Lake Mead and Lake Powell water levels have risen, but runoff is slowing

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

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

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

But this has been an exceptionally wet winter, which is good news for the 40 million people who depend on the river for water.

As a record snowpack continued to build into early April, it became clear that there would be water to help replenish Lake Mead and Lake Powell, which had drained to less than a quarter of the amount of water stored when the tanks were full.

Over the past 23 years a mega drought has taken a heavy toll on both lakes, with Lake Mead’s 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 lowest point was on July 28 of 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 is steadily rising but could only recover to 26% by Oct. 1, according to projections earlier this year. The graph above shows that even one record year for snow was enough to erase just one year of drought, but that’s only at Lake Mead.

The largest body of water in the United States, Lake Mead is the gauge that Nevadans and many people in Arizona and California use to judge the urgency of water shortages. But there is much more to the story.

Importance of Lake Powell

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

One graph shows that Lake Powell has risen about 20 meters since April:

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

Lake Powells projected inflow through the end of this water year (September 30, 2023) is just over 14 million acres of water feet, which is more than the past three years combined, according to a Bureau news release. of Reclamation at the end of May.

If it goes up another 20 feet, it will erase the last five years’ losses. But that’s not likely. Indeed, the recent trend may indicate that the hikes are over.

Slowing flow

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

The spring ballot has officially slowed down, according to a spokesperson for the Bureau of Reclamation.

We are now entering what is called the period of base flow, in which the plateau inflows and reservoirs of the Colorado River Basin are not expected to increase again until next spring, when runoff begins, he said Tuesday the spokesman.

By comparison, on July 3, 2022, Powell hit an aquatic year high at 3,539.84 feet high, 44 feet below this year, the spokesperson said. But as we mentioned, a good water year isn’t going to fix the decades of drought we’ve experienced, and Powell’s remains at about 41% capacity.

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

People often wonder how much a heavy Las Vegas thunderstorm could help Lake Mead. And the thing is, it rains in Vegas even floods are a drop in the bucket. Of course, any water added to the system is a plus. But it’s the decision about how much water to get out of Lake Powell that has by far the biggest effect on Lake Mead.

Last summer, environmentalists revealed that there’s a serious problem with that situation. The pipes that carry water through Glen Canyon Dam to the turbines that produce electricity for the region are not located at the bottom of the dam. I’m higher up.

This means that water managers have prioritized keeping more water in Lake Powell even as Lake Mead has dropped to an all-time low since it was initially filled.

It’s not just about electricity. Research presented by the Utah Rivers Council showed that pipes further down the dam are not large enough to deliver enough water to meet US government contractual obligations to the Lower Basin states Nevada, Arizona and California.

Refund of water

For the past year, Reclamation has relied on water from upstream dams at Lake Powell to ensure that power generation continues at Glen Canyon Dam.

The wet winter has arrived just in time to pay off that water.

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

• Blue Mesa, 91% full. (up from 36% full on April 5)
• Burning Throat, 90%(from 66%)
• Fontenella 88%, (compared to 33% on April 5)
• Morrow Point 94%, (was 94%)
• Navajo 78%(from 55%)

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

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

The June 24 study projected Lake Powell to be at an elevation of 3,575.57 feet and Lake Mead at an elevation of 1,066.77 feet at the end of this water year, according to the Bureau of Reclamation spokesperson. The year of water runs from October 1st to September 30th.