Over the last 26 days, Lake Mead has risen 2 feet 8 inches. Before that, for six months, Lake Mead’s water level had been on a steep downward trajectory.
By the numbers, Lake Mead has risen each of the last 26 days by .8 inches a day on average. In total to date, this is 32.88 inches. As of Aug, 22 Lake Mead’s water level was 1,043.45 feet above sea level. It reached a low of 1,040.71 feet on July 27.
According to the Bureau of Reclamation, to raise the lake’s water level one inch, at its current depth, it takes approximately an additional 68,000 acre-feet of water. An acre-foot is about 326,000 gallons.
This means that approximately 176,800 acre-feet of water have been added to Lake Mead over the last 26 days. Written another way, almost 58 billion gallons of water have been added to the lake.
WHY IS IT RISING?
One of the most common questions when talking about the water level at Lake Mead is speculating why the lake is rising. The prevailing thought is because of the recent monsoonal flow that has brought rain to the area for almost four weeks.
While this has added to the lake level it’s not the only reason according to the Bureau of Reclamation.
“Recent storm events and runoff into the tributaries that enter Lake Mead as well as reduced releases from Hoover – due to a decrease in downstream demand – are the leading cause for the recent increases in Lake Mead’s elevation,” Bureau of Reclamation Public Affairs Officer Michelle Helms told 8 News Now. Helms added that as of Aug. 19 there are no significant changes to operations at Glen Canyon Dam.
So more rain and less demand have led to the increase in Lake Mead’s water level. This, however, is not sustainable since the majority of water in the Colorado River basin – including Lake Mead – comes from melting snow in the Colorado Rockies and the monsoon normally subsides over the next month.
The Department of Interior – which oversees the Bureau of Reclamation – announced new drought restrictions will begin in 2023. The reduction is the second straight year of reductions after the federal government declared a water shortage last August.
Arizona’s allocation will drop by 21%, and California will see no new cuts under drought restrictions because the state has “banked” water. Mexico will lose 7% of its water from the river. The cuts are part of “Tier 2” cuts that were expected as the drought continues.
Nevada’s share of the Colorado River drops to 275,000 acre-feet per year under the Tier 2 cuts. The state used only 242,000 acre-feet last year and is on pace to use about the same this year.
Lake Mead’s water level increase caused by recent rain and decreased downstream demand account for approximately 64% of the total water used by Nevada each year.
The Bureau of Reclamation has asked states that use Colorado River water to formulate plans to cut an additional 2 million to 4 million acre-feet from their allocations – a 15-30% reduction.
The federal government has also decided to keep more water – about 1 million acre-feet – in Lake Powell rather than releasing it downstream to Lake Mead, according to documents released Aug. 16.
The bureau’s 24-month study shows that Lake Mead is headed 26 feet lower a year from now. The lake is currently at 1,042 feet, but forecasts show it dropping to 1,016 at the end of September 2023. Forecasts show it dropping to 1,013 feet by July 2024.
Lake levels are expressed in altitude above sea level — not the depth of the reservoir.
Looking ahead to additional restrictions that might be ahead, the bureau looked at extreme predictions. “Lake Mead could drop below 1,000 feet … as early as the summer of 2024,” according to Daniel Bunk, Deputy Chief of the Boulder Canyon Operations Office of the Bureau of Reclamation. A drop that severe would put the Southwest U.S. on track for Tier 3 restrictions.