For the purposes of this Act—
(1)
the term Red River lands means lands along the approximately 116-mile stretch of the Red River from its confluence with the North Fork of the Red River on the west to the 98th meridian on the east between the States of Texas and Oklahoma;
(2)
the term Secretary means the Secretary of the Interior, acting through the Director of Bureau of Land Management;
(3)
the term “South Bank” means the water-washed and relatively permanent elevation or acclivity, commonly called a cut bank, along the southerly or right side of the Red River which separates its bed from the adjacent upland, whether valley or hill, and usually serves to confine the waters within the bed and to preserve the course of the river; as specified in the fifth paragraph of the decree rendered March 12, 1923, in Oklahoma v. Texas, 261 U. S. 340, 43 S. Ct. 376, 67 L. Ed. 687; and
(4)
the term “gradient boundary survey” means the measurement technique used to demarcate a division of ownership or jurisdiction along the South Bank under the methodology established by the United States Supreme Court which recognizes that the boundary line between the States of Texas and Oklahoma along the Red River is subject to such changes as have been or may be wrought by the natural and gradual processes known as erosion and accretion as specified in the second, third, and fourth paragraphs of the decree rendered March 12, 1923, in Oklahoma v. Texas, 261 U. S. 340, 43 S. Ct. 376, 67 L. Ed. 687.