U.S. Department of the Interior

U.S. Geological Survey

Data Series 1089

Prepared in cooperation with the Delta Regional Monitoring Program

Pesticide Inputs to the Sacramento–San Joaquin Delta, 

2015–16: Results from the Delta Regional Monitoring Program
Cover. 1. U.S. Geological Survey personnel preparing to collect water samples from Ulatis Creek at Browns Road near Elmira, California.

2. Mokelumne River at New Hope Road at Thornton, California, looking upstream.

3. View of bridge over the San Joaquin River near Vernalis, California. 

1

2

3
Pesticide Inputs to the Sacramento–

San Joaquin Delta, 2015–16: Results from 

the Delta Regional Monitoring Program

By Matthew De Parsia, James L. Orlando, Megan M. McWayne, and 

Michelle L. Hladik

Data Series 1089

U.S. Department of the Interior

U.S. Geological Survey

Prepared in cooperation with the Delta Regional Monitoring Program
U.S. Department of the Interior

RYAN K. ZINKE, Secretary

U.S. Geological Survey

James F. Reilly II, Director

U.S. Geological Survey, Reston, Virginia: 2018

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Suggested citation:

De Parsia, M., Orlando, J.L., McWayne, M.M., and Hladik, M.L., 2018, Pesticide inputs to the Sacramento– San 

Joaquin Delta, 2015–16: Results from the Delta Regional Monitoring Program: U.S. Geological Survey Data Series 

1089, 49 p., https://doi.org/10.3133/ds1089

ISSN 2327-638X (online)
iii

Contents

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

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

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

Sampling Sites.......................................................................................................................................2

Mokelumne River at New Hope Road ......................................................................................2

Sacramento River at Hood .........................................................................................................2

San Joaquin River at Buckley Cove..........................................................................................5

San Joaquin River near Vernalis...............................................................................................5

Ulatis Creek at Browns Road.....................................................................................................5

Procedures and Methods.............................................................................................................................5

Sample Collection.................................................................................................................................5

Analytical Methods...............................................................................................................................6

Organic Chemistry Research Laboratory, Sacramento, California .....................................6

Extraction of Pesticides from Surface Water ................................................................6

Extraction of Pesticides from Suspended Sediment ....................................................6

Instrument Methods...........................................................................................................6

National Water Quality Laboratory, Denver, Colorado ..........................................................7

Copper Methods .................................................................................................................7

Inorganic Carbon, Organic Carbon, and Nitrogen Methods .......................................7

Method Detection Limits and Reporting Levels...............................................................................7

Quality-Control Methods and Results ......................................................................................................12

Results ...........................................................................................................................................................17

Mokelumne River at New Hope Road .............................................................................................17

Sacramento River at Hood ................................................................................................................17

San Joaquin River at Buckley Cove.................................................................................................45

San Joaquin River Near Vernalis .....................................................................................................45

Ulatis Creek at Browns Road............................................................................................................46

Summary........................................................................................................................................................46

References Cited..........................................................................................................................................47

Figures

1. Map showing sampling sites and the legal boundary of the Sacramento–

San Joaquin Delta, 2015–16. .......................................................................................................3

2. Map showing land-use types and watershed boundaries for sites sampled

from July 2015 to June 2016 in the Sacramento–San Joaquin Delta, California................4

3. Graph showing numbers of pesticides detected per month in surface-water

samples from July 2015 to June 2016 in the Sacramento–San Joaquin

Delta, California...........................................................................................................................45
iv

Tables

1. Surface-water sampling sites located in the Sacramento–San Joaquin 

Delta, 2015–16................................................................................................................................3

2. Method detection limits for dissolved pesticides in surface water and on

suspended sediments measured by the U.S. Geological Survey 

Organic Chemistry Research Laboratory..................................................................................8

3. Reporting levels for dissolved and suspended consituents measured by the

U.S. Geological Survey National Water Quality Laboratory. ...............................................12

4. Pesticide concentrations with measured detections by gas chromatography

with mass spectrometry (GC/MS) in environmental and field replicate

water samples collected in the Sacramento–San Joaquin Delta, 2015–16......................13

5. Pesticide concentrations with measured detections by liquid chromatography 

tandem mass spectrometry (LC/MS/MS) in environmental and field replicate 

water samples collected in the Sacramento–San Joaquin Delta, 2015–16......................14

6. Minimum, maximum, and median recovery of compounds in pesticide 

matrix-spiked water samples with standard deviation. .......................................................15

7. Pesticide concentrations with measured detections in environmental water 

samples collected in the Sacramento–San Joaquin Delta, 2015–16. ................................18

8. Pesticide concentrations with measured detections in suspended 

sediments filtered from environmental water samples collected in 

the Sacramento–San Joaquin Delta, 2015–16. ......................................................................30

9. Whole water pesticide concentrations for all compounds with detections 

in water and suspended sediment filtered from environmental water 

samples collected in the Sacramento–San Joaquin Delta, 2015–16. ................................33

10. Concentrations of dissolved and suspended constituents measured in 

environmental water samples collected in the Sacramento–

San Joaquin Delta, 2015–16. .....................................................................................................41

11. Water quality field parameters measured in surface-water samples 

collected in the Sacramento–San Joaquin Delta, California, 2015–16..............................43
v

Conversion Factors

International System of Units to U.S. customary units

Multiply By To obtain

Length

micrometer (μm) 0.00003937 inch (in.)

millimeter (mm) 0.03937 inch (in.)

meter (m) 3.281 foot (ft) 

Area

square kilometer (km2) 0.3861 square mile (mi2)

Volume

milliliter (mL) 0.033814 ounce, fluid (fl. oz)

liter (L) 33.81402 ounce, fluid (fl. oz)

Flow rate

milliliter per minute (mL/min) 0.033814 ounce, fluid per minute (fl. oz/min) 

Mass

milligram (mg) 0.000035 ounce, (oz)

kilogram (kg) 2.20462 pound, (lb)

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

°F = (1.8 × °C) + 32.

Datum

North American Datum of 1983 (NAD 83).

Supplemental Information

Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (μS/cm at 

25 °C).

Concentrations of chemical constituents in water are given in either milligrams per liter (mg/L), 

micrograms per liter (μg/L), or nanograms per liter (ng/L). One milligram per liter is equivalent 

to 1 part per million (ppm); one microgram per liter is equivalent to 1 part per billion (ppb); 

one nanogram per liter is equivalent to 1 part per trillion (ppt). Concentrations of pesticide 

compounds in suspended-sediments filtered from 1-liter water samples are provided in ng/L to 

facilitate the approximation of a whole-water pesticide concentration by summing the dissolved 

and suspended-sediment concentrations of pesticide compounds.
vi

Abbreviations

AHP Aquatic Health Program

ASC Aquatic Science Center

CDPR California Department of Pesticide Regulation

Delta RMP Delta Regional Monitoring Program

DOC dissolved organic carbon

EtOAc ethyl acetate

EPA U.S. Environmental Protection Agency

GC/MS gas chromatography mass spectrometry

LC/MS/MS liquid chromatography tandem mass spectrometry 

LT-MDL long-term method detection level

MDL method detection limit

MRL minimum reporting level

NWIS National Water Information System

NWQL National Water Quality Laboratory

OCRL Organic Chemistry Research Laboratory

PIC particulate inorganic carbon

± plus or minus

POC particulate organic carbon

POD pelagic organism decline

QAPP quality assurance program plan

RSD relative standard deviation

SPE solid phase extraction 

SWRCB State Water Resources Control Board

TPC total particulate carbon

TPN total particulate nitrogen

UCD University of California, Davis

USGS U.S. Geological Survey
Abstract

Emergent hypotheses about causes of the pelagic organism decline in the Sacramento–San Joaquin Delta (Delta) 

indicate that a more complete understanding of the quality 

of water entering the Delta is needed. Less than half of 

all pesticides used in the Delta watershed are measured in 

samples collected for routine monitoring, and with new 

pesticides continually being registered for use, the concentrations of unmonitored pesticides in the Delta ecosystem 

are unknown. In response, a multi-year, cooperative effort 

to improve monitoring of mercury, nutrients, pathogens, 

and pesticides was begun by the Delta Regional Monitoring 

Program (RMP). In July 2015, the U.S. Geological Survey 

in cooperation with the Delta RMP began measuring concentrations of 154 pesticide compounds in monthly samples of 

surface water and suspended sediment collected at five major 

inputs to the Sacramento–San Joaquin Delta from July 2015 

to June 2016. In addition to pesticide concentration measurements, field water-quality indicators (water temperature, 

specific conductance, dissolved oxygen, pH, and turbidity) 

were measured at each site and samples were collected for 

the analysis of dissolved organic carbon, dissolved copper, 

particulate organic carbon, particulate inorganic carbon, total 

particulate carbon, and total particulate nitrogen. Pesticide 

concentrations in particulates were measured in collected 

suspended-sediment samples by gas chromatography with 

mass spectrometry, whereas concentrations measured in 

surface-water samples utilized a combination of gas chromatography with mass spectrometry and liquid chromatography 

with tandem mass spectrometry. Samples were collected from 

two sites in the San Joaquin River watershed and at one site 

for each of the Mokelumne River, Sacramento River, and 

Ulatis Creek watersheds.

All water samples contained mixtures of 2–25 pesticides. Pesticides were detected in 100 percent of surfacewater samples. A total of 54 pesticide compounds were 

detected in water samples during the study period (19 fungicides, 18 herbicides, 9 insecticides, 7 breakdown products, 

and 1 synergist). The most frequently detected pesticide 

compounds were the herbicides hexazinone (95 percent) and 

diuron (73 percent) and the fungicides boscalid (93 percent) 

and azoxystrobin (75 percent). Pesticide concentrations ranged 

from below the method detection limits to 2,630 nanograms 

per liter for the herbicide metolachlor.

A total of 11 pesticide compounds were detected in the 

suspended sediments filtered from water samples (6 herbicides, 3 insecticides, 1 fungicide, and 1 breakdown product). 

The most frequently detected compounds were the insecticides 

permethrin (7 percent) and bifenthrin (5 percent) and the 

herbicide pendimethalin (5 percent). Pesticide concentrations 

in the suspended-sediment ranged from below the method 

detection limit to 265 nanograms per liter for the herbicide 

pendimethalin.

Introduction

The Sacramento–San Joaquin Delta (Delta) is an area of 

great importance to humans as both a source and a transport 

mechanism of freshwater. The Delta is also an area of critical habitat for numerous threatened and endangered species 

of concern, including Chinook salmon (Oncorhynchus 

tshawytscha) and the Delta smelt (Hypomesus transpacificus; 

Moyle, 2002; Brown and Moyle, 2005; Sommer and Mejia, 

2013). In recent years, multiple pelagic species in the Delta 

have been in sharp decline (Feyrer and others, 2007; Sommer 

and others, 2007). This phenomenon, termed the pelagic 

organism decline (POD), is thought to have four causes: 

(1) previous abundance of pelagic species; (2) changes in 

habitat, including changes in water quantity and water quality; 

(3) top-down effects, including predation and losses caused 

by entrainment in water export pumps; and (4) bottom-up 

changes in food availability for pelagic species (Baxter and 

others, 2010). These factors point to the need for a complete 

and timely understanding of the quality of water entering the 

Delta.

Studies have indicated that contaminants, including 

pesticides, may play a role in the POD (Sommer and others, 

2007; Werner and others, 2010). In 2014, reported pesticide 

Pesticide Inputs to the Sacramento–San Joaquin Delta, 

2015–16: Results from the Delta Regional Monitoring 

Program

By Matthew De Parsia, James L. Orlando, Megan M. McWayne, and Michelle L. Hladik
2 Pesticide Inputs to the Sacramento–San Joaquin Delta, 2015–16: Results from the Delta Regional Monitoring Program

use in the Delta watershed was over 50 million pounds 

of active ingredient (California Department of Pesticide 

Regulation, 2016). Because year-to-year pesticide use is 

continually changing, it presents a challenge for resource 

managers and policy makers trying to understand the fate and 

effects of these contaminants. Additionally, accurate estimates 

of pesticide use are difficult to make because only licensed 

pesticide applicators are required to report pesticide use to the 

California Department of Pesticide Regulation (CDPR). State 

regulators do not track household pesticide use and pesticides 

used in seed coatings.

Previous studies have shown that pesticides associated 

with agricultural and urban runoff are present in the Delta 

throughout the year and that the types and concentrations 

of these pesticides vary based on their use in the upstream 

watersheds (Dileanis and others, 2002; Kratzer and others, 

2002; Zamora and others, 2003; Orlando and Kuivila, 2005; 

Weston and Lydy, 2010; Zhang and others, 2012; Orlando and 

others, 2013; Orlando and others, 2014). Finally, less than half 

of all pesticides applied in the Delta watershed are analyzed 

for during routine monitoring studies, and new pesticides 

are continually being registered for use (Kuivila and Hladik, 

2008). The concentrations and potential effects of these 

unmonitored pesticides in the Delta ecosystem are unknown.

This study was conducted in cooperation with the San 

Francisco Estuary Institute Aquatic Science Center as part 

of the Delta Regional Monitoring Program (Delta RMP), a 

multi-year, cooperative effort to better track beneficial-use 

protections and restoration efforts in the Delta through the 

monitoring of mercury, nutrients, pathogens, and pesticides 

(Aquatic Science Center, 2017). The Delta RMP was created 

by the Central Valley Regional Water Quality Control Board 

to better coordinate water-quality monitoring in response to 

the early 2000s decline of pelagic fish species in the Delta. 

The Aquatic Science Center (ASC), a joint powers authority created by the State Water Resources Control Board 

(SWRCB) and the Bay Area Clean Water Agencies, is responsible for implementing activities necessary to achieve the 

goals of the Delta RMP, as well as preparing and publishing 

results collected for the program (Aquatic Science Center, 

2017). Monthly pesticide monitoring for the Delta RMP began 

in July 2015 and concluded in June 2017; this report contains 

results for July 2015 through June 2016. Although monthly 

pesticide monitoring concluded in June 2017, the Delta RMP 

is an ongoing monitoring program with no set end date for 

data collection or data dissemination.

Pesticide and toxicity samples were collected concurrently to determine whether pesticides could contribute to 

observed toxicity in the Delta. The role of the USGS in the 

Delta RMP is to collect pesticide, toxicity, and ancillary waterquality (dissolved organic carbon, DOC; dissolved copper; 

particulate organic carbon, POC; particulate inorganic carbon, 

PIC; total particulate carbon, TPC; and total particulate 

nitrogen, TPN) samples; perform the pesticide and ancillary 

water-quality analyses; and to generate pesticide-detection 

reports. Surface-water samples also were collected by the 

USGS for toxicity analysis by the University of California, 

Davis (UCD); ASC plans to publish these toxicity results in a 

future monitoring report. 

Purpose and Scope

This report describes field and laboratory methods used 

and reports the measured concentrations of pesticides and 

pesticide degradates found in surface water and in particulates 

filtered from surface-water samples at five sites that provide 

surface water input to the Delta. Concentrations of organic 

carbon, inorganic carbon, nitrogen, and copper also were 

measured and reported. Constituents with detections above the 

aquatic-life benchmark for chronic toxicity to invertebrates 

(U.S. Environmental Protection Agency, 2017) are reported 

where applicable. The data-collection period of July 2015–

June 2016 represents data collected for the first year of the 

Delta RMP.

Sampling Sites

Five sites were selected to be sampled monthly at inputs 

to the Delta (fig. 1; table 1). These sites were chosen by the 

Delta RMP Technical Advisory Committee to capture water 

at representative inflows to the Delta, to cover an extensive 

area, and to complement existing monitoring datasets (Aquatic 

Science Center, 2017). Land-use types and watershed boundaries for the five sampling sites are shown in figure 2. Land 

use has been grouped into six broad categories: urban, bare 

ground, forest, shrub and grasslands, agricultural, or wetlands 

(U.S. Geological Survey, 2014). The watershed boundary for 

the San Joaquin River at Buckley Cove also includes the San 

Joaquin River at Vernalis watershed boundary.

Mokelumne River at New Hope Road

The Mokelumne River originates in the western slope 

of the Sierra Nevada and drains into the San Joaquin River. 

Samples were collected from a bridge over the Mokelumne 

River. The site is tidally influenced; therefore, samples were 

only collected during outgoing tides. The contributing watershed area is approximately 700 square miles (mi2

), and land 

use is 8 percent agricultural and 2 percent urban (U.S. Geological Survey, 2014). The primary crops grown in the watershed 

by area are grapes, walnuts, and alfalfa (National Agricultural 

Statistics Service, 2016).

Sacramento River at Hood

The Sacramento River flows south from its headwaters in 

northern California and drains into the Delta. Samples at this 

site were collected 30 feet (ft) from the left bank on the Sacramento River from a monitoring platform maintained by the 

SWRCB. This site has minimal tidal influence, and although 
Introduction 3

Figure 1. Sampling sites and the legal boundary of the Sacramento–San Joaquin Delta, 2015–16.

Table 1. Surface-water sampling sites located in the Sacramento–San Joaquin Delta, 2015–16.

[Calif., California; dms, degree minute second; ID, identification; USGS, U.S. Geological Survey; °, degree; ', minute; ", second; *, collected from bridge at 

mid-channel during high-flow events]

USGS station 

number USGS station name Field ID Latitude1 (dms)

Longtitude1 

(dms)

Sample collection 

point

381411121250901 Mokelumne River at New Hope 

Road at Thornton, Calif.

Mokelumne River at New 

Hope Road

38°14'11" 121°25'09" Bridge, mid-channel

382205121311300 Sacramento River at Hood, Calif. Sacramento River at Hood 38°22'05" 121°31'13" Catwalk, mid-channel

375831121223701 San Joaquin River at Buckley 

Cove near Stockton, Calif.

San Joaquin River at 

Buckley Cove

37°58'31" 121°22'37" Wading, bank

11303500 San Joaquin River near Vernalis, 

Calif.

San Joaquin River near 

Vernalis

37°40'34" 121°15'59" Wading, mid-channel*

11455261 Ulatis Creek at Browns Road 

near Elmira, Calif.

