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Published March 24, 2011

Arizona Reservoir Levels

 (through 2/28/11)
Data Source(s): USDA-NRCS, National Water and Climate Center

Combined storage in Lakes Mead and Powell decreased by 242,000 acre-feet in February. While Lake Mead increased by 352,000 acre-feet, Lake Powell decreased by 594,000 acre-feet. As of March 1, combined storage was at 48.2 percent of capacity, which is 2.4 percent less than a year ago, or about 1.2 million acre-feet (Figure 6). Storage in the Salt and Verde river basins and the San Carlos Reservoir increased slightly, by about 8,500 acre-feet. Total reservoir storage in Arizona is lower than it was one year ago and is down by 84,000 acre-feet from last month.

In water-related news, after years of drought and below-average snowpack in the upper basin of the Colorado River, primarily in Utah, Colorado, and Wyoming, this year’s snowpack is about 120 percent of average, (Arizona Daily Star, February 27). The copious snow may delay shortages of Colorado River water for Arizona water users for several years.

Arizona Reservoir Levels
Notes:

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.

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