Western Drought

[RedRoxx44]

From Dr. Jeff Masters Wonderblog ( on Weather Underground)

For the first time in history, the U.S. government has ordered that flow of Colorado River water from the 50-year-old Glen Canyon Dam be slashed, due to a water crisis brought about by the region's historic 14-year drought. On Friday, the Federal Bureau of Reclamation--a division of the Department of Interior that manages water and electric power in the West--announced that it would cut water released from Lake Powell's Glen Canyon Dam by 750,000 acre-feet in 2014. An acre-foot is the amount of water that will cover an acre of land one foot deep; 750,000 acre-feet is enough water to supply at least 750,000 homes for one year. The flow reduction will leave the Colorado River 9% below the 8.23 million acre feet that is supposed to be supplied downstream to Lake Mead for use in California, Nevada, Arizona and Mexico under the Colorado River Compact of 1922 and later agreements. "This is the worst 14-year drought period in the last hundred years," said Upper Colorado Regional Director Larry Walkoviak in a Bureau of Reclamation press release.

In the winter of 2005, Lake Powell reached its lowest level since filling, an elevation 150' below full pool. Lake levels recovered some in during 2005 - 2011, but the resurgence of severe to extreme drought conditions have provoked a steep decline in 2012 and 2013, with the lake falling 35' over the past year. As of August 18, 2013, Lake Powell was 109' below full pool (45% of capacity), and was falling at a rate of one foot every six days."


Get ready for higher water prices and stricter conservation ???

[Jim]

https://www.usbr.gov/uc/water/crsp/stud ... ations.pdf

Upper CO basin appears to be tracking just below the Most Probable Inflow scenario. With the heat dome giving AZ and the SW some early heat, snowpack has already started to drop, and it seems unlikely that will change with the forecasts over the next 14 days. It is too early to tell if the 2026 WY snowpack has peaked, but in a few weeks it may become obvious.

[Jim]

https://www.usbr.gov/newsroom/news-release/5282
Update to winter snowpack calls for a most probable inflow to Powell leading to a lake level below 3490' by end of year.

[Jim]

It is Spring today! Also, it looks like it started a few weeks back in the San Juans.

[Jim]

https://www.usbr.gov/uc/water/crsp/stud ... ations.pdf
Update to the graphs for Powell and Mead. 3490 looks to be met at Powell in last 1/4 of the year, maybe by early August.

[chumley]

This is the first winter that Arizona's water managers have utilized new LiDAR mapping technology, combined with satellite and ground-based observations to more accurately account for mountain snowpack and forecast runoff.

Three airborne snow surveys conducted this winter tracked how much water was stored in the basin’s snowpack.

The first flight in January measured about 9.1 thousand acre-feet (TAF) of snow water equivalent. A second survey in February measured 9.5 TAF, showing only modest accumulation during the heart of winter. By the time the third survey flew on March 12, however, the basin held just 0.8 TAF of snow water.

“For the first time, we were able to quantify the changes in Arizona’s snow conditions using airborne observations,” Vivoni said. “Despite near-average conditions early in the season, a snow drought across the western U.S. since late December has limited accumulation. By early March, the Upper Black River Basin was nearly snow-free.”

Traditional snow monitoring relies on a limited number of ground sensors scattered across mountain ranges, each measuring snow conditions at a single location. In Arizona’s rugged, forested terrain, snow can vary dramatically from one slope to another, leaving gaps in the picture.

The airborne surveys provide something water managers have never had before in Arizona: a basin-wide snapshot.

This technology does not replace SRP’s measurement tools or SNOTEL, an automated network of remote sensors maintained by the USDA's Natural Resources Conservation Service. These tools remain foundational for snow monitoring. Instead, it will help fill in gaps and strengthen the ability to forecast snowmelt entering the reservoirs, enabling SRP to effectively manage the watershed.

Colorado River supplies remain uncertain amid prolonged drought across the river basin and ongoing negotiations among basin states, while groundwater levels continue to decline. As those pressures grow, the reliability of Arizona’s in-state river systems, including the Salt and Verde rivers, becomes even more important for the Phoenix metropolitan area.

The full story: https://news.asu.edu/20260325-environme ... r-snowpack