Ulatis Creek at Browns 

Road

38°18'24" 121°47'41" Wading, mid-channel*

1

All locations reference North American Datum of 1983.

sac18-0662_fig01

Lodi

122° 121°30'

38°30'

38°

CALIFORNIA

Thornton

Vernalis

Davis

Sacramento

Elk Grove

Vacaville Elmira

Tracy

Stockton

Mok e l umne River

Sac ramento River

Sacrame nto River S a n Joa q u in River

Cosum ne s River

San Joaquin Ri v er

American River

Map

area

Suisun Bay

Ulatis Creek

EXPLANATION

Sacramento–San Joaquin Delta

Sampling site

Base modified from U.S. Geological Survey and other Federal and State digital data,

various scales; Albers Equal-Area Conic projection, standard parallels are

29°30' N. and 45°30' N.; North American Datum of 1983

0 5 10 MILES

0 5 10 KILOMETERS

San Joaquin River

near Vernalis

San Joaquin River

at Buckley Cove

Mokelumne River

at New Hope Road

Sacramento River

at Hood

Ulatis Creek

at Browns Road
4 Pesticide Inputs to the Sacramento–San Joaquin Delta, 2015–16: Results from the Delta Regional Monitoring Program

Figure 2. Land-use types and watershed boundaries for sites sampled from July 2015 to June 2016 in the Sacramento–San Joaquin 

Delta, California.

sac18-0662_fig 02

123° 120°

42°

40°

38°

Central

Valley

Map

area

NEVADA

PACIFIC

OCEAN

OREGON

SIERRA

NEVADA

C A L I F O R N I A

0 25 50 MILES

0 25 50 KILOMETERS

Land use

Urban

Bare ground

Forest

Shrub and grasslands

Agricultural/cultivated

Wetlands

EXPLANATION

Watershed boundary

Sampling site

Ulatis Creek

watershed

Sacramento River

watershed

Mokelumne River

watershed

San Joaquin River

at Buckley Cove

watershed

San Joaquin River near

Vernalis watershed

Base modified from U.S. Geological Survey and other Federal and State digital data,

various scales; Albers Equal-Area Conic projection, standard parallels are

29°30' N. and 45°30' N.; North American Datum of 1983
Procedures and Methods 5

flows do not regularly reverse directions, sample collection 

times were limited to outgoing tides to be sure to capture 

inflows to the Delta only. The watershed area upstream of the 

sample site encompasses over 23,900 mi2 of land, of which 

11 percent is used for agricultural purposes and 4 percent for 

urban (U.S. Geological Survey, 2014). The primary crops 

grown in the watershed by area are rice, almonds, and walnuts 

(National Agricultural Statistics Service, 2016).

San Joaquin River at Buckley Cove

The San Joaquin River originates in the Sierra Nevada 

and flows northward through the Central Valley where it enters 

the Delta near Vernalis, Calif. (fig. 2). San Joaquin River at 

Buckley Cove is in an urban area, near the city of Stockton, 

Calif. (population 291,707; U.S. Census Bureau, 2016). 

Samples were collected from the right bank by wading into 

the river at this site. This site has a strong tidal influence, and 

samples were collected during outgoing tides. The watershed 

area includes the San Joaquin River at Vernalis watershed plus 

an additional 1,200 mi2 of land, including 120 mi2 of urban 

land. The primary crops grown in the watershed by area are 

almonds, alfalfa, and walnuts (National Agricultural Statistics 

Service, 2016).

San Joaquin River near Vernalis

Flows on the San Joaquin River near Vernalis are not 

tidally influenced; they are highly influenced by dam releases 

and withdrawals for irrigation upstream of the sample collection point. Samples at this site were collected from a bridge 

over the San Joaquin River during high-flow conditions and 

collected by wading into the river during low-flow conditions. 

The watershed area upstream of the sample site encompasses 

over 7,300 mi2 of land; 21 percent of the land is used for 

agricultural purposes and 5 percent for urban (U.S. Geological 

Survey, 2014). The primary crops grown in the watershed by 

area are almonds, alfalfa, and grapes (National Agricultural 

Statistics Service, 2016).

Ulatis Creek at Browns Road

Ulatis Creek flows eastward from its source in the 

western margin of the Central Valley through the city of 

Vacaville, Calif. (population: 92,428; U.S. Census Bureau, 

2016) to the valley floor where Ulatis Creek enters the Delta. 

Samples were collected from a bridge during high-flow 

conditions and by wading during low-flow conditions. The 

contributing watershed area is approximately 140 mi2 with 

18 percent of the area used for urban purposes and 44 percent 

for agriculture (U.S. Geological Survey, 2014). The primary 

crops grown in the watershed by area are alfalfa, almonds, and 

walnuts (National Agricultural Statistics Service, 2016).

Procedures and Methods

Surface-water samples for pesticide, water chemistry 

(organic carbon, inorganic carbon, particulate nitrogen, and 

copper), and toxicity analyses were collected concurrently 

at each site. Pesticide samples were analyzed by the USGS 

at the Organic Chemistry Research Laboratory (OCRL) in 

Sacramento, Calif. Dissolved and particulate organic carbon, 

particulate inorganic carbon, particulate nitrogen, and dissolved copper samples were analyzed by the USGS at the 

National Water Quality Laboratory (NWQL) in Denver, Colo. 

and toxicity samples were analyzed by the Aquatic Health 

Program (AHP) at UCD.

Sample Collection

Surface-water samples were collected monthly at all sites 

from July 2015 to June 2016. Ten sample sets were collected 

approximately mid-month, and two sample sets were collected 

following moderate-rainfall events on January 19, 2016, and 

March 7, 2016. Surface-water samples for pesticide, ancillary 

water-quality (copper, DOC, PIC, POC, TPC, and TPN), and 

toxicity analyses were collected concurrently at each site. All 

water samples were collected as grab samples in accordance 

with methods described in the USGS National Field Manual 

(U.S. Geological Survey, variously dated). The study design 

approved by the Delta RMP called for grab samples because 

of the large volume of water required for collecting toxicity 

and pesticide samples together, even in hydrologic conditions 

that might otherwise dictate integrated sampling techniques. 

Samples were collected between the high and low tides or 

ebb tide (for tidally influenced sites), by submerging narrowmouthed bottles at mid-channel to a depth of 1.5 ft. During 

low-flow conditions, samples were collected by wading into 

streams and submerging handheld bottles. In high-flow conditions or for sites with difficult bank access, samples were 

collected from bridges using weighted-bottle samplers.

Pesticide samples were collected in precleaned, baked 

glass-amber bottles and transported on ice to the USGS OCRL 

in Sacramento, Calif., for processing and analysis. Samples 

for analysis at the USGS NWQL were collected in Teflon

bottles and transported on ice to the USGS California Water 

Science Center for processing. Prior to sampling, the Teflon

bottles were cleaned with tap water and laboratory-grade 

detergent, rinsed with a 5 percent hydrochloric-acid solution, 

triple rinsed with ASTM Type-I deionized water, and stored 

in sealed plastic bags. The Teflon bottles were triple rinsed 

with native water prior to sample collection.

Toxicity samples were collected in precleaned, glassamber bottles provided by the AHP. Bottles were triple rinsed 

with native water on-site prior to sample collection. Ten 

bottles were collected at each site and transported on ice to the 

AHP for analysis.

Basic water-quality measurements (water temperature, 

specific conductance, dissolved oxygen, pH, and turbidity) 

were taken at a depth of 1.5 ft at mid-channel during each 
6 Pesticide Inputs to the Sacramento–San Joaquin Delta, 2015–16: Results from the Delta Regional Monitoring Program

sample collection using a YSI 6920V2 multi-parameter meter. 

The meter was calibrated using appropriate procedures and 

standards prior to sample collection as described in the USGS 

National Field Manual (U.S. Geological Survey, variously 

dated).

Analytical Methods

Surface-water samples and suspended sediments filtered 

from surface water for pesticide analysis were analyzed by the 

USGS at the OCRL in Sacramento, Calif. Copper, DOC, PIC, 

POC, TPC, and TPN samples were analyzed by the USGS at 

the NWQL in Denver, Colo. Toxicity samples were analyzed 

by the AHP at UCD.

Organic Chemistry Research Laboratory, 

Sacramento, California

Samples for pesticide analysis were analyzed at the 

OCRL in Sacramento, Calif. One liter of water was extracted 

for analysis of 25 compounds by liquid chromatography 

tandem mass spectrometry (LC/MS/MS), and one liter of 

water was extracted for analysis of 129 compounds by gas 

chromatography mass spectrometry (GC/MS). All surfacewater samples for pesticide analysis were filtered through preweighed, baked 0.7-micrometer (μm) glass-fiber filters (Grade 

GF/F, Whatman, Piscataway, N.J.) to remove suspended 

material. The filter paper from the GC/MS sample containing the suspended sediments was dried at room temperature 

overnight, protected from light, then stored in a freezer at –20 

degrees Celsius (°C) until extraction. Analysis of pesticides in 

suspended-material samples was done on resultant filter paper.

Extraction of Pesticides from Surface Water

The extraction procedure and instrumental analysis by 

LC/MS/MS have been previously described in Hladik and 

Calhoun (2012). To summarize the method described in Hladik 

and Calhoun (2012), filtered-water samples were spiked with 

the recovery surrogate standards, monuron (Chem Service, 

West Chester, Pennsylvania) and imidacloprid-d4 (Cambridge 

Isotope Laboratories, Andover, Massachusetts). Each sample 

was then passed through an Oasis Hydrophilic Lipophilic 

Balance (HLB) solid-phase extraction (SPE; 6 milliliters, mL; 

500 milligrams, mg; Waters, Milford, Mass.) cartridge that 

had been cleaned with one column volume of dichloromethane 

followed by one column volume of acetone and two column 

volumes of deionized water. During the SPE process, the water 

samples were pumped through the SPE cartridge at a flow 

rate of 10 milliliters per minute (mL/min) and the cartridge 

was then dried under nitrogen until the SPE sorbent was dry. 

The analytes were eluted with 10 mL of 50:50 DCM:acetone. 

The eluent was then evaporated to less than 0.5 mL using a 

gentle stream of dry nitrogen, solvent exchanged into acetonitrile, and further evaporated to 0.2 mL. The internal standard 

(13C3-caffeine, Cambridge Isotope Laboratories, Andover, 

Mass.) was then added. The sample extracts were stored in a 

freezer at –20 °C until analysis (up to 30 days).

The extraction procedure (Hladik and others, 2008, 2009) 

and instrumental analysis by GC/MS (Hladik and McWayne, 

2012) have been previously described. Filtered-water 

samples were spiked with the recovery surrogate standards 

13C3

-atrazine and d14-trifluralin (Cambridge Isotopes, Andover, 

Mass.). Each sample was then passed through an Oasis HLB 

SPE (6 mL, 500 mg, Waters, Milford, Mass.) cartridge that 

had been cleaned with two column volumes of ethyl acetate 

(EtOAc), followed by two column volumes of methanol, and 

two column volumes of deionized water. During this process, 

the water samples were pumped through the SPE cartridge at 

a flow rate of 10 mL/min and the cartridge was dried under 

nitrogen until the SPE sorbent was dry. After extraction, 

sodium sulfate was added to the sample bottle to remove any 

residual water, then the bottle was rinsed three times with 

approximately 2 mL of DCM into a collection tube. The bottle 

rinse was concentrated to 1 mL under a gentle stream of nitrogen gas. The SPE cartridge was dried under nitrogen until the 

SPE sorbent was dry, then analytes were eluted with 12 mL of 

EtOAc into the concentrator tube containing the bottle rinse. 

The combined bottle rinse and eluent mixture was evaporated 

to less than 0.2 mL using a gentle stream of dry nitrogen. 

The internal standard, a mixture of deuterated compounds 

acenaphthene-d10 and pyrene-d10 was then added. The sample 

extracts were stored in a freezer at –20 °C until analysis (up to 

30 days).

Extraction of Pesticides from Suspended Sediment

Filter papers were cut up and placed in an Erlenmeyer 

flask, spiked with the recovery surrogate standards 

d14-trifluralin, 13C12-p,p’-DDE, and 13C6-permethrin (Cambridge Isotopes, Andover, Mass.) and extracted twice with 

50 mL of dichloromethane in a sonicator (Branson 5200, 

Danbury, Conn.) for 5 minutes. The extract was filtered 

through sodium sulfate, reduced using a Zymark Turbovap 

II (Hopinkton, Md) to 0.5 mL, then solvent exchanged into 

EtOAc, and further evaporated to less than 0.2 mL using a 

gentle stream of dry nitrogen. The internal standard, a mixture 

of deuterated compounds acenaphthene-d10 and pyrene-d10 was 

then added. The sample extracts were stored in a freezer at 

–20 °C until analysis (up to 30 days).

Instrument Methods

Water extracts for analysis by LC/MS/MS were analyzed 

on an Agilent (Palo Alto, Calif.) 1260 Infinity coupled to 

an Agilent 6430 Triple Quad LC/MS with a Zorbax Eclipse 

XDB-C18 column (2.1 by 150 by 3.5 millimeters, mm; 

Agilent). The column flow rate was 0.6 mL/min, and the 

column temperature was 30 °C. Data were collected in the 

multiple-reaction-monitoring mode. Additional details about 

the instrument method can be found in Hladik and Calhoun 

(2012).
Procedures and Methods 7

Water and filter extracts for analysis by GC/MS were analyzed on an Agilent 7890A gas chromatograph with an Agilent 

5975C inert mass-selective detector system using a DB-5MS 

analytical column (30 meter, m, by 0.25 mm by 0.25 μm; 

Agilent) for separation with helium as the carrier gas. Data 

were collected in the selected ion-monitoring mode. Additional details of the GC/MS method can be found in Hladik 

and others (2008, 2009).

National Water Quality Laboratory, Denver, 

Colorado

All samples collected for analysis at the NWQL were 

processed and preserved at the OCRL in Sacramento, Calif., 

prior to shipment on ice to the NWQL in Denver, Colo.

Copper Methods

Water samples for copper analysis were pumped through 

a 0.45-μm capsule filter (Pall Versapor WMV High Capacity) using a peristaltic pump and collected in an acid-rinsed 

250-mL high-density polyethylene bottle. Prior to sample 

collection, the capsule filter was rinsed with 2 L of ASTM 

Type-I deionized water followed by 25 mL of native water; the 

sample collection bottle was rinsed three times with ASTM 

Type-I deionized water and once with filtered native water. 

The sample was then preserved with certified, traceable nitric 

acid obtained from the NWQL. Copper was analyzed at the 

NWQL using the method described in Garbarino and others, 

(2006).

Inorganic Carbon, Organic Carbon, and Nitrogen Methods

Teflon filter towers with 25-mm filters were used for 

DOC, PIC, POC, TPC, and TPN samples. Sample water was 

passed through filters using gravity or compressed air. Water 

samples for DOC analysis were filtered through baked 0.3-μm 

glass-fiber filters (Advantec, Japan) into precleaned, baked 

125-mL amber-glass bottles then preserved with certified, 

traceable sulfuric acid obtained from the NWQL. Particulate 

analytes (PIC, POC, TPC, and TPN) were collected on three 

baked 0.3-μm glass-fiber filters (Advantec, Japan) and stored 

wrapped in aluminum foil. Native water was passed through 

each filter until the filter appeared to be covered with particulate and the total volume of water that passed through each 

filter was recorded. Dissolved organic carbon was analyzed at 

the NWQL using the method described in Brenton and Arnett, 

(1993). Particulate inorganic carbon, POC, TPC, and TPN 

were analyzed at the NWQL using U.S. Environmental Protection Agency (EPA) method 440.0 (Zimmerman and others, 

1997).

Method Detection Limits and Reporting Levels

Method detection limits (MDLs) for pesticide concentrations in surface water were validated in previous work 

(Hladik and others, 2008; Hladik and Calhoun, 2012) 

using the procedure described in 40 CFR 136, appendix B 

(U.S. Environmental Protection Agency, 1992). Method detection limits for pesticide compounds in suspended sediments 

filtered from surface water were validated in previous studies 

by Hladik and others (2009) and Hladik and McWayne (2012). 

Method detection limits for pesticide concentrations measured 

in surface water and suspended sediments are listed in table 2. 

Analytes can sometimes be identified at concentrations less 

than the MDLs with lower confidence in the numerical value; 

therefore, concentrations of compounds detected below the 

MDLs are reported as estimates and coded with an “E.”

Method detection limits for DOC and copper were 

determined by the NWQL by analyzing a series of spiked 

replicate samples and entering the results into the DQCALC 

software package following procedures described in 

ASTM International’s Standard Practice D7510-10 

(ASTM International, 2010). The method detection limit 

determined by DQCALC is the lowest concentration at which 

the chance of a false positive is equal to or less than 1 percent. 

Reporting levels are reevaluated annually and subject to 

change, but the reporting level is generally two times the 

method detection limit. The reporting level is used to control 

false negative error.

Method detection limits for PIC, POC, TPC, and TPN 

were determined by the NWQL using the long-term method 

detection level (LT-MDL) following protocols described in 

Childress and others (1999). The LT-MDL is used to limit the 

chance of reporting false positives. Analytes with positive 

detections, but concentrations measured below the LT-MDL, 

were flagged with an “E” result-level qualifier. Results with an 

“E” qualifier have a high certainty of a positive detection, but 

the exact concentration is uncertain. 

Laboratory reporting levels are used to control false 

negative error and are usually set at two times the LT-MDL. 

Particulate organic carbon was reported based on the 

minimum reporting level (MRL). The MRL is the “smallest 

measured concentration of a constituent that may be reliably 

reported using a given analytical method” (Timme, 1995). 

Results below the MRL were flagged with a “<” qualifier. 

Reporting levels for the analytes measured at the NWQL in 

this study are listed in table 3.
8 Pesticide Inputs to the Sacramento–San Joaquin Delta, 2015–16: Results from the Delta Regional Monitoring Program

Table 2. Method detection limits for dissolved pesticides in surface water and on suspended sediments measured by the 

U.S. Geological Survey Organic Chemistry Research Laboratory.

