Is the Sparta-Memphis Aquifer an interstate resource? That will be the question before Special Master Eugene Siler, Jr. when he hears arguments from attorneys representing Mississippi and Tennessee in the Supreme Court’s first interstate groundwater dispute.

The hearing follows more than a decade of litigation over the groundwater contained in the Sparta-Memphis Aquifer, which underlies Mississippi and Tennessee. The City of Memphis, just north of the two states’ border, has long depended on the aquifer as its sole source of municipal water. To supply over 250,000 residents, Memphis withdraws 187 million gallons from the aquifer daily, which Mississippi claims has exceeded the aquifer’s natural rate of recharge.

In 2007, Mississippi sued Memphis, claiming the city had wrongfully converted its property, 60 million gallons of groundwater per day. By withdrawing excessive amounts of groundwater, Mississippi claimed Memphis had created a zone of depression beneath its land that had caused Mississippi-owned groundwater to migrate to the subsurface beneath Memphis.

Initially, Memphis’ suit went nowhere. A district court dismissed the case, reasoning that the Supreme Court traditionally has had exclusive jurisdiction to equitably apportion interstate waters. An equitable apportionment would require Tennessee to participate. But because Mississippi sued in district court and failed to join Tennessee as a defendant, the court lacked jurisdiction to hear the case.

The Fifth Circuit Court of Appeals affirmed, and the Supreme Court denied a writ of certiorari to hear Mississippi’s appeal.

After several years of unsuccessful negotiation, the parties again turned to the Supreme Court. In June 2015, the Court granted leave for Mississippi to file a bill of complaint that Memphis— and Tennessee, joined this time as a co-defendant—had wrongfully converted the groundwater underlying Mississippi’s land. The bill of complaint did not request equitable apportionment but demanded $615 million in damages and “a declaratory judgment establishing Mississippi’s sovereign right, title and exclusive interest in the groundwater stored naturally in the Sparta Sand formation underlying Mississippi.”

The Court appointed Eugene E. Siler, a Sixth Circuit Court of Appeals judge, to gather evidence in the case as a Special Master. Special Master Siler scheduled a hearing for May 2024, 2019, in Nashville, on the preliminary issue of “whether the [Sparta-Memphis] Aquifer is an interstate resource.” The answer to that question will likely determine whether the Court will use equitable apportionment to resolve its first interstate groundwater dispute.