The Bureau of Reclamation has released its October 24-Month Study and two-year projections of major reservoir levels within the Colorado River system. These projections detail hydrologic conditions and projected operations for Colorado River system reservoirs and are used by Reclamation and water users in the basin for future water management planning.
The October projections are the first to include inflow forecasts developed by the National Oceanic and Atmospheric Administration’s (NOAA) Colorado Basin River Forecast Center (CBRFC) that incorporate updated climate conditions and data sets known as the “U.S. Climate Normals.” Compared to the previous period used by the CBRFC to develop the inflow forecasts (1981-2010), the more recent 30-year period (1991-2020) eliminates the wetter hydrology experienced in the 1980s and includes most of the 22-year drought that started in 2000 (and continues to the present). NOAA updates the “Climate Normals” to a new 30-year period every 10 years, consistent with weather and forecasting offices in the U.S.
As a result of this update, the median water year 2022 inflow forecast into Lake Powell decreased by 800,000 acre-feet and Reclamation’s October projections show lower Lake Powell elevations compared to the September projections.
With this decrease in the inflow forecast, Reclamation’s October projections indicate Lake Powell’s elevation at the end of water year 2022 (Sept. 30, 2022) will be about 8 feet lower than the September projections. The projections also indicate the increased potential of falling below minimum power pool, elevation 3,490 feet, in 2022. Should extremely dry hydrology continue into next year, Lake Powell could reach 3,490 feet as early as July 2022.
Lake Powell is impounded by Glen Canyon Dam and provides water for its 1,312-MW hydro powerhouse.
“Incorporating the updated climate normals into the CBRFC forecasts, and, in turn, into our modeling projections, provides us with a better understanding of what is happening now and will give us a more informed assessment of potential future conditions,” said Reclamation’s Upper Colorado Basin Regional Director Wayne Pullan.
At Lake Mead, the October projections indicate Lake Mead will be at elevation 1,050.63 feet at the end of calendar year 2022, less than 1 foot above the Tier 2 shortage elevation threshold of 1,050 feet. Recent analysis indicates about a 16% chance of a Tier 2 shortage condition in 2023.
Lake Mead is impounded by Hoover Dam and provides water for its 2,078-MW hydro powerhouse.
“We have had to make difficult choices this year, and we will all have to make more difficult decisions if it continues to remain dry next year to protect Lake Mead and Lake Powell,” said Reclamation’s Lower Colorado Basin Regional Director Jacklynn Gould.
Most of the flow of the Colorado River originates in the Rocky Mountains. The Upper Basin experienced an exceptionally dry spring in 2021, with April to July runoff into Lake Powell totaling just 26% of average, despite snowpack reaching 89% of median, due to dry soil conditions and above-average temperatures.