[GC/MS, gas chromatography mass spectrometry; LC/MS/MS, liquid chromatography/tandem mass spectrometry; ng/L, nanogram per liter; NWIS, National 

Water Information System]

Compound

NWIS 

parameter 

code

Chemical class Primary pesticide use

Method 

detection limit 

(ng/L)

Analytical 

method

Acetamiprid 68302 Neonicotinoid Insecticide 3.3 LC/MS/MS

Acibenzolar-S-methyl 51849 Unclassified Fungicide 3.0 GC/MS

Alachlor 65064 Chloroacetanilide Herbicide 1.7 GC/MS

Allethrin 66586 Pyrethroid Insecticide 1.0 GC/MS

Atrazine 65065 Triazine Herbicide 2.3 GC/MS

Azinphos-methyl 65066 Organophosphorus Insecticide 9.4 GC/MS

Azinphos-methyl oxon 68211 Organophosphorus Breakdown product 9.4 GC/MS

Azoxystrobin 66589 Strobin Fungicide 3.1 GC/MS

Benefin (benfluralin) 51643 2,6-Dinitroaniline Herbicide 2.0 GC/MS

Bifenthrin 65067 Pyrethroid Insecticide 0.7 GC/MS

Boscalid 67550 Anilide Fungicide 2.8 GC/MS

Bromoconazole 68315 Azole Fungicide 3.2 GC/MS

Butralin 68545 2,6-Dinitroaniline Herbicide 2.6 GC/MS

Butylate 65068 Thiocarbamate Herbicide 1.8 GC/MS

Captan 68322 Thiophthalimide Fungicide 10.2 GC/MS

Carbaryl 65069 N-Methyl carbamate Insecticide 6.5 GC/MS

Carbendazim 68548 Benzimidazole Fungicide 4.2 LC/MS/MS

Carbofuran 65070 N-Methyl carbamate Insecticide 3.1 GC/MS

Chlorantraniliprole 51856 Anthranilic diamide Insecticide 4.0 LC/MS/MS

Chlorothalonil 65071 Substituted benzene Fungicide 4.1 GC/MS

Chlorpyrifos 65072 Organophosphorus Insecticide 2.1 GC/MS

Chlorpyrifos oxon 68216 Organophosphorus Insecticide 5.0 GC/MS

Clomazone 67562 Unclassified Herbicide 2.5 GC/MS

Clothianidin 68221 Neonicotinoid Insecticide 3.9 LC/MS/MS

Coumaphos 51836 Organophosphorus Insecticide 3.1 GC/MS

Cyantraniliprole 51862 Anthranilic diamide Insecticide 4.2 LC/MS/MS

Cyazofamid 51853 Azole Fungicide 4.1 LC/MS/MS

Cycloate 65073 Thiocarbamate Herbicide 1.1 GC/MS

Cyfluthrin 65074 Pyrethroid Insecticide 1.0 GC/MS

Cyhalofop-butyl 68360 Aryloxyphenoxy propionic acid Herbicide 1.9 GC/MS

Cyhalothrin (all isomers) 68354 Pyrethroid Insecticide 0.5 GC/MS

Cymoxanil 51861 Unclassified Fungicide 3.9 LC/MS/MS

Cypermethrin 65075 Pyrethroid Insecticide 1.0 GC/MS

Cyproconazole 66593 Azole Fungicide 4.7 GC/MS

Cyprodinil 67574 Pyrimidine Fungicide 7.4 GC/MS

DCPA 65076 Alkyl phthalate Herbicide 2.0 GC/MS

DCPMU 68231 Urea Breakdown product 3.5 LC/MS/MS

DCPU 68226 Urea Breakdown product 3.4 LC/MS/MS

Deltamethrin 65077 Pyrethroid Insecticide 0.6 GC/MS

Desthio-prothioconazole 51865 Unclassified Breakdown product 3.0 LC/MS/MS
Procedures and Methods 9

Compound

NWIS 

parameter 

code

Chemical class Primary pesticide use

Method 

detection limit 

(ng/L)

Analytical 

method

Desulfinylfipronil 66607 Unclassified Breakdown product 1.6 GC/MS

Desulfinylfipronil amide 68570 Unclassified Breakdown product 3.2 GC/MS

Diazinon 65078 Organophosphorus Insecticide 0.9 GC/MS

Diazoxon 68236 Organophosphorus Breakdown product 5.0 GC/MS

3,4-Dichloroaniline 66584 Amine Breakdown product 3.2 LC/MS/MS

3,5-Dichloroaniline 67536 Unclassified Breakdown product 7.6 GC/MS

Difenoconazole 67582 Azole Fungicide 10.5 GC/MS

Dimethomorph 68373 Morpholine Fungicide 6.0 GC/MS

Dinotefuran 68379 Neonicotinoid Insecticide 4.5 LC/MS/MS

Dithiopyr 51837 Pyridinecarboxylic acid Herbicide 1.6 GC/MS

Diuron 66598 Urea Herbicide 3.2 LC/MS/MS

EPTC 65080 Thiocarbamate Herbicide 1.5 GC/MS

Esfenvalerate 65081 Pyrethroid Insecticide 0.5 GC/MS

Ethaboxam 51855 Unclassified Fungicide 3.8 LC/MS/MS

Ethalfluralin 65082 2,6-Dinitroaniline Herbicide 3.0 GC/MS

Etofenprox 67604 Pyrethroid ether Insecticide 2.2 GC/MS

Famoxadone 67609 Oxazolidinedione Fungicide 2.5 GC/MS

Fenamidone 51848 Imidazole Fungicide 5.1 GC/MS

Fenarimol 67613 Pyrimidine Fungicide 6.5 GC/MS

Fenbuconazole 67618 Azole Fungicide 5.2 GC/MS

Fenhexamid 67622 Anilide Fungicide 7.6 GC/MS

Fenpropathrin 65083 Pyrethroid Insecticide 0.6 GC/MS

Fenpyroximate 51838 Pyrazole Insecticide 5.2 GC/MS

Fenthion 51839 Organophosphorus Insecticide 5.5 GC/MS

Fipronil 66604 Pyrazole Insecticide 2.9 GC/MS

Fipronil sulfide 66610 Unclassified Breakdown product 1.8 GC/MS

Fipronil sulfone 66613 Unclassified Breakdown product 3.5 GC/MS

Flonicamid 51858 Unclassified Insecticide 3.4 LC/MS/MS

Fluazinam 67636 2,6-Dinitroaniline Fungicide 4.4 GC/MS

Fludioxonil 67640 Unclassified Fungicide 7.3 GC/MS

Flufenacet 51840 Anilide Herbicide 4.7 GC/MS

Flumetralin 51841 2,6-Dinitroaniline Plant growth regulator 5.8 GC/MS

Fluopicolide 51852 Benzamide pyridine Fungicide 3.9 GC/MS

Fluoxastrobin 67645 Strobin Fungicide 9.5 GC/MS

Fluridone 51864 Unclassified Herbicide 3.7 LC/MS/MS

Flusilazole 67649 Azole Fungicide 4.5 GC/MS

Flutolanil 51842 Anilide Fungicide 4.4 GC/MS

Flutriafol 67653 Azole Fungicide 4.2 GC/MS

Fluxapyroxad 51851 Anilide, pyrazole Fungicide 4.8 GC/MS

Hexazinone 65085 Triazinone Herbicide 8.4 GC/MS

Table 2. Method detection limits for dissolved pesticides in surface water and on suspended sediments measured by the 

U.S. Geological Survey Organic Chemistry Research Laboratory.—Continued

[GC/MS, gas chromatography mass spectrometry; LC/MS/MS, liquid chromatography/tandem mass spectrometry; ng/L, nanogram per liter; NWIS, National 

Water Information System]
10 Pesticide Inputs to the Sacramento–San Joaquin Delta, 2015–16: Results from the Delta Regional Monitoring Program

Compound

NWIS 

parameter 

code

Chemical class Primary pesticide use

Method 

detection limit 

(ng/L)

Analytical 

method

Imazalil 67662 Azole Fungicide 10.5 GC/MS

Imidacloprid 68426 Neonicotinoid Insecticide 3.8 LC/MS/MS

Indoxacarb 68627 Unclassified Insecticide 4.9 GC/MS

Ipconazole 52762 Azole Fungicide 7.8 GC/MS

Iprodione 66617 Dicarboximide Fungicide 4.4 GC/MS

Kresoxim-methyl 67670 Strobin Fungicide 4.0 GC/MS

Malaoxon 68240 Organophosphorus Breakdown product 5.0 GC/MS

Malathion 65087 Organophosphorus Insecticide 3.7 GC/MS

Mandipropamid 51854 Amide Fungicide 3.3 LC/MS/MS

Metalaxyl 68437 Xylylalanine Fungicide 5.1 GC/MS

Metconazole 66620 Azole Fungicide 5.2 GC/MS

Methidathion 65088 Organophosphorus Insecticide 7.2 GC/MS

Methoprene 66623 Juvenile hormone mimic Insect growth regulator 6.4 GC/MS

Methoxyfenozide 68647 Diacylhydrazine Insecticide 2.7 LC/MS/MS

Methyl parathion 65089 Organophosphorus Insecticide 3.4 GC/MS

Metolachlor 65090 Chloroacetanilide Herbicide 1.5 GC/MS

Molinate 65091 Thiocarbamate Herbicide 3.2 GC/MS

Myclobutanil 66632 Azole Fungicide 6.0 GC/MS

Napropamide 65092 Amide Herbicide 8.2 GC/MS

Novaluron 68655 Benzoylurea Herbicide 2.9 GC/MS

Oryzalin 68663 2,6-Dinitroaniline Herbicide 5.0 LC/MS/MS

Oxadiazon 51843 Unclassified Herbicide 2.1 GC/MS

Oxyfluorfen 65093 Diphenyl ether Herbicide 3.1 GC/MS

p,p’-DDD 65094 Organochlorine Insecticide, breakdown product 4.1 GC/MS

p,p’-DDE 65095 Organochlorine Breakdown product 3.6 GC/MS

p,p’-DDT 65096 Organochlorine Insecticide 4.0 GC/MS

Paclobutrazol 51846 Azole Plant growth regulator 6.2 GC/MS

Pebulate 65097 Thiocarbamate Herbicide 2.3 GC/MS

Pendimethalin 65098 2,6-Dinitroaniline Herbicide 2.3 GC/MS

Penoxsulam 51863 Triazolopyrimidine Herbicide 3.5 LC/MS/MS

Pentachloroanisole 66637 Organochlorine Breakdown product 4.7 GC/MS

Pentachloronitrobenzene 66639 Substituted benzene Fungicide 3.1 GC/MS

Permethrin 65099 Pyrethroid Insecticide 0.6 GC/MS

Phenothrin 65100 Pyrethroid Insecticide 1.0 GC/MS

Phosmet 65101 Organophosphorus Insecticide 4.4 GC/MS

Picoxystrobin 51850 Strobin Fungicide 4.2 GC/MS

Piperonyl butoxide 65102 Unclassified Synergist 2.3 GC/MS

Prodiamine 51844 2,6-Dinitroaniline Herbicide 5.2 GC/MS

Prometon 67702 Triazine Herbicide 2.5 GC/MS

Prometryn 65103 Triazine Herbicide 1.8 GC/MS

Table 2. Method detection limits for dissolved pesticides in surface water and on suspended sediments measured by the 

U.S. Geological Survey Organic Chemistry Research Laboratory.—Continued

[GC/MS, gas chromatography mass spectrometry; LC/MS/MS, liquid chromatography/tandem mass spectrometry; ng/L, nanogram per liter; NWIS, National 

Water Information System]
Procedures and Methods 11

Compound

NWIS 

parameter 

code

Chemical class Primary pesticide use

Method 

detection limit 

(ng/L)

Analytical 

method

Propanil 66641 Anilide Herbicide 10.1 GC/MS

Propargite 68677 Unclassified Insecticide 6.1 GC/MS

Propiconazole 66643 Azole Fungicide 5.0 GC/MS

Propyzamide 67706 Amide Herbicide 5.0 GC/MS

Pyraclostrobin 66646 Strobin Fungicide 2.9 GC/MS

Pyridaben 68682 Unclassified Insecticide 5.4 GC/MS

Pyrimethanil 67717 Pyrimidine Fungicide 4.1 GC/MS

Quinoxyfen 51847 Quinoline Fungicide 3.3 GC/MS

Resmethrin 65104 Pyrethroid Insecticide 1.0 GC/MS

Sedaxane 52648 Anilide, pyrazole Fungicide 5.2 GC/MS

Simazine 65105 Triazine Herbicide 5.0 GC/MS

Tau-fluvalinate 65106 Pyrethroid Insecticide 0.7 GC/MS

Tebuconazole 66649 Azole Fungicide 3.7 GC/MS

Tebupirimfos 68693 Organophosphorus Insecticide 1.9 GC/MS

Tebupirimfos oxon 68694 Organophosphorus Breakdown product 2.8 GC/MS

Tefluthrin 67731 Pyrethroid Insecticide 0.6 GC/MS

Tetraconazole 66654 Azole Fungicide 5.6 GC/MS

Tetradifon 51651 Unclassified Insecticide 3.8 GC/MS

Tetramethrin 66657 Pyrethroid Insecticide 0.5 GC/MS

Thiabendazole 67161 Benzimidazole Fungicide 3.6 LC/MS/MS

Thiacloprid 68485 Neonicotinoid Insecticide 3.2 LC/MS/MS

Thiamethoxam 68245 Neonicotinoid Insecticide 3.4 LC/MS/MS

Thiazopyr 51845 Pyridinecarboxylic acid Herbicide 4.1 GC/MS

Thiobencarb 65107 Thiocarbamate Herbicide 1.9 GC/MS

Tolfenpyrad 51866 Pyrazole Insecticide 2.9 LC/MS/MS

Triadimefon 67741 Azole Fungicide 8.9 GC/MS

Triadimenol 67746 Azole Fungicide 8.0 GC/MS

Triallate 68710 Thiocarbamate Herbicide 2.4 GC/MS

Tribufos 68711 Organophosphorus Defoliant 3.1 GC/MS

Trifloxystrobin 66660 Strobin Fungicide 4.7 GC/MS

Triflumizole 67753 Azole Fungicide 6.1 GC/MS

Trifluralin 65108 2,6-Dinitroaniline Herbicide 2.1 GC/MS

Triticonazole 67758 Azole Fungicide 6.9 GC/MS

Zoxamide 67768 Amide Fungicide 3.5 GC/MS

Table 2. Method detection limits for dissolved pesticides in surface water and on suspended sediments measured by the 

U.S. Geological Survey Organic Chemistry Research Laboratory.—Continued

[GC/MS, gas chromatography mass spectrometry; LC/MS/MS, liquid chromatography/tandem mass spectrometry; ng/L, nanogram per liter; NWIS, National 

Water Information System]
12 Pesticide Inputs to the Sacramento–San Joaquin Delta, 2015–16: Results from the Delta Regional Monitoring Program

Table 3. Reporting levels for dissolved and suspended consituents measured by the U.S. Geological Survey National Water Quality 

Laboratory.

[dl-dqc, detection limit by DQCALC software; lt-mdl, long term-method detection levels; mg/L, milligram per liter; mrl, minimum reporting level; 

NWIS, National Water Information System; μg/L, microgram per liter]

Analyte Group NWIS 

parameter code Sample fraction Reporting level Reporting threshold type Parameter unit

Organic carbon Organics, other 00681 Dissolved 0.23 dl-dqc mg/L

Inorganic carbon Inorganics, major, non-metals 00688 Suspended 0.03 lt-mdl mg/L

Organic carbon Organics, other 00689 Suspended 0.05 mrl mg/L

Total carbon Inorganics, major, non-metals 00694 Suspended 0.05 lt-mdl mg/L

Copper Inorganics, minor, metals 01040 Dissolved 0.80 dl-dqc μg/L

Nitrogen Nutrient 49570 Suspended 0.030 lt-mdl mg/L

Quality-Control Methods and Results

A quality assurance program plan (QAPP) was designed 

by the Aquatic Science Center and approved by the Delta 

RMP Technical Advisory Committee to ensure data quality 

(Aquatic Science Center, 2016). Field replicates, field blanks, 

laboratory matrix spikes, and matrix-spike replicates were 

used to validate pesticide concentrations measured in the water 

using GC/MS and LC/MS/MS and in the suspended sediments 

using GC/MS. Field replicates and blanks were collected 

and analyzed to validate results for analytes measured at the 

NWQL.

Pesticide Surrogate Compounds—To assess the 

efficiency of water sample extraction for the GC/MS 

and LC/MS/MS analytical methods, 13C3-atrazine and 

d14-trifluralin, and monuron and imidacloprid-d4, respectively, 

were used as recovery surrogates for extracts. Mean (plus 

or minus, ±, standard deviation) recoveries of 13C3-atrazine, 

d14-trifluralin, monuron, and imidacloprid-d4 were 90±11 

percent, 89±14 percent, 83±12 percent, and 91±13 percent, 

respectively. To assess the efficiency of filter sample extraction, d14-trifluralin, 13C12-p,p’-DDE, and 13C6

-permethrin were 

used as recovery surrogates for extracts. Mean (± standard 

deviation) recoveries of d14-trifluralin, 13C12-p,p’-DDE, and 13C6

-permethrin were 91±11 percent, 91±7 percent, and 96±11 

percent, respectively.

Blanks—Six pesticide field blanks (three for analysis 

by GC/MS, three for analysis by LC/MS/MS) were collected 

to verify the cleanliness of pesticide sample collection and 

processing protocols. Filters from the three pesticide field 

blanks collected for analysis by GC/MS also were saved and 

analyzed as suspended-sediment field blanks. No pesticides 

were detected in any of the pesticide field blanks. Six field 

blanks (three for copper analysis, three for DOC analysis) 

were collected for analysis at the USGS NWQL. There were 

no detections in the copper samples. One DOC blank had a 

detection at 0.37 milligram per liter (mg/L; reporting level 

0.23 mg/L).

Replicates—Seven pesticide field-replicate samples 

(three for analysis by GC/MS, four for analysis by 

LC/MS/MS) were collected concurrently to test the reproducibility of results based on field sampling methods (tables 4

and 5, respectively). The relative standard deviations (RSD) 

of all environmental and replicate pairs fell below the control 

limit of 25 percent. Filters from the three replicate samples 

were collected as suspended-sediment replicates; there were 

no pesticide detections in any of the environmental and 

replicate suspended-sediment pairs. Six field replicates were 

collected (three for copper analysis, three for DOC analysis) for analysis at the USGS NWQL. Results from the six 

replicates analyzed by the NWQL met the QAPP data-quality 

objective of less than 25 percent RSD (U.S. Geological 

Survey, 2017).

Matrix Spikes—Nine pesticide matrix-spike samples 

(four for analysis by GC/MS, five for analysis by LC/MS/MS) 

and six pesticide matrix-spike replicate samples (three for 

analysis by GC/MS, three for analysis by LC/MS/MS) were 

collected to assess pesticide recovery, degradation, sorption, 

and potential interferences caused by the sampling matrix. 

The minimum, maximum, and median recoveries and standard 

deviation of the recoveries are presented in table 6. Recoveries 

of 151 matrix-spike compounds satisfied the QAPP objectives 

of 70–130 percent recovery of pesticide matrix-spike compounds. Recoveries of fenthion in 2 samples, mandipropamid 

in 1 sample, and tebupirimfos oxon in 1 sample exceeded 

130 percent recovery of pesticide matrix-spike compounds. 

