Dissolved Pesticide Concentrations Detected in

Storm-Water Runoff at Selected Sites in the 

San Joaquin River Basin, California, 2000–2001

By James L. Orlando, Kathryn M. Kuivila, and Andrew Whitehead

Prepared in cooperation with the

U.S. ENVIRONMENTAL PROTECTION AGENCY

Sacramento, California

2003

Open-File Report 03-101

U.S. GEOLOGICAL SURVEY
For additional information write to:

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U.S. Geological Survey

Placer Hall, 6000 J Street

Sacramento, California 95819-6129

http://ca.water.usgs.gov

Any use of trade, product, or firm names in this publication is for descriptive purposes only and does 

not imply endorsement by the U.S. Government.

Copies of this report can be purchased from:

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U.S. DEPARTMENT OF THE INTERIOR

GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director
Contents iii

CONTENTS

Abstract ................................................................................................................................................................ 1

Introduction .......................................................................................................................................................... 1

Purpose and Scope ...................................................................................................................................... 2

Acknowledgments....................................................................................................................................... 2

Study Design and Methodology........................................................................................................................... 2

Selection of Sampling Sites ........................................................................................................................ 2

Generalized Sampling Methods .................................................................................................................. 4

Sampling Methods at the Three Sites.......................................................................................................... 4

Vernalis .............................................................................................................................................. 4

Orestimba........................................................................................................................................... 4

Upper Orestima.................................................................................................................................. 7

Sample Processing and Analysis................................................................................................................. 7

Dissolved-Pesticide Concentrations..................................................................................................................... 7

References Cited .................................................................................................................................................. 16
iv Dissolved Pesticide Concentrations Detected in Storm-Water Runoff at Selected Sites in the San Joaquin River Basin, California, 2000–2001

FIGURES

Figure 1. Map showing location of study area and sampling sites in the San Joaquin Valley, California ....... 3

Figure 2. Graphs showing sample collection times for the year 2000, fish caging experiment durations, 

streamflow at the collection site, and rainfall at Modesto, California............................................... 5

Figure 3. Graphs showing sample collection times for the year 2001, fish caging experiment durations, 

streamflow at the collection site, and rainfall at Modesto, California............................................... 6
Tables v

TABLES

Table 1. Pesticide sampling sites, San Joaquin River Basin, California.......................................................... 4

Table 2. Pesticide concentrations in water samples collected at Orestimba Creek at 

Orestimba Creek Road near Newman, California, 2000–2001 ......................................................... 8

Table 3. Pesticide concentrations in water samples collected at Orestimba Creek at River Road near 

Crows Landing, California, 2000–2001 ............................................................................................ 9

Table 4. Pesticide concentrations in water samples collected at San Joaquin River near 

Vernalis, California, 2000–2001........................................................................................................ 13

Table 5. Method detection limits for pesticides analyzed in 2000 and 2001................................................... 15
vi Dissolved Pesticide Concentrations Detected in Storm-Water Runoff at Selected Sites in the San Joaquin River Basin, California, 2000–2001

CONVERSION FACTORS AND SYMBOLS

CONVERSION FACTORS 

Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as follows:

°C=(°F-32)/1.8.

ABBREVIATIONS

BML Bodega Marine Laboratory

GC/MS gas chromatography-mass spectrometry

mL milliliter

ng/L nanogram per liter

USGS U.S. Geological Survey

Multiply By To obtain

kilogram (kg) 2.205 pound avoirdupois

kilometer (km) 0.6214 mile

liter (L) 33.82 ounce, fluid

meter (m) 1.094 yard

square kilometer (km2) 247.1 acre
Introduction 1

Dissolved Pesticide Concentrations Detected in StormWater Runoff at Selected Sites in the San Joaquin River 

Basin, California, 2000–2001

By James L. Orlando, Kathryn M. Kuivila, and Andrew Whitehead

ABSTRACT

As part of a collaborative study involving 

the United States Geological Survey Toxics 

Substances Hydrology Project (Toxics Project) 

and the University of California, Davis, Bodega 

Marine Laboratory (BML), water samples were 

collected at three sites within the San Joaquin 

River Basin of California and analyzed for 

dissolved pesticides. Samples were collected 

during, and immediately after, the first significant 

rainfall (greater than 0.5 inch per day) following 

the local application of dormant spray, 

organophosphate insecticides during the winters of 

2000 and 2001. All samples were collected in 

conjunction with fish-caging experiments 

conducted by BML researchers. Sites included 

two locations potentially affected by runoff of 

agricultural chemicals (San Joaquin River near 

Vernalis, California, and Orestimba Creek at River 

Road near Crows Landing, California, and one 

control site located upstream of pesticide input 

(Orestimba Creek at Orestimba Creek Road near 

Newman, California). During these experiments, 

fish were placed in cages and exposed to storm 

runoff for up to ten days. Following exposure, the 

fish were examined for acetylcholinesterase 

concentrations and overall genetic damage. Water 

samples were collected throughout the rising limb 

of the stream hydrograph at each site for later 

pesticide analysis. Concentrations of selected 

pesticides were measured in filtered water samples 

using solid-phase extraction (SPE) and gas 

chromatography-mass spectrometry (GC/MS) at 

the U.S. Geological Survey organic chemistry 

laboratory in Sacramento, California. Results of 

these analyses are presented.

