April 23 (UPI) -- The U.S. Supreme Court on Thursday ruled mostly in favor of an environmental group by saying the federal government must regulate some groundwater pollutants under the Clean Water Act.
The court voted 6-3, saying the law prevents pollutants from being discharged directly into larger bodies of water -- even if they do so from farther away, through indirect groundwater -- without a permit.
The Clean Water Act says companies must acquire a permit to discharge into navigable waters. But the Trump administration, using a loophole in the law's language, argued that no permit is needed if a pipe doesn't directly feed a larger body of water and instead empties into nearby groundwater.
The Supreme Court dismissed the reasoning with the loophole.
Justice Stephen Breyer, writing for he majority, said if the Trump administration used its interpretation, "then why could not the pipe's owner, seeking to avoid the permit requirement, simply move the pipe back, perhaps only a few yards, so that the pollution must travel through at least some groundwater before reaching the sea?"
"We do not see how Congress could have intended to create such a large and obvious loophole in one of the key regulatory innovations of the Clean Water Act."
The Supreme Court, though, tightened some of the wording the lower ruling from the 9th U.S. Circuit Court of Appeals.
The lower court wrote that permits are required when pollutants are "fairly traceable" from a pipe, through groundwater, to a navigable body of water. The high court decided "fairly traceable" was too broad of a term and said the permit should be required when pollution is the "functional equivalent of a direct discharge."
Maui County, Hawaii, brought the case to the Supreme Court last year after the 9th Circuit ruled in favor of a group of environmentalists who accused the local government of allowing treated wastewater to seep into the ocean and kill coral reefs.
The Lahaina Wastewater Reclamation Facility, a decades-old Maui treatment plant, processes millions of gallons of waste per day to be deposited into underground wells.
A 2013 Environmental Protection Agency study showed that 90 percent of wastewater leached through groundwater and ended up in the Pacific.
Maui County argued that it's not liable for environmental damage because the Clean Air Act doesn't explicitly state regulations for pollution via groundwater.