In cooperation with the

U.S. Environmental Protection Agency

Pesticides in Selected Water-Supply Reservoirs and 

Finished Drinking Water, 1999-2000: Summary of 

Results from a Pilot Monitoring Program

Open-File Report 01-456

U.S. Department of the Interior

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

U.S. Geological Survey

Pesticides in Selected Water-Supply Reservoirs and 

Finished Drinking Water, 1999-2000: Summary of 

Results from a Pilot Monitoring Program

by 

Joel D. Blomquist, Janet M. Denis

(U.S. Geological Survey)

and

James L. Cowles, James A. Hetrick, R. David Jones, and Norman B. Birchfield

(U.S. Environmental Protection Agency)

Open-File Report 01-456

 

 

In cooperation with the

U.S. Environmental Protection Agency 

Baltimore, Maryland

2001
U.S. DEPARTMENT OF THE INTERIOR

GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

The use of trade, product, or firm names in this report is for descriptive purposes only and 

does not imply endorsement by the U.S. Government.

For additional information contact:

District Chief

U.S. Geological Survey

8987 Yellow Brick Road

Baltimore, MD 21237

iii

Contents

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

Introduction................................................................................................................................................................................................2

Purpose and scope................................................................................................................................................................................2

Acknowledgments................................................................................................................................................................................3

Pilot monitoring program design............................................................................................................................................................3

General sampling approach................................................................................................................................................................3

Description of sampling sites.............................................................................................................................................................5

Sampling frequency...........................................................................................................................................................................14

Methods of sample collection, analysis, and quality assurance.......................................................................................................17

Field methods......................................................................................................................................................................................17

Analytical methods............................................................................................................................................................................17

Summary of results from the pilot monitoring program...................................................................................................................19

Gas chromatography / mass spectrometry (method 2001)..........................................................................................................20

Gas chromatography / mass spectrometry (provisional method 9002).....................................................................................22

High-performance liquid chromatography / mass spectrometry (provisional method 9060) ...............................................24

Summary ...................................................................................................................................................................................................26

Selected references..................................................................................................................................................................................28

Supplemental tables ................................................................................................................................................................................30

Figures 

1. Diagram showing general on-site sampling locations for reservoirs and community water systems..............................4

2. Map showing locations of 12 reservoirs and community water systems included in the pilot monitoring program. ...5

3. Graph showing sample-collection dates at the 12 pilot monitoring program sites in 1999 and 2000. ..........................16

Tables

1. Characteristics of reservoirs and community water systems included in pilot monitoring program...............................6

2. Land-use characteristics in watersheds upstream from the pilot monitoring sites..............................................................7

3. Major row-crop groups grown in counties intersecting pilot monitoring program watersheds........................................8

4. Order of water-treatment stages and chemicals used during treatment for 12 community water systems included in 

the pilot monitoring program........................................................................................................................................9

5. Process parameters of water from 12 community water systems participating in the pilot monitoring program........13

6. Summary of atrazine-concentration distributions based on 10,000 trials of selected fixed-frequency sampling 

strategies on daily concentration data from Perry Lake, Kansas, 1993-94.........................................................15

7. Summary statistics of 1-week and 2-week sampling-interval test scenarios using PRZMS-EXAMS model-predicted 

atrazine and bromoxynil concentration for a small midwestern reservoir based on 1976 precipitation 

records and equivalent application rates...................................................................................................................15
iv

8-10. Summary of analysis of pesticides in water samples from water-supply intakes and finished water- supply taps 

using:

8. Gas chromatography / mass spectrometry—U.S. Geological Survey National Water Quality 

Laboratory method 2001 .............................................................................................................................21

9. Gas chromatography / mass spectrometry—U.S. Geological Survey National Water Quality 

Laboratory provisional method 9002. .......................................................................................................23

10. High-performance liquid chromatography / mass spectrometry—U.S. Geological Survey National 

Water Quality Laboratory provisional method 9060 ..............................................................................25

11-42. Statistical summary of pesticides and degradates detected in water samples from the:

11. Water-supply intake monitoring site at Canyon Reservoir near Elsinore, California .......................................31

12. Finished-water monitoring site at Elsinore Valley Municipal Water District, Ca lifornia ................................32

13. Water-supply intake monitoring site at Eagle Creek Reservoir, Indiana ............................................................33

14. Reservoir-outflow monitoring site at Eagle Creek Reservoir, Indiana................................................................34

15. Finished-water monitoring site at Indianapolis Water Company, Indiana .........................................................35

16. Water-supply intake monitoring site at Lake Bruin, Louisiana............................................................................36

17. Reservoir-outflow monitoring site at Lake Bruin, Louisiana................................................................................37

18. Finis hed-water monitoring site at Tensas Water Distribution Association, Inc., Louisiana............................38

19. Water-supply intake monitoring site at Higginsville Reservoir, Missouri .........................................................39

20. Reservoir-outflow monitoring site at Higginsville Reservoir, Missouri.............................................................41

21. Finished-water monitoring site at City of Higginsville Municipal Utilities, Missouri.....................................42

22. Water-supply intake monitoring site at Tar River Reservoir, North Carolina ...................................................43

23. Reservoir-outflow monitoring site at Tar River Reservoir, North Carolina.......................................................44

24. Finished-water monitoring site at Tar River Water Treatment Plant, North Carolina......................................45

25. Water-supply intake monitoring site at LeRoy Reservoir, New York.................................................................46

26. Finished-water monitoring site at Village of LeRoy Water Department, New York .......................................47

27. Water-supply intake monitoring site at East Fork Lake, Ohio ..............................................................................48

28. Reservoir-outflow monitoring site at East Fork Lake, Ohio .................................................................................49

29. Finished-water monitoring site at Clermont Water Authority, Ohio ...................................................................50

30. Water-supply intake monitoring site at Lake Arcadia, Oklahoma .......................................................................51

31. Reservoir-outflow monitoring site at Lake Arcadia, Oklahoma ...........................................................................53

32. Finished-water monitoring site at Edmonds Water Supply, Oklahoma ..............................................................54

33. Water-supply intake monitoring site at Blue Marsh Reservoir, Tulpehocken Creek, Pennsylvania..............55

34. Finished-water monitoring site at Western Berks Water Authority, Pennsylvania...........................................57

35. Water-supply intake monitoring site at South Pacolet Reservoir, South Carolina............................................58

36. Reservoir-outflow monitoring site at South Pacolet Reservoir, South Carolina ...............................................59

37. Finished-water monitoring site at Spartanburg Waterworks, South Carolina....................................................60

38. Water-supply intake monitoring site at Lake Mitchell, South Dakota ................................................................61

39. Reservoir-outflow monitoring site at Lake Mitchell, South Dakota....................................................................62

40. Finished-water monitoring site at Mitchell Water Department, South Dakota..................................................63

41. Water-supply intake monitoring site at Lake Waxahachie, Texas......................................................................64

42. Finished-water monitoring site at City of Waxahachie Water Treatment Plant, Texas ...................................65
 v 

Conversion Factors

Multiply By To obtain

mile (mi) 1.609 kilometer (km)

square mile (mi2) 2.590 square kilometer (km2)

acre 4,047 square kilometer (km2)

Acre-foot (acre-ft) 1,233 cubic meter (m3

)

million gallons per day (Mgal/d) 3,785 cubic meters per day(m3

/d)

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

per liter (μg/L).
vi Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:
 Summary of Results from a Pilot Monitoring Program 1

Pesticides in Selected Water-Supply Reservoirs and Finished 

Drinking Water, 1999-2000: Summary of Results from a Pilot 

Monitoring Program

by Joel D. Blomquist, Janet M. Denis, James L. Cowles, James A. Hetrick, 

R. David Jones, and Norman B. Birchfield

Abstract

In 1999, a pilot monitoring program was 

initiated by the U.S. Geological Survey and the 

U.S. Environmental Protection Agency to 

provide information on pesticide concentrations 

in drinking water and to assist in the 

implementation of the Food Quality Protection 

Act of 1996. Drinking-water utilities that 

withdrew from reservoirs were sampled because 

reservoirs are vulnerable to pesticide 

contamination, integrate pesticide loading from 

their watersheds, and show smaller temporal 

variations than streams. Sampling frequencies 

were designed to measure long-term mean and 

short-term peak concentrations of pesticides in 

drinking water. Samples were collected quarterly 

throughout the year and at weekly or bi-weekly 

intervals following the primary pesticideapplication periods. Water samples were 

collected from the raw-water intake and from the 

finished drinking-water tap prior to entering the 

distribution system. At some sites, samples were 

also collected at the reservoir outflow.

Twelve water-supply reservoirs were 

sampled, ranging in size from 120 to 92,600 

acre-feet normal capacity, with contributing 

watersheds ranging from 3.3 to 784 square 

miles. The sites are in California, Indiana, Ohio, 

Oklahoma, Louisiana, Missouri, South Carolina, 

South Dakota, New York, North Carolina, 

Pennsylvania, and Texas. In 1999, drought 

conditions affected parts of the Eastern United 

States and California; therefore sampling was 

extended through 2000 at nine sites.

Analyses for pesticides in water samples were 

performed at the U.S. Geological Survey 

National Water Quality Laboratory in Denver, 

Colorado, using three analytical methods. 

Overall, these methods included 178 different 

pesticides and degradation products. Of these, 

108 compounds were detected in at least one 

sample from a raw-water intake or finishedwater tap. Many of these compounds, however, 

were detected in fewer than 5 percent of the 

samples and at concentrations very near the 

method reporting level. The observed detection 

frequencies for raw water are similar to those 

reported for 58 stream sites sampled from 1992-

95 as part of the U. S. Geological Survey 

National Water-Quality Assessment Program. 

None of the pesticides were detected in finished 

water at a concentration greater than a National 

drinking-water criterion, such as a Maximum 

Contaminant Level or Health Advisory Level.

Widely used herbicides including atrazine, 

simazine, metolachlor, prometon, cyanazine, 

2,4-D, tebuthiuron, and acetochlor were the most 

frequently detected pesticides in both intake and 

finished-water samples. Detection frequencies 

for these compounds ranged from 35.6 to 96.3 

percent in raw-water samples and from 18.7 to 

95.6 percent in finished-water samples. Four 

triazine-herbicide degradation products also 

were detected in more than 60 percent of all 

samples.
2 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

Diazinon and chlorpyrifos were the two most 

frequently detected insecticides in raw-water 

samples, with 35.3 percent and 5.3 percent 

detection frequencies, respectively. Neither of 

these insecticides were detected in finished 

water. Malaoxon, the principal oxidative 

transformation product of malathion, was 

detected in 11 finished-water samples and none 

of the raw-water samples. In three of the samples 

where malaoxon was detected in finished water, 

the corresponding intake sample showed 

measurable concentrations of malathion. 

Diazoxon, the principal oxidative transformation 

product of diazinon, was not included as an 

analyte on any of the three methods used in this 

study.

Introduction

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

U.S. Environmental Protection Agency (USEPA) initiated 

a pilot monitoring program to provide data on pesticide 

concentrations in drinking water. USEPA’s Office of 

Pesticide Programs (OPP) has responsibility under the 

Food Quality Protection Act (FQPA) of 1996 to assess 

aggregate risk from exposure to pesticides in drinking 

water based on available data. Prior to implementation of 

this pilot program, however, there were few available data 

sets that contained information on pesticide concentrations 

in finished drinking water on a national scale, as most 

available data sets generally cover only selected 

compounds or local areas. USEPA’s Office of Ground 

Water and Drinking Water (OGWDW) is responsible for 

regulating contaminant levels in public drinking-water 

supplies under the Clean Water Act of 1999. With this 

responsibility, OGWDW gathers information on the 

occurrence of contaminants, including pesticides, in 

drinking-water supplies. The pilot program described in 

this report was implemented to begin to fill this important 

data gap, and to provide more information about 

appropriate methods for national monitoring of pesticides 

in drinking water.

Since 1986, the USGS National Water-Quality 

Assessment (NAWQA) Program has collected thousands 

of streamwater and ground-water samples for pesticide 

analysis. The USGS National Water Quality Laboratory 

(NWQL) has developed techniques for analysis of large 

groups of pesticide compounds with low reporting limits. 

The NAWQA data sets provide the only nationally 

consistent pesticide concentration data for a large suite of 

compounds. OPP currently uses the NAWQA data in their 

drinking-water and aquatic-exposure assessments; 

however, these data are not collected from public water 

supplies and, therefore, may not reflect exposure to 

pesticides in drinking water.

The pilot monitoring program described in this report 

was designed to provide information on the occurrence of 

pesticides in drinking water in a variety of geographic 

settings using sampling and analytical techniques that 

have been tested and used by the USGS NAWQA 

Program. Sampling focused on drinking-water utilities that 

withdraw from reservoirs because reservoirs are 

considered to be highly vulnerable to pesticide 

contamination, integrate pesticide loading from their 

watersheds, and show smaller temporal variations than 

streams. Although collecting data on the occurrence of 

pesticides in drinking water is not specifically within the 

objectives and current design of the NAWQA program, 

the NAWQA program has the infrastructure for collecting 

samples from raw and treated drinking water to meet 

USEPA’s data requirement. The sampling approach 

implemented in 1999 was designed by a team of scientists 

from USEPA and USGS. Because of drought conditions in 

the Eastern United States and California in 1999, the pilot 

program was extended though 2000 at nine of the twelve 

monitoring sites. 

Purpose and Scope

The purpose of this report is to present and summarize 

the data collected during the pilot monitoring program 

conducted in 1999 and 2000. The report also describes the 

design of the monitoring program and the broad array of 

goals and objectives for this study. The pesticide 

concentration data from the program are summarized for 

the entire data set, and for individual monitoring sites.

The pilot monitoring program was conducted as a datacollection program to provide data for subsequent analysis 

by scientists within the USGS, the USEPA OPP and 

OGWDW, and other interested parties. This report 

summarizes only the raw data from this study; however, 

additional analysis is required to fully meet the overall 

goals of the study.
Summary of Results from a Pilot Monitoring Program 3

Acknowledgments

The United States Environmental Protection Agency 

(USEPA) Office of Pesticide Programs (OPP), the USGS 

National Water-Quality Assessment Program (NAWQA), 

and the USEPA Office of Ground Water and Drinking 

Water (OGWDW) provided financial support for this pilot 

monitoring program. Their support and collaboration 

during the planning and execution of this pilot program 

are greatly appreciated. 

Special thanks are extended to the management and 

staff of each of the participating community water systems 

who granted access to USGS staff for sample collection, 

and provided assistance to the study team. Their 

willingness to participate in this voluntary effort in the 

interest of developing a better understanding of their water 

system is greatly appreciated.

The contribution of many dedicated USGS personnel 

throughout the country that assisted with site selection, 

program design, sample collection, data management, and 

analysis activities is also acknowledged. The authors also 

wish to thank the staff of the USGS NWQL for 

performing the laboratory analyses and for permitting 

analysis by two new laboratory methods concurrent with 

final method development and testing.

Pilot Monitoring Program Design

The pilot monitoring program was designed as a first 

step towards a long-term goal of characterizing human 

exposure to pesticide residues in drinking water derived 

from surface-water sources. A team of scientists from 

USGS and OPP, with input from other USEPA and USGS 

experts, developed the sampling approach to collect data 

on the occurrence of pesticides in drinking-water sources 

that are linked to pesticide concentrations observed in 

finished drinking water. The design enables the resultant 

data set to be used to support the following data-analysis 

objectives: 

1) Ecological risk assessments for reservoir systems;

2) Analysis of the relation between sampling 

frequency and the precision of estimates of peak 

concentrations of pesticides in community water 

systems;

3) Analysis of the concentration of pesticides in 

finished drinking water in relation to sourcewater concentrations and overall water-treatment 

processes;

4) Analysis of the relation of pesticide 

concentrations in reservoirs to watershed and 

reservoir characteristics; and

5) Evaluation and development of watershed and 

reservoir models.

This study focused on small drinking-water supply 

reservoirs in areas with high pesticide use, and will 

provide information that can be linked to the NAWQA 

database on pesticide occurrence in surface water. The 

analytical approach used the unique capability of the 

NWQL to analyze water samples for a broad suite of 

pesticide compounds with low levels of detection. The 

results of this pilot program may be used to increase the 

technical level and cost-effectiveness of future pesticidemonitoring programs.

General Sampling Approach

A comprehensive sampling approach was required for 

the pilot program due to the number of intended uses for 

the monitoring data. The primary sampling approach 

specified water-sample collection of raw water from a 

Community Water System (CWS) intake and of the 

finished water at the entry point to the distribution system. 

These two samples, collected sequentially, provide the 

basis for comparing pesticide concentrations in pre- and 

post-treatment drinking water. CWSs supplied by 

reservoirs were chosen as the focus of this pilot effort 

because reservoirs integrate pesticide loadings over time. 

Pesticide concentrations in reservoirs show smaller 

variations over short periods of time than free-flowing 

streams. Although residence time within a water-treatment 

facility is variable and can extend for many hours, the 

small temporal variability of pesticide concentrations in 

reservoirs improves the link between raw- and finishedwater samples collected at nearly the same time. 

Samples were collected at the outflow of many of the 

reservoirs because conditions at an intake may differ 

substantially from average reservoir conditions. This was 

done so comparisons could be made between the pesticide 

concentrations observed at an intake with a more 

representative sample reflecting water leaving the 

reservoir. Although these data are not necessary for 

assessing pesticide exposure, they provide the primary 

basis for ecological risk assessments and for relating 

pesticide concentrations to watershed and reservoir 

characteristics. 

A schematic diagram for the general sampling 

approach at a reservoir and a CWS is shown in figure 1. 

The finished-water sample was collected from a water tap, 

representative of the treated water entering the distribution 

system (labeled as sampling location “A”). In nearly all 

cases, this was the tap used by the utility for routine 

monitoring. In instances where a water supplier has 

multiple treatment facilities, it was determined that one 

facility and one tap would be selected at random and 

sampled throughout the duration of the program. In 

practice, each facility included in the pilot program had 

only one such tap. The finished-water sample provides the 

best practical measure of pesticide concentrations that the 
4 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

supplied population is exposed to in drinking water. The 

lag time between final treatment and delivery to a 

drinking-water tap may be long and vary considerably 

among distribution systems. Because this can allow 

additional time for degradation and transformation of 

pesticides, the measured levels at the finished-water 

sampling location may be somewhat different than the 

actual concentrations to which consumers are exposed.

Raw-water samples were collected from a tap on the 

intake supply line (shown in figure 1 as sampling location 

“B”). When no intake tap existed, raw-water samples 

were collected from the reservoir at the intake in use at the 

time of sampling. Pesticide analyses of raw-water samples 

show the pesticide occurrence in source water prior to the 

effects of treatment. Raw-water samples were collected in 

conjunction with finished-water samples to determine the 

levels of influent concentrations at these CWSs, to permit 

a general evaluation of the efficiency of water-treatment 

processes in removing residues, and to identify 

transformations that may result from treatment. Due to 

variation in retention time during the treatment process, 

the raw and finished water samples are not precisely 

paired. The goal of pairing the raw and finished samples 

in this study is to provide a general understanding of the 

relative impact of treatment processes on pesticide 

removal and transformation, and to identify areas that may 

require additional study.

A sample from the reservoir outflow (shown as 

sampling site “C” in figure 1) was collected at selected 

sites during each routine sampling trip, and was intended 

to approximate average reservoir concentrations at the 

time of sampling. This measure was designed to provide a 

consistent link between observed concentrations and 

reservoir and watershed characteristics. Studies have 

shown that water-quality and pesticide concentrations can 

vary considerably within any reservoir system (Elkhart 

and others, 1999). Vertical stratification and seasonal 

mixing in deeper reservoirs have been shown to be sources 

of variability, and horizontal stratification in large 

dendritic reservoirs has been shown to be another source 

of variability. It is generally recognized that the intake 

location for many water supplies may not be an ideal 

indicator of average reservoir conditions. The reservoirs 

included in this study were generally small, however, and 

variations in concentrations within the reservoir are 

expected to be slight. Outflow samples were chosen as the 

primary measure of reservoir concentrations because they 

integrate pesticide concentrations within the reservoir 

system and provide data on pesticide flux through 

reservoirs and their watersheds. Several of the pilot 

monitoring sites had drinking-water intakes located at or 

very near the reservoir outflow. In these cases, only the 

intake was sampled and the intake was assumed to be 

representative of outflow concentrations. In addition, 

several of the reservoirs experienced prolonged periods 

without releases. Outflow samples were not collected 

during these periods.

Figure 1. General on-site sampling locations for 

reservoirs and community water 

systems. 
Summary of Results from a Pilot Monitoring Program 5

Figure 2. Locations of 12 reservoirs and community water systems included in the pilot monitoring 

program.

Description of Sampling Sites

Each sampling site included in this study consisted of a 

reservoir and Community Water System. This study 

focuses on small drinking-water supply reservoirs in areas 

with high pesticide use in order to test the sampling 

approach in areas where pesticides are probably present. 

Sampling sites were selected from a variety of geographic 

regions and included different cropping patterns in order 

to assess different pesticide-use patterns. Because this 

program was implemented within the NAWQA design 

structure, strong consideration was given to candidate sites 

that were within existing NAWQA Study Units.

