National Water-Quality Assessment Program

An Overview Comparing Results from Two Decades of 

Monitoring for Pesticides in the Nation’s Streams and Rivers, 

1992–2001 and 2002–2011

Scientific Investigations Report 2014–5154

U.S. Department of the Interior

U.S. Geological Survey

An Overview Comparing Results from Two 

Decades of Monitoring for Pesticides in the 

Nation’s Streams and Rivers, 1992–2001 

and 2002–2011

By Wesley W. Stone, Robert J. Gilliom, and Jeffrey D. Martin

National Water-Quality Assessment Program

Scientific Investigations Report 2014–5154

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2014

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Suggested citation:

Stone, W.W., Gilliom, R.J., and Martin, J.D., 2014, An overview comparing results from two decades of monitoring 

for pesticides in the Nation’s streams and Rrvers, 1992–2001 and 2002–2011: U.S. Geological Survey Scientific 

Investigations Report 2014–5154, 23 p., http://dx.doi.org/10.3133/sir20145154.

ISSN 2328-0328 (online)

http://dx.doi.org/10.3133/sir20145154
iii

Contents

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

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

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

Pesticide Monitoring Design ..............................................................................................................2

Methods...........................................................................................................................................................2

Pesticides...............................................................................................................................................3

Stream-Site Selection..........................................................................................................................4

Detection Frequency and Concentration Statistics........................................................................4

Land-Use Classifications.....................................................................................................................6

Pesticide Occurrence ...................................................................................................................................7

Concentrations And Benchmark Comparisons ........................................................................................8

Summary........................................................................................................................................................10

References Cited..........................................................................................................................................11

Appendix 1.....................................................................................................................................................13

Figures

1. Estimated agricultural use of synthetic organic herbicides, insecticides, and 

fungicides in the conterminous U.S. during first (1992–2001) and second (2002–11) 

decades of stream monitoring....................................................................................................3

2. Map showing the national monitoring network for pesticides in streams and rivers 

included 182 sites during 1992–2001 and 125 sites during 2002–11, with 96 of the sites 

common to both decades....................................................................................................................5 

3. Percentage of time during a year that the most frequently detected pesticides 

were detected in streams and rivers in relation to land-use classification.......................7

4. Pesticides that exceeded chronic Aquatic Life Benchmarks at more than 5 percent 

of stream sites and percent of streams by land-use classification.....................................9

Tables

1. Minimum samples, per water year, by watershed size..........................................................4

2. Land-use classifications and watershed land-use criteria...........................................................6

3. Number of stream sites by land-use classification ................................................................6

4. Percent of time one or more pesticides or pesticide degradates were detected in 

streams, by land-use classification...........................................................................................7

5. Percent of streams with one or more pesticide concentration statistics that 

exceeded a chronic Aquatic Life Benchmark (ALB), by land-use classification ............10
iv

Conversion Factors and Abbreviations

SI to Inch/Pound

Multiply By To obtain

Area

square kilometer (km2

) 247.1 acre

square kilometer (km2

) 0.3861 square mile (mi2)

Water year is the 12-month period of October 1, for any given year through September 30, of the 

following year. The water year is designated by the calendar year in which it ends and which 

includes 9 of the 12 months.

Abbreviations used in this report

ALB Aquatic Life Benchmark

GCMS gas chromatography/mass spectrometry

HHB Human Health Benchmark

NASQAN National Stream Quality Accounting Network

NAWQA National Water-Quality Assessment

NLCD National Land Cover Data

NLCD06 National Land Cover Data 2006

NLCDe National Land Cover Data enhanced

NWQL National Water Quality Laboratory

USGS U.S. Geological Survey
An Overview Comparing Results from Two Decades of 

Monitoring for Pesticides in the Nation’s Streams and 

Rivers, 1992–2001 and 2002–2011

By Wesley W. Stone, Robert J. Gilliom, and Jeffrey D. Martin

Abstract 

This report provides an overview of the U.S. Geological Survey National Water-Quality Assessment program and 

National Stream Quality Accounting Network findings for pesticide occurrence in U.S. streams and rivers during 2002–11 

and compares them to findings for the previous decade 

(1992–2001). In addition, pesticide stream concentrations 

were compared to Human Health Benchmarks (HHBs) and 

chronic Aquatic Life Benchmarks (ALBs). The comparisons 

between the decades were intended to be simple and descriptive. Trends over time are being evaluated separately in a 

series of studies involving rigorous trend analysis. During both 

decades, one or more pesticides or pesticide degradates were 

detected more than 90 percent of the time in streams across all 

types of land uses. For individual pesticides during 2002–11, 

atrazine (and degradate, deethylatrazine), carbaryl, fipronil 

(and degradates), metolachlor, prometon, and simazine were 

detected in streams more than 50 percent of the time. In contrast, alachlor, chlorpyrifos, cyanazine, diazinon, EPTC, Dacthal, and tebuthiuron were detected less frequently in streams 

during the second decade than during the first decade. During 2002–11, only one stream had an annual mean pesticide 

concentration that exceeded an HHB. In contrast, 17 percent 

of agriculture land-use streams and one mixed land-use stream 

had annual mean pesticide concentrations that exceeded HHBs 

during 1992–2001. The difference between the first and second decades in terms of percent of streams exceeding HHBs 

was attributed to regulatory changes. During 2002–11, nearly 

two-thirds of agriculture land-use streams and nearly onehalf of mixed land-use streams exceeded chronic ALBs. For 

urban land use, 90 percent of the streams exceeded a chronic 

ALB. Fipronil, metolachlor, malathion, cis-permethrin, and 

dichlorvos exceeded chronic ALBs for more than 10 percent 

of the streams. For agriculture and mixed land-use streams, the 

overall percent of streams that exceeded a chronic ALB was 

very similar between the decades. For urban land-use streams, 

the percent of streams exceeding a chronic ALB during 

2002–11 nearly doubled that seen during 1992–2001. The 

reason for this difference was the inclusion of fipronil monitoring during the second decade. Across all land-use streams, 

the percent of streams exceeding a chronic ALB for fipronil 

during 2002–11 was greater than all other insecticides during both decades. The percent of streams exceeding a chronic 

ALB for metolachlor, chlorpyrifos, diazinon, malathion, and 

carbaryl decreased from the first decade to the second decade. 

The results of the 2002–11 summary and comparison to 

1992–2001 are consistent with the results from more rigorous 

trend analysis of pesticide stream concentrations for individual 

streams in various regions of the U.S. 

Introduction

The U.S. Geological Survey (USGS) National WaterQuality Assessment (NAWQA) and National Stream Quality 

Accounting Network (NASQAN) are monitoring programs 

that collect and report data for national assessments of pesticide concentrations in the Nation’s streams and rivers. Gilliom 

and others (2006) reported findings for the first decade (1992–

2001) of the NAWQA program and found that pesticides or 

their degradates were present in one or more water samples 

from every stream included in the assessment; one or more 

pesticides were detected more than 90 percent of the time in 

agricultural, urban, and mixed land-use streams; and the most 

frequently detected pesticides also had the greatest use.

This report builds upon the 1992–2001 assessment of 

pesticides in the Nation’s streams (Gilliom and others, 2006) 

by summarizing pesticide occurrence in streams during 

the second decade (2002–11) of NAWQA stream monitoring, including pesticide stream concentration data from the 

NASQAN program, and providing descriptive comparisons 

between the two decades of pesticide monitoring. Gilliom and 

others (2006) assessed the occurrence of 83 pesticides and 

degradates from 186 stream sites that represented agriculture, 

urban, mixed, and undeveloped land uses during 1992–2001. 
2 An Overview Comparing Results from Two Decades of Monitoring for Pesticides in the Nation’s Streams and Rivers

Changes in the NAWQA program between the first and second 

decades reduced the number of monitored stream sites. The 

sampling design (number of samples to be collected and when 

they were to be collected) also changed between the decades. 

Specifically, the 1992–2001 sampling design was a mix of 

fixed-frequency sampling and high-flow sampling (to characterize times of expected higher stream pesticide concentrations); however, the 2002–11 sampling design was fixed-frequency with minimal high-flow sampling efforts. In addition, 

the number of pesticides and degradates that were monitored 

in streams sufficient for a national assessment nearly doubled 

during the second decade. 

The changes in the NAWQA pesticide stream monitoring program from the first to second decade made it difficult 

to do simple, stream site to stream site comparisons between 

the decades and compare directly to the assessment by Gilliom 

and others (2006). In addition, this assessment differs from the 

previous assessment by Gilliom and others (2006) because (1) 

Human Health Benchmarks (HHBs) and chronic Aquatic Life 

Benchmarks (ALBs) have been updated; (2) some pesticides 

assessed during 1992–2001 were not sampled at enough sites 

to attain a reasonable national distribution during 2002–11; (3) 

land use ancillary data used to group sites have changed over 

time; (4) the stream-site selection process was revised; and 

(5) this assessment includes multiple years of data for sites, 

when available. The inclusion of multiple years of concentration data rather than a single year in the assessment, as was 

done by Gilliom and others (2006), was evaluated in terms 

of occurrence and percent of stream sites exceeding an HHB 

or chronic ALB for 1992–2001. The occurrence of pesticides 

in streams and the percent of stream sites that exceeded an 

HHB or chronic ALB for a single year compared to multiple 

years were all within 10 percent of each other for 1992–2001. 

Overall, the 1992–2001 results in this report are not markedly 

different than those reported by Gilliom and others (2006) 

except in cases where an ALB has been more recently established. For example, an ALB for metolachlor or S-metolachlor 

did not exist when Gilliom and others (2006) completed the 

initial assessment for 1992–2001; however, ALBs for S-metolachlor have been established and are used in this assessment. 

This report uses the most current HHBs and chronic ALBs for 

assessment of annual pesticide stream concentrations. Acute 

ALBs were not used in the comparisons between decades 

because the differences in sampling designs between them 

would likely bias the comparisons. 

Purpose and Scope

The purpose of this report is to summarize pesticide 

occurrence in U.S. streams and rivers during 2002–11 in 

comparison to the previous decade, 1992–2001. This overview 

focuses on pesticide occurrence (percent of time detected) 

and pesticide concentrations in relation to HHBs and chronic 

ALBs. Although pesticide occurrence is compared between 

the decades for perspective, the comparisons are simple and 

descriptive, and are not meant as a rigorous trend analysis. 

