; and (B) usually serves, as specified in the fifth paragraph of Oklahoma v. Texas, 261 U.S. 340 (1923)— (i) to confine the waters within the bed; and (ii) to preserve the course of the river. (6) South bank boundary line The term South Bank boundary line means the boundary, with respect to title and ownership, between the States of Oklahoma and Texas identified through the gradient boundary survey method that does not impact or alter the permanent political boundary line between the States along the Red River, as outlined under article II, section B of the Red River Boundary Compact enacted by the States and consented to by Congress pursuant to Public Law 106–288 (114 Stat. 919). 3. Survey of south bank boundary line (a) Survey required (1) In general The Secretary shall commission a survey to identify the South Bank boundary line in the affected area. (2) Requirements The survey shall— (A) adhere to the gradient boundary survey method; (B) span the length of the affected area; (C) be conducted by surveyors that are— (i) licensed and qualified to conduct official gradient boundary surveys; and (ii) selected jointly by and operating under the direction of— (I) the Texas General Land Office, in consultation with each affected federally recognized Indian tribe; and (II) the Oklahoma Commissioners of the Land Office, in consultation with the attorney general of the State of Oklahoma and each affected federally recognized Indian tribe; and (D) be completed not later than 2 years after the date of enactment of this Act. (b) Approval (1) State approval (A) In general Not later than 60 days after the date on which the survey under subsection (a)(1) is completed, the Secretary shall submit the survey for approval to— (i) the Texas General Land Office, in consultation with each affected federally recognized Indian tribe