Wyoming Department 

of Agriculture

Printed on recycled paper

Figure 1. Pathways of pesticide movement in the hydrologic cycle (modified from Barbash 

and Resek, 1996).

In cooperation with the Wyoming Department of Agriculture (WDA) and the Wyoming Department of 

Environmental Quality (WDEQ)

In 1991, members of local, State, and Federal governments, as well as industry and interest groups, formed the 

Ground-water and Pesticide Strategy Committee to prepare the State of Wyoming’s generic Management Plan for 

Pesticides in Ground Water. Part of this management plan is to sample and analyze Wyoming’s ground water for 

pesticides. In 1995, the U.S. Geological Survey, in cooperation with the Ground-water and Pesticide Strategy Committee, began statewide implementation of the sampling component of the State of Wyoming’s generic Management Plan for Pesticides in Ground Water. During 2003-04, baseline monitoring was conducted in Albany County.

PESTICIDES IN GROUND WATER

Synthetic organic pesticides are used to 

control weeds, insects, and other organisms 

in a wide variety of agricultural and nonagricultural settings. The use of pesticides has 

helped to make the United States the world’s 

largest producer of food (Barbash and 

Resek, 1996). Pesticide use, however, has 

also been accompanied by concerns about 

potential adverse effects on the environment 

and human health. A potential pathway 

for the transport of pesticides is through 

hydrologic systems, which supply water 

for both humans and natural ecosystems. 

Water is one of the primary ways pesticides 

are transported from an application area to 

other locations in the environment (fig. 1) 

(Barbash and Resek, 1996).

Pesticide contamination of ground water 

is a national issue because of the widespread 

use of pesticides, the expense and difficulty 

of remediating ground water, and the fact 

that ground water is used for drinking water 

by about half of the Nation’s population. 

Although application rates and the variety 

of pesticides used may be greater in urban 

areas, concern over their presence in ground 

water is especially acute in rural agricultural 

areas where more than 95 percent of the 

population rely upon this resource for drinking water (Hutson and others, 2004).

WYOMING’S PESTICIDE 

MANAGEMENT PLAN

The Ground-water and Pesticide Strategy Committee (GPSC) has developed 

the generic State Management Plan for 

Pesticides in Ground Water for the State of 

Wyoming (SMP) (Wyoming Ground-water 

and Pesticides Strategy Committee, 1999). 

Wyoming was required by the U.S. Environmental Protection Agency to have a SMP 

in order for individuals and organizations 

to continue using certain pesticides in the 

State. The SMP includes information relating to individuals and organizations involved 

with implementation of the SMP, methods 

of preventing ground-water contamination, 

ground-water monitoring, and the responses 

required if pesticides are detected in ground 

water.

One critical part of the SMP is groundwater monitoring. This ground-water 

monitoring program has two phases. The 

first phase, baseline monitoring, is designed 

to determine what pesticides, if any, have 

leached into the county’s ground water. The 

second phase, problem identification monitoring, is used to gather additional information about the ground water near wells 

with samples having significant pesticide 

detections.

Pesticides in Ground Water - Albany County, Wyoming, 2003-04

U.S. Department of the Interior

U.S. Geological Survey

USGS Fact Sheet 2005-3087

July 2005

Wyoming Department of 

Environmental Quality, 

Water Quality Division
Table 1. Summary of baseline monitoring for pesticides in Albany County, September 2003 and April 2004.

[μg/L, micrograms per liter; NA, not applicable; T, trace concentration, value is estimated; C, estimated value used in calculation]

Pesticide

Pesticide

trade name Pesticide action1

Number of

detections/

number of

samples2

Laboratory 

minimum

reporting level3

(μg/L)

Maximum

concentration

(μg/L)

Average

concentration

of detections

(μg/L)

Safe drinking

water

standard4

(μg/L)

Focal pesticides detected in Albany County ground water

Atrazine Aatrex Selective herbicide 3/22 0.007 0.02 0.01C 3

Clopyralid Stinger, Curtail Herbicide 3/22 0.01 0.5 0.2 1,000

Picloram Tordon Systemic herbicide 4/22 0.02 0.2 0.1 70

Simazine Princep Selective herbicide 3/22 0.005 0.01 0.008 4

Tebuthiuron Spike Herbicide 9/22 0.02 1.2 0.4C 5

500

Non-focal pesticides detected in Albany County ground water

Diuron Durashield Herbicide 1/22 0.01 0.01T NA 610

Malathion Malaspray Insecticide 1/22 0.03 0.007T NA 5100

Prometon Pramitol Non-selective herbicide 10/22 0.02 0.4 0.1C 5100

Focal pesticides not detected in Albany County ground water

2,4-D, Alachlor, Aldicarb, Aldicarb Sulfone7

, Aldicarb Sulfoxide7, Bromacil, Cyanazine,

DCPA, Dicamba, Hexazinone, Metalachlor, Metribuzin, Metsulfuron, Telone

Focal pesticides not analyzed in Albany County ground water (no method of analysis available)

Difenzoquat

1

Meister (2002)

2

Each of the 11 wells was sampled twice.

