U.S. Department of the Interior

U.S. Geological Survey

Open-File Report 2007–1118

Prepared in cooperation with the Sisseton-Wahpeton Oyate

Pesticide Concentrations in Wetlands 

on the Lake Traverse Reservation, 

South and North Dakota, July 2006
Pesticide Concentrations in Wetlands on 

the Lake Traverse Reservation, South and 

North Dakota, July 2006

By Kathleen M. Neitzert and Roy C. Bartholomay

Prepared in cooperation with the Sisseton-Wahpeton Oyate

Open-File Report 2007–1118

U.S. Department of the Interior

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

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

U.S. Geological Survey, Reston, Virginia: 2007

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Suggested citation:

Neitzert, K.M., and Bartholomay, R.C., 2007, Pesticide concentrations in wetlands on the Lake Traverse Reservation, 

South and North Dakota, July 2006: U.S. Geological Survey Open-File Report 2007–1118, 25 p.
iii

Contents

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

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

Purpose and Scope ..............................................................................................................................5

Description of Study Area ...................................................................................................................5

Previous Investigations........................................................................................................................5

Methods of Investigation..............................................................................................................................6

Site Selection.........................................................................................................................................6

Sample Collection.................................................................................................................................6

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

Reporting Levels....................................................................................................................................6

Quality Assurance and Quality Control .............................................................................................7

Field Equipment Blank Sample ..................................................................................................7

Field Replicate Sample ...............................................................................................................8

Pesticide Concentrations in Wetlands.....................................................................................................17

Physical Properties.............................................................................................................................17

Pesticides.............................................................................................................................................17

Synopsis of Pesticide Results....................................................................................................................18

Atrazine.................................................................................................................................................19

2,4–D......................................................................................................................................................19

Glyphosate ...........................................................................................................................................19

Metolachlor..........................................................................................................................................20

Prometon..............................................................................................................................................20

Acetochlor............................................................................................................................................20

Picloram................................................................................................................................................20

Summary........................................................................................................................................................21

References Cited..........................................................................................................................................21

Supplemental Information..........................................................................................................................25

 U.S. Fish and Wildlife Service Wetlands Inventory Codes and Definitions .............................25

Figures

1. Map showing location of the historic Lake Traverse Reservation boundry and 

sample collection sites ................................................................................................................4

2–3. Graphs showing:

2. Number of Lake Traverse Reservation wetlands at which selected pesticides 

were detected, July 2006..................................................................................................17

3. Number of pesticides detected in water samples for selected Lake Traverse

Reservation wetlands, July 2006.....................................................................................18
iv

Conversion Factors, Abbreviations and Acronyms

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

Area

acre 4,047 square meter (m2)

acre 0.4047 hectare (ha)

acre 0.4047 square hectometer (hm2)

acre 0.004047 hecsquare kilometer (km2)

square mile (mi2) 2.590 square kilometer (km2)

Volume

gallon (gal) 3.785 liter (L)

Mass

pound, avoirdupois (lb) 0.4536 kilogram (kg)

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

°F=(1.8×°C)+32

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

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

25°C).

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

or micrograms per liter (μg/L).

Tables

1. Estimated use of 34 pesticides in Roberts County, South Dakota, in 1987..........................2

2. Primary wetlands inventory codes for selected Lake Traverse Reservation 

wetland sampling sites ................................................................................................................7

3. Physical properties of water in selected Lake Traverse Reservation wetlands, 

July 2006.........................................................................................................................................9

4. Pesticide concentrations in water samples from selected Lake Traverse

Reservation wetlands, July 2006..............................................................................................10

5. U.S. Fish and Wildlife Service wetlands inventory codes for selected Lake

Traverse Reservation wetlands at which water-quality samples were collected

during July 2006 ..........................................................................................................................25
Abbreviations and Acronyms

< less than

AMPA Aminomethylphosphonic acid

EPTC s-Ethyl dipropylcarbomothiate

FNC Formazin nephelometric units

LRL Laboratory reporting Level

MCL Maximum Contaminant Level

MCPA (4-Chloro-2-methylphenoxy) acetic acid

MDL Method dectection limit

NWIS U.S. Geological Survey National Water Information System

NWQL U.S. Geological Survey National Water Quality Laboratory

PEMF Palustrine, emergent, semipermanently flooded 

RPD Relative percent difference

SDGS South Dakota Department of Environment and Natural Resources, 

Geological Survey Program

SWO Sisseton-Wahpeton Oyate

USEPA U.S. Environmental Protection Agency

USGS U.S. Geological Survey
Pesticide Concentrations in Wetlands on the Lake 

Traverse Reservation, South and North Dakota, July 2006

By Kathleen M. Neitzert and Roy C. Bartholomay

Traverse Reservation is within the glaciated Central Lowlands 

physiographic province (Thompson, 2002) and includes parts 

of two physiographic divisions, the Prairie Coteau and the 

Minnesota River-Red River lowlands. The Prairie Coteau is a 

plateau of rolling morainal topography formed by deposition 

of glacial debris, and the Minnesota River-Red River lowlands 

is a somewhat flat ground moraine that consists of isolated 

areas of debris left by retreating glaciers (Thompson, 2002). 

Some areas are poorly drained and include numerous wetlands 

that provide a valuable wildlife production resource. Surface 

water and ground water on the Lake Traverse Reservation 

are used for public, domestic, stock-water, recreation, and 

irrigation purposes (Amundson, 2002).

More than 80 percent of the land use within the Lake 

Traverse Reservation is for grain production, pasture, or 

hay, and more than 11 percent of the area is covered by 

surface water in the form of wetlands, lakes, and streams 

(Thompson, 2002). Pesticides are used mainly to control 

weeds (herbicides) and insects (insecticides) on crops, 

although they also may be used to control fungus (fungicides) 

and nematodes (nematocides) on some crops. Row crops 

(primarily soybeans and corn) cover about 693 square 

miles, or about 46 percent of the Lake Traverse Reservation 

(Thompson, 2002). In 1987, 34 herbicides were used in 

Roberts County (Battaglin and Goolsby, 1994), with alachlor, 

atrazine, dicamba, s-ethyl dipropylcarbomothiate (EPTC), 

bromoxynil, (4-chloro-2-methylphenoxy) acetic acid (MCPA), 

metolachlor, trifluralin and 2,4–D all applied to more than 

10,000 acres of cropland (table 1) in that county alone. In 

2000, atrazine and metolachlor were the primary herbicides 

used in Roberts County for corn acreage, and glyphosate 

was the primary herbicide used for soybean acreage (South 

Dakota Agricultural Statistics Service, 2001). Although recent 

pesticide-use data are scarce, it is certain that pesticides are 

still widely used based on current agricultural practices on the 

Lake Traverse Reservation.

Pesticides can persist in natural aquatic systems and have 

long-term effects on biota (Gilliom and others, 2006). Some 

water-quality pesticide data have been collected by the South 

Dakota Department of Environment and Natural Resources, 

Geological Survey Program (SDGS) and the U.S. Geological 

Survey (USGS) at selected ground-water and surface-water 

sites, but no data are available for wetlands within the Lake 

Abstract

During July 2006, water samples were collected 

from selected Lake Traverse wetlands within the historic 

Reservation boundary in northeastern South Dakota and 

southeastern North Dakota as part of a reconnaissancelevel assessment by the U.S. Geological Survey (USGS) 

and Sisseton-Wahpeton Oyate (SWO). Eighteen wetlands 

were sampled by the SWO and USGS personnel after 

primary pesticide application occurred on the Lake Traverse 

Reservation. Samples were analyzed for 61 pesticide 

compounds. In addition, the samples were analyzed for 

physical properties that might help further characterize the 

water quality of the wetlands.

During July 2006, water samples were collected from 

18 wetlands and were analyzed for 61 widely used pesticide 

compounds. Pesticides were detected in 17 of the 18 sampled 

wetlands. In the 17 wetlands in which pesticides were 

detected, the number of pesticides detected ranged from two 

to eight. Of the 61 pesticides for which the samples were 

analyzed, 51 pesticides were not detected in any of the wetland 

samples. Ten pesticides were detected in water samples from 

at least one of the wetlands at small concentrations. Atrazine 

and de-ethyl atrazine were detected in samples from 17 of 

the 18 wetlands. The minimum, maximum, and median 

concentrations of dissolved atrazine detected were 0.007, 

0.12, and 0.064 microgram per liter (μg/L), respectively. Two 

pesticides (picloram and simazine) were detected in only one 

wetland each. None of the pesticide concentrations exceeded 

any U.S. Environmental Protection Agency Maximum 

Contaminant Levels for drinking water, and concentrations 

were much less than levels considered toxic for humans or 

aquatic species.

