Edits in Response to OMB Comments

U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

1 

U.S. Environmental Protection Agency 

2010 Public Notice of: 

Draft National Pollutant Discharge Elimination System (NPDES) 

Pesticides General Permit (PGP) for Discharges from the 

Application of Pesticides to or over, including near Waters of the 

U.S. 

Fact Sheet 

Agency: U.S. Environmental Protection Agency 

Action: Notice of Draft NPDES General Permit 

Deleted: 
Edits in Response to OMB Comments

U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

2 

TABLE OF CONTENTS 

I. Background 

 1. Clean Water Act 

 2. NPDES Permits 

 3. History of Pesticide Application Regulation 

 4. Court Decisions Leading to the CWA Regulations Concerning Pesticide Applications 

5. 2006 Agency Rulemaking Excluding Pesticides from the NPDES Pesticides Permitting 

Program 

 6. Legal Challenge to the 2006 Rule and Court Decision 

II. Structure of this Permit 

 1. General 

 2. Conformance to Recent Court Decisions 

 3. Sharing of Responsibilities 

III. Summary of Permit Conditions 

 1. Coverage under this Permit 

 1.1. Eligibility 

 1.1.1. Activities Covered 

 1.1.2. Limitations on Coverage 

 1.2. Authorization to Discharge under this Permit 

 1.2.1. No Requirement to Submit a Notice of Intent (NOI) for Certain Applications 

 1.2.2. How to Obtain Authorization 

 1.2.3. Discharge Authorization Date 

 1.2.4. Continuation of This Permit 

 1.2.5. Terminating Coverage 

 1.3. Alternative Permits 

 1.4. Severability 

2. Technology-Based Effluent Limitations 

 2.1. Minimize Pesticide Discharges into Waters of the United States 

 2.1.1. Use the Lowest Effective Amount of Pesticide Product 

 2.1.2. Regular Maintenance 

 2.1.3. Equipment Calibration 

 2.2. Integrated Pest Management Practices 

 2.2.1. Mosquito and Other Flying Insect Pest Control 

2.2.2. Aquatic Weed and Algae Control 

2.2.3. Aquatic Nuisance Animal Control 

2.2.4. Forest Canopy Pest Control 

 3. Water-Quality-Based Effluent Limitations 

 4. Site Monitoring 

 4.1. Monitoring Requirements for All Operators 

 4.2. Visual Monitoring Requirements 

 4.3. Additional EPA Monitoring 

5. Pesticide Discharge Management Plan (PDMP) 

 5.1. Contents of your Pesticide Discharge Management Plan 

 5.1.1. Pesticide Discharge Management Team 

Deleted: 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

2 

 5.1.2. Pest Management Area Description 

 5.1.3. Control Measure Description 

 

 5.1.4. Schedules and Procedures 

5.1.5. Documentation to Support Eligibility Considerations Under Other Federal 

Laws 

5.1.6 Signature Requirements 

 5.2. Pesticide Discharge Management Plan Modifications 

 5.3. Pesticide Discharge Management Plan Availability 

6. Corrective Actions 

 6.1. Situations Requiring Revision of Control Measures 

 6.2. Corrective Action Deadlines 

 6.3. Effect of Corrective Action 

 6.4. Adverse Incident Documentation and Reporting 

 6.5. Reportable Spills and Leaks 

 6.6. Other Corrective Action Documentation 

7. Annual Reporting and Recordkeeping 

8. EPA Contact and Mailing Addresses 

9. Permit Conditions Applicable to Specific States, Indian Country Lands, or Territories 

 10. Appendices 

 A. Definitions and Acronyms 

 B. Standard Permit Conditions 

 C. Areas Covered 

 D. Notice of Intent Form 

 E. Notice of Termination Form 

 F. Endangered Species Procedures 

 

Appendices 

Appendix A List of Pesticides and degradates which exceeded aquatic-life benchmarks in the 

USGS study and the draft CA Central Valley Regional 303(d) impairment list of 

pesticides 

Appendix B Chemicals and exceedances in USGS study and subsequent mitigation measures 

that reduce pesticides residues in waters 

Appendix C Summary of Pesticide-Specific Exceedance Data and Risk Mitigation Actions
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

2 

I. Background 

This draft permit is being proposed to authorize point source discharges to waters of the 

United States (U.S.) from the application of pesticides for specific pesticide use patterns as 

defined in Part 1.1.1 of the permit. EPA is soliciting comment on many aspects of this permit. 

Please refer to the Federal Register Notice announcing the availability of this permit for review 

and comment for a list of specific questions. Supporting information and materials for this draft 

permit and accompanying fact sheet are included in Docket ID No. EPA-HQ-OW-2010-0257 

available at www.regulations.gov. 

1. Clean Water Act

 Section 301(a) of the Clean Water Act (CWA) provides that “the discharge of any 

pollutant by any person shall be unlawful” unless the discharge is in compliance with certain 

other sections of the Act. 33 U.S.C. 1311(a). The CWA defines “discharge of a pollutant” as 

“(A) any addition of any pollutant to navigable waters from any point source, (B) any addition of 

any pollutant to the waters of the contiguous zone or the ocean from any point source other than 

a vessel or other floating craft.” 33 U.S.C. 1362(12). A “point source” is any “discernible, 

confined and discrete conveyance” but does not include “agricultural stormwater discharges and 

return flows from irrigated agriculture.” 33 U.S.C. 1362(14). 

 The term “pollutant” includes, among other things, “garbage... chemical wastes, 

biological materials ...and industrial, municipal, and agricultural waste discharged into water.” 

 One way a person may discharge a pollutant without violating the section 301 prohibition 

is by obtaining authorization to discharge (referred to herein as “coverage”) under a section 402 

National Pollutant Discharge Elimination System (NPDES) permit (33 U.S.C. 1342). Under 

section 402(a), EPA may “issue a permit for the discharge of any pollutant, or combination of 

pollutants, notwithstanding section 1311(a)” upon certain conditions required by the Act. 

2. NPDES Permits 

An NPDES permit authorizes the discharge of a pollutant or pollutants into a receiving 

water under certain conditions. The NPDES program relies on two types of permits: individual 

and general. An individual permit is a permit specifically tailored for an individual discharger. 

Upon receiving the appropriate permit application(s), the permitting authority, i.e., the U.S. 

Environmental Protection Agency (EPA) or a state, develops a draft permit for public comment 

for that particular discharger based on the information contained in the permit application (e.g., 

type of activity, nature of discharge, receiving water quality). Following consideration of public 

comments, a final permit is then issued to the discharger for a specific time period (not to exceed 

5 years) with a provision for reapplying for further permit coverage prior to the expiration date. 

In contrast, a general permit covers multiple facilities/sites/activities within a specific 

category for a specific period of time (not to exceed 5 years). For general permits, EPA or a 

state develops and issues the permit in advance, with dischargers then generally obtaining 

coverage under the permit through submission of a Notice of Intent (NOI). A general permit is 

also subject to public comment prior to issuance. For the case of this general permit, EPA is the 

permitting authority for the states that have not been authorized by EPA to issue NPDES permits. 

Deleted: regulated amount of a 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

3 

Each permitting authority should review their permittees and geographic area and develop 

appropriate permits considering technology and water quality. In addition, states may issue a 

permit that has different requirements from this permit for similar types of discharges, as long as 

it satisfies the regulatory requirements of the NPDES program and state law. 

Under 40 CFR 122.28, general permits may be written to cover categories of point 

sources having common elements, such as facilities that involve the same or substantially similar 

types of operations, that discharge the same types of wastes, or that are more appropriately 

regulated by a general permit. Given the vast number of pesticide applicators requiring NPDES 

permit coverage and the discharges common to these applicators, EPA believes that it makes 

administrative sense to issue the general permit, rather than issuing individual permits to each 

applicator. Courts have approved of the use of general permits. See e.g., Natural Res. Def. 

Council v. Costle, 568 F.2d 1369 (D.C. Cir. 1977); EDC v. US EPA, 344 F.3d 832, 853 (9th Cir. 

2003). The general permit approach allows EPA to allocate resources in a more efficient manner 

and to provide more timely coverage and may significantly simplify the permitting process for 

the majority of pesticide dischargers. As with any permit, the CWA requires the general permit 

to contain technology-based effluent limitations, as well as any more stringent limits when 

necessary to meet applicable state water quality standards. State water quality standards apply in 

the territorial seas, defined in section 502(8) of the CWA as extending three miles from the 

baseline. Pacific Legal Foundation v. Costle, 586 F.2d 650, 655-656 (9th Cir. 1978); Natural 

Resources Defense Council, Inc. v. U.S. EPA, 863 F.2d 1420, 1435 (9th Cir. 1988). 

3. History of Pesticide Application Regulation 

 In the more than 30 years that EPA has administered the CWA, the Agency has never 

issued an NPDES permit for the application of a pesticide to target a pest that is present in or 

over, including near, the water where such application results in a discharge to waters of the U.S. 

Instead, EPA has been regulating these types of applications through the Federal Insecticide, 

Fungicide, and Rodenticide Act (“FIFRA”). 

 EPA regulates the sale, distribution and use of pesticides in the U.S. under the statutory 

framework of FIFRA to ensure that when used in conformance with FIFRA labeling directions, 

pesticides will not pose unreasonable risks to human health and the environment. All new 

pesticides must undergo a registration procedure under FIFRA during which EPA assesses a 

variety of potential human health and environmental effects associated with use of the product. 

Under FIFRA, EPA is required to consider the effects of pesticides on the environment by 

determining, among other things, whether a pesticide ‘‘will perform its intended function without 

unreasonable adverse effects on the environment,’’ and whether ‘‘when used in accordance with 

widespread and commonly recognized practice [the pesticide] will not generally cause 

unreasonable adverse effects on the environment.’’ 7 U.S.C. 136a(c)(5). In performing this 

analysis, EPA examines the ingredients of a pesticide, the intended type of application site and 

directions for use, and supporting scientific studies for human health and environmental effects 

and exposures. The applicant for registration of the pesticide must provide specific data from 

tests done according to EPA guidelines. 

 When EPA approves a pesticide for a particular use, the Agency imposes restrictions 

through labeling requirements governing such use. The restrictions are intended to ensure that 

the pesticide serves an intended purpose and avoids unreasonable adverse effects. It is illegal 

Deleted: is more stringent or more 

extensive than a

Deleted: issued by EPA 

Deleted: in a label
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

4 

under Section 12(a)(2)(G) of FIFRA to use a registered pesticide in a manner inconsistent with 

its labeling. States have primary authority under FIFRA to enforce “use” violations, but both the 

States and EPA have ample authority to prosecute pesticide misuse when it occurs. 

4. Court Decisions leading to the CWA regulation concerning Pesticide Applications 

Over the past ten years, several courts addressed the question of whether the CWA 

requires NPDES permits for pesticide applications. These cases resulted in some confusion 

among the regulated community and other affected citizens about the applicability of the CWA 

to pesticides applied to waters of the U.S. In 2001, the U.S. Court of Appeals for the Ninth 

Circuit held in Headwaters, Inc. v. Talent Irrigation District (Talent) that an applicator of 

herbicides was required to obtain an NPDES permit under the circumstances before the court. 

243 F.3rd 526 (9th Cir. 2001). The Talent decision caused considerable confusion among public 

health authorities, natural resource managers, and others who rely on pesticides regarding their 

potential obligation to obtain an NPDES permit when applying a pesticide consistent with 

FIFRA. 

In 2002, the Ninth Circuit in League of Wilderness Defenders et al. v. Forsgren

(Forsgren) held that the application of pesticides to control Douglas Fir Tussock Moths in 

National Forest lands required an NPDES permit. 309 F.3d 1181 (9th Cir. 2002). The court in 

Forsgren did not analyze the question of whether the pesticides applied were pollutants, because 

it assumed that the parties agreed that they were. In fact, the U.S. expressly reserved its 

arguments on that issue in its brief to the District Court. Id. at 1184, n.2. The court instead 

analyzed the question of whether the aerial application of the pesticide constituted a point source 

discharge, and concluded that it did. Id. at 1185. 

Since Talent and Forsgren, California, Nevada, Oregon, and Washington, all of which are 

within the jurisdiction of the Ninth Circuit Court of Appeals, have issued permits for the 

application of certain types of pesticides (e.g., products to control aquatic weeds and algae and 

products to control mosquito larvae). Other states have continued their longstanding practice of 

neither requiring nor issuing permits to people who apply pesticides to waters of the U.S.. These 

varying practices reflected the substantial uncertainty among regulators, the regulated 

community, and the public regarding how the CWA applies to discharges of pesticides to waters 

of the U.S. 

 Additionally, the Second Circuit Court of Appeals addressed the applicability of the 

CWA's NPDES permit requirements to pesticide applications. In Altman v. Town of Amherst

(Altman), the court vacated and remanded for further development of the record a District Court 

decision holding that the Town of Amherst was not required to obtain an NPDES permit to spray 

mosquitocides over waters of the U.S. 47 Fed. Appx. 62, 67 (2nd Cir. 2002). In its opinion, the 

Second Circuit stated that “[u]ntil the EPA articulates a clear interpretation of current law – 

among other things, whether properly used pesticides released into or over water of the U.S. can 

trigger the requirement for NPDES permits * * * – the question of whether properly used 

pesticides can become pollutants that violate the CWA will remain open.” Id. at 67. 

In Fairhurst v. Hagener, the Ninth Circuit again addressed the CWA’s applicability to 

pesticide applications. The court held that pesticides applied directly to a lake in order to 

eliminate non-native fish species, where there are no residues or unintended effects, are not 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

5 

“pollutants'' under the CWA because they are not chemical wastes. 422 F.3d 1146 (9th Cir. 

2005). 

5. 2006 Agency Rulemaking Excluding Pesticides from the NPDES Permitting 

Program 

On November 27, 2006, EPA issued a final rule (hereinafter called the “2006 NPDES 

Pesticides Rule”) clarifying two specific circumstances in which an NPDES permit was not 

required to apply pesticides to or around water. They were: 1) the application of pesticides 

directly to water to control pests; and 2) the application of pesticides to control pests that are 

present over, including near, water where a portion of the pesticides will unavoidably be 

deposited to the water to target the pests, in both instances provided that the application is 

consistent with relevant Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) 

requirements. The rule became effective on January 26, 2007. 

6. Legal Challenges to the 2006 NPDES Pesticides Rule and Court Decision 

On January 19, 2007, EPA received petitions for review of the 2006 NPDES Pesticides 

Rule from environmental and industry groups. Petitions were filed in eleven circuit courts with 

the case, National Cotton Council, et al, v. EPA, assigned to the Sixth Circuit Court of Appeals.

On January 9, 2009, the Sixth Circuit vacated EPA’s 2006 NPDES Pesticides Rule under 

a plain language reading of the CWA. National Cotton Council of America v. EPA, 553 F.3d 

927 (6th Cir., 2009). The Court held that the CWA unambiguously includes “biological 

pesticides” and “chemical pesticides” with residuals within its definition of “pollutant.” 

Specifically, an application of chemical pesticides that leaves no excess portion is not a 

discharge of a pollutant, and the applicator need not obtain an NPDES permit. However, 

chemical pesticide residuals are pollutants as applied if they are discharged from a point source 

for which NPDES permits are required. Biological pesticides on the other hand are always 

considered a pollutant under the CWA regardless of whether the application results in residuals 

or not and require a NPDES permit for all discharges from a point source. 

In response to this decision, on April 9, 2009, EPA requested a two-year stay of the 

mandate to provide the Agency time to develop general permits, to assist NPDES-authorized 

states to develop their NPDES permits, and to provide outreach and education to the regulated 

community. On June 8, 2009, the Sixth Circuit granted EPA the two-year stay of the mandate. 

As a result of the Court’s decision to vacate the 2006 NPDES Pesticides Rule, at the end 

of the two-year stay, NPDES permits will be required for discharges to waters of the U.S. of 

biological pesticides, and of chemical pesticides that leave a residue. In response to the Court’s 

decision, EPA decided to propose this general permit to cover certain discharges resulting from 

pesticide applications. EPA Regional offices may issue additional general permits or individual 

permits if needed. 

Irrigation return flows and agricultural stormwater runoff do not require NPDES permits, 

even when they contain pesticides or pesticide residues, as the CWA specifically exempts these 

categories of discharges from requiring NPDES permit coverage. Additionally, other stormwater 

runoff is either: (a) already required to obtain NPDES permit coverage as established in section 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

6 

402(p) of the CWA or (b) classified as a non-point source discharge for which NPDES permit 

coverage is not required. Thus, neither the 2006 NPDES Pesticides Rule, the Sixth Circuit Court 

vacatur of that rule, nor this PGP have changed in any way the determination of whether certain 

types of stormwater runoff are required to obtain permit coverage or under which permit 

coverage is required. This is true whether the runoff contains pesticides or pesticide residues 

resulting from the application of pesticides. In particular, stormwater runoff that may contain 

pesticides would not be eligible for coverage under this permit, and is not required to obtain 

NPDES permit coverage unless it was already required to do so prior to the Sixth Circuit 

decision or EPA designates a source for future stormwater permitting. Existing stormwater 

permits for construction, industry, and municipalities already address pesticides in stormwater.

EPA determined that the four use patterns included in the PGP would encompass the 

majority of pesticide applications that would result in point source discharges to waters of the 

U.S. and generally represent the use patterns intended to be addressed by the 2006 rule that is 

now vacated. This permit does not cover terrestrial applications for the purpose of controlling 

pests on agricultural crops or forest floors. This fact sheet does not address whether these 

activities would need an NPDES permit nor does this fact sheet identify every activity which 

may involve a point source discharge to waters of the U.S. that would require a permit. While 

other use patterns are not covered by this general permit, the existence of this general permit 

does not, by definition, obviate the possibility that an individual permit would be necessary if 

other types of pesticide applications result in point source discharges to waters of the U.S. 

On November 2, 2009, industry petitioners of the Sixth Circuit Case petitioned the 

Supreme Court to review the Sixth Circuit’s decision. On February 22, 2010, the Supreme Court 

denied the request to hear industry’s petition, leaving the April 2011 effective date unchanged. 

II. Structure of this Permit 

1. General 

This permit is written for the many specific areas of the country for which EPA remains 

the NPDES permitting authority. This permit is constructed in such a way as to cover all of 

these areas in one document and is identified as either the “permit” or “general permit” or 

“pesticide general permit” (PGP) even though legally, this single document consists of many 

permits. Specifically, this permit provides coverage for certain point source discharges that 

occur in areas not covered by an authorized State NPDES permit program and includes specific 

areas (e.g., States, Tribal lands, territories, or federal facilities) in all ten EPA Regions. As such, 

the permit will be signed by each of the ten EPA Regions but will remain as one permit 

document. The complete list of areas of geographic coverage of this permit, along with the 

NPDES permit numbers are listed in Appendix C of the permit. 

Note that this permit covers the State of Alaska even though Alaska has recently been 

authorized to administer the NPDES program as the State is not obligated to assume permitting 

responsibilities for discharges from pesticide applications until late 2011. Thus, this permit will 

cover discharges in the State of Alaska until such time as any State permits take effect. Also, the 

authority of the Oklahoma Department of Environmental Quality (ODEQ) to administer the 

NPDES program is uncertain. It may be that, pursuant to Oklahoma state law, Oklahoma's 

Department of Agriculture, Food, and Forestry (ODAFF) is the only state agency with 

Deleted: fro

Deleted: proposed 

Deleted: possible 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

7 

jurisdiction to regulate pesticide applications within the state. ODAFF is not currently authorized 

to administer the NPDES program, and therefore does not have the authority to issue permits for 

discharges from the application of biological pesticides or chemical pesticides. Before issuance 

of this permit, EPA anticipates receipt of a state attorney general opinion addressing that issue in 

connection with a partial program authorization request by ODAFF to administer the NPDES 

program for discharges within its jurisdiction. For this draft permit, EPA assumes that 

Oklahoma will not have authority to permit the types of discharges covered under this permit. 

The final permit will cover discharges in the State of Oklahoma unless and until the authority of 

a state agency to issue such permits is clarified.

States that are authorized to issue NPDES permits for the control of discharges to waters 

of the U.S. from the application of pesticides will be developing their own NPDES permits to 

cover such discharges. Nothing in the federal regulations precludes a state from adopting or 

enforcing requirements that are appropriate to address discharges in their state or are more 

stringent or more extensive than those required under the NPDES regulations. In fact, the Clean 

Water Act is meant to serve as a baseline for state environmental protection. The Clean Water 

Act and corresponding NPDES regulations require that permits, at a minimum, include the 

requirements detailed in Part 122.44. States are free to incorporate additional requirements that 

they feel are necessary to adequately protect water quality. Similarly, how EPA and states 

interpret information from which permit requirements are developed may differ. For example, 

the regulations, as written at 122.44(i) specify that monitoring requirements be included to assure 

compliance with permit limitations. One permit writer may make a best professional judgment 

(BPJ) determination that monitoring of discharges reasonably should occur during pesticide 

application while a second permit writer may make a BPJ determination that monitoring of 

discharges should reasonably be performed after pesticide application. It is reasonable that the 

two different permit writers may come to different conclusions about how best to incorporate this 

requirement into the permit. 

EPA is aware that a number of states have laws that prohibit the state from adopting a 

rule or requirement that is more stringent than the comparable federal regulations that address the 

same issue. Although it is up to states to interpret state law, EPA does not believe these laws

necessarily prohibit states from including requirements in a state-issued general permit that are 

different (and potentially more costly) than the “comparable” requirements in this EPA-issued 

permit. This permit applies only to the areas in which EPA is the permitting authority and 

represents EPA’s best professional judgment about what is required to meet the requirements of 

the Clean Water Act in those areas. Permit writers are to evaluate available information specific 

to the activities and areas covered under their own permits and in many instances, a state may 

determine based on that information that different requirements are necessary to meet the 

requirements of the Clean Water Act for those activities and areas. States should incorporate 

requirements that address public or environmental dangers specific to their state. Contact your 

state environmental protection agency for information on any state-issued NPDES permit.

Throughout this fact sheet (and permit), EPA uses consistent terms when referring to 

what activity or discharge will be eligible for coverage and who will be responsible to comply 

with the terms of the permit. Specifically, the permit holder is referred to as the “operator.” This 

term has a similar meaning to the term “permittee” which is also used in the fact sheet; generally, 

the term permittee is specific to the period of time that an operator or contractor is actually 

covered under the permit. Additionally, the terms “you” and “your” as used in the permit are 

Deleted: of this permit 

Deleted: one

Deleted: In that instance, the 

regulations, as written at 122.44(i) 

specify that monitoring requirements be 

included to assure compliance with 

permit limitations.

Deleted: Some states may believe 

based on the amount of water in their 

state that applications will unavoidably be 

applied to water.

Deleted: , in all instances,

Deleted: is 

Deleted: a comparable 

Deleted: the permit 

Deleted: have more detailed 

Deleted: on

Deleted: to be covered under that state 

permit than EPA has for activities to be 

covered under this general permit issued 

by EPA Regions
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

8 

intended to refer to the operator and their responsibilities under the permit. The use of “you” and 

“your” refer to a specific activity covered under the permit but not necessarily all activities 

operated by a particular entity. For example, “you must submit” means the operator must submit 

something for the specific activities identified. Likewise, “all your discharges” would only apply 

to those discharges covered under the permit. More details on how an operator is to obtain 

permit coverage and the applicable permit requirements are provided in Part III of the fact sheet. 

The permit is divided into nine parts: (1) coverage under this permit, (2) technologybased effluent limitations, (3) water quality-based effluent limitations, (4) site monitoring, (5) 

pesticide discharge management plan, (6) corrective action, (7) annual reporting and 

recordkeeping, (8) EPA contact information and mailing addresses, and (9) permit conditions 

applicable to specific states, Indian country lands, or territorial, and tribal requirements. 

Additionally, the permit includes six appendices with additional conditions and guidance for 

permittees: (A) definitions and acronyms, (B) standard permit conditions, (C) areas covered, (D) 

notice of intent form, (E) notice of termination form, and (F) Endangered Species Procedures. 

Readers should be aware that this version of the permit does not include draft language 

on certain aspects that may be included in the final permit. Those include incorporation of any 

additional requirements consistent with: (1) obtaining certification from States/Tribes under 

Section 401 of the CWA that the permit will adequately protect state water quality; and (2) 

obtaining state certification of consistency with approved state coastal zone management 

planning. 

Operators should carefully read each part of the permit to assess whether or what portion 

of the requirements in each part may apply to their activities. As will be discussed in more detail 

in Part III of this fact sheet, the permit establishes different requirements for different types of 

pesticide use patterns, different types of operators, and different sizes of areas treated and 

managed for the control of pests. The organization of the permit is intended to clarify the 

applicable requirements for permittees to the greatest extent possible. 

2. Conformance to Recent Court Decisions 

 EPA has structured this permit to conform to recent relevant court decisions. 

One of these cases held that because the terms of the Nutrient Management Plan (NMP) 

employed by concentrated animal feeding operations (CAFO) imposed restrictions on 

discharges, those restrictions amounted to effluent limitations that needed to be made part of the 

permit and to be subject to public and permit writer review. Waterkeeper Alliance, Inc. v. EPA, 

399 F.3d 486 (2nd Cir. 2005). In this respect, this permit is different from the CAFO 

requirements. In this permit, EPA explicitly establishes effluent limitations in Parts 2 and 3 that 

are independent of any documentation and recordkeeping requirements regarding 

implementation of the limitations. In a separate part of the permit (Part 5) there is a requirement 

to develop a Pesticide Discharge Management Plan (PDMP). The PDMP is not a limitation and 

does not itself impose requirements on discharges. These are already imposed by the limitations 

in parts 2 and 3. The PDMP is rather a tool for operators to document, among other things, how 

control measures will be implemented to comply with the permit’s effluent limitations. 

Formatted: Font: Not Bold

Deleted: recordkeeping and 

Deleted: state, 

Deleted: seven

Deleted: Consistent with these 

decisions

Deleted: established

Deleted: in 

Deleted: an information gathering

Deleted: 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

9 

Effluent Limitations in the Permit 

Part 2 of the permit contains the technology-based effluent limitations. Part 3 of the 

permit contains the water quality-based effluent limitations. These Parts of the permit contain 

effluent limitations, defined in the CWA as restrictions on quantities, rates, and concentrations of 

constituents that are discharged. CWA section 502(11). Violation of any of these effluent 

limitations constitutes a violation of the permit. As is described in more detail in Part III.2 of the 

fact sheet, under the CWA these effluent limitations can be narrative rather than numeric. 

The technology-based effluent limitations set forth in Part 2 require the operator to 

minimize discharge of pesticides to waters of the U.S. Consistent with the control level 

requirements of the CWA, the term “minimize” means to reduce and/or eliminate pesticide 

discharges to waters of the U.S. through the use of control measures to the extent technologically 

available and economically achievable and practicable for the category or class of point sources 

covered under this permit taking into account any unique factors relating to the operators to be 

covered under the permit. The technology-based effluent limitations section is divided into two 

parts. The first part applies to all operators and addresses the general requirement to minimize 

discharges. In this part, all operators must minimize discharges of pesticides by using the lowest 

effective amount of pesticide product per application and optimum frequency of pesticide 

applications necessary to control the target pest taking into account pest resistance concerns, 

perform regular maintenance activities, calibrate and clean/repair application equipment, and 

comply with all conditions and/or prerequisites resulting from any consultation under Section 7 

of the Endangered Species Act (ESA) or a permit issued under Section 10 of that Act. (see Part 

2.1 of PGP.) The second part requires certain operators to implement additional Integrated Pest 

Management (IPM) Practices which involve the following: (1) identifying and assessing the pest 

problem; (2) assessing effective pest management; and (3) following specified procedures for 

pesticide application (see Part 2.2 of PGP). 

In addition to the technology-based effluent limitations, Part 3 of the PGP contains the 

water-quality-based effluent limitations. The operator must control its discharge as necessary to 

meet applicable water quality standards. Any discharge that results in an excursion of any 

applicable numeric or narrative EPA-approved state, territory, or tribal or EPA-promulgated 

water quality standard is prohibited. In general, based on the data included in the record and the 

additional requirements in this permit in addition to FIFRA, EPA expects that compliance with 

the technology-based effluent limitations and other terms and conditions in this permit will meet 

applicable water quality-based effluent limitations. However, if at any time the operator, or 

EPA, determines that the discharge causes or contributes to an excursion of applicable water 

quality standards, the operator must take corrective actions as required in Part 6, and document 

and report the excursion(s) to EPA as required in Part 7. Furthermore, consistent with Parts 3.0 

and 6.3, EPA may impose additional water quality-based limitations on a site-specific basis, or 

require the operator to obtain coverage under an individual permit, if information in an NOI, 

required reports, or from other sources indicates that, after meeting the technology-based 

limitations in this Permit, the discharges are not controlled as necessary to meet applicable water 

quality standards. EPA also notes that among the eligibility requirements for coverage under 

this permit are that it does not cover discharges of any pesticide into a water impaired for that 

pesticide, or into a Tier 3 water. While not specifically framed as effluent limitations, these 

eligibility conditions further help to protect water quality on a water-body-specific basis. 

Deleted: for discharges from activities 

covered under this permit 

Deleted: Whether or not EPA chooses 

to impose numeric water quality based

Deleted: the operator remains 

responsible for ensuring its discharge 

does not cause or contribute to a violation 

of

Deleted: standards
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

10 

Pesticide Discharge Management Plan (PDMP) 

Distinct from the technology-based or water quality-based effluent limitation provisions 

in the permit, Part 5.0 of the permit requires operators that exceed any annual treatment area 

threshold to prepare a PDMP to document the implementation (including inspection, 

maintenance, monitoring, and corrective action) of control measures being used to comply with 

the effluent limitations set forth in Parts 2.0 and 3.0. 

In general, Part 5.0 requires that the following be documented in the PDMP: (1) pesticide 

discharge management team information; (2) pest management area description; (3) control 

measure description; (4) schedules and procedures pertaining to control measures used to comply 

with the effluent limitations in Part 2 (e.g., application rate and frequency, spill prevention, 

pesticide application equipment, pest surveillance, and assessing environmental conditions) and 

pertaining to other actions necessary to minimize discharges (e.g., spill response procedures, 

adverse incident response procedures, and pesticide monitoring schedules and procedures); and 

(5) documentation to support eligibility considerations under other Federal laws. The PDMP 

must be kept up-to-date and modified whenever necessary to document any corrective actions as 

necessary to meet the effluent limitations in this permit. 

The requirement to prepare a PDMP is not an effluent limitation because it does not 

restrict quantities, rates, and concentrations of constituents that are discharged. CWA section 

502(11). Instead, the requirement to develop a PDMP is a permit “term or condition” authorized 

under sections 402(a)(2) and 308 of the Act. Section 402(a)(2) states, “[t]he Administrator shall 

prescribe conditions for [NPDES] permits to assure compliance with the requirements of 

paragraph (1) of this subsection, including conditions on data and information collection, 

reporting, and such other requirements as he deems appropriate.” The PDMP requirements set 

forth in the permit are terms or conditions under the CWA because the operator is documenting 

information on how it is complying with the effluent limitations (and inspection and evaluation 

requirements) contained elsewhere in the permit. Thus, the requirement to develop a PDMP and 

keep it updated is no different than other information collection conditions, as authorized by 

section 402(a)(2), in other permits. Failure to have a PDMP, where required, is a violation of the 

permit.1

While Part 2 of the permit requires the operator to select control measures to meet the 

effluent limitations in this permit, the control measures themselves described in the PDMP are 

not effluent limitations because the permit does not impose on the operator the obligation to 

comply with the PDMP; rather, the permit imposes on the operator the obligation to meet the 

effluent limitations prescribed in Parts 2.0 and 3.0. Therefore, the operator is free to change as 

appropriate the control measures used to meet the effluent limitations contained in the permit. 

This flexibility helps ensure that the operator is able to adjust its practices as necessary to ensure 

continued compliance with the permit’s effluent limitations. However, the permit also contains a 

recordkeeping condition that requires that the PDMP be updated with any such changes in the 

 1

 This permit is also consistent with the decision in Texas Independent Producers and Royalty Owners 

Assoc., et. al. v. EPA, 410 F.3d 964 (7th Cir. 2005), where petitioners challenged EPA’s issuance of the construction 

general permit (CGP) that covers stormwater discharges. In that case, the Court found that neither the Stormwater 

Pollution Prevention Plan (SWPPP) nor the Notices of Intent (NOIs) are permits or permit applications because they 

do not amount to limits. 410 F.3d at 978. Further, the Court found that the permit requirement to develop a SWPPP 

is not an effluent limitation. For the PGP, the PDMP serves a similar purpose as the CGP SWPPP. 

Deleted: Thus, failure

Deleted: at any time
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

11 

operator’s practices. See Part 5.2. Thus, if an operator’s on-the-ground practices differ from 

what is in the PDMP, this would constitute a violation of the permit’s recordkeeping requirement 

to keep the PDMP up-to-date, and not per se a violation of the permit’s effluent limitations, 

which are distinct from the PDMP. EPA recognizes, however, that because the PDMP 

documents how the operator is meeting the effluent limitations contained in the permit, not 

following through with actions identified by the operator in the PDMP as the method of 

complying with the effluent limitations in the permit is relevant to evaluating whether the 

operator is complying with the permit’s effluent limitations. 

Public Notice 

Once the EDC and Waterkeeper courts found that the plan or NOI contained effluent 

limitations, they stated that the plan or NOI must be available for public comment. The CWA 

contains provisions that relate to public participation in the issuance of permits. For instance, 

CWA section 402(j) states, in relevant part: “A copy of each permit application and each permit 

issued under this section shall be available to the public.” EPA is proposing the general permit 

for public comment, including the effluent limitations, and providing an opportunity to request a 

public hearing on the permit. 

Public Availability of Documents 

Part 5.3 of the permit requires that the operator retain a copy of the current PDMP at the 

address listed on the NOI and it must be immediately available, at the time of an onsite 

inspection or upon request to EPA, a State, Tribal or local agency governing wastewater 

discharges and/or pesticide applications, and representatives of the U.S. Fish and Wildlife 

Service (USFWS) or the National Marine Fisheries Service (NMFS). While not required to be 

submitted to EPA, interested persons can request a copy of the PDMP through EPA, at which 

point EPA will likely request the operator to provide a copy of the PDMP. By requiring 

members of the public to request a copy of the PDMP through EPA, the Agency is able to 

provide the operators with assurance that any Confidential Business Information that may be 

contained within its PDMP is not released to the public. NOIs will be publicly available once 

submitted through the eNOI system. The NOIs generally will be available to the public for 10 

days before permit coverage begins. During this time period, issues can be raised with EPA, 

who has the authority to deny coverage. 

3. Sharing of Responsibilities 

 This general permit was developed with the understanding that there may be more than 

one responsible entity implementing it for a given discharge. As structured, the permit provides 

for sharing of responsibilities to meet the end goal of discharges being in compliance with permit 

requirements. The NPDES regulations state that “operators” are responsible for achieving 

permit compliance. Specifically, 40 CFR 122.21(b) clarifies that when an activity is owned by 

one person but it is operated by another person (e.g. contractor), it is the operator’s duty to meet 

terms of the permit. EPA acknowledges, however, that in many instances the owner may still 

perform operator duties; as such, they may still be required to obtain permit coverage, even in 

situations in which, for example, the owner hires a contractor to apply the pesticides to control 

pests. The PGP includes a definition of an “operator” in Appendix A that is intended to clarify 

this point, focusing on the fact that operator control exists both at the decision-making level 

Deleted: but

Deleted: may be 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

12 

about how to control pests, including financial considerations, as well as at a level where 

activities are performed to ensure compliance with the specific provisions of the permit (such as 

calibration of pesticide application equipment). In these instances, both operators are required to 

obtain NPDES permit coverage; however, the permit strives to minimize any potential 

duplication of effort. In many instances, the requirements that operators must meet depend on 

how their agreements with contractors hired to perform the pest control activities are structured. 

Entities such as subcontractors that are hired by an owner or other entity but are under the 

supervision of such owner or entity generally are not operators. Similarly, you are likely not an 

operator if, for example, you own the land, but the activities are being performed outside of your 

control (e.g., a public entity is spraying for mosquitoes over your property). 

 EPA encourages operators to explore possible cost savings by sharing responsibilities for 

implementing aspects of this permit. For example, a mosquito control district could assume the 

overall coordination of an integrated pest management program while a hired contractor may be 

responsible for minimizing the pesticide discharge and for site monitoring and maintaining and 

calibrating pesticide application equipment. EPA is requiring, however, that in instances where 

multiple operators are responsible for the discharge from larger pesticide application activities, 

some form of written explanation of the division of responsibilities be documented. However, 

any and all operators covered under this permit are still responsible, jointly and severally, for any 

violation that may occur, though EPA may consider this written division of responsibilities when 

determining the appropriate enforcement response to a violation. 

III. Summary of Permit Conditions 

1. Coverage under this Permit 

1.1. Eligibility 

 Only operators meeting the eligibility requirements outlined in the permit may be covered 

under this permit. The activities covered by this permit include the use patterns and types of pest 

control activities described in the vacated 2006 rule. Specifically, this permit covers the 

discharge of pesticides (biological pesticides and chemical pesticides which leave a residue) to 

waters of the U.S. resulting from the following use patterns: (1) Mosquito and Other Flying 

Insect Pest Control; (2) Aquatic Weed and Algae Control; (3) Aquatic Nuisance Animal Control; 

and (4) Forest Canopy Pest Control. If an operator does not meet the eligibility provisions 

described in Part 1.1 of the permit, point source discharges to waters of the U.S. from the 

application of pesticides will be in violation of the CWA, unless the operator has obtained 

coverage under another permit. 

As discussed above, EPA’s decision to include specific use patterns generally stems from 

the Agency’s 2006 rule. That rule provided that NPDES permits are not required for the 

application of pesticides when these pesticides are applied consistent with all relevant 

requirements under FIFRA (i.e., those relevant to protecting water quality), in the following two 

circumstances: 

Formatted: Font color: Black

Deleted: the operator

Deleted: that 

Deleted: acknowledgement
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

13 

1) The application of pesticides directly to waters of the U.S. in order to control pests. 

Examples of such applications include applications to control mosquito larvae, 

aquatic weeds, or other pests that are present in the waters of the U.S. 

2) The application of pesticides to control pests that are present over waters of the U.S., 

including near such waters, where a portion of the pesticides will unavoidably be 

deposited into waters of the U.S. in order to target pests effectively; for example, 

when insecticides are aerially applied to a forest canopy where waters of the U.S. may 

be present below the canopy or when pesticides are applied over or near water for the 

control of adult mosquitoes or other pests. 

EPA reasoned that such products were not “pollutants” because they served the beneficial 

purpose of controlling pests. In promulgating this rule, EPA expressly noted that the rule did not 

cover either “spray drift” – the airborne movement of pesticide sprays away from the target 

application site into a water of the U.S. – or applications of pesticides to terrestrial agricultural 

crops. To address the vacated 2006 Rule, the PGP is designed to cover activities in which it is 

unavoidable that some of the pesticides will be deposited into water in order to effectively target 

the pests. 

