Tighter, costlier water shifting focus to curbing demand

Shaun McKinnon in the Arizona Republic: About 25 miles west of Yuma, across the Colorado River in California's sand-dunes country, construction crews work day and night on two gaping basins that will, inside of a year, add another piece to Arizona's increasingly complex water future.

The Drop 2 Reservoir, a name befitting the project's utilitarian purpose, will collect the dregs of the Colorado, billions of gallons of water that seep through the cracks of an imperfect system. The water now flows south into Mexico if it can't be used immediately, written off as a loss for U.S. users.

For its $28.6 million investment in Drop 2, about 16 percent of the total cost, Arizona will receive a small share of the water saved, to be taken in even smaller increments over 20-some years. California and Nevada will split the rest based on their contributions.

The water saved - up to 70,000 acre-feet each year - will amount to barely one-half of 1 percent of the river's annual flow. Arizona's share, 100,000 acre-feet by 2036, is a few drops in the bucket for a state that in a year uses 7 million acre-feet. (An acre-foot is 325,851 gallons, enough to serve two average households for one year.)

But as demand for water creeps steadily past the supply available, no drop is too small, even if capturing it requires a giant hole in the desert. The question is whether that solution - spending millions of dollars to squeeze more water from a finite resource - is still the right one…

Yuma, Arizona from space, courtesy of NASA. That green surrounded by brown illustrates the problem