Introduction

The historic Lake Traverse Reservation boundary 

encompasses parts of five counties (Roberts, Marshall, 

Day, Grant, and Codington Counties) in northeastern South 

Dakota, and parts of two counties (Sargent and Richland 

Counties) in southeastern North Dakota (fig. 1). The Lake 
Table 1. Estimated use of 34 pesticides in Roberts County, South Dakota, in 1987.—Continued

[Data in columns 3, 5, and 9 from Battaglin and Goolsby (1994). Shaded cells indicate pesticides detected in selected Lake Traverse Reservation wetlands 

(fig. 1). EPTC, s-ethyl dipropylcarbomothiate; MCPA, (4-chloro-2-methylphenoxy) acetic acid; --, not applicable]

Pesticide

Analyzed for 

in selected 

Lake Traverse 

Reservation 

wetlands 

(table 4)

Acres1

treated

Rank 

acres 

treated

Pounds2

of active 

ingredient 

applied

Rank of 

active 

ingredient 

applied (all 

pesticides)

Rank of active 

ingredient 

applied

for pesticides 

analyzed for 

in samples 

from Lake 

Traverse 

Reservation 

wetlands

Pounds3

applied 

per treated 

acre

Pounds4

used per 

square mile 

of Roberts 

County

2,4–D Yes 67,614 1 25,029 5 4 2.701 22.281

2,4–DB No 2 33 2 33 -- 1.000 .002

Acifluorfen No 2,645 23 661 24 -- 4.002 .588

Alachlor Yes 30,766 5 56,397 2 1 .546 50.204

Atrazine Yes 11,054 9 10,060 8 6 1.099 8.955

Bentazon No 9,523 10 7,999 10 -- 1.191 7.121

Bromoxynil No 14,734 7 4,289 16 -- 3.435 3.818

Butylate Yes 1,299 27 5,196 13 9 .250 4.625

Chloramben No 1,444 25 3,417 19 -- .423 3.042

Chlorsulfuron No 4,356 19 86 29 -- 50.651 .077

Cyanazine No 5,845 15 6,956 12 -- .840 6.192

Dalapon No 48 31 36 32 -- 1.333 .032

Diallate No 48 31 72 30 -- .667 .064

Dicamba Yes 38,501 3 9,339 9 7 4.123 8.313

Diclofop No 5,261 17 3,946 17 -- 1.333 3.513

Difenzoquat No 1,443 26 1,082 21 -- 1.334 .963

Diquat No 1 34 0 34 -- -- .000

EPTC No 16,469 6 72,185 1 -- .228 64.258

Ethalfluralin Yes 4,861 18 4,571 15 11 1.063 4.069

   Pesticide Concentrations in Wetlands on the Lake Traverse Reservation, South and North Dakota, July 2006
Table 1. Estimated use of 34 pesticides in Roberts County, South Dakota, in 1987.—Continued

[Data in columns 3, 5, and 9 from Battaglin and Goolsby (1994). Shaded cells indicate pesticides detected in selected Lake Traverse Reservation wetlands 

(fig. 1). EPTC, s-ethyl dipropylcarbomothiate; MCPA, (4-chloro-2-methylphenoxy) acetic acid; --, not applicable]

Pesticide

Analyzed for 

in selected 

Lake Traverse 

Reservation 

wetlands 

(table 4)

Acres1

treated

Rank 

acres 

treated

Pounds2

of active 

ingredient 

applied

Rank of 

active 

ingredient 

applied (all 

pesticides)

Rank of active 

ingredient 

applied

for pesticides 

analyzed for 

in samples 

from Lake 

Traverse 

Reservation 

wetlands

Pounds3

applied 

per treated 

acre

Pounds4

used per 

square mile 

of Roberts 

County

Fluazifop No 529 30 106 28 -- 4.991 0.094

Glyphosate Yes 9,187 12 4,957 14 10 1.853 4.413

Imazethapyr No 5,290 16 265 25 -- 19.962 .236

MCPA No 32,076 4 12,151 7 -- 2.640 10.817

Metolachlor Yes 13,135 8 29,929 4 3 .439 26.642

Metribuzin Yes 3,403 21 1,040 22 14 3.272 .926

Metsulfuron No 6,725 13 67 31 -- 100.373 .060

Pendimethalin Yes 6,015 14 7,314 11 8 .822 6.511

Picloram Yes 1,984 24 992 23 15 2.000 .883

Propachlor Yes 3,251 22 16,254 6 5 .200 14.469

Sethoxydim No 1,058 28 212 26 -- 4.991 .189

Simazine Yes 758 29 1,137 20 13 .667 1.012

Thiameturon Yes 9,493 11 190 27 16 49.963 .169

Triallate Yes 3,847 20 3,847 18 12 1.000 3.425

Trifluralin Yes 46,345 2 35,538 3 2 1.304 31.636

1

Rounded to the nearest acre.

2

Rounded to the nearest pound.

3

Calculated from columns 3 and 5.

4

Rounded to three decimal places.

Introduction   
1867 Boundary of the Lake Traverse Reservation

45°30' 45°30'

45°15' 45°15'

45°45' 45°45'

46°00’

97°00'

97°30'

97°15'

North Dakota 96°45'

South Dakota

Sargent Co

Marshall Co Roberts Co

Richland Co

Marshall Co

Day Co

Grant Co

Roberts Co

Codington Co

Day Co

Lake

Traverse

Bois

de

Sioux

River

Mud

Lake

Claire

City

Veblen Hammer

New

Effington

Victor Rosholt

Sisseton

Peever

Ortley

Summit

Agency

Village

Big Sioux 

River Basin

Minnesota

River Basin

Upper Red River Basin

James 

River

Basin

Big Sioux 

River Basin

Minnesota

River Basin

Upper Red River Basin

James 

River

Basin

S22

S21

S20

S19

S18

S17

S15

S14

S13

S10 S12

S09

S08

S07

S04

S03

S02

S01

S22

S21

S20

S19

S18

S17

S15

S14

S13

S10 S12

S09

S08

S07

S04

S03

S02

S01

0 2 4 6 8 10 MILES

0 2 4 6 8 10 KILOMETERS

Base from U.S. Geological Survey digital line graph 1:100,000, 1993

Universal Transverse Mercator projection, zone 14

Study

area

EXPLANATION

Sample site—Number is site label

SOUTH DAKOTA

S08

Figure 1. Location of the historic Lake Traverse Reservation boundry and sample collection sites.

   Pesticide Concentrations in Wetlands on the Lake Traverse Reservation, South and North Dakota, July 2006
Traverse Reservation. Previously collected water-quality data 

indicate that several pesticides, including alachlor, atrazine, 

and 2,4–D, have been detected at concentrations greater than 

laboratory reporting levels (LRLs) (Thompson, 2000, 2002). 

Some of the pesticides that are applied on the Lake Traverse 

Reservation (including alachlor and atrazine) are known 

endocrine disruptors (Danzo, 1997; Wilson and others, 1996; 

and Rawlings and others, 1998), whereas others (including 

glyphosate and 2,4–D) have various levels of toxicity to 

aquatic organisms (U.S. Forest Service, 1995, 1997).

To address concerns about the quality of water in Lake 

Traverse Reservation wetlands, the USGS, in cooperation with 

the Sisseton-Wahpeton Oyate (SWO), conducted a reconnaissance-level study of pesticide concentrations in selected 

wetlands. The samples were analyzed for 61 widely used 

pesticides. The locations of the selected Lake Traverse Reservation wetlands that were sampled for pesticides are shown in 

figure 1.

Purpose and Scope

The purpose of this report is to present the results of a 

reconnaissance-level assessment of pesticide concentrations 

in selected Lake Traverse Reservation wetlands during July 

2006. Specifically, this report presents (1) a summary of 

sample collection and analytical methods; (2) concentrations 

of pesticides and physical properties for selected Lake 

Traverse Reservation wetlands; and (3) a synopsis of the 

pesticide results for those pesticides detected at concentrations 

greater than LRLs. Analytical results for water samples 

include physical properties and pesticide concentrations 

for 18 wetlands. The quality of water in all Lake Traverse 

Reservation wetlands cannot be thoroughly characterized with 

such a limited sampling program; however, the results may 

be useful to assess the effects of land-management practices 

on the aquatic resources and to identify possible water-quality 

concerns that could be the focus of more comprehensive 

investigations in the future.

Description of Study Area

The study area includes the area within the historic 

1867 boundary of the Lake Traverse Reservation (hereafter 

called the Lake Traverse Reservation) and much of Roberts 

County, and parts of Marshall, Day, Grant, and Codington 

Counties in northeastern South Dakota, and parts of Sargent 

and Richland Counties in southeastern North Dakota 

(fig. 1). The Lake Traverse Reservation has an area of about 

1,508 square miles. The Bois des Sioux River, Lake Traverse, 

and Mud Lake form most of the northeastern boundary of 

Roberts County.

Numerous lakes, ponds, and wetlands are located in 

the Lake Traverse Reservation, particularly within internally 

drained, noncontributing areas of the basins of the Big 

Sioux and James Rivers. Many of the lakes are hydraulically 

connected to glacial-outwash aquifers, and lake levels tend to 

rise or fall with the water table (Lawrence, 1989). Several of 

the larger lakes within the study area have been developed for 

recreation, whereas many of the smaller lakes and wetlands 

are used for livestock watering or wildlife-production areas 

(Thompson, 2001).

The study area is relatively sparsely populated, with a 

population in Roberts County of 10,016 in 2000 (U.S. Census 

Bureau, 2001). Municipalities and rural water systems currently provide most of the water used in the study area, with 

nearly all of it from ground-water sources. Surface-water use 

is limited to livestock watering (Thompson, 2001).

Previous Investigations

Although little information is available about pesticide 

concentrations in wetlands within the Lake Traverse 

Reservation, some previous investigations were useful in 

developing the study described in this report. A comprehensive 

water-resources investigation for the Lake Traverse 

Reservation was completed by Thompson (2001). As part of 

that investigation, samples from 13 observation wells were 

analyzed for atrazine, carbofuran, cyanazine, and 2,4–D using 

enzyme-linked immunosorbent assay analysis; a sample from 

one well had a detectable concentration of 2,4–D (Thompson, 

2000).