Consistent with the 2006 Rule, this PGP does not cover spray drift resulting from 

pesticide applications. Instead, to address spray drift, EPA established a multi-stakeholder 

workgroup under the Pesticides Program Dialogue Committee (PPDC), an advisory committee 

chartered under the Federal Advisory Committee Act (FACA) to explore policy issues relating 

spray drift. The goals of the workgroup were: (1) improving the understanding of the 

perspectives of all stakeholders regarding pesticide spray drift; (2) finding common ground for 

further work toward minimizing both the occurrence and potential adverse effects of pesticide 

spray drift; (3) developing options for undertaking work where common ground exists; and (4) 

exploring the extent of drift, even with proper usage, and the range and effectiveness of potential 

responses to unacceptable levels of off-target drift. On November 4, 2009, EPA issued a draft 

Pesticide Registration Notice (PR Notice) for public comment. The actions detailed in the PR 

Notice focus on improving the clarity and consistency of pesticide labels in order to reduce spray 

drift and prevent harm to human health and the environment. The draft PR Notice and related 

documents are available in Docket EPA-HQ-OPP-2009-0628 at www.regulations.gov. EPA is 

currently reviewing the public comments received. 

Scope of Permit 

 As stated above, the Sixth Circuit found that if a chemical pesticide leaves any excess or 

residue after performing its intended purpose, such excess or residue would be considered a 

pollutant under the CWA. The Court also found that, unlike chemical pesticides, not only would 

the residue and excess quantities of a biological pesticide be considered a pollutant, but so too 

would the biological pesticide itself. 

Although the court did not define what a residual is, for purposes of this permit, EPA 

assumes that all chemical pesticides will leave a residual once the product has performed its 

intended purpose. 

Deleted: described below 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

14 

EPA offers the following guidance with respect to the use patterns of chemical pesticides 

covered by this general permit. 

1. If the application of a chemical pesticide is made over a water of the U.S. to control 

pests over the water, any amount of the pesticide that falls into the water of the U.S. is 

“excess” pesticide and would require coverage by an NPDES permit. Based on field 

studies of pesticide applications, the Agency expects that some portion of every 

application of a pesticide made over a water of the U.S. will fall directly into the 

water of the U.S. and thus assumes that applications will trigger the requirement for 

an NPDES permit. Any person who wishes to contest this assumption should submit 

scientific data to prove that no quantity of the pesticide falls into a water of the U.S. 

A permit may not be necessary if EPA receives scientific information which 

convinces the Agency that no portion of a chemical pesticide applied over a water of 

the U.S. will fall into the water of the U.S.. 

2. If the application of a chemical pesticide is made into a water of the U.S. to control a 

pest in the water of the U.S., once the pesticide no longer provides any pesticidal 

benefit, any amount of the pesticide that remains in the water of the U.S. is a 

“residual” and would require coverage by an NPDES permit. Based on field studies 

of pesticides applied into water, the Agency expects that some portion of every 

application of a pesticide made into a water of the U.S. will leave a residual in the 

water of the U.S. and thus assumes every application will trigger the requirement for 

an NPDES permit. Any person who wishes to dispute this assumption should submit 

scientific data to prove that no quantity of the pesticide will remain as a residual in a 

water of the U.S. The data should include data to show what level of the pesticide 

can be detected in water, and at what level in water the pesticide provides a pesticidal 

benefit. Such data should address the properties of the chemical pesticide under 

different water conditions (e.g., different pH, organic content, temperature, depth, 

etc.) that might affect the pesticide’s properties. A permit may not be necessary if 

EPA receives scientific information that convinces the Agency that a chemical 

pesticide applied into a water of the U.S. will not remain as a residual in the water of 

the U.S. 

 For purposes of this permit, EPA is relying on existing regulatory definitions in 40 CFR 

174.3 and 158.2100(a) developed under FIFRA to define the term “biological pesticides.” For 

purposes of this permit, EPA identifies biological pesticides (also called “biopesticides” under 

FIFRA regulations) to include microbial pesticides [40 CFR 158.2100(a)] and biochemical 

pesticides and plant-incorporated protectants. [40 CFR 174.3] 

How the Court’s Decision Expands the NPDES Program 

EPA estimates that nationwide (this includes the EPA-issued permit as well as the states 

issuing their own NPDES permits), approximately 365,000 pesticide applicators perform 5.6 

million applications a year for the four use patterns covered under the PGP. This permit covers 

only six of the fifty states (and many other smaller areas, such as most U.S. territories and Indian 

Country lands) for which EPA assumes approximately 10 percent of the applications will occur 

in these areas based on the fact that approximately 10 percent of the population lives in these 

areas. The remaining 90 percent of pest control activities will occur in areas covered under state-
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

15 

issued NPDES permits. If each applicator needs NPDES permit coverage, this represents an 

approximately 65% increase in the number of NPDES permittees (up from EPA’s current 

estimate of 565,000 permittees annually). It should be noted that the four use patterns do not 

include the control of agricultural, ornamental or silvicultural terrestrial pests that are routinely 

controlled as part of production of agricultural or ornamental plant commodities and in forestry 

operations. The fact sheet does not address every activity which may involve a point source 

discharge of pollutants to waters of the US that would require a permit. However, any pesticide 

application activities that do not fall within the four use patterns covered by this permit will 

require coverage under some other NPDES permit if those activities result in point source 

discharges to waters of the U.S. 

Additionally, the permit does not cover discharges that, by law, are not required to obtain 

NPDES permit coverage. Of note, the CWA specifically excludes from the definition of point 

source, “agricultural stormwater discharges and return flow from irrigated agriculture.” Nothing 

in this permit changes the effect of those statutory exemptions. Thus, for example, the 

application of a pesticide to an agricultural crop for the control of terrestrial pests that later runs 

off the field, either as irrigation return flow or stormwater runoff, is exempt from permit 

coverage even if that discharge to a water of the U.S. is known to contain pesticide residuals. 

Also, as a result of the court’s decision to vacate the 2006 NPDES Pesticides Rule, discharges 

from the application of pesticides to irrigation ditches and canals that are either waters of the 

U.S. or convey to waters of the U.S. now require NPDES permit coverage. These discharges, 

i.e., from application of pesticides to “irrigation systems and along canal banks” were 

specifically included in the preamble and response to comment on the now vacated 2006 NPDES 

Pesticides Rule as not needing NPDES permits because the application was not a discharge of a 

pollutant.

More detailed discussion of the types of activities included under each of the four 

pesticide use patterns and the permit requirements are provided in Part III.2 of the fact sheet. 

 EPA acknowledges that it has been difficult to derive definitive estimates of the number 

of activities actually conducted and potentially covered under the PGP and points to two main 

limitations of the available data. 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. Second, the CWA does not define the terms “application” or “applicator” as it 

relates to discharges from pesticide applications. Thus, available data may not all use similar 

definitions of these terms. More detail, by pesticide use pattern, is provided in the Economic 

Analysis and the table entitled “NPDES Applicator & Application Estimates” that is included in 

the administrative record for this permit. 

1.1.2 Limitations on Coverage 

1.1.2.1 Discharges to Water Quality Impaired Waters 

Coverage under the PGP is only available with this general permit for certain discharges 

to impaired waters. For example, discharges to waters which are impaired for pollutants other 

than the pesticide or its degradate, are eligible for coverage. Also, discharges to waters impaired 

for temperature or some other indicator parameter, or for physical impairments such as “habitat 

Formatted: Tabs: Not at 0.5" + 

0.75"

Deleted: These, and other use patterns, 

not covered under this permit,

Deleted: where 

Deleted: pesticide applications
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

16 

alteration” are also eligible for PGP coverage. Conversely, the permit is not available for the 

discharge of any pesticide to water that is impaired for the specific pesticide or degradates of that 

pesticide. For example, application of the pesticide copper sulfate to a waterbody impaired for 

either copper or sulfates would not be eligible for coverage under this permit, because copper 

sulfate can degrade into these two substances. In this instance, the operator would have to 

choose between obtaining coverage under an individual permit for such a discharge or selecting 

some other means of pest management, e.g., using mechanical means or some other pesticide 

product. 

For this permit, EPA determined that it does not have information warranting a limitation 

for all impaired waters regardless of the impairment. In fact, in some instances, the application of 

a pesticide to water actually can improve the quality of the water such as when used to control 

algae growth that can deplete oxygen levels in water. It is important to note that this permit 

allows EPA, based on additional information, to opt not to approve coverage under the PGP, or 

at a later date to require an operator covered under the PGP to apply for coverage under an 

individual permit. 

For purposes of this permit, impaired waters are those which have been identified by a 

State, Territory, Tribe, or EPA pursuant to Section 303(d) of the CWA as not meeting applicable 

State, Territorial, and Tribal water quality standards. Impaired waters for purposes of this permit 

include both waters with EPA-approved and EPA-established Total Maximum Daily Loads 

(TMDLs) and those for which EPA has not yet approved or established a TMDL. (A list of 

impaired waters, along with the pollutants or pollution identified as the cause of the impairment 

is available at www.epa.gov/owow/tmdl). It is EPA’s opinion that the 303(d) list is not a final 

determination of impairments, however, it is the best available information for operators to use 

when deciding whether their discharges meet the eligibility requirements regarding water bodies 

impaired for specific pesticides. These requirements this will further ensure protection of water 

quality. 

Also, several states have listed waters as impaired for “pesticides” but have not identified 

the specific pesticide for which the waterbody is impaired. Without additional information 

suggesting that the waterbody is impaired for a specific pesticide, EPA is proposing to provide 

coverage under this permit for discharges of pesticides to waters that are impaired generally for 

“pesticides.” The Agency expects that as these impaired waters are further assessed, specific 

pesticides or classes of pesticides will be identified as the cause of the impairment – at which 

point dischargers will no longer be eligible to obtain permit coverage under the PGP for 

discharges of those named pesticides or their degradates. 

 

1.1.2.2 Discharges to Waters Designated as Tier 3 for Antidegradation Purposes 

Tier 3 waters are identified as outstanding national resource waters and generally include 

the highest quality waters of the U.S. Except for certain temporary changes, water quality cannot 

be lowered in such waters. In broad terms, EPA’s view of “temporary” is weeks and months not 

years. The Tier 3 designation also provides special protection for waters of exceptional 

ecological significance, i.e., those which are important, unique, or sensitive ecologically. States 

and Tribes make the decision of which waterbodies to designate as Tier 3. A list of Tier 3 waters 

in areas where the PGP is available will be available on the Internet, similar to how this list is 

Field Code Changed

Deleted: EPA has determined

Deleted: although this

Deleted: which

Deleted: are better suited under the 

individual permit scheme. In turn,
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

17 

currently provided for stormwater discharges: (see 

http://cfpub.epa.gov/npdes/stormwater/antideg.cfm). 

EPA believes that blanket coverage under the PGP for discharges to Tier 3 waters is 

inconsistent with Tier 3 anti-degradation requirements. Additionally, in order to allow such 

discharges, the Agency would have to determine for all of these waters that such discharges 

would maintain and protect Tier 3 water quality. Instead, operators applying pesticides that could 

result in discharges to Tier 3 waters of the U.S. must apply for individual permits. 

Note about alternate antidegradation designations used by some States: Some States have 

adopted alternative approaches to designating Tier 2 or Tier 3 waters. These are collectively 

referred to as “Tier 2.5” waters since they fall between Tiers 2 and 3 in terms of characteristics 

and regulations supporting them. Tier 2.5 waters are commonly described as providing 

protection more stringent than Tier 2 but allowing some added flexibility that a Tier 3-designated 

water (Outstanding National Resource Water) would not. Refer to Memorandum from William 

Diamond (Former Director, Standards and Applied Science Division) to Victoria Binetti (Chief, 

Region III, Program and Support Branch), June 13, 1991. Examples of Tier 2.5 waters exist in 

Massachusetts, which designates “outstanding resource waters” (ORWs). These waters have 

exceptional sociologic, recreational, ecological and/or aesthetic values and are subject to more 

stringent requirements under both the Massachusetts Water Quality Standards and the 

Massachusetts Stormwater Management Standards. ORWs include vernal pools certified by the 

Natural Heritage Program of the Massachusetts Department of Fisheries and Wildlife and 

Environmental Law Enforcement, all Class A designated public water supplies with their 

bordering vegetated wetlands, and other waters specifically designated. The PGP is available for 

use for discharges to Tier 2.5 waters. 

1.1.2.3 Discharges Currently or Previously Covered by another Permit 

This Part of the PGP describes situations where an operator is ineligible for coverage 

under this permit because of coverage under another permit. These include discharges currently 

covered under an NPDES permit; discharges covered by a permit within the past five years prior 

to the effective date of this permit which established site-specific numeric water quality-based 

limitations; and discharges from activities where the associated NPDES permit has been or is in 

the process of being denied, terminated, or revoked by EPA (although this last provision does not 

apply to the routine reissuance of permits every five years). 

EPA is including this last provision to be clear that it is not possible to obtain coverage 

by requesting termination of an individual permit and then submitting an NOI for coverage under 

the PGP. To avoid potential conflicts with the anti-backsliding provisions of the CWA, transfer 

from an individual permit to the PGP is only allowed under limited conditions, including that the 

individual permit did not contain numeric water quality-based effluent limits. In order for a 

transfer to be permissible, EPA must find compliance with all the conditions of the PGP are at 

least as stringent as meeting the conditions of the individual permit. 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

18 

1.2 AUTHORIZATION TO DISCHARGE UNDER THIS PERMIT 

1.2.1 No Requirement to Submit a Notice of Intent (NOI) for Certain Applications 

Under 40 CFR § 122.28 (b)(2)(v), some pesticide application operators may, at the 

discretion of the Director2

, “be authorized to discharge under a general permit without 

submitting a notice of intent where EPA finds that a notice of intent requirement would be 

inappropriate.” In making such a finding, EPA must consider: “the type of discharge; the 

expected nature of the discharge; the potential for toxic and conventional pollutants in the 

discharges; the expected volume of the discharges; other means of identifying discharges 

covered by the permit; and the estimated number of discharges to be covered by the permit.” 

EPA’s focus is on the largest applications of pesticides to water of the U.S. When EPA 

analyzed the regulatory considerations provided in §122.28(b)(2)(v), it gave particular weight to 

the expected volume of the discharges and the estimated number of discharges to be covered by 

the permit. After considering the universe of entities in light of the regulatory considerations 

EPA found a logical break between entities applying pesticides to larger areas versus smaller 

areas. EPA’s consideration of the regulatory factors is as follows: 

All discharges authorized by this general permit involve applications made directly to 

waters of the U.S. in order to control pests in or over the water or applications to control pests 

near water in which pesticides will make unavoidable contact with the water. The general permit 

is structured by pesticide use patterns. These use patterns were developed to include discharges 

that are similar in type and nature and therefore represent the type of discharges and expected 

nature of the discharges covered under this permit. The general permit covers the following use 

patterns: 

Mosquito and Other Flying Insect Pest Control

This use pattern includes the application, by any means, of chemical and biological 

insecticides and larvicides into or over water to control insects that breed or live in, over, 

or near water. Applications of this nature usually involve the use of ultra low volume 

sprays or granular larvicides discharged over large swaths of mosquito breeding habitat 

and may occur several times per year. 

 

Aquatic Weed and Algae Control 

This use pattern includes the application, by any means, of contact or systemic herbicides 

to control vegetation and algae in water and at water’s edge, including irrigation ditches 

and/or irrigation canals. Applications of this nature may be single spot treatments of 

infestations or staged large scale treatments intended to clear several acres of waterway. 

Treatments may be singular or occur several times per year. 

Aquatic Nuisance Animal Control

This use pattern includes the application, by any means, of chemicals into waters to 

control a range of animals for purposes such as fisheries management, invasive species 

eradication or equipment maintenance. Applications of this nature are usually made over 

 2

 Defined in 40 CFR § 122.2 for this permit to mean “EPA.”
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

19 

an entire waterbody as the target pests are mobile. Treatments are generally made several 

years apart. 

 

Forest Canopy Pest Control

This use pattern includes aerial pest control projects, in and over forest canopies where 

there are waters of the U.S. below the canopy. Applications of this nature usually occur 

over large tracts of land, and are typically made in response to specific outbreaks. EPA 

understands that for this use pattern pesticides will be unavoidably discharged into waters 

in the course of controlling for pests that are present near or over waters as a result of the 

aerially spraying (i.e., a point source discharge from a nozzle) over a forest canopy. 

These pests are not necessarily aquatic (e.g., airborne non-aquatic insects) but are 

detrimental to industry, the environment, and public health. Note: EPA recognizes that 

mosquito adulticides may be applied to forest canopies, in which case the application 

would be covered under the “Mosquito and Other Flying Insect Pest Control” use pattern. 

EPA understands that prior to initiating the 2006 NPDES Pesticides Rule the Agency had 

interpreted the Clean Water Act and its implementing regulations as not requiring a 

NPDES permit for forest pest control activities. The rule stated that pesticides applied 

consistently with FIFRA do not require an NPDES permit in certain circumstances, 

including the aerial application of insecticides to a forest canopy. 71 Fed. Reg. at 68,482. 

Vacating the 2006 NPDES Pesticides Rule, the Sixth Circuit Court of Appeals held that 

“dischargers of pesticide pollutants are subject to the NPDES permitting program in the 

Clean Water Act.” National Cotton Council, 553 F.3d 927, 940. EPA therefore now 

requires all dischargers of pesticide pollutants, including dischargers in and over forest 

canopies where there are waters of the U.S. below the canopy, to obtain NPDES permits.

EPA also considered the expected volume of discharges from each use pattern. It is 

difficult to estimate the expected volume of discharges for each use pattern because control 

measures used by permittees to meet the permit’s technology based effluent limitations may vary 

based on site-specific conditions. For example, the volume of the discharge may vary depending 

on the specific pesticide being used, the intensity of the pest pressure based on the specific pest 

problem, and the pest management strategy deemed to be most effective for the pest problem. 

Moreover, the lowest effective amount of pesticide product necessary to manage pests 

successfully will vary among operators depending on which control measures the operator uses. 

Nonetheless, EPA expects that, in general, the volume of the discharge will vary proportionally 

with the number of acres and linear miles treated. Therefore, for all use patterns, EPA expects 

that the volume of the discharge for a given pesticide application will be lower when fewer acres 

or linear feet are treated over a calendar year. Moreover, while there may be more operators 

applying pesticides to small treatments areas when compared to operators applying to large 

treatment areas, the volume of discharges from operators applying to small treatment areas is 

believed to be substantially less on a per applicator basis and cumulatively less than the volume 

of discharges from applications made by operators applying to large treatment areas. 

Similarly, EPA does not expect the potential for toxic and conventional pollutants in the 

discharges from pesticides to vary among use patterns. EPA would expect, however, that the 

potential for high concentrations of toxic or conventional pollutants in the discharge would be 

smaller when fewer acres or linear feet are treated. 

Deleted: that 

Deleted: to
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

20 

EPA also considered other means of identifying types of discharges covered by this 

permit. EPA may be able to identify pesticide discharges from operator submitted data, ambient 

water sampling data reported to EPA and the States, as well as reported information submitted by 

pesticide dischargers pursuant to state law. EPA recognizes that the availability, quality, and 

uniformity of these data may be limited. 

Lastly, EPA considered the estimated number of discharges to be covered by the permit. 

While the exact number of entities and thus the number of categorical discharges which may be 

covered by the permit is unknown, EPA estimates that the PGP covers more than 30,000 

applicators per year in the states for which EPA is the permitting authority. Of this total, a large 

majority represent applicators performing small pesticide treatments that EPA considers to have 

very low potential for impact (such as herbicide treatments to short sections of ditch or canal 

banks). Thus, requiring an NOI from all dischargers would be a large burden of little value for 

permitting authorities and permittees alike. 

Based on the analysis outlined above, EPA has determined that it would be inappropriate 

to require operators that apply pesticides to relatively small areas to submit NOIs. Therefore, 

EPA is exercising its discretion and not requiring these operators to submit NOIs. EPA 

developed annual treatment area thresholds for each use pattern that it believes will only exclude 

those operators making small-area applications from the NOI requirement because their 

discharges will be comparatively small. 

To determine the appropriate annual treatment area thresholds that would trigger the NOI 

requirement, EPA’s Office of Water, Office of Pesticides, Pollution, and Toxic Substances, and 

Regional Offices, engaged in discussions with USDA, states as co-regulators, and representatives 

from industry including pesticide registrants, applicators, and land managers. Based on these 

discussions and EPA’s best professional judgment, EPA developed annual treatment area 

thresholds that differentiate between applications to small areas and those treatments to larger 

areas which are believed to have a greater potential for impact on waters of the U.S. EPA 

recognizes there are many unknowns concerning the size, organization, and activities of the 

permitted universe. Considerable variation in the availability of data and in the consistency of 

requirements across regions and states resulted in EPA depending on its best professional 

judgment in setting the NOI annual treatment area thresholds for each of the use patterns. EPA 

will use any additional information received to determine if the annual treatment area thresholds 

are appropriate in the finalized permit and the next permit cycle. 

Deleted: ditchbank
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

21 

EPA established the following annual (calendar year) treatment area thresholds for the 

four use patterns under this permit: 

PGP Part Pesticide Use Annual Threshold 

Part 2.2.1 Mosquitoes and Other Flying Insect Pests 640 acres of treatment area 

In Water: Aquatic Weeds and Algae 20 acres of treatment area 1 Part 2.2.2 

At Waters Edge: Aquatic Weeds and Algae 20 linear miles of treatment area 

at water’s edge 2

In Water: Aquatic Nuisance Animals 20 acres of treatment area 1 Part 2.2.3 

At Waters Edge: Aquatic Nuisance Animals 20 linear miles of treatment area 

at water’s edge 2

Part 2.2.4 Forest Canopy 640 acres of forest canopy 

1 Calculations should include the area of the applications made to: (1) waters of the U.S. and (2) conveyances 

with a hydrologic surface connection to waters of the U.S. at the time of pesticide application. For calculating 

annual treatment area totals, count each pesticide application activity as a separate activity. For example, 

applying pesticides twice a year to a ten acre site should be counted as twenty acres of treatment area. 

2 Calculations should include the area of the application made at water’s edge adjacent to: (1) waters of the U.S. 

and (2) conveyances with a hydrologic surface connection to a water of the U.S. at the time of pesticide 

application. For calculating annual treatment totals, count each pesticide application activity as a separate 

activity. For example, treating both sides of a ten mile ditch is equal to twenty miles of water treatment area. 

Any operator that has reason to believe it will exceed one or more of the annual treatment 

area thresholds in any calendar year of the permit cycle must submit a Notice of Intent to obtain 

coverage. To determine whether the pesticide application operators are required to submit an 

NOI, the operator must compare the total area in which the pesticide is intended to be effective 

multiplied by the number of times that area is treated per year. 

EPA’s rationale for the annual treatment area threshold for each use pattern is as follows: 

Mosquito Control and Other Flying Insect Pest Control 

For Mosquitoes and Other Flying Insect Pest, the annual treatment area threshold has 

been set at 640 acres. EPA believes that the vast majority of mosquito control and 

abatement districts in the U.S. manage areas significantly larger than this threshold and 

may reasonably expect to exceed it during any given year. For instance, information 

from the state of Florida on 49 independent mosquito control districts shows that 48 of 

the 49 districts annually apply to more than 640 acres, which indicates that applications 

exceeding this area are quite typical. Similarly, data provided in EPA’s draft Economic 

Achievability Analysis of the Pesticide General Permit (PGP) for Point Source 

Discharges from the Application of Pesticides and included in the administrative record 

for this permit show similar findings as for Florida. Furthermore, the effective control of 

other aquatic breeding, flying insects, such as the blackfly, necessitates an application 

approaching or exceeding this threshold. Therefore, EPA believes the threshold 

appropriately captures most operators engaging in this use pattern. 

Aquatic Weed and Algae Control 

For Aquatic Weeds and Algae, the annual treatment area threshold has been set at 20 

acres or 20 linear miles of treatment on canals and irrigation system conveyances. This 

threshold has been set to capture operators treating relatively large portions of surface 

waters and watersheds, such as water management districts, wildlife and game 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

22 

departments, and some homeowner and lake associations. For example, Florida’s South 

Florida Water Management District usually performs treatments of generally 60 acres at a 

time hundreds of times per year for various invasive plants on Florida’s Lake 

Okeechobee. After reviewing the operations of major irrigation and flood control 

systems, EPA expects that generally, relatively large entities such as South Florida Water 

Management District or California Department of Water Resources or organizations with 

comparable resources are the types of entities that manage 20 or more miles of 

engineered irrigation system conveyances and that this is a reasonable limit to trigger the 

NOI requirement. The same rationale is applied to managers of ditch and canal banks. 

Therefore, EPA believes the threshold appropriately captures the relatively large 

applications but excludes a significant number of small applications.

Aquatic Nuisance Animal Control

Invasive and Nuisance Aquatic Animals are most commonly treated by public agencies 

such as departments of fish and game or utilities such as water management districts that 

manage areas of surface water in excess of 20 acres. The high mobility and prolific 

breeding ability that necessitate control of aquatic animals usually means that their 

treatment most often occurs in the entirety or large portions of the water bodies they 

inhabit. For example, fishery management treatments using rotenone must occur in the 

entire lake and, thus any treatment to a lake of more than 20 acres in area will trigger the 

annual treatment area threshold. EPA expects that for this reason, only spot treatments to 

eradicate small emergent populations of sessile animals or treatments to very small water 

bodies might be excluded from an NOI requirement. Therefore, EPA believes the 

threshold appropriately captures the relatively large operators engaging in this use 

pattern. 

Forest Canopy Pest Control

Forest canopy pest suppression programs are designed to aerially blanket large tracts of 

terrain, throughout which operators may not be able to see waters of the U.S. beneath the 

canopy. EPA has set the annual treatment area threshold at 640 acres for this use pattern 

with the understanding that this will exclude only the smallest applications from the NOI 

requirement. These smaller applications generally occur on private lands. Therefore, 

EPA believes the threshold appropriately captures most operators engaging in this use 

pattern, particularly public agencies managing large tracts of land. 

1.2.2 How to Obtain Authorization 

To obtain authorization under the permit, operators must meet the Part 1.1 eligibility 

requirements and, if required by Part 1.2.2 of the permit, submit a complete and accurate NOI 

according to the requirements in Appendix D no later than the appropriate deadline described in 

Part 1.2.3. 

Part 1.2.2 describes which operators are required to submit an NOI, and Table 2 sets out 

the timeframes within which an NOI must be submitted. An operator is required to submit an 

NOI if his application area exceeds any applicable annual treatment area threshold during any 

calendar year of the permit cycle. 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

23 

1.2.2.1 Operators Required to Submit NOIs 

 An operator is required to submit a Notice of Intent to obtain coverage under this general 

permit for discharges resulting from the application of pesticides if it has reason to believe it will 

exceed one or more of the annual (i.e., calendar year) treatment area thresholds. 

Operators hiring another party to apply pesticides are responsible for submitting an NOI 

if: 

- The application exceeds any applicable annual treatment area threshold, or 

- The application, in addition to any other treatments made under the hiring 

operator’s authority in the same calendar year, will exceed any applicable annual 

treatment area threshold. 

For-hire applicators applying pesticides under contract from another party will include the 

acreage treated on behalf of the client in their annual total unless that client has submitted or has 

responsibility for submitting an NOI reflecting that treatment per the NOI requirements. If the 

client has already submitted an NOI for the area to be treated, the applicator does not need to 

include it in her NOI threshold calculation.

Operators required to submit an NOI for their application must submit an NOI in 

accordance with Table 2 of the permit. When completing the NOI form, the operator is asked to 

define the general area in which the discharge is expected to occur and the use pattern with 

which the discharge is associated. The form will allow EPA to better understand where certain 

discharges typically occur. Table 2 specifies applicable deadlines for different categories of 

operators to submit NOIs. 

Based on a review of the NOI or other information, EPA may in certain, limited 

circumstances delay the authorization of the operator’s discharge or may deny coverage under 

the permit and require submission of an application for an individual NPDES permit, as detailed 

in Part 1.3. EPA will notify the operator in writing of any such delay or the request for 

submission of an individual NPDES permit application. 

1.2.2.2 Operators Not Required to Submit NOIs 

An operator is not required to submit an NOI pursuant to Part 1.2.1 of the permit if no 

application is made in excess of any applicable annual treatment area threshold during any 

calendar year of the permit cycle (typically 5 years). Operators whose discharges are authorized 

by this permit but are not required to submit an NOI would automatically be covered under the 

permit for their application and would be authorized to discharge in accordance with the permit 

requirements as soon as the permit becomes effective. Nonetheless, EPA emphasizes that these 

operators would still be subject to all applicable requirements contained within the permit. If an 

operator, otherwise not required to submit an NOI, anticipates that he or she will exceed an 

applicable annual treatment area threshold during any time in a given calendar year of the permit 

cycle, he or she must submit an NOI at least 10 days prior to exceeding the threshold to continue 

to be authorized to discharge. EPA is requiring NOIs be submitted at least 10 days in advance of 

permit authorization to provide EPA with time necessary to ensure that permit coverage is 

appropriate for those activities identified in the NOI. If an operator that is not required to submit 

Deleted: 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

24 

an NOI wants EPA to consider alternative permit requirements for the application, the operator 

must apply to EPA for a substitute individual permit applicable to his or her application as 

required by Part 1.3 of the permit (Alternative Permits). 

1.2.3 Discharge Authorization Date 

Table 2 specifies applicable deadlines for different categories of operators to submit 

NOIs. Timing for NOI submittal is based on an operator determination that they will exceed a 

treatment area threshold during the calendar year, not on the time when the threshold is actually 

exceeded. For operators making such a determination prior to commencement of discharge, an 

NOI is due at least 10 days prior to commencement of discharge and the operator shall be 

authorized to discharge 10 days after EPA receipt and posting of a complete and accurate NOI. 

For operators making a determination after commencement of discharge (it was unexpected or 

unforeseen that a treatment area threshold would be exceeded for that year) an NOI is due at 

least 10 days prior to exceeding an annual threshold during any calendar year. In this situation, 

the operator’s original authorization to discharge without having submitted an NOI expires when 

the threshold is exceeded. The operator is reauthorized 10 days after EPA receipt of a complete 

and accurate NOI unless EPA denies authorization. For this reason, it is important that operators 

in this situation submit their NOI at least 10 days before the threshold will be exceeded. For 

operators commencing discharge in response to a declared emergency situation (as defined in 

Appendix A of the permit), discharge authorization is granted immediately, but a complete and 

accurate NOI is due no later than 30 days after commencement of discharge if that discharge has 

exceeded a threshold. This is so that emergency response operations may be conducted without 

interruption. The deadlines are displayed in the following table: 

Discharge Authorization Date 

Category 

NOI Submittal 

Deadline Discharge Authorization Date 

Operators not required to submit an 

NOI. 

Not applicable. Immediately. 

Operators who are aware or should be 

aware, prior to commencement of 

discharge, that they will exceed an 

annual treatment area threshold 

identified in Part 1.2.2 for that year. 

At least 10 days 

prior to 

commencement of 

discharge. 

No earlier than 10 days after EPA 

posts on the Internet receipt of your 

complete and accurate NOI. 

Operators who cannot determine until 

after commencement of discharge, that 

they will exceed an annual treatment 

area threshold identified in Part 1.2.2 

for that year. 

At least 10 days 

prior to exceeding 

an annual treatment 

area threshold. 

Original authorization terminates 

when annual treatment area threshold 

is exceeded . Operator is 

reauthorized no earlier than 10 days 

after EPA posts on the Internet 

receipt of your complete and accurate 

NOI. 

Operators commencing discharge in 

response to a declared pest emergency 

situation as defined in Appendix A. 

No later than 30 

days after 

commencement of 

discharge.3

Immediately, for activities conducted 

in response to declared pest 

emergency situation. 

 3

 In the event that a discharge occurs prior to your submitting an NOI, you must comply with all other requirements of 

this permit immediately.

Deleted: annual treatment area 

Deleted: approached 

Deleted: if a complete and accurate 

NOI has not been received by this time

Deleted: if a complete and accurate 

NOI has not been received by this time
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

25 

NOIs submitted electronically are instantaneously posted on the NPDES website and the 

operator will normally be authorized to discharge 10 days after the posting, and will receive 

automatic confirmation of authorization. 

1.2.4 Continuation of this Permit. 

 If this permit is not reissued or replaced (or revoked or terminated) prior to its expiration 

date, existing dischargers are covered under an administrative continuance, in accordance with 

40 CFR § 122.6. If coverage is provided to a permittee prior to the expiration date of this permit, 

the permittee is authorized to discharge under this permit until the earliest of: 

(a) Your authorization for coverage under a reissued permit or a replacement of this permit 

following your timely and appropriate submittal of a complete NOI (if required) requesting 

authorization to discharge under the new permit and compliance with the requirements of the 

NOI (if you are below the NOI threshold, your authorization is automatically extended until you 

are covered under a revised or replacement permit); 

(b) The processing and posting of your Notice of Termination consistent with Part 1.2.5.1; 

(c) The issuance or denial of an individual permit for a discharge resulting from application of a 

pesticide that would otherwise be covered under this permit; 

 (d) A formal permit decision by EPA not to reissue this general permit, at which time EPA will 

identify a reasonable time period for covered dischargers to seek coverage under an alternative 

general permit or an individual permit. Coverage under this permit will cease when coverage 

under another permit is granted/authorized; or 

(e) EPA has informed you that you are no longer covered under this permit. 

Where EPA fails to issue a final general permit prior to the expiration of a previous general 

permit, EPA has the authority to administratively extend the permit for permittees authorized to 

discharge under the prior general permit. However, EPA does not have the authority to provide 

coverage to facilities not authorized to discharge under that prior general permit. 

1.2.5 Terminating Coverage 

1.2.5.1 Submitting a Notice of Termination. 

The permit requires permittees to use the eNOI system to file Notices of Termination. To 

terminate coverage under this permit, the permittee is required under the permit to submit a 

Notice of Termination in accordance with information identified in Appendix E. The permittee’s 

authorization to discharge under the permit terminates at midnight of the day that a complete 

Notice of Termination is processed and posted on EPA’s website 

(www.epa.gov/npdes/noisearch). The requirement to submit a Notice of Termination applies 

only to those operators that were required to submit a Notice of Intent to obtain permit coverage. 

Dischargers automatically covered under this permit as identified in Part 1.2.3 are likewise 

automatically terminated upon permanent cessation of discharge consistent with any of the 

criteria identified in Part 1.2.5.2. 

Field Code Changed
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

26 

EPA requires permittees to file a Notice of Termination to notify EPA that its obligation 

to manage pesticide discharges is no longer necessary for one of the EPA-approved reasons (as 

described in Part 1.2.5.2). If EPA determines that the permittee has not satisfied one of the 

conditions in Part 1.2.5.2 for being able to submit a Notice of Termination (e.g., the permittee 

continues to have a discharge), then the notice is not valid and the permittee must continue to 

comply with the conditions of the permit. Likewise, if EPA determines that the Notice of 

Termination is incomplete, the permittee may be found to be in violation of reporting 

requirements under Section 308 of the CWA.

1.2.5.2 When to Submit a Notice of Termination. 

Once all point source discharges associated with pesticide application have ceased, the 

permittee must submit a Notice of Termination, as described in Part 1.2.5.1, within 30 days after 

one or more of the following conditions have been met: (1) a new operator has taken over 

responsibility for the pest treatment; (2) operations have ceased for which permit coverage had 

been obtained or there will no longer be discharges from such activities, or (3) permit coverage 

has been obtained under an individual or alternative general permit for all discharges requiring 

NPDES permit coverage (unless you obtained coverage under an alternative permit based on an 

EPA request consistent with Part 1.3, in which case coverage under this permit will terminate 

automatically once coverage under that alternative permit is obtained and a Notice of 

Termination is not required).

 EPA is requiring a Notice of Termination from operators identified in (3) above – i.e., 

operators that on their own switch to a different permit – to provide the Agency with clear notice 

that the operator’s discharge is not covered under two NPDES permits. Operators that terminate 

coverage based on an EPA request consistent with Part 1.3 are not required to submit a Notice of 

Termination. 

1.3. Alternative Permits 

EPA Requiring Coverage under an Alternative Permit 

EPA may require an individual permit (in accordance with 40 CFR 122.28(b)(3)(ii)) or 

coverage under an alternative NPDES general permit instead of the PGP. The regulations also 

provide that any interested party may petition EPA to take such an action. The issuance of the 

individual permit or alternative NPDES general permit is in accordance with 40 CFR Part 124 

and provides for public comment and appeal of any final permit decision. The circumstances in 

which such an action would be taken are set forth at 40 CFR 122.28(b)(3). EPA notes that 

discharges of pesticides from some vessels are already covered under the Vessel General Permit 

and do not require coverage under this general permit (see EPA NPDES Vessels General Permit 

at http://www.epa.gov/NPDES/vessels).

Permittee Requesting Coverage under an Alternative Permit 

After being covered by this permit, the permittee may request to be excluded from such 

coverage by applying for an individual permit. In this case, the permittee must submit an 

individual permit application in accordance with 40 CFR 122.28(b)(3)(iii), along with a 

statement of reasons supporting the request, to EPA at the applicable EPA Regional Office listed 

Formatted: Font color: Black

Deleted: Notice of termination is 

incomplete or the 

Deleted: ;

Deleted: )
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

27 

in Part 9.2 of the PGP. The request may be granted by issuance of an individual permit or 

authorization of coverage under an alternative general permit if the reasons are adequate to 

support the request. Under this scenario, if an individual permit is issued, or authorization to 

discharge under an alternative general permit is granted, coverage under this permit is 

automatically terminated under 40 CFR 122.28(b)(3)(iv) on the effective date of the individual 

permit or the date of authorization of coverage under the alternative general permit. 

Part 1.3.2 reminds permittees of their ability to apply for coverage under an individual 

permit in lieu of coverage under this general permit and describes the steps they must take to 

exclude themselves from this permit after being authorized under this permit. Cases where an 

individual NPDES permit may be required, are described fully in 122.28(b)(3)(iii). The 

following are the pertinent situations for this permit where an individual permit may be 

necessary: 

(A) A Water Quality Management plan containing requirements applicable to such point sources 

is approved; 

(B) Circumstances have changed since the time of the request to be covered so that the 

discharger is no longer appropriately controlled under the general permit, or either a 

temporary or permanent reduction or elimination of the authorized discharge is necessary; 

(C) The discharge(s) is a significant contributor of pollutants. In making this determination, EPA 

may consider the following factors: 

(1) The location of the discharge with respect to waters of the U.S.; 

(2) The size of the discharge; 

(3) The quantity and nature of the pollutants discharged to waters of the U.S.; and 

(4) Other relevant factors. 

