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Published August 22, 2012
Arizona Reservoir Levels(data through 7/31/12)
Data Source(s): National Water and Climate Center
Combined storage in Lakes Mead and Powell stands at 55 percent of capacity, a decrease of 607,000 acre-feet during the last month (Figure 6). Total reservoir storage in the Colorado River Basin is at 59 percent of capacity. San Carlos Reservoir storage continued to decline in July, and only contains about 1,600 acre-feet. Also, combined storage in the Salt and Verde river basin systems is at 56 percent of capacity, which is about 19 percent less than it was one year ago.
In water news, a federal appeals court rejected a bid by the Grand Canyon Trust to annually assess how the operation of the Glen Canyon Dam affects the humpback chub, an endangered Colorado River fish (Capitol Media Services, August 14). The three-judge panel found no legal requirement for such an annual review. At issue for the trust is the current policy of operating Glen Canyon Dam releases based on demand for electricity. The trust prefers water releases that mimic the natural flow of the river, saying that would benefit endangered species downstream.
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
- 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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