LAS VEGAS (KLAS) — Big swings in water levels at Lake Mead aren’t expected to repeat over the next two years, according to projections released Friday by the U.S. Bureau of Reclamation.

For now, projections that are updated each month in Reclamation’s 24-month study aren’t changing much. Lake Mead is expected to hit a low of 1,059.83 feet in November 2024, just 5 feet lower than its current level, 1,064.81 feet at noon on Friday. Those are measures of the lake surface’s altitude — the number of feet above sea level.

From there, Lake Mead will climb to 1,066.08 feet in February 2025, and then drop to 1,052.62 feet by July 2025. Projections show the lake reaching 1,067.11 feet — the highest level in the 24-month forecast — in March 2026.

How reliable are the projections?

The projections aren’t always accurate. They just show the range of possibilities based on the best models available. Projections made a year ago missed the mark at Lake Mead by 9 feet.

The “most probable inflow” numbers are used in generating the report each month. Alternate reports chart “minimum probable” and “maximum probable” data. This month’s report is remarkably similar to projections released in May.

The 24-month study released in May 2023 projected Lake Mead to be 1,058.20 feet in May 2024. But it actually hit 1,067.08 feet, according to the Bureau’s records. Looking ahead a year to May 2025, last year’s report is in line with the study released on Friday: 1,056.01 feet (2023 projection) and 1,057.11 (2024 projection).

For Lake Powell, the most probable numbers were quite a bit more out of whack.

Last year’s 24-month study had Lake Powell hitting 3,586.94 feet in May 2024. It was actually about 18 feet lower, at 3,568.69 feet. Looking ahead to May 2025, the 2023 projection expects Lake Powell to reach 3,592.95 feet. The current projection is 3,575.17.

If it seems like there’s something wrong with the math, remember that Reclamation controls how much water comes out through each dam on the Colorado River. After water dropped almost low enough to disrupt power production at Glen Canyon Dam in recent years, Reclamation has made it a priority to keep enough water upstream to prevent Lake Powell from dropping that low again.

Nevada, Arizona and California have proposed a major change in how the federal government makes decisions related to water allocations. Those states want the total water content in the Colorado River Basin to guide the decisions, not just the surface levels of Lake Powell and Lake Mead — which can be manipulated by Reclamation.

A strong finish to winter

Snowpack isn’t usually an interesting topic in early June, but sometimes Mother Nature saves the best news for last. Late-season weather gave a little boost to snow water equivalent (SWE) measurements, especially in the Colorado River Headwaters region of the area that feeds the river that supplies 40 million people with the water they need.

In early April — typically the peak for SWE levels — Bureau statistics showed the Upper Colorado River Basin at around 111% of normal. Two months ago, that was welcome news.

And it’s gotten better since then. On June 6, SWE levels were at 179% of the median level over the past 10 years. On Friday, that had dropped to 132% (blue box at the center of the map above).

At the end of April, when snowmelt is usually happening at a fast and furious pace, SWE levels took an uncharacteristic turn for the better (bright blue line in the chart below):

Granted, the peak level in early April makes the most difference. But for a couple of weeks in late May to early June, the basin had a better water year than a year ago (red line in the chart above). The winter of 2023 helped Lake Mead and Lake Powell recover after an a dry 2021-22.

The years 2019 and 2023 stand out as the best water years over the past decade.