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Groundwater Conditions in the Lower Gila Basin

Major aquifers, well yields, estimated water in storage, number of index wells and date of last water-level sweep are shown in Table 7.4-6Figure 7.4-6 shows aquifer flow direction and water-level change between 1990-1991 and 2003-2004.  Figure 7.4-7 contains hydrographs for selected wells shown on Figure 7.4-6.  Figure 7.4-8 shows well yields in five yield categories.  A description of aquifer data sources and methods as well as well data sources and methods, including water-level changes and well yields are found in Volume 1, Appendix A. 

Major Aquifers

  • Refer to Table 7.4-6 and Figure 7.4-6
  • The major aquifers are recent stream alluvium and basin fill.
  • Predevelopment flow direction was from the north and southeast edges of the basin to the Gila River and downstream to the southwest.  Extensive agricultural development has created a series of cones of depression including the Hyder Valley cone that pulls water from the Hyder area to the north and a cone east of Dateland.

Well Yields

  • Refer to Table 7.4-6 and Figure 7.4-8
  • As shown on Figure 7.4-8, well yields are generally greater than 1,000 gallons per minute (gpm). 
  • One source of well yield information, based on 597 reported wells, indicates that the median well yield is 1,600 gpm.

Natural Recharge

  • Refer to Table 7.4-6
  • Estimates of natural recharge range from greater than 9,000 acre-feet per year (AFA) to 88,000 AFA.
  • The largest source of natural recharge is runoff in washes and the Gila River floodplain.  In the western portion of the basin, “artificial” recharge from infiltration of irrigation water requires pumping of excess groundwater into drainage canals for removal from the basin. (ADWR 1994b)

Water in Storage

  • Refer to Table 7.4-6
  • Estimates of water in storage range from 100 million acre-feet (maf) to a depth of 1,200 feet to 246 maf to an unknown depth. 

Water Level

  • Refer to Figure 7.4-6. Water levels are shown for wells measured in 2003-2004.
  • The Department annually measures 33 index wells in this basin.  Hydrographs for 10 index wells and one other well (B) are shown on Figure 7.4-7
  • The deepest water level shown on the map is 809 feet in the vicinity of Why and the shallowest is five feet northeast of Wellton.

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Table 7.4-6 Groundwater Data for the Lower Gila Basin

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Figure 7.4-6 Lower Gila Basin Groundwater Conditions

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Figure 7.4-7 Lower Gila Basin Hydrographs Showing Depth to Water in Selected Wells


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Figure 7.4-8 Lower Gila Basin Well Yields


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References and Supplemental Reading for the Lower Gila Basin

Colorado River
Lower Colorado River Planning Area
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Imperial Dam
Welton Mohawk Agriculture