A flowing river is a symbol for progress and change, and the Colorado River is specifically emblematic of the evolution of Western agriculture. Water from the river shaped and supported crop production from the time the first settlers started farming and continues to do so today.

At the Western Alfalfa & Forage Symposium held in Sparks, Nev., last month, Jeff Silvertooth with the University of Arizona outlined the past and present dynamics of water usage in the Colorado River Basin. The seven U.S. states that comprise the basin — Arizona, California, Colorado, Nevada, New Mexico, Utah, and Wyoming — are seeking changes to their water allocations, but variable drought conditions, expanding urban populations, and legal implications make it difficult for these changes to occur.

Silvertooth began by giving context to the Colorado River. At more than 1,400 miles in length, the river has a budget of 16.5 million acre-feet of water per year, which is divided among the seven U.S. states and two states in Mexico. It provides water for about 40 million people, and its watershed encompasses roughly 6 million acres of cropland. More than 70% of the river’s water is used for agriculture, but so is 70% of water worldwide.

Jeff Silvertooth

“Globally speaking, 70% of water on this planet is directed to agriculture, primarily in the arid and semi-arid regions around the world,” Silvertooth stated. Therefore, this statistic that is commonly used against crop producers is a weak argument for unfair water allocations. What better defines water usage in the West is the history and legislature of the Colorado River.

The law of the river

Silvertooth called this legislature the “law of the river.” Rather than an individual law, though, it is a collection of laws, contracts, agreements, and treaties that have accumulated over the past century. Legal disputes about water allocations began in 1922 with the signing of the Colorado River Compact, which was the first document to define how much water each state in the Colorado River Basin would receive.

“Even after (the states) signed the compact and made an agreement, they were immediately at each other’s throats, looking for more water, thinking that one was getting more water than another,” Silvertooth said. He noted his state of Arizona was particularly reluctant to accept the water allocations, waiting 22 years to ratify the compact in 1944.

The Boulder Canyon Project Act was the next major piece of legislation to pass through Congress in 1928. This spurred the creation of the then-named Boulder Dam, now Hoover Dam, and the All-American Canal, which directs water from the Colorado River to California’s Imperial Valley. Instead of settling arguments about water allocations, though, this act accentuated them.

“In 1952, Arizona followed up with a major lawsuit against California, saying they were getting too much water,” Silvertooth said. Even though the Supreme Court assigned 7.5 million acre-feet of water to both the Upper and Lower Colorado River Basins in 1963 in attempt to curb conflicts, the Bureau of Reclamation still allotted California the bulk of the volume because of the state’s present perfected rights.

First come, first serve

“Present perfected rights, or PPR, is a fundamental concept of how we manage water on a first in time, first in right basis,” Silvertooth explained. “To have your water rights perfected through the legislature of your respective state, it had to be done before 1928 because that is when the Boulder Canyon Project Act was passed. That is very important; that is key to where we are today.”

In other words, water rights were a matter of priority, not equality. But despite decades of trying to appease PPRs and adhere to allocations, the water levels in Lake Powell and Lake Mead — formed by the Glen Canyon Dam and the Hoover Dam, respectively — started to show signs of overconsumption and under supply in 2002.

“In 2002, it was recognized the lake levels were coming down, water flow was definitely decreasing, and a drought was already beginning,” Silvertooth recalled. As a result, the 2007 Interim Guidelines were created as a framework for managing a critical water shortage on the Colorado River. But as drought conditions worsened, the agreement became less effective.

Drought Contingency Plans

In 2019, each state in the Lower Colorado River Basin completed a Drought Contingency Plan (DCP) based on water levels in Lake Mead at the Hoover Dam, measured in tiers as elevation in feet above sea level. Silvertooth said in 2020, lake levels fell to 1,090 feet above sea level at the dam, and then dropped 1,075 feet at the end of 2021. These reductions initiated the cutbacks to water allocations that were outlined in each state’s DCP, with successive tier levels requiring deeper cuts to Arizona, Nevada, and Mexico.

The DCPs were not successful in sustaining lake levels, and in June 2022, the Bureau of Reclamation gave states 60 days to develop a plan that would save between 2 million and 4 million acre-feet of water from the river’s 16.5 million acre-feet budget.

“Of the seven U.S. states and two states in Mexico, there weren’t many volunteers who were stepping up to say they were ready to take a bigger cut than what was already defined in the DCP,” Silvertooth said. He noted that in 2023, Arizona, Nevada, and Mexico surrendered more than 700,000 acre-feet combined, but California did not give up any due to its high-priority water allocations.

“What is driving a big stick in our backs right now is that in 2026, all the DCPs expire, and we will have to negotiate the whole deal,” Silvertooth added. As water supplies tighten and populations rise, he fears the biggest challenge moving forward will be ensuring enough water is available for agriculture.

The sensationalized statistic of 70% water usage for agriculture will likely continue to pit urban citizens against producers, but Silvertooth reminded the audience of the advancements in crop genetics, equipment, irrigation technology, and management that have greatly enhanced water efficiency on Western farms. He commended producers for respecting their water allocations and accepting the responsibility to use them resourcefully.

“Water is the lifeblood of this desert, and without water, agriculture cannot exist. Rainfed agriculture is not going to support the population,” he resolved. “What we are trying to do is build a coexistence between urban and agricultural sectors of our states. As we do that, we not only have to think about ourselves, but how what we do will impact our children and grandchildren — the generations that are yet to come.”