OCR Text |
Show CHAPTER VII 115 but not limited to, historic streamflows, the most critical period of record, and probabilities of water supply), shall find this to be reasonably necessary to assure deliveries under clauses (1) and (2) without impairment of annual consumptive uses in the Upper Basin pursuant to the Colorado River Compact; Provided, That water not so required to be stored shall be released from Lake Powell: (i) to the extent it can be reasonably applied in the States of the Lower Division to the uses specified in Article III(e) of the Colorado River Compact, but no such releases shall be made when the active storage in Lake Powell is less than the active storage in Lake Mead, (ii) to maintain, as nearly as practicable, active storage in Lake Mead equal to the active storage in Lake Powell, and (iii) to avoid anticipated spills from Lake Powell." Statements in House Report 1312, at pages 83, 84, 85 and 86, and in Senate Report 408, pages 62, 63, 64 and 65, deal with the Operating Criteria provisions (see also an "Analysis of Public Law 90-537, Colorado River Basin Project Act, Paul L. Bilhymer, General Counsel, Twentieth Annual Report of the Upper Colorado River Commission, dated September 30, 1968, pages 69-98). C. Formulation of Operating Criteria In October 1968, immediately following passage of the Colorado River Basin Project Act, field discussions were initiated by the Bureau of Reclamation to formulate a program for developing Operating Criteria. A Bureau Task Force, composed of representatives of the Denver, Salt Lake City, Boulder City and Washington offices, was created to act upon the matter. Subsequent discussions on January 27-29, 1969, indicated there was no agreement among the States on the magnitude of the Upper Basin share of the Mexican Treaty obligation. It was agreed that appropriate rule curves be developed, assuming delivery of 8.25 maf at Lee Ferry in order to determine the quantity of storage required in the Upper Basin to permit deliveries required by Article III(c) and (d) of the Compact without curtailing Upper Basin use; that the reservoirs will be operated on the basis of runoff forecasts, but releases from Lake Powell would be scheduled so that the powerplant will not be bypassed absent a spill. Also discussed were the relationship of the Operating and Filling Criteria. In February 1969, the Chief Engineer provided the Task Force with an initial draft of criteria. The draft of Operating Criteria followed the Task Force discussion of the following items: 1. Period of record to use; e.g., 63 years, 1906-1968, inclusive; 2. Studies with a 2,500 ftVs and 3,000 frVs Granite Reef Aqueduct; 3. Method of study-historic content of reservoirs on September 30, 1968, and three runoff sequences starting in 1969 as follows: 1908, 1938, and 1948; 4. Depletions in Upper Basin; 5. Virgin flow at Lee Ferry; 6. Demands at Lake Mead; 7. Operation of Upper Basin reservoirs, assuming that minimum power pool will be maintained at all reservoirs, and that 8.25 maf per year will be used as the minimum annual flow at Lee Ferry after CAP becomes operative; and 8. Operation of Lake Mead-not to be drawn below elevation 1083. The initial draft of Operating Criteria referred to paragraphs 3, 4, 8 and 10 of the Filling Criteria approved April 2, 1962. It stated that the operating rules are not to be construed as an interpretation of the Upper Basin States obligation under the Mexican Treaty, and that it contemplated that the reservoirs not be drawn down below the minimum elevations needed for the generation of power. The criteria would rely on runoff-forecasts, and on storage in the reservoirs and the demands for water therefrom in both Basins. A rule curve would be prepared on the basis of the critical runoff sequence starting in water year 1953 to determine the live storage capacity needed in the Upper Basin to meet a delivery requirement at Lee Ferry of 8.25 maf without curtailing Upper Basin uses; that the powerplant not be bypassed; that, prior to CAP, downstream requirements below Hoover will be met and that, after CAP, releases from Hoover will vary with the end of year elevation of Lake Mead, so that, for example, if Lake Mead is between elevations 1083 and 1100, diversions to CAP will be reduced to 340,000 acre-feet per year. In a joint letter to the Assistant Secretary dated June 11, 1969, the Lower Basin States urged that full consideration be given to all flow conditions, not just the low flows, and recommended an early meeting with the seven Basin States. |