A candidate list of sites was developed from an 

analysis of CWS sites from the Safe Drinking Water 

Information System /Federal Version (SDWIS/FED) 

(USEPA, 1998), and from recommendations from local 

NAWQA Study Units and USGS District offices. Twelve 

water-supply reservoirs, considered to be vulnerable to 

pesticide contamination, were selected from the list of 

candidates (fig. 2; table 1). The 12 sites are located in 

California (CA), Indiana (IN), Ohio (OH), Oklahoma 

(OK), Louisiana (LA), Missouri (MO), South Carolina 

(SC), South Dakota (SD), New York (NY), North 

Carolina (NC), Pennsylvania (PA), and Texas (TX). The 

primary factors considered in assessing vulnerability were 

reservoir size, and estimates of pesticide use and runoff 

potential; however, no direct measure of the last two 

factors was readily available for contributing watersheds 

during the design process. Small reservoirs in high 

pesticide-use areas were anticipated to have high rates of 

pesticide occurrence. Thus, the ideal candidate reservoirs 

were mostly small reservoirs located in high pesticide-use 

areas, with a high runoff potential. Three sources of data 

were used together as surrogates for watershed pesticideuse rates, including: county row-crop production, county 

estimates of pesticide use, and mapped land-cover data. 

Site selection was conducted by reviewing maps and other 

data for each potential CWS and reservoir to determine: 

(1) whether the contributing land use was largely 

agricultural or developed, (2) the primary cropping 

patterns, and (3) relative pesticide use rates for a variety of 

compounds. Many candidate reservoirs were eliminated 
6 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

Table 1. Characteristics of reservoirs and community water systems included in pilot monitoring 

program

[See page 16 for a description of sampling frequencies]

State Reservoir name Community water system Location Population 

served 1

(thousands)

Reservoir 

capacity 2

(acre-feet)

Watershed 

size

(square 

miles)

Sampling 

frequency

CA Canyon 

Reservoir

Elsinore Valley Municipal 

Water District

Lake Elsinore 81.1 11,867 758 Base

IN3 Eagle Creek 

Reservoir

Indianapolis Water Company Indianapolis 801 24,000 170 Enhanced

LA3 Lake Bruin Tensas Water Distribution 

Association, Inc.

St. Joseph 0.4 -- 21.4 Base

MO3 Higginsville 

Reservoir

City of Higginsville 

Municipal Utilities

Higginsville 4.7 1,661 4.9 High

NY3 LeRoy 

Reservoir

Village of LeRoy Water 

Department

LeRoy 6.3 196 3.3 Base

NC Tar River 

Reservoir

Tar River Water Treatment 

Plant

Rocky Mount 56411,200 784 Base

OH3 East Fork 

Lake

Clermont Water Authority Batavia 80592,600 218 Base

OK3 Lake Arcadia Edmonds Water Supply Arcadia 53 120 98.1 High

PA3 Blue Marsh 

Reservoir

Western Berks Water 

Authority

Reading 25 22,897 175 Base

SC3 South Pacolet 

Reservoir

Spartanburg Waterworks Chesnee 1.9 22,400 414 High

SD3 Lake Mitchell Mitchell Water Department Mitchell 13.8 8,960 579 Base

TX Lake 

Waxahachie

City of Waxahachie Water 

Treatment Plant

Waxahachie 23613,500 31.3 High

1 Data obtained from Marilee Horn, U.S. Geological Survey, written commun.,1999.

2 Data obtained from National Inventory of Dams, U.S. Army Corps of Engineers, 1996.

3 Sites sampled in 1999 and 2000.

4 Jay Van Hoose, Tar River Water Treatment Plant, oral commun., 2001.

5 Eric Heiser, Clermont Water Authority, written commun. 2001.

6 Leonard Leinfelder, City of Waxahachie, written commun., 2001.

from consideration because they are upstream from the 

principal agricultural lands. Other factors considered in the 

selection of sampling sites were spatial representation 

across the country, integration with ongoing monitoring 

efforts, and willing participation by the water-supply 

utility. Where possible, sites were selected on reservoirs 

located downstream from NAWQA fixed streammonitoring sites so that additional data could be collected 

to represent the flux of pesticides into reservoirs. Several 

of the sites selected have ongoing monitoring programs 

within the watershed or reservoir studies. As a final check, 

each site was evaluated in relation to National maps of 

county pesticide-use estimates (Thelin and Gianessi, 2000) 

to determine the watershed’s representation of regional 

pesticide-use patterns. The 12 sites selected were 

determined to be vulnerable to the pesticides used 

regionally, however, they are not necessarily the most 

vulnerable sites in any given region. 

During the site-selection process, the limitations of 

available National data sets for CWSs and watershed 

characteristics became evident. CWS latitude-longitude 

locations were frequently inaccurate or unavailable in 

SDWIS, and relatively little information was available that 

identified the type of water body used for water supply. 

Marilee Horn (U.S. Geological Survey, written commun., 

1998) supplied additional information on water-supply 

intakes serving populations greater than 10,000 people. 

The 12 sites selected for the pilot monitoring program 

include reservoirs ranging in size from 120 to 92,600 acreft normal capacity and watersheds ranging from 3.3 to 784 

mi2 (square miles). Watershed boundaries were delineated 

for each of the reservoirs sampled and land-use 
Summary of Results from a Pilot Monitoring Program 7

characteristics were summarized by intersecting the 

watershed boundary with the 30-m (meter) resolution 

National Land Cover Dataset (NLCD) (Vogelmann, 

2001). Ten of the 12 sites were selected to represent 

agricultural land use, with percent total agricultural land 

ranging from 24.4 to 94.9 percent (table 2). The CA and 

OK sites were selected because urban areas were deemed 

to be the predominant influence on water quality in their 

basins. The urban area in the CA watershed has grown 

considerably since the early 1990’s when the satellite 

imagery, which provides the basis for the NLCD, was 

collected and most of this growth has occurred near the 

reservoir.

The major crops grown in each of the watersheds 

generally reflect national cropping patterns. Table 3 

summarizes the major crop groups grown in each county 

intersecting the watersheds, and uses the classifications 

provided by Gilliom and Thelin (1997). These crop 

classifications are based on the 1992 Census of 

Agriculture (U.S. Department of Commerce, 1995) and 

may differ from crops actually grown during the study 

period. Many of the sites selected include areas with 

substantial amounts of corn, soybeans, wheat, and 

alfalfa—four of the most widely grown crops in the 

country. An effort was made to include sites that 

encompass regionally important crop groups including 

tobacco in NC and orchards in SC.

Table 2. Land-use characteristics in watersheds upstream from the pilot monitoring sites

Primary land-use groups

1 NLCD agriculture sub-groups,

in percent in percent

State Reservoir

Agriculture Urban Forest Pasture Row crop

Grasslands Small grains

CA Canyon 28.7 8.1 60.6 2.1 13.2 10.9 2.6

IN Eagle Creek 86.3 4.6 7.5 21.2 65.2

LA Bruin 64.9 0.1 9.8 2.5 58.0 4.5

MO Higginsville 81.7 0.6 12.0 43.7 37.0 0.6 0.4

NC Tar River 24.4 2.4 71.5 7.8 16.6

NY Leroy 81.8 0.1 13.7 51.8 30.0

SC South Pacolet 28.9 9.9 59.7 13.0 15.9

SD Mitchell 94.9 0.4 0.4 47.7 41.7 4.5 1.0

OH East Fork 72.3 2.3 23.4 28.7 43.5

OK Arcadia 34.5 39.5 22.2 9.8 2.2 21.5 1.0

PA Blue Marsh 67.0 2.5 28.8 49.2 17.8

TX Waxahachie 84.5 0.8 11.0 51.5 20.8 11.4 0.7

1

 Land-use data from National Land Cover Dataset (NLCD) (Vogelmann, 2001). 
8 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

Table 3. Major row-crop groups grown in counties intersecting pilot monitoring program watersheds

[>, greater than]

State Reservoir Classification of row crops on a county basis 1

County Crop and total harvested acreage on a county basis, in 

percent

CA Canyon Riverside Wheat and other grains > 20 Alfalfa > 20

IN Eagle Creek Hamilton, Boone, Marion, Hendricks Corn > 20 Soybeans > 20

LA Bruin Tensas Corn > 20 Soybeans > 20

MO Higginsville Lafayette Corn > 20 Soybeans > 20

NY Leroy Wyoming Corn > 50

Genesee Corn > 20 Wheat and other grains > 20 Vegetables > 10

NC Tar River Granville Tobacco > 50

Franklin, Polk, Vance Wheat and other grains > 20 Soybeans > 20

Nash Wheat and other grains > 20 Soybeans > 20 Cotton > 10

OH East Fork Clinton, Brown, Clermont Corn > 20 Soybeans > 20

SC South Pacolet Spartanburg, Greenville Corn>20 Soybeans>20 Wheat and other grains>20

SD Mitchell Sanborn Corn>20 Alfalfa>20 Soybeans >20

Jerauld Corn>20 Alfalfa>20 Wheat and other grains>20

Aurora, Davison Corn > 20 Soybeans > 20

OK Arcadia Oklahoma Wheat and other grains > 50

PA Blue Marsh Berks, Lebanon Corn > 50

TX Waxahachie Ellis Corn > 20 Wheat and other grains > 20

1

 from Gilliom and Thelin, 1997

The type of water treatment used at each of the 

selected CWSs was not used as a selection criterion. 

Interviews were conducted with staff from each of the 

CWSs to assemble a consistent coding of the treatment 

processes used at each site and a record of the chemicals 

used during each step of the treatment processes. A 

summary of this information is listed in table 4.

CWSs generally use one or a combination of four basic 

treatment types. These include disinfection, mixing, 

flocculation, and filtration. There are several methods of 

disinfecting raw water. These include chlorination, 

pasteurization, ultraviolet radiation, distillation, and 

ozonation. There are also many types of filtration units for 

treating raw water. These include micro-filtration, 

activated carbon filters, oxidizing filters, sand, and 

neutralizing filters. Each treatment step can occur at any 

point during the treatment process. The point at which it 

occurs may influence how well unwanted elements such as 

pesticides are eliminated from the raw water. At eight of 

the sites (MO, TX, OH, CA, IN, SC, NY, and PA), 

chlorine is added during pre-disinfection. In OK, ozone is 

added instead. At nine of the sites (MO, TX, OH, OK, IN, 

SC, NC, NY, and PA), flocculation is followed by 

filtration. In all of the states listed above, post-disinfection 

occurred before storage and included the addition of 

chlorine in some form. In seven of the states (OH, IN, SD, 

SC, NC, NY, and PA), fluoride was also added to bring 

the concentration to approximately 1 milligram per liter.

Two sites, CA and OH, underwent significant 

operational changes during the course of the pilot 

monitoring program. The CA site closed for major 

renovations just prior to the intended start of sampling. 

Sampling was delayed until July 1999, and continued until 

December 1999, when the facility closed. During the 

startup of a new facility, the treatment process may be 

somewhat unstable and results may differ from those 

collected while a facility is in normal operation. In March 

2000, the OH site shifted from a more conventional 

treatment system using powdered activated carbon to an 

advanced treatment system using granular activated 

carbon (GAC). 
Summary of Results from a Pilot Monitoring Program 9

Table 4. Order of water-treatment stages and chemicals used during treatment for 12 community water 

systems included in the pilot monitoring program 

[GAC, granular activat ed carbon; PAC powdered activated carbon]

California Site Indiana Site Louisiana Site

Elsinore Valley Municipal 

Water District

Indianapolis Water 

Company

Tensas Water Distribution 

Association, Inc.

Lake Elsinore, CA Indianapolis, IN St. Joseph, LA

Canyon Reservoir Eagle Creek Reservoir Lake Bruin

I I |

screen/pump screen/pump surface intake

I I I

Pre-Disinfection Pre-Disinfection Clarification

chlorine (optional) chlorine, carbon (optional) chlorine, aluminum, 

aluminum salts I and soda ash added

I Splitter and Rapid Mix I

Rapid Mix chlorine, aluminum Filtration

cationic polymer sulfate, polymers, I

I carbon (optional), lime Reservoir

Accelerator potassium permangate I

chlorine (optional) I Distribution

non-ionic polymer Mixing and Settling Basin

I I

Pre-Chlorination chlorine, polymer, and

sodium hydroxide PAC added

I I

Dual-Media Filters Filter Plant

I I

Post-Chlorination fluoride, ammonia 

I I

Clearwell Storage Finished Water Reservoir

I chlorine

Holding Pond I

| Distribution

Distribution
10 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

Table 4. Order of water-treament stages and chemicals used during treatment for 12 community water 

systems included in the pilot monitoring program--continued

Missouri Site New York Site North Carolina Site

City of Higginsville Municipal 

Utilities

Village of LeRoy Water 

Department

Tar River Water Treatment 

Plant

Higginsville, MO LeRoy, NY Rocky Mount, NC

Higginsville Reservoir Leroy Reservoir Tar River Reservoir

I I I

screen/pump screen/pump screen/pump

I I I

Pre-Disinfection Pre-Disinfection Pre-Disinfection

chlorine dioxide chlorine, PAC, aluminum salts and pre-caustic

I potassium permanganate I

Flash Mixer I Flash Mixer

polymer coagulant Flocculation polymer

I aluminum salts/polymers I

Flocculation/Sedimentation I Flocculation

lime Filtration I

I rapid sand and mixed media Sediment Basin

Flash Mixer I I

sodium silica fluoride Post-Disinfection Dual Media Filtration

I chlorine, flouride, chlorine

Flocculation/Sedimentation ortho-phosphate I

chlorine I Post-Disinfection

I Clearwell Storage post-caustic, fluoride, chlorine,

Dual Media Filtration I and phosphate

sand with GAC cap Storage I

I I Clearwell Storage

Post-Disinfection Distribution I

chlorine Distribution

I

Clearwell Storage

I

Distribution
Summary of Results from a Pilot Monitoring Program 11

Table 4. Order of water-treament stages and chemicals used during treatment for 12 community water 

systems included in the pilot monitoring program--continued

Ohio Site Oklahoma Site Pennsylvania Site

Clermont Water Authority Edmonds Water Supply Western Berks Water 

Authority

Batavia, OH Arcadia, OK Reading, PA

East Fork (Harsha Lake) Lake Arcadia Blue Marsh Reservoir

I I |

screen/pump screen/pump reservoir release

I I |

Pre-Disinfection Aeration Tulpehocken Creek

potassium permanganate, I I

chlorine dioxide Pre-Disinfection screen/pump

I ozone I

Rapid Mix I Pre-Disinfection

aluminum Flocculation / Clarification powdered activated carbon,

I polymers/lime potassium permanganate,

Flocculation I chlorine dioxide, and lime

pH adjustment, polymers Solids Contact / Clarification I

I carbon dioxide Flocculation / Clarification

Settling I aluminum sulfate

I Post-Disinfection I

Filtration ozone Filtration 

rapid sand with GAC I sand and anthracite

I Polyphosphate Polymer hydrofluosilicic acid

Post-Disinfection chlorine I

phosphate, flouride, chlorine I Ammonium Sulfate

and caustic soda Mixed Media Filters chloramines

I multimedia I

Clearwell Storage I Corrosion control

I Carbon Filter phosphate

Distribution granular activated carbon I

I Clearwell Storage

Post-Disinfection I

chlorine Reservoir

I I

Clearwell Storage Distribution

I

Distribution
12 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

Table 4. Order of water-treament stages and chemicals used during treatment for 12 community water 

systems included in the pilot monitoring program--continued

South Carolina Site South Dakota Site Texas Site

Spartanburg Waterworks Mitchell Water 

Department

City of Waxahachie Water 

Treatment Plant

Chesnee, SC Mitchell, SD Waxahachie, TX

South Pacolet Reservoir Lake Mitchell Lake Bardwell

(Lake Bowen) I (seasonal, used to recharge

I screen/pump Lake Waxahachie)

Municipal Reservoir #1 I |

I GAC Polymers screen/pump

screen/pump I |

I lime, aluminum sulfate Lake Waxahachie

Pre-Disinfection polymers added I

liquid alum, lime, carbon, I screen/pump

chlorine, and polymer chlorine dioxide, I

I and fluoride added Pre-Disinfection

Hydraulic Flocculation I potassium permanganate

aluminum salts, polymers ammonium poly phosphate (seasonal, taste and odor)

I added free chlorine

Dual Media High Rate I I

Filters Post-Disinfection Flocculation

I chlorine iron salts (ferric sulfate),

Post-Disinfection I |

fluoride, lime, phosphate, Distribution Disinfection

and chlorine chloramines

I | 

Clearwell Storage Filtration

I dual media sand / anthracite

Distribution |

Corrosion Control

caustic soda (pH control)

hydrofluorisilic acid

|

Clearwell Storage

I

Distribution
Summary of Results from a Pilot Monitoring Program 13

Table 5. Process parameters of water from 12 community water systems participating in the pilot 

monitoring program 

[Mgal/D, million gallons per day; mg/L, milligrams per liter; PAC, powdered activated carbon; TOC, total organic carbon; n.a., not available]

Water quality properties

State System name Average 

flowthrough 

time 

(hours)

Average 

flow-

 through 

rate 

(Mgal/d)

pH

(standard 

units)

Alkalinity 

(mg/L)

Hardness

(mg/L)

TOC 

(mg/L)

Seasonal 

modifications to 

treatment process

CA Elsinore Valley Municipal Water 

District

3.25 5 7.5 91 250 6 - 8 None

IN Indianapolis Water Company 8.75 n.a. 8.2 128 200 4 PAC added as needed 

following spring runoff

LA Tensas Water Distribution 

Association, Inc.

1 n.a. 7.5 25.8 78.3 n.a. None

MO City of Higginsville Municipal 

Utilities

26 1 7.9 - 9.2 63 - 120 90 - 145 4.7 treated with copper 

sulfate, May through 

September

NY Village of LeRoy Water 

Department

0.29 0.75 7.8 - 9.0 40 - 100 ~140 4.4 Increase potassium 

permanganate in 

summer/fall for taste 

and odor; PAC used as 

backup

NC Tar River Water Treatment Plant 4-5 10 7 12 12 4-6 None

OH Clermont Water Authority 23 5 7.7 95 126 5.2 0.25 mg/L potassium 

permanganate in winter 

- 3.0 or greater by late 

June

OK Edmonds Water Supply n.a. n.a. 7.9 - 8.8 137 150 5.8 Adjust ozone treatment 

if taste and odor is 

present

SC Spartanburg Waterworks 4 11 6.9 17 15 3.8 None

SD Mitchell Water Department 12 - 13 1.1 - 4.3 9.2 32 222 n.a. n.a.

PA Western Berks Water Authority 7 - 9 4 7.2 138 172 2 - 3 None

TX City of Waxahachie Water 

Treatment Plant

10 6 7.7 100 108 4 - 8 Potassium 

permanganate 

(as needed for taste 

and odor)

Process parameters including average flow-through 

time and average flow-through rate are reported for each 

of the 12 CWS plants in table 5. Water-quality parameters 

of raw water including normal ranges of pH, alkalinity, 

hardness, and total organic carbon are also included in 

table 5 as they were reported by the CWSs. Several CWSs 

reported seasonal modifications to the treatment process 

that are used to address an increase in flow, increased 

sedimentation, or other changes in physical and chemical 

characteristics of the source water.

The average flow-through time from collection of raw 

water to the completion of the finished water ranged from 

0.29 (NY) to 26 (MO) hours. Flow-through time was 

dependent on the total amount of water treated and the 

amount of time that the treated water remained in the 

clearwells. Seasonal modifications are regularly made at 

many of the sites investigated, and are mainly intended to 

control the taste and odor of the water.
14 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

Sampling Frequency 

One objective of this study was to provide estimates of 

annual-mean pesticide concentrations and high 

concentrations that occur for short periods of time, such as 

the annual 95th and 99th percentile concentration. An 

analysis of sampling-frequency requirements by the 

International Life Sciences Institute (ILSI, 1998) 

recommended a fixed-frequency sampling program of 100 

times per year to develop measures of chronic (long-term) 

and acute (short-term) exposure to pesticides in water 

from streams. This level of effort was impractical for this 

pilot program and was not necessary to meet the primary 

goal of comparing raw- and finished-water concentrations. 

However, the sampling frequency implemented was 

designed to characterize the occurrence of commonly 

occurring pesticides and to identify compounds that may 

occur for only a short period of time at concentrations 

greater than the laboratory detection level. 

The sampling frequency for this study was determined 

on the basis of data from Perry Lake, a large midwestern 

reservoir in Kansas. During 1993-94, Perry Lake was 

sampled on a daily basis and analyzed for triazine 

herbicides using Enzyme -Linked Immuno Assay kits—a 

low-cost method for performing large numbers of 

analyses— with supplemental samples sent to research 

labs for confirmation. The Perry Lake data were provided 

by Peter Van Meter (U.S. Geological Survey, written 

commun., 1998) and were analyzed using quarterly, 

monthly, bimonthly, 4-times monthly, and 10-times 

monthly sampling frequencies. In the analysis of Perry 

Lake data, 10,000 replicates of each sampling frequency 

were performed using a random starting date. Estimates of 

the mean and standard deviation showed that quarterly 

sampling was adequate to determine the annual-mean 

concentration of atrazine (table 6) (Charles Crawford, U.S. 