INTRODUCTION

The land and water resources of California’s San 

Joaquin River Basin help support the nation’s most 

productive agricultural economy. The counties of the 

San Joaquin River Basin produced a variety of crops 

worth over 8.3 billion dollars in the year 2000 

(California Department of Food and Agriculture, 

2001). Important crops that are grown in this region 

include almonds, apricots, cherries, peaches, and 

walnuts. Organophosphates and other types of 

pesticides are applied to these orchards during 

dormancy to control wood-boring insects. Application 

of pesticides during the December–February dormant 

spray season coincides with the region’s peak annual 

rainfall. Previous studies have shown that, for areas 

within the basin, the first significant rainfall and runoff 

following the winter application of organophosphate 

insecticides is accompanied by a rise in the detected 

concentrations of these same pesticides in downstream 

surface waters (Kuivila and Foe, 1995; Kratzer, 1997; 

Dubrovsky and others, 1998). Studies have also shown 

these pesticide pulses to be acutely toxic to certain 

aquatic invertebrates such as Ceriodaphnia dubia (Foe 

and Connor, 1991; Kuivila and Foe, 1995). However, 

little is known concerning the potential effects of these 

pulses on fish.

 In 1999, the U.S. Geological Survey (USGS) 

Toxics Project began a collaborative study with 

researchers from the U.C. Davis Bodega Marine 

Laboratory (BML) that focused on an examination of 
2 Dissolved Pesticide Concentrations Detected in Storm-Water Runoff at Selected Sites in the San Joaquin River Basin, California, 2000–2001

the physical and genetic responses to pesticides of the 

native California fish species, Catastomus occidentalis, 

under both field and laboratory conditions. Field 

experiments exposing C. occidentalis to storm-water 

runoff at three locations in the San Joaquin River Basin 

(fig. 1) were conducted in the winters of 2000 and 

2001. During these experiments, fish were placed in 

cages and exposed to in-stream conditions for periods 

ranging from one to ten days, beginning prior to the 

onset of the first significant rainfall and runoff 

following the local application of dormant spray 

pesticides, and extending through the rising limb of the 

stream hydrograph at each site. Water samples were 

collected throughout the exposure periods for pesticide 

analysis, and laboratory fish-exposure studies. 

Following exposure in the field, fish were dissected and 

samples of blood and tissue were collected and 

analyzed at BML for acetylcholinesterase 

concentrations and overall genetic damage.

Purpose and Scope

As part of this study, the Toxics Project was 

responsible for a number of field and analytical tasks. 

These tasks included the selection of sampling sites, 

initiation of field experiments, collection of water 

samples for lab exposures and water quality analysis, 

and analysis of all water samples for dissolved 

pesticides. This report describes the sampling sites 

chosen and the methods and procedures used during 

water sample collection and analysis. Dissolved 

pesticide concentrations analyzed in water samples 

collected during this study are presented.

Acknowledgments

The authors gratefully acknowledge G. Edward 

Moon, of the USGS Toxics Project as well as other 

USGS personnel for help with sample collection and 

logistical support during this project. The authors also 

wish to acknowledge Jacqueline Houston and Theresa 

Pedersen of the USGS for their many hours of 

laboratory work and pesticide analyses. This project 

was funded by the USGS Toxics Substances Hydrology 

Program and by a grant from the U.S. Environmental 

Protection Agency (R-826603-01-0).

STUDY DESIGN AND METHODOLOGY

Selection of Sampling Sites

Three sites were chosen in the San Joaquin River 

Basin for combined fish exposure studies and pesticide 

analysis (fig. 1; table 1). Sites were selected on the 

basis of local agricultural practices, past and current 

use of organophosphate insecticides, previous surfacewater detections of organophosphate insecticides, 

suitability for fish caging, and safety of field personnel 

during storm conditions. Using these criteria, two sites 

potentially affected by insecticides were chosen: San 

Joaquin River near Vernalis, California (or “Vernalis”), 

and Orestimba Creek at River Road near Crows 

Landing, California (or “Orestimba”). In addition, a 

single control site located upstream of potential 

pesticide input, Orestimba Creek at Orestimba Creek 

Road near Newman, California (or “Upper 

Orestimba”) was chosen (fig. 1). All three sites are 

located in proximity to active USGS gaging stations.

Vernalis is located at the basin outlet of the San 

Joaquin River watershed and receives runoff from 

approximately 19,002 km2 of land in the Sierra 

Nevada, the San Joaquin Valley, and the Coast Ranges. 

Land use at lower elevations is principally agricultural 

and urban, while higher elevations are dominated by 

forest and woodland. This site has a long history of 

water-quality monitoring by numerous state and federal 

agencies. Previous studies have detected diazinon at 

concentrations in excess of 1,000 ng/L in water 

samples collected at this site (Kuivila and Foe, 1995). 

Orestimba is located approximately 1.5 km upstream 

from the confluence of Orestimba Creek and the San 

Joaquin River and represents a watershed of 

approximately 603 km2 in the San Joaquin Valley and 

the Coast Ranges. Land use in the vicinity of this site is 

predominantly agricultural. High concentrations of 

agricultural chemicals have been detected at this site in 

previous years (Panshin and others, 1998). Upper 

Orestimba is located 19 km upstream of Orestimba, at 

the edge of the Coast Ranges. The drainage area above 

this site is approximately 332 km2. Vegetation 

upstream of the sampling site is mostly woodland with 

little or no agriculture.
Study Design and Methodology 3

San Joaquin River

near Vernalis, CA

Modesto raingage

Orestimba Creek at River Road

near Crows Landing, CA

Modesto

San Joaquin River Watershed

Study area

Stanislaus River

San Joaquin River

Orestimba Creek

Tuolumne River

Merced River

0 10 20 5 Kilometers

EXPLANATION

Sampling site

Orestimba Creek

watershed boundary

San Joaquin River

watershed boundary

121301211512145

3745

3730

3715

121

Orestimba Creek at Orestimba Creek Road

near Newman, CA

Figure 1. Location of study area and sampling sites in the San Joaquin Valley, California.
4 Dissolved Pesticide Concentrations Detected in Storm-Water Runoff at Selected Sites in the San Joaquin River Basin, California, 2000–2001