Additional water-quality analyses for pesticides from 

other USGS studies in the Lake Traverse Reservation area 

were compiled from the USGS National Water Information 

System (NWIS) database. A total of 113 pesticides and 

pesticide metabolites were analyzed in samples from two 

wells and six surface-water sites; six pesticides were detected. 

Lindane was detected in four samples, and 2,4–D, dicamba, 

dieldrin, heptachlor, and p,p ́–DDE were detected in one 

sample each (Thompson, 2002, table 4).

The SDGS has periodically sampled two surface-water 

sites and nine ground-water sites. Atrazine, 2,4–D, and 

alachlor were detected at the surface-water sites, and simazine 

was detected at one ground-water site (Thompson, 2002, 

tables 2–3).

A reconnaissance-level assessment of pesticides in 

wetlands on the Yankton Sioux Reservation in southeastern 

South Dakota was completed by Schaap and Bartholomay 

(2006). Samples from 19 wetlands were analyzed for 

61 pesticide compounds, and 13 pesticides were detected in at 

least one wetland. Samples from all 19 wetlands contained at 

least three to eight pesticides.

As part of a reconnaissance-level assessment of organic 

wastewater compounds in the Upper Big Sioux River Basin 

(Sando and others, 2005), samples from the Big Sioux River 

were analyzed for three pesticides (atrazine, metolachlor, and 

prometon). All three pesticides were detected in some of the 

samples.

Introduction 
Methods of Investigation

This study was designed to provide a reconnaissancelevel assessment of pesticide concentrations in selected 

wetlands within the Lake Traverse Reservation. Waterquality samples were collected for pesticide analyses 

from 18 wetlands during July 2006. Site selection, sample 

collection, analytical methods, reporting levels, and quality 

assurance and quality control are described in this section.

Site Selection

Samples were collected from 18 wetlands on the Lake 

Traverse Reservation (fig. 1). Sites were selected to best 

represent the broad range of wetlands found within the Lake 

Traverse Reservation including physical location, size, and 

type (as indicated by the U.S. Fish and Wildlife National 

Wetlands Inventory; table 2). The area received above-normal 

precipitation in April 2006 (National Weather Service, 2006a, 

2006b), and crop planting began later than normal. Due to the 

wet conditions, the normal spring pesticide application was 

finished later than normal, requiring the pesticide sampling 

to be completed in mid-summer. The wetlands from which 

samples were collected were fairly well distributed throughout 

the study area (fig. 1). The area of the sampled wetlands 

ranged from a few acres to a few hundred acres. The amount 

of vegetation in and surrounding the wetlands ranged from 

little (primarily dirt) to extreme (heavy cattails, bushes, or 

trees), dependent on location and type of wetland.

Sampled wetlands were classified using wetlands 

inventory codes (U.S. Fish and Wildlife Service, 2004). These 

alpha-numeric codes were developed to correspond to the 

classification nomenclature that best describes the habitat. In 

some cases, the sampled wetlands had been assigned multiple 

codes to note multiple influences on the wetlands (table 2). 

For these sites, the code assigned for the largest area of the 

wetland where the sample was collected was considered to be 

the primary code for this report, and varying codes for smaller 

areas associated with the primary area were considered to 

be additional influence codes. A primary wetlands inventory 

code had been assigned to 16 of the sampled wetlands. Of 

the wetlands with primary codes, four also had multiple class 

codes designated within the wetland area. The two sites with 

no assigned primary code did have additional influence codes 

noted. The most frequently noted code was PEMF (Palustrine, 

Emergent, Semipermanently Flooded). More information on 

the wetland codes is given in the Supplemental Information 

Section at the back of this report.

Sample Collection

Eighteen wetlands were sampled by SWO and USGS 

personnel in July 2006 after primary pesticide application 

occurred on the Lake Traverse Reservation. In general, 

sampling procedures followed guidelines described by Wilde 

and others (1999) using two-person, ultra-clean procedures, 

but these procedures were adapted to the conditions 

encountered at the different sites. For each sampled wetland, 

this process involved some combination of collecting water 

in bottles, directly or after filtering, or collecting several 

liters of water in a large container and later transferring 

it to the appropriate bottles in a mobile laboratory. For 

determination of dissolved pesticides, filtering was performed 

using precleaned, baked, glass-fiber 142-millimeter filters or 

precleaned 0.7-micron glass fiber filters. Samples for total 

pesticides were containerized in pre-cleaned, 1-liter, glass 

amber bottles. Samples were collected by wading when 

possible; when the depth or bottom material of the wetland 

did not allow wading, a boat was used. All samples were 

grab samples collected at one vertical location. All samples 

were chilled according to sample specifications and then 

packed for overnight shipping to the USGS National Water 

Quality Laboratory (NWQL) located in Denver, Colorado, for 

analyses.

Analytical Methods

Standard methods were used to analyze samples for 

physical properties (information on specific analytical 

methods can be accessed at http://nwql.usgs.gov/Public/ref_

list.html). Samples for pesticides were analyzed at the NWQL. 

Analyses for the 61 pesticides were performed using methods 

described in Wershaw and others (1987), Zaugg and others 

(1995), and Lee and others (2001).

Reporting Levels

The presence of some constituents, even at very low 

concentrations, is of interest because of potential health effects 

of the constituents. Childress and others (1999) provides 

details about the approach used by the USGS regarding 

detection levels and reporting levels.

The method detection limit (MDL) is the minimum 

concentration of a substance that can be measured and 

reported with 99-percent confidence that the concentration 

is greater than zero. The laboratory reporting level (LRL) 

is the concentration at which the false negative error rate is 

minimized to be no more than one percent of the reported 

results. The LRL generally is equal to twice the yearly 

determined long-term MDL, which is a detection level derived 

by determining the standard deviation of a minimum of 

24 MDL spike-sample measurements over an extended time. 

The long-term MDL controls false positive error and is the 

concentration at which the false positive risk is minimized to 

be no more than one percent of the reported values (Childress 

and others, 1999). These reporting levels may be described 

as preliminary for a developmental method if the levels have 

been based on a small number of analytical results. Also, 

these levels may vary from sample to sample for the same 

   Pesticide Concentrations in Wetlands on the Lake Traverse Reservation, South and North Dakota, July 2006
constituent and the same method if matrix effects or other 

factors arise that interfere with the analysis. Concentrations 

measured between the MDL and the LRL are described as 

estimated values. For most of the constituents in this report, 

reported concentrations are greater than the LRLs unless they 

are indicated as estimated. An estimated concentration should 

be considered a qualitatively detected analyte (Childress and 

others, 1999).

Quality Assurance and Quality Control

Analytical results should describe the environmental 

conditions at the time the samples were collected. 

Unfortunately, certain factors such as sampling error can affect 

the process and ultimately lead to analytical results that are not 

representative of the natural conditions. Several techniques, 

collectively known as quality assurance and quality control, 

were used to evaluate the precision and accuracy of the 

reported analytical results for this study. Quality-assurance 

samples collected during July 2006 as part of this study 

included one field equipment blank sample and one replicate 

sample. Analytical results for the quality-assurance samples 

are presented in the tables along with the analytical results for 

the environmental samples.

Field Equipment Blank Sample

The field equipment blank sample was used to assess 

the possible contamination of samples or analytical error. 

The blank sample was collected by passing ultra-pure water 

through the collection and processing equipment used for 

environmental samples. Procedures used were identical to 

those used to collect and process the environmental samples. 

Table 2. Primary wetlands inventory codes for selected Lake Traverse Reservation wetland sampling sites.

Site

(fig. 1) Station number

Primary wetlands

inventory code

(table 5)

Basin land use

Approximate

wetland size or area 

sampled within wetland

(in acres)

1

S01 454535097023100 PFOC Crops, grazing 36

S02 454717096493000 L2ABG Grazing 50

S03 455426096545100 PEMF Crops 8

S04 454933096361200 PEM/ABFh Marsh, crops 170

S07 453107096583500 PEMF Marsh, crops 18

S08 453031097011800 PAB/EMF Crops 9

S09 453245097071800 PEMFx Crops 8

S10 453801097120100 L1UBG Crops, marsh, grazing 200

S12 453825097104400 PEMC Grazing 1

S13 450811097114200 PEMF Crops, grazing 6

S14 452129097111500 PEM/SSB Crops, grazing 100

S15 452214097095900 None noted Crops grazing 19

S17 452540097142000 L2ABG Unused 75

2

S18 453354097040800 None noted Unused, in town 8

S19 455145097072900 PEMF Marsh, crops 6

S20 455941097223800 PEM/ABF Unused, refuge 2

S21 454315097184400 PEM/ABF Tribal grazing 9

S22 454012097181700 PABF Tribal grazing 4

1

Field equipment blank sample collected at site.

2

Replicate sample collected at site.

Methods of Investigation 
The blank sample was collected at the same location as one of 

the environmental samples and just before the environmental 

sample was collected. If no contamination of the sample is 

introduced during the collection, processing, transport, and 

analysis of the blank sample, and the analytical results are 

accurate, then none of the constituents should be detected.

A field blank was collected at wetland site S01 on 

July 11, 2006 (tables 3–4). All the pesticide concentrations 

in the blank sample were less than the LRLs, indicating the 

sampling and analytical methods did not contaminate the 

samples or produce false detections.

Field Replicate Sample

A field replicate sample is intended to be an exact copy 

of the environmental sample. The field replicate sample was 

collected and processed immediately after the associated 

primary environmental sample was collected and processed, 

and procedures used for the replicate sample were identical 

to those used for the primary sample. Any differences in 

the analytical results between the environmental sample 

and the replicate sample may indicate some combination of 

inconsistency of sample collection, the natural variability in 

the sampled water, and the variability of the analytical method.

