Lake Powell, the nation's second-largest reservoir, is approaching critically low water levels, nearing a threshold that could halt hydropower generation and impact water supplies for millions. As of Monday, the reservoir's elevation stood at 3,524.3 feet above sea level.
The minimum elevation required to operate the hydroelectric turbines at Glen Canyon Dam, known as the "dead power pool," is 3,490 feet. Lake Powell is currently about 34 feet above this critical mark. If the water level drops below this point, the turbines can no longer spin, and hydropower production will cease.
Experts are concerned as the reservoir continues to lose water. Since June 1, Lake Powell has been losing approximately 4,800 acre-feet of water per day. "If you do the simple math, it would suggest that Lake Powell will set a record for its lowest point in about a month and a half," said Jack Schmidt, director of the Center for Colorado River Studies at Utah State University.
The reservoir could reach a "dead pool" state if its elevation drops to 3,370 feet, at which point water can no longer flow past Glen Canyon Dam by gravity. At this level, an estimated 240 feet of water would remain trapped at the bottom of the canyon, unable to reach Arizona, California, and Nevada, which rely on it for water.
The current situation is largely attributed to the ongoing megadrought affecting the Western United States and a historically low snowpack in the Colorado River Basin. Much of the basin is experiencing severe to extreme drought conditions, according to the U.S. Drought Monitor.
While some short-term relief may come from above-average precipitation forecasts, monsoon season, and an intensifying El Niño, experts caution that these factors will not offset the long-term effects of the drought and reduced snowpack. "The basin is severely over-allocated," noted Erica Fleishman, director of the Oregon Climate Change Research Institute. Water rights in the Colorado River Basin were established during a period of unusually high water levels in the 20th century.
Since the mid-21st century, runoff in the Colorado River Basin has decreased significantly compared to the mid- to late 20th century. Combined with a series of dry years, the river system has struggled to replenish its storage levels. "During those very dry years, we deplete reservoir storage because society is not able to reduce its use at the same rate that nature reduces its supply," Schmidt explained.
Efforts are underway to establish new operating guidelines for the Colorado River system. Lower basin states have proposed an allocation plan, but consensus among all states, including those in the upper basin, has not yet been reached. If an agreement cannot be negotiated, the Bureau of Reclamation may need to intervene to make a final decision.
"The Department and Reclamation remain committed to reducing the collective risk of both Lake Powell and Lake Mead falling below critical elevations to protect critical infrastructure so that it can continue to function as authorized to meet the water and hydropower needs of the basin," stated Peter Soeth, public affairs lead at the Bureau of Reclamation. The Bureau of Reclamation is scheduled to release an updated projection this week.
Meanwhile, Lake Mead, the largest reservoir in the country, is also experiencing declining water levels. It is currently measuring just over two feet above its record-low level and continues to steadily drop, with projections indicating it could approach its July 2022 record low by the end of this month.