By Tom Buschatzke, director, Arizona Department of Water Resources and Ted Cooke, general manager, Central Arizona Project
(The following opinion piece was published in the Sunday, May 8 edition of the Arizona Republic)
For weeks, we’ve been seeing media reports regarding conditions in the Colorado River Basin, specifically with regard to our country’s largest reservoirs, Lake Powell and Lake Mead, which have dropped to record low elevations.
The media have been reporting it accurately. The Colorado River Basin has been in a prolonged drought, exacerbated by climate change. We are experiencing the driest conditions in the Colorado River Basin in more than 1,200 years – and these conditions are expected to continue well into the future. Both Lake Powell and Lake Mead are approaching critical elevations and will require unprecedented management actions to protect infrastructure in both the Upper (Colorado, New Mexico, Utah and Wyoming) and Lower (Arizona, California, Nevada, parts of Mexico) Colorado River Basins. Protecting infrastructure protects water supplies.
Lake Powell and Lake Mead operate “conjunctively.” That means that the operations of one affect the other. The system is designed to work so that runoff originating in the Upper Basin fills Lake Powell, and Lake Mead is filled by releases from Lake Powell and intervening flows below Glen Canyon Dam.
Lake Powell releasing less
“Operational uncertainty” has become a watchword for Lake Powell. Lake Powell is at 24% of capacity (elevation 3523’), the lowest since it was first filled. At this juncture, Lake Powell’s elevation requires immediate protective actions. This year, Glen Canyon Dam will be releasing about 500,000 acre-feet less than was anticipated to Lake Mead. Lake Mead and the Lower Basin still have the ability to recover this water, but it will be left in Lake Powell to protect that reservoir. Lake Mead is also at record low levels, but the infrastructure is not currently at risk.
Shortage declaration planning
With the decreased release, the elevation of Lake Mead will drop this year by an additional eight feet. But when the Bureau of Reclamation makes the 2023 Shortage Tier determination for Lake Mead, it will account for the water held back in Lake Powell as if it had been delivered to Lake Mead.
The shortage declaration will occur as usual in August, and current projections point to a Tier 2 Shortage in 2023. For Arizona, that would mean at least a 592,000 acre-foot shortage, as compared to the 512,000 acre-foot shortage in 2022. That means less water for CAP water users.
For Lower Basin water users this will mean that collectively, 821,000 acre-feet of water will be left in Lake Mead (721,000 acre-feet among Arizona, Nevada and Mexico and contributions of up to 100,000 acre-feet from Reclamation), plus the additional volumes as part of the “500+ Plan”. Signed late last year, the 500+ Plan implementation is an effort to protect Lake Mead from critically low elevations that is separate from the immediate action now being taken to reserve more water in Lake Powell.
Arizona – stronger together
We are proud of the work we have been doing in Arizona and the contributions to protect the system that have come together in our state. When you account for the mandatory reductions already taken as part of the first-ever Tier 1 shortage and the voluntary compensated conservation that’s part of the 500+ Plan, Arizonans’ Colorado River water use has been reduced by more than 700,000 acre feet – one-fourth of our state’s Colorado River apportionment and more than 40% of CAP’s supply – in 2022. Arizona water users and interested parties are already working on the plan for 2023, and this will take more broad-based collaboration and collective action to meet the water volumes that will be required.
Conservation is a must
While this situation is serious and parties are coming together in our state, it’s important to note that supplies to homes and businesses do not face a threat in 2023, but the outlook for Arizona’s Colorado Supply certainly warrants additional actions. Everyone will be asked to conserve. Conservation may delay or reduce further mandatory reductions. We will be reinforcing, renewing and strengthening the strong conservation ethic that has served Arizona well for decades as we continue to work together to find innovative and effective solutions to conserve water.