The Pearl Harbor groundwater aquifer is the most important source of freshwater supply for the island of Oahu, Hawaii, and the most exploited one in the state. Expanded use of this water must be made with a well-formulated groundwater management plan. Over the last twenty years, numerous groundwater models developed and applied to study flow and salinity transport in the Pearl Harbor aquifer enhanced our understanding of the aquifer. However, most of them are too complicated, and adequate calibration and verification of these models require extensive field data which are not currently available. As a result, these models are not being accepted as effective groundwater management tools. At this time, groundwater management decisions, especially those concerning the aquifer's sustainable yield, are being made using a simple robust analytical model (RAM) developed by John Mink in 1981. In this study RAM is modified by including a salinity transport simulation to make it a more realistic groundwater management tool. The modified model, or RAM2, consists of two submodels: (a) a flow submodel, which takes the form of the original RAM, and (b) a salinity transport submodel, which simulates the transport processes and the evolution of the transition zone in a basal freshwater lens. The mathematical structure of the modified model remains simple, such that it can be solved analytically and can be readily calibrated based on available field data of hydraulic head variations .and salinity profiles. Its usefulness as a viable management tool was demonstrated by applying it in a re-evaluation of the sustainable yield of the Pearl Harbor aquifer.