From purpose and scope: This report includes a description of the geohydrologic features of the different aquifers; a definition of source, occurrence, movement, and quality of the ground water; and an estimation of the current pumpage and ground-water storage.

Purpose and scope: The U.S. Marine Corps conducts training maneuvers in the study area. Lack of a local source of water has severely limited the utilization of the area. In the past, limited quantities of water have been transported to the area by truck or helicopter. The purpose of this study was to determine the feasibility of obtaining a supply of ground water in the area for use when field maneuvers are being conducted. The major effort for this study was concentrated on the part within the Marine Corps base boundary. The study involved the assessment of ground-water quality, ground water in storage, and aquifer characteristics.

Report and geographical survey. This report examines the distribution of nitrates in the Redland area's ground water and concludes that this distribution depends primarily upon depth below the water table and areal location. Includes several maps and figures.

From purpose and scope: The purpose of this part of the Central Valley Aquifer Project is to gather and analyze all available information on the magnitude and distribution of ground-water pumpage in the Central Valley. These data will be used as input to a digital ground-water model, one of the products of the Central Valley Aquifer Project.

Purpose and scope: The purpose of this study was to develop a method for estimating the amount of subsurface return flow to the Colorado River in the Yuma area. This report presents a method that will permit an accounting of ground-water return flows from each side of the Colorado River in the Yuma reach. The estimates of return flow can be used by water-management agencies in determining return-flow credits for the States of Arizona and California.

From abstract: This report presents the theory and method of calculation used by MIX2, describes the input to the program, presents results of two test cases, and provides a program listing.

From purpose and scope: The purpose of this report, prepared by the U.S. Geological Survey in cooperation with the Napa County Flood Control and Water Conservation District, is to provide local planners with sufficient data to permit them to manage effectively the local ground-water resources for long-term use.

This report presents a historical review of sediment-data collected for the San Francisco Bay systems in California from 1909 to 1966. It includes maps, graphs, tables, and a foreword.

From purpose and scope: This report describes methods for evaluating the magnitude and frequency of floods at gaged and (or) ungaged sites in California. The purpose is to provide a base for the study of floods and the review and extension of flood magnitude-frequency relations by agencies and individuals who are concerned with the management and control of floods, highway construction, and other related work.

From abstract: "This study was made to describe the distribution of inorganic nitrogen and other chemical constituents and nitrogen-using bacteria in the unsaturated zone, to relate nitrogen occurrences, in a general way, to present and historical land use, and to attempt to predict nitrogen concentrations in ground water after recharge" within the Highland-East Highlands area of San Bernardino County, California. It includes maps, graphs, and tables.

This report presents the results of a "multiple-reach method-of-characteristics flow-simulation model" applied to a ten point eight mile portion of the Sacramento River in 1976. It includes a map, graphs, and a table.

From introduction: The goals of this investigation were: (1) To estimate ground-water fluxes for use in predictions of transport of radionuclides; and (2) to study the effects of uncertainty in model parameters on these estimates.

From purpose and scope: The purpose of this study, done in cooperation with the U.S. Bureau of Indian Affairs, was to provide hydrologic information necessary to aid in evaluating the feasibility of developing a water supply for the Twenty-Nine Palms Indian Reservation.

Abstract: Sacramento County expected to begin operation of the Sacramento Regional Wastewater Treatment Plant in 1982. The California State Water Resources Control Board has ruled that the plant will not be allowed to release effluent into the Sacramento River when flow in the river is 4,000 cubic feet per second or less. Depending on tide condition, flows less than 4,000 cubic feet per second may occur either once or twice during each 24-hour 50-minute tide cycle when the daily mean flow is less than about 12,000 cubic feet per second. Daily mean flows less than 12,000 cubic feet per second occur about 28 percent of the time. Riverflow at the plant outfall is monitored by an acoustic streamflow measuring system. Regulation of effluent released from the plant will normally be based on real-time flow data computed by the acoustic system. A graphical method for determining the occurrence and duration of flows of 4,000 cubic feet per second and less was developed as a backup system to be used if a temporary failure in the acoustic system occurs.

