United States Environmental Protection Agency

Final National Pollutant Discharge Elimination System (NPDES)

Pesticide General Permit (PGP) for Point Source Discharges to 

Waters of the United States from the Application of Pesticides

Fact Sheet

Agency: United States Environmental Protection Agency

Action: Notice of Draft NPDES General Permit
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

2 

TABLE OF CONTENTS

I. Background ............................................................................................................................4

1. Clean Water Act ................................................................................................................4

2. NPDES Permits .................................................................................................................4

3. History of Pesticide Application Regulation ....................................................................5

4. Court Decisions leading to the CWA regulation concerning Pesticide Applications .......5

5. 2006 Agency Rulemaking Excluding Pesticides from the NPDES Permitting 

Program .............................................................................................................................6

6. Legal Challenges to the 2006 NPDES Pesticides Rule and Court Decision ....................7

7. Implications of the Court’s Decision ................................................................................8

8. Publication of Draft Pesticide General Permit ..................................................................9

9. Public Meetings/Hearing Held on Draft Pesticide General Permit ..................................9

10. Public Comments Received on Draft Pesticide General Permit .......................................9

11. EPA’s Posting of a Pre-publication Draft of the Final PGP ...........................................10

12. ESA Consultation............................................................................................................10

13. Provisions in the Final PGP Added Following Consultation with NMFS......................13

II. Structure of this Permit .......................................................................................................18

1. General ............................................................................................................................18

2. Conformance to Recent Court Decisions ........................................................................19

3. Sharing of Responsibilities .............................................................................................22

III. Summary of Permit Conditions ..........................................................................................23

1. Coverage under this Permit .............................................................................................23

1.1 Eligibility ...............................................................................................................23

1.2 Authorization to Discharge Under this Permit.......................................................32

1.3 Alternative Permits ................................................................................................44

1.4 Severability ............................................................................................................46

1.5 Other Federal and State Laws ................................................................................46

1.6 Federally Listed Endangered and Threatened Species and Designated 

Critical Habitat. .....................................................................................................47

2. Effluent Limitations ........................................................................................................47

2.1 Applicators’ Responsibilities .................................................................................55

2.2 Decision-makers’ Responsibilities.........................................................................57

3. Water Quality-Based Effluent Limitations .....................................................................92

4. Site Monitoring .............................................................................................................106

4.1 Visual Monitoring Requirements for Pesticide Applicators ................................108

4.2 Visual Monitoring Requirements for all Operators .............................................109

5. Pesticide Discharge Management Plan (PDMP) ..........................................................109

5.1 Contents of Your PDMP ......................................................................................110

5.2 Pesticide Discharge Management Plan Modifications. .......................................113

5.3 Pesticide Discharge Management Plan Availability. ...........................................114

6. Corrective Action ..........................................................................................................114

6.1 Situations Requiring Revision of Pest Management Measures ...........................114

6.2 Corrective Action Deadlines ................................................................................115

6.3 Effect of Corrective Action ..................................................................................115
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

3 

6.4 Adverse Incident Documentation and Reporting .................................................116

6.5 Reportable Spills and Leaks .................................................................................118

6.6 Documentation for Other Corrective Action .......................................................119

7. Recordkeeping and Annual Reporting ..........................................................................119

7.1 Records to be kept by all Operators (all Decision-makers and all 

Applicators) .........................................................................................................119

7.2 Records to be kept by all For-Hire Applicators ...................................................120

7.3 Records to be kept by Small Entities, Submitting an NOI ..................................120

7.4 Records to be kept by Large Entities, Submitting an NOI ..................................121

7.5 Retention of Records ............................................................................................122

7.6 Annual Reports ....................................................................................................123

7.7 Annual Reporting for Any Decision-maker with Discharges to Waters of 

the United States containing NMFS Listed Resources of Concern, as 

defined in Appendix A of the permit, and Who is a Small Entity .......................124

8. EPA Contact and Mailing Addresses ............................................................................125

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

Territories ......................................................................................................................125

10. Permit Appendices ........................................................................................................126

A. Definitions and Acronyms ...................................................................................126

B. Standard Permit Conditions .................................................................................126

C. Areas Covered ......................................................................................................126

D. Notice of Intent Form...........................................................................................126

E. Notice of Termination Form ................................................................................127

F. Pesticide Discharge Evaluation Worksheet .........................................................127

G. Annual Report Template ......................................................................................127

H. Adverse Incident Template ..................................................................................128

I. Endangered Species Procedures ..........................................................................128

Fact Sheet Appendices ...............................................................................................................129 

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 ................................................................................129 

Appendix B Chemicals and exceedances in USGS study and subsequent mitigation 

measures that reduce pesticides residues in waters ..............................................131 

Appendix C Summary of Pesticide-Specific Exceedance Data and Risk Mitigation 

Actions .................................................................................................................134
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

4 

I. Background 

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 or 

situations that require individual consideration. Upon receiving the appropriate permit 

application(s), the permitting authority, e.g., the United States 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. 

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 EPA permit for similar types of discharges, as 

long as it satisfies the regulatory requirements of the NPDES program, the CWA, 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 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

5 

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

regulated by a general permit. Given the significant number of pesticide operations requiring 

NPDES permit coverage and the discharges common to these operations, EPA believes that it 

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

each Operator. 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

 EPA regulates the sale, distribution and use of pesticides in the United States under the 

statutory framework of the Federal Insecticide, Fungicide, and Rodenticide Act (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 

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 United States. In 2001, the United States 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 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

6 

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 United States 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 weeds and algae and products 

to control mosquito larvae). Other states have continued their practice of neither requiring nor 

issuing permits to people who apply pesticides to Waters of the United States. These varying 

practices reflected the substantial uncertainty among regulators, the regulated community, and 

the public regarding how the CWA applies to discharges to Waters of the United States from the 

application of pesticides.

 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 United States. 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 United States 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 

“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 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

7 

deposited to the water to target the pests, provided that the application is consistent with relevant 

Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) requirements in both instances. 

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 7, 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 an 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.

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. On March 3, 2011, EPA requested an extension 

from April 9, 2011 to October 31, 2011 to allow sufficient time for EPA to engage in 

Endangered Species Act (ESA) consultation and complete the development of an electronic 

database to streamline requests for coverage under the Agency’s general permit. EPA also 

requested more time to allow for authorized states to finish developing their state permits and for 

permitting authorities to provide additional outreach to stakeholders on pesticide permit 

requirements. On March 28, 2011, the U.S. Court of Appeals for the Sixth Circuit granted EPA's 

request for an extension to October 31, 2011. 

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

31, 2011, Operators must comply with NPDES permit requirements for discharges to Waters of 

the United States of biological pesticides, and of chemical pesticides that leave a residue. In 

response to the Court’s decision, EPA proposed a general permit on June 4, 2010 to cover certain 

discharges resulting from pesticide applications. EPA Regional offices and State NPDES 

authorities may issue additional general permits or individual permits if needed. After 

consideration of comments received on the proposed permit and engaging in ESA consultation, 

EPA is issuing its final permit.
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

8 

7. Implications of the Court’s Decision

Irrigation return flow (which includes runoff from a crop field due to irrigation of that 

field) and agricultural stormwater runoff do not require NPDES permits, as exempted by the 

CWA. For example, runoff into engineered conservation measures on a crop field such as grassy 

swales and other land management structures that direct flow from the crop field is considered 

either irrigation return flow or agricultural stormwater. However, discharges from the 

application of pesticides, which includes applications of herbicides, into irrigation ditches and 

canals that are themselves Waters of the United States, are not exempt as irrigation return flows 

or agricultural stormwater, and do require NPDES permit coverage. This is because such 

pesticide discharges are not only point sources, but also that these pesticides are now defined as 

“pollutants” under the CWA due to the Sixth Circuit Court’s decision. Some irrigation systems 

may not be Waters of the United States and thus discharges to those waters would not require 

NPDES permit coverage.

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, non-agricultural 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. Thus, 

stormwater runoff is either: (a) already required to obtain NPDES permit coverage as established 

in section 402(p) of the CWA or (b) classified as a discharge for which NPDES permit coverage 

is not currently required. The regulations that specify what types of stormwater require NPDES 

permits can be found in 40 CFR §122.26. 

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 

United States and generally represent the use patterns intended to be addressed by the 2006 rule 

that is now vacated. This permit does not cover, nor is permit coverage required, for pesticides 

applications that do not result in a point source discharge to Waters of the United States such as 

for the purpose of controlling pests on agricultural crops, forest floors, or range lands. However, 

the application of herbicides in Waters of the United States and the control of pests on plants 

grown in Waters of the United States, such as perennial obligate hydrophytes, is within the scope 

of coverage of this permit. This fact sheet does not identify every activity which may involve a 

point source discharge of pesticides to Waters of the United States that would require a permit; 

rather, the fact sheet focuses on the activities for which coverage under the PGP is available. 

The existence of this general permit does not alter the requirement that discharges of pesticides 

to Waters of the United States that are not covered by this permit be covered by an individual 

permit or another general permit.
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

9 

8. Publication of Draft Pesticide General Permit

 EPA published for purposes of public notice a draft NPDES pesticide general permit for 

point source discharges from the application of pesticides to Waters of the United States on June 

4, 2010 for four specific pesticide use patterns (75 FR 31775). The draft permit was developed 

to apply in all 10 EPA Regions in those areas where EPA remains the NPDES permitting 

authority. The federal register notice for the draft permit briefly summarized the requirements in 

the draft permit and also identified a list of issues for which EPA was specifically asking for 

comment. In general, those issues included: 

- Numbers, types, and sizes of entities that would be covered under this permit; 

- Other activities that should be covered under this permit and for those activities, the 

applicable requirements;

- Whether discharges to impaired waters and Tier 3 waters should be eligible for coverage 

under this permit and if so, the applicable requirements;

- Whether the draft permit is clear and if it provides a logical approach to the expected 

sharing of responsibilities; 

- Whether the Notice of Intent framework strikes an appropriate balance between capturing 

information on the largest applications and avoiding imposition of unreasonable burdens 

on smaller activities (and whether the thresholds for distinguishing between these two are 

appropriate); 

- Who should be required to implement integrated pest management practices, what 

specific practices should be required, and what type of guidance is necessary;

- Whether other parameters or narrative water quality based effluent limitations would be 

appropriate; 

- The value, feasibility, and safety of visual monitoring and how ambient water quality 

monitoring could be incorporated into the permit to assess compliance or to provide 

information that can be used to enhance the permit in the future; and 

- The scope of Operators required to submit annual reports and the type, level of detail, and 

practical utility of the information being requested. 

9. Public Meetings/Hearing Held on Draft Pesticide General Permit

 During the public comment period of the draft pesticide general permit, EPA held three 

public meetings (Albuquerque on June 14, 2010, Boise on June 16, 2010, and Boston on June 

21, 2010), one public hearing (Washington, DC on June 23, 2010), and a webcast (on June 24, 

2010) to provide an overview of the draft permit requirements and the basis for those 

requirements, and to answer questions about the draft permit and how the public can best assist 

EPA in the public comment process. Summaries of information presented at those meetings and 

comments received are included in the official docket for this permit (Docket ID No. EPA-HQOW-2010-0257 available at: www.regulations.gov). 

10. Public Comments Received on Draft Pesticide General Permit

EPA received 771 sets of written comments on the draft pesticide general permit. EPA 

has prepared a response to comments document which is available in the docket for this permit. 

Comments were used to inform EPA’s decision-making in finalizing this permit. This fact sheet 

does not discuss EPA’s rationale for changes made to the permit based on public comment. 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

10 

EPA’s responses to the comments, including the Agency’s rationale for changes to the permit, 

are reflected in the response to comment document also available in the docket for this permit 

(Docket ID No. EPA-HQ-OW-2010-0257 available at: www.regulations.gov). 

11. EPA’s Posting of a Pre-publication Draft of the Final PGP

 On April 1, 2011, EPA posted a pre-publication version of its draft final pesticide general 

permit for discharges of pesticide applications to U.S. waters. This draft final permit was not 

considered a “final agency action,” and the Agency did not solicit public comment on this draft 

final permit. EPA provided a preview of the draft final permit to assist states in developing their 

own permits and for the regulated community to become familiar with the permit’s requirements 

before it was to become effective. This reflected EPA’s commitment to transparency and 

responding to the needs of stakeholders. The pre-publication version of the draft final pesticide 

general permit underwent interagency review pursuant to EOs 12866 and 13563. The draft final 

permit posted on April 1, 2011 contains largely identical requirements to the final permit being 

published today. The principle change is the addition of conditions to protect listed species as a 

result of consultation with the National Marine Fisheries Service (NMFS) under the Endangered 

Species Act (ESA). There have also been changes to the timing of NOI submission deadlines and 

some additional clarifying changes, but these do not alter the intent of the pre-publication version 

posted in April.

12. ESA Consultation

The Endangered Species Act (ESA) of 1973 requires all Federal Agencies to ensure, in 

consultation with the U.S. Fish and Wildlife Service (FWS) and the National Marine Fisheries 

Service (NMFS) (together, the “Services”), that any Federal action carried out by the Agency is 

not likely to jeopardize the continued existence of any endangered species or threatened species 

(together, “listed” species), or result in the adverse modification or destruction of habitat of such 

species that is designated by the Services as critical (“critical habitat”). See 16 U.S.C. 

1536(a)(2), 50 CFR 402. When a Federal agency’s action “may affect” a protected species, that 

agency is required to consult with one or both of the Services, depending upon the endangered 

species, threatened species, or designated critical habitat that may be affected by the action (50 

CFR 402.14(a)). 

 To evaluate how the PGP would likely affect listed species and their critical habitat 

(together, “listed resources”), EPA prepared a Biological Evaluation (BE), a copy of which is 

available in the PGP administrative record (Docket ID No. EPA-HQ-OW-2010-0257 available 

at: www.regulations.gov), which concluded that in some instances the PGP “may affect” listed 

resources. EPA provided that BE to the Services on July 30, 2010. 

 On June 17, 2011, NMFS provided EPA with its Draft Endangered Species Act Section 7 

Consultation Biological Opinion on the U.S. Environmental Protection Agency’s Proposed 

Pesticides General Permit, ( draft Biological Opinion). That draft Biological Opinion tentatively 

concluded that the issuance of the PGP would jeopardize the continued existence of 33 listed 

species and result in the destruction or adverse modification of critical habitat that has been 

designated for 29 of those species. This draft Biological Opinion also included, a Reasonable and 

Prudent Alternative (RPA) intended to avoid the likelihood of jeopardizing the continued 

existence of any listed species or destruction or adverse modification of critical habitat. The 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

11 

species and habitat identified in NMFS’s draft Biological Opinion are identified in the PGP as 

“NMFS Listed Resources of Concern” as defined in Appendix A of the permit. The RPA was to 

be applicable in areas where the PGP overlaps with NMFS Listed Resources of Concern (i.e., 

portions of Idaho, Massachusetts, the District of Columbia, some tribal lands, and potentially for 

federal facilities in Delaware, Vermont and Washington). 

 EPA sought public comment on NMFS’ draft RPA, noticing, to the public, a 30-day 

request for comments on June 24, 2011. EPA received approximately 300 sets of written 

comments on the draft Biological Opinion and provided those comments to NMFS for their 

consideration in finalizing the Biological Opinion. Comments received on the draft BiOp are 

included in the administrative record for this permit (Docket ID No. EPA-HQ-OW-2010-0257 

available at: www.regulations.gov).

 On October 14, 2011, NMFS provided EPA with its final BiOp. The final PGP reflects 

the revisions to the draft permit that were made following consultation with NMFS and are 

designed to ensure that discharges allowed under the PGP are not likely to cause jeopardy to the 

continued existence of listed species and their critical habitat. These new permit provisions 

include eligibility criteria for permit coverage as well as requiring compliance with technologybased effluent limitations in Part 2.2 and recordkeeping and reporting requirements for Decisionmakers with discharges to Waters of the United States containing NMFS Listed Resources of 

Concern. The final PGP is consistent with the RPA set forth in NMFS’ final BiOp

 During ESA consultation, NMFS determined that it was appropriate to focus the list of 

resources of concern on certain listed species of salmonids, eulachon and sturgeon. NMFS 

determined that such resources of concern reside in approximately the middle third of the State 

of Idaho, the Merrimack and Connecticut Rivers in the State of Massachusetts and the Potomac 

River in Washington, D.C. There may also be some overlap with species on some tribal lands in 

the States of Washington, Oregon and California and some Federal facilities in Washington. 

 These new provisions of the PGP apply to Decision-makers in the limited areas where the 

NMFS Listed Resources of Concern, as defined in Appendix A of the permit, exist. EPA 

estimates that less than 2 % of the total number of Operators in the 6 states in which this PGP 

will apply may need to meet additional permit requirements than they would otherwise have to 

in order to meet the PGP's ESA related provisions. Such additional permit requirements include 

submittal of an NOI, implementing IPM-like practices, and submitting annual reports. Most of 

these Operators are small entities likely located in either Idaho or Massachusetts. Outreach 

efforts focused on assisting these small entities in determining whether they discharge to areas 

with resources of concern, whether they can be covered under this PGP, how to apply for permit 

coverage and what permit requirements they would be responsible for meeting will be elements 

included in the outreach and education efforts. In addition, EPA will develop a template to assist 

small operators in determining if they will discharge to Waters containing NMFS Listed 

Resources of Concern, and if so, how they can avoid adverse effects to those resources in order 

to obtain permit coverage. Information on such outreach activities will be available on EPA's 

NPDES website at www.epa.gov/npdes/pesticides.

 EPA notes that these new provisions were developed only for areas for which this PGP 

applies (all EPA authorized areas). The 44 states authorized to administer their own NPDES 

programs are not bound by the same ESA consultation requirements that bind EPA, and thus, 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

12 

these new permit terms are not federal NPDES requirements that the NPDES-authorized states 

must adopt. Some states may have their own endangered species related requirements under state 

law and these may be reflected in state permits.

 NMFS has issued four biological opinions on the authorization pursuant to FIFRA of the 

use of 24 pesticides. NMFS determined that the use of some of those pesticides was likely to 

jeopardize listed species or destroy or adversely modify designated critical habitat. NMFS 

included RPAs for the authorization of these pesticides in order to avoid likely jeopardy to those 

species or destruction or adverse modification of designated critical habitat. EPA understands 

that NMFS will consider this information when evaluating whether any discharges authorized by 

the PGP would be likely to have any adverse effects on listed resources.

A committee of the National Research Council (NRC) is examining scientific and 

technical issues related to the methods and assumptions used by the U.S. Environmental 

Protection Agency (EPA), the U.S. Fish and Wildlife Service (FWS), and the National Oceanic 

and Atmospheric Administration (NOAA) to conduct scientific assessments of ecological risks 

from pesticides registered by EPA under the Federal Insecticide, Fungicide, and Rodenticide Act 

(FIFRA) to species listed under the Endangered Species Act (ESA). The range of scientific 

studies needed to make such assessments will be considered, including ecological, agricultural, 

hydrological, toxicological, and exposure studies. The committee will develop conclusions 

reflecting the use of scientific principles and to facilitate a more holistic approach to assessing 

risks across the agencies, considering the intent of the ESA and of FIFRA. The expectation is 

that the NRC's conclusions would also be applied to the methods and assumptions used for 

scientific assessment of federal actions under the Clean Water Act to species listed under the 

ESA. See http://www8.nationalacademies.org/cp/projectview.aspx?key=49396. 

 For informational purposes, EPA is providing the following citations to four Biological 

Opinions issued by NMFS in recent years that evaluated specific pesticides.

• November 18, 2008, National Marine Fisheries Service Endangered Species Act Section 

7 Consultation Biological Opinion Environmental Protection Agency Registration of 

Pesticides Containing Chlorpyrifos, Diazinon, and Malathion at 

http://www.epa.gov/espp/litstatus/1st-biop.pdf 

• April 20, 2009, National Marine Fisheries Service Endangered Species Act Section 7 

Consultation Biological Opinion Environmental Protection Agency Registration of 

Pesticides Containing Carbaryl, Carbofuran, and Methomyl at 

http://www.epa.gov/oppfead1/endanger/litstatus/wtc/carbama-biop-4-20-09.pdf 

• August 31, 2010, National Marine Fisheries Service Endangered Species Act Section 7 

Consultation Biological Opinion Environmental Protection Agency Registration of 

Pesticides Containing Azinphos methyl, Bensulide, Dimethoate, Disulfoton, Ethoprop, 

Fenamiphos, Naled, Methamidophos, Methidathion, Methyl parathion, Phorate and 

Phosmet at http://www.epa.gov/oppfead1/endanger/litstatus/final-batch-3-opin.pdf
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

13 

June 30, 2011 National Marine Fisheries Service Endangered Species Act Section 7 

Consultation Biological Opinion Environmental Protection Agency Registration of Pesticides 

2,4-D, Triclopyr BEE, Diuron, Linuron, Captan, and Chlorothalonil at 

http://www.epa.gov/espp/litstatus/final-4th-biop.pdf.

EPA continues to be in consultation with FWS. Since EPA is issuing the PGP in response 

to a court decision vacating EPA’s 2006 NPDES Pesticides Rule, after October 31, 2011 and 

without coverage by an NPDES permit, certain discharges to Waters of the United States from 

the application of pesticides will be in violation of the Clean Water Act (CWA), and could be 

subject to citizen suits or enforcement actions. For these reasons, EPA has determined that it is 

of the utmost importance to issue the final PGP while consultation is pending. Once consultation 

is complete, EPA will modify this permit should the Agency find that the consultation 

demonstrates that different permit limits or additional conditions to protect listed species or 

critical habitat are warranted. Any such change would require public notice and an opportunity 

for comment. The current permit would remain in effect during those proceedings. 

EPA’s decision to issue this permit while consultation is ongoing is consistent with 

section 7(d) because its issuance does not foreclose either the formulation by the Services, or the 

implementation by EPA, of any alternatives that might be determined in the consultation to be 

necessary to comply with section 7(a)(2). If consultation reveals new information warranting 

different effluent limits or conditions to protect listed species or critical habitat, EPA plans to 

modify this permit under 40 C.F.R. §122.62(a)(2) to incorporate those limits or conditions. EPA 

may, as a result of completion of consultation with FWS, revoke the permit for use in areas 

where FWS determines the permit is likely to jeopardize the continued existence of listed species 

or adversely modify designated critical habitat. Should EPA opt to revoke the permit for reasons 

described above, Operators currently covered under the permit in those areas would be given a 

reasonable amount of time to seek coverage under an individual permit or other general permit 

consistent with provisions for permit revocation in 40 CFR Part 122.62. 

