90

25

25

80

20

26

26

16

85

80

80

16

85

287

14

191

189

14

30

89

89

90

287

287

Cody

Kane

Basin

Casper

Lander

Lovell

Laramie

Rawlins

Worland

Buffalo

Cheyenne

Evanston

Riverton

Gillette

Sheridan

Wheatland

Newcastle

Torrington

Thermopolis

Rock

Springs

Jackson

Douglas

Saratoga

Wind

River

River

River

Boysen

Reservoir River

Yellowstone

 Lake

Jackson

 Lake

Green

River

Fontenelle

Reservoir

Flaming Gorge Reservoir

River

Belle Fourche

River

Powder

Greybull

Shoshone

Bighorn

Nowood

River

River

Cheyenne

River

Platte

North

River

Pathfinder

Reservoir

Seminoe

 Reservoir River

Laramie

Snake River

Sweetwater

Grayrocks

Reservoir

0

0

50

50

100 MILES

100 KILOMETERS

Base modified from U.S. Geological Survey Digital Chart of the World 

digital data, 2002

Albers Equal-Area Conic projection, Standard parallels 29o30a and 45o30a,

central meridian -107o30a

06674500

06664000

06285100

06274300

Sampling site and number

EXPLANATION

06664000

06279500

44°

45°

111° 110° 109° 108° 107° 106° 105o

43°

42°

41o

North Platte

River Basin

Bighorn River

Basin

Figure 1.  Location of sampling sites in the Bighorn and North Platte River Basins, Wyoming.

Wyoming Department

of Agriculture

U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2007–3017

March 2007

In cooperation with the Wyoming Department of Agriculture (WDA)

Pesticides in Surface Water in the Bighorn and North Platte 

River Basins, Wyoming, 2006

By Cheryl A. Eddy-Miller, Gregory K. Boughton, and R.E. Woodruff

Printed on recycled paper

Introduction

In 2006, the U.S. Geological 

Survey (USGS), in cooperation with 

the Wyoming Department of Agriculture, sampled five surface-water sites 

in Wyoming—three in the Bighorn 

River Basin (BRB) and two in the 

North Platte River Basin (NPRB) 

(fig. 1). The purpose of the sampling 

was to describe the occurrence of 

pesticides in these basins during 

three different times of the year. This 

fact sheet presents the results of the 

sampling.

Approach

Three samples were collected 

from each site, one each in March, 

May, and September 2006 (table 1; 

fig. 2). The sampling events corresponded with pre-application of pesticides, post application of pesticides, 

and late growing season. The samples 

were collected using standard methods 

described in the National Field Manual 

for the Collection of Water-Quality 

Data (U.S. Geological Survey, 1997 

to 2004) and analyzed at the USGS 

National Water Quality Laboratory, to 

determine the presence and concentration of 132 different pesticides and 

degradation products (table 2) (Furlong and others, 2001, and Sandstrom 

and others, 2001).

Site Descriptions

Four of the five selected sites were located at the farthest 

downstream site available on the river in order to integrate drainage 

from as much land use in the river basin as possible. The fifth site 

is located on the mainstem of the Bighorn River at Basin (station 

number 06274300). This additional site on the Bighorn River was 

selected because of the large drainage area of the river.

All sampling locations in the BRB were located at sites with 

active streamflow-gaging stations. The sampling site near Torrington (station number 06674500) in the NPRB was located at 

an active gaging station. The Laramie River sampling site near 

Wheatland (station number 06664000), is a historic gaging station, 

but was not active at the time of sampling. This sampling site is 

the farthest downstream site on the Laramie River with an active or 

inactive gaging station, that is upstream from Grayrocks Reservoir.

Results

Samples collected in both the BRB and NPRB contained 

detectable concentrations of pesticides for all three sampling 

events. Eighteen different pesticides and degradation products were 

detected (table 1).

Sixteen different pesticides were detected in water samples 

collected in the BRB. The most commonly detected pesticide was 

atrazine, a selective herbicide commonly applied to corn, grains, 

and sorghum (Meister, 2002), detected at low concentrations in all 

nine samples collected in the BRB. The pesticide with the largest 

concentration in the BRB was the herbicide MCPA (trade names 
Table 1.  Pesticides detected in samples from five surface-water sites in the Bighorn and North Platte River Basins—March, May, and September 2006.

