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Published February 22, 2012
Arizona Reservoir Levels(data through 1/31/12)
Data Source(s): National Water and Climate Center
Lake Powell declined by 311,000 acre-feet in January, while Lake Mead increased by about 125,000 acre-feet. Combined storage in both lakes decreased by 186,000 acre-feet (Figure 6). The discrepancy exists because operation of the reservoirs restores storage to Lake Mead as dictated by rules developed in the landmark 2007 Interim Guidelines on joint operation of the two reservoirs. Despite the decline, combined storage is about 12 percent greater than it was one year ago. Storage in other reservoirs within Arizona’s borders increased by more than 19,000 acre-feet in January. Salt River basin reservoirs, which supply water to the Phoenix metropolitan area, are at a healthy 72 percent of capacity, about 14 percent above their historical average.
In water-related news, business interests from Colorado, Utah, Arizona, New Mexico, and Nevada urged the Department of the Interior and legislators to consider strategies to keep the Colorado River flowing when demand outpaces supply (summitdailynews.com, February 4). More than 800,000 jobs in the West rely on the river.
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 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
- Dan Ferguson, CLIMAS Program Director
- Gregg Garfin, Founding Editor, Institute of the Environment
- Zack Guido, CLIMAS Associate Staff Scientist
- Gigi Owen, CLIMAS Assistant Staff Scientist
- Nancy J. Selover, Arizona State Climatologist
- Jessica Swetish, CLIMAS Publications Assistant
Please direct your Southwest Climate Outlook comments and suggestions to Zack Guido.
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