Appendix B

NPDES Applicator and Application Estimates
The following table provides EPA’s current estimates of the number of applicators and applications of 

pesticides that fall within pesticide use patterns that result in the application of pesticides to and over, 

including near, waters of the United States. The information has not undergone peer review, and EPA 

intends to update these estimates as additional data become available.

There are two main limitations to the data provided. First, there is not a direct source of information on the 

number of applicators and applications made for these pesticide use patterns. As a result, the estimates 

were derived from secondary sources of information, and generalizing assumptions were sometimes made. 

The second limitation is that the definition of an application and an applicator is derived from the best 

available data by use pattern. Therefore the definition may be different by use pattern. More detail, by 

pesticide use pattern, is provided in the calculation notes.

Following the table is a listing of information sources used in EPA’s estimation of the number of pesticide 

applicators and applications. Information sources are listed by pesticide use pattern.

NPDES Applicator & Application Estimates

Use Patterns Number of 

Applicators

Number of 

Applications Calculation Notes

Mosquito Adulticides 1,200 461,450 There are 400 mosquito abatement districts and 

approximately 800 other public agencies that apply 

mosquito control pesticides--it is assumed that each 

represents an applicator. There were 103 million acretreatments with insecticides in 2005 (99 million for 

adulticides and 4 million for larvicides). Assuming 

that 77% of adulticide applications are made by

ground and 23% are made by air and that an average 

adulticide application by ground covers 180 acres and 

that an adulticide application by air covers 600 acres, 

there are an estimated 461,450 annual adulticide 

applications.

Mosquito Larvicides 1,200 18,800 There are 400 mosquito abatement districts and 

approximately 800 other public agencies that apply 

mosquito control pesticides--it is assumed that each 

represents an applicator. There were 103 million acretreatments with insecticides in 2005 (99 million for 

adulticides and 4 million for larvicides). Assuming 

that 77% of larvicide applications are made by ground 

and 23% are made by air and that an average larvicide 

application by ground covers 180 acres and that a

larvicide application by air covers 600 acres, there are 

an estimated 18,800 annual larvicide applications.

Aquatic Weed 

Control - Lakes and 

Ponds 

23,200 4,524,000 OPP data show approximately 23,200 applicators 

holding certification in the aquatic category. The 

estimate of applications to lakes, ponds, irrigation 

systems and waterways is the result of 23,200 

multiplied by 1 application per day over 195 work 

days (5 work days per week multiplied by 39 weeks [9 

months of the year]), which equals 4,524,000 

applications per year. EPA cannot determine what 

applications are made to each site, so one overall 

number has been calculated for all aquatic weed 

control in lakes, ponds, irrigation systems, and 

waterways.
Use Patterns Number of 

Applicators

Number of 

Applications Calculation Notes

Aquatic Weed 

Control - Irrigation 

Systems and 

Waterways 

See Aquatic 

Weed 

Control -

Lakes and 

Ponds

See Aquatic 

Weed 

Control -

Lakes and 

Ponds

See Aquatic Weed Control - Lakes and Ponds

Aquatic Weed 

Control – Ditchbanks

330,000 660,000 About 15%, or 330,000, of 2.2 million U.S. farms are 

irrigated. EPA assumes that each farm is treated twice 

per year. This does not account for types of irrigation.

Aquatic Nuisance 

Animal Control

Not 

Available

Not 

Available

Includes use of pesticides for the control of fish, 

lampreys, and mollusks. EPA currently does not have 

an estimate of the number of applicators and 

applications within this use pattern.

Wide Area Pest 

Control - Insects

170 5,000 Based on grasshopper & Mormon cricket control.

Estimate of 5 million acres treated with a minimum of 

1,000 acres per application. This is a low estimate 

because it does not include east of the Mississippi, and 

parts of west. Number of applicators is based on 

NAAA survey estimate of available aircraft.

Wide Area Pest 

Control - Invasive 

Weeds

5,000 10,000 Herbicides are usually not feasible for control of large 

wide area infestations. They are most likely used to 

control and/or eradicate smaller newer infestations. 

Applicators may be individual landowners or 

government agencies. No data is available for number 

of applicators and applications, but EPA estimates that 

there are at least 5,000 applicators and 10,000 

applications, and that these estimates may be low. 

