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Published December 20, 2012
Arizona Reservoir Levels(data through 11/30/12)
Data Source(s): National Water and Climate Center
Combined storage in Lakes Mead and Powell stood at 52.7 percent of capacity as of November 30, a slight decrease from last month (Figure 1) and 7.9 percent lower than it was one year ago. Declines in reservoir storage during the last year were primarily due to a La Niña event, which helped push storms north of the Upper Colorado River Basin. Storage continued to decrease in the San Carlos Reservoir and the Salt and Verde river basin reservoir systems, which is normal for this time of year. Higher elevation winter snowpacks, , which substantially contribute to Arizona’s water supply, are off to a good start. Several recent storms boosted snowpacks in the White Mountains and other ranges, and water contained in snowpacks measured at snow telemetry sites (SNOTEL) record above-average conditions, with some exceeding 200 percent of average. The first spring streamflow forecasts for Arizona will be issued on January 1 and every two weeks thereafter until April 1; forecasts become progressively more accurate as the winter advances.
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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