All pesticide matrix-spike samples with matrix-spike replicate 

pairs satisfied the QAPP objective of less than 25 percent relative percent difference between matrix spike and matrix-spike 

replicate pairs.
Table 4. Pesticide concentrations with measured detections by gas chromatography with mass spectrometry (GC/MS) in environmental and field recollected in the Sacramento–San Joaquin Delta, 2015–16.[Numbers in brackets are U.S. Geological Survey (USGS) National Water Information System (NWIS) parameter codes. Concentrations are in nanograms per liter. Results in padetection limits and are estimates. Abbreviations: E, estimated; hh:mm, hour:minute; mm/dd/yyyy, month/day/year; RSD, relative standard deviation; %, percent; —, not detec

Sample date 

(mm/dd/yyyy)

Sample 

time 

(hh:mm)

Sample type Atrazine [65065] Azoxystrobin [66589] Boscalid [67550] Carbaryl [65069] Clomazone [67562] Desulfiny

[666

Sacramento River at Hood

07/28/2015 08:45 Environmental — 84.4 3.8 31.1 10.9 — 07/28/2015 08:45 Field replicate — 78.6 3.4 29.4 10.5 — 

— — RSD — 5% 10% 4% 3% — 

San Joaquin River at Buckley Cove

09/23/2015 10:45 Environmental 8.2 38.0 11.6 — — 309/23/2015 10:45 Field replicate 8.6 41.8 12.2 — — 3

— — RSD 3% 7% 4% — — 3

Mokelumne River at New Hope Road

11/10/2015 10:00 Environmental — — 14.8 — — — 11/10/2015 10:00 Field replicate — — 16.9 — — — 

— — RSD — — 9% — — — 

Sample date 

(mm/dd/yyyy)

Sample 

time 

(hh:mm)

Sample type Fipronil [66604] Fipronil sulfide [66610] Fluxapyroxad [51851] Hexazinone [65085] Metolachlor [65090] Piperonyl butoxide [65102] 

Sacramento River at Hood—Continued

07/28/2015 08:45 Environmental 25.0 — — 43.8 13.2 36.3 07/28/2015 08:45 Field replicate 23.6 — — 40.6 12.1 32.8 

— — RSD 4% — — 5% 6% 7% 

San Joaquin River at Buckley Cove—Continued

09/23/2015 10:45 Environmental — 3.0 22.6 39.0 43.3 6.1 09/23/2015 10:45 Field replicate — 3.2 24.7 40.3 45.4 6.5 

— — RSD — 3% 6% 2% 3% 5% 

Mokelumne River at New Hope Road—Continued

11/10/2015 10:00 Environmental 3.1 — E3.4 15.9 — 14.6 11/10/2015 10:00 Field replicate 2.9 — E3.2 17.7 — 13.6 

— — RSD 3% — 4% 8% — 5% 
Table 5. Pesticide concentrations with measured detections by liquid chromatography tandem mass spectrometry (LC/MS/MS) in environmental ansamples collected in the Sacramento–San Joaquin Delta, 2015–16. [Numbers in brackets are U.S. Geological Survey (USGS) National Water Information System (NWIS) parameter codes. Concentrations are in nanograms per liter. Results in padetection limits and are estimates. Abbreviations: E, estimated; hh:mm, hour:minute; mm/dd/yyyy, month/day/year; RSD, relative standard deviation; %, percent; —, not detec

Sample date (mm/dd/yyyy) Sample time (hh:mm) Sample type Carbendazim [68548] Chlor-antranilip- role [51856] DCPMU [68231] DCPU [68226] 3,4-Dichloroani- line [66584] Diuron [66598] Fluridone [51864] Imidacloprid [68426] Meth

San Joaquin River at Buckley Cove 07/28/2015 08:45 Environmental 61.0 5.0 49.5 9.1 9.3 86.5 382.7 E3.2 

07/28/2015 08:45 Field replicate 67.9 5.5 52.1 9.8 8.9 87.7 409.7 E3.5 

— — RSD 8% 6% 4% 5% 4% 1% 5% 6% 

Ulatis Creek at Browns Road 09/23/2015 14:15 Environmental — 36.1 4.0 — E2.1 5.1 6.7 4.6 

09/23/2015 14:15 Field replicate — 42.5 4.8 — E2.4 5.7 7.6 5.5 

— — RSD — 12% 13% — 9% 7% 9% 12% 

Sacramento River at Hood 11/10/2015 10:00 Environmental 21.1 — — — 3.2 — — — 

11/10/2015 10:00 Field replicate 22.2 — — — 3.3 — — — 

— — RSD 4% — — — 2% — — — 

San Joaquin River near Vernalis 05/18/2016 12:20 Environmental — — — — — 7.5 — — 

05/18/2016 12:20 Field replicate — — — — — 8.0 — — 

— — RSD — — — — — 4% — — 
Quality-Control Methods and Results 15

Table 6. Minimum, maximum, and median recovery of compounds in pesticide matrix-spiked water samples with standard deviation.

[Four spiked samples and three spiked replicate samples were analyzed by gas chromatography/mass spectrometry. Compounds noted with ** were analyzed in 

five spiked samples and three spiked replicate samples by liquid chromatography/tandem mass spectrometry. Abbreviation: ±, plus or minus]

Compound

Minimum 

recovery 

(percent)

Maximum 

recovery 

(percent)

Median 

recovery 

(percent)

Standard 

deviation

(percent)

Acetamiprid** 74 89 82 ±6

Acibenzolar-Smethyl

89 122 99 ±12

Alachlor 92 113 97 ±7

Allethrin 87 113 96 ±10

Atrazine 94 101 99 ±2

Azinphos-methyl 86 109 93 ±8

Azinphos-methyl 

oxon

82 106 98 ±10

Azoxystrobin 88 102 92 ±5

Benfluralin 86 97 93 ±4

Bifenthrin 83 100 96 ±7

Boscalid 91 104 98 ±5

Bromuconazole 88 108 100 ±8

Butralin 90 111 100 ±7

Butylate 79 102 95 ±9

Captan 79 104 96 ±9

Carbaryl 85 119 105 ±12

Carbendazim** 73 98 81 ±13

Carbofuran 76 110 95 ±13

Chlorantraniliprole**96 113 106 ±5

Chlorothalonil 82 103 96 ±8

Chlorpyrifos 87 119 112 ±12

Chlorpyrifos 

oxon 

81 115 92 ±15

Clomazone 91 104 100 ±4

Clothianidin** 79 93 85 ±5

Coumaphos 85 114 92 ±12

Cyantraniliprole**94 111 102 ±6

Cyazofamid** 78 102 92 ±9

Cycloate 82 97 91 ±6

Cyfluthrin 97 104 100 ±3

Cyhalofop-butyl 85 102 95 ±7

Cyhalothrin 91 109 103 ±8

Cymoxanil** 71 83 72 ±6

Cypermethrin 85 115 91 ±11

Cyproconazole 91 106 103 ±6

Cyprodinil 77 107 88 ±12

3,4-Dichloroaniline**76 90 84 ±6

3,5-Dichloroaniline**73 90 80 ±7

Compound

Minimum 

recovery 

(percent)

Maximum 

recovery 

(percent)

Median 

recovery 

(percent)

Standard 

deviation

(percent)

DCPA 87 101 91 ±5

DCPMU** 75 97 89 ±11

DCPU** 75 99 83 ±10

Deltamethrin 93 113 100 ±6

Desthio-prothioconazole**83 118 97 ±10

Diazinon 94 113 100 ±7

Diazinon oxon 82 117 94 ±12

Difenconazole 91 107 93 ±6

Dimethomorph 90 108 102 ±7

Dinotefuran** 77 112 93 ±13

Dithiopyr 97 110 102 ±4

Diuron** 92 118 95 ±9

EPTC 71 107 91 ±16

Esfenvalerate 91 112 97 ±8

Ethaboxam** 75 102 93 ±10

Ethalfluralin 93 112 98 ±7

Etofenprox 85 107 91 ±10

Famoxadone 78 113 98 ±13

Fenamidone 93 104 98 ±4

Fenarimol 89 110 96 ±8

Fenbuconazole 92 120 101 ±9

Fenhexamide 81 116 96 ±13

Fenpropathrin 88 113 93 ±11

Fenpyroximate 88 113 101 ±9

Fenthion 83 155 97 ±27

Fipronil 95 110 105 ±5

Desulfinylfipronil 84 109 105 ±9

Desulfinylfipronil 

amide

88 110 105 ±9

Fipronil sulfide 93 105 100 ±5

Fipronil sulfone 87 102 94 ±5

Flonicamid** 72 100 77 ±14

Fluazinam 80 105 97 ±10

Fludioxinil 96 103 97 ±3

Flufenacet 91 114 95 ±9

Flumethralin 92 118 103 ±8

Fluopicolide 85 110 95 ±9

Fluoxastrobin 92 106 97 ±5

Fluridone** 89 112 102 ±7

Flusilazole 88 122 96 ±12

Flutolanil 100 116 105 ±5

Flutriafol 95 124 98 ±10
16 Pesticide Inputs to the Sacramento–San Joaquin Delta, 2015–16: Results from the Delta Regional Monitoring Program

Table 6. Minimum, maximum, and median recovery of compounds in pesticide matrix-spiked water samples with standard deviation.—

Continued

[Four spiked samples and three spiked replicate samples were analyzed by gas chromatography/mass spectrometry. Compounds noted with ** were analyzed in 

five spiked samples and three spiked replicate samples by liquid chromatography/tandem mass spectrometry. Abbreviation: ±, plus or minus]

Compound

Minimum 

recovery 

(percent)

Maximum 

recovery 

(percent)

Median 

recovery 

(percent)

Standard 

deviation

(percent)

Fluxapyroxad 90 101 97 ±4

Hexazinone 82 101 93 ±8

Imazalil 76 114 101 ±13

Imidacloprid** 77 106 89 ±12

Indoxacarb 80 110 103 ±12

Ipconazole 90 110 102 ±7

Iprodione 82 105 88 ±11

Kresoxim-methyl 91 101 96 ±4

Malathion 83 115 99 ±11

Malathion oxon 83 100 95 ±6

Mandipropamid**85 164 98 ±24

Metalaxyl 100 121 103 ±7

Metconazole 87 107 97 ±7

Methidathion 90 117 105 ±9

Methoprene 93 113 101 ±6

Methoxyfenozide**87 104 98 ±5

Methyl parathion 94 104 99 ±3

Metolachlor 95 104 98 ±3

Molinate 75 108 96 ±14

Myclobutanil 88 114 96 ±9

Napropamide 87 103 92 ±6

Novaluron 71 84 78 ±6

Oryzalin** 71 100 84 ±16

Oxydiazon 95 114 102 ±6

Oxyfluorfen 92 104 98 ±5

p,p’-DDD 86 101 95 ±5

p,p’-DDE 76 92 84 ±7

p,p’-DDT 87 100 93 ±6

Paclobutrazol 98 107 104 ±4

PCA 73 88 79 ±6

PCNB 88 105 97 ±7

Pebulate 79 106 84 ±12

Pendimethalin 96 111 100 ±6

Penoxsulam** 74 92 77 ±9

Permethrin 81 96 90 ±6

Phenothrin 79 97 92 ±7

Phosmet 94 101 97 ±3

Picoxystrobin 88 103 93 ±6

Compound

Minimum 

recovery 

(percent)

Maximum 

recovery 

(percent)

Median 

recovery 

(percent)

Standard 

deviation

(percent)

Piperonyl 

butoxide

90 103 95 ±4

Prodiamine 98 111 104 ±4

Prometon 72 112 96 ±17

Prometryn 89 119 92 ±11

Propanil 94 117 101 ±8

Propargite 84 106 100 ±9

Propiconazole 95 113 100 ±6

Propyzamide 86 117 102 ±11

Pyraclostrobin 73 92 84 ±9

Pyridaben 96 102 101 ±2

Pyrimethanil 91 107 101 ±6

Quinoxyfen 83 102 95 ±8

Resmethrin 80 104 98 ±11

Sedaxane 93 103 99 ±4

Simazine 85 110 101 ±9

Tau-fluvalinate 77 108 101 ±12

Tebuconazole 86 106 101 ±7

Tebupirimfos 90 107 99 ±6

Tebupirimfos 

oxon

87 146 93 ±20

Tefluthrin 70 85 79 ±6

Tetraconazole 91 119 98 ±9

Tetradifon 97 125 101 ±10

Tetramethrin 87 109 101 ±9

Thiabendazole** 71 99 81 ±11

Thiacloprid** 75 97 78 ±10

Thiamethoxam** 77 91 82 ±8

Thiazopyr 89 103 97 ±5

Thiobencarb 88 105 94 ±7

Tolfenpyrad** 84 118 96 ±12

Triadimefon 99 118 107 ±6

Triadimenol 89 119 97 ±12

Triallate 92 103 98 ±4

Tribufos 92 109 100 ±6

Trifloxystrobin 93 115 98 ±8

Triflumizole 96 115 106 ±6

Trifluralin 90 103 98 ±4

Triticonazole 91 118 96 ±9

Zoxamide 84 105 94 ±8
Results 17

Results

A total of 54 out of 154 pesticide compounds were detected 

in water samples collected during the study, and all samples 

contained multiple pesticides (table 7). A variety of pesticide 

types were detected in the water during the study period (19 fungicides, 18 herbicides, 9 insecticides, 7 breakdown products, and 

1 synergist). The most frequently detected compounds were the 

herbicide hexazinone (95 percent) and the fungicides boscalid 

(93 percent) and azoxystrobin (75 percent). Overall, 14 pesticides 

were detected in at least half of all samples. Pesticide concentrations ranged from below the MDLs to 2,630 nanograms per liter 

(ng/L) for the herbicide metolachlor.

Pesticide concentrations measured in suspended sediments 

filtered from surface water are presented in table 8. Pesticide 

concentrations in suspended-sediments filtered from 1-liter water 

samples are presented using surface water parameter codes and 

units to facilitate the approximation of a whole-water pesticide 

concentration (table 9). A total of 11 pesticide compounds were 

detected in the suspended sediments during the study period 

(6 herbicides, 3 insecticides, 1 fungicide, and 1 breakdown 

product). Overall, the most frequently detected pesticides in 

suspended sediments were the insecticides permethrin (7 percent) 

and bifenthrin (5 percent) and the herbicide pendimethalin 

(5 percent). Pesticide concentrations in the suspended sediments 

ranged from below the MDLs to 265 ng/L for the herbicide 

pendimethalin. Whole-water pesticide concentrations were 

calculated for compounds with at least one suspended-sediment 

detection (table 9).

Results for dissolved and suspended constituents measured 

at the NWQL are provided in table 10 and water quality measurements taken in the field are provided in table 11. Dissolved 

organic carbon was detected at concentrations from 1.59 to 

11.6 mg/L. Particulate inorganic carbon was detected above the 

MRL of 0.03 mg/L in five samples (8 percent) at concentrations 

from 0.03 to 0.14 mg/L. Particulate organic carbon was present 

in 60 samples (100 percent) at concentrations ranging from less

than 0.11 to 38.5 mg/L. Total particulate nitrogen was detected 

above the LT-MDL of 0.03 mg/L in 52 samples (87 percent) at 

concentrations from 0.031 to 4.59 mg/L. Dissolved copper was 

detected above the detection limit of 0.8 mg/L in 58 samples 

(97 percent) at concentrations ranging from 0.81 to 4.4 micrograms per liter (μg/L).

The data presented in this report are publicly available in 

the USGS National Water Information System web interface 

(U.S. Geological Survey, 2017). Results for this report were 

retrieved from NWIS and compiled in April 2017.

Mokelumne River at New Hope Road

A total of 32 pesticides (14 fungicides, 10 herbicides, 

4 insecticides, 3 breakdown products, and 1 synergist) were 

detected in water samples collected at this site; the most frequently detected compounds were boscalid (100 percent) and 

hexazinone (92 percent). The maximum pesticide concentration measured at this site was 247 ng/L (simazine) in a sample 

collected on March 7, 2016. A minimum of 2 (October 21, 

2015, May 18, 2016, and June 15, 2016) and a maximum of 

13 (March 7, 2016) pesticides or pesticide degradates were 

detected in each water sample (fig. 3). No pesticides or pesticide degradates were detected in the suspended sediments 

collected at this site. There were no pesticide detections at 

concentrations above EPA aquatic-life benchmarks at this site 

(U.S. Environmental Protection Agency, 2017).

Sacramento River at Hood

A total of 33 pesticides (11 herbicides, 11 fungicides, 

6 insecticides, 4 breakdown products, and 1 synergist) were 

detected in the water samples collected at this site. The 

fungicide azoxystrobin was detected in every sample, and an 

additional seven pesticides (hexazinone, 3,4-dichloroaniline, 

boscalid, diuron, piperonyl butoxide, carbendazim, and fipronil) were detected in at least half of the samples collected at 

this site. The maximum pesticide concentration measured at 

this site was 348 ng/L for azoxystrobin in the sample collected 

on August 18, 2015. A minimum of 6 (February 17, 2016) 

and a maximum of 15 (March 7, 2016) pesticides or pesticide 

degradates were detected in each water sample (fig. 3). Permethrin was detected in the suspended sediments of the sample 

collected on March 7, 2016, at a concentration of 19.2 ng/L. 

This was the only detection of pesticides on suspended sediments from this site.

Bifenthrin was detected in the water sample collected 

on August 18, 2015 (2.9 ng/L), at a concentration above the 

aquatic-life benchmark for chronic toxicity to invertebrates of 

1.3 ng/L (U.S. Environmental Protection Agency, 2017). The 

insecticide fipronil was detected at concentrations above the 

aquatic-life benchmark for chronic toxicity to invertebrates of 

11 ng/L in the samples collected on July 28, 2015 (25 ng/L), 

and November 10, 2015 (12.2 ng/L).
Table 7. Pesticide concentrations with measured detections in environmental water samples collected in the Sacramento–San Joaquin Delta, 2015–[Numbers in brackets are U.S. Geological Survey (USGS) National Water Information System (NWIS) parameter codes. Concentrations are in nanograms per liter. Abbreviatiohh:mm, hour:minute; mm/dd/yyyy, month/day/year; —, not detected; *, storm sample] Sample date (mm/dd/yyyy) Sample time (hh:mm) Acibenzolar- S-methyl [51849] Atrazine [65065] Azoxystrobin [66589] Bifenthrin [65067] Boscalid [67550] Carbaryl [65069] Carbendazim [68548] Chlorantraniliprole [51856] Chlorothalon

[65071] 

Mokelumne River at New Hope Road 07/28/2015 09:50 — — 54.4 — 10.4 — — — — 

08/18/2015 09:50 — — 115 — 21.2 — — — — 09/23/2015 09:20 — — 90.1 — 3.5 — 4.3 — E2.3 10/21/2015 09:10 — — — — 11.1 — — — — 

11/10/2015 10:00 — — — — 14.8 — E3.0 — — 

12/15/2015 14:00 — — — — E2.5 — 11.6 — — 

*01/19/2016 09:45 — — — — 9.2 — E3.1 E3.7 — 

02/17/2016 09:00 — — — — 4.8 — — — — 

*03/07/2016 13:30 — — — — 4.7 — 5.6 — — 

04/19/2016 09:20 — — 14.1 — 20.7 — — — 6.7 05/18/2016 09:30 — — — — 7.3 — — — — 06/15/2016 09:15 — — — — 6.4 — — — — 

Sacramento River at Hood 07/28/2015 08:45 — — 84.4 — 3.8 31.1 — — — 

08/18/2015 08:40 — — 348 2.9 7.5 — 20.6 — — 09/23/2015 08:30 — — 19.2 — — — 29.4 — E2.9 10/21/2015 08:00 — — 35.9 — 10.6 — 21.1 — — 

11/10/2015 09:00 — — 93.9 — 6.3 — 37.9 — — 

12/15/2015 15:00 — — 30.3 — — — 18.5 — — 

*01/19/2016 08:30 — — 32.6 — — — 4.2 4.4 — 

02/17/2016 08:00 — — 28.9 — — — — — — 

*03/07/2016 14:20 — — 7.3 — 3 — 4.4 — — 

04/19/2016 08:20 — — 15.3 — 13.4 — — — 6.8 05/18/2016 08:30 — — 11.8 — 7.2 — — — — 06/15/2016 08:10 — — 24.5 — 8.9 — — — — 

San Joaquin River at Buckley Cove 07/28/2015 11:10 — 49.3 58.1 — 34.1 — 61 5 — 

08/18/2015 11:10 — 21.4 118 — 46 — 58.6 9.3 — 09/23/2015 10:45 — 8.2 38 — 11.6 — 70.7 10.3 — 
Sample date 

(mm/dd/yyyy)

Sample 

time 

(hh:mm)

AcibenzolarS-methyl

[51849]

Atrazine

[65065]

Azoxystrobin

[66589]

Bifenthrin

[65067]