Trends are being evaluated separately in a series of studies 

involving quantitative site-based trend models, including 

Corn-Belt streams (Sullivan and others, 2009) and urban 

streams (Ryberg and others, 2010).

Pesticide Monitoring Design

The national design for monitoring pesticides in streams 

and rivers has evolved from the combination of two USGS 

programs, NAWQA and NASQAN. NAWQA stream monitoring during 1992–2001 focused on assessing water-quality conditions in 51 of the Nation’s river basins, referred to as “Study 

Units,” on a rotational schedule—20 Study Units during 1992–

95, 16 during 1996–98, and 15 during 1998–2001 (Gilliom 

and others, 2006). Pesticide samples generally were collected 

at each stream site by using a combination of fixed-frequency 

and high-flow sampling (Gilliom and others, 1995). Fixedfrequency sampling means that a given number of waterquality samples were allocated to each month (more samples 

for months with expected higher potential for pesticide runoff 

and fewer samples during months of lower expected potential 

for pesticide runoff), and the water samples were collected 

at regularly spaced intervals within each month. High-flow 

sampling was used to allocate additional water samples to 

characterize high-flow events during seasonal periods of high 

pesticide use and potential runoff. Changes to the design of 

the NAWQA program during 2002–2011 included reduction in 

the number of long-term stream-monitoring sites, an increased 

emphasis on regional assessments, and supplemental highflow sampling was limited to special regional studies. 

The NASQAN program was redesigned in 1995 to estimate the mass flux of pesticides and other constituents at 41 

monitoring sites in four large river systems: the Mississippi, 

the Rio Grande, the Columbia, and the Colorado. Similar to 

the NAWQA program, water samples generally were collected 

at each stream site by using a combination of fixed-frequency 

and high-flow sampling (Hooper and others, 2001). Also 

similar to the NAWQA program, the frequency of waterquality sampling typically changed seasonally, with more 

frequent samples during the peak pesticide-runoff months. 

The NASQAN sampling strategy was revised in 2000 (U.S. 

Geological Survey, 2010), with reduced monitoring in the 

Columbia and Colorado River Basins.

Methods

This report summarizes pesticide stream concentration 

data from samples collected during 2002–11 and compares 

the results to findings from 1992–2001. Site selection was 

based on the number of years with data, watershed size, and 

frequency of sampling within each year. For a sampling 

site, all years of sampling that met the minimum sampling 

criteria were included in the summaries. The summaries for 
Methods 3

both decades are based on the estimated amount of time a 

pesticide was detectable at a stream site and the number of 

times HHBs and chronic ALBs were exceeded. For summary 

purposes, sampling sites were grouped by dominant land-use 

classification. 

Pesticides

During any given year more than 400 different pesticides 

are used in agricultural settings (Stone, 2013). The large number of pesticides in use and the phasing out and introduction 

of new pesticides make it not possible to monitor all pesticides because of budget and method constraints. This report 

includes a selected subset of pesticides in use over the last two 

decades that were sampled at enough sites to attain a reasonable national distribution during 2002–11.

Pesticides included in this report are listed in appendix 

1 (table 1–1). Martin (2009) determined that only pesticide 

data from a single laboratory and analytical method were 

sufficiently extensive in time and space for a national assessment across decades. Hence, only pesticides and pesticide 

data that were analyzed at the National Water-Quality Laboratory (NWQL) by a gas chromatography/mass spectrometry 

(GCMS) method were included in this report. The NAWQA 

and NASQAN programs periodically evaluate the full range of 

pesticides in use to prioritize monitoring to include the most 

important ones in relation to ecosystem and human health 

(Norman and others, 2012). This prioritization process also 

evaluates the likelihood that a pesticide will be found in surface water or sediment, based on chemical properties. During 

2002–11, there were 123 pesticides and pesticide degradates 

with sufficient stream concentration data to include in this 

assessment. Gilliom and others (2006) included 83 pesticides 

in their assessment of 1992–2001; however, only 47 of these 

pesticides were sampled at enough sites during 2002–11 for a 

national-level comparison between the decades. The difference 

between the 47 pesticides assessed during the first decade and 

the 123 pesticides assessed during the second decade included 

39 (or 51 percent) pesticide degradates; 21 (or 28 percent) 

insecticides; 8 (or 11 percent) fungicides; and the remaining 

were herbicides, nematicides, plant growth regulators, and 

defoliants.

Figure 1 shows an overview by one measure—amount 

used—of how pesticides included in this report relate to total 

national use and to selected pesticides or groups not included. 

A large portion of the difference between national total herbicide use and the proportion included in this report was the 

result of increased use of glyphosate that came with the rapid 

adoption of genetically modified crops resistant to glyphosate, beginning in the mid-1990s. Glyphosate is difficult and 

costly to measure, and efforts to assess glyphosate have been 

limited primarily to local or short-term studies. Other types of 

pesticides not comprehensively included in this report, such 

as fungicides and neonicotinoid insecticides, are not individually as prominent as glyphosate in terms of amounts applied, 

but may be environmentally important because of their greater 

toxicity. Finally, some hydrophobic pesticides, such as legacy 

organochlorines and pyrethroid insecticides, are important as 

contaminants of sediment and (or) tissues, but are not often 

found in filtered-water samples.

0

100

200

300

400

500

600

2010200820062004200220001998199619941992

Year

Estimated use, in million pounds

0

20

40

60

80

100

120

200820062004200220001998199619941992 2010

Year

Herbicides Insecticides

Total use* Included in assessment

EXPLANATION

Glyphosate Fungicides Neonicotinoids

*Does not include fumigants or inorganic compounds 

Figure 1. Estimated agricultural use of synthetic organic herbicides, insecticides, and 

fungicides in the conterminous U.S. during first (1992-2001) and second (2002-11) decades of 

stream monitoring. (GfK Kynetec, Inc., proprietary data, written commun., December 2011 and 

July 2013).

Figure 1. Estimated agricultural use of synthetic organic herbicides, insecticides, and fungicides in the conterminous U.S. during first 

(1992–2001) and second (2002–11) decades of stream monitoring. (GfK Kynetec, Inc., proprietary data, written commun., December 2011 

and July 2013).
4 An Overview Comparing Results from Two Decades of Monitoring for Pesticides in the Nation’s Streams and Rivers

Stream-Site Selection

Stream-site selection was based on total number of 

samples each year, watershed size, and the number of samples 

during potentially high pesticide runoff months. A year was 

defined as the water year, beginning October 1 and ending 

September 30. Stream-site selection was based on modification of the criteria used in Stone and others (2013). The 

stream-site selection process began with an evaluation of the 

number of samples collected for the water year compared to 

minimums based on watershed size (table 1). Stream sites 

retained from the previous step were then evaluated to make 

sure there was at least one sample during the months of May, 

June, and July. These three months are typically the months 

of expected higher transport of pesticides to streams for the 

most heavily used pesticides (Stone and others, 2013). Stream 

sites retained to this point were then evaluated to ensure that 

samples were present during times when pesticides are less 

likely transported to streams in order to better represent their 

occurrence during the entire water year. Specifically, each 

stream site could not have a consecutive 3-month period without a sample. The stream-site selection process was done by 

individual pesticide because changing analysis schedules over 

time caused variations in sample numbers between pesticides 

for some years. The stream-site selection process also did not 

limit the selection to a single year; all years of sampling at a 

stream site that met the selection criteria were included in this 

summary. Stream sites selected for the summary are shown in 

figure 2 and listed in appendix 1 (table 1–2).

Table 1. Minimum samples, per water year, by watershed size.

[km2, square kilometer; water year, the 12-month period of October 1, for 

any given year through September 30, of the following year. The water year 

is designated by the calendar year in which it ends and which includes 9 of 

the 12 months]

Watershed size (km2) Minimum number of samples

Less than 500 16

500 to 4,999 12

5,000 to 50,000 10

Greater than 50,000 8

Detection Frequency and Concentration 

Statistics

Time-weighted detection frequencies account for the 

more frequent sample collection during some months than 

in other months and provide an estimate of the percentage of 

time (throughout the water year) that a pesticide was detected. 

The weights were calculated as the amount of time extending 

from one-half the time interval between an observation and the 

preceding observation and one-half the time interval extending 

from the observation to the subsequent observation, divided 

by the total time in one year. Sample weights for a pesticide at 

a stream site sum to one for each year; therefore, the sum of 

the weights for samples with detections represent the percentage of time that pesticide was detected for that stream site and 

year. When there were multiple water years for a stream site 

and pesticide, the median percentage of time detected across 

the years was used for that stream site and pesticide. Both 

the mean and median were evaluated for sites and pesticides 

with multiple water years of data, and there was not a large 

difference between the two statistics for the sites and pesticides used in this summary.

Annual concentration statistics were calculated for each 

stream site and pesticide for comparison to HHBs (Toccalino 

and others, 2014) and chronic ALBs (U.S. Environmental 

Protection Agency Office of Pesticide Program, http://www.

epa.gov/oppefed1/ecorisk_ders/aquatic_life_benchmark.htm, 

accessed July 2013). Specifically, the annual mean concentration for comparison to HHBs, the annual maximum 21-day 

moving-average concentration for comparison to the chronic 

invertebrate ALBs, and the annual maximum 60-day movingaverage concentration for comparison to chronic fish and 

chronic aquatic community (atrazine) ALBs were calculated 

for this comparison. 

Annual mean pesticide concentrations were calculated 

following the methods described in Larson and others (2004). 

Specifically, each observed concentration was weighted 

according to the amount of time it was used to represent the 

pesticide concentration in the stream. The weights were calculated as the amount of time extending from one-half the time 

interval between an observation and the preceding observation 

and one-half the time interval extending from the observation to the subsequent observation, divided by the total time 

in 1 year. Censored observations complicate the calculation 

of annual mean concentrations. As described in Larson and 

others (2004), if less than 10 percent of the weighted data for a 

site, pesticide, and year combination were censored, censored 

observations were replaced by one-half the censoring threshold reported by the laboratory. If more than 10 percent of the 

weighted data were censored, and there were at least 20 annual 

observations with at least 10 uncensored observations and at 

least 33 percent of the sample weights were represented by 

uncensored observations, then the log-regression method (Gilliom and Helsel, 1986; Helsel and Gilliom, 1986) was used to 

approximate the annual mean concentration. Otherwise, the 

annual mean concentration was considered to be censored at 

the censoring threshold reported by the laboratory. For stream 

sites and pesticides with multiple years of data, if an HHB was 

exceeded for a pesticide in any year during the first or second 

decade then the HHB was considered exceeded for that stream 

site and pesticide in the respective decade. 

