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ANTIDEGRADATION REVIEW

NPDES Permit # ID- Pesticide General Permit

Idaho Department of Environmental Quality

June 7, 2011

Antidegradation Overview

The Idaho Water Quality Standards (WQS) contain an antidegradation policy providing three

levels of protection to water bodies in Idaho. The first level of protection (Tier 1) applies to all

water bodies and assures that existing uses of a water body and water quality necessary to protect

those uses will be maintained. The second level of protection (Tier 2) applies to those water

bodies that are considered high quality and assures that no lowering of water quality will be

allowed unless it is deemed to be necessary to accommodate important economic or social

development. The third level of protection (Tier 3) applies to water bodies that have been

designated outstanding resource waters (ORWs) and requires activities to not cause a lowering of

water quality.

In March 2011, Idaho incorporated additional sections addressing antidegradation

implementation in the Idaho Code. At the same time, Idaho adopted antidegradation

implementation procedures in its WQS. DEQ submitted the antidegradation implementation

procedures to EPA for approval on April 15, 2011. DEQ is employing a waterbody-bywaterbody approach to implementing Idaho’s antidegradation policy. This approach to

antidegradation implementation means that any water body fully supporting its beneficial uses

will be considered high quality. Any waterbody not fully supporting its beneficial uses will be

provided Tier 1 protection for that use, unless specific circumstances warranting Tier 2

protection are met. The most recent federally approved Integrated Report and supporting data

are used to determine support status and the tier of protection.

Types of Activities Covered

The draft final Pesticide General Permit (PGP) authorizes discharges to surface waters subject to

the jurisdiction of the Clean Water Act (CWA) from the application of biological and chemical

pesticides for the following four pesticide use patterns:

1. mosquito and other flying insect pest control;

2. aquatic weed and algae control;

3. aquatic nuisance animal control; and

4. forest canopy pest control.

These use patterns will be collectively referred to as “pesticide applications” in the remainder of

this document. As described in EPA’s “Draft National Pollutant Discharge Elimination System

(NPDES) Pesticides General Permit (PGP) for Discharges from the Application of Pesticides to

or over, including near Waters of the U.S. Fact Sheet” (2010, page 3), EPA has not historically

regulated pesticide applications under the CWA. Rather, pesticide applications have been

regulated under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). In fact, EPA

issued a final rule in 2006 exempting pesticide applications from obtaining an NPDES permit.

As a result of litigation over the final rule, EPA is now requiring NPDES permits for pesticide

applications.
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Pollutants of Concern

EPA estimated this permit would provide coverage for discharge of over 3,500 pesticide

products that are currently registered for use (Fact Sheet, page 30). These pesticide products

contain at least one of the more than 400 pesticide active ingredients and they may also contain a

variety of other inert ingredients.

Receiving Water Body Level of Protection

The draft final PGP provides coverage to pesticide applications that may occur anywhere in

Idaho. Because of the statewide applicability, all of the jurisdictional waters within Idaho may

potentially receive discharge either directly or indirectly from a pesticide application covered

under the PGP. DEQ uses a waterbody-by-waterbody approach when determining the level of

antidegradation protection a waterbody will receive.

All waters in Idaho that receive discharge from pesticide applications authorized in the draft final

PGP will receive Tier 1 antidegradation protection because Idaho’s antidegradation policy

requires the protection and maintenance of all existing uses and water quality necessary to

support existing uses in waters of the U.S. Waterbodies that support their aquatic life or

recreational uses will receive Tier 2 antidegradation protection. Although Idaho does not

currently have any ORWs designated, it is possible that a water body could be designated as an

ORW during the life of this permit. Because of this potential, this antidegradation review will

also assess whether the permit complies with the outstanding resource water requirements of

Idaho’s antidegradation policy.

Protection and Maintenance of Existing Uses (Tier 1)

Waters throughout Idaho are designated for a variety of beneficial uses including: cold water,

warm water, seasonal cold, salmonid spawning, or modified aquatic life; primary or secondary

contract recreation; domestic, agricultural, or industrial water supply; wildlife habitats; and

aesthetics. In order to protect and maintain the existing beneficial uses of a particular water

body, a permitted discharge must comply with Idaho water quality standards (WQS). The WQS

contain narrative and numeric criteria which are set at levels that ensure protection of existing

and designated beneficial uses. The WQS also contain a variety of other provisions that a

discharger must comply with, such as Section 054 which addresses water quality limited waters.

Water quality limited waters are those that do not fully support existing or designated beneficial

uses as determined by Idaho’s current EPA-approved Integrated Report.

Most of the active and inert ingredients in pesticides do not have numeric criteria in Idaho WQS;

therefore, for these pollutants, DEQ relies on the narrative criteria for toxic substances,

hazardous materials, and deleterious materials to ensure protection of designated and existing

beneficial uses. These narrative criteria states that water bodies shall be free of these substances

and materials in concentrations that impair designated beneficial uses.

