I. Introduction
The Colorado River Basin (CRB) covers a drainage area of 246,000 square miles across California, Colorado, Nevada, New Mexico, Utah, Wyoming and Arizona. Studies have estimated that the basin provides $1.4 trillion of economic revenue per year, 16 million jobs across 7 states, water to 40 million people, and irrigation to approximately 5.5 million acres of agricultural land. For states such as New Mexico and Nevada, it represents more than two thirds of their annual GDP (65% and 87%, respectively). [1]
On August 21, 2021, the U.S. federal government declared its first-ever water cuts in the basin, due to the ongoing megadrought. The basin is estimated to be filled to 35% of its full capacity and has suffered a 20% decrease in inflow in the last century. [2] Rising temperatures caused in part by climate change have dried up the water supply of the basin, with certain areas experiencing more than double the global average temperature. Hotter temperatures have had three notable impacts on the drying of the basin: accelerated evaporation and snowpack melting, drying up soil before runoff reaches reservoirs, and increased wildfires which cause erosion of sediment into the basin.
The CRB finds itself at a critical juncture; as the population and demand in the area continues to grow, the water supply is only diminishing. Ideally, the basin should provide for municipal, agricultural, tribal, recreational and wildlife needs. Thus, appropriate water management policies will be foundational to the efficacy of water distribution in these critical times.
II. Brief History
Representatives from the seven Colorado River states negotiated and signed the Colorado River Compact on November 9th, 1922, and a century later, this compact still defines much of the management strategies of the CRB. The compact divided the basin into Upper and Lower sections and provided a framework for the distribution of water [3]. At the time of the signing, it was estimated that the annual flow of the basin was 16.4 million acre-feet (maf/y). Accordingly, the right to 7.5 maf/y of water was split between each portion of the basin. A more accurate estimate of total flow adjusted this to 13.5 maf/y with fluctuations between 4.4 maf/y to 22 maf/y [3]. State-specific allocations were defined in 1928 as part of the Boulder Canyon Act for the Lower Basin, and in 1948 for the Upper Basin in the Upper Colorado River Basin Compact [4]. Figure 2 displays water distribution on a state basis in million-acre feet/year.
The system of water allocation, which is still in place today, dates back to 1876 when the Colorado Constitution put into place the Doctrine of Prior Appropriation. The core of the doctrine enforces that water rights can only be obtained for beneficial use. These rights can be bought, sold, inherited, and relocated. The doctrine gives owners of the land near the water, equal rights of use. This system regulates the uses of surface and tributary groundwater on a basis of priority. The highest priority are senior water rights holders. This group are those that have had the rights for the longest time and are typically best positioned in times of drought. Contrastingly, junior water rights holders are those that have obtained their water rights more recently and tend to be those whose supply is curtailed first in times of drought. This system is often described as “first-in-time, first-in-right” [5]. However, a key criticism of this doctrine is that it fails to encompass beneficial uses of water, which are particularly important when water is scarce.
Figure 3 summarizes the key historic moments of the Colorado River Basin from the Colorado Constitution in 1876 to the most recent 2023 negotiations. Some of the most notable events are the 1922 signing of the Colorado River Compact which created the foundation of division and apportionment of the water basin. Additionally, the construction of dams in the early to mid 20th century such as the Hoover Dam, Parker Dam, Glen Canyon, Flaming Gorge, Navajo and Curecanti have played an important role in determining water flow today. The formation of the Central Arizona Project in 1968, provided access to water for both agricultural lands and metropolitan areas such as the Maricopa, Pinal and Pima counties [6]. More recently, the critically low water levels of Lake Powell and the Glen Canyon Dam have raised concerns about their ability to generate hydropower. In early 2023, the seven states that utilize the CRB met in hopes of reaching an agreement on how to deal with the current shortages but the proposal failed.
III. Key Players
Figure 4, highlights prominent key players in the Colorado River Basin who are frequently involved in negotiations and policy making.
IV. Current Situation
In January 2023, the states within the CRB failed to come to an agreement on an updated water consumption plan aimed to curbing the impacts of the megadrought. The proposed plan would require California to cut their water from 4.4 maf/y to 1 maf/y. The agreement, aimed at preventing Lake Powell and Mead from falling below the critical level for hydropower, proposed major water cuts for Southwestern states of California and Arizona and incorporated losses from evaporation into the cutbacks [7]. Although six states agreed on a plan to move forward, California rejected the major water cuts due to concerns related to agriculture and legal water rights status. The proposed cuts would primarily impact regions such as Imperial County which have senior rights to 3.1 maf/y and an agricultural revenue of $2.3 billion annually [8]. California proposed an alternative plan, which called for a 400,000 acre-foot reduction (for CA specifically), with additional reductions contingent upon the water level of Lake Mead in the future. While both plans are similar, the California plan is founded on waiting until the water level passes a critical threshold, while the plan from the other states is more preventative in nature [7].
