Pursuant to the authority set out in the Reclamation Act of June 17, 1902, 32 Stat. 388, and Acts amendatory thereof or supplementary thereto, and the provisions of the Water Resources Planning Act of July 22, 1965, 79 Stat. 244, as amended [42 U.S.C. 1962 et seq.], with respect to the coordination of studies, investigations and assessments, the Secretary of the Interior shall conduct full and complete reconnaissance investigations for the purpose of developing a general plan to meet the future water needs of the Western United States. Such investigations shall include the long-range water supply available and the long-range water requirements in each water resource region of the Western United States. Progress reports in connection with these investigations shall be submitted to the President, the National Water Commission (while it is in existence), the Water Resources Council, and to the Congress every two years. The first of such reports shall be submitted on or before June 30, 1971, and a final reconnaissance report shall be submitted not later than June 30, 1977: Provided, That for a period of ten years from November 2, 1978

The Secretary of the Army, acting through the Chief of Engineers, is authorized to cooperate and participate with concerned Federal, State, and local agencies in preparing the general plan for the development of the water resources of the western United States authorized by the Colorado River Basin Project Act [43 U.S.C. 1501 et seq.].

The Congress declares that the satisfaction of the requirements of the Mexican Water Treaty from the Colorado River constitutes a national obligation which shall be the first obligation of any water augmentation project planned pursuant to section 1511 of this title and authorized by the Congress. Accordingly, the States of the Upper Division (Colorado, New Mexico, Utah, and Wyoming) and the States of the Lower Division (Arizona, California, and Nevada) shall be relieved from all obligations which may have been imposed upon them by article III(c) of the Colorado River Compact so long as the Secretary shall determine and proclaim that means are available and in operation which augment the water supply of the Colorado River system in such quantity as to satisfy the requirements of the Mexican Water Treaty together with any losses of water associated with the performance of that treaty: Provided, That the satisfaction of the requirements of the Mexican Water Treaty (Treaty Series 994, 59 Stat. 1219), shall be from the waters of the Colorado River pursuant to the treaties, laws, and compacts presently relating thereto, until such time as a feasibility plan showing the most economical means of augmenting the water supply available in the Colorado River below Lee Ferry by two and one-half million acre-feet shall be authorized by the Congress and is in operation as provided in this chapter.

There are authorized to be appropriated such sums as are required to carry out the purposes of this subchapter.