Uploaded April 2023 | Updated September 2026, 5 hours ago
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?
grist.org/drought/colorado-river-cuts-arizona-california-lower-basin
Tribes in the Colorado River Basin are fighting for their water. States wish they wouldn’t.
grist.org/indigenous/colorado-river-tribal-water-rights-navajo-nation-arizona-nevada-drought-data
The Colorado River is drying up. Here’s how that affects Indigenous water rights
grist.org/equity/colorado-river-drought-indigenous-water-rights
Sources:
History of Parker Dam war between Arizona and California (among other sources)
azcapitoltimes.com/news/2015/06/29/tale-of-the-arizona-navy-old-story-revived-as-state-competes-with-california-for-water
Flow of Colorado River, 1930 - 2016 (Wheeler, 2019)
researchgate.net/publication/336058345_Water_Resource_Modeling_of_the_Colorado_River_Present_and_Future_Strategies#pf9
Flow of Colorado River, 2000-2018 (Stern, Sheikh, 2020)
crsreports.congress.gov/product/pdf/R/R45546/13
Estimated flow of Colorado River (Kuhn, Fleck, 2021)
bookshop.org/p/books/science-be-dammed-how-ignoring-inconvenient-science-drained-the-colorado-river/18865804?ean=9780816543236
1963 Court Case
books.google.com/books?id=BAFiIBETui8C&pg=RA14-PP29&lpg=RA14-PP29&dq=%22Motion+to+Reopen+the+Trial+for+the+Taking+of+Evidence+re+Depletion+of+the+Colorado+River+at+Lee+Ferry%22&source=bl&ots=RVZMKCCO3w&sig=ACfU3U1AYFSruhZWYD9TefD1_dZsm9kLsg&hl=en&sa=X&ved=2ahUKEwjPv9DvmNn9AhWyEFkFHUpwBPsQ6AF6BAgCEAM#v=onepage&q=%22morally%20certain%22&f=false
California Congress keeping water for own state:
g-a-l.info/capreport.pdf
Visual sources:
Getty Images
National Archives
Library of Congress
UCLA | Charles E. Young Research Library: creativecommons.org/licenses/by/4.0
Storyblocks
Music:
Audiosocket
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?
grist.org/drought/colorado-river-cuts-arizona-california-lower-basin
Tribes in the Colorado River Basin are fighting for their water. States wish they wouldn’t.
grist.org/indigenous/colorado-river-tribal-water-rights-navajo-nation-arizona-nevada-drought-data
The Colorado River is drying up. Here’s how that affects Indigenous water rights
grist.org/equity/colorado-river-drought-indigenous-water-rights
Sources:
History of Parker Dam war between Arizona and California (among other sources)
azcapitoltimes.com/news/2015/06/29/tale-of-the-arizona-navy-old-story-revived-as-state-competes-with-california-for-water
Flow of Colorado River, 1930 - 2016 (Wheeler, 2019)
researchgate.net/publication/336058345_Water_Resource_Modeling_of_the_Colorado_River_Present_and_Future_Strategies#pf9
Flow of Colorado River, 2000-2018 (Stern, Sheikh, 2020)
crsreports.congress.gov/product/pdf/R/R45546/13
Estimated flow of Colorado River (Kuhn, Fleck, 2021)
bookshop.org/p/books/science-be-dammed-how-ignoring-inconvenient-science-drained-the-colorado-river/18865804?ean=9780816543236
1963 Court Case
books.google.com/books?id=BAFiIBETui8C&pg=RA14-PP29&lpg=RA14-PP29&dq=%22Motion+to+Reopen+the+Trial+for+the+Taking+of+Evidence+re+Depletion+of+the+Colorado+River+at+Lee+Ferry%22&source=bl&ots=RVZMKCCO3w&sig=ACfU3U1AYFSruhZWYD9TefD1_dZsm9kLsg&hl=en&sa=X&ved=2ahUKEwjPv9DvmNn9AhWyEFkFHUpwBPsQ6AF6BAgCEAM#v=onepage&q=%22morally%20certain%22&f=false
California Congress keeping water for own state:
g-a-l.info/capreport.pdf
Visual sources:
Getty Images
National Archives
Library of Congress
UCLA | Charles E. Young Research Library: creativecommons.org/licenses/by/4.0
Storyblocks
Music:
Audiosocket