In more recent news, the Biden Administration just proposed a plan to evenly cut water allocations to California, Arizona and Nevada by approximately one-quarter. An intervention from the federal government on such a scale would be unprecedented in the history of the region. The options considered include: taking no action, making reductions based on senior water rights, or making equal reductions across the three states. Opting for the first option would likely result to a dead pool in Lake Mead and Powell, a term used to describe when the water levels fall too low to continue flowing downstream [12]. The second option would favor California, as it is one of the states which holds the most seniority in the basin particularly in the Coachella and Imperial Valleys of Southern CA [9]. Consequently, this decision would more severely impact Arizona and Nevada, which are important swing states for the President and have an important tribal presence. The final decision is anticipated to be made in the summer of 2023 [10].
In many parts of California and Colorado, this winter has been particularly heavy in rain and snow, making people hopeful that the river could be replenished. Scholars estimate that it would require 3 years of average snow with no water consumption to fully restore the Colorado River Basin reservoirs and 7 years under current consumption activity [11]. Unfortunately, the basin’s soil is extremely dry, which means that any excess water that comes from the snowpack is likely to be absorbed by the ground before it has a chance to reach rivers and streams. It is estimated that by the end of 2023 Lake Powell will be at 3,555 feet of elevation (roughly 32% capacity). When Lake Powell reaches 3,490 feet, the Glen Canyon Dam will be unable to produce hydroelectric power. At 3,370 feet, a dead pool will be reached.
V. Paths to a Sustainable Future
As water supply in the CRB continues to diminish, it has become increasingly crucial to find ways to minimize water loss of the system. One of the major contributor is through evaporation, which accounts for approximately 1.5 maf/y of loss. This loss is more than Utah’s allocation from the Colorado River. In order to minimize evaporation loss, an ideal reservoir would be very deep and have small surface area. However, this is not the case for reservoirs like Lake Powell which loses approximately 0.86 maf/y (more than 6% of CRB annual flow) [13]. This raises the important question of how to best allocate the CRB water considering that some states experience more evaporation loss than others. According to research from CU Boulder, some possible solutions include covering the surface water with reflective materials, films of organic compounds, and lightweight shades. Additionally, relocating the reservoir water underground storage areas or aquifers could also serve to reduce evaporation [14].
An alternative approach is cloud seeding. In early March of 2023, the Federal Government invested $2.4 million in cloud seeding for the CRB. Cloud seeding is a technique used to artificially induce more precipitation by injecting ice nuclei, silver iodide or other small crystals into subfreezing clouds. This promotes condensation of water around the nuclei and the formation of rain drops which are estimated to increase precipitation by 5-15% [15]. The grant will be used to fund new cloud seeding generators which can be operated remotely as well as aircrafts for silver iodide injections. While this is a significant investment, cloud seeding has been practiced for decades in the CRB. Indeed, it is estimated that Colorado, Utah, and Wyoming each spend over $1 million annually on cloud seeding and Utah has planned to increase its spendings to $14 million next year [16]. While the negative impacts of cloud seeding are still unclear, some scholars believe that they could cause silver toxicity because of the use of potentially harmful chemicals. Additionally, the wind can sometimes blow the seeded clouds to a different location [17]. Ultimately, cloud seeding does not solve the underlying obstacles of climate change or aridification in the region, but it may help alleviate some of the impact from the drought until a more sustainable alternative can be found.
Work Cited
[1] “Economic Importance of the Colorado River.” The Nature Conservancy. The Nature Conservancy. Accessed December 1, 2021. https://www.nature.org/en-us/about-us/where-we-work/priority-landscapes/colorado-river/economic-importance-of-the-colorado-river/.
[2] Kann, Drew. “Climate Change Is Drying up the Colorado River, Putting Millions at Risk of ‘Severe Water Shortages’.” CNN. Cable News Network, February 22, 2020. https://www.cnn.com/2020/02/21/weather/colorado-river-flow-dwindling-warming-temperatures-climate-change/index.html.
[3] Megdal, Sharon B. “Sharing Colorado River Water: History, Public Policy and the Colorado River Compact.” The University of Arizona: Water Resources Research Center , 1 Aug. 1997, https://wrrc.arizona.edu/publication/sharing-colorado-river-water-history-public-policy-and-colorado-river-compact.
[4] Water Education Foundation. (n.d.). Colorado River Compact. Water Education Foundation. Retrieved April 17, 2023, from https://www.watereducation.org/aquapedia-background/colorado-river-compact#:~:text=The%20Lower%20Basin%20states%20were,River%20Basin%20Compact%20of%201948.
[5] Hockaday, S, and K.J Ormerod. “Western Water Law: Understanding the Doctrine of Prior Appropriation: Extension.” University of Nevada, Reno , University of Nevada, Reno, 2020, https://extension.unr.edu/publication.aspx?PubID=3750#:~:text=Senior%20water%20rights%20are%20often,farming%2C%20ranching%20and%20agricultural%20uses.&text=A%20claim%20to%20water%20that%20is%20more%20recent%20than%20senior,municipal%2C%20environmental%20or%20recreational%20uses.
[6] State of the Rockies Project 2011-12 Research Team. “The Colorado River Basin: An Overview.” Colorado College, 2012.
