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Filling Criteria

As construction progressed on the Upper Basin storage units authorized by the Colorado River Storage Project Act of April 11, 1956, 70 Stat. 105, including Glen Canyon Dam, Secretary of the Interior Udall, in consultation with various interests in the Colorado River Basin, initiated studies to determine how Lake Powell could accumulate storage with the least possible disruption of the many activities, including power production at Hoover Dam, then dependent upon the flow of the river not being restricted in the Upper Basin.

Starting in October 1957, meetings of Basin States representatives were held with Interior officials at which hydrological data was considered. These were later refined by engineering groups of both Basins. Among the conflicting Upper and Lower Basin views were the obtaining of minimum power head at Glen Canyon Reservoir (elevation 3490 or 6.1 mat) at the earliest practicable time and at the same time dealing with any deficiency that might occur in the firm energy generation at Hoover Powerplant incident to filling the Upper Basin Storage Project reservoirs.

On January 16, 1960, Reclamation proposed a set of principles and operating criteria (later termed "Filling Criteria"). These, it should be noted, were based upon a reasonable exercise of Secretarial discretion without attempting to define the outer limits of either rights or obligations of any of the States or of the United States. These principles were issued February 12, 1960, and were revised following receipt of comments and suggested modifications in a series of meetings extending from March 1960 to May 1961.

On April 2, 1962, Secretary Udall approved Reclamation's redraft of the general principles which appeared in the Federal Register of July 19, 1962, 27 F.R. 6851. The most controversial of the principles was No. 5, which was that an allowance should be made for computed deficiency in arm energy generation at Hoover which might be caused by the four storage units in the Upper Basin; i.e., Glen Canyon, Flaming Gorge, Curecanti, and Navajo, but excluding the effects of evaporation from the surface of such reservoirs as a part of the theoretical streamflow used in the formula for computing allowance. (The initial draft considered only the presence of Glen Canyon on the river and was silent regarding evaporation losses.)

The allowance for computed deficiencies in Hoover arm energy is the difference between two calculations - the first in the so-called Hoover basic firm, which is the firm energy that would have been produced at Hoover without the four storage reservoirs on the river and using an overall efficiency factor for power operations of 83 percent. The second calculation would be to adjust the energy actually generated at Hoover to an efficiency factor of 83 percent (rather than 70-78 percent efficiency actually experienced).

The Secretary would determine how the allowance would be accomplished; i.e., (1) monetarily, if the incremental cost, that is, fuel replacement cost of generating substitute energy, is less than the selling rate for power from the Upper Basin projects, or (2) whether it might be well to compensate the Hoover Dam power contractors with kilowatt hours through the interconnection of the two power systems.

This principle, in particular, was vigorously attacked by the Upper Basin States as without legal basis and as implying a responsibility on the Upper Basin for energy deficiencies at Hoover which they denied. However, Principle No. 5 made provision for reimbursing the Upper Basin Fund after 1987 from Hoover Dam power revenues for purchasing power to meet Hoover deficiencies, but not for confirm or other energy from the storage project's powerplants. Interior's intention to secure reimbursement was reflected in an Additional Regulation No. 1 to the General Regulations for Generation and Sale of Power in accordance with the Boulder Canyon Project Adjustment Act, adopted by Secretary Udall on July 12, 1962, 27 F.R. 6850, which stated that the rates to be charged for electric energy after 1987 would include a component to return to the United States funds adequate to reimburse the Upper Basin Fund. No interest would be included in the reimbursement. Reclamation indicated its intention to make minimum use of dollars and maximum use of energy from Federal powerplants, but not firm energy, which would otherwise be sold at firm power rates.

The principles would be applicable during the filling period, defined as the time required to fill Glen Canyon (elevation 3700), with a cutoff date of May 31, 1987, the date when the Hoover power contracts expire. Provision was also made for earlier termination if conditions warranted and called for consultation with the States before such action.

During the filling period, uses of water below Hoover Dam, other than power, will be satisfied, including delivery of not more than 1.5 maf/yr to Mexico. Minimum power head (elevation 3490 - 6.1 maf available surface storage) would be sought at Glen Canyon at the earliest practicable time without drawing Lake Mead below its rated head (elevation 1123 - 14.5 maf available surface storage).

The partial closure of Glen Canyon Dam was accomplished March 31, 1963, when computationally the Hoover deficiencies began, at which time Lake Mead held 22.3 mat. This dropped to 15.4 maf at the beginning of January 1964. Lake Powell was about 3410 (80 feet short of the minimum power point of 3490). With a forecast of another poor runoff in 1964 the gates of Glen Canyon were ordered opened on March 26, 1964 by the Secretary to maintain elevation 1123 at Lake Mead, despite Upper Basin requests that water be retained in Lake Powell in order to start generation of energy by August 1, 1964. However, 6 weeks after the gates were opened; on May 11, 1964, the Secretary announced the closure of the gates at Glen Canyon and the modification of the 1962 Filling Criteria to reduce by 40 feet, from elevation 1123 (rated power head) to elevation 1083 (minimum power pool), the water level below which Lake Mead would not be drawn. This was conditioned on the fact that, in addition to the allowance for deficiencies in firm energy pursuant to the 1962 Filling Criteria, the United States would replace impairments in Hooves. Powerplant capacity and energy which result from lowering Lake Mead below elevation 1123 by reason of' storage of water in Lake Powell, and would also relieve the allottees of the costs of extraordinary maintenance of the turbines and generators resulting from such lowering. These costs would be charged to the Upper Basin Fund but were not subject to reimbursement as was the case for deficiencies in firm energy as determined pursuant to the 1962 Filling Criteria.

Minimum power operating level (6.1 maf at elevation 3490) was achieved in Lake Powell on August 18, 1964. Energy generation began September 4, 1964. To obtain this minimum power pool at Glen Canyon Dam the flow at Lee Ferry was restricted to 2,520,000 acre-feet in water year 1963 and 2,427,000 acre-feet in water year 1964. Because of the tight water situation, Secretary Udall also directed Lower Basin water users, on May 16, 1964, to reduce their water demands by 10 percent for the period of July through December 1964. The Metropolitan Water District of Southern California was exempted from the 10 percent cutback. Also, a suit by the Yuma Valley water users to overturn the decision was unsuccessful.

The water surface elevation of Lake Mead dropped to a low of 1088.1 in December 1964, but was restored to rated power head elevation of 1123 on June 23, 1965.

The Upper Basin has repeatedly sought termination of the Filling Criteria or relief from use of the Upper Colorado River Basin Fund for payment for energy deficiencies at Hoover Dam. This led to Section 502 of the Colorado River Basin Project Act, which provides for reimbursement to the Upper Basin Fund for monies used therefrom and replaced Additional Regulation No. 1.

During discussions on the formulation of the Operating Criteria, Upper Basin efforts to terminate the Filling Criteria were unsuccessful, as were other attempts in 1975 and 1978.


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