Preliminary geologic map of the coastal part of the Point Dume quadrangle, Los Angeles County, California
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During the past few years, the U.S. Geological Survey has installed many different types of instrumentation for the observation and detection of crustal deformation within the San Andreas fault system. In order to have an effective earthquake prediction program, it is important to have continuous data from these instruments collected at a central site. A second prerequisite is to provide adequate coverage throughout the large region of active faulting in this system.
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In April 1986, the U.S. Geological Survey began a pilot program to assess the quality of the nation 's surface water and groundwater resources. This program, called the National Water-Quality Assessment (NAWQA) program, is designed to acquire and interpret information about a wide range of water quality issues. The program is in its early stages and consists of four surface water and three groundwater pilot projects. The objectives of the Carson River basin NAWQA project are described in the context of the national program, the study area and its associated water quality issues, and a proposed study approach. The objectives of the Carson River basin NAWQA project are to: (1) investigate regional groundwater quality; (2) describe relations of groundwater quality to land use, geohydrology, and other pertinent factors; (3) provide a general description of the location, nature and possible causes of selected widespread water quality problems in the project area; and (4) develop new techniques for characterizing regional groundwater quality, especially in arid alluvial basins. There are to be three major phases of the Carson River basin project. The first will consist of compilation and analysis of existing data. The second phase will consist of a regional water quality survey that will produce a consistent set of data that can be used to: (1) define regional quality of groundwater within the Carson River basin; and (2) compare that water quality with other aquifers in the Nation. The third phase will include topical studies that will define groundwater quality in the Carson River basin with respect to certain constituents, either basin wide or within specific areas of concern. (Lantz-PTT)
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The U.S. Geological Survey conducted hydrologic investigations in San Francisco Bay during Water Years 1988, 1989, 1990 and 1991. Dissolved inorganic plant nutrients, nitrate, nitrite, ammonium, silica, and reactive phosphorus were measured in surface and in near-bottom waters at previously established locations in both northern and southern reaches of the bay. Salinity, turbidity, and concentrations of suspended particulate matter also were measured. Additionally, in Water Year 1991, concentrations of dissolved organic nitrogen and phosphorus were measured. From November 1990 through April 1991, surface waters were sampled near the end of the old Dumbarton Bridge (east span). Salinity, dissolved inorganic nutrients, and alkalinity were measured for these samples. This report presents the sampling and analytical methods, and the data for these studies.
The U.S. Geological Survey conducted hydrologic investigations in San Francisco Bay between October 1991 and November 1993. Dissolved inorganic plant nutrients, nitrate, nitrite, ammonium, silica, and reactive phosphorus were measured in surface and in near-bottom waters at previously established locations in both northern and southern reaches of the bay. Salinity, turbidigy, and concentrations of suspended particulate matter also were measured. Additionally, concentratons of dissolved organic nitrogen and phosphorus were occasionally measured. This report presents the sampling and analytical methods, and the data for these studies. Data on the variability due to sampling and sample handling procedures, on the precision of the analytical methods, and on recoveries of known additions from samples are also presented.