Boscalid

[67550]

Carbaryl

[65069]

Carbendazim

[68548]

Chlorantraniliprole

[51856]

Chlorothalon

[65071]

San Joaquin River at Buckley Cove—Continued

10/21/2015 10:50 — — 129 — 37.6 — 107 11 — 

11/10/2015 11:30 — — 66.7 — 28.1 — 33.4 E2.0 — 

12/15/2015 12:20 — — 14.1 — 6.9 — 20.3 4.7 — 

*01/19/2016 10:50 — — 11.9 — 118 — 50.1 21.1 — 

02/17/2016 10:10 — — 5.6 — 67.6 — 8.8 14.4 — 

*03/07/2016 10:15 — — 3.7 — 24.7 — 35 10.6 — 

04/19/2016 10:40 88.4 — 48.4 — 93.7 — — 8.9 — 05/18/2016 10:45 — — 14.7 — 14.6 — — — — 06/15/2016 10:50 — 40 33.2 — 28.6 — 7.1 — — 

San Joaquin River near Vernalis

07/28/2015 12:15 — 9.7 5.1 — 9.1 — — E3.9 — 08/18/2015 12:50 — 3.9 16 — 17.1 — — 4 — 09/23/2015 12:20 — — 24.5 — 3.7 — — 4.9 E3.4 10/21/2015 12:40 — — 37.7 — 13.4 — — 5.1 — 

11/10/2015 13:00 — — 22.2 — 17.9 — 9.2 — — 

12/15/2015 11:00 — — — — 3.8 — — E2.9 — 

*01/19/2016 12:30 — — 16.5 — 39.4 — 7.5 10.8 — 

02/17/2016 12:00 — — — — 27.5 — 7.6 7.3 — 

*03/07/2016 11:50 — — 4.2 — 21.8 — 40.7 6.5 — 

04/19/2016 12:45 23.7 — 27.9 — 49.7 — — 4.1 — 05/18/2016 12:20 — — 12.9 — 12.5 — — — — 06/15/2016 12:40 — — 14.6 — 15.5 — — — — 

Ulatis Creek at Browns Road

07/28/2015 14:20 — 14.6 34.7 — 32.6 — — 150 — 08/18/2015 15:00 — 5.9 104 — 47.5 — — 36.1 — 09/23/2015 14:15 — 4.1 5.9 — 10 — — 49.5 — 10/21/2015 15:00 — — 54.6 — 47.3 20.7 156 12.3 — 

11/10/2015 15:30 — 14.1 — 33.3 66.8 — — E2.3 — 

12/15/2015 08:50 — 6.3 — 13.2 23.5 — 57 E2.4 — 

Table 7. Pesticide concentrations with measured detections in environmental water samples collected in the Sacramento–San Joaquin Delta, 2015–[Numbers in brackets are U.S. Geological Survey (USGS) National Water Information System (NWIS) parameter codes. Concentrations are in nanograms per liter. Abbreviatiohh:mm, hour:minute; mm/dd/yyyy, month/day/year; —, not detected; *, storm sample]
Sample date (mm/dd/yyyy) Sample time (hh:mm) Acibenzolar- S-methyl [51849] Atrazine [65065] Azoxystrobin [66589] Bifenthrin [65067] Boscalid [67550] Carbaryl [65069] Carbendazim [68548] Chlorantraniliprole [51856] Chlorothalon

[65071] 

Ulatis Creek at Browns Road—Continued *01/19/2016 15:00 — — — — 82.1 — E4.0 25.9 — 

02/17/2016 14:10 — — — 11.5 46.2 — — E3.0 — 

*03/07/2016 08:30 — — 6.5 — 64.9 — 8 26.9 — 

04/19/2016 15:10 — 10.4 29.1 — 50.4 — — E2.5 — 05/18/2016 14:20 — — 14.5 — 20.3 — — 14.4 — 06/15/2016 14:40 — — — — 25.4 — — 260 — 

Sample date (mm/dd/yyyy) Sample time (hh:mm) Desulfinylfipronil [66607] Diazinon [65078] 3,4-Dichloroaniline [66584] 3,5-Dichloroaniline [67536] 3,4-Dichlorophenylurea [68226] N-(3,4-Dichlorophenyl)- N’-methylurea [68231] 

Mokelumne River at New Hope Road—Continued 07/28/2015 09:50 8.1 — 4.7 — — — 

08/18/2015 09:50 2.4 — 4.2 — — — 09/23/2015 09:20 — — 7.6 — — — 10/21/2015 09:10 — — — — — — 

11/10/2015 10:00 — — — — — — 

12/15/2015 14:00 — — — — — — 

*01/19/2016 09:45 — — — — — — 

02/17/2016 09:00 — — — — — — 

*03/07/2016 13:30 — 89.1 — — — E2.6 

04/19/2016 09:20 — — — — — — 05/18/2016 09:30 — — — — — — 06/15/2016 09:15 — — — — — — 

Sacramento River at Hood—Continued 07/28/2015 08:45 — — 10.5 — — — 

08/18/2015 08:40 — — 15.3 — — — 09/23/2015 08:30 — — 9 — — — 10/21/2015 08:00 — — 3.2 — — — 

11/10/2015 09:00 — — 7.8 — E2.6 4.1 

12/15/2015 15:00 — — 5.5 — — E2.0 

Table 7. Pesticide concentrations with measured detections in environmental water samples collected in the Sacramento–San Joaquin Delta, 2015–[Numbers in brackets are U.S. Geological Survey (USGS) National Water Information System (NWIS) parameter codes. Concentrations are in nanograms per liter. Abbreviatiohh:mm, hour:minute; mm/dd/yyyy, month/day/year; —, not detected; *, storm sample]
Sample date 

(mm/dd/yyyy)

Sample 

time 

(hh:mm)

Desulfinylfipronil

[66607]

Diazinon

[65078]

3,4-Dichloroaniline

[66584]

3,5-Dichloroaniline

[67536]

3,4-Dichlorophenylurea

[68226]

N-(3,4-Dichlorophenyl)-

N’-methylurea

[68231]

Sacramento River at Hood—Continued

*01/19/2016 08:30 — — 5.7 E1.6 E2.3 E2.9 

02/17/2016 08:00 — — — — — E2.0 

*03/07/2016 14:20 — — 21.1 — E2.2 9.4 

04/19/2016 08:20 — — — — — — 05/18/2016 08:30 — — E2.6 — — — 06/15/2016 08:10 — — 145 — — — 

San Joaquin River at Buckley Cove—Continued

07/28/2015 11:10 13.1 — 9.3 — 9.1 49.5 08/18/2015 11:10 4.9 — 6.2 — 10.3 39.4 09/23/2015 10:45 3.1 — 4.3 — 5.4 19.5 10/21/2015 10:50 4.7 — — — E2.9 8.4 

11/10/2015 11:30 2.1 — 3.2 — E2.5 3.5 

12/15/2015 12:20 2.7 — — — — 4.7 

*01/19/2016 10:50 — — 5 — 11.8 54.6 

02/17/2016 10:10 2.8 — 3.9 — 9.7 26.2 

*03/07/2016 10:15 — — 5.1 — 15.9 46.4 

04/19/2016 10:40 — 14.8 3.7 — 4.2 27.7 05/18/2016 10:45 — 5.3 — — — 5.5 06/15/2016 10:50 — — 53.1 — 3.8 11.7 

San Joaquin River near Vernalis—Continued

07/28/2015 12:15 — — E1.6 — — E2.4 08/18/2015 12:50 — — — — — — 09/23/2015 12:20 — — — — — — 10/21/2015 12:40 — — — — — — 

11/10/2015 13:00 — — — — — — 

12/15/2015 11:00 — — — — — 8.2 

*01/19/2016 12:30 — 7.2 E3.1 — 9.2 27.6 

02/17/2016 12:00 — — E3.0 — — 9.9 

*03/07/2016 11:50 — — 3.5 E3.2 8.1 21.9 

Table 7. Pesticide concentrations with measured detections in environmental water samples collected in the Sacramento–San Joaquin Delta, 2015–[Numbers in brackets are U.S. Geological Survey (USGS) National Water Information System (NWIS) parameter codes. Concentrations are in nanograms per liter. Abbreviatiohh:mm, hour:minute; mm/dd/yyyy, month/day/year; —, not detected; *, storm sample]
Sample date (mm/dd/yyyy) Sample time (hh:mm) Desulfinylfipronil [66607] Diazinon [65078] 3,4-Dichloroaniline [66584] 3,5-Dichloroaniline [67536] 3,4-Dichlorophenylurea [68226] N-(3,4-Dichlorophenyl)- N’-methylurea [68231] 

San Joaquin River near Vernalis—Continued 04/19/2016 12:45 — — E2.5 — E2.9 10.8 

05/18/2016 12:20 — 6 — — — — 06/15/2016 12:40 — — 5 — — — 

Ulatis Creek at Browns Road—Continued 07/28/2015 14:20 — — E2.9 — — 4.4 

08/18/2015 15:00 — — E2.1 — — 4 09/23/2015 14:15 — — — — — — 10/21/2015 15:00 5.3 — — — 3.6 6.6 

11/10/2015 15:30 2.7 — 4 — — E2.2 

12/15/2015 08:50 3.2 — E2.2 — — 5.4 

*01/19/2016 15:00 — — — — — 7 

02/17/2016 14:10 — — 3.6 — 5.3 3.8 

*03/07/2016 08:30 — 44.2 — — — 5.4 

04/19/2016 15:10 — — 4.2 — 3.4 18.7 05/18/2016 14:20 — — E2.2 — — 3.5 06/15/2016 14:40 — — 6.1 — — — 

Sample date (mm/dd/yyyy) Sample time (hh:mm) Fenhexamid [67622] Fipronil sulfide [66610] Fipronil sulfone [66613] Fipronil [66604] Fluridone [51864] Flusilazole [67649] Fluxapyroxad [51851] Hexazinone [65085] Imazalil [67662] Imidaclopr

[68426] 

Mokelumne River at New Hope Road—Continued 07/28/2015 09:50 — — — — 4 — 4.8 40.7 — — 

08/18/2015 09:50 — — — — 4.3 — 23.5 20.3 — — 09/23/2015 09:20 17.3 — — — — — — 11.5 119 — 10/21/2015 09:10 — — — — — — — 13.6 — — 

11/10/2015 10:00 — — — 3.1 — — E3.4 15.9 — — 

12/15/2015 14:00 — — — — — — — E5.8 — — 

*01/19/2016 09:45 — — — — — — — E7.9 — — 

02/17/2016 09:00 — — — — — — — — — — 

*03/07/2016 13:30 — — — — — — E2.7 E4.2 — — 

Table 7. Pesticide concentrations with measured detections in environmental water samples collected in the Sacramento–San Joaquin Delta, 2015–[Numbers in brackets are U.S. Geological Survey (USGS) National Water Information System (NWIS) parameter codes. Concentrations are in nanograms per liter. Abbreviatiohh:mm, hour:minute; mm/dd/yyyy, month/day/year; —, not detected; *, storm sample]
Sample date 

(mm/dd/yyyy)

Sample time 

(hh:mm)

Fenhexamid

[67622]

Fipronil 

sulfide

[66610]

Fipronil 

sulfone

[66613]

Fipronil

[66604]

Fluridone

[51864]

Flusilazole

[67649]

Fluxapyroxad

[51851]

Hexazinone

[65085]

Imazalil

[67662]

Imidaclopr

[68426]

Mokelumne River at New Hope Road—Continued

04/19/2016 09:20 — — — — — — 6.8 17.7 — — 05/18/2016 09:30 — — — — — — — 9.9 — — 06/15/2016 09:15 — — — — — — — 11.8 — — 

Sacramento River at Hood—Continued

07/28/2015 08:45 — — — 25 — — — 43.8 — — 08/18/2015 08:40 — — — 6.9 4.5 — E2.0 22.9 — E2.3 09/23/2015 08:30 8.5 — — — — — — 11.6 100 — 10/21/2015 08:00 — — — 4.4 — — — 20 — — 

11/10/2015 09:00 — — — 12.2 — — — 27.2 — E1.9 

12/15/2015 15:00 — — — — — — — E8.2 — — 

*01/19/2016 08:30 — — — — — 7.5 — 9 — — 

02/17/2016 08:00 28.1 — — — — — — E7.0 — E2.2 

*03/07/2016 14:20 — — — — — — — — — 9.3 

04/19/2016 08:20 — — — 4.6 — — — 19.4 — — 05/18/2016 08:30 — — — — — — — 14.8 — — 06/15/2016 08:10 — — — 3.1 — — — 17.5 — — 

San Joaquin River at Buckley Cove—Continued

07/28/2015 11:10 — 10.8 12.2 13.5 383 — 15.4 132 — E3.2 08/18/2015 11:10 — 4.6 3.9 — 293 — 32.4 94.8 — 5.2 09/23/2015 10:45 — 3 — — 165 — 22.6 39 — 9.7 10/21/2015 10:50 — — — — 57 — 35.8 33 — — 

11/10/2015 11:30 — — — E1.8 9.6 — 21.7 19.2 — — 

12/15/2015 12:20 — — — — 23.4 — — E8.3 — 4.6 

*01/19/2016 10:50 — — — 3.4 11.3 — 10 30.7 — 17.8 

02/17/2016 10:10 — — — — 16.3 — 11.4 13.5 — 8.9 

*03/07/2016 10:15 — — — — 25.6 — E4.7 16.6 — 7.2 

04/19/2016 10:40 — — — 4.4 230 — 57.7 54.5 — 60.1 05/18/2016 10:45 — — — — 208 — 7.2 10.3 — 13.7 06/15/2016 10:50 — — — — 213 — 11.1 21.2 — 7.3 

Table 7. Pesticide concentrations with measured detections in environmental water samples collected in the Sacramento–San Joaquin Delta, 2015–[Numbers in brackets are U.S. Geological Survey (USGS) National Water Information System (NWIS) parameter codes. Concentrations are in nanograms per liter. Abbreviatiohh:mm, hour:minute; mm/dd/yyyy, month/day/year; —, not detected; *, storm sample]
Sample date (mm/dd/yyyy) Sample time (hh:mm) Fenhexamid [67622] Fipronil sulfide [66610] Fipronil sulfone [66613] Fipronil [66604] Fluridone [51864] Flusilazole [67649] Fluxapyroxad [51851] Hexazinone [65085] Imazalil [67662] Imidaclopr

[68426] 

San Joaquin River near Vernalis—Continued 07/28/2015 12:15 — — — — 4.4 — — 38.8 — — 

08/18/2015 12:50 — — — — — — 5.8 22.9 — — 09/23/2015 12:20 — — — — — — — 11.4 — — 10/21/2015 12:40 — — — — — — E4.0 12.9 — — 

11/10/2015 13:00 — — — E2.4 — — 6.6 10.9 — — 

12/15/2015 11:00 12.1 — — — — — — 8.9 — E2.9 

*01/19/2016 12:30 — — — E2.1 — 12.7 — 46.4 — 12.4 

02/17/2016 12:00 — — — — E2.4 — 6.3 9.5 — 4.3 

*03/07/2016 11:50 — — — — E2.7 — E4.3 17.9 — 8.3 

04/19/2016 12:45 — — — — E2.5 — 24.7 33.5 — 11.1 05/18/2016 12:20 — — — — — — 6.9 8.7 — — 06/15/2016 12:40 — — — — — — 7.9 11.7 — — 

Ulatis Creek at Browns Road—Continued 07/28/2015 14:20 — — — — 11.6 — 14.8 67.8 — 12.6 

08/18/2015 15:00 — — — — 6.7 — 32.6 72.2 — 4.6 09/23/2015 14:15 — — — — 4.5 — E2.7 — — 3.9 10/21/2015 15:00 — — — 13.4 5.4 — 13.8 32.9 — 30 

11/10/2015 15:30 — — 4.7 3.8 E2.1 — 13.3 41.4 — 16 

12/15/2015 08:50 73.1 — 4.6 4.1 — — — 14.1 — 21.9 

*01/19/2016 15:00 — — — 11 — — — 32.2 — 19.5 

02/17/2016 14:10 — — — — E2.0 — — 13.2 — 17.8 

*03/07/2016 08:30 — — 4.8 4 23.3 — 71.4 2,270 — 19.5 

04/19/2016 15:10 — — — — 95.8 — 15.2 78.2 — 9.6 05/18/2016 14:20 — — — — 12.7 — 7.6 112 — 7.8 06/15/2016 14:40 — — — — 3.8 — — 86.6 — 6.4 

Table 7. Pesticide concentrations with measured detections in environmental water samples collected in the Sacramento–San Joaquin Delta, 2015–[Numbers in brackets are U.S. Geological Survey (USGS) National Water Information System (NWIS) parameter codes. Concentrations are in nanograms per liter. Abbreviatiohh:mm, hour:minute; mm/dd/yyyy, month/day/year; —, not detected; *, storm sample]
Sample date 

(mm/dd/yyyy)

Sample 

time 

(hh:mm)

Metalaxyl

[68437]

Methoxyfenozide

[68647]

Metolachlor

[65090]

Myclobutanil

[66632]

Oryzalin

[68663]

Oxadiazon

[51843]

Oxyfluorfen

[65093]

Pendimethalin

[65098]

Penoxsula

[51863]

Mokelumne River at New Hope Road—Continued

07/28/2015 09:50 — 3.2 14.2 — — — — — — 08/18/2015 09:50 — 11.8 8 15.2 — — — — — 09/23/2015 09:20 — — 4.4 — — — — — — 10/21/2015 09:10 — — — — — — — — — 

11/10/2015 10:00 — — — — — — — — — 

12/15/2015 14:00 — — — — — — 7.7 — — 

*01/19/2016 09:45 — — — — — — 16.7 17.7 — 

02/17/2016 09:00 — — — — — — — — — 

*03/07/2016 13:30 — 6.4 — — E2.6 — 6.3 — — 

04/19/2016 09:20 — — — — — — — — — 05/18/2016 09:30 — — — — — — — — — 06/15/2016 09:15 — — — — — — — — — 

Sacramento River at Hood—Continued

07/28/2015 08:45 — — 13.2 — — — — — — 08/18/2015 08:40 — — 3.9 — — — — — — 09/23/2015 08:30 — — — — — — — — — 10/21/2015 08:00 — — — — — — — — — 

11/10/2015 09:00 — — — — — — — — — 

12/15/2015 15:00 — — — — — — 3.8 — — 

*01/19/2016 08:30 — 3.2 — — — — — — — 

02/17/2016 08:00 — — — — — — — — — 

*03/07/2016 14:20 — — 13.6 — 25 — — — — 

04/19/2016 08:20 — — — — — — — — — 05/18/2016 08:30 — — 5.9 — — — — — — 06/15/2016 08:10 — — 7.1 — — — — — — 

San Joaquin River at Buckley Cove—Continued

07/28/2015 11:10 — 47 143 — — — — — — 08/18/2015 11:10 — 48.8 94.5 — — — — — — 09/23/2015 10:45 — 63.9 43.3 — — — — — — 