EPA may require a permittee to apply for an individual permit only if EPA notifies the 

operator in writing that a permit application is required. This notice must include a brief 

statement of the reasons for this decision, an application form, a statement setting a time for the 

operator to file the application, and a statement that on the effective date of the individual 

NPDES permit the general permit as it applies to the individual permittee shall automatically 

terminate. EPA may grant additional time upon request of the applicant. 

When an individual NPDES permit is issued to an operator otherwise subject to a general 

NPDES permit, the applicability of the general permit to the individual NPDES permittee is 

automatically terminated on the effective date of the individual permit. 

Note that an individual permit is required for applications of pesticides to waters impaired for 

that pesticide, and for applications of pesticides to Tier 3 waters and as such, in these cases, 

authorization under this general permit would not have been available in the first place.

1.4. Severability 

 Invalidation of a portion of this permit does not necessarily render the whole permit 

invalid. EPA’s intent is that the permit remains in effect to the extent possible; in the event any 

part of this permit is invalidated, EPA will advise the regulated community as to the effect of 

such invalidation. 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

28 

1.5 Other Federal and State Laws 

Part 1.5 of this permit includes the following language: “You must comply with all other 

applicable federal and state laws and regulations that pertain to your application of pesticides. 

For example, this permit does not negate the requirements under FIFRA and its implementing 

regulations to use registered pesticides consistent with the product's labeling. Additionally, there 

are other laws and regulations that may only apply to federal agencies covered under this permit 

(e.g., U.S. Coast Guard regulations).” 

This part of the permit is intended to clarify that pesticide applicators are still required to 

comply with other applicable laws and that merely complying with the conditions of this permit 

may not meet all regulations applicable to the types of activities covered under this permit. 

1.6 Federally-Listed Endangered and Threatened Species and Designated Critical 

Habitat. 

 Part 1.6 of the draft permit includes certain requirements specific to the protection of 

federally-listed endangered and threatened species and its designated critical habitat. Procedures 

to assist in protecting listed species and critical habitat are currently being considered by EPA in 

consultation with the National Marine Fisheries Service (NMFS) and the U.S. Fish and Wildlife 

Service (FWS) under section 7 of the ESA. A more detailed discussion of permit conditions 

being considered is provided in Part III.10.F of this fact sheet. Based on consultation to date, the 

PGP includes language that would incorporate as enforceable permit conditions any pre-existing 

requirements resulting from ESA Section 7 consultation and/or an ESA Section 10 permit that is 

issued to the operator by FWS and/or NMFS. Operators seeking coverage under this permit do 

not have a separate obligation to consult with the FWS or NMFS under Section 7 of the ESA 

prior to submitting an NOI. As the Federal entity issuing this permit, EPA is the entity with an 

obligation to consult with FWS and NMFS. However, if any pre-existing consultation has been 

conducted between an operator and the Services and the results of that consultation are relevant 

to an operator's expected discharge(s), then this permit obliges the operator to comply with any 

additional conditions or limits on the discharge of pesticide residuals resulting from such 

consultation. (Such additional consultation might come up in the context of a separate Federal 

agency action, and the operator might be involved directly if, for example, it was designated as a 

non-Federal representative to conduct consultation under 50 CFR § 402.08 for a related action.) 

2. TECHNOLOGY-BASED EFFLUENT LIMITATIONS 

Background 

 The Clean Water Act (CWA) requires that all point source discharges from existing 

facilities, or in this case, pesticide applications, meet technology-based effluent limitations4

 4 Natural Res. Def. Council, Inc. v. EPA, 673 F.2d 400, 403 (D.C. Cir. 1982) (noting that "section 502(11)

defines 'effluent limitation' as ' any restriction' on the amounts of pollutants discharged, not just a numerical 

restriction"; holding that section of CWA authorizing courts of appeals to review promulgation of "any effluent 

limitation or other limitation" did not confine the court's review to the EPA's establishment of numerical limitations 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

29 

representing the applicable levels of necessary control. Additionally, water quality-based 

effluent limitations (WQBELs) are required by CWA Section 301(b)(1)(C) as necessary where 

the technology-based effluent limitations are not sufficient to protect applicable water quality 

standards. See P.U.D. No. 1 of Jefferson County et. al. v. Washington Department of Ecology, 

511 U.S. 700 (704) 1994. Water quality-based requirements will be discussed in greater depth in 

Section III.3 of the fact sheet. The technology-based effluent limitations contained in the PGP 

are non-numeric and constitute the levels of control that reduce the area and duration of impacts 

caused by the discharge of pesticides to waters of the U.S. in a treatment area. In addition, these 

effluent limitations provide for protection of water quality standards, including protection of 

beneficial uses of the receiving waters inside the treatment area following completion of pest 

management activities.

Types of Technology-Based Effluent Limitations 

Technology-based effluent limitations are in many cases established by EPA in 

regulations known as effluent limitations guidelines, or “ELGs.” EPA establishes these 

regulations for specific industry categories or subcategories after conducting an in-depth analysis 

of that industry. The Act sets forth different standards for the ELGs based upon the type of 

pollutant or the type of permittee involved. Where EPA has not issued effluent guidelines for an 

industry, EPA and State permitting authorities establish effluent limitations for NPDES permits 

on a case-by-case basis based on their best professional judgment. See 33 U.S.C. § 1342(a)(1); 

40 C.F.R. § 125.3(c)(2). 

EPA’s Authority to Include Non-Numeric Technology-Based Limitations in this Permit 

All NPDES permits are required to contain technology-based limitations. 40 CFR §§ 

122.44(a)(1) and 125.3. When EPA has not promulgated effluent limitation guidelines for an 

industry, or if an operator is discharging a pollutant not covered by the effluent guideline, permit 

limitations may be based on the best professional judgment (BPJ, sometimes also referred to as 

"best engineering judgment") of the permit writer. 33 U.S.C. § 1342(a)(1); 40 CFR 125.3(c). 

See Student Public Interest Group v. Fritzsche, Dodge & Olcott, 759 F.2d 1131, 1134 (3rd Cir. 

1985); American Petroleum Inst. v. EPA, 787 F.2d 965, 971 (5th Cir. 1986). For this permit, the 

technology-based limitations are based on BPJ decision-making because no ELG applies. 

Under EPA’s regulations, non-numeric effluent limitations are authorized in lieu of 

numeric limitations, where “[n]umeric effluent limitations are infeasible.” 40 CFR 122.44(k)(3). 

As far back as 1977, courts have recognized that there are circumstances when numeric effluent 

limitations are infeasible and have held that EPA may issue permits with conditions (e.g., best 

management practices) designed to reduce the level of effluent discharges to acceptable levels. 

Natural Res. Def. Council, Inc. v. Costle, 568 F.2d 1369 (D.C.Cir.1977). 

Through the Agency’s NPDES permit regulations, EPA interpreted the CWA to allow 

best management practices (BMPs) to take the place of numeric effluent limitations under certain 

 on pollutant discharges, but instead authorized review of other limitations under the definition) (emphasis added). 

In Natural Res. Def. Council, Inc. v. Costle, 568 F.2d 1369 (D.C. Cir. 1977), the D.C. Circuit stressed that when 

numerical effluent limitations are infeasible, EPA may issue permits with conditions designed to reduce the level of 

effluent discharges to acceptable levels. 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

30 

circumstances. Federal Regulations at 40 CFR §122.44(k), entitled “Establishing limitations, 

standards, and other permit conditions (applicable to State NPDES programs ...),” provides that 

permits may include BMPs to control or abate the discharge of pollutants when: (1) 

“[a]uthorized under section 402(p) of the CWA for the control of stormwater discharges”; or (2) 

“[n]umeric effluent limitations are infeasible.” 40 CFR § 122.44(k). 

Courts have held that the CWA does not require the EPA to set numeric limitations 

where such limits are infeasible. Citizens Coal Council v. United States Environmental 

Protection Agency, 447 F3d 879, 895-96 (6th Cir. 2006). The Sixth Circuit cited to Waterkeeper 

Alliance, Inc. v. EPA, 399 F.3d 486, 502 (2nd Cir. 2005), stating “site-specific BMPs are effluent 

limitations under the CWA.” Additionally, the Sixth Circuit cited to Natural Res. Def. Council, 

Inc. v. EPA, 673 F.2d 400, 403 (D.C.Cir.1982) noting that “section 502(11) [of the CWA] 

defines ‘effluent limitation’ as ‘any restriction’ on the amounts of pollutants discharged, not just 

a numerical restriction.” 

EPA’s Decision to Include Non-Numeric Technology-Based Effluent Limitations in This 

Permit

As described above, numeric effluent limitations are not always feasible because the 

discharges pose challenges not presented by other types of NPDES-regulated discharges. The 

technology-based effluent limitations in this permit are non-numeric based on the following 

facts: 

• The point in time for which a numeric effluent limitation would apply is not easily 

determinable. For discharges from the application of pesticides, the discharges can be 

highly intermittent with those discharges not practically separable from the pesticide 

application itself. For example, the discharge from the application of a chemical 

pesticide to a water of the U.S. is represented by the residual remaining in the ambient 

water after the pesticide is no longer serving its intended purpose (i.e., acting as a 

pesticide against targeted pests in the applied medium). Chemical pesticides applied 

directly to water are not considered pollutants until some time after actual discharge at 

which point the pesticides will have performed their intended function for pest control, 

dissipated in the waterbody, and broken down into other compounds to some extent, etc. 

This discharge also will have combined with any other discharges to that waterbody (be it 

from other point sources, non-point source runoff, air deposition, etc). Given this 

• situation, it is not clear what would be measured for a numeric limit or when.

• For discharges from the application of pesticides, there are often many short duration, 

highly variable, pesticide discharges to surface waters from many different locations for 

which it would be difficult to establish a numeric limitation at each location. This 

variability makes setting numeric effluent limitations for pesticide applications extremely 

difficult. In this situation, requiring the use of standard control practices (i.e., narrative 

non-numeric effluent limitations), provides a reasonable approach to control pesticides 

discharges. 

• The precise location for which a numeric effluent limitation would apply is not clear. 

Discharges from the application of pesticide are different from discharges of process 

Formatted: Indent: Before: 0.25"

Deleted: the vast majority of 

Deleted: EPA does not consider

Deleted: to be a reasonable measure 

upon which to assess compliance with 

effluent limitations. ¶

Deleted: addition, although the 

limitations may be similar across use 

patterns, the same set of control measures 

or BMPs may not be appropriate for all 

the different types of pesticide 

applications covered by 

Deleted: permit. The record for this 

permit indicates that there is a high level 

of variability among discharges, in terms 

of how pesticides are applied due to the 

dissimilarity of locations where those 

pesticides are applied, the types of pests 

to control, the density of the pests, the 

types of pesticides used, and the type of 

residuals generated from the discharge of 

these pesticides to waters of the U.S. 

However

Deleted: available

Deleted: is in contrast to 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

31 

wastewater from a particular industrial or commercial facility where the effluent is more 

predictable and easily identified as an effluent from a conveyance (e.g., pipe or ditch),

can be precisely measured for compliance prior to discharge, and can be more effectively 

analyzed to develop numeric effluent limitations. 

• Information needed to develop numeric effluent limitations is not available at this time. 

To develop numeric technology-based effluent limitations, EPA must fully evaluate 

factors outlined in 40 CFR 125.3, such as the age of equipment and facilities involved, 

the process employed, the potential process changes, and non-water quality 

environmental impacts. In addition, EPA estimates that more than 400 pesticide active 

ingredients contained in over 3,500 pesticide products may be covered under this permit. 

Technology-based effluent limitations in this permit are presented specific to each 

pesticide use pattern to reflect the variations in procedures and expectations for the use and 

application of pesticides. These non-numeric effluent limitations are expected to minimize 

environmental impacts by reducing the discharge of pesticides to waters of the U.S., thereby 

protecting the receiving waters, including meeting of all applicable water quality standards. 

The effluent limitations in this permit are expressed as specific pollution prevention 

requirements for minimizing the pollutant levels in the discharge. EPA has determined that the 

combination of pollution prevention approaches and structural management practices required by 

these limits are the most environmentally sound way to control the discharge of pesticide 

pollutants to meet the effluent limitations. Pollution prevention continues to be the cornerstone 

of the NPDES program. 

EPA continues to study the efficacy of various types of pollution prevention measures 

and BMPs; however, for this permit numeric limitations are not feasible. 

Control Measures Used to Meet the Technology-Based Effluent Limitations 

Just as there is variability in the pesticide applications as described above, there is 

variability in the control measures that can be used to meet the effluent limitations. Therefore, 

EPA is not mandating the specific control measures operators must implement to meet the 

limitations. This is analogous to an industrial situation where discharges to waters of the U.S. 

are via pipes and a numeric effluent limitation may be specified as a given quantity of pollutant 

that may be discharged, but EPA would not specify what technology should be employed to meet 

that limitation. For pesticides, namely mosquitocides, for example, Part 2.2.1.2 of the PGP 

requires mosquito control operators to consider mechanical/physical methods of control to 

eliminate or reduce mosquito habitat. How this is achieved will vary by operator: For some, this 

many be achieved through regular mowing while for others mowing will not be feasible. Thus, a 

given control measure may be acceptable and appropriate in some circumstances but not in 

others. In this respect, the non-numeric effluent limitations in this permit are similar to numeric 

effluent limitations, which also do not require specific control technologies as long as the 

limitations are met. 

Control measures can be actions (including processes, procedures, schedules of activities, 

prohibitions on practices and other management practices), or structural or installed devices to 

prevent or reduce water pollution. The key is determining what measure is appropriate for your 

Deleted: discharges

Deleted: , 

Deleted: ) and

Deleted: Even if EPA could somehow 

establish technology-based numeric 

effluent limitations, EPA believes it 

would be infeasible to do so in the 

amount of time given for the Agency to 

develop and issue this permit. 

Deleted: For example, in 

Deleted: , 

Deleted: this
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

32 

situation in order to meet the effluent limitation. In this permit, operators are required to 

implement site-specific control measures to meet these limitations. The permit along with this 

fact sheet provides examples of control measures, but operators must tailor these to their 

situations as well as improve upon them as necessary to meet permit limits. The examples 

emphasize minimization over treatment. 

EPA notes that this permit uses both the term “control measures” and “best management 

practices” or “BMPs”. Use of the term control measure is intended to better describe the range 

of pollutant reduction practices that may be employed, whether they are structural, non-structural 

or procedural and includes BMPs as one of the components. The greater breadth of meaning for 

control measures vis-à-vis BMPs is why EPA uses this term in many parts of the permit. 

The approach to control measures in this permit is consistent with the CWA as well as its 

implementing regulations at 40 CFR 122.44(k)(4). Section 402(a)(2) of the CWA states: “The 

administrator shall prescribe conditions for such permits to assure compliance with the 

requirements in paragraph (1) . . . including conditions on data and information collection, 

reporting and such other requirements as he deems appropriate." (Section 402(a)(1) includes 

effluent limitation requirements.) This statutory provision is reflected in the CWA implementing 

regulations, which state that control measures can be included in permits when, “[t]he practices 

are reasonably necessary to achieve effluent limitations and standards or to carry out the 

purposes and intent of the CWA.” 40 CFR 122.44(k)(4). 

Implementation of Control Measures 

Part 2.0 of this permit requires operators to implement control measures to meet the 

technology-based effluent limitations listed in that Part. It also provides operators with 

important considerations for the implementation of their specific control measures. Some 

operators will have to document how such factors were taken into account in the implementation 

of their control measures (See Part 5). EPA recognizes that not all of these considerations will 

be applicable to every site nor will they always affect the choice of control measures. If 

operators find their control measures are not minimizing discharges of pesticide adequately, the 

control measures must be modified as expeditiously as practicable. See Part 6, Corrective 

Action. 

Control Measures and Technology-Based Effluent Limitations – Definition of “Minimize” 

The non-numeric effluent limitations require operators to “minimize” discharges of 

pesticide. Consistent with the control level requirements of the CWA, the term “minimize” 

means to reduce and/or eliminate pesticide discharges to waters of the U.S. through the use of 

control measures to the extent technologically available and economically achievable and 

practicable. 

EPA believes that for many pesticide applications minimization of the discharge of 

pesticides to waters of the U.S. can be achieved without using highly engineered, complex 

treatment systems. The specific limits included in Part 2.0 emphasize effective “low-tech” 

approaches, including using the lowest effective amount of pesticide product, performing regular 

equipment maintenance and calibration, accurately identifying the pest problem, efficiently and 

effectively managing the pest problem, and properly using pesticides. 

Deleted: and 

Deleted: controls to use 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

33 

Statutes, Regulations, and Other Requirements 

Operators must comply with all applicable statutes, regulations and other requirements 

including, but not limited to requirements contained in the labeling of pesticide products 

approved under FIFRA (“FIFRA labeling”). Although the FIFRA label and labeling 

requirements are not effluent limitations, it is illegal to use a registered pesticide inconsistent 

with its labeling. If operators are found to have applied a pesticide in a manner inconsistent with 

any relevant water-quality related FIFRA labeling requirements, EPA will presume that the 

effluent limitation to minimize pesticides entering the waters of the U.S. has been violated under 

the NPDES permit. EPA considers many provisions of FIFRA labeling -- such as those relating 

to application sites, rates, frequency, and methods, as well as provisions concerning proper 

storage and disposal of pesticide wastes and containers -- to be requirements that affect water 

quality. For example, an operator, who is a pesticide applicator, decides to use a mosquito 

adulticide pesticide product with a FIFRA label that contains the following language, "Apply this 

product at a rate not to exceed one pound per acre." The applicator applies this product at higher 

than the allowable rate, which results in excess product being discharged into waters of the U.S. 

EPA would find that this application was a misuse of the pesticide under the FIFRA label and 

because of the misuse; the Agency would determine that the effluent limitation that requires the 

operator to minimize discharges of pesticide products to waters of the U.S. was also violated. 

Therefore, pesticide use inconsistent with certain FIFRA labeling requirements could result in 

the operator being held liable for a CWA violation as well as a FIFRA violation.

Technology-Based Effluent Limitations in the PGP 

The permit requires the operator to achieve all of the non-numeric effluent limitations 

delineated in Parts 2.1 and 2.2 as described below. 

All operators under Part 2.1 must “minimize” pesticide applications. Under Part 2.2, 

only those operations required to submit an NOI (i.e., applying pesticides above the annual 

treatment area threshold) are required to implement IPM and other permit conditions. EPA is not 

requiring these additional technology-based effluent limitation requirements from permittees 

who treat areas below the annual treatment area thresholds at this time, because of concerns 

about potential unintended consequences of such a requirement. 

2.1 General Effluent Limitations

Part 2.1 of this permit contains the general effluent limitations that apply to all operators, 

regardless of use pattern. These effluent limitations are generally preventative in nature, and are 

designed to minimize pesticide discharges into waters of the U.S. All operators, regardless of 

whether you are required to submit an NOI, are required to minimize the discharge of pesticides 

to waters of the U.S. by doing the following:
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

34 

2.1.1 Use the lowest effective amount of pesticide product per application and optimum 

frequency of pesticide applications necessary to control the target pest, consistent with 

reducing the potential for development of pest resistance. 

As noted earlier, it is illegal to use a pesticide in any way prohibited by the FIFRA 

labeling. Also, use of pesticides must be consistent with any other applicable state or federal 

laws. To minimize the total amount of pesticide discharged, operators must consider lower 

application rates, frequencies, or both to accomplish effective control keeping in mind pesticide 

resistance. Using the lowest possible effective rate ensures maximum efficiency in pest control 

with the minimum quantity of pesticide. The lowest effective application rate also reduces the 

amount of pesticide available that is not performing a specific pest-control function. Using the 

lowest possible effective rate and frequency of applications can result in cost and time savings to 

the user. To minimize discharges of pesticide, operators should base the rate and frequency of 

application on what is known to be effective against the target pest or necessary for resistance 

management. 

Operators must also consider pest resistance to pesticides when reducing discharges from 

application of pesticide. Resistance management is an important part of pest control. Some 

pests can develop resistance to pesticides unless resistance management techniques are adopted 

by pesticide users. Resistance can result in the loss of effectiveness of pesticides with relatively 

favorable environmental and human health risks and increase reliance on riskier pesticides. 

When resistance occurs, users may increase rates and frequency of application in an attempt to 

maintain pesticide effectiveness. This can lead to the loss of efficacy and increased exposure to 

the pesticide. Pesticide applicators should be aware of the potential for pest resistance to develop 

by considering the pest, the pesticide and its mode of action, the number of applications and 

intervals, and application rates. 

Pest resistance develops because intensive pesticide use kills the susceptible individuals 

in a population, leaving only the resistant ones to reproduce. Several pest management tactics 

help prevent or delay the occurrence of pesticide resistance. One tactic is to reduce dosages in 

order to avoid establishing a population of resistant organisms and instead allowing some

survivors to pass on genes for susceptibility. Another is to apply pesticides over limited areas to 

reduce the proportion of the total pest population exposed to the pesticide, thereby maintaining a 

large pool of individuals still susceptible to the pesticide. A third tactic to prevent development 

of resistant pest populations is to rotate pesticides with different modes of actions against the 

pests rather than depend on a single mode of action. See National Pesticide Applicator 

Certification Core Manual, Chapter 1 – Pest Management for additional information on pesticide 

resistance. 

2.1.2 Perform regular maintenance activities to minimize potential for leaks, spills, or 

other unintended discharges of pesticides associated with the application of pesticides 

covered under this permit. 

Common-sense and good housekeeping practices enable pesticide users to save time and 

money and reduce potential for unintended discharges of pesticides to waters of the U.S. 

Regular maintenance activities should be practiced and improper pesticide mixing and 

equipment loading should be avoided. When preparing the pesticides for application be certain 

that you are mixing them correctly and preparing only the amount of material that you need. 

Deleted: applied 

Deleted: consider the following factors: ¶

¶

Base

Deleted: as 

Deleted: ; and

Deleted: <#>The frequency of 

applications should be based on target 

pest action thresholds to provide most 

effective and economical control and to 

prevent unnecessary impact on non-target 

pests.¶

Deleted: so fewer pests are killed thus 

decrease the development

Deleted: pest population

Deleted: from pesticide 

Deleted: .

Deleted: to minimize this potential that 

can be caused by 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

35 

Carefully choose the pesticide mixing and loading area and avoid places where a spill will 

discharge into waters of the U.S. Some basic factors operators should consider are: 

• Inspect pesticide containers at purchase to ensure proper containment; 

• Maintain clean storage facilities for pesticides; 

• Regularly monitor containers for leaks; 

• Rotate pesticide supplies to prevent leaks that may result from long term storage; 

and 

• Promptly deal with spills following manufacturer recommendations. 

2.1.3. Maintain application equipment in proper operating condition by adhering to any 

manufacturer’s conditions and industry practices, and by calibrating, cleaning, and 

repairing such equipment on a regular basis to ensure effective pesticide application and 

pest control. You must ensure that the equipment’s rate of pesticide application is 

calibrated to deliver the precise quantity of pesticide needed to achieve greatest efficacy 

against the target pest. 

 To minimize discharges of pesticide, operators must ensure that the rate of application is 

calibrated (i.e. nozzle choice, droplet size, etc.) to deliver the appropriate quantity of pesticide 

needed to achieve greatest efficacy against the target pest. Improperly calibrated pesticide 

equipment may cause either too little or too much pesticide to be applied. This lack of precision 

can result in excess pesticide being available or result in ineffective pest control. When done 

properly, equipment calibration can assure uniform application to the desired target and result in 

higher efficiency in terms of pest control and cost. It is important for applicators to know that 

pesticide application efficiency and precision can be adversely affected by a variety of 

mechanical problems that can be addressed through regular calibration. Sound calibration 

practices to consider are:

• Choosing the right spray equipment for the application 

• Ensuring proper regulation of pressure and choice of nozzle to ensure desired 

application rate 

• Calibrating spray equipment prior to use to ensure the rate applied is that required 

for effective control of the target pest 

• Cleaning all equipment after each use and/or prior to using another pesticide 

unless a tank mix is the desired objective and cross contamination is not an issue

• Checking all equipment regularly (e.g., sprayers, hoses, nozzles, etc.) for signs of 

uneven wear (e.g., metal fatigue/shavings, cracked hoses, etc.) to prevent 

equipment failure that may result in inadvertent discharge into the environment 

• Replacing all worn components of pesticide application equipment prior to 

application. 

2.2. Integrated Pest Management Practices 

As noted above, NPDES permits must contain technology-based effluent limitations. In 

addition to the technology-based effluent limitations described immediately above that apply to 

all permittees, EPA is requiring certain permittees to also comply with additional technologybased effluent limitation because we have found that IPM is economically achievable for these 

large applications. Permittees subject to these additional limits are those permittees who exceed 

Deleted: , 

Deleted: minimum 

Deleted: use to avoid

Deleted: with other pesticides where 

tank mixes are

Deleted: used in pest control 

Deleted: limitations
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

36 

the annual treatment area thresholds described in section 1.2.2.1 of the permit. These entities are 

those who manage large treatment areas as explained in Part III, section 1.2.1. EPA expects that 

many of these permittees are already performing some of the IPM practices required in these 

additional technology-based effluent limitations. EPA is not requiring these additional 

technology-based effluent limitation requirements from permittees who treat areas below the 

threshold at this time because we are still unclear whether it is economically achievable for small 

applications to implement IPM and because of concerns about potential unintended 

consequences of such a requirement, such as an inability to conduct essential public health and 

safety operations due to a reduction of available funds or manpower. Additionally, operators 

whose discharges of pesticides to waters of the U.S. are solely from pesticide research and 

development activities do not have to comply with these additional technology-based effluent 

limitations to the extent the limits may compromise the research design. EPA is soliciting 

comment on the applicability of these additional technology-based effluent limitations for all or 

some of the applicators that fall below the thresholds (e.g., states, governmental agencies, small 

public entities, and private entities). EPA is also soliciting comment about the impacts such a 

requirement would have on those entities 

The additional technology-based effluent limitations in Part 2.2 are based on integrated 

pest management (IPM) practices. IPM, as defined in FIFRA, is a sustainable approach to 

managing pests by combining biological, cultural, physical, and chemical tools in a way that 

minimizes economic, health, and environmental risks. (FIFRA, 7 U.S.C. 136r-1) IPM is not a 

single pest control method but, rather, a series of pest management evaluations, decisions and 

controls. In evaluating available and relevant information, EPA found that some commercial 

(for-hired applicators) and non-commercial (e.g., state governments, federal governments, local 

governments, utilities) entities are currently implementing IPM practices or components of IPM 

to minimize pesticide use. For example, federal agencies are required to implement IPM under 7 

USC 136r-1, “Federal agencies shall use Integrated Pest Management techniques in carrying out 

pest management through procurement and regulatory policies, and other activities.” EPA has 

found that mosquito control operations are performed by local government entities and that they 

are generally performing IPM. 

EPA believes requiring IPM practices in this permit will reduce discharges of pesticide to 

waters of the U.S. For example, the Metropolitan Water District of Southern California 

(MWDSC) at Lake Matthews managed the underlying causes of recurring taste and odor 

problems in the reservoir using IPM. Between 1982 and 1991, the MWDSC was inefficiently 

escalating the amounts of copper sulfate applied to treat an algae problem, to the point where it 

was releasing hundreds of tons of the chemical via helicopter each year, increasing the risk of 

using lake water due to the toxins produced by the dying algae. Introducing the concept of sector 

monitoring and at-need copper sulfate application allowed for more controlled released of algaerelated toxins and avoided overuse of pesticides. After several years of this type of treatment, 

the benthic algal population diversified and the algal population was manageable such that in 

some years, pesticides are no longer used.5 

 5

 Taylor, W., R. Losee, M. Torobin, G. Izaguirre, D. Sass, D. Khiari, and K. Atasi. 2006. Early Warning 

and Management of Surface Water Taste-and-Odor Events. AwwaRF Report 91102F. AWWA Research 

Foundation, American Water Works Association, and IWA Publishing. 

Deleted: requirements of the 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

37 

 Part 2.2 of this permit requires operators above the annual treatment area threshold to 

identify the pest problem; to evaluate and implement efficiently and effectively pest 

management; and to properly use pesticides. Operators are required to perform each of these 

permit conditions prior to the first pesticide application covered under this permit and at least 

once each calendar year thereafter. Below is a general discussion describing the limitations for 

all use patterns. Following the general discussion are more detailed descriptions of each specific 

requirement under each use pattern. Requirements for documentation of the specific measures 

implemented are contained in Part 7, Recordkeeping and Annual Reporting. 

 Operators required to perform IPM practices will be required to do the following 

regardless of use pattern: 

Identify the Problem 

 Operators are required to identify the pest problem, identify the target pest, and establish 

an action threshold. Understanding the pest biology and ecology will provide insight into 

selecting the most effective and efficient pest management strategies (pesticidal or non-pesticidal 

methods), and in developing an action threshold. An action threshold is a point at which pest 

populations or environmental conditions indicate that pest control action must be taken. Action 

thresholds help determine both the need for control actions and the proper timing of such actions. 

It is a predetermined pest level that is deemed to be unacceptable. In some situations, the action 

threshold for a pest may be zero (i.e., no presence of the pest is tolerated). This is especially true 

when the pest is capable of transmitting a human pathogen (e.g., mosquitoes and the West Nile 

virus). In areas where aquatic weeds are problematic, it may be preferable to use an aquatic 

herbicide as a preventive measure rather than after weeds become established. In some 

situations, even a slight amount of pest damage may be unacceptable for ecological or aesthetic 

reasons. Sometime pre-emergent pesticide application is needed, as preventive measure to keep 

aquatic weeds at bay. Action thresholds can vary by pest, by site, and by season. Often the 

action threshold is expressed as the number of pests per unit area. Action thresholds may be 

difficult to establish. In a new IPM program, a practical approach is to establish an action 

threshold for the major pests. As operators gain insight and experience into specific pest 

management settings, the action levels can be revised up or down. 

 To identify the problem at a treatment area, operators may use existing data to meet the 

conditions of the permit. For example, a mosquito district may use surveillance data from an 

adjacent district to identify mosquito species at their pest management area. Operators may also 

use relevant historic site data. 

Pest Management 

Operators are required to implement efficient and effective means of pest management 

that most successfully minimizes discharges to waters of the U.S. resulting from the application 

of pesticides. Operators must evaluate both pesticide and non-pesticide methods. Operators 

must consider and evaluate the following options: no action, prevention, mechanical/physical 

methods, cultural methods, biological control agents, and pesticides. In the evaluation of these 

options, operators must consider impacts to water quality, impacts to non-target organisms, pest 

resistance, feasibility, and cost effectiveness. Combinations of various management methods are 

frequently the most effective pest management strategies over the long term. The goal should be 

Deleted: Documentation

Deleted: is

Deleted: , 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

38 

to emphasize long-term control rather than a temporary fix. For additional information, see 

discussion under each use pattern. 

Pesticide Use 

 Operators are required to conduct pest surveillance and reduce the impact on the 

environment. Pest surveillance is important to properly time the need for pest control. To 

reduce the impact on the environment and non-target organisms, operators are required to apply 

pesticide when the action threshold has been met. As noted earlier, action thresholds help 

determine both the need for control actions and the proper timing of such actions. There are 

additional requirements designed for each use pattern in Sections 2.2.1 through 2.2.4 of the 

permit. For additional information and other limits on pesticide use, see specific discussion 

under each use pattern. 

2.2.1 Mosquito and Other Flying Insect Pests Control

a. Mosquitoes 

Background 

There are over 2500 different species of mosquitoes throughout the world with 

approximately 200 species occurring in the U.S. The total budgets for mosquito control in the 

U.S. exceed $200,000,000 annually (AMCA 2009). Mosquitoes can be a source of annoyance 

(e.g., work and leisure activities), a limiting factor in economic development (e.g., residential 

development and property value), a causal factor in decreased agricultural productivity (e.g., 

animal weight loss/death and decreased milk production) from irritation and blood loss, and a 

source of disease transmission (e.g., malaria, encephalitis, yellow fever, dengue, and West Nile 

Virus). Most of these diseases have been prominent as endemic or epidemic diseases in the U.S. 

in the past, although today, only the insect-borne (arboviral) encephalitides and West Nile virus 

fever occur annually and dengue occurs periodically in this country. Thus, control of mosquitoes 

is an important public health issue. Numerous strategies are used to reduce the impact of 

mosquitoes but a comprehensive approach using a variety of complementary control methods is 

necessary for any mosquito control program. 

Of major concern is the transmission of microorganisms that cause diseases such as 

western equine encephalitis and St. Louis encephalitis. Both of these diseases can cause serious, 

sometimes fatal neurological ailments in people. (Western equine encephalitis virus also causes 

disease in horses.) Western equine encephalitis infections tend to be more serious in infants 

while St. Louis encephalitis can be a problem for older people. These viruses normally infect 

birds or small mammals. During such infections, the level of the virus may increase in these 

infected animals facilitating transmission to humans by mosquitoes. The West Nile virus, which 

can also cause encephalitis, was found in the northeastern U.S. for the first time in 1999, and is a 

good example of this mode of transmission. Over 20,000 human cases of West Nile virus have 

been reported in the U.S. Symptoms of human illness can range from mild flu-like symptoms to 

severe encephalitis, meningitis, or acute flaccid paralysis. Over 800 people have died from West 

Nile virus since its emergence in North America in 1999 (CDC). 

Deleted: under

Deleted: Pesticide Use Part

Deleted: under

Deleted: Also of

Deleted: are 

Deleted: ions of
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

39 

Other pathogens transmitted by mosquitoes include a protozoan parasite which causes 

malaria, and Dirofilaria immitis, a parasitic roundworm and the causative agent of dog 

heartworm. Disease carrying mosquito species are found throughout the U.S., especially in 

urban areas and coastal or inland areas where flooding of low lands frequently occurs. Even 

when no infectious diseases are transmitted by mosquitoes, they can be a health problem to 

people and livestock. Mosquito bites can result in secondary infections, allergic reactions, pain, 

irritation, redness, and itching. 

Mosquito Control IPM Practices

Identify the Problem 

Part 2.2.1.1: Prior to the first pesticide application covered under this permit 

that will result in a discharge to waters of the U.S., and at least once each calendar year 

thereafter prior to the first pesticide application for that calendar year, you must do the 

following for each pest management area, as defined in Appendix A. Operators must 

identify the pest problem in their pest management area prior to the first application covered 

under this permit. Knowledge of the pest problem is an important step to developing pest 

management strategies. Re-evaluation of the pest problem is also important to ensure pest 

management strategies are still applicable. Operators must identify the pest problem at least 

once each calendar year prior to the first application for that calendar year. 

 

Establish densities for larval and adult mosquito or flying insect pest populations to 

serve as action threshold(s) for implementing pest management strategies. Operators must 

develop action thresholds for larval and adult mosquito prior to the first pesticide application 

covered under this permit. The action thresholds must be re-evaluated at least once each 

calendar year. As noted in the general discussion above, an action threshold is a point at which 

pest populations or environmental conditions indicate that pest control action must be taken. 

Action thresholds help determine both the need for control actions and the proper timing of such 

actions. It is a predetermined pest level that is deemed to be unacceptable. For example in 

Maryland, “A collection of more than 10 anthropophagous (human biting) female mosquitoes 

per night of trap operation is considered to be the level which causes discomfort and/or 

complaints from the majority of people. The light trap action threshold for ground spraying of 

adult mosquitoes is 10-20 per trap-night. The action threshold to suppress pest populations of 

adult mosquitoes by aerial spraying (application of insecticide by an aircraft) is a light trap 

collection of 100 female mosquitoes. The action threshold for landing rate counts to justify 

ground spraying for the control of adult mosquitoes is 1 to 3 in 1 minute. The action threshold 

for aerial spraying is 12 mosquitoes per minute.”6

 For larvae control, action thresholds are 

determined by standard mosquito dipping techniques. For example, in Canyon County Mosquito 

Abatement District, Idaho7

, they established larvae density action levels for Culex species 

(primary disease vectors) as Low: 1-5 larvae per dip; Medium: 6-10 larvae per dip; High: > than 

10 larvae per dip. The larvae density action threshold can be used to determine how much larval 

control products are to be used or even if any action is to be taken. In some situations, the action 

threshold for a pest may be zero (i.e., no presence of the pest is tolerated). This is especially true 

 6 http://www.mda.state.md.us/plants-pests/mosquito_control/mosquito_control_program_description.php

7 http://www.canyoncountymosquito.com/CCMADMosquitoPesticideUsePlan.pdf

Deleted: in 

Deleted: level
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

40 

when the pest is capable of transmitting a human pathogen (e.g., mosquitoes and the West Nile 

virus).

Identify the target mosquito or flying insect pest species to develop a species-specific 

pest management strategy based on developmental and behavioral considerations for each 

species. Knowledge of the developmental biology of mosquitoes is essential to developing pest 

management strategies for mosquito control. The mosquito undergoes complete metamorphosis 

and has four distinct stages in its life cycle: egg, larva, pupa, and adult. Depending on the 

species, eggs are deposited either in permanent water habitats or in temporary/floodwater 

habitats. Egg deposition in permanent water habitats occurs as individual eggs or as multiple egg 

rafts deposited directly to the water surface in natural or artificial water-holding containers found 

in the domestic environment or in naturally occurring pools. Egg rafts may contain 100-200 

eggs. A batch laid of single eggs may range from 60-100 eggs. Egg deposition in 

temporary/floodwater habitats occurs as individual eggs on moist soil (e.g., roadside ditches, 

depressions, farmland irrigation ditches, etc.) or in other objects (e.g., flower pots, cans, tires, 

tree holes, etc.) in which periodic flooding will occur. Eggs deposited in permanent habitats will 

hatch in a few days whereas eggs deposited in temporary/floodwater habitats are resistant to 

desiccation in the absence of flooding and can withstand drying for extended periods of time 

(weeks to months) before hatching. 

Following egg hatching, typically 2-3 days after laying, mosquitoes go through four 

larval developmental stages (instars) commonly known as wrigglers. Larval development 

generally is completed in a week or less, depending upon the species and environmental 

conditions (e.g., crowding, food availability, and water temperature). The first three larval 

instars continually feed on detritus, algae, bacteria, and fungi. However, some mosquito species 

are predacious with larva feeding on other mosquitoes and/or small aquatic invertebrates. Late 

in the fourth larval instar the larvae ceases to feed in preparation for pupation. The pupal stage, 

commonly referred to as a tumbler, is a non-feeding developmental stage in which the adult form 

is developed. Following a few hours to several days, dependent upon species and water 

temperature, the adult emerges from the pupae. 

