Colorado River Guidelines for Shortage Management and Coordinated Reservoir Operation

The Upper Colorado River Commission (UCRC) was created in 1948 as part of the passage of the Upper Colorado River Basin Compact. The UCRC is governed by one Commissioner appointed by the governors of the four upper basin states of Colorado, New Mexico, Utah and Wyoming and one Commissioner appointed by the President representing the United States. The UCRC is an interstate water administrative agency that is charged to act as the water master for the upper basin states. The member states and the UCRC were instrumental in the negotiation of the 2007 Interim Guidelines for Shortage Management and Coordinated Reservoir Operation subsequently adopted by the Secretary of the Interior.

The Colorado River is governed by various compacts, court decrees and agreements that collectively are known as the Law of the River. These agreements frame how water may be used in the upper and lower basin states. Working with the Department of the Interior, the seven basin states agreed to, and Interior adopted, interim Guidelines for Shortage Management and Coordinated Reservoir Operation in 2007. The Guidelines are effective to 2026 and while complicated, basically guide how Lakes Powell and Mead will be governed and when the lower basin states will take shortages. The guidelines are based on pre-established elevation triggers which govern the release of water from Lake Powell to Lake Mead. Of course, hydrology within the basin affects the elevations in Powell and Mead. This year because of above average snowpack and runoff , the U.S. Bureau of Reclamation (BOR) will be releasing additional water from Glen Canyon Dam until equalization requirements are fulfilled.

In a year like this, with considerable runoff (currently projected to be the eighth wettest year since the operation of Glen Canyon Dam began in 1963), Lake Powell will be rising considerably. Enough so that it triggered equalization. When operating under Equalization, if Lake Mead has a lower projected volume of storage than Lake Powell for the end of the water year (September 30th) and Lake Powell is above the equalization elevation, then Lake Powell will be managed to try to equalize the storage volumes of the two reservoirs by releasing larger volumes during the water year than normal. ‘Normal’ water year release volumes under the Interim Guidelines range from 7.0 to 9.5 maf depending actual and projected storage conditions in Lake Powell and Lake Mead. This year (water year 2011), under Equalization, Lake Mead will likely receive approximately 14.3 million acre-feet from Lake Powell, but the exact amount will depend upon the actual inflow volume to Lake Powell during the remainder of water year 2011. With this projected inflow volume, the Lake Mead storage level is projected to rise considerably, but won’t rise to storage volume of Lake Powell because Lake Mead storage has been significantly lower than Lake Powell storage for several years. As Dave Trueman, BOR Division Chief of the Salt Lake City Regional office stated, “It potentially takes decades to draw the two reservoirs down and may also take decades to refill.”