| |  | Wyoming Department of Agriculture (WDA) |  | Wyoming Department of Environmental Quality (WDEQ), Water 
      Quality Division
| |  | --------------------------------------- |  | ---------------------------------------------------------------------------------

#### In cooperation with the Wyoming Department of Agriculture (WDA), the Wyoming 
Department of Environmental Quality (WDEQ), and the Laramie County Conservation 
District

# Pesticides in Ground Water - Laramie County, Wyoming, 
1998-99

#### USGS Fact Sheet 034-00 (format modified)

*pdf icon This fact sheet is also available in pdf 
format:*   fs03400.pdf 
*(3.3 mb)*

---

## Contents

- Pesticides in 
  Ground Water
- Wyoming's 
  Pesticides Management Plan
- Ground-water 
  Monitoring in Laramie County
- Monitoring 
  Status and Data Availability
- References
- More Information

---

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. In 1998, 
baseline monitoring began in Laramie 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). | Figure1
      **Figure 1.** Pathways of pesticide movement 
      in the hydrologic cycle (modified from 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 50 
percent of the Nation's population. Concern about pesticides in ground water is 
especially acute in rural agricultural areas where over 95 percent of the 
population relies upon ground water for their drinking water (Solley and others, 
1998), although application rates and the variety of pesticides used may be 
greater in urban areas.

---

### WYOMING'S PESTICIDES 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). 
The SMP is required by the U.S. Environmental Protection Agency (EPA) in order 
for individuals and organizations to continue using certain pesticides in 
Wyoming. The SMP includes information relating to individuals and organizations 
involved with the implementation of the SMP, methods of preventing ground-water 
contamination, ground-water monitoring, and what the responses will be if 
pesticides are detected in ground water.

One critical part of the SMP is ground-water monitoring. The ground-water 
monitoring program has two phases. The first phase involves baseline monitoring, 
which is an initial survey of pesticides in a county's ground water. The second 
phase is problem identification monitoring, which is used to gather more 
information about the ground water near wells with significant pesticide 
detections.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 
based on 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 by the University of Wyoming Spatial Data and Visualization Center 
(SDVC). A Geographic Information System was used to overlay seven coverages 
describing hydro- geology and land use. The map pro- duced 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). An additional 66 pes ticides and degradation products are 
included in the U.S. Geological Survey analytical protocol, resulting in 
possible detections of non-focal pesticides. Ground water from all wells in the 
base- line monitoring program was analyzed for the pesticides listed in table 1, 
with the exception of difenzoquat and metsulfuron because analytical methods 
were not available for their analysis.

The goal of the sampling program is to collect ground-water samples for 
pesticide analyses in all 23 Wyoming counties. The ground-water sampling part of 
the SMP began in Goshen County in 1995. Sampling in Park and Washakie Counties 
was conducted in 1997, and completed by 1998. In August 1998, sampling began in 
Fremont, Lincoln, and Laramie Counties. The sampling for these three counties 
was completed in May 1999.



Table 1. Baseline monitoring for pesticides in Laramie 
County, 1998-99.(Click on image for a larger version, 108kb jpg)

---

### GROUND-WATER MONITORING IN LARAMIE 
COUNTY

|The ground water in Laramie County was ranked the sixth most vulnerable 
      to to pesticide contamination in Wyoming. The vulnerability map for 
      Laramie County (fig. 2) was created by the SDVC (Hammerlink and Arneson, 
      1998). Shallow alluvial and terrace deposits, and urban and suburban areas 
      in and near Cheyenne were identified as the most vulnerable areas in the 
      county.
      Sixteen sites were selected for baseline monitoring in Laramie County 
      (fig. 3). All wells were located in the most vulnerable areas (shown as 
      red and yellow in fig. 2). The wells were inspected and selected with the 
      assistance of the Laramie County Conservation District. All sites were 
      sampled twice, late summer 1998 and spring 1999. These time periods were 
      selected to correspond with the shallowest or deepest water-table 
      conditions.                                                                  | **Figure 2.** Vulnerability of Laramie County 
      ground water to pesticide contamination (from Hammerlink and Arneson, 
      1998).*(Click on image for a larger version, 176kb 
  jpg)*
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|Nine of the 18 focal pesticides and 
      2 non-focal pesticides were detected in Laramie County (table 1). At least 
      one pesticide was detected in 11 of the 16 wells sampled in Laramie 
      County. All concentrations of pesticides were less than the drinking water 
      standards (U.S. Environmental Protection Agency, 1996). The laboratory 
      minimum reporting limit is the lowest concentration at which the pesticide 
      can be quantified. One-third of the detections were trace quantities. A 
      trace quantity indicates the pesticide was detected, but at a 
      concentration too small to quantify. The most commonly 
      detected pesticide in Laramie County was atrazine. Atrazine was also the 
      most commonly detected pesticide in Goshen, Park, Washakie, and Fremont 
      Counties. Atrazine is an agricultural herbicide typically used for weed 
      control in corn and other crops (Farm Chemicals Handbook, 1996). | **Figure 3.** Location of wells sampled in Laramie County, 
      and notation of pesticide detection in each well.*(Click on image 
      for a larger version, 104kb jpg)*                 