Annual maximum moving-average pesticide concentrations were calculated following the methods described in 

Stone and others (2008). Hourly pesticide concentrations were 

estimated for each stream site through linear interpolation of 

actual observations. Censored observations were assigned 

a value of zero for the process of linear interpolation. The 

hourly concentration estimates were averaged to obtain an 
EXPLANATION

Sites by land-use classification

Decade Agriculture Urban Mixed

2002–11

1992–2001

Both

Figure 2. The national monitoring network for pesticides in streams and rivers included 182 sites during 1992-2001 and 125 sites during 2002-11, with 96 of the sites common to both decades.

Figure 2. The national monitoring network for pesticides in streams and rivers included 182 sites during 1992–2001 and 125 sites during 2002–11, with both decades.
6 An Overview Comparing Results from Two Decades of Monitoring for Pesticides in the Nation’s Streams and Rivers

estimated daily concentration. The hourly estimates facilitated computations for days with multiple samples but were 

not used for other purposes. Moving-average concentrations 

for the selected durations (21 and 60 days) were computed 

for each day. The annual maximum moving-average pesticide concentrations for each duration were then determined 

for each stream site/year combination meeting the selection 

criteria. In most cases, insufficient observations were available 

for stream sites to calculate moving-average concentrations 

(21- or 60-day durations) for the beginning of the selected year 

used in the summary. For example, if the selected year for a 

stream site was 1993, and there were no observations available 

prior to that year. To address this issue and estimate movingaverage concentrations for the beginning of the selected year, 

the actual observations for the selected year for that stream 

site and pesticide were used as surrogate observations for the 

prior year. For stream sites and pesticides with multiple years 

of data, if a chronic ALB was exceeded for a pesticide in any 

year during the first or second decade then the chronic ALB 

was considered exceeded for that stream site and pesticide in 

the respective decade. 

For discussion and illustration purposes, the percentage 

of time pesticides were detected in streams and percent of 

streams exceeding an HHB or chronic ALB were grouped by 

land-use classification, which is discussed in the subsequent 

section. The percentage of time a pesticide was detected in 

a stream for a land-use classification was normalized by the 

number of stream sites within that land-use classification to 

avoid one stream site having more influence than another in 

the summary.

Land-Use Classifications

The summaries and comparisons in this report group 

streams into three land-use classifications: agriculture, urban, 

and mixed. The land-use classifications and watershed landuse criteria are similar to those used in Gilliom and others 

(2006), with two modifications. First, the 2006 National Land 

Cover Data (NLCD06) was used to classify streams based 

on land use instead of the 1992 enhanced NLCD (NLCDe). 

Second, the amount of urban land use allowable in a watershed for the agriculture stream classification was increased 

from 5 to 10 percent because of the differences in methodology between NLCDe and NLCD06. In addition, Gilliom and 

others (2006) included streams with a land-use classification 

of undeveloped; however, this summary does not include 

streams with this land-use classification. The land-use classifications and watershed land-use criteria are shown in table 2. 

For some streams (fewer than 5 percent), the area within the 

watershed that contributed the majority of water to the stream 

was not reflective of the land use for the total watershed area. 

Differences between the total watershed area and the area contributing the majority of water to a stream can be caused by 

natural landscape variations and water-management practices. 

In these cases, the land-use classification for the stream was 

changed to reflect the land use for the area contributing the 

majority of water to the stream. The land-use classifications 

for each stream are shown in figure 2 and listed in appendix 1 

(table 1–2). The number of stream sites by land-use classification is shown in table 3.

Table 2. Land-use classifications and watershed land-use criteria.

Land-use classification Watershed land-use criteria

Agriculture Greater than 50 percent agricultural land and less than or equal to 10 percent urban land

Urban Greater than 25 percent urban land and less than or equal to 25 percent agricultural land

Undeveloped Less than or equal to 5 percent urban land and less than or equal to 25 percent agriculture land

Mixed All other combinations of agriculture, urban, and undeveloped land use

Table 3. Number of stream sites by land-use classification.

Land-use classification

Number

of stream sites

1992–2001

Number

of stream sites

2002–11

Number of common

stream sites

Agriculture 59 36 28

Mixed 83 59 45

Urban 40 30 23

Total 182 125 96
Pesticide Occurrence 7

Pesticide Occurrence

One or more pesticides or pesticide degradates were 

detectable more than 90 percent of the time in streams across 

all land uses during 2001–11 (table 4). As mentioned previously, the data from this second decade included analysis of 

nearly twice as many pesticides and pesticide degradates than 

the first decade; however, the overall percent of time they 

were detected in streams was nearly the same for both decades 

(table 4). Variations in percent of time pesticides and pesticide 

degradates were detected in streams was more evident for 

individual compounds.

Figure 3 shows the percent of time individual compounds 

were detected in streams. For illustration purposes, only the 

top 20 most frequently detected pesticides and degradates 

by land-use classification and decade are shown. The top 20 

most frequently detected are a composite of the top 10 most 

frequently detected from each land use/decade combination. 

Across all land-use classifications, the herbicides atrazine, 

deethylatrazine (atrazine degradate), metolachlor, and simazine were detected more than 50 percent of the time in streams 

during 2002–11 (fig. 3). The herbicide prometon was detected 

more than 50 percent of the time in mixed and urban land-use 

classification streams during 2002–11. The insecticides fipronil, fipronil sulfide (degradate), and carbaryl, were detected 

more than 50 percent of the time in urban land-use classification streams during 2002–11.

Table 4. Percent of time one or more pesticides or pesticide 

degradates were detected in streams, by land-use classification.

Land-use classification

Percent of time 

detected for 

1992–2001

Percent of time 

detected for 

2002–11

Agriculture 98 95

Mixed 96 96

Urban 98 99

ND

ND

ND

ND

1992–2001

2002–11

0 52 7550 100 0 52 7550 100 0 755025 100

0 52 7550 100 0 52 7550 100 0 755025 100

Mixed

Percentage of time detected

Urban

Atrazine

Deethylatrazine

Metolachlor

Simazine

Prometon

Tebuthiuron

Cyanazine

Acetochlor

Alachlor

Metribuzin

EPTC

Dacthal

Diazinon

Carbaryl

Chlorpyrifos

Agriculture

Insecticides Herbicides

3,4-Dichloroaniline

Fipronil

Desulfinylfipronil

Fipronil sulfide

Metalaxyl

Mixed

Percentage of time detected

Agriculture Urban

Pesticides measured only during 2002–11

Fig. 3 Percentage of time during a year that the most frequently detected pesticides were found 

in streams and rivers in relation to landuse classification

Figure 3. Percentage of time during a year that the most frequently detected pesticides were detected in streams 

and rivers in relation to land-use classification. 
8 An Overview Comparing Results from Two Decades of Monitoring for Pesticides in the Nation’s Streams and Rivers

The herbicides alachlor, cyanazine, EPTC, Dacthal, and 

tebuthiuron were detected less frequently in streams (more 

than 10 percent change) during the second decade than during 

the first decade. Sullivan and others (2009) found generally 

decreasing stream concentration trends for alachlor, cyanazine, 

and EPTC at individual stream sites within the Corn Belt. The 

decrease in the amount of time these pesticides were detected 

in streams between decades may reflect use changes from 

pesticide-registration cancellations and increased use of other 

herbicides. For example, cyanazine registration was voluntarily cancelled in the mid-1990s, which was followed by a 

rapid decline in cyanazine use. Alachlor use steadily declined 

after the introduction of acetochlor in the mid-1990s, which 

was an expected result following the registration of acetochlor 

(de Guzman and others, 2005). In addition, the introduction of 

genetically modified crops that are resistant to the herbicide, 

glyphosate, has seen rapid adoption over the course of the last 

two decades with a corresponding decrease in other herbicides 

over the same time period (fig. 1).

The organophosphate insecticides chlorpyrifos and diazinon were detected less frequently in streams (more than 10 

percent change) during the second decade than during the first 

decade (fig. 3). Sullivan and others (2009) and Ryberg and 

others (2010) found generally decreasing stream concentration trends for these two pesticides at individual stream sites in 

agricultural and urban land-use areas, respectively. The change 

in detection frequency between the two decades for these 

pesticides reflects registration changes and changes in pesticide-use patterns. Various uses of chlorpyrifos and diazinon, 

primarily residential, began being voluntarily cancelled during 

the late-1990s, and these regulatory changes continued into the 

early-2000s. In addition, fipronil was first registered for use in 

the United States in 1996 (Jackson and others, 2009) and was 

suggested as an alternative to organophosphate insecticides for 

residential and commercial turf applications during the early2000s (U.S. Environmental Protection Agency, 2001).

Fipronil was detected in streams across all land-use classifications from 17 to 63 percent of the time during 2002–11 

(fig. 3); however, fipronil was not included in the NAWQA 

and NASQAN efforts during 1992–2001 because it was not 

registered for use until 1996. Ryberg and others (2010) found 

a preponderance of increasing fipronil stream concentration 

trends for urban land-use streams from 2000 to 2008.

An important consideration when comparing detection frequencies over time is the possible impacts of analysis 

instrument changes. The assumption is that improvements in 

laboratory instrumentation could result in increased detection 

sensitivity over time. Alternatively, changes in instrumentation over time could possibly result in decreased sensitivity 

over time. Ryberg and others (2010) evaluated detections of 

trace concentrations in duplicate quality-control water samples 

collected from 1994 to 2005. They found that for most of the 

pesticides evaluated, improvements to instrumentation did 

not result in changes to detection sensitivities through time. 

However, instrumentation improvements did increase the 

detection sensitivity for tebuthiuron and carbaryl (Ryberg 

and others, 2010). As discussed previously, the amount of 

time tebuthiuron was detected in streams decreased from the 

first to the second decade (fig. 3); therefore, improvements to 

instrumentation was not a factor for this pesticide. For carbaryl, the differences in detection frequency between the first 

and second decades were less than 10 percent in all land-use 

classifications.