[ft3/s, cubic feet per second; mg/L, milligrams per liter; μS/cm, microsiemens per centimeter; μg/L, microgram per liter; <, less than, indicates chemical was not detected, and the value following the less than is the laboratory reporting level; E, value is estimated; M, presence verified but not quantified; tan rows, Bighorn River Basin sites; blue rows, North Platte River Basin sites]

Station name and number Date

Time

(24 

hour)

Instantaneous 

discharge 

(ft3/s)

Dissolved 

oxygen, 

(mg/L) 

pH 

(standard 

units)

Specific 

conductance 

(μS/cm)

Water 

temperature 

(degrees

Celsius)

Aldicarb 

sulfoxide 

(μg/L)

Atrazine 

(μg/L)

Bentazon 

(μg/L)

Bromoxynil 

(μg/L)

Carbofuran 

(μg/L)

Chlorodiamino-striazine

(μg/L)

Bighorn River at Basin, Wyo.06274300

3/23/2006 1200 1,090 11.7 8.3 982 6.7 <0.022 E0.006 <0.01 <0.03 <0.02 <0.04

5/18/2006 1030 1,600 8.4 8.1 445 16.5 E.004 E.007 <.02 E.01 <.02 <.04

9/14/2006 1030 560 10.0 8.5 984 16.5 E.014 E.006 M <.04 <.02 <.04

Bighorn River at Kane, Wyo.06279500

3/23/2006 1730 1,230 11.2 8.3 1,000 8.7 <.022 E.006 <.01 <.03 <.02 <.04

5/18/2006 1415 1,950 7.9 8.0 539 20.0 E.004 .01 <.02 M <.02 <.04

9/14/2006 1430 710 9.6 8.5 1,030 19.0 E.013 E.006 <.02 <.04 <.02 <.04

Shoshone River near Lovell, 

Wyo.

06285100

3/24/2006 1400 427 12.0 8.2 909 8.5 <.022 E.006 <.01 <.03 <.02 <.04

5/18/2006 1730 430 9.5 8.6 676 21.0 E.008 E.006 <.02 E.01 <.02 <.04

9/14/2006 1730 490 10.5 8.7 725 17.5 E.012 E.006 E.01 <.04 E.014 <.04

Laramie River near Wheatland06664000

3/13/2006 1645 18 12.5 8.3 530 3.0 <.022 <.007 <.01 <.03 <.02 <.04

5/26/2006 1400 3.6 8.1 8.2 790 22.6 <.10 <.007 <.02 <.04 <.02 <.04

9/29/2006 1330 6.7 9.3 8.4 750 15.0 <.10 E.007 <.02 <.04 <.02 <.04

North Platte River at WyomingNebraska State line06674500

3/13/2006 1215 118 11.1 8.1 938 6.5 <.022 E.007 <.01 <.03 <.02 E.05

5/26/2006 0930 156 8.3 8.2 859 17.5 <.10 E.008 <.02 <.04 <.02 <.04

9/29/2006 1100 260 8.9 8.3 920 13.0 <.10 .009 <.02 <.04 <.02 <.04

Station name and number Date

Time

(24 

hour)

2-Chloro4-isopropylamino6-amino-s-triazine 

(μg/L)

4-Chloro2-methylphenol 

(μg/L)

Cycloate 

(μg/L)

2,4-D 

(μg/L) 

EPTC

(μg/L)

Hexazinone

(μg/L)

MCPA

(μg/L) 

Metolachlor

(μg/L)

Metribuzin 

(μg/L)

Prometon 

(μg/L)

Simazine 

(μg/L)

Trifluralin 

(μg/L)

Bighorn River at Basin, Wyo.06274300

3/23/2006 1200 <0.006 <0.006 <0.01 <0.04 <0.004 <0.013 <0.03 <0.006 <0.006 <0.01 <0.005 <0.009

