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
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, any Federal official shall not undertake reconnaissance studies of any plan for the importation of water into the Colorado River Basin from any other natural river drainage basin lying outside the States of Arizona, California, Colorado, New Mexico, and those portions of Nevada, Utah, and Wyoming which are in the natural drainage basin of the Colorado River.