The adult mosquito is the pestiferous stage. Adults emerge from the water surface and 

after a short period of rest seek out a food source. Both males and females feed on nectar of 

flowers and other sugar sources as a source of energy. Only female mosquitoes seek out a blood 

meal as a source of protein and lipids for egg development. However, females of some species 

are autogenous (i.e., able to use energy reserves carried over from the immature stage to develop 

the first egg batch). In addition, most mosquitoes have preferred hosts which may include warm 

and cold blooded animals and birds. Human blood meals are seldom first or second choices with 

livestock, smaller mammals and/or birds generally preferred. Host seeking and blood feeding 

activities by mosquitoes are initiated by a complex variety of host and environmental cues (e.g., 

carbon dioxide, temperature, moisture, smell, color, movement and host preference). Adult 

feeding activity is generally either crepuscular (early morning, dusk and into the evening) or 

diurnal (daytime, particularly in relation to cloudy days and shaded areas). Although highly 

variable by species and environmental conditions, a complete development cycle can occur every 

one to three weeks. An understanding of the developmental biology of species in a given area 

provides the basis for developing a pest management strategy aimed at reducing pesticide 

discharge into waters of the U.S. 

Deleted: exist
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

41 

Prior to the first pesticide application covered under this permit, operators must ensure 

proper identification of mosquito species to better understand the biology of the target species 

and develop a detailed pest management strategy. Due to the great variability in developmental 

habitats and adult feeding behaviors as discussed previously, proper identification is imperative 

in designing an effective and efficient pest management strategy. Identification of the target 

species will aid in development of strategies aimed at both the immature and adult 

developmental stages. Identification of the target species for a specific area allows 1) 

identification of potential breeding sites, 2) evaluation of alternative control measures aimed at 

controlling the immature stages (habitat modification, source reduction, larvicides, biological 

larvicides, and oils), and 3) assessment of potential for disease transmission. 

 

Identify known breeding sites for source reduction, larval control program, and 

habitat management. Once species have been identified, mapping is a valuable tool in assessing 

mosquito habitats and designing control programs for a specific area to minimize pesticide 

discharge into waters of the U.S. Maps may simply be township/city/county maps but may also 

include aerial photo assessments, topographic maps, and satellite imagery where available. 

Mapping is essential to identify mosquito producing areas which can and cannot be controlled 

using non-chemical preventative measures (e.g., source reduction). Maps should include all 

potential sites for mosquito development including agricultural areas in the specific area (e.g., 

hay, pasture, circle irrigation, orchards, rill irrigated field crops, and flood irrigated pastures and 

farmland). Mapping should also be a priority in a surveillance program utilizing mosquito traps, 

biting counts, complaints, and reports from the public. Planning in coordination with mapping 

ensures the best pest management strategy (whether source reduction, biological, or chemical) 

for each particular species is chosen. Operators must identify known breeding sites prior to the 

first pesticide application covered under this permit. 

Analyze existing surveillance data to identify new or unidentified sources of 

mosquito or flying insect pest problems as well as sites that have recurring pest problems. 

As discussed above, mapping is a valuable tool in assessing mosquito habitats and designing 

control programs. Operators must analyze existing surveillance data to identity any new source 

of mosquito problems. 

In the event there are no data for your pest management area in the past calendar 

year, see Part 5 for documentation requirements regarding why current data are not 

available and the data you used to meet the permit conditions in Part 2.2.1.1. Operators 

may use historical data or neighboring district data to identify the species and establish action 

thresholds. 

Pest Management 

Part 2.2.1.2: Prior to the first pesticide application covered under this permit that 

will result in a discharge to waters of the U.S., and at least once each calendar year 

thereafter prior to the first pesticide application for that calendar year, you must select and 

implement, for each pest management area, efficient and effective means of pest 

management that minimize discharges resulting from application of pesticides to control 

mosquitoes or other flying insect pests. In developing these pest management strategies, 

you must evaluate the following management options, considering impact to water quality, 

impact to non-target organisms, pest resistance, feasibility, and cost effectiveness: No 

Deleted: Parts 

Deleted: and 7 

Deleted: any

Deleted: or record keeping

Deleted: of

Deleted: ;
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

42 

action; Prevention; Mechanical/physical methods; Cultural methods; Biological control 

agents; and Pesticides. 

 Operators are required to evaluate and implement a pest management strategy to 

minimize pesticide discharge into waters of the U.S. prior to the first pesticide application 

covered under this permit. Pest management strategies will vary by locality, mosquito species, 

and financial concerns. As noted above, combinations of various management methods are 

frequently the most effective pest management strategies over the long term. The goal should be 

to emphasize long-term control rather than a temporary fix. Operators must reevaluate every 

year prior to the first pesticide application for that calendar year. The following describes the 

management options that must be evaluated. 

No Action. No action is to be taken, although a mosquito problem has been identified. This 

may be appropriate in cases where, for example, available control methods may cause secondary 

or non-target impacts that are not justified or no control methods exist. 

Prevention. Prevention strategies are program activities which eliminate developing mosquito 

populations through environmental modification and/or habitat management. For mosquito 

control, these activities are physical methods such as habitat modification, cultural methods that 

reduce sources of mosquitoes, and biological control. 

Mechanical/Physical Methods. Habitat modification, also known as physical or permanent 

control, is in many cases the most effective mosquito control technique available and is 

accomplished by eliminating mosquito breeding sites. Habitat modification activities have the 

potential to be both effective and economical in some areas and can virtually eliminate the need 

for pesticide use in and adjacent to the affected habitat. However, the ability to use prevention 

strategies is dependent upon local authority and restrictions. 

Cultural Methods. Cultural methods can reduce sources of mosquitoes and can be as simple as 

properly discarding old containers that hold water capable of producing Aedes aegypti, Ae. 

albopictus or Culex spp. or as complex as implementing Rotational Impoundment Management 

(RIM) or Open Marsh Water Management (OMWM) techniques. RIM is a source reduction 

strategy that controls salt marsh mosquitoes (e.g., Ae. taeniorhynchus and Ae. sollicitans) at the 

same time as significant habitat restoration is occurring. Source reduction may include; water 

management, vegetation management, biological control, and pesticide use in non-waters of the 

U.S. 

Containers provide excellent habitats for development of numerous mosquito species. 

These may include but are not limited to flowerpots, cans, and tires. Container-inhabiting 

mosquitoes of particular concern include, Ae. aeypti, Ae. albopictus, Cx. p. pipiens, and Cx. 

salinarious. A container-breeding mosquito problem can be solved by properly disposing of 

such materials, covering them, tipping them over to ensure that they do not collect water, and/or 

periodic draining. Urban container-breeding mosquito control is best implemented through 

education and surveillance programs. 

Source reduction in freshwater lakes, ponds, and retention areas is more applicable to 

artificially created areas than natural areas. Artificial ponds can be eliminated as a breeding site 

simply by filling in the areas, (i.e. habitat modification). However, large permanent water bodies 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

43 

and areas for stormwater or wastewater retention require other methods. Options for these areas 

include minimizing and/or eliminating emergent and standing vegetation, maintenance of steep 

banks, and inclusion of deep water areas as sanctuary for larvivorous fish. 

Mosquito production from stormwater/wastewater habitats can result in considerable 

mosquito problems as a result of engineering, poor construction or improper maintenance. 

However, mosquito populations can typically be managed by keeping such areas free of weeds 

through an aquatic plant management program and maintaining water quality that can support 

larvivorous fish. Culex, Coquillettidia, Mansonia, and Anopheles mosquitoes are often produced 

in these habitats. 

Pastures and agricultural lands are enormous mosquito producers, frequently generating 

huge broods of Aedes, Psorophora, and Culex mosquitoes. Improved drainage is one effective 

tool for source reduction in such habitats. The second is the use of efficient, precision irrigation 

practices that will result in less standing water for those agricultural areas that require artificial 

watering. 

In coastal areas with extensive coastal salt marshes, there can be tremendous production 

of Aedes mosquitoes, making coastal human habitation virtually impossible. Several source 

reduction efforts can greatly reduce salt-marsh mosquito production through high-to midintensity management that relies upon artificial manipulation of the frequency and duration of 

inundation. 

Biological Control. The use of biological organisms or their byproducts to combat pest insects, 

such as mosquitoes, is termed biological control, or biocontrol. Biocontrol is utilization of 

parasites, predators, and pathogens to regulate pest populations. Generally, this definition 

includes natural and genetically modified organisms and means that the agent must be alive and 

able to attack the mosquito. The overall premise is simple: Biocontrol agents that attack 

mosquitoes naturally are grown in the lab and then released into the environment, usually in far 

greater numbers than they normally occur, and often in habitats that previously were devoid of 

them, so as to control targeted mosquito species. 

One advantage of biocontrol agents is host-specificity which affords minimal disturbance 

to non-target species and to the environment. However, it is this specificity and the cost of 

commercializing biocontrol agents that deter development of biocontrol agents. In addition, 

utilization of biocontrol requires increased capital outlay and start up costs as well as increased 

training requirements for personnel. 

Biocontrol should be considered a set of tools that a mosquito control program can use 

when it is economically feasible. When combined with conventional chemicals and physical 

control procedures, biocontrol agents can provide short and, occasionally, long-term control. 

Biocontrol, as a conventional control method, should aim at the weakest link of the life cycle of 

the mosquito. In most cases, this is the larval life stage. 

Mosquitofish (Gambusia affinis) are currently the most extensively used biocontrol 

agent. These fish, which feed on mosquito larvae, can be placed in a variety of permanent and 

semi-permanent water habitats. Differences of opinion exist on the utility and actual control 

benefits derived from Gambusia implementation in an Integrated Pest Management (IPM) 

Deleted: when done without sound 

Deleted: in these marshes 

Deleted: Mosquito fish
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

44 

program with results reported from excellent control to no control at all. Recently, concerns over 

placing Gambusia in habitats where other fish species assemblages are threatened have arisen. 

Care must be taken in placement of this cosmopolitan species in areas where endemic fish 

species are sensitive to further environmental perturbation. Additionally, use of endemic fish 

species in these areas of concern deserves greater attention. An example of this is Rivulus fish 

species. The potential of Rivulus as mosquito predators is currently being evaluated in saltwater 

habitats, especially in Brevard County, Florida. 

In some aquatic habitats, fish function as an excellent mosquito biocontrol mechanism. 

These typically are permanent habitats where Culex and Anopheles are the primary mosquito 

residents and where the mosquito densities are not excessive. However, in habitats such as salt 

marshes fish are unable to control the sudden explosion of larvae produced by rainfall or rising 

tides. Here, the mosquito population numerically exceeds what the fish can consume during the 

brief immature mosquito developmental period. In salt marshes, fish must rely on things other 

than mosquito larvae for their nutritional needs most of the time, simply because there may be 

long delays between hatches of larvae. Mosquito larvae present an abundant food source, but 

only for a few days during their rapid development. 

Species of predacious mosquitoes in the genus Toxorhynchites have been studied in a 

variety of urban areas for control of container-inhabiting mosquitoes, such as the Asian tiger 

mosquito (Ae. albopictus). Toxorhynchites mosquitoes also affect mosquito populations that 

develop in the treehole environment; however, their introduction into urban container habitats 

has proven unsuccessful. 

In specific containers, Toxorhynchites may consume a large number of prey mosquito 

larvae, such as Aedes aegypti and Ae. albopictus. However, this predator does not disperse well 

enough to impact the vast number of natural and artificial containers used by these mosquitoes. 

Additionally their life-cycle is 2-3 times that of their prey making it impossible for them to keep 

up with the other more rapidly developing mosquitoes. 

Another group of biocontrol agents with promise for mosquito control is the predacious 

copepods (very small crustaceans). Copepods can be readily mass reared, are easily to delivered 

to the target sites, and perform well when used with insecticides. 

Birds and bats are often promoted as potential biocontrol agents of adult mosquitoes. 

However, while both predators eat adult mosquitoes, they do not do so in sufficient amounts to 

impact the mosquito populations. Mosquitoes provide such a small amount of nutrition that birds 

or bats expel more energy pursuing and eating mosquitoes than they derive from them. They are 

not a primary food source for these predators. Additionally, with mosquito flight behavior being 

crepuscular they are not active during the feeding periods of most birds. While bats are active 

during the correct time period, they simply cannot impact the massive numbers of adult 

mosquitoes available. 

Bio-rational products exploit insecticidal toxins found in certain naturally occurring 

bacteria. These bacteria are cultured in mass and packaged in various formulations. The bacteria 

must be ingested by mosquito larvae so the toxin is released. Therefore bio-rational products are 

only effective against larvae since pupae do not feed. The bacteria used to control mosquito 

Deleted: targeting 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

45 

larvae have no significant effects on non-target organisms. The possibility of creating a new 

invasive species by the introduction of biocontrols should be considered, evaluated, and avoided. 

Pesticides. There are chemical and biological pesticide products registered for use against 

mosquitoes. Two biological pesticide products that are used against mosquito larvae singly or in 

combination are Bacillus thuringiensis israelensis (Bti) and Bacillus sphaericus (Bs). 

Manufactured Bti contains dead bacteria and remains effective in the water for 24 to 48 hours; 

some slow release formulations provide longer control. In contrast, Bs products contain live 

bacteria that in favorable conditions remain effective for more than 30 days. Both products are 

safe enough to be used in water that is consumed by humans. In addition to the biological 

pesticides, there are chemical pesticides for use against mosquitoes. As described below, once 

the determination is made to use pesticides to control mosquitoes, additional requirements under 

this general permit must be met. 

Pesticide Use

Conduct larval and/or adult surveillance prior to each pesticide application to assess the 

pest management area and to determine when action threshold(s) are met that necessitate 

the need for pest management. Pest surveillance is important for timing pest control properly 

and to evaluate the potential need for pesticide use for mosquito control. Understanding 

surveillance data may enable mosquito control operators to more effectively target their control 

efforts. Operators are required to conduct a surveillance program to minimize discharges from 

control activities. Surveillance is necessary not only to establish species’ presence and 

abundance but also as an evaluation tool of the effectiveness of source reduction and chemical 

control activities. Furthermore, surveillance should be used as an indicator of the need for 

additional chemical control activities based on pre-established criteria related to population 

densities in local areas. 

Larval surveillance involves routine sampling of aquatic habitats for developing 

mosquitoes. The primary tools used to determine larval densities and species composition are a 

calibrated dip cup and/or a bulb syringe for inaccessible areas such as treeholes. The counts 

may be expressed as the number of immature (larvae and pupae) mosquitoes per dip, per unit 

volume, or per unit surface area of the site. However, due to natural mortality from 

environmental factors, disease and predators, larval dip counts do not provide an accurate 

indication of the potential adult population. Nevertheless, larval counts do indicate when 

chemical larval control measures are warranted. 

Adult surveillance is a key component of any mosquito control program. Adult 

surveillance can be conducted using CDC traps, New Jersey light traps, resting site traps, egg 

oviposition traps, vehicle traps, and landing count rates. Mosquito control operators should use a 

variety of the available traps as adults are attracted to different traps depending on their species, 

sex, and physiological condition. Trapped adults provide information about local species 

composition, distribution, and density. In addition, the need for adulticide application may also 

be established through the number and distribution of service requests received from the public. 

Collection data also provide feedback to the mapping and planning component of the IPM 

program as well as to its effectiveness and also serve to identify new sources of mosquitoes or 

identify recurring problem sites. 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

46 

Disease surveillance, where practical, is also a key component of a pest management 

strategy. Detecting antibodies in “sentinel” chicken flocks, equine cases, and testing dead birds 

and adult mosquitoes for infections are all used to determine whether disease is being transmitted 

in an area. Mosquito and vector control agencies also may test mosquitoes for viruses in their 

laboratories. Although generally less sensitive than sentinel chickens, mosquito infections may 

be detected earlier in the season than chicken seroconversions and therefore provide an early 

warning of virus activity. However, disease surveillance is not applicable to all mosquito control 

programs. In the absence of a dedicated disease surveillance program, mosquito control 

operators should stay informed of arboviral occurrence or potential for occurrence in their 

control areas as determined by local, state, and/or national public health agencies. 

Assess environmental conditions (e.g. temperature, precipitation, and wind speed) in 

the treatment area prior to each pesticide application to identify whether existing 

environmental conditions support development of pest populations and are suitable for 

control activities. Environmental conditions also may affect the results of adulticide 

application. Wind determines how the ULV droplets will be moved from the output into the 

treatment area. Conditions of no wind will result in the material not moving from the application 

point. High wind, a condition that inhibits mosquito activity, will quickly disperse the insecticide 

over too wide an area but at a diluted rate too low to effectively control pests. Light wind 

conditions (< 10 mph) are the most desirable because they move the material through the 

treatment area and are less inhibiting to mosquito activity. Thermal fogs perform best under very 

light wind conditions. 

ULV application should be avoided during hot daylight hours. Thermal conditions, 

particularly temperature inversion, will cause the small droplets to quickly rise, moving them 

away from mosquito habitats. Generally, applications are made after sunset and before sunrise, 

depending upon mosquito species activity. Some mosquitoes (Culex and Anopheles) are most 

active several hours after sunset, while others (Ae. aegypti and Ae. albopictus) are more active 

during the daytime, and if these species are the targets, application should be made during the 

period of highest activity for the target species, provided that meteorological conditions are 

suitable for application (seldom during daylight hours). 

One notable exception to treatments made when mosquitoes are up and flying is a 

residual barrier treatment application. Barrier treatments are based on the natural history and 

behavioral characteristics of the mosquito species causing the problem. Barrier applications use a 

residual material and are generally applied with a powered backpack sprayer to preferred resting 

areas and migratory stops in order to intercept adult mosquitoes hunting for blood meals. Barrier 

treatments are often applied during daylight hours as a large-droplet liquid application and are 

designed to prevent a rapid re-infestation of specific areas, such as recreational areas, parks, 

special-event areas, and private residences. Barrier applications can help provide control of 

nuisance mosquitoes for up to one week or longer. 

Reduce the impact on the environment and on non-target organisms by applying the 

pesticide only when the action threshold has been met. Operators must apply pesticide only 

as indicated by action thresholds for the pest management area. As noted above, action 

threshold, established by the operator, help determine both the need for control actions and the 

proper timing of such actions. Timing pesticide application can reduce the impact on the 

environment and on non-target organisms. 

Deleted: virus
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

47 

In situations or locations where practicable and feasible for efficacious control, use 

larvicides as a preferred pesticide for mosquito or flying insect pest control when larval 

action thresholds have been met. Operators may use larvicides, adulticides or a combination of 

both. However, when practicable and feasible, larviciding should be the primary method for 

mosquito control. Larviciding is a general term for the process of killing mosquitoes by applying 

natural agents or manmade pesticide products designed to control larvae and pupae (collectively 

called larvicides) to aquatic habitats. Larviciding uses a variety of equipment, including aerial, 

from boats, and on the ground, as necessitated by the wide range of breeding habitats, target 

species, and budgetary constraints. Applications can be made using high pressure sprayers, ULV 

sprayers, handheld sprayers, and back sprayers. However, larviciding is only effective when a 

high percentage of the mosquito production sites are regularly treated, which may be difficult 

and expensive. 

There are advantages and disadvantages to aerial and ground larvicide treatments. 

Ground larviciding allows application to the actual treatment area and consequently to only those 

micro-habitats where larvae are present. Therefore, ground larviciding reduces unnecessary 

pesticide load on the environment. However, ground applications often rely on in-the-field 

human estimates of the size of treatment areas and equipment output with a greater chance of 

overdosing or under-dosing. Ground larviciding is also impractical for large or densely wooded 

areas and exposes applicators to greater risk of insecticide exposure. 

Aerial larviciding application methods are generally used for controlling mosquito larvae 

present in large areas and areas that are inaccessible for ground application. However, failure to 

treat an entire area with good larvicide coverage can result in the emergence of large adult 

populations. In order to prevent poor site coverage, a global positioning system (GPS), where 

economically feasible, or site flagging are necessary to increase accuracy of the treatment 

coverage while minimizing the amount of larvicides being applied. Aerial application does 

provide easier calibration of equipment due to the fact that the target area is generally mapped 

and the material is weighed or measured when loading. However, cost of aerial application is 

higher than ground application (i.e. additional personnel for flagging or expensive electronic 

guidance systems) and also requires special FAA licenses, training of staff, and additional 

liability insurance. In addition, aerial larviciding has greater potential for non-target impacts. 

In situations or locations where larvicide use is not practicable or feasible for 

efficacious control, use adulticides for mosquito or flying insect pest control when adult 

action thresholds have been met. Chemical treatment for adult mosquitoes, adulticiding, is the 

most visible and commonly used form of mosquito control. Adulticide applications may be used 

for nuisance or disease vectoring mosquitoes. Adulticiding consists of dispersing an insecticide 

as a space spray into the air column, using ground or aerial equipment, which then remains 

suspended in the air column through the habitat where adult mosquitoes are flying. Any 

mosquito adulticiding activity that does not follow reasonable guidelines, including timing of 

applications, avoidance of sensitive areas, and strict adherence to the pesticide label, risks 

affecting non-target insect species. 

Operators must ensure that the adulticide applications are made only when necessary by 

determining a need in accordance with specific criteria that demonstrate a potential for a 

mosquito-borne disease outbreak, or numbers of disease vector mosquitoes sufficient for disease 

Deleted: both

Deleted: in turn 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

48 

transmission, or a quantifiable increase in numbers of pestiferous mosquitoes. To determine the 

need for adulticide application, at least one of the following criteria should be met and 

documented by records: 1) when a large population of adult mosquitoes is demonstrated by 

either a quantifiable increase in, or a sustained elevated mosquito population level as detected by 

standard surveillance methods, 2) where adult mosquito populations build to levels exceeding 

community standards (e.g., 25 mosquitoes per trap night or 5 mosquitoes per trap hour during 

crepuscular periods), and/or 3) when service requests for arthropod control from the public have 

been confirmed by one or more recognized surveillance methods. 

The most common forms of adulticiding are ultra-low volume spray (ULV) and thermal 

fogging. Ground adulticiding is almost exclusively conducted with ULV equipment and is the 

most common method used to control mosquitoes. Ground adulticiding can be a very effective 

technique for controlling most mosquito species in residential areas with negligible non-target 

effects. 

Aerial adulticiding is a very effective means of controlling adult mosquitoes, particularly 

in inaccessible areas, and may be the only means of covering a very large area quickly in case of 

severe mosquito outbreaks or vector borne disease epidemics. Aerial adulticide applications are 

made using either fixed wing aircraft or rotor craft. Application is generally as ULV spray but 

some thermal fogging still occurs. 

Adulticide application has its own set of conditions that determine success or failure. The 

application must be at a dosage rate that is lethal to the target insect and applied with the correct 

droplet size. Whether the treatment is ground or aerially applied, it must distribute sufficient 

insecticide to cover the prescribed area with an effective dose. Typically with ground 

applications, vegetated habitats may require up to three times the dosage rates that open areas 

require. This is purely a function of wind movement and its ability to sufficiently carry droplets 

to penetrate foliage. In addition, aerial application is dependent upon favorable weather 

conditions. 

Recommended Mosquito Control References 

EPA recommends the following sources for additional information on IPM’s and BMP’s for 

mosquito control. 

Anderson, RR and LC Harrington. 2010. Mosquito Biology for the Homeowner. Cornell 

Cooperative Extension – Medical Entomology Extension. Available at: 

http://www2.entomology.cornell.edu/MedEnt/MosquitoFS/MosquitoFS.html

American Mosquito Control Association. 2009. Mosquito Information. Available at: 

http://www.mosquito.org/mosquito-information/index.aspx

American Mosquito Control Association. 2010. Best Management Practices for Integrated 

Mosquito Management. Available at: 

http://www.mosquito.org/secure/upload/articles/BMPsforMosquitoManagement.pdf

California Department of Public Health. 2008. Best Management Practices for Mosquito 

Control on California State Properties. Available at: 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

49 

http://westnile.ca.gov/downloads.php?download_id=996&filename=CDPH_BMP_

MosquitoControl6-08.pdf

Commonwealth of Massachusetts Department of Food and Agriculture State Reclamation and 

Mosquito Control Board. 1998. Generic Environmental Impact Report (GEIR) 

for the Massachusetts Mosquito Control. Available at: 

http://www.mass.gov/agr/mosquito/geir_docs/GEIR_FULL_TEXT.pdf

Florida Coordinating Council on Mosquito Control. 2009. Florida Mosquito Control – The 

State of Mission as defined by mosquito controllers, regulators, and environmental managers. 

Available online at: 

http://mosquito.ifas.ufl.edu/Documents/Florida_Mosquito_Control_White_Paper.pdf

New York City Department of Health and Human Hygiene. 2006. Comprehensive Mosquito 

Surveillance and Control Plan. Available at: 

http://www.nyc.gov/html/doh/downloads/pdf/wnv/wnvplan2006.pdf

Grodner, MG, J Criswell, C Sutherland, P Spradley, DL Renchie, ME Merchant, M Johnsen, and 

S Sawlis. 2007. The Best Way to Control Mosquitoes - Integrated Mosquito Management 

Explained. Available at: http://wwwaes.tamu.edu/Public_Health_and_Vector_Control/Publications/The%20Best%20Way%20to%20

Control%20Mosquitoes.pdf

Kwasny, DC, M Wolder, and CR Isola. 2004. Technical Guide to Best Management Practices 

for Mosquito Control in Managed Wetlands. Central Valley Joint Venture. Available at: 

http://www.dfg.ca.gov/lands/wetland/docs/CVJV-Mosquito-BMP.pdf 

Rose, RI. 2001. Pesticides and Public Health: Integrated Methods of Mosquito Management. 

Emerging Infectious Diseases 7:1. Available at: 

http://www.cdc.gov/ncidod/eid/vol7no1/rose.htm

Sacramento-Yolo Mosquito and Vector Control District. 2008. Mosquito Reduction Best 

Management Practices. Available at: 

http://www.fightthebite.net/download/SYMVCD_BMP_Manual.pdf

State of Massachusetts. 2008. Massachusetts Best Management Practices and Guidance for 

Freshwater Mosquito Control. Available at: 

http://www.mass.gov/agr/mosquito/docs/mepa/Document_2_Freshwater%20BMP%20to%20ME

PA_%20Oct_24_2008.pdf

State of New Hampshire. 2008. Policy for Mosquito Control on State Lands. Available at: 

http://governor.nh.gov/news/documents/040108policy.pdf

State of New Mexico. 2008. Philosophy of Mosquito Control. 

http://www.health.state.nm.us/ERD/HealthData/documents/PhilosophyofMosquitoControl2008_

000.pdf

Washington State Department of Ecology/Water Quality Program. 2004. Best Management 

Practices for Mosquito Control. Available at: http://www.ecy.wa.gov/biblio/0310023.html
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

50 

b. Other Flying Insect Pest Control (Black Flies Example) 

The Agency has chosen to use black flies as a demonstration of how IPM practices would 

be implemented for other flying insect pest control. 

Black Flies – Background 

There are 1800 species of black flies throughout the world with approximately 254 

species in North America alone. Black flies can be 1) a source of annoyance to people, animals, 

and wildlife, 2) a limiting factor in economic development (e.g., residential development and 

property value), and 3) a causal factor in decreased agricultural productivity (e.g., animal weight 

loss/death and milk production). Black fly control in the U.S. provides economic, health and 

quality of life benefits. In contrast to the integrated approach used for mosquito control, due to 

its unique biology, black fly control in the U.S. is primarily through the use of larvicides. 

Black Flies - IPM Practices

Identify the Problem 

Part 2.2.1.1: Prior to the first pesticide application covered under this permit that will 

result in a discharge to waters of the U.S., and at least once each calendar year thereafter 

prior to the first pesticide application for that calendar year, you must do the following for 

each pest management area, as defined in Appendix A. Operators must identify the pest 

problem in their pest management area prior to the first application covered under this permit. 

Knowledge of the pest problem is an important step to developing pest management strategies. 

Re-evaluation of the pest problem is also important to ensure pest management strategies are still 

applicable. Operators must identify the pest problem at least once each calendar year prior to the 

first application for that calendar year. Operators are required to fulfill problem identification 

requirements to minimize discharges to waters of the U.S. in black fly control operations. 

Identification includes: (1) black fly biology, (2) local developmental habitats, (3) avoidance 

methods, and (4) the benefits and risks of chemical use as a pest management strategy. 

Black flies, commonly referred to as buffalo gnats, are the smallest of the blood feeding 

dipterans. Worldwide, blackflies are responsible for transmitting ochocerciasis (river blindness) 

to millions of people in tropical areas. Black flies can also vector bovine onchocerciasis, 

mansonellosis, and leucoytozoonosis in wild and domestic animals. While generally only 

considered nuisance pests in the U.S., epidemiological research has demonstrated that black flies 

are competent vectors of vesicular stomitis and suggests that these pests may be responsible for 

periodic outbreaks of this disease in livestock, wildlife, and humans in the western U.S. 

However, flies may also become so abundant as to be drawn into the air passages of livestock, 

occasionally resulting in death. Black fly feeding activity may also result in allergic reaction in 

both animals and man as a result of histaminic substances in black fly saliva. 

Establish densities for larval and adult mosquito or flying insect pest populations to 

serve as action threshold(s) for implementing pest management strategies. Operators must 

develop action thresholds for black flies prior to first pesticide application covered under this 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

51 

permit. The action thresholds must be re-evaluated at least once each calendar year. As noted in 

the general discussion above, an action threshold is a point at which pest populations or 

environmental conditions indicate that pest control action must be taken. Action thresholds help 

determine both the need for control actions and the proper timing of such actions. It is a 

predetermined pest level that is deemed to be unacceptable. 

Identify the target mosquito or flying insect pest species to develop species-specific 

pest management strategies based on developmental and behavioral considerations for 

each species. The life cycle for black fly includes four stages: egg, larva, pupa, and adult. All are 

aquatic except the adults, which leave the water to search for food and mates. Black fly 

immatures have three general life history strategies. One group of species produces 1 generation 

per year (univoltine) that matures in late winter or early spring. A second group is also 

univoltine, but these species develop during late spring or summer. The third and final group of 

species produces 2 or more generations per year (bivoltine or multivoltine) that typically develop 

from early summer through fall. 

Adult females deposit from 150 to 500 eggs in flowing water. Flowing water habitats 

capable of black fly production range from a 4-inch trickle to large rivers. Egg-laying occurs 

near dusk for many species. The eggs are dropped singly from the air or deposited in masses on 

trailing vegetation, rocks, debris and other substrates. Eggs hatch in 2 days to 8 months, 

depending on black fly species and water temperature. Incubation time in some species is 

delayed by a prolonged diapause, or resting period. Eggs of many species can successfully 

withstand temperature extremes, fluctuating water levels, and desiccation associated with 

alternating flood and drought conditions during seasonal changes. Many species overwinter in 

the egg stage, but a few black flies spend the winter months as larvae and pupae, or rarely, as 

adults. 

Larvae anchor themselves to clean vegetation, rocks, or debris by spinning a small silken 

pad with their mouthparts and inserting a row of hooks at the end of their enlarged abdomen into 

the silk pad. This technique allows the larvae to secure themselves in areas of very fast water 

velocity and orient their body with the abdomen pointed upstream, and head positioned 

downstream to feed. Larvae can easily relocate to other areas by drifting downstream on a silken 

thread, spinning a new silk pad, and reattaching themselves in areas with more acceptable 

substrates or food supplies. Feeding is accomplished by expanding a pair of fan-like structures 

on their hardened head capsule to efficiently filter microscopic food particles from the water 

column. The larvae filter or scrape very fine organic matter, filamentous algae, bacteria and tiny 

aquatic animals from the current or substrates. Larvae are often infected with various parasites 

and pathogens, including nematode worms, bacteria, fungi, protozoa and viruses. 

Larval instars vary from 4 to 9, depending on species, with many species passing through 

an average of 7 instars. Larval development time varies from 1 week to 6 months depending on 

species, water temperature, stream turbidity and food availability. Larval growth is very 

temperature dependent, with relatively slow growth during the cold winter months and very rapid 

growth during warm summer water temperatures. Some summer-developing, multivoltine 

species are capable of completing their entire life cycle in just a few weeks. Mature larvae, with 

fully developed respiratory filaments visible as a dark area on each side of the thorax, stop 

feeding, and construct a silken pupal cocoon where metamorphosis takes place. 

Deleted: note

Deleted: a 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

52 

Pupae secure themselves inside their cocoons with rows of spine-like hooks on their 

abdomen. The tightly woven or loose cocoons, characteristically shaped for each species, are 

attached to substrates with the closed end facing upstream to protect pupae from current and 

sediments. Some species have a lateral aperture, or window, on each side of the cocoon to 

increase water circulation around the pupa. The branched respiratory organs that project from the 

pupal thorax are designed to function in or out of water. This adaptation allows pupae to obtain 

oxygen at all times, and survive normal fluctuations in water levels. The pupal stage may last 

from 2 days to several weeks depending on the species and water temperature. 

Adults emerge from the pupal skin through an elongate slit at the top of the thorax and 

ride a bubble of air that propels them to the water surface. Freshly emerged adults fly to 

streamside vegetation where their wings and bodies quickly dry and harden. Mature adults 

immediately seek food sources and mates. Both sexes feed on nectar, sap, or honeydew to obtain 

the sugar used for flight and energy. Only females feed on blood. In most species, mating takes 

place in flight, with females flying into male swarms that form over landmarks such as 

waterfalls, vegetation or host species. Males utilize their large eyes to detect and seize females 

entering the swarm. Male and female pairs exit the swarm, and mating takes place in flight in 

just a few seconds. Females then seek a host to obtain the blood meal required to nourish their 

eggs. Adults are strong fliers, capable of dispersing many miles from their larval habitats. 

Black fly females are attracted to their specific hosts by size, shape, color, carbon 

dioxide, body odor, body movement, skin texture, temperature and humidity. Females use their 

mouthparts to cut, or lacerate the host skin, and then drink from the resulting pool of blood. 

Anticoagulants in the saliva are injected into the bite to facilitate bleeding. Many domestic and 

wild animals have been killed by outbreaks of adult black flies. Deaths have been attributed to 

acute toxemia from large numbers of bites, anaphylactic shock, and weakness due to blood loss. 

In humans, lesions can develop at the bite, accompanied by reddening, itching, and swelling. In 

severe cases, allergic reactions may occur, resulting in nausea, dizziness, and fever. 

Host specificity in black flies varies from highly specific species that will feed on blood 

from only 1 host, too much more generalized species that will draw blood from a number of 

different hosts. Although host preferences for many North American black flies are poorly 

understood, it is estimated that 67% feed on mammals and 33% feed on birds. Approximately 

10% of North American species will feed on the blood of humans. 

Prior to first pesticide application covered under this permit, operators must ensure 

proper identification of black fly species to develop a detailed pest management strategy. Due to 

preferred hosts and developmental habitats, proper identification of the pest species is 

instrumental in determining the biology (univoltine or multivoltine), and developmental habitat 

preference (e.g., flow rate, stream size, stream substrate composition), and flight range of the 

target species. By knowing these factors, a control program can 1) determine if the black fly 

species warrants control activities (i.e. host preference and historical problems), 2) identify 

habitats and delineate the potential area for ongoing monitoring and control activities, 3) 

determine frequency of site monitoring, 4) estimate timing for pesticide application (i.e. 

historical seasonal occurrence, age distribution of susceptible immature population, 

environmental conditions suitable for control activity, etc.), 5) reduce discharge of pesticides into 

waters of the U.S. 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

53 

Identify known breeding sites for source reduction, larval control program, and 

habitat management. In conjunction with species identification, mapping should be considered 

part of control programs aimed at black fly management. Maps may simply be 

township/city/county maps but may also include aerial photo assessments, topographic maps, 

and satellite imagery where available and/or practicable. Mapping is essential to identify areas 

of flowing water which are suitable for production of the target species. As black flies are strong 

fliers and will travel great distance to obtain a blood meal, mapping should be for an extended 

area from the site to be protected by control activities. Species identification and mapping 

should also be a priority in a surveillance program (both current and historical) to determine the 

need for initiating control activity. Identification and mapping are both essential to planning a 

control program which reduces pesticide discharge into waters of the U.S. 

Analyze existing surveillance data to identify new or unidentified sources of 

mosquito or flying insect pest problems as well as sites that have recurring pest problems. 

As discussed above, mapping is a valuable tool in assessing pest habitats and designing control 

programs. Operators must analyze existing surveillance data to identity new sources of black fly 

problems. 

In the event there are no data for your pest management area in the past calendar year, see 

Part 5 for documentation requirements regarding why current data are not available and 

the data you used to meet the permit conditions in Part 2.2.1.1. Operators may use historical 

data or neighboring district data to identify the species and establish action thresholds. 

Pest Management 

Part 2.2.1.2: Prior to the first pesticide application covered under this permit that 

will result in a discharge to waters of the U.S., and at least once each calendar year 

thereafter prior to the first pesticide application for that calendar year, you must select and 

implement, for each pest management area, efficient and effective means of pest 

management that minimize discharges resulting from application of pesticides to control 

mosquitoes or other flying insect pests. In developing these pest management strategies, 

you must evaluate the following management options, considering impact to water quality, 

impact to non-target organisms, pest resistance, feasibility, and cost effectiveness: No 

action; Prevention; Mechanical/physical methods; Cultural methods; Biological control 

agents; and Pesticides. Operators are required to evaluate and implement a pest management 

strategy to minimize pesticide discharge into waters of the U.S. prior to the first pesticide 

application covered under this permit. Pest management strategies will vary by locality (i.e. 

stream size, stream substrate, and stream vegetation), black fly species (i.e. multi/univoltine 

development and host specificity), and financial concerns (i.e. accessibility to streams and 

size/rate of flow for the streams). As noted above, combinations of various management 

methods are frequently the most effective pest management strategies over the long term. The 

goal should be to emphasize long-term control rather than a temporary fix. Operators must 

reevaluate every year prior to the first pesticide application for that calendar year. 

Based on problem identification, two preventive strategies other than pesticides should be 

evaluated. The first is reducing the number of black fly breeding areas. This may include 

removal (physical and/or chemical) of vegetation and other objects in streams to reduce number 

of larval habitats. The second is temporary damming of flowing stream larval development sites 

Deleted: source

Deleted: flies problem

Deleted: Parts 

Deleted: and 7 

Deleted: any 

Deleted: or record keeping

Deleted: of

Deleted: ;
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

54 

to create pool habitats. As larvae require flowing water for development, pooling can kill 

developing black fly larvae. However, the impact of these habitat management options must be 

considered in relation to other environmental impacts on other aquatic species. Furthermore, due 

to the wide variability in stream size/flow rate and the accessibility of streams for habitat 

modification, these options are seldom acceptable control solutions for most black fly 

developmental habitats. 

Pesticide Use

Conduct larval and/or adult surveillance prior to each pesticide application to assess the 

pest management area and to determine when action threshold(s) are met that necessitate 

the need for pest management. Larval surveillance involves routine sampling of aquatic 

habitats for developing black flies. Larval surveillance is primarily accomplished by collecting 

stream substrates (rocks, vegetation, etc.) and examining for larval and pupal occurrence. Due to 

the varied developmental sites for black larvae and their ability to move in streams relative to 

changes in flow patterns, quantitative sampling will vary from site to site and in many instances, 

particularly with continuously changing water levels, is not practical. Qualitative sampling is 

often used in lieu of quantitative sampling, as an indicator of egg hatch and to indicate the age 

distribution of developing larvae. Qualitative sampling alone when used in conjunction with 

historical occurrence data can provide a reliable indicator of the need to initiate control activities. 