Concentrations And Benchmark 

Comparisons

Annual mean pesticide concentrations in streams were 

compared to HHBs to provide perspective; however, these 

comparisons are not appropriate for assessing compliance 

with drinking-water regulations, which are applied to treated 

water. The pesticide stream concentrations used in this report 

represent untreated water from sites that are not located at 

drinking-water intakes. 

During 2002–11, one agriculture land-use stream had 

an annual mean pesticide concentration that exceeded an 

HHB (atrazine), and no urban or mixed land-use streams had 

annual mean pesticide concentrations that exceeded HHBs. 

In contrast, 17 percent of the agriculture land-use streams and 

5 percent of mixed land-use streams exceeded HHBs during 

1992–2001. During the previous decade, alpha-HCH (lindane), atrazine, cyanazine, molinate, dieldrin, and propargite 

annual mean concentrations exceeded HHBs in 10 agriculture 

and 4 mixed land-use streams. The differences in the percent 

of streams exceeding an HHB between the first and second 

decade are related to regulatory and use changes. Throughout 

the last three decades, various lindane uses were voluntarily 

cancelled by registrants; the last remaining uses were cancelled in 2006. Sullivan and others (2009) found downward 

trends in atrazine concentrations measured in agriculture 

streams of the Corn Belt. As mentioned previously, cyanazine 

registration was voluntarily cancelled in the mid-1990s, and 

cyanazine use sharply declined from the first to the second 

decade. During the early-2000s, molinate registration was voluntarily cancelled, and use sharply declined during 2002–11. 

Dieldrin registration was voluntarily cancelled during the 

late-1980s, and certain uses of propargite were voluntarily 

cancelled during the mid-1990s.

Pesticide concentrations in streams were compared 

to chronic ALBs. Acute ALBs were not used because the 

sampling frequencies do not adequately represent the highest concentrations that may be present in a stream during the 

year (Crawford, 2004). In addition, differences in sampling 

designs between the two decades limit comparisons between 

the decades based on the highest concentrations measured 

in streams. Specifically, sampling during the first decade 

included samples targeting high-flow events during the season 

when pesticides were expected to be transported to streams, 
Concentrations And Benchmark Comparisons 9

while sampling during the second decade maintained a 

fixed-frequency sampling design. Therefore, comparison of 

the highest pesticide stream concentrations between the two 

decades would be biased.

During 2002–11, nearly two-thirds of agriculture land-use 

classification streams and nearly one-half of mixed land-use 

classification streams exceeded a chronic ALB (table 5). For 

urban land-use classification streams, 90 percent exceeded a 

chronic ALB. The insecticide fipronil exceeded chronic ALBs 

for more than 20 percent of the streams across all land-use 

classifications (fig. 4). The herbicide metolachlor (chronic 

ALB for S-metolachlor) exceeded chronic ALBs for more 

than 10 percent of agriculture and mixed land-use streams. 

Similarly, the insecticide malathion exceeded chronic ALBs 

for more than 10 percent of agriculture and urban land-use 

streams. The insecticides cis-permethrin (chronic ALB for permethrin) and dichlorvos exceeded chronic ALBs for more than 

10 percent of mixed and urban land-use streams, respectively.

Overall, the percent of streams with pesticides that 

exceeded a chronic ALB was very similar between the 

two decades for the agriculture and mixed land-use groups 

(table 5). In terms of pesticides that were evaluated during both decades, the percent of urban land-use streams that 

exceeded a chronic ALB during the second decade was about 

the same as that for the first decade. However the inclusion 

of fipronil and dichlorvos during the second decade nearly 

doubled the percent of urban land-use streams that exceeded 

a chronic ALB during the second decade in comparison to the 

first decade (table 5; fig. 4). 

During 2002–11, there were 21 pesticides that exceeded 

chronic ALBs compared to 16 that exceeded chronic ALBs 

during 1992–2001. Figure 4 shows a subset of the pesticides 

that had annual concentration statistics that exceeded a chronic 

ALB (pesticides and degradates that exceeded a chronic 

ALB for more than 5 percent of the stream sites, by pesticide 

and land-use classification). The second decade had a lower 

percent of streams exceeding a chronic ALB for the herbicide 

metolachlor than the first decade for all land-use classifications. For the agriculture land-use streams, this difference was 

greater than 10 percent. During the last part of the first decade 

Figure 4. Pesticides that exceeded chronic Aquatic Life Benchmarks at more than 5 percent of stream sites and percent 

of streams by land-use classification.

Urban

Metolachlor

Atrazine

Diazinon

Malathion

Chlorpyrifos

Carbaryl

Azinphos methyl

cis-Permethrin

Disulfoton

Parathion

Agriculture

1992–2001

2002–11

Mixed

Urban

Fipronil

Fipronil sulfone

Dichlorvos

Agriculture Mixed

0 10 50403020 60 70 0 10 50403020 60 70 0 10 403020 50 60 70

0 10 50403020 60 70 0 10 50403020 60 70 0 10 403020 50 60 70

Percent of stream sites exceeding chronic Aquatic Life Benchmarks

Percent of stream sites exceeding chronic Aquatic Life Benchmarks

Pesticides measured only during 2002–11

Herbicides Insecticides

Figure 4. Pesticides that exceeded chronic Aquatic Life Benchmarks at more than 5 percent of 

stream sites and percent of streams by land-use classification.
10 An Overview Comparing Results from Two Decades of Monitoring for Pesticides in the Nation’s Streams and Rivers

Table 5. Percent of streams with one or more pesticide 

concentration statistics that exceeded a chronic Aquatic Life 

Benchmark (ALB), by land-use classification.

Land-use 

classification

Percent of streams 

exceeding 

ALB 1992–2001

Percent of streams 

exceeding 

ALB 2002–11

Agriculture 69 61

Mixed 45 46

Urban 53 90

replaced by the resolved isomer S-metolachlor, which reduces 

the amount of pesticide required for the same agronomic 

effect (Hartzler, 2000). Although metolachlor was detected in 

streams for nearly the same amount of time for both decades 

(fig. 3), the decreased use (in terms of mass applied) because 

of the introduction of S-metolachlor likely contributed to the 

decrease in the percent of streams that exceeded a chronic 

ALB during 2002–11 when compared to 1992–2001.

For streams in the urban land-use classification group, 

the organophosphate insecticides chlorpyrifos, diazinon, and 

malathion, and the carbamate insecticide carbaryl all had 

decreases (greater than 10 percent) in the percent of streams 

exceeding a chronic ALB from the first decade to the second 

decade (fig. 4). This is consistent with the decreasing stream 

concentration trends found by Ryberg and others (2010) 

for chlorpyrifos and diazinon in individual urban land-use 

streams. These pesticides also were detected less frequently in 

streams during 1992–2001 compared to 2002–11 (fig. 3). In 

contrast, the percent of streams, across all land-use classifications, exceeding a chronic ALB for fipronil during the second 

decade was greater than all other insecticides during both 

decades. As discussed previously, fipronil registration and use 

began toward the end of the first decade and was a suggested 

alternative for organophosphate insecticides during the second 

decade. 

Summary

This report provides an overview of U.S. Geological 

Survey National Water-Quality Assessment (NAWQA) and 

National Stream Quality Accounting Network (NASQAN) 

findings for pesticide occurrence (percent of time pesticides 

were detected) in U.S. streams during 2002–11 and compares 

them to findings during 1992–2001. In addition, pesticide 

stream concentrations are compared to Human Health Benchmark (HHBs) and chronic Aquatic Life Benchmark (ALBs) 

and differences between the decades discussed. 

Direct and simple, one to one comparisons of pesticides 

in stream water between the two decades are not possible 

because of changes in stream sampling sites, sampling 

designs, and pesticides monitored within the programs over 

the last two decades. The comparisons in this report are from 

a site selection and land-use classification based on 2002–11 

information that is applied to evaluate results for the 1992–

2001 sites. In addition, the most current chronic ALBs are 

used in comparison to annual concentration statistics.

During 2002–11, atrazine, deethylatrazine (atrazine 

degradate), carbaryl, fipronil, fipronil sulfide (fipronil degradate), metolachlor, prometon, and simazine were detected 

more than 50 percent of the time in streams. One or more 

pesticides or pesticide degradates were detected more than 90 

percent of the time in streams across all land uses during both 

decades. The overall amount of time pesticides were detected 

in streams was nearly the same between the first and second 

decades. However, there were differences between the two 

decades when comparing individual pesticides. The herbicides alachlor, cyanazine, EPTC, Dacthal, and tebuthiuron 

were detected less frequently in streams during 2002–11 than 

during 1992–2001. Regulatory changes and the increased use 

of acetochlor and glyphosate between the first decade and 

the second decade may be contributing to the decrease in the 

amount of time these pesticides were detected in streams. The 

organophosphate insecticides diazinon and chlorpyrifos were 

detected less frequently during 2002–11 than during 1992–

2001. Product registration changes as well as the registration 

of the insecticide fipronil during the last part of the first decade 

may be contributing to the decrease in the amount of time 

these pesticides were detected in streams.

When stream concentration statistics were compared to 

HHBs, only one agriculture land-use stream had an annual 

mean pesticide concentration that exceeded an HHB (atrazine) 

during 2002–11. In contrast, during 1992–2001, about 17 percent of the agriculture land-use streams and one mixed landuse stream exceeded HHBs. The HHB exceedance difference 

between the first and second decades was the result of regulatory changes; specifically, cancellation of pesticide registration 

and subsequent decreased use.

During 2002–11, most agriculture and urban land-use 

classification streams and nearly one-half of mixed land-use 

classification streams had pesticide concentration statistics 

that exceeded a chronic ALB. The overall percent of streams 

that exceeded a chronic ALB was very similar between the 

two decades for agricultural and mixed land-use classification 

streams. However, for urban land-use classification streams 

the percent of streams exceeding a chronic ALB during 2002–

11 nearly doubled that seen during 1992–2001. The inclusion 

of fipronil and dichlorvos monitoring during 2002–11 was the 

reason for this difference.

The summaries and comparisons between the two 

decades in this report were intended to be simple and descriptive overviews and not substitutes for more quantitative 

trend analysis that account for streamflow and other factors. 

