Comparison of hydraulic conductivity calculated from geophysical logs, aquifer tests, and grain-size distribution at SAWS Aquifer Storage and Recovery Site, Bexar County, Texas

San Antonio Water System (SAWS) operates an Aquifer Storage and Recovery (ASR) facility that is developed within an interval of a 'massive sand' of the Carrizo aquifer on a 3,200 acre site in southern Bexar County, Texas. Spatial variations in hydraulic conductivity reflect heterogeneity in the physical properties of the aquifer that could affect the recharge, movement, storage, and recovery of water at the site. Several independent estimates of hydraulic conductivity at various wells were made from nuclear magnetic resonance (NMR), resistivity, and porosity geophysical logs. Estimates of hydraulic conductivity from well tests and from Kozeny-Carman-equation calculations, which used grain-size-distribution data from partial core recovery, provide a comparison to the geophysical-log interpretations.