Geological Survey, written commun., 1998). Estimates of 

the maximum value and 95th percentile showed that, based 

on sufficiently small standard deviations, reasonable 

measures of the actual values could be determined using a 

monthly sampling frequency. Since this scenario is based 

on a large reservoir system and a comparatively long-lived 

analyte, a semi-weekly sampling frequency was selected 

as the base level for this program. 

A similar test scenario was performed on data from a 

pesticide runoff / reservoir model. OPP modeled daily 

atrazine and bromoxynil concentrations using the Pesticide 

Root Zone Model-Exposure Analysis Model System 

(PRZM-EXAMS) with the Shipman Reservoir scenario 

(U.S. Environmental Protection Agency, 1998). The 

watershed characteristics are representative of cotton 

grown on a Loring silt loam in Mississippi using 

conventional and no-till management. Application rates 

and timing were standardized to allow comparison 

between pesticides with different environmental fate and 

transport characteristics, since bromoxynil is 

significantly more reactive in the environment than 

atrazine. Table 7 presents a summary of these scenarios 

using 1976 precipitation data, showing the expected 

percentiles and mean value, in addition to the mean and 

standard deviation of 10,000 simulated sampling years for 

one-week and two-week sampling intervals. The standard 

deviation of the bromoxynil test is always a greater 

percentage of the expected value than for the atrazine 

test—indicating that more frequent sampling is necessary 

for reactive compounds in order to achieve the same level 

of precision. A 2-week sampling interval sufficiently 

characterized the 90th percentile bromoxynil concentration 

with a standard deviation of 20 percent of the peak model 

value. In contrast, weekly sampling significantly 

improved the estimate of the 90th percentile concentration 

with a standard deviation less than 5 percent of the peak 

model value.
Summary of Results from a Pilot Monitoring Program 15

Table 6. Summary of atrazine-concentration distributions based on 10,000 trials of selected fixedfrequency sampling strategies on daily concentration data from Perry Lake, Kansas, 1993-94

[Values, concentrations in micrograms per liter; n.d., not determined]

Percentile

50th 75th 90th95th 99th Maximum

Reported values, based on daily 

samples 

1.720 3.170 3.379 3.475 3.640 3.790

Quarterly sampling

 Value 1.684 3.040 n.d. n.d. n.d. 3.437 

 Standard deviation 0.209 0.172 n.d. n.d. n.d. 0.135

Monthly sampling

 Value 1.691 3.102 3.408 3.536 n.d. 3.566

 Standard deviation 0.105 0.149 0.064 0.094 n.d. 0.109

Bimonthly sampling

 Value 1.703 3.138 3.390 3.501 n.d. 3.636

 Standard deviation 0.052 0.102 0.039 0.054 n.d. 0.090

4-times monthly sampling

 Value 1.712 3.171 3.385 3.493 n.d. 3.715

 Standard deviation 0.026 0.018 0.021 0.030 n.d. 0.066

10-times monthly sampling

 Value 1.715 3.170 3.382 3.480 3.665 3.775

 Standard deviation 0.009 0.006 0.010 0.016 0.033 0.011

Table 7. Summary statistics of 1-week and 2-week sampling-interval test scenarios using PRZMSEXAMS1

 model-predicted atrazine and bromoxynil concentration for a small midwestern 

reservoir based on 1976 precipitation records and equivalent application rates

[Values, concentrations in micrograms per liter]

1-Week sampling 

interval

2-Week sampling 

interval

Expected 

Value

Mean Standard 

deviation

Mean Standard

deviation

Atrazine

Maximum value 4.710 4.586 0.091 4.387 0.204

99th percentile 4.590 4.586 0.091 4.387 0.204

95th percentile 4.040 4.060 0.066 4.043 0.072

90th percentile 3.700 3.699 0.070 3.749 0.070

Mean 1.483 1.483 0.022 1.515 0.037

Bromoxynil

Maximum value 2.090 1.504 0.386 1.428 0.504

99th percentile 1.460 1.504 0.386 1.428 0.504

95th percentile 0.460 0.496 0.063 0.461 0.128

90th percentile 0.134 0.122 0.031 0.125 0.027

Mean 0.066 0.066 0.015 0.083 0.026

 1 U.S. Environmental Protection Agency, 1998
16 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

Figure 3. Sample-collection dates at the 12 pilot monitoring program sites in 1999 and 2000.

Based on both the Perry Lake concentration data and 

PRZMS-EXAMS model results, the design team chose to 

implement three sampling frequencies (see table 1): 

-- Base sampling frequency-- included quarterly 

sampling, plus semi-weekly sampling for a 4-

month period following pesticide application, 

with samples collected from water intake, 

finished-water tap, and reservoir outflow (11 

samples per year). 

-- High-frequency sampling-- supplemented the 

base sampling frequency with intake-water 

samples collected weekly over the 6-month 

period with highest pesticide applications (26 

samples per year).

-- Enhanced sampling--supplemented the highfrequency sampling by collecting samples from 

the intake site every 3 days for about 1 month 

after spring corn herbicide application (37 

samples per year). 

Because pesticide concentrations are often serially 

correlated and concentrations vary most during the 

principal growing season, the weekly, semi-weekly, and 

enhanced sampling intervals were scheduled around the 

principal application season, based on local knowledge 

and analysis of historical data for these areas. Thus, the 

measurements from the pilot program are representative of 

compounds that are used and mobilized during the period 

sampled and are less representative of concentrations 

during the remainder of the year. The dates that samples 

were collected from each monitoring site are shown in 

figure 3. The actual sampling frequency may differ 

somewhat from the designed frequency because of sitespecific scheduling and associated logistical concerns. The 

enhanced sampling frequency was used at the IN site in 

1999. These data are intended to support an analysis of 

precision in sample statistics to further quantify the results 

of the pilot monitoring program and other similar data 

sets. In 2000, all sites were sampled at the base sampling 

frequency and no samples were collected from reservoir 

outflows.
Summary of Results from a Pilot Monitoring Program 17

Methods of Sample Collection, 

Analysis, and Quality Assurance

The field and data-collection methods used in this 

study followed or were adapted from standard USGS 

protocols, and provided a high-quality data set that is 

consistent with the NAWQA Program and other USGS 

trace-organic water-chemistry data-collection efforts. The 

sample-collection, sample -handling, and data-management 

protocols were outlined for all project participants in an 

approved quality-assurance project plan, which 

documented the standard operating procedures to be 

followed. The laboratory methods used in this study 

encompass standard USGS methods, which have been 

reviewed and approved by the USGS, and developmental 

methods that are considered provisional for samples 

analyzed during the study period.

Field Methods

All water samples were collected by USGS personnel 

using sample-collection protocols documented by the 

USGS and the NAWQA Program (Wilde and others, 

1998). Consistent site-visit and sample -documentation 

forms were completed at the time of sampling at each site. 

During each site visit, water samples were collected from 

the intake and finished-water spigot and where necessary, 

the spillway, for the analyses of dissolved pesticides. 

Finished-water samples were collected directly from a 

spigot and filtered. Raw-water samples were collected 

from the intake or outflow site using either the equalwidth-increment or grab method. All samples were filtered 

into a 1-L glass amber bottle. Samples were processed 

using methods described in Shelton (1994), however it 

was not necessary to use a cone splitter to process 

samples. Samples were shipped using overnight carriers in 

sealed coolers to the USGS NWQL for analysis. No 

preservatives or quenching agents, such as sodium 

thiosulfate to remove residual chlorine, were added to the 

water samples. In order to minimize the risk of crosscontamination, all sampling equipment was cleaned 

according to standard protocols that include a thorough 

cleaning with soapy tap water, followed by a distilledwater rinse, and a final rinse with laboratory-grade 

methanol. Quality-assurance measures were conducted in 

a manner consistent with the NAWQA stream-sampling 

quality-assurance plan (Mueller and others, 1997). All 

analytical data were computerized and returned to the 

offices responsible for sample collection, then compiled 

into a single project data set. 

Analytical Methods

Three different laboratory methods were selected for 

use during the pilot monitoring program— a USGS 

approved method and two developmental methods. The 

primary method, known as method 2001 (or schedule 

2001) uses C-18 solid-phase extraction and gas 

chromatography / mass spectrometry (GC/MS) to 

determine concentrations of 47 pesticides and pesticide 

degradates in water samples (Zaugg and others, 1995). 

The two developmental methods were included in this 

program in order to greatly expand the available 

information on the occurrence of a wide number of 

pesticides and pesticide degradates in surface water across 

the Nation, and to test for the occurrence of these 

compounds in drinking-water supplies. These methods 

were included with the knowledge that the methods were 

developmental and that their performance may be more 

variable than would be expected of methods that have 

been thoroughly tested and approved. The two 

developmental methods were approved by the USGS in 

2001—without any changes to the proceedures.

Method 2001 was first developed in the early 1990s as 

a means of isolating and quantifying a broad range of 

target compounds while achieving low-level method 

reporting limits (ranging from .001 to .018 parts per 

billion). The pesticides selected for inclusion in this 

method were based on national use rates and their 

chemical properties, which would permit isolation using 

the C-18 cartridge and analysis by GC/MS. Thus, this 

method encompasses many of the more widely used 

pesticides, including many triazine and acetanilide 

herbicides; selected carbamate compounds; and selected 

organophosphate insecticides. Two pesticide metabolites, 

deethylatrazine and 2,6 diethylanaline, are also included in 

this method. Method 2001 is the principal pesticide 

analysis used throughout the Nation by the NAWQA 

Program.

Standard performance of method 2001 for untreated 

water samples has been documented based on qualityassurance samples collected by the NAWQA Program 

from 1992-96 (Jeffrey Martin, 1999). That report provides 

spiked-sample recovery data for each analyte included in 

method 2001, and indicates laboratory performance across 

a range of time and sample matrices. Therefore, these 

results are more indicative of the performance of the 

method from monitoring data than performance estimates 

provided in the method documentation. Each sample 

analyzed during the pilot program was spiked with a 

standard aliquot of a surrogate matrix prior to extraction, 

which may be used to track the performance of the 

analysis for individual samples. These results are reported 

as a percent of the expected value. Surrogate-spike 

recoveries are included in the accompanying pilot 

monitoring program data sets. 
18 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

Some pesticide-concentration data from method 2001 

are reported as qualified estimates. These samples have an 

“E” in the parameter’s remark field. There are two cases 

where concentrations are reported as qualified estimates. 

The first case includes the permanently qualified 

compounds deethylatrazine, azinphos-methyl, carbaryl, 

carbofuran, and terbacil. During method development, 

deethylatrazine exhibited consistently low recoveries (9-

19 percent) but was retained in the method due to its 

national relevance. The other four compounds exhibited 

variable recoveries and thus are reported as qualified 

estimates. The second case includes qualitative detections 

of concentrations less than the statistically determined 

Method Reporting Level (MRL).

The first developmental method is provisional method 

9002 (also known as schedule 9002), which is an 

adaptation of the same C-18-solid-phase extraction and 

GC/MS technology used in method 2001. The method 

provides a quantitative analysis of 20 parent pesticides and 

21 pesticide degradates. Qualitative estimates are provided 

for 14 parent pesticides and 20 degradates that through 

testing, showed greater bias, higher variability, or shorter 

holding times than the other compounds. The details of 

this adaptation are described in Sandstrom and others 

(2001) and should be used as a guide in the interpretation 

of the results from this method. Selection of candidate 

parent compounds for testing under this method was based 

on national rankings of pesticide use, the existence of 

current NWQL methods for these compounds, and the 

chemical characteristics that make analysis by this method 

favorable. Only compounds without an existing method 

were tested. Inclusion of pesticide degradates was based 

on whether the parent compound was included in a current 

NWQL method and the availability of analytical 

standards.

Method 9002 was implemented for conditional 

analysis by the NAWQA Program in March 1999, when 

the pilot monitoring program started. The method was 

approved for routine analysis in 2001 and is now referred 

to as method 2002. Although the method is now approved, 

the data collected during this program must be considered 

provisional, as the analyses were performed prior to 

method approval. Thus, these data will not be included as 

part of the USGS’s publicly accessible National Water 

Information System (NWIS). These data are available to 

the public; however, they must be accompanied by the 

documentation of analytical methodology in accordance 

with USGS policy (U.S. Geological Survey Office of 

Water Quality Technical Memorandum No. 98.05, 1998). 

During the period of study, no changes were made to the 

method or instrument settings. Therefore, the data from 

method 9002 should be consistent throughout the study, 

with the possible exception of the first 2 months, when the 

instruments were brought on line (Mark Sandstrom, U.S. 

Geological Survey, oral commun., 1999).

The second developmental method, provisional 

method 9060, is a substantially new technique using solidphase extraction and high-performance liquid 

chromatography/mass spectrometry (HPLC/MS) for the 

instrumental analysis of extracts. This method is designed 

to determine low-level concentrations of 64 polar 

pesticides and pesticide degradates. The use of HPLC/MS 

for this method provides improved sensitivity and 

selectivity over a previous method that included many of 

the same compounds, particularly in the presence of 

dissolved organic matter. Complete documentation of 

method 9060, now known as method 2060, can be found 

in Furlong and others (2001).

Samples analyzed using method 9060 pose the same 

set of qualifications as described for method 9002. The 

data are to be considered provisional, and interpreted with 

the knowledge that variability in concentration detections 

and quantifications may be greater than expected in a 

production method. An additional qualification should be 

given to samples analyzed during 1999, the first year of 

study. During this period, while the method was still in the 

testing phase, the NWQL received an unusually large

number of requests for this method—an amount greater 

than their instrumental capacity. As a result, a significant 

backlog developed and many samples were stored in 

refrigerators before extraction well beyond recommended 

holding times, with some as long as 180 days. NWQL has 

additional holding-time studies underway that may 

identify the compounds most vulnerable to degradation. 

Sample-holding times are available for each of the 

samples collected during the pilot monitoring program. By 

December 1999, NWQL had resolved the backlog by 

adding additional instruments and analysts. The likely 

implications of extended holding times for the pilot 

monitoring program’s provisional method 9060 are as 

follows—first, it is likely that in 1999, some compounds 

in some samples may have degraded to less than the MRL 

prior to extraction and analysis. Second, it is likely that 

reported concentrations are lower than would have been 

determined through extraction and analysis within 

prescribed holding times. And finally, it is possible that 

transformations may have occurred that produced a 

detectable degradate or elevated the concentration of a 

degradation compound relative to the concentration at the 

time of sampling. Ongoing NWQL holding-time studies 

may indicate which compounds are more susceptible to 

degradation and transformation.
 Summary of Results from a Pilot Monitoring Program 19

Summary of Results from the Pilot 

Monitoring Program

Summary tables are presented for each of the 

laboratory methods performed during the pilot monitoring 

program. These tables provide a systematic view of the 

analytical results for samples from raw-water-supply 

intake and finished-water sampling locations and are 

ordered by detection frequency to aid the reader in 

identifying the most commonly detected compounds. 

Summary tables were not prepared for the reservoiroutflow sites because much of the information was 

redundant between raw-water samples at the intake and 

reservoir-outflow samples. In addition, not all sampling 

sites included a reservoir-outflow sampling point. A 

summary of analytical results for individual sampling sites 

is presented as supplemental information at the end of this 

report. 

Each summary table presents the MRL for all 

compounds analyzed, summarizes the detection frequency, 

and presents the upper bounds of detected concentrations 

as the maximum value and 95th percentile concentrations. 

Those compounds that were included in the analysis but 

were not detected in any sample are listed with their MRL 

following the table. The summary statistics presented in 

tables 8, 9, and 10 are an aggregation of all data collected 

in this study, so that although the percent detection 

frequencies, 95th percentile values and maximum 

concentrations reflect the data as a whole, they do not 

represent conditions at any one site. The summary 

statistics are also influenced more by samples from the 

frequently sampled sites than the other sites. No measure 

of central tendency, such as mean or median value, is 

presented for the entire data set because only 11 

compounds had detection frequencies greater than 50 

percent. Median concentrations are presented for 

individual sites where detection frequencies exceeded 50 

percent in the supplemental tables. The supplemental 

tables also present the higher-level concentrations as 90th

percentiles because many sites had an insufficient number 

of samples to calculate the 95th percentile. 

In 1999, drought conditions extended across the 

Eastern Unites States and California, thus the conditions 

measured at six sites in 1999 (CA, OH, NC, NY, PA, and 

SC) were not representative of average runoff patterns. 

Drought conditions ended in the Eastern States in 

September 1999, when Hurricane Floyd produced flood 

conditions at most of the eastern sites. LeRoy Reservoir in 

NY had pesticide concentration-data collected in 1998 

from another program (Phillips and others, 1999). In 1998 

the maximum observed concentration of metolachlor was 

greater than 2.0 μg/L (micrograms per liter); and in 1999, 

the maximum concentration was 0.17 μg/L. This indicates 

that concentrations and detection frequencies from 1999 

may have been strongly affected by the drought, and was a 

primary consideration in the decision to ext end sampling 

through 2000.
20 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

Gas Chromatography / Mass Spectrometry (method 

2001)

The results of analysis using method 2001 show that 

widely used herbicides are frequently detected in rawwater samples from water-supply intakes. Atrazine, 

metolachlor, and simazine were detected at every rawwater intake site; and deethylatrazine, a triazine degradate, 

was detected in raw-water samples from all sites except 

CA. Each of these compounds was detected in more than 

90 percent of the 323 raw-water samples. Other commonly 

used herbicides including prometon, cyanazine, 

tebuthiuron, acetochlor, and alachlor were detected in 

greater than 26 percent of all intake samples. Insecticides 

were detected less frequently in intake samples than 

herbicides. Diazinon (35.3 percent) and chlorpyrifos (5.3 

percent) were the two most frequently detected 

insecticides, with p,p’-DDE, azinphos-methyl, carbaryl, 

carbofuran, and dieldrin occurring in fewer than 5 percent 

of all raw-water samples. In all, 17 compounds were 

detected in less than 5 percent of the intake samples. In 

most cases, the occurrence of these compounds is limited 

to only a few sites. The observed detection frequencies for 

intake-water samples are similar to those reported for 58 

stream sites sampled by the NAWQA program during 

1992-95 (Larson and others, 1998). 

Herbicides were frequently detected in finished-water 

samples and the high-use compounds were found in 

frequencies only slightly lower than those of raw water. 

Metribuzin, however, was detected in nearly 15 percent of 

the intake samples and was not detected in any finishedwater sample. None of the herbicides were detected in 

finished water at a concentration greater than a national 

drinking-water criterion. 