EPA has determined, moreover, that issuing this permit pending the completion of 

consultation is not likely to jeopardize the continued existence of listed species or adversely 

modify designated critical habitat. The attached memo, included in the administrative record for 

this permit (Docket ID No. EPA-HQ-OW-2010-0257 available at: www.regulations.gov), 

discusses in greater detail the conservative nature of the biological evaluation and why the 

proposed action under the PGP will lead to increased protection of and not be likely to jeopardize 

the continued existence of listed species or adversely modify designated critical habitat. 

13. Provisions in the Final PGP Added Following Consultation with NMFS

The following discussion summarizes the requirements in the permit added following 

consultation with NMFS, which are designed to ensure that discharges covered under this permit 

are not likely to adversely effect NMFS Listed Resources of Concern, except as provided in 

Criterion B, C, and, for 60 days, D, in part 1.1.2.4 of the permit.

EPA’s PGP requires anyone seeking permit coverage to determine if their pesticide 

discharges would be to Waters of the United States containing NMFS Listed Resources of 

Concern, as defined in Appendix A of the permit. The locations of NMFS Listed Resources of 

Concern are publicly available at www.epa.gov/npdes/pesticides. Any Decision-maker who 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

14 

discharges to Waters of the United States containing NMFS Listed Resources of Concern is 

required to: 

a. Submit a Notice of Intent (NOI) for coverage under the PGP;

b. Implement pest management measures to meet the technology-based effluent limitations 

that are based on IPM principles except those Decision-makers that will need to submit 

an NOI only because they discharge to Waters of the United States containing NMFS 

Listed Resources of Concern and that also comply with provisions in Part 1.6; and 

c. Submit annual reports.

NOIs for point source discharges to Waters of the United States containing NMFS Listed 

Resources of Concern are due at least 30 days prior to commencement of discharge to Waters of 

the United States except where pesticide applications are being made in response to a Declared 

Pest Emergency Situation, as identified in Appendix A of the permit. For those Declared Pest 

Emergency Situations, NOIs are due no later than 15 days after beginning discharge. Declared 

Pest Emergency Situations are eligible for permit coverage for a period of at least 60 days after 

beginning to discharge. Operators may continue to discharge after 60 days in these situations 

unless EPA notifies them that the discharge raises concern related to NMFS Listed Resources of 

Concern, in which case EPA will either direct that the discharge cease within the 60 day 

timeframe, or specify additional conditions to protected NMFS Listed Resources of Concern. 

Decision-makers can contact EPA or NMFS in advance of NOI submission to assess 

permit coverage eligibility for planned discharges to Waters of the United States containing 

NMFS Listed Resources of Concern. EPA expects this advance contact will help Decisionmakers determine if planned pesticide applications are or are not likely to cause adverse effects 

to listed species and if so, to identify steps that should be taken to ensure that such adverse 

effects do not occur. 

NOIs submitted for any point source discharge to Waters of the United States containing 

NMFS Listed Resources of Concern (except for those applications where: (1) consultation under 

ESA Section 7 has occurred already; (2) one of the Services issued a permit for “take” under 

ESA Section 10 action; (3) or the Decision-maker has written correspondence from NMFS that 

pesticide application activities performed consistent with appropriate measures will avoid or 

eliminate the likelihood of adverse effects) must include the following information: 

1. Description of the location of the pest management area in detail or a map of the location; 

2. Pest(s) to be controlled;

3. Pesticide product(s) to be discharged and method of application; 

4. Planned quantity and rate of discharge(s) for each method of application; 

5. Number of planned discharges;

6. Approximate date(s) of planned discharge(s); 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

15 

7. Rational supporting the determination whether the discharge is likely to adversely affect a 

NMFS Listed Resource of Concern, including a description of appropriate measures to be 

undertaken to avoid or eliminate the likelihood of adverse effects; and 

8. Signed certification by the Decision-maker consistent with the six criteria (A-F) outlined 

below. 

In the event an NOI is submitted for a Declared Pest Emergency Situation, the NOI must 

include information contained in items 1 through 7 listed above. Decision-makers must also 

include equivalent information in items 1 thorough 6, listed above, for those discharges that have 

already occurred for an NOI filed 15 days after beginning to discharge. 

EPA recognizes that implementation of pest management measures as specified in the 

permit may involve a degree of “adaptive management” such that exact timing and quantities of 

applications cannot be determined in advance for the duration of the permit. EPA expects the 

Decision-maker to provide the required information to the extent feasible and consistent with the 

implementation of the selected pest management measures.

EPA will notify NMFS immediately upon submission of any NOI that identifies 

discharges to Waters of the United States containing NMFS Listed Resources of Concern. 

NMFS will have 30 days from the NOI submission date to provide EPA with a determination as 

to whether it believes the eligibility criterion of “not like to adversely affect listed species or 

designated critical habitat,” has been met, could be met with conditions that NMFS specifies, or 

has not been met. EPA expects to rely on NMFS’ expertise with regard to NMFS Listed 

Resources of Concern when considering whether the prospective discharges would have any 

adverse effects on NMFS Listed Resources of Concern, and whether to withhold authorization. If 

NMFS does not provide EPA with this information within 30 days of EPA posting on the 

Internet receipt of a complete and accurate NOI, the discharges will be authorized 30 days after 

EPA posts on the Internet receipt of a complete NOI. EPA could, after receiving NMFS’ 

determination (or other issues raised by other parties) decide to place the NOI on hold (i.e., delay 

authorization to discharge) if necessary. EPA may authorize certain discharges in less than 30 

days, but no fewer than 10 days, for any discharges under Criterion B, C, or E of Part 1.1.2.4 of 

the permit (for which NMFS has already evaluated the effects of these discharges).

Annual reports submitted by the Decision-makers for these point source discharges to 

Waters of the United States containing NMFS Listed Resources of Concern will include the 

following information: 

a. A description of treatment area, including location and size, 

b. The approximate date of any discharge, 

c. Identification of any waters of the United States to which pesticide pollutants are 

discharged,

d. The pesticide use pattern resulting in any discharge,

e. Any target pest(s),
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

16 

f. Contact information for the decision-maker or any pesticide applicator, 

g. The total amount of each pesticide product applied for the reporting year by the 

application method,

h. If applicable, an annual report of any adverse incidents as a result of any discharge, and

i. If applicable, a description of any corrective action. 

EPA will collect and summarize these annual reports and provide such information to NMFS on 

an annual basis. 

The following outlines the criteria to determine if an Operator may be authorized for 

permit coverage consistent with the principle provisions of this permit relating to the protection of 

NMFS Listed resources of Concern.

A. Pesticide application activities will not result in a point source discharge to one or more 

Waters of the United States containing National Marine Fisheries Service (NMFS) Listed 

Resources of Concern, as defined in Appendix A, for this permit. In this case, no further 

certification is necessary. Decision-makers not otherwise required to submit an NOI are 

not required to do so merely to check Criterion A. However, Decision-makers who must 

submit an NOI anyway should check Criterion A if they do not discharge to a Water of 

the United States containing NMFS Listed Resources of Concern. 

B. Pesticide application activities will result in a point source discharge to one or more 

receiving Waters of the United States containing NMFS Listed Resources of Concern, as 

defined in Appendix A, but consultation with NMFS under section 7 of the ESA has been 

concluded for pesticide application activities covered under this permit. Consultations 

can be either formal or informal, and would have occurred only as a result of a separate 

federal action. The consultation addressed the effects of pesticide discharges and 

discharge-related activities on federally-listed threatened or endangered species and 

federally-designated critical habitat, and must have resulted in either:

i. A biological opinion from NMFS finding no likely jeopardy to listed species and no 

destruction/adverse modification of federally-designated critical habitat; or

ii. Written concurrence from NMFS with a finding that the pesticide discharges and 

discharge-related activities are not likely to adversely affect federally-listed species or 

federally-designated critical habitat.

C. Pesticide application activities will result in a point source discharge to one or more 

Waters of the United States containing NMFS Listed Resources of Concern, as defined 

in Appendix A, but any “take” of these resources associated with such pesticide 

application activities has been authorized through NMFS’ issuance of a permit under 

section 10 of the ESA, and such authorization addresses the effects of the pesticide 

discharges and discharge-related activities on federally-listed species and federallydesignated critical habitat. (The term "take" means to harass, harm, pursue, hunt, shoot, 

wound, kill, trap, capture, or collect, or to attempt to engage in any such conduct. See 

Section 3 of the Endangered Species Act, 16 U.S.C. § 1532(19).) 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

17 

D. Pesticide application activities were, or will be, discharged to one or more Waters of the 

United States containing NMFS Listed Resources of Concern, as defined in Appendix A, 

but only in response to a Declared Pest Emergency Situation. Decision-makers must 

provide EPA with their rationale supporting the determination whether the discharge is likely 

to adversely affect listed species, including the description of appropriate measures to be 

undertaken to avoid or eliminate the likelihood of adverse effects.

E. Pesticide application activities for which permit coverage is being requested in the NOI 

will discharge to one or more Waters of the United States containing NMFS Listed 

Resources of Concern, as defined in Appendix A. Eligible discharges include those where 

the Operator includes in the NOI written correspondence from NMFS that pesticide 

application activities performed consistent with appropriate measures will avoid or 

eliminate the likelihood of adverse effects.

F. Pesticide application activities for which permit coverage is being requested in the NOI 

will discharge to one or more Waters of the United Stated containing NMFS Listed 

Resources of Concern, as defined in Appendix A. Eligible discharges include those from 

pesticide application activities that are demonstrated by the operator as not likely to 

adversely affect federally-listed species or their designated critical habitat or that the pest 

poses a greater threat to the NMFS Listed Resources of Concern than does the discharge 

of the pesticide. Operators must provide EPA with their documentation demonstrating 

the basis for their finding. 

Criteria E and F, at least 30 days prior to beginning to discharge, require an operator to 

demonstrate: 

- Pesticides being discharged or to be discharged are known not to cause adverse effects, or 

are or will be discharged at concentrations determined not to cause adverse effects, to 

NMFS Listed Resources of Concern (Criterion F), or

- NMFS Listed Resources of Concern are or will not be exposed to pesticide pollutants 

produced by the discharge (e.g., species will not occur in the discharge area during that 

time of year, the species will not be present in the hydrologic unit in which the discharge 

will occur, the species is not present because of the presence of the pest being controlled, 

etc) (Criterion F), or 

- Other considerations that demonstrate the discharge is not likely to adversely affect 

NMFS Listed Resources of Concern (Criterion F), or

- They have obtained written correspondence from NMFS indicating that pesticide application 

activities performed consistent with appropriate measures will avoid or eliminate the 

likelihood of adverse effects to Listed Resources of Concern. Eligibility under this criterion is 

contingent upon the Decision-maker following the measures described in correspondence 

from NMFS designed to avoid or eliminate the likelihood of adverse effects (Criterion E). 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

18 

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 that each Region will 

sign and issue the permit and include in that issuance CWA Section 401 certification language 

for areas in their Region covered by the permit. 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, territories, Indian Country lands, or 

federal facilities) in all ten EPA Regions. 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 

Oklahoma Department of Environmental Quality (ODEQ), who is the NPDES permitting 

authority, currently does not have the authority to administer the NPDES program for the types 

of pesticide discharges covered under this permit. Pursuant to Oklahoma state law, Oklahoma's 

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

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

authorized to administer the NPDES program, the state does not have the authority to issue 

permits for discharges from the application of biological pesticides or chemical pesticides. Thus, 

EPA’s PGP covers discharges in the State of Oklahoma.

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

of the United States 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 (but not necessarily in the same way as in this permit). 

States are free to incorporate additional or different 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. 

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; 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

19 

generally, the term permittee is specific to the period of time that an Operator or contractor is 

actually 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) monitoring, (5) 

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

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

applicable to specific states, Indian country lands, or territories. Additionally, the permit 

includes seven appendices with additional conditions and guidance for permittees: (A) 

definitions, abbreviations, and acronyms, (B) standard permit conditions, (C) areas covered, (D) 

Notice of Intent Form, (E) Notice of Termination Form, (F) Pesticide Discharge Evaluation 

Worksheet, and (G) Annual Report Template. 

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 Operators 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 those Operators who are defined as Decisionmakers to document, among other things, how Pest Management Measures will be implemented 

to comply with the permit’s effluent limitations.

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.
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

20 

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

minimize the discharge of pesticides to Waters of the United States from the application of 

pesticides. Consistent with the control level requirements of the CWA, the term “minimize” 

means to reduce and/or eliminate pesticide discharges to Waters of the United States through the 

use of Pest Management 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 Applicators and addresses the general requirement to minimize discharges from application 

of pesticides. In this part, all Applicators must minimize discharges of pesticides by using only 

the amount of pesticide product per application and frequency of pesticide applications necessary 

to control the target pest, performing regular maintenance activities, calibrating and 

cleaning/repairing application equipment, and assessing weather conditions in the treatment area. 

The second part requires certain Decision-makers to implement pest management measures that 

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 the 

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, 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 requirements that the permit does not cover discharges of any pesticide into a water 

impaired by a substance which either is an active ingredient in that pesticide or is a degradate of 

such an active ingredient, or into a Tier 3 water (except for pesticide applications made to restore 

or maintain water quality or to protect public health or the environment that either do not degrade 

water quality or only degrade water quality on a short-term or temporary basis). While not 

specifically framed as effluent limitations, these eligibility conditions further help to protect 

water quality on a water-body-specific basis.

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 Decision-makers that must submit an NOI and that 

are large entities to prepare a PDMP to document the implementation of Pest Management 

Measures being used to comply with the effluent limitations set forth in Parts 2.0 and 3.0. A 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

21 

large entity, as defined in Appendix A of the permit, is (1) a public entity that serves a population 

greater than 10,000 people or (2) a private enterprise that exceeds the Small Business 

Administration “size standards” as provided in 13 CFR 121.201. 

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

discharge management team information; (2) problem identification; (3) pest management 

options evaluation; (4) response procedures pertaining to spills and adverse incidents; (5) 

documentation to support eligibility considerations under other federal laws, and (6) signature 

requirements. 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 Pest Management Measures to 

meet the effluent limitations in this permit, the Pest Management 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 Pest Management 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 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 

 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.
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

22 

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 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 United States Fish and 

Wildlife Service (FWS) 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 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 “Operator” in Appendix A of the permit that is intended to clarify this 

point, focusing on the fact that Operator control exists both at the “Decision-maker” level about 

how to control pests, including financial considerations, as well as at the pesticide Applicator” 

level (such as calibration of pesticide application equipment). In these instances, both Operators, 

i.e., the Decision-Maker and the Applicator, are required to obtain NPDES permit coverage; 

however, the permit strives to minimize any potential duplication of effort by identifying which 

Operator is responsible for certain permit conditions. The final permit clarifies these 

responsibilities by identifying whether EPA expects these activities to be performed by all 

Operators, or just the Decision-maker or the Applicator.

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, entities are likely not 

an Operator if, for example, they own the land, but the activities are being performed outside of 

their control (e.g., a public entity is spraying for mosquitoes over private property, or a private 

party is spraying for weeds on public lands leased from the federal government).
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

23 

 EPA encourages Operators to use already prepared information and explore possible cost 

savings by sharing responsibilities for implementing aspects of this permit. For example, a 

mosquito control district may have developed something for their FIFRA program and they 

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. 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 should 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

1.1.1 Activities Covered

 Only Operators meeting the eligibility requirements outlined in the PGP may be covered 

under the permit. If an Operator does not meet the eligibility provisions described in Part 1.1 of 

the PGP, the Operator’s point source discharges to Waters of the United States from the 

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

coverage under another permit or the Clean Water Act exempts these discharges from NPDES 

permit requirements. The activities covered by this permit generally include the use patterns and 

types of pest control activities described in the vacated 2006 NPDES Pesticides Rule. As was 

discussed in that rule, agricultural stormwater and irrigation return flow are exempt from NPDES 

permits. Also, applications that do not reach Waters of the United States do not need permit 

coverage. Thus, the final PGP, consistent with the permit as proposed, covers the discharge of 

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

United States resulting from the following use patterns: (1) Mosquito and Other Flying Insect 

Pest Control; (2) Weed and Algae Control; (3) Animal Pest Control; and (4) Forest Canopy Pest 

Control as summarized below: 

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 Waters of the United States. 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 often are performed several times per year. 

Weed and Algae Pest Control

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

to control vegetation and algae (and plant pathogens such as fungi) in Waters of the 

United States and at water’s edge, including ditches and/or canals. Applications of this 

nature typically are single spot pesticide applications to control infestations or staged 

large scale pesticide applications intended to control pests in several acres of waterway. 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

24 

Pesticide applications in a treatment area may be performed one or more times per year to 

control the pest problem.

Animal Pest Control

This use pattern includes the application, by any means, of pesticides into Waters of the 

United States to control a range of animal pests for purposes such as fisheries 

management, invasive species eradication or equipment operation and maintenance. 

Applications of this nature are often made over an entire or large portion of a waterbody 

as typically the target pests are mobile. Multiple pesticide applications to a waterbody 

for animal pest control are often made several years apart.

Forest Canopy Pest Control

This use pattern includes pest control projects in, over, or to forest canopies (aerially or 

from the ground) to control pests in the forest canopy where Waters of the United States 

exist below the canopy. Applications of this nature usually occur over large tracts of 

land, and are typically made in response to specific pest outbreaks. EPA understands that 

for this use pattern pesticides will be unavoidably discharged into Waters of the United 

States in the course of controlling pests over a forest canopy as a result of pesticide 

application. 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 are applied to forest canopies, and this application is 

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

 Prior to initiating the 2006 NPDES Pesticides Rule, the Agency had interpreted the Clean 

Water Act and its implementing regulations as not requiring an 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 application of insecticides to a forest 

canopy. 71 Fed. Reg. at 68,482. In 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. 

Therefore, the holding of National Cotton Council has overtaken the 2003 General Counsel 

Memorandum as well as the 2006 rule. Other Courts have issued decisions consistent with 

National Cotton Council. Northwest Envt’l Def. Ctr. v. Brown, 617 F.3d 1176, 1191 (9th Cir. 

2010) (“the [silviculture] exemption ceases to exist as soon as the natural runoff is channeled and 

controlled in some systematic way through a ‘discernible, confined and discrete conveyance’ and 

discharged into waters of the United States”); Peconic Baykeeper v. Suffolk Cty., 600 F.3d 180, 

189 (2nd Cir. 2010) (holding that trucks and helicopters that spray pesticides are point sources 

under the CWA.) Thus, point source discharges to Waters of the United States from pesticides 

applied for forest pest control activities need to obtain an NPDES permit. 

As discussed above, EPA’s decision to include specific use patterns in this PGP generally 

stems from the Agency’s 2006 NPDES Pesticides 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:

1) The application of pesticides directly to Waters of the United States in order to 

control pests. Examples of such applications include applications to control mosquito 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

25 

larvae, aquatic weeds, or other pests that are present in the Waters of the United 

States. 

2) The application of pesticides to control pests that are present over Waters of the 

United States, including near such waters, where a portion of the pesticides will 

unavoidably be deposited into Waters of the United States in order to target pests 

effectively; for example, when insecticides are aerially applied to a forest canopy 

where Waters of the United States may be present below the canopy or when 

pesticides are applied over or near water for the control of adult mosquitoes or other 

pests.

However, as a result of the 6th Circuit Court’s decision, what did not require an NPDES 

permit in the 2006 rule, does require an NPDES permit now. 

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

beneficial purpose of controlling pests. In promulgating the 2006 NPDES Pesticides 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 Waters of the United States – or 

applications of pesticides to terrestrial agricultural crops where runoff from the crop, either as 

irrigation return flow or from stormwater, discharges into Waters of the United States.

Consistent with the 2006 NPDES Pesticides Rule, this PGP does not cover spray drift 

resulting from pesticide applications. Instead, to address spray drift, EPA established a multistakeholder workgroup under the Pesticides Program Dialogue Committee (PPDC), an advisory 

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

issues relating to spray drift. The goals of the workgroup are to: (1) improve the understanding 

of the perspectives of all stakeholders regarding pesticide spray drift; (2) find common ground 

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

pesticide spray drift; (3) develop options for undertaking work where common ground exists; 

and (4) explore 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 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 under the CWA. 

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

assumes that most if not all chemical pesticides will leave a residual once the product has 

performed its intended purpose, unless the Operator can show otherwise. 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

26 

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 Waters of the United States to 

control pests over the water, any amount of the pesticide that falls into Waters of the 

United States 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 Waters of the United States will fall 

directly into such waters and thus assumes that applications will trigger the 

requirement for an NPDES permit. A permit is not necessary if no portion of a 

chemical pesticide applied over Waters of the United States will fall into those 

waters.

2. If the application of a chemical pesticide is made into Waters of the United States to 

control a pest in such waters, once the pesticide no longer provides any pesticidal 

benefit, any amount of the pesticide that remains in those waters is a “residual” and

would require coverage by an NPDES permit. Additionally, as the Sixth Circuit 

reasoned, the residual is discharged at the time of a pesticides initial application. 

Based on field studies of pesticides applied into water, the Agency expects that some 

portion of every application of a pesticide made into Waters of the United States will 

leave a residual in those waters and thus assumes every application will trigger the 

requirement for an NPDES permit. EPA expects that an entity applying pesticides 

with a discharge to Waters of the United States who wishes to dispute this assumption 

would be expected to provide scientific data supporting such a determination. Such 

data should 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 would not be necessary if it is determined that a 

residual did not enter Waters of the United States.

3. This permit authorizes discharges associated with four categories of pesticide 

application activities: mosquito and other flying insect pest control, weed and algae 

pest control, animal pest control, forest canopy pest control. As noted above, only 

point source discharges of pollutants to Waters of the United require a permit, and it 

is beyond the scope of this Fact Sheet to identify all specific activities that do or do 

not require a permit. However, to the extent that activities that fall within the four 

covered categories require a permit, they can be authorized by this general permit if 

all eligibility requirements are met. For example, discharges to control pests in or 

near areas that are Waters of the United States, even when these areas are dry for 

much of the year, may be covered by this permit, if one is required. This would 

include discharges on forest or range lands that include dry washes and ephemeral 

streams, to control pests that may be found in these occasionally wet areas, including 

pests that may also be found in upland areas. For two of the categories, weed and 

algae pest control and animal pest control, the permit specifies that covered activities 

include applications to control pests “in water and at water’s edge.” EPA intends for 

the phrase “at water’s edge” to allow coverage of activities targeting pests that are not 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

27 

necessarily “in” the water but are near the water such that control of the pests may 

unavoidably involve a point-source discharge of pesticides to Waters of the United 

States. The category forest canopy pest control is for applications to a forest canopy. 

EPA intends that this can include both mature and immature forest canopies, 

including canopies that may not be continuously connected, where control of pests 

associated with the canopy (i.e., branches and leaves of the trees) may unavoidably 

involve point source discharges of pesticides to Waters of the United States.

