Explosive population growth will bring challenges to metro Phoenix’s water future

Apr 25, 2022, 4:45 AM | Updated: Apr 28, 2022, 9:33 am

Editor’s Note: This is the first of a five-part series called “KTAR Water Watch,” which will explore the present and future of the water supply across Arizona and metro Phoenix.

PHOENIX — The images are shocking. Areas submerged for decades are now islands.

Lake Mead and Lake Powell, two reservoirs Arizona relies on for its water, are historically low, with each about a third full.

Arizona State University climatologist Randy Cerveny says in addition to climate change, it’s explosive population growth in Arizona and other states that rely on water from the Colorado River via Lake Mead and Lake Powell that will present challenges in the future in the Valley.

Cerveny says most of the water that fills the Colorado River is due to melting snowpack in Colorado. The state is going through a historically dry period and the Rockies haven’t experienced consistent, above-normal precipitation.

“The river is so severely allocated that just south of Yuma, every remaining drop is sent to California,” Cerveny said. “It doesn’t reach the Gulf of California anymore. Even if there were to be more extra water that fell on the Colorado Rockies and into the Colorado River, it has already been allocated.

“We will never see those lakes ever go back to the days prior to the drought that we’re in right now.”

The Valley gets about 30% of its water from the Colorado River via the Central Arizona Project canal.

Salt River Project provides about half of the water for the Phoenix metropolitan area — approximately 2.5 million customers — from its chain of reservoirs on the Salt River and Verde River. The rest of the Valley water supply comes from groundwater.

The region’s ongoing population and business growth could strain the overall system, but Cerveny says the water sources won’t all dry up at the same time.

But is the business growth sustainable given the available sources?

“It will depend on which community they’re going to be affiliated with because different organizations will have to use different sources of water,” Cerveny said. “SRP is pretty picky about who they allow to have access to their water. There are other sources that charge a lot for their particular water.”

Storage in SRP’s reservoirs has dropped very little since 1996 thanks in part to some recent wet winters in 2017, 2019 and 2020.

The winters of 2005 and 2010 were also solid, while last summer’s powerful monsoon also added water to the system.

SRP’s chain of six reservoirs on the Salt River and Verde River provide about half of the Valley water supply and collectively are at about 70% capacity.

Central Arizona Project saw the first and so far only water cuts because of the declining reservoir levels, but the reduction only impacts agriculture at this time.

Bo Svoma, staff scientist and meteorologist with SRP, says the Colorado River basin stream flows into Lake Powell are very sensitive to warming, whereas the Salt and Verde rivers are about five times less sensitive to warming.

“What warming does is it increases the evaporative losses from the landscape and results in less water for stream flow,” Svoma said. “The Colorado River is more sensitive to that than the Salt and Verde.

“That one reason is why things aren’t as dire on the Salt and Verde.”

Even with the Valley’s explosive population growth since the mid 1990s, Svoma says demand has actually gone down.

“SRP has been delivering less water because of better efficiencies and water use and people being more conservation minded with their water use, which is really important,” Svoma said.

“That brings SRP into a perfect balance with the long term median inflow into the system is equal to our water deliveries, which is not the case on the Colorado River, which is over-allocated.”

Svoma doesn’t see Lakes Mead and Powell dropping to the point that they can no longer supply water to the Valley.

“I think it will be challenging to address the over allocation on the Colorado River, but people are working on that,” Svoma said.

“What happens with future precipitation is very uncertain, but from a western U.S. perspective the climate model projections are leaning toward increased winter precipitation for the Colorado River is a positive.”

Will the water situation impact the ability to lure business, specifically semiconductor outfits? Svoma says yes.

“Certainty in the water supply is attractive to businesses and there are several current projects that could increase the resiliency and sustainability of Arizona’s water supply,” Svoma said.

Lifetime Windows & Doors

We want to hear from you.

Have a story idea or tip? Pass it along to the KTAR News team here.

Arizona News

(Twitter Photo/@ArizonaDOT)...

Dust storm moves into Valley ahead of expected overnight thunderstorms

A dust storm was spotted Wednesday afternoon in the southeast Valley ahead of anticipated thunderstorms overnight.
18 hours ago
(Photo by Alex Wong/Getty Images)...
Danny Shapiro

AG Mark Brnovich says pre-statehood abortion ban is law of the land in Arizona

Attorney General Mark Brnovich released a conclusion Wednesday stating a pre-statehood abortion ban that only allows the procedure when it saves the mother's life is the law of the land in Arizona.
18 hours ago
Rob Duggan (Town of Gilbert Photo)...

Town of Gilbert promotes assistant Rob Duggan to fire chief

The town of Gilbert announced Wednesday that Assistant Chief Rob Duggan has been promoted to serve as the next fire chief.
18 hours ago
After multiple nights of abortion-rights protests, security fences and barbed wire surround the Ari...
Kevin Stone

Electronic surveillance used in 8 Phoenix abortion protest arrests; court doesn’t find probable cause

Electronic surveillance was involved in eight of the nine arrests state troopers made over the weekend at or near abortion rights protests at the Arizona Capitol, according to court documents.
18 hours ago
(AP Photo/Andrew Harnik, File)...
Danny Shapiro

US Rep. Andy Biggs of Arizona denies asking for pardon following Jan. 6 attack

U.S. Rep. Andy Biggs of Arizona on Wednesday denied asking for a pardon following the Jan. 6 attack on the Capitol in 2021.
18 hours ago
Follow @Crossfire923...
Sponsored Content by Arizona Department of Health Services

Great news: Children under 5 can now get COVID-19 vaccine

After more than two years of battle with an invisible killer, we can now vaccinate the youngest among us against COVID-19. This is great news.

Sponsored Articles

Dr. Richard Carmona

Great news: Children under 5 can now get COVID-19 vaccine

After more than two years of battle with an invisible killer, we can now vaccinate the youngest among us against COVID-19. This is great news.
Day & Night Air

Tips to lower your energy bill in the Arizona heat

Does your summer electric bill make you groan? Are you looking for effective ways to reduce your bill?
Arizona Division of Problem Gambling

Arizona Division of Problem Gambling provides exclusion solution for young sports bettors

Sports betting in Arizona opened a new world to young adults, one where putting down money on games was as easy as sending a text message.
Explosive population growth will bring challenges to metro Phoenix’s water future