Six insecticides (p,p’-DDE, azinphos-methyl, carbaryl, 

carbofuran, fonofos, and phorate) were detected in 

finished-water samples, with each of these compounds 

detected in less than 3 percent of the samples. Fonofos 

was detected in three finished-water samples and phorate 

in one sample—neither of these comp ounds was detected 

in raw water. Three of the organophosphorus insecticides 

found in raw-water samples (diazinon, chlorpyrifos, and 

malathion) were not detected in any finished-water 

samples. Several studies have shown that 

organophosphorus compounds are readily oxidized in the 

presence of chlorine (Adnan and Yurdun, 1999; Aizawa 

and others, 1994). The oxidative products of these 

compounds include diazoxon, chlorpyrifos-oxygen analog, 

and malaoxon. 
Summary of Results from a Pilot Monitoring Program 21

Table 8. Summary of analysis of pesticides in water samples from water-supply intakes and finished 

water-supply taps using gas chromatography / mass spectrometry—U.S. Geological Survey 

National Water Quality Laboratory method 2001

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; ()=qualified estimates of pesticide 

concentrations-- for concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method 

performance; H, herbicide; D, degradate; I, insecticide]

Samples from raw-water intake (n = 323) Samples from finished-water tap (n = 228)

Compound (class) Method Number Detection 95th Maximum Number Detection 95th Maximum

reporting of frequency percentile value of frequency percentile value

level detections in percent value detections in percent value

Atrazine (H) 0.001 311(8) 96.3 0.516 11.600 218(13) 95.6 1.400 2.470

Simazine (H) 0.005 293(6) 90.7 0.028 1.520 192(7) 84.2 0.385 0.571

Deethylatrazine (D) 0.002 289(289) 89.5 0.080 0.771 203(203) 89.0 0.265 0.352

Metolachlor (H) 0.002 288(12) 89.2 0.033 3.320 198(4) 86.8 0.336 0.661

Prometon (H) 0.018 241(164) 74.6 0.017 0.138 145(109) 63.6 0.067 0.103

Cyanazine (H) 0.004 145(4) 44.9 0.007 0.332 96(3) 42.1 0.128 0.355

Tebuthiuron (H) 0.010 135(87) 41.8 0.010 0.030 64(46) 28.1 0.019 0.032

Acetochlor (H) 0.002 115 35.6 0.002 0.334 69(1) 30.3 0.061 0.395

Diazinon (I) 0.002 114(20) 35.3 0.002 0.101 0 0.0 --- ---

Alachlor (H) 0.002 87(5) 26.9 0.002 0.655 51(4) 22.4 0.027 0.148

Metribuzin (H) 0.004 47 14.6 0.004 0.291 0 0.0 --- ---

Pronamide (H) 0.003 34 10.5 0.003 0.048 9(1) 3.9 --- 0.017

EPTC (H) 0.002 25(5) 7.7 0.002 0.037 12(1) 5.3 0.005 0.030

Chlorpyrifos (I) 0.004 17(9) 5.3 0.004 0.034 0 0.0 --- ---

Dacthal (H) 0.002 16(15) 5.0 0.002 0.014 8(8) 3.5 --- 0.004

p,p'-DDE (I) 0.006 14(14) 4.3 --- 0.006 6(6) 2.6 --- 0.006

Trifluralin (H) 0.002 9(9) 2.8 --- 0.009 5(4) 2.2 --- 0.009

Azinphos-methyl (I) 0.001 8(8) 2.5 --- 0.144 5(5) 2.2 --- 0.114

Terbacil (H) 0.007 7(7) 2.2 --- 0.100 0 0.0 --- ---

Carbaryl (I) 0.003 7(7) 2.2 --- 0.047 2(2) 0.9 --- 0.041

Malathion (H) 0.005 6 1.9 --- 0.106 0 0.0 --- ---

Pendimethalin (H) 0.004 6 1.9 --- 0.125 3 1.3 --- 0.010

Fonofos (I) 0.003 0 0.0 --- --- 3 1.3 --- 0.040

Carbofuran (I) 0.003 2(2) 0.6 --- 0.050 3(3) 1.3 --- 0.030

2,6 Diethylaniline (D) 0.003 2(2) 0.6 --- 0.003 1(1) 0.4 --- 0.003

Phorate (I) 0.002 0 0.0 --- --- 1(1) 0.4 --- 0.011

Benfluralin (H) 0.002 1(1) 0.3 --- 0.010 0 0.0 --- ---

Butylate (H) 0.002 1(1) 0.3 --- 0.002 0 0.0 --- ---

Dieldrin (I) 0.001 1(1) 0.3 --- 0.010 0 0.0 --- ---

Linuron (H) 0.002 1 0.3 --- 0.035 0 0.0 --- ---

Molinate (H) 0.004 1(1) 0.3 --- 0.004 0 0.0 --- ---

Napropamide (H) 0.003 1(1) 0.3 --- 0.007 0 0.0 --- ---

Parathion-methyl (I) 0.006 1 0.3 --- 0.061 0 0.0 --- ---

Triallate (H) 0.001 1(1) 0.3 --- 0.002 0 0.0 --- ---

The following compounds were not detected in any water sample. Method detection level in micrograms per liter shown in ()’s. Herbicide: 

Ethalfluralin (0.004), Pebulate (0.004), Propachlor (0.007), Propanil (0.004), Thiobencarb (0.002), Insecticide: alpha-HCH (0.002), 

Disulfoton (0.017), Ethoprop (0.003), Lindane (0.004), Parathion (0.004), Permethrin, cis (0.005), Propargite (0.013), Terbufos (0.013),
22 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

Gas Chromatography / Mass Spectrometry (provisional 

method 9002)

Compounds included in NWQL provisional method 

9002 were generally detected much less frequently than 

compounds in method 2001. Two compounds were 

detected in more than 10 percent of the intake samples—

3,4-dichloroaniline with 19.9 percent detections, and 

prometryn with 16.1 percent detections (table 9). 3,4-

dichloroaniline was detected in only one finished-water 

sample and prometryn was not detected in any finishedwater samples. 3,4-Dichloroaniline is a degradation 

product of three different compounds: linuron, propanil, 

and neburon. Sandstrom and others (2001) reported that 

diruon may be transformed to 3,4-dichloroaniline in the 

gas chromatograph injection port and that some 

percentage of the reported concentration of this compound 

may originate from diuron in the sample extract.

Twenty-one degradation products were found in water 

samples using this method—17 in raw water and 14 in 

finished-water samples. Malaoxon, the principal oxidative 

transformation product of malathion, was detected in 11 

finished-water samples and none of the raw-water 

samples. In three of the samples where malaoxon was 

detected in finished water, the corresponding intake 

sample showed measurable concentrations of malathion. 

Other transformation products that were detected in more 

finished-water samples than intake samples include: 

azinphos-methyl-oxon, fenamiphos sulfone, terbufos-Oanalogue sulfone, and 4-chloro-2-methyl phenol (a 

degradate of MCPA and MCPB). Chlorpyrifos oxygen 

analog was not detected in any finished-water samples, 

although chlorpyrifos was detected in 5.3 percent of the 

raw-water samples using method 2001.

Most compounds detected with this method were 

found in four or fewer of the intake or finished-water 

samples, with most concentrations observed at or near the 

method detection level. Of these, 23 were detected in rawwater samples and 16 were detected in finished-water 

samples. Forty-one of the 75 compounds reported were 

not detectable in any intake or finished-water sample. 
Summary of Results from a Pilot Monitoring Program 23

Table 9. Summary of analysis of moderate-use pesticides and degradates in water samples from watersupply intakes and finished water-supply taps using gas chromatography / mass spectrometry—

U.S. Geological Survey National Water Quality Laboratory provisional method 9002

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; ()=qualified estimates of pesticide 

concentrations-- for concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method 

performance; H, herbicide; D, degradate; I, insecticide; F, fungicide]

Samples from raw-water intake (n = 317) Samples from finished-water tap (n = 221)

Compound (Class) Method Number Detection 95th Maximum Number Detection 95th Maximum

reporting of frequency percentile value of frequency percentile value

level detections in percent value detections in percent value

3,4-Dichloroaniline (D) 0.008 63(21) 19.9 0.019 0.061 1(1) 0.5 --- 0.008

Prometryn (H) 0.005 51(23) 16.1 0.026 0.041 0 0.0 --- ---

Malaoxon (D) 0.016 0 0.0 --- --- 11(3) 5.0 0.016 0.556

3-Trifluoromethylaniline (D) 0.005 12(11) 3.8 --- 0.008 0 0.0 --- ---

2-[2-Ethyl-6-methylphenyl)

amino]-1-propanal (D) 0.016 11(9) 3.5 --- 0.074 6(6) 2.7 --- 0.016

2,5-Dichloroaniline (D) 0.005 10(2) 3.2 --- 0.020 2(1) 0.9 --- 0.009

Azinphos-methyl-oxon (D) 0.031 1 0.3 --- 0.263 4(4) 1.8 --- 0.063

4-Chloro-2-methyl

phenol (D) 0.005 1(1) 0.3 --- 0.005 4(4) 1.8 --- 0.007

2-Chloro-2,6-diethylacetanilide (D) 0.008 4 1.3 --- 0.012 0 0.0 --- ---

Dimethoate (I) 0.005 4(1) 1.3 --- 0.022 0 0.0 --- ---

Metalaxyl (F) 0.016 4(4) 1.3 --- 0.016 2(2) 0.9 --- 0.016

4-(Hydroxymethyl)

pendimethalin (D) 0.031 3(3) 0.9 --- 0.045 1(1) 0.5 --- 0.126

1,4-Naphthoquinone (D) 0.008 3(3) 0.9 --- 0.008 1(1) 0.5 --- 0.008

1-Naphthol (D) 0.005 3(3) 0.9 --- 0.228 0 0.0 --- ---

Endosulfan sulfate (D) 0.008 3(2) 0.9 --- 0.009 2(2) 0.9 --- 0.008

Myclobutanil (F) 0.008 3(2) 0.9 --- 0.015 0 0.0 --- ---

Tebupirimphos (I) 0.008 3(3) 0.9 --- 0.008 0 0.0 --- ---

4,4'-Dichlorobenzophenone (D) 0.008 0 0.0 --- --- 2(2) 0.9 --- 0.008

Fenamiphos sulfone (D) 0.008 1(1) 0.3 --- 0.008 2(1) 0.9 --- 0.016

Terbufos-O-analogue 

sulfone (D) 0.016 0 0.0 --- --- 2(2) 0.9 --- 0.016

Fenamiphos sulfoxide (D) 0.031 2(1) 0.6 --- 0.033 1(1) 0.5 --- 0.031

Hexazinone (H) 0.008 2(2) 0.6 --- 0.008 0 0.0 --- ---

Tefluthrin metabolite

 [R 119364] (D) 0.005 2(2) 0.6 --- 0.005 0 0.0 --- ---

Tefluthrin metabolite 

[R 152912] (D) 0.008 2(1) 0.6 --- 0.021 0 0.0 --- ---

3,5-Dichloroaniline (D) 0.005 0 0.0 --- --- 1 0.5 --- 0.009

Bifenthrin (I) 0.005 0 0.0 --- --- 1(1) 0.5 --- 0.005

Iprodione (F) 0.031 0 0.0 --- --- 1(1) 0.5 --- 0.031

Isofenphos (I) 0.008 1(1) 0.3 --- 0.008 1(1) 0.5 --- 0.008

cis-Propiconazol (F) 0.005 1(1) 0.3 --- 0.005 0 0.0 --- ---

Disulfoton sulfone (D) 0.005 1 0.3 --- 0.013 0 0.0 --- ---

Disulfoton sulfoxide (D) 0.016 1(1) 0.3 --- 0.016 0 0.0 --- ---

Methidathion (I) 0.008 1 0.3 --- 0.110 0 0.0 --- ---

Tefluthrin (I) 0.008 1(1) 0.3 --- 0.008 0 0.0 --- ---

trans-Propiconazol (F) 0.005 1(1) 0.3 --- 0.005 0 0.0 --- ---

The following compounds were not detected in any water sample. Method detection level in micrograms per liter shown in ()’s. 

Defoliant: Tribuphos (0.016); Fungicide : E-Dimethomorph (0.031), Z-Dimethomorph (0.031), Ethion monoxon (0.008); Herbicide: Cycloate (0.016), 

Oxyfluorfen (0.016), Terbuthylazine (0.005); Insecticide: Cyhalothrin (0.008), Cyfluthrin (0.031), Cypermethrin (0.031), Dicrotophos (0.016), Ethion 

(0.005), Fenthion (0.005), Phosmet (0.008), Profenofos (0.008), Propetamphos (0.016), Sulfotepp (0.005), Sulprofos (0.005), Temephos (0.031); Nematocide : 

Fenamiphos (0.016); Plant Growth Regulator: Flumetralin (0.016);

Degradate: 2-Amino-N-isopropylbenzamide (0.005), 2-Ethyl-6-methylaniline (0.005), 3-Phenoxybenzyl alcohol (0.031), 4-Chlorobenzylmethyl sulfone 

(0.008), Chlorpyrifos oxygen analog (0.016), c-Methyl-3-(2,2-dichlorovinyl)-2,2-dimethyl-(1-cyclopropane)-carboxylate (0.016), 2-(4-tert-butylphenoxy) 

cyclohexanol (0.016), Diclorvos (0.005), alpha-Endosulfan (0.016), beta-Endosulfan (0.016), Endosulfan-ether (0.016), Fenthion sulfoxide (0.008), Fonofos 

oxygen analog (0.016), O-ethyl-O-methyl-S-propylphosphorothioate (0.005), t-Methyl-3-(2,2-dichlorovinyl)-2,2-dimethyl-(1-cyclopropane)-carboxylate 

(0.016), Paraoxon-ethyl (0.031), Paraoxon-methyl (0.031), Phorate oxon (0.031), Phosmet oxon (0.016), Tebupirimphos oxygen analog (0.016)
24 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

High-Performance Liquid Chromatography / Mass 

Spectrometry (provisional method 9060)

Sample results for NWQL provisional method 9060 

(table 10) also show that the widely used herbicides are 

often detected in samples of both raw and finished water. 

This method provides data on three additional triazine 

degradation products that are not included in method 

2001, including: 2-hydroxy atrazine, deisopropylatrazine, 

and desethyl-desisopropylatrazine. Each of these 

compounds was detected in greater than 60 percent of the 

raw- and finished-water samples and the maximum 

observed concentrations were nearly equal between the 

two sample sources. Atrazine and deethylatrazine are 

included in method 9060 and method 2001, however, the 

MRL for these compounds, as well as other compounds, in 

method 9060 are generally much greater than for 

compounds included in method 2001, and range from 0.01 

to 0.114 μg/L. Therefore, the detection frequencies based 

on this method are expected to be somewhat lower for 

compounds that are included in both methods. 

Nine herbicides and one fungicide (metalaxyl) were 

detected in greater than 10 percent of the raw-water 

samples. Four of these compounds (diuron, bentazon, 

chlorimuron-ethyl, and sulfometuron-methyl) were 

detected in less than 10 percent of the finished-water 

samples. A total of 48 pesticide compounds were detected 

in intake or finished-water samples. An additional 16 

compounds were included in the method but not detected 

in any water samples.

Caffeine is not a widely used pesticide or a 

degradation product, but it was included in this method 

because of its utility as an indicator of wastewater effluent 

and because its chemical characteristics make it well 

suited for this analytical technique. Caffeine was detected 

in about 36 percent of all intake samples.
Summary of Results from a Pilot Monitoring Program 25

Table 10. Summary of analysis of pesticides in water samples from water-supply intakes and finished 

water-supply taps using high performance liquid chromatography / mass spectrometry—U.S. 

Geological Survey National Water Quality Laboratory provisional method 9060

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; ()=qualified estimates of pesticide 

concentrations-- for concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method 

performance; H, herbicide; D, Degradate; I, insecticide; F, fungicide]

Samples from raw-water intake (n = 312) Samples from finished-water tap (n = 225)

Compound Method Number Detection 95th Maximum Number Detection 95th Maximum

reporting of frequency percentile value of frequency percentile value

Level detections in percent value detections in percent value

Atrazine (H) 0.074 265(140) 84.9 1.888 6.176 185(86) 82.2 1.118 1.944

2-Hydroxyatrazine (D) 0.193 256(255) 82.3 1.263 2.058 182(182) 81.3 1.008 1.785

Deisopropylatrazine (D) 0.074 250(210) 80.1 0.195 0.386 146(136) 64.9 0.081 0.178

Deethylatrazine (D) 0.087 249(196) 79.8 0.340 0.546 167(147) 74.6 0.201 0.267

Desethyl desisopropyl 

atrazine (D) 0.060 216(184) 69.2 0.079 0.150 141(137) 62.7 0.060 0.150

2,4-D (H) 0.077 179(92) 57.4 0.158 0.414 98(60) 43.6 0.132 0.634

Metalaxyl (F) 0.057 133(123) 42.6 0.057 0.351 80(79) 35.6 0.057 0.072

Tebuthiuron (H) 0.077 118(118) 37.8 0.077 0.077 42(42) 18.7 0.077 0.077

Diuron (H) 0.079 117(70) 37.5 0.319 0.540 13(13) 5.8 0.079 0.079

Caffeine* 0.081 112(88) 35.9 0.108 88.000 24(24) 10.7 0.081 0.081

Bentazon (H) 0.019 80(80) 25.6 0.021 0.344 21(21) 9.3 0.019 0.019

2,4-D methyl ester (D) 0.087 77(77) 24.7 0.087 0.087 44(42) 19.6 0.087 0.136

Dicamba (H) 0.096 61(45) 19.6 0.100 0.192 35(31) 15.6 0.096 0.147

Chlorimuron-ethyl (H) 0.037 52(45) 16.7 0.037 0.058 4(4) 1.8 --- 0.040

Bromacil (H) 0.081 49(47) 15.7 0.081 0.481 2(2) 0.9 --- 0.481

Sulfometuron-methyl (H) 0.039 38(21) 12.2 0.095 0.160 6(6) 2.7 --- 0.039

Fluometuron (H) 0.062 24(5) 7.7 0.145 0.264 19(17) 8.4 0.062 0.100

Clopyralid (H) 0.041 21(8) 6.7 0.042 0.170 4(3) 1.8 --- 0.059

Benomyl (F) 0.022 20(19) 6.5 0.022 0.038 2(2) 0.9 --- 0.215

Picloram (H) 0.071 11(1) 3.5 --- 1.441 11(1) 4.9 0.094 0.389

Imazaquin (H) 0.103 14(14) 4.5 --- 0.351 9(9) 4.0 --- 0.111

Nicosulfuron (H) 0.065 9(9) 2.9 --- 0.139 8(8) 3.6 --- 0.093

Imazethapyr (H) 0.088 10(10) 3.4 --- 0.133 3(3) 1.4 --- 0.088

Flumetsulam (H) 0.087 9(9) 2.9 --- 0.088 4(4) 1.8 --- 0.087

MCPA (H) 0.059 9(7) 2.9 --- 0.121 1 0.4 --- 0.077

Diphenamid (H) 0.058 7(7) 2.2 --- 0.058 3(3) 1.3 --- 0.058

Norflurazon (H) 0.077 6(5) 1.9 --- 0.414 0 0.0 --- ---

Bromoxynil (H) 0.057 0 0.0 --- --- 4(4) 1.8 --- 0.057

Oryzalin (H) 0.071 3 1.0 --- 0.127 4(2) 1.8 --- 0.095

Triclopyr (H) 0.101 3(3) 1.0 --- 0.101 4(4) 1.8 --- 0.101

Acifluorfen (H) 0.062 5(5) 1.7 --- 0.062 1(1) 0.5 --- 0.062

3(4-chlorophenyl)-1-methyl

 urea (D) 0.092 5(5) 1.6 --- 0.092 0 0.0 --- ---

Metsulfuron-methyl (H) 0.114 4(3) 1.3 --- 1.194 1(1) 0.4 --- 0.200

Dichlorprop (H) 0.050 3(3) 1.0 --- 0.050 1(1) 0.4 --- 0.050

Oxamyl oxime (D) 0.064 0 0.0 --- --- 2(2) 0.9 --- 0.064

2,4-DB (H) 0.054 0 0.0 --- --- 2(2) 0.9 --- 0.054

Carbaryl (I) 0.063 2(2) 0.6 --- 0.063 0 0.0 --- ---

Carbofuran (I) 0.057 2(2) 0.6 --- 0.057 1(1) 0.4 --- 0.057

Dinoseb (H) 0.043 2(2) 0.6 --- 0.043 1(1) 0.4 --- 0.043

Siduron (H 0.093 2(2) 0.6 --- 0.093 0 0.0 --- ---

* Caffeine is not a pesticide compound, however it is included in this method.
26 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

Table 10 Summary of analysis of pesticides in water samples from water-supply intakes and finished 

water-supply taps using high performance liquid chromatography / mass spectrometry—U.S. 

Geological Survey National Water Quality Laboratory provisional method 9060 –Continued.

Samples from raw-water intake (n = 312) Samples from finished-water tap (n = 225)

Compound Method Number Detection 95th Maximum Number Detection 95th Maximum

reporting of frequency percentile value of frequency percentile value

level detections in percent value detections in percent value

Propoxur (I) 0.059 1(1) 0.3 --- 0.059 1 0.5 --- 0.823

3-Hydroxycarbofuran (D) 0.062 0 0.0 --- 0.062 1(1) 0.4 --- 0.062

Bendiocarb (I) 0.061 0 0.0 --- 0.061 1(1) 0.4 --- 0.061

Neburon (H) 0.075 1(1) 0.3 --- 0.075 1(1) 0.4 --- 0.075

Propiconazole (F) 0.064 1(1) 0.3 --- 0.064 1(1) 0.4 --- 0.064

Chloramben methyl ester (H) 0.114 1 0.3 --- 0.126 0 0.0 --- ---

Aldicarb sulfone (D) 0.160 1(1) 0.3 --- 0.160 0 0.0 --- ---

Imidacloprid (I) 0.106 1(1) 0.3 --- 0.106 0 0.0 --- ---

Terbacil (H) 0.095 1(1) 0.3 --- 0.100 0 0.0 --- ---

The following compounds were not detected in any water sample. Method detection level in micrograms per liter shown in ()’s:

Herbicide: Chlorothalonil (0.049), Cycloate (0.054), Fenuron (0.074), Linuron (0.070), MCPB (0.063), Propham (0.072), Tribenuronmethyl (0.068), Insecticide: Aldicarb (0.082), Methiocarb (0.080), Methomyl (0.077), Oxamyl (0.016), Degradate: 3-keto-carbofuran 

(0.072), Aldicarb sulfoxide (0.027), Bensulfuron-methyl (0.048), Dacthal monoacid (0.072), Methomyl oxime (0.010),

Summary 

The pilot monitoring program described in this report 

was initiated by the U.S. Geological Survey National 

Water-Quality Assessment Program and the U.S. 

Environmental Protection Agency Office of Pesticide 

Programs to provide monitoring data on pesticide 

concentrations in drinking water because the Office of 

Pesticide Programs has responsibility under the Food 

Quality Protection Act of 1996 to assess aggregate risk 

from exposure to pesticides in drinking water based on 

available data. This program was designed to fill 

important data gaps and to provide more information 

about appropriate methods for National monitoring of 

pesticides in drinking water. This report presents and 

summarizes the data collected during the pilot monitoring 

program conducted in 1999 and 2000. The design of the 

monitoring program is described in order to facilitate 

effective analysis of the data collected to meet a broad 

array of goals and objectives. 

The pilot monitoring program was designed as a first 

step towards a long-term goal of characterizing human 

exposure to pesticide residues in drinking water derived 

from surface-water sources. The principal goal of this 

program is to develop a data set on the occurrence of 

pesticides in drinking-water sources that is tied to 

pesticide concentrations observed in finished drinking 

water. Reservoirs and community water systems that 

withdraw from reservoirs were selected for this pilot 

monitoring program because reservoirs are considered to 

be highly vulnerable to pesticide contamination, serve as 

integrators of pesticide loading from their watersheds, and 

are important sources of drinking water. 

