The very bad math drying up the Colorado River

California and Arizona are currently fighting each other over water. But this isn’t new – it’s actually been going on for over 100 years. At one point, the states literally went to war about it. The problem comes down to some really bad math from 1922.

To some extent, the crisis can be blamed on climate change. The West is in the middle of a once-in-a-millennium drought. As temperatures rise, the snow pack that feeds the river has gotten much thinner and the river’s main reservoirs have all but dried up. But that’s only part of the story.

The United States has also been overusing the Colorado for more than a century thanks to a byzantine set of flawed laws and lawsuits known as “the law of the river.” This legal tangle not only has been over-allocating the river, it also has been driving conflict in the region, especially between the two biggest users: California and Arizona, both trying to secure as much water as they can. And now, as a massive drought grips the region, the law of the river has reached a breaking point.

Video:
Jake Bittle
Daniel Penner

Data and map animations:
Jesse Nichols

Videographer:
Nikki Dodd

Deputy Editor:
Teresa Chin

Executive Editor:
Kat Bagley

Additional reading:
Feds’ Colorado River choice: California’s rights or Arizona’s future?
https://grist.org/drought/colorado-ri...

Tribes in the Colorado River Basin are fighting for their water. States wish they wouldn’t.
https://grist.org/indigenous/colorado...

The Colorado River is drying up. Here’s how that affects Indigenous water rights
https://grist.org/equity/colorado-riv...

Sources:
History of Parker Dam war between Arizona and California (among other sources)
https://azcapitoltimes.com/news/2015/...

Flow of Colorado River, 1930 - 2016 (Wheeler, 2019)
https://www.researchgate.net/publicat...

Flow of Colorado River, 2000-2018 (Stern, Sheikh, 2020)
https://crsreports.congress.gov/produ...

Estimated flow of Colorado River (Kuhn, Fleck, 2021)
https://bookshop.org/p/books/science-...

1963 Court Case
https://books.google.com/books?id=BAF...

California Congress keeping water for own state:
http://www.g-a-l.info/capreport.pdf

Visual sources:
Getty Images
National Archives
Library of Congress
UCLA | Charles E. Young Research Library: https://creativecommons.org/licenses/...
Storyblocks

Music:
Audiosocket