3

The laboratory minimun reporting level is the lowest concentration at which a 

pesticide concentration can be quantified without estimation.

4

U.S. Environmental Protection Agency Maximum Contaminant Level unless 

otherwise noted (U.S. Environmental Protection Agency, 2002).

5

U.S. Environmental Protection Agency Lifetime Health Advisory Level 

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

6

U.S. Environmental Protection Agency Drinking Water Equivalent Level 

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

7

Degradation product of aldicarb.

Baseline monitoring is prioritized by 

a county rank and the vulnerability of the 

county’s ground water to pesticides. During 

the development of the SMP, the GPSC evaluated each county in Wyoming to determine 

the potential vulnerability of the county’s 

ground water to pesticides. Each county was 

ranked according to the extent of cropland 

and urban areas in the county, as well as the 

amount of pesticides sold within the county in 

1991 (Wyoming Ground-water and Pesticides 

Strategy Committee, 1999).

A ground-water vulnerability map was 

prepared for the uppermost or shallowest 

aquifer (Hamerlinck and Arneson, 1998). A 

Geographic Information System was used to 

overlay seven layers describing hydrogeology 

and land use. Ground water is more vulnerable because of either inherent sensitivity of 

the hydrogeology, or because of the combination of the sensitivity and associated land use. 

The map was used to assist in the selection of 

monitoring sites in each county. The monitoring focuses on areas where the ground water 

is most vulnerable.

The GPSC selected 18 pesticides (focal 

pesticides) and 2 degradation products to be 

sampled as part of the SMP (table 1). The 

analytical method used to detect the focal 

pesticides can also detect 66 other pesticides 

and degradation products. Any additional 

pesticides detected are listed in table 1 as 

non-focal pesticides. Ground water from all 

wells in the baseline monitoring program was 

analyzed for the pesticides listed in table 1, 

with the exception of difenzoquat, for which 

analytical methods are not available.

The goal of the ground-water sampling 

part of the SMP is to collect ground-water 

samples for pesticide analyses in all 23 Wyoming counties. To date, sampling has been 

completed in Goshen (1995-96), Park (1997), 

Washakie (1997-98), Fremont (1998-99), 

Lincoln (1998-99), Laramie (1998-99), Big 

Horn (1999-2000), Sheridan (1999-2000), 

Platte (2000-01), Johnson (2000-01), Crook 

(2000-01), Natrona (2001-02), Sweetwater 

(2001-02), Teton (2001-02), Uinta (2002-03), 

Albany (2003-04), Converse (2003-04), and 

Hot Springs (2003-04) Counties. Sampling 

began in 2004 in Carbon, Campbell, and 

Sublette Counties.

GROUND-WATER MONITORING IN 

ALBANY COUNTY

The ground water in Albany County was 

ranked seventeenth most vulnerable to pesticide contamination in Wyoming (Wyoming 

Ground-water and Pesticide Strategy Committee, 1999). The vulnerability map created 

by the Spatial Data and Visualization Center 

(Hamerlinck and Arneson, 1998), identifies 

ground water found in unconsolidated Quaternary (primarily alluvial and terrace deposits) 

and Tertiary deposits in the county with urban 

and agricultural land use as well as mountainous areas in the county as the most vulnerable to pesticides (shown as red on fig. 2). 

The focus of the sampling was in the alluvial 

and terrace deposits of the Laramie and Little 

Laramie Rivers (fig. 3). The mountainous 

areas were not sampled because, although the 

hydrogeology makes the ground water susceptible to contamination, the land use does not 

create a large potential for contamination.

Eleven wells were selected in Albany 

County (fig. 3) for baseline monitoring. Ten 

wells were located in the Quaternary and Tertiary unconsolidated deposits, and one well was 

located in the Permian Santaka Formation. 
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Figure 2. Vulnerability of Albany County, Wyoming ground water to pesticide 

contamination (from Hamerlinck and Arneson, 1998).

All wells were sampled in September 2003 and 

April 2004.

Five of the 19 focal pesticides or degradation products and 3 non-focal pesticides were 

detected in Albany County (table 1). Pesticides 

were detected in 6 of the 11 wells sampled in 

Albany County; however the concentrations of 

each pesticide detected were less than 1/150 of the 

applicable drinking-water standard (U.S. Environmental Protection Agency, 2002) (table 1). About 

one-fifth of the detections were less than the 

minimum reporting level, at trace concentrations. 

A trace concentration indicates that the pesticide 

was detected, but at a concentration too small to 

quantify without estimation. Trace concentrations 

are qualified with a “T” in table 1, if the result was 

considered an estimate due to analytical uncertainty.