Twelve community water systems supplied by 

reservoirs were selected for study based on their 

vulnerability to pesticides from their contributing 

watersheds. The reservoirs sampled range in size from 120 

to 92,600 acre-feet normal capacity, with contributing 

watersheds ranging from 3.3 to 784 square miles and are 

located in California, Indiana, Ohio, Oklahoma, Louisiana, 

Missouri, South Carolina, South Dakota, New York, North 

Carolina, Pennsylvania, and Texas. Ten of these sites were 

selected because they were representative of regional 

agricultural practices and two sites (Oklahoma and 

California) were selected because they were representative 

of urban pesticide runoff. 

The primary sampling approach involved sample 

collection from the raw-water intake as well as from the 

finished-water tap located at the entry point to the 

distribution system. Samples were also collected at the 

outflow of many of the reservoirs because the waterquality conditions at an intake may substantially differ 

from average reservoir conditions. All samples were 

collected by trained U.S. Geological Survey personnel, 

following sample-collection protocols documented by the 

U.S. Geological Survey. The sampling frequency was 

designed to characterize the occurrence of commonly 

occurring pesticides and to identify compounds that may 

occur for only a short period of time at concentrations 

greater than the laboratory reporting level. Each site was 

sampled quarterly over a one-year period, with semi-
Summary of Results from a Pilot Monitoring Program 27

weekly samples collected during a 4-month period 

coincident with the most intensive application season. 

Four site had additional raw-water samples collected every 

week for a 6-month period. In 1999, drought conditions 

extended across the Eastern Unites States and California, 

thus the conditions measured at six sites in 1999 were not 

representative of average runoff patterns. This was a 

primary consideration in the decision to extend sampling 

at nine sites through 2000.

Three laboratory methods were used during the pilot 

monitoring program— an approved method and two 

developmental methods. Together, these three methods 

measure 178 different pesticides and pesticide degradation 

products in filtered-water samples. The primary method, 

method 2001, uses C-18 solid-phase extraction and gas 

chromatography / mass spectrometry to determine 

concentrations of 47 pesticides and pesticide metabolites 

in water samples. The two developmental methods were 

included in this program in order to expand the available 

information on the occurrence of a wide number of 

pesticides and pesticide degradates in surface water across 

the Nation, and to test for the occurrence of these 

compounds in drinking-water supplies. These methods 

were included with the knowledge that the methods were 

developmental and that the performance of the methods 

may be more variable than would be expected of a 

thoroughly tested and approved method. Provisional 

method 9002 is an adaptation of the C-18 solid-phase 

extraction and gas chromatography / mass spectrometry 

technology used in method 2001. The method provides a 

quantitative analysis of 20 parent pesticides and 21 

pesticide degradates, and provides qualitative estimates for 

14 parent pesticides and 20 degradates. Provisional 

method 9060 is a substantially new technique using 

graphitized carbon solid-phase extraction and highperformance liquid chromatography/mass spectrometry for 

the instrumental analysis of extracts. This method is 

designed to determine low-level concentrations of 64 polar 

pesticides and pesticide degradates. 

Overall, the three methods provided analyses for 178 

different parent pesticide or degradation products. Of 

these, 108 compounds were detected in at least one sample 

of raw water at an intake or of finished water. Many of 

these compounds, however, were detected in fewer than 5 

percent of the samples and at concentrations very near the 

method reporting level. The observed detection 

frequencies for intake water are similar to those reported 

for 58 stream sites sampled by the NAWQA program in 

1992-95. 

The results show that widely used herbicides and 

triazine degradation products are frequently detected in 

samples from water-supply intakes as well as in finishedwater samples. Atrazine, simazine, and metolachlor were 

detected in at least one raw-water sample from each of the 

12 monitoring sites; and deethylatrazine, a triazine 

degradate, was detected in raw-water samples from all 

sites except the California site. Other commonly used 

herbicides including metolachlor, prometon, cyanazine, 

2,4-D, tebuthiuron, acetochlor and alachlor were detected 

in more than 26 percent of all intake samples. Insecticides 

were detected less frequently in intake samples than 

herbicides. Four triazine-herbicide degradation products 

(2-hydroxyatrazine, deisopropylatrazine, deethylatrazine, 

and desethyl-deisopropylatrazine) were detected in more 

than 60 percent of both the raw and finished-water 

samples. None of the herbicides were detected in finished 

water at a concentration greater than a National drinkingwater criterion.

Insecticides were detected less frequently in water 

samples than herbicides. Diazinon and chlorpyrifos were 

the two most frequently detected insecticides (detected in 

35.3 percent and 5.3 percent of the raw-water samples, 

respectively). Neither diazinon, chlorpyrifos, nor 

malathion, three organophosphorus insecticides, were 

detected in any finished-water samples. Several studies 

have shown that organophosphorus compounds are readily 

oxidized in the presence of chlorine, with the oxidative 

products of these compounds being diazinon, chlorpyrifos 

oxygen analog, and malaoxon. Malaoxon, the principal 

oxidative transformation product of malathion, was 

detected in 11 finished-water samples and none of the 

raw-water samples. In three of the samples where 

malaoxon was detected in finished water, the 

corresponding intake sample showed measurable 

concentrations of malathion. Chlorpyrifos oxygen analog 

was not detected in any water sample, and diazoxon was 

not included as an analyte on any of the three methods.
28 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

Selected References

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organochlorine pesticides in water sources of 

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Eckhardt, D.A., Kappel, W. M., Coon, W. F., and Phillips, 

P. J., 1999, Herbicides and their metabolites in 

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Morganwalp, D.W., and Buxton, H.T., eds., U.S. 

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Geological Survey Water-Resources Investigations 

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analyses of water and fluvial sediments: U.S. 

Geological Survey Techniques of Water-Resources 

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Gilliom, R. J. and Thelin, G. P., 1997. Classification and 

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methods to estimate pesticide concentrations in 

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International Life Sciences Institute, Risk Science 

Institute, 

Larson, S. J., Gilliom R. J., and Capel, P. D., 1998, 

Pesticides in streams of the United States--Initial 

results from the National Water-Quality Assessment 

Program: U.S. Geological Survey Water-Resources 

Investigations Report 98-4222, 99 p.

Martin, J. D., 1999, Quality of pesticide data for 

environmental water samples collected for the 

National Water-Quality Assessment Program, 1992-

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Mueller, D. K., Martin, J. D., and Lopes, T. J., 1997, 

Quality-control design for surface-water sampling in 

the National Water-Quality Assessment Program: 

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p.

Phillips, P. J., Eckhardt, D. A., Smith, M. A., and 

Rosenmann, L., 1999, Pesticides and their metabolites 

in selected surface-water public supplies in New York 

State: U.S. Geological Survey Water-Resources 

Investigations Report 00-4119, 17 p.

Pirkey, K.D., and Glodt, S.R., 1998, Quality control at the 

U.S. Geological Survey National Water Quality 

Laboratory: U.S. Geological Survey Fact Sheet FS026-98, 4 p.

Pritt, J.W., and Raese, J.W., 1995, Quality 

assurance/quality control manual--National Water 

Quality Laboratory: U.S. Ge ological Survey OpenFile Report 95-443, 35 p. 

Sandstrom, M. W., Stroppel, M. E., Foreman, W. T., and 

Schroeder, M. P., 2001, Methods of analysis by the 

U.S. Geological Survey National Water Quality 

Laboratory—Determination of moderate-use 

pesticides and selected degradates in water by C-18 

solid-phase extraction and gas chromatography/mass 

spectrometry: U.S. Geological Survey WaterResources Investigations Report 01-4098, 70 p.

Shelton, L. R., 1994, Field guide for collecting and 

processing stream-water samples for the National 

Water-Quality Assessment Program: U.S. Geological 

Survey Open-File Report 94-455, 42 p.

Thelin, G. P., and Gianessi, L. P., 2000, Methods for 

estimating pesticide use for county areas in the 

conterminous United States: U.S. Geological Survey 

Open-File Report 00-250, 62 p.

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of Dams, Washington, D.C., [CD-ROM].

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agriculture: Washington, D.C. [CD-ROM, dBase 

format].
Summary of Results from a Pilot Monitoring Program 29

U.S. Environmental Protection Agency, 1998, Proposed 

methods for basin-scale estimation of pesticide 

concentrations in flowing water and reservoirs for 

tolerance reassessment: U.S. Environmental 

Protection Agency Office of Pesticide Programs 

Science Advisory Panel, July 29-30, 1998, [variously 

paged].

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available from the Safe Drinking Water Information 

System; U.S. Environmental Protection Agency 

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U.S. Geological Survey water-quality analytical 

methods: Office of Water Quality Technical 

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URL 

http://water.usgs.gov/admin/memo/QW/qw98.05.html.

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1990s National Land Cover Data Set for the 

Conterminous United States from Landsat thematic 

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Photogrammetric Engineering and Remote Sensing, 

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[variously paged].

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K.M., 1995, Methods of analysis by the U.S. 

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30 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

Supplemental Tables
Summary of Results from a Pilot Monitoring Program 31

Table 11. Statistical summary of pesticides and degradates detected in water samples from the watersupply intake monitoring site at Canyon Reservoir near Elsinore, California

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Prometon 8 8(1) 100 0.025 0.028 0.028

Simazine 8 8 100 0.078 0.091 0.091

Diazinon 8 7 87.5 0.015 0.045 0.045

Tebuthiuron 8 6(6) 75.0 0.007 0.012 0.012

Atrazine 8 4(2) 50.0 0.002 0.006 0.006

Dacthal 8 4(4) 50.0 0.001 0.003 0.003

Metolachlor 8 3(1) 37.5 --- 0.005 0.005

Tri-allate 8 1(1) 12.5 --- 0.002 0.002

Trifluralin 8 1(1) 12.5 --- 0.002 0.002

Analysis of Moderate-Use Pesticides and Degradates by GC-MS (NWQL provisional method 9002)

3,4-Dichloroaniline 8 8 100 0.044 0.061 0.061

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

Sulfometuron-methyl 8 8(3) 100 0.098 0.131 0.131

Diuron 8 7 87.5 0.340 0.540 0.540

3(4-chlorophenyl)-1-methyl urea 8 5(5) 62.5 0.008 0.026 0.026

Desethyl desisopropylatrazine 8 5(5) 62.5 0.005 0.011 0.011

2-Hydroxyatrazine 8 3(3) 37.5 --- 0.028 0.028

Deisopropylatrazine 8 3(3) 37.5 --- 0.019 0.019

Tebuthiuron 8 3(3) 37.5 --- 0.011 0.011

Bromacil 8 1(1) 12.5 --- 0.005 0.005

Caffeine* 8 1(1) 12.5 --- 0.026 0.026

Dicamba 8 1(1) 12.5 --- 0.090 0.090

MCPA 8 1(1) 12.5 --- 0.011 0.011

Norflurazon 8 1 12.5 --- 0.414 0.414

* Caffeine is not a pesticide compound, however it is included in this method.
32 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

Table 12. Statistical summary of pesticides and degradates detected in water samples from the finishedwater monitoring site at Elsinore Valley Municipal Water District, California

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Prometon 8 8(3) 100 0.022 0.030 0.030

Simazine 8 8 100 0.062 0.078 0.078

Atrazine 8 4(3) 50.0 0.002 0.005 0.005

Tebuthiuron 8 4(3) 50.0 0.003 0.018 0.018

Dacthal 8 2(2) 25.0 --- 0.002 0.002

Metolachlor 8 1 12.5 --- 0.003 0.003

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

2-Hydroxyatrazine 8 2(2) 25.0 --- 0.028 0.028

Desethyl desisopropylatrazine 8 2(2) 25.0 --- 0.013 0.013

Tebuthiuron 8 2(2) 25.0 --- 0.008 0.008
Summary of Results from a Pilot Monitoring Program 33

Table 13. Statistical summary of pesticides and degradates detected in water samples from the watersupply intake monitoring site at Eagle Creek Reservoir, Indiana

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Atrazine 48 48 100 1.050 1.840 2.140

Deethylatrazine 48 48(48) 100 0.091 0.198 0.290

Metolachlor 48 48 100 0.308 0.765 0.950

Prometon 48 47(29) 97.9 0.016 0.030 0.034

Acetochlor 48 41 85.4 0.060 0.119 0.188

Simazine 48 38 79.2 0.018 0.025 0.028

Cyanazine 48 30 62.5 0.008 0.028 0.035

Tebuthiuron 48 23(16) 47.9 --- 0.010 0.012

Diazinon 48 19(6) 39.6 --- 0.008 0.010

Metribuzin 48 19 39.6 --- 0.020 0.025

Alachlor 48 12(1) 25.0 --- 0.010 0.014

Analysis of Moderate-Use Pesticides and Degradates by GC-MS (NWQL provisional method 9002)

3,4-Dichloroaniline 48 9(8) 18.8 --- 0.004 0.014

2-[2-Ethyl-6-methylphenyl)

Amino]-1-propan 48 1(1) 2.1 --- --- 0.007

cis-Propiconazol 48 1(1) 2.1 --- --- 0.005

Fenamiphos sulfoxide 48 1 2.1 --- --- 0.033

trans-Propiconazol 48 1(1) 2.1 --- --- 0.005

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

Atrazine 48 48(25) 100 0.891 1.423 2.280

Deethylatrazine 48 48(34) 100 0.112 0.211 0.303

2-Hydroxyatrazine 48 47(47) 97.9 0.552 0.878 1.335

Deisopropylatrazine 48 45(44) 93.8 0.030 0.074 0.097

Metalaxyl 48 44(44) 91.7 0.011 0.025 0.030

2,4-D 48 42(9) 87.5 0.120 0.192 0.356

Desethyl desisopropylatrazine 48 42(37) 87.5 0.028 0.068 0.106

Chlorimuron-ethyl 48 38(33) 79.2 0.018 0.037 0.058

Tebuthiuron 48 38(38) 79.2 0.003 0.007 0.010

Diuron 48 36(36) 75.0 0.030 0.055 0.065

2,4-D methyl ester 48 34(34) 70.8 0.017 0.044 0.067

Bentazon 48 31(31) 64.6 0.008 0.021 0.026

Dicamba 48 22(13) 45.8 --- 0.117 0.161

Clopyralid 48 20(7) 41.7 --- 0.079 0.170

Caffeine* 48 16(16) 33.3 --- 0.023 0.034

Bromacil 48 12(12) 25.0 --- 0.023 0.051

MCPA 48 5(4) 10.4 --- 0.011 0.121

Diphenamid 48 3(3) 6.3 --- --- 0.004

Flumetsulam 48 3(3) 6.3 --- --- 0.059

Imazaquin 48 2(2) 4.2 --- --- 0.060

Sulfometuron-methyl 48 2(2) 4.2 --- --- 0.009

Metsulfuron-methyl 48 1(1) 2.1 --- --- 0.002

Triclopyr 48 1(1) 2.1 --- --- 0.037

* Caffeine is not a pesticide compound, however it is included in this method.
34 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

Table 14. Statistical summary of pesticides and degradates detected in water samples from the reservoiroutflow monitoring site at Eagle Creek Reservoir, Indiana

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Atrazine 11 11 100 1.080 1.530 1.560

Cyanazine 11 11 100 0.015 0.017 0.021

Deethylatrazine 11 11(11) 100 0.120 0.200 0.208

Metolachlor 11 11 100 0.334 0.409 0.433

Prometon 11 10(9) 90.9 0.012 0.018 0.020

Acetochlor 11 9 81.8 0.059 0.108 0.132

Simazine 11 9 81.8 0.013 0.017 0.017

Metribuzin 11 6 54.5 0.009 0.014 0.025

Tebuthiuron 11 3(1) 27.3 --- 0.011 0.011

Alachlor 11 2(1) 18.2 --- 0.003 0.004

Diazinon 11 2(2) 18.2 --- 0.003 0.004

Analysis of Moderate-Use Pesticides and Degradates by GC-MS (NWQL provisional method 9002)

3,4-Dichloroaniline 11 1(1) 9.1 --- --- 0.007

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

2,4-D 11 11(4) 100 0.166 0.221 0.319

2-Hydroxyatrazine 11 11(11) 100 0.692 1.017 1.619

Atrazine 11 11(7) 100 0.848 1.198 1.392

Deethylatrazine 11 11(7) 100 0.110 0.198 0.200

Deisopropylatrazine 11 11(11) 100 0.026 0.046 0.054

Desethyl desisopropylatrazine 11 10(10) 90.9 0.027 0.058 0.066

Metalaxyl 11 10(10) 90.9 0.012 0.024 0.028

2,4-D methyl ester 11 7(6) 63.6 0.022 0.078 0.165

Chlorimuron-ethyl 11 7(6) 63.6 0.024 0.033 0.041

Tebuthiuron 11 7(7) 63.6 0.003 0.007 0.010

Bentazon 11 5(5) 45.5 --- 0.011 0.011

Diuron 11 5(5) 45.5 --- 0.030 0.052

Dicamba 11 4(4) 36.4 --- 0.060 0.062

Caffeine* 11 2(2) 18.2 --- 0.016 0.030

Clopyralid 11 2(1) 18.2 --- 0.040 0.053

Bromacil 11 1(1) 9.1 --- --- 0.028

* Caffeine is not a pesticide compound, however it is included in this method.
Summary of Results from a Pilot Monitoring Program 35

Table 15. Statistical summary of pesticides and degradates detected in water samples from the finishedwater monitoring site at Indianapolis Water Company, Indiana

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Atrazine 22 22 100 0.830 1.490 1.700

Deethylatrazine 22 22(22) 100 0.097 0.220 0.253

Metolachlor 22 22 100 0.145 0.360 0.661

Prometon 22 22(10) 100 0.019 0.028 0.032

Simazine 22 19 86.4 0.017 0.022 0.025

Acetochlor 22 13 59.1 0.018 0.105 0.121

Cyanazine 22 11 50.0 0.003 0.023 0.030

Tebuthiuron 22 6(5) 27.3 --- 0.009 0.011

Alachlor 22 3 13.6 --- 0.005 0.012

Fonofos 22 2 9.1 --- --- 0.023

Analysis of Moderate-Use Pesticides and Degradates by GC-MS (NWQL provisional method 9002)

3,4-Dichloroaniline 22 1(1) 4.5 --- --- 0.003

Fenamiphos sulfoxide 22 1(1) 4.5 --- --- 0.022

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

2-Hydroxyatrazine 22 22(22) 100 0.386 0.918 1.525

Deethylatrazine 22 22(14) 100 0.148 0.229 0.242

Atrazine 22 21(9) 95.5 0.575 1.123 1.519

2,4-D 22 20(3) 90.9 0.109 0.185 0.317

Deisopropylatrazine 22 20(19) 90.9 0.035 0.084 0.087

Desethyl desisopropylatrazine 22 18(15) 81.8 0.031 0.079 0.083

Metalaxyl 22 17(17) 77.3 0.012 0.022 0.026

2,4-D methyl ester 22 16(15) 72.7 0.018 0.042 0.087

Dicamba 22 12(9) 54.5 0.016 0.110 0.119

Diuron 22 10(10) 45.5 --- 0.024 0.026

Tebuthiuron 22 9(9) 40.9 --- 0.006 0.011

Bentazon 22 7(7) 31.8 --- 0.010 0.016

Caffeine* 22 4(4) 18.2 --- 0.010 0.026

Clopyralid 22 3(2) 13.6 --- 0.030 0.059

Diphenamid 22 3(3) 13.6 --- 0.003 0.006

Bromoxynil 22 1(1) 4.5 --- --- 0.011

Chlorimuron-ethyl 22 1(1) 4.5 --- --- 0.040

Flumetsulam 22 1(1) 4.5 --- --- 0.030

MCPA 22 1 4.5 --- --- 0.077

Oryzalin 22 1 4.5 --- --- 0.071

Propoxur 22 1 4.5 --- --- 0.823

* Caffeine is not a pesticide compound, however it is included in this method
36 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

Table 16. Statistical summary of pesticides and degradates detected in water samples from the watersupply intake monitoring site at Lake Bruin, Louisiana

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Atrazine 22 22 100 0.848 0.991 1.020

Cyanazine 22 22 100 0.173 0.238 0.332

Deethylatrazine 22 22(22) 100 0.156 0.188 0.195

Simazine 22 22 100 0.121 0.164 0.184

Metolachlor 22 21 95.5 0.013 0.026 0.033

Tebuthiuron 22 7(7) 31.8 --- 0.006 0.009

Prometon 22 6(6) 27.3 --- 0.005 0.008

Malathion 22 5 22.7 --- 0.023 0.106

Chlorpyrifos 22 3 13.6 --- 0.005 0.008

Trifluralin 22 3(3) 13.6 --- 0.002 0.002

Terbacil 22 2(2) 9.1 --- --- 0.054

Dacthal 22 1 4.5 --- --- 0.014

Diazinon 22 1 4.5 --- --- 0.010

EPTC 22 1(1) 4.5 --- --- 0.011

Parathion-methyl 22 1 4.5 --- --- 0.061

Analysis of Moderate-Use Pesticides and Degradates by GC-MS (NWQL provisional method 9002)

