Local Opinion: The Colorado River won't obey our rules

By Karl Flessa

Special to the Arizona Daily Star (Dec. 2, 2022)

Karl Flessa, an Arizona resident since 1977, is emeritus professor of geosciences at the University of Arizona. He has been studying the Colorado River since 1992.

The Colorado River Compact is 100 years old. A University of Arizona conference and the upcoming Colorado River Water Users Association will mark the anniversary. But there’s no reason to celebrate. Twenty-two years into a drought and with reservoirs at all-time lows, the federal government may soon intervene in the states’ management of the river.

The Compact has failed. Don’t blame the river.

We need a new system that manages with the river and provides all users with fair shares.

In 1922, the seven Colorado Basin states used an optimistic estimate of the river’s annual flow to allocate the waters. The states chose the biggest estimate because that made it easy to agree.

Everyone could pretend the river could satisfy all anticipated demands. That was the first mistake.

Also in 1922, the Upper Basin states of Wyoming, Colorado, Utah and New Mexico agreed to provide the Lower Basin states of Arizona, California and Nevada with 7.5 million acre-feet of water per year. In other words, the Lower Basin got its share first – regardless of how much water was available upstream. Later rules made things worse. In 1928, Arizona, California and Nevada agreed to fix their allocations at 2.8, 4.4 and 0.3 million acre-feet, respectively. In 1944, Mexico got an annual share of 1.5 million acre-feet by treaty.

Once everyone was entitled to a set amount, there was no incentive to cooperate. Agreeing on fixed allocations was the second mistake.

Moreover, none of the rules set aside any water for tribes or for ecosystems: Mistakes three and four.

By 1965, the Upper Basin states saw there would not be enough water to meet all the obligations. In 1976 and again in 2006, University of Arizona researchers showed the river’s actual flows weren’t enough to deliver all the water that had been promised.

The giant reservoirs built after 1922 came at a cost to the river’s supply. Evaporation and seepage pull out about 10% of the river’s annual volume.

The warming climate is also decreasing the Colorado’s flow. Scientists’ concerns about the effects of warming have been issued at least since 1993. A warmer climate triggers more evaporation, increases water use by vegetation, depletes soil moisture and reduces runoff to the river.

The warnings of climate scientists have been ignored for too long. A 2008 climate model predicted a 50:50 chance that Lakes Mead and Powell would go dry by 2021. Leading experts were jeered at the 2009 and 2010 meetings of the Colorado River Water Users Association.

Officials of the State of Arizona and the Central Arizona Project have been particularly slow to accept the reality of climate change.

Our knowledge has improved, and our values have changed. It’s time for a new century of enlightened river management. We need to manage with the river, rather than expecting the river to obey our faulty rules.

Short-term plans to avoid river bankruptcy have just kicked the can down the road. Wishful thinking about a few good years of snowpack in the Rockies did not solve all our problems. The proposed reductions in deliveries won’t correct the original mistakes.

We need to redefine what a fair proportion of the river’s volume is for each user. Managing with the river means that everyone shares what the river is able to deliver. Fair shares of a five-year running average of the Colorado’s flow give every user some certainty, an incentive to conserve, and ensures that every user shares the pain of any shortage.

Don’t blame the river. One hundred years ago, we invented a set of rules for a river that never behaved as we hoped it would. We can do better, but only if we get to work on it right now.