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Published April 25, 2012

Arizona Reservoir Levels

 (data through 3/31/12)
Data Source(s): National Water and Climate Center

Combined storage in Lakes Mead and Powell decreased by 334,000 acre-feet in March but is still about 12 percent greater than it was one year ago due to copious winter snow in 2010–2011. The Salt River Basin system, which supplies water to the Phoenix metropolitan area, decreased by about 3,000 acre-feet in March and is 72 percent full, about 6 percent above average for this time of year (Figure 6). Reservoirs in the Verde River Basin experienced the largest increase in total storage, rising by 15,000 acre-feet in March, but are still only at 28 percent of capacity. Storage in the San Carlos Reservoir also is very low, at about 3 percent of capacity.

In water-related news, researchers from Arizona and Sonora, Mexico, found increased vulnerability among urban water users throughout the Arizona-Sonora region to climatic changes because of aging or inadequate water-delivery infrastructure, over-allocation of water resources, and the location of poor neighborhoods in flood-prone areas or other areas at risk (UANews.org, April 16).

Arizona Reservoir levels as a percent of capacity
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 Resources Conservation Service (NRCS).

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