Pesticide stream concentration trends at individual stream sites 

have been evaluated with more rigorous analysis methods 

for regions of the U.S. and selected time periods during these 

decades (Sullivan and others, 2009; Ryberg and others, 2010). 

Pesticide stream concentration trends using NAWQA and 

NASQAN results will continue to be evaluated in a series of 

studies involving quantitative site-based trend models.
References Cited 11

References Cited

Crawford, C.G., 2004, Sampling strategies for estimating 

acute and chronic exposures of pesticides in streams: Journal of the American Water Resources Association, v. 40, no. 

2, p. 485–502, DOI:10.1111/j.1752-1688.2004.tb01045.x.

de Guzman, N.P., Hendley, P., Gustafson, D.I., van Wesenbeeck, I., Klein, A.J., Fuhrman, J.D., Travis, K., Simmons, 

N.D., Teskey, W.E., and Durham, R.B, 2005, The Acetochlor Registration Partnership state ground water monitoring program: Journal of Environmental Quality, v. 34, 

p. 793–803, doi:10.2134/jeq2003.0412.

Gilliom, R.J., Alley, W.M., and Gurtz, M.E., 1995, Design 

of the National Water-Quality Assessment Program—

Occurrence and distribution of water-quality conditions: 

U.S. Geological Survey Circular 1112, 33 p. 

Gilliom, R.J., Barbash, J.E., Crawford, C.G., Hamilton, P.A., 

Martin, J.D., Nakagaki, Naomi, Nowell, L.H., Scott, J.C., 

Stackelberg, P.E., Thelin, G.P., and Wolock, D.M., 2006, 

The quality of our Nation’s waters—Pesticides in the 

Nation’s streams and ground water, 1992–2001: U.S. 

Geological Survey Circular 1291, 172 p.

Gilliom, R.J., and Helsel, D.R., 1986, Estimation of distributional parameters for censored trace level water quality data 

1—Estimation techniques: Water Resources Research, v. 22, 

no. 2, p. 135–146, DOI:10.1029/WR022i002p00135.

Hartzler, Bob, 2000, Resolved isomers explained: Ames, Iowa, 

Iowa State University, Weed Science, accessed February 

14, 2014, at http://www.weeds.iastate.edu/mgmt/qtr00-1/

isomers.htm.

Helsel, D.R., and Gilliom, R.J., 1986, Estimation of distributional parameters for censored trace level water quality 

data, 2—Verification and applications: Water Resources 

Research, v. 22, no. 2, p. 147–155, DOI:10.1029/

WR022i002p00147.

Hooper, R.P., Aulenbach, B.T., and Kelly, V.J., 2001, The 

National Stream Quality Accounting Network—A fluxbased approach to monitoring the water quality of large 

rivers: Hydrological Processes, v. 15, p. 1089–1106.

Jackson, D., Cornell, C.B., Luukinen, B., Buhl, K., and Stone, 

D., 2009, Fipronil Technical Fact Sheet: National Pesticide 

Information Center, Oregon State University Extension 

Services, accessed July 21, 2014, at http://npic.orst.edu/

factsheets/fiptech.pdf.

Larson, S.J., Crawford, C.G., and Gilliom, R.J., 2004, 

Development and application of Watershed Regressions 

for Pesticides (WARP) for estimating atrazine concentration 

distributions in streams: U.S. Geological Survey WaterResources Investigations Report 03–4047, 68 p.

Martin, J.D., 2009, Sources and preparation of data for assessing trends in concentrations of pesticides in streams of the 

United States, 1992–2006: U.S. Geological Survey Scientific Investigations Report 2009–5062, 41 p.

Norman, J.E., Kuivila, K.M., and Nowell, L.H., 2012, Prioritizing pesticide compounds for analytical methods development: U.S. Geological Survey Scientific Investigations 

Report 2012–5045, 206 p.

Ryberg, K.R., Vecchia, A.V., Martin, J.D., and Gilliom, R.J., 

2010, Trends in pesticide concentrations in urban streams 

in the United States, 1992–2008: U.S. Geological Survey 

Scientific Investigations Report 2010–5139, 101 p.

Stone, W.W., 2013, Estimated annual agricultural pesticide use 

for counties of the conterminous United States, 1992–2009: 

U.S. Geological Survey Data Series 752, 1–p. pamphlet, 

14 tables.

Stone, W.W., Crawford, C.G., and Gilliom, R.J, 2013, Watershed Regressions for Pesticides (WARP) models for predicting stream concentrations of multiple pesticides: Journal 

of Environmental Quality, v. 42, no. 6, p. 1838–1851, 

doi:10.2134/jeq2013.05.0179.

Stone, W.W., Gilliom, R.J., and Crawford, C.G., 2008, Watershed Regressions for Pesticides (WARP) for predicting 

annual maximum and maximum moving-average concentrations of atrazine in streams: U.S. Geological Survey OpenFile Report 2008–1186, 19 p.

Sullivan, D.J., Vecchia, A.V., Lorenz, D.L., Gilliom, R.J., 

and Martin, J.D., 2009, Trends in pesticide concentrations 

in corn-belt streams, 1996–2006: U.S. Geological Survey 

Scientific Investigations Report 2009–5132, 75 p.

Toccalino, P.L., Norman, J.E., and Schoephoester, K.M., 2014, 

Health-based screening levels for evaluating water-quality 

data: U.S. Geological Survey National Water-Quality 

Assessment Program, updated June 2014, accessed July 22, 

2014, at http://water.usgs.gov/nawqa/HBSL.

U.S. Environmental Protection Agency, 2001, FY2001 conventional pesticides registration decisions, accessed February 14, 2014, at http://www.epa.gov/opprd001/workplan/

regdec2001.pdf.

U.S. Geological Survey, 2010, NASQAN National Stream 

Quality Accounting Network, 2001–2007 NASQAN design 

information, accessed September 15, 2011, at http://water.

usgs.gov/nasqan/2001_2007_design_info.html.

Appendix 13

Appendix 1.

Table 1–1. Pesticide compounds used in the 1992–2001 and 2002–11 summaries........................14

Table 1–2. Stream sites used in the first decade (1992–2001) and second decade 

(2002–11) summaries......................................................................................................................18
14 An overview comparing results from two decades of monitoring for pesticides in the Nation’s streams and rivers

Table 1–1. Pesticide compounds used in the 1992–2001 and 2002–11 summaries.—Continued

[CASRN, Chemical Abstracts Service Registry Number®;—, not applicable]

 Pesticide compound

(synonym)

Type of pesticide compound 

(parent pesticide, if degradate) CASRN1 Parameter code

1992–

2001 2002–11

Acetochlor Herbicide 34256-82-1 49260 Yes Yes

Alachlor Herbicide 15972-60-8 46342 Yes Yes

2,6-Diethylaniline Degradate (Alachlor) 579-66-8 82660 Yes Yes

2-Chloro-2,6-diethylacetanilide Degradate (Alachlor) 6967-29-9 61618 Yes

alpha-Endosulfan Insecticide 959-98-8 34362 Yes

Endosulfan ether Degradate (alpha-Endosulfan) 3369-52-6 61642 Yes

Endosulfan sulfate Degradate (alpha-Endosulfan, 

beta-Endosulfan)

1031-07-8 61590 Yes

Atrazine Herbicide 1912-24-9 39632 Yes Yes

Deethylatrazine Degradate (Atrazine) 6190-65-4 04040 Yes Yes

Azinphos-methyl (Guthion) Insecticide 86-50-0 82686 Yes Yes

Azinphos-methyl-oxon Degradate (Azinphos-methyl) 961-22-8 61635 Yes

Benfluralin Herbicide 1861-40-1 82673 Yes Yes

2-Amino-N-isopropylbenzamide Degradate (Bentazon) 30391-89-0 61617 Yes

beta-Endosulfan Insecticide 33213-65-9 34357 Yes

Bifenthrin Insecticide 82657-04-3 61580 Yes

Butylate Herbicide 2008-41-5 04028 Yes Yes

Carbaryl Insecticide 63-25-2 82680 Yes Yes

1-Naphthol Degradate (Carbaryl, Napromide) 90-15-3 49295 Yes

Carbofuran Insecticide 1563-66-2 82674 Yes Yes

2,5-Dichloroaniline Degradate (Chloramben) 95-82-9 61614 Yes

Chlorpyrifos Insecticide 2921-88-2 38933 Yes Yes

Chlorpyrifos_oxon Degradate (Chlorpyrifos) 5598-15-2 61636 Yes

cis-Permethrin Insecticide 61949-76-6 82687 Yes Yes

cis-Propiconazole Fungicide 112721-87-6 79846 Yes

Cyanazine Herbicide 21725-46-2 04041 Yes Yes

Cycloate Herbicide 1134-23-2 04031 Yes

Cyfluthrin Insecticide 68359-37-5 61585 Yes

cis-Methyl-3-(2,2-dichlorovinyl)-

2,2-dimethyl-(1-cyclopropane)-

carboxylate

Degradate (Cyfluthrin) 59897-93-7 79842 Yes

trans-Methyl-3-(2,2-dichlorovinyl)-

2,2-dimethyl-(1-cyclopropane)-

carboxylate

Degradate (Cyfluthrin) 59897-94-8 79843 Yes

Cypermethrin Insecticide 52315-07-8 61586 Yes

Dacthal (DCPA) Herbicide 1861-32-1 82682 Yes Yes

Diazinon Insecticide 333-41-5 39572 Yes Yes

Diazoxon Degradate (Diazinon) 962-58-3 61638 Yes

Dichlorvos Insecticide/Fumigant/Degradate 

(Naled)

62-73-7 38775 Yes

Dicrotophos Insecticide 141-66-2 38454 Yes
Appendix 15

Table 1–1. Pesticide compounds used in the 1992–2001 and 2002–11 summaries.—Continued

[CASRN, Chemical Abstracts Service Registry Number®;—, not applicable]

 Pesticide compound

(synonym)

Type of pesticide compound 

(parent pesticide, if degradate) CASRN1 Parameter code

1992–

2001 2002–11

Dieldrin

Dimethoate

Disulfoton

Disulfoton_sulfone

Disulfoton_sulfoxide

E-Dimethomorph

3,4-Dichloroaniline

EPTC

Ethalfluralin

Ethion

Ethion_monoxon

Ethoprophos (Ethoprop)