[7] Partlow, Joshua. “As the Colorado River Dries up, States Can’t Agree on Saving Water.” The Washington Post, The Washington Post, 4 Apr. 2023, https://www.washingtonpost.com/climate-environment/2023/01/31/colorado-river-states-water-cuts-agreement/.
[8] Bland, Alastair. “California, Other States Reach Impasse over Colorado River.” CalMatters, 1 Feb. 2023, https://calmatters.org/environment/2023/01/california-colorado-river-water-2/.
[9] Hager, Alex. “Six States Agree on a Proposal for Colorado River Cutbacks, California Has a Counter.” KUNC, NPR, 1 Feb. 2023, https://www.kunc.org/environment/2023-01-31/six-states-agree-on-a-proposal-for-colorado-river-cutbacks-california-has-a-counter.
[10] Flavelle, Christopher. “Biden Administration Proposes Evenly Cutting Water Allotments from Colorado River.” The New York Times, The New York Times, 11 Apr. 2023, https://www.nytimes.com/2023/04/11/climate/colorado-river-water-cuts-drought.html?campaign_id=190&%3Bemc=edit_ufn_20230411&%3Binstance_id=89950&%3Bnl=from-the-times&%3Bregi_id=108807334&%3Bsegment_id=130155&%3Bte=1&%3Buser_id=ea42cfd845993c7028deab54b22c44cd.
[11] Mullane, Shannon. “Colorado’s Healthy Snowpack Promises to Offer Some Relief for Strained Water Supplies.” The Colorado Sun, The Colorado Sun, 14 Mar. 2023, https://coloradosun.com/2023/03/14/colorado-snowpack-water-supply-relief/.
[12]Tavernise, Sabrina, host. “7 States, 1 River and an Agonizing Choice.” The Daily, The New York Times, 31 Jan. 2023. https://www.nytimes.com/2023/01/31/podcasts/the-daily/colorado-river-water-cuts.html?showTranscript=1
[13] “Lake Powell Reservoir: A Failed Solution.” Glen Canyon Institute, Glen Canyon Institute , https://www.glencanyon.org/lake-powell-reservoir-a-failed-solution/.
[14] Blanken, Peter, et al. “Reservoir Evaporation a Big Challenge for Water Managers in West.” CU Boulder Today, 28 Dec. 2015, https://www.colorado.edu/today/2015/12/28/reservoir-evaporation-big-challenge-water-managers-west.
[15] McDonough, Frank. “What Is Cloud Seeding?” DRI, Desert Research Institute, 19 Sept. 2022, https://www.dri.edu/cloud-seeding-program/what-is-cloud-seeding/.
[16] Peterson, Brittany. “Feds Spend $2.4 Million on Cloud Seeding for Colorado River.” AP NEWS, Associated Press, 17 Mar. 2023, https://apnews.com/article/climate-change-cloud-seeding-colorado-river-f02c216532f698230d575d97a4a8ac7b.
[17] Rinkesh. “Various Pros and Cons of Cloud Seeding.” Conserve Energy Future, Conserve Energy Future, 28 July 2022, https://www.conserve-energy-future.com/pros-cons-of-cloud-seeding.php.
Work Cited for Photos
[18] McBride , P. (n.d.). The Colorado River winds through the Grand Canyon. photograph, Arizona.
[19] Kuhn, Eric, and John Fleck . “A Century Ago in Colorado River Compact Negotiations: Storage, Yes. but in the Compact?” Jfleck at Inkstain , 15 Nov. 2022, https://www.inkstain.net/2022/11/a-century-ago-in-colorado-river-compact-negotiations-storage-yes-but-in-the-compact/.
[20] “A Project for the Ages.” Bechtel Corporate, https://www.bechtel.com/projects/hoover-dam/.
[21] Lane, Taylor. “Lake Mead through the Decades – Lake Mead in 1950 Photograph from United States National Park Service Photography Collection .” Journal, Las Vegas Review-Journal, 17 Aug. 2022, https://www.reviewjournal.com/local/local-las-vegas/lake-mead-through-the-decades-photos-2602149/.
[22] “1944: U.S. Mexico Water Treaty.” Know Your Water News , Central Arizona Project , 25 Oct. 2022, https://knowyourwaternews.com/1944-u-s-mexico-water-treaty/.
[23] “Glen Canyon Unit – Arial View of the Glen Canyon Dam and Lake Powell.” Bureau of Reclamation – Upper Colorado Region , Bureau of Reclemation , https://www.usbr.gov/uc/rm/crsp/gc/.
[24] “Reclamation and Arizona.” Reclamation, U.S Department of the Interior , https://www.usbr.gov/lc/phoenix/AZ100/1960/supreme_court_AZ_vs_CA.html.
[25] Ferris, Kathleen. “CAP: Tracking the Flow of Colorado River Water to Your City.” AMWUA, Arizona Municipal Water Users Association, 19 Oct. 2015, https://www.amwua.org/blog/cap-tracking-the-flow-of-colorado-river-water-to-your-city.