Generalized Sampling Methods 

Field experiments were initiated just prior to the 

first significant rainfall (>0.5 in./day) and runoff 

following the local application of dormant spray 

pesticides in 2000 and 2001. Fish cages were emplaced 

at each of the sites under prestorm streamflow 

conditions and exposed throughout the rising limb of 

the stream hydrograph (figs. 2 and 3). This sequence of 

events was chosen to ensure the exposure to maximum 

concentrations of dissolved pesticides associated with 

initial storm runoff from upstream agriculture. Water 

samples for pesticide analysis and laboratory exposures 

were collected over the same time periods, but under 

varying schedules depending on the hydrologic 

characteristics of the individual watersheds. 

All samples were collected as surface grabs by 

one of three methods. At Vernalis and Orestimba, 

samples were collected from a bridge as mid-channel 

surface grabs or by pumping. At Upper Orestimba, all 

samples were collected as mid-channel grabs or from 

the shore. All water samples were collected in 

proximity to the fish exposure cages at each site and at 

a depth of 0.5 m beneath the water surface. Streamflow 

at each site was likely well mixed, with the exception 

of the Upper Orestimba in 2001. 

Sampling Methods at the Three Sites

Vernalis 

Water samples were collected over a period of 

nine consecutive days (2/11/00–2/19/00) in 2000 

(fig. 2) and seven consecutive days (1/26/01–2/01/01) 

in 2001 (fig. 3). Additional samples were collected 

during the emplacement and removal of individual fish 

cages. Samples were obtained either by pumping 

directly into 1-L amber glass bottles using a peristaltic 

pump equipped with a single stainless steel and Teflon 

inlet hose suspended in mid-channel, or as single midchannel grabs using a weighted 3-L Teflon bottle 

sampler from a bridge.

Orestimba 

In both years, sampling took place in two stages: 

an initial intensive period during which samples were 

collected hourly over approximately 24 hours, followed 

by daily sampling for a period of six consecutive days 

(figs. 2 and 3). Additional samples were collected in 

2001 during the emplacement and removal of 

individual fish cages. During the initial hourly 

sampling, water was collected using a peristaltic pump 

with a single stainless steel and Teflon inlet hose 

suspended in the center of flow. Samples were pumped 

directly into 1-L amber glass bottles. For the 2000 

sampling period, daily water samples were collected 

using a weighted two-bottle sampler, which consisted 

of a 7-kg brass sounding weight modified to hold two 

1-L amber glass bottles. During 2001, daily samples 

were collected using a weighted 3-L Teflon bottle 

sampler and poured directly into 1-L amber glass 

bottles. A series of samples were collected January 

24–27, 2000, in response to a storm that failed to 

produce significant runoff. This storm was considered a 

“false start,” though the pesticide analyses are included 

in this report. A complete sampling and field caging 

was conducted in mid-February following a much 

stronger winter storm.

Table 1. Pesticide sampling sites, San Joaquin River Basin, California

[ID, identification; USGS, U.S. Geological Survey; km, kilometer]

Site name USGS site ID number Latitude Longitude Description

Orestimba Creek at Orestimba Creek 

Road near Newman, California 

(Upper Orestimba)

371912121071201 3719091210715Located 19 km upstream of Orestimba, 

at the edge of the Coast Ranges

Orestimba Creek at River Road near 

Crow’s Landing, California 

(Orestimba)

11274538 3724511210054Located 1.6 km upstream of confluence 

with San Joaquin River

San Joaquin River near Vernalis, 

California (Vernalis)

11303500 3740331211555Basin outlet for the San Joaquin River 

watershed
Study Design and Methodology 5

1,000 Orestimba Creek at Orestimba Creek Road near Newman, CA

1,500

1,000

10,000

15,000

20,000

30,000

25,000

1,500

500

0

500

5,000

0

0

2,000

2,500

3,000

2,000

2,500

3,000

0.0

0.5

1.0

1.5

2.0

2.5

Orestimba Creek at River Road near Crows Landing, CA

Streamflow, in cubic feet per second

Rainfall at Modesto, in inches per day

0.0

0.5

1.0

1.5

2.0

2.5

San Joaquin River near Vernalis, CA

January February

7 10 13 16 19 22 25 28 31 3 6 9 12 15 18 21 24

0.0

0.5

1.0

1.5

2.0

2.5

Fish caging experiment

Rainfall

Pesticide sample

Streamflow

Figure 2. Sample collection times for the year 2000, fish caging experiment durations, streamflow at the collection site, and rainfall at Modesto, California.

Streamflow data collected at USGS site 11274500 Orestimba Creek near Newman, California.
6 Dissolved Pesticide Concentrations Detected in Storm-Water Runoff at Selected Sites in the San Joaquin River Basin, California, 2000–2001

Orestimba Creek at Orestimba Creek Road near Newman, CA

0

100

200

300

400

500 0.0

0.5

1.0

1.5

2.0

2.5

Orestimba Creek at River Road near Crows Landing, CA

Streamflow, in cubic feet per second

0

100

200

300

400

500

Rainfall at Modesto, in inches per day

0.0

0.5

1.0

1.5

2.0

2.5

San Joaquin River near Vernalis

7 10 13 16 19 22 25 28 31 3 6 9 12 15 18 21 24

0

1,000

2,000

3,000

4,000

5,000 0.0

0.5

1.0

1.5

2.0

2.5

Fish caging experiment

Rainfall

Pesticide sample

Streamflow

January February

Figure 3. Sample collection times for the year 2001, fish caging experiment durations, streamflow at the collection site, and rainfall at Modesto, California. 