From purpose and scope: The purpose of this study is to describe water-quality conditions in Shasta Lake and in major tributaries to the lake. The study involved the collection and interpretation of historical, hydrologic, and water-quality data collected during intensive and routine monitoring efforts.

From purpose and scope: This report describes the effect of land application of effluent from wastewater treatment plants on ground-water quality in the Livermore-Amador Valley. The report focuses on five wastewater application areas contiguous to or near following wastewater treatment plants: Livermore, Pleasanton, Dublin-San Ramon Services District (was Valley Community Services District), Castlewood Corporation, and Veterans Administration Hospital.

The Anza-Terwilliger area consists of about 96 square miles (24-9 square kilometers) in the upper parts of the Santa Margarita River and Coyote Creek drainage basins in Riverside County, Calif., about 90 miles (145 kilometers) southeast of Los Angeles. This report deals with geology, steady state and transient state of ground water, net depletion of ground water, surface-water flow, precipitation, chemistry of water, land and water use, and gravity data for the Anza-Terwilliger area. The data indicate that the rate of ground-water depletion ha's accelerated since 1950. Pumping depressions adjacent to the Cahuilla Indian Reservation have increased the hydraulic gradient and are.causing water beneath the reservation to flow toward these depressions. Total depletion of ground water since 1950 is about 14,000 acre-feet (17.3 cubic hectometers). Chemical analyses indicate that the ground water in local areas contains concentrations of nitrate above that recommended by the Environmental Protection Agency for human consumption.

Abstract: The Mojave Water Agency includes several desert basins where ground water in storage is many times as great as the average annual recharge. The Johnson Valley area was evaluated to find (1) the quantity of ground water in storage, (2) the chemical quality of the ground water, and (3) the potential for storage of recharge water in the unsaturated zone. Johnson Valley contains about 250,000 acre-feet of water in storage, of which about half can be considered recoverable. About 250,000 acre-feet of void space in the unsaturated alluvium is available for storage of imported water, but considerably less than this amount of recharged water could be recovered. The quality of the water in storage is satisfactory for public consumption, although water from some areas has high fluoride concentrations and should be mixed with water of low fluoride concentration.

From purpose and scope: The purpose of this study was to update hydrologic data and refine understanding of the hydrologic system within the San Dieguito, San Elijo, and San Pasqual hydrologic subareas in San Diego County, Calif., and to evaluate the suitability of these areas for reclaimed water use.

From introduction: The primary objective of this study was to determine the net transport of zinc into the study area from urbanized perimeter, out of the study area across the northern boundary of the study area, and across the sediment-water interface within the study area, all within a limited time period. A secondary objective was to assemble as much data on other trace metals--their concentrations and chemical states in water, suspended solids, sediments and interstitial fluids--as possible within the time and funding constraints of the study in order to describe the existing trace metal conditions in the south bay. Thus the bulk of effort was directed toward evaluating the distribution and movements of zinc, but the data collected on the distribution and movements of zinc, but the data collected on the distribution of other metals is important and is reported here.

Purpose and Scope: The purpose of this study was to evaluate the geohydrologic characteristics that influence sustained artificial recharge and to determine long-term infiltration rates in the northern part of Chino ground-water basin. Results of this study will help management to design and implement a recharge-recapture system in Chino Basin. Nine test holes were drilled, long-term infiltration tests were made, and drillers' logs and water-level data were evaluated to determine the probable effects of recharging the ground-water basin. The study was concentrated in the northern part of Chino Basin, where recharge is proposed.

Purpose and scope: The purpose of this study was to develop a method for estimating the amount of subsurface return flow to the Colorado River in the Yuma area. This report presents a method that permits an approximate accounting of ground-water return flow from each side of the Colorado River in Yuma reach. The method presented in this report was developed specifically for application in the Yuma area. The validity of the assumptions inherent in the method was evaluated on the basis of the local hydrologic system. The applicability of the method to other hydrologic systems is not addressed in this report.

From introduction: The purpose of this investigation is to provide the additional geohydologic information needed for Monterey County to develop plans for the optimum utilization of its water resources--particularly in the Prunedale and Aroms areas.

This report examines water quality, levels, and use for groundwater in the Eureka Area, Humboldt County, California. It includes maps, graphs, and other figures.