A field replicate was collected at wetland site S18 on 

July 13, 2006 (tables 3–4). Precision of analytical results for 

the field replicate sample was determined by calculating the 

relative percent difference (RPD) for the primary/replicate 

sample pair as indicated in the following equation:

RPD = ( ) d x/ *100, (1)

where

	 d	 = difference in concentration between the 

primary environmental sample and the 

field replicate sample for a given primary/

replicate sample pair, and

x = mean concentration of the primary 

environmental sample and the field 

replicate sample for a given primary/

replicate pair.

All the primary/replicate sample pairs either had 

concentrations less than the LRL for both pairs or had the 

given constituent detected in both sample pairs (table 3). All 

the RPDs were within the acceptable level of precision, which 

generally is 20 percent or less (Taylor, 1987).

 Pesticide Concentrations in Wetlands on the Lake Traverse Reservation, South and North Dakota, July 2006
Table 3. Physical properties of water in selected Lake Traverse Reservation wetlands, July 2006.

[Location of sites shown in figure 1. mm of Hg, millimeters of mercury; FNU, formazin nephelometric turbidity units; mg/L, milligrams per liter; μS/cm, microsiemens per centdeg C, degrees Celsius; --, no data. Number in parentheses below property is U.S. Geological Survey National Water Information System parameter code]

Site Station number Date (mm–dd–yyyy) Time Water depth (meters) (82903) Barometric pressure (mm of Hg) (00025) Turbidity (FNU) (63680) Oxygen, dissolved (mg/L) (00300) pH, whole field, standard units (00400) Specific conductance, μS/cm (00095) 

S01 454535097023100 07–11–2006 0910 1.27 729 -- 2.0 7.8 897 S02 454717096493000 07–12–2006 0930 1.28 733 6.1 8.3 8.5 1,490 S03 455426096545100 07–11–2006 1355 1.22 732 16 7.0 8.2 995 S04 454933096361200 07–12–2006 1130 .21 736 6.1 8.4 8.7 1,400 S07 453107096583500 07–20–2006 0950 .06 736 65 3.5 8.1 5,040 S08 453031097011800 07–20–2006 0910 .27 730 66 9.2 8.8 1,360 S09 453245097071800 07–13–2006 1030 .61 703 1.0 3.0 7.4 320 S10 453801097120100 07–12–2006 1440 4.88 709 3.5 9.2 8.8 681 S12 453825097104400 07–12–2006 1540 .15 712 230 18.5 8.7 409 S13 450811097114200 07–20–2006 1255 .12 720 160 4.0 6.7 775 S14 452129097111500 07–20–2006 1135 .31 719 1.5 4.6 7.4 552 S15 452214097095900 07–20–2006 1105 .17 718 5.3 5.0 7.4 502 S17 452540097142000 07–20–2006 1040 .46 718 .5 11.9 9.4 823 S18 453354097040800 07–13–2006 1120 1.22 717 3.2 10.3 8.5 1,240 

1S18 453354097040800 07–13–2006 1130 1.22 717 3.2 10.3 8.5 1,240 

S19 455145097072900 07–11–2006 1025 .76 729 34 1.4 7.0 885 S20 455941097223800 07–11–2006 1240 .70 728 20 2.2 7.7 1,360 S21 454315097184400 07–13–2006 0850 .34 706 3.8 4.8 8.2 1,230 S22 454012097181700 07–13–2006 0930 .46 707 1.0 7.2 9.0 272 

1Replicate sample collected at site.
Table 4. Pesticide concentrations in water samples from selected Lake Traverse Reservation wetlands, July 2006.

[Location of sites shown in figure 1. All concentrations in micrograms per liter. All concentrations are dissolved, unless otherwise noted. RPD, relative percent difference; AMPAacid; EPTC, s-ethyl dipropylcarbomothiate; <, less than; E, estimated. Shading represents estimated values or values greater than the reporting level. Number in parentheses beloU.S. Geological Survey National Water Information System parameter code]

Site Station number Date (mm–dd–yyyy) Time 2,4,5–T, total (39740) 2,4–D, total (39730) 2,6–Di- ethyl aniline (82660) Aceto- chlor (49260) Alachlor (46342) alpha- HCH (34253) AMPA (62649) 

S01 454535097023100 07–11–2006 0910 <0.03 0.11 <0.006 <0.006 <0.005 <0.005 0.46 

1S01 454535097023100 07–11–2006 0900 <.03 <.02 <.006 <.006 <.005 <.005 <.310 

S02 454717096493000 07–12–2006 0930 <.03 <.02 <.006 <.006 <.005 <.005 <.310 

S03 455426096545100 07–11–2006 1355 <.03 <.02 <.006 <.006 <.005 <.005 <.310 

S04 454933096361200 07–12–2006 1130 <.03 .03 <.006 <.006 <.005 <.005 E.260 

S07 453107096583500 07–20–2006 0950 <.03 <.02 <.006 <.006 <.005 <.005 <.310 

S08 453031097011800 07–20–2006 0910 <.03 E.11 <.006 <.006 <.005 <.005 E.130 

S09 453245097071800 07–13–2006 1030 <.03 .1 <.006 <.006 <.005 <.005 <.310 

S10 453801097120100 07–12–2006 1440 <.03 .1 <.006 E.007 <.005 <.005 <.310 

S12 453825097104400 07–12–2006 1540 <.03 <.02 <.006 <.006 <.005 <.005 <.310 

S13 450811097114200 07–20–2006 1255 <.03 E.11 <.006 <.006 <.005 <.005 <.310 

S14 452129097111500 07–20–2006 1135 <.03 <.02 <.006 <.006 <.005 <.005 <.310 

S15 452214097095900 07–20–2006 1105 <.03 <.02 <.006 <.006 <.005 <.005 <.310 

S17 452540097142000 07–20–2006 1040 <.03 E.05 <.006 <.006 <.005 <.005 <.310 

S18 453354097040800 07–13–2006 1120 <.03 .03 <.006 E.008 <.005 <.005 <.310 

2S18 453354097040800 07–13–2006 1130 <.03 .03 <.006 E.009 <.005 <.005 <.310 

S19 455145097072900 07–11–2006 1025 <.03 <.02 <.006 <.006 <.005 <.005 E.150 

S20 455941097223800 07–11–2006 1240 <.03 <.02 <.006 <.006 <.005 <.005 E.090 

S21 454315097184400 07–13–2006 0850 <.03 <.02 <.006 <.006 <.005 <.005 <.310 

S22 454012097181700 07–13–2006 0930 <.03 .08 <.006 <.006 <.005 <.005 <.310 

RPD3 0 0 0 11.8 0 0 0 
Table 4. Pesticide concentrations in water samples from selected Lake Traverse Reservation wetlands, July 2006.—Continued

[Location of sites shown in figure 1. All concentrations in micrograms per liter. All concentrations are dissolved, unless otherwise noted. RPD, relative percent difference; AMPAacid; EPTC, s-ethyl dipropylcarbomothiate; <, less than; E, estimated. Shading represents estimated values or values greater than the reporting level. Number in parentheses beloU.S. Geological Survey National Water Information System parameter code]

Site Station number Date (mm–dd–yyyy) Time Ben- fluralin (82673) Butylate (04028) Carbaryl (82680) Carbo- furan (82674) Chlor- pyrifos (38933) cis- Perme- thrin (82687) Cyan- azine (04041) 

S01 454535097023100 07–11–2006 0910 <0.010 <0.004 <0.041 <0.020 <0.005 <0.006 <0.018 

1S01 454535097023100 07–11–2006 0900 <.010 <.004 <.041 <.020 <.005 <.006 <.018 

S02 454717096493000 07–12–2006 0930 <.010 <.004 <.041 <.020 <.005 <.006 <.018 

S03 455426096545100 07–11–2006 1355 <.010 <.004 <.041 <.020 <.005 <.006 <.018 

S04 454933096361200 07–12–2006 1130 <.010 <.004 <.041 <.020 <.005 <.006 <.018 

S07 453107096583500 07–20–2006 0950 <.010 <.004 <.041 <.020 <.005 <.006 <.018 

S08 453031097011800 07–20–2006 0910 <.010 <.004 <.041 <.020 <.005 <.006 <.018 

S09 453245097071800 07–13–2006 1030 <.010 <.004 <.041 <.020 <.005 <.006 <.018 

S10 453801097120100 07–12–2006 1440 <.010 <.004 <.041 <.020 <.005 <.006 <.018 

S12 453825097104400 07–12–2006 1540 <.010 <.004 <.041 <.020 <.005 <.006 <.018 

S13 450811097114200 07–20–2006 1255 <.010 <.004 <.041 <.020 <.005 <.006 <.018 

S14 452129097111500 07–20–2006 1135 <.010 <.004 <.041 <.020 <.005 <.006 <.018 

S15 452214097095900 07–20–2006 1105 <.010 <.004 <.041 <.020 <.005 <.006 <.018 

S17 452540097142000 07–20–2006 1040 <.010 <.004 <.041 <.020 <.005 <.006 <.018 

S18 453354097040800 07–13–2006 1120 <.010 <.004 <.041 <.020 <.005 <.006 <.018 

2S18 453354097040800 07–13–2006 1130 <.010 <.004 <.041 <.020 <.005 <.006 <.018 

S19 455145097072900 07–11–2006 1025 <.010 <.004 <.041 <.020 <.005 <.006 <.018 

S20 455941097223800 07–11–2006 1240 <.010 <.004 <.041 <.020 <.005 <.006 <.018 

S21 454315097184400 07–13–2006 0850 <.010 <.004 <.041 <.020 <.005 <.006 <.018 

S22 454012097181700 07–13–2006 0930 <.010 <.004 <.041 <.020 <.005 <.006 <.018 

RPD3 0 0 0 0 0 0 0 
Table 4. Pesticide concentrations in water samples from selected Lake Traverse Reservation wetlands, July 2006.—Continued

