Design of a ground-water-quality monitoring network for the Salinas River basin, California

Abstract

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.