Concentrations of Organic Contaminants Detected during Managed Flow Conditions, San Joaquin River and Old River, California, 2001

By James L. Orlando and Kathryn M. Kuivila



Data Series 120—ONLINE ONLY

Sacramento, California 2005

Prepared in cooperation with the
CALFED California Bay-Delta Authority and the
University of California at Davis

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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.




Project Design

Purpose and Scope


Procedures and Methods

Description of Sampling Sites

Sample Collection

Analysis of Pesticides

Analysis of Wastewater Compounds

Analysis of Suspended-Sediment Concentration and Parameters


Pesticide Concentrations

Wastewater Compounds

Suspended-Sediment Concentrations and Water Parameters

References Cited

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