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Published May 23, 2012
Arizona Reservoir Levels(data through 4/30/12)
Data Source(s): National Water and Climate Center
Most of the reservoirs in Arizona are well below their historical average. Combined storage in Lakes Mead and Powell decreased by more than 500,000 acre-feet in April but is still about 10 percent greater than it was one year ago as a result of the copious winter snow in 2010–2011. The projected water year inflow to Lake Powell is 5.57 million acre-feet (MAF). If this holds true, inflow will rank as the fourth lowest on record since the closure of the Glen Canyon Dam in 1963. Precipitation in coming months could increase or decrease actual inflow, with the likely range falling between 4.9 MAF (45 percent of average) and 6.5 MAF (60 percent of average).
The Salt River Basin system, which supplies water to Phoenix, decreased by about 25,600 acre-feet in April and is about 4 percent above average for this time of year (Figure 6). Storage in the San Carlos Reservoir is at about 2 percent of capacity and is at its lowest level for this time of year since at least 1997, reflecting very low precipitation in southeastern Arizona during two consecutive La Niña winters.
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).
Portions of the information provided in this figure can be accessed at the NRCS website:
Southwest Climate Outlook Staff
- Michael Crimmins, UA Extension Specialist
- Stephanie Doster, Institute of the Environment Editor
- Gregg Garfin, Founding Editor, Institute of the Environment
- Zack Guido, Managing Editor, CLIMAS Associate Staff Scientist
- Nancy J. Selover, Arizona State Climatologist
- Jessica Dollin, CLIMAS Publications Assistant
- Dave Dubois, New Mexico State Climatologist
Please direct your Southwest Climate Outlook comments and suggestions to Zack Guido.
The CLIMAS Web site contains official and non-official forecasts, as well as other information. While we make every effort to verify this information, please understand that we do not warrant the accuracy of any of these materials.... Read full disclaimer