SHORTAGE ON THE COLORADO

THE LAW OF THE RIVER IN A CHANGING CLIMATE

by Sara Porterfield, Water Policy Associate – Trout Unlimited

INTRODUCTION

If you look at the U.S. Drought Monitor map you can see a bullseye of extreme drought over the Colorado River Basin, the headwaters of which drain from Colorado’s

Western Slope. Drought, high wildfire risk, and the potential for a shortage declaration in the Lower Colorado River Basin have all been making headlines lately. What is a shortage declaration, exactly, and what does the likelihood of a shortage declaration mean for Colorado and the Colorado River Basin?

THE COLORADO RIVER COMPACT & HISTORICAL CONTEXT

The seven states of the Colorado River Basin—Arizona, California, Colorado, Nevada, New Mexico, Utah, and Wyoming—negotiated the Colorado River Compact in November of 1922. The states of the Upper Colorado River Basin – Colorado, New Mexico, Utah and Wyoming - were concerned that fast-growing California would lay claim to the majority of the river’s water before the smaller population of the Upper Basin states would develop a demand for the water. Negotiated during a particularly wet period of time on the Colorado River, and ignoring evidence that the average annual flow was less than negotiators agreed upon, the Colorado River Compact requires the Upper Basin to deliver 7.5 million acre-feet of water annually on a ten-year running average to the Lower Basin, as well as half of the 1.5 million acre-foot obligation to Mexico. The understanding at the time was that the Upper Basin states would have available an approximately equal share of 7.5 million acre-feet annually. History has proven that this understanding was overly optimistic.

The years since the signing of the Colo-

rado Compact have been significantly drier than the years preceding the compact. Since the year 2000, the Colorado River Basin has been in severe drought, resulting in a precipitous decline in the amount of water stored in the Colorado’s two big reservoirs, Lake Mead and Lake Powell. Climate scientists are urging water managers and residents in the West to start thinking about the drier conditions as aridification—a long-term condition—rather than a shorter-lived drought.

INTERIM GUIDELINES & THE DROUGHT CONTINGENCY PLAN

The Compact is the foundational document governing Colorado River Basin water use and development, but in the nearly century since its negotiation, a body of laws, agreements, and Supreme Court decisions has developed, known as the Law of the River and providing further governance over the Colorado River. Some of the most recent additions to the Law of the River are the 2007 Interim Guidelines and the 2019 Drought Contingency Plan (DCP).

The frighteningly dry hydrology prompted the seven Basin states to develop what are known as the Interim Guidelines: a set of criteria to determine how Lake Mead and Lake Powell would be managed based on the volume of water stored in the two reservoirs. Water users in the Basin quickly realized, as the dry years continued, that the Interim Guidelines provided a foundation for ad-

dressing water scarcity concerns but that the guidelines needed to go further to bolster reservoir storage and water supply.

In 2019, the states signed a series of agreements collectively known as the Drought Contingency Plan (DCP). The Lower Basin DCP agreement increased the amount of water states are required to conserve from the Interim Guidelines’ baseline and bumped up the elevation of Lake Mead at which those delivery reductions would begin. The Upper Basin DCP agreements created a storage “account” of 500,000 acre-feet in Lake Powell to which states could contribute water for the sole purpose of maintaining the storage volume in Lake Powell at a sufficient level such that the Upper Basin could satisfy its water delivery obligations to the Lower Basin under the Compact.

THE APRIL 24-MONTH PROJECTION & SHORTAGE PROJECTION

The Bureau of Reclamation produces 24-month forecasts throughout the year, and Colorado River reservoir operations are based on the August forecast. The August 24-month projections determine Lower Basin reservoir operations based on the elevation of Lake Mead on January 1st as projected by the August forecast.

The 24-month study released in April of this year is newsworthy because it forecasts that, for the first time, Lake Mead’s elevation will be below 1075 feet in elevation on January 1st, the trigger point for a Tier 1 shortage declaration per the Interim Guidelines and DCP. The declaration requires Arizona and Nevada to take cuts in their Colorado River water supply, while California does not take a shortage until Lake Mead hits elevation 1045’. For Arizona and Nevada, these cuts are “planned pain,” as an Arizona water manager recently described it; the Lower Basin has been preparing for shortage declarations for years and has “mitigation water” available to fill the gaps created by the decrease in Colorado River supply.

For the Upper Basin, a shortage declaration in the Lower Basin doesn’t have any practical effect and doesn’t cut water use in Colorado or any of the other Upper Basin states. It is, however, a sign of the difficult hydrological conditions the Colorado River Basin and the West more broadly are facing. If dry conditions continue into future years, and the Upper Basin states fail to deliver 7.5 million acre-feet of water per year to the lower basin on a ten-year running average, the lower basin could place a compact “call.” A compact call would result in forced curtailment of water uses, according to priority date, in the Upper Basin. Farms, ranches, cities, and industries that depend on Colorado River water could be forced to go without. The disruption to Colorado’s economy and quality of life is difficult to imagine.

In an effort to stave off a compact call, the four Upper Basin states are considering the development of a Colorado River “demand management” program. Demand management would be a program under which water users are compensated to temporarily and voluntarily cease water use. TU supports this concept because we see it as a step towards balancing water supply and water demand on the Colorado River system, and such a program also has potential to produce stream flow benefits. We also support the notion of allowing water users increased flexibility in how they use their water, including the option of using less or even no water on a temporary basis.

Over the past several years, TU has participated in policy discussions around the feasibility of demand management. We have also worked with water users to develop on-the-ground demand management demonstration projects. In these projects, we have raised funds to compensate farmers and ranchers for temporarily foregoing water use, and we use the projects to conduct research on the impacts of demand management on crops and stream flows.

Through both our policy work and our on-the-ground projects, we believe that a program that compensates water users for foregoing water diversions on a temporary and voluntary basis has potential to help address the supply and demand imbalance and to improve flow conditions in the Colorado River basin. These collaborative efforts offer real potential for both basin-level and localized benefits as we face the challenges of a warmer, drier future.

To Learn More.

To learn more about this story and Colorado Trout Unlimited, visit coloradotu.org.

Have you considered a planned gift to Colorado TU?

A legacy gift to Colorado TU helps to secure our future and enables us to continue our work preserving and restoring Colorado’s watersheds for years to come. It allows us to improve wild trout habitat in your homewaters, to restore native cutthroats, and to offer our River Conservation and Fly Fishing Youth Camp to more of Colorado’s youth. By making Colorado TU a beneficiary of your estate, you are making one of the most sincere and lasting commitments to our conservation mission and supporting cold, clean, fishable waters in Colorado.