 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(b)], biochemical 

pesticides [40 CFR 158.2000(a)(1)] and plant-incorporated protectants. [40 CFR 174.3] 

How the Court’s Decision Expands the NPDES Program 

EPA estimates that nationwide approximately 365,000 Applicators perform 5.6 million 

applications a year for the four use patterns covered under the PGP. EPA’s general permit 

covers only six of the fifty states (plus many other smaller areas, such as most United States 

territories and Indian Country lands). EPA assumes approximately 10 percent of pesticide 

applications will occur in the areas covered under EPA’s general permit 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-issued NPDES permits. If each 

Applicator requires NPDES permit coverage, this represents an approximately 70 percent 

increase in the total number of NPDES permittees covered under the entire NPDES program (an 

increase from EPA’s current estimate of 565,000 permittees annually to 930,000 permittees 

annually). 

EPA recognizes that there are many site-specific situations which will determine whether 

a pesticide application operation needs permit coverage. EPA is not attempting to define all such 

situations in this Fact Sheet. Additionally, 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 United States. 

However, the Agency does want to make it clear that to the extent pesticide application 

operations need permit coverage, this permit is available for the four pesticide use categories. 

Thus, to the extent that a permit is needed for discharges from pesticide applications to 

rangelands, forestry, park lands, rights-of-way, wetlands and other areas, and the activity falls 

within one of the four use categories, coverage can be granted under this general permit. 

Additionally, as described in Part I.6 of this fact sheet, 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.

 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 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

28 

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 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. Discharges to waters which are impaired for a substance which is not an 

active ingredient in that pesticide or a degradate of such an active ingredient are eligible for 

coverage. Discharges to waters impaired for temperature or some other indicator parameter, or 

for physical impairments such as “habitat alteration” are also eligible for PGP coverage, unless 

otherwise notified by EPA. Conversely, the permit is not available for the discharge of any 

pesticide to water that is impaired for a substance that is an active ingredient in that pesticide or a 

degradate of such an active ingredient. 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 

a different pesticide active ingredient.

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

for all impaired waters regardless of the impairment. In fact, the application of a pesticide to 

water in some instances actually improves 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 that have been identified by a 

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

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). While, it is EPA’s opinion that the 303(d) list is not a final 

determination of impairments, it is the best available information and Operators should use it 

when deciding whether their discharges meet the eligibility requirements regarding waterbodies 

impaired for specific pesticides. Thus, these requirements 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 active ingredient or degradate of that 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

29 

active ingredient, EPA is providing 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 pesticide active ingredients or degradates 

of such. Additional discussion of existing impairments identified for which pesticides are 

identified as the source of the impairment is provided in Part III.3 of this fact sheet.

1.1.2.2 Discharges to Waters Designated as Tier 3 for Antidegradation Purposes

States and tribes provide the most stringent level of antidegradation protection, i.e., Tier 3 

protection, to outstanding national resource waters. These waters are often regarded as the 

highest quality Waters of the United States, but the Tier 3 designation also provides special 

protection for waters of exceptional ecological significance, i.e., those which are important, 

unique, or sensitive ecologically. Except for certain temporary changes, Tier 3 protection means 

that water quality cannot be lowered in such waters. In broad terms, EPA’s view of “temporary” 

is weeks and months, not years. States and tribes make the decision of which water bodies to 

designate as Tier 3. A list of Tier 3 waters in areas where the PGP is available can be accessed 

on the Internet at www.epa.gov/npdes/pesticides. EPA proposed in the draft PGP that Tier 3 

waters not be eligible for coverage; rather, such discharges would be required to obtain coverage 

under an individual permit. 

EPA received many comments on the draft permit indicating that time sensitive pesticide 

applications to Tier 3 waters are routinely performed and quick response is needed to preserve 

the outstanding quality of these Tier 3 waters and/or to protect public health near these waters. 

Several commenters stated that having to go through the more timely individual permit process 

would complicate the ability to control pests in a timely manner as is needed to minimize the 

environmental effects and costs of these pest problems. Several commenters noted that 

pesticides have been discharged to these waters for many years without negatively impacting 

those waters. In light of these comments, and in recognition of the fundamental purpose of water 

quality standards (“to protect the public health or welfare, enhance the quality of water and serve 

the purposes of this chapter,” as stated in Section 303(c)(2) of the Clean Water Act), the final 

PGP provides permit coverage for discharges made to restore or maintain water quality or to 

protect public health or the environment that either do not degrade water quality or only degrade 

water quality on a short-term or temporary basis. This is consistent with EPA’s longstanding 

view that “[s]tates may allow some limited activities which result in temporary and short-term 

changes in water quality. Such activities are considered to be consistent with the intent and 

purpose of [a Tier 3 water].” 48 FR 51400, 51403 (1983). 

EPA is imposing additional documentation and reporting requirements for discharges to 

Tier 3 waters. See Part 5.1.2 of the permit. Any Decision-maker proposing to discharge to a 

Tier 3 water must submit a Notice of Intent consistent with Part 1.2.2 of the PGP. NOIs for such 

discharges are required to identify the Tier 3 water by name, and provide a discussion of the 

environmental problem and demonstration that the pesticide discharge is necessary to protect 

water quality, the environment, and/or public health. This NOI requirement includes the 

requirement for any Decision-maker already covered under the PGP who wants to discharge to a 

Tier 3 water at a later date, to submit an updated NOI containing the information identified 

above for discharges to Tier 3 waters. Additionally, NOIs for any discharges to Tier 3 waters 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

30 

must be submitted at least 10 days before beginning discharge unless discharges are in response 

to a Declared Pest Emergency Situation, in which case, an NOI is due for such discharges no 

later than 15 days after beginning discharge (if water contains NMFS Listed Resource of 

Concern) or 30 days after beginning discharge (if no NMFS Listed Resource of Concern). 

Discharges to Tier 3 waters are authorized for permit coverage through January 12, 2012 without 

submission of an NOI. For any discharges to Tier 3 waters after January 12, 2012, Decisionmakers are required to submit an NOI consistent with the earliest due date identified in Table 1-2 

of the permit.

Of note, 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 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 does not restrict eligibility for 

discharges to Tier 2.5 waters; rather, EPA expected States and Tribes to further limit such 

discharges as the States and Tribes deemed necessary through the CWA §401 certification 

process, the results of which are detailed in Part 9 of the general permit.

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 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). 

1.1.2.4 Endangered and Threatened Species and Critical Habitat Protection

 As a result of consultation with NMFS EPA has added the following conditions to the 

permit to protect NMFS Listed Resources of Concern. Part 1.1.2.4.Part 1.1.2.4 requires the 

Operator to certify that they are eligible for permit coverage under one of the six criteria (A-F) as 

follows: 

Criterion A. Pesticide application activities will not result in a point source discharge to 

one or more Waters of the United States containing National Marine Fisheries Service 

(NMFS) Listed Resources of Concern, as defined in Appendix A, for this permit. In this 

case, no further certification is necessary. Decision-makers not otherwise required to 

submit an NOI are not required to do so merely to check Criterion A. However, Decision-
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

31 

makers who must submit an NOI anyway should check Criterion A if they do not 

discharge to a Water of the United States containing NMFS Listed Species of Concern. 

Criterion B. Pesticide application activities will discharge to one or more receiving 

Waters of the United States containing NMFS Listed Resources of Concern, as defined in 

Appendix A, but consultation with NMFS under section 7 of the ESA has been concluded 

for pesticide application activities covered under this permit. Consultations can be either 

formal or informal, and would have occurred only as a result of a separate federal action. 

The consultation addressed the effects of pesticide discharges and discharge-related 

activities on federally-listed threatened or endangered species and federally-designated 

critical habitat, and must have resulted in either:

i. A biological opinion from NMFS finding no likely jeopardy to listed 

species and no destruction/adverse modification of federally-designated critical 

habitat; or

ii. Written concurrence from NMFS with a finding that the pesticide 

discharges and discharge-related activities are not likely to adversely affect 

federally-listed species or federally-designated critical habitat.

Criterion C. Pesticide application activities will discharge to one or more Waters of the 

United States containing NMFS Listed Resources of Concern, as defined in Appendix A, 

but any “take” of these resources associated with such pesticide application activities has 

been authorized through NMFS’ issuance of a permit under section 10 of the ESA, and 

such authorization addresses the effects of the pesticide discharges and discharge-related 

activities on federally-listed species and federally-designated critical habitat. (The term 

"take" means to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect, or 

to attempt to engage in any such conduct. See Section 3 of the Endangered Species Act, 

16 U.S.C. § 1532(19).) 

Criterion D. Pesticide application activities were, or will be, discharged to one or more 

Waters of the United States containing NMFS Listed Resources of Concern, as defined in 

Appendix A, but only in response to a Declared Pest Emergency Situation. Decisionmakers must provide EPA with their rationale supporting the determination whether the 

discharge is likely to adversely affect NMFS Listed Resources of Concern, including the 

description of appropriate measures to be undertaken to avoid or eliminate the likelihood of 

adverse effects.

Criterion E. Pesticide application activities for which permit coverage is being 

requested in the NOI will discharge to one or more Waters of the United States 

containing NMFS Listed Resources of Concern, as defined in Appendix A. Eligible 

discharges include those where the Decision-maker includes in the NOI written 

correspondence from NMFS that pesticide application activities performed consistent 

with appropriate measures will avoid or eliminate the likelihood of adverse effects.

Eligibility under this criterion is contingent upon the Decision-maker following the measures 

described in correspondence from NMFS designed to avoid or eliminate the likelihood of 

adverse effects.
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

32 

Criterion F. Pesticide application activities for which permit coverage is being 

requested in the NOI will discharge to one or more Waters of the United Stated 

containing NMFS Listed Resources of Concern, as defined in Appendix A. Eligible 

discharges include those from pesticide application activities that are demonstrated by the 

Decision-maker as not likely to adversely affect NMFS Listed Resources of Concern or 

that the pest poses a greater threat to the NMFS Listed Resources of Concern than does 

the discharge of the pesticide. Decision-makers must provide EPA with their 

documentation demonstrating the basis for their finding. 

Any Decision-maker proposing to discharge to Waters of the United States containing 

NMFS Listed Resources of Concern, as defined in Appendix A of the permit, must submit a 

Notice of Intent consistent with Part 1.2.2 of the PGP. The specific requirements of the PGP NOI 

are identified in the NOI form provided in Appendix D of the permit. Also, refer to Appendix F 

of the PGP factsheet for the ESA Review Procedures to determine eligibility prior to submittal of 

the NOI. This NOI requirement includes the requirement for any Decision-maker already 

covered under the PGP who discharges to any Waters of the United States containing NMFS 

Listed Resources of Concern, as defined in Appendix A of the permit, that were not identified in 

a previously submitted NOI, to submit an updated NOI containing the information identified in 

Appendix D of the permit. Additionally, NOIs for any discharges to Waters of the United States 

containing NMFS Listed Resources of Concern, as defined in Appendix A of the permit, must be 

submitted at least 30 days before beginning discharge. EPA may authorize certain discharges in 

less than 30 days, but no fewer than 10 days, for any discharges under Criterion B, C, or E of 

Part 1.1.2.4 of the permit (for which NMFS has already evaluated the effects of these discharges.

Where eligibility is determined consistent with Criterion D, response to a Declared Pest 

Emergency Situation, an NOI is due for such discharges no later than 15 days after beginning 

discharge.

1.2 AUTHORIZATION TO DISCHARGE UNDER THIS PERMIT

1.2.1 How to Obtain Authorization

The NPDES general permit regulations, at 40 CFR §122.28(b)(2), require that Operators 

submit a Notice of Intent (NOI) to obtain coverage under an existing general permit for which 

that discharge is eligible. However, those regulations, at §122.28(b)(2)(v), provide that at the 

discretion of the Director (which, for the PGP, is EPA), certain discharges can be authorized 

under a general permit without submitting an NOI where EPA finds that an NOI would be 

inappropriate for such discharges. In making such a finding, EPA must consider the following 

criteria: 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. As described below, EPA is requiring submission of an NOI for certain 

discharges and is providing automatic coverage for certain other discharges for which EPA 

determined it would be inappropriate to require an NOI. EPA is exempting Operators of 

pesticide research and development activities from the need to submit an NOI because these 

activities are typically smaller and in many instances, are already covered under FIFRA’s 

Section 5 (experimental use permits). Similarly, the permit exempts these activities from many 

requirements of the permit where such activities are inconsistent with the research plan.
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

33 

As identified in Part III.1.1.1 of the fact sheet, EPA expects a large number of discharges 

from the application of pesticides spanning a wide range of Operators and activities will require 

NPDES permit coverage. EPA’s consideration of the regulatory criteria in §122.28(b)(2)(v) is as 

follows: 

Type and expected nature of discharge

All discharges authorized by this general permit involve either (1) applications made directly to 

or over Waters of the United States to control pests in or over the water, or (2) applications to 

control pests near water such that pesticides will be unavoidably deposited into Waters of the 

United States. 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 four use patterns described in Part III.1.1. EPA evaluated each use 

pattern independently with the goal of identifying the significant activities resulting in discharges 

that should be covered under this PGP. 

Potential for toxic and conventional pollutants in the discharge

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 

impacts from high concentrations of toxic or conventional pollutants in the discharge would be 

smaller when fewer acres or linear feet are treated.

Expected volume of discharge

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 Pest Management 

Measures used by Operators 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, minimizing the discharge of pesticide product necessary to manage pests successfully 

will vary among Operators depending on which Pest Management 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.

Other means to identify discharges

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, and other information submitted by pesticide dischargers pursuant to federal or 

state law. However, EPA recognizes that the availability and quality of these data may be 

limited and highly variable across the scope of activities and areas covered under the PGP. 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

34 

Number of discharges

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 discharges which may be covered by the 

permit is unknown, EPA estimates that the PGP covers more than 35,000 dischargers per year in 

the states for which EPA is the permitting authority. Of this total, a large majority represent 

dischargers performing small pesticide applications that EPA considers to have very low 

potential for impact (such as herbicide applications to short sections of ditches or canal banks). 

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

authorities and permittees alike. Also, EPA received many comments that indicated For-Hire 

Applicators apply to many small areas throughout different pest management areas, and 

requiring an NOI from them for certain activities would be duplicative of Decision-maker 

requirements. This would likely confuse For-Hire Applicators who are generally very small 

businesses, and would not provide meaningful information on identification of pest management 

areas.

In analyzing these regulatory criteria, the Agency 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 to be covered under the permit, EPA found a logical 

break between entities applying pesticides to larger areas versus smaller areas, and a difference 

between the types of entities generally responsible for performing such pest control activities. 

As a result, NOI requirements are based on the size of areas treated and the entity making the 

decision to perform pesticide applications. In addition, EPA identified a need for additional 

information for any discharges to outstanding national resource waters (Tier 3 waters) and to 

Waters of the United States containing NMFS Listed Resources of Concern, as defined in 

Appendix A of the permit, and is including NOI requirements for all discharges to these waters 

as well.

1.2.2 Decision-makers Required to Submit an NOI

 

To obtain authorization under the PGP, Operators must meet the Part 1.1 eligibility 

requirements, and only if required by Part 1.2.2, also submit a complete and accurate NOI no 

later than the appropriate deadline described in Part 1.2.3. Decision-makers who are required to 

submit an NOI, but are discharging between October 31, 2011 and January 12, 2012, must begin 

complying with Part 2.2 requirements as of October 31. 2011. 

Table 1-1 in Part 1.2.2 of the permit identifies which Decision-makers are or will be 

required to submit an NOI. Based on the analysis outlined in Part 1.2.1 above, EPA has 

determined that it is inappropriate to require For-Hire Applicators, who are not Decision-makers 

as defined in Appendix A of the permit, to submit NOIs. EPA has further determined that 

Decision-makers who apply pesticides to relatively small areas should not be required to submit 

NOIs. Therefore, EPA is exercising its discretion and not requiring these Operators to submit 

NOIs (except for certain Operators that the Agency believes have a significant role in pest 

control for public health and environmental protection and should be expected to provide 

Agency notice of such activities). Nonetheless, EPA emphasizes that even if an NOI is not 

required, these Operators are covered automatically under this permit and are still subject to all 

applicable requirements contained within the permit. EPA is requiring NOIs from the following 

types of Decision-makers:
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

35 

- Decision-makers exceeding an annual treatment area threshold;

- Other Decision-makers specifically in the business of pest control; 

- Decision-makers discharging to Tier 3 waters; and

- Decision-makers discharging to Waters of the United States containing NMFS Listed 

Resources of Concern, as defined in Appendix A of the permit. 

A more detailed discussion of EPA’s rationale for requiring NOIs for these three 

categories of Decision-makers follows.

NOIs for Decision-Makers Exceeding an Annual Treatment Area Threshold

 EPA developed annual treatment area thresholds for each use pattern that will only 

require larger Operators applying pesticides to larger areas to submit an NOI. To determine the 

appropriate annual treatment area thresholds that would trigger the NOI requirement, EPA’s 

Office of Water, Office of Chemical Safety and Pollution Prevention (formerly the Office of 

Pesticides, Pollution, and Toxic Substances) and the ten EPA Regional Offices engaged in 

discussions with USDA, states as co-regulators, and representatives from industry including 

pesticide registrants, applicators, and land managers. EPA also solicited and received some 

comments on the draft PGP on appropriate threshold values to use for NOI submission. Based 

on these discussions, the comments received, and EPA’s best professional judgment, EPA 

developed annual treatment area thresholds that establish NOI requirements for applications to 

larger areas, which are believed to have the greatest potential for impact to Waters of the United 

States. 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 relying heavily on its best 

professional judgment in setting the NOI annual treatment area thresholds for each of the use 

patterns. If a Decision-maker, otherwise not required to submit an NOI, anticipates it will 

exceed an applicable annual treatment area threshold during any time in a given calendar year of 

the permit cycle, that Decision-maker must then submit an NOI consistent with the due dates 

described in Part 1.2.3. 

When calculating the size of the treatment area for comparing to an annual treatment area 

threshold, EPA uses the term “at water’s edge adjacent to Waters of the United States” to 

identify those areas where pesticides are applied to control pests that are present near water 

where a portion of the pesticides will unavoidably be deposited to the water to target the pests. 

EPA’s use of the word “adjacent” in identifying these areas is merely used to identify areas near 

Waters of the United States and is not intended to mean “adjacent” as defined in regulation for 

use when defining the term “Waters of the United States.” 

 To avoid duplication of submission, EPA is requiring that the Decision-maker 

responsible for such applications be the Operator required to submit the NOI. So, where a 

Decision-maker hires an Applicator to perform the pest control activities, the NOI is to be 

submitted by the Decision-maker.

EPA’s rationale for the annual treatment area threshold and Decision-makers required to 

submit NOIs for each use pattern is as follows:
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

36 

Mosquito Control and Other Flying Insect Pest Control 

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

been set at 6,400 acres. EPA believes that the vast majority of mosquito control and 

abatement districts in the United States 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 6,400 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 applications that 

approach or exceed this threshold. Therefore, EPA believes the threshold appropriately 

captures most Decision-makers engaging in this use pattern. EPA also believes too that 

even those mosquito control districts that treat areas below the threshold should be 

required to submit NOIs, as these entities were created specifically for the control of 

pests and should provide notice to the Agency of their activities. As such, the permit 

requires all mosquito control districts or similar pest control districts, as well as any other 

Decision-makers treating over the annual treatment area threshold, to submit an NOI. 

The Agency believes this appropriately captures those two classes of entities that either 

(1) are established with a specific purpose of pest control or that (2) treat large enough 

areas to warrant notice to the Agency.

Weed and Algae Control 

For Weeds and Algae, the annual treatment area threshold has been set at 80 acres or 20 

linear miles of pesticide application to canals and other Waters of the United States. This 

threshold has been set to capture Decision-makers treating relatively large portions of 

surface waters and watersheds, such as water management districts, wildlife and game 

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

Florida Water Management District usually applies pesticides to 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, California Department of Water Resources, or organizations with comparable 

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

systems, 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. Similar to mosquito control, EPA believes that 

weed control districts, or similar pest control districts created specifically for the control 

of pests that treat areas below the threshold should be required to submit NOIs. As such, 

the permit requires all weed control districts or similar pest control districts as well as any 

other Decision-makers treating over the annual treatment area threshold to submit an 

NOI. The Agency believes this appropriately captures those two classes of entities that 

either (1) are established with a specific purpose of pest control or that (2) treat large 

enough areas to warrant notice to the Agency. 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

37 

Animal Pest 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 80 acres or 20 linear miles. The high mobility 

and prolific breeding abilities that necessitate control of aquatic animals usually means 

that pesticide applications most often occurs in the entirety or large portions of the water 

bodies they inhabit. For example, fishery management applications using rotenone often 

occur in the entire lake and thus, any similar application to a lake of more than 80 acres 

in area will trigger the annual treatment area threshold. EPA expects that for this reason, 

only spot applications to eradicate small emergent populations of sessile animals or 

applications to very small water bodies might be excluded from an NOI requirement. 

Therefore, EPA believes the threshold appropriately captures the relatively large 

Decision-makers engaging in this use pattern.

Forest Canopy Pest Control 

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

throughout which Operators may not be able to see Waters of the United States beneath 

the canopy. EPA has set the annual treatment area threshold at 6,400 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 Decision-makers 

engaging in this use pattern, particularly public agencies managing large tracts of land. 

NOIs for Certain Entities Regardless of the Annual Treatment Area Threshold

 In addition to NOIs from Decision-makers treating the largest areas, EPA is also 

requiring NOIs from certain other types of entities with land resource stewardship 

responsibilities that involve the routine control of pests. For these entities, the permit requires 

NOIs regardless of the size of the area treated. In general, EPA expects that in many instances 

these entities will exceed one or more of the annual treatment area thresholds. Nonetheless, the 

Agency believes that regardless of the size of the treatment area, any Agency for which pest 

management for land resource stewardship is an integral part of the organization’s operations 

should also be required to submit NOIs. Such entities may include Federal government agencies 

such as USDA forest Service and DOI Bureau of Land Management, or state government

agencies such as departments of natural resources. EPA’s rationale for imposing the NOI 

requirement is premised on these entities (public, quasi-public, and private) having as an integral

responsibility controlling pests. The specific entities required to submit NOIs regardless of 

whether an annual treatment area threshold is exceeded are as follows:

Any Agency for which pest management for land resource stewardship is an integral part 

of the organization’s operations – Any agency that has pest control as an integral part of 

the organization’s operations or responsibilities is required to submit an NOI. EPA 

believes that many pest control activities performed by these entities will meet or exceed 

the threshold requirement to submit an NOI. Even when these activities do not exceed 

the thresholds, however, they are subject to the NOI requirement if the pesticide 

application is an integral part of their operations and responsibilities. EPA also 

recognizes, however, that some of these agencies may perform ad-hoc pest control on a 

small-scale that is not an integral part of the organization’s operations but rather 

incidental, for example, to its occupancy of a building. As an example, the U.S. Social 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

38 

Security Administration may maintain a building or group of buildings where weeds have 

overtaken a parking lot that is adjacent to a lake, and the local office decides to control 

those weeds with an herbicide. That weed control activity would not be considered an 

integral part of the Social Security Administration operations but rather the weed control 

would be incidental to operation of the facility. By contrast, state agencies such as a 

department of natural resources and federal agencies such as the US Forest Service,

would have pest control as an integral part of their organization’s operations and as such 

would be required to submit an NOI. To be clear, in all instances described above, 

discharges would require permit coverage; however, the requirement to submit an NOI 

applies only to those pest control activities that are integral to an organization’s 

operations and responsibilities. 

