LAS VEGAS (KLAS) —  Lake Mead has risen more than 3 feet over the past month, and nearly 13 feet since Jan. 1.

The lake, which supplies 90% of the water used in the Las Vegas Valley, is bucking the trend of the past five years. Lake Mead typically drops beginning around April, following a seasonal pattern.

As snow melts upstream in the Upper Colorado River Basin, water is held back in dams all along the way to prepare for higher consumption during the hot summer months. Water eventually reaches Lake Powell before flowing through the Grand Canyon and into Lake Mead.

But this was an exceptionally wet winter — good news for the 40 million people who rely on the river for water.

As a record snowpack continued to grow into early April, it became clear there would be water to help refill Lake Mead and Lake Powell, which had drained to less than a quarter of the amount of water stored when the reservoirs are full.

The past 23 years — a “megadrought” — took a heavy toll on both lakes, with the Lake Mead “bathtub ring” getting bigger every year.

Current lake level

Currently, the level is at 1,057.75 feet after starting the year at 1,044.96 on Jan. 1. The lowpoint was on July 28 last year, when Lake Mead was at 1,040.72 feet. Lake levels are expressed as the elevation of the lake surface above sea level.

Lake Mead has been rising steadily, but might only recover to 26% full by Oct. 1, according to projections earlier this year. The graphic above shows that even a record year for snow has only been enough to erase one year of drought — but that’s just at Lake Mead.

The largest reservoir in the United States, Lake Mead is the gauge that Nevadans — and a lot of people in Arizona and California — use to judge the urgency of the water shortage. But there’s a lot more to the story.

Lake Powell’s importance

What’s happening at Lake Powell — the nation’s second-largest reservoir — shows that the wet winter will make up for more than the last two years of drought. Lake Powell is now about 41% full, up from 22% in early April.

A chart shows Lake Powell has risen about 65 feet since April:

Lake Powell is now at 3,584.67 feet, after a low of 3,519.92 in April.

“Lake Powell’s projected inflow through the end of this water year (Sept. 30, 2023) is just over 14 million acre-feet of water — that’s more than the last three years combined,” according to a U.S. Bureau of Reclamation news release in late May.

If it climbs another 20 feet, it will wipe out losses over the past five years. But that’s not likely. If fact, the recent trend could indicate that the increases have ended.

Runoff slowing down

On July 6, the level dropped by a fraction for the first time since late April.

The spring runoff has officially slowed down, according to a Bureau of Reclamation spokesperson.

“We are now entering what is called the ‘base flow period,’ where inflows plateau and Colorado River Basin reservoirs are not expected to rise again until next spring when runoff begins,” the spokesperson said Tuesday.

“In comparison, on July 3, 2022, Powell hit its water year high at 3,539.84 feet in elevation, 44 feet below this year,” the spokesperson said. “But as we’ve mentioned, one good water year will not fix the decades of drought we’ve experienced, and Powell remains at about 41% of capacity.”

While it’s a long way from Las Vegas, what happens at Lake Powell has everything to do with how much water is in Lake Mead.

People often wonder about how much a heavy Las Vegas rainstorm will help Lake Mead. And the fact is rains in Las Vegas — even floods — are a drop in the bucket. Granted, any water added to the system is a plus. But it’s the decision about how much water to let out of Lake Powell that has by far the biggest effect on Lake Mead.

Last summer, conservationists revealed that there’s a serious problem with that situation. The pipes that take water through Glen Canyon Dam to turbines that produce electricity for the region are not at the bottom of the dam. They are farther up.

That means water managers have prioritized keeping more water back in Lake Powell even as Lake Mead dropped to a record low since it was initially filled.

It’s not just for the electricity. Research presented by the Utah Rivers Council showed that the pipes lower in the dam are not big enough to supply enough water to meet the U.S. government’s contractual obligation to the Lower Basin states — Nevada, Arizona and California.

Water payback

Over the past year, Reclamation has relied on water from dams upstream from Lake Powell to ensure power production continued at Glen Canyon Dam.

The wet winter came just in time to pay that water back.

A look at the current levels of those reservoirs (compared to levels about three months ago):

• Blue Mesa, 91% full (up from 36% full on April 5)
• Flaming Gorge, 90%, (up from 66%)
• Fontenelle 88%, (up from 33% on April 5)
• Morrow Point 94%, (was 94%)
• Navajo 78%, (up from 55%)

Restocking these important reservoirs reestablishes a cushion in case of another extremely dry year.

The decision to hold back water in all these reservoirs affects how much water eventually makes it to Lake Mead.

“The June 24-Month Study projected Lake Powell to be at elevation 3,575.57 feet and Lake Mead to be at elevation 1,066.77 feet at the end of this water year,” according to the Bureau of Reclamation spokesperson. The “water year” runs from Oct. 1 to Sept. 30.