With the feds' help, Roosevelt Dam was completed in 1911. Other dams tamed the wild rivers and formed immense reservoirs in ways that Native Americans couldn't. The Hohokam canals, built along stunningly precise grades, were cleared and modernized with concrete. In 1980, a crisis of pumping too much groundwater was averted with a new law that requires "water banking" back into aquifers. Then came the Central Arizona Project canal, which Congress authorized in 1968 and now provides water to about 40 percent of the state's population.
New development in the state must prove that it has a 100-year water supply before it can be authorized, a standard not required in other states with potential water-shortage problems.
No one can predict the future with certainty, of course. Maybe it never will rain again in Phoenix. However, worst-case scenarios are not likely.
Climate change will be felt gradually, experts say. It may grow hotter over time, but it's already hot here, and a few more degrees won't matter. A dramatic end to rain, snow, and river flow, like the shutting off of a spigot, isn't a realistic prediction.
The worst 14-year period of drought in the past 100 years is taking place now, and scientists predict further reductions in the flows of the Colorado, Salt, Verde, and Gila rivers in the next few years. Releases of Colorado River water from Lake Powell will drop next year to their lowest level since the lake was filled in the 1960s. Yet, officials say, even if poor snowpack persists for another two years and a shortage is declared in 2016, resulting in fewer allocations for farms and underground aquifers, Valley residents would keep receiving their full share of CAP canal water. New development would continue.
"We're still growing into our water supplies," asserts Dave Roberts, executive manager for SRP's water-rights and contracts department. "Phoenix is among the most sustainable" among Southwest cities because of advance planning and conservation efforts.
The underground water-banking program has stored nearly two trillion gallons of water that can help the area get through extreme dry periods of little surface water, if it comes to that, Roberts says.
Meanwhile, per-capita water usage by Valley residents has decreased at least 20 percent since 1990 because of public awareness and such technology as water-efficient toilets.
The bottom line is that experts, like those at SRP, feel confident that water supplies for the Phoenix area will be sufficient to maintain the growth that fuels our economy for the next several decades. Regional water problems are expected during this time, because high-growth areas, including those in the East Valley's Superstition Vistas area, aren't "blessed with an abundant water supply," Roberts says. "Buckeye, Queen Creek, Apache Junction, Goodyear are where we are going to have to get creative."
After this time, as even more new residents arrive, estimated water supplies won't meet the expected demand, especially those from the Central Arizona Project canal. Sandy Fabritz-Whitney, director of the Arizona Department of Water Resources, says state planners are working to address the future "imbalance" predicted for 50 to 100 years from now.
"You're not going to get to a point where you just run out of water because you can't grow beyond what you have," she says, referring to the state's 100-year supply requirement for development. "There could be a drought that disrupts the supply. That's when you go to your other water supplies. Unlike Las Vegas, we're redundant."
With the double-edged sword of increasing demand and dwindling supply, however, eventually Phoenix and the rest of the state will need more options.
"Ocean desalination is the next supply," Roberts says. "The technology is there."
One likely spot for a large-scale desalination plant is at the northern end of the Gulf of California, in Mexico, which isn't lined by million-dollar homes (like Southern California) and is relatively close to Phoenix.
Water could be piped in from there or traded with Mexico for part of its share of Colorado River water, experts say. The project, considered in some form since the 1960s, would need to involve an expensive energy source to power it — maybe nuclear — because desalination needs continuous, reliable electricity to function.
With a higher projected population at that time for Arizona and the six other Western states expected to join in on such a project, it would be easier to fund the expected $10 billion cost (based on today's currency value), Roberts says.
Mexico is interested in the plan because the northern state of Sonora, with about 2.5 million people, desperately needs more water for its growing population.
The subtitle of Andrew Ross' book about Phoenix, Lessons from the World's Least Sustainable City, is fact-challenged.