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Recent Conditions
Published August 25, 2010

Arizona Reservoir Levels

 (through 7/31/10)
Data Source(s): USDA-NRCS, National Water and Climate Center

Overall storage in the Colorado River Basin as of August 10 was 57.4 percent of capacity, according to the U.S. Bureau of Reclamation. During the last month, storage in both Lake Mead and Lake Powell decreased by about 450,000 acre-feet; Lake Mead is at its lowest level in 54 years. (Figure 6). The combined water storage now hovers around 51.4 percent of capacity, about 2.3 percent less than a year ago. The April through July unregulated inflow to Lake Powell was 5.8 million acre-feet, which was 73 percent of average. Storage in other reservoirs within Arizona’s borders decreased in July by more than 120,000 acre-feet. However, storage in the Salt and Verde river basins is greater than average and greater than they were in July last year.

In water-related news, the Payson Town Council is considering awarding a contract to design a $1.5 million system to put Blue Ridge Reservoir water into the town’s aquifer (Payson Roundup, August 3). This will help offset declines in Payson’s aquifer caused by groundwater pumping.

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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