Other frequently detected pesticides in Laramie County were picloram and 
prometon. Picloram is the active ingredient in Tordon and prometon is the active 
ingredient in Pramitol. Picloram was detected in 5 wells in Laramie County, all 
of which were located in rural settings. Picloram was the pesticide detected at 
highest concentration in Laramie County ground water at 4 micrograms per liter 
(parts per billion). Picloram, an herbicide, is one of the most commonly used 
pesticides in Wyoming. Prometon was detected in four wells in the county, three 
of which were located within the city of Cheyenne. Prometon is a general use 
pesticide and its detection is typically associated with urban land use (Barbash 
and others, 1999).

---

### MONITORING STATUS AND DATA 
AVAILABILITY

The sampling results have been given to local groups interested in pesticides 
in ground water in Laramie County. The information can be used by citizens and 
local governments to help understand current conditions. Results of the Laramie 
County sampling can be found in Mason and others, 1999, and Swanson and others, 
2000. Results of all analyses, including sampling of all counties to date, are 
available from the U.S. Geological Survey in Cheyenne.

---

### REFERENCES

Barbash, J.E., and Resek, E.A., 1996, Pesticides in ground 
water--Distribution trends, and governing factors: Ann Arbor Press, Chelsea, 
Michigan, p. 3

Barbash, J.E., Thelin, G.P., Kolpin, D.W., and Gillom, R.J., 
1999, Distribution of major herbicides in ground water of the United States: 
U.S. Geological Survey Water-Resources Investigations Report98-4245, 64 
p.

Hammerlink, J.D., and Arneson, C.S., editors, 1998, Wyoming 
ground water vulnerability assessment handbook: Volume 2. Assessing ground water 
vulnerability to pesticides: Spatial Data and Visualization Center Publication 
SDVC 98-01-2, University of Wyoming, Laramie, Wyoming, variable pagination.

Mason J.P., Miller, D.T., and Ogle, K.M., 1999, Water 
resources data, Wyoming, water year 1998, Volume 2. Ground Water: U.S. 
Geological Survey Water-Data Report WY-98-2, 127 p.

Meister, R.T., 1996, Farm Chemicals Handbook: Willoughby, 
Ohio, Meister Publishing Co., variable pagination.

Solley, W.B., Pierce, R.R., and Perlman, H.A., 1998, 
Estimated use of water in the United States in 1995: U.S. Geological Survey 
Circular 1200, 71 p.

Swanson, R.B., Mason, J.P., and Miller, D.T., 2000, 
Water-resources data, Wyoming, water year 1999, Volume 2. Ground Water: U.S. 
Geological Survey Water-Data Report WY-99-2.

U.S. Environmental Protection Agency, 1996, Drinking water 
regulations and healthadvisories: EPA 822-B-96-002.

Wyoming Department of Environmental Quality, 1993, Procedures 
for establishing environmental restoration standards for leaking underground 
storage tank remediation actions, WDEQ/WQD Rules and Regulations, Chapter 
XVII.

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.

---

FOR MORE INFORMATION, 
      CONTACT:
      Jim BigelowWyoming Department of Agriculture2219 Carey 
      AvenueCheyenne, Wyoming 82002(307) 777-7324Kevin 
      FrederickWyoming Department of Environmental Quality,Water 
      Quality Division4th Floor, Herschler BuildingCheyenne, Wyoming 
      82002(307) 777-7781District Chief, U.S. Geological 
      Survey, WRD2617 E. Lincolnway, Suite BCheyenne, Wyoming 
      82001(307) 778-2931Email: state_rep_wy@usgs.govInternet: 
      http://wy.water.usgs.gov/
    photo


---

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 Wyo. Dept. of Environmental Quality's 
Non-Point 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.

---

Prepared by: Cheryl A. Eddy-Miller and Jodi R. 
Norris**Email:***cemiller@usgs.gov*

Layout by: Suzanne C. Roberts

---