Prometryn 20 20 100 0.031 0.039 0.041

3-Trifluoromethylaniline 20 12(11) 60.0 0.003 0.007 0.008

3,4-Dichloroaniline 20 8(7) 40.0 --- 0.007 0.011

2,5-Dichloroaniline 20 1 5.0 --- --- 0.011

2-[2-Ethyl-6-methylphenyl)

amino]-1-propanal 20 1(1) 5.0 --- --- 0.074

Dimethoate 20 1 5.0 --- --- 0.007

Analysis of Pesticides and Degradates by HPLC-MS (NWQL pr ovisional method 9060)

2-Hydroxyatrazine 21 21(20) 100 0.483 0.970 1.044

Atrazine 21 21(4) 100 0.549 1.104 1.698

Deethylatrazine 21 21(15) 100 0.099 0.121 0.172

Deisopropylatrazine 21 21(20) 100 0.043 0.061 0.131

Fluometuron 21 21(2) 100 0.157 0.238 0.264

2,4-D 21 20(5) 95.2 0.085 0.140 0.180

Diuron 21 19(15) 90.5 0.045 0.101 0.139

Desethyl desisopropylatrazine 21 12(12) 57.1 0.006 0.019 0.027

2,4-D methyl ester 21 10(10) 47.6 --- 0.027 0.051

Metalaxyl 21 6(6) 28.6 --- 0.005 0.040

Norflurazon 21 5(5) 23.8 --- 0.005 0.011

Tebuthiuron 21 4(4) 19.0 --- 0.003 0.004

Dicamba 21 2(2) 9.5 --- --- 0.039

Imazethapyr 19 1(1) 5.3 --- --- 0.004

Bromacil 21 1(1) 4.8 --- --- 0.481

Caffeine* 21 1 4.8 --- --- 0.143

Siduron 21 1(1) 4.8 --- --- 0.003

* Caffeine is not a pesticide compound, however it is included in this method.
Summary of Results from a Pilot Monitoring Program 37

Table 17. Statistical summary of pesticides and degradates detected in water samples from the reservoiroutflow monitoring site at Lake Bruin, Louisiana

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Atrazine 4 4 100 0.972 1.000 1.000

Cyanazine 4 4 100 0.126 0.139 0.139

Deethylatrazine 4 4(4) 100 0.110 0.154 0.154

Metolachlor 4 4 100 0.028 0.032 0.032

Simazine 4 4 100 0.158 0.162 0.162

Chlorpyrifos 4 3 75.0 0.005 0.006 0.006

Trifluralin 4 2(2) 50.0 0.001 0.002 0.002

Prometon 4 1(1) 25.0 --- 0.003 0.003

Tebuthiuron 4 1(1) 25.0 --- 0.009 0.009

Analysis of Moderate-Use Pesticides and Degradates by GC-MS (NWQL provisional method 9002)

3,4-Dichloroaniline 3 3(2) 100 0.006 0.008 0.008

Prometryn 3 3 100 0.024 0.024 0.024

3-Trifluoromethylaniline 3 1(1) 33.3 --- 0.007 0.007

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

2,4-D 4 4 100 0.099 0.142 0.142

2-Hydroxyatrazine 4 4(4) 100 0.727 0.865 0.865

Atrazine 4 4(3) 100 0.934 1.243 1.243

Deethylatrazine 4 4(4) 100 0.096 0.147 0.147

Deisopropylatrazine 4 4(4) 100 0.060 0.070 0.070

Desethyl desisopropylatrazine 4 4(4) 100 0.008 0.015 0.015

Diuron 4 4(4) 100 0.041 0.060 0.060

Fluometuron 4 4 100 0.231 0.247 0.247

2,4-D methyl ester 4 3(3) 75.0 0.008 0.013 0.013

Metalaxyl 4 2(2) 50.0 0.001 0.004 0.004

Norflurazon 4 1(1) 25.0 --- 0.009 0.009
38 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

Table 18. Statistical summary of pesticides and degradates detected in water samples from the finishedwater monitoring site at Tensas Water Distribution Association, Inc., Louisiana

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Atrazine 21 21 100 0.733 0.832 0.851

Cyanazine 21 21 100 0.117 0.170 0.355

Deethylatrazine 21 21(21) 100 0.134 0.170 0.194

Simazine 21 21 100 0.102 0.138 0.173

Metolachlor 21 19(1) 90.5 0.011 0.023 0.027

Prometon 21 7(7) 33.3 --- 0.005 0.007

Tebuthiuron 21 5(5) 23.8 --- 0.004 0.008

Dacthal 21 1(1) 4.8 --- --- 0.004

Trifluralin 21 1(1) 4.8 --- --- 0.002

p,p'-DDE 21 1(1) 4.8 --- --- 0.001

Analysis of Moderate-Use Pesticides and Degradates by GC-MS (NWQL provisional method 9002)

Malaoxon 21 11(3) 52.4 0.008 0.128 0.556

4-Chloro -2-methylphenol 21 4(4) 19.0 --- 0.006 0.007

4,4'-Dichlorobenzophenone 21 2(2) 9.5 --- --- 0.003

Isofenphos 21 1(1) 4.8 --- --- 0.005

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

2-Hydroxyatrazine 22 22(22) 100 0.449 1.045 1.172

Atrazine 22 22(5) 100 0.389 0.699 0.840

2,4-D 22 21(10) 95.5 0.077 0.114 0.124

Deethylatrazine 22 20(20) 90.9 0.049 0.078 0.091

Deisopropylatrazine 22 18(17) 81.8 0.022 0.065 0.085

Fluometuron 22 18(16) 81.8 0.031 0.077 0.100

2,4-D methyl ester 22 14(14) 63.6 0.009 0.021 0.045

Desethyl desisopropylatrazine 22 11(11) 50.0 --- 0.018 0.028

Bromoxynil 22 3(3) 13.6 --- 0.012 0.021

Dicamba 22 2(2) 9.1 --- --- 0.042

Metalaxyl 22 2(2) 9.1 --- --- 0.005

Tebuthiuron 22 1(1) 4.5 --- --- 0.002
Summary of Results from a Pilot Monitoring Program 39

Table 19. Statistical summary of pesticides and degradates detected in water samples from the watersupply intake monitoring site at Higginsville Reservoir, Missouri

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Atrazine 40 40 100 2.600 5.880 11.600

Deethylatrazine 40 40(40) 100 0.410 0.624 0.771

Simazine 40 40(2) 100 0.199 0.634 0.769

Metolachlor 40 39 97.5 0.334 2.250 3.320

Prometon 40 37(26) 92.5 0.013 0.024 0.026

Alachlor 40 31(2) 77.5 0.012 0.394 0.655

Cyanazine 40 26(1) 65.0 0.008 0.021 0.024

Acetochlor 40 22 55.0 0.008 0.027 0.031

Diazinon 40 14 35.0 --- 0.011 0.022

Metribuzin 39 9 23.1 --- 0.083 0.291

2,6-Diethylaniline 40 1(1) 2.5 --- --- 0.001

Azinphos-methyl 40 1(1) 2.5 --- --- 0.034

Carbaryl 40 1(1) 2.5 --- --- 0.008

Chlorpyrifos 40 1 2.5 --- --- 0.034

Dacthal 40 1(1) 2.5 --- --- 0.002

Malathion 40 1 2.5 --- --- 0.007

Tebuthiuron 40 1(1) 2.5 --- --- 0.003

Terbacil 40 1(1) 2.5 --- --- 0.007

p,p'-DDE 40 1(1) 2.5 --- --- 0.003

Analysis of Moderate-Use Pesticides and Degradates by GC-MS (NWQL provisional method 9002)

Prometryn 38 12(12) 31.6 --- 0.004 0.005

2,5-Dichloroaniline 38 9(2) 23.7 --- 0.011 0.017

2-Chloro -2,6-diethylacetanilide 38 4 10.5 --- 0.010 0.012

Myclobutanil 38 2(1) 5.3 --- --- 0.015

4-(Hydro xymethyl)

pendimethalin 38 2(2) 5.3 --- --- 0.016

Tebupirimphos 38 2(2) 5.3 --- --- 0.007

1-Naphthol 38 1(1) 2.6 --- --- 0.228

2-[2-Ethyl-6-methylphenyl)

amino]-1-propanal 38 1(1) 2.6 --- --- 0.010

3,4-Dichloroaniline 38 1 2.6 --- --- 0.011

Fenamiphos sulfoxide 38 1(1) 2.6 --- --- 0.008

Methidathion (Supracide) 38 1 2.6 --- --- 0.010

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

2-Hydroxyatrazine 36 36(36) 100 1.010 1.612 2.058

Atrazine 36 36(34) 100 1.492 3.223 6.176

Deethylatrazine 36 35(14) 97.2 0.292 0.399 0.546

Deisopropylatrazine 36 35(17) 97.2 0.120 0.201 0.260

Metalaxyl 36 35(27) 97.2 0.033 0.077 0.104

Desethyl desisopropylatrazine 36 28(20) 77.8 0.039 0.088 0.092

2,4-D 36 23(18) 63.9 0.037 0.078 0.133

Caffeine* 36 16(6) 44.4 --- 0.179 0.435

* Caffeine is not a pesticide compound, however it is included in this method.
40 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

Table 19. Statistical summary of pesticides and degradates detected in water samples from the watersupply intake monitoring site at Higginsville Reservoir, Missouri—continued

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)--Continued

2,4-D methyl ester 36 7(7) 19.4 --- 0.018 0.041

Bentazon 36 4(4) 11.1 --- 0.003 0.008

Chlorimuron-ethyl 36 4(4) 11.1 --- 0.006 0.018

Dicamba 36 4(3) 11.1 --- 0.047 0.126

Flumetsulam 36 4(4) 11.1 --- 0.006 0.027

Acifluorfen 35 3(3) 8.6 --- --- 0.022

Imazaquin 36 1(1) 2.8 --- --- 0.012

MCPA 36 1 2.8 --- --- 0.061

Nicosulfuron 36 1(1) 2.8 --- --- 0.017

Propoxur 36 1(1) 2.8 --- --- 0.005

Tebuthiuron 36 1(1) 2.8 --- --- 0.027
Summary of Results from a Pilot Monitoring Program 41

Table 20. Statistical summary of pesticides and degradates detected in water samples from the reservoiroutflow monitoring site at Higginsville Reservoir, Missouri

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Alachlor 11 11(1) 100 0.182 0.482 0.643

Atrazine 11 11 100 3.140 5.690 6.200

Deethylatrazine 11 11(11) 100 0.429 0.728 0.754

Metolachlor 11 11 100 1.380 2.870 3.580

Prometon 11 10(4) 90.9 0.019 0.025 0.028

Simazine 11 10 90.9 0.397 0.603 0.805

Acetochlor 11 8 72.7 0.013 0.023 0.029

Cyanazine 11 8(1) 72.7 0.013 0.021 0.021

Diazinon 11 7 63.6 0.006 0.015 0.018

Metribuzin 10 4 40.0 --- 0.202 0.265

Tebuthiuron 11 1(1) 9.1 --- --- 0.002

Analysis of Moderate-Use Pesticides and Degradates by GC-MS (NWQL provisional method 9002)

2-Chloro -2,6-diethylacetanilide 9 3 33.3 --- 0.012 0.012

Terbuthylazine 8 1(1) 12.5 --- 1.500 1.500

3,4-Dichloroaniline 9 1 11.1 --- 0.070 0.070

Myclobutanil 9 1(1) 11.1 --- 0.006 0.006

Tebupirimphos 9 1(1) 11.1 --- 0.005 0.005

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

Atrazine 10 10(10) 100 2.408 3.904 4.068

Deethylatrazine 10 10(6) 100 0.235 0.460 0.577

Deisopropylatrazine 10 10(9) 100 0.114 0.201 0.258

2-Hydroxyatrazine 10 9(9) 90.0 1.276 1.951 2.175

Desethyl desisopropylatrazine 10 9(7) 90.0 0.040 0.301 0.514

Metalaxyl 10 9(7) 90.0 0.037 0.074 0.077

Caffeine* 10 7(5) 70.0 0.056 0.130 0.150

2,4-D 10 4(3) 40.0 --- 0.089 0.115

2,4-D methyl ester 10 2(2) 20.0 --- 0.011 0.013

Flumetsulam 10 2(2) 20.0 --- 0.021 0.029

Acifluorfen 9 1(1) 11.1 --- 0.029 0.029

Chlorimuron-ethyl 10 1(1) 10.0 --- 0.013 0.026

* Caffeine is not a pesticide compound, however it is included in this method.
42 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

Table 21. Statistical summary of pesticides and degradates detected in water samples from the finishedwater monitoring site at City of Higginsville Municipal Utilities, Missouri

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Atrazine 25 25 100 0.722 1.190 1.300

Deethylatrazine 25 25(25) 100 0.100 0.249 0.296

Metolachlor 25 25 100 0.063 0.453 0.514

Simazine 25 24 96.0 0.020 0.087 0.092

Prometon 25 19(19) 76.0 0.004 0.010 0.012

Alachlor 25 14(2) 56.0 0.004 0.051 0.056

Cyanazine 25 12(1) 48.0 --- 0.019 0.020

Acetochlor 25 10 40.0 --- 0.011 0.022

Carbaryl 25 1(1) 4.0 --- --- 0.004

Phorate 25 1(1) 4.0 --- --- 0.001

Analysis of Moderate-Use Pesticides and Degradates by GC-MS (NWQL provisional method 9002)

Azinphos-methyl-oxon 20 2(2) 10.0 --- 0.004 0.010

2-[2-Ethyl-6-methylphenyl)

amino]-1-propanal 20 1(1) 5.0 --- --- 0.005

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

Atrazine 25 25(5) 100 0.269 0.772 1.013

2-Hydroxyatrazine 25 24(24) 96.0 0.260 0.574 1.210

Deethylatrazine 25 24(23) 96.0 0.042 0.153 0.201

Deisopropylatrazine 25 21(21) 84.0 0.013 0.048 0.071

Metalaxyl 25 21(20) 84.0 0.012 0.042 0.072

Desethyl desisopropylatrazine 25 17(17) 68.0 0.014 0.029 0.036

2,4-D 25 9(8) 36.0 --- 0.035 0.131

Caffeine* 25 6(6) 24.0 --- 0.024 0.035

Dicamba 25 2(2) 8.0 --- --- 0.054

Imazethapyr 23 1(1) 4.3 --- --- 0.004

Benomyl 25 1(1) 4.0 --- --- 0.215

Bentazon 25 1(1) 4.0 --- --- 0.004

Chlorimuron-ethyl 25 1(1) 4.0 --- --- 0.009

Imazaquin 25 1(1) 4.0 --- --- 0.008

Oryzalin 25 1(1) 4.0 --- --- 0.012

* Caffeine is not a pesticide compound, however it is included in this method.
Summary of Results from a Pilot Monitoring Program 43

Table 22. Statistical summary of pesticides and degradates detected in water samples from the watersupply intake monitoring site at Tar River Reservoir, North Carolina

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Deethylatrazine 10 10(10) 100 0.006 0.009 0.010

Prometon 10 10(10) 100 0.010 0.014 0.015

Atrazine 10 9 90.0 0.020 0.042 0.043

Metolachlor 10 9 90.0 0.020 0.045 0.046

Simazine 10 8 80.0 0.012 0.019 0.022

Diazinon 10 5(2) 50.0 0.001 0.011 0.012

Carbaryl 10 1(1) 10.0 --- 0.002 0.004

Tebuthiuron 10 1 10.0 --- 0.006 0.011

Analysis of Moderate-Use Pesticides and Degradates by GC-MS (NWQL provisional method 9002)

Fenamiphos sulfone 10 1(1) 10.0 --- 0.002 0.005

Metalaxyl 10 1(1) 10.0 --- 0.003 0.005

Prometryn 10 1(1) 10.0 --- 0.002 0.004

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

2-Hydroxyatrazine 10 7(7) 70.0 0.043 0.102 0.110

Atrazine 10 6(6) 60.0 0.003 0.025 0.027

Bentazon 10 4(4) 40.0 --- 0.083 0.107

Caffeine* 10 4(4) 40.0 --- 0.046 0.057

Desethyl desisopropylatrazine 10 3(3) 30.0 --- 0.003 0.003

Fluometuron 10 3(3) 30.0 --- 0.012 0.017

Diuron 10 2(2) 20.0 --- 0.042 0.069

2,4-D 10 1(1) 10.0 --- 0.009 0.018

Chloramben methyl ester 10 1 10.0 --- 0.063 0.126

Picloram 10 1 10.0 --- 0.037 0.075

* Caffeine is not a pesticide compound, however it is included in this method.
44 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

Table 23. Statistical summary of pesticides and degradates detected in water samples from the reservoiroutflow monitoring site at Tar River Reservoir, North Carolina

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Atrazine 1 1 100 0.011 0.011 0.011

Deethylatrazine 1 1(1) 100 0.003 0.003 0.003

Metolachlor 1 1 100 0.009 0.009 0.009

Prometon 1 1(1) 100 0.011 0.011 0.011

Simazine 1 1 100 0.008 0.008 0.008

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

2-Hydroxyatrazine 1 1(1) 100 0.015 0.015 0.015

Atrazine 1 1(1) 100 0.008 0.008 0.008

Caffeine* 1 1(1) 100 0.014 0.014 0.014

* Caffeine is not a pesticide compound, however it is included in this method.
Summary of Results from a Pilot Monitoring Program 45

Table 24. Statistical summary of pesticides and degradates detected in water samples from the finishedwater monitoring site at Tar River Water Treatment Plant, North Carolina

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Prometon 10 10(10) 100 0.008 0.013 0.014

Atrazine 10 9 90.0 0.014 0.030 0.034

Deethylatrazine 10 9(9) 90.0 0.007 0.009 0.009

Metolachlor 10 9 90.0 0.012 0.016 0.016

Simazine 10 8(1) 80.0 0.008 0.016 0.018

Dacthal 10 1(1) 10.0 --- 0.001 0.002

Analysis of Moderate-Use Pesticides and Degradates by GC-MS (NWQL provisional method 9002)

Fenamiphos sulfone 10 2(1) 20.0 --- 0.011 0.016

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

2-Hydroxyatrazine 10 7(7) 70.0 0.048 0.091 0.101

Atrazine 10 6(6) 60.0 0.005 0.018 0.023

Desethyl desisopropylatrazine 10 5(5) 50.0 0.001 0.005 0.007

Metalaxyl 10 2(2) 20.0 --- 0.002 0.003

2,4-D 10 1(1) 10.0 --- 0.017 0.034

3-Hydroxycarbofuran 10 1(1) 10.0 --- 0.005 0.009

Caffeine* 10 1(1) 10.0 --- 0.015 0.031

Deethylatrazine 10 1(1) 10.0 --- 0.004 0.007

Deisopropylatrazine 10 1(1) 10.0 --- 0.002 0.005

Dicamba 10 1(1) 10.0 --- 0.005 0.011

Fluometuron 10 1(1) 10.0 --- 0.002 0.003

Neburon 10 1(1) 10.0 --- 0.001 0.002

Triclopyr 10 1(1) 10.0 --- 0.009 0.017

* Caffeine is not a pesticide compound, however it is included in this method.
46 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

Table 25. Statistical summary of pesticides and degradates detected in water samples from the watersupply intake monitoring site at LeRoy Reservoir, New York

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Atrazine 22 22 100 0.178 0.229 0.490

Deethylatrazine 22 22(22) 100 0.070 0.099 0.127

Metolachlor 22 22 100 0.093 0.243 0.442

Cyanazine 22 16(1) 72.7 0.014 0.049 0.079

Simazine 22 15(2) 68.2 0.005 0.008 0.008

EPTC 22 13(3) 59.1 0.003 0.014 0.037

Alachlor 22 9 40.9 --- 0.065 0.176

Prometon 22 7(7) 31.8 --- 0.007 0.008

Acetochlor 22 2 9.1 --- --- 0.009

2,6-Diethylaniline 22 1(1) 4.5 --- --- 0.002

Butylate 22 1(1) 4.5 --- --- 0.002

Analysis of Moderate-Use Pesticides and Degradates by GC-MS (NWQL provisional method 9002)

Disulfoton sulfone 20 1 5.0 --- --- 0.013

Disulfotone sulfoxide 20 1(1) 5.0 --- --- 0.006

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

2-Hydroxyatrazine 20 20(20) 100 0.299 0.767 1.083

Atrazine 20 20(10) 100 0.103 0.175 0.219

Deethylatrazine 20 20(20) 100 0.047 0.074 0.091

Metalaxyl 20 17(16) 85.0 0.026 0.050 0.072

Deisopropylatrazine 20 14(14) 70.0 0.013 0.031 0.041

Desethyl desisopropylatrazine 20 13(13) 65.0 0.018 0.043 0.052

Bentazon 20 9(9) 45.0 --- 0.120 0.344

2,4-D 20 3(3) 15.0 --- 0.026 0.031

Caffeine* 20 3(3) 15.0 --- 0.014 0.024

Imazaquin 20 3(3) 15.0 --- 0.008 0.022

Flumetsulam 20 2(2) 10.0 --- 0.012 0.088

2,4-D methyl ester 20 1(1) 5.0 --- --- 0.006

Aldicarb sulfone 20 1(1) 5.0 --- --- 0.007

Dicamba 20 1(1) 5.0 --- --- 0.031

MCPA 20 1(1) 5.0 --- --- 0.018

Metsulfuron-methyl 20 1 5.0 --- --- 0.148

Neburon 20 1(1) 5.0 --- --- 0.009

Oryzalin 20 1 5.0 --- --- 0.071

Picloram 20 1(1) 5.0 --- --- 1.441

* Caffeine is not a pesticide compound, however it is included in this method.
Summary of Results from a Pilot Monitoring Program 47

