A reader writes to correct my mistakes regarding the Colorado River – no doubt committed through sleepiness:
A correction to this statement: “In the map above, the olive and turquoise areas serve to illuminate the Colorado River basin, and it’s that area to which the Colorado River provides water.” No, the shaded areas are the areas _drained_ by the Colorado River.
The areas to which it _provides_ water are different, especially a significant amount of the water is pumped _out_ of that basin for use elsewhere. Those include:
- Water captured in the Rocky Mountains in Colorado just west of the continental divide in places like Shadow Mountain Reservoir and Lake Granby which is pumped over the divide to the Denver metro area and used by cities there.
- Water pumped out (I believe from Lake Havasu) and sent westward all the way to the Los Angeles basin to serve cities there.
Some further notes (as someone who has mentioned this disaster in waiting for decades, and who has lived in Colorado, Utah and California):
The vast majority of the water in that river system comes from snow melt, not rain. And most of that comes from snow melt in Colorado and Wyoming. Those other tributaries on the map, like the Salt River in Arizona, are tiny by comparison, although the Salt is also mostly snow melt from Arizona mountains.
And this is not new. But people have been doing everything they can to ignore it or imagine any shortages or droughts were just short-term blips for more than 30 to 40 years. I last visited Lake Mead in about 1974; it was completely full. I have not checked, but it’s likely that at some point shortly after that, it became less than full and has never regained that stature. More than that, historical climate evidence has shown that the period from about 1900 to 1950 was unusually cool, wet and heavy with snowfall for the Colorado basin. That is to say, when the states and the feds were divvying up the Colorado River water for users and guesstimating the future, they were using a baseline that was actually far wetter/plentiful than average. So even a return to average would have been a water shortage. Meanwhile, actual usage went way up (see how Las Vegas and Phoenix have doubled in size in Lake Mead was last full) and climate has not only returned to “average” but gotten drier and warmer.
I plead exhaustion. Old Age. Something bad. I should have recognized that was a drainage basin!