Table 7. Pesticide concentrations with measured detections in environmental water samples collected in the Sacramento–San Joaquin Delta, 2015–[Numbers in brackets are U.S. Geological Survey (USGS) National Water Information System (NWIS) parameter codes. Concentrations are in nanograms per liter. Abbreviatiohh:mm, hour:minute; mm/dd/yyyy, month/day/year; —, not detected; *, storm sample]
Sample date (mm/dd/yyyy) Sample time (hh:mm) Metalaxyl [68437] Methoxyfenozide [68647] Metolachlor [65090] Myclobutanil [66632] Oryzalin [68663] Oxadiazon [51843] Oxyfluorfen [65093] Pendimethalin [65098] Penoxsula

[51863] 

San Joaquin River at Buckley Cove—Continued 10/21/2015 10:50 — 55.8 16.5 — — — — — — 

11/10/2015 11:30 — 8.1 12.2 — — — — — — 

12/15/2015 12:20 — 15.7 7 — — — — — — 

*01/19/2016 10:50 36.9 254 16.2 15.9 17.5 7.7 68.2 53.8 — 

02/17/2016 10:10 — 85.4 10.8 — E4.7 9.8 — — — 

*03/07/2016 10:15 — 45.2 42.8 — 16.7 11.5 211 33.4 — 

04/19/2016 10:40 — 74.3 55.6 — 15.1 — — — — 05/18/2016 10:45 — 11.5 42.6 — — — — — — 06/15/2016 10:50 — 21.7 83.5 — — — — 14.4 — 

San Joaquin River near Vernalis—Continued 07/28/2015 12:15 — 18.9 30.8 — — — — — — 

08/18/2015 12:50 — 10.5 5.9 — — — — — — 09/23/2015 12:20 — 16.6 — — — — — — — 10/21/2015 12:40 — 13.8 3.5 — — — — — — 

11/10/2015 13:00 — 5.2 6.4 — — — — — — 

12/15/2015 11:00 — 8.5 — — — — — — — 

*01/19/2016 12:30 — 67.2 28.3 — 8.7 — 22.6 46 — 

02/17/2016 12:00 — 28.2 — — — — — — — 

*03/07/2016 11:50 — 36 12.6 — 10.1 — — 28.9 — 

04/19/2016 12:45 — 14 9 — — — — — — 05/18/2016 12:20 — 7.6 11.8 — — — — — — 06/15/2016 12:40 — 22.8 14.8 — — — — — — 

Ulatis Creek at Browns Road—Continued 07/28/2015 14:20 — 3.8 140 — — — — — — 

08/18/2015 15:00 — 5.3 63 — — — — — — 09/23/2015 14:15 17 — — — — — — — — 10/21/2015 15:00 — 9 14.5 — — — — — — 

11/10/2015 15:30 — — 20.9 — — — — — — 

12/15/2015 08:50 — — — — — — 29.7 — E3.1 

Table 7. Pesticide concentrations with measured detections in environmental water samples collected in the Sacramento–San Joaquin Delta, 2015–[Numbers in brackets are U.S. Geological Survey (USGS) National Water Information System (NWIS) parameter codes. Concentrations are in nanograms per liter. Abbreviatiohh:mm, hour:minute; mm/dd/yyyy, month/day/year; —, not detected; *, storm sample]
Sample date 

(mm/dd/yyyy)

Sample 

time 

(hh:mm)

Metalaxyl

[68437]

Methoxyfenozide

[68647]

Metolachlor

[65090]

Myclobutanil

[66632]

Oryzalin

[68663]

Oxadiazon

[51843]

Oxyfluorfen

[65093]

Pendimethalin

[65098]

Penoxsula

[51863]

Ulatis Creek at Browns Road—Continued

*01/19/2016 15:00 — 23.9 114 — 72.6 11 — 99.6 — 

02/17/2016 14:10 — — — — — — 37.9 — — 

*03/07/2016 08:30 — 9.4 57.2 — 18.7 50.4 25.7 205 — 

04/19/2016 15:10 — — 9.1 — — — 6.3 33.6 E3.0 05/18/2016 14:20 — — 2,630 — — — — — — 06/15/2016 14:40 — — 178 — 10.9 — 25.8 — — 

Sample date 

(mm/dd/yyyy)

Sample 

time 

(hh:mm)

Prometryn

[65103]

Propanil

[66641]

Propiconazole

[66643]

Pyrimethanil

[67717]

Quinoxyfen

[51847]

Simazine

[65105]

Tetraconazole

[66654]

Thiabendazole

[67161]

Thiamethoxam

[68245]

Mokelumne River at New Hope Road—Continued

07/28/2015 09:50 — — — E2.0 — — — — — 08/18/2015 09:50 — — — E2.3 — — — — — 09/23/2015 09:20 — — — — — — — — — 10/21/2015 09:10 — — — — — — — — — 

11/10/2015 10:00 — — — — — — — — — 

12/15/2015 14:00 — — — — — E4.5 — — — 

*01/19/2016 09:45 — — — — — 19.9 E5.2 — — 

02/17/2016 09:00 — — — — — — — — — 

*03/07/2016 13:30 — — — — — 247 — — — 

04/19/2016 09:20 — — — 4.9 4.2 E4.3 7.5 — — 05/18/2016 09:30 — — — — — — — — — 06/15/2016 09:15 — — — — — — — — — 

Sacramento River at Hood—Continued

07/28/2015 08:45 — 38.8 — — — — — — — 08/18/2015 08:40 — — — — — — — — — 09/23/2015 08:30 — — — — — — — — — 10/21/2015 08:00 — — — — — — — — — 

11/10/2015 09:00 — — — — — — — — — 

12/15/2015 15:00 — — — — — — — — — 

Table 7. Pesticide concentrations with measured detections in environmental water samples collected in the Sacramento–San Joaquin Delta, 2015–[Numbers in brackets are U.S. Geological Survey (USGS) National Water Information System (NWIS) parameter codes. Concentrations are in nanograms per liter. Abbreviatiohh:mm, hour:minute; mm/dd/yyyy, month/day/year; —, not detected; *, storm sample]
Sample date (mm/dd/yyyy) Sample time (hh:mm) Prometryn [65103] Propanil [66641] Propiconazole [66643] Pyrimethanil [67717] Quinoxyfen [51847] Simazine [65105] Tetraconazole [66654] Thiabendazole [67161] Thiamethoxam [68245] 

Sacramento River at Hood—Continued *01/19/2016 08:30 — — — — — 5.9 — — — 

02/17/2016 08:00 — — — — — — — — — 

*03/07/2016 14:20 — — E3.5 — — 23.9 — — — 

04/19/2016 08:20 — — — — — E3.5 — — — 05/18/2016 08:30 — — — — — — — — — 06/15/2016 08:10 — 27.6 — — — — — — — 

San Joaquin River at Buckley Cove—Continued 07/28/2015 11:10 — — — E2.6 — 53.5 — — — 

08/18/2015 11:10 — — — E3.0 — 26 — E3.1 — 09/23/2015 10:45 — — — — — 6.9 — — 3.4 10/21/2015 10:50 — — — — — 6.5 — — — 

11/10/2015 11:30 — — — — — E4.2 — — — 

12/15/2015 12:20 — — — — — E4.9 — E3.0 — 

*01/19/2016 10:50 — — — — — 387 — — — 

02/17/2016 10:10 — — — — — 131 — — — 

*03/07/2016 10:15 — — — E2.0 — 192 — — — 

04/19/2016 10:40 — — 38.7 — — 39.4 — 7.0 — 05/18/2016 10:45 — — — — — 5.9 — 5.5 — 06/15/2016 10:50 — — — — — 16.5 — — — 

San Joaquin River near Vernalis—Continued 07/28/2015 12:15 — — — — — 17 — — — 

08/18/2015 12:50 — — — — — 5.3 — — — 09/23/2015 12:20 — — — — — E3.3 — — — 10/21/2015 12:40 — — — — — — — — — 

11/10/2015 13:00 — — 23.5 — — 7.3 — — — 

12/15/2015 11:00 — — — — — 8.4 — — — 

*01/19/2016 12:30 — — 23.4 — — 30.6 11.6 — — 

02/17/2016 12:00 — — 16.4 — — 23.8 — — — 

*03/07/2016 11:50 — — E4.8 — — 21.6 — — — 

Table 7. Pesticide concentrations with measured detections in environmental water samples collected in the Sacramento–San Joaquin Delta, 2015–[Numbers in brackets are U.S. Geological Survey (USGS) National Water Information System (NWIS) parameter codes. Concentrations are in nanograms per liter. Abbreviatiohh:mm, hour:minute; mm/dd/yyyy, month/day/year; —, not detected; *, storm sample]
Sample date 

(mm/dd/yyyy)

Sample 

time 

(hh:mm)

Prometryn

[65103]

Propanil

[66641]

Propiconazole

[66643]

Pyrimethanil

[67717]

Quinoxyfen

[51847]

Simazine

[65105]

Tetraconazole

[66654]

Thiabendazole

[67161]

Thiamethoxam

[68245]

San Joaquin River near Vernalis—Continued

04/19/2016 12:45 10.2 — 23.5 — — 10.2 — — — 05/18/2016 12:20 — — — — — — — — — 06/15/2016 12:40 — — — — — — — — — 

Ulatis Creek at Browns Road—Continued

07/28/2015 14:20 — — — — — 54.5 — — — 08/18/2015 15:00 — — — E2.4 — 29.5 — E2.7 — 09/23/2015 14:15 — — — — — 13.5 — — — 10/21/2015 15:00 — — — — — — — — — 

11/10/2015 15:30 — — — — — 9.5 — — — 

12/15/2015 08:50 — — — — — — — 3.9 — 

*01/19/2016 15:00 — — 34 — — 6.9 10.3 — — 

02/17/2016 14:10 — — — — — 15.3 — 4 — 

*03/07/2016 08:30 — — 24.8 — — 209 — — — 

04/19/2016 15:10 — — 35.1 — — 12.6 — E2.3 — 05/18/2016 14:20 — — — — — 159 — — 25.7 06/15/2016 14:40 — — — — — 16.2 — — — 

Table 7. Pesticide concentrations with measured detections in environmental water samples collected in the Sacramento–San Joaquin Delta, 2015–[Numbers in brackets are U.S. Geological Survey (USGS) National Water Information System (NWIS) parameter codes. Concentrations are in nanograms per liter. Abbreviatiohh:mm, hour:minute; mm/dd/yyyy, month/day/year; —, not detected; *, storm sample]
Table 8. Pesticide concentrations with measured detections in suspended sediments filtered from environmental water samples collected in the SaDelta, 2015–16. [Numbers in brackets are U.S. Geological Survey (USGS) National Water Information System (NWIS) parameter codes. Concentrations are in nanogram per liter. Abbreviationhh:mm, hour:minute; mm/dd/yyyy, month/day/year; —, not detected; *, storm sample] Sample date (mm/dd/yyyy) Sample time (hh:mm) Bifenthrin [65067] Cyhalothrin (all isomers) [68354] DCPA [65076] Dithiopyr [51837] Metalaxyl [68437] Metolachlor [65090] Oxyfluorfen [65093] p,p’-DDE [65095] Pendimethalin [65098] 

Mokelumne River at New Hope Road 07/28/2015 09:50 — — — — — — — — — 

08/18/2015 09:50 — — — — — — — — — 09/23/2015 09:20 — — — — — — — — — 10/21/2015 09:10 — — — — — — — — — 

11/10/2015 10:00 — — — — — — — — — 

12/15/2015 14:00 — — — — — — — — — 

*01/19/2016 09:45 — — — — — — — — — 

02/17/2016 09:00 — — — — — — — — — 

*03/07/2016 13:30 — — — — — — — — — 

04/19/2016 09:20 — — — — — — — — — 05/18/2016 09:30 — — — — — — — — — 06/15/2016 09:15 — — — — — — — — — 

Sacramento River at Hood 07/28/2015 08:45 — — — — — — — — — 

08/18/2015 08:40 — — — — — — — — — 09/23/2015 08:30 — — — — — — — — — 10/21/2015 08:00 — — — — — — — — — 

11/10/2015 09:00 — — — — — — — — — 

12/15/2015 15:00 — — — — — — — — — 

*01/19/2016 08:30 — — — — — — — — — 

02/17/2016 08:00 — — — — — — — — — 

*03/07/2016 14:20 — — — — — — — — — 

04/19/2016 08:20 — — — — — — — — — 05/18/2016 08:30 — — — — — — — — — 06/15/2016 08:10 — — — — — — — — — 
Sample date 

(mm/dd/yyyy)

Sample time 

(hh:mm)

Bifenthrin

[65067]

Cyhalothrin 

(all isomers)

[68354]

DCPA

[65076]

Dithiopyr

[51837]

Metalaxyl

[68437]

Metolachlor

[65090]

Oxyfluorfen

[65093]

p,p’-DDE

[65095]

Pendimethalin

[65098]

San Joaquin River at Buckley Cove

07/28/2015 11:10 — — — — — — — — — 08/18/2015 11:10 — — — — — — — — — 09/23/2015 10:45 — — — — — — — — — 10/21/2015 10:50 — — — — — — — — — 

11/10/2015 11:30 — — — — — — — — — 

12/15/2015 12:20 — — — — — — — — — 

*01/19/2016 10:50 — — — — — — — — 51.1 

02/17/2016 10:10 — — — — — — — — — 

*03/07/2016 10:15 — — — — — — — — — 

04/19/2016 10:40 — — — — — — — — — 05/18/2016 10:45 — — — — — — — — — 06/15/2016 10:50 — — — — — — — — — 

San Joaquin River near Vernalis

07/28/2015 12:15 — — — — — — — — — 08/18/2015 12:50 — — — — — — — — — 09/23/2015 12:20 — — — — — — — — — 10/21/2015 12:40 — — — — — — — — — 

11/10/2015 13:00 — — — — — — — — — 

12/15/2015 11:00 — — — — — — — — — 

*01/19/2016 12:30 — — 86.8 — E1.0 — — — 27.5 

02/17/2016 12:00 — — — — — — — — — 

*03/07/2016 11:50 — — — — — — — — — 

04/19/2016 12:45 4.3 — — — — — — — — 05/18/2016 12:20 — — — — — — — — — 06/15/2016 12:40 — — — — — — — — — 

Table 8. Pesticide concentrations with measured detections in suspended sediments filtered from environmental water samples collected in the SaDelta, 2015–16.—Continued[Numbers in brackets are U.S. Geological Survey (USGS) National Water Information System (NWIS) parameter codes. Concentrations are in nanogram per liter. Abbreviationhh:mm, hour:minute; mm/dd/yyyy, month/day/year; —, not detected; *, storm sample]
Sample date (mm/dd/yyyy) Sample time (hh:mm) Bifenthrin [65067] Cyhalothrin (all isomers) [68354] DCPA [65076] Dithiopyr [51837] Metalaxyl [68437] Metolachlor [65090] Oxyfluorfen [65093] p,p’-DDE [65095] Pendimethalin [65098] 

Ulatis Creek at Browns Road 07/28/2015 14:20 — — — — — — — — — 

08/18/2015 15:00 — — — — — — — — — 09/23/2015 14:15 — — — — — — — — — 10/21/2015 15:00 — — — — — — — — — 

11/10/2015 15:30 — — — — — — — — — 

12/15/2015 08:50 — — — — — — — — — 

*01/19/2016 15:00 19 — — 9.6 — — 23.2 5.6 265 

02/17/2016 14:10 — — — — — — — — — 

*03/07/2016 08:30 3.5 15.2 — — — — — — — 

04/19/2016 15:10 — — — — — — E2.9 — — 05/18/2016 14:20 — — — — — 17.8 — — — 06/15/2016 14:40 — — — — — 4.1 — — — 

Table 8. Pesticide concentrations with measured detections in suspended sediments filtered from environmental water samples collected in the SaDelta, 2015–16.—Continued [Numbers in brackets are U.S. Geological Survey (USGS) National Water Information System (NWIS) parameter codes. Concentrations are in nanogram per liter. Abbreviationhh:mm, hour:minute; mm/dd/yyyy, month/day/year; —, not detected; *, storm sample]
Table 9. Whole water pesticide concentrations for all compounds with detections in water and suspended sediment filtered from environmental waSacramento–San Joaquin Delta, 2015–16.[Table contains concentrations for all compounds with at least one detection in the suspended sediment filtered from environmental water. The whole water concentration is the sconcentration and the dissolved concentration. Numbers in brackets are U.S. Geological Survey (USGS) National Water Information System (NWIS) parameter codes. Concentr(ng/L). Whole water concentrations are listed in bold. Abbreviations: E, estimated; hh:mm, hour:minute; mm/dd/yyyy, month/day/year; —, not detected; *, storm sample]

Sample date 

(mm/dd/yyyy)

Sample 

time 

(hh:mm)

Bifenthrin 

[65067]

Cyhalothrin 

(all isomers) 

[68354]

DCPA 

[65076]

Suspended 

sediment Dissolved Whole water Suspended sediment Dissolved Whole water Suspended sediment Dissolved Whole water Suspen

sedim

Mokelumne River at New Hope Road

07/28/2015 09:50 — — — — — — — — — — 08/18/2015 09:50 — — — — — — — — — — 09/23/2015 09:20 — — — — — — — — — — 10/21/2015 09:10 — — — — — — — — — — 

11/10/2015 10:00 — — — — — — — — — — 

12/15/2015 14:00 — — — — — — — — — — 

*01/19/2016 09:45 — — — — — — — — — — 

02/17/2016 09:00 — — — — — — — — — — 

*03/07/2016 13:30 — — — — — — — — — — 

04/19/2016 09:20 — — — — — — — — — — 05/18/2016 09:30 — — — — — — — — — — 06/15/2016 09:15 — — — — — — — — — — 

Sacramento River at Hood

07/28/2015 08:45 — — — — — — — — — — 08/18/2015 08:40 — 2.9 2.9 — — — — — — — 09/23/2015 08:30 — — — — — — — — — — 10/21/2015 08:00 — — — — — — — — — — 

11/10/2015 09:00 — — — — — — — — — — 

12/15/2015 15:00 — — — — — — — — — — 

*01/19/2016 08:30 — — — — — — — — — — 

02/17/2016 08:00 — — — — — — — — — — 

*03/07/2016 14:20 — — — — — — — — — — 

04/19/2016 08:20 — — — — — — — — — — 05/18/2016 08:30 — — — — — — — — — — 06/15/2016 08:10 — — — — — — — — — — 
Sample date (mm/dd/yyyy) Sample time (hh:mm) Bifenthrin [65067] Cyhalothrin (all isomers) [68354] DCPA [65076] 

Suspended sediment Dissolved Whole water Suspended sediment Dissolved Whole water Suspended sediment Dissolved Whole water Suspen

sedim

San Joaquin River at Buckley Cove 07/28/2015 11:10 — — — — — — — — — — 

08/18/2015 11:10 — — — — — — — — — — 09/23/2015 10:45 — — — — — — — — — — 10/21/2015 10:50 — — — — — — — — — — 

11/10/2015 11:30 — — — — — — — — — — 

12/15/2015 12:20 — — — — — — — — — — 

*01/19/2016 10:50 — — — — — — — — — — 

02/17/2016 10:10 — — — — — — — — — — 

*03/07/2016 10:15 — — — — — — — — — — 

04/19/2016 10:40 — — — — — — — — — — 05/18/2016 10:45 — — — — — — — — — — 06/15/2016 10:50 — — — — — — — — — — 

San Joaquin River near Vernalis 07/28/2015 12:15 — — — — — — — — — — 

08/18/2015 12:50 — — — — — — — — — — 09/23/2015 12:20 — — — — — — — — — — 10/21/2015 12:40 — — — — — — — — — — 

11/10/2015 13:00 — — — — — — — — — — 

12/15/2015 11:00 — — — — — — — — — — 

*01/19/2016 12:30 — — — — — — 86.8 — 86.8 — 

02/17/2016 12:00 — — — — — — — — — — 

*03/07/2016 11:50 — — — — — — — — — — 

04/19/2016 12:45 4.3 — 4.3 — — — — — — — 05/18/2016 12:20 — — — — — — — — — — 06/15/2016 12:40 — — — — — — — — — — 

Table 9. Whole water pesticide concentrations for all compounds with detections in water and suspended sediment filtered from environmental waSacramento–San Joaquin Delta, 2015–16.—Continued [Table contains concentrations for all compounds with at least one detection in the suspended sediment filtered from environmental water. The whole water concentration is the sconcentration and the dissolved concentration. Numbers in brackets are U.S. Geological Survey (USGS) National Water Information System (NWIS) parameter codes. Concentr(ng/L). Whole water concentrations are listed in bold. Abbreviations: E, estimated; hh:mm, hour:minute; mm/dd/yyyy, month/day/year; —, not detected; *, storm sample]
Sample date 

(mm/dd/yyyy)

Sample 

time 

(hh:mm)

Bifenthrin 

[65067]

Cyhalothrin 

(all isomers) 

[68354]

DCPA 

[65076]

Suspended 

sediment Dissolved Whole water Suspended sediment Dissolved Whole water Suspended sediment Dissolved Whole water Suspen

sedim

Ulatis Creek at Browns Road

07/28/2015 14:20 — — — — — — — — — — 08/18/2015 15:00 — — — — — — — — — — 09/23/2015 14:15 — — — — — — — — — — 10/21/2015 15:00 — — — — — — — — — — 

11/10/2015 15:30 — 33.3 33.3 — — — — — — — 

12/15/2015 08:50 — 13.2 13.2 — — — — — — — 

*01/19/2016 15:00 19 — 19 — — — — — — 9.

