Problem:  Long term water level records are needed to evaluate the effects of climatic variations on the recharge to and discharge from the groundwater systems, to provide a data base from which to measure the effects of development, to assist in the prediction of future supplies, and to provide data for management of the resource.

Objective: (1) To collect water-level data sufficient to provide a minimum long-term data base so that the general response of the hydrologic system to natural climatic variations and induced stresses is known and potential problems can be defined early enough to allow proper planning and management. (2) To provide a data base against which the short-term records acquired in areal studies can be analyzed. (3) Measure the effect of long-term groundwater withdrawals on land subsidence.

Relevance and Benefits: An important part of the USGS mission is to provide scientific information to manage the water resources of the Nation. To effectively assess the Nation's groundwater resources, the USGS monitors water levels in thousands of wells, determines aquifer characteristics in principal aquifers, and monitors the quality of water in wells and springs using standardized methods. The data are published in annual data reports, reports on specific aquifers, modeling reports, and are made available on the World Wide Web. These data are used in determining long-term trends in water levels by aquifer, sustainable yields by aquifer, climatic effects on water levels, and in development of flow and transport models that allow prediction of future conditions and detection and definition of contaminant and water-supply problems. The data are critical to local, state, and regional water managers for broad-based planning and managing of water-resources projects concerning drought warning and assessment, subsurface water storage, the effects of changing land use, and interstate water-rights agreements. The groundwater data collected in this State are an integral part of the nationwide ground-water data program.

Approach: Evaluation of regional geology allows broad, general definition of aquifer systems and their boundary conditions.  Within this framework and with some knowledge of the stress on the system in time and space and the hydrologic properties of the aquifers a subjective decision can be made on the most advantageous locations for observation of long-term system behavior.  This subjective network can be refined as records become available and detailed areal studies of the groundwater system more closely define the aquifers, their properties, and the stresses to which they are subjected.