5/18/2006 1030 <.014 E.005 <.01 E.06 E.004 <.026 .15 <.006 E.009 <.01 <.005 <.009

9/14/2006 1030 E.007 <.005 <.01 E.01 <.004 <.026 <.07 <.006 <.028 M <.005 <.009

Bighorn River at Kane, Wyo.06279500

3/23/2006 1730 <.006 <.006 <.01 <.04 <.004 <.013 <.03 <.006 <.006 <.01 <.005 <.009

5/18/2006 1415 <.014 E.005 <.01 E.1 <.004 <.026 .1 <.006 E.007 <.02 <.007 <.009

9/14/2006 1430 E.007 <.005 <.01 <.04 <.004 <.026 <.07 E.005 <.028 .03 <.005 <.009

Shoshone River near Lovell, 

Wyo.

06285100

3/24/2006 1400 <.006 <.006 <.01 <.04 <.004 .013 <.03 E.005 <.006 <.01 <.005 <.009

5/18/2006 1730 <.014 <.005 .12 E.02 .071 E.011 E.01 <.006 .13 <.01 <.005 <.009

9/14/2006 1730 <.014 <.005 <.01 E.02 <.004 <.026 <.07 <.006 <.028 <.01 <.005 E.006

Laramie River near Wheatland, 

Wyo.

06664000

3/13/2006 1645 <.006 <.006 <.01 <.04 <.004 <.013 <.03 <.006 <.006 <.01 <.005 <.009

5/26/2006 1400 <.014 <.005 <.01 <.04 <.004 <.026 <.07 <.006 <.028 <.01 <.005 <.009

9/29/2006 1330 <.014 <.005 <.01 <.04 <.004 <.026 <.07 E.009 <.028 E.01 .08 <.009

North Platte River at WyomingNebraska State line06674500

3/13/2006 1215 E.011 <.006 <.01 <.04 <.004 .014 <.03 <.006 <.006 E.01 <.005 <.009

5/26/2006 0930 E.007 <.005 <.01 <.04 E.005 E.015 <.07 E.005 <.028 <.01 <.005 <.009

9/29/2006 1100 <.014 <.005 <.01 <.04 <.004 E.013 <.07 E.007 <.028 <.01 <.005 <.009
0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

5,000

5,500

Bighorn River at Kane, Wyo.

Station 06279500

Jan.

Jan.

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

Bighorn River at Basin, Wyo.

Station 06274300

DAILY MEAN DISCHARGE, IN CUBIC FEET PER SECOND

Oct. Nov. Dec.

2005 2006

Feb. Mar. Apr. May June July Aug. Sept.

Oct. Nov. Dec.

2005 2006

Feb. Mar. Apr. May June July Aug. Sept.

Bighorn River Basin sites

Jan.

Shoshone River near Lovell, Wyo.

Station 06285100

0

1,500

2,000

2,500

3,000

3,500

4,000

500

1,000

Oct. Nov. Dec.

2005 2006

Feb. Mar. Apr. May June July Aug. Sept.

Oct. Nov. Dec.

2005 2006

Jan. Feb. Mar. Apr. May June July Aug. Sept.

North Platte River at Wyoming-Nebraska 

 State line

Station 06674500

-200

200

0

400

600

800

1,000

1,200

1,400

1,600

1,800

Oct. Nov. Dec.

2005 2006

Feb. Mar. Apr. May June July Aug. Sept.

INSTANTANEOUS DISCHARGE, 

IN CUBIC FEET PER SECOND

0

2

4

6

8

10

12

14

16

18

20

Laramie River near 

 Wheatland, Wyo.

Station 06664000

EXPLANATION

Dates when sampling occurred

DAILY MEAN DISCHARGE, IN CUBIC FEET PER SECOND

North Platte River Basin sites

Jan.

Figure 2.  Daily mean discharge or instantaneous discharge

(station 06664000 only) for sampled streams in the Bighorn and

North Platte River Basins, water year 2006.

Solve and MCP), which was detected in a May sample at a concentration of 0.15 μg/L (micrograms per liter).

Eight different pesticides were detected in water samples 

collected in the NPRB. The most commonly detected pesticide was 

atrazine, detected in four of six samples collected in the NPRB. 

The pesticide with the largest concentration in the NPRB was the 

selective herbicide simazine (trade names Aquazine and Princep), 

which was detected in a September sample at a concentration of 

0.08 μg/L.