Mosquito control districts (or similar pest control districts, such as vector control 

districts) – In many parts of the country, state and territorial governments have 

established special districts for the purpose of mosquito control. Generally, these districts 

treat large areas that would exceed EPA’s annual treatment area thresholds; however 

EPA is requiring any such district, regardless of the area treated, to submit an NOI. 

Irrigation control districts (or other similar public or private entities supplying irrigation 

waters) – In many parts of the country, special districts have been established for the 

purpose of maintaining irrigation canals and ditches. Generally, these districts treat large 

areas that exceed EPA’s annual treatment area thresholds; however EPA is requiring any 

such district, regardless of the area treated, to submit an NOI.

Weed control districts (or other similar special purpose districts created with a 

responsibility of pest control) – EPA is aware of some weed control districts created 

across the country with the specific responsibility to control pests. The Agency has 

determined that these types of entities, who perform pest management and control, as the 

primary function of their organization, should provide notice to the Agency of such 

activities regardless of the size of the area treated.

NOIs for Discharges to Tier 3 Waters

Any Decision-maker requesting to discharge to Tier 3 waters may seek coverage under 

the PGP provided that the discharge is short-term or temporarily lowers water quality due to 

pesticide applications that are necessary to protect the water quality, environment, or public 

health. Any Decision-maker wanting coverage under the PGP for such a discharge will be 

required to identify the Tier 3 water by name with authorization to discharge to Tier 3 waters 

limited to only such named waters. 

NOIs for Discharges to Waters of the United States Containing NMFS Listed Resources of 

Concern, as Defined in Appendix A of the Permit

Any Decision-maker with any discharges to Waters of the United States containing 

NMFS Listed Resources of Concern, as defined in Appendix A of the permit, may seek coverage 

under the PGP by submitting a complete and accurate NOI form that includes certifying 

eligibility under one of the five criteria (B-F) in Part 1.1.2.4 of the permit. 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

39 

Contents of the NOI

Pursuant to 40 CFR §122.28(b)(2)(ii), the contents of any NOI must be specified in the 

general permit and require the submission of information necessary for adequate program 

implementation, including at a minimum:

- the legal name and address of the Owner or Operator,

- the facility name and address,

- type of facility or discharges, 

- the receiving stream(s), and

- signed in accordance with §122.22. 

The specific requirements of the PGP NOI are identified in the NOI form provided in 

Appendix A of the permit but include those elements identified in the regulations described 

above with three additional data elements that EPA believes are important to fully characterize 

the activities for which permit coverage is being provided, namely identification of: 

- pesticide use activities that trigger the PGP requirements to develop a pesticide discharge 

management plan and submit an annual report; 

- impaired water(s) and/or Tier 3 water(s) for which permit coverage is being requested for 

discharges to these waters and demonstration of eligibility for such discharges; and

- whether pesticide discharges will be to Waters of the United States containing NMFS 

Listed Resources of Concern, and, if so, what pest(s) are to be controlled; the pesticide 

product(s) to be discharged; the planned quantity and rate of discharge(s); the number of 

planned discharges; and signed certification by the Decision-maker that one of the six 

criteria in Part 1.1.2.4 have been met. EPA recognizes the implementation of pest 

management measures as specified in the permit may involve a degree of “adaptive 

management” such that exact timing and quantities of applications cannot be determined 

in advance for the duration of the permit. EPA expects the Decision-maker to provide the 

required information to the extent feasible and consistent with the implementation of the 

selected pest management measures.

Also, the NOI form requires Decision-makers to submit changes to previous NOI forms 

where, for example, coverage for an additional discharge not included in the original NOI is 

being requested. EPA expects these NOI change requests to be submitted primarily in four 

instances: (1) coverage for a new or expanded pest management area or a new pesticide use 

pattern is being requested, (2) discharge to a not-previously identified Tier 3 water is identified 

for permit coverage, or (3) discharge to any not-previously identified Waters of the United States 

containing NMFS Listed Resources of Concern, as defined in Appendix A of the permit, is being 

requested or (4) changes in the treatment area, pesticide product, method or rate of application, 

or approximate dates of applications for discharges to Waters of the United States containing 

NMFS Listed Resources of Concern. In cases where this information was previously provided to 

the extent feasible and consistent with the implementation of selected pest management 

practices, a revised NOI is not required as long as the discharge continues to be consistent with 

the information provided in the original NOI submission. In these four instances, Decisionmakers are required to submit revised NOIs that reflect changes in the areas and types of 

activities for which coverage is being requested.
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

40 

1.2.3 Discharge Authorization Date 

The PGP is effective on October 31, 2011. Eligible discharges are covered under this 

permit automatically, without submission of an NOI, from the effective date of this permit 

through January 12, 2012. Decision-makers required to submit NOIs, as detailed in Part 1.2.2, 

are authorized consistent with the timeframes and provisions detailed in Part 1.2.3 of the permit. 

EPA is not requiring NOIs be submitted for any discharges that occur on or before January 12, 

2012 to allow Decision-makers enough time to read and understand the permit requirements and 

comply with the recordkeeping and reporting requirements of the permit. Decision-makers who 

are required to submit an NOI, but are discharging between October 31, 2011 and January 12, 

2012, must begin complying with Part 2.2 requirements as of October 31. 2011. 

For any discharges occurring after January 12, 2012 for which Operators are not required 

to submit an NOI, permit coverage continues uninterrupted. For any discharges occurring after 

January 12, 2012, NOIs are required from Decision-makers according to the schedule detailed in 

Table 1-2 in the final PGP and as described below:

- Other than for discharges in response to a Declared Pest Emergency Situation or that 

are to NMFS Listed Resources of Concern, both of which are described below, 

Decision-makers who discharge after January 12, 2012 are authorized 10 days after 

EPA posts on its public Internet website at www.epa.gov/npdes/pesticides receipt of a 

complete and accurate NOI unless EPA places a hold on the authorization. The 

Agency may place an authorization on hold (i.e., delay authorization) if the Agency 

determines, including based on information provided by other interested parties, that 

the Operator may not be eligible for PGP coverage. Thus, for any discharges 

commencing on or before January 12, 2012 for which continuing coverage is needed 

after that date, an NOI will need to be submitted no later than January 2, 2012 to 

ensure uninterrupted permit coverage, and for any discharges beginning after January 

12, 2012 no later than 10 days before the first discharge. 

- Any Decision-maker that discharges in response to a Declared Pest Emergency 

Situation, as defined in Appendix A of the permit, that is not to Waters of the United 

States containing NMFS Listed Resources of Concern, for which that activity triggers 

the requirement to submit an NOI, is authorized to discharge immediately; however, a 

complete and accurate NOI is required to be submitted no later than 30 days after 

beginning to discharge (for any related discharges after January 12, 2012). This delay 

in NOI submission and immediate authorization is to allow pest managers the 

opportunity to respond to pest emergencies without delay.

- In any Declared Pest Emergency Situation for discharges to Waters of the United 

States containing NMFS Listed Resources of Concern, the discharges are authorized 

for 60 days or until EPA determines that the discharges may not continue (or places 

additional conditions on the discharge) due to concerns related to compliance with the 

ESA-related conditions of this permit. These Decision-makers must file an NOI no 

later than 15 days after beginning to discharge. The NOI must identify: 

1. The location of the pest management area in detail or include a map of the 

location; 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

41 

2. Pest(s) to be controlled;

3. Pesticide product(s) to be discharged and method of application; 

4. Planned quantity and rate of discharge(s) for each method of application; 

5. Number of planned discharges;

6. Approximate date(s) of planned discharge(s); and 

7. The rational supporting whether the discharge is likely to adversely affect a 

NMFS Listed Resource of Concern, including the description of appropriate 

measures to be undertaken to avoid or eliminate the likelihood of adverse 

effects.

For discharges that have already occurred prior to NOI submission, items 1 through 6 

above must also be identified in that NOI. 

In any Declared Pest Emergency Situation in areas with Waters of the United States 

containing NMFS Listed Resources of Concern, NMFS will have 30 days after 

submission of an NOI to provide EPA with a determination as to whether NMFS 

believes the eligibility criteria of “not likely to adversely affect listed species or 

designated critical habitat” has been met, could be met with conditions that NMFS 

identifies, or has not been met. EPA expects to rely on NMFS’ determination in 

deciding whether to disallow continued permit coverage or if additional conditions 

are necessary. If NMFS does not provide EPA with a recommendation within 30 

days of EPA posting on the Internet receipt of a complete and accurate NOI, 

authorization for these discharges will continue. If EPA identifies additional permit 

conditions, or includes additional permit conditions recommended by NMFS, as 

necessary to qualify discharges as eligible for coverage beyond 60 days under the 

PGP, those conditions remain in effect for the life of the permit. EPA will advise the 

Decision-maker within 15 days of receiving a determination from NMFS whether the 

discharge or discharges qualify for coverage beyond the 60-day authorization 

provided under the PGP. If the decision maker does not hear from EPA, the decision 

maker may assume that permit authorization continues unless notified otherwise. 

EPA believes this approach provides a reasonable amount of time for Operators to 

quickly respond to any Declared Pest Emergency Situation (i.e., 60 days after 

beginning to discharge), yet provides the Agency with an opportunity to ensure that 

subsequent discharges are controlled as necessary to protect water quality and any 

NMFS Listed Resources of Concern.

- For any discharges commencing on or before January 12, 2012 to Waters of the 

Unites States containing NMFS Listed Resources of Concern for which continuing 

coverage is needed after that date, an NOI will need to be submitted no later than 

December 12, 2012 to ensure uninterrupted permit coverage, and for any discharges 

beginning after January 12, 2012 no later than 30 days before the first discharge. 

EPA may, of course, place a hold on such authorization. This 30-day timeframe 

operates similar to the 10-day timeframe described above but provides more time for 

interested parties (including the Services) to review information prior to EPA 

authorizing discharges under the PGP. This additional timeframe reflects NMFS’ 

interest in having sufficient time to review NOI submissions as a result of discharges 

to Waters of the United States containing NMFS Listed Resources of Concern, as 

defined in Appendix A of the permit. EPA strongly recommends Decision-makers 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

42 

submit NOIs as early as possible for activities that discharge to Waters of the United 

States containing NMFS Listed Resources of Concern. It is important that the fullest 

possible opportunity be given for consideration of any effects that an application may 

have on listed species. The permit includes a 30-day waiting period after submittal of 

an NOI to provide an opportunity for NMFS and other interested stakeholders to 

review the NOI. Also during this time period, issues can be raised with EPA. EPA 

may authorize certain discharges in less than 30 days, but no fewer than 10 days, after 

submission of an NOI for any discharges under Criterion B, C, or E of Part 1.1.2.4 of 

the permit. This is because under criteria B and C, Operators would have already 

consulted with NMFS and under criterion E, the Operator would have received a 

written letter from NMFS that the discharge will not adversely affect NMFS Listed 

Resources of Concern. The Agency may determine that a Decision-maker is ineligible 

for coverage under the PGP and deny coverage. However, the Agency is concerned 

that if a large number of NOIs with discharges to Waters of the United States 

containing NMFS Listed Resources of Concern are submitted to EPA around the 

same time, it will make it difficult to fully consider the contents of each NOI of 

interest. Early submittal and review of NOIs will help ensure that any issues are 

addressed and resolved in a timely manner so that appropriate pesticide applications 

can proceed as planned. In determining whether to withhold permit authorization 

under this permit, EPA expects to rely on NMFS expertise in making a determination 

as to whether there is likely to be adverse effect. Within 30 days after EPA posts on 

the Internet receipt of a complete and accurate NOI, for those discharges to Waters of 

the United States containing NMFS Listed Resources of Concern, as defined in 

Appendix A, NMFS will provide EPA with a determination as to whether it believes 

the eligibility criteria of “not likely to adversely affect listed species or designated 

critical habitat” has been met, could be met with conditions the NMFS identifies, or 

has not been met. EPA expects to rely on NMFS’ determination in deciding whether 

to disallow continued permit coverage or if additional conditions are necessary. EPA 

notes that it is also advantageous to the Decision-maker to work with NMFS prior to 

submitting the NOI, and to obtain written correspondence from NMFS, if possible, 

that pesticide application activities performed consistent with appropriate measures 

will avoid or eliminate the likelihood of adverse effects. In this case, as noted above, 

EPA may authorize discharges in as few as 10 days after the NOI is submitted, 

although the operator may not assume authorization before 30 days unless 

specifically so notified by EPA. 

NOIs submitted electronically will be posted on the NPDES website instantaneously with 

the Operator authorized to discharge 10 or 30 days after the posting, providing EPA does not 

place a hold on the authorization for that NOI. EPA will send automatic confirmation of receipt 

of NOIs and of discharge authorization. 

The PGP contains standard language that provides EPA with the authority to modify 

permit terms or terminate permit coverage as appropriate. NMFS and any other interested 

persons may provide information to EPA noting any concerns with authorized discharges, 

including those resulting from Declared Pest Emergency Situations. EPA will consider that 

information and take future action as appropriate. As provided in the permit, in general, EPA 

may take the following actions: 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

43 

Part 1.3 - Require Operators to apply for and/or obtain authorization to discharge under 

either an NPDES individual permit or an alternative NPDES general permit.

Appendix B, Part B.1 - Terminate, revoke and reissue, or modify a permit for any 

permit noncompliance, that is also grounds for enforcement action. 

Part 1.2.3; Part 6.3; Appendix B, Part B.6 - Modify, revoke and reissue, or terminate a 

permit for cause.

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 an Operator prior to the expiration date of this permit, 

the Operator 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 Operators authorized to 

discharge under the prior general permit. However, EPA does not have the authority to provide 

coverage under an administratively extended permit to entities not authorized prior to the 

expiration date of the permit.

1.2.5 Terminating Coverage 

1.2.5.1 Submitting a Notice of Termination. 

The permit recommends Decision-makers use the eNOI system to file Notices of 

Termination. To terminate coverage under this permit, any Decision-maker that submitted a 

Notice of Intent to obtain permit coverage is required to submit a Notice of Termination in 

accordance with information identified in Appendix E. The Decision-maker’s authorization to 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

44 

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/eNOI). 

Dischargers automatically covered under this permit as identified in Part 1.2.3 are automatically 

terminated upon permanent cessation of discharge consistent with any of the criteria identified in 

Part 1.2.5.2. 

EPA requires Decision-makers 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 Decision-makers 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 Decision-maker continues to have a discharge), then the notice is not valid and the 

Decision-maker must continue to comply with the conditions of the permit. Likewise, if EPA 

determines that the Notice of Termination is incomplete, the Decision-maker 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 

Decision-maker 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 Decision-maker has 

taken over responsibility for the pest control activities; (2) all discharges have ceased from the 

application of pesticides for which permit coverage was obtained and discharges are not 

expected during the remainder of the permit term for any of the use patterns as identified in Part 

1.1.1, or (3) coverage under an individual permit or alternative general permit has been obtained 

for all discharges required to be covered by an NPDES permit, unless coverage was obtained 

consistent with Part 1.3, in which case, coverage under this permit will terminate automatically.

EPA is requiring a Notice of Termination from 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. 

1.2.5.3 Termination for Operators not Required to Submit an NOI.

Operators covered under this permit that are not required to submit an NOI are terminated 

from permit coverage when there is no longer a discharge from the application of pesticides or 

the discharges are covered under an NPDES individual permit or alternative NPDES general 

permit. Operators not required to submit an NOI are also not required to submit an NOT.

1.3 Alternative Permits

1.3.1 Requirements for 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 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

45 

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 from 

anti-foulant hull coatings, biofouling prevention, and residuals from ballast water treatment 

technologies are already covered under the Vessels General Permit and do not require coverage 

under this general permit (see EPA NPDES Vessels General Permit at 

http://www.epa.gov/NPDES/vessels).

1.3.2 Operator Requesting Coverage under an Alternative Permit

After being covered by this permit, the Operator may request to be excluded from such 

coverage by applying for an individual permit or alternative NPDES general permit. In this case, 

the Operator 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 in Part 8.2 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 of the permit reminds Operators of their ability to apply for coverage under an 

individual permit in lieu of coverage under this general permit and describes the steps to take to 

be excluded 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; or 

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 United States;

(2) The size of the discharge;

(3) The quantity and nature of the pollutants discharged to Waters of the United States; and

(4) Other relevant factors.

EPA may require an Operator 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 Operator shall automatically 

terminate. EPA may grant additional time upon request of the applicant. 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

46 

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 Operator is 

automatically terminated on the effective date of the individual permit.

Note that an individual permit is required for discharges from the application of 

pesticides to waters where such waters are impaired by a substance which either is an active 

ingredient in that pesticide or is a degradate of such an active ingredient, and for certain 

applications of pesticides to Tier 3 waters where such applications are not made to restore or 

maintain water quality or to protect public health or the environment in such a way that they 

either do not degrade water quality or only degrade water quality on a short-term or temporary 

basis. 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. 

1.5 Other Federal and State Laws

Part 1.5 of this permit includes the following language: “Operators must comply with all 

other applicable federal and state laws and regulations that pertain to the application of 

pesticides. For example, this permit does not negate the requirements under the Federal 

Insecticide, Fungicide, and Rodenticide Act (FIFRA) and its implementing regulations to use 

registered pesticides consistent with the product’s labeling. In fact, applications in violation of 

certain FIFRA requirements could also be a violation of the permit and therefore a violation of 

the CWA (e.g. exceeding label application rates). Additionally, other laws and regulations might 

apply to certain activities that are also covered under this permit (e.g., United States Coast Guard 

regulations).”

This part of the permit is intended to clarify that Operators 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. In fact, 

compliance with permit terms, in some instances, establishes an expectation that Operators will 

comply with other laws to demonstrate compliance with this permit. For example, the permit 

requires Operators to use “Pest Management Measures” to “minimize” discharges. As these 

terms are defined in Appendix A of the permit, Operators must use practices that comply with, 

among other things, “relevant legal requirements” to reduce and/or eliminate pesticide discharges 

to Waters of the United States.
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

47 

1.6 Federally Listed Endangered and Threatened Species and Designated Critical 

Habitat.

This part of the permit clarifies that Operators are required to comply with conditions 

and/or requirements for discharges to Waters of the United States from any Section 7 

consultation or Section 10 permit for pesticides application activities covered under this permit.

2. 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 limitations2

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 United States. In addition, these effluent 

limitations provide for protection of water quality standards, including protection of beneficial 

uses of the receiving waters following completion of pest management activities.

The Clean Water Act Requires EPA to Develop Effluent Limitations that Represent the 

Following:

Best Practicable Control Technology Currently Available (BPT) 

The CWA requires BPT effluent limitations for conventional, toxic, and non-conventional 

pollutants. Section 304(a)(4) designates the following as conventional pollutants: biochemical 

oxygen demand (BOD5), total suspended solids, fecal coliform, pH, and any additional pollutants 

defined by the Administrator as conventional. The Administrator designated oil and grease as an 

additional conventional pollutant on July 30, 1979. 40 CFR 401.16. EPA has identified 65 pollutants 

and classes of pollutants as toxic pollutants, of which 126 specific substances have been designated 

priority toxic pollutants. 40 CFR 401.15 and 40 CFR Part 423 Appendix A. All other pollutants are 

considered to be non-conventional. 

 2 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 

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 2011 NPDES Pesticide General Permit Fact Sheet

48 

In specifying BPT, under CWA section 301(b)(1)(A); 304(b)(1)(B); 40 CFR 125.3(d)(1), EPA 

looks at a number of factors. EPA first considers the total cost of applying the control technology in 

relation to the effluent reduction benefits. The Agency also considers the age of the equipment and 

facilities, the processes employed, and any required process changes, engineering aspects of the 

control technologies, non-water quality environmental impacts (including energy requirements), and 

such other factors as the EPA Administrator deems appropriate. Traditionally, EPA establishes BPT 

effluent limitations based on the average of the best performance of facilities within the industry of 

various ages, sizes, processes, or other common characteristics. Where existing performance is 

uniformly inadequate, BPT may reflect higher levels of control than currently in place in an 

industrial category if the Agency determines that the technology can be practically applied. 

Best Conventional Pollutant Control Technology (BCT) 

The 1977 amendments to the CWA required EPA to identify effluent reduction levels for 

conventional pollutants associated with BCT for discharges from existing industrial point sources. 

CWA section 301(b)(2)(E); 304(b)(4)(B); 40 CFR 125.3(d)(2). In addition to considering the other 

factors specified in section 304(b)(4)(B) to establish BCT limitations, EPA also considers a two part 

“cost-reasonableness'' test. EPA explained its methodology for the development of BCT limitations 

in 1986. 51 FR 24974 (July 9, 1986). 

Best Available Technology Economically Achievable (BAT)

For toxic pollutants and non-conventional pollutants, EPA includes technology-based effluent 

limitations based on BAT in NPDES permits. CWA section 301(b)(2)(A); 304(b)(2)(B); 40 CFR 

125.3(d)(3). In establishing BAT, the technology must be technologically “available” and 

“economically achievable.” The factors considered in assessing BAT include the cost of achieving 

BAT effluent reductions, the age of equipment and facilities involved, the process employed, 

potential process changes, non-water quality environmental impacts, including energy requirements 

and other such factors as the EPA Administrator deems appropriate. The Agency retains considerable 

discretion in assigning the weight accorded to these factors. BAT limitations may be based on 

effluent reductions attainable through changes in an Operator’s processes and operations. Where 

existing performance is uniformly inadequate, BAT may reflect a higher level of performance than is 

currently being achieved within a particular subcategory based on technology transferred from a 

different subcategory or category. BAT may be based upon process changes or internal controls, 

even when these technologies are not common industry practice.

This permit contains effluent limits that correspond to required levels of technology-based 

control (BPT, BCT, BAT) for discharges under the CWA. Some effluent limits have been established 

by examining other existing laws, requirements and practices. Because these are demonstrated 

practices, EPA has found that they are technologically available and economically practicable (BPT) 

or achievable (BAT). 