Before a pesticide that is not considered to be minimum risk can be registered for use, it

undergoes significant review by the U.S. EPA in accordance with the Federal Insecticide,

Fungicide, and Rodenticide Act (FIFRA). The purpose of this review is to ensure the pesticide is

safe for workers and homeowners who might apply the product, safe when used on food items

and safe for the environment. The review evaluates the risk to non target organism and seeks to
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minimize those risks thru label restrictions that may limit the number or applications made on an

annual basis or thru maximum application rates. EPA’s review evaluates the risk of both active

ingredients and the formulated end use product and considers the effects on the target pest(s) and

the environment where the pesticide is applied. It takes into account how the pesticide is

applied, how often it is applied (amount, timing, and frequency) and where it is applied. Before

EPA will approve a pesticide they must determine it will "not generally cause unreasonable

adverse effects" on the environment, pose a risk to workers or home applicators, or pose a human

dietary risk from residues on food or in drinking water when used according to the pesticide

label. In examining the environmental or human health effects, EPA considers whether the

pesticide has the potential to cause adverse effects on non target organisms, wildlife, fish, and

plants, as well as possible contamination of surface water or ground water from leaching, runoff,

and spray drift. If a pesticide posed unacceptable acute or chronic risk, then EPA would not

register the pesticide for use.

If EPA approves a pesticide for use, then EPA will impose restrictions on its use through

labeling requirements that are designed to avoid unreasonable adverse affects on the environment

and human health. The draft final PGP only authorizes the use of pesticides that have been

registered according to FIFRA or that have been classified as minimum risk pesticides exempt

from federal registration requirements.

In addition to the FIFRA requirement that pesticides be applied according to their label

instructions, the draft final PGP contains non-numeric technology-based effluent limitations that

are designed to minimize impacts from pesticide applications. These effluent limitations require

Operators to use the lowest effective amount of pesticide per application and to perform regular

maintenance activities to prevent and reduce unintended releases of pesticides and to ensure the

equipment is operating properly. Furthermore, the draft final PGP contains a water quality-based

effluent limitation that prohibits the discharge from violating WQS. In addition to these

requirements, the draft final PGP prohibits the discharge of pollutants for which a water body is

considered to be impaired. Table 1 lists Idaho water bodies not fully supporting their beneficial

uses due to elevated concentrations of pollutants that have the potential to be contained in, or a

degradate of, pesticides.
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Table 1. Water bodies not fully supporting beneficial uses as a result of concentrations of

pollutants that have the potential to be contained in, or a degradate of, pesticides. This list is

based upon the EPA-approved Integrated Report (DEQ 2008). According to the draft final

permit, pesticides that contain copper may not be used in or near the water bodies in this table.

Pollutant Water body Assessment Unit

Copper Clark Fork River Delta - Mosquito Creek to Pend Oreille

Lake

ID17010213PN001_08

Clark Fork River - Cabinet Gorge Dam to Mosquito

Creek

ID17010213PN003_08

Clark Fork River - Idaho/Montana border to Cabinet

Gorge Dam

ID17010213PN005_08

Prichard Creek – middle, Butte Gulch to Eagle Creek ID17010301PN004_03

Prichard Creek - between Butte Gulch and Eagle Creek ID17010301PN004_03

Big Deer Creek – South Fork Big Deer Creek to mouth ID17060203SL005_03

South Fork Big Deer Creek - Bucktail Creek to mouth ID17060203SL007_02

Panther Creek - Blackbird Creek to Napias Creek ID17060203SL011_02

Panther Creek - Napias Creek to Big Deer Creek ID17060203SL010_05

In consideration of the rigorous registration process for pesticide products and active ingredients

and the requirements of the draft final PGP, the use of pesticides in accordance with the label

instructions is not expected to result in concentrations that will impair designated or existing

beneficial uses of Idaho’s water bodies (see Fact Sheet, pages 71-85 for further discussion).

Additionally, the effluent limitations and associated requirements contained in the draft final

PGP permit and this certification are set at levels that ensure compliance with the narrative and

applicable numeric criteria as well as Section 054 of the Idaho WQS. Therefore, DEQ has

determined the permit will protect and maintain existing beneficial uses in Idaho’s water bodies.

Protection of High Quality Waters (Tier 2)

As indicated previously, waterbodies that support their aquatic life or recreational uses will be

provided Tier 2 protection. As such, the quality of these waters must be maintained and

protected, unless it is deemed necessary and important to allow a lowering of water quality.

The pesticide applications identified in the draft final PGP have historically occurred in Idaho for

decades. For example, mosquito abatement districts were formed in Idaho as early as the 1960’s

and the Idaho mosquito abatement district statute (Title 39 Chapter 28) was enacted in 1959.