Streamflow data collected at USGS site 11274500 Orestimba Creek near Newman, California.
Dissolved-Pesticide Concentrations 7

Upper Orestima

As a control, samples were collected at times 

corresponding to the beginning, middle, and end of the 

sampling periods of the other two sites. In 2000, all 

samples were collected at a point near the center of 

flow using a weighted two-bottle sampler. Because of 

very light rainfall in the upper reaches of the watershed 

during the 2001 sampling period, no appreciable 

surface flow occurred at this site. However, samples 

were collected from a large, permanent, in-channel 

pool located approximately 100 m downstream from 

the standard collection site. Samples were collected at 

times corresponding to the emplacement and removal 

of fish cages by submerging 1-L amber glass bottles to 

a depth of 0.5 m for filling. 

Sample Processing and Analysis

Collected water samples were preserved on ice 

and, within 24 hours, filtered through baked, 

0.7 micrometer glass-fiber filters. A surrogate 

compound, terbuthylazine, was added to provide 

quantitative data on extraction efficiency, and the 

samples were then extracted using C8 solid-phase 

extraction cartridges. The cartridges were then dried 

using a syringe to repeatedly force air through each 

cartridge, frozen, and delivered to the USGS organic 

chemistry laboratory in Sacramento, California, where 

they were stored frozen for up to six months. Once 

removed from storage, each cartridge was eluted with 

9 mL ethyl-acetate and analyzed by gas 

chromatography-mass spectrometry (GC/MS). 

Samples collected in 2000 were analyzed for 

26 individual pesticides, whereas in 2001, the total was 

31 pesticides.

Four types of quality-control data were collected: 

field and laboratory equipment blanks, replicate 

samples, matrix spikes, and surrogate recovery. 

Equipment blanks were analyzed every 

20–30 samples for a total of two blanks in 2000 and 

three in 2001. None of the pesticides were detected in 

the blanks. Replicate samples constituted 33 percent of 

the samples analyzed and were within 25 percent 

agreement for each of the pesticides detected. As part 

of the method validation, recoveries of matrix spikes 

were determined in 10 percent of the samples, and 

details are listed in the method reports (Kathryn 

Kuivila and Jacqueline Houston, USGS, Sacramento, 

California, unpub. data, 2002; Theresa Pedersen and 

Kathryn Kuivila, USGS, Sacramento, California, 

unpub. data, 2002). Recovery of the surrogate, 

terbuthylazine, was used to assess the efficiency of 

each extraction. The average percent recovery and 

standard deviation for terbuthylazine was calculated for 

each year. Sample data were excluded if the recovery of 

terbuthylazine was outside the control limit of the 

annual mean plus or minus two standard deviations 

(Kuivila and Houston, unpub. data, 2002; Pedersen and 

Kuivila, unpub. data, 2002).

DISSOLVED-PESTICIDE 

CONCENTRATIONS

This report presents dissolved-pesticide 

concentrations analyzed in water samples collected 

during storms in January–February 2000 and 2001. 

Samples were collected at three surface-water sites in 

conjunction with fish-caging studies (figs. 2 and 3). 

A total of 105 water samples were analyzed for 26 or 

31 pesticides by GC/MS at the U.S. Geological 

Survey’s organic chemistry laboratory in Sacramento, 

California. Results of these analyses are presented in 

tables 2, 3, and 4. Table 5 shows pesticide detection 

limits for the analysis methods used in 2000 and 2001. 

Pesticides that were detected at concentrations below 

the method detection limits listed in table 5 are shown 

in parentheses because the values are estimates.
8 Dissolved Pesticide Concentrations Detected in Storm-Water Runoff at Selected Sites in the San Joaquin River Basin, California, 2000–2001

Table 2. Pesticide concentrations in water samples collected at Orestimba Creek at Orestimba Creek Road near Newman, California, 2000–2001.

[Values are reported as nanograms per liter. Water samples were analyzed for the following pesticides that were not detected at this site: alachlor, atrazine, 

azinphos-methyl, butylate, carbaryl, cyanazine, cycloate, diethatyl-ethyl, eptam, ethalfluralin, fonofos, malathion, methylparathion, napropamide, pebulate, 

pendimethalin, phosmet, sulfotep, and thiobencarb. nd, nondetection; —, not analyzed; ( ), concentration below detection limit]

Date

(mm/dd/yy) Time Carbofuran

Chlorpyrifos Dacthal Diazinon Hexazinone

MethidathionMetolachlorMolinateOxyfluorfen

Piperonyl 

Butoxide

SimazineTrifluralin

Sampling year 2000 

02/12/00 1440 nd nd nd nd — nd nd nd — — nd nd

02/14/00 930 8.6 11.3 7.0 10.7 — 20.1 11.7 nd — — 14.1 16.5

02/14/00 1615 nd nd nd nd — nd nd nd — — nd nd

02/19/00 1050 nd nd nd nd — nd nd nd — — nd nd

Sampling year 2001

01/19/01 1200 nd nd nd nd nd nd nd nd nd nd nd nd

01/26/01 1245 nd nd nd nd nd nd nd 9.4 nd nd nd nd

01/26/01 1745 nd nd nd nd 10.0 nd nd nd nd (2.9) nd nd

01/30/01 1445 nd nd nd nd nd nd nd 14.9 nd nd nd nd

02/04/01 1300 nd nd nd nd nd nd nd nd nd nd nd 17.7

02/05/01 1200 nd nd nd 12.0 17.3 nd nd nd 23.2 16.2 26.1 19.1
Dissolved-Pesticide Concentrations 9

