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Published August 21, 2013
Arizona Reservoir Volumes(data through August 7, 2013 )
Data Source(s): National Water and Climate Center
Combined storage in Lakes Mead and Powell stood at 46.5 percent of capacity as of July 31 (Figure 6), a decrease of 561,000 acre-feet from the previous month and about 10 percent lower than it was one year ago. The water elevation of Lake Powell peaked in mid-June and will continue to decline until spring 2014. Monsoon rainfall gave a small boost to San Carlos Reservoir storage, which increased for the first time in many months. Combined storage in the Salt and Verde river basins decreased by about 45,000 acre-feet and currently stands at 56 percent of capacity, down almost 3 percent from last year, and at about 82 percent of average.
In water-related news, the White Mountain Apache Tribe and the U.S. Department of the Interior signed a water rights agreement on July 30 that guarantees the tribe 23,000 acre-feet per year of water from the Central Arizona Project (Cronkite News, July 30). This ends a long-standing legal dispute and resolves issues related to Phoenix metropolitan water users, who depend on water originating in the Salt River watershed, which flows through the White Mountain Apache Tribe Reservation.
The map gives a representation of current storage 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 (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 (dotted line) and the 1971–2000 reservoir average (red line).
The table details more exactly the current capacity (listed as a percent of maximum storage). Current and maximum storage 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 Resources Conservation Service (NRCS).
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 Dubois, New Mexico State Climatologist
Please direct your Southwest Climate Outlook comments and suggestions to Zack Guido.
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