The most commonly detected pesticide (10 of 

22 samples) in Albany County was prometon, the 

active ingredient in Pramitol, a general-use pesticide. Prometon’s detection is typically associated 

with urban land use (Barbash and others, 1999). 

Prometon was also the most commonly detected 

pesticide in Sheridan, Crook, Johnson, Natrona, 

Teton, Uinta, and Converse Counties.

The second most commonly detected pesticide 

in Albany County was tebuthiuron (detected in 9 

of 22 samples). Tebuthiuron is an herbicide used 

in noncropland areas, rangeland, and right-ofways (Meister, 2002).

DATA DISTRIBUTION AND 

AVAILABILITY

Sampling results have been provided to local 

groups interested in pesticides in ground water in 

Albany County. The information can be used by 

citizens and local governments to help understand current conditions. Analytical results of the 

Albany County sampling can be found in Swanson and others (2004), and Blajszczak and others 

(2005), or on the internet at http://waterdata.usgs.

gov/wy/nwis/qwdata. Analytical results and fact 

sheets for all counties sampled to date are available from the U.S. Geological Survey in Cheyenne 

either by phone, email, or on the internet at 

http://wy.water.usgs.gov/projects/pesticide/.

REFERENCES

Barbash, J.E., and Resek, E.A., 1996, Pesticides in ground 

water: Distribution, trends, and governing factors: in

Gilliom, R.J., ed., Pesticides in the hydrologic system 

(v. 2): Lewis Publishers, 590 p.

Barbash, J.E., Thelin, G.P., Kolpin, D.W., and Gilliom, R.J., 

1999, Distribution of major herbicides in ground water 

of the United States: U.S. Geological Survey WaterResources Investigations Report 98-4245, 64 p.

Blajszczak, E.J., Mason, J.P., Watson, K.R., Roberts, S.C., 

and Miller, K.A., 2005, Water-resources data, Wyoming, 

water year 2004, Volume 2. Ground Water: U.S. Geological Survey Water-Data Report WY-04-2.
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Figure 3. Location of wells sampled in Albany County, Wyoming, and notation of 

pesticide detection in each well.

Hamerlinck, J.D., and Arneson, C.S., eds., 1998, Wyoming ground water vulnerability assessment handbook: Volume 2. Assessing ground water vulnerability to pesticides: University of Wyoming, Laramie, 

Spatial Data and Visualization Center Publication 

SDVC 98-01-2, variable pagination.

Hutson, S.S., Barber, N.L., Kenny, J.F., Linsey, K.S., 

Lumia, D.S., and Maupin, M.A., 2004, Estimated use 

of water in the United States in 2000: U.S. Geological Survey Circular 1268, 46 p.

Meister, R.T., 2002, Farm Chemicals Handbook: Willoughby, Ohio, Meister Publishing Co., variable 

pagination.

Swanson, R.B., Blajszczak, E.J., Roberts, S.C., Watson, 

K.R., and Mason, J.P., 2004, Water-resources data, 

Wyoming, water year 2003, Volume 2. Ground 

Water: U.S. Geological Survey Water-Data Report 

WY-03-2, 141 p.

U.S. Environmental Protection Agency, 2002, Drinking 

water regulations and health advisories: EPA 822-R02-038.

Wyoming Ground-water and Pesticides Strategy Committee, 1999, Wyoming generic state management 

plan for pesticides and ground water: prepared for 

Wyoming Department of Agriculture, Cheyenne, 

Wyoming, 103 p.

• Prepared by Cheryl A. Eddy-Miller and 

Kendra J. Remley

• Layout prepared by Suzanne C. Roberts

FOR MORE INFORMATION, CONTACT:

Roy Reichenbach

Wyoming Department of Agriculture

2219 Carey Avenue

Cheyenne, Wyoming 82002

(307) 777-6590

Kevin Frederick

Wyoming Department of Environmental 

Quality, Water Quality Division

Herschler Building West, 4th Floor

Cheyenne, Wyoming 82002

(307) 777-5985

Cheryl Eddy Miller

U.S. Geological Survey

2617 E. Lincolnway, Suite B

Cheyenne, Wyoming 82001

(307) 778-2931

Email: cemiller@usgs.gov

This document was prepared by the U.S. Geological Survey 

(USGS), the Wyoming Department of Agriculture (WDA), 

and the Wyoming Department of Environmental Quality, 

Water Quality Division (WDEQ). All agencies are members 

of the Ground-water and Pesticide Strategy Committee.

This project has been funded in part with a Section 319 

grant from the U.S. Environmental Protection Agency to 

Wyoming Department of Environmental Quality’s NonPoint Source Program.

The use of trade, product, industry, or firm names is for 

descriptive purposes only and does not imply endorsement 

by the U.S. Government.