Adult surveillance for black flies may include sweep sampling, vacuum aspiration of 

adults, and the use of silhouette traps. Traps may be simple visual attractants or may be baited 

with artificial attractants (e.g., ocentol and CO2). However, as different black fly species will 

respond differently in relation to different attractants, based on host preference, care must be 

used in selecting attractants that will provide a representative sample of the complete black fly 

spectrum present in any given location. Choice of adult sampling will in many cases be dictated 

by historical occurrence of black flies in a given area. Regardless, surveillance data is a useful 

tool in providing feedback to the mapping and planning component of any pest management 

strategy. 

Assess environmental conditions (e.g. temperature, precipitation, and wind speed) in 

the treatment area prior to each pesticide application to identify whether existing 

environmental conditions support development of pest populations and are suitable for 

control activities. Environmental conditions may affect the results of pesticide application. 

Operators must assess the treatment area to determine whether site conditions support pest 

populations and are suitable for pesticide application. 

Reduce the impact on the environment and on non-target organisms by applying the 

pesticide only when the action threshold has been met. Operators must apply pesticide only 

as indicated by action thresholds for the pest management area. As noted above, action threshold 

help determine both the need for control actions and the proper timing of such actions. Timing 

pesticide application can reduce the impact on the environment and on non-target organisms. 

In situations or locations where practicable and feasible for efficacious control, use 

larvicides as a preferred pesticide for mosquito or flying insect pest control when larval 

action thresholds have been met. Bacillus thuringiensis var israelensis (Bti) is the primary 

larvicide used for black fly control in the U.S. Bti is a gram positive, aerobic, spore-forming 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

55 

bacterium that produces protoxins in the form of parasporal protein crystals. In the alkaline 

digestive tract of black flies and mosquitoes, the protoxins become activated into highly toxic 

delta-endotoxins. The endotoxins cause a rapid breakdown in the lining of the mid-gut and 

necrosis of skeletal muscles, resulting in paralysis and mortality of target insect pests. Bti is 

nontoxic to most non-target organisms due to their acidic digestive systems and lack of suitable 

tissue receptor sites. 

To minimize pesticide discharge into waters of the U.S., operators must apply larvicides 

as needed for source reduction as indicated by the action threshold in situations or locations 

where it is practicable and feasible to do so. The action threshold may be based on occurrence of 

adults (current or historical) and/or larval sampling of stream substrates for immature black flies. 

Surveillance is also a valuable tool for assessing the effectiveness of larval control activities. 

Larvicides may be applied to streams using either ground or aerial equipment. Choice of 

equipment is largely dictated by stream size and accessibility. Application equipment may 

include backpack sprayers, boats equipped with sprayers or metered release systems, helicopters 

or fixed wing aircraft. The amount of insecticide required to treat a stream should be based on 

the desired dosage and the stream discharge. Stream discharge is calculated by determining the 

average width and depth of the stream and the stream velocity (discharge = width (m) x depth 

(m) x velocity (m/s)). Proper calibration of insecticide delivery based on discharge is necessary 

to ensure complete coverage throughout the water column in order to expose all larval habitats to 

an effective insecticide dose. 

Larvicide is applied across the stream width for the time specified by the application rate. 

The point of application should be far enough upstream from the larval habitat to ensure proper 

insecticide dispersal in the water passing over the treatment area. Operators should determine 

the effective downstream carry (maximum distance at which at least 80% larval control is 

achieved) of the insecticide suspension. By determining downstream carry, black fly control 

operators can limit the number of applications necessary to treat any given stream and thereby 

reduce pesticide discharge into waters of the U.S. 

In situations or locations where larvicide use is not practicable or feasible for 

efficacious control, use adulticides for mosquito or flying insect pest control when adult 

action thresholds have been met. Pesticide control of black flies in the U.S. historically relied 

upon both larvicides and adulticides. However, adulticide use against black fly populations is no 

longer a common practice. As adult black flies are seeking blood meals during the daytime, 

adulticide application coincides with human activity, so daytime application is no longer a 

standard control procedure. One reason for this change is due to environmental factors 

associated with daytime adulticide application, particularly thermal inversions, which cause 

adulticide application for black fly control to be ineffective. Furthermore, as only adults directly 

contacted by the adulticide application are killed, with no residual activity against other adults 

immigrating to the treatment area, adulticide applications are both ineffective and expensive. 

For these reasons, larvicides which target the immature stages before development of the 

pestiferous adult are now the primary means of black fly control in the U.S. 

Recommended Black Fly Control References 

EPA recommends the following sources for additional information on IPMs and BMPs 

for black fly control: 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

56 

Commonwealth of Pennsylvania. 2009. Black Fly Suppression Program. Available at: 

http://www.depweb.state.pa.us/blackfly/cwp/view.asp?a=3&Q=505536&blackflyNav=|

Government of Alberta – Agriculture and Rural Development. 1993. Black Fly Control. 

Available at: http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex3321

Greater Los Angeles Vector Control District. 2008. Black Flies – Vector Services and 

Information. Available at: http://www.glacvcd.org/Contents/Vector-Services-Info/BlackFlies.aspx

Metropolitan Mosquito Control District. 2009. Biting Gnat Control. Available at: 

http://www.mmcd.org/gnat.html

North Carolina Cooperative Extension. 2005. Insect Notes – Black Flies and Their Control. 

Available at: http://www.ces.ncsu.edu/depts/ent/notes/Urban/blackfly.htm

North Elba – Black Fly Control Dept. 2009. About the black fly control program. Available at: 

http://www.northelba.org/html/black_fly_control.html

Ohio State University Extension. 1997. Factsheet – Black Flies. HYG-2167-97. Available at: 

http://imayhavetermites.com/Black%20Flies,%20HYG-2167-97.htm

The Merck Veterinary Manual. 2009. Black Flies. Available at: 

http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/71702.htm

Undeen, AH and DP Malloy. 1996. Use of stream width for determining the dosage rates of 

Bacillus Thuringiensis Var. israensis for larval black fly (Diptera: Simuliidae) control. Journal 

of the American Mosquito Control Association. 12(2):312-315. Available at: 

http://www.nysm.nysed.gov/bio_molloy/patent_pubs/pdfs/undeen_&_molloy_1996_use_of_stre

am_width.pdf

University of Florida. 2007. Featured Creatures – Black Flies. EENY-30. Available at 

http://entomology.ifas.ufl.edu/creatures/livestock/bfly.htm

University of New Hampshire Cooperative Extension. 2001. Black Flies. Available at: 

http://www.ultimate.com/washington/wla/blackfly/

2.2.2. Aquatic Weed and Algae Control 

Background

Aquatic weeds and algae that negatively affect aquatic biodiversity, human health, and 

economic stability are considered to be pests. Aquatic weeds and algae can decrease populations 

of native aquatic species including threatened and endangered species. Aquatic weeds and algae 

can reduce aquatic biodiversity by preventing desirable species growth and unbalancing 

desirable aquatic species populations and development. Social, economic, and human health are 

all affected by a lower aesthetic appeal of a water bodies, an increased cost of agricultural 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

57 

irrigation water, and an increase in the risk of human diseases by providing ideal vector breeding 

grounds. In addition, the reduction in the utility of water can have social and economic impacts 

due to reduced hydroelectric operations, impeded opportunity for recreational activities (e.g., 

fishing, boating, and swimming), and disruption of water transport (e.g., agricultural irrigation) 

to name a few. As a result, if aquatic weeds and algae become established and impede the 

environmental stability and use goals for a body of water, control measures will be necessary. 

Pest control may be necessary before the pests become established. 

The requirements in Part 2.2.2, apply to pesticide discharges associated with management 

of aquatic weed and algae in, but not limited to, lakes, ponds, rivers, streams, irrigation canals, 

and drainage systems. Irrigation and drainage systems differ in the type and disposition of the 

water that they convey; these systems may consist of earthen or concrete lined canals or 

combinations of the two. 

Most aquatic plants and algae are largely beneficial to water quality, especially when 

present in the appropriate densities. However, overabundant native algae and aquatic vegetation, 

as well as introduced, exotic species can decrease water quality and utility. Dense plant or algae 

growth can interfere with recreational activities (e.g., fishing, boating, and swimming), disrupt 

water transport, reduce aquatic biodiversity by preventing desirable plant growth and 

unbalancing fish populations, lower the aesthetic appeal of a water body, and increase the risk of 

human diseases by providing ideal vector breeding grounds. 

Algae 

Algae are non-vascular plant that do not have true roots, stems, leaves, or vascular tissue 

and have simple reproductive systems. Some macroscopic algae may resemble a plant in 

appearance. Algae may occur in the sea or freshwater. Algae are an important aquatic food 

source for many animals. However, excess algae growth such as algae blooms, frequently 

caused by unbalanced or elevated nutrients, can be damaging to aquatic ecosystems. Control 

options include mechanical, biological, and chemical methods. 

Weeds

Aquatic weeds include floating, emergent, or submerged plants that negatively impact the 

quality and utility of waters of the U.S. Aquatic systems need plant materials as an important 

part of the systems ecology; however, when vegetation becomes established to the point of 

impeding the use goals for a body of water, control measures will become necessary. As a part 

of such aquatic weed control programs a pest management strategy should consider mechanical, 

biological, and/or chemical controls. Details for developing an integrated aquatic weed pest 

management strategy can be found in the document Aquatic Plant Management, Best 

Management Practices in Support of Fish and Wildlife Habitat (January 2005. Aquatic 

Ecosystem Restoration Foundation. Project Leader Kurt Getsinger, Ph.D. 

http://cenapa.ucdavis.edu/files/54815.pdf). 

The appropriate type of control for aquatic weeds and algae is dictated by the biology of 

the target species and by environmental conditions and concerns for a specific area. "Control" 

means, as appropriate, eradicating, suppressing, reducing, or managing invasive species 

populations, preventing spread of aquatic nuisance plants from areas where they are present, and 

Deleted: pest

Deleted: An aquatic weed includes
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

58 

taking steps such as restoration of native species and habitats to reduce the effects of aquatic 

nuisance plants and to prevent further invasions. [Source: 

www.invasivespeciesinfo.gov/laws/execorder.shtml#sec1] Numerous strategies are used to 

reduce the impact of aquatic weeds and algae, but a pest management strategy should be the 

basis for any pest control program. This is a comprehensive approach for managing pest 

populations using a variety of control methods. 

Aquatic Weed and Algae Control IPM Practices 

Identify the Problem 

Part 2.2.2.1: Prior to the first pesticide application covered under this permit that 

will result in a discharge to waters of the U.S., and at least once each calendar year 

thereafter prior to the first pesticide application for that calendar year you must do the 

following for each pest management area, as defined in Appendix A. Operators must 

identify the pest problem in their pest management area prior to the first application covered 

under this permit. Knowledge of the pest problem is an important step to developing pest 

management strategies. Re-evaluation of the pest problem is also important to ensure pest 

management strategies are still applicable. Operators must identify the pest problem at least 

once each calendar year prior to the first application for that calendar year.

 Identify areas with aquatic weed or algae problems and characterize the extent of 

the problems, including, for example, water use goals not attained (e.g. wildlife habitat, 

fisheries, vegetation, and recreation). Operators must be well-acquainted with the unique 

regional conditions of their sites and available methods for controlling the pest species present. 

Intended use goals for the water bodies that are being impeded because of nuisance pest 

infestation must also be considered based on the control site. The use of the best available 

mapping information to aid in identifying the problem areas is suggested. Mapping may include 

aerial photo assessments, topographic maps, and satellite imagery where available and/or 

practicable. Mapping can be essential to identify problem areas which can and cannot be 

controlled using non-pesticide preventative measures (e.g., mechanical control). Mapping can 

also be used in plotting the regional desired aquatic species, as well as water use goals and 

complaints or reports of aquatic weeds and algae from the public. 

Identify target weed species. Positive identification of the aquatic weed or algae is 

required because many species within the same genera may require different levels and types of 

control measures species. Aquatic weed and algae identification is important when determining 

the best pest management strategy for each particular species and for determining application 

areas. Operators should develop a detailed pest management strategy based on identification of 

the targeted pest species which occur in their area. 

Identify possible factors causing or contributing to the weed or algae problem (e.g., 

nutrients, invasive species, etc). While there may not be reasonable means to control and/or 

stop the introduction and occurrence of some nuisance species infestations, the identification of 

possible sources (e.g., outflows from other water systems/bodies) may help in reducing the need 

for control measures. Potential aquatic weed and algae sources such as changes in nutrient levels 

or accidental or intentional introduction of exotic species must be identified before control 

measures are implemented

Deleted: These are 

Deleted: es
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

59 

 Establish past or present aquatic weed or algae densities to serve as action 

threshold(s) for implementing pest management strategies. Any data and/or information 

regarding pest densities can be used to establish an action threshold. Determining increases in 

pest densities may indicate a need for action. An action threshold must be established before 

implementing a pest management strategy. However, action thresholds will be species specific. 

 In the event there are no data for your pest management area in the past calendar 

year, see Part 5 for documentation requirements regarding why current data are not 

available and the data you used to meet the permit conditions in Part 2.2.2.1. Operators 

may use historical data or neighboring district data to identify the species and establish action 

thresholds. 

Pest Management

Part 2.2.2.2: Prior to the first pesticide application covered under this permit that 

will result in a discharge to waters of the U.S., and at least once each calendar year 

thereafter prior to the first pesticide application for that calendar year, you must select and 

implement, for each pest management area, efficient and effective means of pest 

management that minimize discharges resulting from application of pesticides to control 

aquatic weeds or algae. In developing these pest management strategies, you must evaluate 

the following management options, considering impact to water quality, impact to nontarget organisms, pest resistance, feasibility, and cost effectiveness: No action; Prevention; 

Mechanical/physical methods; Cultural methods; Biological control agents; and Pesticides. 

Operators must evaluate and implement a pest management strategy to minimize pesticide 

discharge into waters of the U.S. prior to the first pesticide application covered under this permit. 

As noted above, combinations of various management methods are frequently the most effective 

pest management strategies over the long term. The goal should be to emphasize long-term 

control rather than a temporary fix. Operators must reevaluate every year prior to the first 

pesticide application for that calendar year. All control measures must be implemented in a 

manner that reduces impacts to non-target species. The following describes the management 

options that must be evaluated. 

No Action

 No action is to be taken, although an aquatic weed or algae problem has been identified. 

This may be appropriate in cases where, for example, available control methods may cause 

secondary or non-target impacts that are not justified, no available controls exist, or the pest 

population is stable at a level that does not impair water body uses. 

Prevention

 Preventing introductions of possible aquatic weeds and algae is the most efficient way to 

reduce the threat of nuisance species (ANS Task Force, 2009). Identifying primary pathways of 

introduction and actions to cut off those pathways is essential to prevention. Through a better 

understanding of the transportation and introduction of aquatic weeds and algae, private entities 

(aquaculture) and the public have the necessary knowledge to assist in local aquatic weed and 

algae control by reducing conditions that encourage the spread of aquatic weeds and algae in 

Deleted: Parts 

Deleted: and 7 

Deleted: any 

Deleted: or record keeping 

Deleted: of

Deleted: or 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

60 

their immediate surroundings. For example, recreational water users provide a pathway of 

unintentional introductions. Increasing public awareness of aquatic weeds and algae, their 

impacts, and what individuals can do to prevent their introduction and spread is critical for 

prevention. Other examples of prevention include: better design of water holding sites, better 

management and maintenance of potential problem sites, and volunteer removal of pest species 

(e.g., hand weeding). Monitoring and detection also play important roles in the prevention of the 

spread and introduction of aquatic weeds and algae. 

Cultural Method

Cultural techniques include the use of pond dyes and water-level drawdown. Use pond 

dyes to manage filamentous algae and submersed (underwater) vegetation. Several pond 

colorants and one or two dyes are EPA-registered for aquatic-weed control. Pond dyes and 

colorants can be effective if there is little water outflow from the pond. Dyes and colorants 

intercept sunlight needed by algae and other underwater plants for photosynthesis. Therefore, 

they are generally ineffective on floating plants like duckweed and water lilies and emergent 

(growing above the surface) plants like cattails and bulrushes. Dyes and colorants are nontoxic 

and do not kill the plants, and they are safe for use in ponds for irrigation, fishing and livestock. 

However, they are not intended for use in large lakes with a lot of water flow or lakes used for 

public water supplies.8

Mechanical and Biological Control 

Mechanical and biological controls will be the appropriate method in some cases, or a 

part of a combination of methods. In some instances, the need for chemical pesticide use in and 

adjacent to the affected habitat can be reduced or virtually eliminated with proper execution of 

alternative strategies and proper best management practices. 

Mechanical control techniques will vary depending on the pest. Examples include 

dewatering, pressure washing, abrasive scrubbing, and weed removal by hand or machine. 

 Biological control of aquatic weeds and algae may be achieved through the introduction 

of diseases, predators, or parasites. While biological controls generally have limited application 

for control of aquatic weeds and algae, the operator should fully consider this option in 

evaluating pest management options. 

Pesticide

 Aquatic herbicides are chemicals specifically formulated for use in water to kill or 

control aquatic plants. Aquatic herbicides are spray directly onto floating or emergent aquatic 

plants or are applied to the water in either a liquid or pellet form. Systemic herbicides are 

capable of killing the entire plant. Contact herbicides cause the parts of the plant in contact with 

the herbicide to die back, leaving the roots alive and able to regrow. Non-selective, broad 

 8 http://www.grounds-mag.com/mag/grounds_maintenance_weeds_overboard/

Deleted: of control method 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

61 

spectrum herbicides will generally affect all plants that they come in contact with. Selective 

herbicides will affect only some plants.9

 

Pesticide Use

Conduct surveillance prior to each pesticide application to assess the pest 

management area and to determine when the action threshold is met that necessitates the 

need for pest management. Often, each aquatic weed and algae species and pest management 

area warrants a different pest management strategy tailored to the regional conditions. The pest 

management strategy should consist of combinations of mechanical, biological, and/or pesticidal 

control methods. All control measures must be conducted in a manner that minimizes impacts to 

non-target species. 

Operators should apply chemical pesticides only after considering the alternatives and 

determining those alternatives not to be appropriate control measures. If pesticides are used they 

must be used only as needed as determined by the action threshold, and proper best management 

practices including use of the minimum effective application rate. Also, the operator should 

conduct surveillance (e.g., pest counts or area survey) prior to application of pesticides to 

determine when the action threshold is met and necessitates the need for pest control measures. 

Surveillance may include the relatively sophisticated transect method used in ecological 

studies to evaluate species distribution, or it may consist of simply conducting visual 

observations in the treated area to verify the eradication or reduction in populations of aquatic 

weeds and algae following pesticide application (Getsinger et al. 2005, pp 23-25). 

Reduce the impact on the environment and non-target organisms by applying the 

pesticide only when the action threshold has been met. Operators must apply pesticide only 

as indicated by action thresholds for the pest management area. As noted above, action threshold 

help determine both the need for control actions and the proper timing of such actions. Timing 

pesticide application can reduce the impact on the environment and on non-target organisms. 

Environmental factors such as temperature and dissolved oxygen content, as well as biological 

factors such as stage of growth should be considered when deciding on application timing. 

Partial site treatments over time may be considered to reduce risk. Pesticide application must be 

limited to the appropriate amount required to control the target pests. Methods used in applying 

pesticides must reduce the impact to non-target species. 

Recommended Aquatic Weed and Algae Control References 

EPA recommends the following sources for additional information on IPM’s and BMP’s 

for aquatic nuisance plant control: 

Aquatic Nuisance Species Taskforce. Online: http://www.anstaskforce.gov/default.php. 

Aquatic Plant Management, Best Management Practices in Support of Fish and Wildlife Habitat. 

January 2005. Aquatic Ecosystem Restoration Foundation. Project Leader Kurt Getsinger, 

(http://cenapa.ucdavis.edu/files/54815.pdf) 

 9 http://www.ecy.wa.gov/programs/wq/plants/management/aqua028.html

Deleted: necessitate

Deleted: Each

Deleted: often warrant

Deleted: an
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

62 

2.2.3 Aquatic Nuisance Animal Control

Background 

Aquatic nuisance animals, such as fish, lampreys, and mollusks, negatively affect aquatic 

biodiversity, human health, and economic stability. Aquatic nuisance animals decrease 

populations of native aquatic species including threatened and endangered species. Aquatic 

nuisance animals can reduce aquatic biodiversity by preventing desirable species growth and 

unbalancing desirable aquatic species populations and development. Social, economic, and 

human health are all affected by a lower aesthetic appeal of water bodies, an increased cost of 

agricultural irrigation water, and an increase in the risk of human diseases by providing ideal 

vector breeding grounds. In addition, the reduction in the utility of water can have social and 

economic impacts due to reduced hydroelectric operations, impeded opportunity for recreational 

activities (e.g., fishing, boating, and swimming), and disruption of water transport (e.g., 

agricultural irrigation), to name a few. As a result, if or when aquatic nuisance animals become 

established and impede the environmental stability and use goals for a body of water, control 

measures will become necessary. 

The requirements in this Part apply to pesticide discharges associated with management 

of aquatic nuisance animals including, but not limited to, fish, lampreys, and mollusks. Aquatic 

nuisance animal control includes management of nuisance species in waters of the U.S. including 

but not limited to lakes, ponds, rivers, estuaries, and streams. As a part of an aquatic nuisance 

animal control program, a pest management strategy should consider mechanical, biological, and 

chemical controls. Details for identifying aquatic nuisance animals and developing a pest 

management strategy can be found online through the Aquatic Nuisance Species Taskforce 

(http://www.anstaskforce.gov/default.php). 

Fish

Reasons for applications of piscicides in waters of the U.S. for controlling nuisance 

species of fish may include, but are not limited to, restoration of threatened and endangered 

species; fish population management; restoration of native species; and aquaculture. A pest 

management strategy for fish should consider mechanical, biological, and chemical controls. 

Lampreys

There are approximately 40 species of lamprey, which are aquatic vertebrates. The sea 

lamprey is an example of a problematic non-native parasitic species that feeds on native fish 

species in U.S. waters. Lampreys may be managed using lampricides that are applied directly to 

the waters of the U.S. Several effective management techniques such as mechanical and 

biological methods are available for lamprey control in addition to lampricides and should be 

considered when developing a pest management strategy. 

Mollusks

Nuisance mollusks including, but not limited to, zebra and quagga mussels, may cause 

damage to freshwater ecosystems, degrade drinking water, clog water-intake/discharge pipes for 

utilities and industries, and negatively impact commercial and recreational activities. Use of 

Deleted: a 

Deleted: Applications
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

63 

molluscicides is one of several methods of control for these aquatic nuisance animals; however, 

it is important to consider the impacts of mechanical, biological, and/or chemical pesticide use 

for control of mussels and other aquatic nuisance mollusk species. 

Other Aquatic Nuisance Animals

There may be aquatic nuisance animals of concern in addition to fish, lampreys, and 

mollusks. Control of other aquatic animals including, but not limited to, crustaceans found to be 

a nuisance and requiring management with mechanical, biological, and/or chemical pesticides 

are included in the requirements in Part 2.2.3. 

 The appropriate type of control for aquatic nuisance animals is dictated by the biology of 

the target species and by environmental conditions and concerns for a specific area. "Control" 

means, as appropriate, eradicating, suppressing, reducing, or managing invasive species 

populations, preventing spread of aquatic nuisance animals from areas where they are present, 

and taking steps such as restoration of native species and habitats to reduce the effects of aquatic 

nuisance animals and to prevent further invasions. [Source: 

www.invasivespeciesinfo.gov/laws/execorder.shtml#sec1] Numerous strategies are used to 

reduce the impact of aquatic nuisance animals, but a pest management strategy should be the 

basis for any pest control program. This is a comprehensive approach for managing pest 

populations using a variety of control methods. 

Aquatic Nuisance Animal IPM Practices

Identify the Problem

Part 2.2.3.1: Prior to the first pesticide application covered under this permit 

that will result in a discharge to waters of the U.S., and at least once each calendar year 

thereafter prior to the first pesticide application for that calendar year, you must do the 

following for each pest management area, as defined in Appendix A. Operators must 

identify the pest problem in their pest management area prior to the first application covered 

under this permit. Knowledge of the pest problem is an important step to developing pest 

management strategies. Re-evaluation of the pest problem is also important to ensure pest 

management strategies are still applicable. Operators must identify the pest problem at least 

once each calendar year prior to the first application for that calendar year

 Identify areas with aquatic nuisance animal problems and characterize the 

extent of the problems, including, for example, water use goals not attained (e.g. wildlife 

habitat, fisheries, vegetation, and recreation). Operators must be well-acquainted with the 

unique regional conditions of their sites and available methods for controlling the pest species 

present. Intended use goals for the water bodies that are being impeded because of nuisance pest 

infestation must also be considered based on the control site. 

 The use of the best available mapping information to aid in identifying the problem areas 

is suggested. Mapping may include aerial photo assessments, topographic maps, and satellite 

imagery where available and/or practicable. Mapping can be essential to identify problem areas 

which can and cannot be controlled using non-pesticide preventative measures (e.g., mechanical 

control). Mapping can also be used in plotting the regional distribution of desired aquatic 

Deleted: animals 

Deleted: These are 

Deleted: es
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

64 

species, as well as water use goals and complaints or reports of aquatic nuisance animals from 

the public. 

Identify target aquatic nuisance animal species. Positive identification of the aquatic 

nuisance animal is required because many species within the same genus may require different 

levels and types of control measures. Aquatic nuisance animal identification is important when 

determining the best pest management strategy for each particular species and for determining 

application areas. Operators must develop a detailed pest management strategy based on 

identification of the targeted pest species which occur in their area. 

 Identify possible factors causing or contributing to the problem (e.g., nutrients, 

invasive species). While there may not be reasonable means to control and/or stop the 

introduction and occurrence of some nuisance species infestations, the identification of possible 

sources (e.g., outflows from other water systems/bodies) may help in minimizing the need for 

control measures. Potential factors which could lead to establishment of aquatic nuisance animal 

populations such as accidental or intentional introduction of exotic species must be identified 

before control measures are implemented. 

 Establish past or present aquatic nuisance animal densities to serve as action 

threshold(s) for implementing pest management strategies. An action threshold should be 

established before implementing a pest management strategy. Any data and/or information 

regarding pest densities can serve as an action threshold. 

 In the event there are no data for your pest management area in the past calendar 

year, see Part 5 for documentation requirements regarding why current data are not 

available and the data you used to meet the permit conditions in Part 2.2.3.1. Operators 

may use historical data or neighboring district data to identify the species and establish action 

thresholds. 

Pest Management

Part 2.2.3.2: Prior to the first pesticide application covered under this permit that 

will result in a discharge to waters of the U.S., and at least once each year thereafter prior 

to the first pesticide application during that calendar year, you must select and implement, 

for each pest management area, efficient and effective means of pest management that 

minimize discharges resulting from application of pesticides to control aquatic nuisance 

animals. In developing these pest management strategies, you must evaluate the following 

management options, considering impact to water quality, impact to non-target organisms, 

pest resistance, feasibility, and cost effectiveness: No action; Prevention; 

Mechanical/physical methods; Biological control agents; and Pesticides.

Operators are required to evaluate and implement a pest management strategy to minimize 

pesticide discharge into waters of the U.S. prior to the first pesticide application covered under 

this permit. As noted above, combinations of various management methods are frequently the 

most effective control strategies over the long term. The goal should be to emphasize long-term 

control rather than a temporary fix. Operators must reevaluate every year prior to the first 

pesticide application for that calendar year. All control measures must be conducted in a manner 

that minimizes impacts to non-target species. The following describes the management options 

that must be evaluated. 

Deleted: Parts 

Deleted: and 7 

Deleted: any 

Deleted: or record keeping 

Deleted: of
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

65 

No Action

 No action is to be taken, although an aquatic nuisance animal problem has been 

identified. This may be appropriate in cases where, for example, available control methods may 

cause secondary or non-target impacts that are not justified or no available controls exist. 

Prevention

Preventing introductions of possible nuisance species is the most efficient way to reduce 

the threat of aquatic nuisance animals (ANS Task Force, 2009). Identifying primary pathways of 

introduction and actions to cut off those pathways is essential to prevention. Through a better 

understanding of the transportation and introduction of aquatic nuisance animals, private entities 

(aquaculturists) and the public have the necessary knowledge to assist in local aquatic nuisance 

animal control by reducing conditions that encourage the spread of aquatic nuisance animals in 

their immediate surroundings. For example, recreational water users provide a pathway of 

unintentional introductions. Increasing public awareness of aquatic nuisance species, their 

impacts, and what individuals can do to prevent their introduction and spread is critical for 

prevention. Other examples of prevention include: better design of water holding sites, better 

management and maintenance of potential problem sites, and volunteer removal of pest species 

(e.g., fishing). Monitoring and detection also play important roles in the prevention of the spread 

and introduction of aquatic nuisance animals. 

Mechanical and Biological Control 

Mechanical and biological controls will be the appropriate methods in some cases, or a 

part of a combination of methods. Mechanical control techniques will vary depending on the 

pest. Examples include fishing, dewatering, netting, electrofishing, pressure washing, use of 

electric fences and abrasive scrubbing. 

 Biological control of aquatic nuisance animals may be achieved through the introduction 

of diseases, predators, or parasites. While biological control generally has limited application for 

control of aquatic nuisance animals, operators should fully consider this option in evaluating pest 

management options. 

Cultural Method 

 Cultural controls require altering the habitat such that it is unsuitable for the aquatic 

nuisance animals. This is an unlikely method of control for aquatic nuisance animal control. 

Pesticide 

 Chemical and biological pesticides such as lampricides, molluscides, and piscicides, are 

registered for use to control aquatic nuisance animals. These pesticides are specifically 

formulated for use in water where aquatic nuisance animals occur. In some cases, pesticide use 

may impact non-target species. As described below, once the determination is made to use 

pesticides, additional requirements must be met.

Deleted: of control method 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

66 

Pesticide Use 

Conduct surveillance prior to each application to assess the pest management area 

and to determine when the action threshold is met that necessitates the need for pest 

management. Often, each aquatic nuisance animal and pest management area warrants a 

different IPM plan, tailored to the regional conditions. The IPM practices should consist of 

combinations of mechanical, biological, and/or pesticidal control methods. All control measures 

must be conducted in a manner that minimizes impacts to non-target species. 

Operators must apply chemical pesticides only after considering the alternatives and 

determining those alternatives not to be appropriate control measures. In some instances, the 

need for chemical pesticide use in and adjacent to the affected habitat can be reduced or virtually 

eliminated with proper execution of alternative strategies and proper best management practices. 

If pesticides are used, they must only be used as needed as determined by an action threshold, 

and proper best management practices must be adopted, including use of the minimum effective 

application rate. Also, the operator must conduct surveillance (e.g., pest counts or area survey) 

prior to application of pesticides to determine when the action threshold is met that necessitates 

the need for pest control measures. 

Surveillance may include the relatively sophisticated transect method used in ecological 

studies to evaluate species distribution, or it may consist of simply conducting visual 

observations in the treated area to verify the eradication or reduction in populations of aquatic 

nuisance animals following pesticide application (Getsinger et al. 2005, pp 23-25). 

Reduce the impact on the environment and non-target organisms by evaluating site 

restrictions, application timing, and application method in addition to applying the 

pesticide only when the action threshold has been met. Aquatic nuisance animal species and 

site restrictions (water use, water movement, etc.) must be identified when choosing an 

appropriate pesticide. Environmental factors such as temperature as well as biological factors 

such as migration timing should be considered when deciding on application timing. Partial site 

treatments over time may be considered to minimize risk to non-target organisms. 

Pesticide application must be limited to the appropriate amount required to control the target 

pests. Methods used in applying pesticides must minimize the impact to non-target species. 

Recommended Aquatic Nuisance Animal Control References 

EPA recommends the following sources for additional information on IPMs and BMPs 

for ANS control: 

Aquatic Nuisance Species Taskforce. Online: http://www.anstaskforce.gov/default.php. 

Aquatic Plant Management, Best Management Practices in Support of Fish and Wildlife Habitat. 

January 2005. Aquatic Ecosystem Restoration Foundation. Project Leader Kurt Getsinger, 

(http://cenapa.ucdavis.edu/files/54815.pdf) 

Deleted: necessitate

Deleted: Each

Deleted: often 

Deleted: tailored 

Deleted: an

Deleted: and

Deleted: content, 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

67 

2.2.4 Forest Canopy Pest Control 

Background

The forest canopy is the uppermost level of the forest. It is composed of mature treetops, 

or the crowns of the mature trees. It provides habitat for animals and plants, some of whom live 

their entire lives in the canopy. Pests that threaten the health of the forest canopy must be 

controlled to maintain forest health. Forest canopy pest control programs are designed to integrate 

environment-friendly control measures (e.g., sterile insect release, pheromone trapping, mating 

disruption, etc.) to reduce losses and pesticide use. But pesticide applications may aerially 

blanket large tracts of terrain to control an entire population of pests within a delimited geographic 

area 

Forest canopy pest control programs included in this permit are treetop pesticide 

applications that may inadvertently expose waters of the U.S. to direct, but limited, pesticide 

application. Forest canopy pest control can be directed at a variety of pests, but primarily 

insects. Forest canopy pest control programs are utilized to prevent habitat elimination/ 

modification, economic losses (e.g., habitat aesthetics, tree losses), quarantine pest outbreaks, 

and eradicate or prevent the spread of introduced invasive species. Therefore, forest canopy pest 

management programs provide environmental, economic, and quality of life benefits in the U.S. 

The type of forest canopy pest control is dictated by the biology of the target pest and by 

environmental conditions and concerns for a specific area. Forest canopy pest control programs 

are primarily conducted at the state and federal level but may also be conducted at the 

local/community level. 

This permit requires IPM programs to incorporate, but not be limited to, the following 

components: problem identification, mapping/planning, pest survey, cultural control, biological 

control, chemical control, and education. 

Forest Canopy Pest Control IPM Practices

Identify the Problem 

Part 2.2.4.1: Prior to the first pesticide application covered under this permit that 

will result in a discharge to waters of the U.S., and at least once each calendar year 

thereafter prior to the first pesticide application in that calendar year, you must do the 

following for each pest management area, as defined in Appendix A. In order to reduce 

pesticide discharge into waters of the U.S. associated with forest canopy pest control, it is 

important for operators to ensure proper problem identification. Problem identification is 

determined through pest identification, delineation of the extent and range of the pest problem, 

determination of the potential for pest problem expansion, and assessing the economic impact of 

failure to provide pest control. 

Establish target pest densities to serve as action threshold(s) for implementing pest 

management strategies. Operators must develop action thresholds for the target pests prior to 

first pesticide application covered under this permit. The action thresholds must be re-evaluated 

at least once each calendar year. As noted in the general discussion above, an action threshold is 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

68 

a point at which pest populations or environmental conditions indicate that pest control action 

must be taken. Action thresholds help determine both the need for control actions and the proper 

timing of such actions. It is a predetermined pest level that is deemed to be unacceptable. 

Identify target species to develop a species-specific pest management strategy based 

on developmental and behavioral considerations for each species. Pest identification is a key 

activity for implementation of a forest canopy pest control system. Pest identification should 

only be conducted by personnel with adequate training and experience with the pests. While 

numerous similar pests (insects and/or pathogens) may be present in any given location, only a 

few of the representative species may constitute a threat which requires control activities. 

Through proper pest identification informed control decisions can be made based on the 

development biology of the pest (susceptible development stage), pest mobility (potential rate of 

spread), timing of selected control measures, applicable control techniques, and most effective 

chemical pesticides for the target species (insecticide class, resistance, etc.). Failure to identify 

pests can lead to unwarranted control activities and/or the need for chemical application with 

potential for discharge into waters of the U.S. Control for each specific pest is also predicated on 

the status of the pest as native recurring, quarantine restricted, or designated as an invasive 

species. 

Identify current distribution of the target pest and assess potential distribution in 

the absence of control measures. Control activities are warranted only after exact pest 

identification and delineation of the extent of the pest infestation. As forest canopy pest control 

can involve treating large expanses of forests, mapping is also an important component in 

identification of the problem. The distribution of the pest, usually insects, within the area of 

infestation can impact the selection of treatment activities. In addition, mapping of the pest 

infestation will allow evaluation of the actual/potential spread of the infestation (e.g., pest 

biology, pest mobility, and host availability) and also serve as a tool to evaluate the effectiveness 

of the control activities. Mapping can also provide essential information for assessment of 

economic damages that can result from the current and potential pest infestation and failure to 

control the pest. Management decisions can thereby be based on cost/benefit evaluations based 

on the current and potential distribution of any pest. 

The third component of problem identification is to determine the potential economic 

impact of not controlling the pest. By establishing economic thresholds, it is possible to 

determine pest density action thresholds which warrant control activities. However, control 

decisions must take into account not only the projected economic impact of the current pest 

infestation but also the potential of the pest infestation to spread. Therefore, control decisions 

based on economic impact must in turn rely on proper pest identification, pest biology, and 

current and potential pest distribution. 

 In the event there are no data for your pest management area in the past calendar 

year, see Part 5 for documentation requirements regarding why current data are not 

available and the data you used to meet the permit conditions in Part 2.2.4.1. Operators 

may use historical data or neighboring district data to identify the species and establish action 

thresholds. 

Deleted: to 

Deleted: designation

Deleted: of 

Deleted: also 

Deleted: Parts 

Deleted: and 7 

Deleted: any

Deleted: or record keeping 

Deleted: of
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

69 

Pest Management 

Part 2.2.4.2: Prior to the first pesticide application covered under this permit that 

will result in a discharge to waters of the U.S., and at least once each calendar year 

thereafter prior to the first pesticide application for that calendar year, you must select and 

implement for each pest management area efficient and effective means of pest 

management that minimize discharges resulting from application of pesticides to control 

forestry pests. In developing these pest management strategies, you must evaluate the 

following management options considering impact to water quality, impact to non-target 

organisms, pest resistance, feasibility, and cost effectiveness: No action; Prevention; 

Mechanical/physical methods; Cultural methods; Biological control agents; and Pesticides. 

Pest control activities in forest canopy management programs may be warranted following 

problem identification and based solely on pest occurrence (e.g., quarantine pest, invasive 

species). However, in many instances control activities may only be necessary based on pest 

population distribution and/or pest densities. To minimize the need for pest control while also 

producing the best control results, a pest management strategy appropriate for the specific 

problem site(s) must be developed. A site-specific management plan will consider biotic (e.g., 

plant and animal species community structure) and abiotic (e.g., environmental) factors. 

Combinations of various management methods are frequently the most effective pest 

management strategies over the long term. The goal of a pest management strategy in forest 

canopy pest control should be to emphasize long-term control rather than a temporary fix. 

