By James L. Orlando and Kathryn M. Kuivila
U.S. GEOLOGICAL SURVEY
Data Series 120—ONLINE ONLY
Sacramento, California 2005
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Concentrations of organic contaminants were determined in water samples collected at six surface-water sites located along the San Joaquin and Old Rivers during April through June 2001. Water samples were collected, coincident with salmon smolt caging studies conducted by researchers from the Bodega Marine Laboratory at the University of California at Davis to characterize exposure of the salmon smolt to organic contaminants. Sampling occurred prior to, during, and following the implementation of managed streamflow conditions on the San Joaquin and Old Rivers as part of the Vernalis Adaptive Management Plan. Thirteen pesticides were detected in water samples collected during this study, and at least five pesticides were detected in each sample. The total number of pesticide detections varied little between river systems and between sites, but the maximum concentrations of most pesticides occurred in San Joaquin River samples. The total number of pesticides detected varied little over the three time periods. However, during the period of managed streamflow, the fewest number of pesticides were detected at their absolute maximum concentration. Nine wastewater compounds were detected during this study. Suspended-sediment concentrations were similar for the San Joaquin and Old Rivers except during the period of managed streamflow conditions, when suspended-sediment concentration was higher at sites on the San Joaquin River than at sites on the Old River. Values for water parameters (pH, specific conductance, and hardness) were lowest during the period of managed flows.
Abstract
Introduction
Project Design
Purpose and Scope
Acknowledgments
Procedures and Methods
Description of Sampling Sites
Sample Collection
Analysis of Pesticides
Analysis of Wastewater Compounds
Analysis of Suspended-Sediment Concentration and Parameters
Results
Pesticide Concentrations
Wastewater Compounds
Suspended-Sediment Concentrations and Water Parameters
References Cited
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