Table 3. Pesticide concentrations in water samples collected at San Joaquin River near Vernalis, 2000–2001—Continued

Date

(mm/dd/yy) Time Atrazine Butylate Carbaryl Chlorpyrifos Cycloate Dacthal Diazinon Diethatylethyl Eptam

Sampling year 2000

01/30/00 1425 nd nd nd nd nd nd 9.7 nd nd

01/30/00 1625 nd nd nd nd nd nd nd nd nd

02/11/00 2335 nd nd nd nd nd nd 24.4 nd nd

02/12/00 135 nd nd nd nd nd 17.2 24.5 nd nd

02/12/00 300 11.4 nd nd nd nd nd 27.7 nd nd

02/12/00 335 nd nd nd nd nd nd 27.6 nd 19.3

02/12/00 630 nd nd nd nd nd 14.3 26.5 nd nd

02/12/00 840 nd nd nd nd nd 15.5 25.1 nd nd

02/12/00 1340 nd nd nd nd nd nd 22.9 nd 16.8

02/13/00 2055 nd nd nd nd nd nd 46.3 nd nd

02/13/00 2130 nd nd nd nd nd 14.2 65.3 nd nd

02/13/00 2320 nd nd nd nd nd nd 252 nd nd

02/14/00 030 nd nd nd nd nd nd 71.4 nd nd

02/14/00 130 nd nd nd nd nd nd 93.2 nd nd

02/14/00 230 nd nd nd 10.9 nd 6.3 61.7 nd nd

02/14/00 650 nd nd nd nd nd 13.9 18.9 nd nd

02/14/00 1100 nd 15.8 nd nd nd nd 12.4 nd nd

02/14/00 1500 nd nd nd nd nd nd nd nd nd

02/15/00 1145 nd nd nd nd nd nd nd nd nd

02/16/00 1200 nd nd nd nd nd nd 13.3 nd nd

02/17/00 615 nd nd nd nd nd nd 14.3 nd nd

02/17/00 1830 nd nd nd nd nd 6.0 nd nd nd

02/18/00 1300 nd nd nd nd nd nd nd nd nd

02/19/00 1000 nd nd nd nd nd nd 14.4 nd nd

Table 3. Pesticide concentrations in water samples collected at Orestimba Creek at River Road near Crows Landing, California, 2000–2001 

[Values are reported as nanograms per liter. Water samples were analyzed for the following pesticides that were not detected at this site: alachlor, azinphosmethyl, carbofuran, cyanazine, fonofos, malathion, methylparathion, napropamide, pebulate, phosmet, sulfotep, and thiobencarb. nd, nondetection; —, not 

analyzed; ( ), concentration below detection limit]
10 Dissolved Pesticide Concentrations Detected in Storm-Water Runoff at Selected Sites in the San Joaquin River Basin, California, 2000–2001

Table 3. Pesticide concentrations in water samples collected at Orestimba Creek at River Road near Crows Landing, California, 2000–2001—Continued

Date

(mm/dd/yy) Time Atrazine Butylate Carbaryl Chlorpyrifos Cycloate Dacthal Diazinon Diethatylethyl Eptam

Sampling year 2001

01/19/01 1230 8.6 nd nd nd nd nd 9.9 nd nd

01/25/01 1445 nd nd nd nd nd 196 18.4 nd nd

01/25/01 1700 17.7 nd nd nd nd nd 11.9 nd nd

01/25/01 1800 nd nd nd nd nd 8.5 nd 31.9 nd

01/25/01 1915 4.7 nd nd nd nd nd 7.8 nd nd

01/25/01 2000 (3.3) nd nd nd nd 45.4 9.0 nd nd

01/25/01 2100 nd nd nd nd nd nd 11.0 nd nd

01/25/01 2200 17.3 nd nd nd nd 122 23.0 nd nd

01/25/01 2300 (3.1) nd nd nd nd 82.3 8.3 nd nd

01/25/01 2359 10.3 nd nd nd nd 39.0 9.0 nd nd

01/26/01 100 13.2 nd 22.6 nd nd 38.9 12.8 nd nd

01/26/01 200 nd nd 19.2 nd nd 45.0 7.8 nd nd

01/26/01 300 18.4 nd nd nd nd 15.7 15.7 nd nd

01/26/01 400 10.3 nd nd nd nd 22.6 18.7 nd 8.6

01/26/01 500 13.4 nd nd nd nd 19.0 11.7 nd nd

01/26/01 700 13.5 nd nd nd nd 11.3 15.2 nd nd

01/26/01 900 10.2 nd nd nd nd 10.5 12.8 nd nd

01/26/01 1845 9.4 nd nd nd 15.0 7.5 16.4 nd nd

01/27/01 1830 10.8 nd nd nd nd nd 7.4 nd nd

01/28/01 1520 18.1 nd nd nd nd nd 11.4 nd nd

01/29/01 1430 nd nd nd nd nd 8.9 9.8 nd nd

01/30/01 1530 10.9 nd nd nd nd nd 7.8 nd nd

01/31/01 1051 10.0 nd nd nd nd 8.3 18.4 nd nd

02/01/01 1200 8.5 nd nd 63.7 nd 8.4 49.6 nd nd

02/05/01 1200 13.3 nd nd nd nd 128 18.0 nd nd
Dissolved-Pesticide Concentrations 11

