Lake Mead and Lake Powell are swelling. Here’s what that means for the water supply

LAS VEGAS (KLAS) — Lake Mead will rise 33 feet higher than expected this year because of snowpack levels in the Upper Colorado River Basin, according to estimates released Thursday by the U.S. Bureau of Reclamation.

Snow that will melt and feed the Colorado River is causing major adjustments in government plans to store water in Lake Powell and Lake Mead. Nexstar’s 8NewsNow.com reported on April 12 that water flows have already increased from Lake Powell, a fact confirmed by the U.S. Bureau of Reclamation’s latest 24-month study.

Now the government is revealing plans that include increasing the amount of water released from Lake Powell by 35% this year. The plan to release 7 million acre-feet has been adjusted to 9.5 million acre-feet – a difference of more than 800 billion gallons of water – by the end of the year.

It’s the good news Las Vegas has been waiting for after two decades of watching the bathtub ring at Lake Mead. But to put one good year in perspective, the Bureau of Reclamation said Lake Powell and Lake Mead – the two biggest reservoirs in the country would go from 23% full to 26% full.

Snowpack levels at the beginning of April were around 160% of normal. Water managers regard the start of April as the peak of the snowpack, when spring temperatures begin to melt snow faster than new snow accumulates.

The high snowpack levels are translating to an expected flow in the Colorado River that’s 177% of normal levels.

The Bureau of Reclamation also announced plans for a “high-flow release” later this month, when water will come out of Glen Canyon Dam at a rate of 35,900 cubic feet per second. That will move sediment stored in the river to build up beaches, “which will benefit conditions at Grand Canyon National Park and aid in management of invasive species in the Colorado River,” officials said. 

This winter’s snowpack is promising and provides us the opportunity to help replenish Lakes Mead and Powell in the near-term — but the reality is that drought conditions in the Colorado River Basin have been more than two decades in the making,” Reclamation Commissioner Camille Calimlim Touton said. “Despite this year’s welcomed snow, the Colorado River system remains at risk from the ongoing impacts of the climate crisis.” 

While Lake Mead rises by 33 feet – to an expected 1,068.05 feet this year – Lake Powell will go up by 40 feet to 3,576.50 feet, holding back an extra 2.74 million acre-feet of water from the higher runoff. Lake levels are expressed as the elevation of the lake’s surface compared to sea level.

Lake Mead sat at 1,047.03 feet late this week. The lake typically rises in spring months and begins to drop around July, continuing for the remainder of the year. The extra water from Lake Powell this year could change that pattern.

For the past few years as the megadrought has had its most severe impact on the river, water managers have adjusted releases from Glen Canyon Dam, trying to maintain hydropower production as water levels dropped to their lowest levels since the dam was built and Lake Powell was initially filled. The adjustments meant holding back water that would typically go downstream to Lake Mead.

This year’s snowpack provides a break from “emergency” adjustments to dam operations as the reservoirs finally fill – even if it’s only to 26% capacity.

The Colorado River Compact – a century-old agreement – determines how much water each state is entitled to take as the river flows from its headwaters in the Colorado Rockies all the way to the Gulf of Mexico. Nevada takes only a small share of that water, but the drought cut allocations as the federal government formally declared a water shortage.

None of the announcements on Thursday change the situation with lower allocations for Nevada, Arizona and California.