The looming specter of shortage on the Colorado River poses a serious concern for states relying on the precious source of water, but with foresight and planning, many parts of Arizona are prepared to endure for decades to come.
Kelly Mott Lacroix, senior research analyst with the Water Resources Research Center at the University of Arizona, explains the difficulty of trying to summarize the condition of the state as a whole.
“You can’t have a statewide statement that everyone is going to be fine because different areas have different water resources,” Mott Lacroix said. “And some areas, like Tucson, we have our Central Arizona Project water that we mix with the groundwater then we pump it back up.
“If you’re in the Phoenix area, you have water from the Verde (river), water from the Salt (river), you have water that’s pumped from the Colorado River, just like we do down in Tucson, and you have groundwater.”
In Tucson, the projections of water availability are optimistic and reach as far 2050, with considerations for population growth, but depend on when a shortage on the Colorado is declared.
A shortage on the Colorado River is based on water volume in Lake Meade. A monthly report produced by the U.S. Bureau of Reclamation, known as the 24-Month Study, forecast the levels of the lake.
The determining factor for a shortage would be if the water level prediction falls to 1,075 feet or lower. Currently, the potential for a declared shortage may be as soon as 2016 but the higher probability is being considered for 2017.
According to CAP, there has never been a declared shortage on the Colorado since 1964.
When a shortage is declared some parts of Arizona will be in better positions than others and it is due to the various capabilities and properties of water sources and infrastructure for a given region.
Fernando Molina, the public information officer for Tucson Water, acknowledges that a future shortage on the Colorado is inevitable but the uncertainty of “when” creates a difficulty of making definitive statements as to specific time frames.
“We know that it’s going to happen, we just don’t know when it’s going to happen,” Molina said. “If this happens sooner and we’re not able to recharge as much water, then we will have a bit of a shortage but we’ll still have our groundwater to pump if we need to.
“We’re holding on to that as the very last source of water that we would use because we want to retain that.”
The recharge of groundwater is one of the reasons why Tucson Water is better equipped than many other areas to handle an impending shortage. The CAP water is put into recharge fields that add to the groundwater supply.
The pumping Tucson Water does to supply its service area is not greater than the amount of water being put into the ground. The result is a surplus of water that remains banked in the ground for future use.
Part of the advanced planning done by Tucson Water for meeting future needs was the construction of wells surrounding the recharge fields.
The first phase of construction was the Central Avra Valley Storage and Recovery Project that began in 1996 and was completed in 2002. The second phase was the Southern Avra Valley Storage and Recovery Project that began in 2006 and was completed in 2012.
The completion of the two Avra Valley sites allowed Tucson Water to take the full allocation of CAP water that continues to be stored in the aquifer.
The wells have created an advantage over other providers that did not construct wells at the time the fields were being constructed in their areas. Now those providers cannot access the water without first having to construct the expensive well infrastructure that already exists in Tucson.
While a shortage would be bad, many Arizonans would not see immediate effects. The first to be effected would be the agricultural industry in Arizona that uses the bulk of the state’s water. Cities and tribes that rely on CAP water would feel the effects much later should conditions continue to worsen.
In Arizona, 70 percent of the usage goes to agriculture, 25 percent to cities and 5 percent to power generation and mining uses, said Mott Lacroix.
After a declared shortage it would likely take 15 to 20 years for the cities in Arizona to be effected, Molina said.
There are several factors for Tucson having a good outlook in water availability. One factor is the different conservation programs from Tucson Water that have made the public and businesses more efficient in their water usage.
“Our whole management strategy here is to stop pumping non-renewable groundwater,” Molina said. “Last year we pumped groundwater at the same level we pumped in 1944.
“We pumped the same volume of water in 2013 as we did in 1989, but we’re serving more than 200,000 more customers.”
Although groundwater can build up naturally, it is considered a finite and non-renewable source because of the time it takes to replenish itself without artificial intervention, such as the recharge provided by CAP water.
“Groundwater, once you pump it out, at least in the area we live in, the geology here, for all practical purposes it’s not going to be replenished in a human time frame,” Molina said.
Rapid influxes of storm water from rainfall, even with a stronger El Nino monsoon season, do not provide significant replenishment of groundwater sources. Much of the water, around 90 percent, is lost to evaporation or runoff away from Tucson Water’s wells and jurisdiction.
A better source of natural water is slower moving flows resulting from snowmelt. Snowmelt is the primary source of water in the Colorado. This has led to an increased awareness of climate and weather patterns outside of Arizona.
“We never had to worry about weather outside of the Tucson basin before,” Molina said. “Now we have to understand climate and what’s happening because that effects our planning.”
Ben McMahan, research, outreach and assessment specialist with CLIMAS Institute of Environment at the University of Arizona, highlights the uncertainty of predicting precipitation effects on the Colorado.
“In the long-term, projections suggest a gradual warming in the Southwestern climate, an increase in a few degrees over a few decades,” McMahan said. “As far as how that relates to sort of the specific variability of water and precipitation, it doesn’t have a very good handle, or at least the models don’t have a very good handle on what the changes in precipitation might look like.
“We think it’s going to be warmer and drier but precipitation is a lot harder to predict,” he said.
While precipitation and how climate change can affect it is too unclear to make a definitive statement about, the higher temperatures could affect the hydrological system in how it reacts with the snowmelt that supplies the Colorado.
The increased temperatures in winter could cause the snow to melt earlier making the flow begin earlier and increase the amount of evaporation as a result of it beginning sooner, McMahan said.
Even with an impending shortage on the Colorado, there are no calls for panic coming from water providers or researchers about a potential water crisis in Arizona. Despite the positive outlook on water supplies to most cities and tribes, Mott Lacroix cautions against allowing that to be an excuse for complacency.
“We live in an arid environment, we live in an arid environment that’s getting increasingly arid, so we have to continue to think about where that water is going to come from in the future,” she said. “So long as we’re thinking about it and planning for it and being proactive, we’ll be fine.”
Jorge Encinas is a reporter for Arizona Sonora News, a service from the School of Journalism with the University of Arizona. Contact him at jencinas9@email.arizona.edu.
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