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 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

49 

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). 

As stated above, the CWA establishes two levels of technology-based controls. The first 

level of control, “best practicable control technology currently available,” or “BPT” applies to all 

pollutants. CWA section 304(b)(1)(B); 33 U.S.C. 1314(b)(1)(B). BPT represents the initial stage of 

pollutant discharge reduction, designed to bring all sources in an industrial category up to the level of 

the average of the best source in that category. See EPA v. National Crushed Stone Association, 449 

U.S. 64, 75-76 (1980). In the second level of control, all point sources are required to meet effluent 

limitations based on “best conventional pollutant control technology,” or “BCT” CWA section 

304(b)(4)(B); 33 U.S.C. 1314(b)(4)(B) or “best available technology economically achievable,” or 

“BAT” CWA section 301(b)(2)(A); 33 U.S.C. 1311(b)(2)(A), depending on the types of pollutants 

discharged. BCT applies to conventional pollutants, listed at 40 CFR 401.16 (biological oxygen 

demand (BOD), pH, fecal coliform, TSS, and oil and grease). BAT applies to toxic and nonconventional pollutants. Technology-based limitations are to be applied throughout industry without 

regard to receiving water quality. Appalachian Power Co. v. EPA, 671 F.2d 801 (4th Cir. 1982

EPA’s Authority to Include Non-Numeric Technology-Based Limitations in this Permit

All NPDES permits are required to contain technology-based effluent limitations. 40 

CFR §§ 122.44(a)(1) and 125.3. CWA sections 301(b)(1)(A) for (BPT); 301(b)(2)(A) for 

(BAT); and 301(b)(2)(E) for (BCT). Technology-based effluent limitations in this permit 

represent the BPT (for conventional, toxic, and non-conventional pollutants), BCT (for 

conventional pollutants), and BAT (for toxic pollutants and non-conventional) levels of control 

for the applicable pollutants. When EPA has not promulgated effluent limitation guidelines for 

an industry, or if an Operator is discharging a pollutant not considered in the development of 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 effluent limitations are based on BPJ decisionmaking 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 

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).
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

50 

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.”

For this permit, EPA is using the term “Pest Management Measures,” as defined in 

Appendix A of the permit, to represent those practices used to meet the non-numeric effluent 

limitations.

EPA’s Decision to Include Non-Numeric Technology-Based Effluent Limitations in This 

Permit and Rationale for Why the Limits Represent the Appropriate (BPT, BCT, or BAT) 

Level of Control.

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 Waters of the United States is a discharge of pollutants when there is a 

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). 

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 

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. 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

51 

• 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. 

In the context of this general permit, EPA has determined these non-numeric effluent 

limits represent the best practicable technology (BPT) for all pollutants, the best conventional 

pollutant control technology for conventional pollutants (BCT) and the best available technology 

economically achievable (BAT) for toxic and non-conventional pollutants. EPA has determined 

that the combination of pollution reduction practices described below are the most 

environmentally sound way to control the point source discharges of biological pesticides, and 

chemical pesticides that leave a residue.

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 point source discharges of pesticides to Waters of the 

United States, thereby protecting the receiving waters, including to the extent necessary to meet 

applicable water quality standards. EPA notes that this permit uses the term “Pest Management 

Measures.” Use of the term Pest Management Measures is intended to better describe the range 

of pollutant reduction practices that may be employed when applying pesticides, whether they 

are structural, non-structural or procedural and includes BMPs as one of the components. 

The BAT/BPT/BCT effluent limitations in this permit are expressed as specific pollution 

prevention requirements for minimizing the pollutant levels in the discharge. In the context of 

this general permit, these requirements represent the best technologically available and 

economically practicable and achievable controls. 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. 

Requirements are technologically available

EPA has found that the requirements of this permit represent the appropriate level of control 

representing BPT, BCT, and BAT. For example, many states already require operators to evaluate 

pest management options or produce an IPM plan before applying pesticides. This permit is not 

requiring IPM, but is requiring certain Operators to implement pest management measures to meet 

the technology-based effluent limitations that are based on IPM principles. See further discussion of 

pest management measures below. Unlike other general permits, the technology available to 

Operators depends on the type of Operator (e.g. Applicator v. Decision-maker). For this reason, 

technology-based effluent limitations vary depending on Operator type. As an example of an 

effluent limit that meets BPT and BAT standards, applicators are required to maintain pesticide 

application equipment in proper operating condition, including requirement to calibrate, clean, and 

repair such equipment and prevent leaks, spills, or other unintended discharges. This effluent 

limitation is not appropriate for decision-makers that do not apply the pesticide themselves and as 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

52 

such, is not an effluent limitation for decision-makers. EPA determined that calibrating, cleaning, 

and repairing pesticide application equipment is technologically available and based on EPA’s 

evaluation of this industry, is currently being implemented by many operators and is a practice that 

every operator should be doing when using pesticides as a way to prevent leaks, spills, and other 

unintended discharges, such as over-applying pesticides as a result of poorly maintained equipment. 

Requirements meet the BPT and BAT economic tests set forth in the CWA

There are different economic considerations under BPT, BCT and BAT. EPA finds that the 

limits in this permit meet the BPT and BAT economic tests. Because the types of controls under 

consideration minimize toxic, nonconventional, and conventional pollutants, conventional pollutants 

are controlled by the same practices that control toxic and nonconventional pollutants. Hence, EPA is 

evaluating effluent limits using a BPT and a BAT standard, but since conventional pollutants will 

also be adequately controlled by these same effluent limits for which EPA applied the BPT and BAT 

tests, EPA has determined that it is not necessary to conduct BCT economic tests.

Under BPT, EPA has determined that the requirements of this permit are economically 

practicable. To make this determination, EPA has considered the reasonableness of the relationship 

between the costs of application of technology in relation to the effluent reduction benefit derived. 

CWA section 301(b)(1)(B); 40 CFR 125.3(d)(1). EPA estimates the total universe that will be 

affected by this permit includes approximately 35,000 entities. The economic analysis 

completed for this permit indicates that the technology-based effluent limitations will incur a 

total cost to the permitted universe of between $8 million and $9 million annually. Including 

paperwork requirements, EPA estimates the cost of the permit to the permitted universe to be 

between $10 million and $11 million annually. Unit costs for implementing the different 

technology based requirements are summarized in Table 5-13 in the PGP Economic Analysis, a 

copy of which is available in the PGP administrative record.

EPA has determined that the requirements of this permit are economically achievable. In 

determining “economic achievability” under BAT, EPA has considered whether the costs of the 

controls can reasonably be borne by the industry. EPA typically evaluates “closures,” whereby the 

costs of requirements are evaluated to see whether they would cause a facility or Operator in this case 

to go out of business. To evaluate potential economic impacts of this permit, EPA estimated the 

applicable thresholds below which average per entity compliance cost could exceed a percentage 

of annual revenues/sales. EPA used percentages of 1% and 3% of revenues/sales to characterize 

the potential for significant impact. Based on this analysis, EPA concludes that the technologybased effluent limitations in this permit are unlikely to result in a substantial economic impact to 

the permitted universe, including small businesses. The economic analysis is available in the 

docket for this permit. In addition, EPA considered the non-water quality environmental 

impacts, including energy impacts, of the controls required under this permit and found that they 

are acceptable. EPA expects that the permit will result in few non-water impacts because in 

many cases, the permit is reflective of practices currently implemented by Operators. Hence, EPA 

interprets this analysis to indicate that the BAT limits are economically achievable.

EPA continues to study the efficacy of various types of pollution prevention measures 

and BMPs; however, for this permit numeric limitations are not feasible.
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

53 

Pest Management 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 Pest Management Measures that can be used to meet the effluent limitations. 

Therefore, EPA is not mandating the specific Pest Management Measures Operators must 

implement to meet the limitations. This is analogous to an industrial situation where discharges 

to Waters of the United States 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.b of the PGP requires mosquito control Decision-makers to consider 

mechanical/physical methods of control to eliminate or reduce mosquito habitat. How this is 

achieved will vary by Operator: For some, this may be achieved through elimination of 

development habitat (e.g. filling low areas, dredging, etc.) while for others these measures will 

not be feasible. Thus, a given Pest Management 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.

Pest Management 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 situation in order to meet the effluent limitation. In this permit, Operators 

are required to implement site-specific Pest Management Measures to meet these effluent 

limitations. The permit along with this fact sheet provides examples of Pest Management 

Measures, but Operators must tailor these to their situations as well as improve upon them as 

necessary to meet the effluent limitations.

The approach to Pest Management 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 Pest Management 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 Pest Management Measures

Part 2.0 of this permit requires Operators to implement Pest Management 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 Pest Management Measures. 

Some Decision-makers will have to document how such factors were taken into account in the 

implementation of their Pest Management Measures (See Part 5). EPA recognizes that not all of 

these considerations will be applicable to every pest management area nor will they always affect 

the choice of Pest Management Measures. EPA expects Operators to have the experience and 

working knowledge to apply pesticides properly. The PGP requires the Operator to apply such 

expertise and working knowledge to use best professional judgment in meeting the permit terms. 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

54 

If Operators find their Pest Management Measures are not minimizing discharges of pesticide 

adequately, the Pest Management Measures must be modified as expeditiously as practicable. 

See Part 6, Corrective Action.

EPA believes flexibility is needed for Operators to tailor Pest Management Measures to 

their situation as well as improve upon them as necessary to meet the technology-based effluent 

limitations; with the selection of Pest Management Measures based on available information and 

best professional judgment of personnel who are qualified to make pest management decision. 

For example, while Part 2.2 requires Decision-makers to evaluate other means than pesticide use, 

it remains the best professional judgment what ultimate pest control method is employed. Thus, 

while mechanical pest removal or less toxic chemicals may be possible options, the Decisionmaker is in the best position to know what method is most appropriate and effective against the 

target pest.

Pest Management Measures and Technology-Based Effluent Limitations – Definition of 

“Minimize”

EPA has found that the requirements of this permit represent the appropriate level of 

control to address BPT, BCT, and BAT. 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 United States through the use of Pest Management 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 United States can be 

achieved without using highly engineered, complex pest control systems. The specific limits 

included in Part 2.0 emphasize effective “low-tech” approaches, including using only the 

amount of pesticide product and frequency of pesticide application necessary to control the target 

pest, performing equipment maintenance and calibration, assessing weather conditions prior to 

pesticide application, accurately identifying the pest problem, efficiently and effectively 

managing the pest problem, and properly using pesticides.

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 United States 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 United States. EPA would find that this application was a misuse 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

55 

of the pesticide under the FIFRA label and because of the misuse; the Agency might also 

determine that the effluent limitation that requires the Operator to minimize discharges of 

pesticide products to Waters of the United States was also violated, depending on the specific 

facts and circumstances. 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

In this permit, all Operators are classified as either “Applicators” or “Decision-makers” 

or both. An Applicator is an entity who performs the application of a pesticide or who has dayto-day control of the application (i.e., they are authorized to direct workers to carry out those 

activities) that results in a discharge to Waters of the United States. A Decision-maker is an 

entity with control over the decision to perform pesticide applications, including the ability to 

modify those decisions that result in discharges to Waters of the United States. As such, more 

than one Operator may be responsible for compliance with this permit for any single discharge 

from the application of pesticides. EPA has delineated the non-numeric effluent limitations into 

tasks that EPA expects the Applicator to perform and tasks that EPA expects the Decision-maker 

to perform. In doing so, EPA has assigned the Applicator and the Decision-maker different 

responsibilities.

2.1 Applicators’ Responsibilities

Part 2.1 of this permit contains the general technology-based effluent limitations that all

Applicators must perform, regardless of pesticide use pattern. These effluent limitations are 

generally preventative in nature, and are designed to minimize pesticide discharges into Waters 

of the United States. All Applicators are required to minimize the discharge of pesticides to 

Waters of the United States by doing the following:

2.1.1 To the extent not determined by the Decision-maker, use only the amount of 

pesticide and frequency of pesticide application necessary to control the target pest, using 

equipment and application procedures appropriate for this task.

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 use only the amount 

of pesticide and frequency of pesticide application necessary to control the target pest. Using 

only the amount of pesticide and frequency of pesticide application needed ensures maximum 

efficiency in pest control with the minimum quantity of pesticide. Using only the amount and 

frequency of applications necessary 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.
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

56 

2.1.2 Maintain pesticide application equipment in proper operating condition, including 

requirement to calibrate, clean, and repair such equipment and prevent leaks, spills, or 

other unintended discharges.

Common-sense and good housekeeping practices enable pesticide users to save time and 

money and reduce the potential for unintended discharge of pesticides to Waters of the United 

States. 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. 

Carefully choose the pesticide mixing and loading area and avoid places where a spill will 

discharge into Waters of the United States. Some basic practices 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.

To minimize discharges of pesticides, Applicators 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 maintenance 

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. 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

57 

2.1.3 Assess weather conditions (e.g. temperature, precipitation, and wind speed) in the 

treatment area to ensure application is consistent with all applicable federal requirements.

Weather conditions may affect the results of pesticide application. Applicators must 

assess the treatment area to determine whether weather conditions support pest populations and 

are suitable for pesticide application.

2.2 Decision-makers’ Responsibilities

As noted above, NPDES permits must contain technology-based effluent limitations. 

Part 2.2 of this permit contains the effluent limitations that Decision-makers must perform. The 

PGP requires all Decision-makers, to the extent Decision-makers determine the amount of 

pesticide or frequency of pesticide application, to minimize the discharge of pesticides to Waters 

of the United States from the application of pesticides, through the use of Pest Management 

Measures, as defined in Appendix A of this permit, by using only the amount of pesticide and 

frequency of pesticide application necessary to control the target pest. 

In addition, Part 2.2 of this permit requires that any Decision-maker who is or will be3

required to submit a Notice of Intent (NOI) to identify the pest problem, implement effective and 

efficient pest management options, and adhere to certain pesticide use provisions. (For purposes 

of the discussion below on Part 2.2, the term Decision-maker means any Decision-maker who is 

or will be required to submit an NOI.) Parts 2.2.1 – 2.2.4 do not apply to Decision-makers that 

will need to submit an NOI only because they discharge to Waters of the United States 

containing NMFS Listed Resources of Concern and whose: (1) Pesticide application activities for 

which permit coverage is being requested will discharge to one or more receiving Waters of the 

United States containing NMFS Listed Resources of Concern, but consultation with NMFS under 

Section 7 of the ESA has been concluded for pesticide application activities covered under this 

permit; or (2) Pesticide application activities for which permit coverage is being requested will 

discharge to one or more Waters of the United States containing NMFS Listed Resources of 

Concern, but all “take” of these resources associated with such pesticide application activities 

has been authorized through NMFS’ issuance of a permit under Section 10 of the ESA, and such 

authorization addresses the effects of the pesticide discharges and discharge-related activities on 

federally-listed species and federally-designated critical habitat. However, these Decisionmakers must comply with all applicable conditions and/or requirements resulting from Section 7 

consultation or Section 10 permit.

Decision-makers 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. 

These additional technology-based effluent limitations are based on integrated pest management 

principles. EPA is requiring certain Decision-makers to also comply with different technologybased effluent limitation than Applicators because we have found that they are the Best 

Available Technology Economically Achievable for these Operators. These requirements are 

aimed at reducing discharge of pesticides to Waters of the United States and lessening the 

adverse effects of pesticides that are applied. Each pesticide use pattern has specific limitations, 

 3 Decision-makers who are required to submit an NOI, but are discharging between October 31, 2011 and 

January 12, 2012, must begin complying with Part 2.2 requirements as of October 31, 2011.
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

58 

and these requirements are divided into three different sections: (1) identify the problem, (2) pest 

management options, and (3) pesticide use. For each pest management area, Decision-makers 

must identify the problem prior to pesticide application, consider using a combination of 

chemicals and non-chemical Pest Management Measures, and perform surveillance before 

pesticide application to reduce environmental impacts. 

EPA expects that many of these Decision-makers are already implementing Pest 

Management Measures that are likely to meet these technology-based effluent limitations. EPA 

is requiring these additional technology-based effluent limitation requirements from Decisionmakers and not the Applicators because the measures necessary to meet these requirements are 

within the control of the Decision-makers, not the Applicators. Based on comments received on 

the proposed permit, the Applicators’ main role is to apply pesticide when needed. 

As stated above, these technology-based effluent limitations are based on integrated pest 

management principles. Integrated pest management, 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) 

Integrated pest management 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-Hire Applicators) and non-commercial (e.g., 

state governments, federal governments, local governments, utilities) entities are currently 

implementing integrated pest management or components of integrated pest management to 

minimize pesticide use. For example, federal agencies are required to implement integrated pest 

management 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.” In addition, Executive Order 13514 (October 5, 2009) requires the head of each 

federal agency to implement integrated pest management and other appropriate landscape 

management practices as a means to promote pollution prevention and eliminate waste. EPA has 

found that mosquito control operations are performed by local government entities and that they 

are generally performing integrated pest management.

Below is a general discussion describing the limitations for all pesticide use patterns. 

Following the general discussion are more detailed descriptions of each specific requirement 

under each pesticide use pattern.

Any Decision-maker who is or will be required to submit an NOI must do the following 

regardless of the pesticide use pattern:

Identify the Problem

Decision-makers 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 Measures (pesticidal or nonpesticidal methods), and in developing an action threshold. Action threshold is defined in 

Appendix A of this permit as the point at which pest populations or environmental conditions 

cannot be tolerated necessitating that pest control action be taken based on economic, human 

health, aesthetic, or other effects. An action threshold helps determine both the need for control 

actions and the proper timing of such actions. It is a predetermined pest level that is deemed to 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

59 

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) and/or is an invasive species. 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. Sometimes pre-emergent 

pesticide application is needed, as a preventive measure to keep aquatic weeds at bay. Action 

thresholds, often expressed as number of pests per unit area, can vary by pest, by site, and by 

season. In a new pest management program, action thresholds may be difficult to establish and 

as a practical approach should first focus on 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, Decision-makers may use existing data to 

meet the conditions of this permit. For example, a mosquito district may use surveillance data 

from an adjacent district to identify pests in their pest management area. Decision-makers may 

also use relevant historical site data. 

Pest Management Options

Decision-makers are required to implement efficient and effective means of Pest 

Management Measures that most successfully minimize discharges to Waters of the United 

States resulting from the application of pesticides. Decision-makers must evaluate both pesticide 

and non-pesticide methods. Decision-makers 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, Decision-makers must consider impacts to 

water quality, impacts to non-target organisms, feasibility, and cost effectiveness. Combinations 

of various management options are frequently the most effective Pest Management Measures 

over the long term. The goal should be to emphasize long-term control rather than a temporary 

fix. For additional information, see discussion under each pesticide use pattern. 

Pesticide Use

Decision-makers are required to conduct pest surveillance in an area that is representative 

of the pest problem 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 only 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 pesticide use pattern in Sections 

2.2.1 through 2.2.4 of this permit. For additional information and other limits on pesticide use, 

see specific discussion under each pesticide use pattern.
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

60 

2.2.1 Mosquito and Other Flying Insect Pests Control

i. Mosquitoes

Background 

There are over 2500 different species of mosquitoes throughout the world with 

approximately 200 species occurring in the United States. The total budgets for mosquito 

control in the United States 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 United States 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 usually 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 United States 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 United States. 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).

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 United States, 

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. 

ii. Black Flies

Background 

 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) 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

61 

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 United States, epidemiological research has demonstrated that 

black flies are competent vectors of vesicular stomatitis and suggests that these pests may be 

responsible for periodic outbreaks of this disease in livestock, wildlife, and humans in the 

western United States. 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.

 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 United States 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 United States is primarily through the 

use of larvicides.

Part 2.2.1.a -- Identify the Problem

Prior to the first pesticide application covered under this permit that will result in a 

discharge to Waters of the United States, and at least once each calendar year thereafter 

prior to the first pesticide application for that calendar year, any Decision-makers who is 

or will be required to submit an NOI must do the following for each pest management area, 

as defined in Appendix A. Decision-makers 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 Measures. Re-evaluation of the 

pest problem is also important to ensure Pest Management Measures are still applicable. 

Decision-makers 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 or 

identify environmental condition(s), either current or based on historical data, to serve as 

action threshold(s) for implementing Pest Management Measures. Decision-makers 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. For example, an action threshold could be the number and distribution of service 

requests received from the public. It is a predetermined pest level (or other indicator) 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 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

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.”4 For 

larvae control, action thresholds are determined by standard mosquito dipping techniques. For 

example, in Canyon County Mosquito Abatement District, Idaho5, 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 when the pest is capable of transmitting a human 

pathogen (e.g., mosquitoes and the West Nile virus).

62 

Identify the target pest(s) to develop Pest Management Measures based on 

developmental and behavioral considerations for each pest. Knowledge of the 

developmental biology of mosquitoes is essential to developing Pest Management Measures 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 may 

be completed in a week or less under ideal conditions but may also take longer depending on the 

species, geography, 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 

 4 http://www.mda.state.md.us/plants-pests/mosquito_control/mosquito_control_program_description.php 5 http://www.canyoncountymosquito.com/CCMADMosquitoPesticideUsePlan.pdf
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

63 

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 Pest Management Measures aimed at reducing pesticide 

discharges into Waters of the United States.

Prior to the first pesticide application covered under this permit, Operators must ensure 

proper identification of mosquito to better understand the biology of the target pest and develop 

Pest Management Measures. 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 Measures. Identification of the target pest will aid in 

development of Pest Management Measures aimed at both the immature and adult 

developmental stages. Identification of the target pest for a specific area allows 1) identification 

of potential breeding sites, 2) evaluation of alternative Pest Management Measures aimed at 

controlling the immature stages (habitat modification, source reduction, larvicides, biological 

larvicides, and oils), and 3) assessment of potential for disease transmission.

 For black flies, the life cycle 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 one 

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 two 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 two days to eight 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 and fluctuating water levels associated with seasonal flood and 

drought conditions, .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 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

64 

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 four to nine, depending on species, with many species passing 

through an average of seven instars. Larval development time varies from one week to six 

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. 

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 two 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 one host, to 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 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

65 

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 the pest to develop Pest Management Measures. Due to preferred hosts 

and developmental habitats, proper identification of the pest 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 pest. 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 United States.

Identify known breeding sites for source reduction, larval control program, and 

habitat management. Once pests have been identified, mapping is a valuable tool in assessing 

mosquito habitats and designing control programs for a specific area to minimize pesticide 

discharges into Waters of the United States. Maps may simply be township/city/county maps but 

may also include aerial photo assessments, topographic maps, and satellite imagery where 

available and/practicable. Mapping is essential to identify pest 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 Measures (whether source 

reduction, biological, or chemical) for each particular pest is chosen. Operators must identify 

known breeding sites prior to the first pesticide application covered under this permit. 

