Despite an 11th-hour lawsuit and a settlement vote by the Maui County Council, Maui’s decade-long injection well case will be argued this morning before the justices of the U.S. Supreme Court.

At 5 a.m. Hawaii time, David Henkin, attorney with Earthjustice’s office in Honolulu, will present oral arguments on behalf of plaintiffs Hawaii Wildlife Fund and three other Maui community groups, while attorneys from a Virginia law firm will represent Maui County.

Complaints about pollution from the Lahaina Wastewater Treatment Plant have been heard for decades, but after an Environmental Protection Agency-funded study in 2011 used tracer dye to link treated sewage from the plant to near-shore waters off Kahekili Beach, the community groups sued, accusing the county of violating the Clean Water Act.

Following an extended battle in lower courts, the dispute has surfaced as a national case with broad ramifications on the federal water rules that were established in the early 1970s.

How big of a deal is it?

The Office of the Solicitor General of the United States has been granted time to argue on the side of Maui County.

Amicus parties have joined the case from across the country, 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.

Earthjustice attorneys are calling it “the clean water case of the century” with potentially disastrous repercussions for clean water across the U.S.

At issue is whether the Clean Water Act requires a permit when pollutants originate from a point source but end up in navigable waters via a nonpoint source such as groundwater. While the law is silent on groundwater, the EPA interpreted the law that way all along.

But that changed in April when the Trump administration came up with a new interpretation that aligns with Maui.

According to the solicitor general, the text and history of the act support the conclusion that there is no violation when a pollutant is released from a point source, such as a factory, into the groundwater, even if it ultimately ends up in navigable waters.

Congress has repeatedly rejected proposals to regulate groundwater as a conduit for pollution, according to the solicitor general’s brief, and to rule otherwise would “upend the traditional federal-state regulatory balance” by substantially enlarging the authority of the EPA beyond what Congress intended.

However, a bipartisan group of former EPA administrators argues in a brief that the new interpretation rolls back Clean Water Act protections and opens a “huge loophole” in the protection of surface waters.

Earthjustice says it would allow industry to freely pollute U.S. waters as long as the pollution isn’t directly discharged into a water source.

Mayor Michael Victorino, who made a unilateral decision to go forward with the appeal in the face of a Council vote to settle, left Maui on Monday night to witness the oral arguments in person.

“This is a case of historic importance regarding home rule for Maui County,” Victorino said in a statement. “The Supreme Court can now settle this matter, and the county can manage its operations and resources with certainty under the law for the benefit of our residents and environment.”

Honolulu Attorney Robert Thomas also will be attending the arguments, with his students at the William and Mary Law School in Virginia, where he teaches property rights.

Thomas said the case is important because it has the potential to define more clearly when a property owner needs to get a federal Clean Water Act permit.

“If the plaintiff’s argument is accepted by the court, it could have huge practical implications for property owners who either have to obtain an expensive Clean Water Act permit or risk being held liable” for what might reach navigable waters, he said.

However, uncertainty remains whether the high court ultimately will have a say in the case. A lawsuit filed last week by state Rep. Angus McKelvey, the Maui Tomorrow Foundation and a trio of West Maui residents asks a judge to rule on the question of who gets to settle a lawsuit on Maui, the Council or the mayor.

The challenge, which seeks to give the power solely to the Council, isn’t expected to be heard until next month. But Supreme Court rules provide that an appeal may be withdrawn at any time before the court issues a written opinion, and that isn’t expected before summer.