The report mentioned that water is used to grow pecans in Arizona. Just to get a rough idea of the monetary value of this use of water, I found somewhere a pecan tree needs about 2000 gallons/week, and produces up to 100 pounds a year. Shelled pecans can be had for $6/lb on ebay, so that's a sort of upper bound on the price. Let's suppose we need to water 30 weeks a year.

100 lb x $6/lb = $600 per tree for a year

2000 gal/week x 30 weeks = 60,000 gallons

$600 /60,000 gallons = $0.01/gallon

Then if we need about 7 gallons to produce a pound of copper, it's just 7 cents.

I'll be interested in comments from Metacomet and others.