 All control measures must be conducted in a manner that minimizes impacts to non-target 

species. The following is a discussion of the relevant management options as they might be 

implemented for forest canopy pest control. 

No Action

 No action is to be taken, although a forest canopy pest control problem has been 

identified. This may be appropriate in cases where available control methods may cause 

secondary or non-target impacts or where aesthetic/ economic losses are not anticipated. 

 

Mechanical and Biological Control 

Mechanical and biological controls will be the appropriate method in some cases, or a 

part of a combination of methods. In some instances, the need for chemical pesticide use in and 

adjacent to the affected habitat can be reduced or virtually eliminated with proper execution of 

alternative strategies and proper best management practices. 

Mechanical control techniques will vary depending on the pest. An example of 

mechanical control in a forest canopy would be egg mass removal (gypsy moth). 

Biological control of forest canopy pests may be achieved through the 

introduction/enhancement of diseases, predators, or parasites. In addition, forest canopy pest 

control programs aimed specifically at insects may also utilize sterile insect release, mating 

disruption, and biological pesticides. While biological controls generally have limited 

applications for forest canopy pest control programs, they should be fully considered as an 

Deleted: of control method 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

70 

option in the development of an IPM plan. The latter two control approaches are often utilized 

when controlling for gypsy moth. 

Cultural Method 

Cultural control methods are strategies that make the habitat unsuitable for a pest. An 

example of a cultural method to manage pests of the forest canopy would be to select a different 

species of tree to plant, or to plant resistant varieties of trees. Maintaining the trees in good 

health to discourage pests is another method of cultural control. 

Pesticide 

Several chemical and biological pesticides are available that may be used to reduce 

defoliation of the trees. These pesticides are typically used when pest populations are high and 

the action threshold has been reached. These products are aerially applied. As described below, 

once the determination is made to use pesticides, additional requirements must be met. 

Pesticide Use 

Conduct surveillance prior to each application to assess the pest management area 

and to determine when a pest action threshold is met that necessitates the need for pest 

management. Operators must apply pesticides only as needed as determined by pre-established 

criteria and pest action thresholds. Operators must establish a pest action threshold that warrants 

pesticide application based on problem identification and pest surveillance. In order to establish 

pest densities and determine when pest action thresholds have been met, forest canopy pest 

control programs must include pest surveillance activities as an integral component of pest 

management strategies. Pest surveillance is necessary to detect the presence (or confirm the 

absence) and magnitude of pest populations in a given location and precisely pinpoint zones of 

infestation. Surveillance activities will vary according to the pest (insect, weed, or pathogen) but 

in general should include observations of pest numbers, developmental stage of the current 

infestation, and biotic factors which would enhance development/expansion of pest populations 

(e.g., weather, crowding, predators, pathogens, etc.). 

Pest surveillance will vary according to pest type and species. For insect pests, 

surveillance activities may include, but not be limited to, pheromone traps, sticky traps, light 

traps, defoliation monitoring. In some cases, traps used in surveillance activities have been 

developed to the extent that they alone provide adequate control of the targeted pest, thus 

eliminating the need for pesticide completely. Conversely, in the instance of quarantine pests or 

invasive species, pest identification alone may suffice to fulfill surveillance requirements and 

indicate need for control measures. Regardless, surveillance should take in to account local 

environmental conditions and projected environmental conditions which would support 

development and/or spread of the pest population and which would limit the choice or 

effectiveness of control activities. 

It is also important to continue surveillance following control activities to assess 

treatment efficacy and to monitor for new pests. Surveillance can determine if the current 

techniques are effective and whether additional control measures are required, particularly 

pesticide application. Based on follow-up surveillance activity, operators can make informed 

Deleted: programs

Deleted: necessitate

Deleted: However
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

71 

decisions which serve to increase the effectiveness of their control programs and minimize the 

potential for pesticide discharge to waters of the U.S. Surveillance is necessary not only to 

establish the species presence and their abundance but also as an evaluation tool of the 

effectiveness of chemical control activities. Furthermore, surveillance should be used as an 

indicator of the need for additional chemical control activities based on pre-established criteria 

related to population densities in local areas. 

Assess environmental conditions (e.g. temperature, precipitation, and wind speed) in 

the treatment area to identify conditions that support target pest development and are 

conducive for treatment activities. Operator may use insecticides as dictated by the pest. 

Although pesticide formulations and applications vary according to pest and habitat, the focus 

here is on aerial applications of chemical/biological sprays. Aerial application is considered the 

preferred application method for large areas and areas that are inaccessible for ground 

application. In order to prevent poor site coverage, a guidance system (GPS), where 

economically feasible, or site flagging are necessary to increase accuracy of the treatment 

coverage while minimizing the amount of pesticides being applied. 

Before using a pesticide, the forest canopy pest control operator should consider the 

following points; 1) do not apply a pesticide in unfavorable environmental conditions (e.g., 

windy, rainy, etc.) with increased potential for drift and wash off/runoff, 2) choose an application 

method and a pesticide formulation that will minimize the potential for movement of the material 

to off-site locations, 3) restrict or minimize the use of volatile pesticides on areas in or around 

sensitive on-target plants or animals, especially during hot weather, 4) generally, liquid 

pesticides applied by broadcast methods are more subject to drift than are granular formulations 

and their application methods, 5) during liquid application, spray droplet size should be 

maintained within the recommended range for the proposed target and the application method to 

be used, and 6) use additives to minimize drift and enhance efficacy as appropriate. 

Reduce the impact on the environment and non-target organisms by evaluating the 

restrictions, application timing, and application methods in addition to applying the 

pesticide only when the action thresholds have been met. Forest canopy pest species and site 

restrictions (water use, water movement, etc.) must be identified when choosing an appropriate 

pesticide. For instance with gypsy moth control a biological insecticide, Bacillus thuringiensis 

kurstaki, is usually selected. However, if endangered or threatened butterfly or moth species are 

in the area, a viral insecticide that specifically targets gypsy moth larvae will be selected. 

Environmental factors such as temperature, as well as biological factors such as migration timing 

should be considered when deciding on application timing. Partial site treatments over time may 

be considered to minimize risk to non-target organisms. Pesticide application must be limited to 

the appropriate amount required to control the target pests. Methods used in applying pesticides 

must minimize the impact to non-target species. 

 Evaluate using pesticides against the most susceptible developmental stage. For 

forest canopy pests, pesticides should be selected that target the most susceptible life stage. For 

instance, with gypsy moths, the larvae are present in the canopy, are soft-bodied, and therefore 

are the target of chemical controls. 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

72 

Recommended Forest Canopy Pest Control Reference 

EPA recommends the following source for additional information on IPM’s and BMP’s 

for forest canopy pest control: 

Emily Grafton and Ralph Webb. Homeowner's guide to gypsy moth management. West 

Virginia University Extension Service. 

http://www.nj.gov/agriculture/divisions/pi/pdf/GMguide.pdf 

3. WATER-QUALITY-BASED EFFLUENT LIMITATIONS 

The CWA requires NPDES permits to include technology-based effluent limitations for 

all discharges and then if necessary for a specific discharge, water quality based effluent 

limitations (WQBELs). Permit writers are to assess whether the technology-based effluent 

limitations are protective of water quality standards and if not, permit writers must also include 

WQBELs as necessary to ensure that the discharge will not cause, have the reasonable potential 

to cause, or contribute to an excursion above any state water quality standard, including state 

narrative criteria for water quality (see 40 CFR 122.44(d)). In developing WQBELs; permit 

writers must consider the potential impact of every proposed surface water discharge on the 

quality of the receiving water. Unlike individual permits that include requirements tailored to 

site-specific considerations, general permits, while tailored to specific industrial processes or 

types of discharges (e.g., from the application of pesticides), often do not contain site-specific 

WQBELs. Instead, in general, EPA includes a narrative statement that addresses WQBELs. In 

this permit the WQBEL is as follows: 

Your discharge must be controlled as necessary to meet applicable numeric and narrative 

state, territory, or tribal water quality standards.

If at any time you become aware, or EPA determines, that your discharge causes or 

contributes to an excursion of applicable water quality standards, you must take corrective 

action as required in Part 6.

The first sentence includes the general requirement to control discharges as necessary to 

meet water quality standards, while the second sentence implements this requirement in more 

specific terms by imposing on operators a responsibility to take corrective action in response to 

an excursion of applicable water quality standards, whether discovered by EPA or by the 

permittee. Failure to take such corrective action is a violation of the permit. Additionally, the 

permit includes a provision, in Part 1.2.3, that specifies that EPA may determine that additional 

technology-based and/or water quality-based effluent limitations are necessary, or may deny 

coverage under this permit and require submission of an application for an individual NPDES 

permit, as detailed in Part 1.3. 

Each permittee is required to control its discharge as necessary to meet applicable water 

quality standards. In general, EPA expects that compliance with the other conditions in this 

permit (e.g., the technology-based limitations, corrective actions, etc.) will result in discharges 

that are controlled as necessary to meet applicable water quality standards based on the 

cumulative effect of the following factors, which are described in more detail below: 

Deleted: Any

Deleted: that causes or contributes to 

an excursion of any 

Deleted: or 

Deleted: , or federally-promulgated

Deleted: standard is prohibited and is a 

violation of this permit. 

Deleted: 3 of the permit also

Deleted: additional language that 

notifies

Deleted: of their 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

73 

(1) Under FIFRA, EPA evaluates risk associated with pesticides and mitigates unreasonable 

ecological risk. Compliance with FIFRA is assumed. (See Part III.1.5 of this fact sheet.) 

(2) EPA evaluated national–scale ambient monitoring data, as well as the frequency of the 

identification of specific pesticides as the cause of water impairments, to assess whether 

pesticide residues are currently present in waters at levels that would exceed water 

quality standards. The monitoring data show that, in most samples, most pesticides were 

below ambient water quality criteria or benchmarks developed by EPA’s Office of 

Pesticide Programs (OPP) as indicators of narrative water quality criteria. For the small 

number of pesticides found in monitoring data to be present above such benchmarks, the 

evaluation, as summarized in Appendices B and C of this fact sheet, also documents risk 

mitigation actions taken by EPA (such as cancellation of pesticide uses) that EPA expects 

have reduced the levels of those pesticides in water. 

(3) Technology-based effluent limitations in the PGP provide further protections beyond 

compliance with existing FIFRA requirements. 

(4) Biological pesticides discharged to waters, by regulatory definition, do not work through 

a toxic mode of action. For chemical pesticides, the discharges covered under this permit 

are the residues after the pesticide has performed its intended purpose. Thus, the residue 

will be no higher than, and in many instances, lower than, the concentration of the 

pesticide as applied. 

(5) The PGP excludes pesticide applications that result in discharges of any pesticide to (1) 

waters impaired for that pesticide or (2) any Tier 3 waters (i.e., outstanding national 

resource waters). 

In addition to the five factors identified above, before issuance, EPA permits require 

CWA §401 certification by states and tribes. The states and tribes review the permit and certify 

that it will meet their water quality standards. States and tribes can, in this process, add further 

conditions to ensure that water quality standards will be met. Part 10 of the permit is reserved 

for any additional conditions so required by any state or tribe in areas where this permit is 

available. 

This permit requires permittees to control discharges as necessary to meet applicable 

water quality standards. When the permittee or EPA determines a discharge will cause or 

contribute to an excursion above any WQS, including failure to protect and maintain existing 

designated uses of receiving waters, the permittee must take corrective action to ensure that the 

situation is eliminated and will not be repeated in the future. (See Part 6.0). If additional control 

measures are required, EPA expects the operator to vigilantly and in good-faith follow and 

document, as applicable, the process for BMP selection, installation, implementation and 

maintenance, and cooperate to eliminate the identified problem within the timeframe stipulated 

in Part 6.0 of the PGP. 

(1) Under FIFRA, EPA evaluates risk associated with pesticides and mitigates 

unreasonable ecological risk

Background 

EPA regulates the use of pesticides under the Federal Insecticide, Fungicide, and 

Rodenticide Act (FIFRA). In general, FIFRA authorizes EPA to register each pesticide product 

Deleted: to ensure that all discharges 

will be adequately controlled or they will 

be in violation of the permit. ¶

¶

Additionally, when
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

74 

intended for distribution or sale in the U.S. To register a pesticide, the Agency must determine 

that its use in accordance with the label will not cause “unreasonable adverse effects on the 

environment.” (see, e.g., FIFRA sec. 3(c)(5)). FIFRA defines that term to mean, in part, “any 

unreasonable risk to man or the environment, taking into account the economic, social, and 

environmental costs and benefits of the use of any pesticide” (FIFRA sec. 2(bb)). The 

“unreasonable adverse effects” standard requires EPA, in effect, to balance the human health and 

ecological risks of using a pesticide against its economic, social, human health, and ecological 

benefits. Pesticides are registered for sale and distribution only if EPA determines that the 

benefits outweigh the risks. In making decisions on whether to register a pesticide, EPA 

considers the use directions on proposed product labeling and evaluates data on product 

chemistry, human health, ecological effects, and environmental fate to assess the potential risks 

associated with the use(s) proposed by the applicants for registration and expressed on the 

labeling. Among other things, the Agency evaluates the risks to human health and the 

environment (including water quality) posed by the use of the pesticide.

As stated above, EPA reviews and approves pesticide product labeling. EPA implements 

risk mitigation measures identified through the risk assessment process by placing use 

restrictions and warnings on labeling to ensure the use of the pesticide (under actual use 

circumstances and commonly accepted practice) will not cause any “unreasonable adverse 

effects on the environment.” It is a violation under FIFRA sec. 12(a)(2)(G) (FIFRA’s “misuse” 

provision) to use a registered pesticide inconsistent with its labeling. 

After a pesticide has been registered, changes in science, public policy, and pesticide use 

practices will occur over time. FIFRA, as amended by the Food Quality Protection Act of 1996, 

mandates a registration review program, under which the Agency periodically reevaluates 

pesticides to make sure that as the ability to assess risk evolves and as policies and practices 

change, all registered pesticides continue to meet the statutory standard of no unreasonable 

adverse effects to human health or the environment. The Agency is implementing the 

registration review program pursuant to Section 3(g) of FIFRA and will review each registered 

pesticide every 15 years to determine whether it continues to meet the FIFRA standard for 

registration. Information on this program is provided at: 

http://www.epa.gov/oppsrrd1/registration_review/. 

Ecological Risk Assessment 

The following is a discussion about the FIFRA risk assessment process with a focus on 

Ecological (specifically aquatic) Assessments. Persons seeking pesticide registrations bear the 

burden of demonstrating their products meet the statutory standard under FIFRA. As set forth in 

40 CFR Part 158, applicants for pesticide registrations must provide EPA with a suite of product 

chemistry, residue chemistry, toxicity, environmental fate, and ecotoxicity studies to support an 

application for registration. To support outdoor uses, studies are required that provide 

information related to the environmental fate and transport of the chemical and that measure the 

acute and chronic toxicity to terrestrial and aquatic organisms. These studies, along with open 

literature that meet data quality guidelines, are the basis for the ecological risk assessments. The 

ecological risk assessment combines the results of an environmental exposure assessment and an 

ecological effect assessment for a pesticide active ingredient to produce a quantitative measure 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

75 

of potential risk.10 A risk characterization is also presented to put the quantitative assessment of 

risk in the context of other lines of evidence, such as available monitoring data and incident 

reports, and to discuss uncertainties in the risk assessment. The quantitative and qualitative 

determination of potential ecological risk is independent of economic or other benefit 

considerations. 

Aquatic Exposure 

EPA estimates pesticide concentrations in aquatic environments to determine if exposure 

to a pesticide active ingredient is at a level that could cause unreasonable adverse effects to 

aquatic organisms. EPA estimates pesticide concentrations in water using peer-reviewed 

simulation modeling because there are not sufficient monitoring data to estimate exposure to 

aquatic organisms under all potential use conditions. When available, monitoring data are used 

to help characterize aquatic exposure. 

 EPA also estimates potential exposure from uses involving direct application to water. 

The model used for pesticides applied directly to water uses environmental fate data to simulate 

partitioning of the pesticide between the water column and bottom sediment in a standard rice 

paddy. This modeling is conservative because it does not simulate degradation of the applied 

pesticide, as would be necessary to estimate the amount of residue remaining after the pesticide 

product had performed its intended function. Depending on the rate of degradation, the initial 

concentration as estimated by the model could be much higher than the residual concentration 

remaining after treatment has been completed. Additionally, this modeling scenario is 

conservative because the resulting exposure estimate is the concentration in the paddy water 

itself, not taking into account dilution which would occur when paddy water is diluted by 

precipitation or when it is released into a receiving water body. 

 As discussed above, when available, EPA uses ambient water monitoring data as a line of 

evidence to characterize aquatic exposure in ecological and human health risk assessments. The 

U.S. Geological Survey (USGS) maintains several sources of pesticide monitoring data. These 

sources include the National Water Quality Assessment program (NAWQA), the Toxic 

Substances Hydrology Program, and the National Stream Quality Accounting Network 

(NASQAN). EPA sources of water monitoring data include STORET, a storage and retrieval 

database of national water quality information, the Safe Drinking Water Information System 

(SDWIS), Office of Water compliance monitoring data, and the USGS/EPA Reservoir 

Monitoring Program. In addition to the federal data sources, monitoring data are sometimes 

available from States, pesticide registrants, and the open literature. 

 These monitoring data are evaluated on a case-by-case basis to help characterize the 

likelihood, extent, and nature of pesticide concentration in water under current use practices and 

actual field conditions. EPA considers the locations and frequency of sampling, the analytical 

methods, and detection limits when determining how such data will be incorporated into the risk 

assessment. The usefulness of monitoring for an aquatic exposure assessment is tied to the 

purpose of the monitoring studies from which the data are derived. For example, a monitoring 

study targeted to measure concentrations of a pesticide in a watershed with high agricultural use 

 10 As part of the risk assessment, EPA also examines available information to determine the need to expand 

beyond the focus on the active ingredient to consider pesticide formulation, inert ingredients, or degradates. 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

76 

of that pesticide will not provide much insight on the potential exposure from its use as a 

mosquito adulticide. Similarly, a general survey of ambient water quality might not necessarily 

target specific pesticide use areas or the time of year when pesticide concentrations may be at 

their peak, and for this reason may not provide a reliable estimate of acute exposure. However, 

if monitoring data from such a study shows higher confirmed detections than estimated by 

modeling, the higher monitoring values typically would be used in the risk assessment. 

 

 In sum, EPA’s screening level exposure estimates from simulation models are 

conservative, consistent with their intended use as a screen to identify pesticide use scenarios 

that do not pose a risk of concern, both because of the selected inputs used to generate them and 

the values from the model outputs that are selected for risk assessment. When ambient aquatic 

monitoring data are available for a given pesticide, monitored concentrations are usually lower 

than modeled concentrations and in many cases substantially lower. The next section describes 

the second portion of the risk assessment: effects. 

Aquatic Effects 

To determine if a pesticide is sufficiently toxic at its estimated exposure concentrations to cause 

unreasonable adverse effects in the environment, EPA reviews available ecotoxicity data. These 

data may come from a number of sources, including direct guideline study submissions required 

in support of registration, and open literature data retrieved through ECOTOX11. The typical 

assessment endpoints for pesticide ecological risk assessments are reduced survival from direct 

acute exposures and survival, growth, and reproductive impairment from direct chronic 

exposures. As noted in the OPP Overview12 document, which describes the process OPP uses to 

conduct ecological risk assessment, OPP evaluates other data on sublethal effects in addition to 

direct effects on survival, growth and reproduction. 

In general, the current data regulations require studies that include but are not limited to a 

suite of aquatic toxicity studies for effects characterization. These test requirements are defined 

for each chemical class by use category (40 CFR Part 158 Subpart D; Wildlife and Aquatic 

Organism data requirements; http://edocket.access.gpo.gov/cfr_2007/julqtr/40cfr158.490.htm) 

and are performed on a limited number of laboratory test organisms in the following broad 

taxonomic groupings. 

• Freshwater fish, 

• Freshwater invertebrates, 

• Estuarine/marine fish, 

• Estuarine/marine invertebrates, and 

• Algae and aquatic plants. 

 11 U.S. EPA. 2007. Ecotoxicity Database (ECOTOX) Mid-Continent Ecology Division, National Health 

and Environmental Effects Research Laboratory. U.S. Environmental Protection Agency, Office of Research and 

Development. http://cfpub.epa.gov/ecotox/. 12 U.S. EPA. 2004. Overview of the Ecological Risk Assessment Process in the Office of Pesticide 

Programs. Office of Prevention, Pesticides, and Toxic Substances. Office of Pesticide Programs. Washington, 

D.C. January 23, 2004. Support Document 1: Study Classification used by EFED in Data Evaluation Records 

(DERs) http://www.epa.gov/oppfead1/endanger/consultation/ecorisk-overview.pdf
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

77 

Within each of these very broad taxonomic groups, the most sensitive acute and chronic 

toxicity value is selected from the all available test data, including open literature and registrant 

submissions. If additional toxicity data for more species of organisms in a particular group are 

available, the most sensitive toxicity values from all sources for other species/studies that meet 

data quality standards are used in the risk assessment13. Aquatic toxicity data are required for 

each active ingredient, but aquatic toxicity data are also required on the typical end use product 

for any pesticide that will be introduced directly to aquatic environments (40 CFR Part 158.630). 

Risk Characterization 

 Risk characterization is the integration of effects and exposure characterization to 

determine the ecological risk from the use of the pesticide and the likelihood of effects on nontarget species based on the pesticide-use scenarios. In screening-level assessments, OPP relies 

on the deterministic risk quotient (RQ) method to compare estimated exposure to toxicity 

endpoints. Estimated environmental concentrations (EECs) derived in the exposure 

characterization are divided by acute and chronic toxicity endpoints identified in the effects 

characterization. Risk quotients are then compared to the Agency’s Levels of Concern (LOCs). 

These LOCs are the Agency’s interpretative policy and are used to analyze the potential risk to 

non-target organisms and the need to consider regulatory action. These criteria are used to 

indicate when a pesticide use as directed on the label has the potential to cause adverse effects on 

non-target organisms. If a risk of concern is identified, risk mitigation measures are considered. 

 

Risk Mitigation 

 EPA acknowledges that there are uncertainties in its pesticide risk assessments (see full 

discussion below), nonetheless the Agency reduces the risks of concern by imposing additional 

restrictions on the use of a pesticide to reduce pesticide concentrations in the aquatic 

environment. Mitigation measures may include limits on the amount and frequency that a 

pesticide may be applied, or the application methods may be restricted to limit off-site transport. 

Mitigation may also limit the geographical areas to which a pesticide can be applied or may 

include mandatory buffer distances from sensitive habitats. Mitigation measures are 

implemented through product labeling instructions, with which pesticide users are required to 

comply. 

 In some cases, EPA restricts the use of a pesticide so that levels of pesticide predicted by 

the model to reach water are below the relevant aquatic benchmarks (see Aquatic Bencharmks 

discussion below). In other cases, using the FIFRA risk-benefit balancing standard, EPA may 

permit the use of a pesticide even though estimated water concentration might exceed a relevant 

benchmark. In such cases, the decision incorporates consideration of the benefits of the pesticide 

use and other lines of evidence, such as any available National Recommended Water Quality 

Criterion for ambient water quality, concerning the conservativeness of the modeling assessment 

and available monitoring data. 

 

13 Ibid U.S. EPA 2004 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

78 

Uncertainties with Risk Assessment and Mitigation 

 For the majority of pesticides, the Agency relies on simulation modeling to predict 

potential aquatic exposure following pesticide applications. There are uncertainties embedded in 

the exposure assessment, for example, the extent to which the simulated scenario represents 

actual use conditions in terms of hydrologic vulnerability and the amount and frequency with 

which pesticides are applied. In order to account for the inherent uncertainty the Agency uses a 

combination of parameters and assumptions in the models that results in estimated potential 

exposure concentrations that are high-end and are not likely to underestimate actual aquatic 

exposure. This allows the Agency to screen out pesticides that are not likely to pose a risk to 

aquatic life. 

 In the effects characterization under FIFRA, the lowest acute and chronic toxicity values 

from the most sensitive species tested in acceptable studies are used as the relevant endpoint for 

evaluating risk to various taxa. Implicit in the use of the lowest toxicity values for the most 

sensitive species is the presumption that these toxicity values afford protection not only for the 

individual surrogate species but for other untested taxa as well. The extent to which the most 

sensitive laboratory test species are representative of the sensitivities of naturally occurring 

aquatic species to pesticides is uncertain. 

 

 In the FIFRA risk characterization, data gaps are also considered as a source of 

uncertainty in the risk assessment conclusions, and each risk assessment discusses the potential 

for additional data to affect the risk assessment conclusions. 

An additional source of uncertainty in assessing risk to aquatic life is the impacts of 

multiple stressors on aquatic organisms. A United States Geological Survey (USGS) 10-year 

study (Gilliom et al., 2006) shows that the most common form of pesticide exposure for aquatic 

organisms is simultaneous exposure to multiple pesticides. More than 50 percent of all stream 

samples contained five or more pesticides, although the majority of mixtures are comprised 

mainly of agricultural herbicides and their degradates, or urban/residential use insecticides in 

urban streams. Pesticides that will be applied under the PGP may also co-occur with other 

manmade contaminants and/or other pesticides from other uses. For instance, the USGS has also 

performed monitoring studies which revealed the widespread presence of some pharmaceuticals 

and personal care products in drinking water. However, although pesticides may be detected 

with other chemicals or in discharges covered by other NPDES permits, the majority of research 

and data on the effects of pesticides has focused on individual pesticides. 

Possible interactions among pesticides or between pesticides and other contaminants may 

occur including: independent, additive, antagonistic or synergistic. The variety of chemical 

interactions presented in the available literature suggests that the interaction can be a function of 

many factors including but not necessarily limited to: (1) the exposed species, (2) the cocontaminants in the mixture, (3) the ratio of concentrations in the mixture, (4) differences in the 

pattern and duration of exposure among contaminants, and (5) the differential effects of other 

physical/chemical characteristics of the receiving waters (e.g., organic matter present in sediment 

and suspended water). Quantitatively predicting the combined effects of all these variables on 

mixture toxicity to any given taxon with confidence is beyond the capabilities of the available 

data. In order to assess the impacts of environmental mixtures on aquatic life, states have 

included ambient toxicity testing (also called Whole Effluent Toxicity or WET testing) in their 

Deleted: re is some uncertainty of the

Deleted: even 

Deleted: with 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

79 

monitoring programs. WET testing allows states to identify potential impacts to aquatic life and 

identify the toxicant(s) and through the toxicity reduction evaluation, reduce the source(s) of the 

toxicant(s). The level of toxic effect to the most sensitive tested species is therefore assumed to 

be protective of other species that may be present in any given water body and is assumed to 

represent the most toxic component of a mixture. Note that a discussion of EPA’s consideration 

of WET testing as a condition of the permit is discussed in Part III.4 of the fact sheet. 

Aquatic Benchmarks 

EPA’s Office of Pesticide Programs (OPP) derives aquatic benchmarks by multiplying 

the most sensitive toxicity values (i.e., the lowest acceptable toxicity value for the most sensitive 

species within a taxonomic group) by their respective (level of concern) LOC. These taxonspecific benchmarks, based on toxicity data used by OPP in assessments for pesticide registration 

decision-making, are considered estimates of the concentrations below which pesticides are not 

expected to have the potential for adverse effects for the particular taxon for which those data 

serve as surrogates. It is reasonable to assume that above these levels, there is potential for the 

pesticide to cause adverse effects to the given taxon. 

 EPA’s Office of Water (OW) and OPP agreed that these values can be used by States 

and others to evaluate potential risks of pesticides in the aquatic environment, if a National 

Recommended Water Quality Criterion for ambient water quality is not available.14 A number 

of States have used these benchmark values as indicators of whether pesticide residues detected 

in surface water warrant additional action such as refined monitoring efforts. While benchmarks 

can be useful as a screening tool, they do not provide the information necessary to link detected 

concentrations with their sources. 

 In response to recommendations and input from stakeholders, EPA developed a webpage 

of non-regulatory “OPP Aquatic Benchmarks.”15

As described above, EPA’s FIFRA risk assessment process includes a number of 

conservative assumptions that taken as a whole mitigate unreasonable ecological risk and protect

water quality. 

(2) Examination of national–scale ambient monitoring data to assess whether pesticide 

residues are currently present in waters at levels that would exceed water quality 

standards.

U.S. Geological Survey: The Quality of Our Nation’s Waters – Pesticides in the Nation’s 

Streams and Ground Water, 1992-2001. 

In addition to the protective nature of the pesticide risk assessment, EPA reviewed readily 

available surface-water monitoring data. In 2006, the USGS National Water-Quality Assessment 

Program (NAWQA)16 released a 10-year (1992-2001) study of 51 major river basins and aquifer 

 14 Correspondence to SFIREG, November 3, 2006 from Office of Water director. 

15 OPP Aquatic Benchmark Table http://www.epa.gov/oppefed1/ecorisk_ders/aquatic_life_benchmark.htm 16 Gilliom and others 2006. The Quality of Our Nation’s Waters-Pesticides in the Nation’s Streams and 

Ground Water, 1992-2001: U.S. Geological Survey Circular 1291, 172p. 

Deleted: interim measures

Deleted: are sufficient to 

Deleted: in terms of resources to refine

Deleted: As a screening tool, use of 

these

Deleted: ; however, benchmarks

Deleted: concentations

Deleted: aquatic toxicity 

Deleted: including protection of
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

80 

systems that account for more than 70 percent of total U.S. water use and more than 50 percent 

of the U.S. drinking water supply. Most NAWQA samples were analyzed for 75 pesticides and 

eight degradation products, including 20 of the 25 most commonly used herbicides and 16 of the 

25 most commonly used insecticides. Water samples were collected at 186 stream sites for 

analysis of pesticides and degradates dissolved in water. The samples were collected from 

streams throughout the year, including high-flow and low-flow conditions. Sampling was most 

intensive during the time of highest pesticide use and runoff – generally weekly or twice monthly 

for a 4- to 9-month period. As a general matter, the USGS uses sampling and analytic methods 

that provide highly reliable data. The NAWQA database stands out among available data 

sources in terms of the number of pesticides and sites examined, as well as the overall number of 

samples collected and analyzed. 

Overall results. Overall, the 10-year assessment indicates that for the pesticides sampled, surface 

and ground water are generally not being adversely affected by pesticide applications for 

irrigation, drinking water, and home/recreational uses. The USGS analytical methods are very 

sensitive and are designed to detect and measure minute amounts – in some cases parts per 

trillion – that are often 10 to 100 times lower than benchmarks or water quality criteria for most 

pesticides. There were detections of pesticides in these samples, but the concentrations detected 

were generally low (parts per billion and parts per trillion). The NAWQA data generally reflect 

pesticides that were used in watersheds from which water samples were taken. There were also 

some detections of legacy pesticides that were no longer registered at the time of sampling. 

For environmental effects, the USGS compared the concentrations found in the NAWQA 

sampling with two general types of aquatic life benchmarks (1) ambient water quality criteria 

(AWQC) for the pesticide and (2) benchmarks derived from the lowest acute and chronic 

ecological effects endpoint for the pesticide (OPP benchmarks). Acute AWQC and all acute 

OPP benchmarks were compared with each measured concentration for the most complete year 

of data for each NAWQA stream. Chronic AWQC were compared with 4-day moving average 

concentrations, chronic OPP benchmarks for invertebrates were compared to 21-day moving 

average concentrations, and chronic fish OPP benchmarks were compared to 60-day moving 

average concentrations. AWQC were available for 7 of the 83 pesticides and degradates 

analyzed by NAWQA. One or more OPP benchmarks were available for 60 of the 83 NAWQA 

analytes, including 5 of the 7 that had AWQC. A total of 62 of the pesticide compounds 

analyzed in water by NAWQA had one or more aquatic-life benchmarks. 

A total of 20 pesticides or degradates exceeded an EPA benchmark in one or more 

agricultural streams and/or urban streams (see Appendix A of fact sheet for a complete list of 

pesticides/degradates that had exceedances). In agricultural streams, most concentrations 

greater than a benchmark involved chlorpyrifos, azinphos-methyl, atrazine, p,p’-DDE and 

alachlor. In urban streams most concentrations greater than a benchmark involved diazinon, 

chlorpyrifos, and malathion. It should be noted that pesticide concentrations in agricultural 

streams most often originate from terrestrial agricultural activities exempted under the CWA 

from NPDES permit requirements or activities not covered under this permit. 

Since 2001, the last year of sampling covered by the NAWQA report, EPA has taken 

regulatory action against all 20 pesticides found to be in excess of a benchmark and many of 

their uses have been canceled (several detections were of pesticides no longer in use prior to the 

start of the study). For atrazine, the registrant has been required to undertake an aggressive and 

Deleted: moving 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

81 

innovative ecological monitoring program to protect vulnerable watersheds in areas of atrazine 

use, and to develop mitigation measures for watersheds that might have atrazine detections above 

levels of concern. Residential uses of the two pesticides most commonly detected above a 

benchmark (diazinon and chlorpyrifos) have been canceled. Additional detail on the nature of 

EPA’s regulatory actions under FIFRA appears in Appendices B and C of the fact sheet. 

 

State Water Quality Monitoring under CWA 

Every two years States must identify waterbodies that are not attaining water quality 

standards (WQS; both narrative and numeric) under CWA Section 303(d). States must place 

waterbodies not meeting water quality standards on a list (303(d) list) which identifies the 

pollutant or pollutants causing or expected to cause the impairment. The Office of Water’s 

Impaired Waters and Total Maximum Daily Loads website17 (accessed November 2009) 

indicates 303(d) impairments in several states for 14 currently registered specific pesticides and 

3 general classes of pesticides (e.g., pyrethoids; Table 1). With the adoption of a 303 list, States 

are required to develop a Total Maximum Daily Load (TMDL). States also must include a 

priority ranking for developing those TMDLs. A critical component in the TMDL process is to 

identify the sources of each parameter for which the waterbody is listed. Then, the State must 

develop waste load allocation(s) for point source(s) and load allocation(s) for nonpoint source(s). 

Table 1. Currently registered pesticides listed as causes of 303(d) impairment (data accessed 

November 2009). 

Cause of Impairment States 

2-Methylnaphthalene CA, NH, WA 

Acrolein OR 

Atrazine AL, IA, IL, KS, LA, MO, NE, OH, OR 

Azinphos-methyl CA, OR 

Carbaryl OR 

Carbofuran CA, LA, OR 

Chlorpyrifos AL, CA, OK, OR, WA 

Dacthal CA 

Diazinon CA, OK, OR, WA 

Dibutyl phthalate OR, WA 

Dimethyl phthalate OR, WA 

Diuron OR 

Endosulfan AL, CA, MT, OR, WA 

Fipronil LA 

Malathion CA, OR 

Methyl parathion AL, CA, LA 

Naphthalene NH, OR, WA 

Prometon OR 

Pronamide OR 

Simazine OR 

Terbacil OR 

Tributyltin VA 

 17 http://iaspub.epa.gov/waters10/attains_nation_cy.control?p_report_type=T

Deleted: the 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

82 

Cause of Impairment States 

Trifluralin OR 

Xylenes CA 

Organophosphates CA 

“Pesticides” – listed generically as such CA, IN, MA, NY, OH, OR, PA, PR 

Pyrethroids CA 

According to the Office of Water’s Impaired Waters and Total Maximum Daily Loads 

website there are a total of 75,677 causes of impairments for 303(d) listed waters18. Of these, 

approximately 2% (a total of 1,798) are listed as pesticides. The majority (77% or 1,386 of the 

1,798) of impairments attributed to pesticides are for those no longer registered for use by the 

EPA. While 23% (412 of the 1,798) of impairments attributed to pesticides are for currently 

registered pesticides, including impairments listed generically for “pesticides“ (83 of the 1,798). 

This accounts for 0.5% (412 of 75,677) of the total causes of impairments for 303(d) listed 

waters nationally. However, it is important to note that many States do not routinely monitor for 

many currently registered pesticides which is a source of uncertainty for this assessment. 

Additionally, 3,266 impairments are listed for “impaired biota” and 1,259 impairments are for an 

“unknown” cause, which together account for about 6% of all impairments. 

EPA has received ambient monitoring data for pesticides present in waters that are 

attributable to the pesticide use patterns covered under this permit from states and other 

stakeholders. A list of these data sources is included in the administrative record for this permit 

(see docket number EPA-HQ-OW-2010-0257). EPA is still in the process of evaluating these 

data in more detail, but in general, these data do not show the presence of pesticides in 

concentrations above levels of concern (i.e., recommended water quality criteria – available at 

http://epa.gov/waterscience/criteria/wqctable/ or FIFRA benchmark levels – available at 

http://www.epa.gov/oppefed1/ecorisk_ders/aquatic_life_benchmark.htm). 

2004 National Water Quality Inventory Report 

States, tribes and territories are required to report biennially on the water quality of 

navigable waters in their boundaries, and the extent to which these waters support designated 

uses, under Section 305(b) of the Clean Water Act. In its report to Congress on the 2004 

reporting cycle19, which was submitted in January 2009, the Agency reported the results on the 

portion of Waters of the U.S. evaluated during that cycle. The report indicated that 44% of river 

miles assessed, 64% of lake acres assessed, and 30% of the square miles of estuaries assessed 

were impaired for failing to support at least one designated use. 

While pesticides are not always monitored when assessing water quality, the Report to 

Congress indicated that pesticides were not among the most common causes of impairments in 

the 2004 cycle for rivers and streams, nor for lakes, ponds and reservoirs. Pesticides were the 

sixth leading cause of impairments for bays and estuaries, but the Report did not indicate 

whether these were caused by actively registered pesticides, or by sediment contamination by 

persistent legacy pesticides, which account for the majority of water impairments caused by 

 18 http://iaspub.epa.gov/waters10/attains_nation_cy.control?p_report_type=T 19 http://www.epa.gov/owow/305b/2004report/

Deleted: this includes

Deleted: which 

Deleted: for which the presence of 

these pesticides
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

83 

pesticides nationwide. The Report does not indicate whether any impairments identified by the 

States were caused by uses that will be subject to NPDES permits under the CWA. 

Interpretation of Monitoring Data Relevant to the PGP 

When re-evaluating the registrations of existing pesticides, the Agency considers 

available surface-water monitoring data as a line of evidence regarding potential aquatic risk in 

addition to considering exposure estimates derived from simulation models. Such monitoring 

data can provide a measure of trends in aquatic exposure associated with mitigation measures 

imposed by the Agency. For instance, the USGS’s 2009 report of Trends of Pesticide 

Concentrations in Corn-belt Streams states, “(t)he declines in pesticide concentrations closely 

followed declines in their annual applications, indicating that reducing pesticide use is an 

effective and reliable strategy for reducing pesticide contamination in streams.” 

Monitoring studies are valuable because they may specifically target areas in which 

pesticides considered in the study are likely to be used. This is an effective way of evaluating 

impact from mitigation measures, or the increase in use of other pesticides that might replace 

pesticides to which mitigation measures are applied. 