[Location of sites shown in figure 1. All concentrations in micrograms per liter. All concentrations are dissolved, unless otherwise noted. RPD, relative percent difference; AMPAacid; EPTC, s-ethyl dipropylcarbomothiate; <, less than; E, estimated. Shading represents estimated values or values greater than the reporting level. Number in parentheses beloU.S. Geological Survey National Water Information System parameter code]

Site Station number Date (mm–dd–yyyy) Time Desulfinyl- fipronil (62170) Desulfinyl- fipronil- amide (62169) Diazinon (39572) Dicamba, total (82052) Dichlor- prop, total (82183) Dieldrin (39381) Disulfoton (82677) 

S01 454535097023100 07–11–2006 0910 <0.012 <0.029 <0.005 <0.03 <0.02 <0.009 <0.02 

1S01 454535097023100 07–11–2006 0900 <.012 <.029 <.005 <.03 <.02 <.009 <.02 

S02 454717096493000 07–12–2006 0930 <.012 <.029 <.005 <.03 <.02 <.009 <.02 S03 455426096545100 07–11–2006 1355 <.012 <.029 <.005 <.03 <.02 <.009 <.02 S04 454933096361200 07–12–2006 1130 <.012 <.029 <.005 <.03 <.02 <.009 <.02 S07 453107096583500 07–20–2006 0950 <.012 <.029 <.005 <.03 <.02 <.009 <.02 S08 453031097011800 07–20–2006 0910 <.012 <.029 <.005 <.03 <.02 <.009 <.02 

S09 453245097071800 07–13–2006 1030 <.012 <.029 <.005 <.03 <.02 <.009 <.02 

S10 453801097120100 07–12–2006 1440 <.012 <.029 <.005 <.03 <.02 <.009 <.02 

S12 453825097104400 07–12–2006 1540 <.012 <.029 <.005 <.03 <.02 <.009 <.02 

S13 450811097114200 07–20–2006 1255 <.012 <.029 <.013 <.03 <.02 <.009 <.02 

S14 452129097111500 07–20–2006 1135 <.012 <.029 <.005 <.03 <.02 <.009 <.02 

S15 452214097095900 07–20–2006 1105 <.012 <.029 <.005 <.03 <.02 <.009 <.02 

S17 452540097142000 07–20–2006 1040 <.012 <.029 <.005 <.03 <.02 <.009 <.02 

S18 453354097040800 07–13–2006 1120 <.012 <.029 <.005 <.03 <.02 <.009 <.02 

2S18 453354097040800 07–13–2006 1130 <.012 <.029 <.005 <.03 <.02 <.009 <.02 

S19 455145097072900 07–11–2006 1025 <.012 <.029 <.005 <.03 <.02 <.009 <.02 

S20 455941097223800 07–11–2006 1240 <.012 <.029 <.005 <.03 <.02 <.009 <.02 

S21 454315097184400 07–13–2006 0850 <.012 <.029 <.005 <.03 <.02 <.009 <.02 

S22 454012097181700 07–13–2006 0930 <.012 <.029 <.005 <.03 <.02 <.009 <.02 

RPD3 0 0 0 0 0 0 0 
Table 4. Pesticide concentrations in water samples from selected Lake Traverse Reservation wetlands, July 2006.—Continued

[Location of sites shown in figure 1. All concentrations in micrograms per liter. All concentrations are dissolved, unless otherwise noted. RPD, relative percent difference; AMPAacid; EPTC, s-ethyl dipropylcarbomothiate; <, less than; E, estimated. Shading represents estimated values or values greater than the reporting level. Number in parentheses beloU.S. Geological Survey National Water Information System parameter code]

Site Station number Date (mm–dd–yyyy) Time Ethoprop (82672) Fipronil (62166) Fipronil sulfide (62167) Fipronil sulfone (62168) Fonofos (04095) Glufosinate (62721) Gly- phosate (62722) 

S01 454535097023100 07–11–2006 0910 <0.012 <0.016 <0.013 <0.024 <0.005 <0.140 <0.150 

1S01 454535097023100 07–11–2006 0900 <.012 <.016 <.013 <.024 <.005 <.140 <.150 

S02 454717096493000 07–12–2006 0930 <.012 <.016 <.013 <.024 <.005 <.140 E.060 S03 455426096545100 07–11–2006 1355 <.012 <.016 <.013 <.024 <.005 <.140 <.150 S04 454933096361200 07–12–2006 1130 <.012 <.016 <.013 <.024 <.005 <.140 E.070 S07 453107096583500 07–20–2006 0950 <.012 <.016 <.013 <.024 <.005 <.140 <.150 S08 453031097011800 07–20–2006 0910 <.012 <.016 <.013 <.024 <.005 <.140 <.150 

S09 453245097071800 07–13–2006 1030 <.012 <.016 <.013 <.024 <.005 <.140 E.050 

S10 453801097120100 07–12–2006 1440 <.012 <.016 <.013 <.024 <.005 <.140 <.150 

S12 453825097104400 07–12–2006 1540 <.012 <.016 <.013 <.024 <.005 <.140 <.150 

S13 450811097114200 07–20–2006 1255 <.012 <.016 <.013 <.024 <.005 <.140 E.110 

S14 452129097111500 07–20–2006 1135 <.012 <.016 <.013 <.024 <.005 <.140 <.150 

S15 452214097095900 07–20–2006 1105 <.012 <.016 <.013 <.024 <.005 <.140 <.150 

S17 452540097142000 07–20–2006 1040 <.012 <.016 <.013 <.024 <.005 <.140 <.150 

S18 453354097040800 07–13–2006 1120 <.012 <.016 <.013 <.024 <.005 <.140 <.150 

2S18 453354097040800 07–13–2006 1130 <.012 <.016 <.013 <.024 <.005 <.140 <.150 

S19 455145097072900 07–11–2006 1025 <.012 <.016 <.013 <.024 <.005 <.140 <.150 

S20 455941097223800 07–11–2006 1240 <.012 <.016 <.013 <.024 <.005 <.140 .3 

S21 454315097184400 07–13–2006 0850 <.012 <.016 <.013 <.024 <.005 <.140 <.150 

S22 454012097181700 07–13–2006 0930 <.012 <.016 <.013 <.024 <.005 <.140 <.150 

RPD3 0 0 0 0 0 0 0 
Table 4. Pesticide concentrations in water samples from selected Lake Traverse Reservation wetlands, July 2006.—Continued

[Location of sites shown in figure 1. All concentrations in micrograms per liter. All concentrations are dissolved, unless otherwise noted. RPD, relative percent difference; AMPAacid; EPTC, s-ethyl dipropylcarbomothiate; <, less than; E, estimated. Shading represents estimated values or values greater than the reporting level. Number in parentheses beloU.S. Geological Survey National Water Information System parameter code]

Site Station number Date (mm–dd–yyyy) Time Malathion (39532) Meto- lachlor (39415) Metribuzin (82630) Molinate (82671) Naprop- amide (82684) p,p ́–DDE (34653) Parathion (39542) 

S01 454535097023100 07–11–2006 0910 <0.027 <0.006 <0.028 <0.003 <0.007 <0.003 <0.010 

1S01 454535097023100 07–11–2006 0900 <.027 <.006 <.028 <.003 <.007 <.003 <.010 

S02 454717096493000 07–12–2006 0930 <.027 <.006 <.028 <.003 <.007 <.003 <.010 S03 455426096545100 07–11–2006 1355 <.027 <.006 <.028 <.003 <.007 <.003 <.010 S04 454933096361200 07–12–2006 1130 <.027 .027 <.028 <.003 <.007 <.003 <.010 S07 453107096583500 07–20–2006 0950 <.027 <.006 <.028 <.003 <.007 <.003 <.010 S08 453031097011800 07–20–2006 0910 <.027 .008 <.028 <.003 <.007 <.003 <.010 

S09 453245097071800 07–13–2006 1030 <.027 <.006 <.028 <.003 <.007 <.003 <.010 

S10 453801097120100 07–12–2006 1440 <.027 <.006 <.028 <.003 <.007 <.003 <.010 

S12 453825097104400 07–12–2006 1540 <.027 <.006 <.028 <.003 <.007 <.003 <.010 

S13 450811097114200 07–20–2006 1255 <.027 <.006 <.028 <.003 <.007 <.003 <.010 

S14 452129097111500 07–20–2006 1135 <.027 <.006 <.028 <.003 <.007 <.003 <.010 

S15 452214097095900 07–20–2006 1105 <.027 <.006 <.028 <.003 <.007 <.003 <.010 

S17 452540097142000 07–20–2006 1040 <.027 <.006 <.028 <.003 <.007 <.003 <.010 

S18 453354097040800 07–13–2006 1120 <.027 E.004 <.028 <.003 <.007 <.003 <.010 

2S18 453354097040800 07–13–2006 1130 <.027 E.004 <.028 <.003 <.007 <.003 <.010 

S19 455145097072900 07–11–2006 1025 <.027 <.006 <.028 <.003 <.007 <.003 <.010 

S20 455941097223800 07–11–2006 1240 <.027 <.006 <.028 <.003 <.007 <.003 <.010 

S21 454315097184400 07–13–2006 0850 <.027 <.006 <.028 <.003 <.007 <.003 <.010 

S22 454012097181700 07–13–2006 0930 <.027 <.006 <.028 <.003 <.007 <.003 <.010 

RPD3 0 0 0 0 0 0 0 
Table 4. Pesticide concentrations in water samples from selected Lake Traverse Reservation wetlands, July 2006.—Continued