02/17/2016 14:10 — 11.5 11.5 — — — — — — — 

*03/07/2016 08:30 3.5 — 3.5 15.2 — 15.2 — — — — 

04/19/2016 15:10 — — — — — — — — — — 05/18/2016 14:20 — — — — — — — — — — 06/15/2016 14:40 — — — — — — — — — — 

Sample date 

(mm/dd/yyyy)

Sample 

time 

(hh:mm)

Metalaxyl 

[68437]

Metolachlor 

[65090]

Oxyfluorfen 

[65093]

Suspended 

sediment Dissolved Whole water Suspended sediment Dissolved Whole water Suspended sediment Dissolved Whole water Suspend

sedime

Mokelumne River at New Hope Road—Continued

07/28/2015 09:50 — — — — 14.2 14.2 — — — — 08/18/2015 09:50 — — — — 8 8 — — — — 09/23/2015 09:20 — — — — 4.4 4.4 — — — — 10/21/2015 09:10 — — — — — — — — — — 

11/10/2015 10:00 — — — — — — — — — — 

12/15/2015 14:00 — — — — — — — 7.7 7.7 — 

*01/19/2016 09:45 — — — — — — — 16.7 16.7 — 

02/17/2016 09:00 — — — — — — — — — — 

*03/07/2016 13:30 — — — — — — — 6.3 6.3 — 

Table 9. Whole water pesticide concentrations for all compounds with detections in water and suspended sediment filtered from environmental waSacramento–San Joaquin Delta, 2015–16.—Continued[Table contains concentrations for all compounds with at least one detection in the suspended sediment filtered from environmental water. The whole water concentration is the sconcentration and the dissolved concentration. Numbers in brackets are U.S. Geological Survey (USGS) National Water Information System (NWIS) parameter codes. Concentr(ng/L). Whole water concentrations are listed in bold. Abbreviations: E, estimated; hh:mm, hour:minute; mm/dd/yyyy, month/day/year; —, not detected; *, storm sample]
Sample date (mm/dd/yyyy) Sample time (hh:mm) Metalaxyl [68437] Metolachlor [65090] Oxyfluorfen [65093] 

Suspended sediment Dissolved Whole water Suspended sediment Dissolved Whole water Suspended sediment Dissolved Whole water Suspend

sedime

Mokelumne River at New Hope Road—Continued 04/19/2016 09:20 — — — — — — — — — — 

05/18/2016 09:30 — — — — — — — — — — 06/15/2016 09:15 — — — — — — — — — — 

Sacramento River at Hood—Continued 07/28/2015 08:45 — — — — 13.2 13.2 — — — — 

08/18/2015 08:40 — — — — 3.9 3.9 — — — — 09/23/2015 08:30 — — — — — — — — — — 10/21/2015 08:00 — — — — — — — — — — 

11/10/2015 09:00 — — — — — — — — — — 

12/15/2015 15:00 — — — — — — — 3.8 3.8 — 

*01/19/2016 08:30 — — — — — — — — — — 

02/17/2016 08:00 — — — — — — — — — — 

*03/07/2016 14:20 — — — — 13.6 13.6 — — — — 

04/19/2016 08:20 — — — — — — — — — — 05/18/2016 08:30 — — — — 5.9 5.9 — — — — 06/15/2016 08:10 — — — — 7.1 7.1 — — — — 

San Joaquin River at Buckley Cove—Continued 07/28/2015 11:10 — — — — 143 143 — — — — 

08/18/2015 11:10 — — — — 94.5 94.5 — — — — 09/23/2015 10:45 — — — — 43.3 43.3 — — — — 10/21/2015 10:50 — — — — 16.5 16.5 — — — — 

11/10/2015 11:30 — — — — 12.2 12.2 — — — — 

12/15/2015 12:20 — — — — 7 7 — — — — 

*01/19/2016 10:50 — 36.9 36.9 — 16.2 16.2 — 68.2 68.2 — 

02/17/2016 10:10 — — — — 10.8 10.8 — — — — 

*03/07/2016 10:15 — — — — 42.8 42.8 — 211 211 — 

Table 9. Whole water pesticide concentrations for all compounds with detections in water and suspended sediment filtered from environmental waSacramento–San Joaquin Delta, 2015–16.—Continued [Table contains concentrations for all compounds with at least one detection in the suspended sediment filtered from environmental water. The whole water concentration is the sconcentration and the dissolved concentration. Numbers in brackets are U.S. Geological Survey (USGS) National Water Information System (NWIS) parameter codes. Concentr(ng/L). Whole water concentrations are listed in bold. Abbreviations: E, estimated; hh:mm, hour:minute; mm/dd/yyyy, month/day/year; —, not detected; *, storm sample]
Sample date 

(mm/dd/yyyy)

Sample 

time 

(hh:mm)

Metalaxyl 

[68437]

Metolachlor 

[65090]

Oxyfluorfen 

[65093]

Suspended 

sediment Dissolved Whole water Suspended sediment Dissolved Whole water Suspended sediment Dissolved Whole water Suspend

sedime

San Joaquin River at Buckley Cove—Continued

04/19/2016 10:40 — — — — 55.6 55.6 — 22.6 22.6 — 05/18/2016 10:45 — — — — 42.6 42.6 — — — — 06/15/2016 10:50 — — — — 83.5 83.5 — — — — 

San Joaquin River near Vernalis—Continued

07/28/2015 12:15 — — — — 30.8 30.8 — — — — 08/18/2015 12:50 — — — — 5.9 5.9 — — — — 09/23/2015 12:20 — — — — — — — — — — 10/21/2015 12:40 — — — — 3.5 3.5 — — — — 

11/10/2015 13:00 — — — — 6.4 6.4 — — — — 

12/15/2015 11:00 — — — — — — — — — — 

*01/19/2016 12:30 E1.0 — E1.0 — 28.3 28.3 — — — — 

02/17/2016 12:00 — — — — — — — — — — 

*03/07/2016 11:50 — — — — 12.6 12.6 — — — — 

04/19/2016 12:45 — — — — 9 9 — — — — 05/18/2016 12:20 — — — — 11.8 11.8 — — — — 06/15/2016 12:40 — — — — 14.8 14.8 — — — — 

Ulatis Creek at Browns Road—Continued

07/28/2015 14:20 — — — — 140 140 — — — — 08/18/2015 15:00 — — — — 63 63 — — — — 09/23/2015 14:15 — 17 17 — — — — — — — 10/21/2015 15:00 — — — — 14.5 14.5 — — — — 

11/10/2015 15:30 — — — — 20.9 20.9 — — — — 

12/15/2015 08:50 — — — — — — — 29.7 29.7 — 

*01/19/2016 15:00 — — — — 114 114 23.2 — 23.2 5.6 

02/17/2016 14:10 — — — — — — — 37.9 37.9 — 

*03/07/2016 08:30 — — — — 57.2 57.2 — 25.7 25.7 — 

Table 9. Whole water pesticide concentrations for all compounds with detections in water and suspended sediment filtered from environmental waSacramento–San Joaquin Delta, 2015–16.—Continued[Table contains concentrations for all compounds with at least one detection in the suspended sediment filtered from environmental water. The whole water concentration is the sconcentration and the dissolved concentration. Numbers in brackets are U.S. Geological Survey (USGS) National Water Information System (NWIS) parameter codes. Concentr(ng/L). Whole water concentrations are listed in bold. Abbreviations: E, estimated; hh:mm, hour:minute; mm/dd/yyyy, month/day/year; —, not detected; *, storm sample]
Sample date (mm/dd/yyyy) Sample time (hh:mm) Metalaxyl [68437] Metolachlor [65090] Oxyfluorfen [65093] 

Suspended sediment Dissolved Whole water Suspended sediment Dissolved Whole water Suspended sediment Dissolved Whole water Suspend

sedime

Ulatis Creek at Browns Road—Continued 04/19/2016 15:10 — — — — 9.1 9.1 E2.9 6.3 E9.2 — 

05/18/2016 14:20 — — — 17.8 2,630 2,650 — — — — 06/15/2016 14:40 — — — 4.1 178 182 — 25.8 25.8 — 

Sample date (mm/dd/yyyy) Sample time (hh:mm) Pendimethalin [65098] Prodiamine [51844] Permethrin [65099] Suspended sediment Dissolved Whole water Suspended sediment Dissolved Whole water Suspended sediment Dissolved Whole water Mokelumne River at New Hope Road—Continued 07/28/2015 09:50 — — — — — — — — — 08/18/2015 09:50 — — — — — — — — — 09/23/2015 09:20 — — — — — — — — — 10/21/2015 09:10 — — — — — — — — — 11/10/2015 10:00 — — — — — — — — — 12/15/2015 14:00 — — — — — — — — — *01/19/2016 09:45 — 17.7 17.7 — — — — — — 02/17/2016 09:00 — — — — — — — — — *03/07/2016 13:30 — — — — — — — — — 04/19/2016 09:20 — — — — — — — — — 05/18/2016 09:30 — — — — — — — — — 06/15/2016 09:15 — — — — — — — — — Sacramento River at Hood—Continued 07/28/2015 08:45 — — — — — — — — — 08/18/2015 08:40 — — — — — — — — — 09/23/2015 08:30 — — — — — — — — — 10/21/2015 08:00 — — — — — — — — — 11/10/2015 09:00 — — — — — — — — — Table 9. Whole water pesticide concentrations for all compounds with detections in water and suspended sediment filtered from environmental wa

Sacramento–San Joaquin Delta, 2015–16.—Continued [Table contains concentrations for all compounds with at least one detection in the suspended sediment filtered from environmental water. The whole water concentration is the sconcentration and the dissolved concentration. Numbers in brackets are U.S. Geological Survey (USGS) National Water Information System (NWIS) parameter codes. Concentr(ng/L). Whole water concentrations are listed in bold. Abbreviations: E, estimated; hh:mm, hour:minute; mm/dd/yyyy, month/day/year; —, not detected; *, storm sample]
Sample date 

(mm/dd/yyyy)

Sample 

time 

(hh:mm)

Pendimethalin [65098] Prodiamine [51844] Permethrin [65099]

Suspended 

sediment Dissolved Whole water Suspended sediment Dissolved Whole water Suspended sediment Dissolved Whole water

Sacramento River at Hood—Continued

12/15/2015 15:00 — — — — — — — — —

*01/19/2016 08:30 — — — — — — — — —

02/17/2016 08:00 — — — — — — — — —

*03/07/2016 14:20 — — — — — — 19.2 — 19.2

04/19/2016 08:20 — — — — — — — — —05/18/2016 08:30 — — — — — — — — —06/15/2016 08:10 — — — — — — — — —

San Joaquin River at Buckley Cove—Continued

07/28/2015 11:10 — — — — — — — — —08/18/2015 11:10 — — — — — — 2.7 — 2.709/23/2015 10:45 — — — — — — — — —10/21/2015 10:50 — — — — — — — — —

11/10/2015 11:30 — — — — — — — — —

12/15/2015 12:20 — — — — — — — — —

*01/19/2016 10:50 51.1 53.8 105 — — — — — —

02/17/2016 10:10 — — — — — — — — —

*03/07/2016 10:15 — 33.4 33.4 — — — — — —

04/19/2016 10:40 — — — — — — — — —05/18/2016 10:45 — — — — — — — — —06/15/2016 10:50 — 14.4 14.4 — — — — — —

San Joaquin River near Vernalis—Continued

07/28/2015 12:15 — — — — — — — — —08/18/2015 12:50 — — — — — — — — —09/23/2015 12:20 — — — — — — — — —10/21/2015 12:40 — — — — — — — — —

11/10/2015 13:00 — — — — — — — — —

Table 9. Whole water pesticide concentrations for all compounds with detections in water and suspended sediment filtered from environmental waSacramento–San Joaquin Delta, 2015–16.—Continued[Table contains concentrations for all compounds with at least one detection in the suspended sediment filtered from environmental water. The whole water concentration is the sconcentration and the dissolved concentration. Numbers in brackets are U.S. Geological Survey (USGS) National Water Information System (NWIS) parameter codes. Concentr(ng/L). Whole water concentrations are listed in bold. Abbreviations: E, estimated; hh:mm, hour:minute; mm/dd/yyyy, month/day/year; —, not detected; *, storm sample]
Sample date (mm/dd/yyyy) Sample time (hh:mm) Pendimethalin [65098] Prodiamine [51844] Permethrin [65099] Suspended sediment Dissolved Whole water Suspended sediment Dissolved Whole water Suspended sediment Dissolved Whole water San Joaquin River near Vernalis—Continued 12/15/2015 11:00 — — — — — — — — — *01/19/2016 12:30 27.5 46 73.5 — — — — — — 02/17/2016 12:00 — — — — — — — — — *03/07/2016 11:50 — 28.9 28.9 — — — — — — 04/19/2016 12:45 — — — — — — — — — 05/18/2016 12:20 — — — — — — — — — 06/15/2016 12:40 — — — — — — — — — Ulatis Creek at Browns Road—Continued 07/28/2015 14:20 — — — — — — — — — 08/18/2015 15:00 — — — — — — 3.2 — 3.2 09/23/2015 14:15 — — — — — — — — — 10/21/2015 15:00 — — — — — — — — — 11/10/2015 15:30 — — — — — — — — — 12/15/2015 08:50 — — — — — — — — — *01/19/2016 15:00 265 99.6 365 9.6 8.5 18.1 — — — 02/17/2016 14:10 — — — — — — — — — *03/07/2016 08:30 — 205 205 — E3.9 E3.9 26.4 — 26.4 04/19/2016 15:10 — 33.6 33.6 — — — — — — 05/18/2016 14:20 — — — — — — — — — 06/15/2016 14:40 — — — — — — — — — Table 9. Whole water pesticide concentrations for all compounds with detections in water and suspended sediment filtered from environmental wa

Sacramento–San Joaquin Delta, 2015–16.—Continued [Table contains concentrations for all compounds with at least one detection in the suspended sediment filtered from environmental water. The whole water concentration is the sconcentration and the dissolved concentration. Numbers in brackets are U.S. Geological Survey (USGS) National Water Information System (NWIS) parameter codes. Concentr(ng/L). Whole water concentrations are listed in bold. Abbreviations: E, estimated; hh:mm, hour:minute; mm/dd/yyyy, month/day/year; —, not detected; *, storm sample]
Results 41

Table 10. Concentrations of dissolved and suspended constituents measured in environmental water samples collected in the 

Sacramento–San Joaquin Delta, 2015–16.

