Arizona to Suffer Drastic Colorado River Water Cutback as Tier 1 Water Shortage Declared at Lake Mead

ON 08/17/2021 AT 03:03 AM

Yesterday the U.S. Bureau of Reclamation declared its first “Tier 1” water shortage at Lake Mead, the nation’s largest water reservoir. It will have devastating effects on Arizona, Nevada, and even Mexico starting January 1.

Colorado River Basin and Lake Mead

The Colorado River system in the American West and how it affects Lake Mead's estimated water levels as of January 1, 2022. Photo: CAP Arizona, via Twitter

The expected cutback in water supplied from the Colorado River is no longer a rumor.

After 20 years of drought which accelerated over the past year, Lake Mead is now at just 35% of full capacity. It is the lowest it has been since the reservoir was completed on September 30, 1935.

In early Spring 2021, the government released data that Lake Mead and Lake Powell, both large man-made lakes intended to buffer the occasional drought of individual seasons, were already at dangerously low levels.

Lake Mead was built as part of the 1930s’ Boulder Canyon project, which was built along the Colorado River. When at full capacity, the lake is 532 feet deep and contains 26.12 million-acre-liters of water.

For most of the lake’s existence, though the water levels had drained and refilled over time, it served its purpose to keep water flowing to farmers, agricultural needs, and individuals even when there were temporary drops in water flow within the Colorado River. An estimated 20 million people depend on the water from it, particularly in Arizona, Nevada, and even Mexico, which is allocated part of the water under an early agreement with the U.S. government.

The lake is fed by the Colorado River, which begins with snowmelt from the Colorado Rocky Mountains. It flows for 1,450 miles southwards, dammed in some places and with water routed off for agriculture, industrial applications including fracking, the single biggest industrial use for the water, and to support individual persons’ water supplies. The water is allocated, mostly according to a formula concocted in 1922 and has changed little since.

Since 1983, the lake’s level has steadily dropped, as billions of gallons have been diverted to fracking, agricultural needs grew, and the population increased. In the 21st century those demands have become tougher to meet as a long-term drought set in within the American west. That drought, a product of the climate crisis as temperatures rose and rainfall became less plentiful, has accelerated far more rapidly just in the last two years. The higher temperatures accelerate the impact of the drought, as reservoirs, agricultural fields, and the Colorado River basin itself evaporate more of the water now than in the past.

In April 2020, the lake had dropped to 42.97% of full capacity. Based on that and trends already evident about what has become the hottest and driest summer on record in the American west, the Bureau of Reclamation issued a warning that it might need to cut back on water allocation to some of its biggest customers starting next year.

The reason for the warnings is that the Colorado River system itself is operating only at half its normal throughput, according to information provided by the Department of the Interior. According to its records, the last 16 years were the driest in the last 1,200 years of history of that river basin.

On August 16, the Bureau of Reclamation announced that last year’s dry spell and this year’s drought coupled with high temperatures had dropped the water levels to just under 1,068 feet full (35% of total capacity), a drop of 17% from the total water volume present just 15 months ago. It then made it official: the Bureau was declaring a “Tier 1’ water shortage for the first time in the history of Lake Mead.

Various Warning Tiers for Lake Mead Water Levels

What the Tier 1 Water Shortage at Lake Mead means, and how much more water might fall before the next warning tiers get announced. Photo: ESG Hound, via Twitter

The shortage was announced based on projections that as 2022 begins, Lake Mead will be filled at just 1,065.85 feet above sea level, another three feet down from its current level. That is ten feet below the level at which the Bureau of Reclamation is required to cut back water distributed from the reservoir.

Effective January 1, 2022, that Tier 1 shortage means that Arizona will lose the supply of 20 percent of the water it normally draws in from the Colorado River.

Different parts of the state will experience the effects of the water shortage differently. In Pinal County, located just slightly southeast of Phoenix and the third most populous county in the state with over 460,000 inhabitants, farmers and ranchers will lose a full 50 percent of their normal allocation of water from the Colorado River. That will cause irreparable harm to land currently belonging to the Tohono O’odham Nation, the Gila River Indian Community, the San Carlos Apache Indian Reservation, and the Ak-Chin Indian Community, as well as extensive land used for agriculture and cattle raising by non-Native-Americans.

Arizona’s landholders will switch to groundwater to make up much of the difference in their water allocation. That will be expensive and risky, as it could undermine the aquifers which feed the region.

While some of that has planned for already as the state had seen the problem coming, the already-implemented increased water storage in the state, water-sharing plans to help those most in need get access, and conservation approaches newly developed in anticipation of what might happen will still not be near enough to address a 20 percent to 50 percent drop in water availability, depending on the region.

Many “will physically not have the water [they need], and they will have to figure out how to deal with the ramifications of that outcome,” said director of the Arizona Department of Water Resources Tom Buschatzke, in a statement released yesterday.

According to Arizona Farm Bureau head Stefanie Smallhouse, a rancher herself, famers in the Central Arizona Project, a region which depends on the Colorado River aqueduct in the state, may need to set aside as much as 40 percent of their land as fallow because of the lack of water. With many of those farmers producing cotton seed on their land there, Smallhouse warned that the lower production rates in the state will “reverberate into other areas of the United States which rely on our production of cotton.”

North of Arizona, Nevada will see its Colorado River water allocation cut by 7 percent from normal. It will be affected far less than Arizona since it does have access to other sources.

To the south, Mexico’s supply will drop by 5%. On Arizona’s western border, California will still see the same allocation of water from the Colorado, for this year at least. But then California already has its own problems with other water shortages throughout the state, such as at Lake Oroville where that reservoir is low enough that it has had to shut down its sole hydroelectric power plant.

The water level drop at Lake Mead is such that Hoover Dam, operating at its edge, is running at 25% less efficiency than normal. That lack of power will also soon be felt as far higher temperatures than in the past become the new normal in the region. The dam provides electricity for around 1.3 million people in Arizona, Nevada, and California. As it drops, the risks of rolling power blackouts in the region increase.

“We are seeing the effects of climate change in the Colorado River basin through extended drought, extreme temperatures, expansive wildfires, and in some places, flooding and landslides,” said the Interior Department’s assistant secretary for water and science, Tanya Trujillo, in comments to reporters yesterday about the Tier 1 water shortage declaration. “Now is the time to take action to respond to them.”