Opinion of the Court
in and around Memphis. Joint Statement of Stipulated and Contested Facts 101. Some of these wells are located just a few miles from the Mississippi–Tennessee border, though all are drilled straight down such that none crosses the physical border between the States. Id., at 101–102, 106. MLGW’s pumping contributes to a cone of depression that underlies both the City of Memphis and DeSoto County, Mississippi. Report of Special Master 21–23; Hearing Tr. 206, 435–436, 525.
Mississippi argues that MLGW’s pumping has altered the historic flow of groundwater within the Middle Claiborne Aquifer. Mississippi concedes that some water naturally flows from the part of the aquifer beneath Mississippi to the part beneath Tennessee. But only to the extent of some 30 to 60 feet per year. See Exceptions Brief for Mississippi 8; see also Report of Special Master 24 (“Mississippi does not dispute the expert consensus that at least some quantity of groundwater … crossed the border under natural conditions.”). Mississippi contends that MLGW’s pumping has substantially hastened this existing flow, allowing Memphis to take billions of gallons of groundwater that otherwise would have remained under Mississippi for thousands of years.
B
In 2005, prior to the present litigation, the Attorney General of Mississippi sued the City of Memphis and MLGW in Federal District Court. The suit alleged that Memphis had wrongfully appropriated groundwater belonging to Mississippi through its pumping activities. Mississippi sought hundreds of millions of dollars in damages.
The District Court dismissed the suit for failure to join Tennessee, which it determined was an indispensable party. Hood ex rel. Miss. v. Memphis, 533 F. Supp. 2d 646, 651 (ND Miss. 2008). The Fifth Circuit then affirmed. Hood ex rel. Miss. v. Memphis, 570 F. 3d 625 (2009).
