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Published August 23, 2011
Arizona Reservoir Levels(data through 7/31/11)
Data Source(s): National Water and Climate Center
Combined storage in Lakes Mead and Lake Powell increased by almost 2 million acre-feet during July. As of July 1, Mead and Powell storage was at 61 percent of capacity (Figure 6), which is around 10 percent more than a year ago. On July 30, the elevation of Lake Powell peaked for the water year at 3,660.9 feet, which is 39.1 feet below full capacity. The projected unregulated inflow to Lake Powell for the 2011 water year is 17.0 million acre-feet, or 141 percent of average. Storage in other reservoirs within Arizona’s borders decreased by more than 116,000 acre-feet in July. San Carlos Reservoir, in drought-stricken southeastern Arizona, is at a mere 1 percent of capacity.
The increase in Lake Mead’s level, which is currently about 20 feet higher than it was one year ago, allowed the U.S. National Park Service to reopen several boat-launch ramps along the lake’s National Recreation Area (Las Vegas Review Journal, August 7).
The map gives a representation of current storage levels for reservoirs in Arizona. Reservoir locations are numbered within the blue circles on the map, corresponding to the reservoirs listed in the table. The cup next to each reservoir shows the current storage level (blue fill) as a percent of total capacity. Note that while the size of each cup varies with the size of the reservoir, these are representational and not to scale. Each cup also represents last year’s storage level (dotted line) and the 1971–2000 reservoir average (red line).
The table details more exactly the current capacity level (listed as a percent of maximum storage). Current and maximum storage levels are given in thousands of acre-feet for each reservoir. One acre-foot is the volume of water sufficient to cover an acre of land to a depth of 1 foot (approximately 325,851 gallons). On average, 1 acre-foot of water is enough to meet the demands of 4 people for a year. The last column of the table list an increase or decrease in storage since last month. A line indicates no change.
These data are based on reservoir reports updated monthly by the National Water and Climate Center of the U.S. Department of Agriculture’s Natural Resource Conservation Service (NRCS). For additional information, contact Dino DeSimone, Dino.DeSimone@az.usda.gov.
Portions of the information provided in this figure can be accessed at the NRCS website:
Southwest Climate Outlook Staff
- Michael Crimmins, UA Extension Specialist
- Stephanie Doster, Institute of the Environment Editor
- Gregg Garfin, Founding Editor, Institute of the Environment
- Zack Guido, Managing Editor, CLIMAS Associate Staff Scientist
- Nancy J. Selover, Arizona State Climatologist
- Jessica Dollin, CLIMAS Publications Assistant
- Dave Dubious, New Mexico State Climatologist
Please direct your Southwest Climate Outlook comments and suggestions to Zack Guido.
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