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Published May 26, 2011
Arizona Reservoir Levels(through 4/30/11)
Data Source(s): National Water and Climate Center
During the last month, combined storage in Lakes Mead and Powell increased by 63,000 acre-feet. As of May 1, combined storage was at 47.6 percent of capacity, which is 2.1 percent less than a year ago (Figure 6). However, above-average precipitation and snowpack in the Upper Colorado River Basin are projected to generate 145 percent of average April–July unregulated inflow to Lake Powell by the end of July. Storage in other reservoirs within Arizona’s borders decreased slightly in April, including a decrease of about 56,000 and 20,000 acre-feet in the Verde River Basin and San Carlos Reservoir, respectively.
In water-related news, a water rights settlement between Navajo Nation, the Hopi Tribe, and 30 other entities, including the state, major water providers, and cities and ranchers is threatened due to its high cost and an unfavorable political climate (Associated Press, May 17). The settlement would give Navajo Nation 31,000 acre-feet of water from the Lower Colorado River Basin, plus a portion of flows from the Little Colorado River and groundwater from beneath the reservation.
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.
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
- Dan Ferguson, CLIMAS Program Director
- Gregg Garfin, Founding Editor, Institute of the Environment
- Zack Guido, CLIMAS Associate Staff Scientist
- Gigi Owen, CLIMAS Assistant Staff Scientist
- Nancy J. Selover, Arizona State Climatologist
- Jessica Swetish, CLIMAS Publications Assistant
Please direct your Southwest Climate Outlook comments and suggestions to Zack Guido.
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