Significant changes in Lake Mead outlook explained

Greg Haas
·4 min read
2
Significant changes in Lake Mead outlook explained

LAS VEGAS (KLAS) — Updated projections released on Thursday show Lake Mead rising another foot by the end of February and then crashing in April, eventually dropping 20 feet by November.

The U.S. Bureau of Reclamation’s February 24-month study shows Lake Mead hanging onto about 2 feet more water this year than projections showed just a month ago. And the outlook for 2025 is even more positive. The study is updated monthly to summarize expected river flows, and charts reflect the “most probable inflow” based on scientific models.

On Wednesday, Lake Mead’s surface reached 1,075 feet above sea level — a benchmark level used when the federal government formally declared a water shortage in August of 2021. The Lower Colorado River Basin states — Nevada, Arizona and California — remain in a Tier 1 water shortage and Lake Mead is expected to drop below 1,058 feet as August arrives this year.

24mo-Lake-Mead-only-02152024Download

Improvements, and why they are happening

The February report has some significant improvements compared to January’s 24-month study. Snow conditions in the Upper Basin along with recent wet weather produced by atmospheric rivers that drenched Southern California have allowed Reclamation to continue to fill Lake Mead. All the rain in California reduced demand for water from the Colorado River in the state that uses more than any other. Among the changes in the past month:

  • January’s 24-month study projected Lake Mead would drop to 1,054.60 feet in November 2024, but the study released today shows an expected level at 1,056.53 — nearly a 2-foot improvement.

  • By the end of this month, Lake Mead will get to 1,076.14 feet — the highest projected level over the next two years — but in 2025 it will only reach a high of 1,061.39 feet (February 2025). Both levels are higher than January’s projections.

  • A month ago, projections showed Lake Mead at a low of 1,042.82 feet in November 2025, but now the outlook shows the lake’s decline to a low of 1,043.97 sooner — in September 2025. By November 2025, it will rebound to 1,047.68 feet, nearly 5 feet higher than Reclamation projected in January.

  • Runoff feeding Lake Powell is a healthier 95% of average, better than the 84% measured in January.

  • Snow water equivalent (SWE) measures in the Upper Colorado River Basin are currently at 100% of average, down slightly from 102% on Feb. 9. A month ago, SWE was only at 83% of normal.

An unknown is when water saved under conservation agreements with tribes and water agencies — including the biggest user of all, the Imperial Irrigation District in California — will show up in Lake Mead. Some of the water already accumulating now might be part of that savings.

The 24-month study is a document that guides how dams are managed along the Colorado River. It’s unlikely to include incremental updates related to the conservation agreements.

There’s still a water shortage

While February’s projections are positive, Lake Mead continues to be on track for Tier 1 water shortages in 2025 and 2026. Projections could change, and the lake might dip far enough by the end of 2025 to trigger a Tier 2a water shortage, but right now, it is projected to be just above the threshold in December of 2025 (graph below). It is projected to rise about 5 feet above that level in January of 2026. The shortage level determines how much water will be allocated to each state.

The region’s water consumption is far below the government’s thresholds because of a commitment to recycling most of the water that is used indoors.

Nevada is entitled to 279,000 acre-feet of river water under Tier 1 restrictions, and at the end of 2023 it used only 186,621 acre-feet for the entire year, according to Reclamation records.

An acre-foot is enough water to supply two to three households for a year. It’s 325,851 gallons — enough to cover one acre in water a foot deep.

Every inch that Lake Mead rises is the equivalent of about 2 billion gallons of water — enough for 12,000 to 18,000 households. The projected rise by the end of this month — 1 foot –represents about 24 billion gallons — enough for 144,000 to 216,000 households.

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