AQUIFER-BASED GROUND-WATER MANAGEMENT

Abstract - Ground-water management often proceeds without all parties recognizing that they are managing the same aquifer. This has resulted in a fragmented, often ineffective, and sometimes contradictory, non-resource-based approach to ground-water management. Effective ground-water protection and management relies on recognition by state and local governments that there is a common unit of management and therefore common interests in proper management of the resource. It is not logical to attempt to manage a part of an aquifer without sufficient understandings about the entire aquifer. The different local, State and Federal programs that have authority and responsibility for ground-water management should have a common understanding of the nature of the occurrence ground water within their respective areas of jurisdiction. Aquifers and aquifer systems are the natural units of management for ground water just as a stream; lake and watershed are natural units of management for surface water. An aquifer is defined (USGS) as: a geologic formation, group of formations or part of a formation that will yield usable quantities of water to a well or spring. It is obvious from this definition that most geologic formations will function as an aquifer, at least over part of its' occurrence. Aquifers have mappable boundaries that are delineated based on geologic features (formation boundaries), hydrologic features (flow system divides) and water quality. Aquifers have hydrologic characteristics/properties that are routinely assessed by standardized methods. Under non-perturbed conditions the total annual recharge to an aquifer is balanced by the total annual discharge from the aquifer. Within an aquifer there are aquifer zones, which can be defined as sub-divisions of aquifers with differing hydrologic conditions. Aquifer zones include recharge and discharge areas and confined vs. unconfined areas. Aquifer zones are ecologically important in identifying ground-water interactions with surface water systems, including wetlands. The USGS and State Geological Surveys have mapped and assessed hundreds of aquifers and aquifer systems in the US.