((a)) The President is authorized to declare the establishment of a river basin water and related land resources commission upon request therefor by the Council, or request addressed to the Council by a State within which all or part of the basin or basins concerned are located if the request by the Council or by a State (1) defines the area, river basin, or group of related river basins for which a commission is requested, (2) is made in writing by the Governor or in such manner as State law may provide, or by the Council, and (3) is concurred in by the Council and by not less than one-half of the States within which portions of the basin or basins concerned are located and, in the event the Upper Colorado River Basin is involved, by at least three of the four States of Colorado, New Mexico, Utah, and Wyoming or, in the event the Columbia River Basin is involved, by at least three of the four States of Idaho, Montana, Oregon, and Washington. Such concurrences shall be in writing.

((b)) Each such commission for an area, river basin, or group of river basins shall, to the extent consistent with —

((1)) serve as the principal agency for the coordination of Federal, State, interstate, local and nongovernmental plans for the development of water and related land resources in its area, river basin, or group of river basins;

((2)) prepare and keep up to date, to the extent practicable, a comprehensive, coordinated, joint plan for Federal, State, interstate, local and nongovernmental development of water and related resources: , That the plan shall include an evaluation of all reasonable alternative means of achieving optimum development of water and related land resources of the basin or basins, and it may be prepared in stages, including recommendations with respect to individual projects;

((3)) recommend long-range schedules of priorities for the collection and analysis of basic data and for investigation, planning, and construction of projects; and

((4)) foster and undertake such studies of water and related land resources problems in its area, river basin, or group of river basins as are necessary in the preparation of the plan described in clause (2) of this subsection.