This paper describes a study of groundwater characteristics and groundwater dating in the Kern Water Bank, west of Bakersfield, Calif. The paper also presents the results of developing a calibrated groundwater-flow model for the Kern Water Bank's aquifer. The Kern Water Bank is one of the largest artificial storage and recovery operations in the southwestern United States. This study sheds light on the chemical characteristics of groundwater, on the nature of the recharge water, on the subsequent groundwater movement through the storage aquifer, and on the origin and age of groundwater in the Kern Water Bank. It also produced a calibrated groundwater-flow model that can be used in predicting the effects of future recharge and groundwater extraction operations in the Kern Water Bank aquifer. It was determined that the chemistry of groundwater in the Kern Water Bank is suitable for irrigation following additional purification. Groundwater in the Kern Water Bank originates primarily from western Sierra Nevada runoff and from regional groundwater accretions. Groundwater age shows a clear differentiation into three age ranges. An optimal set of hydrogeologic parameters was identified which, in conjunction with recharge data, boundary-, and initial-condition data, and a hydrogeologically based finite difference grid, were integrated into a groundwater-flow model useful for predicting recharge and stress impacts in the Kern Water Bank. © ASCE 2008.