O-Ethyl-O-methyl-S-propylphosphorothioate

Fenamiphos

Fenamiphos_sulfone

Fenamiphos_sulfoxide

Fenthion

Fenthion_sulfoxide

Fipronil

Desulfinylfipronil

Desulfinylfipronil_amide

Fipronil_sulfide

Fipronil_sulfone

Flumetralin

3-(Trifluoromethyl)aniline

Fonofos

gamma-HCH (Lindane)

alpha-HCH

Hexazinone

Iprodione

3,5-Dichloroaniline

Isofenphos

lambda-Cyhalothrin

Linuron

Malathion

Malaoxon

Metalaxyl

4-Chloro-2-methylphenol

Methidathion

Insecticide

Insecticide

Insecticide

Degradate (Disulfoton)

Degradate (Disulfoton)

Fungicide

Degradate (Diuron)

Herbicide

Herbicide

Insecticide

Degradate (Ethion)

Insecticide

Degradate (Ethoprophos)

Nematocide

Degradate (Fenamiphos)

Degradate (Fenamiphos)

Insecticide

Degradate (Fenthion)

Insecticide

Degradate (Fipronil)

Degradate (Fipronil)

Degradate (Fipronil)

Degradate (Fipronil)

Plant_Growth_Regulator

Degradate (Fluometuron)

Insecticide

Insecticide

Degradate (gamma-HCH)

Herbicide

Fungicide

Degradate (Iprodione)

Insecticide

Insecticide

Herbicide

Insecticide

Degradate (Malathion)

Fungicide

Degradate (MCPA)

Insecticide

60-57-1

60-51-5

298-04-4

2497-06-5

2497-07-6

—

95-76-1

759-94-4

55283-68-6

563-12-2

17356-42-2

13194-48-4

76960-87-7

22224-92-6

31972-44-8

31972-43-7

55-38-9

3761-41-9

120068-37-3

—

—

120067-83-6

120068-36-2

62924-70-3

98-16-8

944-22-9

58-89-9

319-84-6

51235-04-2

36734-19-7

626-43-7

25311-71-1

91465-08-6

330-55-2

121-75-5

1634-78-2

57837-19-1

1570-64-5

950-37-8

39381

82662

82677

61640

61641

79844

61625

82668

82663

82346

61644

82672

61660

61591

61645

61646

38801

61647

62166

62170

62169

62167

62168

61592

61630

04095

39341

34253

04025

61593

61627

61594

61595

82666

39532

61652

61596

61633

61598

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes
16 An overview comparing results from two decades of monitoring for pesticides in the Nation’s streams and rivers

Table 1–1. Pesticide compounds used in the 1992–2001 and 2002–11 summaries.—Continued

[CASRN, Chemical Abstracts Service Registry Number®;—, not applicable]

 Pesticide compound

(synonym)

Type of pesticide compound 

(parent pesticide, if degradate) CASRN1 Parameter code

1992–

2001 2002–11

Metolachlor

2-Ethyl-6-methylaniline

Metribuzin

Molinate

Myclobutanil

Napropamide

1,4-Napthaquinone

Oxyfluorfen

p,p’-DDE

4,4’-Dichlorobenzophenone

Paraoxon-ethyl

Parathion (Ethyl parathion)

Parathion-methyl (Methyl parathion)

Paraoxon-methyl

Pebulate

Pendimethalin

Phorate

Phorate_oxon

Phosmet

Phosmet_oxon

Profenofos

Prometon

Prometryn

Propachlor

Propanil

Propargite

2-(4-tert-butylphenoxy)-cyclohexanol

Propetamphos

Propyzamide (Pronamide)

Simazine

Sulfotepp

Sulprofos

Tebuconazole

Tebupirimfos

Tebupirimfos_oxon

Tebuthiuron

Tefluthrin

Temephos

Terbacil

Herbicide

Degradate (Metolaclor)

Herbicide

Herbicide

Fungicide

Herbicide

Degradate (Napromide)

Herbicide

Degradate (DDT)

Degradate (DDT, Dicofol)

Insecticide/Degradate (Parathion)

Insecticide

Insecticide

Degradate (Methyl parathion)

Herbicide

Herbicide

Insecticide

Degradate (Phorate)

Insecticide

Degradate (Phosmet)

Insecticide

Herbicide

Herbicide

Herbicide

Herbicide

Acaricide

Degradate (Propargite)

Insecticide

Herbicide

Herbicide

Insecticide

Insecticide

Fungicide

Insecticide

Degradate (Tebupirimfos)

Herbicide

Insecticide

Insecticide

Herbicide

51218-45-2

24549-06-2

21087-64-9

2212-67-1

88671-89-0

15299-99-7

130-15-4

42874-03-3

72-55-9

90-98-2

311-45-5

56-38-2

298-00-0

950-35-6

1114-71-2

40487-42-1

298-02-2

2600-69-3

732-11-6

3735-33-9

41198-08-7

1610-18-0

7287-19-6

1918-16-7

709-98-8

2312-35-8

1942-71-8

31218-83-4

23950-58-5

122-34-9

3689-24-5

35400-43-2

107534-96-3

96182-53-5

—

34014-18-1

79538-32-2

3383-96-8

5902-51-2

39415

61620

82630

82671

61599

82684

61611

61600

34653

61631

61663

39542

82667

61664

82669

82683

82664

61666

61601

61668

61603

04037

04036

04024

82679

82685

61637

61604

82676

04035

61605

38716

62852

61602

61669

82670

61606

61607

82665

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes
Appendix 17

Table 1–1. Pesticide compounds used in the 1992–2001 and 2002–11 summaries.—Continued

[CASRN, Chemical Abstracts Service Registry Number®;—, not applicable]

 Pesticide compound

(synonym)

Type of pesticide compound 

(parent pesticide, if degradate) CASRN1 Parameter code

1992–

2001 2002–11

Terbufos Insecticide 13071-79-9 82675 Yes Yes

Terbufos_sulfone_oxygen_analog Degradate (Terbufos) 56070-15-6 61674 Yes

Terbuthylazine Herbicide 5915-41-3 04022 Yes

Thiobencarb Herbicide 28249-77-6 82681 Yes Yes

4-Chlorobenzylmethyl_sulfone Degradate (Thiobencarb) 98-57-7 61634 Yes

trans-Propiconazole Fungicide 120523-07-1 79847 Yes

Triallate Herbicide 2303-17-5 82678 Yes Yes

Tribuphos Defoliant 78-48-8 61610 Yes

Trifluralin Herbicide 1582-09-8 82661 Yes Yes

Z-Dimethomorph Fungicide — 79845 Yes

1

This report contains CAS Registry Numbers®, which is a Registered Trademark of the American Chemical Society. CAS recommends the verification 

of the CASRNs through CAS Client ServicesSM.
18 An overview comparing results from two decades of monitoring for pesticides in the Nation’s streams and rivers

Table 1–2. Stream sites used in the first decade (1992–2001) and second decade (2002–11) summaries.—Continued

[km2, square kilometer; Cr, Creek; Ri, River; Irr Dist; Irrigation District; No., number; MA, Massachusetts; CT, Connecticut; NY, New York; 

NJ, New Jersey; PA, Pennsylvania; MD, Maryland; VA, Virginia; WV, West Virginia; DC, District of Columbia; NC, North Carolina; SC, South 

Carolina; GA, Georgia; FL, Florida; AL, Alabama; OH, Ohio; IN, Indiana; TN, Tennessee; KY, Kentucky; IL, Illinois; WI, Wisconsin; MI, Michigan; 

MN, Minnesota; ND, North Dakota; IA, Iowa; MT, Montana; WY, Wyoming; CO, Colorado; NE, Nebraska; MO, Missouri; AR, Arkansas; 

MS, Mississippi; LA, Louisiana; TX, Texas; AZ, Arizona; VT, Vermont; NV, Nevada; CA, California; WA, Washington; ID, Idaho; OR, Oregon]

Site number Site name Watershed area 

(km2

) Land use

Number of years

1992–

2001 2002–11

01102500 Aberjona River at Winchester, MA 60 Urban 2

01104615 Charles River near Watertown, MA 695 Urban 2

01184000 Connecticut River at Thompsonville, CT 25,000 Mixed 4 3

01209710 Norwalk River at Winnipauk, CT 85 Urban 5 3

01349150 Canajoharie Creek near Canajoharie, NY 155 Agriculture 5 3

01356190 Lisha Kill northwest of Niskayuna, NY 40 Urban 1 3

01357500 Mohawk River at Cohoes, NY 9,110 Mixed 8 2

01403300 Raritan River at Bound Brook, NJ 2,070 Urban 3 6

01403900 Bound Brook at Middlesex, NJ 126 Urban 2 2

01410784 Great Egg Harbor River near Sicklerville, NJ 39 Urban 2

01454700 Lehigh River at Easton, PA 3,520 Mixed 1

01463500 Delaware River at Trenton, NJ 17,600 Mixed 2 2

01464907 Little Neshaminy Creek near Warminster, PA 72 Urban 2 1

01470779 Tulpehocken Creek near Bernville, PA 179 Mixed 2

01472157 French Creek near Phoenixville, PA 152 Mixed 1

01474500 Schuylkill River at Philadelphia, PA 4,900 Mixed 2

01485000 Pocomoke River at Willards, MD 138 Mixed 1

01493112 Chesterville Branch near Crumpton, MD 17 Agriculture 1

01493500 Morgan Creek near Kennedyville, MD 33 Agriculture 3

01555400 East Mahantango Creek at Klingerstown, PA 116 Agriculture 2

01571490 Cedar Run at Eberlys Mill, PA 33 Urban 3

01573095 Bachman Run at Annville, PA 20 Mixed 1

01576540 Mill Creek near Lyndon, PA 141 Mixed 2

01578310 Susquehanna River at Conowingo, MD 70,100 Mixed 2 6

01621050 Muddy Creek at Mount Clinton, VA 37 Agriculture 2 3

01636500 Shenandoah River at Millville, WV 7,880 Mixed 1

01639000 Monocacy River at Bridgeport, MD 449 Mixed 1

01646580 Potomac River at Washington, DC 30,000 Mixed 4 7

01654000 Accotink Creek near Annandale, VA 61 Urban 2 4

02082731 Devils Cradle Creek near Alert, NC 35 Mixed 1

02083500 Tar River at Tarboro, NC 5,750 Mixed 1

02083833 Pete Mitchell Swamp near Penny Hill, NC 45 Agriculture 1

02084160 Chicod Cr near Simpson, NC 109 Mixed 1 1

02084558 Albemarle Canal near Swindell, NC 191 Agriculture 1

02087580 Swift Creek near Apex, NC 54 Urban 5

02089500 Neuse River at Kinston, NC 7,020 Mixed 4 7
Appendix 19

Table 1–2. Stream sites used in the first decade (1992–2001) and second decade (2002–11) summaries.—Continued

