This investigation determines the optimal design of a collector using seaward groundwater flow in a coastal aquifer. The optimal design is obtained by analyzing the interrelated hydrologic, engineering, and economic aspects of the project. The optimal size of the project determines the pumping rate and the pumping policy, as well as the location of the wells in relation to the coast. The present work identifies a model of the relevant hydrologic relationships in the aquifer, formulates a criterion for economically efficient utilization of the aquifer, estimates the model parameters, and determines an optimal project size given specific numerical values of the parameters.