Analysis: Western states buy time with a 7-year Colorado River drought plan, but face a hotter, drier future

The Colorado River near Hite, Utah on Oct. 20, 2018. (Photo by John Herrick)
The Colorado River near Hite, Utah on Oct. 20, 2018. (Photo by John Herrick)

As Midwest states struggled with record spring flooding this year, the Southwest was wrestling with the opposite problem: not enough water. On May 20, 2019, federal officials and leaders from seven states signed the Colorado River Drought Contingency Plan, a sweeping new water management agreement for this arid region.

The plan is historic: It acknowledges that southwestern states need to make deep water use reductions – including a large share from agriculture, which uses over 70% of the supply – to prevent Colorado River reservoirs from declining to critically low levels.

But it also has serious shortcomings. It runs for less than a decade, through 2026. And its name – “Drought Contingency Plan” – suggests a response to a temporary problem.

As scholars who have spent years researching water issues in the West, we know the Colorado River’s problems are anything but temporary. Its waters have already been over-allocated, based on a century of false optimism about available supply. In other words, states have been allowed to take out more than nature puts back in.

Now the river is being further depleted by climate change-driven aridification. The next steps, post-2026, require a recognition that Arizona, Nevada and California will likely have to come to terms with permanent reductions in their Colorado River supply. For their part, Wyoming, Utah, Colorado and New Mexico must abandon dreams of taking ever-larger gulps from the Colorado River to support future growth.

The Colorado River historically flowed 1,450 miles from Colorado south into Mexico and then into the Gulf of California. For over 50 years it has failed to reach the ocean due to upstream diversions.USBR
The Colorado River historically flowed 1,450 miles from Colorado south into Mexico and then into the Gulf of California. For over 50 years it has failed to reach the ocean due to upstream diversions.(Image via U.S. Bureau of Reclamation)

Draining western reservoirs

The Drought Contingency Plan is an important step in that direction. By creating a new layer of rules that temporarily reduces water allocations, it significantly reduces the chance of emptying Lake Mead, the massive reservoir on the Arizona-Nevada border that supports residents of Arizona, Nevada, California and Mexico. Without the plan, the lake conceivably could have been sucked dry – a devastating prospect for 40 million people who live in the Colorado River Basin.

As a seven-year stopgap, the plan comes just in time. After 19 years of unprecedented low flows, the nation’s two largest reservoirs – Lakes Mead and Powell – collectively contain only 40% as much water as they held in 2000. And while the winter of 2018-2019 was a big snow year, it merely balances the previous year, when record-setting warm and dry weather in large parts of the basin lowered water levels in Lake Powell by over 40 feet.

Dry years like 2018 are the far more likely future. From 2000 through 2004, annual runoff totaled only 65% of the 20th-century average. And in 2012-2013, it was just 60% of the 20th century average. More episodes like these would seriously compromise the system’s ability to provide water to the seven Colorado River Basin states and Mexico.

Farmer Dan Thelander talks about how the Colorado River drought plan will affect farms in Pinal County, Ariz.

A hotter, drier future

Climate change is and will remain a significant issue. Since 2000, Colorado river flows have been 16% below the 20th-century average. Temperatures across the Colorado River Basin are now over 2 degrees Fahrenheit warmer than the 20th-century average, and are certain to continue rising.

Scientists have begun using the term “aridification” to describe the hotter, drier climate in the basin, rather than “drought,” which implies a temporary condition.

Studies show that higher 21st-century temperatures have been reducing runoff. Warmer temperatures increase evaporation from soils and water bodies, and increase sublimation from snowpacks – direct conversion of snow and ice into fog or steam, without melting first. And they increase plant water use, due to a longer growing season and more warmth on any given day.

In a 2017 study, one of us (Brad Udall) and Jonathan Overpeck found that higher temperatures due to climate change had reduced the flow of the Colorado River by approximately 6%. The study projected that additional warming could reduce flows by approximately 20% in 2050 and up to 35% by 2100 if precipitation levels did not change. A 2018 modeling study estimated the flow losses due to higher temperatures at about 10%.

Overuse in the Lower Basin states of Arizona, Nevada and California is the second major problem. This problem is officially known as the “Structural Deficit” – a 1.2 million acre-foot gap, representing 8% of the river’s flow, between allocations made in the early 20th century and the amount of water the river can provide.