Table 3. Pesticide concentrations in water samples collected at Orestimba Creek at River Road near Crows Landing, California, 2000–2001—Continued

Date

(mm/dd/yy) Time Ethalfluralin

HexazinoneMethidathionMetolachlor Molinate Pendimethalin

OxyfluorfenPiperonyl 

butoxide Simazine Trifluralin

Sampling year 2000

01/30/00 1425 nd — 46.8 6.2 nd nd — — 588 14.8

01/30/00 1625 nd — 43.5 104 nd nd — — 963 29.0

02/11/00 2335 nd — nd 14.5 nd 33.8 — — 117 32.0

02/12/00 135 20.9 — 9.4 226 nd 30.0 — — 981 38.9

02/12/00 300 nd — (1.6) 62.2 nd 20.0 — — 104 18.8

02/12/00 335 nd — nd 41.3 nd (10.5) — — 366 23.2

02/12/00 630 nd — 9.4 44.3 nd 30.1 — — 196 23.2

02/12/00 840 nd — 9.9 52.0 nd 28.7 — — 362 27.8

02/12/00 1340 nd — nd 22.8 nd 40.4 — — 283 24.6

02/13/00 2055 nd — 92.3 9.8 nd 22.3 — — 182 23.1

02/13/00 2130 nd — 95.2 38.0 nd 40.6 — — 191 27.0

02/13/00 2320 nd — 25.2 10.4 nd nd — — 70.0 30.3

02/14/00 030 nd — 61.0 35.3 nd nd — — 83.4 41.4

02/14/00 130 nd — 31.8 nd nd nd — — nd 25.5

02/14/00 230 nd — 30.0 12.9 nd 22.3 — — 58.3 17.1

02/14/00 650 nd — nd nd nd nd — — 31.7 19.3

02/14/00 1100 nd — nd nd nd nd — — nd 21.8

02/14/00 1500 nd — nd nd nd nd — — 33.9 6.1

02/15/00 1145 nd — nd 11.5 nd nd — — nd 11.3

02/16/00 1200 nd — nd nd nd nd — — 57.0 12.5

02/17/00 615 nd — nd nd nd nd — — 30.7 13.3

02/17/00 1830 nd — nd 8.4 nd 14.9 — — nd 13.5

02/18/00 1300 nd — nd nd nd nd — — nd 21.7

02/19/00 1000 nd — nd nd nd nd — — 21.3 13.0
12 Dissolved Pesticide Concentrations Detected in Storm-Water Runoff at Selected Sites in the San Joaquin River Basin, California, 2000–2001

Table 3. Pesticide concentrations in water samples collected at Orestimba Creek at River Road near Crows Landing, California, 2000–2001—Continued

Date

(mm/dd/yy) Time Ethalfluralin

HexazinoneMethidathionMetolachlor Molinate Pendimethalin

OxyfluorfenPiperonyl 

butoxide Simazine Trifluralin

Sampling year 2001

01/19/01 1230 nd 43.6 nd 9.6 nd 8.8 40.1 nd 62.5 25.1

01/25/01 1445 nd 47.5 nd 31.5 nd 27.8 49.2 nd 74.1 24.4

01/25/01 1700 nd 45.1 nd 16.1 nd 25.5 38.3 nd 54.4 16.1

01/25/01 1800 nd 56.2 nd 23.1 nd 38.9 60.9 24.7 54.4 36.8

01/25/01 1915 nd 55.9 nd 10.2 nd 27.2 46.3 nd 45.2 27.6

01/25/01 2000 nd 47.8 nd 34.3 nd 30.3 42.2 nd 58.2 17.4

01/25/01 2100 nd 49.8 nd 12.1 nd 25.5 44.8 nd 41.0 24.1

01/25/01 2200 nd 38.3 nd 23.0 nd 26.0 39.3 nd 67.6 16.0

01/25/01 2300 nd 43.0 nd 16.3 nd 27.8 37.2 nd 116 22.3

01/25/01 2359 nd 35.1 nd 6.7 nd 22.5 28.6 11.6 129 9.7

01/26/01 100 nd 61.4 nd 20.7 nd 24.1 49.7 nd 242 19.1

01/26/01 200 nd 72.0 nd 54.6 nd 61.6 114 nd 315 18.4

01/26/01 300 nd 59.4 nd 29.1 nd 41.1 97.2 nd 337 17.0

01/26/01 400 nd 39.5 nd 21.5 12.3 27.1 52.4 nd 330 19.9

01/26/01 500 nd 35.3 nd 19.0 nd 24.6 51.7 nd 301 19.4

01/26/01 700 nd 41.8 nd 11.9 nd 31.3 64.2 8.9 236 14.6

01/26/01 900 nd 38.6 nd 15.2 nd 22.4 40.7 nd 145 17.4

01/26/01 1845 nd 39.0 nd 21.2 nd 20.5 168 nd 75.8 17.7

01/27/01 1830 nd 40.1 nd 6.2 nd nd 87.6 13.1 1,611 12.1

01/28/01 1520 nd 40.6 nd 16.3 nd 111 78.9 nd 321 17.0

01/29/01 1430 nd 34.7 nd 16.6 nd 31.5 40.9 nd 60.5 18.6

01/30/01 1530 nd 41.7 nd 4.9 nd 26.7 33.5 nd 62.4 8.3

01/31/01 1051 nd 53.4 nd 14.8 nd 33.8 30.5 5.2 50.3 10.3

02/01/01 1200 nd 29.0 nd 14.3 nd 33.0 30.2 nd 48.1 10.6

02/05/01 1200 nd 26.0 nd 25.1 nd 28.8 33.8 nd 90.2 12.7
Dissolved-Pesticide Concentrations 13

