Pesticides in Surface Water Measured at Select Sites in the Sacramento River Basin, California, 1996-1998

FIGURES

1. Map showing location of the Sacramento River Basin study unit, California

2. Map showing physiographic provinces of the Sacramento River Basin, California

3. Map showing land uses and land cover of the Sacramento River Basin, California

4. Drainage basin boundary, land uses, and land cover of the Colusa Basin Drain drainage basin
and location of the Colusa Basin Drain at Road 99E near Knights Landing site,
Sacramento River Basin, California

5. Drainage basin boundary, land uses, and land cover of the Arcade Creek drainage basin
and location of the Arcade Creek near Del Paso Heights site, Sacramento River Basin, California

6. Drainage basin boundary, land uses, and land cover of the Sacramento River at Freeport drainage basin and location of the Sacramento River at Freeport site, Sacramento River Basin, California

7. Drainage basin boundary, land uses, and land cover of the Yolo Bypass at Interstate 80 near West
Sacramento drainage basin and location of the Yolo Bypass at Interstate 80 near West Sacramento site,
Sacramento River Basin, California

8. Time series plot of molinate concentrations at the Colusa Basin Drain
at Road 99E near Knights Landing site, Sacramento River Basin, California

9. Time series plot of diazinon concentrations at the Arcade Creek near Del Paso Heights site and the
Colusa Basin Drain at Road 99E near Knights Landing site, Sacramento River Basin, California

TABLES

1. Pesticides analyzed and reporting limits in water samples, in the Sacramento River Basin, California

2. Recoveries and standard deviations of pesticides measured by gas chromatography/mass spectrometry

3. Recoveries and standard deviations of pesticides measured by high performance liquid
chromatography/ultraviolet light spectrometry

4. Maximum, minimum, and median concentrations, and detection frequency of pesticides in water samples
analyzed by gas chromatography/mass spectrometry, in Colusa Basin Drain at Road 99E near Knights Landing, Sacramento River Basin, California

5. Maximum, minimum, and median concentrations, and detection frequency of pesticides in water samples
analyzed by gas chromatography/mass spectrometry, in Arcade Creek near Del Paso Heights,
Sacramento River Basin, California

6. Maximum, minimum, and median concentrations, and detection frequency of pesticides in water samples
analyzed by gas chromatography/mass spectrometry, in Sacramento River at Freeport,
Sacramento River Basin, California

7. Maximum, minimum, and median concentrations, and detection frequency of pesticides in water samples
analyzed by gas chromatography/mass spectrometry, in Yolo Bypass at Interstate 80 near West Sacramento,
Sacramento River Basin, California

8. Maximum, minimum and median concentrations, and detection frequency of pesticides in water samples
analyzed by high performance liquid chromatography/ultraviolet light spectrometry, in Colusa Basin Drain
at Road 99E near Knights Landing, Sacramento River Basin, California

9. Maximum, minimum, and median concentrations, and detection frequency of pesticides in water samples
analyzed by high performance liquid chromatography/ultraviolet light spectrometry, in Arcade Creek
near Del Paso Heights, Sacramento River Basin, California

10. Maximum, minimum, and median concentrations, and detection frequency of pesticides in water samples
analyzed by high performance liquid chromatography/ultraviolet light spectrometry,
in Sacramento River at Freeport, Sacramento River Basin, California

11. Maximum, minimum, and median concentrations, and detection frequency of pesticides in water samples
analyzed by high performance liquid chromatography/ultraviolet light spectrometry,
in Yolo Bypass at Interstate 80 near West Sacramento, Sacramento River Basin, California

CONVERSION FACTORS, VERTICAL DATUM AND ABBREVIATIONS

Multiply	By	To obtain
centimeter (cm)	0.3937	inch
cubic meter (m3)	35.31	Cubic foot
cubic meter per second (m3/s)	35.31	cubic foot per second
kilogram (kg)	2.205	pound (avoirdupois)
meter (m)	3.281	foot
square kilometer (km2)	0.3861	square mile

Vertical Datum

Sea level: In this report, "sea level" refers to the National Geodetic Vertical Datum of 1929--a geodetic datum derived from a general adjustment of the first-order level nets of the United States and Canada, formerly called Sea Level Datum of 1929.

Acronyms

          GC/MS   gas chromatography/mass spectrometry
          GIRAS   Geographic Retrieval and Analysis System
          HPLC    high performance liquid chromatography
          NAWQA   National Water-Quality Assessment
          PERA    probabilistic ecological risk assessment
          TMDL    total maximum daily load
          UVD     untraviolet light detection
          mg/L    microgram per liter

For additional information          Copies of this report can be 
write to:                           purcahsed from:

District Chief                      U.S. Geological Survey
U.S. Geological Survey              Information Service
Placer Hall, Suite 2012             Box 25286
6000 J Street                       Federal Center
Sacramento, CA 95819                Denver, CO 80225

Abstract
Pesticides were measured in one urban stream, one agricultural stream, one site on the Sacramento River, and one large flood control channel over a period of 18 months during 1996-1998. All sites were located within the Sacramento River Basin of California. Measurements were made on 83 pesticides or pesticide transformation products by either gas chromatography/mass spectrometry or by high performance liquid chromatography with ultraviolet light spectrometry. Some pesticides were detected frequently at the agricultural stream and downstream in the Sacramento River and at the flood control channel of the Sacramento River. These were pesticides related to rice farming (molinate, carbofuran, thiobencarb, and bentazon); herbicides used both agriculturally or for roadside maintenance (diuron, simazine, and metolachlor); or insecticides used on orchards and row corps (diazinon and chlorpyrifos). No pesticide concen-trations above enforceable water quality criteria were measured at either the agricultural site or the Sacramento River sites. In contrast to the agricul-tural site, insecticides used for household, lawn, or garden maintenance were the most frequently detected pesticides at the urban site. Diazinon, an organophosphate insecticide, exceeded recom-mended criteria for the protection of aquatic life, and the diazinon levels were frequently above known toxic levels for certain zooplankton species at the urban site. Because of the low discharge of the urban stream, pesticide concentrations were greatly diluted upon mixing with Sacramento River water.