Status and Understanding of Groundwater Quality in the Northern San Joaquin Basin, 2005: California GAMA Priority Basin Project

摘要

Groundwater quality in the 2,079 square mile Northern San Joaquin Basin (Northern San Joaquin) study unit was investigated from December 2004 through February 2005 as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The GAMA Priority Basin Project was developed in response to the Groundwater Quality Monitoring Act of 2001 that was passed by the State of California and is being conducted by the California State Water Resources Control Board in collaboration with the U.S. Geological Survey and the Lawrence Livermore National Laboratory. The GAMA Priority Basins Project is comprised of three types of water-quality assessments in each study unit-(1) Status: assessment of the current quality of the groundwater resource, (2) Understanding: identification of the natural and human factors affecting groundwater quality, and (3) Trends: detection of changes in groundwater quality. The purpose of the GAMA status assessments is to provide a statistically robust characterization of raw (untreated) groundwater quality in the part of the aquifer system used for drinking-water supply. The statistically robust design also allows for comparison between basins and for synthesis of results at regional and statewide scales. The purpose of this report is to present results of the status and understanding assessments done in the Northern San Joaquin Basin study unit. This report is one in a series of published and planned USGS Scientific Investigation Reports presenting the status and understanding of current water-quality conditions in GAMA study units.