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 3.8-6.  Figure 3.8-7 shows aquifer flow direction and water-level change between 1990-1991 and 2003-2004.  Figure 3.8-8 contains hydrographs for selected wells shown on Figure 3.8-7.  Figure 3.8-9 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 Lower San Pedro Basin Hydrology.

Major Aquifers

• Refer to Table 3.8-6 and Figure 3.8-7.

• The major aquifers in the basin are basin fill and recent stream alluvium.

• Artesian conditions exist about five miles north to ten miles south of Mammoth in wells drilled deeper than 500 feet.

• Flow direction is generally from southeast to northwest.

• There are two groundwater sub-basins; Camp Grant Wash and Mammoth.

Well Yields

• Refer to Table 3.8-6 and Figure 3.8-9.

• As shown on Figure 3.8-9 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 181 reported wells, indicates that the median well yield in this basin is 1,000 gpm.

Natural Recharge

• Refer to Table 3.8-6.

• Principal sources of recharge in this basin are mountain-front recharge and streambed infiltration.

• Natural recharge estimates range from 24,000 acre-feet per year (AFA) to 29,000 AFA.

Water in Storage

• Refer to Table 3.8-6. 

• Storage estimates for this basin range from 11 million acre-feet (maf) to more than 27 maf to a depth of 1,200 feet. 

Water Level

• Refer to Figure 3.8-7.  Water levels are shown for wells measured in 2003-2004.
• The Department annually measures 19 index wells in this basin.  Hydrographs for six of these wells are shown in Figure 3.8-8.  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 in 2003-2004 at 503 feet south of Mammoth and the shallowest at 17 feet north of Mammoth.

Click to view Table 3.8-6 Groundwater Conditions in the Lower San Pedro Basin

Click to view Figure 3.8-7 Lower San Pedro Basin Groundwater Conditions

Click to view Figure 3.8-8 Lower San Pedro Basin Hydrographs Showing Depth to Water in Selected Wells

Click to view Figure 3.8-9 Lower San Pedro Basin

Well Yields

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