The Regional Aquifer-System Analysis (RASA) Program was started in 1978 following a congressional mandate to develop quantitative appraisals of the major groundwater systems of the United States. The RASA Program represents a systematic effort to study a number of the Nation's most important aquifer systems, which in aggregate underlie much of the country and which represent an important component of the Nation's total water supply. In general, the boundaries of these studies are identified by the hydrologic extent of each system and accordingly transcend the political subdivisions to which investigations have often arbitrarily been limited in the past. The broad objective for each study is to assemble geologic, hydrologic, and geochemical information, to analyze and develop an understanding of the system, and to develop predictive capabilities that will contribute to the effective management of the system. The use of computer simulation is an important element of the RASA studies, both to develop an understanding of the natural, undisturbed hydrologic system and the changes brought about in it by human activities, and to provide a means of predicting the regional effects of future pumping or other stresses. The final interpretive results of the RASA Program are presented in a series of U.S. Geological Survey Professional Papers that describe the geology, hydrology, and geochemistry of each regional aquifer system. Each study within the RASA Program is assigned a single Professional Paper number, and where the volume of interpretive material warrants, separate topical chapters that consider the principal elements of the investigation may be published. The series of RASA interpretive reports begins with Professional Paper 1400 and thereafter will continue in numerical sequence as the interpretive products of subsequent studies become available.

The Regional Aquifer-System Analysis Program The RASA Program represents a systematic effort to study a number of the Nation's most important aquifer systems, which, in aggregate, underlie much of the country and which represent an important component of the Nation's total water supply. In general, the boundaries of these studies are identified by the hydrologic extent of each system and, accordingly, transcend the political subdivisions to which investigations have often arbitrarily been limited in the past. The broad objective for each study is to assemble geologic, hydrologic, and geochemical information, to analyze and develop an understanding of the system, and to develop predictive capabilities that will contribute to the effective management of the system. The use of computer simulation is an important element of the RASA studies to develop an understanding of the natural, undisturbed hydrologic system and the changes brought about in it by human activities and to provide a means of predicting the regional effects of future pumping or other stresses. The final interpretive results of the RASA Program are presented in a series of U.S.

The California Department of Water Resources, through the Future Water Supply Program, is investigating the use of ground-water basins for storage of State Water Project water in order to help meet maximum annual entitlements to water project contractors. This report presents a preliminary evaluation of the geohydrologic factors affecting storage of water by artificial recharge in the upper Coachella Valley, Calif. The ground-water basin of the upper Coachella Valley seems to be geologically suitable for large-scale artificial recharge. A minimum of 900,000 acre-feet of water could probably be stored in the basin without raising basinwide water levels above those that existed in 1945. Preliminary tests indicate that a long-term artificial recharge rate of 5 feet per day may be feasible for spreading grounds in the basin if such factors as sediment and bacterial clogging can be controlled.

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A regional ground-water-quality monitoring network was designed for the entire Salinas River basin by the U.S. Geological Survey. The network is to be implemented by the California State Water Resources Control Board and was designed to meet their needs.The project was carried out in three phases. In phase 1, monitoring networks that exist in the region were identified. In phase 2, information about the wells contained in each network was collected. In phase 3, factors that influence the ground-water quality--such as geology, land use, hydrology and geohydrology--were studied and a regional network was designed. This report is the major product of phase 3.Based on a review of available data, published reports, and discussions of known and potential ground-water-quality problems with local officials, an ideal ground-water-quality monitoring network was designed without regard to costs or existing monitoring. This network was then used as a guide in the design of the proposed network which utilizes existing wells and ongoing monitoring efforts. Because pumpage is higher in the basin's unconsolidated sediments than in the consolidated ones, the network is concentrated in the unconsolidated sediment. In areas where network wells are not available, new wells are proposed for addition to local networks. The proposed network is composed of 325 wells and 8 stream-gaging stations.The data collected by this network will be used to assess the groundwater quality of the entire Salinas River basin. Previously, ground-water quality had only been considered locally or on a countywide basis. After 2 years of data are collected, the network will be evaluated to test whether it is meeting the network objectives. Subsequent network evaluations will be done every 5 years.