Table 26. Statistical summary of pesticides and degradates detected in water samples from the finishedwater monitoring site at Village of LeRoy Water Department, New York

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Atrazine 21 21 100 0.162 0.225 0.459

Deethylatrazine 21 21(21) 100 0.072 0.110 0.151

Metolachlor 21 21 100 0.093 0.222 0.410

Cyanazine 21 13 61.9 0.015 0.051 0.072

Alachlor 21 8 38.1 --- 0.055 0.148

Simazine 21 7(2) 33.3 --- 0.008 0.008

Prometon 21 2(2) 9.5 --- --- 0.008

Fonofos 20 1 5.0 --- --- 0.009

2,6-Diethylaniline 21 1(1) 4.8 --- --- 0.002

Acetochlor 21 1 4.8 --- --- 0.014

Analysis of Moderate-Use Pesticides and Degradates by GC-MS (NWQL provisional method 9002)

Azinphos-methyl-oxon 20 2(2) 10.0 --- 0.013 0.026

2,5-Dichloroaniline 20 1(1) 5.0 --- --- 0.004

3,5-Dichloroaniline 20 1 5.0 --- --- 0.009

Iprodione 20 1(1) 5.0 --- --- 0.023

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

2-Hydroxyatrazine 20 20(20) 100 0.303 0.913 1.175

Atrazine 20 20(10) 100 0.115 0.159 0.199

Deethylatrazine 20 20(20) 100 0.039 0.067 0.258

Metalaxyl 20 18(18) 90.0 0.022 0.047 0.055

Desethyl desisopropylatrazine 20 12(12) 60.0 0.013 0.037 0.043

Deisopropylatrazine 20 11(11) 55.0 0.011 0.037 0.059

Flumetsulam 20 3(3) 15.0 --- 0.028 0.037

Imazaquin 20 3(3) 15.0 --- 0.011 0.111

2,4-D 20 2(2) 10.0 --- 0.011 0.024

2,4-DB 20 2(2) 10.0 --- 0.003 0.011

Bentazon 20 2(2) 10.0 --- 0.004 0.011

Dichlorprop 20 1(1) 5.0 --- --- 0.018

Benomyl 20 1(1) 5.0 --- --- 0.005

Dicamba 20 1(1) 5.0 --- --- 0.018

Triclopyr 20 1(1) 5.0 --- --- 0.041
48 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

Table 27. Statistical summary of pesticides and degradates detected in water samples from the watersupply intake monitoring site at East Fork Lake, Ohio

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Acetochlor 21 21 100 0.031 0.136 0.284

Alachlor 21 21 100 0.014 0.053 0.105

Atrazine 21 21 100 0.230 3.240 3.860

Cyanazine 21 21 100 0.149 0.210 0.233

Deethylatrazine 21 21(21) 100 0.074 0.448 0.668

Metolachlor 21 21 100 0.294 0.682 1.010

Simazine 21 21 100 0.032 0.437 0.625

Metribuzin 21 19 90.5 0.012 0.042 0.095

Tebuthiuron 21 17(6) 81.0 0.011 0.015 0.015

Prometon 21 14(14) 66.7 0.007 0.013 0.013

Diazinon 21 10(1) 47.6 --- 0.013 0.015

Chlorpyrifos 21 2(2) 9.5 --- --- 0.004

Carbaryl 21 1(1) 4.8 --- --- 0.012

Analysis of Moderate-Use Pesticides and Degradates by GC-MS (NWQL provisional method 9002)

3,4-Dichloroaniline 21 5(5) 23.8 --- 0.004 0.005

2-[2-Ethyl-6-methylphenyl)amino]-1-propan 21 1(1) 4.8 --- --- 0.006

Metalaxyl 21 1(1) 4.8 --- --- 0.005

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

Atrazine 19 19(12) 100 0.154 1.888 2.718

Deethylatrazine 19 19(18) 100 0.038 0.381 0.458

Deisopropylatrazine 19 19(18) 100 0.024 0.225 0.269

2-Hydroxyatrazine 18 17(17) 94.4 0.334 0.543 1.636

Desethyl desisopropylatrazine 19 17(15) 89.5 0.030 0.071 0.134

Metalaxyl 19 14(13) 73.7 0.016 0.045 0.086

2,4-D 19 13(6) 68.4 0.076 0.120 0.139

Tebuthiuron 19 13(13) 68.4 0.006 0.010 0.011

Caffeine* 19 10(10) 52.6 0.020 0.035 0.047

Chlorimuron-ethyl 19 9(7) 47.4 --- 0.042 0.050

2,4-D methyl ester 19 8(8) 42.1 --- 0.016 0.030

Bentazon 19 7(7) 36.8 --- 0.042 0.079

Imazaquin 19 6(6) 31.6 --- 0.065 0.084

Imazethapyr 18 4(4) 22.2 --- 0.084 0.111

Diphenamid 19 3(3) 15.8 --- 0.026 0.038

Acifluorfen 18 2(2) 11.1 --- 0.013 0.015

Diuron 19 2(2) 10.5 --- 0.013 0.020

Picloram 19 1 5.3 --- --- 0.430

Terbacil 19 1(1) 5.3 --- --- 0.013

* Caffeine is not a pesticide compound, however it is included in this method.
Summary of Results from a Pilot Monitoring Program 49

Table 28. Statistical summary of pesticides and degradates detected in water samples from the reservoiroutflow monitoring site at East Fork Lake, Ohio

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Acetochlor 11 11 100 0.020 0.037 0.041

Alachlor 11 11(1) 100 0.011 0.033 0.129

Atrazine 11 11 100 0.389 0.465 2.390

Cyanazine 11 11 100 0.163 0.178 0.250

Deethylatrazine 11 11(11) 100 0.082 0.121 0.182

Metolachlor 11 11 100 0.238 0.449 0.689

Simazine 11 11 100 0.026 0.034 0.035

Tebuthiuron 11 9(3) 81.8 0.011 0.012 0.012

Prometon 11 6(6) 54.5 0.003 0.005 0.007

Metribuzin 11 3 27.3 --- 0.010 0.013

p,p'-DDE 11 2(2) 18.2 --- 0.001 0.002

Chlorpyrifos 11 1 9.1 --- --- 0.006

Analysis of Moderate-Use Pesticides and Degradates by GC-MS (NWQL provisional method 9002)

3,4-Dichloroaniline 10 1(1) 10.0 --- 0.002 0.003

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

Atrazine 11 11(6) 100 0.221 0.331 0.358

Deethylatrazine 11 11(11) 100 0.048 0.057 0.065

Desethyl desisopropylatrazine 11 10(10) 90.9 0.022 0.043 0.045

Metalaxyl 11 10(10) 90.9 0.012 0.023 0.027

2-Hydroxyatrazine 10 9(9) 90.0 0.428 0.584 0.598

2,4-D 11 9(9) 81.8 0.042 0.058 0.135

Deisopropylatrazine 11 9(9) 81.8 0.023 0.030 0.033

Tebuthiuron 11 7(7) 63.6 0.002 0.009 0.009

Caffeine* 11 6(6) 54.5 0.027 0.047 0.081

2,4-D methyl ester 11 5(5) 45.5 --- 0.023 0.033

Chlorimuron-ethyl 11 4(4) 36.4 --- 0.020 0.021

Bentazon 11 3(3) 27.3 --- 0.007 0.010

Acifluorfen 10 2(2) 20.0 --- 0.003 0.003

Dinoseb 11 1(1) 9.1 --- --- 0.001

Imazaquin 11 1(1) 9.1 --- --- 0.010

* Caffeine is not a pesticide compound, however it is included in this method.
50 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

Table 29. Statistical summary of pestic ides and degradates detected in water samples from the finishedwater monitoring site at Clermont Water Authority, Ohio

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Atrazine 21 20(2) 95.2 0.095 0.166 0.208

Metolachlor 21 20 95.2 0.041 0.238 0.384

Deethylatrazine 21 18(18) 85.7 0.017 0.061 0.078

Acetochlor 21 15 71.4 0.016 0.032 0.045

Alachlor 21 14(1) 66.7 0.006 0.013 0.027

Simazine 21 14(1) 66.7 0.010 0.020 0.024

Cyanazine 21 10 47.6 --- 0.135 0.211

Prometon 21 5(5) 23.8 --- 0.003 0.007

Tebuthiuron 21 5(5) 23.8 --- 0.009 0.009

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

2-Hydroxyatrazine 19 16(16) 84.2 0.059 0.404 0.463

Atrazine 20 16(13) 80.0 0.045 0.123 0.160

Desethyl desisopropylatrazine 20 16(16) 80.0 0.014 0.022 0.030

Deethylatrazine 19 13(13) 68.4 0.008 0.044 0.053

Metalaxyl 20 13(13) 65.0 0.009 0.024 0.025

Deisopropylatrazine 20 8(8) 40.0 --- 0.021 0.032

2,4-D 20 5(4) 25.0 --- 0.056 0.089

Imazaquin 20 5(5) 25.0 --- 0.012 0.014

Caffeine* 20 4(4) 20.0 --- 0.021 0.041

Tebuthiuron 20 3(3) 15.0 --- 0.004 0.006

Imazethapyr 19 2(2) 10.5 --- 0.036 0.038

Acifluorfen 19 1(1) 5.3 --- --- 0.016

2,4-D methyl ester 20 1(1) 5.0 --- --- 0.009

Bentazon 20 1(1) 5.0 --- --- 0.009

Dicamba 20 1(1) 5.0 --- --- 0.025

* Caffeine is not a pesticide compound, however it is included in this method.
Summary of Results from a Pilot Monitoring Program 51

Table 30. Statistical summary of pesticides and degradates detected in water samples from the watersupply intake monitoring site at Lake Arcadia, Oklahoma

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Atrazine 41 41 100 0.286 0.595 0.745

Deethylatrazine 41 41(41) 100 0.046 0.067 0.095

Prometon 41 41 100 0.086 0.113 0.138

Simazine 41 41 100 0.971 1.300 1.520

Diazinon 41 40 97.6 0.051 0.080 0.101

Metolachlor 41 40(2) 97.6 0.012 0.029 0.039

Pronamide 41 34 82.9 0.023 0.038 0.048

Tebuthiuron 41 33(5) 80.5 0.017 0.023 0.024

Dacthal 41 7(7) 17.1 --- 0.002 0.004

Terbacil 41 4(4) 9.8 --- --- 0.024

Chlorpyrifos 41 2(1) 4.9 --- --- 0.004

Benfluralin 41 1(1) 2.4 --- --- 0.001

p,p'-DDE 41 1(1) 2.4 --- --- 0.002

Analysis of Moderate-Use Pesticides and Degradates by GC-MS (NWQL provisional method 9002)

3,4-Dichloroaniline 41 31 75.6 0.013 0.022 0.034

2-[2-Ethyl-6-methylphenyl)

amino]-1-propanal 41 6(4) 14.6 --- 0.011 0.037

1,4-Naphthoquinone 41 1(1) 2.4 --- --- 0.005

4-Chloro -2-methylphenol 41 1(1) 2.4 --- --- 0.003

Azinphos-methyl-oxon 41 1 2.4 --- --- 0.263

Isofenphos 41 1(1) 2.4 --- --- 0.007

Metalaxyl 41 1(1) 2.4 --- --- 0.005

Myclobutanil 41 1(1) 2.4 --- --- 0.006

Prometryn 41 1(1) 2.4 --- --- 0.003

Tefluthrin metabolite [R 119364] 41 1(1) 2.4 --- --- 0.004

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

2-Hydroxyatrazine 39 39(39) 100 0.099 0.321 0.357

Atrazine 39 39(8) 100 0.199 0.519 0.618

Deisopropylatrazine 39 39(27) 100 0.133 0.223 0.386

Deethylatrazine 39 38(38) 97.4 0.029 0.038 0.051

Diuron 39 38(2) 97.4 0.278 0.379 0.435

Caffeine* 39 35(24) 89.7 0.073 0.102 0.133

2,4-D 39 34(19) 87.2 0.073 0.098 0.154

Tebuthiuron 39 34(34) 87.2 0.008 0.013 0.015

Bromacil 39 28(26) 71.8 0.043 0.084 0.136

Sulfometuron-methyl 39 28(16) 71.8 0.033 0.126 0.160

Desethyl desisopropylatrazine 39 27(22) 69.2 0.034 0.077 0.114

Dicamba 39 22(17) 56.4 0.037 0.105 0.192

Benomyl 39 14(13) 35.9 --- 0.031 0.038

2,4-D methyl ester 39 8(8) 20.5 --- 0.016 0.041

Metalaxyl 39 6(6) 15.4 --- 0.003 0.351

* Caffeine is not a pesticide compound, however it is included in this method.
52 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

Table 30. Statistical summary of pesticides and degradates detected in water samples from the watersupply intake monitoring site at Lake Arcadia, Oklahoma—continued.

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)--continued

Dichlorprop 39 2(2) 5.1 --- --- 0.036

Bentazon 39 2(2) 5.1 --- --- 0.011

Imazethapyr 38 1(1) 2.6 --- --- 0.103

Clopyralid 39 1(1) 2.6 --- --- 0.024

MCPA 39 1(1) 2.6 --- --- 0.004

Metsulfuron-methyl 39 1(1) 2.6 --- --- 1.194

Triclopyr 39 1(1) 2.6 --- --- 0.017
Summary of Results from a Pilot Monitoring Program 53

Table 31. Statistical summary of pesticides and degradates detected in water samples from the reservoiroutflow monitoring site at Lake Arcadia, Oklahoma

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Atrazine 10 10 100 0.299 0.659 0.687

Deethylatrazine 10 10(10) 100 0.032 0.056 0.059

Prometon 10 10(3) 100 0.060 0.104 0.107

Simazine 10 10 100 0.629 1.500 1.580

Metolachlor 10 8 80.0 0.014 0.034 0.038

Tebuthiuron 10 8(3) 80.0 0.012 0.022 0.024

Diazinon 10 7(2) 70.0 0.027 0.096 0.111

Pronamide 10 6 60.0 0.016 0.040 0.045

p,p'-DDE 10 2(2) 20.0 --- 0.002 0.002

Analysis of Moderate-Use Pesticides and Degradates by GC-MS (NWQL provisional method 9002)

3,4-Dichloroaniline 10 5(1) 50.0 0.003 0.029 0.031

Azinphos-methyl-oxon 10 1 10.0 --- 0.150 0.300

Metalaxyl 10 1(1) 10.0 --- 0.003 0.005

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

Atrazine 10 10(6) 100 0.174 0.600 0.659

Deisopropylatrazine 10 10(8) 100 0.048 0.155 0.156

2-Hydroxyatrazine 10 9(9) 90.0 0.164 0.315 0.346

Desethyl desisopropylatrazine 10 9(9) 90.0 0.013 0.037 0.038

Deethylatrazine 10 8(8) 80.0 0.013 0.036 0.037

Diuron 10 8(3) 80.0 0.141 0.425 0.448

Tebuthiuron 10 6(6) 60.0 0.004 0.013 0.015

Bromacil 10 5(5) 50.0 0.016 0.069 0.072

Caffeine* 10 5(2) 50.0 0.025 0.220 0.329

Sulfometuron-methyl 10 5(1) 50.0 0.045 0.162 0.194

Dicamba 10 3(3) 30.0 --- 0.065 0.067

Terbacil 10 2(2) 20.0 --- 0.046 0.051

2,4-D 10 1(1) 10.0 --- 0.033 0.065

2,4-DB 10 1 10.0 --- 0.027 0.054

Benomyl 10 1(1) 10.0 --- 0.014 0.027

Metalaxyl 10 1(1) 10.0 --- 0.001 0.002

* Caffeine is not a pesticide compound, however it is included in this method.
54 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

Table 32. Statistical summary of pesticides and degradates detected in water samples from the finishedwater monitoring site at Edmonds Water Supply, Oklahoma

[Concentrations shown in micrograms per liter; --- indicates value reported as less than t he method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Atrazine 19 19 100 0.269 0.346 0.385

Deethylatrazine 19 19(19) 100 0.040 0.062 0.062

Prometon 19 19 100 0.072 0.084 0.103

Simazine 19 19 100 0.395 0.463 0.571

Metolachlor 19 18 94.7 0.007 0.010 0.012

Tebuthiuron 19 18(2) 94.7 0.022 0.031 0.032

Pronamide 19 8 42.1 --- 0.012 0.017

Dacthal 19 4(4) 21.1 --- 0.002 0.003

Trifluralin 19 1 5.3 --- --- 0.005

p,p'-DDE 19 1(1) 5.3 --- --- 0.002

Analysis of Moderate-Use Pesticides and Degradates by GC-MS (NWQL provisional method 9002)

2-[2-Ethyl-6-methylphenyl)amino]-

1-propanol 19 4(4) 21.1 --- 0.005 0.014

Metalaxyl 19 1(1) 5.3 --- --- 0.004

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

Atrazine 19 19(7) 100 0.163 0.337 0.416

2-Hydroxyatrazine 19 17(17) 89.5 0.060 0.308 0.345

Tebuthiuron 19 17(17) 89.5 0.010 0.017 0.018

Deisopropylatrazine 19 15(9) 78.9 0.053 0.137 0.178

Deethylatrazine 19 14(14) 73.7 0.012 0.023 0.037

2,4-D 19 12(12) 63.2 0.026 0.044 0.054

Desethyl desisopropylatrazine 19 11(11) 57.9 0.004 0.035 0.039

Dicamba 19 8(8) 42.1 --- 0.049 0.063

Sulfometuron-methyl 19 6(6) 31.6 --- 0.008 0.024

Oxamyl oxime 19 2(2) 10.5 --- 0.013 0.014

Triclopyr 19 2(2) 10.5 --- 0.012 0.013

Bendiocarb 19 1(1) 5.3 --- --- 0.004

Caffeine* 19 1(1) 5.3 --- --- 0.009

Clopyralid 19 1(1) 5.3 --- --- 0.027

* Caffeine is not a pesticide compound, however it is included in this method.
Summary of Results from a Pilot Monitoring Program 55

Table 33. Statistical summary of pesticides and degradates detected in water samples from the watersupply intake monitoring site at Blue Marsh Reservoir, Tulpehocken Creek, Pennsylvania

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Atrazine 23 23 100 0.094 0.761 1.600

Deethylatrazine 23 23(23) 100 0.104 0.197 0.255

Metolachlor 23 23 100 0.025 0.268 0.520

Simazine 23 22 95.7 0.036 0.092 0.123

Prometon 23 21(21) 91.3 0.009 0.015 0.017

Tebuthiuron 23 11(11) 47.8 --- 0.007 0.009

Acetochlor 23 10 43.5 --- 0.036 0.048

Alachlor 23 10(1) 43.5 --- 0.011 0.021

Cyanazine 23 9(1) 39.1 --- 0.026 0.037

Diazinon 23 7(1) 30.4 --- 0.007 0.015

Pendimethalin 23 6 26.1 --- 0.022 0.125

Chlorpyrifos 23 5(2) 21.7 --- 0.004 0.012

Carbaryl 23 4(4) 17.4 --- 0.008 0.047

Trifluralin 23 3(3) 13.0 --- 0.001 0.002

p,p'-DDE 23 3(3) 13.0 --- 0.002 0.002

Carbofuran 23 2(2) 8.7 --- --- 0.019

Dacthal 23 1(1) 4.3 --- --- 0.003

EPTC 23 1(1) 4.3 --- --- 0.002

Linuron 23 1 4.3 --- --- 0.010

Napropamide 23 1(1) 4.3 --- --- 0.003

Analysis of Moderate-Use Pesticides and Degradates by GC-MS (NWQL provisional method 9002)

Dimethoate 24 3(1) 12.5 --- 0.006 0.022

Endosulfan sulfate 24 3(2) 12.5 --- 0.005 0.009

Tefluthrin metabolite [R 152912] 24 2(1) 8.3 --- --- 0.021

1,4-Naphthoquinone 24 1(1) 4.2 --- --- 0.004

1-Naphthol 24 1(1) 4.2 --- --- 0.006

2-[2-Ethyl-6-methylphenyl)

amino]-1-propanal 24 1(1) 4.2 --- --- 0.006

3,4-Dichloroaniline 24 1(1) 4.2 --- --- 0.004

Hexazinone 24 1(1) 4.2 --- --- 0.005

Tefluthrin 24 1(1) 4.2 --- --- 0.003

Tefluthrin metabolite [R 119364] 24 1(1) 4.2 --- --- 0.005

Tebupirimphos 24 1(1) 4.2 --- --- 0.006

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

Deethylatrazine 24 24(24) 100 0.063 0.120 0.228

Atrazine 24 23(14) 95.8 0.063 0.553 1.253

2-Hydroxyatrazine 24 22(22) 91.7 0.073 0.206 0.295

Desethyl desisopropylatrazine 24 22(13) 91.7 0.047 0.079 0.102

Caffeine* 24 15(14) 62.5 0.035 0.074 0.085

Deisopropylatrazine 24 14(14) 58.3 0.011 0.033 0.118

Bentazon 24 8(8) 33.3 --- 0.008 0.013

Bromacil 24 7(7) 29.2 --- 0.012 0.014

* Caffeine is not a pesticide compound, however it is included in this method.
56 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

