WeatherImpact Earth


Arizona's water supply could be impacted by continued drought conditions

Posted at 3:52 PM, Apr 26, 2021
and last updated 2021-05-06 16:40:44-04

PHOENIX — The long-term drought and effects of climate change means more trouble for the millions of people that depend on the Colorado River.

In a statement released in early April, the Arizona Department of Water Resources, and the Central Arizona Project state that they expect the first-ever shortage declaration for the river in 2022, meaning substantial cuts to Arizona's share of the water supply.

The experts in charge of managing much of Arizona's water supply give a serious warning: we all need to plan for a drier future.

"The resources are suffering because of climate change and drought, but we are responding appropriately to what's happening and we're prepared for it to get worse," says Ted Cooke, the General Manager for the Central Arizona Project, or C.A.P.

He oversees the 336 mile system of aqueducts and power plants that extends from Lake Havasu to south of Tucson, delivering 1.5 million acre-feet of Colorado River water to Maricopa, Pinal, and Pima counties, making up half of Arizona's water allotment.

For perspective, one acre-foot equals 326,000 gallons, which is enough to flood a football field under a foot of water.

There's only one problem: in recent years, because of drought and potential shortage, the Central Arizona Project has been taking less than its annual allotment, leaving some behind in Lake Mead.

The once dependable Rocky Mountain snowmelt is anything but, because of climate change.

A 2020 study by the U.S. Geological Survey links the dwindling flow of water with the loss of what is known as "albedo," or the snow's reflective quality. With less snow, the ground and air above the mountains heat up, causing any lingering moisture to evaporate into the atmosphere, instead of trickling down into the nearby streams, leading to the Colorado River, and eventually to Lake Mead.

For nearly a century, the lake has ensured a steady water supply for the Lower Colorado River Basin, which includes Arizona, Nevada, California, and Mexico.

Since 2000 however, the once healthy water supply at Lake Mead started dropping and kept dropping.

At its lowest, the lake level plunged more than 140 feet.

Action needed to be taken.

In 2007, the "Interim Guidelines" was created, which is a set of guidelines agreed upon by the Lower Colorado River Basin states, stating that each state, except for California, would put a percentage of its water allotment back into Lake Mead, if the lake level reached certain tiers.

If Lake mead dropped to 1,075 feet above sea level, or Tier 1, Arizona's annual allotment would be reduced by 320,000 acre-feet.

Tier 2, or 1,050 feet, would mean an additional reduction of 80,000 acre-feet.

Tier 3, or 1025 feet, would tack on another 80,000 acre-feet reduction.

A good start, but more needed to be done, says Tom Buschatzke, the Director of the Arizona Department of Water Resources.

"Around 2012, 2013, the basin state representatives & water providers recognized that the plan in 2007 wasn't enough. The risks were too high of Lake Mead falling."

While a new agreement was in the works, the Central Arizona Project voluntarily left more than 12% of its annual allotment, or 192,000 acre-feet, inside Lake Mead between 2015 to 2019, preparing for an uncertain future.

In 2019, the "Drought Contingency Plan" was signed. All lower basin states, including California, would reduce their water allotments even more under the same tier system.

Additionally, a near tier was introduced, called "Tier 0."

This tier means a mandatory reduction of 192,000 acre-feet for Arizona if the level at Lake Mead was below 1,090 feet, which it was in 2020 and 2021.

Since the C.A.P. was already doing this voluntarily, nothing changed for its water users.

What hasn't changed is the extensive and expansive drought in the southwest, intensifying over the past year.

This means a likely first for Lake Mead and the people that rely on the water stored here.

"Looking forward to 2022, all indications are that we'll be in a Tier 1 for the first time, which is a 512,000-acre-foot reduction for Arizona," Cooke stated.

That's nearly one-third of the Central Arizona Project's annual allotment.

This reduction eliminates access to C.A.P. water to agricultural customers, mainly in Pinal County.

The farmers and ranchers in these areas will have access to groundwater and help from other water users, but not the water source that they've had at their disposal for decades.

Buschatzke says that Arizona would likely be in Tier 2 today if the voluntary conservation and the 2019 Drought Contingency Plan had not occurred.

The situation is not ideal, but it's a necessary step to ensure that bigger reductions won't happen in the future.

"We will have enough water, but it won't perhaps be the same amount of water that we've enjoyed historically."

"The U.S. Bureau of Reclamation recently released its "24-Month Study" for April.

The report anticipates conditions on the Colorado River system for the next two years.

The results, unsurprisingly, show a very high likelihood of a shortage declaration for next year and beyond.

To read the full report, click here.