Tucson AMA Groundwater Conditions

Major aquifers, well yields, estimated natural recharge, number of index wells and date of last water-level sweep are shown in Table 8.5-6.  Figure 8.5-6 shows aquifer flow direction and water-level change between 1994-1995 and 2004-2005 for the entire Tucson AMA.  Figures 8.5-6A-B show depth to water during 2004-2005 and water-level change between 1994-1995 and 2004-2005 for selected wells by sub-basin.  Figure 8.5-7 contains hydrographs for selected wells shown on Figures 8.5-6A-B.  Figure 8.5-8 shows well yields in five yield categories.  Underground Storage Facilities (USF) and Groundwater Savings Facilities (GSF) are shown on Table 8.5-7 with facility name, facility permit number and type, permittee name, permitted acre-feet per year and water source. Locations of USFs and GSFs are shown on Figure 8.5-9.   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 8.5-6 and Figure 8.5-6
• The major aquifers are recent stream alluvium and basin fill including the Fort Lowell Formation and the Tinaja Beds.
• In the Upper Santa Cruz sub-basin groundwater flows from the mountains along the eastern AMA boundary toward the center of the AMA then north-northwest.  In the Avra Valley Sub-basin groundwater flows from south to north. 

Well Yields

• Refer to Table 8.5-6 and Figure 8.5-8
• As shown on Figure 8.5-8, well yields are generally between 100 and 1,000 gallons per minute (gpm). 
• One source of well yield information, based on 1,063 wells, indicates that the median well yield is 520 gpm.

Natural Recharge

• Refer to Table 8.5-6
• Natural recharge in the Tucson AMA is approximately 60,800 acre-feet per year.
• Principal sources of natural recharge are groundwater inflow from the south, infiltration of runoff into stream channels, and mountain front recharge.

Water Level

• Refer to Figure 8.5-6A-B. Water levels are shown for wells measured in 2004-2005.
• The Department annually measures 137 index wells in this AMA.  Hydrographs for nine of these wells are shown on Figure 8.5-7. 
• The deepest water level shown is 633 feet in the vicinity of Three Points in the Avra Valley sub-basin (Figure 8.5-6A), and the shallowest is four feet in the eastern portion of the Upper Santa Cruz sub-basin  (Figure 8.5-7B).

Recharge Sites

• Refer to Table 8.5-7 and Figure 8.5-9.
• There are 10 active USFs and six active GSFs.
• Total permitted storage capacity for USFs is 293,000 acre-feet per year and total permitted storage capacity for GSFs is 82,986. 

Figure 8.5-6 Tucson AMA Groundwater Conditions

Figure 8.5-6A Avra Valley Sub-basin Groundwater Conditions

Figure 8.5-6B Upper Santa Cruz Sub-basin Groundwater Conditions

Figure 8.5-7 Tucson AMA Hydrographs Showing Depth to Water in Selected Wells

Figure 8.5-8 Tucson AMA Well Yields

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