Publications

This report presents surface water and surface (top 0-2 cm) sediment geochemical data collected during 2005-2006, as part of a larger study of mercury (Hg) dynamics in seasonal and permanently flooded wetland habitats within the lower Sacramento River basin, Yolo County, California. The study was conducted in two phases. Phase I represented reconnaissance sampling and included three...

This report presents data on the physical and hydraulic properties of unsaturated alluvial deposits and on the chemical and isotopic composition of water collected at two recharge sites in the western part of the Mojave Desert, near Victorville, California, from 2001 to 2006. Unsaturated-zone monitoring sites were installed adjacent to the two recharge ponds using the ODEX air-hammer and...

Sampling trips were coordinated in the second half of 2008 to examine the interstitial water in the sediment and the overlying bottom waters of three shallow (average depth 2 meters). The water column at all deployment sites was monitored with dataloggers for ancillary water-quality parameters (including dissolved oxygen, salinity, specific conductance, temperature, and pH) to facilitate...

Groundwater quality in the approximately 653-square-mile South Coast Interior Basins (SCI) study unit was investigated from August to December 2008, as part of the Priority Basins Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The GAMA Priority Basins Project was developed in response to Legislative mandates (Supplemental Report of the 1999 Budget Act 1999...

The ability to dynamically simulate the integrated supply-and-demand components of irrigated agricultural is needed to thoroughly understand the interrelation between surface water and groundwater flow in areas where the water-use by vegetation is an important component of the water budget. To meet this need, the computer program Farm Process (FMP1) was updated and refined for use with...

A method for the determination of 14 pyrethroid insecticides in environmental water and sediment samples is described. The method was developed by the U.S. Geological Survey in response to increasing concern over the effects of pyrethroids on aquatic organisms. The pyrethroids included in this method are ones that are applied to many agricultural and urban areas. Filtered water samples...

The purpose of this study was to determine how vertical accretion rates in marshes vary through the millennia. Peat cores were collected in remnant and drained marshes in the Sacramento–San Joaquin Delta of California. Cubic smooth spline regression models were used to construct age–depth models and accretion histories for three remnant marshes. Estimated vertical accretion rates at...

Competition for water resources is growing throughout California, particularly in the Central Valley. Since 1980, the Central Valley's population has nearly doubled to 3.8 million people. It is expected to increase to 6 million by 2020. Statewide population growth, anticipated reductions in Colorado River water deliveries, drought, and the ecological crisis in the Sacramento-San Joaquin...

A tidally averaged sediment-transport model of San Francisco Bay was incorporated into a tidally averaged salinity box model previously developed and calibrated using salinity, a conservative tracer (Uncles and Peterson, 1995; Knowles, 1996). The Bay is represented in the model by 50 segments composed of two layers: one representing the channel (>5-meter depth) and the other the shallows...

The U.S. Geological Survey, Water Resources, in cooperation with Federal, State, and local agencies, obtains a large amount of data pertaining to the groundwater resources of California each water year (October 1-September 30). These data constitute a valuable database for developing an improved understanding of the water resources of the State. This Fact Sheet serves as an index to...

California's Central Valley covers about 20,000 square miles and is one of the most productive agricultural regions in the world. More than 250 different crops are grown in the Central Valley with an estimated value of $17 billion per year. This irrigated agriculture relies heavily on surface-water diversions and groundwater pumpage. Approximately one-sixth of the Nation's irrigated land...

The U.S. Geological Survey (USGS) is the primary Federal agency responsible for scientific evaluation of the natural resources of the United States, including its water. To meet the demands of a growing California, the U.S. Geological Survey's California Water Science Center provides essential science to help Federal, State, and local water agencies evaluate and manage California's...