@USBR Announces 2020 #ColoradoRiver Operating Conditions: #LakeMead operations = Normal or ICS Surplus Condition in Calendar Year 2020, #LakePowell operations = Upper Elevation Balancing Tier in Water Year 2020 #DCP #COriver #aridification

Lake Mead. Photo credit: Bureaus of Reclamation

Here’s the release from the Bureau of Reclamation (Patti Aron/Marlon Duke):

The Bureau of Reclamation today released its Colorado River Basin August 2019 24-Month Study, which sets the annual operations for Lake Mead and Lake Powell in 2020. Based on projections in the 24-Month Study, Lake Mead will operate in the Normal or ICS Surplus Condition in Calendar Year 2020 and Lake Powell will operate in the Upper Elevation Balancing Tier in Water Year 2020 (October 1, 2019 through September 30, 2020).

The Upper Basin experienced above average snowpack, and runoff was 145% of average this past spring, raising Lake Powell’s elevation by more than 50 feet since early April. Total Colorado River system storage today is 55% of capacity, up from 49% at this time last year. In addition, critical drought contingency plans adopted by the seven Basin States, federal government and Mexico earlier this year are now in place to reduce risks to the system.

“While we appreciate this year’s above average snowpack, one good year doesn’t mean the drought is over. We must remain vigilant,” said Commissioner Brenda Burman. “I applaud everyone who came together this year to get the drought contingency plans done. The additional actions under the contingency plans will help ensure the reliability of the Colorado River system for the 40 million people dependent upon it.”

The August 2019 24-Month Study projects Lake Mead’s January 1, 2020, elevation to be 1,089.4 feet, about 14 feet above the Lower Basin shortage determination trigger of 1,075 feet. Lake Powell’s January 1, 2020, elevation is projected to be 3,618.6 feet — 81 feet below full. Because Lake Mead is projected to begin the year below the drought contingency plans threshold of 1,090 feet, Arizona, Nevada and Mexico will make water savings contributions to Lake Mead in 2020.

Despite the above average 2019 snowpack, the Colorado River Basin continues to experience its worst 20-year drought on record, dating back to 2000. This 20-year period is also one of the driest in the 1,200-year paleo record. The August 2019 24-Month Study can be found at https://www.usbr.gov/lc/region/g4000/24mo.pdf

DCP’s Tier Zero Begins a New Era from the Central Arizona Project (Chuck Cullom):

Today, the U.S. Bureau of Reclamation issued its August 24-Month Study Report, a two-year outlook projecting water supply and operating conditions in the Lower Colorado River Basin..

The August Report defines, among other things, the operating conditions for Lake Mead for 2020, and includes the recently enacted Lower Basin Drought Contingency Plan (DCP). At the end of 2019, the projected Lake Mead elevation – the measuring stick for whether there is a shortage declaration on the river for 2020 – is just shy of 1090’. And, for the first time, the Lower Colorado River Basin will formally implement reductions outlined in the DCP at the new Tier Zero beginning January 2020.

What does this mean?

In short, it shows that in its first year, DCP is already working.

While the Basin experienced a stellar snowpack year and subsequent phenomenal run-off, because Lake Mead is projected to end 2019 below elevation 1090’, the Lower Basin States (Arizona, California and Nevada) will be in a DCP Tier Zero shortage condition next year. Under Tier Zero, Arizona’s Colorado River supplies will be reduced by 192,000 acre-feet; Nevada’s will be reduced by 8,000 acre-feet; and California takes no reductions. In addition, Mexico will reduce its water use by 41,000 acre-feet, due to Minute 323, an agreement under the 1944 Treaty for water users in both countries. [ed. emphasis mine] Because of Arizona’s Colorado River priority system and agreements amongst water users, the Central Arizona Project (CAP) will take 100% of Arizona’s reductions under Tier Zero. CAP’s supplies will be reduced by 192,000 acre-feet, representing 12% of its normal annual Colorado River water supply. For CAP customers, this means eliminating the water that would have been available for underground storage, banking and replenishment. Water going toward CAP agricultural uses will be reduced by about 15%.

The Tier Zero reduction to CAP, while significant, is largely equivalent to the amount of Colorado River water CAP has been leaving voluntarily in Lake Mead since 2015 as part of our Lake Mead Conservation Program. In essence, CAP and its water users have been planning and preparing for Tier Zero reductions for the past five years. The difference is that those previous contributions were voluntary – now, under DCP, these contributions are mandatory.

Through the DCP, Arizona continues to prepare for a drier future. This year, CAP, along with the Gila River Indian Community and the Colorado River Indian Tribes, is contributing and storing 236,000 acre-feet in Lake Mead. Next year, even with the Tier Zero reductions, these same water users, along with the Mohave Valley Irrigation and Drainage District, will continue to conserve and store additional water in Lake Mead. These efforts are part of Arizona’s plan to implement DCP developed collaboratively by the Arizona water community and legislative leaders. The plan balances the impacts of DCP amongst water users and provides additional protection to the Colorado River system, giving us a road map to follow for the next several years.

Tier zero cuts. Graphic credit: Central Arizona Project

From Arizona Central (Ian James):

Arizona, Nevada and Mexico will be required to take less water from the Colorado River for the first time next year under a set of agreements that aim to keep enough water in Lake Mead to reduce the risk of a crash.

The federal Bureau of Reclamation activated the mandatory reductions in water deliveries on Thursday when it released projections showing that as of Jan. 1, the level of Lake Mead will sit just below a threshold that triggers the cuts.

Arizona and Nevada agreed to leave a portion of their water allotments in the reservoir under a landmark deal with California called the Lower Basin Drought Contingency Plan, which the states’ representatives signed at Hoover Dam in May.

California agreed to contribute water at a lower trigger point if the reservoir continues to fall. And Mexico agreed under a separate accord to start contributing to help prop up Lake Mead, which is now 39 percent full…

Reservoirs were approaching levels last year that would have triggered a shortage and required deeper cuts, but heavy snow across much of the Rocky Mountains this winter boosted runoff and raised reservoir levels. The river’s reservoirs are now at 55% of total capacity, up from 49% at the same time last year.

But Lake Mead is still projected to be just below the threshold of 1,090 feet above sea level at the beginning of next year. That will put the reservoir in a zone called “Tier Zero,” at which the first cuts take effect.

“While we appreciate this year’s above-average snowpack, one good year doesn’t mean the drought is over. We must remain vigilant,” federal Reclamation Commissioner Brenda Burman said in a statement. She applauded the seven states that depend on the river for coming together to finish the set of drought-contingency plans. Burman said the actions laid out under those agreements “will help ensure the reliability of the Colorado River system for the 40 million people dependent upon it.”

Arizona will see a cut of 192,000 acre-feet in water deliveries next year, or 6.9% of its total allotment of 2.8 million acre-feet. Nevada’s share will be reduced by 8,000 acre-feet, while Mexico’s will take 41,000 acre-feet less. That water will remain in Lake Mead, and will only be recovered once the reservoir rises above an elevation of 1,100 feet.

The cuts under the Drought Contingency Plan, or DCP, represent 12% of the total water supply for the Central Arizona Project, which delivers water by canal to Phoenix, Tucson and other areas. Chuck Cullom, manager of Colorado River programs for CAP, said this reduction will mean “eliminating the water that would have been available for underground storage, banking and replenishment,” and cutting CAP deliveries to agriculture by about 15%.

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