The Upper Basin Compact in a nutshell

By Steve Harris | Guest Commentary, Rocky Mountain Voice

Editor’s note: This is Part 5 of 6 in the Water Time Reflections series by Steve Harris, marking 100 years since the Colorado River Compact. In this installment, Harris examines the 1948 Upper Colorado River Basin Compact—how it divided water among the Upper Basin states, shaped drought management, and continues to guide allocations today.

For those of us in the Upper Colorado River Basin, we have the Upper Colorado River Basin Compact (UBC) that was negotiated from 1946 to 1948, and was ratified in 1948 (a copy is available by clicking here). The UBC is as important to the Upper Basin States as the Colorado River Compact (CRC) is for the entire basin because it allocates water to each state including during shortages. Though not as succinct as the four-page Colorado River Compact, the UBC is only 12 pages, which is still pretty good for such an important document.

Map courtesy of U.S. Bureau of Reclamation

The purpose of UBC is best described in Article I:

“The major purposes of this Compact are to provide for the equitable division and apportionment of the use of the waters of the Colorado River System, the use of which was apportioned in perpetuity to the Upper Basin by the Colorado River Compact; to establish the obligations of each State of the Upper Division with respect to the deliveries of water required to be made at Lee Ferry by the Colorado River Compact; to promote interstate comity; to remove causes of present and future controversies; to secure the expeditious agricultural and industrial development of the Upper Basin, the storage of water and to protect life and property from floods.”

Commissioner Stone from Colorado states: “…we will attempt to make progress by agreeing upon the percentage method as against the method of a given acre-foot allocation. It seems to me we might find on some of these tributaries that some provision would have to be made to work out the equity between given states.” The percentage was the allocation that each State could deplete at Lees Ferry instead of a set volume amount. This was a critical agreement because it allowed for adjustments in the allocation based on the actual available water supply. There was also discussion of how to allocate water on tributaries some of which are included in the 14-page UBC.

Based on the “percentage method,” the UBC established the proportions that each of the Upper Basin States was entitled to: Colorado, 51.75 percent; New Mexico, 11.25 percent; Utah, 23 percent; Wyoming, 14 percent; and Arizona, 50,000 acre-feet. These percentages are proportions of man-made depletions and beneficial use is the basis, the measure and the limit. An important caveat of the proportions is:

“No State shall exceed its apportioned use in any water year when the effect of such excess use, as determined by the Commission, is to deprive another signatory State of its apportioned use during that water year;”

The UBC also established the Upper Colorado River Commission (Commission), which includes a member from each of the four Upper Division States (not Arizona) and a Federal member who is the chair. Becky Mitchell, the CWCB Director, is the Colorado representative. The Commission has established an office and a small staff in Salt Lake City. 

The Commission and staff are responsible to make findings on numerous water issues in the Upper Basin. Please review the UCRC and the office website for the full list.

Lake Powell Fall 2022, Photo Credit: John Norton

An important subsection is Article VIII, section (d)(10) which states the Commission has the power to “Make findings of fact in the event of the occurrence of extraordinary drought…” This section may directly apply if our current drought situation continues.

In reading the minutes of the negotiations for the UBC, it is clear the States’ representatives hoped there was an average of 7.5 million acre-feet (MAF) of depletion available to the Upper Basin as allowed in the Colorado River Compact. However, it is also clear that they established the percentage allocation system if there was not 7.5 MAF and still meet the lower basin non-depletion obligation of 75 MAF over a running ten-year average. 

Despite the best attempts by the Upper Division States, the water users have not come close to depleting 7.5 MAF of water. At the peak, when there is a full supply to all irrigators, the Upper Basin has only depleted approximately 4.5 MAF in a year. In 2021, the estimate is closer to 3.5 MAF because of drought water availability. 

These numbers don’t include the shared Colorado River Storage Project evaporation that is part of the Upper Division States apportionment.

In short, passage of the Compact provided the UCRC and its staff with the responsibility and the authority to allocate water to the Upper Division States whether in average or drought periods to meet the provisions of the Colorado River Compact. If the UCRC ever has to allocate shortages to meet the CRC, the process has been established to allocate those shortages between the States. This is unlike the Lower Basin, which does not have a compact but is administered by a water master who is the Secretary of Interior. 

Water allocation during drought in the Lower Basin is very different and less known than the Upper.

Miss the earlier pieces in this series?

Part 1: “Harris Water Time” and the Colorado River Compact’s century of lessons

Part 2: When did the Upper and Lower Basin of the Colorado River become a thing?

Part 3: How Did Compact Negotiators Split the Colorado River’s Flow in 1922?

Part 4: A small river with big influence: How the La Plata shaped western water law

Steve Harris is a distinguished water engineer based in Durango, Colorado, with a career spanning over 50 years that has significantly shaped water policy and resource management in the region. As president of Harris Water Engineering, Inc., he has led major projects such as the Dry Gulch Reservoir and played a guiding role in local and state water planning initiatives. Harris is widely respected for his advocacy of water conservation and xeriscaping, serving on the Animas Basin Roundtable and the Colorado Interbasin Compact Committee, and has worked closely with legislators to promote the sustainable use of water resources. His leadership and technical expertise have influenced landmark legislation, while his public outreach—such as the “Lawn Gone” campaign—underscores his commitment to balancing municipal and agricultural needs in Colorado’s water management.

Editor’s note: Opinions expressed in commentary pieces are those of the author and do not necessarily reflect the opinions of the management of the Rocky Mountain Voice, but even so we support the constitutional right of the author to express those opinions.