"the consequences could be dire:"
For the first time, the state agency that operates the multibillion-dollar Central Arizona Project warns that water shortages could hit Tucson and Phoenix as soon as five years from now.
Such shortages would occur if Lake Mead, now about 1,085 feet elevation, drops below 1,000 feet. Then the lake becomes what CAP calls a “dead pool” in which operations are sharply curtailed.
It's more complicated, so read the full report from the AZ Daily Star here.