Table 33. Statistical summary of pesticides and degradates detected in water samples from the 

water-supply intake monitoring site at Blue Marsh Reservoir, Tulpehocken Creek, Pennsylvania—

continued

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)--continued

2,4-D 24 5(5) 20.8 --- 0.026 0.056

Benomyl 24 5(5) 20.8 --- 0.016 0.030

Dicamba 24 4(4) 16.7 --- 0.045 0.094

Metalaxyl 24 4(4) 16.7 --- 0.007 0.014

Diuron 24 3(3) 12.5 --- 0.003 0.041

Imazethapyr 21 2(2) 9.5 --- --- 0.041

Imazaquin 23 2(2) 8.7 --- --- 0.351

Carbofuran 24 2(2) 8.3 --- --- 0.010

Tebuthiuron 24 2(2) 8.3 --- --- 0.005

Carbaryl 24 1(1) 4.2 --- --- 0.005

Dinoseb 24 1(1) 4.2 --- --- 0.003

Nicosulfuron 24 1(1) 4.2 --- --- 0.022

Oryzalin 24 1 4.2 --- --- 0.071
Summary of Results from a Pilot Monitoring Program 57

Table 34. Statistical summary of pesticides and degradates detected in water samples from the finishedwater monitoring site at Western Berks Water Authority, Pennsylvania

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Atrazine 23 23 100 0.056 0.470 0.740

Deethylatrazine 23 23(23) 100 0.069 0.119 0.200

Metolachlor 23 23 100 0.015 0.155 0.245

Simazine 23 22(1) 95.7 0.016 0.039 0.056

Prometon 23 21(21) 91.3 0.008 0.012 0.012

Acetochlor 23 9(1) 39.1 --- 0.016 0.025

Alachlor 23 8(1) 34.8 --- 0.008 0.010

Cyanazine 23 7(1) 30.4 --- 0.014 0.019

Tebuthiuron 23 7(7) 30.4 --- 0.005 0.005

Carbofuran 23 3(3) 13.0 --- 0.008 0.010

Pendimethalin 23 3 13.0 --- 0.006 0.009

p,p'-DDE 23 2(2) 8.7 --- --- 0.002

Carbaryl 23 1(1) 4.3 --- --- 0.003

EPTC 23 1(1) 4.3 --- --- 0.001

Trifluralin 23 1(1) 4.3 --- --- 0.001

Analysis of Moderate-Use Pesticides and Degradates by GC-MS (NWQL provisional method 9002)

Endosulfan sulfate 24 2(2) 8.3 --- --- 0.005

Terbufos-O-analogue sulfone 24 2(2) 8.3 --- --- 0.015

1,4-Naphthoquinone 24 1(1) 4.2 --- --- 0.003

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

Atrazine 23 23(16) 100 0.034 0.271 0.588

Deethylatrazine 23 23(23) 100 0.035 0.079 0.138

Desethyl desisopropylatrazine 23 22(22) 95.7 0.031 0.046 0.055

2-Hydroxyatrazine 23 20(20) 87.0 0.044 0.099 0.200

Deisopropylatrazine 23 13(13) 56.5 0.003 0.020 0.042

Caffeine* 23 8(8) 34.8 --- 0.023 0.071

Bentazon 23 5(5) 21.7 --- 0.005 0.011

Metalaxyl 23 4(4) 17.4 --- 0.005 0.007

2,4-D 23 3(3) 13.0 --- 0.019 0.035

Dicamba 23 3(3) 13.0 --- 0.019 0.055

Bromacil 23 1(1) 4.3 --- --- 0.481

Carbofuran 23 1(1) 4.3 --- --- 0.004

Dinoseb 23 1(1) 4.3 --- --- 0.002

Metsulfuron-methyl 23 1(1) 4.3 --- --- 0.030

Propiconazole 23 1(1) 4.3 --- --- 0.001

Tebuthiuron 23 1(1) 4.3 --- --- 0.003

* Caffeine is not a pesticide compound, however it is included in this method.
58 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

Table 35. Statistical summary of pesticides and degradates detected in water samples from the watersupply intake monitoring site at South Pacolet Reservoir, South Carolina

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Simazine 45 45 100 0.030 0.051 0.059

Atrazine 45 38(6) 84.4 0.005 0.008 0.010

Tebuthiuron 45 24(23) 53.3 0.003 0.008 0.008

Prometon 45 23(23) 51.1 0.002 0.005 0.013

Deethylatrazine 45 19(19) 42.2 --- 0.004 0.005

Metolachlor 45 19(9) 42.2 --- 0.005 0.006

Azinphos-methyl 43 7(7) 16.3 --- 0.054 0.144

Diazinon 45 5(5) 11.1 --- 0.001 0.003

Chlorpyrifos 45 4(4) 8.9 --- --- 0.002

p,p'-DDE 45 3(3) 6.7 --- --- 0.002

Dacthal 45 2(2) 4.4 --- --- 0.001

Dieldrin 45 1(1) 2.2 --- --- 0.002

Molinate 45 1(1) 2.2 --- --- 0.002

Analysis of Moderate-Use Pesticides and Degradates by GC-MS (NWQL provisional method 9002)

1,4-Naphthoquinone 44 1(1) 2.3 --- --- 0.002

1-Naphthol 44 1(1) 2.3 --- --- 0.008

Hexazinone 44 1(1) 2.3 --- --- 0.007

Metalaxyl 44 1(1) 2.3 --- --- 0.011

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

Deisopropylatrazine 44 20(20) 45.5 --- 0.011 0.016

Tebuthiuron 44 19(19) 43.2 --- 0.005 0.007

Desethyl desisopropylatrazine 44 16(16) 36.4 --- 0.007 0.047

Bentazon 44 12(12) 27.3 --- 0.007 0.013

2,4-D 44 10(10) 22.7 --- 0.029 0.078

Atrazine 44 10(10) 22.7 --- 0.003 0.021

Diuron 44 7(7) 15.9 --- 0.007 0.068

Caffeine* 44 5(4) 11.4 --- 0.005 88.000

2-Hydroxyatrazine 44 4(4) 9.1 --- --- 0.041

Metalaxyl 44 2(2) 4.5 --- --- 0.015

Benomyl 43 1(1) 2.3 --- --- 0.006

Dichlorprop 44 1(1) 2.3 --- --- 0.021

2,4-D methyl ester 44 1(1) 2.3 --- --- 0.016

Carbaryl 44 1(1) 2.3 --- --- 0.006

Deethylatrazine 44 1(1) 2.3 --- --- 0.008

Dicamba 44 1(1) 2.3 --- --- 0.049

Dinoseb 44 1(1) 2.3 --- --- 0.003

Imidacloprid 44 1(1) 2.3 --- --- 0.030

Metsulfuron-methyl 44 1(1) 2.3 --- --- 0.168

Propiconazole 44 1(1) 2.3 --- --- 0.004

Siduron 44 1(1) 2.3 --- --- 0.007

Triclopyr 44 1(1) 2.3 --- --- 0.087

* Caffeine is not a pesticide compound, however it is included in this method.
Summary of Results from a Pilot Monitoring Program 59

Table 36. Statistical summary of pesticides and degradates detected in water samples from the reservoiroutflow monitoring site at South Pacolet Reservoir, South Carolina

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Simazine 16 16 100 0.041 0.047 0.047

Atrazine 16 13(3) 81.3 0.005 0.006 0.007

Tebuthiuron 16 9(9) 56.3 0.006 0.009 0.010

Deethylatrazine 16 8(8) 50.0 --- 0.003 0.004

Metolachlor 16 5(2) 31.3 --- 0.005 0.005

Prometon 16 3(3) 18.8 --- 0.004 0.005

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

Desethyl desisopropylatrazine 15 9(9) 60.0 0.002 0.005 0.006

Tebuthiuron 15 6(6) 40.0 --- 0.005 0.006

Caffeine* 15 3(3) 20.0 --- 0.015 0.016

Deisopropylatrazine 15 3(3) 20.0 --- 0.009 0.010

Bentazon 15 2(2) 13.3 --- 0.002 0.005

2-Hydroxyatrazine 15 1(1) 6.7 --- --- 0.009

Atrazine 15 1(1) 6.7 --- --- 0.002

Bendiocarb 15 1(1) 6.7 --- --- 0.001

Diuron 15 1(1) 6.7 --- --- 0.011

Metsulfuron-methyl 15 1(1) 6.7 --- --- 0.003

Terbacil 15 1(1) 6.7 --- --- 0.021

* Caffeine is not a pesticide compound, however it is included in this method.
60 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

Table 37. Statistical summary of pesticides and degradates detected in water samples from the finishedwater monitoring site at Spartanburg Waterworks, South Carolina

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Simazine 27 27 100 0.027 0.039 0.051

Atrazine 27 23(8) 85.2 0.004 0.007 0.008

Deethylatrazine 27 14(14) 51.9 0.001 0.003 0.004

Tebuthiuron 27 11(11) 40.7 --- 0.006 0.008

Metolachlor 27 9(3) 33.3 --- 0.005 0.005

Prometon 27 7(7) 25.9 --- 0.003 0.004

Azinphos-methyl 25 5(5) 20.0 --- 0.038 0.114

p,p'-DDE 27 2(2) 7.4 --- --- 0.002

Pronamide 27 1(1) 3.7 --- --- 0.003

Analysis of Moderate-Use Pesticides and Degradates by GC-MS (NWQL provisional method 9002)

2-[2-Ethyl-6-methylphenyl)amino]-

1-propanol 26 1(1) 3.8 --- --- 0.007

Bifenthrin 26 1(1) 3.8 --- --- 0.002

Metalaxyl 26 1(1) 3.8 --- --- 0.009

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

Deisopropylatrazine 26 9(9) 34.6 --- 0.010 0.013

Desethyl desisopropylatrazine 26 8(8) 30.8 --- 0.018 0.036

Tebuthiuron 26 8(8) 30.8 --- 0.004 0.005

Bentazon 26 4(4) 15.4 --- 0.005 0.010

Atrazine 26 3(3) 11.5 --- 0.002 0.003

2,4-D 26 2(2) 7.7 --- --- 0.021

2-Hydroxyatrazine 26 2(2) 7.7 --- --- 0.007

Bromacil 26 1(1) 3.8 --- --- 0.013

Dicamba 26 1(1) 3.8 --- --- 0.016

Diuron 26 1(1) 3.8 --- --- 0.008

Metalaxyl 26 1(1) 3.8 --- --- 0.004

Oryzalin 26 1(1) 3.8 --- --- 0.037
Summary of Results from a Pilot Monitoring Program 61

Table 38. Statistical summary of pesticides and degradates detected in water samples from the watersupply intake monitoring site at Lake Mitchell, South Dakota

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Atrazine 21 21 100 1.320 2.310 2.530

Cyanazine 21 21(1) 100 0.025 0.035 0.038

Deethylatrazine 21 21(21) 100 0.273 0.363 0.444

Metolachlor 21 21 100 0.025 0.061 0.079

Prometon 21 21(21) 100 0.010 0.012 0.015

Acetochlor 21 19 90.5 0.030 0.249 0.334

Simazine 21 15(2) 71.4 0.007 0.014 0.016

EPTC 21 10 47.6 --- 0.030 0.036

Alachlor 21 3 14.3 --- 0.011 0.013

Tebuthiuron 21 2(2) 9.5 --- --- 0.004

Trifluralin 21 2(2) 9.5 --- --- 0.002

Analysis of Moderate-Use Pesticides and Degradates by GC-MS (NWQL provisional method 9002)

4-(Hydroxymethyl)pendimethalin 21 1(1) 4.8 --- --- 0.045

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

2-Hydroxyatrazine 21 21(21) 100 0.725 1.350 1.664

Atrazine 21 21(12) 100 1.098 1.745 2.508

Deethylatrazine 21 21(10) 100 0.199 0.259 0.302

Deisopropylatrazine 21 21(14) 100 0.073 0.108 0.160

2,4-D 21 17(6) 81.0 0.082 0.102 0.414

Desethyl desisopropylatrazine 21 14(11) 66.7 0.027 0.062 0.074

Picloram 21 8 38.1 --- 0.259 0.360

Nicosulfuron 21 7(7) 33.3 --- 0.086 0.139

2,4-D methyl ester 21 6(6) 28.6 --- 0.011 0.054

Dicamba 21 4(3) 19.0 --- 0.030 0.104

Metalaxyl 21 4(4) 19.0 --- 0.007 0.008

Imazethapyr 19 2(2) 10.5 --- 0.071 0.133

Bentazon 21 1(1) 4.8 --- --- 0.015

Caffeine* 21 1(1) 4.8 --- --- 0.019

Chlorimuron-ethyl 21 1(1) 4.8 --- --- 0.021

Diuron 21 1(1) 4.8 --- --- 0.010

Oryzalin 21 1 4.8 --- --- 0.127

Tebuthiuron 21 1(1) 4.8 --- --- 0.008

* Caffeine is not a pesticide compound, however it is included in this method.
62 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

Table 39. Statistical summary of pesticides and degradates detected in water samples from the reservoiroutflow monitoring site at Lake Mitchell, South Dakota

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Acetochlor 9 9 100 0.102 0.395 0.395

Atrazine 9 9 100 1.720 2.660 2.660

Cyanazine 9 9 100 0.032 0.065 0.065

Deethylatrazine 9 9(9) 100 0.151 0.395 0.395

Metolachlor 9 9 100 0.039 0.083 0.083

Prometon 9 9(9) 100 0.010 0.018 0.018

Simazine 9 9 100 0.013 0.016 0.016

Alachlor 9 4 44.4 --- 0.017 0.017

EPTC 9 4 44.4 --- 0.038 0.038

Trifluralin 9 2(2) 22.2 --- 0.003 0.003

Carbaryl 9 1(1) 11.1 --- 0.001 0.001

Tebuthiuron 9 1(1) 11.1 --- 0.006 0.006

Analysis of Moderate-Use Pesticides and Degradates by GC-MS (NWQL provisional method 9002)

2,5-Dichloroaniline 9 1(1) 11.1 --- 0.005 0.005

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

2-Hydroxyatrazine 9 9(9) 100 0.999 1.913 1.913

Atrazine 9 9(8) 100 1.466 1.821 1.821

Deethylatrazine 9 9(3) 100 0.129 0.237 0.237

Deisopropylatrazine 9 9(6) 100 0.058 0.089 0.089

2,4-D 9 8(3) 88.9 0.095 0.702 0.702

Desethyl desisopropylatrazine 9 7(7) 77.8 0.024 0.058 0.058

2,4-D methyl ester 9 4(4) 44.4 --- 0.077 0.077

Nicosulfuron 9 3(3) 33.3 --- 0.128 0.128

Imazethapyr 8 1(1) 12.5 --- 0.027 0.027

Chlorimuron-ethyl 9 1(1) 11.1 --- 0.023 0.023

Diuron 9 1(1) 11.1 --- 0.011 0.011

Metalaxyl 9 1(1) 11.1 --- 0.007 0.007
Summary of Results from a Pilot Monitoring Program 63

Table 40. Statistical summary of pesticides and degradates detected in water samples from the finishedwater monitoring site at Mitchell Water Department, South Dakota

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Atrazine 22 22 100 1.165 2.110 2.470

Cyanazine 22 22(1) 100 0.024 0.038 0.051

Deethylatrazine 22 22(22) 100 0.244 0.328 0.352

Metolachlor 22 22 100 0.024 0.058 0.072

Prometon 22 22(22) 100 0.010 0.013 0.017

Acetochlor 22 21 95.5 0.027 0.289 0.395

Simazine 22 15(2) 68.2 0.006 0.012 0.014

EPTC 22 11 50.0 0.002 0.019 0.029

Alachlor 22 4 18.2 --- 0.009 0.011

Tebuthiuron 22 3(3) 13.6 --- 0.002 0.004

Trifluralin 22 2(2) 9.1 --- --- 0.002

Analysis of Moderate-Use Pesticides and Degradates by GC-MS (NWQL provisional method 9002)

2,5-Dichloroaniline 21 1 4.8 --- --- 0.009

4-(Hydroxymethyl)pendimethalin 21 1(1) 4.8 --- --- 0.029

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

2-Hydroxyatrazine 22 22(22) 100 0.765 1.344 1.785

Atrazine 22 22(11) 100 1.032 1.728 1.944

Deethylatrazine 22 22(11) 100 0.172 0.206 0.267

Deisopropylatrazine 22 22(20) 100 0.055 0.071 0.141

2,4-D 22 19(11) 86.4 0.070 0.337 0.634

2,4-D methyl ester 22 13(12) 59.1 0.008 0.055 0.136

Desethyl desisopropylatrazine 22 13(12) 59.1 0.018 0.054 0.069

Picloram 22 11(1) 50.0 0.047 0.276 0.389

Nicosulfuron 22 8(8) 36.4 --- 0.074 0.093

Dicamba 22 4(3) 18.2 --- 0.046 0.147

Chlorimuron-ethyl 22 2(2) 9.1 --- --- 0.026

Diuron 22 2(2) 9.1 --- --- 0.029

Metalaxyl 22 2(2) 9.1 --- --- 0.010

Bentazon 22 1(1) 4.5 --- --- 0.015

Oryzalin 22 1 4.5 --- --- 0.095
64 Pesticides in Selected Water-Supply Reservoirs and Finished Drinking Water, 1999-2000:

Table 41. Statistical summary of pesticides and degradates detected in water samples from the watersupply intake monitoring site at Lake Waxahachie, Texas

[Concentrations shown in micrograms per liter; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Atrazine 22 22 100 0.531 0.577 0.612

Deethylatrazine 22 22(22) 100 0.104 0.128 0.137

Metolachlor 22 22 100 0.045 0.066 0.078

Simazine 22 18 81.8 0.016 0.018 0.021

Tebuthiuron 22 10(10) 45.5 --- 0.006 0.008

Diazinon 22 6(5) 27.3 --- 0.004 0.004

Prometon 22 6(6) 27.3 --- 0.006 0.008

p,p'-DDE 22 6(6) 27.3 --- 0.002 0.003

Alachlor 22 1(1) 4.5 --- --- 0.004

Analysis of Moderate-Use Pesticides and Degradates by GC-MS (NWQL provisional method 9002)

Prometryn 22 17(9) 77.3 0.006 0.010 0.013

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

Atrazine 22 22(5) 100 0.359 0.533 0.741

Deethylatrazine 22 22(22) 100 0.052 0.073 0.098

2-Hydroxyatrazine 22 19(19) 86.4 0.425 0.549 0.714

Deisopropylatrazine 22 19(19) 86.4 0.010 0.024 0.038

Desethyl desisopropylatrazine 22 17(17) 77.3 0.007 0.014 0.016

2,4-D 22 11(10) 50.0 0.009 0.074 0.079

Caffeine* 22 5(5) 22.7 --- 0.027 0.038

Tebuthiuron 22 3(3) 13.6 --- 0.002 0.005

2,4-D methyl ester 22 2(2) 9.1 --- --- 0.030

Bentazon 22 2(2) 9.1 --- --- 0.006

Diuron 22 2(2) 9.1 --- --- 0.008

Diphenamid 22 1(1) 4.5 --- --- 0.002

Metalaxyl 22 1(1) 4.5 --- --- 0.003

* Caffeine is not a pesticide compound, however it is included in this method.
Summary of Results from a Pilot Monitoring Program 65

Table 42. Statistical summary of pesticides and degradates detected in water samples from the finishedwater monitoring site at City of Waxahachie Water Treatment Plant, Texas

[Concentrations shown in micrograms per lit er; --- indicates value reported as less than the method reporting level; GC-MS, gas chromatography – mass 

spectrometry; HPLC-MS, high performance liquid chromatography – mass spectrometry; (),qualified estimates of pesticide concentrations-- for 

concentrations quantified less than the method reporting level and for compounds with low and variable recoveries based on method performance]

Compound Number Detections Detection Median 90th Maximum

of (qualified frequency, value percentile value

analyses estimates) in percent value 

Analysis of Pesticides by GC-MS (NWQL method 2001)

Atrazine 9 9 100 0.515 0.589 0.589

Deethylatrazine 9 9(9) 100 0.111 0.134 0.134

Metolachlor 9 9 100 0.039 0.050 0.050

Simazine 9 8 88.9 0.017 0.020 0.020

Tebuthiuron 9 5(5) 55.6 0.005 0.008 0.008

Prometon 9 3(3) 33.3 --- 0.008 0.008

Analysis of Pesticides and Degradates by HPLC-MS (NWQL provisional method 9060)

2-Hydroxyatrazine 8 8(8) 100 0.480 0.728 0.728

Atrazine 8 8(1) 100 0.389 0.717 0.717

Deethylatrazine 8 8(8) 100 0.066 0.089 0.089

Deisopropylatrazine 8 8(8) 100 0.014 0.020 0.020

Desethyl desisopropylatrazine 8 6(6) 75.0 0.010 0.013 0.013

2,4-D 8 4(4) 50.0 0.014 0.060 0.060

Tebuthiuron 8 1(1) 12.5 --- 0.003 0.003