First-ever Lower Colorado River Basin Water Shortage Declaration

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Peter Lobner, updated 17 September 2011

At its maximum capacity, Lake Mead water level is at an elevation of 1,220 feet (372 meters) at the Hoover Dam and holds 9.3 trillion gallons (36 trillion liters) of water. It was last at its maximum capacity in 2000 and has been declining since then as shown in the following graph.

Source: Universe Today, data via US Bureau of Reclamation & NASA

In my 18 June 2021 post, I discussed the Lake Mead water supply for Las Vegas and the alarming trend of decreasing water level in Lake Mead as a result of the persistent drought in the watershed for the Colorado River. 

In July, the Bureau of Reclamation began releasing additional water from reservoirs upstream of Lake Powell (which is upstream of Lake Mead) in an attempt to stabilize the lake level and maintain hydropower generation at the Glen Canyon dam (which forms Lake Powell). 

The following chart shows that the Lake Mead water level was at 1,067.72 feet on 17 August 2021, more than seven feet below the 1,075 foot threshold for triggering a water shortage declaration.  The lake level appears to have temporarily stabilized, possibly benefiting from the increased releases into upstream Lake Powell.

Source: Universe Today, data via US Bureau of Reclamation & NASA

On 16 August 2021, the Bureau of Reclamation issued their much anticipated projection of 2022 operating conditions for Lake Powell and Lake Mead. They reported: 

“Given ongoing historic drought and low runoff conditions in the Colorado River Basin, downstream releases from Glen Canyon Dam and Hoover Dam will be reduced in 2022 due to declining reservoir levels. In the Lower Basin the reductions represent the first “shortage” declaration—demonstrating the severity of the drought and low reservoir conditions.”

The planned actions in response to this first-ever shortage declaration take effect on 1 January 2022, as described in the Bureau’s news release here: https://www.usbr.gov/newsroom/#/news-release/3950

In summary, the following cuts in Colorado River water allocations are expected:

  • Arizona:  Loses 18% of the state’s annual apportionment
  • Nevada:  Loses 7% of the state’s annual apportionment
  • Mexico:  Loses about 5% of the country’s annual allotment

California has more senior water rights than Arizona and Nevada and will be spared immediate cutbacks when they are implemented on 1 January 2022.

Additional cuts in water allocations will be triggered if Lake Mead water level continues to decline to the following thresholds:  1,050 feet, 1,045 feet, and 1,025 feet.

Let’s pray for a lot of wet weather in the US southwest.

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