In conjunction with identifying the target pest, mapping should be considered part of 

control programs aimed at black fly management. 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. Pest 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 discharges into Waters of the United States.

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. Decision-makers must analyze existing surveillance data to identity any new 

source of pest problems. 

In the event there are no data for the pest management area in the past calendar 

year, use other available data as appropriate to meet the permit conditions in Part 2.2.1.a. 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

66 

Decision-makers may use historical data or neighboring district data to identify the pest and 

establish action thresholds.

Part 2.2.1.b -- Pest Management Options

Prior to the first pesticide application covered under this permit that will result in a 

discharge to Waters of the United States, and at least once each calendar year thereafter 

prior to the first pesticide application for that calendar year, any Decision-maker who is or 

will be required to submit NOIs must select and implement efficient and effective means 

of Pest Management Measures that minimize discharges resulting from the application of 

pesticides to control mosquitoes or other flying insect pests. In developing the Pest 

Management Measures for each pest management area, the Decision-maker must evaluate 

the following management options, including a combination of these management options, 

considering impact to water quality, impact to non-target organisms, feasibility, and cost 

effectiveness: No action; Prevention; Mechanical/physical methods; Cultural methods; 

Biological control agents; and Pesticides.

Decision-makers are required to evaluate management options and implement Pest 

Management Measures to minimize pesticide discharges into Waters of the United States prior to 

the first pesticide application covered under this permit. For blackflies, Pest Management 

Measures 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 options are frequently the most effective Pest Management Measures over 

the long term. The goal should be to emphasize long-term control rather than a temporary fix. 

Decision-makers must reevaluate every year prior to the first pesticide application for that 

calendar year.

 Based on problem identification, two preventive measures other than pesticides should 

be evaluated for blackflies. 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 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. 

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 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

67 

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 

United States.

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 

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.
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

68 

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 Agents. 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 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. 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

69 

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 two to three 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 

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.

Part 2.2.1.c. -- Pesticide Use

Conduct larval and/or adult surveillance in an area that is representative of the pest 

problem or evaluate existing larval surveillance data, environmental conditions, or data 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

70 

from adjacent area prior to each pesticide application to assess the pest management area 

and to determine when action threshold(s) is met. 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. Decision-makers are required to conduct a surveillance program to 

minimize discharges from control activities. Surveillance is necessary not only to establish 

pests’ 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 Pest Management Measures. Adult 

surveillance can be conducted using a variety of methods including but not limited to 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 integrated pest management program as well as to 

its effectiveness and also serve to identify new sources of mosquitoes or identify recurring 

problem sites.

Disease surveillance, where practical, is also a key component of Pest Management 

Measures. 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. 

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 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

71 

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 

Measure.

Aside from surveillance data, Decision-makers may also evaluate environment conditions 

to assess the pest management area. For example, if the pest management area is known for pest 

development after flooding then Pest Management Measures may be needed after a rain storm.

Reduce the impact on the environment and on non-target organisms by applying the 

pesticide only when the action threshold(s) has been met. Operators must apply pesticide 

only as indicated by action thresholds for the pest management area. As noted above, action 

thresholds, established by the Decision-maker, 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 the larval 

action threshold(s) has 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 applications. 

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.
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

72 

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 pesticide 

application 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 nontarget impacts.

Bacillus thuringiensis var israelensis (Bti) is the primary larvicide used for black fly 

control in the United States. Bti is a gram positive, aerobic, spore-forming 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 nontarget organisms due to their acidic digestive systems and lack of suitable tissue receptor sites.

To minimize pesticide discharges into Waters of the United States, 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.

A 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 discharges into Waters of the United States.

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 the adult 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

73 

action threshold(s) has been met. Chemical pesticide applications 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 

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 pesticide application 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. 

Environmental conditions may also 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 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

74 

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 applications made when mosquitoes are up and flying is a 

residual barrier treatment application. Barrier applications 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 

applications 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. 

Pesticide control of black flies in the United States 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 United States.

Recommended Mosquito Control References

EPA recommends the following sources for additional information on Pest Management 

Measures 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-info

American Mosquito Control Association. 2010. Best Management Practices for Integrated 

Mosquito Management. 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

75 

California Department of Public Health. 2008. Best Management Practices for Mosquito 

Control on California State Properties. Available at: 

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://www-aes.tamu.edu/files/2010/06/The-Best-Way-to-ControlMosquitoes.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.

Sacramento-Yolo Mosquito and Vector Control District. 2008. Mosquito Reduction Best 

Management Practices. Available at: 

http://www.fightthebite.net/download/ecomanagement/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://www.governor.nh.gov/media/orders/documents/Executive_order_2008-4.pdf

State of New Mexico. 2008. Philosophy of Mosquito Control. 

http://www.health.state.nm.us/ERD/HealthData/documents/PhilosophyofMosquitoControl2008_

000.pdf
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

76 

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

Recommended Black Fly Control References

EPA recommends the following sources for additional information on Pest Management 

Measures for black fly control: 

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://ohioline.osu.edu/hyg-fact/2000/2167.html

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. israelensis for larval black fly (Diptera: Simuliidae) control. Journal 

of the American Mosquito Control Association. 12(2):312-315. 

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/
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

77 

2.2.2 Weed and Algae Pest Control

Background

Weeds and algae that negatively affect aquatic biodiversity, human health, and economic 

stability are considered to be pests. Weeds and algae can decrease populations of native aquatic 

species including threatened and endangered species. 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 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 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 weeds, algae, and plant pathogens in water and water’s edge (including near the water), 

including ditches and/or canals. 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

Weeds include floating, emergent, or submerged plants that negatively impact the quality 

and utility of Waters of the United States. Weeds also include unwanted vegetation, including 

invasive species, at water’s edge, including near the water and vegetation in or near Waters of 

the United States that are not always “wet” (eg, ephemeral streams, seasonal waters). 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 Pest 

Management Measures should consider mechanical, biological, and/or chemical controls. 

Details for developing an aquatic weed pest management measures can be found in the document 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

78 

Aquatic Plant Management, Best Management Practices in Support of Fish and Wildlife Habitat

(Getsinger et al. 2005). 

The appropriate type of control for weeds and algae is dictated by the biology of the 

target species and by environmental conditions and concerns for a specific area. Numerous Pest 

Management Measures are used to reduce the impact of weeds and algae, but an integrated pest 

management should be the basis for any pest control program. This is a comprehensive approach 

for managing pest populations using a variety of control methods. 

Plant Pathogens 

Plant pathogens are microorganisms that cause plant disease. Plant pathogens can be 

fungi, bacteria, viruses, mycoplasmas or nematodes. Each has a different life cycle which 

includes an infectious stage. Most pathogens are host-specific to a particular plant species, genus, 

or family. Some diseases, such as the powdery mildews, produce similar symptoms on different 

plants. However, the fungi involved are usually host-specific. (Ohio State University Extension) 

 

 Fungi is one group of plant pathogens. They cause plant diseases such as rusts, smuts, 

and mildews. Fungal spores may be actively or passively released for dispersal by several 

effective methods (air dispersal, rain splash, flowing water dispersal, and forceable release). The 

function of some spores is not primarily for dispersal, but to allow the organisms to survive as 

resistant cells during periods when the conditions of the environment are not conducive to 

growth. Most phyla are terrestrial in origin, although all major groups have invaded marine and 

freshwater habitats. Wherever adequate moisture, temperature, and organic substrates are 

available, fungi are present. Although we normally think of fungi as growing in warm, moist 

forests, many species occur in habitats that are cold, periodically arid, or otherwise seemingly 

inhospitable. It is important to recognize that optimum conditions for growth and reproduction 

vary widely with fungal species. Fungi can be controlled using chemical, biological, and cultural 

practices.

 Bacteria are single celled organisms that can cause many plant diseases (such as fireblight, canker, and leaf spots). The infected plant can suffer significant yield losses or die 

prematurely. Bacterial diseases can be managed by chemical, biological or cultural practices. 

Nematodes are simple, multi-cellular organisms that look like worms. They are softbodied (no skeleton) non-segmented round worms. Most nematode species that attack plants are 

microscopic. Plant parasitic nematodes may attack the roots, stem, foliage, and flowers of plants. 

Nematodes can be controlled by chemical, physical, or biological methods. 

Part 2.2.2.a -- Identify the Problem

Prior to the first pesticide application covered under this permit that will result in a 

discharge to Waters of the United States, and at least once each calendar year thereafter 

prior to the first pesticide application for that calendar year, any Decision-maker who is or 

will be required to submit NOI must do the following for each pest management area, as 

defined in Appendix A. Decision-makers 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 Measures. Re-evaluation of the 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

79 

pest problem is also important to ensure Pest Management Measures are still applicable. 

Decision-makers must identify the pest problem at least once each calendar year prior to the first 

application for that calendar year.

Identify areas with pest problems and characterize the extent of the problems, 

including, for example, water use goals not attained (e.g. wildlife habitat, fisheries, 

vegetation, and recreation). Decision-makers must be well-acquainted with the unique 

regional conditions of their sites and available Pest Management Measures for controlling the 

pest 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 pest, as well as water use goals and complaints or 

reports of weeds and algae from the public. 

Identify target pest(s). Positive identification of the pest is required because many pests 

within the same genera may require different levels and types of Pest Management Measures. 

Pest identification is important when determining the best Pest Management Measures for each 

pest and for determining application areas. Decision-makers should develop Pest Management 

Measures based on identification of the targeted pest which occur in their area.

Identify possible factors causing or contributing to the pest 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 pest infestations, the identification of possible 

sources (e.g., outflows from other water systems/bodies) may help in reducing the need for 

pesticide. Potential weed and algae sources such as changes in nutrient levels or accidental or 

intentional introduction of exotic species must be identified. 

Establish any pest- and site-specific action threshold, as defined in Appendix A, for 

implementing Part 2.2.2b. Any data and/or information regarding pest can be used to establish 

an action threshold. An action threshold must be established.

In the event there are no data for the pest management area in the past calendar 

year, use other available data as appropriate to meet the permit conditions in Part 2.2.2.a. 

Decision-makers may use historical data or neighboring district data to identify the pest and 

establish action thresholds.

Part 2.2.2.b -- Pest Management Options

Prior to the first pesticide application covered under this permit that will result in a 

discharge to Waters of the United States, and at least once each calendar year thereafter 

prior to the first pesticide application for that calendar year, any Decision-maker who is or 

will be required to submit an NOI must select and implement efficient and effective means 

of Pest Management Measures that minimize discharges resulting from the application of 

pesticides to control pests. In developing the Pest Management Measures for each pest 

management area, the Decision-makers must evaluate the following management options, 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

80 

including a combination of these management options, considering impact to water quality, 

impact to non-target organisms, feasibility, and cost effectiveness: No action; Prevention; 

Mechanical/physical methods; Cultural methods; Biological control agents; and Pesticides.

Decision-makers must evaluate management options and implement Pest Management Measures 

to minimize pesticide discharges into Waters of the United States prior to the first pesticide 

application covered under this permit. As noted above, combinations of various management 

options are frequently the most effective Pest Management Measures over the long term. The 

goal should be to emphasize long-term control rather than a temporary fix. Decision-makers 

must reevaluate every year prior to the first pesticide application for that calendar year. All Pest 

Management 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 pest problem has been identified. This may be 

appropriate in cases where, for example, available pest management options 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 pest 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 pest, private entities (aquaculture) and the public have the 

necessary knowledge to assist in local pest control by reducing conditions that encourage the 

spread of pest in their immediate surroundings. For example, recreational water users provide a 

pathway of unintentional introductions. Increasing public awareness of 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 (e.g., 

hand weeding). Monitoring and detection also play important roles in the prevention of the 

spread and introduction of weeds and algae. 

Mechanical or Physical Methods

Mechanical control techniques will vary depending on the pest. Examples include 

dewatering, pressure washing, abrasive scrubbing, and weed removal by hand or machine. 

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 Pest 

Management Measures.

Cultural Methods

 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 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

81 

colorants and one or two dyes are EPA-registered for 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.6

Biological Control Agents

 Biological control of weeds and algae may be achieved through the introduction of 

diseases, predators, or parasites. While biological controls generally have limited application for 

control of weeds and algae, the Operator should fully consider this option in evaluating pest 

management options. 

Pesticides

Aquatic herbicides are chemicals specifically formulated for use in water to kill or 

control aquatic plants. Aquatic herbicides are sprayed directly onto floating or emergent aquatic 

plants as well as plants at or near the water’s edge 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 spectrum herbicides will generally affect all plants that they come 

in contact with. Selective herbicides will affect only some plants.7

Part 2.2.2.c. -- Pesticide Use

Conduct surveillance in an area that is representative of the pest problem prior to 

each pesticide application to assess the pest management area and to determine when the 

action threshold(s) is met. Often, each weed and algae and pest management area warrants a 

different Pest Management Measures tailored to the regional conditions. The Pest Management 

Measures should consist of combinations of mechanical, biological, and/or pesticidal control 

methods. All Pest Management Measures must be conducted in a manner that minimizes 

impacts to non-target species.

Decision-makers should apply chemical pesticides only after considering the alternatives 

and determining those alternatives not to be appropriate Pest Management Measures. Also, 

Decision-maker 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 

implementing Pest Management Measures.

 6 http://www.grounds-mag.com/mag/grounds_maintenance_weeds_overboard/ 7 http://www.ecy.wa.gov/programs/wq/plants/management/aqua028.html
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

82 

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 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 

thresholds help determine both the need to implement Pest Management Measures 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 pesticide applications 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 Weed and Algae Control References

EPA recommends the following sources for additional information on Pest Management 

Measures for weed and algae control:

Aquatic Nuisance Species Taskforce. Online: http://www.anstaskforce.gov/default.php. 

Getsinger, K., Moore, M. D., Layne, C. P., Petty, D. G., L, S., Sprecher, Dibble, E. D., Karcas, 

E., Maceina, M., Mudrak, V., Lembi, C., Madsen, J. D., Stewart, R. M., Anderson, L., Haller, 

W., Confrancesco, A., Newman, R., & Nibling, F. (2005). Aquatic Plant Management Best 

Management Practices in Support of Fish and Wildlife Habitat. Aquatic Ecosystem Restoration 

Foundation. Lansing, MI.

2.2.3 Animal Pest Control

Background 

Animal Pests, 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 animal pests become established 

and impede the environmental stability and use goals for a body of water, implementation of Pest 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

83 

Management Measures will become necessary. Animal aquatic pests also include insects, 

amphibians, and other animals that spend part or all of their life cycle at water’s edge, including 

near the water, as well as in or near Waters of the US that are not always “wet” (eg, ephemeral 

streams, seasonal waters).

The requirements in this Part apply to pesticide discharges associated with management 

of animal pest including fish, lampreys, insects, mollusks, and microorganisms. Animal pest 

control includes management of nuisance species in Waters of the United States including lakes, 

ponds, rivers, estuaries, and streams. Pest Management Measures for animal pest control should 

consider mechanical, biological, and chemical controls. Details for identifying animal pests and 

developing Pest Management Measures can be found online through the Aquatic Nuisance 

Species Taskforce (http://www.anstaskforce.gov/). 

Fish

Reasons for applications of piscicides in Waters of the United States 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; control of 

invasive species; and aquaculture. Pest Management Measures 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 United States waters. Lampreys may be managed using lampricides that are applied 

directly to the Waters of the United States. 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 Pest Management Measures.

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 

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 Animals

There may be animals of concern in addition to fish, lampreys, and mollusks. Control of 

other animals including, but not limited to, crustaceans, amphibians, or insects 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 Pest Management Measures for animal pests is dictated by the 

biology of the target pest and by environmental conditions and concerns for a specific area. 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

84 

Numerous Pest Management Measures are used to reduce the impact of animal pests, but 

integrated pest management should be the basis for any pest control program. This is a 

comprehensive approach for managing pest populations using a variety of Pest Management 

Measures.

Part 2.2.3.a-- Identify the Problem

Prior to the first pesticide application covered under this permit that will result in a 

discharge to Waters of the United States, and at least once each calendar year thereafter 

prior to the first pesticide application for that calendar year, any Decision-maker who is or 

will be required to submit an NOI must do the following for each pest management area, 

as defined in Appendix A. Decision-makers 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 Measures. Re-evaluation of the 

pest problem is also important to ensure Pest Management Measures are still applicable. 

Decision-makers must identify the pest problem at least once each calendar year prior to the first 

application for that calendar year

Identify areas with pest problems and characterize the extent of the problems, 

including, for example, water use goals not attained (e.g. wildlife habitat, fisheries, 

vegetation, and recreation). Decision-makers must be well-acquainted with the unique 

regional conditions of their sites and available Pest Management Measures for controlling the 

pest 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 

species, as well as water use goals and complaints or reports of pests from the public.

Identify target pest(s). Positive identification of the pest is required because many pest 

within the same genus may require different levels and types of Pest Management Measures. 

Animal identification is important when determining the best Pest Management Measures for 

each particular pest and for determining application areas. Decision-makers must develop Pest 

Management Measures based on identification of the targeted pest 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 pest infestations, the identification of possible sources (e.g., 

outflows from other water systems/bodies) may help in minimizing the need for implementing 

Pest Management Measures. Potential factors which could lead to the establishment of animal 

populations such as accidental or intentional introduction of exotic species must be identified 

before Pest Management Measures are implemented.

Establish any pest- and site-specific action threshold, as defined in Appendix A, for 

implementing Part 2.2.3.b. An action threshold should be established before implementing 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

85 

Pest Management Measures. Any data and/or information regarding pest can serve as an action 

threshold. 

In the event there are no data for the pest management area in the past calendar 

year, use other available data as appropriate to meet the permit conditions in Part 2.2.3.a. 

Decision-makers may use historical data or neighboring district data to identify the pest and 

establish action thresholds. 

Part 2.2.3.b -- Pest Management Options

Prior to the first pesticide application covered under this permit that will result in a 

discharge to Waters of the United States, and at least once each year thereafter prior to the 

first pesticide application during that calendar year, any Decision-maker who is or will be 

required to submit an NOI must select and implement efficient and effective means of Pest 

Management Measures that minimize discharges resulting from the application of 

pesticides to control pests. In developing the Pest Management Measures for each pest 

management area, the Decision-maker must evaluate the following management options, 

including a combination of management options, considering impact to water quality, 

impact to non-target organisms, feasibility, and cost effectiveness: No action; Prevention; 

Mechanical/physical methods; Biological control agents; and Pesticides.

Decision-makers are required to evaluate management options and implement Pest Management 

Measures to minimize pesticide discharges into Waters of the United States prior to the first 

pesticide application covered under this permit. As noted above, combinations of various 

management options are frequently the most effective Pest Management Measures over the long 

term. The goal should be to emphasize long-term control rather than a temporary fix. Decisionmakers must reevaluate every year prior to the first pesticide application for that calendar year. 

All Pest Management Measures must be conducted in a manner that minimizes impacts to nontarget species. The following describes the management options that must be evaluated. 

No Action

No action is to be taken, although an animal pest 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 animals, private entities (aquaculturists) 

and the public have the necessary knowledge to assist in local animal control by reducing 

conditions that encourage the spread of animals in their immediate surroundings. For example, 

recreational water users provide a pathway of unintentional introductions. Increasing public 

awareness of pests, 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 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

86 

removal of pest species (e.g., fishing). Monitoring and detection also play important roles in the 

prevention of the spread and introduction of pests. 

Mechanical or Physical Methods

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 Agents

 Biological control of animals may be achieved through the introduction of diseases, 

predators, or parasites. While biological control generally has limited application for control of 

animals, Decision-makers should fully consider this option. 

Pesticides

Chemical and biological pesticides such as lampricides, molluscides, insecticides, and 

piscicides, are registered for use to control animal pests. 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.

Part 2.2.3.c. -- Pesticide Use

Conduct surveillance in an area that is representative of the pest problem prior to 

each application to assess the pest management area and to determine when the action 

threshold(s) is met. Often, each animal and pest management area warrants a different Pest 

Management Measures, tailored to the regional conditions. Pest Management Measures should 

consist of combinations of mechanical, biological, and/or pesticidal control methods. All Pest 

Management 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 Pest Management 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 Pest Management Measures must be implemented, including 

use of the minimum effective application rate. Also, the Decision-maker 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 implementing Pest Management 

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 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

87 

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(s) has been met. The pest 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 pesticide applications 

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. For piscicides, chemical deactivation is currently required for all lotic (flowing water) 

environments. Management agencies typically work down the watershed in consecutive 

treatments as this will require the least amount of chemical deactivation. Most invertebrates 

repopulate treated areas through immigration (typically in the direction of flow); as such 

headwater streams/tributaries seem to be effective at accomplishing this. EPA also notes that not 

all piscicides are that harmful to invertebrate populations (e.g., antimycin is more selective for 

scaled fish). It can be difficult to know the point at which headwater streams are "fishless"; 

however, most fishery management agencies do not treat streams unless they are considered a 

refuge for target species.

Recommended Animal Pest Control References

EPA recommends the following sources for additional information on Pest Management 

Measures for animal control:

Aquatic Nuisance Species Taskforce. Online: http://www.anstaskforce.gov/. 

Getsinger, K., Moore, M. D., Layne, C. P., Petty, D. G., L, S., Sprecher, Dibble, E. D., Karcas, 

E., Maceina, M., Mudrak, V., Lembi, C., Madsen, J. D., Stewart, R. M., Anderson, L., Haller, 

W., Confrancesco, A., Newman, R., & Nibling, F. (2005). Aquatic Plant Management Best 

Management Practices in Support of Fish and Wildlife Habitat. Aquatic Ecosystem Restoration 

Foundation. Lansing, MI.

2.2.4 Forest Canopy Pest Control

Background

The forest canopy is the uppermost level of the forest. It is composed of treetops, or the 

crowns of the 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 environmentfriendly Pest Management 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 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

88 

area. Forest canopies may also include the tops or crowns of immature trees, where pesticide 

application is necessary to control pests that live in or threaten these areas.

Forest canopy pest control programs included in this permit are treetop pesticide 

applications that may inadvertently expose Waters of the United States 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 United States.

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. 

Part 2.2.4.a -- Identify the Problem

Prior to the first pesticide application covered under this permit that will result in a 

discharge to Waters of the United States, and at least once each calendar year thereafter 

prior to the first pesticide application in that calendar year, any Decision-maker who is or 

will be required to submit an NOI must do the following for each pest management area, as 

defined in Appendix A. In order to reduce pesticide discharges into Waters of the United States 

associated with forest canopy pest control, it is important for Decision-makers 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 implement Pest 

Management Measures.

