.

In his statement Thursday, Victorino did not appear to view the ruling as a setback.

“The court reversed the 9th Circuit ruling and sent the case back to the lower court. What this means for Maui County is — as we have said all along — that the County has and will continue to work with our state regulators to follow the rules and regulations as Congress set them out,” the mayor said.

Victorino pointed out that the court did not rule that the county needs a National Pollutant Discharge Elimination System Permit required under the Clean Water Act.

“It set up factors for agencies to consider in determining whether a permit is required. We look forward to further clarity from our local regulators and working collaboratively to protect our waters,” he said.

But Henkin noted that the opinion strongly suggests that a permit will be needed.

“I hope the county gets the message to stop wasting taxpayer dollars and just fix the problem,” he said.

Henkin said a conditional settlement reached five years ago is still open to the county. Among other things, it calls for the county to fund at least $2.5 million in West Maui projects to divert treated sewage from the injection wells and to pay a $100,000 penalty to the federal government.

Councilwoman Kelly King, who led the Council opposition to the Supreme Court appeal, said the mayor is putting a positive spin on what she described as “a colossal waste of funds.”

”Now we’re right back at the 9th Circuit — right where we were $4 million and four years ago,” she said.