Lake Mead

Hills showing the change in water level at Lake Mead.

In and effort to preserve the Colorado River and Lake Mead’s water level, Arizona lawmakers passed a Drought Contingency Plan in the late hours of Thursday, Jan. 31.

The new plan seeks to correct a water deficit in Lake Mead; lower basin states annually take 1.2 million more acre-feet of water from the Colorado River system than is returned. 

Arizona receives nearly 40 percent of its water from Lake Mead, which is facing a 19-year drought. Since July 2018, stakeholders from across the state have worked to develop the DCP, which reduces water deliveries to all lower basin states,  including Arizona. The Governor’s Office declared the DCP as historic, calling it one of the most significant pieces of water legislation in Arizona. 

According to Oro Valley Water Utility Director Peter Abraham, anytime a group of legislators can agree on something, “It’s historic.” 

“If there’s anything landmark about it, it’s that California is participating,” Abraham said.

The DCP improves upon a similar plan, Arizona’s 2007 River Shortage Guidelines, also put in place to preserve Lake Mead, though its provisions proved to not be drastic enough. 

The DCP sets “a schedule of voluntary cuts that users agree to take to keep lake levels sustainable” while at the same time protecting “high priority users” from these cuts. Essentially, Arizona’s agriculture will feel the brunt of water cutbacks, while the high priority users, such as municipalities like Oro Valley and Marana, remain unchanged for the time being. 

“With the current drought contingency plan, the structural deficit is made up before it hits municipalities such as Oro Valley,” Abraham said. “And if we start seeing continued shortages, it allows us to predict and make long-term planning.” 

The 2007 River Shortage Guidelines indicated three tiers of water shortage on Lake Mead. When these proved to not be drastic enough, the DCP added additional cuts onto these tiers. The lower Lake Mead’s water level, the more Arizona (and other states dependent on the Colorado River system) cut back. 

At its greatest depth, Mead has a surface elevation of 1,221 feet. According to the Central Arizona Project, if the Lake Mead elevation reaches 1,090 feet, Arizona must cut back 192,000 acre feet. If the elevation reaches 1,040, Arizona must cut back 640,000 acre-feet, and so on.

Pinal County’s agriculture industry may be among the first Arizona systems to take a cut. Pinal is a mostly agricultural county, without major high priority user municipalities. 

“The reason Pinal County is hurting so much in this, is because they’re not mitigated by a higher priority user, like Pima or Maricopa County are.” Abraham said. “For all intents and purposes, it’s an agriculture-dominant area, where as Pima is a mix [of agriculture and municipality].”

For local municipalities to receive a water cut, Arizona would have to call for roughly an additional 250,000 acre-feet of water to be preserved, almost another 20 percent on top of the current 1.2 million. But even this wouldn’t initially stall towns like Oro Valley and Marana, which have each been taking steps to recharge the local aquifer. 

“Marana is in a good spot, similar to most other municipalities in Southern Arizona,” said Marana Water Director John Kmiec. “Southern Arizona has always been conscious about water.” 

If Lake Mead drops below 1,025 feet, the municipality group could see water reductions of up to 7 percent. A 7 percent cut would equate to a reduction of 721 acre-feet a year of water for Oro Valley. Oro Valley’s current annual allotment is 10,305 acre-feet, of which the town only used 7,4000 in 2018.  

Abraham estimates even if Oro Valley were asked to cut back 10 percent of its water, build-out could still be achieved. He said it’s thanks to careful management of water via a master plan, which has Oro Valley now using less groundwater than it did in 2003, despite an increase in population.

It’s a similar situation in Marana, thanks in part to the town’s new water reclamation facility, which can treat 1.5 million gallons of wastewater per day, pumping the reclaimed water back into the ground’s natural aquifer.

“Water cuts are one of the reasons the town got into the wastewater field—to diversify our water portfolio,” Kmiec said. “We’re currently getting water credits both for CAP and aquifer recharge water. The Tucson area water departments are in a really good spot for dealing with drought cutbacks.”

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