[km2, square kilometer; Cr, Creek; Ri, River; Irr Dist; Irrigation District; No., number; MA, Massachusetts; CT, Connecticut; NY, New York; 

NJ, New Jersey; PA, Pennsylvania; MD, Maryland; VA, Virginia; WV, West Virginia; DC, District of Columbia; NC, North Carolina; SC, South 

Carolina; GA, Georgia; FL, Florida; AL, Alabama; OH, Ohio; IN, Indiana; TN, Tennessee; KY, Kentucky; IL, Illinois; WI, Wisconsin; MI, Michigan; 

MN, Minnesota; ND, North Dakota; IA, Iowa; MT, Montana; WY, Wyoming; CO, Colorado; NE, Nebraska; MO, Missouri; AR, Arkansas; 

MS, Mississippi; LA, Louisiana; TX, Texas; AZ, Arizona; VT, Vermont; NV, Nevada; CA, California; WA, Washington; ID, Idaho; OR, Oregon]

Site number Site name Watershed area 

(km2

) Land use

Number of years

1992– 2002–11 2001

02091500

02169570

02174250

02175000

02215100

02226160

02281200

02289034

02306774

02317797

02318500

02326838

02335870

02336300

02338000

02350080

02356980

02359170

02424000

02429500

02444490

02469762

02470500

03049625

03049646

03167000

03176500

03201300

03267900

03274000

03303280

03353637

03357330

03360895

03374100

03378500

Contentnea Creek at Hookerton, NC

Gills Creek at Columbia, SC

Cow Castle Creek near Bowman, SC

Edisto River near Givhans, SC

Tucsawhatchee Creek near Hawkinsville, GA

Altamaha River near Everett City, GA

Hillsboro Canal near Shawano, FL

U.S. Sugar Outflow Canal near Clewiston, FL

Rocky Creek near Citrus Park, FL

Little River near Tifton, GA

Withlacoochee River near Quitman, GA

Lafayette Creek near Tallahassee, FL

Sope Creek near Marietta, GA

Peachtree Creek at Atlanta, GA

Chattahoochee River near Whitesburg, GA

Lime Creek near Cobb, GA

Aycocks Creek near Boykin, GA

Apalachicola River near Sumatra, FL

Cahaba River at Centreville, AL

Alabama River at Claiborne, AL

Bogue Chitto near Memphis, AL

Tombigbee River near Coffeeville, AL

Mobile River at Mt. Vernon, AL

Allegheny River at New Kensington, PA

Deer Creek near Dorseyville, PA

Reed Creek at Grahams Forge, VA

New River at Glen Lyn, VA

Kanawha River at Winfield, WV

Mad River near Eagle City, OH

Great Miami River at Hamilton, OH

Ohio River at Cannelton Dam at Cannelton, IN

Little Buck Creek near Indianapolis, IN

Big Walnut Creek near Roachdale, IN

Kessinger Ditch near Monroe City, IN

White River at Hazleton, IN

Wabash River at New Harmony, IN

1,910

154

62

7,080

420

36,100

806

73

46

335

3,860

25

80

222

6,250

162

271

49,800

2660

56,900

136

47,800

111,400

29,700

70

669

9,780

30,600

802

9,400

251,200

45

339

146

29,300

75,700

Agriculture

Urban

Mixed

Mixed

Mixed

Mixed

Agriculture

Agriculture

Urban

Mixed

Mixed

Urban

Urban

Urban

Urban

Mixed

Mixed

Mixed

Mixed

Mixed

Agriculture

Mixed

Mixed

Mixed

Urban

Mixed

Mixed

Mixed

Agriculture

Mixed

Mixed

Urban

Agriculture

Agriculture

Mixed

Agriculture

3

1

2

4

1

3

1

1

3

2

2

1

3

2

1

2

1

1

1

1

1

1

1

3

2

6

3

1

10

5

3

2

2

3

4

1

2

1

3

4

7

4

1

1

3

1

4

3

10

2

2

7

10
20 An overview comparing results from two decades of monitoring for pesticides in the Nation’s streams and rivers

Table 1–2. Stream sites used in the first decade (1992–2001) and second decade (2002–11) summaries.—Continued

[km2, square kilometer; Cr, Creek; Ri, River; Irr Dist; Irrigation District; No., number; MA, Massachusetts; CT, Connecticut; NY, New York; 

NJ, New Jersey; PA, Pennsylvania; MD, Maryland; VA, Virginia; WV, West Virginia; DC, District of Columbia; NC, North Carolina; SC, South 

Carolina; GA, Georgia; FL, Florida; AL, Alabama; OH, Ohio; IN, Indiana; TN, Tennessee; KY, Kentucky; IL, Illinois; WI, Wisconsin; MI, Michigan; 

MN, Minnesota; ND, North Dakota; IA, Iowa; MT, Montana; WY, Wyoming; CO, Colorado; NE, Nebraska; MO, Missouri; AR, Arkansas; 

MS, Mississippi; LA, Louisiana; TX, Texas; AZ, Arizona; VT, Vermont; NV, Nevada; CA, California; WA, Washington; ID, Idaho; OR, Oregon]

Watershed area Number of years

Site number Site name Land use (km2

) 1992– 2002–11 2001

03455000 French Broad River near Newport, TN 4,800 Mixed 1

03466208 Big Limestone Creek near Limestone, TN 205 Agriculture 2 1

03467609 Nolichucky River near Lowland, TN 4,370 Mixed 2 1

03526000 Copper Creek near Gate City, VA 277 Mixed 1

03528000 Clinch River above Tazewell, TN 3,820 Mixed 1

03575100 Flint River near Brownsboro, AL 969 Agriculture 3 2

03609750 Tennessee River at Highway 60 near Paducah, 104,500 Mixed 5 4

KY

03612500 Ohio River at Dam 53 near Grand Chain, IL 526,000 Mixed 6 10

04072050 Duck Creek near Howard, WI 247 Agriculture 3 3

04087000 Milwaukee River at Milwaukee, WI 1,810 Mixed 3 2

04159492 Black River near Jeddo, MI 1,200 Agriculture 1

04161820 Clinton River at Sterling Heights, MI 803 Urban 1 2

04175600 River Raisin near Manchester, MI 331 Mixed 1

04178000 St. Joseph River near Newville, IN 1,600 Agriculture 2

04183000 Maumee River at New Haven, IN 5,040 Mixed 1

04186500 Auglaize River near Fort Jennings, OH 858 Agriculture 1 2

04193500 Maumee River at Waterville, OH 16,400 Mixed 5 3

04208504 Cuyahoga River at Cleveland, OH 2,040 Urban 1

04211820 Grand Ri at Harpersfield, OH 1,430 Mixed 1

04213500 Cattaraugus Creek at Gowanda, NY 1,130 Mixed 1

05062500 Wild Rice River at Twin Valley, MN 2,410 Mixed 1

05082625 Turtle River near Arvilla, ND 658 Agriculture 1

05085900 Snake River above Alvarado, MN 566 Agriculture 1

05102490 Red River of the North at Pembina, ND 92,100 Agriculture 5

05288705 Shingle Creek at Minneapolis, MN 73 Urban 1 3

05320270 Little Cobb River near Beauford, MN 336 Agriculture 1 2

05330000 Minnesota River near Jordan, MN 42,000 Agriculture 2

05330902 Nine Mile Creek at Bloomington, MN 116 Urban 1

05331580 Mississippi River at Hastings, MN 96,000 Agriculture 5 3

05420500 Mississippi River at Clinton, IA 221,700 Mixed 6 10

05420680 Wapsipinicon River near Tripoli, IA 897 Agriculture 1

05449500 Iowa River near Rowan, IA 1,080 Agriculture 2

05451210 South Fork Iowa River near New Providence, IA 581 Agriculture 2 5

05455570 English River at Riverside, IA 1,620 Agriculture 1

05464220 Wolf Creek near Dysart, IA 775 Agriculture 2

05465500 Iowa River at Wapello, IA 32,400 Agriculture 5 3
Appendix 21

Table 1–2. Stream sites used in the first decade (1992–2001) and second decade (2002–11) summaries.—Continued

[km2, square kilometer; Cr, Creek; Ri, River; Irr Dist; Irrigation District; No., number; MA, Massachusetts; CT, Connecticut; NY, New York; 

NJ, New Jersey; PA, Pennsylvania; MD, Maryland; VA, Virginia; WV, West Virginia; DC, District of Columbia; NC, North Carolina; SC, South 

Carolina; GA, Georgia; FL, Florida; AL, Alabama; OH, Ohio; IN, Indiana; TN, Tennessee; KY, Kentucky; IL, Illinois; WI, Wisconsin; MI, Michigan; 

MN, Minnesota; ND, North Dakota; IA, Iowa; MT, Montana; WY, Wyoming; CO, Colorado; NE, Nebraska; MO, Missouri; AR, Arkansas; 

MS, Mississippi; LA, Louisiana; TX, Texas; AZ, Arizona; VT, Vermont; NV, Nevada; CA, California; WA, Washington; ID, Idaho; OR, Oregon]