The best way to interpret the likely causes of pesticide detections in surface water is to 

consider any detection in light of the design of the monitoring study itself. For instance, the 

USGS’s study The Quality of Our Nation’s Water – Pesticides in the Nation’s Streams and 

Ground Water, 1992-2001, described above, used a targeted approach, focusing on areas of 

relatively homogenous land-use and environmental settings to relate pesticide occurrence to 

individual non-point sources. The sampling was also most intensive during periods of high 

pesticide use and runoff. Such a design can best capture transport of pesticide to surface water 

from runoff from treated agricultural fields (or treated buildings/lawns) in a watershed. But, the 

timing and location of sample collection may not be as effective in capturing residues of 

pesticides applied for purposes covered under the General Permit. Concentrations detected could 

at times reflect such uses, but the design of the study was meant to capture more diffuse nonpoint transport of pesticides in watersheds, and not point source discharge. 

Uncertainties with Monitoring Data 

The Agency recognizes that monitoring of pesticide levels in water has limitations in its 

ability to identify whether use of specific pesticides may adversely affect water quality. The 

product monitoring data give only a “snap shot” of the concentration in a particular waterbody at 

a particular time. While the USGS (Gilliom et al., 2006) intensified the frequency of its 

monitoring during times of the year when most agricultural pesticide usage commonly occurred, 

their sampling did not necessarily account for timing of specific pesticide applications, frequency 

of applications, and meteorological events that can cause pesticides to reach surface water as 

covered by this permit. Thus, monitoring may not collect a sample when pesticide concentrations 

are at peak levels or when present in the water. Moreover, if monitoring detects the presence of 

a pesticide, the data usually do not identify the source or if the pesticide residue is actually still a 

product serving its intended purpose. Ambient monitoring cannot determine whether the 

contamination was due to lawful use (and if so, which one) or unlawful pesticide use, an 

accidental spill or discharge, or whether the residues detected were from runoff, or from aquatic 

Deleted: of

Deleted: caused by

Deleted: (described above) which 

Deleted: in 

Deleted: Details in the National-Scale 

Ambient Water Quality Monitoring 

Section above indicate both the effect 

regulation under FIFRA has on potential 

transport of pesticides to surface water, 

but also the Agency’s response to 

detections in water found in a monitoring 

program like NAWQA. ¶

Deleted: Agency does not have data 

that clearly shows when the

Deleted: Monitoring 

Deleted: of residue 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

84 

uses such as those to be included in the NPDES general permit. Monitoring data are often 

difficult to interpret because the ancillary data on pesticide usage in a basin, and factors that 

could make the location more or less vulnerable are often not available. 

(3) Technology-based effluent limitations in the PGP provide further protections beyond 

compliance with existing FIFRA requirements. 

EPA expects the proposed general permit contains requirements necessary to ensure that 

water quality is protected. For example, the operators that apply pesticides over the annual 

treatment area threshold must implement IPM control measures under Part 2.2. As stated above, 

EPA expects that the technology-based effluent limitations are as stringent as necessary to meet 

WQS. These effluent limitations require permittees to minimize the discharge of pesticides 

through the use of the most efficient and effective means of pest management options, including 

pesticide and non-pesticide methods. The technology-based effluent limitations require 

applicators to: use the lowest effective amount of pesticide product per application and optimum 

number of applications to control the target pest, perform regular maintenance activities on 

pesticide containers and application equipment, and calibrate equipment. There are other 

requirements to consider human health and ecological impact, pest resistance, feasibility, and 

cost effectiveness and include prevention, mechanical/physical methods, cultural methods, 

biological control agents, and as a final resort, the application of pesticides. To ensure that 

pesticide discharges are minimized, permittees identified under Part 2.2 must identify target pest 

species and areas where those pests occur, identify the possible sources of the problem, and 

establish action thresholds for implementing pest management strategies. The technology-based 

effluent limitations also require permittees identified under Part 2.2 to conduct surveillance prior 

to each pesticide application to assess the treatment area and to determine when pest action 

thresholds are met. 

The general permit includes several other provisions that the Agency expects to provide 

further protections beyond compliance with FIFRA requirements. For one, Part 4 of the permit 

requires these operators to monitor pesticide applications activities to minimize discharges and 

during any post-application monitoring to determine effectiveness of the pesticide treatment. In 

addition, Part 6.0 of the general permit contains requirements for all permittees to document and 

report adverse incidents involving non-target organisms or the environment, and to take 

corrective action if it is determined that revising control measures can help to prevent future 

incidents. An adverse incident report calls due attention to a situation in which water quality 

may be impacted by pesticide use and may indicate that corrective action is required to ensure 

that water quality standards are further protected during future applications. The permit also 

requires permittees to take corrective actions to eliminate other situations such as unauthorized 

releases (i.e., spills or leaks) or the failure to meet applicable water quality standards. These 

requirements are discussed further in Part 6.0 of this fact sheet. EPA expects this approach will 

further reduce discharges of pesticides to waters of the U.S. from the use patterns covered under 

this permit. 

 

Deleted: ¶

¶

Finally, the
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

85 

(4) Biological pesticides do not work through a toxic mode of action. For chemical 

pesticides, the discharges covered under this permit are the residues after the pesticide has 

performed its intended purpose. 

This permit provides coverage for point source discharges from certain applications of 

pesticides, as identified in Part 1.1.1 of the PGP. Discharges from the application of both 

chemical and biological pesticides are covered under this PGP consistent with the Sixth Circuit 

Court’s reading of the CWA term “pollutant” in National Cotton Council v. EPA. 

For chemical or conventional pesticides applied directly to waters (e.g., for aquatic weed 

control and aquatic nuisance pest control), it is the pesticide residue, including excess pesticide 

that is present outside of the treatment area or within the treatment area once the target pests 

have been controlled that is considered a pollutant under this permit. For any pesticide applied 

over water (e.g., mosquito control), any pesticide or pesticide residue that is incidentally 

deposited in waters of the U.S. is considered a pollutant since the intended purpose of the 

application is to target pests above the water. Therefore, the concentrations of “pollutants” will 

be no higher, and in many instances significantly lower, than the product concentrations 

considered in EPA’s assessment when registering these products. 

Discharges of biological pesticides require permit coverage regardless of whether or not a 

residue exists. Biological pesticides or biopesticides are certain types of pesticides derived from 

such natural materials as animals, plants, bacteria, and certain minerals. Two classes of 

biopesticides are relevant to this permit, microbial pesticides and biochemical pesticides. 

Microbial pesticides consist of a microorganism (e.g., a bacterium, fungus, virus or protozoan) as 

the active ingredient. The most widely used microbial pesticides are subspecies and strains of 

Bacillus thuringiensis, or Bt. Biochemical pesticides, as defined at 40 CFR 158.2000(a), are 

naturally occurring substances that control pests by non-toxic mechanisms. Biochemical 

pesticides include substances, such as insect sex pheromones that interfere with mating, as well 

as naturally-occurring repellants and attractants. 

Biopesticides are usually inherently less toxic than conventional pesticides and generally 

only affect the target pests and closely related organisms. Often, they are effective in very small 

quantities and decompose quickly thereby resulting in lower exposures and largely avoiding the 

pollution problems caused by chemical pesticides. When used as a component of Integrated Pest 

Management (IPM) programs, biopesticides can greatly decrease the use of chemical pesticides; 

however, use of biopesticides effectively requires users to have a very good understanding of 

pest management. Since biochemical pesticides, by regulatory definition, do not work through a 

toxic mode of action they may be less likely to result in an excursion of a water quality standard. 

(5) The PGP excludes pesticide applications that result in discharges of any pesticide to (1) 

waters impaired for that pesticide or (2) any Tier 3 waters (i.e., outstanding national 

resource waters).

EPA identified two scenarios where it believes the PGP may not be adequately protective 

of water quality standards and has excluded those discharges from coverage under this permit. 

Namely, the PGP excludes from coverage: (1) discharges to impaired waters from the application 

of pesticides when that waterbody is impaired for that specific pesticide or its degradates and (2) 

Deleted: when 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

86 

discharges to Tier 3 Waters (i.e., Outstanding National Resource Waters). Any operator desiring 

to discharge in either of these two scenarios is required to submit an application for an individual 

permit. Note that the PGP does cover situations where a waterbody may be impaired generically 

for “pesticides,” though EPA is requesting comment on this issue. EPA will post on its website a 

list of Tier 3 waterbodies in the areas of the country where this permit applies. 

4. Site Monitoring 

 Monitoring is required in any NPDES permit specifically for the purpose of 

demonstrating compliance with the permit conditions. There are a variety of monitoring 

methods that a “traditional” NPDES permit may require, including end-of-pipe monitoring to 

show compliance with relevant effluent limitations prior to discharging to a receiving waterbody. 

Monitoring may also pertain to actions taken to ensure that record keeping or other permit 

control activities are being properly implemented. Water quality monitoring of receiving 

streams is not typically required in NPDES permits unless it is required to determine among 

other things, compliance with mixing zone dilution standards or some other special permit 

condition. 

 Pursuant to CWA section 308 and 402(a)(2), 40 CFR 122.43(a), and other applicable 

implementing regulations, the following requirements have been included in the permit, as 

discussed below. The monitoring requirements of this permit are narrative and demonstrate 

compliance with permit conditions by using currently established pesticide use routines for 

monitoring pest control. For instance, the permit requires routine visual inspections (described 

below) to be conducted as part of the pest treatment activity or as part of post-application pest 

surveillance, and calls for records of the pesticide discharge volume to be kept. The monitoring 

requirements of the permit are reasonable measures of good pest management practice that the 

conscientious operator should be currently employing to ensure environmental health and safety 

and optimal control of pest organisms. 

Monitoring of pesticide discharges poses several challenges not generally encountered in 

“traditional” NPDES permitting situations. For example, there is no “wastewater discharge” per 

se from pesticide applications that is analogous to end-of-pipe discharges. A manufacturing 

plant would, for example, typically direct its wastewater through a treatment system to remove 

pollutants, and then would direct the effluent through a pipe into a receiving waterbody. 

However, for chemical pesticide applications, at the time of application the pesticide contains 

both the portion serving its intended purpose as well as the potential residual for which 

monitoring data would be appropriate. Thus, monitoring the “outfall” in this case would merely 

provide data on the amount of the product as applied (information already known through the 

FIFRA registration process) and would not be useful for comparing with any type of effluent 

limitation or water quality standard. 

 EPA considered requiring ambient water quality monitoring. However EPA determined 

that it was infeasible for the following reasons: 

1) Uncertainty: Ambient water quality monitoring would generally not be able to distinguish 

whether the results were from the pesticide application for which monitoring is being performed, 

or some other upstream source. 

Deleted: .” Also, see EPA’s

Deleted: water quality 

Deleted: of 

Deleted: are 

Deleted: the discharge of pesticide 

product 

Deleted: it is applied (e.g., released 

from

Deleted: nozzle) for purposes of 

controlling pests, is not yet considered a 

“pollutant” except for any contained
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

87 

2) Lack of applicable measurable standards: Pesticide-specific water quality standards do not 

exist at this time for the vast majority of constituents in the products authorized for use under this 

PGP. 

3) Safety and Accessibility: Pesticides, particularly those used for mosquito control and forestry 

pest control, are often applied over waterbodies in remote areas, hazardous terrain, and swamps 

that are either inaccessible or pose safety risks for the collection of samples. 

4) Difficulty of residue sampling for chemical pesticides: For chemical pesticides, the 

“pollutant” regulated by the PGP is the residue that remains after the pesticide has completed its 

activity, and it is this residue that would be the subject of any water quality monitoring 

requirement. However, the point at which only “residue” remains is not practically discernable 

at this time for all pesticides. 

5) Usefulness of data: Some states have questioned the value of ambient water quality 

monitoring data obtained from state permitting programs. The data generally showed that water 

quality impacts were not occurring, and one state even discontinued the requirement in revisions 

of its state permit. 

Given the questionable ability of ambient water quality data to demonstrate permit compliance, 

EPA has determined that there are suitable alternative monitoring activities to determine permit 

compliance, other than ambient water quality monitoring, for this permit. 

Additionally, in assessing the appropriateness of requiring ambient water quality 

monitoring, EPA also considered Whole Effluent Toxicity (WET) testing as a possible option for 

assessing operator compliance with permit conditions; however, WET testing in an NPDES 

permit program is best used to monitor whether an operator’s discharge is toxic and not whether 

a receiving stream (i.e., the ambient environment), that may be influenced by a number of 

different discharges from different operators and different sources is toxic. In addition, WET 

testing would not indicate the actual source of the toxicity. If a waterbody is found to be toxic or 

to contain pollutants above water quality standards, it can be quite complex to identify the source 

of the toxicity, which may or may not actually be the NPDES permittee performing the 

monitoring. 

 Thus, the monitoring program that EPA has developed for this PGP has been tailored to 

accommodate the unique situations related to pesticide applications. Visual monitoring is 

required in the PGP to determine if any pesticide use practices may need to be revised to ensure 

that avoidable adverse impacts to the environment do not occur (See Section 4.2 of fact sheet). 

Monitoring records required by those operators who submit NOIs will establish a history that 

may indicate if or when practices need to be reconsidered. 

4.1 Monitoring Requirements for all Permittees 

All permittees must monitor the amount of pesticide used to ensure that the lowest 

amount needed to effectively control the pest is balanced with the potential for development of 

pesticide resistance. EPA understands that appropriate application rates are variable depending 

on conditions, and expects permittees to use their best professional judgment in combination 

with the label requirements in determining the appropriate amount of product needed to optimize 

Deleted: purposes

Deleted: collecting 

Deleted: their

Deleted: Furthermore, once there is a 

pollutant (biological pesticide or residue 

of a chemical pesticide), their 

combination with other stressors in the 

ambient environment can affect water 

quality, any one of which may be the 

cause of an exceedance of a water quality 

standard or of a finding of a toxic WET 

testing result. 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

88 

efficacy of the treatment. EPA expects that should a pest be eradicated or marginalized, no 

further discharge to control that pest should occur unless it is absolutely necessary for the 

continued control of that pest. All permittees must also monitor their operation to ensure the 

integrity of application equipment by calibrating, cleaning, and repairing equipment on a regular 

basis to reduce the potential for leaks, spills, and unintended/accidental release of pesticides to 

waters of the U.S. 

4.2 Visual Monitoring Requirements 

Visual monitoring assessments are required as a means of identifying, for example, 

instances of detrimental impact to non-target organisms, disruption or degradation of wildlife 

habitat, or the prevention of designated recreational or municipal uses of a waterbody that may 

possibly be related to the operator’s use of pesticides in a given area. Visual monitoring will 

consist of spot checks in the area to and around which pesticides are applied for possible and 

observable adverse incidents, such as fish kills and/or distressed fish or macro-invertebrates. 

Visual monitoring assessments are also required during the pesticide application when 

feasibility and safety allow. Visual monitoring is not required during the course of treatment 

when that treatment is performed in darkness as it would be infeasible for the inspector to note 

adverse effects under these circumstances. Additionally, the following scenarios often preclude 

visual monitoring during pesticide application: 

1. Applications made from an aircraft 

2. Applications made from a moving road vehicle when the applicator is the driver 

3. Applications made from moving watercraft when the applicator is the driver 

4. Applications made from a moving off-road wheeled or tracked vehicle when the 

applicator is the driver. 

A visual monitoring assessment must also be conducted during any post-application 

surveillance to determine the efficacy of the pesticide treatment. Visual monitoring of this type 

is only required if the operator performs post application surveillance in the normal course of 

business. EPA expects that visual assessments may reasonably be conducted during applications 

and efficacy inspections may be conducted on foot or from a stationary vehicle. 

5. Pesticide Discharge Management Plan (PDMP) 

Part 5 of this permit requires any operator who is subject to Part 2.2 of this permit (i.e., 

one who is required to submit an NOI) to develop a Pesticide Discharge Management Plan 

(PDMP). Operators who know or should have reasonably known prior to commencement of 

discharge, that they will exceed an annual treatment area threshold identified in Part 1.2.2 for 

that year, must develop a PDMP prior to first pesticide application covered under this permit.. 

Operators who do not know or would reasonably not know until after commencement of 

discharge, that they will exceed an annual treatment area threshold identified in Part 1.2.2 for 

that year , must develop a PDMP prior to exceeding the annual treatment area threshold.. 

Operators commencing discharge in response to a declared pest emergency situation as defined 

in Appendix A, that will cause the operator to exceed an annual treatment area threshold, must 

develop a PDMP no later than 90 days after responding to the declared pest emergency. Once 

the operator meets the requirement to prepare a PDMP, he/she must maintain the plan thereafter 

Deleted: where

Deleted: pest

Deleted: For example, visual

Deleted: as a

Deleted: or

Deleted: operators 

Deleted: are required

Deleted: implement technology-based 

effluent limitations in 

Deleted: those

Deleted: are

Deleted: ) within 90 days of his/her 

determination that he/she has exceed any 

Deleted: . This means the initial 

PDMP must be completed prior to 

submitting an NOI for permit coverage 

unless the operators do not meet the 

annual treatment area threshold until after 

submitting his/her NOI. Once the 

operator meets the 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

89 

for the duration of coverage under this general permit. This means even if the operator’s annual 

treatment area subsequently falls below the annual treatment area threshold, the operator is 

required to keep the plan up-to-date. 

Developing a PDMP helps operators ensure they have (1) taken steps to identify the pest 

problem, (2) evaluated pest management options, and (3) appropriate control measures to control 

pesticide discharges. Operators, who exceed an annual treatment area due to a declared pest 

emergency and thus must submit an NOI, do not need to include activities in their PDMP that 

were conducted in response to that declared pest emergency. Their PDMP, however, must 

address any future pesticide application covered under this permit. Part 5.1 of the permit 

contains the required elements to be documented in the PDMP.

The PDMP itself does not contain effluent limitations; rather it constitutes a tool both to 

assist the operator in documenting what control measures it is implementing to meet the effluent 

limitations, and to assist the permitting/compliance authority in determining whether the effluent 

limitations are being met. A PDMP is a “living” document that requires periodic reviews and 

must be kept up-to-date. Where control measures are modified or replaced to meet effluent 

limitations, such as in response to a Part 6.1 triggering condition, such changes must be 

documented in the PDMP. If operators fail to develop and maintain an up-to-date PDMP, they 

will have violated the permit. This recordkeeping violation is separate and distinct from a 

violation of any of the other substantive requirements in the permit (e.g., effluent limitations, 

corrective action, monitoring, reporting, and state-specific requirements). 

Operators may choose to reference other documents, such as a pre-existing integrated 

pest management (IPM) plan or spill prevention and response plan, in the PDMP rather than 

recreating the same text in the PDMP. It is not required that an operator must have authored the 

pre-existing plan in order to use it. When referencing other documents, the operator is 

responsible for ensuring his/her PDMP and the other documents together contain all the 

necessary elements for a complete PDMP, as specified in Part 5.1. In addition, the operator 

must ensure that a copy of relevant portions of those referenced documents is attached to the 

PDMP and is located on-site and it is available for review consistent with Part 5.3 of the permit. 

5.1. Contents of Your PDMP 

The PDMP prepared under this permit must meet specific requirements under Part 5.1 of 

the permit. Generally, operators must document the following: (1) a pesticide discharge 

management team; (2) a description of the pest management area and the pest problem; (3) a 

description of control measures; (4) schedules and procedures for application rate and frequency, 

pest surveillance, assessment of environmental conditions, spill prevention and response, 

equipment maintenance, adverse incident response, and pesticide monitoring; and (5) any 

eligibility considerations under other federal laws. 

Pesticide Discharge Management Team 

The permit requires that a qualified individual or team of individuals be identified to 

manage pesticide discharge, including the pesticide applicator. If the pesticide applicator has not 

been identified at the time of the plan development, the operator should indicate whether or not a 

for-hire applicator will be used. Identification of a pesticide discharge management team ensures 

Deleted: 

Deleted: operator

Deleted: is 

Deleted: thereafter

Deleted: both 

Deleted: they are 

Deleted: As noted above, to be covered 

under this permit, the initial PDMP must 

be completed prior to submitting an NOI 

for permit coverage unless the operator 

does not meet the annual treatment area 

threshold until after submitting his/her 

NOI. Doing so helps operators ensure 

they have (1) taken steps to identify the 

pest problem, (2) evaluated pest 

management options, and (3) appropriate 

control measures to control pesticide 

discharges. Part 5.1 of the permit 

contains the required elements to be 

documented in the PDMP.¶

¶
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

90 

that appropriate persons (or positions) are identified as necessary for developing and 

implementing the plan. Inclusion of the team in the plan provides notice to staff and 

management (i.e., those responsible for signing and certifying the plan) of the responsibilities of 

certain key staff for following through on compliance with the permit’s conditions and limits. 

 

The pesticide discharge management team is responsible for developing and revising the 

PDMP, implementing and maintaining the control measures to meet effluent limitations, and 

taking corrective action where necessary. Team members should be chosen for their expertise in 

the relevant areas to ensure that all aspects of pest management are considered in developing the 

plan. The PDMP must clearly describe the responsibilities of each team member to ensure that 

each aspect of the PDMP is addressed. EPA expects most operators will have more than one 

individual on the team, except for small entities with relatively simple plans and/or staff 

limitations. The permit requires that team members have ready access to any applicable portions 

of the PDMP and the permit. 

Pest Management Area Description 

The pest management area description includes the pest problem description, action 

threshold(s), a general location map, and water quality standards. 

1. Pest Problem Description. 

The permit requires that the PDMP include a description of the pest problem at the pest 

management area. A detailed pest management area description assists operators in subsequent 

efforts to identify and set priorities for the evaluation and selection of control measures taken to 

meet effluent limitations set forth in Parts 2 and 3 and in identifying necessary changes in pest 

management. The description must include identification of the target pest(s), source of the pest 

problem, and source of data used to identify the problem. The permit allows use of historic data 

or other available data (eg, from another similar site) to identify the problem at your site. If you 

use other site data, you must document in this section why data from your site is not available or 

not taken within the past year and explain why the data is relevant to your site. Additionally, the 

pest management area descriptions should include any sensitive resources in the area, such as 

unique habitat areas, rare or listed species, or other species of concern that may limit pest 

management options. 

2. Action Threshold(s) 

The permit requires that the PDMP include a description of the action threshold(s) 

established for the target pest, including a description of how they were determined. An action 

threshold is a level of pest prevalence at which an operator takes action to reduce the pest 

population. 

3. General Location Map 

The PDMP must also contain a general location map of the site that identifies the 

geographic boundaries of the area to which the plan applies and location of the waters of the U.S. 

To improve readability of the map, some detailed information may be kept as an attachment to 

the site map and pictures may be included as deemed appropriate. 

Deleted: departments

Deleted: existing

Deleted: site 

Deleted: must 

Deleted: the point
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

91 

4. Water Quality Standards 

Operators must identify the water quality standards applicable to their discharge. This 

must include a list of pesticide(s) or any degradates for which the water is impaired. Internet 

links to all state, territory and tribal water quality standards are available at: 

http://epa.gov/waterscience/standards/wqslibrary/. 

Description of Control Measure 

The permit requires that the PDMP include a description of the control measures to 

demonstrate how the operators specifically plan to meet the applicable technology-based or 

water quality-based effluent limitations. The description of the control measures selected to 

meet the effluent limitations must include a brief explanation of the control measures used at the 

site to reduce pesticide discharge, including evaluation and implementation of the six pest 

management tools (no action, prevention, mechanical/physical methods, cultural methods, 

biological control agents, and pesticides). Operators must consider impact to non-target 

organisms, impact to water quality, pest resistance, feasibility, and cost effectiveness when 

evaluating and selecting the most efficient and effective means of pest management to minimize 

pesticide discharge to waters of the U.S. 

All six pest management tools may not be available for a specific use category and/or 

treatment area. However, the PDMP must include documentation of how the six pest 

management tools were evaluated prior to selecting a site specific pest management strategy. 

For the no action option, operators should document the impact of this option without any 

current pest management strategy at the site. For the prevention management option, the 

operator should document the methods implemented to prevent new introductions or the spread 

of the pests to new sites such as identifying routes of invasion and how these can be intercepted 

to reduce the chance of invasion. Prevention may include source reduction, using pathogen-free 

or weed-free seeds or fill; exclusion methods (e.g., barriers) and/or sanitation methods, like wash 

stations, to prevent reintroduction by vehicles, personnel, etc. Some prevention management 

methods may fall under mechanical/physical or cultural methods as well. 

For the pesticide management option, operators must include a list of active ingredient(s) 

evaluated. Discussion should also identify specific equipment or methods that will prevent or 

reduce the risks to non-target organisms and pesticide discharges to waters of the U.S. 

Schedules and Procedures 

a. The following schedules and procedures, used to comply with the effluent limitations in Part 2 

of the permit, must be documented in the PDMP: 

1. Application Rate and Frequency Procedures 

In the PDMP, operators must describe the procedures for determining the lowest effective 

amount of pesticide product per application and the optimum frequency of pesticide applications 

to minimize discharges from the application of pesticide. 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

92 

2. Spill Prevention 

a. Operators must describe the spill prevention program for their pest management area. 

The program should address areas and activities at the site that typically pose a high risk 

for spills including loading and unloading areas, storage areas, process areas, and waste 

disposal activities. It should also address appropriate material handling procedures, 

storage requirements, and containment or diversion equipment that will minimize the 

potential for spills, or in the event of a spill, enable proper and timely response. 

b. As required in Part 6.1 of this permit, any spills or leaks that occur while covered under 

this permit must be documented. 

c. Documenting spills does not relieve operators of any reporting requirements established 

in 40 CFR 110, 40 CFR 117, and 40 CFR 302, or any other statutory requirements 

relating to spills or other releases of oils or hazardous substances. 

3. Pesticide Application Equipment Procedures 

Operators must describe the preventive equipment maintenance program to keep the 

pesticide application equipment in proper operating condition, including how and when the 

following will be addressed: calibration, regular inspections, and cleaning/repairing of the 

application equipment to avoid situations that may result in leaks, spills, and other releases. 

4. Pest Surveillance Procedures 

Operators must discuss how their pest surveillance programs assess the pest treatment 

area, to determine when the action threshold(s) is met. The discussion should also include 

surveillance method(s) selected. 

5. Environmental Conditions Assessment Procedures 

Operators must discuss the procedures and methods to assess environmental conditions in the 

treatment area. 

b. The following additional schedules and procedures necessary to minimize discharges must 

also be documented in the PDMP 

1. Spill Response Procedures 

The PDMP must document procedures for expeditiously stopping, containing, and 

cleaning up leaks, spills, and other release. In addition, the PDMP must include documentation 

of the procedures for notification of appropriate facility personnel, emergency response agencies, 

and regulatory agencies. 

Deleted: , and spill cleanup procedures
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

93 

2. Adverse Incident Response Procedures 

In the PDMP, operators must document appropriate procedures for responding to an 

adverse incident resulting from pesticide applications. Operator must identify and document the 

following: 

• Course of action or responses to any incident resulting from pesticide 

applications; 

• Chain of command notification for the incident, both internal to your 

agency/organization and external; 

• State/Federal contacts with phone numbers; 

• Name, location, and telephone of nearest emergency medical facility; 

• Name, location, and telephone of nearest hazardous chemical responder; and

(including police and fire department).

3. Pesticide Monitoring Schedules and Procedures 

In the PDMP, operators must describe procedures for monitoring consistent with the 

requirements in Part 4.0 including: 

 The process for determining the location and timing of monitoring; 

 A schedule and procedures for monitoring; 

 The person (or position) responsible for conducting monitoring; and 

 Procedures for documenting any observed impacts to non-target organisms 

resulting from your pesticide discharge. 

Signature Requirements 

 The PDMP must be signed and certified in accordance with the signatory requirements in 

the Standard Permit Conditions part of the permit (Appendix B, subsection B.11). This 

requirement is consistent with standard NPDES permit conditions described in 40 CFR 122.22 

and is intended to ensure that the operator understands his/her responsibility to create and 

maintain a complete and accurate PDMP. The signature requirement includes an 

acknowledgment that there are significant penalties for submitting false information. 

5.2 Pesticide Discharge Management Plan Modifications. 

 This permit requires that the PDMP be updated whenever any of the triggering conditions 

for corrective action in Part 6.1 of the permit occur, or when a review following the triggering 

conditions in Part 6.1 requires the operator to revise his/her control measures as necessary to 

meet the effluent limitations in this permit (Part 2). Keeping the PDMP up-to-date will help the 

operator ensure that the condition that triggered the corrective action does not reoccur. 

Operators are also required to review the PDMP at least once a year or whenever necessary to 

update the pest problem description and pest management strategies at the pest management 

area. 

 It is important to note that failure to update the PDMP in accordance with Part 5.2 is a 

recordkeeping violation, not a violation of an effluent limit. For example, if the operator changes 

its maintenance procedures, but fails to update its PDMP to reflect these changes, a 

recordkeeping violation will result. The operator must revise its PDMP to reflect the new 

Deleted: ); and 

Deleted: any 

Deleted: any 

Deleted: its

Deleted: its

Deleted: are
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

94 

maintenance procedures and include documentation of the corrective action (in accordance with 

Part 6) to return to full compliance. 

5.3 Pesticide Discharge Management Plan Availability. 

 This permit requires that a copy of the current PDMP, along with all supporting maps and 

documents, be kept at the address provided on the NOI. The PDMP and all supporting 

documents must be immediately available to representatives of EPA, a State, Tribal, or local 

agency governing pesticide applications, as well as representatives of the U.S. Fish and Wildlife 

Service (USFWS) or the National Marine Fisheries Service (NMFS) at the time of an on-site 

inspection or upon request. This requirement is consistent with standard NPDES permit 

conditions described in 40 CFR 122.41. Part 5.3 of this permit indicates that EPA may provide 

access to portions of your PDMP to a member of the public upon request. Confidential Business 

Information (CBI) may be withheld from the public, but consistent with 40 CFR Part 2, may not 

be withheld from EPA or the Services. 

6.0 Corrective Action 

 The purpose of including corrective action requirements in this permit is to assist this 

new universe of NPDES permittees with effectively meeting technology-based and waterquality-based effluent limitations and implementing integrated pest management practices in this 

permit. Corrective actions in this permit are follow-up actions a permittee must take to assess 

and correct problems. They require review and revision of control measures and pesticide 

application activities, as necessary, to ensure that these problems are eliminated and will not be 

repeated in the future. The permit makes clear that the permittee is expected to assess why a 

specific problem has occurred and document what steps were taken to eliminate the problem. 

EPA believes this approach will help permittees in complying with the requirements of the 

permit quickly. Compliance with many of the permit’s requirements -- for instance, those related 

to reporting and recordkeeping and some of those related to operation and maintenance -- can be 

accomplished immediately, and therefore, are not considered problems that trigger corrective 

actions. 

It should be noted that a situation triggering corrective action is not necessarily a permit 

violation and, as such, may not necessarily trigger a modification of control measures to meet 

effluent limitations. However, failure to conduct (and document) corrective action reviews in 

such cases does constitute a permit violation. 

6.1 Situations Requiring Revision of Control Measures. 

 Permittees are required to review and, as necessary, revise the selection and 

implementation of their control measures to eliminate any of the following situations: 

- an unauthorized release or discharge occurs; 

- the permittee becomes aware, or EPA determines, that control measures are not stringent 

enough for the discharge to meet applicable water quality standards; 

- an inspection or evaluation of your facility by an EPA official, or local, state, or Tribal entity, 

determines that modifications are necessary to meet the non-numeric effluent limits detailed 

in Part 2 of the PGP; or 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

95 

- the permittee observes or is otherwise made aware (e.g., a third party notification) of an 

adverse incident for which symptoms are unusual or unexpected during the normal course of 

treatment. 

 EPA considers the above situations to be of significant concern. Thus, EPA is requiring 

permittees to assess the cause of these situations which may be affiliated with the permittees 

discharge from the application of pesticides and to take any necessary steps to eliminate the 

situation and ensure that the situation will not be repeated in the future. 

 The purpose of Part 6.1 is to ensure compliance with corrective action requirements 

through increased accountability and oversight. EPA views ongoing assessment of control 

measure effectiveness and corrective actions as integral to an effective pesticide management 

program. This corrective action assessment must be kept with the other recordkeeping 

documentation required by this permit. 

6.2. Corrective Action Deadlines. 

The permit requires that corrective action be completed “before the next pesticide 

application that results in a discharge, if practicable, or if not, as soon as practicable thereafter.” 

EPA emphasizes that this timeframe is not a grace period within which an operator is relieved of 

any liability for a permit violation. EPA is adopting this flexible deadline to account for the 

variation in types of responses (e.g., evaluate situation and select, design, install, and implement 

new or modified control measures) that may be necessary to address any identified situations of 

concern. EPA recognizes that in rare cases a corrective action review may identify the need for 

substantial improvements to the permittee’s control measures, and does not want to limit the 

selection and implementation of such controls with an inflexible deadline. Another possibility is 

that EPA or the permittee may determine that further monitoring is needed under Part 6.3 of the 

permit to pinpoint the source of the problem, and this monitoring may need to be conducted 

during future pesticide application activities. However, EPA believes that in the vast majority of 

cases, corrective action reviews will identify responses that can be taken quickly, either before 

the next pesticide application that results in a discharge or shortly thereafter. EPA expects 

operators to document and justify any schedules for selecting, designing, installing, and 

implementing new or modified control measures. 

 When any of the listed situations are identified under 6.1, such as discovery that water 

quality standards are being exceeded, the permittee must take steps to ensure the problems 

causing any violation are eliminated. If the original inadequacy constitutes a permit violation, 

then that violation is not excused by response within the timeframe EPA has allotted for 

corrective action, though EPA may consider this when determining the appropriate enforcement 

response to a violation. EPA assumes that permittees will need less time to make minor repairs 

or change practices than to make substantial operational changes or equipment repair. A 

timeframe, albeit flexible, is included specifically so that problems are not allowed to persist 

indefinitely. Failure to take the necessary corrective action within the stipulated timeframe 

constitutes an additional and independent permit violation. 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

96 

6.3 Effect of Corrective Action 

 The occurrence of a situation described in Part 6.1 may, but does not implicitly, 

constitute a violation of the permit. The occurrence of a situation identified in Part 6.1 does 

require the permittee to immediately review and as necessary, revise the selection and 

implementation of their control measures to eliminate the situation. Part 6.3 explains that taking 

corrective action does not absolve the permittee of any liability for a permit violation requiring 

that action, however, failure to take required corrective action will constitute an original or an 

additional permit violation. EPA will consider the appropriateness and promptness of corrective 

action in determining enforcement responses to permit violations. EPA or a court may impose 

additional requirements and schedules of compliance, including requirements to submit 

additional information concerning the condition(s) triggering corrective action, additional sitespecific water-quality based limitations, additional monitoring requirements, or other schedules 

and requirements more stringent than specified in this permit. Those requirements and schedules 

will supersede those of Part 6.1 if such requirements conflict. 

6.4 Adverse Incident Documentation and Reporting 

Part 6.4 of the PGP requires permittees to take specific actions in response to identified 

adverse incidents which may have resulted from a discharge from the permittee’s pesticide 

application. Namely, permittees are required to provide oral notice to EPA within 24 hours and 

then follow-up with a written report within 5 days of becoming aware of the adverse incident. 

EPA defines an “adverse incident” in Appendix A of the PGP, but generally it is defined as any 

effect of a pesticide’s use that is unexpected or unintended. 

 Part 6.4.1 requires permittees to call the appropriate EPA Incident Reporting Contact 

within 24 hours of any identified adverse incident and provide basic information about it. The 

purpose of this requirement is twofold: (1) to provide an opportunity for the Agency to respond 

to these incidents as soon as reasonably can be expected, and (2) to provide a basis for potential 

corrective actions. EPA does not expect this initial notification to be detailed but merely a 

reporting of the date of the finding, a general discussion of the incident and a review of the 

necessity to conduct corrective action. The permit requires permittees to document the 

information identified in 6.4.1, including the date and time you notified EPA and a description of 

any deviations from 6.4.1 notification requirements based on nuances of the adverse incident. 

For example, a permittee may decide to notify multiple EPA contacts because of the severity of 

the adverse incident. This type of information should be included in the written documentation 

of the 24-hour notification as described below. 

Part 6.4.2 requires permittees to provide a written report of the adverse incident to the 

appropriate EPA Regional office and to the State Lead Agency for pesticide regulation within 5 

days of discovering the adverse incident. The adverse incident report must include the following 

information: 

• Information required to be provided in Part 6.4.1 

• Date and time you contacted EPA notifying the Agency of the adverse incident; 

• Location of incident, including the names of any waters affected and appearance of 

those waters (sheen, color, clarity, etc.) 

Deleted: 3

Deleted: Permittees to 

Deleted: an acknowledgement

Deleted: and 

Deleted: findings
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

97 

• A description of the circumstances of the incident including species affected, number 

of individual and approximate size of dead or distressed organisms 

• Magnitude of the effect (e.g., aquatic square area or total stream distance affected) 

• Pesticide application rate, intended use site (e.g., banks, above, or direct to water), 

and method of application; 

• Description of the habitat and the circumstances under which the incident occurred 

(including any available ambient water data for pesticides applied); 

• Actions to be taken to prevent recurrence of the incident. 

 EPA believes adverse incident information associated with discharges from the 

application of pesticides is useful to the Agency because the information: 

- Provides the Agency with an indication of the effectiveness of the permit in 

controlling discharges to protect water quality, including data upon which the Agency 

may base future permit decisions (e.g., modifications to or reissuance of this permit). 

- May be considered when reviewing applications for registration of new pesticides 

that are chemically similar to existing pesticides; 

- May be considered in ecological risk assessment and during deliberations on risk 

management decisions; 

- May be reviewed to determine trends that may indicate potential ecological impacts 

with an existing pesticide and/or to track improvements when mitigation measures are 

applied; 

- Provides information on the nature, extent, and severity of incidents to decisionmakers, stakeholders, and the public; and 

- Provides the Agency with information on which to assess compliance with regulatory 

requirements, including documentation and reporting. 

Currently, there is no database that includes adverse reporting from anyone other than the 

registrant under 6(a)(2) of FIFRA. EPA does not consider inclusion of adverse incident 

reporting in the NPDES permit to be a duplicative requirement to the FIFRA section 6(a)(2) 

requirements for registrant reporting of adverse incidents. This is because pesticide registrants 

are not likely to be directly covered under the PGP. Requiring the reporting of adverse incidents 

and follow-up corrective actions may address the lack of a universal, mandatory legal duty for 

pesticide users to report adverse incidents, at least for the pesticide use patterns covered by this 

permit. 

