The issue is "water rights". In Western states, somebody owns that water already. The rain might fall on your house, but it normally flows into some creek/stream/river where the legal and moral rights to that water belong to someone else. Capturing that water is legally considered theft. In Colorado, for example, every bit of river water was allocated to someone before Colorado became a state.

One book that covers the history of water projects in the US is Cadillac Desert [0]. We have this cultural myth that all we need is a little more water to make the desert bloom. And as a country, we've wasted trillions of dollars diverting rivers for agricultural use. Agricultural users of water pay almost nothing for their water while using enormous amounts of taxpayer funding to do so. Utah and Arizona have recently had droughts where water consumption by private citizens was limited.

There are several crops that use enormous amounts of water, the one receiving attention is alfalfa. 82% of Utah's water is consumed by agriculture. The UT governor owns a farm that grows alfalfa for export. Instead of cutting back on his own farm's water consumption, he's been on radio & TV telling Utahns to pray for rain. Arizona has had some recent news stories about Saudi companies growing alfalfa in AZ and exporting the hay to Saudi Arabia. Alfalfa consumes so much water that growing it in Saudi Arabia is illegal. Amusingly, `alfalfa` is an Arabic word. The issue with AZ & UT is that there is plenty of taxpayer subsidized water to grow alfalfa for export while simultaneously rationing residential water consumption.

0 - https://www.amazon.com/Cadillac-Desert-American-Disappearing...

In Utah, 80% of water use goes to agriculture. And farmers pay about 1% of what residential customers pay for water.

As a nation, we have this fantasy of turning the desert green. The book Cadillac Desert lists our national obsession with massive water projects that never pay for themselves and that always require massive tax subsidies.

https://www.amazon.com/Cadillac-Desert-American-Disappearing...

Quite an interesting (and somewhat infuriating) history. Cadillac Desert [1] is also an excellent chronicle of water projects in the west.

[1] https://www.amazon.com/Cadillac-Desert-American-Disappearing...

People born after the 1970s may not be aware of the Teton Dam collapse, but it was another case of total disregard for many, many expert warnings of disaster in the rush to build something big and impressive. Here's kind of a cheesy documentary clip describing the incident [1], but the book Cadillac Desert [2] goes into some detail if you're curious.

[1] https://www.youtube.com/watch?v=cdOGPBnfoKE

[2] http://www.amazon.com/Cadillac-Desert-American-Disappearing-...

The definitive history of water development in California is this book: http://www.amazon.com/Cadillac-Desert-American-Disappearing-...

It's almost thirty years old now, but the history is just as relevant, and the warnings issued similarly prescient.

Anyone interested in the mind-bending history of moistening the West in general and California in particular just enough to be advertised as paradise may want to do themselves a favor and read "Cadillac Desert": http://www.amazon.com/Cadillac-Desert-American-Disappearing-.... (Not an affiliate link.)