Arizona Reservoir Levels

Recent Conditions
Published July 25, 2012

Arizona Reservoir Levels

 (data through 6/30/12)
Data Source(s): National Water and Climate Center

Storage in each of the Arizona reservoirs listed in Figure 6 declined during the last month. Combined storage in Lakes Mead and Powell decreased by 679,000 acre-feet in June. Total reservoir storage in the Colorado River Basin is 60 percent of capacity (rounded to 0 percent in Figure 6, around 5 percent lower than it was at the beginning of the water year. Storage in the San Carlos Reservoir, which completely dried in 1976 and 1977, is at about 0.2 percent of capacity, an extremely low level that reflects scant precipitation in southeastern Arizona for two consecutive La Niña winters. The reservoir is also nearing its lowest capacity in 20 years. Combined storage in the Salt and Verde river basin systems is 59 percent of capacity, which is about 20 percent less than it was one year ago. 

In water-related news, hot and dry conditions have left the Blue Ridge Reservoir, a key to the water security of Rim Country, near Payson, vulnerable to wildfires. Fires, if ignited, would elevate post-wildfire erosion that could greatly reduce storage capacity (Payson Roundup, July 13). Future growth in the region would subsequently be impacted, as it is in part tied to the 14,000 acre-foot capacity reservoir.
 
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 Resources Conservation Service (NRCS).

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