Cities from Las Vegas on the north to Tucson and Phoenix on the south and west to San Diego and Los Angeles all have come to depend on that water. Meanwhile, agriculture – including important areas like Yuma and the Imperial Valley, where much of the nation’s valuable winter produce is grown – uses 70% of the river’s water.

The All American Canal diverts water from the Lower Colorado River to irrigate crops in California’s Imperial Valley and supply 9 cities. Although the Colorado River is depicted here as reaching the ocean, it no longer does so due to upstream diversions.USGS
The All American Canal diverts water from the Lower Colorado River to irrigate crops in California’s Imperial Valley and supply 9 cities. Although the Colorado River is depicted here as reaching the ocean, it no longer does so due to upstream diversions.USGS

Looking past 2026

With the contingency plan only running until 2026, Basin leaders are already discussing the framework of a new planning effort. In our view, the process should be open and inclusive, given the huge number of competing interests in the region, including municipalities, agriculture, tribes and the environment.

An effective long-term plan should solve the overuse problem in the Lower Basin, while preparing for extended and unprecedented low flows. It should revisit a number of long-standing assumptions about how the river is managed, including the Upper Basin’s so-called “delivery obligation” to the Lower Basin, which leaves the upper states – Wyoming, Utah, Colorado and New Mexico – bearing the burden of climate change, while the Lower Basin states remain free to overuse. And it will have to address the reality that there is not enough water for users in the Upper Basin to continue exporting ever more water to growing cities like St. George, Utah, and Colorado’s Front Range.

Solving the twin problems of climate change and overuse will not be easy. The good news is that water users in the basin have found ways to work together for everyone’s benefit, first in a set of water management guidelines negotiated in 2007, and then with the Drought Contingency Plan.

Now, after staving off worry that system reservoirs could drop to calamitous levels, water users and managers can focus on these pressing longer-term issues. It is time to step back, look at the big picture and design a water management system that works for all stakeholders in the basin for the next several decades.

This study has been updated with a more detailed map of the Colorado River Basin. This article is republished from The Conversation under a Creative Commons license. Read the original article.

Bradley Udall is a past Colorado Independent board member. 
The Conversation

 

BRAD UDALL serves as senior water and climate research scientist at the Colorado Water Institute to provide additional expertise in the field of water resources and climate change. He has extensive experience in water and climate policy issues, most recently as the director of the Getches-Wilkinson Center for Natural Resources, Energy and the Environment and the Western Water Assessment at the University of Colorado, Boulder. He has authored numerous peer-reviewed publications on water management and climate change which have been published by the federal government and major journals. He has researched water problems on all major Southwestern US rivers including the Rio Grande, Colorado, Sacramento-San Joaquin and Klamath, and has spent six months in Australia studying their recent water reforms. DOUG KENNEY has been with the Natural Resources Law Center since 1996. He researches and writes extensively on several water-related issues, including law and policy reform, river basin and watershed-level planning, the design of institutional arrangements, water resource economics, and alternative strategies for solving complex resource issues. Dr. Kenney has served as a consultant to a variety of local, state, multi-state, and federal agencies, including several Interior Department agencies, EPA, the US Forest Service, and special commissions (e.g., the Western Water Policy Review Advisory Commission); and national governments and non-governmental organizations in Asia and Africa. Additionally, he has made presentations in (at least) 19 states (and the District of Columbia), 7 nations, and 4 continents. JOHN FLECK is Professor of Practice in Water Policy and Governance and Director of the University of New Mexico Water Resources Program. Much of his career was spent in journalism, focused since the 1980s on the interface between science and political and policy processes, with special emphasis on climate and water in the southwestern United States. He was the Water Resource program’s writer-in-residence for three years before transitioning to academia full time in 2016. In the field of water resources, his primary interest is in nurturing the collaborative water governance needed to adapt to scarcity in the southwestern United States as populations grow while climate change reduces water supplies. That goal animates the Water Resources Program, where he and his colleagues work with graduate students who will become the region’s future water managers. In both the Water Resources Program and the Department of Economics, he also works on translational activities – helping make the technical work done in academia of maximum benefit to political and policy processes. Bios via The Conversation.com/profiles