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Published March 27, 2013
Arizona Reservoir Volumes(data through 2/28/13)
Data Source(s): National Water and Climate Center
Combined storage in Lakes Mead and Powell stood at about 51 percent of capacity as of February 28, a decrease of 317,000 acre-feet from the previous month (Figure 6) and 9 percent lower than one year ago. Storage in all other Arizona reservoirs reported in Figure 6 increased in February, which is typical for this time of year. However, combined reservoir storage in those reservoirs is about 7.5 percent lower than one year ago. It is likely that decreasing storage on the Colorado River will remain the norm as a result of below-average precipitation, which on average has measured less than 80 percent of average. Outside the Colorado River Basin, total accumulated precipitation through mid-March was close to average in the higher elevations of the Verde River Basin. Despite this, recent warm temperatures have eaten into snowpacks in the Verde Basin and elsewhere and are contributing to forecasts for below-average spring streamflows in all rivers in the Southwest.
In water-related news, a proposed plan to build 7,000 homes in Sierra Vista has caused a dispute over groundwater pumping and water rights near the San Pedro River (The Wall Street Journal, February 15). The U.S. Bureau of Land Management and some landowners and environmental groups argue that pumping will intercept water that is needed to sustain a stretch of the San Pedro.
The map gives a representation of current storage 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 (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 (dotted line) and the 1971–2000 reservoir average (red line).
The table details more exactly the current capacity (listed as a percent of maximum storage). Current and maximum storage 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.
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