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Environmental Blog

  • 30
  • June
  • 2015

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Supreme Court Grants Review in Interstate Groundwater Dispute

Water wars will return to the Supreme Court next term, this time in a lawsuit brought by the State of Mississippi against the State of Tennessee. On Monday, June 29, the Court agreed to review a claim by Mississippi that the City of Memphis and its water utility, backed by the state of Tennessee, are illegally pumping water from the Sparta-Memphis Aquifer on Mississippi’s side of the state line. The federal common law doctrine of “equitable apportionment”1governs interstate surface waters, but the Supreme Court has never before explicitly adjudicated an interstate dispute over groundwater. The case is Mississippi v. Tennessee, 143 Original.


The case involves water contained in the Sparta-Memphis Aquifer, a water-bearing sand formation that spans the Mississippi-Tennessee border. The City of Memphis began drawing water from the aquifer for municipal use in 1886, and has used it to supply drinking water throughout the region for over a century. In more recent years, the City has drawn more water for irrigation and industrial purposes, largely through the operation of its public utility, the Memphis Light, Gas and Water Division (MLGW). Increased pumping led to lower groundwater levels in the part of the aquifer below the City. Those lower water levels in turn create a large differential in the water pressure in that section of the aquifer and sections under other parts of Mississippi, Tennessee, and Arkansas. As a result of MLGW’s pumping, Mississippi contends, water stored in the aquifer in Mississippi moves north toward Memphis, even though it would remain in Mississippi under natural conditions.

In 2005, Mississippi brought an action for trespass and wrongful conversion against Memphis and MLGW—but not Tennessee—in federal district court. In its complaint, Mississippi alleged that a substantial portion of the groundwater that MLGW pumped out of the aquifer is Mississippi’s sovereign property, and that Mississippi was entitled to compensation. The district court dismissed the action, concluding that, absent an equitable apportionment between Mississippi and Tennessee of the water in the aquifer, the court could not evaluate whether Memphis and MLGW had pumped water that belonged to Mississippi. The court further explained that the relief requested by Mississippi would require the court to engage in a de facto apportionment of the aquifer, which would require joinder of Tennessee as a defendant, and that such a dispute would fall within the exclusive original jurisdiction of the Supreme Court. 2

In June 2009, the U.S. Court of Appeals for the Fifth Circuit affirmed, holding that the action could not proceed in Tennessee’s absence because the aquifer is an “interstate water source” that must be apportioned before any state may claim a judicially enforceable right to a particular share of water within it. The court of appeals explained that the aquifer flows, albeit very slowly, under several states and in that respect is indistinguishable from a river or lake bordered by several states. The court of appeals also affirmed that Tennessee could not be joined in the lawsuit without depriving the district court of subject matter jurisdiction. Mississippi then filed a petition for a writ of certiorari, which the Supreme Court denied the following year.

Simultaneous with filing its petition for a writ of certiorari, Mississippi filed a motion in the Supreme Court for leave to file a bill of compliant against Tennessee, the City of Memphis, and MLGW, seeking approximately $1 billion in damages. In addition to repeating its claims of trespass and conversion, Mississippi contended that an equitable apportionment was not necessary because there had already been an “inherent apportionment” of the groundwater in the aquifer upon Mississippi’s admission to the Union in 1817. Mississippi requested an equitable apportionment as an alternative form of relief, but only if the Court determined that Mississippi did not own and control the aquifer resources within its borders. The Supreme Court denied Mississippi’s motion without prejudice, which opened the door for Mississippi to refile at a later date.

Mississippi’s Argument

In June 2014, Mississippi again sought leave to file a bill of complaint in the Supreme Court, naming Tennessee as a defendant in addition to Memphis, and MLGW). In its motion, Mississippi alleges that MLGW has developed a groundwater pumping and distribution system consisting of “more than 170 wells and ten well fields pumping over 140 million gallons of groundwater daily for sale to MLGW’s customers,” and contends that much of the pumping occurs at three well fields near the Tennessee-Mississippi border, across from DeSoto County, Mississippi.

