We have know this for more than 140 years [0]. Since my previous post I can now also strongly recommend that everyone (yes, everyone) living in the western United States read at least the introduction[1] to Beyond the Hundredth Meridian[2]. The introduction is more relevant now than it was when it was written 67 years ago, itself 75 years after the publication of Lands of the Arid Region.
I fully expect the western water related engineering projects of the 20th century to fail in this century because you can't store what never falls from the sky, and you cannot refill a depleted aquifer. Powell presented us with the reality of the ecological and political situation, maybe some day we will finally get around to implementing the solution [3,4].
Edit: for a special treat RE the thread on water usage in Utah as see the discussion of page 84 (96) of [0] where Powell writes the following: "In general, there is a great wastage, due to badly constructed canals, from which the water either percolates away or breaks away from time to time; due, also, to too rapid flow, and also to an excessive use of the water, as there is a tendency among the farmers to irrigate too frequently and too copiously, errors corrected only by long experience." Apparently long experience is more than 140 years.
Previously:
https://news.ycombinator.com/item?id=18098899
https://news.ycombinator.com/item?id=26964166
0. https://pubs.usgs.gov/unnumbered/70039240/report.pdf LANDS OF THE ARID REGION John Wesley Powell 1878
1. https://erenow.net/modern/beyond-the-hundredth-meridian/1.ph... Bernard DeVoto 1954
2. Beyond the Hundredth Meridian: John Wesley Powell and the Second Opening of the West ISBN:9780140159943 Wallace Stegner 1954
3. https://www.smithsonianmag.com/smithsonian-institution/visio...
4. https://commons.wikimedia.org/wiki/File:Map_of_Water_Sheds_o...