Reclamation publishes updated projections for conditions in the Colorado River System


Lake Mead
NPS photo

Modeling results support drought response planning in the Colorado River Basin

Sept. 27, 2021 – COLORADO RIVER BASIN – The Bureau of Reclamation released updated modeling projections of the main reservoirs within the Colorado River System for the next five years last week. These projections are used by recultivations and water users in the catchment area for future water management planning. The new projections show a persistent increased risk that Lake Powell and Lake Mead will reach critically low altitudes due to the historic drought and low runoff conditions in the Colorado River Basin.

Today’s announcement comes as the government adopts a state-wide approach to drought containment through the interagency working group on drought relief, co-chaired by the Home Office. The working group coordinates with partners throughout the federal government, supports affected communities and develops long-term solutions for climate change.

At Lake Powell, the projections suggest that the power reserve could fall below the minimum power reserve as early as July 2022 if the extremely dry hydrology continues into the next year. After 2022, the likelihood of Lake Powell falling below the minimum performance pool is around 25% to 35%. Elevation 3,525 feet, the target altitude in Lake Powell, has a nearly 90% chance of being reached next year. This target elevation provides a 35-foot buffer that minimizes the risk of dropping below the 3490-foot minimum energy pool and offsets the need to protect the Glen Canyon Dam infrastructure and current operational obligations to the Lower Basin States of Arizona Meet California and Nevada.

“The recent outlook for Lake Powell is worrying” said Wayne Pullan, Reclamation’s Upper Colorado Basin regional director. “This underscores the importance of continuing to work on solutions with the basin states, tribes and other partners.”

After consultation with – and confirmation by – all seven basin states and other partners, Reclamation began in July 2021 as part of the emergency provisions of the Drought Control Agreement (DROA) with additional water supplies from the upper reservoirs of the Flaming Gorge to Lake Powell. Blue Mesa and Navajo. These additional supplies will provide Lake Powell with up to 181,000 acres of water by the end of 2021.

As Upper Basin states continue to work towards developing a drought operations plan that will address potential future additional shipments, previous model assumptions regarding additional or continued DROA releases have been removed to provide a clearer understanding of future risk. The removal of these assumptions contributed most to the increase in risk between the last projections published in June of this year.

For Lake Mead, today’s projections show that the chance that Lake Mead will sink to an altitude of 1,025 feet (the third deficiency trigger) is up to 66% in 2025 and that there is a 22% chance that the reservoir’s height will be drops to 1,000 feet a year.

Reclamation continues to work with all seven states of the Colorado River Basin to address the current conditions in the Colorado River Basin.

“This five-year probability table highlights the need for additional action beyond the 2007 guidelines and the 2019 Drought Contingency Plan to reinforce our efforts to protect Lake Mead, Lake Powell and the Colorado River system as a whole.” said Tom Buschatzke, director of the Arizona Department of Water Resources.

Most of the Colorado River has its source in the Rocky Mountains. The Upper Basin experienced an exceptionally dry spring in 2021, with runoff into Lake Powell from April through July averaging just 26% of the average despite almost average snowfall last winter. The total storage capacity of the Colorado River system is 39% of its capacity today, up from 49% at this point last year.

Today’s press release also includes updated presentations that use additional predictive information to improve the public’s understanding of Reclamation’s future hydrological projections. In line with its commitment to better educate all water users and the public about the hydrological tools available, Reclamation has added extensive information on modeling and projections in the Colorado River system to its website. A new interactive tool also allows users to study projected reservoir conditions under a range of inflow forecasts.

“We are providing detailed information about our models and projections to stimulate further productive discussions about the future of Lake Powell and Lake Mead based on the best available data.” said Jacklynn Gould, Reclamation’s Lower Colorado Basin regional director. “The willingness to take further measures to protect the elevations of these reservoirs remains a priority and focus of reclamation.”

To view the latest projections of the Colorado River system, visit https://www.usbr.gov/lc/region/g4000/riverops/crss-5year-projections.html.
Source: Bureau of Reclamation

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