Louisiana v. Mississippi
466 U.S. 96 (1984)

Annotate this Case

U.S. Supreme Court

Louisiana v. Mississippi, 466 U.S. 96 (1984)

Louisiana v. Mississippi

No. 86

Orig. Argued January 16, 1984

Decided April 2, 1984

466 U.S. 96


This original action was filed by Louisiana against Mississippi and a riparian landowner (Dille) to resolve a dispute as to the boundary between the two States in a reach of the Mississippi River. In 1970, Louisiana, acting in its capacity under Louisiana law as the owner of the riverbed out to the boundary line, executed an oil and gas lease covering the disputed area. In 1971, Dille, as the owner of riparian land in Mississippi who, under Mississippi law, has title to the riverbed out to the boundary line, executed a similar lease to the same lessee, who drilled a well directionally under the river from a surface location on Dille's land on the Mississippi side. The location of the "bottom hole" of the well -- which was completed in 1972 and has been producing continuously since then -- is known and agreed upon. After trial, the Special Master filed a Report, concluding that, at all times during the disputed period of 1972-1982, the well's bottom hole was within Louisiana, west of wherever the boundary might have been, and that it was not necessary to delineate the specific boundary during the relevant years. Mississippi filed exceptions to the Report.


1. At all times since the completion of the well in 1972, its bottom hole has been within Louisiana. Pp. 466 U. S. 99-106.

(a) Earlier original jurisdiction litigation between Louisiana and Mississippi in this Court has established that the "live thalweg" of the navigable channel of the Mississippi River is the boundary between the two States. A boundary defined as the live thalweg follows the course of the stream as its bed and channel change with the gradual processes of erosion and accretion. The ordinary course of vessel traffic on the river defines the thalweg. Pp. 466 U. S. 99-101.

(b) The Court agrees with the Special Master's conclusion, which is consistent with the testimony of Louisiana's two expert witnesses, that the live thalweg was to the east of the well's bottom-hole location for each of the years in question, thus leaving the well within Louisiana throughout the disputed period, and with his rejection of the view of Mississippi's expert witness that the boundary line migrated so as to shift the jurisdictional location of the well back and forth between the States during the relevant years. This conclusion resolves the case so far as

Page 466 U. S. 97

the Louisiana and Dille leases, and the consequences that flow therefrom, are concerned. Pp. 466 U. S. 101-106.

2. The Master properly concluded that the only issue to be resolved centered on the location of the well's bottom hole, and that it as not necessary to delineate the specific boundary in the area for each of the 11 years from 1972 to 1982. Pp. 466 U. S. 106-108.

Exceptions to Special Master's Report overruled and Report confirmed.

BLACKMUN, J., delivered the opinion for a unanimous Court.

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