Dive Brief:

• The Supreme Court on Tuesday announced it will hear a broad case on the Clean Water Act that could have major implications for utility infrastructure, particularly coal ash disposal facilities.

• The case, County of Maui, Hawaii v. Hawaii Wildlife Fund, concerns whether the CWA applies to pollution that seeps through groundwater before entering navigable waterways subject to the law. It focuses on a wastewater treatment facility in Hawaii, but lower courts have also provided split decisions on how the CWA applies to such pollution from coal ash facilities.

• Last year, federal circuit courts ruled that pollution from ash facilities owned by the Tennessee Valley Authority and Dominion Energy did not violate the CWA because they were not point sources of pollution. In the Tennessee case, the court said the proper avenue to address the pollution is the Resource Conservation and Recovery Act (RCRA) — another federal law facing litigation.

Dive Insight:

Though the Supreme Court case focuses on discharges from a wastewater treatment plant on Maui, the eventual ruling could have broad impacts on permitting for a variety of energy projects that can release diffuse pollution.

Arguments in the County of Maui case reflect similar issues at stake in the coal ash cases. The county argues that wastewater pumped out of the plant does not violate the CWA because it travels through groundwater — not subject to the federal law — before it reaches the Pacific Ocean. The Hawaii Wildlife Fund says the law still applies.

The EPA weighed in on the side of the environmental group during the Obama administration, arguing the CWA has long applied to groundwater if there is a direct hydrological link to a navigable waterway. But the Trump administration is now reviewing that finding and could recommend the court reverse the precedent.

How the court decides could influence billion-dollar disposal decisions for coal ash facilities across the U.S. When TVA lost a lower court decision regarding coal ash at its Gallatin plant in 2017, it estimated the cost of moving the waste to a lined landfill at $2 billion.

TVA won a temporary reprieve last year from the U.S. Court of Appeals for the 6th Circuit when it reversed that decision, holding that "migration of pollutants through groundwater" is excluded from the CWA.

A similar situation played out at Dominion’s Chesapeake Energy Center, where the 4th Circuit Court of Appeals last year struck down a lower court ruling that arsenic pollution from ash facilities at the plant violated the CWA.

In that case, the three-judge panel said a “simple causal link" between the groundwater pollution and pollution found in navigable waters "does not fulfill the Clean Water Act's requirement that the discharge be from a point source."

Instead of the CWA, the courts in both cases said this type of groundwater pollution falls within the regulatory scope of RCRA. That law is the foundation of the nation's first federal regulations on coal ash, finalized during the Obama administration, but it is also the subject of legal uncertainty.

Last July, the Environmental Protection Agency announced it would roll back the rule following a court challenge from utility companies, giving states the authority to set disposal standards. But then, in a different case decided in August, the D.C. Circuit Court ruled that the original, Obama-era rule was not protective enough.

Environmental groups in October filed a petition with the U.S. Court of Appeals for the District of Columbia Circuit, arguing it should vacate the offending parts of the EPA coal ash rule and force utilities to take cleanup actions immediately. EPA filed a response in late January, arguing that throwing out the rule could “compromise the reliability of the electric grid,” and asking the court to allow utilities to continue compliance efforts for its weakened rule.