Establish any pest- and site-specific action threshold, as defined in Appendix A, for 

implementing Part 2.2.4.b. Decision-makers must develop action thresholds for the target pests 

prior to first pesticide application covered under this permit. The action thresholds must be reevaluated 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 

Management Measures must be taken. Action thresholds help determine both the need for 

implementing Pest Management Measures and the proper timing of such actions. It is a 

predetermined pest level that is deemed to be unacceptable.

Identify target pest(s) to develop Pest Management Measures based on 

developmental and behavioral considerations for each pest. 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 pest 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 Pest Management Measures, applicable control techniques, and most effective 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

89 

chemical pesticides for the target pests (insecticide class, resistance, etc.). Failure to identify 

pests can lead to unwarranted control activities and/or the need for chemical application with 

potential for discharges into Waters of the United States. 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 Pest Management 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 Pest Management Measures. 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 Pest Management Measures. 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 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 the pest management area in the past calendar 

year, use other available data as appropriate to meet the permit conditions in Part 2.2.4.a. 

Decision-makers may use historical data or neighboring district data to identify the pest and 

establish action thresholds.

Part 2.2.4.b. -- Pest Management Options

Prior to the first pesticide application covered under this permit that will result in a 

discharge to Waters of the United States, and at least once each calendar year thereafter 

prior to the first pesticide application for that calendar year, any Decision-maker who is or 

will be required to submit an NOI must select and implement efficient and effective means 

of Pest Management Measures that minimize discharges resulting from the application of 

pesticides to control pests. In developing the Pest Management Measures for each 

management area, the Decision-maker must evaluate the following management options, 

including a combination of management options, considering impact to water quality, 

impact to non-target organisms, 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 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

90 

producing the best control results, Pest Management Measures 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 options are frequently the most effective Pest 

Management Measures over the long term. The goal of Pest Management Measures in forest 

canopy pest control should be to emphasize long-term control rather than a temporary fix. 

All Pest Management 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 pest 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/Physical Methods

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 measures 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). 

Cultural Methods

Cultural control methods are Pest Management Measures 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. 

Biological Control Agents

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 

option in the development of Pest Management Measures. The latter two control approaches are 

often utilized when controlling for gypsy moth.

Pesticides

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 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

91 

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. 

Part 2.2.4.c. -- Pesticide Use

Conduct surveillance in an area that is representative of the pest problem prior to 

each application to assess the pest management area and to determine when the pest action 

threshold is met. Decision-makers must apply pesticides only as needed as determined by preestablished criteria and pest action thresholds. Decision-makers 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 Measures. 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 Pest 

Management Measures efficacy and to monitor for new pests. Surveillance can determine if the 

current techniques are effective and whether additional Pest Management Measures are required, 

particularly pesticide application. Based on follow-up surveillance activity, Decision-makers can 

make informed decisions which serve to increase the effectiveness of their control programs and 

minimize the potential for pesticide discharges to Waters of the United States. Surveillance is 

necessary not only to establish the pest 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.

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 threshold(s) have been met. Forest canopy pest 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 considered. 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

92 

Environmental factors such as temperature, as well as biological factors such as migration timing 

should be considered when deciding on application timing. Partial site pesticide applications 

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 should weigh the potential 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. 

Gypsy moth caterpillars are susceptible to control by chemical pesticides, or by ingestion of 

nucleopolyhedrosis virus occlusion bodies. 

Recommended Forest Canopy Pest Control Reference

EPA recommends the following source for additional information on Pest Management 

Measures 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

USDA. 2009. Gypsy Moth Program Manual. 

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

Kucera, Daniel and P. Orr. Spruce Budworm in the Eastern United States. U.S Department of 

Agriculture, Forest Service. Forest Insect and Disease Leaflet 160. Retrieved 3/12/09 at 

http://www.na.fs.fed.us/spfo/pubs/fidls/sbw/budworm.htm

Michael, Jerry. 2004. Best Management Practices for Silvicultural Chemicals and the Science 

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

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:

All Operators must control discharges as necessary to meet applicable numeric and 

narrative state, territory, or tribal water quality standards, for any discharges 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

93 

authorized under this permit, with compliance required upon beginning such 

discharge. 

If at any time an Operator becomes aware (e.g., through self-monitoring or by 

notification from the state, tribe, or territory), or EPA determines, that a discharge 

causes or contributes to an excursion of any applicable water quality standards, the 

Operator must take corrective action as required in Part 6 and Appendix B, Section 

B.3, up to and including the ceasing of the discharge, if necessary. 

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 

Operator. 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 Operator 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: 

(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, although limited in scope, show that, in most 

samples, most pesticides were below ambient water quality criteria or benchmarks 

developed by EPA’s Office of Pesticide Programs (OPP). For this assessment, ambient 

water quality criteria were available for 7 of the 83 analytes and one or more OPP 

benchmarks were available for 60 of the 83 analytes. 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 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

94 

resource waters) except for pesticide applications made to restore or maintain water 

quality or to protect public health or the environment that either do not degrade water 

quality or only degrade water quality on a short-term or temporary basis.

In addition to the five factors identified above, before issuance, EPA permits require 

CWA §401 certification by states, territories, and tribes. The states, territories, and tribes 

included in this permit have reviewed the permit and certified that it will meet their water quality 

standards. In this process, some states, territories, and tribes have, in this process, added further 

conditions to ensure that water quality standards will be met. Part 9 of the permit includes those 

additional conditions so required by any state, territory, or tribe in areas where this permit is 

available.

This permit requires Operators to control discharges as necessary to meet applicable 

water quality standards. When the Operator 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 Operator 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 Pest 

Management Measures are required, EPA expects the Operator to vigilantly and in good-faith 

follow and document, as applicable, the process for Pest Management Measure 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 

intended for distribution or sale in the United States. 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 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

95 

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 

of potential risk.8 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 Characterization 

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.

 8 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 2011 NPDES Pesticide General Permit Fact Sheet

96 

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 pesticide application 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 

United States 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, the detection limits, and the purpose of the monitoring studies from which the data are 

derived when determining how such data will be incorporated into the FIFRA risk assessment 

and the usefulness of the monitoring data for an aquatic exposure assessment. For example, a 

monitoring study targeted to measure concentrations of a pesticide in a watershed with high 

agricultural use 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 the FIFRA 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. 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

97 

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 ECOTOX9. 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 Overview10 document, which describes the process OPP uses to 

conduct ecological risk assessment under FIFRA, OPP evaluates other data on sublethal effects 

in addition to direct effects on survival, growth and reproduction. 

In general, the current FIFRA 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.

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 assessment11

Risk Characterization 

. 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 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 FIFRA screening-level assessments, OPP 

relies on the deterministic risk quotient (RQ) method to compare estimated exposure to toxicity 

 9 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/. 10 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 11 Ibid U.S. EPA 2004
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

98 

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 Benchmarks 

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. 

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 FIFRA 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 identify 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. 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

99 

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 degradates of these herbicides, 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 

rather than on additive and synergistic toxic effects of exposure to multiple pesticides and/or 

non-pesticide toxicants. 

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 

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 FIFRA 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 

may be potential for the pesticide to cause adverse effects to the given taxon.
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

100 

 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.12 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.”13

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.

United States 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)14 released a 10-year (1992-2001) study of 51 major river basins and aquifer 

systems that account for more than 70 percent of total United States water use and more than 50 

percent of the United States 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 

 12 Correspondence to SFIREG, November 3, 2006 from Office of Water director. 13 OPP Aquatic Benchmark Table http://www.epa.gov/oppefed1/ecorisk_ders/aquatic_life_benchmark.htm 14 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.
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

101 

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 under FIFRA with respect to 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 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 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

102 

Impaired Waters and Total Maximum Daily Loads website15 (accessed November 2009) 

indicates 303(d) impairments in several states for 12 currently registered specific pesticides and 

4 general classes of pesticides (e.g., pyrethroids; 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 pesticide active ingredients listed as causes of 303(d) impairment 

(data accessed November 2010). 

Cause of Impairment States

2-Methylnaphthalene CA, NH, WA

Atrazine IA, IL, KS, MO, NE, OH

Azinphos-methyl CA, OR

Carbofuran CA

Chlorpyrifos CA, OK, OR, WA

Dacthal CA

Diazinon CA, OK, WA

Endosulfan CA, MT, WA

Malathion CA

Methyl parathion CA

Naphthalene NH, WA

Phthalates WA

Pyrethroids CA

Tributyltin VA

Xylenes CA

Pesticides – listed generically CA, HI, IN, MA, NY, OH, PA, PR, WA

According to the Office of Water’s Impaired Waters and Total Maximum Daily Loads 

website there are a total of 71,323 causes of impairments for 303(d) listed waters16. Of these, 

approximately 2.6% (a total of 1,865) are listed as pesticides. The majority (74.3% or 1,386 of 

the 1,865) of impairments attributed to pesticides are for those no longer registered for use by the 

EPA. A total of 19.9% (372 of the 1,865) of impairments are attributed to currently registered 

pesticides, with an additional 5.7% (107 of the 1,865) of the impairments listed generically for 

pesticides, such as for “pesticides” or “organochlorine pesticides.” Combined, these two 

categories of listings account for 0.7% (479 of 71,323) 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, 3,401 impairments are listed for “impaired biota” and 1,317 

impairments are for an “unknown” or “cause unknown – fish kills”, which together account for 

about 6.6% of all impairments. 

 15 http://iaspub.epa.gov/waters10/attains_nation_cy.control?p_report_type=T 16 http://iaspub.epa.gov/waters10/attains_nation_cy.control?p_report_type=T
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

103 

EPA has received ambient monitoring data for pesticides present in waters that are 

attributable to a variety of types of pesticide use patterns from states and other stakeholders. 

These data are included in the administrative record for this permit (see docket number EPAHQ-OW-2010-0257) and in general, do not show the presence of pesticides in concentrations 

above levels of concern (i.e., recommended ambient water quality criteria – available at 

http://epa.gov/waterscience/criteria/wqctable/ or FIFRA OPP 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 cycle17, which was submitted in January 2009, the Agency reported the results on the 

portion of Waters of the United States 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 as described above account for the majority (74.3%) of water 

impairments caused by 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.

 17 http://www.epa.gov/owow/305b/2004report/
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

104 

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 

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 that the technology-based effluent limitations are as stringent as necessary 

to meet WQS. These effluent limitations require Operators to minimize the discharge of 

pesticides through the use of the most efficient and effective means of Pest Management 

Measures, including pesticide and non-pesticide methods.

The technology-based effluent limitations require Applicators to minimize the discharge 

of pesticides by using only the amount of pesticide and frequency of pesticide application 

necessary to control the target pest, maintaining pesticide application equipment in proper 

operating condition, and ensuring weather conditions in the treatment area are appropriate for 

pesticide application.
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

105 

The Applicator, to the extent not determined by the Decision-maker, must also use only 

the amount of pesticide and frequency of pesticide application necessary to control the target 

pest, using equipment and application procedures appropriate for the task. 

Certain Decision-makers are also required to more fully assess and implement procedures 

to minimize the discharge of pesticides. In this assessment, these Decision-makers must 

consider human health and ecological impacts, 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, 

these Decision-makers must identify target pest species and areas where those pests occur, 

identify the possible sources of the problem, and establish action thresholds or similar measures 

for implementing pest management strategies. The technology-based effluent limitations in Part 

2.2 also require certain Decision-makers, as appropriate to analyze surveillance data prior to each 

pesticide application 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 Operators to monitor pesticide applications activities to minimize discharges and during 

any post-application monitoring to determine effectiveness of the pesticide application. In 

addition, Part 6.0 of the general permit contains requirements for all Operators to document and 

report adverse incidents involving non-target organisms or the environment, and to take 

corrective action if it is determined that revising Pest Management 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 Operators 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 United States from the 

use patterns covered under this permit.

(4) Biological pesticides do not work through a toxic mode of action, or when they do, are 

toxic only to a very narrow range of target pest organisms. 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 United States is considered a pollutant since the intended purpose of 

the application is to target pests above the water. Therefore, the concentrations of “pollutants” 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

106 

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 which do operate by a toxic mode of action yet they are toxic only 

to a very narrow range of target pest organisms (mosquito larvae). Biochemical pesticides, as 

defined at 40 CFR 158.2000(a), are naturally occurring substances that control pests by nontoxic 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) except for applications made to restore or maintain water quality or to 

protect public health or the environment that either do not degrade water quality or only 

degrade water quality on a short-term or temporary basis.

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) any discharges from a pesticide application to 

Waters of the United States if the water is identified as impaired by a substance which either is 

an active ingredient in that pesticide or is a degradate of such an active ingredient and (2) 

discharges to Tier 3 Waters (i.e., Outstanding National Resource Waters) except for pesticide 

applications made to restore or maintain water quality or to protect public health or the 

environment that either do not degrade water quality or only degrade water quality on a shortterm or temporary basis. Any Operator desiring to discharge in either of these two scenarios is 

required to submit an application for an NPDES individual permit. Links to lists of impaired 

waters and Tier 3 waters is available at www.epa.gov/npdes/pesticides. Additional discussion of 

the basis for these requirements is provided in Part III.1.1.2 of the fact sheet.

4. Site Monitoring 

 Monitoring is required in any NPDES permit to demonstrate compliance with the permit 

conditions. Monitoring requirements apply from the time any authorized Operator begins 

discharging under this permit. These requirements are not tied to submission of an NOI. There 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

107 

are a variety of monitoring methods that a “traditional” NPDES permit may require, including 

end-of-pipe monitoring to show compliance with relevant water quality-based and technologybased 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 sections 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 control activity and/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. 

 In addition, EPA will collect information required from permittees. EPA will also solicit 

and collect information and water quality monitoring and other data from states, federal 

agencies, and other entities on water quality to help determine the presence of pesticides, 

degradates, metabolites, etc. EPA will encourage states, federal agencies, and other entities to 

collect this information. The Agency will compile and analyze this information and data and has 

agreed to meet with NMFS annually during the permit term to present and discuss the results and 

identify data gaps and possible approaches to address the gaps.

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. For example, a 

manufacturing plant would 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 be inappropriate to compare with any type of technology 

based 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.
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

108 

2) Lack of applicable measurable standards: Federal pesticide-specific ambient water quality 

criteria 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 infeasibility of requiring 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. Routine visual monitoring 

is required in the PGP and can be used 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 Visual Monitoring Requirements for Pesticide Applicators 

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. This requirement consists 

of visually monitoring the area to and around where pesticides are applied for possible and 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

109 

observable adverse incidents, such as unanticipated death or distress of non-target organisms and 

disruption of wildlife habitat, recreational or municipal water use.

Visual monitoring assessments are required during the pesticide application when 

feasibility and safety allow. Visual monitoring is not required during the course of pesticide 

application when that application 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.

4.2 Visual Monitoring Requirements for all Operators

Visual monitoring must also be conducted during any post-application surveillance, such 

as to determine the efficacy of the pesticide application. Visual monitoring of this type is 

required of all Operators but only if the Operator, be it the Applicator or the Decision-maker or 

both, performs post application surveillance in the course of business. EPA expects that postapplication visual assessments are reasonably conducted on foot or from a stationary vehicle, 

although they might also be conducted from a moving vehicle, including a boat or plane, in 

certain circumstances.

5. Pesticide Discharge Management Plan (PDMP)

Any Decision-maker who is or will be required to submit an NOI and is not a small 

entity18

Any Decision-maker who is or will be required to submit an NOI and is a small entity 

(i.e., is below the SBA size standard as, as defined at 13 CFR. 121.201, or is a public entity 

serving a population of 10,000 or less), is not required to develop a PDMP. Small entity 

Decision-makers are required to document activities as described in Part III.7 of this fact sheet. 

EPA recognizes that SBA defines “small entities” as including government entities that serve 

populations of less than 50,000 persons. However, EPA’s NPDES program has historically 

considered “major” municipal NPDES permits as those that serve greater than 10,000 persons 

(i.e., with a wastewater treatment plant design of greater than one million gallons a day). Major 

 must develop a PDMP, except for any pesticide applications made in response to a 

Declared Pest Emergency situation, as defined in Appendix A of the permit or any Decisionmaker who is or will be required to submit an NOI solely because of discharges to Waters of the 

United States containing NMFS Listed Resources of Concern, as defined in Appendix A of the 

permit. EPA defines a Decision-maker that is not a small entity as a large entity in the permit. 

Large entity Decision-makers must prepare the PDMP by the time the NOI is filed.

 18 A small entity is any (1) private enterprise that does not exceed the Small Business Administration size 

standard as identified at 13 CFR 121.201, or (2) local government that serves a population of 10,000 or less.
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

110 

NPDES permittees have increased recordkeeping and public notice obligations over minor 

NPDES which is consistent with EPA’s intent for the PGP to impose additional recordkeeping 

and reporting information only on these larger communities. 

The PDMP itself does not contain effluent limitations; rather it constitutes a tool both to 

assist the Decision-maker in documenting what pest management 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. Developing a PDMP helps Decision-makers

ensure they have (1) taken steps to identify the pest problem, (2) evaluated pest management 

options, and (3) selected appropriate pest management measures to control pesticide discharges. 

A PDMP is a “living” document that requires reviews and must be kept up-to-date. Where pest 

management 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. All changes 

to the PDMP must be made before the next pesticide application that results in a discharge, if 

practicable, or if not, no later than 90 days after any change in pesticide application activities. 

Failure of a Decision-maker to develop and maintain an up-to-date PDMP is a violation of 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).

A PDMP must include identification of the pesticide discharge management team, a 

description of the pest problem, and a description of the pest management options evaluation. 

Decision-makers must also provide response procedures for spill response and adverse incident 

response. The size of a pest management area is determined by the Decision-maker responsible 

for and with the authority to conduct pest management activities. For example, the pest 

management area for a mosquito control district is the total area of the district. Once the plan is 

developed, the Decision-maker must maintain the plan thereafter for the duration of coverage 

under this general permit. For any Decision-maker for which the annual treatment area threshold 

triggers the NOI requirement (and the Decision-maker is a large entity), the Decision-maker 

must keep the plan up-to-date for the duration of permit coverage even if the annual treatment 

area subsequently falls below the annual treatment area threshold.

Decision-makers may choose to reference other documents, such as a pre-existing pest 

management plan or spill prevention and response plan, in the PDMP rather than recreating the 

same text in the PDMP. It is not required that a Decision-maker must have authored the preexisting plan in order to use it. When referencing other documents, the Decision-maker 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 Decisionmaker 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, Decision-makers must document the following: (1) a pesticide discharge 

management team; (2) a description of the pest management area and the pest problem; (3) a 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

111 

description of pest management options evaluation; (4) response procedures for spill response 

and adverse incident response; 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 discharges covered under the permit. Identification of a pesticide discharge 

management team ensures 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 Pest Management 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 Decisionmakers will have more than one individual on the team, except for those 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. 

Problem Identification

This section 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 Decision-makers in 

subsequent efforts to identify and set priorities for the evaluation and selection of Pest 

Management 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 historical data or other available data (e.g., 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 and 

method(s) to determine when the action threshold(s) has been met. An action threshold is a level 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

112 

of pest prevalence (or other indicator) 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 

United States. 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.

4. Water Quality Standards 

Operators must identify any Tier 3 (Outstanding National Resource Waters and any 

water(s) impaired for a specific pesticide or its degradates to which there may be a discharge. 

Internet links to all state, territory and tribal water quality standards are available at: 

http://epa.gov/waterscience/standards/wqslibrary/.

Description of Pest Management Measures Options Evaluation

The permit requires that the PDMP include a description of the Pest Management 

Measures implemented to meet the applicable technology-based or water quality-based effluent 

limitations. The description must include a brief explanation of the Pest Management Measures 

used at the site to reduce pesticide discharge, including evaluation and implementation of the six 

management options (no action, prevention, mechanical/physical methods, cultural methods, 

biological control agents, and pesticides). Decision-makers must consider impact to non-target 

organisms, impact to water quality, feasibility, and cost effectiveness when evaluating and 

selecting the most efficient and effective means of Pest Management Measures to minimize 

pesticide discharge to Waters of the United States.

All six management options may not be available for a specific use category and/or 

treatment area. However, the PDMP must include documentation of how the six management 

options, including combination of these options, were evaluated prior to selecting a site specific 

Pest Management Measures. For the no action option, Operators should document the impact of 

this option without any current Pest Management Measures at the site. For the prevention 

management option, the Decision-maker 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, Decision-makers should 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 

United States.
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

113 

Response Procedures

The following procedures necessary to minimize discharges must 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. 

2. Adverse Incident Response Procedures 

In the PDMP, Decision-makers must document appropriate procedures for responding to 

an adverse incident resulting from pesticide applications. Decision-makers must identify and 

document the following: 

• Procedures for responding to any adverse incident resulting from pesticide applications;

• Procedures for notification of the adverse incident, both internal to the Decision-maker’s 

agency/organization and external.; 

• State/Federal permitting agency 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).

Documentation to Support Eligibility Considerations under other Federal Laws [reserved]

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 Decision-maker 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 Pest Management Measures as 

necessary to meet the effluent limitations in this permit (Part 2). Keeping the PDMP up-to-date 

will help the Decision-maker ensure that the condition that triggered the corrective action does 

not reoccur. All changes to the PDMP must be made before the next pesticide application that 

results in a discharge, if practicable, or if not, no later than 90 days after any change in pesticide 

application activities or after an annual review.
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

114 

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 Decision-maker 

changes its spill response procedures, but fails to update its PDMP to reflect these changes, a 

recordkeeping violation will result. The Decision-maker must revise its PDMP to reflect the new 

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 United States 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. 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 Pest Management Measures in this permit. 

Corrective action requirements apply from the time any authorized Operator begins discharging 

under this permit. These requirements are not tied to submission of an NOI. Corrective actions 

in this permit are follow-up actions an Operator must take to assess and correct problems. They 

require review and revision of Pest Management 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 Operator 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 Operators in complying with the requirements of the permit on a consistent 

basis. Compliance issues with some of the permit’s requirements -- for instance, those related to 

reporting and recordkeeping and some of those related to operation and maintenance -- may be 

able to be corrected immediately simply by following already established procedures, and 

therefore, are not considered problems that trigger the corrective action provisions of the permit.

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 Pest Management 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 Pest Management Measures

 Operators are required to review and, as necessary, revise the selection and 

implementation of their Pest Management Measures to eliminate any of the following situations:
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

115 

- An unauthorized release or discharge associated with the application of pesticides (e.g., spill, 

leak, or discharge not authorized by this or another NPDES permit) occurs; 

- Operators become aware, or EPA concludes, that Pest Management Measures are not 

adequate/sufficient for the discharge to meet applicable water quality standards;

- Any monitoring activities indicate failure to meet applicable technology-based effluent 

limitations in Part 2;

- An inspection or evaluation by an EPA official, or local, state, or Tribal entity, determines 

that modifications are necessary to meet the non-numeric effluent limitations detailed in Part 

2 of the PGP; or 

- An Operator observes or is otherwise made aware (e.g., a third party notification) of an 

adverse incident.