Forestry 4,500 4,500 There are 5,175 tracts of forest in the U.S. and 2.7 

million acres of forest are treated per year. Assuming

that an average pesticide application to forests is 600 

acres (based on NAAA survey), the number of 

applications is calculated as the number of acres 

treated per year divided by the number of acres treated 

per application. It is assumed that the 4,500 

applications are evenly distributed across the 5,175 

forest tracts, thus it is assumed that there is one 

applicator per treated tract. The estimate of the number 

of applications and applicators may be low because 

data are not available on pesticides applied by ground.

Total 365,270 5,683,750
NPDES Applicator &Application Information Sources

Mosquito Control

CDC, 2009. Infectious disease information: Mosquito-borne diseases. U.S. Centers for Disease Control and 

Prevention. Available online at: http://www.cdc.gov/ncidod/diseases/list_mosquitoborne.htm

EPA Proprietar Marketing Research Data. 

EPA and CDC, 2007. Joint statement on mosquito control in the United States. U.S. Environmental 

Protection Agency and the U.S. Centers for Disease Control and Prevention. Available online at: 

http://www.epa.gov/opp00001/health/mosquitoes/mosquitojoint.htm

Florida Coordinating Council on Mosquito Control, 1998. Florida mosquito control: The

state of the mission as defined by mosquito controllers, regulators, and environmental

managers, University of Florida, Vero Beach, FL.

NAAA, 2004. Pesticide use survey report for agricultural aviation. National Agricultural Aviation 

Association, Washington, DC. 

University of Florida, IFAS Extension,(undated). Integrated mosquito management (IMM). Florida 

Medical Entomology Laboratory. Available online at:

http://mosquito.ifas.ufl.edu/Integrated_Mosquito_Management.htm

Aquatic Weed Control 

Baker Hughes Incorporated, 2004. MAGNACIDE® H herbicide: Most cost effective aquatic weed control. 

Available online at:

http://www.bakerhughesdirect.com/cgi/hello.cgi/BPC/public/agriculture/pdf/BakerPetrolie_costeffective.pd

f

Bronzini, Michael S., 1997. Inland waterways: Still or turbulent waters ahead? Annals of the American 

Academy of Political and Social Science, Vol. 553, Transport at the Millennium (Sep., 1997), 66-74.

California Department of Pesticide Regulation. Pesticide Information Portal, 2009. Pesticide Use 

Reporting. Available online at: http://www.cdpr.ca.gov/docs/pur/purmain.htm

EPA Proprietar Marketing Research Data. 

EPA. 2007. Survey of the Nation’s lakes: A fact sheet for communities. U.S. EPA, Office of Water, 

National Lakes Assessment. Available online at: http://epa.gov/owow/lakes/lakessurvey/

Smith, S.V., W.H. Renwick, J.D. Bartley, and R.W. Buddenmier, 2002. Distribution and significance of 

small, artificial water bodies across the United States landscape. The Science of The Total Environment

,Volume 299, Issues 1-3, 1 November 2002, 21-36.

University of Kentuchy, 2009. Aquatic weed control. Univ. of Kentucky Pesticide Education Program. 

Available online at: http://www.uky.edu/Ag/PAT/cat5/cat5.htm

U.S. Census Bureau, 2003. 2002 Census of Governments, Volume 1, Number 1, Government Organization,

GC02(1)-1, U.S. Government Printing Office, Washington, DC. Available online at: 

http://www.census.gov/prod/2003pubs/gc021x1.pdf

USDA NASS, 2005 Census of Aquaculture, Volume 3, Special Studies, Part 2, AC-02-SP-2, 2006. 

Available online at: http://www.agcensus.usda.gov/Publications/2002/Aquaculture/index.asp
USDA NASS. 2009. 2007 Census of Agriculture. U.S. Department of Agriculture, National Agricultural 

Statistics Service. Available online at: http://www.agcensus.usda.gov/ 

Wide Area Pest Control

Evans, E.W. and E.W. Hodgdon, 2008. Grasshoppers, Utah Pests Fact Sheet ENT-125-08. Utah State U. 

Extension and Utah Plant Pest Diagnostic Laboratory, June 2008.

NAAA, 2004. Pesticide use survey report for agricultural aviation. National Agricultural Aviation 

Association, Washington, DC.

Plant Protection Act, Public Law 106-224 of June 20, 2000, Title IV, as amended by Public Law 108-412, 

Section 1, Noxious Weed Control and Eradication, October 30, 2004.

Roe, Alan, 2000. Grasshoppers and their control, Fact Sheet No.48. Utah State U. Dept of Biology.