Date

(mm/dd/yy) Time Atrazine Carbaryl Chlorpyrifos Dacthal Diazinon Diethatylethyl

EthalfluralinHexazinoneMethidathionMetolachlor

Sampling year 2000

01/24/00 1500 nd nd nd nd 7.6 nd nd — 44.8 (2.1)

01/25/00 010 nd nd nd nd 9.3 nd nd — nd nd

01/25/00 1100 nd nd nd nd 11.5 nd nd — 51.4 (3.6)

01/25/00 2000 nd nd nd nd 26.8 nd nd — nd 19.3

01/26/00 730 nd nd nd nd 14.8 nd nd — nd 4.6

01/27/00 820 nd nd nd nd nd nd nd — nd nd

01/27/00 1600 nd nd nd nd nd nd nd — nd nd

02/11/00 2200 10.2 nd nd nd 26 nd nd — (0.3) 15.6

02/12/00 1230 11.0 nd nd nd 21.8 nd nd — (0.6) 15.1

02/12/00 2100 10.0 nd nd nd 31.2 nd nd — nd 6.3

02/13/00 530 13.1 nd nd nd 77.1 nd nd — (1.1) 35.3

02/13/00 2330 8.8 nd nd nd 40.6 nd nd — (3.9) 18.6

02/14/00 650 11.5 nd nd nd 40.7 nd nd — (0.9) 26.2

02/14/00 2000 nd nd nd nd 35.6 nd nd — 33.2 21.7

02/15/00 900 nd nd 12.3 nd 22.5 nd nd — nd 13.2

02/15/00 1000 nd nd nd nd 26.4 nd nd — nd nd

02/15/00 1830 nd nd 18.0 nd 17.1 nd nd — nd 18.7

02/16/00 830 nd nd nd nd 13.5 nd nd — nd 4.2

02/16/00 1600 nd nd nd nd 17.9 nd (0.8) — nd nd

02/16/00 1945 nd nd nd nd nd nd nd — nd nd

02/17/00 930 nd nd nd nd 23.4 nd nd — nd nd

02/17/00 1930 nd nd nd nd 16.2 nd nd — nd nd

02/18/00 1005 nd nd nd nd 13.4 nd nd — nd nd

02/18/00 1930 11.4 nd nd nd nd nd nd — nd nd

02/19/00 830 nd nd nd nd 12.6 nd nd — nd 15.7

02/23/00 1200 12.1 nd nd nd nd nd nd — nd nd

02/23/00 1200 nd nd nd nd 10.7 nd nd — nd (3.5)

Sampling year 2001

01/19/01 1330 (1.3) nd 16.3 nd 6.5 nd nd 30.2 nd nd

01/26/01 1345 16.0 nd 18.2 10.4 39.3 nd nd 32.5 33.0 22.3

01/27/01 845 10.7 31.6 nd nd 133 nd nd 27.9 17.6 nd

01/27/01 1710 nd 27.5 nd nd 128 32.0 nd 55.1 29.0 25.6

01/28/01 1030 19.3 nd nd nd 134 nd nd 37.8 nd 19.1

01/28/01 1650 8.6 nd 14.6 nd 154 nd nd 34.4 26.0 16.8

01/29/01 915 nd nd 13.4 nd 126 nd nd 32.5 nd 12.3

01/29/01 930 16.0 nd nd nd 137 nd nd 39.2 nd 18.9

01/29/01 2020 7.8 nd 13.6 nd 113 nd nd 44.7 nd 16.2

01/30/01 1800 nd nd nd nd 103 nd nd 106 nd 19.4

01/31/01 800 nd nd nd nd 52.9 nd nd 105 nd 6.1

02/01/01 1100 nd 8.3 8.2 nd 33.3 nd nd 47.3 nd 11.1

02/04/01 1200 nd 20.9 nd nd 22.4 nd nd 28.7 nd 18.6

Table 4. Pesticide concentrations in water samples collected at San Joaquin River near Vernalis, California, 2000–2001 

[Values are reported as nanograms per liter. Water samples were analyzed for the following pesticides that were not detected at this site: alachlor, azinphosmethyl, butylate, carbofuran, cyanazine, cycloate, eptam, fonofos, malathion, methylparathion, molinate, pebulate, sulfotep, and thiobencarb. nd, 

nondetection; —, not analyzed; ( ), concentration below detection limit]
14 Dissolved Pesticide Concentrations Detected in Storm-Water Runoff at Selected Sites in the San Joaquin River Basin, California, 2000–2001

Table 4. Pesticide concentrations in water samples collected at San Joaquin River near Vernalis, California, 2000–2001—Continued