Site number Site name Watershed area 

(km2

) Land use

Number of years

1992– 2002–11 2001

05490500

05525500

05531500

05532500

05553500

05572000

05584500

05586100

05587455

06208500

06279500

06295000

06329500

06713500

06714000

06753990

06754000

06795500

06800000

06800500

06805500

06923150

06934500

07022000

07031692

07043500

07053250

07263620

07288650

07288955

07369500

07373420

07374000

07374525

07375050

07379960

Des Moines River at Keosauqua, IA

Sugar Creek at Milford, IL

Salt Creek at Western Springs, IL

Des Plaines River at Riverside, IL

Illinois River at Ottawa, IL

Sangamon River at Monticello, IL

La Moine River at Colmar, IL

Illinois River at Valley City, IL

Mississippi River Below Grafton, IL

Clarks Fork Yellowstone River near Edgar, MT

Bighorn River at Kane, WY

Yellowstone River at Forsyth, MT

Yellowstone River near Sidney, MT

Cherry Creek at Denver, CO

South Platte River at Denver, CO

Lonetree Creek near Greeley, CO

South Platte River near Kersey, CO

Shell Creek near Columbus, NE

Maple Creek near Nickerson, NE

Elkhorn River at Waterloo, NE

Platte River at Louisville, NE

Dousinbury Creek near Wall Street, MO

Missouri River at Hermann, MO

Mississippi River at Thebes, IL

Fletcher Creek at Memphis, TN

Little River Ditch No 1 near Morehouse, MO

Yocum Creek near Oak Grove, AR

Arkansas River at David D Terry Lock and Dam 

below Little Rock, AR

Bogue Phalia near Leland, MS

Yazoo River near Long Lake, MS

Tensas River at Tendal, LA

Mississippi River near St. Francisville, LA

Mississippi River at Baton Rouge, LA

Mississippi River at Belle Chasse, LA

Tchefuncte River near Covington, LA

Dawson Creek at Baton Rouge, LA

36,400

1,160

291

1,630

28,300

1,430

1,700

69,200

443,700

5,240

40,800

102,000

177,000

1,060

10,000

1,480

25,000

762

955

18,000

221,000

106

1,353,000

1,847,000

79

1,140

134

401,000

1,300

34,800

721

2,915,000

2,926,000

2,727,000

366

39

Agriculture

Agriculture

Urban

Urban

Mixed

Agriculture

Agriculture

Mixed

Agriculture

Mixed

Mixed

Mixed

Mixed

Urban

Urban

Agriculture

Mixed

Agriculture

Agriculture

Agriculture

Mixed

Mixed

Mixed

Mixed

Urban

Agriculture

Agriculture

Mixed

Agriculture

Mixed

Agriculture

Mixed

Mixed

Mixed

Mixed

Urban

2

1

1

3

2

2

5

5

1

1

3

5

2

4

2

5

5

7

1

6

6

1

2

1

6

3

6

4

6

2

2

2

1

2

6

7

3

4

5

1

3

1

5

4

8

8

8

1

9

3

10

10

7

5

1

1
22 An overview comparing results from two decades of monitoring for pesticides in the Nation’s streams and rivers

Table 1–2. Stream sites used in the first decade (1992–2001) and second decade (2002–11) summaries.—Continued

[km2, square kilometer; Cr, Creek; Ri, River; Irr Dist; Irrigation District; No., number; MA, Massachusetts; CT, Connecticut; NY, New York; 

NJ, New Jersey; PA, Pennsylvania; MD, Maryland; VA, Virginia; WV, West Virginia; DC, District of Columbia; NC, North Carolina; SC, South 

Carolina; GA, Georgia; FL, Florida; AL, Alabama; OH, Ohio; IN, Indiana; TN, Tennessee; KY, Kentucky; IL, Illinois; WI, Wisconsin; MI, Michigan; 

MN, Minnesota; ND, North Dakota; IA, Iowa; MT, Montana; WY, Wyoming; CO, Colorado; NE, Nebraska; MO, Missouri; AR, Arkansas; 

MS, Mississippi; LA, Louisiana; TX, Texas; AZ, Arizona; VT, Vermont; NV, Nevada; CA, California; WA, Washington; ID, Idaho; OR, Oregon]

Site number Site name Watershed area 

(km2

) Land use

Number of years

1992– 2002–11 2001

07381440

07381495

07381590

07381600

08010000

08012150

08012470

08049240

08051500

08057200

08057410

08064100

08116650

08178800

08180640

08181800

08364000

09153290

09481740

09514000

09517000

10102200

10168000

10171000

10350500

11060400

11074000

11075610

11261100

11262900

11273500

11274538

11274560

11274570

11303500

11390890

Bayou Grosse Tete at Rosedale, LA

Atchafalaya River at Melville, LA

Wax Lake Outlet at Calumet, LA

Lower Atchafalaya River at Morgan City, LA

Bayou Des Cannes near Eunice, LA

Mermentau River at Mermentau, LA

Bayou Lacassine near Hayes, LA

Rush Creek at Arlington, TX

Clear Creek near Sanger, TX

White Rock Creek at Dallas, TX

Trinity River below Dallas, TX

Chambers Creek near Rice, TX

Brazos River near Rosharon, TX

Salado Creek at San Antonio, TX

Medina River at La Coste, TX

San Antonio River near Elmendorf, TX

Rio Grande at El Paso, TX

Reed Wash near Mack, CO

Santa Cruz River at Tubac, AZ

Buckeye Canal near Avondale, AZ

Hassayampa River near Arlington, AZ

Cub River near Richmond, UT

Little Cottonwood Creek at Salt Lake City, UT

Jordan River at Salt Lake City, UT

Truckee River at Clark, NV

Warm Creek near San Bernardino, CA

Santa Ana River below Prado Dam, CA

Santa Ana River near Anaheim, CA

Salt Slough near Stevinson, CA

Mud Slough near Gustine, CA

Merced River near Newman, CA

Orestimba Creek near Crows Landing, CA

Turlock Irr Dist Lateral No. 5 near Patterson, CA

San Joaquin River near Patterson, CA

San Joaquin River near Vernalis, CA

Colusa Basin Drain near Knights Landing, CA

305

241,700

5,600

245,100

369

3,580

767

74

763

173

16,200

2,140

117,400

506

2,100

4,530

77,600

36

3,120

117,000

3,970

577

117

9,100

4,310

31

3,730

3,870

1,270

1,270

3,620

28

218

9,800

19,200

4,260

Agriculture

Mixed

Mixed

Mixed

Mixed

Agriculture

Agriculture

Urban

Mixed

Urban

Mixed

Mixed

Mixed

Urban

Mixed

Urban

Mixed

Mixed

Urban

Mixed

Mixed

Agriculture

Urban

Mixed

Mixed

Urban

Urban

Urban

Agriculture

Agriculture

Agriculture

Agriculture

Mixed

Mixed

Mixed

Agriculture

1

6

1

2

3

1

2

5

1

1

1

2

5

1

2

1

2

2

3

4

2

2

2

1

6

5

1

1

8

1

10

5

5

2

1

5

7

2

2

2

9

1

1

1

2

5

3

3

7
Appendix 23

Table 1–2. Stream sites used in the first decade (1992–2001) and second decade (2002–11) summaries.—Continued

[km2, square kilometer; Cr, Creek; Ri, River; Irr Dist; Irrigation District; No., number; MA, Massachusetts; CT, Connecticut; NY, New York; 

NJ, New Jersey; PA, Pennsylvania; MD, Maryland; VA, Virginia; WV, West Virginia; DC, District of Columbia; NC, North Carolina; SC, South 

Carolina; GA, Georgia; FL, Florida; AL, Alabama; OH, Ohio; IN, Indiana; TN, Tennessee; KY, Kentucky; IL, Illinois; WI, Wisconsin; MI, Michigan; 

MN, Minnesota; ND, North Dakota; IA, Iowa; MT, Montana; WY, Wyoming; CO, Colorado; NE, Nebraska; MO, Missouri; AR, Arkansas; 

MS, Mississippi; LA, Louisiana; TX, Texas; AZ, Arizona; VT, Vermont; NV, Nevada; CA, California; WA, Washington; ID, Idaho; OR, Oregon]

Site number Site name Watershed area 

(km2

) Land use

Number of years

1992– 2002–11 2001

11447360

11447650

12113390

12128000

12212100

12424500

12464770

12471400

12472380

12473740

12500420

12505450

12510500

13055000

13092747

13154500

13351000

14201300

14202000

14206950

14211720

040863075

040869415

073814675

094196783

0242354750

0357479650

252414080333200

322023090544500

393944084120700

394340085524601

Arcade Creek near Del Paso Heights, CA

Sacramento River at Freeport, CA

Duwamish River at Tukwila, WA

Thornton Creek near Seattle, WA

Fishtrap Creek at Lynden, WA

Spokane River near Spokane, WA

Crab Creek near Ritzville, WA

Lind Coulee Wasteway near Warden, WA

Crab Creek Lateral near Othello, WA

El 68 D Wasteway near Othello, WA

Moxee Drain near Union Gap, WA

Granger Drain at Granger, WA

Yakima River at Kiona, WA

Teton River near St Anthony, ID

Rock Creek at Twin Falls, ID

Snake River at King Hill, ID

Palouse River at Hooper, WA

Zollner Creek near Mt. Angel, OR

Pudding River at Aurora, OR

Fanno Creek at Durham, OR

Willamette River at Portland, OR

North Branch Milwaukee River near Random 

Lake, WI

Lincoln Creek at Milwaukee, WI

Bayou Boeuf at Amelia, LA

Las Vegas Wash near Las Vegas, NV

Cahaba Valley Creek at Pelham, AL

Hester Creek near Plevna, AL

C-111 Canal near Homestead, FL

Mississippi River above Vicksburg, MS

Holes Creek at Kettering, OH

Sugar Creek at New Palestine, IN

82

61,700

1,190

29

99

13,000

1,190

1,820

146

377

353

160

14,500

2,290

623

92,900

6,380

39

1,260

81

28,900

130

26

3,170

2,650

66

76

132

2,929,500

52

246

Urban

Mixed

Urban

Urban

Mixed

Urban

Agriculture

Agriculture

Agriculture

Agriculture

Mixed

Agriculture

Mixed

Mixed

Agriculture

Mixed

Agriculture

Agriculture

Agriculture

Urban

Mixed

Agriculture

Urban

Mixed

Urban

Urban

Agriculture

Mixed

Mixed

Urban

Agriculture

1

5

5

2

1

1

3

1

1

1

1

1

1

5

5

8

1

6

1

1

5

2

2

1

2

7

2

10

3

1

4

3

1

2

6

2

3

5

9

5

5

3

1

1

2

5


Stone and others—An Overview Comparing Results from Two Decades of Monitoring for Pesticides in the Nation’s Streams and Rivers—Scientific Investigations Report 2014–5154

ISSN 2328-0328 (online)

http://dx.doi.org/10.3133/sir20145154