Delineating Hydrologically-Based Conjunctive Management Units in Idaho

Idaho has recently promulgated rules requiring the conjunctive management of ground water and surface water resources in areas designated as "Areas Having a Common Ground Water Supply." How many areas the state will eventually designate, and the size, location and makeup of these areas will depend on the numerous criteria (e.g., social, political, economic, management, hydrological, land use, and water use needs). However, these areas should be hydrologically competent; optimally sized and shaped to meet specific management needs and/or goals; and be acceptable to the state, water managers, water users, and the public. The purpose of this paper is to provide an overview of Idaho's criteria for delineating Areas Having a Common Ground Water Supply in Idaho and to recommend additional factors that should be considered during the delineation process.