Home » September 2010 Southwest Climate Outlook » Arizona Reservoir Levels
Recent Conditions
Published September 23, 2010

Arizona Reservoir Levels

 (through 8/31/10)
Data Source(s): USDA-NRCS, National Water and Climate Center

Overall storage in the Colorado River Basin as of September 1 was 56.7 percent of capacity. During the last month, storage in both Lakes Mead and Powell decreased to a combined storage of 51.0 percent of capacity (Figure 6), which is about 2 percent less than a year ago. Currently, the water elevation in Lake Mead is only 13 feet above 1,075 feet; when water levels dip below the 1,075-foot elevation, shortage sharing agreements go into effect. However, it’s likely that more water than normal will be released from Lake Powell into Lake Mead during the upcoming water year to temporarily prevent water levels from decreasing below that threshold. Determination of whether this “equalization” strategy will occur depends on the reservoir conditions projected for the end of 2011 water year in the Bureau of Reclamation’s April 2011 24-Month Study.

In other reservoirs within Arizona, storage in the Salt and Verde River basins is greater than average and greater than last year.

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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