Operating Criteria

Section 602(a) of the Colorado River Basin Project Act of September 30, 1968, 82 Stat. 885, directed the Secretary of the Interior to "propose criteria for the coordinated long-range operation of the reservoirs constructed and operated under the authority of the Colorado River Storage Project Act, the Boulder Canyon Project Act, and the Boulder Canyon Project Adjustment Act" and to receive comments from the States.

The need for the criteria was the concern of the Upper Basin States as to their ability to recapture from a new project in the Lower Basin presently unused water apportioned to the Upper Basin when needed for their own development. As a result of negotiations the Basin Project Act contained a list of priorities to govern the storage of water in storage units of the Storage Project and releases of water from Lake Powell. The Act also provided that the Upper Basin's rights to the consumptive use of water apportioned to that Basin by the Colorado River Compact would not be prejudiced or reduced by any use thereof in the Lower Basin. In other words, storage in Lake Powell is the cornerstone of the Upper Basin's ability to deliver water to the Lower Basin to fulfill the requirements of Articles III(c) and (d) of the Compact and, at the same time, permit Upper Basin consumptive uses. Article III(c) deals with deliveries to Mexico and III(d) deals with deliveries of 75 maf to the Lower Basin each 10 years. The criteria were to be prepared and reviewed each year after an exchange of views with the States and affected parties.

The objective of the legislative requirements for the criteria was more efficient and reasonable river management. At the same time augmentation was emphasized in an effort to minimize the controversy over the Upper Basin's share of contribution to Mexico and whether the Gila River flows are accountable therefor. An example was the requirement that the first priority for the release of water from Lake Powell is to satisfy one-half of the deficiency in deliveries of water to Mexico, if any such deficiency exists and is chargeable to the States of the Upper Basin, but that the priority shall not apply in any year that the river is augmented sufficiently to satisfy the Treaty requirements and associated losses. Among other major issues involved in the discussions over the criteria were: Lake Powell bank storage; estimates of Upper and Lower Basin depletions; the use and magnitude of a specific figure for releases from Lake Powell (e.g., 8.23 maf; continuation of the Filling Criteria; and the use of a rule curve to accumulate storage in the Upper Basin reservoirs. On June 8, 1970, after evaluation of the comments of the Upper and Lower Basin States, Secretary Hickel adopted the Operating Criteria. A letter of June 9, 1970, from the Commissioner of Reclamation explained the rationale of the decisions on these comments. The Secretary concluded that the Filling Criteria would be continued, that energy needed to replace Hoover Dam deficiencies would be purchased, that the Upper Colorado River Basin Fund will be reimbursed pursuant to Section 502 of the Basin Project Act for monies used therefrom to purchase energy, except that the costs incurred in connection with impairment of capacity and energy resulting from the drawdown of Lake Mead below elevation 1123 feet incident to the attainment of minimum power pool in Lake Powell would not be repaid.

The criteria for coordinated long-range operation of Colorado River reservoirs, approved June 8, 1970, include the following provisions:

The Secretary may modify them from time to time and will sponsor a formal review at least every 5 years with the States participation. The Secretary shall transmit to Congress and the Basin States Governors an annual report, starting January 1, 1972, and each January 1 thereafter, describing actual operations for the preceding compact water year and the projected plan of operation for the current year (Article I(1)).

The plan of operation shall include a determination by the Secretary of the quantity of water considered necessary to be in storage as of September 30 of that year as required by Section 602(a) of Public Law 90-537 ("602(a) Storage"). The factors to be considered in arriving at that determination are listed; e.g., historic streamflow, the most critical periods of record, and probabilities of water supply, estimated storage depletions in the Upper Basin, including the effects of recurrence of critical periods of water supply, the report of the committee on probabilities and test studies dated October 30, 1967, and the necessity to assure that Upper Basin consumptive uses not be impaired because of failure to store sufficient water to assure delivery under Section 602(A)(1) and (2), Public Law 90-537 (Article II(1)).

If, in the plan of operation, either
(a) the Upper Basin storage reservoirs active storage forecast for September 30 of the current year is less than the quantity of Section 602(a) storage determined for that date, or
(b) the Lake Powell active storage forecast for that date is less than the Lake Mead active storage forecast for that date, the objective shall be to maintain a minimum release from Lake Powell of 8.23 maf for that year (Article II(2)).

Importantly, if the Upper Basin storage reservoirs active storage forecast for September 30 of the current water year is greater than the quantity of 602(a) storage, water shall be released annually from Lake Powell at a rate greater than 8.23 maf to accomplish the following objectives:
(a) To the extent it can be reasonably applied in the Lower Division States, but no such release shall be made when the active storage in Lake Powell is less than the active storage in Lake Mead;
(b) To maintain, as nearly as practicable, active storage in Lake Mead equal to the active storage in Lake Powell; and
(c) To avoid anticipated spills from Lake Powell (Article II(3)).

In the application of Article 11(3) the objective will be to pass the releases through Glen Canyon Powerplant as soon as practicable, utilizing the available capability of the powerplant, in order to equalize the active storage in Lake Powell and Lake Mead (Article II(4)).

Releases from Lake Powell pursuant to the criteria shall not prejudice either Basin's interests with respect to required deliveries at Lee Ferry pursuant to the Compact (Article II(5)).

Lake Mead is to be operated to meet Mexican Treaty obligations, reasonable consumptive use requirements of mainstream users in the Lower Basin, net river and net reservoir losses, and regulatory waste (Article III(1)).

Until Central Arizona Project water deliveries are made, Lower Basin reasonable consumptive use requirements will be met (Article III(2)). Thereafter, the consumptive use requirements will be met in light of the following situations: normal (7.5 maf); surplus (i.e., quantities greater than normal); and shortage (i.e., insufficient water to satisfy 7.5 maf annual consumptive use requirements) (Article III(5)). The criteria specified the relevant factors to consider in connection with "surplus" and "shortages." Definitions are contained in Article IV.

In the actual operations under the Operating Criteria the annual reports have avoided the determination of the numerical value for Section 602(a) storage by stating that "the accumulation of 602(a) storage is not the criteria governing the release of water during the current year."

In 1975 the first formal 5-year review of the criteria was made, but after receipt of comments, the Secretary announced their continuation without change. Subsequent reviews of the Criteria in 1980, 1985, 1990 and 1995 have also resulted in no changes being made to the Operating Criteria.