Mississippi contends that the groundwater at issue was “naturally collected and stored” in the Sparta Sand in Mississippi, and that under natural conditions, the water would not leave Mississippi’s groundwater storage. Mississippi further contends that pressure differentials caused by MLGW’s pumping creates a “cone of depression” that causes groundwater beneath Mississippi to move north toward Memphis, altering the water’s natural east-to-west path and leading to a substantial drawdown of stored groundwater in DeSoto County. Mississippi maintains that, by pumping groundwater from the aquifer, Tennessee has removed more than 252 billion gallons of water since 1985, and also alleges that Tennessee continues to draw between 20 and 27 million gallons of water from Mississippi every day.

Unlike its 2009 action, Mississippi is not seeking an equitable apportionment of the groundwater at issue. Mississippi instead contends that the case does not fall within the Court’s equitable apportionment jurisprudence because, although the aquifer straddles two states, the water at issue does not constitute a shared water natural resource. According to Mississippi, the water naturally accumulated within its borders before the formation of the States and under natural conditions, the water would never have moved into or been available in Tennessee. 

With this foundation laid, Mississippi argues that defendants’ pumping constitutes an unlawful taking of its groundwater. Mississippi requests damages of $615 million, based on the value of the groundwater taken from 1985 to 2012 (including prejudgment interest). In the alternative, Mississippi requests an accounting and disgorgement of profits, saved expenditures, consequential gains, and any other benefits realized by defendants as a result of the pumping. Finally, Mississippi asks the Court to order defendants to take all actions necessary to eliminate the cone of depression vis-à-vis Mississippi, including the funding, construction, and modification of Memphis-MLGW’s groundwater pumping systems.

Tennessee’s Reply

In its reply on behalf of defendants, Tennessee argues that Mississippi is relying on the same territorial property rights theory that the Supreme Court rejected when it denied Mississippi leave to file a bill of complaint in 2010. Defendants further contend that Mississippi has no enforceable rights to water in the aquifer until that water has been apportioned. In addition, Tennessee maintains that the Supreme Court’s doctrine of equitable apportionment applies to an action by one state that reaches into the territory of another state through the agency of natural law. Tennessee characterizes its commercial pumping operation, and the resulting drop in aquifer pressure, as an example of Tennessee reaching into Mississippi by the “agency of natural law.”

Tennessee also argues that Mississippi’s claims are barred by the doctrine of issue preclusion, which prevents a party from re-arguing an issue of fact that has already been determined by a previous court where no error was found. The district court and the Fifth Circuit both rejected Mississippi’s territorial property-rights theory, and determined that the aquifer is a shared interstate waterway subject to equitable apportionment. Tennessee asserts that these findings are conclusive; therefore Mississippi is precluded from raising these same issues before the Supreme Court.

Views of the Solicitor General

In October 2014, the Supreme Court invited the Solicitor General to file a brief expressing the views of the United States; he filed a brief on May 12, 2015. The Solicitor General recommended that the Court deny Mississippi’s motion for leave to file a bill of complaint. In the Solicitor General’s view, Mississippi failed to allege a cause of action because it cannot contend that Tennessee is taking its water until the aquifer resources have been apportioned. Not only has there been no apportionment, he emphasizes, but Mississippi expressly does not seek an equitable apportionment in this case. Accordingly, the Solicitor General concluded that the motion should be denied without prejudice to allow Mississippi to refile a “properly framed complaint for equitable apportionment of the Aquifer premised on concrete allegations of real and substantial injury.”


This case raises important issues regarding states’ groundwater rights and the appropriate standard for resolving interstate disputes over groundwater. To date, the Supreme Court has only applied the doctrine of equitable apportionment to disputes involving interstate surface waters. However, the Mississippi v. Tennessee original action concerns a source of groundwater that is arguably shared by the two states. Case law suggests that equitable apportionment could be applicable to this type of resource, but no Supreme Court decision has squarely addressed this issue. Alternatively, the Supreme Court may elect to develop a new standard to resolve disputes over interstate groundwater resources. In any event, litigation over groundwater is likely to become more common in the future, and a decision in this case will have important ramifications for the use and control of groundwater claimed by multiple states.

1 Equitable apportionment is a doctrine developed by the Supreme Court to resolve disputes between states over the use of an interstate water resource. Through equitable apportionment, the Court seeks to determine how to fairly allocate water among affected states. This allocation must be made before a state can sue another state over the misuse of an interstate water resource.

2 The U.S. Supreme Court has original and exclusive jurisdiction over a justiciable case or controversy between States pursuant to Article III, § 2, clause 2 of the U.S. Constitution and 28 U.S.C. 1251(a).

Posted at 06/30/2015 5:40 PM

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