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 3.3-5.  Figure 3.3-6 shows aquifer flow direction and water-level change between 1990-1991 and 2003-2004.  Figure 3.3-7 contains hydrographs for selected wells shown on Figure 3.3-6.  Figure 3.3-8 shows well yields in four yield categories.  Descriptions of aquifer and 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 Cienega Creek Basin Hydrology.

Major Aquifers

• Refer to Table 3.3-5 and Figure 3.3-6.

• Major aquifers in the basin include recent

• In the central valley the principal aquifer is the basin-fill alluvium.

• From “the Narrows” south of Interstate 10 there are three aquifers: stream alluvium, basin fill and the Pantano formation. The main aquifer in this section is the stream alluvium.

• In the southwestern portion of the basin the main aquifer is the stream alluvium that forms the floodplain of Sonoita Creek and its tributaries. 

• Flow direction south of Sonoita is generally from north to southwest and north of Sonoita it is from the southwest to the northeast.

Well Yields

• Refer to Table 3.3-5 and Figure 3.3-8.
• As shown on Figure 3.3-8 well yields in this basin range from less than 100 gallons per minute (gpm) to 2,000 gpm.
• One source of well yield information, based on 35 reported wells, indicates that the median well yield in this basin is 250 gpm.

Natural Recharge

• Refer to Table 3.3-5.

• Natural recharge estimates range from 8,500 acre-feet per year (AFA) to 25,500 AFA.

Water in Storage

• Refer to Table 3.3-5.
• Storage estimates for this basin range from 5.1 million acre-feet (maf) to 11 maf to a depth of 1,200 feet.   

Water Level

• Refer to Figure 3.3-6. Water levels are shown for wells measured in 2003-2004.
• The Department annually measures 14 index wells in this basin. Hydrographs for two index wells (B and C) and one other well are shown in Figure 3.3-7.  More recent hydrographs of the index wells may be available through the Department's GWSI webpage.
• The deepest recorded water level in 2003-2004 is 207 feet in Sonoita and the shallowest is 21 feet in the vicinity of Elgin.