The Middle Claiborne Aquifer is a large sand formation that contains groundwater within its sand’s porous spaces. The Aquifer spans beneath Mississippi, Tennessee, and at least six other neighboring states. Since 1886, the City of Memphis has withdrawn water from the aquifer to supply drinking water. Memphis also has withdrawn water for irrigation and industrial purposes. Due to increased water pumping, water levels in the aquifer have dropped, lowering the piezometric head (water pressure) in different locations, including between the two states’ borders. In 2005, Mississippi filed suit against the City of Memphis and the Memphis Light, Gas and Water Division (MLGW) on territorial property rights theory, claiming that the city and MLGW were stealing Mississippi’s groundwater resources. The District Court for the Northern District of Mississippi dismissed the case on a procedural ground. Mississippi subsequently filed a new complaint within the Supreme Court’s original jurisdiction, this time including Tennessee. Mississippi is seeking declaratory and injunctive relief as well as more than $600 million in damages for conversion of the groundwater. Mississippi argues its territorial property rights are being invaded. The suit explicitly disclaims reliance on equitable apportionment, which is the typical remedy supplied by the Supreme Court for disputes between states involving interstate water resources. The Court appointed a Special Master who found that the water of the aquifer was not “owned” by Mississippi and was, instead, an interstate resource subject to equitable apportionment. Both states objected to aspects of the Special Master’s Report.
Robert Abrams & Monik Markus, Does the Doctrine of Equitable Apportionment Apply to Conflicts between States over Groundwater Resources When Such Resources Are Derived from an Aquifer That Lies beneath More than One State?, 49 PREVIEW U.S. SUP. CT. CAS. 3 (2021).