 EPA considers the above situations to be of significant concern. Thus, EPA is requiring 

Operators to assess the cause of these situations which may be affiliated with the Operator’s 

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 the 

effectiveness of Pest Management Measures and corrective actions as integral to an effective 

pesticide management program. Written records associated with corrective action assessments 

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 or, if not practicable, as 

soon as possible after the next pesticide application that results in a discharge.” 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 Pest 

Management 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 Operator’s Pest Management 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 Operator 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.

 

6.3 Effect of Corrective Action

 The occurrence of a situation described in Part 6.1 may, but does not necessarily, 

constitute a violation of the permit. The occurrence of a situation identified in Part 6.1 does 

require the Operator to immediately review and as necessary, revise the selection and 

implementation of their Pest Management Measures to eliminate the situation. Part 6.3 explains 

that taking corrective action does not absolve the Operator of any liability for a permit violation 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

116 

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 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 Parts 6.1 and 6.2 if such requirements conflict. 

6.4 Adverse Incident Documentation and Reporting

Part 6.4 of the PGP requires Operators to take specific actions in response to identified 

adverse incidents which may have resulted from a discharge from the Operator’s pesticide 

application. Namely, Operators are required to provide oral notice to EPA within 24 hours and 

then follow-up with a written report within 30 days of becoming aware of the adverse incident. 

EPA defines an “adverse incident” in Appendix A of the permit, but generally it is defined as any 

effect of a pesticide’s use that is unexpected or unintended in which there is evidence that a 

person or non-target organism has likely been exposed to a pesticide residue and suffered a toxic 

or adverse effect.

 Part 6.4.1 requires Operators 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 Operators to document the 

information identified in 6.4.1, including the date and time that EPA was notified and a 

description of any deviations from 6.4.1 notification requirements based on nuances of the 

adverse incident. For example, an Operator 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 Operators 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 30 

days of discovering the adverse incident. The adverse incident report must include the following 

information: 

• Information required to be provided in Part 6.4.1.1; 

• 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.);

• 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);

• Quantity of pesticide applied and EPA registration number of pesticide product, 

intended use site (e.g., banks, above, or direct to water), and method of application; 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

117 

• Description of the habitat and the circumstances under which the incident occurred 

(including any available ambient water data for pesticides applied);

• Information on any laboratory tests performed and test results; and 

• 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, as well as re-evaluations of 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 

incident related to a discharge of pesticides during application. EPA acknowledges that some 

degree of detrimental impact to non-target species may occur and may be acceptable during the 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

118 

course of normal pesticide application. 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 fish, 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 pest control 

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 Pest 

Management Measures.

Complete information concerning adverse impacts will aid EPA in any review of current 

or future pesticide use, adherence to Pest Management Measures, or effectiveness of these 

measures. Reporting of adverse incidents is not required under this permit in the following 

situations: (1) you are aware of facts that indicate 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, even for these situations, certain records must be 

kept on site by those Decision-makers who are required to submit NOIs, pursuant to Part 7.3 and 

7.4 of the permit.

6.5 Reportable Spills and Leaks

Part 6.5.1 requires Operators to call the appropriate EPA Incident Reporting Contact to 

report any spill or leak of a hazardous substance or oil into Waters of the United States with 24 

hours of becoming aware of the spill or leak.19

 19 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.

 Part 6.5.2 requires Operators to document this 

notification within 30 days of becoming aware of such spill or leak. If the spill or leak triggers 

the notification in Part 6.5.1 and results in an adverse incident, then Operators must report the 

incident per the guidelines in Part 6.4.1 and 6.4.2. If the spill or leak triggers the notification in 

Part 6.5.1, but does not result in an adverse incident, then Operators must document and retain 

information outlined in Part 6.5.2 within 30 days of becoming aware of the situation. 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 Operators to 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

119 

notify either the National Marine Fisheries Service or the United States Fish and Wildlife Service 

if the Operator 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. 

6.6 Documentation for Other Corrective Action

 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 Operators must 

document basic information describing the event and the Operators’ response to that event within 

30 days. For triggering events in Part 6.1, where the Operator determines that any revision to 

Pest Management Measures is not necessary, the Operator must still document the review and 

the basis for this determination. EPA is not requiring Operators to submit this documentation to 

the Agency. Rather, EPA expects Operators 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 Operators subject to the annual reporting requirement. 

7. Recordkeeping and Annual Reporting

This permit requires all Decision-makers and Applicators to maintain certain records to 

help them assess performance of Pest Management Measures and to document compliance with 

permit conditions. Recordkeeping and reporting requirements apply from the time any 

authorized Operator begins discharging under this permit. These requirements are consistent 

with Federal regulations at 40 CFR 122.41(j), but have been tailored to more closely reflect the 

requirements in the PGP. This permit requires a basic set of records to be maintained by all 

Decision-makers and Applicators, as well as separate requirements depending on the type of 

Operator (i.e., Applicator, For-Hire Applicators, NOI submitting Decision-maker that is a small 

entity and NOI submitting Decision-maker that is a large entity). Part 7 of the permit sets forth 

the recordkeeping requirements for each of these types of Operators. Operators can rely on 

records and documents developed for other programs, such as requirements under FIFRA, 

provided all requirements of the permit are satisfied.

 EPA has found that it is appropriate and reasonable to require different records for 

different types of Operators, reasoning that the recordkeeping responsibilities assigned in the 

permit reflect the nature of involvement in pesticide application activities for the Operators 

described. The following sections describe the sets of records that the permit requires different 

types of Operators keep, and enumerates the specific information items to be recorded.

7.1 Records to be kept by all Operators (all Decision-makers and all Applicators)

These records must be kept by all Operators, including those not submitting an NOI. 

Although this section is a universal requirement, these particular records are necessary only in 

the event of an adverse incident, the case that corrective action was required, or in the event of a 

discharge resulting from a spill or leak.

a. A copy of any Adverse Incident Reports (See Part 6.4.2); 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

120 

b. Rationale for any determination that reporting of an identified adverse incident is 

not required, consistent with allowances identified in Part 6.4.1.2; 

c. A copy of any corrective action documentation (See Part 6.6); and, 

d. A copy of any spill and leak or other unpermitted discharge documentation (See 

Part. 6.5.2) 

7.2 Records to be kept by all For-Hire Applicators

All Operators who are For-Hire Applicators, as defined in Appendix A of the permit, 

must keep the records listed above, as well as records that specifically document pesticide 

application equipment maintenance and details of the pesticide application event. Since 

Decision-makers who are not themselves performing pesticide applications are generally not able 

to record such information, EPA requires different recordkeeping requirements depending on 

the type of Operator. 

a. Documentation of equipment calibration; and

b. Information on each treatment area to which pesticides are discharged, including: 

1. Description of each 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 pesticide(s) are discharged; 

2. Pesticide use pattern(s) (i.e., mosquito and other flying insects, weed and algae, 

animal pest, or forest canopy); 

3. Target pest(s);

4. Documentation of any assessment of weather conditions in the treatment area 

prior to and during application to ensure application is consistent with all 

applicable federal requirements;

5. Name of each pesticide product used including the EPA registration number; 

6. Quantity of each pesticide product applied to each treatment area;

7. Pesticide application date(s); and

8. Whether or not visual monitoring was conducted during pesticide application 

and/or post-application and if not, why not and whether any unusual or 

unexpected effects identified to non-target organisms.

7.3 Records to be kept by Small Entities, Submitting an NOI

As mentioned in Part 5, any Decision-maker that is required to submit an NOI and is 

below the SBA thresholds for small businesses or is a public entity serving a population of fewer 

than 10,000, is defined as a small entity in the permit. Beginning January 12, 2012, small entities 

are required to keep a basic records set, outlined in Part 7.3 of the permit, all of which can be 

recorded on the Pesticide Discharge Evaluation Worksheet provided in PGP Appendix F. 

Decision-makers who are required to submit an NOI and who are defined as small 

entities (as identified in Part 5) are required to keep the following records at the address provided 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

121 

on the NOI, as identified in Part 1.2.2. A worksheet for documenting this information on each 

treatment area is provided in Appendix F, Pesticide Discharge Evaluation Worksheet. 

a. Copy of the NOI submitted to EPA, any correspondence exchanged between the 

Decision-maker and EPA specific to coverage under this permit, and a copy of the 

EPA acknowledgment letter with the assigned permit tracking number;

b. Documentation of equipment calibration (only if Decision-maker is also the 

Applicator);

c. Information on each treatment area to which pesticides are discharged, including:

1. Description of treatment area, including location and size (acres or linear 

feet) of treatment area and identification of any Waters of the United 

States, either by name or by location, to which pesticide(s) are discharged; 

2. Pesticide use pattern(s) (i.e., mosquito and other flying insects, weed and 

algae, animal pest, or forest canopy);

3. Target pest(s) and explanation of need for pest control; 

4. Description of pest management measure(s) implemented prior to the first 

pesticide application;

5. Company name and contact information for pesticide applicator; 

6. Name of each pesticide product used including the EPA registration 

number; 

7. Quantity of each pesticide product applied to each treatment area; 

8. Pesticide Application Start Date;

9. Pesticide Application End Date; and

10. Whether or not visual monitoring was conducted during pesticide 

application and/or post-application and if not, why not and whether any 

unusual or unexpected effects identified to non-target organisms.

7.4 Records to be kept by Large Entities, Submitting an NOI

 

Any Decision-maker that is required to submit an NOI and is above the Small Business 

Administration (SBA) threshold for a small business or a public entity that serves a population of 

10,000 or more is defined as a large entity in the permit. Beginning January 12, 2012, large 

entities are required to keep the records listed in Part 7.4 of the permit. EPA expects that large 

entities will have a greater capability than small entities to record specific details of the pest 

treatment area, and is therefore requiring slightly more comprehensive recordkeeping. In 

addition, much of the records set for large entities are reflected in the annual report that these 

entities must submit. The reported information will allow EPA to better characterize the 

discharges resulting from pesticide applications in a variety of different circumstances.

Decision-makers who are to submit an NOI and are defined as large entities (as 

identified in Part 5) must keep the following records as identified in Section 7.4 of the permit.
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

122 

a. Copy of the NOI submitted to EPA, any correspondence exchanged between the 

Decision-maker and EPA specific to coverage under this permit, and a copy of the 

EPA acknowledgment letter with the assigned permit tracking number;

b. A copy of the PDMP, including any modifications made to the PDMP during the 

term of this permit;

c. Copy of annual reports submitted to EPA; 

d. Documentation of equipment calibration (only if Decision-maker is also the 

Applicator);

e. Information on each treatment area to which pesticides are discharged, including: 

1. Description of each treatment area, including location and size (acres or 

linear feet) of treatment area and identification of any Waters of the 

United States, either by name or by location, to which pesticide(s) are 

discharged;

2. Pesticide use pattern(s) (i.e., mosquito and other flying insects, weed and 

algae, animal pest, or forest canopy);

3. Target pest(s) and explanation of need for pest control; 

4. Action Thresholds; 

5. Method and/or data used to determine that action threshold(s) has been 

met;

6. Description of pest management measure(s) implemented prior to the first 

pesticide application;

7. Company name and contact information for pesticide applicator; 

8. Name of each pesticide product used including the EPA registration 

number; 

9. Quantity of each pesticide product applied to each treatment area; 

10. Pesticide application date(s); and

11. Whether or not visual monitoring was conducted during pesticide 

application and/or post-application and if not, why not and whether any 

unusual or unexpected effects identified to non-target organisms.

7.5 Retention of Records

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. 

EPA recommends that all Decision-makers keep records of acres or linear miles treated 

each calendar year for all applicable use patterns covered under this general permit. This record 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

123 

will help Decision-makers estimate when they will exceed the annual treatment area threshold 

(requiring submission of an NOI), or to complete an annual report if required. 

7.6 Annual Reports

In addition to recordkeeping, EPA is requiring Decision-makers who are required to 

submit an NOI and are large entities as identified in Part 5 to submit annual reports that contain 

basic information on their pesticide discharges to Waters of the United States. An annual report 

form, along with instructions on how to complete it is available in Appendix G. 

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, the Operator 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.

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 provides specific 

information concerning the scope and nature of discharges permitted under the PGP. 

The annual report is a summary of the pest control activities for each applicable use 

pattern and must contain: 

a. Decision-maker’s name and contact information; 

b. NPDES permit tracking number(s);

c. Contact person name, title, e-mail address (if any), and phone number; and 

d. For each treatment area, report the following information:

1. Description of treatment area, including location and size (acres or linear feet) of 

treatment area and identification of any Waters of the United States, either by name 

or by location, to which pesticide(s) are discharged; 

2. Pesticide use pattern(s) (i.e., mosquito and other flying insects, weed and algae, 

animal pest, or forest canopy) and target pest(s);

3. Company name(s) and contact information for pesticide applicator(s), if different 

from the Decision-maker;

4. 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, ground based spray, etc.); 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

124 

5. Whether this pest control activity was addressed in the PDMP prior to pesticide 

application;

6. If applicable, any adverse incidents as a result of these treatment(s), for incidents, as 

described in Part 6.4.1; and

7. If applicable, description of any corrective action(s), including spill responses, 

resulting from pesticide application activities and the rationale for such action(s).

7.7 Annual Reporting for Any Decision-maker with Discharges to Waters of the United 

States containing NMFS Listed Resources of Concern, as defined in Appendix A of the 

permit, and Who is a Small Entity 

Any Decision-maker who is required to submit an NOI for discharges to Waters of the 

United States containing NMFS Listed Resources of Concern, as defined in Appendix A of the 

permit, and is a small entity, as defined in Appendix A of the permit, must submit an annual 

report to EPA. Large entities with discharges to Waters of the United States containing NMFS 

Listed Resources of Concern are required to submit annual reports consistent with Part 7.6 of the 

permit. Decision-makers must submit the annual report electronically through EPA’s notice 

processing system (eNOI), available at www.epa.gov/npdes/pesticides, unless eNOI is otherwise 

unavailable or the Decision-maker meets the waiver requirements for submitting a paper annual 

report. Decision-makers waived from the requirement to use eNOI for annual report submission 

must certify on the paper annual report submitted to EPA the rationale for eligibility to use the 

waiver. The annual report must be submitted to EPA Headquarters (either through eNOI or if 

eNOI is otherwise unavailable or the Decision-maker meets the eNOI waiver requirement, to the 

EPA Headquarters address identified in Part 8.1) no later than February 15 of the following year 

for all pesticide activities covered under this permit occurring during the previous calendar year. 

Annual reporting requirements begin with those discharges occurring during calendar year 2012. 

When Decision-makers terminate permit coverage, as specified in Part 1.2.5, an annual 

report must be submitted for the portion of the year up through the date of termination. The 

annual report is due no later than February 15 of the next year. 

The annual report is a summary of the pest control activities for each applicable use 

pattern that results in a discharge to Waters of the United States containing a NMFS Listed 

Resource of Concern, as defined in Appendix A of the permit. For small entities, discharges to 

waters that do not contain NMFS Listed Resources of Concern do not need to be included in the 

annual report. The annual report must contain: 

a. Decision-maker’s name and contact information; 

b. NPDES permit tracking number(s);

c. Contact person name, title, e-mail address (if any), and phone number; and 

d. For each treatment area, report the following information:

1. Description of treatment area, including location and size (acres or linear feet) of 

treatment area and identification of any Waters of the United States, either by name 

or by location, to which pesticide(s) are discharged; 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

125 

2. Pesticide use pattern(s) (i.e., mosquito and other flying insects, weed and algae, 

animal pest, or forest canopy) and target pest(s);

3. Company name(s) and contact information for pesticide applicator(s), if different 

from the Decision-maker;

4. 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, ground based spray, etc.); 

5. The approximate date of any discharge; 

6. If applicable, any adverse incidents as a result of these treatment(s), for incidents, as 

described in Part 6.4.1; and

7. If applicable, 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 9.0 of the final PGP contains conditions provided by States, Territories, 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 

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 made 

a consistency determination regarding the enforceable policies in each approved state CZM 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

126 

program for the coastal zones including state waters where the PGP authorizes discharges. [15 

CFR 930.31(d)]. 

10. Permit Appendices

A. Definitions and Acronyms

 Appendix A of the PGP provides permit-specific definitions of statutory, regulatory, and 

other terms important for understanding 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 Operator’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 United States. NPDES-authorized states issue permits elsewhere in the United 

States for these types of discharges. Appendix C includes a list of those areas where this EPA 

permit is available which 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 2011. EPA is including discharges from 

pesticide applications in Alaska in this permit such that PGP coverage is available beginning 

October 31, 2011 and lasting until the State of Alaska assumes responsibility for administration 

of these discharges.

D. Notice of Intent Form

Part 1.2.2 identifies certain Decision-makers required to prepare and submit a complete 

and accurate Notice of Intent (NOI) form to be authorized to discharge under this permit. 

Decision-makers 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 a Decisionmaker’s eligibility to discharge under this permit, and enables EPA to better match up Operators 

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. Except is special 

circumstances, EPA requires that Decision-makers submit that information electronically, using 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

127 

EPA’s eNOI system that will be available for use beginning October 31, 2012 at 

www.epa.gov/npdes/pesticides, 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). Paper 

submissions are allowed if eNOI is unavailable (e.g., for discharges to Tier 3 waters that occur 

before October 31, 2011) or, if authorized by EPA, if the use of eNOI will cause the Operator 

undue burden or expense. 

E. Notice of Termination Form

Part 1.2.5 of the PGP requires certain Decision-makers (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 Decisionmaker has taken over responsibility for the pest control activity, (2) the Decision-maker has 

ceased aquatic pesticide application covered under the general permit, (3) there is not and no 

longer will be pesticide discharge, or (4) the Decision-maker 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 requires that 

Decision-makers complete and submit the NOT form electronically using EPA’s eNOI system 

that also will be available for use beginning October 31, 2011 at www.epa.gov/npdes/pesticides, 

except in specified circumstances.

F. Pesticide Discharge Evaluation Worksheet

 

Part 7.3 of the PGP requires Decision-makers who are required to submit an NOI and are small 

entities, as defined in Appendix A of the PGP, to complete and retain a worksheet for at least 3 

years from when an Operator’s coverage under the PGP expires or is terminated. Decisionmakers are required to make this worksheet available to EPA, including an authorized 

representative of EPA, upon requires. Appendix F of the PGP contains a copy of the worksheet 

required to be retained by Decision-makers.

G. Annual Report Template

Part 7.6 of the PGP requires Decision-makers who: (1) are required to submit an NOI and 

are large entities, as identified in Part 5 of the PGP; and/or (2) discharge to Waters of the United 

States containing NMFS Listed Resources of Concern, to submit Annual Reports. The Annual 

Report must be submitted no later than February 15 of the following year for all pesticide 

activities covered under the PGP occurring during the previous calendar year. When Decisionmakers terminate permit coverage, as specified in Part 1.2.5, an Annual Report must be 

submitted for the portion of the year up through the date of termination. Appendix G of the PGP 

contains a copy of the information required to be submitted with an Annual Report. Like the NOI 

and NOT, EPA requires that Decision-makers complete and submit the Annual Report form 

electronically using EPA’s eNOI system that will be available for use at 

www.epa.gov/npdes/pesticides unless eNOI is otherwise unavailable or the Decision-maker has 

obtained a waiver from the requirement to use eNOI for submitting the Annual Report. A waiver 

may be obtained by checking the appropriate box at the top of Annual Report form and providing 

a brief explanation of why the waiver is needed. 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

128 

H. Adverse Incident Template

Part 6.4 of the PGP requires Operators to : (1) provide oral notice to EPA within 24 

hours, and (2) submit a written report within 30 days of becoming aware of an adverse incident 

which may have resulted from a discharge from the Operator’s pesticide application. Adverse 

Incident, as defined in the PGP Appendix A, is an unusual or unexpected incident that an 

Operator has observed upon inspection or of which the Operator otherwise become aware, in 

which: (1) There is evidence that a person or non-target organism has likely been exposed to a 

pesticide residue, and (2) The person or non-target organism suffered a toxic or adverse effect. 

Appendix H of the PGP contains a copy of the information required to be submitted to the 

appropriate EPA Regional office and to the State Lead Agency within 30 days of discovering the 

adverse incident. 

I. Endangered Species Procedures

As discussed in section 1.1.2.4 of the permit, coverage under this permit is available only for 

discharges and discharge-related activities that are not likely to adversely affect species that are 

federally-listed as endangered or threatened under the ESA or federally-designated critical habitat 

under the ESA, except as provided in Criterion B, C and, for 60 day, D. For discharges to a subset of 

these resources, identified in this permit as NMFS Listed Resources of Concern, which are defined in 

Appendix A, the operator must document that discharges meet these conditions by certifying 

eligibility under one of Criteria A-F. (Note that operators not otherwise required to submit an NOI 

do not need to do so merely to certify under Criterion A, which indicates that discharges will not 

occur to waters of the U.S. where NMFS Listed Resources of Concern are present.) Appendix I 

contains a four-step process that must be followed for determining whether an Operator is eligible for 

permit coverage, prior to submittal of the NOI. In order to become eligible for this permit, each 

Operator must determine its compliance with one of six criteria (A – F). If Operators cannot 

determine if they meet one of the eligibility criteria related to NMFS Listed Resources of Concern, 

the operator cannot submit an NOI to gain coverage under the PGP. In these instances, the Operator 

may consider applying to EPA for an individual NPDES permit. 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

129 

Fact Sheet 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.

Table A1. List of all pesticides and degradates 

which exceeded aquatic-life benchmarks in the 

USGS study

Pesticide/Degradate 

Percentage of sites that 

exceed one or more 

aquatic-life benchmarks

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 2011 NPDES Pesticide General Permit Fact Sheet

130 

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.
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

131 

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
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

132 

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 2011 NPDES Pesticide General Permit Fact Sheet

133 

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 2011 NPDES Pesticide General Permit Fact Sheet

134 

APPENDIX C

Summary of Pesticide-Specific Exceedance Data and Risk Mitigation Actions

• Of the 75 pesticides and 8 degradates analyzed, 18 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.

• Five pesticides accounted for the majority of the exceedances: alachlor, azinphosmethyl, chlorpyrifos, diazinon, and malathion. These pesticides, along with atrazine, 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 2011 NPDES Pesticide General Permit Fact Sheet

135 

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 
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

136 

concentrations of atrazine in Missouri and Nebraska exceeded the Agency's LOC. The 

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
U.S. Environmental Protection Agency 2011 NPDES Pesticide General Permit Fact Sheet

137 

Diazinon

History and Mitigation Measures:

• MOA with registrant signed in December 2000; phased out and cancelled all indoor and 

outdoor residential uses.

• 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.