Declining water levels at Lake Powell leaves a one-in-three chance that its dam will be unable to produce hydropower in under two years time, the US government has reported.
It is a troubling development at the vast reservoir which generates electricity for millions of people in the US West. The region is suffering from a 20-year “megadrought”, worsened by increasing temperatures linked to the climate crisis.
On Wednesday, the Bureau of Reclamation, a Department of the Interior agency which oversees water resource management, released new five-year projections for Lake Powell, near the Utah-Arizona state line, and Lake Mead, located on the Arizona-Nevada border.
That lakes are at a combined 39 per cent capacity today, down from 49 per cent at this time last year, the Bureau reported. In August, US officials declared the first-ever water shortage from the Colorado River.
Both lakes act as storage from the Colorado River, which flows from the Rocky Mountains to supply water to 40 million people and sustain 4.5m acres of agriculture.
The major reservoirs show continued risk of falling to critically-low water levels as a result of the historic drought and low-runoff conditions.
The Upper Basin experienced an exceptionally dry spring in 2021 with April-July runoff into Lake Powell totaling just 26 per cent of average, despite a fairly average snowfall in winter 2020.
Lake Powell’s water levels have a 3 per cent chance of dropping below what’s needed for its Glen Canyon dam to produce hydroelectricity in 2022, the Bureau report stated. By 2023, the risk of the dam being unable to generate power increases to 34 per cent.
At full capacity, the Glen Canyon dam is the second-largest producer of hydroelectricity in the Southwest after the Hoover Dam, supplying power to an estimated 5.8 million customers.
“The latest outlook for Lake Powell is troubling,” said Wayne Pullan, Reclamation’s regional director for the Upper Colorado Basin.
“This highlights the importance of continuing to work collaboratively with the Basin States, Tribes and other partners toward solutions.”
Lake Powell was topped up with water this summer from the smaller reservoirs of Flaming Gorge, Blue Mesa and Navajo.
Water levels at Lake Mead are at a record low and the Bureau of Reclamation recently declared the first-ever shortage, meaning Arizona, Nevada and Mexico will get less water than normal next year.
The new projections indicate a 66 per cent chance that Lake Mead will decline to a critical level of 1,025ft in 2025. There is a 22 per cent chance of the reservoir elevation dropping to 1,000 feet that same year. Water would become inaccessible to states downstream at 895 feet, often referred to as “dead pool,” says government officials.
A white “bathtub ring” of minerals is now evident around the lake, showing where the high water line once stood.