BUCKEYE, Ariz. — Drive traffic-clogged Interstate 10 through Phoenix's West Valley suburbs and you'd hardly know the Southwest is as dry as it's been in 1,200 years.

Water gulping data centers, large warehouses and distribution centers have sprouted in the barren desert. Housing development after housing development is slated for construction.

A two lane highway is being widened in the former farming town of Buckeye, at the edge of the Phoenix sprawl, to make way for an 800 home "master planned community." A sign advertises new homes coming soon with the offer of joining "the VIP interest list."

City officials proudly promote Buckeye as one of America's fastest growing cities. In 2000, the population was around 6,500. Today it's north of 111,000, according to the city's mayor Eric Orsborn. His city's master plan calls for future growth encompassing a staggering 640 square miles of open land to the south, west and north.

"For perspective, the city of Phoenix is about 518 square miles, so we have this massive footprint to grow into," Orsborn says.

But where are they going to get the water? The answer is complicated.

People want to move to Arizona and Buckeye can't stop them

Phoenix is now America's fifth largest city. And the growth and economic boom particularly in its West Valley is continuing unabated despite larger questions about the future of water supplies amid a 23 year megadrought on the Colorado River.

Winter temperatures at the river's headwaters in the Rocky Mountains have risen by an estimated 3 degrees Fahrenheit since 1980, meaning less water for the region's snow fed reservoirs.

Arizona has some of the lowest priority rights to the river water of any of the seven basin states. So Phoenix and its suburbs are increasingly turning to groundwater as the state has endured big cuts to Colorado River water.

In Buckeye, Mayor Eric Orsborn, who owns a construction company and also grew up in the West Valley, is accustomed to fielding questions from a skeptical public who he says doesn't always understand how meticulously water is managed in Arizona. In Buckeye, he says, the city recently implemented a drought management plan. They're investing heavily in water reuse and recycling and and working aggressively to find water to import.

"A lot of people want to move here," Orsborn says. "Part of it is the regulation, the tax, how we do business in Arizona. Part of it is the open opportunity that's here."

Governor says her state is at a tipping point over water

But there's been a small damper on all the opportunity talk in the West Valley lately. Arizona's new Governor Katie Hobbs, a Democrat, released a state report she says was hidden by her Republican predecessor Doug Ducey. It shows that most all of the ground water in the West Valley is already spoken for and allocated, if not over-promised already.

"I just think there was a lack of real honesty with the people of Arizona about the situation we're in," Hobbs said in an interview with NPR.

Asked whether she thinks it's time to curb future development given the water crisis, Hobbs replied: "I don't think we're there yet. But I think if we don't really address these issues head on, look at the reality of the situation with water, look at how quickly we're growing, then we will get to that point."

Still, is Phoenix and the rest of booming central Arizona facing some sort of reckoning over growth? It's not yet clear.

In Buckeye anyway, city officials welcomed the release of that Department of Water Resources analysis. Mayor Eric Orsborn says it helps his city better plan. For now, most of the construction is continuing because developers already had met the state requirement to prove they have a one hundred year water supply lined up.

"I don't think we want to shut off all of the growth trying to figure out the solution for all the growth, " Orbsorn says. "We can do this in an incremental approach."

Much of Buckeye's growth plan relies on taking revenues from the boom to go out and buy what would most likely be imported water from other basins to support future growth here.

"It's definitely our intent to make sure we're doing exactly what we're required to do so that we don't ever run out of water," Orsborn says.

Phoenix uses way less water today despite exploding growth

Phoenix and most of its suburbs have become really good at using a lot less water even as their populations boomed, according to Sarah Porter, director of the Kyle Center for Water Policy at Arizona State University. Agriculture still uses the bulk of all the available water in Arizona - around 70%.

"We have largely decoupled urban growth from an increase in water demand," Porter says.

Many cities have been pumping a lot of their Colorado River water into the underground aquifers where they've stored it for years. West Valley suburbs have also spent millions on conservation and recycling. The city of Peoria's water advisor Brett Fleck says they've been trying to wean themselves off the river for years.

"When I see these headlines I think, yeah, if we continue on the path we're on, there might be an ecological disaster, there might be a real problem," Fleck says. "It's scary to think about, but we're trying to change the direction that we're headed in so those things don't happen.

People are even talking about a rescue plan to build a desalination plant on the Sea of Cortez and pipe water across Mexico to here. And it's not like the Hobbs groundwater report stopped new construction.

Most developers in cities like Buckeye already had approval to build or expand planned communities and resorts from state and local regulators.

But as is the case across the arid West, a lot of Arizona's rules on development and water are based on estimates - some written in cooler times - when most people didn't believe the Colorado River might actually run dry.

One person sounding the alarms is Kathy Ferris, an attorney and former director of the Arizona Department of Water Resources.

"For a long time a lot of those master planned community developers just thought well, we'll get to be able to do this, we'll get to be able to use this groundwater," Ferris says. "And you know what? They can't because there's not enough of it and it's already over-allocated."

A similar parallel is being drawn with the Colorado River itself. Ferris helped write what was at the time hailed as a landmark groundwater management act passed in Arizona in 1980. Then, many cities were relying solely on groundwater to support their growth. Now, Gov. Hobbs wants to expand and modernize it, especially to regulate uncontrolled pumping in rural areas, which Ferris finds encouraging.

"We cannot just grow anywhere and everywhere and as much as we want and still sustain every kind of economy and economic growth that we want, we have to make choices," she says.

One Phoenix suburb already ran out of water

A cautionary tale of uncontrolled development in a desert lies north of the wealthy Phoenix suburb of Scottsdale.

John Hornewer owns a water hauling company in Rio Verde Foothills, an unincorporated sliver of Maricopa County. Some people had wells but most families lived off of hauled water from Scottsdale, until that city cut them off at the start of this year, citing its shrinking Colorado River deliveries.

"You know what, when Scottsdale cut us off, that's a reality check," Hornewer says, standing next to one of his six silver delivery tank trucks. "In my personal opinion, we're living way outside our means, you know, to build when you don't have water just doesn't make sense."

And yet even on his country road, lots are still for sale and even some houses are being built. A few miles away, neighborhood activist Karen Nabity and her husband are living on about twenty gallons of hauled water a day. (a typical US family uses upwards of 300 gallons a day). They've been rationing what's left in their underground tank since January first, the date deliveries were cut off.

"It's like camping in your own home," Nabity says, with a chuckle. On a recent afternoon she was saving the water she'd used to wash vegetables in her kitchen sink, reusing it for toilet flushing.

Scottsdale recently said it would resume some water deliveries here. But Nabity knows it's not a permanent solution. She says her home state needs to get much more aggressive cracking down on turf and especially outdoor watering and landscaping.

"The water is overallocated in Arizona and years ago they didn't think the river would ever stop flowing but guess what, it just might and we need to be prepared for that."