Publications

Carboxylated microspheres were employed as surrogates to assess the transport potential of Cryptosporidium parvumoocysts during forced- and natural-gradient tests conducted in July and October 2004. The tests involved poorly-sorted, near-surface sediments where groundwater is pumped from an alluvial aquifer underlying the Russian River, Sonoma County, CA. In an off channel infiltration...

Assessment of the composition, reactivity, and potential health effects of dissolved organic matter (DOM) is an important issue in the regulation and operation of groundwater recharge projects. The composition of DOM in various natural surface waters and reclaimed waters used to recharge the alluvial aquifers of the lower Santa Ana River Basin in California was derived primarily from...

Coupled measurements of nitrate (NO3−), nitrogen (N), and oxygen (O) isotopic composition (δ15NNO3 and δ18ONO3) were made in surface waters of Monterey Bay to investigate multiple N cycling processes occurring within surface waters. Profiles collected throughout the year at three sites exhibit a wide range of values, suggesting simultaneous and variable influence of both phytoplankton...

No abstract available.

The San Bernardino area of southern California has complex water-management issues. As an aid to local water managers, this report provides an integrated analysis of the surface-water and ground-water systems, documents ground-water flow and constrained optimization models, and provides seven examples using the models to better understand and manage water resources of the area. As an aid...

Ground water with arsenic concentrations greater than the U.S. Environmental Protection Agency drinking water standard exists throughout much of the CALFED solution area. These high concentrations are of con-cern from the standpoint of both existing water supply and development of conjunctive use projects. Much is known about arsenic mobility in ground water subject to different...

A series of storms beginning before Christmas 2005 and ending after New Year’s Day 2006 produced significant runoff over much of northern California. The storms resulted in an estimated $300 million in damages and Federal disaster declarations in 10 counties. Several precipitation stations in the Sierra Nevada had precipitation totals greater than 20 inches for the period December 24...

The U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program is designed to assess current water-quality conditions, changes in water quality over time, and the effects of natural and human factors on water quality for the Nation's streams and ground-water resources. For streams, one of the most difficult parts of the assessment is to link chemical conditions to effects...

This study of the geohydrology and water chemistry of the Alexander Valley, California, was done to provide an improved scientific basis for addressing emerging water-management issues, including potential increases in water demand and changes in flows in the Russian River. The study tasks included (1) evaluation of existing geohydrological, geophysical, and geochemical data; (2)...

The Sacramento-San Joaquin Delta (Delta) of California is an ecologically rich and hydrologically complex region that receives runoff from nearly one-quarter of the state. Water-quality studies of surface water in the region have found dissolved pesticides in winter storm runoff at concentrations toxic to some aquatic invertebrates. However, scientists have little information on...

The U.S. Geological Survey, Water Resources, in cooperation with Federal, State, and local agencies, obtains a large amount of data pertaining to the ground-water 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...

The Sonoma Valley, located about 30 miles north of San Francisco, is one of several basins in Sonoma County that use a combination of ground water and water delivered from the Russian River for supply. Over the past 30 years, Sonoma Valley has experienced rapid population growth and land-use changes. In particular, there has been a significant increase in irrigated agriculture...