Extreme heat served to accelerate drought, prompting increased wildfire vigilance and continuing reevaluation of hydroelectric generation capacity across the West.
"[A]bove-normal temperatures persisted across in the northwestern [continental United States], resulting in continued degradations of drought conditions from the Pacific Northwest eastward to central Montana," the U.S. Drought Monitor said in its weekly report covering July 5 through July 13. The heat "has resulted in rapid deteriorations in drought conditions across the Pacific Northwest, northern Great Basin, and Northern Rockies."
Roughly two-thirds of the region is now at the D3 and D4 drought levels, the two most severe rankings in the five-tier system. A year ago, only 3 percent of the region was experiencing the most intense drought level categories, according to Drought Monitor data.
Rain in northwest Montana caused "modest improvements" in the region, which recorded 1-2 inches of rainfall. Likewise, rain across New Mexico, thanks to the robust Southwest monsoon, has created drastic improvements in recent weeks, the Drought Monitor said. There have been several drought level improvements in central and eastern New Mexico where moisture has penetrated to at least 200 cm beneath the surface, according to NASA and ground reports. Shallow groundwater conditions also improved in the state during the report week.
California Gov. Gavin Newsom signed a proclamation on July 8 that expanded the state's drought state of emergency to the nine additional counties of Inyo, Marin, Mono, Monterey, San Luis Obispo, San Mateo, Santa Barbara, Santa Clara and Santa Cruz.
That same day, Newsom signed an executive order requesting that residents voluntarily reduce their water consumption by 15 percent compared to 2020 water use levels. The state estimates this could save as much as 850,000 acre-feet of water over the next year.
"[F]ire concerns remain across the West as a whole," the Drought Monitor said in its weekly report. The number of new wildfires has increased from nearly 40 reported since July 10 to 89 as of July 14.
Hydroelectric generation at U.S. Bureau of Reclamation facilities on the Colorado River also continues dropping as drought reduces the amount of water available for electricity production.
BuRec said that since 2000, Glen Canyon hydropower energy production has declined by about 16 percent and hydropower generation capacity has declined by about 20 percent.
"As reservoir elevations continue to drop with the drought, Glen Canyon annual energy production is projected to decline over the next two to three years by 20 to 25 percent when compared with current levels," according to Amee Andreason, a spokeswoman in BuRec's Upper Colorado Basin Public Affairs Office.
Lake Powell remains at 34 percent of capacity, according to BuRec's July 12 report. The full Lower Colorado River system is now at 41 percent of capacity, with 24,467 thousand acre-feet of water.
Water elevations at Lake Powell are continuing to decrease, which is adversely affecting hydro output, Andreason said. When the lake is full, at 3,700 feet above sea level, the power plant capacity is 1,320 MW. She told Clearing Up via e-mail that on Jan. 1, 2000, the reservoir elevation was 3,681.21 feet, "which corresponds to a power plant capacity of approximately 1,263 megawatts. On December 31, 2020, the reservoir elevation was 3,582.21 feet which corresponds to a power plant capacity of approximately 967 megawatts." This is roughly a 27 percent reduction compared to the full generation potential and a 24 percent drop in generation since 2000.
BuRec is forecasting that there is a 79 percent chance that Lake Powell will fall below 3,525 feet in 2022. That figure is known as its "target water-surface elevation," and includes a 35-foot buffer compared to the minimum power pool elevation, which is 3,490 feet. The buffer is also designed to protect the infrastructure at Glen Canyon as well as help BuRec meet its operational targets for Arizona, California and Nevada.
Beyond 2022, "Lake Powell's chances of falling to critical levels also increased," the agency said in a July 8 news release. "There is a 5 percent chance that Lake Powell will fall below the minimum power pool elevation of 3,490 feet in 2023 and 17 percent in 2024."
Hoover Dam's hydroelectric power plant is currently operating at roughly 75 percent capacity or roughly 1,500 MW, according to Patti Aaron, a spokeswoman for the Bureau of Reclamation.
There is a "high likelihood of a first-ever shortage condition in the Lower [Colorado River] Basin in calendar year 2022," the agency stated in that same July 8 news release. Should Lake Mead fall to or below 1,075 feet, that would trigger the lake to be operated "in a shortage condition in the upcoming year," according to the bureau.
"Reclamation is also concerned with the longer-term projections, which show a higher likelihood of Lake Mead declining to the critical elevations of 1,025 and 1,000 feet by 2025. Based on the June update, the chance of this occurring by 2025 is 58 percent and 21 percent, respectively."
Salt River Project storage is at 71 percent of capacity as of July 15, with roughly 1.4 million acre-feet of water in the system's storage. This is 20 percent less than year-ago levels, when the system was at 91 percent of capacity, according to SRP's daily report.
Almost 60 million people in the Western U.S. now live in drought conditions, according to the Drought Monitor.