[Location of sites shown in figure 1. All concentrations in micrograms per liter. All concentrations are dissolved, unless otherwise noted. RPD, relative percent difference; AMPAacid; EPTC, s-ethyl dipropylcarbomothiate; <, less than; E, estimated. Shading represents estimated values or values greater than the reporting level. Number in parentheses beloU.S. Geological Survey National Water Information System parameter code]

Site Station number Date (mm–dd–yyyy) Time Pendi- methalin (82683) Phorate (82664) Picloram, total (39720) Prometon (04037) Propyz- amide (82676) Propa- chlor (04024) Propanil (82679) 

S01 454535097023100 07–11–2006 0910 <0.022 <0.055 <0.04 <0.01 <0.004 <0.010 <0.011 

1S01 454535097023100 07–11–2006 0900 <.022 <.055 <.04 <.01 <.004 <.010 <.011 

S02 454717096493000 07–12–2006 0930 <.022 <.055 <.04 <.01 <.004 <.010 <.011 S03 455426096545100 07–11–2006 1355 <.022 <.055 <.04 <.01 <.004 <.010 <.011 S04 454933096361200 07–12–2006 1130 <.022 <.055 <.04 E.01 <.004 <.010 <.011 S07 453107096583500 07–20–2006 0950 <.022 <.055 <.04 <.01 <.004 <.010 <.021 S08 453031097011800 07–20–2006 0910 <.022 <.055 <.04 <.01 <.004 <.010 <.011 

S09 453245097071800 07–13–2006 1030 <.022 <.055 <.04 <.01 <.004 <.010 <.011 

S10 453801097120100 07–12–2006 1440 <.022 <.055 <.04 <.01 <.004 <.010 <.011 

S12 453825097104400 07–12–2006 1540 <.022 <.055 <.04 <.01 <.004 <.010 <.011 

S13 450811097114200 07–20–2006 1255 <.022 <.055 .05 <.01 <.004 <.010 <.011 

S14 452129097111500 07–20–2006 1135 <.022 <.055 <.04 <.01 <.004 <.010 <.011 

S15 452214097095900 07–20–2006 1105 <.022 <.055 <.04 <.01 <.004 <.010 <.011 

S17 452540097142000 07–20–2006 1040 <.022 <.055 <.04 <.01 <.004 <.010 <.015 

S18 453354097040800 07–13–2006 1120 <.022 <.055 <.04 E.01 <.004 <.010 <.011 

2S18 453354097040800 07–13–2006 1130 <.022 <.055 <.04 E.01 <.004 <.010 <.011 

S19 455145097072900 07–11–2006 1025 <.022 <.055 <.04 .03 <.004 <.010 <.011 

S20 455941097223800 07–11–2006 1240 <.022 <.055 <.04 <.01 <.004 <.010 <.011 

S21 454315097184400 07–13–2006 0850 <.022 <.055 <.04 <.01 <.004 <.010 <.011 

S22 454012097181700 07–13–2006 0930 <.022 <.055 <.04 <.01 <.004 <.010 <.011 

RPD3 0 0 0 0 0 0 0 
Table 4. Pesticide concentrations in water samples from selected Lake Traverse Reservation wetlands, July 2006.—Continued

[Location of sites shown in figure 1. All concentrations in micrograms per liter. All concentrations are dissolved, unless otherwise noted. RPD, relative percent difference; AMPAacid; EPTC, s-ethyl dipropylcarbomothiate; <, less than; E, estimated. Shading represents estimated values or values greater than the reporting level. Number in parentheses beloU.S. Geological Survey National Water Information System parameter code]

Site Station number Date (mm–dd–yyyy) Time Simazine (04035) Tebuthi- uron (82670) Terbacil (82665) Terbufos (82675) Thioben- carb (82681) Triallate (82678) Trifluralin (82661)

S01 454535097023100 07–11–2006 0910 <0.005 <0.02 <0.034 <0.02 <0.010 <0.006 <0.009

1S01 454535097023100 07–11–2006 0900 <.005 <.02 <.034 <.02 <.010 <.006 <.009

S02 454717096493000 07–12–2006 0930 <.005 <.02 <.034 <.02 <.010 <.006 <.009S03 455426096545100 07–11–2006 1355 <.005 <.02 <.034 <.02 <.010 <.006 <.009S04 454933096361200 07–12–2006 1130 E.002 <.02 <.034 <.02 <.010 <.006 <.009S07 453107096583500 07–20–2006 0950 <.005 <.02 <.034 <.02 <.010 <.006 <.009S08 453031097011800 07–20–2006 0910 <.005 <.02 <.034 <.02 <.010 <.006 <.009

S09 453245097071800 07–13–2006 1030 <.005 <.02 <.034 <.02 <.010 <.006 <.009

S10 453801097120100 07–12–2006 1440 <.005 <.02 <.034 <.02 <.010 <.006 <.009

S12 453825097104400 07–12–2006 1540 <.005 <.02 <.034 <.02 <.010 <.006 <.009

S13 450811097114200 07–20–2006 1255 <.005 <.02 <.034 <.02 <.010 <.006 <.009

S14 452129097111500 07–20–2006 1135 <.005 <.02 <.034 <.02 <.010 <.006 <.009

S15 452214097095900 07–20–2006 1105 <.005 <.02 <.034 <.02 <.010 <.006 <.009

S17 452540097142000 07–20–2006 1040 <.005 <.02 <.034 <.02 <.010 <.006 <.009

S18 453354097040800 07–13–2006 1120 <.005 <.02 <.034 <.02 <.010 <.006 <.009

2S18 453354097040800 07–13–2006 1130 <.005 <.02 <.034 <.02 <.010 <.006 <.009

S19 455145097072900 07–11–2006 1025 <.005 <.02 <.034 <.02 <.010 <.006 <.009

S20 455941097223800 07–11–2006 1240 <.005 <.02 <.034 <.02 <.010 <.006 <.009

S21 454315097184400 07–13–2006 0850 <.005 <.02 <.034 <.02 <.010 <.006 <.009

S22 454012097181700 07–13–2006 0930 <.005 <.02 <.034 <.02 <.010 <.006 <.009

RPD3 0 0 0 0 0 0 0

1Field equipment blank sample collected at site (water only).2Replicate sample collected at site.3Relative percent difference between field environmental and field replicate sample for site S18.
2,4-D

Acetochlor

AMPA

Atrazine

de-ethly Atrazine

Glyphosate

Metolachlor

Picloram

Prometon

Simazine

PESTICIDES DETECTED

0

2

4

6

8

10

12

14

16

18

Samples were collected from

 18 wetlands (see table 2)

NUMBER OF WETLANDS

Figure 2. Number of Lake Traverse Reservation wetlands at which selected pesticides were detected, July 2006.

Pesticide Concentrations in Wetlands

This section of the report summarizes the pesticide 

concentrations in water samples collected from 18 wetlands 

within the Lake Traverse Reservation. In addition to presenting 

analytical results for pesticides, results for physical properties 

are included. The samples collected for this study were 

analyzed for the physical properties of barometric pressure, 

turbidity, dissolved oxygen, pH, specific conductance, water 

temperature, and air temperature (table 3), and 61 pesticides 

(table 4).

Physical Properties

Water samples collected for this study were analyzed 

for the physical properties presented in table 3. The results 

indicate the wetlands are representative of a wide variety of 

conditions. Turbidity ranged from 0.5 formazin nephelometric 

turbidity unit (FNU) (wetland site S17) to 230 FNU (wetland 

site S12), with a median value of 6.1 FNU. Dissolved-oxygen 

concentrations ranged from 1.4 milligrams per liter (mg/L) 

(wetland site S19) to 18.5 mg/L (wetland site S12), with 

a median concentration of 6 mg/L. The pH values ranged 

from 6.7 (wetland site S13) to 9.4 (wetland site S17), with 

a median value of 8.2. Specific conductance ranged from 

272 microsiemens per centimeter (μS/cm) (wetland site S22) 

to 5,040 μS/cm (wetland site S07), with a median value of 

891 μS/cm. Water temperature ranged from 18.1 degrees 

Celsius (oC) (wetland site S14) to 32.7oC (wetland site S12), 

with a median temperature of 23.5oC.

Pesticides

Water samples were analyzed for dissolved 

concentrations of 55 pesticides and for total concentrations 

of 6 pesticides (table 4). Of the 61 pesticides analyzed for 

in samples, 51 were not detected in any of the samples. 

Of the 10 pesticides that had estimated concentrations or 

concentrations greater than the LRL (fig. 2), most were 

detected at very low concentrations in only a few samples. 

Pesticide Concentrations in Wetlands 17
LAKE TRAVERSE WETLAND SAMPLED DURING JULY 2006

0

2

4

6

8

10

Samples were analyzed for 61 pesticides

 (see tables 3 and 4)

NUMBER OF PESTICIDES DETECTED

S01 S02 S03 S04 S07 S08 S09 S10 S12 S13 S14 S15 S17 S18 S19 S20 S21 S22

Figure 3. Number of pesticides detected in water samples for selected Lake Traverse Reservation wetlands, July 2006.

