LAS VEGAS (KLAS) — A large release of water from Lake Powell began Monday morning, sending water on a two-day journey through the Grand Canyon – where it will help restore sandbars and beaches while moving sediment downriver – to Nevada’s Lake Mead.

Monday’s water release from the Glen Canyon Dam is known as a High Flow Experiment (HFE) by the U.S. Bureau of Reclamation. The National Park Service (NPS) is working with Reclamation to ensure people using the Colorado River in the canyons know a surge of water is on the way.

The last time Reclamation conducted an HFE was in November 2018 and has been doing them sporadically since 1996. Lake Powell, much like Lake Mead, has seen its water level rise and subside over the years, but the last time it was full was the summer of 1983. That summer, Reclamation released more than 100,000 cubic feet per second (cfs) to lower the reservoir and help the downriver canyons.

During the current HFR, Reclamation is allowing 39,500 cfs of water through the dam for 72 hours, through Thursday evening. It will be days before it reaches Lake Mead.

Reclamation has released a detailed map showing when the water surge will reach different points on the Colorado River. It shows the water surge will make it to Pearce Ferry, near where the Colorado River enters Lake Mead, beginning at 5 a.m. Wednesday morning. The surge is expected to peak at 9 a.m. before subsiding back to normal flow between Friday at 5 p.m. and ending around 11 a.m. Saturday.

High flow routing and arrival times at critical monitoring sites in Grand Canyon and downstream of Glen Canyon Dam. (Image: U.S. Bureau of Reclamation)

“The experiment is designed to move accumulated sediment from the Paria River up onto beaches and sandbars in Marble Canyon and eastern Grand Canyon to restore the Colorado River corridor in eastern Grand Canyon National Park,” Reclamation wrote on its website. “Sandbars serve as camping beaches for recreationists, while also supplying sand needed to protect archaeological sites. Currently, high sediment loads and favorable hydrology conditions are present to support this experiment.”

Reclamation also wrote, “The 1992 Grand Canyon Protection Act directs the Secretary of the Interior to manage Glen Canyon Dam in such a way as to ‘protect, mitigate adverse impacts to, and improve the values for which Grand Canyon National Park and Glen Canyon National Recreation Area were established.'”

Sandbar at river mile 45 before (LEFT) & after (RIGHT), the 2012 high-flow. (Photos: U.S. Geological Survey/Willie Taylor)

Lake Mead is now projected to rise 33 feet higher than expected this year because of snowpack levels in the Upper Colorado River Basin, according to Reclamation.

Lake Powell’s water level has risen more than 5 feet over the last 10 days, bringing it higher than this time last year when it was continuing to drop to record lows.

Lake Mead’s water level has also improved, rising more than half a foot in the last 10 days.

While all this water flowing downriver is great news for farmers, boaters, and the 40 million people who rely on Colorado River water, it’s really a drop in the proverbial bucket.

Reclamation says this year’s record snowpack melt from the Colorado Rockies will bring both Lake Powell and Lake Mead from being 23% full to 26% full. It’s going to take more than one good year to refill the Colorado River basin bucket.