Major aquifers, well yields, estimated natural recharge, estimated water in storage, number of index wells and date of last water-level sweep are shown in Table 3.7-6.  Figure 3.7-6 shows aquifer flow direction and water-level change between 1990-1991 and 2003-2004.  Figure 3.7-7 contains hydrographs for selected wells shown on Figure 3.7-6.  Figure 3.7-8 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.  For more information on groundwater in the basin see Duncan Valley Basin Hydrology.

Major Aquifers

• Refer to Table 3.7-6 and Figure 3.7-6.

• The major aquifers in the basin are recent stream alluvium, consisting of gravel and sand underlain by clay, and Gila Formation sedimentary rock, consisting of poorly consolidated sand, silt and gravel.

• The principal source of groundwater is the recent stream alluvium.

• Flow direction is generally from the south to the northwest.

Well Yields

• Refer to Table 3.7-6 and Figure 3.7-8.

• As shown on Figure 3.7-8 well yields in this basin range from less than 100 gpm to more than 2,000 gpm.

• One source of well yield information, based on 160 reported wells, indicates that the median well yield in this basin is 850 gpm.

Natural Recharge

• Refer to Table 3.7-6.
• Natural recharge estimates range from 6,000 acre-feet per year to 14,200 acre-feet per year.

Water in Storage

• Refer to Table 3.7-6
• Storage estimates for this basin range from 9.0 million acre-feet (maf) to 19 maf to a depth of 1,200 feet. 

Water Level

• Refer to Figure 3.7-6.  Water levels are shown for wells measured in 2003-2004.
• The Department annually measures 11 index wells in this basin.  Hydrographs for three of these wells are shown in Figure 3.7-7.  More recent hydrographs of the index wells may be available through the Department's GWSI webpage.

• Depth to water varies in this basin, with the deepest recorded water level measured during 2003-2004 at 503 feet at the northwestern basin boundary and the shallowest at 19 feet in the vicinity of Duncan.

• All recorded wells in this basin have declined between 1 and 15 feet between 1990-1991 and 2003-2004.

Click for Table 3.7-6 Groundwater Data for the

Duncan Valley Basin

Click for Figure 3.7-6 Duncan Valley Basin

Groundwater Conditions

Click for Figure 3.7-7 Duncan Valley Basin

Hydrographs Showing Depth to Water

in Selected Wells

Click for Figure 3.7-8 Duncan Valley Basin

Well Yields

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