Date

(mm/dd/yy) Time Napropamide Pendimethalin Phosmet Oxyfluorfen Piperonyl 

butoxide Simazine Trifluralin

Sampling year 2000

01/24/00 1500 nd 35.1 nd — — 95.0 15.6

01/25/00 010 nd 35.3 nd — — 80.8 15.6

01/25/00 1100 nd 42.9 53.9 — — 123 17.3

01/25/00 2000 nd 37.9 nd — — 244 nd

01/26/00 730 nd 36.2 nd — — 149 nd

01/27/00 820 nd 37.2 nd — — 136 nd

01/27/00 1600 nd 40.3 nd — — 99.6 nd

02/11/00 2200 nd 16.8 nd — — 45.2 15.8

02/12/00 1230 nd 13.3 nd — — 35.4 15.8

02/12/00 2100 nd 25.7 nd — — 206 14.7

02/13/00 530 nd 28.6 nd — — 106 21.3

02/13/00 2330 nd 18.8 nd — — 448 16.6

02/14/00 650 nd 22.6 nd — — 469 20.6

02/14/00 2000 28.4 nd nd — — 471 nd

02/15/00 900 38.9 17.5 nd — — 461 13.1

02/15/00 1000 37.3 20.7 nd — — 470 13.7

02/15/00 1830 nd 36.0 nd — — 487 6.4

02/16/00 830 45.7 nd nd — — 435 nd

02/16/00 1600 12.7 17.9 nd — — 331 14.5

02/16/00 1945 nd 43.2 nd — — 304 6.4

02/17/00 930 nd 19.6 nd — — 166 10.8

02/17/00 1930 nd 18.4 nd — — 133 11.5

02/18/00 1005 nd nd nd — — 113 9.8

02/18/00 1930 nd 23.6 nd — — 157 13.7

02/19/00 830 nd nd nd — — 124 6.7

02/23/00 1200 nd 23.5 nd — — 122 14.4

02/23/00 1200 nd nd nd — — 63.6 nd

Sampling year 2001

01/19/01 1330 nd 24.1 nd nd 19.6 51.1 21.4

01/26/01 1345 nd 27.3 nd 25.0 19.6 111 18.3

01/27/01 845 nd 39.0 nd nd 15.1 179 8.1

01/27/01 1710 nd 72.7 nd 57.7 28.2 178 35.4

01/28/01 1030 90.7 64.2 nd nd nd 376 nd

01/28/01 1650 79.8 39.8 nd nd nd 372 16.3

01/29/01 915 62.7 35.0 nd nd 4.5 694 10.5

01/29/01 930 67.7 40.7 nd nd nd 731 nd

01/29/01 2020 34.0 32.9 nd nd 12.6 664 16.0

01/30/01 1800 nd 26.3 nd nd 16.6 468 19.7

01/31/01 800 nd 25.7 nd nd 14.0 453 8.6

02/01/01 1100 nd 22.3 nd nd 10.5 211 11.3

02/04/01 1200 nd 23.5 nd nd 3.9 79.0 9.0
Dissolved-Pesticide Concentrations 15

Table 5. Method detection limits for pesticides analyzed in 2000 and 2001 

[—, not analyzed] 

Pesticide

2000 Method 

detection limit, in 

nanogram per liter

2001 Method 

detection limit, in 

nanogram per liter

Alachlor1 3.8 2.1

Atrazine 4.3 4.2

Azinphos-methyl1 — 11.1

Butylate 4.5 1.8

Carbaryl 4.6 4.2

Carbofuran 5.5 3.3

Chlorpyrifos 1.5 4.2

Cyanazine1 — 3.0

Cycloate 2.2 1.5

Dacthal 1.5 1.2

Diazinon 2.0 3.6

Diethatyl-ethyl 2.2 3.6

Eptam 5.7 4.5

Ethalfluralin 5.0 2.4

Fonofos1 3.5 2.4

Hexazinone — 5.7

Malathion1 3.1 2.1

Methidathion 5.5 5.4

Methylparathion1 6.9 4.2

Metolachlor 4.0 3.3

Molinate 4.0 2.7

Napropamide 10.9 7.2

Oxyfluorfen — 4.2

Pebulate1 3.4 0.6

Pendimethalin 12.4 2.4

Phosmet 5.9 4.2

Piperonyl butoxide — 3.3

Simazine 5.2 6.9

Sulfotep1 2.0 1.2

Thiobencarb1 3.4 3.9

Trifluralin 3.1 3.0

1Pesticide not detected in any samples in either year. 
16 Dissolved Pesticide Concentrations Detected in Storm-Water Runoff at Selected Sites in the San Joaquin River Basin, California, 2000–2001

Significant figures were estimated by the 

rounding method as described in American Society for 

Testing and Materials (1993).

REFERENCES CITED

American Society of Testing and Materials, 1993, Annual 

book of ASTM standards, Committee E-11 on Quality 

and Statistics, ASTME29-93a: Standard practice for 

using significant digits in test data to determine 

conformance with specifications: p. 18–21.

California Department of Food and Agriculture, 2001, 

California agricultural resource directory, 2001: 

Sacramento, Calif., California Department of Food and 

Agriculture, 180 p.

Dubrovsky, N.M., Kratzer, C.R., Brown, L.R., Gronberg, 

J.M., and Burow, K.R., 1998, Water quality in the San 

Joaquin–Tulare basins, California, 1992–95: 

U.S. Geological Survey Circular 1159, 38 p.

Foe, C.G., and Connor, V., 1991, San Joaquin watershed 

bioassay results, 1988–90: Central Valley Regional 

Water Quality Control Board, Staff Report, 

Sacramento, Calif., 79 p.

Kratzer, C.R., 1997, Transport of diazinon in the San Joaquin 

River Basin, California: U.S. Geological Survey Open 

File Report 97-411, 22 p.

Kuivila, K.M., and Foe, C.G., 1995, Concentrations, 

transport, and biological effects of dormant spray 

pesticides in the San Francisco Estuary, California: 

Journal of Environmental Toxicology and Chemistry, 

v. 14, no. 7, p. 1141–1150.

Panshin, S.Y., Dubrovsky, N.M., Gronberg, J.M., and 

Domagalski, J.L., 1998, Occurrence and distribution of 

dissolved pesticides in the San Joaquin River Basin, 

California: U.S. Geological Survey Water-Resources 

Investigations Report 98-4032, 88 p.