References

Furlong, E.T., Anderson, B.D., Werner, S.L., Soliven, P.P., Coffey, L.J., 

and Burkhardt, M.R., 2001, Methods of analysis by the U.S. Geological 

Survey National Water Quality Laboratory--Determination of pesticides 

in water by graphitized carbon-based solid-phase extraction and highperformance liquid chromatography/mass spectrometry: U.S. Geological 

Survey Water-Resources Investigations Report 01-4134, 73 p.

Meister, R.T., 2002, Farm Chemicals Handbook: Willoughby, Ohio, Meister Publishing Co., variable pagination.
For additional information on the project, visit the USGS 

Wyoming Water Science Center web site at http://wy.water.

usgs.gov/projects/pesticide/sw/ or contact:

Roy Reichenbach Wyoming Department of 

Agriculture

2219 Carey Avenue

Cheyenne, Wyoming 

82002

(307) 777-6590

Table 2.  Pesticides and degradation products analyzed for in samples.

[Pesticide trade names1 in parentheses if different from pesticide name; pesticides in color were detected in the corresponding basin: tan, Bighorn River Basin; 

blue, North Platte River Basin; dark red, both basins]

Pesticide name 

Acetochlor (Guardian, Harness, Relay)

Acifluorfen (Blazer, Tackle 2S, Astic)

Alachlor (Alanex, Lasso, Shroud)

Aldicarb (Temik)

Aldicarb sulfone (Standak, Aldicarb degradation product)

Aldicarb sulfoxide (Aldicarb degradation 

product)

Atrazine (Aatrex, Atranex)

Azinphos-methyl (Guthion, Crysthyon)

Azinphos-methyl-oxon (Azinphos-methyl 

degradation product)

Barban

Bendiocarb (Ficam, Garrox, Turcam)

Benfluralin (Balan, Benefin)

Benomyl (Benlate, Benex)

Bensulfuron-methyl (Escuri, Londax)

Bentazon (Basagram, Bentzone)

Bromacil (Hyvar X)

Bromoxynil (Buctril, Brominal, Agristar)

Carbaryl (Carbatox, Sevin)

Carbofuran (Furadan, Futura)

Chloramben, methyl ester (Chloramben)

Chlordiamino-s-triazine {CAAT} (Atrazine 

degradation product)

Chlorimuron-ethyl (Classic, Darban, Lory)

2-Chloro-2,6-diethylacetanilide (Alachlor 

degradation product)

2-Chloro-4-isopropylamino-6-amino-striazine {CIAT} (Atrazine degradation product)

2-Chloro-6-ethylamino-4-amino-s-triazine 

{CEAT} (Atrazine degradation product)

4-Chloro-2-methylphenol (MCPA degradation product)

3(4-Chlorophenyl)-1-methyl urea (Diuron 

degradation product)

Chlorpyrifos (Dursban, Lorsban)

Clopyralid (Stinger, Lontrel)

Cyanazine (Bladex)

Cycloate (Ro-Neet)

Pesticide name 

Cyfluthrin (Decathlon)

Cypermethrin

2,4-D (Dacamine, Weed-B-Gon)

2,4-D methyl ester

2,4-DB (Butoxone, Butyrac)

Dacthal

Dacthal monoacid (Dacthal degradation 

product)

Desulfinylfipronil (Fipronil degradation 

product)

Desulfinylfipronil amide (Fipronil degradation product)

Diazinon (Basudin, Spectracide, Knoxout)

Dicamba (Banvel, Banex)

3,4-Dichloroaniline (Chloramben degradation product)

3,5-Dichloroaniline (Diuron degradation 

product)

Dichlorprop (Weedone, Polymone)

Dichlorvos (DDVP)

Dicrotophos (Bidrin)

Dieldrin (Panoram D-31, Octalox)

2,6-Diethylaniline (Alachlor degradation 

product)

Dimethoate (Trounce)

Dinoseb (Premerge)

Diphenamid (Dymid, Enide)

Disulfoton (Di-Syston)

Disulfoton sulfone (Disulfoton degradation 

product)