Samples from all but one wetland (site S14) contained at least 

two pesticides (fig. 3); no pesticides were detected at site 14. 

Of the 17 wetlands in which pesticides were detected, the 

number of pesticides detected ranged from two to eight, with a 

median of four.

Atrazine and the atrazine metabolite, de-ethyl atrazine, 

were detected in 17 of the 18 wetlands sampled (fig. 2). 

Detected concentrations of dissolved atrazine ranged from 

0.007 to 0.12 microgram per liter (μg/L), with a median 

concentration of 0.064 μg/L. Estimated concentrations of 

dissolved de-ethyl atrazine ranged from 0.005 to 0.03 μg/L, 

with a median concentration of 0.017 μg/L. Other pesticides 

that had concentrations that were estimated or greater 

than the LRL included 2,4–D, which was detected in nine 

environmental samples and the one replicate sample, with 

dissolved concentrations that ranged from 0.03 to 0.11 μg/L; 

glyphosate, which was detected in five samples with dissolved 

concentrations that ranged from an estimated 0.050 to 

0.3 μg/L; aminomethylphosphonic acid (AMPA), which was 

detected in five samples with dissolved concentrations that 

ranged from an estimated 0.090 to 0.46 μg/L; metolachlor, 

which was detected in three environmental samples and the 

one replicate sample, with dissolved concentrations that 

ranged from an estimated 0.004 to 0.027 μg/L; prometon, 

which was detected in three environmental samples and the 

one replicate sample, with dissolved concentrations that 

ranged from an estimated 0.01 to 0.03 μg/L; acetochlor, 

which was detected in two environmental samples and the 

one replicate sample, with estimated dissolved concentrations 

that ranged from 0.007 to 0.009 μg/L; picloram, which was 

detected in one sample at a concentration of 0.05 μg/L; and 

simazine, which was detected in one sample at a dissolved 

concentration of an estimated 0.002 μg/L.

Synopsis of Pesticide Results

The analytical results from this study indicate some 

pesticides were present in selected Lake Traverse Reservation 

wetlands. Comparing these results to those from previous 

studies and to established water-quality standards may provide 

useful information relative to the quality of the water in the 

wetlands. This synopsis will focus on the pesticides detected 

at concentrations greater than the LRLs for this study.

18  Pesticide Concentrations in Wetlands on the Lake Traverse Reservation, South and North Dakota, July 2006
The U.S. Environmental Protection Agency (USEPA) has 

established drinking water standards for some compounds that 

may cause adverse health effects from long-term exposure. 

These standards are known as Maximum Contaminant Levels 

(MCLs) (U.S. Environmental Protection Agency, 2002). 

Because MCLs apply only to drinking water from public water 

supplies, the MCLs do not apply to any of the wetlands in this 

study, but are used as a basis of comparison.

Atrazine

Atrazine has been widely used in the study area (table 1) 

and has the physical and chemical properties that allow it to 

move readily in the environment (Capel, 1990). Atrazine was 

one of 34 pesticides for which Battaglin and Goolsby (1994) 

estimated use in Roberts County in 1987. Of the 34 pesticides, 

atrazine was ranked ninth in the number of acres treated and 

eighth in pounds of active ingredient applied (table 1).

Atrazine (along with its metabolite, de-ethyl atrazine) 

was detected more frequently (fig. 2) than any other pesticide 

in wetlands (17 of 18 wetlands) selected for this study 

and had detected concentrations that ranged from 0.007 to 

0.12 μg/L. Atrazine also was commonly detected in two 

samples from surface-water sites in the study area (Big Sioux 

River and Indian River) sampled by the SDGS in 1993 at 

concentrations that ranged from 0.1 to 1.5 μg/L (Thompson, 

2002). The SDGS also sampled nine observation wells in 

the study area and found atrazine concentrations that ranged 

from 0.1 to 0.7 μg/L (Thompson, 2002). Atrazine also was 

detected in samples collected during June 2004 from all nine 

Big Sioux River sites near Watertown, Volga, and Brookings 

at concentrations that ranged from an estimated 0.16 to 

1.5 μg/L, but was not as frequently detected in samples 

collected at the same sites during August 2003 (Sando and 

others, 2005). Atrazine was detected in all 18 wetland samples 

collected in 2005 from the Yankton Sioux Reservation at 

concentrations that ranged from 0.056 to 0.151 μg/L (Schaap 

and Bartholomay, 2006).

For this study and previous studies, samples analyzed for 

atrazine were collected during periods when the concentrations 

probably were at their largest concentrations because of 

recent application to fields. Although the detection frequency 

was high, concentrations for this study were much less than 

the MCL for drinking water of 3 μg/L (U.S. Environmental 

Protection Agency, 2002). Field and laboratory studies have 

indicated that atrazine may be associated with endocrine 

disruption in aquatic organisms (Hayes and others, 2003, 

2006; Spano and others, 2004). Atrazine exposure has been 

reported to result in reproductive abnormalities in American 

Leopard frogs at concentrations as small as 0.1 μg/L (Hayes 

and others, 2003), but reported levels for fish are substantially 

larger (Sando and others, 2005). The atrazine concentrations 

detected in two samples from this study were at the levels 

that may affect reproduction in frogs, but the length of time 

the concentrations remained at this level in the environment 

cannot be determined without more sampling. Further research 

is needed to fully assess the potential for endocrine disruption.

2,4–D

2,4–D was one of the most widely used pesticides in the 

study area (table 1) and the second most frequently detected 

compound (fig. 2). 2,4–D was detected in 9 of 18 wetlands 

sampled. It was one of 34 pesticides for which Battaglin and 

Goolsby (1994) estimated use in Roberts County in 1987. Of 

the 34 pesticides, 2,4–D ranked first in number of acres treated 

and fifth in pounds of active ingredient applied (table 1).

2,4–D concentrations in Lake Traverse Reservation wetlands ranged from 0.03 to 0.11 μg/L. 2,4–D also was detected 

in three samples from two surface-water sites in the study area 

(Big Sioux River and Indian River) sampled by SDGS in 1993 

at concentrations that ranged from 1.0 to 7.5 μg/L (Thompson, 

2002). The SDGS also sampled nine observation wells in the 

study area and found 2,4–D concentrations that ranged from 

0.1 to 0.7 μg/L (Thompson, 2002). 2,4–D also was detected in 

12 wetland samples collected in 2005 from the Yankton Sioux 

Reservation at concentrations that ranged from an estimated 

0.02 to 0.85 μg/L (Schaap and Bartholomay, 2006).

2,4–D samples for this study and other previous studies 

were collected during periods when the concentrations were 

probably at their largest concentrations because of recent 

application to fields. Although the detection frequency was 

high, concentrations for this study were much less than the 

MCL for drinking water of 70 μg/L (U.S. Environmental 

Protection Agency, 2002). Field and laboratory studies 

have indicated that 2,4–D and its forms range from being 

practically nontoxic to highly toxic to fish and aquatic 

invertebrates (U.S. Forest Service, 1995), but toxicity occurs at 

concentrations that are much larger than those detected in this 

study.

Glyphosate

Glyphosate was a commonly used pesticide in the study 

area (table 1) and was the third most frequently detected 

compound (fig. 2), along with its primary transformation 

product AMPA. Glyphosate was detected in 5 of the 

18 wetlands sampled (fig. 2). It was one of 34 pesticides for 

which Battaglin and Goolsby (1994) estimated use in Roberts 

County in 1987. Of the 34 pesticides, glyphosate was ranked 

twelfth in number of acres treated and fourteenth in pounds 

of active ingredient applied (table 1); however, its use in the 

midwestern United States tripled from 1997 to 2001 (Battaglin 

and others, 2003).

Glyphosate concentrations ranged from an estimated 

0.050 to 0.3 μg/L. Glyphosate was not detected in previous 

samples from the study area (Thompson, 2002), but was 

detected in eight wetland samples collected in 2005 from the 

Yankton Sioux Reservation at concentrations that ranged from 

0.1 to 0.7 μg/L (Schaap and Bartholomay, 2006).

Synopsis of Pesticide Results 19
Glyphosate samples for this study and other previous 

studies were collected during periods when the concentrations 

probably were at their largest concentrations because of 

recent application to fields. Concentrations for this study 

were much less than the MCL for drinking water of 700 μg/L 

(U.S. Environmental Protection Agency, 2002). Field and 

laboratory studies have indicated that glyphosate is only 

slightly toxic to birds, fish, and aquatic invertebrates and does 

not bioaccumulate (Battaglin and others, 2003). Toxicity to 

aquatic organisms occurs at concentrations that are orders of 

magnitude larger than what was detected in this study.

Metolachlor

Metolachlor was a commonly used pesticide in the 

study area (table 1) and was detected in 3 of the 18 wetlands 

sampled (fig. 2). Metolachlor was one of 34 pesticides for 

which Battaglin and Goolsby (1994) estimated use in Roberts 

County in 1987. Of the 34 pesticides, metolachlor was ranked 

eighth in number of acres treated and fourth in pounds of 

active ingredient applied (table 1); however, its use in the 

midwestern United States decreased by 55 percent from 1997 

to 2001 (Battaglin and others, 2003).

Metolachlor concentrations ranged from an estimated 

0.004 to 0.027 μg/L. Metolachlor was detected in two previous 

samples from the study area (Thompson, 2002) and was 

detected in 17 wetland samples collected in 2005 from the 

Yankton Sioux Reservation at concentrations that ranged from 

0.006 to 1.89 μg/L (Schaap and Bartholomay, 2006).