[Numbers in brackets are U.S. Geological Survey (USGS) National Water Information System (NWIS) parameter codes. Abbreviations: del., result deleted by 

laboratory; hh:mm, hour:minute; mg/L, milligram per liter; mm/dd/yyyy, month/day/year; <, less than ; μg/L, microgram per liter; —, not detected]

Sample date 

(mm/dd/yyyy)

Sample 

time 

(hh:mm)

Dissolved 

organic carbon 

[00681] 

(mg/L)

Particulate 

inorganic carbon 

[00688] 

(mg/L)

Particulate 

organic carbon 

[00689] 

(mg/L)

Total 

particulate carbon 

[00694] 

(mg/L)

Dissolved 

copper 

[01040] 

(μg/L)

Total 

particulate nitrogen 

[49570] 

(mg/L)

Mokelumne River at New Hope Road

07/28/2015 09:50 3.06 — 1.41 1.41 1.3 0.19

08/18/2015 09:50 2.12 — <0.86 0.86 0.96 0.099

09/23/2015 09:20 2.83 — <0.61 0.61 1.4 0.069

10/21/2015 09:10 2.13 — <0.21 0.21 1.1 0.033

11/10/2015 10:00 2.2 — <0.20 0.2 1.2 0.031

12/15/2015 14:00 2.65 — <0.30 0.3 0.99 0.049

01/19/2016 09:45 2.94 — <0.62 0.62 1.4 0.088

02/17/2016 09:00 2.26 — <0.76 0.76 1.5 0.094

03/07/2016 13:30 2.89 — <0.42 0.42 2 0.063

04/19/2016 09:20 2.14 — <0.95 0.95 1.4 0.131

05/18/2016 09:30 del. — <0.38 0.38 1.2 0.039

06/15/2016 09:15 2.68 — <0.51 0.51 1.3 0.06

Sacramento River at Hood

07/28/2015 08:45 1.81 — 0.36 0.36 1.2 0.049

08/18/2015 08:40 1.81 — <0.11 0.11 1.7 —

09/23/2015 08:30 1.59 — <0.11 0.11 1.9 —

10/21/2015 08:00 1.64 — <0.17 0.17 1.3 —

11/10/2015 09:00 1.78 — <0.26 0.26 1.3 0.04

12/15/2015 15:00 2.04 — <0.51 0.51 1.0 0.084

01/19/2016 08:30 4.44 — <2.11 2.11 2.6 0.254

02/17/2016 08:00 2.65 — <0.45 0.45 1.9 0.064

03/07/2016 14:20 4.42 — <2.55 2.55 2.6 0.316

04/19/2016 08:20 1.64 — <0.50 0.5 1.3 0.086

05/18/2016 08:30 del. — <0.15 0.15 1.0 —

06/15/2016 08:10 2.56 — <0.49 0.49 1.1 0.062

San Joaquin River at Buckley Cove

07/28/2015 11:10 5.04 — 1.28 1.28 2.0 0.233

08/18/2015 11:10 4.82 — <0.44 0.44 1.8 0.081

09/23/2015 10:45 4.28 — <0.43 0.43 1.9 0.08

10/21/2015 10:50 3.54 — <0.35 0.35 1.5 0.061

11/10/2015 11:30 2.72 — <0.19 0.19 1.1 —

12/15/2015 12:20 3.35 0.06 1.12 1.18 1.5 0.145

01/19/2016 10:50 7.65 0.03 2.35 2.38 3.3 0.319

02/17/2016 10:10 8.37 — <0.89 0.89 3.7 0.123

03/07/2016 10:15 7.37 — <0.54 0.54 4.4 0.075

04/19/2016 10:40 4.8 — <1.30 1.3 1.9 0.218

05/18/2016 10:45 3.23 — <1.51 1.51 1.2 0.192

06/15/2016 10:50 3.85 — <2.17 2.17 1.6 0.303
42 Pesticide Inputs to the Sacramento–San Joaquin Delta, 2015–16: Results from the Delta Regional Monitoring Program

Sample date 

(mm/dd/yyyy)

Sample 

time 

(hh:mm)

Dissolved 

organic carbon 

[00681] 

(mg/L)

Particulate 

inorganic carbon 

[00688] 

(mg/L)

Particulate 

organic carbon 

[00689] 

(mg/L)

Total 

particulate carbon 

[00694] 

(mg/L)

Dissolved 

copper 

[01040] 

(μg/L)

Total 

particulate nitrogen 

[49570] 

(mg/L)

San Joaquin River near Vernalis

07/28/2015 12:15 2.6 — 0.79 0.79 0.86 0.178

08/18/2015 12:50 2.27 — <0.15 0.15 — —

09/23/2015 12:20 2.55 — <0.15 0.15 0.92 —

10/21/2015 12:40 2.23 — <0.18 0.18 0.81 —

11/10/2015 13:00 2.38 — <0.29 0.29 0.88 0.042

12/15/2015 11:00 2.54 — <0.29 0.29 — 0.05

01/19/2016 12:30 4.47 — <1.40 1.4 1.8 0.193

02/17/2016 12:00 4.74 — <1.48 1.48 1.2 0.236

03/07/2016 11:50 5.08 — <1.60 1.6 1.6 0.225

04/19/2016 12:45 3.06 — <2.99 2.99 1.5 0.434

05/18/2016 12:20 2.89 — <2.90 2.9 0.83 0.461

06/15/2016 12:40 2.77 — <4.80 4.8 1.0 0.67

Ulatis Creek at Browns Road

07/28/2015 14:20 8.01 — 0.96 0.96 3.0 0.209

08/18/2015 15:00 7.22 — <1.66 1.66 2.5 0.29

09/23/2015 14:15 9.97 — <1.83 1.83 2.3 0.346

10/21/2015 15:00 8.93 — <1.16 1.16 1.5 0.175

11/10/2015 15:30 4.25 — <1.25 1.25 1.2 0.186

12/15/2015 08:50 6.32 0.05 1.54 1.59 2.4 0.248

01/19/2016 15:00 7.77 0.14 38.5 38.6 3.8 4.59

02/17/2016 14:10 4.74 — <1.04 1.04 2.4 0.158

03/07/2016 08:30 9.24 0.13 5.14 5.27 3.9 0.613

04/19/2016 15:10 6.06 — <4.41 4.41 3.6 0.77

05/18/2016 14:20 6.85 — <1.69 1.69 3.0 0.255

06/15/2016 14:40 11.6 — <1.80 1.8 4.2 0.323

Table 10. Concentrations of dissolved and suspended constituents measured in environmental water samples collected in the 

Sacramento–San Joaquin Delta, 2015–16.—Continued

[Numbers in brackets are U.S. Geological Survey (USGS) National Water Information System (NWIS) parameter codes. Abbreviations: del., result deleted by 

laboratory; hh:mm, hour:minute; mg/L, milligram per liter; mm/dd/yyyy, month/day/year; <, less than ; μg/L, microgram per liter; —, not detected]
Results 43

Table 11. Water quality field parameters measured in surface-water samples collected in the Sacramento–San Joaquin Delta, 

California, 2015–16.

[Numbers in brackets are U.S. Geological Survey (USGS) National Water Information System parameter codes. Abbreviations: hh:mm, hour:minute; 

mg/L, milligram per liter; mm/dd/yyyy, month/day/year; NTU, nephelometric turbidity units; °C, degrees Celsius; μS/cm, microsiemens per centimeter; —, data 

not collected; *, storm sample]

Sample date 

(mm/dd/yyyy)

Sample time 

(hh:mm)

Water temperature 

[00010]

(°C)

Specific conductance 

[00095]

(μS/cm)

Dissolved oxygen 

[00300]

(mg/L)

pH 

[00400]

Turbidity 

[63675]

(NTU)

Mokelumne River at New Hope Road

07/28/2015 9:50 24.2 122 8.0 8.2 —

08/18/2015 9:50 25.1 130 7.9 7.9 11

09/23/2015 9:20 20.6 187 8.2 7.8 6.6

10/21/2015 9:10 16.7 54 8.7 7.4 4.5

11/10/2015 10:00 12.4 52 9.9 7.2 6.6

12/15/2015 14:00 9.1 57 10.6 7.7 3.0

01/19/2016* 9:45 14.6 53 — 7.3 7.6

02/17/2016 9:00 14.0 59 9.3 7.6 7.6

03/07/2016* 13:30 13.6 55 9.3 7.6 —

04/19/2016 9:20 17.9 52 8.4 7.2 830

05/18/2016 9:30 18.9 52 8.3 7.4 0.0

06/15/2016 9:15 18.2 53 8.4 7.2 0.0

Sacramento River at Hood

07/28/2015 8:45 23.7 132 7.2 7.2 —

08/18/2015 8:40 24.9 169 7.1 7.5 6.7

09/23/2015 8:30 20.9 172 8.1 7.5 7.6

10/21/2015 8:00 18.9 160 8.5 7.3 6.6

11/10/2015 9:00 13.4 178 9.2 7.0 5.9

12/15/2015 15:00 10.5 182 10.0 7.5 9.8

01/19/2016* 8:30 9.8 142 10.2 7.3 90

02/17/2016 8:00 13.4 190 9.6 7.5 14

03/07/2016* 14:20 13.0 140 9.2 7.3 76

04/19/2016 8:20 16.8 127 9.2 7.0 1.0

05/18/2016 8:30 19.2 108 8.6 7.2 0.0

06/15/2016 8:10 19.9 113 8.3 7.0 2.1

San Joaquin River at Buckley Cove

07/28/2015 11:10 26.3 1,370 8.8 8.2 —

08/18/2015 11:10 26.0 1,360 6.2 7.7 16

09/23/2015 10:45 23.0 1,410 7.5 7.7 12

10/21/2015 10:50 21.4 860 8.1 7.8 5.6

11/10/2015 11:30 15.9 366 8.7 7.6 6.5

12/15/2015 12:20 11.1 592 11.1 7.9 22

01/19/2016* 10:50 11.1 409 9.1 7.4 68

02/17/2016 10:10 13.4 606 7.2 7.3 11

03/07/2016* 10:15 15.7 672 8.7 7.5 —

04/19/2016 10:40 20.6 878 9.4 7.5 0.1

05/18/2016 10:45 21.0 276 8.7 7.5 6.6

06/15/2016 10:50 23.7 624 7.8 7.3 4.8
44 Pesticide Inputs to the Sacramento–San Joaquin Delta, 2015–16: Results from the Delta Regional Monitoring Program

Sample date 

(mm/dd/yyyy)

Sample time 

(hh:mm)

Water temperature 

[00010]

(°C)

Specific conductance 

[00095]

(μS/cm)

Dissolved oxygen 

[00300]

(mg/L)

pH 

[00400]

Turbidity 

[63675]

(NTU)

San Joaquin River near Vernalis

07/28/2015 12:15 25.3 962 9.0 7.9 —

08/18/2015 12:50 26.6 668 8.6 7.8 6.6

09/23/2015 12:20 21.9 706 8.6 7.7 5.0

10/21/2015 12:40 18.7 453 7.5 7.5 12

11/10/2015 13:00 13.4 299 8.3 7.3 7.2

12/15/2015 11:00 8.8 476 10.2 7.8 6.4

01/19/2016* 12:30 12.3 449 8.4 7.4 24

02/17/2016 12:00 15.5 975 8.7 7.6 12

03/07/2016* 11:50 16.0 751 8.0 7.7 4.6

04/19/2016 12:45 17.4 382 10.1 7.9 18

05/18/2016 12:20 19.4 322 12.0 8.4 1.7

06/15/2016 12:40 21.2 433 14.1 8.6 7.0

Ulatis Creek at Browns Road

07/28/2015 14:20 25.2 695 7.1 7.9 —

08/18/2015 15:00 24.0 763 8.2 8.0 14

09/23/2015 14:15 20.9 1,050 7.2 7.8 16

10/21/2015 15:00 18.2 930 5.6 7.7 14

11/10/2015 15:30 13.8 1,030 10.2 8.1 22

12/15/2015 8:50 7.3 805 9.8 7.7 8.4

01/19/2016* 15:00 12.9 134 8.7 7.7 730

02/17/2016 14:10 16.6 1,120 11.0 8.2 7.2

03/07/2016* 8:30 12.1 208 9.5 7.2 160

04/19/2016 15:10 23.3 819 — 8.8 2.4

05/18/2016 14:20 24.4 811 9.0 8.1 0.0

06/15/2016 14:40 19.0 1,040 9.4 8.2 11

Table 11. Water quality field parameters measured in surface-water samples collected in the Sacramento–San Joaquin Delta, 

California, 2015–16.—Continued

[Numbers in brackets are U.S. Geological Survey (USGS) National Water Information System parameter codes. Abbreviations: hh:mm, hour:minute; 

mg/L, milligram per liter; mm/dd/yyyy, month/day/year; NTU, nephelometric turbidity units; °C, degrees Celsius; μS/cm, microsiemens per centimeter; —, data 

not collected; *, storm sample]
Results 45

sac18-0662_fig03

30

25

20

10

0

July Aug. Sept. Oct. Nov. Dec. Jan.

Month

Feb. Mar. Apr. May June

15

5

Number of pesticides detected

EXPLANATION

Mokelumne River at New Hope Road

Sacramento River at Hood

San Joaquin River at Buckley Cove

San Joaquin River near Vernalis

Ulatis Creek at Browns Road

Figure 3. Numbers of pesticides detected per month in surface-water samples from July 2015 to June 2016 in the Sacramento–San 

Joaquin Delta, California.

San Joaquin River at Buckley Cove

A total of 37 pesticides (13 herbicides, 11 fungicides, 

6 insecticides, 6 breakdown products, and 1 synergist) were 

detected in the water samples from this site. Nine pesticides 

were detected in every sample from this site (azoxystrobin, 

boscalid, DCPMU, diuron, fluridone, hexazinone, methoxyfenozide, metolachlor, and simazine), and nine additional 

pesticides (fluxapyroxad, carbendazim, chlorantraniliprole, 

DCPU, imidacloprid, 3,4-dichloroaniline, dithiopyr, piperonyl butoxide, and desulfinylfipronil) also were detected in 

at least 50 percent of the samples. The maximum pesticide 

concentration measured at the site was 451 ng/L for diuron 

in the sample collected on January 19, 2016. A minimum of 

14 (May 18, 2016) and a maximum of 25 (January 19, 2016) 

pesticides or pesticide degradates were detected in each water 

sample (fig. 3). Pendimethalin was detected in the suspended 

sediments of the sample collected on January 19, 2016 

(51.1 ng/L), and permethrin was detected in the suspended 

sediments collected on August 18, 2015 (2.7 ng/L).

The insecticide fipronil was detected (13.5 ng/L) in 

the water sample collected on July 28, 2015, at a concentration above the aquatic-life benchmark for chronic toxicity to 

invertebrates of 11 ng/L. Imidacloprid was detected in the 

water samples collected on January 19, 2016 (17.8 ng/L), 

April 19, 2016 (60.1 ng/L), and May 18, 2016 (13.7 ng/L), at 

concentrations above the aquatic-life benchmark for chronic 

toxicity to invertebrates of 10.0 ng/L (U.S. Environmental 

Protection Agency, 2017).

San Joaquin River Near Vernalis

A total of 32 pesticides (12 fungicides, 11 herbicides, 

5 insecticides, and 4 breakdown products) were detected in the 

water samples collected from San Joaquin River near Vernalis. 

Three pesticides (methoxyfenozide, hexazinone, and boscalid) 

were detected in every sample from this site, and nine 

additional pesticides (azoxystrobin, metolachlor, simazine, 

chlorantraniliprole, dithiopyr, diuron, fluxapyroxad, DCPMU, 

and 3,4-dichloroaniline) were detected in at least half of the 

samples. The maximum pesticide concentration measured at 

this site was 201 ng/L for iprodione in the sample collected on 

February 17, 2016. A minimum of 7 (September 23, 2015, and 

October 21, 2015) and a maximum of 23 (January 19, 2016) 

pesticides or pesticide degradates were detected in each 

water sample (fig. 3). Imidacloprid was detected in the water 

samples collected on January 19, 2016 (12.4 ng/L), and April 

19, 2016 (11.1 ng/L), at concentrations above the aquatic-life 

benchmark for chronic toxicity to invertebrates of 10.0 ng/L 

(U.S. Environmental Protection Agency, 2017).
46 Pesticide Inputs to the Sacramento–San Joaquin Delta, 2015–16: Results from the Delta Regional Monitoring Program

Four pesticides were detected in the suspended sediments 

of water samples collected at San Joaquin River near Vernalis. 

The herbicides DCPA and pendimethalin were detected in 

the sample collected on January 19, 2016, at concentrations 

of 86.8 and 27.5 ng/L, respectively. The fungicide metalaxyl 

was detected at an estimated concentration of 1.0 ng/L in the 

sample collected on January 19, 2016. The insecticide bifenthrin was detected at a concentration of 4.3 ng/L in the sample 

collected on April 19, 2016.

Ulatis Creek at Browns Road

A total of 40 pesticides (14 herbicides, 12 fungicides, 

9 insecticides, and 5 breakdown products) were detected in 

water samples collected from Ulatis Creek at Browns Road. 

Three pesticides were detected in every sample (boscalid, 

chlorantraniliprole, and imidacloprid), and 11 additional 

pesticides were detected in at least half of the samples. 

The maximum concentration measured at Ulatis Creek 

was 2,630 ng/L for the herbicide metolachlor in the sample 

collected on May 18, 2016. A minimum of 9 (September 

23, 2015) and a maximum of 25 (March 7, 2016) pesticides 

or pesticide degradates were detected in each water sample 

(fig. 3).

Bifenthrin was detected in the samples collected 

on November 10, 2015 (33.3 ng/L), December 15, 2015 

(13.2 ng/L), and February 17, 2016 (11.5 ng/L), at concentrations above the aquatic-life benchmark for chronic toxicity 

to invertebrates of 1.3 ng/L. Fipronil was detected at concentrations at or above the aquatic-life benchmark for chronic 

toxicity to invertebrates of 11 ng/L in the samples collected on 

October 21, 2015 (13.4 ng/L), and January 19, 2016 (11 ng/L). 

Imidacloprid was detected at concentrations above the aquaticlife benchmark for chronic toxicity to invertebrates of 10.0 

ng/L in seven water samples at this site (U.S. Environmental 

Protection Agency, 2017).

Pesticides were detected in the suspended sediments of 

six samples collected at Ulatis Creek. A total of nine pesticides 

were detected (bifenthrin, cyhalothrin, dithiopyr, metolachlor, 

oxyfluorfen, p,p’-DDE, pendimethalin, permethrin, and prodiamine); the most frequently detected compounds being the 

herbicides metolachlor and oxyfluorfen (17 percent each) and 

the insecticides bifenthrin and permethrin (17 percent each). 

The storm sample collected on January 19, 2016, contained 

the most pesticides (six) and generally had the highest concentrations. The highest concentrations measured in the suspended sediment were 265 ng/L for pendimethalin, 26.4 ng/L 

for permethrin, and 23.2 ng/L for oxyfluorfen.

Summary

This study was conducted as part of the Sacramento–

San Joaquin Delta (Delta) Regional Monitoring Program, 

which is a cooperative effort to better track beneficial-use 

protections and restoration efforts through the monitoring of 

mercury, nutrients, pathogens, and pesticides in the Delta. The 

U.S. Geological Survey (USGS) was responsible for collecting, analyzing, and reporting pesticide concentration data in 

the Delta. Samples were collected monthly at five major inputs 

to the Delta from July 2015 to June 2016 and analyzed for 

a suite of 154 pesticides and pesticide degradates, dissolved 

organic carbon, particulate organic carbon, particulate inorganic carbon, particulate nitrogen, and dissolved copper by the 

USGS. Ten samples were collected approximately mid-month, 

and two samples were collected following moderate-rainfall 

events.

Thirty-two quality-assurance and quality-control samples 

(replicates, blanks, and matrix spikes) were collected to 

validate measurements taken on environmental water samples. 

Twenty-seven quality-control samples satisfied quality assurance program plan requirements for the study; one blank 

sample analyzed for dissolved organic carbon was measured 

at a concentration above the reporting level, and four pesticide 

matrix-spike samples each contained one compound that was 

measured at over 130 percent recovery.

A total of 54 pesticides were detected in water samples 

collected during the study period (19 fungicides, 18 herbicides, 9 insecticides, 7 breakdown products, and 1 synergist). 

All samples contained mixtures of pesticides ranging from 

2 to 25 pesticides per sample. Overall, 14 pesticides were 

detected in at least half of all samples. Pesticide concentrations 

ranged from below method detection limits listed in table 2 to 

2,630 nanograms per liter for the herbicide metolachlor.

A total of 11 pesticides were detected in suspended 

sediments filtered from the water samples collected during 

the study period (6 herbicides, 3 insecticides, 1 fungicide, 

and 1 breakdown product). Overall, the most frequently 

detected pesticides on suspended sediments were permethrin (7 percent), pendimethalin (5 percent), and bifenthrin 

(5 percent). Pesticide concentrations in the suspended sediments ranged from below the method detection limits to 

265 nanograms per liter for pendimethalin.

Bifenthrin, fipronil, and imidacloprid were measured 

at concentrations above their respective U.S. Environmental 

Protection Agency (EPA) aquatic-life benchmarks for chronic 

toxicity to invertebrates. The EPA aquatic-life benchmarks 

are listed only to give context to measurements; instantaneous 

concentrations above chronic criteria do not constitute an 

assessment of water quality.
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