EPA acknowledges that assessing and correcting adverse incidents may be complicated 

in certain instances. For example, symptoms associated with adverse incidents are often vague 

or mimic other causes which may lead to incorrect diagnoses. Thus, it may be difficult to 

identify and track chronic effects resulting from pesticides discharges. It may also be difficult to 

observe adverse effects because of limited visibility or access such as dead fish poisoned in a 

wetland under dense vegetation or in sparsely populated areas or because scavengers scatter or 

devour carcasses before discovery. However, EPA believes that it is important to identify to the 

extent feasible situations where adverse effects occur where discharges from the application of 

pesticides also occur. 

Immediately observable signs of distress or damage to non-target plants, animals and 

other macro-organisms within the treatment area may warrant concern for a possible adverse 

Deleted: s

Deleted: of 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

98 

incident related to a discharge of pesticides during application. EPA acknowledges that some 

degree of detrimental impact to non-target species is to be expected and is acceptable during the 

course of normal pesticide treatment. EPA expects operators to use their best professional 

judgment in determining the extent to which non-target effects appear to be abnormal or 

indicative of an unforeseen problem associated with an application of pesticides. 

During a visual inspection, operators should watch for distressed or dead juvenile and 

small fishes, washed up or floating fish, fish swimming abnormally or erratically, fish lying 

lethargically at the water surface or in shallow water, fish that are listless or nonresponsive to 

disturbance, the stunting, wilting, or desiccation of non-target submerged or emergent aquatic 

plants, and other dead or visibly distressed non-target organisms including amphibians, turtles, 

and macro-invertebrates. These observations must be noted unless they are deemed not to be 

aberrant (for example, distressed non-target fish are to be expected when conducting a treatment 

with rotenone and non-target vegetation will be stressed near the target of contact herbicides). It 

should be noted that observation of these impacts does not necessarily imply that a pesticide has 

been misused or that there has been a permit violation or an instance of noncompliance, but may 

provide cause for further investigation of local water quality or reconsideration of Best 

Management Practices. Not reporting such incidents, however, is a permit violation.

Complete information concerning adverse impacts will aid EPA in any review of current 

or future pesticide use, adherence to Best Management Practices, or effectiveness of Best 

Management Practices. Reporting of adverse incidents is not required under this permit in the 

following situations: (1) you are aware of facts that clearly establish that the adverse incident 

was not related to toxic effects or exposure from the pesticide application; (2) you have been 

notified in writing by EPA that the reporting requirement has been waived for this incident or 

category of incidents; (3) you receive information notifying you of an adverse incident but that 

information is clearly erroneous; (4) an adverse incident occurs to pests that are similar in kind to 

pests identified as potential targets on the FIFRA label. However, records of all visual 

inspections, even for these situations, must be kept on site with the permittee. 

6.5 Reportable Spills and Leaks 

Part 6.5.1 requires permittees to call the appropriate EPA Incident Reporting Contact to 

report any spill or leak of a hazardous substance or oil into waters of the U.S with 24 hours of 

becoming aware of the spill or leak.20 Part 6.5.2 requires permittees to document this 

notification within 5 days of becoming aware of such spill or leak. This documentation provides 

a written record of what you reported to EPA orally. It should also include a description of the 

reporting system that will be used to alert responsible managers and legal authorities in the event 

of a future spill or leak and a description of preventive measures to prevent, contain, or treat 

spills and leaks of these materials. Part 6.4.3 requires permittees to notify either the National 

Marine Fisheries Service or the U.S. Fish and Wildlife Service if the permittee becomes aware of 

an incident that may have resulted from a discharge from your pesticide application that 

adversely affects a federally-listed threatened or endangered species or its federally-designated 

critical habitat. This information will be used by EPA to ascertain compliance with permit 

conditions. 

 20 Reportable Spills and Leaks are defined as those that trigger the requirement to notify the National 

Response Center (40 CFR Parts 110, 117, 302) based on the type of pollutant and quantity released.

Deleted: if 

Deleted: .) 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

99 

6.6 Other Corrective Action Documentation 

 For any event described in Part 6.1 of the permit, other than for adverse incidents or 

reportable spills or leaks, immediate reporting to EPA is not required, but permittees must 

document basic information describing the event and the permittees’ response to that event

within 5 days. For triggering events in Part 6.1, where the permittee determines that any revision 

to control measures is not necessary, the permittee must still document the review and the basis 

for this determination. EPA is not requiring permittees to submit this documentation to the 

Agency. Rather, EPA expects permittees to retain this information on-site and upon request, to 

make any such records available to EPA or any other Federal, state, or local regulatory agency 

governing pesticide applications. A summary of this information must also be included in the 

annual report for permittees subject to the annual reporting requirement. 

7. Recordkeeping and Annual Reporting 

This permit requires operators to maintain certain records to help them assess 

performance of control measures and to document compliance with permit conditions. These 

requirements are consistent with Federal regulations at 40 CFR 122.41(j), but have been tailored 

to more closely reflect requirements of the PGP. Part 7 of this permit describes recordkeeping 

requirements for all operators and the requirements for certain operators (i.e., those large 

applicators that are required to submit an NOI). Operators can rely on records and documents 

developed for other programs, such as requirements under FIFRA, provided all requirements of 

the permit are satisfied. 

This permit requires those who will exceed the annual treatment area threshold in Part 

1.2.2. to keep additional records and to submit an annual report. EPA recommends that all 

operators keep records of acres of linear miles treated each calendar year for all applicable use 

patterns covered under this general permit. This record will help operators estimate when they 

will exceed the annual treatment area threshold. As explained in the NOI discussion, the total 

acres or linear miles should not include those acres/miles accounted for in another operator’s 

NOI. 

The records that must be kept by all operators, specifically the entity who has operational 

control over the decision to perform pesticide applications, include the following: 

• A copy of the permit; 

• Adverse incident reports; and 

• Rationale for any determination that reporting of an identified adverse incident is not 

required consistent with allowances identified in Part 6.4.1. 

• A copy of any corrective action documentation (See Part 6.6)

As noted above, operators who are required to submit an NOI must keep additional 

records. These records are listed below and identified in Section 7.2 of the permit. Section 7.2 

of the permit applies to the entity submitting the NOI and to any pesticide applicator hired by 

such entity to perform activities covered under the permit. Records of equipment maintenance 

and calibration are to be maintained only by the entity performing the pest management activity 

on behalf of self or client. 

Deleted: . Similar to that for adverse 

incidents, the permit establishes 

conditions for both 24-hour and 5-day 

response periods

Deleted: acre

Deleted: treatment area/miles 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

100 

a. A copy of the NOI submitted to EPA, any correspondence exchanged between you and 

EPA specific to coverage under this permit, and a copy of the EPA acknowledgment letter 

assigning your permit tracking number; 

b. The date on which you knew or should have known that you would exceed an annual 

treatment area threshold during any calendar year, as identified in Part 1.2.2; 

c. Surveillance method(s) used, date(s) of surveillance activities, and findings of 

surveillance; 

d. Target pest(s); 

e. Pest density prior to pesticide application; 

f. Company name and contact information for pesticide applicator; 

g. Pesticide application date(s); 

h. Description of treatment area, including location and size (acres or linear feet) of 

treatment area and identification of any waters, either by name or by location, to which you 

discharged any pesticide(s); 

i. Name of each pesticide product used including the EPA registration number; 

j. Quantity of pesticide applied (and specify if quantities are for the pesticide product as 

packaged or as formulated and applied) 

k. Concentration (%) of active ingredient in formulation; 

l. For pesticide applications directly to waters, the effective concentration of active 

ingredient required for control; 

m. Any unusual or unexpected effects identified to non-target organisms; 

n. Documentation of any equipment cleaning, calibration, and repair (to be kept by pesticide 

application equipment operator); 

o. A copy of your PDMP, including any modifications made to the PDMP during the term 

of this permit. 

All required records must be prepared as soon as possible but no later than 14 days 

following completion of the associated activity. Operators must retain copies of these documents 

for a period of at least 3 years from the date their coverage under this permit expires or is 

terminated. The recordkeeping requirements in Appendix B, Subsection B.12 include a more 

general statement of the NPDES standard condition for records retention, but does not impose 

additional requirements on the operator above what is required in Part 7. 

In addition to recordkeeping, EPA is requiring certain operators (i.e., those larger 

applicators that are also required to submit an NOI) to submit annual reports that contain basic 

information on their pesticide discharges to waters of the U.S. EPA expects to have an online 

system available in time for submission of the first annual reports (in early 2012) with the intent 

of streamlining the process for completing this permit obligation. 

The annual report must include information for the calendar year, with the first annual 

report required to include activities for the portion of the calendar year after the effective date of 

the NOI. If the effective date of the NOI is after December 1, he/she is not required to submit an 

annual report for that first partial year but must submit annual reports thereafter, with the first 

annual report submitted also including information from the first partial year. When an operator 

terminates permit coverage, as specified in Part 1.2.5, the operator must submit an annual report 

for the portion of the year up through the date of the termination. The annual report is due no 

later than 45 days after the termination date, or February 15 of the following year, whichever is 

earlier. 

Deleted: know

Deleted: documented

Deleted: such

Deleted: point at which the operator 

exceeded the annual treatment area 

threshold

Deleted: operator first exceeds an 

annual treatment area threshold 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

101 

This information in the annual report will be used by EPA to assess permit compliance 

and to determine whether additional controls on pesticide discharges are necessary to protect 

water quality. For example, these data will help the Agency identify where pesticide discharges 

are occurring and the types of pesticides being discharged. 

The annual report is a summary of the pest control activities for each applicable use 

pattern. The annual report must contain the following information specific to each pest treatment 

area covered under the permit: 

a. Identification of any waters or other treatment area, including size, either by name or by 

location, to which you discharged any pesticide(s); 

b. Pesticide use pattern(s) (i.e., mosquito and other flying insects, aquatic weeds and algae, 

aquatic nuisance animals, or forest canopy) and target pest(s); 

c. Company name(s) and contact information for pesticide applicator(s), if different from 

the NOI submitter; 

d. Total amount of each pesticide product applied for the reporting year by the EPA 

registration number(s) and by application method (e.g., aerially by fixed-wing or rotary 

aircraft, broadcast spray, etc.); 

e. Whether this pest control activity was addressed in your PDMP prior to pesticide 

application; 

f. If applicable, an annual report of any adverse incidents as a result of these treatment(s), 

for incidents, as described in Part 6.4.1; and 

g. A description of any corrective action(s), including spill responses, resulting from 

pesticide application activities and the rationale for such action(s). 

8. EPA Contact and Mailing Addresses 

 This part of the permit identifies contact information and mailing addresses for any 

applicable reporting requirements of this permit. Note that depending on the requirement, some 

reports/notifications are to go to the EPA Regional office while others are to be sent to an EPA 

Headquarters location. Generally, Regions are notified for information that may require rapid 

review and response by the Region to address potential adverse effects or other concerns 

requiring more immediate attention. 

9. Permit Conditions Applicable to Specific States, Indian Country Lands, or 

Territories 

 Part X of the final PGP will contain conditions provided by States and Tribes as part of 

the Clean Water Act (CWA) Section 401 certification and consistent with the Coastal Zone 

Management Act (CZMA). 

 Section 401 of the CWA provides that all Federally-issued permits be certified by the 

state in which the discharge occurs. The state certifies that the proposed permit will comply with 

state water quality standards and other state requirements. Additionally, Section 401 provides 

that any certification under the Act shall set forth any effluent limitations and other limitations, 

and monitoring requirements necessary to assure that any applicant for a Federal license or 

permit will comply with any applicable effluent limitations and other limitations, standard of 

Deleted: s
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

102 

performance, or prohibition, effluent standard, or pretreatment standard, and with any other 

appropriate requirement of State and Tribal law set forth in such certification and shall become a 

condition on any Federal permit subject to the provisions of this section. 

 The Coastal Zone Management Act (CZMA) and its implementing regulations (15 CFR 

Part 930) require that any Federal licensed activity directly affecting the coastal zone of a state 

with an approved Coastal Zone Management Program (CZMP) be consistent with the 

enforceable policies of that approved program to the maximum extent practicable. Agency 

general permits that do not involve case-by-case or individualized determinations by the Agency 

are federal activities for the purposes of CZMA section 307(c)(1). For the final PGP, EPA will 

make a consistency determination regarding the enforceable policies in each approved state CZM 

program for the coastal zones including state waters where the PGP would authorize discharges. 

15 CFR 930.31(d). 

 Those provisions are not included in the draft PGP but will be included in the final PGP. 

10. Appendices 

A. Definitions and Acronyms 

 Appendix A of the Permit provides permit-specific definitions of statutory, regulatory, 

and other terms important for understanding this draft permit and its requirements. Any terms 

that are not listed in this definitions part have the meaning given to the terms by 40 CFR Part 

122.2 (the definitions section of the NPDES regulations). To develop these definitions, EPA has, 

where possible, relied on existing definitions in other laws and regulations applicable to this 

universe of permittees in order to provide consistency with those laws and provide permittees 

with a familiar framework. 

B. Standard Permit Conditions 

Federal regulations require that all NPDES permits contain the standard permit 

conditions specified in 40 CFR 122.41. Appendix B incorporates those standard conditions with 

some minor revisions to more clearly address pesticide application operations covered under the 

PGP. Of note, Subsection B.1 in Appendix B explains the permittee’s duty to comply with the 

conditions of the permit with failure to do so constituting a violation of the Clean Water Act. 

C. Areas Covered 

 As noted above, this permit is available in those areas where EPA remains the NPDES 

permitting authority for discharges from the application of pesticides to or over, including near, 

waters of the U.S. NPDES-authorized states issue permits elsewhere in the U.S. for these types 

of discharges. Appendix C includes a list of those areas where this EPA permit is available for 

such discharges and includes portions of all ten EPA Regions where EPA remains the NPDES 

permitting authority. One important note to acknowledge is that the State of Alaska has received 

authorization to administer the NPDES program; however, EPA and the State established a 

three-year phase-in schedule that does not have the State issuing permits for discharges from 

pesticide applicators until November 1, 2011. As the court decision only granted a stay until 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

103 

April 9, 2011, EPA is including discharges from pesticide applications in Alaska in this permit 

such that permit coverage is available at least between April 9, 2011 and November 1, 2011. 

D. Notice of Intent Form 

 Part 1.2.2 identifies certain operators required to prepare and submit a complete and 

accurate Notice of Intent (NOI) form to be authorized to discharge under this permit. Operators 

must submit NOIs in accordance with the deadlines provided in Part 1.2.3 of the PGP. The NOI 

form provides EPA with the information necessary to determine an operator’s eligibility to 

discharge under this permit, and enables EPA to better match up permittees with other reporting 

requirements and to prioritize oversight activities. Appendix D of the PGP contains information 

that is required to be provided on the NOI form. Operators are required to submit that 

information electronically using EPA’s eNOI system (website URL to be provided in the final 

permit but will be similar to EPA’s Vessel General Permit eNOI site at: 

http://cfpub.epa.gov/npdes/vessels/enoi.cfm and EPA’s stormwater general permit eNOI site at 

http://cfpub.epa.gov/npdes/stormwater/enoi.cfm). EPA is using the eNOI system because it is 

easier (including availability of online instructions and help menus to guide you through the 

process), faster (NOIs can be processed 2 weeks or more faster than paper forms), and more 

accurate (eNOI will ensure form is completed and will auto check certain key elements to 

improve accuracy of information submitted). 

E. Notice of Termination Form 

Part 1.2.5 of the PGP requires certain permittees (i.e., those required to submit an NOI to 

be authorized under this permit) to submit a Notice of Termination (NOT) form within 30 days 

of the occurrence of one of several different triggering events: (1) when a new operator has taken 

over responsibility for the pest treatment, (2) the operator has ceased aquatic pesticide 

application covered under the general permit, (3) there is not and no longer will be pesticide 

discharge, or (4) the operator has obtained coverage under an individual permit or an alternative 

general permit. Appendix E of the PGP contains a copy of the information required to be 

submitted on the NOT form. Like the NOI, EPA is requiring that operators complete and submit 

the NOT form electronically using EPA’s eNOI system, (website URL to be provided in final 

permit). 

F. Endangered Species Procedures 

Background 

 Section 7(a)(2) of the Endangered Species Act (ESA) requires each Federal agency, in 

consultation with and with the assistance of the Fish and Wildlife Service (FWS) and the 

National Marine Fisheries Service (NMFS), collectively “the Services,” to ensure that the actions 

they authorize, fund, or carry out are not likely to jeopardize the continued existence of any 

endangered or threatened species (referred to as “listed species”) or result in the destruction or 

adverse modification of their designated critical habitats. 

 The Services have published regulations implementing ESA section 7 at 50 CFR Part 

402. The regulations provide that a Federal agency (such as EPA) must consult with FWS, 

NMFS, or both if the agency determines that an activity authorized, funded, or carried out by the 

Deleted: or 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

104 

agency may affect listed species or critical habitat. The kinds of effects that trigger the 

consultation obligation could include, among other things, beneficial, detrimental, direct and 

indirect effects. EPA believes the issuance of the PGP may affect listed species and is thus 

subject to the ESA section 7(a)(2) consultation requirements. 

Current Action 

 EPA is consulting with the National Marine Fisheries Service (NMFS) and U.S. Fish and 

Wildlife Service (FWS) on this general permit, which may result in the addition of permit 

conditions to further protect: 

- Species that are listed under the Endangered Species Act (ESA) as endangered or threatened 

(known as “listed species”); 

- Listed species’ habitat that is designated under the ESA as critical (“critical habitat”); and 

- Species proposed, but not yet listed as endangered or threatened, or habitat proposed, but not 

yet listed as designated critical habitat. 

EPA initiated informal consultation with the Services in October 2009 and continues to 

work closely with them to meet the Agency’s obligation to insure that issuance of the PGP will 

not be likely to jeopardize the continued existence of any listed species or result in the 

destruction or adverse modification of their designated critical habitats. 

As a result of EPA’s discussions with the Services, EPA has proposed three provisions in 

the draft permit to address ESA-related concerns. First, if an operator is required to file an NOI 

to be eligible for coverage, the operator must provide information in the NOI relating to the 

possibility that the pesticide activities covered by the permit will overlap with the distribution of 

listed species or critical habitat. If such overlap is expected and the pesticide activities have not 

been the subject of consideration by the appropriate Service under ESA sections 7 or 10, the 

operator must identify the species and habitat within the areas for which the operator is seeking 

permit coverage. (See the Notice of Intent requirements in Appendix D of the draft permit.) The 

Agency proposes to transmit to the appropriate Service a copy of NOIs received pursuant to the 

general permit. Second, Part 6.4.3 of the draft permit would require any permittee who becomes 

aware of an adverse effect on any listed species to report that information not only to EPA (as is 

already required under Parts 6.4.1 and 6.4.2), but also to the appropriate Service. Information 

submitted pursuant to either of these provisions could lead EPA to impose on a permittee 

additional restrictions to protect listed species or critical habitat. Finally, Part 1.6.2 of the draft 

permit contains a provision that makes clear that an operator must comply with requirements 

resulting from any pre-existing consultations under ESA section 7 or “take permits” under ESA 

section 10 that address any discharges from activities that would be covered under this general 

permit. 

The general permit also includes a placeholder in Part 1.6.1 noting that the Agency is 

working with the Services to identify possible additional permit conditions (i.e., effluent 

limitations, site monitoring, planning, corrective action, recordkeeping, and/or reporting) to 

reduce the risks to listed species and critical habitat from actions under this permit in addition to 

documenting the actions necessary and that were taken to protect species and critical habitat. In 

developing these additional requirements, EPA is considering how best to draft these 

requirements so that they apply to operators whose activities may affect listed species or their 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

105 

critical habitat, while not imposing requirements on operators when their activities would not 

affect listed species or critical habitat. EPA is also considering how best to draft these permit 

provisions so that compliance with permit terms that may require operators to further minimize 

or eliminate pesticide use in certain circumstances does not result in operators taking actions that 

would cause greater harm to listed species and their habitats than would otherwise result from 

the application of pesticide discharges consistent with the conditions in the draft PGP. 

Based on the results of consultation with the Services, it may be necessary to add 

additional effluent limitations to the permit. Effluent limitations such as those identified below 

are examples of what EPA is considering, should they be necessary, to protect listed species and 

their habitat. The limitations described below reflect two general approaches that may be 

appropriate for inclusion in the PGP: a) where practicable, avoid the discharge of any pesticide in 

areas where it could adversely affect listed species adversely; or b) when avoiding pesticide 

discharge is impracticable, select the types of pesticide and the method of application that will 

minimize adverse effects. In the FR notice announcing this draft permit, EPA is requesting 

comment on appropriate measures to protect listed species, including the potential provisions 

described below. 

1. For aquatic weeds and algae control upstream of threatened and endangered species habitat, 

explore the use of mechanical or physical control methods before applying pesticides. In 

many cases, manual removal of weeds would be less harmful than applying pesticides. 

2. Consider treating vegetation early in the season and the vegetation growth stage to minimize 

the build-up of nuisance vegetation, and to minimize the depletion of dissolved oxygen from 

decaying vegetation at these times unless listed species are present only at this time. 

3. In cases where listed species use a waterbody for specific periods, if practicable, control pests 

when these organisms are not present. 

4. Treat only a portion of a waterbody at a time, allowing the possibility that more mobile 

organisms will move away from the treatment area, if such a step-wise treatment would 

provide for adequate pest control. Depending on the type of organism, using some type of 

exclosure or deterrence measures in or near the treated area prior to treatment may reduce 

likelihood of species being exposed. For instance, in areas upstream of areas containing 

listed salmonids, consider the use of block nets to deter movement of fish into the treatment 

area. 

5. In cases where pesticides are applied upstream, or in a pond-like environment draining into 

waters occupied by listed species, consider the retention time of the treated areas, 

degradation rate of the pesticide and/or the dilution capacity of the receiving waters to 

minimize exposure of listed species to pesticides. 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

106 

APPENDIX A. List of pesticides and degradates which exceeded aquatic-life benchmarks 

in the USGS study and the draft CA Central Valley Regional 303(d) impairment list of 

pesticides. 

Table A1. List of all pesticides and degradates 

which exceeded aquatic-life benchmarks in the 

USGS study 

Percentage of sites that 

exceed one or more 

aquatic-life benchmarks 

Pesticide/Degradate Agricultural 

sites Urban Sites 

Chlorpyrifos 20.5 36.7 

Azinphos-methyl 19.3 13.3 

Atrazine 18.1 -- 

p,p-DDE 15.7 13.3 

Alachlor 14.5 -- 

Diazinon 8.4 73.3 

Malathion 7.2 30.0 

Parathion-methyl 7.2 3.3 

Carbofuran 6.0 -- 

Disulfoton 2.4 -- 

Diuron 2.4 6.7 

Methomyl 2.4 -- 

Thiobencarb 2.4 -- 

Carbaryl 1.2 13.3 

Dieldrin 1.2 3.3 

Molinate 1.2 -- 

Parathion 1.2 6.7 

Phorate 1.2 -- 

Propargite 1.2 -- 

Terbufos 1.2 -- 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

107 

Table A2. Pesticides/Degradates that are listed as 303(d) impairments from the CA Central 

Valley (Draft 2008 list) 

Pesticide/Degradate # of 

impairments 

WQS being exceeded 

Aldicarb 1 Narrative toxicity and pesticide objectives – one-tenth the 48-hr LC50 

Chironomus tentans. 

Azinphos-methyl 3 Narrative toxicity and pesticide objectives – USEPA ambient water 

quality criteria (USEPA, 1976). 

Bifenthrin 1 Narrative toxicity and pesticide objectives - one tenth the 96 hour LC50 

for Haylella azteca. 

Carbofuran 1 Narrative toxicity and pesticide objectives – USEPA recommended 

water quality criterion for the protection of freshwater aquatic life. 

Chlorpyrifos 63 Numeric site-specific water quality objective for chlorpyrifos or 

narrative toxicity and pesticides objective – exceedance of 1-hour 

and/or 4-day average maximum concentration criterion above the 

allowable frequency. 

Copper (not all from 

pesticide sources) 

18 Exceedance of 4-day average maximum concentration criterion above 

the allowable frequency; or exceedance of California Toxics Rule 

criteria. 

Diazinon 46 Numeric site-specific water quality objective for diazinon or narrative 

toxicity and pesticides objectives – exceedances of 1-hour and/or 4-day 

average maximum concentration criterion above the allowable 

frequency. 

Dichlorvos 1 Narrative toxicity and pesticides objectives – one-tenth the 96-hour 

LC50 for Daphnia magna. 

Dimethoate 8 Narrative toxicity and pesticides objectives – one-tenth LC50 for the 

most sensitive species in freshwater (Cyclops strenuus, a copepod 

crustacean). 

Disulfoton 1 Narrative toxicity and pesticides objectives – USEPA National 

Ambient Water Quality Disulfoton Criterion for freshwater aquatic life 

protection, maximum concentration of 0.05 ug/L. 

Diuron 8 Narrative toxicity and pesticides objectives – the 96-hour EC50 for 

Chlorella pyrenoidosa (1.3 ug/L). 

Malathion 3 Narrative toxicity and pesticides objectives – The USEPA 

recommended 4-day average criterion continuous concentration (CCC) 

(0.1 ug/L) (USEPA, 1976). The California Department of Fish and 

Game Hazard Assessment Criterion 1-hr average concentration (CMC) 

(0.43 ug/L) (CDFG, 1998).. 

Organophosphorus 

Pesticides 

1 Narrative toxicity and pesticides objectives – Toxicity and chemistry 

results indicating organophosphorus pesticide toxicity.. 

Oxyflurofen 2 Narrative toxicity and pesticides objectives – the 96-hour EC50 for 

Selenastrum capricornutum, a green algae. 

cis-Permethrin 1 Narrative toxicity and pesticides objectives – one-tenth the LC50 value 

for the most sensitive freshwater species, Tanytarsus sp. 

Prometryn 1 Narrative toxicity objective; 96-hour EC50 value for Navicula 

pelliculosa, a freshwater diatom. 

Pyrethroids 13 Narrative toxicity objective; sediment-bound toxicity; chemical 

analysis; and TIE manipulations indicate pyrethroid pesticides are the 

likely cause. 

Simazine 4 Drinking water primary Maximum Contaminant Limit (MCL) (4 

μg/L). 

Trifluralin 1 Narrative toxicity and pesticides objectives; interpreted using LOEC 

for Pimephales promelas of 0.7 ug/L. 

Formatted Table
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

108 

Appendix B. Chemicals with exceedances in USGS study and subsequent mitigation 

measures that reduce pesticide residues in water 

Chemical Action Date 

Alachlor Reduced maximum application rates and frequency of 

application; Restricted Use Pesticide; 50 foot setback 

from waters for mixing and loading; state management 

plan; spray drift advisory; monitoring program. 

1998 Reregistration 

Eligibility Decision 

(RED) 

Atrazine Intensive monitoring program 2003 Interim 

Reregistration 

Eligibility Decision 

(IRED) 

Diuron 

Used monitoring data from

USGS, Florida & California

Powder formulations cancelled; reduction in application 

rates and number of applications; no aerial applications 

for most crops; no treatment of home lawns 

2003 RED 

Thiobencarb Application restrictions for LA, TX; label restrictions for 

catfish/crayfish farming; 14-day holding periods for rice 

farming; mixing and loading restrictions within 100 ft of 

water; no applications within 24 hr of rainfall 

1997 RED 

Azinphos-methyl All uses to be phased out by 2012; until such time, the 

following measures imposed: buffer zones; limit 

maximum usage and frequency; spray drift requirements; 

prohibit aerial application on most crops; limit maximum 

usage and frequency 

2001 IRED 

Carbaryl Lawn broadcast uses of liquid formulations cancelled; 

certain other uses and application methods cancelled; 

reduced application rates for some uses; prohibit most 

aerial applications 

2003 IRED 

Carbofuran Most uses cancelled; for remaining six uses the Agency 

plans to issue a Notice of Intent to Cancel. 

2006 IRED 

Chlorpyrifos Residential uses cancelled; agricultural use restrictions 

including reduced application rates and fewer 

applications per season, increase in retreatment intervals 

and addition of buffer zones around water bodies 

2001 IRED 

Diazinon Residential uses and granular uses cancelled; aerial 

application cancelled; seed treatment uses cancelled 

2002 IRED 

Disulfoton Cancelled some uses; reduced application rates and 

frequency of application for certain crops; buffers zones 

near water; aerial application prohibited; Notice of 

Receipt of Voluntary Cancellation of all Product 

Registrations published 7/22/09. Product Cancellation 

Order published September 23, 2009. 

2002 IRED 

Deleted: Page Break
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

109 

Chemical Action Date 

Malathion Some uses cancelled; reduced application rates and 

frequency of application for many crops; 25 and 50 foot 

buffer zones for non-ULV and ULV aerial applications 

near water; droplet size and application altitude 

specifications for mosquito adulticide use; spray drift 

minimization label statements for agricultural and public 

health products; environmental hazard precautionary 

label statements required for agricultural, public health, 

and residential products 

2006 RED; 2009 

RED Revision 

Methomyl Reduced maximum applications rates; buffer zones; use 

rate restrictions; ground water and surface water 

advisories 

1998 RED 

Methyl Parathion Cancelled several fruit and vegetable uses; mixing and 

loading away from water; reduced application rates and 

number of applications 

2003 IRED 

Phorate Reduced application rates and number of applications; 

prohibit aerial applications; buffer zones; setbacks from 

wells 

2001 IRED 

Propargite Reduced maximum rates and number of applications; 50 

ft buffer; spray drift label requirement 

2001 RED 

Terbufos Buffer zones and setbacks; reduction in sales; limited 

mixing and loading near water 

2001 IRED 

Lindane All uses cancelled except seed treatment (2002 RED); all 

remaining uses cancelled effective 7/07 

2002 RED; 2006 

RED Addendum 

Heptachlor/Heptachlor 

Epoxide 

All uses cancelled 1978 Cancellation 

Chlordane All uses cancelled 1978 Cancellation 

Molinate All uses cancelled over 5 year period - 2008 effective 

date 

2003 Voluntary 

Cancellation 

Ethyl Parathion All uses cancelled; all products phased out by 2003 2000 Cancellation 

Dinoseb All uses cancelled 1986 Cancellation 

Cyanazine All uses cancelled 1996 Cancellation 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

110 

Chemical Action Date 

DDT/DDE All uses cancelled 1972 Cancellation 

Dieldrin All uses cancelled 1974 Cancellation 

Toxaphene All uses cancelled 1982 Cancellation 

Methoxychlor All uses cancelled 2004 Cancellation 

Endrin All uses cancelled 

1995 Cancellation 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

111 

APPENDIX C 

Summary of Pesticide-Specific Exceedance Data and Risk Mitigation Actions

• Of the 75 pesticides and 8 degradates analyzed, 19 pesticides in use at the time of the 

study were measured at concentrations that exceeded EPA benchmarks: 5 herbicides 

(alachlor, atrazine, diuron, molinate, and thiobencarb) and 13 insecticides (azinphosmethyl, carbaryl, carbofuran, chlorpyrifos, diazinon, disulfoton, malathion, methomyl, 

parathion, methyl parathion, phorate, propargite, and terbufos). 

• In addition, DDE, a degradate of DDT, was detected at levels in approximately 20 

streams that exceeded EPA benchmarks. 

• The uses for five pesticides (diuron, diazinon, chlorpyrifos, parathion, and DDT 

(degradate DDE)) detected by USGS have been cancelled or significantly limited. 

• 5 pesticides accounted for the majority of the exceedances: alachlor, azinphos-methyl, 

chlorpyrifos, diazinon, and malathion. These pesticides are discussed in more detail 

below: 

Alachlor 

Summary of USGS Findings:

• For alachlor, there were 14 instances where alachlor measured concentrations exceeded a 

benchmark. Usage of alachlor declined along with number of exceedances throughout 

the study and following the issuance of EPA’s RED in 1998, there were no exceedances 

observed in the last 3 years of the study (1999 – 2001). 

Azinphos Methyl 

Summary of USGS Findings:

• For azinphos-methyl, there were 15 instances where azinphos-methyl measured 

concentrations exceeded a benchmark. All uses of azinphos methyl will be phased out by 

2012. 

Atrazine

 

History: 

• Registered in 1958 as a triazine herbicide 

• Initiated special review based on carcinogenic potential in 1988 

• Risk reduction measures voluntarily initiated by registrant in 1990s 

• Special review for triazines initiated in 1994 

• January 2003 IRED specified mitigation measures to reduce risk, including intensive 

drinking water monitoring of 125 vulnerable CWS 

• October 2003 Addendum to IRED concluded not likely to be a human carcinogen; 

specified ecological monitoring and mitigation program for vulnerable 

watersheds; and, consistent with FIFRA-SAP review, concluded that available data does 

not establish atrazine caused developmental effects on amphibians 

• Cumulative triazine assessment to be issued later this year and may identify further risk 

mitigation options 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

112 

Review Process:

• Extensive public participation review process during reregistration 

• Extensive consultation with federal, state, and local regulatory partners, registrants, 

pesticides users, public interest groups, and other stakeholders 

• SAP review of Agency’s cancer assessment and ecological risk assessment for 

amphibians 

Mitigation Measures: 

• Product use changes required in January, 2003 IRED to reduce exposure to workers 

 and exposure from residential uses 

• Intensive and targeted monitoring program of drinking water (raw water at 125 CWS in 

areas of atrazine use); if atrazine exceeds EPA’s safety standards, use will be prohibited 

in affected watershed area; complemented by routine SDWA monitoring of finished 

drinking water and rural well monitoring study 

• Ecological monitoring and risk mitigation within 40 representative vulnerable watersheds 

associated with corn and sorghum production. If watershed exceeds level of concern, 

remediation measures will be required, and need for further expansion of monitoring will 

be considered. 

• Implementation of testing program to evaluate potential risk to amphibians 

• Continue to review ongoing epidemiology and cancer studies and amphibian studies 

Summary of USGS Findings:

• Only 4 exceedances in agricultural streams for the aquatic community benchmark were 

observed. 

Atrazine Ecological Monitoring Program

• As a condition of reregistration, the registrant must conduct a monitoring program. The 

purpose of program is to determine the extent to which water bodies in the most 

vulnerable watersheds may exceed an effects-based benchmark. If a water body exceeds 

a benchmark, it will be subject to mitigation measures through registrant actions, 

regulatory options, and/or TMDL-like watershed management programs. 

• Endpoint of concern or benchmark is change in aquatic community structure, based in 

part, on a large number of microcosm and mesocosm studies for atrazine. This is the 

most sensitive endpoint and considers direct effects on fish and invertebrates and indirect 

effects on habitat and food sources. 

• The FIFRA risk assessment and draft atrazine aquatic life criteria are based on the same 

endpoint and were jointly prepared. 

• 40 representative vulnerable watersheds in corn/sorghum areas (Midwest) are being 

monitored. Monitoring in the Midwest sites will occur over three years (2004-2006) and 

each watershed will have a minimum of two years worth of data. Each watershed is 

sampled every 4 days; some watersheds are sampled daily. 

• 4 vulnerable watersheds in sugarcane growing areas (LA, FL) will be monitored; 

sugarcane monitoring sites will have two years of data from 2005-2006. 

• EPA scientists are reviewing the first 5 years of Midwest data and 2 years of the 

sugarcane data for Louisiana. Preliminary analysis suggests that measured 

concentrations of atrazine in Missouri and Nebraska exceeded the Agency's LOC. The 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

113 

Agency is evaluating the sugarcane data and has not yet made a determination on those 

results. 

Atrazine Drinking Water Monitoring Program 

• As a condition of reregistration, the registrant must monitor over 130 Community Water 

Systems (CWSs) in areas of atrazine use in 10 states (Illinois, Indiana, Iowa, Kansas, 

Kentucky, Missouri, North Carolina, Ohio, Texas, and Louisiana.) If atrazine is detected 

above Agency standards for raw water, the use will be prohibited in that specific 

watershed area. 

• Weekly monitoring through the growing season (generally April through July) with 

biweekly monitoring for the rest of the year. 

• Both raw and finished water are being monitored; some CWSs have more than one raw 

water source measured. 

• There were no exceedances of the human health benchmark, which is 37.5 ppb atrazine 

and its degradates based on a 90-day average in raw water. 

Chlorpyrifos 

History and Mitigation Measures 

• Registered in 1965 as an Organophosphate (“OP”) insecticide

• MOA signed with registrant in January 1997 to reduce indoor exposures

• MOA signed with registrant in June 2000 to eliminate and phase out most uses that result 

in residential exposure (home lawns, indoor crack and crevice treatments, and whole 

house post-construction termiticide treatments). These actions also mitigated risks to 

workers who apply chlorpyrifos and reduced risks to the environment. 

• IRED issued in February 2002 included additional provisions to further reduce worker 

and ecological risks through label changes that included worker protection measures, 

buffer zones around water bodies, and rate reductions for agricultural uses. 

Summary of USGS Findings: 

• Chlorpyrifos exceedances were observed in approximately 20 of the agricultural streams, 

10 of the mixed land-use streams, and 14 of the urban streams predominantly in the 

period of 1993-1994. 

• For chlorpyrifos, there were 46 instances where chlorpyrifos measured concentrations 

exceeded a benchmark which were predominantly observed in the period of 1993-1994. 

Urban uses for chlorpyrifos have been banned in 2000, and in 2002 agricultural uses were 

changed to mitigate potential aquatic effects. 

• Chlorpyrifos levels have decreased significantly since the June 2000 MOA was signed 

and residential uses were eliminated

Diazinon 

History and Mitigation Measures:

• MOA with registrant signed in December 2000; phased out and cancelled all indoor and 

outdoor residential uses. 
U.S. Environmental Protection Agency 2010 NPDES Pesticides General Permit Fact Sheet 

114 

• IRED issued in May 2004 included additional measures for the remaining agricultural use 

products to further reduce risks to workers, birds and the environment. These measures 

included cancellation of certain crop uses, terminating most uses of the granular 

formulation, deleting most aerial applications, reducing the amount and frequency of use, 

adopting engineering controls, and other protective measures. 

• EPA’s regulatory activities have eliminated about 75% of diazinon’s former uses, 

particularly its residential uses. 

• Final water quality criteria was issued by Office of Water in 2006 

USGS Results:

• Diazinon exceedances were observed in approximately 10 agricultural streams, 10 mixed 

land-use streams, and 20 urban streams. 

• The vast majority of exceedances were associated with potential aquatic invertebrate 

effects. 

• For diazinon, there were 44 sites where diazinon measured concentrations exceeded a 

benchmark. 

• Since urban uses of diazinon were cancelled in 2000, concentrations have decreased 

significantly in urban and mixed land-use streams. A recent regional USGS study of 

diazinon shows declining concentrations in several urban streams in the Northeast during 

1998-2004. 

Malathion 

Summary of USGS Findings:

• For malathion, there were 27 instances where malathion measured concentrations 

exceeded a benchmark. 

• The revision of the malathion RED was completed in 2009. Mitigation required by the 

RED will reduce maximum application rates and the number of applications allowed 

annually when labels are revised during product reregistration, which is currently 

underway. 

Deleted: 37 instances