Diuron (Durashield, Karmex)

alpha-Endosulfan (Thiodan, Tiovel)

Endosulfan sulfate (alpha-Endosulfan 

degradation product)

EPTC (Eptam, Eradicane)

Ethion (Ethanox, Rhodocide)

Ethoprophos (Mocap, Prophos)

2-Ethyl-6-methylaniline (Metalachlor 

degradation product)

Fenamiphos

Fenamiphos sulfone (Fenamiphos degradation product)

Pesticide name 

Fenamiphos sulfoxide (Fenamiphos degradation product)

Fenuron

Fipronil (Regent)

Fipronil sulfide (Fipronil degradation 

product)

Fipronil sulfone (Fipronil degradation 

product)

Flumetsulam (Broadstrike)

Fluometuron (Cotoran)

Fonofos (Dyfonate)

Hexazinone (Velpar)

3-Hydroxycarbofuran (Carbofuran degradation product)

2-Hydroxy-4-isopropylamino-6-ethylamino-s-triazine {OIET} (Atrazine 

degradation product)

Imazaquin (Scepter)

Imazethapyr (New Path, Pursuit)

Imidacloprid (Admire, Provado)

Iprodione (Kidan)

Isofenphos (Oftanol, Lighter)

lambda-Cyhalothrin (Charge, Karate)

Linuron (Linurex, Lorox)

Malaoxon (Malathion degradation product)

Malathion (Cythion, Malaspray)

MCPA (Solve, MCP)

MCPB (Butoxone M40, Thistrol)

Metalaxyl (Apron, Ridamil, Subdue)

Methidathion (Supra)

Methiocarb (Mesurol)

Methomyl (Lannate, Nudrin)

Metolachlor (Bicep, Dual)

Metribuzin (Lexone, Sencor)

Metsulfuron methyl (Ally, Escort)

Molinate (Hydram, Ordram)

Myclobutanil (Eagle, Nova)

1-Naphthol (Carbaryl degradation product)

Neburon (Granurex, Propuron)

Pesticide name 

Nicosulfuron (Accent, OneHope)

Norflurazon (Zorial, Solicam)

Oryzalin (Surflan)

Oxamyl (Vydate)

Oxyfluorfen (Offside, Goal)

Paraoxon-methyl (Parathion-methyl degradation product)

Parathion-methyl (Alkron, Bladan, Fighter)

Pendimethalin (Prowl, Stomp)

cis-Permethrin (Ambush, Pounce)

Phorate (Thimet, Rampart)

Phosmet (Imidan)

Picloram (Tordon)

Prometon (Pramitol, Gesafram)

Prometryn (Cotton-pro)

Propanil (Stamp)

Propargite (Comite, Omite)

Propham (Chem Hoe)

Propiconazole (Banner)

cis-Propiconazole (Banner)

trans-Propiconazole (Banner)

Propoxur (Baygone, Suncide)

Propyzamide (Kerb)

Siduron (Tupersan)

Simazine (Aquazine, Princep)

Sulfometuron-methyl (Oust)

2,4,5-T

Tebuconazole (Elite)

Tebuthiuron (Graslan, Spike)

Tefluthrin (Force)

Terbacil (Sinbar, Herbicide 732)

Terbufos (Counter, Contraven)

Terbuthylazine (Gardoprim)

Thiobencarb (Bolero, Saturn)

Tribufos (DEF 6)

Triclopyr (Garlon)

Trifluralin (Treflan, Trim)

Cheryl A. Eddy-Miller

U.S. Geological Survey

2617 E. Lincolnway, Suite B

Cheyenne, Wyoming 82001

(307) 778-2931

Email: cemiller@usgs.gov

1

The use of trade, product, industry, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government or the Wyoming State 

Government.

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.

U.S. Geological Survey, 1997 to 2004, National field manual for the collection of water-quality data: U.S. Geological Survey Techniques of 

Water-Resources Investigations, book 9, chaps. A1-A9, 2 v., variously 

paged. [Also available online at http://pubs.water.usgs.gov/twri9A. 

Chapters originally were published from 1997–1999; updates and revisions are ongoing and are summarized at: http://water.usgs.gov/owq/ 

FieldManual/mastererrata.html]