The scope of a potentially landmark case over groundwater pollution before the Supreme Court could widen.

A group of environmentalists asked the court this week to take up their lawsuit against the Tennessee Valley Authority over coal ash pollution from the authority’s power plants.

The Supreme Court has already agreed to hear another case that gets at this same question, Cty. of Maui v. Haw. Wildlife Fund. Briefing in that case is scheduled to wrap up this summer.

The environmentalists say TVA’s coal ash waste in retention ponds is seeping into the ground and then into the Cumberland River, a protected water body under the Clean Water Act.

The issue of whether this law was intended to regulate groundwater pollution is an uncertain one, with different appeals courts coming to different conclusions.

If the court’s justices ultimately side with the environmentalists on this issue, retention ponds and underground injection wells will no longer escape federal regulation and businesses across the industrial spectrum will be forced to find new, potentially costly ways to dispose of their effluent.

Divided Opinion

An energy company involved in a third groundwater pollution case coming out of South Carolina also asked the Supreme Court to hear its case, but the court hasn’t ruled yet on this request. Several other groundwater cases currently in appeals courts haven’t gone to the Supreme Court yet.

Frank Holleman, an attorney with the Southern Environmental Law Center who is representing the environmentalists in the TVA case, said he filed with the Supreme Court because he wanted his clients “to have the benefits of the Supreme Court’s ruling” in the Maui case.

If he hadn’t taken the case to the Supreme Court, “we would be left with the divided opinion of the Sixth Circuit, which ruled against us,” Holleman told Bloomberg Environment.

The U.S. Court of Appeals for the Sixth Circuit ruled last year that groundwater pollution, even when it flows into surface waters, is explicitly outside the scope of the Clean Water Act.

The case is Tenn. Clean Water Network v. TVA, U.S., No. 18-1307, 4/15/19.