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Published September 26, 2012

Arizona Reservoir Levels

 (data through 8/31/12)
Data Source(s): http://www.nmdrought.state.nm.us/MonitoringWorkGroup/wk-monitoring.html

Combined storage in Lakes Mead and Powell is at about 54 percent of capacity, a decrease of 467,000 acre-feet during the last month (Figure 6). While this time of year usually experiences water storage declines, the 2012 April–July period this year recorded the third lowest streamflows since the closure of Glen Canyon Dam in 1963. Due to copious inflow that occurred in spring 2011, storage in the two reservoirs is still greater than it was two years ago when water levels in Lake Mead dipped to within about 15 feet, or about 1.5 million acre-feet, of triggering mandatory conservation measures.

Elsewhere in Arizona, combined storage is about 3 million acre-feet less than it was one year ago. Storage in San Carlos Reservoir slightly increased in August but remains low, at less than 1 percent of capacity as of September 1. Combined storage in the Salt and Verde river basin systems is 57 and 30 percent of capacity, respectively. While the Salt River Basin contains about as much water as it did one year ago, the Verde River Basin decreased by about 400,000 acre-feet.

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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