Shaun McKinnon has a must-read story for those interested in western water in today’s Arizona Republic about the discussion in his state about the future of agricultural and municipal water use:

As Phoenix grew, the land available for farms shrank and water use shifted. As recently as 1965, 80 percent of the water delivered by Salt River Project was used by agriculture. Today, that number is just 15 percent.

Converting retired agricultural water supplies to urban uses helped Phoenix grow without the water issues facing Las Vegas, where there were never many irrigated fields. The canals that move water – particularly the Central Arizona Project canal, which taps the Colorado River – could help fuel more population growth if farmers were to give up some of their water.

But if farmers go out of business, the crops they sold in Arizona would be imported from another state or country. As their water is claimed by new development, cities would lose the backup water source, which would become more important if droughts worsen as climate scientists predict.

I recommend reading the whole thing, which lays out the dilemma(s): To what extent do we need to keep growing food with that water? To what extent is ag the most economically beneficial use? What are the policy mechanisms that might be used to manage what ag-urban transfers we make?

And while Shaun’s story focuses on Arizona, the exact same situation holds across the border in California, where the Imperial Irrigation District is the largest single Colorado River water user. At yesterday’s meeting of the Middle Rio Grande Water Assembly here in Albuquerque, the ag-municipal question was on everyone’s mind.