Meeting the drinking-water needs of Arizona’s future population will force residents to live with trade-offs. But as more people move here and are born here, they may not have a choice, state officials say.

Saying the state’s population could nearly triple by 2110, the Arizona Department of Water Resources says we must start planning now to get more supplies, particularly from desalinated seawater.

If something isn’t done, the agency predicts statewide annual water shortfalls of up to 900,000 acre-feet a year by 2050 and 2 million to 3 million acre-feet — enough to serve 4 million to 9 million people — by the early 2100s.

Those predictions are based on forecasts from another state water report of a few years back that Arizona would have 10.5 million people by 2035, 13.3 million by 2060 and 18.3 million by 2110. Today, the state’s population is estimated at  6.6 million.

The agency’s new report lists plenty of ideas for staving off future water problems, from sewage effluent reuse to more conservation to cloud seeding. But planning for seawater desalination is one of the few options the report recommended should start now.

One reason is that planning, designing, financing and building a desalination plant could take up to 20 years. That’s partly because seawater desalination would cost a lot, the report said — 10 or 20 times the cost of bringing Central Arizona Project water to Tucson by canal from the Colorado River. The cost of desalination has dropped significantly in recent decades, however, as the technology has improved, the report noted.

Separating salt from seawater is the high end of the desalination scale. Another option is to desalt the brackish, salty groundwater that already is plentiful in Arizona.

It’s much less expensive and would carry a far smaller environmental cost, said David Modeer, the CAP’s general manager. Seawater desalination plants use huge amounts of greenhouse-gas-generating energy, for instance.

By contrast, “the brackish groundwater in Arizona has a lot less salt than seawater” and wouldn’t need as much energy to get the salts out, said Christopher Scott, a University of Arizona water policy professor. “We should leave no stone unturned in our search for these options.”

He and environmentalists are also uneasy about the need for disposing of large amounts of highly saline brine wastewater left over after salt is removed from seawater.

Instead of pushing big water projects, the state should look at reducing water demand and seriously consider whether the growth envisioned in the report is achievable, desirable or sustainable, the Sierra Club said.

“There are not a lot of water-supply options that are economically feasible, and that’s certainly the case for water-importation schemes,” said the club’s Steve Pawlowski, who specializes in water issues. “A lot of options in this vision statement are speculative at best.”

House Speaker Andy Tobin dismissed the idea of limiting growth, saying he’s glad such limits didn’t exist when he moved to Arizona 30 years ago. Tobin “is behind all efforts to explore ways to secure Arizona water supply well into the future,” said Christopher Leone, spokesman for the House Republican caucus.

In an interview, Tobin said he hopes the Legislature can push through a bill this year to set up a low-interest loan program offering $30 million for water infrastructure today and up to $100 million over the next few years. While that’s a fraction of the cost of building a major seawater desalination plant, it’s a start, he said.

Said Tobin, “I would like to see the Legislature start having conversations about desalination now so people can clearly see the costs.”

Starting a dialogue

Gov. Jan Brewer, who commissioned the state water report, isn’t ready to push toward any particular solution.

“The governor wants to start the dialogue now and not have to act because of a crisis,” said her spokesman, Andrew Wilder. “Moreover, the ‘vision’ offers a menu of solutions. Some can be achieved locally, others statewide, some regionally or a combination.”

Michael Lacey, the state water agency’s interim director, said the report gives Arizona time to build a coalition among elected officials and business leaders.

“It’s really a question of what the state’s destiny will be — whether we limit ourselves to the water resources we have available today, or whether we choose to develop water supplies to allow the state to continue to grow,” Lacey said.

This is the third major report in the past two years warning about Arizona’s future water problems. One report, from the State Water Resources Development Commission, focused on population growth and future demands. The other, from the U.S. Bureau of Reclamation, warned about threats to the Colorado River from drought and climate change.

The new state report notes that after the second study came out in December 2012, many critics dismissed water-importation schemes like desalination because of their cost and environmental problems. But even if Arizona can manage to conserve even more water, reuse effluent and employ other tactics, shortfalls remain likely, the report said.

Environmental change

There are two ways Arizona could get involved in desalinating seawater. It could build plants on the Sonoran or Southern California coasts and bring the water here directly. Or, Arizona could exchange seawater to California or Mexico for some of their Colorado River water rights.

As CAP’s Modeer sees it, the Mexican coast is the only reasonable place for Arizona to get involved in seawater desalination. California isn’t likely to cut deals with Arizona involving desalinated seawater when it’s in its own water crisis, he said.

But getting a plant in Mexico won’t be done in the short term, although it needs to be considered for the long term, he said. A few years back, the CAP had a strong enough interest in building a desalination project in Sonora to do an engineering study, but the idea died.

“The national political structure in Mexico didn’t want to do anything with it,” Modeer recalled. “In Mexico, water is all controlled out of the Mexican national government and is really caught up in national politics in Mexico.”

A Gulf of California desalination plant will have major environmental issues, Modeer said, in part because the upper gulf is not an open water system, in which water circulates easily into the ocean. In dumping the brine wastewater into the gulf, “you would change the water quality and change the environment significantly,” Modeer said.

That won’t sit well with conservationists.

“It’s such a fragile ecosystem down there,” said Val Little, director of the Water Conservation Alliance of Southern Arizona. “The little dolphins down there are so critically endangered. It’s just going to cause a firestorm.”

Brackish water

CAP will start working on brackish water desalination this year, bringing up the issue to various interest groups and trying to develop a financing mechanism, Modeer said.

The state’s brackish water supply is far less than what could be obtained from the ocean. There are at least 20,000 acre-feet, and possibly much more, near the Willcox Playa in Southeast Arizona. Maybe 40,000-50,000 acre-feet are available annually in the Yuma and Buckeye-Goodyear areas, 10,000 acre-feet near Gila Bend and more than 100,000 acre-feet on the Navajo Reservation.

But that much would make a huge difference in locations where it’s available, CAP spokesman Mitch Basefsky said. Brackish water, which is the product of agricultural wastewater runoff in some places and occurs naturally in others, generally lies close to the surface, and is less expensive to pump out than much of Arizona’s fresh groundwater: 4-10 feet underground in the Yuma area, 10 to 100 feet deep near Buckeye; and 25 to 200 feet deep around the Willcox Playa. Only in Navajo country is the brackish water really deep — about 500 feet.

Risk of inaction

The water study was not an academic exercise — it was designed to spur action, said Lacey, the state water director. The agency hopes for broader public participation in water issues than anytime since Arizona’s landmark Groundwater Management Act passed in 1980, he said.

But the report also acknowledges — in boldface — that the lack of an immediate water problem increases the risk of inaction.

Even now, Gov. Brewer appears in no hurry for action and says she doesn’t believe legislation is needed this year.

The governor wants the state water agency to first reach out to 22 planning areas around the state and start talking about potential solutions, said her press secretary, Ann Dockendorff.

Garrick Taylor, a spokesman for the Arizona Chamber of Commerce, said that group agrees that “we need to have a water conversation” bringing all interest groups together.

But it’s unlikely the new report’s recommendations will get much traction over the next 12 months because the state likely will have a new governor next year, he said.

If desalination emerges as an option, he said, “hopefully the technology will be such that we can do it without breaking the bank.”

Contact reporter Tony Davis at or 806-7746. Follow him on Twitter@tonydavis987.