Metolachlor samples for this study and other previous 

studies were collected during periods when the concentrations 

probably were at their largest concentrations because of recent 

application to fields. No MCL for drinking water has been 

established for metolachlor. Field and laboratory studies have 

indicated that metolachlor is slightly toxic to some aquatic 

species (Battaglin and Fairchild, 2002), but toxicity occurs at 

concentrations that are orders of magnitude larger than what 

was detected in this study.

Prometon

Prometon was detected in three wetlands in the study area 

(fig. 2), but was not one of 34 pesticides for which Battaglin 

and Goolsby (1994) estimated use in Roberts County in 

1987. Prometon concentrations ranged from an estimated 

0.01 to 0.03 μg/L. Prometon was not detected in previous 

samples from the study area (Thompson, 2002) nor in samples 

collected in 2005 from the Yankton Sioux Reservation (Schaap 

and Bartholomay, 2006).

Prometon samples for this study and other previous 

studies were collected during periods when the concentrations 

probably were at their largest concentrations because of recent 

application to fields. No MCL for drinking water has been 

established for prometon. Field and laboratory studies have 

indicated that prometon is slightly toxic to green algae and 

bluegill sunfish (Battaglin and Fairchild, 2002), but toxicity 

occurs at concentrations that are orders of magnitude larger 

than what was detected in this study.

Acetochlor

Acetochlor was detected in two wetlands in the study 

area (fig. 2), but was not one of 34 pesticides for which 

Battaglin and Goolsby (1994) estimated use in Roberts County 

in 1987. Battaglin and others (2003) estimated the use of 

acetochlor had increased in the midwestern United States by 

about 10 percent from 1997 to 2001. Acetochlor, which was 

detected in two environmental samples and the one replicate 

sample, had estimated dissolved concentrations that ranged 

from 0.007 to 0.009 μg/L. Acetochlor was not detected in 

previous samples from the study area (Thompson, 2002) but 

was detected in nine wetland samples collected in 2005 from 

the Yankton Sioux Reservation at concentrations that ranged 

from 0.011 to 0.039 μg/L (Schaap and Bartholomay, 2006).

Acetochlor samples for this study and other previous 

studies were collected during periods when the concentrations 

probably were at their largest concentrations because of recent 

application to fields. No MCL for drinking water has been 

established for acetochlor. Field and laboratory studies have 

indicated that acetochlor is slightly toxic to some aquatic 

species (Battaglin and Fairchild, 2002), but toxicity occurs at 

concentrations that are orders of magnitude larger than what 

was detected in this study.

Picloram

Picloram was detected in one wetland in the study area 

(fig. 2), and was one of 34 pesticides for which Battaglin and 

Goolsby (1994) estimated use in Roberts County in 1987. 

The picloram concentration was 0.05 μg/L. Picloram was not 

detected in previous samples from the study area (Thompson, 

2002) but was detected in nine wetland samples collected in 

2005 from the Yankton Sioux Reservation at concentrations 

that ranged from an estimated 0.01 to 0.88 μg/L (Schaap and 

Bartholomay, 2006).

Picloram samples for this study and other previous 

studies were collected during periods when the concentrations 

probably were at their largest concentrations because of 

application to fields. The MCL for picloram in drinking water 

is 500 μg/L (U.S. Environmental Protection Agency, 2002). 

Field and laboratory studies have indicated that picloram is 

slightly to moderately toxic to some birds, fish, and other 

aquatic species, but toxicity occurs at concentrations that are 

orders of magnitude larger than what was detected in this 

study (EXTOXNET, 2006).

20 Pesticide Concentrations in Wetlands on the Lake Traverse Reservation, South and North Dakota, July 2006
Summary

During July 2006, water samples were collected from 

selected Lake Traverse Reservation wetlands within the 

historic Reservation boundary in northeastern South Dakota 

and southeastern North Dakota as part of a reconnaissancelevel assessment by the U.S. Geological Survey (USGS) 

and Sisseton-Wahpeton Oyate (SWO). Eighteen wetlands 

were sampled by the SWO and USGS personnel after 

primary pesticide application occurred on the Lake Traverse 

Reservation. Samples were analyzed for 61 pesticides and for 

physical properties that might help further characterize the 

water quality of the wetlands.

Analysis results of the physical properties indicate 

that a wide variety of conditions occur among the wetlands. 

Turbidity ranged from 0.5 to 230 formazin nephelometric 

turbidity units. Dissolved-oxygen concentrations ranged 

from 1.4 to 18.5 milligrams per liter. The pH values ranged 

from 6.7 to 9.4. Specific conductance ranged from 272 to 

5,040 microsiemens per centimeter. Water temperature ranged 

from 18.1 to 32.7 degrees Celsius.

Pesticides were detected in 17 of the 18 sampled 

wetlands. In the 17 wetlands in which pesticides were 

detected, the number of pesticides detected ranged from two to 

eight, with a median of four. Of the 61 pesticides for which the 

samples were analyzed, 51 pesticides were not detected in any 

of the wetland samples. The 10 detected pesticides had small 

concentrations. Atrazine and de-ethyl atrazine were detected 

in samples from 17 of the 18 wetlands. Concentrations of 

dissolved atrazine ranged from 0.007 to 0.12 microgram per 

liter (μg/L). Estimated concentrations of dissolved de-ethyl 

atrazine ranged from 0.005 to 0.03 μg/L. Other pesticides that 

had concentrations that were estimated or greater than the 

laboratory reporting level included 2,4–D, which was detected 

in nine samples with dissolved concentrations that ranged 

from 0.03 to 0.11 μg/L; glyphosate, which was detected in 

five samples with dissolved concentrations that ranged from 

an estimated 0.050 to 0.3 μg/L; aminomethylphosphonic acid 

(AMPA), which was detected in five samples with dissolved 

concentrations that ranged from an estimated 0.090 to 

0.46 μg/L; metolachlor, which was detected in three samples 

with dissolved concentrations that ranged from an estimated 

0.004 to 0.027 μg/L; prometon, which was detected in three 

samples with dissolved concentrations that ranged from an 

estimated 0.01 to 0.03 μg/L; acetochlor, which was detected in 

two environmental samples and the one replicate sample, with 

estimated dissolved concentrations that ranged from 0.007 to 

0.009 μg/L; picloram, which was detected in one sample at a 

concentration of 0.05 μg/L; and simazine, which was detected 

in one sample at a dissolved concentration of an estimated 

0.002 μg/L.

None of the pesticides detected were greater than any 

U.S. Environmental Protection Agency Maximum Contaminant Levels for drinking water. Concentrations were much less 

than levels considered toxic for humans or aquatic species.

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Supplemental Information

U.S. Fish and Wildlife Service Wetlands Inventory Codes and Definitions

This Supplemental Information section provides information about U.S. Fish and Wildlife Service wetlands inventory 

codes and definitions for the selected Lake Traverse wetlands at which water samples were collected in July 2006 (table 5). The 

U.S. Fish and Wildlife Service wetlands inventory for South Dakota was last accessed November 28, 2006, at http://wetlandsfws.

er.usgs.gov/. The inventory is in the form of a geographic information system shapefile for individual U.S. Geological Survey 

quadrangles consisting of delineated wetlands and attributes of the wetlands. One of the attributes for each wetland is a code that 

indicates how the wetland had been classified in terms of various factors including geomorphology, water quality, vegetation, 

and the duration of the presence of standing water.

Of the 18 wetland sites at which water samples were collected, two (sites S15 and S18) did not have an associated primary 

wetland inventory code. Three sites, S02, S10, and S17, have been assigned to the lacustrine system; and the remaining 13 sites 

have been assigned to the palustrine system.

Table 5. U.S. Fish and Wildlife Service wetlands inventory codes for selected Lake Traverse Reservation wetlands at which waterquality samples were collected during July 2006.

Wetland code Definition Sampling sites1

(fig. 2)

Total number 

of sites

L1UBG Lacustrine, Limnetic, Unconsolidated Bottom, Intermittently Exposed S10 1

L2ABG Lacustrine, Littoral, Aquatic Bed, Intermittently Exposed S02, S17 2

PABF Palustrine, Aquatic Bed, Semipermanently Flooded S22 1

PAB/EMF Palustrine, Aquatic Bed/Emergent, Semipermanently Flooded S08 1

PEMC Palustrine, Emergent, Seasonally Flooded S12 1

PEMF Palustrine, Emergent, Semipermanently Flooded S03, S07, S13, S19 4

PEMFx Palustrine, Emergent, Semipermanently Flooded, Excavated S09 1

PEM/ABF Palustrine, Emergent/Aquatic Bed, Semipermanently Flooded S20, S21 2

PEM/ABFh Palustrine, Emergent/Aquatic Bed, Semipermanently Flooded, Diked/Impounded S04 1

PEM/SSB Palustrine, Emergent/Scrub-Shrub, Saturated S14 1

PFOC Palustrine, Forested, Seasonally Flooded S01 1

1

No wetland inventory code was assigned for sampling sites S15 or S18.

Supplemental Information 25
Manuscript approved for publication, April 20, 2007.

Prepared by the Helena Publishing Service Center.

For more information concerning the research in this report, contact:

 U.S. Geological Survey

 Director, South Dakota Water Science Center

 1608 Mountain View Road

 Rapid City, SD 57702

 http://sd.water.usgs.gov/
Neitzert and Bartholmay—Pesticide Concentrations in Wetlands on the Lake Traverse Reservation, South and North Dakota, July 2006—OFR 2007–1118

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