USDA/APHIS. 2002. Rangeland Grasshopper and Mormon Cricket Suppression Program, Final 

Environmental Impact Statement--2002. Available online at: 

http://www.aphis.usda.gov/import_export/plants/manuals/domestic/downloads/eis.pdf

Forestry

Baker, J. and S. Bambara, 2001. White pine weevil. North Carolina Cooperative Extension, NC State 

University, retrieved 3/12/09. Available online at:

http://www.ces.ncsu.edu/depts/ent/notes/O&T/trees/note33/note33.html

Christopherson J., (no date). Mountain pine beetle. Nevada Division of Forestry, Forest Health Program, 

retrieved 3/12/09 at http://www.forestry.nv.gov/main/health_pine.htm

Day, E. and S. Salom, 2003. White pine weevil. Virginia State University, Cooperative Extension. 

Publication Number 444-270, retrieved 3/12/09. Available online at:

http://www.ext.vt.edu/pubs/entomology/444-270/444-270.html

Duddles, R.E. and M. Cloughesy, 2002. Introduction to conifer release. The Woodland Workbook: 

Reforestation, retrieved 3/12/09. Available online at:

http://extension.oregonstate.edu/catalog/pdf/ec/ec1388.pdf

Dun and Bradstreet, 2009. Query, retrieved 2/14/09. Available online at:

https://pdp.dnb.com/pdpepa/PDPLogin.asp

Fitzgerald. S.A.,1998. Site preparation: an Introduction for the woodland owner. The Woodland Workbook: 

Reforestation, retrieved 3/12/09. Available online at:

http://extension.oregonstate.edu/catalog/pdf/ec/ec1188.pdf

Jackson, D., 2007. Herbicides and forest vegetation management: Controlling unwanted trees, brush, and 

other competing forest vegetation, Penn State College of Agricultural Sciences, Agricultural Research 

Cooperative Extension, retrieved 3/12/09. Available online at:

http://pubs.cas.psu.edu/freepubs/pdfs/UH174.pdf

Kelley, T., 2007. Gypsy moth infestation may kill 17,000 acres of trees in New Jersey. New York Times, 

July 20, 2007, retrieved 3/12/09. Available online at:

http://www.nytimes.com/2007/07/20/nyregion/20gypsy.html?fta=y

Kucera, D. and P. Orr, (no date). Spruce budworm in the Eastern United States, Forest Insect and Disease 

Leaflet 160. U.S Department of Agriculture, Forest Service. retrieved 3/12/09. Available online at: 

http://www.na.fs.fed.us/spfo/pubs/fidls/sbw/budworm.htm
Leatherman, D.A., J.W. Brewer, and R.E. Stevens, 2009. Western spruce budworms. Colorado State 

University, retrieved 3/12/09. Available online at: http://www.ext.colostate.edu/pubs/insect/05543.html

McManus, M, N. Schneeberger, R. Reardon, and G. Mason, (no date). Gypsy moth, Forest Insect and 

Disease Leaflet 162, U.S. Department of Agriculture, Forest Service, retrieved 3/12/09. Available online at: 

http://www.na.fs.fed.us/SPFO/pubs/fidls/gypsymoth/gypsy.htm

Michael, J., 2004. Best management practices for silvicultural chemicals and the science behind them. 

Water, Air, and Pollution: Focus. 4(1), 95-117.

NAAA, 2004. Pesticide use survey report for agricultural aviation. National Agricultural Aviation 

Association, Washington, DC.

Robbins, J., 2008. Bark beetles kill millions of acres of trees in West. New York Times, November 17, 

2008, retrieved 3/12/09. Available online at: http://www.nytimes.com/2008/11/18/science/18trees.html

USDA APHIS, 2008. Gypsy moth program manual. United States Department of Agriculture, Animal and 

Plant Health Inspection Service, retrieved 3/16/09. Available online at: 

http://www.aphis.usda.gov/import_export/plants/manuals/domestic/downloads/gypsy_moth.pdf

USDA FS, 2008. The cooperative state-county-landowner gypsy moth suppression program in West 

Virginia. West Virginia Cooperative Extension Service/United States Department of Agriculture, Forest 

Service, retrieved 3/12/09. Available online at:

http://home.comcast.net/~wvdanewcreek/2008_2009_CSCL_Program_Brochure.pdf

Wickman, B.E., R.R. Mason, and G.C. Trostle. Douglas-fir Tussock moth, Forest Insect and Disease 

Leaflet 86. U.S. Department of Agriculture, Forest Service, retrieved 3/12/09. Available online at: 

http://www.na.fs.fed.us/spfo/pubs/fidls/tussock/fidl-tuss.htm