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 4.1-6.  Figure 4.1-6 shows aquifer flow direction and water-level change between 1990-1991 and 2003-2004.  Figure 4.1-7 contains hydrographs for selected wells shown on Figure 4.1-6.  Figure 4.1-8 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 Big Sandy Basin click here.

Major Aquifers

• Refer to Table 4.1-6 and Figure 4.1-6.
• Major aquifers in the basin include recent stream alluvium, basin fill and sedimentary rock (R Aquifer).
• This basin contains two sub-basins, Wikieup and Fort Rock.
• Flow direction is generally from the north to the south.

Well Yields

• Refer to Table 4.1-6 and Figure 4.1-8.
• As shown on Figure 4.1-8 well yields in this basin range from less than 100 gallons per minute (gpm) to greater than 2,000 gpm.
• One source of well yield information, based on 87 reported wells, indicates that the median well yield in this basin is 300 gpm.

Natural Recharge

• Refer to Table 4.1-6.
• The estimated natural recharge for this basin is 22,000 acre-feet per year (AFA).

Water in Storage

• Refer to Table 4.1-6.

• Storage estimates range from 9.5 million acre-feet (maf) to 21 maf to a depth of 1,200 feet. 

Water Level

• Refer to Figure 4.1-6. Water levels are shown for wells measured in 2003-2004.
• The Department annually measures 18 index wells in this basin. Hydrographs for four of these wells are shown in Figure 4.1-7.  More recent hydrographs of the index wells may be available through the Department's GWSI webpage.
• The deepest recorded water level in the basin is 488 feet near the northeastern basin boundary and the shallowest is 15 feet south of Wikieup.

Click for Table 4.1-6 Groundwater Data for the Big Sandy Basin