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Published December 19, 2011

Arizona Reservoir Levels

 (data through 11/31/11)
Data Source(s): National Water and Climate Center

Combined storage is Lakes Mead and Powell decreased slightly in November by about 100,000 acre-feet. As of November 30, combined storage in both lakes was at 61 percent of capacity (Figure 6), which is about 12 percent more than a year ago. While Lake Powell declined by about 566,000 acre-feet, Lake Mead increased by about 467,000 acre-feet. The discrepancy is because joint management of the two lakes under current conditions sends water from Lake Powell, which was at 69 percent of capacity, to Lake Mead, which was only 53 percent full. Storage in other reservoirs within Arizona’s borders rose by about 47,000 acre-feet in November, driven primarily by increased volume in Lake Mohave. Reservoir storage in the Salt and Verde river basins decreased by 4.7 and 17.7 acre-feet and are at 70 and 28 percent of capacity, respectively. San Carlos Reservoir in drought-stricken southeastern Arizona is about 1 percent full.

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 Resource Conservation Service (NRCS).

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