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Environmental Blog

  • 13
  • October
  • 2016

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Mississippi v. Tennessee: Are Aquifers "Interstate Waters"?

A dispute in the United States Supreme Court between Mississippi and Tennessee may have lasting effects on interstate water law. The primary issue is whether an aquifer that crosses state lines should be considered “interstate waters,” subject to the doctrine of equitable apportionment. Equitable apportionment is used by the Court to resolve interstate disputes over surface water. But, the Court has never applied this doctrine to ground water, which has traditionally been viewed as an intrastate matter.

This dispute began in 2005, when Mississippi sued the City of Memphis and the Memphis Light, Gas & Water Division (“MLGW”) in federal district court alleging conversion and other claims regarding MLGW’s pumping of water from the Sparta-Memphis Sand Aquifer. The complaint alleged that pumping of the ground water caused Mississippi water in the aquifer to drain into the portion of the aquifer under Memphis, Tennessee.

The district court held that the doctrine of equitable apportionment applied, which led to two conclusions: (1) Mississippi should have included Tennessee as a necessary party under Federal Rule of Civil Procedure 19; and (2) the case should have been brought in the Supreme Court under the Court’s original jurisdiction because it was an interstate dispute. The district court dismissed the case without prejudice, and the Fifth Circuit affirmed.

In June 2014, Mississippi sued Tennessee, the City of Memphis, and MLGW in the Supreme Court, contending that the water taken from Mississippi’s side of the state line was not interstate water and not subject to equitable apportionment. The complaint seeks injunctive relief and damages of $615 million for water taken over a period of 20 years. Tennessee, supported by the United States as intervenor, argues that the water is interstate, meaning that Mississippi is not allowed to sue for injunctive relief or damages until either the Court has equitably apportioned the aquifer or an interstate agreement is in place.

On August 12, 2016, the Court-appointed Special Master issued a Memorandum of Decision, tentatively siding with Tennessee that “it does not appear that the complaint plausibly alleges that the Aquifer or the water within the Aquifer that Mississippi sues over—lacks an interstate character.” Mem. Dec. at 35. But the Special Master indicated that he would hold an evidentiary hearing on whether the aquifer is indeed interstate water to provide the Supreme Court with a more complete record.

After the hearing, the Special Master will recommend findings of fact and conclusions of law, which the Court will either accept or reject. If the Court holds that aquifers are subject to equitable apportionment, this will lead either to the Court equitably apportioning interstate ground water for interstate aquifers or, potentially, to the creation of interstate agreements like those developed for surface waters. If the Court allows Mississippi to proceed on its claims, this would open the door for similar claims by states for damages and injunctive relief. With either outcome, this case will likely have lasting effects on the law surrounding ground water.

Stay tuned to the Water Blog as the case progresses.

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