The National Sea Grant Law Center


  • Mississippi v. Tennessee Case Update

  • October 19th, 2018 — by Catherine Janasie — Category: Groundwater

  • Although the U.S. Supreme Court has developed a common law framework for resolving disputes over interstate water resources, the Court has never resolved a dispute over groundwater resources. Mississippi v. Tennessee, a case over the use of groundwater by the City of Memphis near the MS-TN border, is the first case of its kind.

    The states of Mississippi and Tennessee have very different theories for the case. Tennessee is claiming the water is an interstate resource, and thus, the Court needs to determine how much water each state is entitled to use. Mississippi is treating the water in the aquifer as Mississippi property, not as an interstate resource, and is asking for damages for the water Tennessee has taken.

    An initial issue is whether the aquifer will be treated as an interstate resource, and there will be a hearing on this issue early next year.

    Equitable Apportionment

    Disputes over interstate water bodies are treated differently under water law. When two or more states disagree on how to share water resources between them, federal rules apply. Interstate water disputes are common, and sometimes states can negotiate agreements as to how to share water resources that cross state borders, such as the Great Lakes Compact. But when states can’t reach an agreement among themselves, the disputes can only be resolved by the Court, as the Court has original jurisdiction in all cases in which a state is a party.

    The Court has developed common law to resolve disputes over the allocation of interstate rivers through the doctrine of equitable apportionment. When apportioning water, the Court is not bound by the laws of the individual states.

    The Court has stated that equitable apportionment is a flexible doctrine, and it will consider all relevant factors of a case so that a just result is reached. The doctrine’s basis is that each state is entitled to “equality of right,” not equal amounts of water. In previous cases, the Court has given factors that will inform its decision. A major factor the Court has considered is the benefit to one state versus the present harm to the other one. However, as many of these factors deal with characteristics of surface water, not groundwater, the question remains how the Court would apply them to groundwater.

    In suits between states, the Court serves as a trial court and appoints a Special Master (often not an expert in water law) to run a trial-like process. The Special Master hears the parties’ initial motions and evaluates the evidence. The Special Master then makes findings of fact, conclusions of law, and recommends a decision for the Court. The Court then decides whether or not to follow the Special Master’s recommendation. The Special Master process can take years to complete.

    The Lawsuit

    In the current lawsuit, Mississippi is concerned with the City of Memphis pumping groundwater close to the MS-TN border. When you pump large amounts of groundwater, it creates what is known as a cone of depression. The pumping changes the flow of water, causing more water to flow your way and lowering the water table of your neighbor, forcing them to need a deeper well. Mississippi claims the City’s pumping has taken billions of gallons of water out of Mississippi, and that the water belongs to Mississippi.

    Mississippi has challenged this use before by suing the City of Memphis for monetary damages. In 2009, the 5th Circuit Court of Appeals dismissed Mississippi’s lawsuit ruling that Mississippi had framed its case incorrectly. The court determined that the aquifer was an interstate resource, so Tennessee, which was not named in the suit, was a necessary party and exclusive jurisdiction belonged to the Supreme Court. The Court denied review in that case, citing an equitable apportionment case in doing so.

    Despite declining to hear the previous case, the Court allowed Mississippi to file this new lawsuit. The states have widely varying arguments. Tennessee argues that the framework the Court has developed for surface water should apply to the underground aquifer that both states use. Under that doctrine, neither state has any right to the water until the Court apportions the water.

    Mississippi argues that the water is state property, claiming it owns the groundwater within the state and Tennessee needs to pay for the water it has taken. Thus, Mississippi has not asked for the water to be apportioned, but rather, has asked for monetary damages (not less than $615 million).

    Case Update

    The Special Master for the lawsuit is the Hon. Eugene E. Siler of the U.S. Court of Appeals for the 6th Circuit. The initial issue in the case is the Special Master’s determination on whether the case should be treated as an interstate water dispute (which could potentially dismiss the lawsuit, with no apportionment).

    After considering each state’s initial filings in the case, the Special Master issued a Memorandum of Decision in August 2016 that ordered an initial hearing on whether the aquifer was an interstate resource. In the Memorandum, the Special Master noted that he did not think that Mississippi had made its case in its initial pleadings.

    Since that time, the parties have been preparing for the hearing by gathering their experts, exhibits, and other evidence to make their case. The hearing has been set to start on January 15, 2019 in Nashville, TN. On June 1, 2018, Tennessee filed a summary judgment motion on the basis that the aquifer is an interstate resource. Mississippi has filed a response asking for the Special Master to deny Tennessee’s motion. In its response, Mississippi focused on the specific question the Special Master highlighted in his 2016 Memorandum of Decision - “whether the water that is at issue in this case is interstate in nature.” Relying on this language, Mississippi tried to make the case in its response that even though they are part of a larger aquifer, the Sparta Sand and Memphis Sand are separate aquifers and geologic formations, thus making the groundwater in Mississippi intrastate in nature.

    If Tennessee’s motion is denied, any pre-hearing briefs need to be filed by December 20, including an amicus brief by the United States if it chooses to submit one.

    The docket sheet for the Special Master can be found at:

  • Catherine Janasie
    Research Counsel

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