Although not used often anymore, the U.S. Forest Service conducted forest canopy pest control

in Idaho in the early 1970s as well as in the 1980s. The Idaho Department of Lands has

employed aerial application of pesticides sporadically since at least 1965. In consideration of the

historical application of pesticides directly to or near water bodies in Idaho, DEQ concludes that

many of the pesticide application activities are existing and do not constitute a new or increased

discharge to high quality waters. However, this permit may also result in new dischargers, such

as the examples described below.

1. A new pesticide may be used in or near a water body that has historically

received discharge either directly or indirectly from the application of a different

pesticide.
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2. A pesticide application to or near a water body that has never had a direct or

indirect discharge of pesticides may occur during the term of this permit (e.g. a

lake may be treated for milfoil for the first time in its history).

While a pesticide application might constitute a new discharge, DEQ expects that generally, the

application of a pesticide will not result in a lowering of water quality. Idaho WQS define

lowering water quality as a “measurable and adverse” anthropogenic change1. Pesticides are not

applied continuously rather their application varies in magnitude, duration, and frequency

depending upon the target pest(s) and product used. Pesticide applicators are required by FIFRA

to follow the pesticide use directions and restrictions, which limit the application rate and in

some cases, the frequency of application (e.g. total number of applications per season). In

addition to their non-continuous application, pesticides have varying half-lives, ranging from

hours to months and this is considered during the registration process. By complying with the

use directions and pesticide labeling restrictions, the risks to human health and the environment

from the pesticide application are minimized. Furthermore, the draft final PGP requires that

pesticides be applied in the smallest effective amount possible and that the optimum application

frequency be used, which is a requirement above and beyond simply complying with the FIFRA

use directions and label restriction.

Given these factors, DEQ expects that many pesticide applications authorized by the draft final

PGP will not result in measurable change in water quality. In recent years, the Idaho State

Department of Agriculture (ISDA) provided funding to various Eurasian watermilfoil control

projects implemented in various lakes and reservoirs in Idaho. Many of these projects conducted

water quality monitoring for the pesticide active ingredient that was used. The Inland Empire

Cooperative Weed Management Area has prepared at least four reports summarizing their

Eurasian watermilfoil control efforts for 2006, 2007, 2008, and 2009

(http://www.iecwma.org/milfoil/reports.htm). These reports contain water quality monitoring

data for the active ingredients in pesticide products that were applied in Hayden Lake, Cave

Lake, and Medicine Lake. This data indicates that the active ingredients (e.g. 2,4-D and

triclopyr) in pesticides were not measurable in treatment areas anywhere from 1 to 41 days

following application. Similarly results have been found for fish eradication projects using

rotenone. Finlayson, Siepmann, and Trumbo (2001)2found that for the various rotenone

application projects in California, rotenone generally degraded to nondetectable levels in one to

three weeks. In a more recent study (McMillin and Finlayson 20083), concentrations of rotenone

and rotenolone (a metabolite) in water were below reporting limits 32 and 54 days, respectively,

after treatment in Lake Davis.

1 The definition of lower water quality in DEQ’s pending antidegradation policy and implementation rules (Docket

Number 58-0102-1001) no longer contain the concept of measurability. This concept is only applicable for the

current (2010) Idaho WQS.

2

Finlayson, B.J., S. Siepmann, and J. Trumbo. 2001. Chemical Residues in Surface and Ground Waters Following

Rotenone Application to California Lakes and Streams. Pages 37-54 in R.L. Cailteux, L. DeMong, B.J. Finlayson,

W. Horton, W. McClay, R.A. Schnick, and C. Thompson, editors. Rotenone in fisheries science: are the rewards

worth the risks? American Fisheries Society, Trends in Fisheries Science and Management 1, Bethesda, Maryland.

3 McMillin, S. and B.J. Finlayson. 2008. Chemical residues in water and sediment following rotenone application to

Lake Davis, California 2007. California Department of Fish and Game, Pesticide Investigations Unit, OSPR

Administrative Report 08-01. Rancho Cordova, California.
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While DEQ concludes that most pesticide applications, when done in accordance with use

directions and label restrictions, will not result in a lowering of water quality, DEQ

acknowledges that there may be circumstances where a pesticide application authorized under

the draft final PGP has the potential to result in a lowering of water quality. We expect that

projects with this potential will be only those that surpass the annual treatment area thresholds

stipulated in the draft permit (Section 1.2.2). Where an activity may result in lowering of water

quality, DEQ must assure that the activity is necessary to accommodate important social or

economic development. DEQ considers activities covered under the draft final PGP to be

necessary to accommodate important social or economic development for a variety of reasons.

First, DEQ believes that, with respect to the larger or more frequent applications that may cause

a lowering of water quality, the draft final PGP only allows necessary pesticide application. The

draft final PGP requires certain Operators (i.e. federal or state governmental entities, irrigation

districts, pest control districts, and entities exceeding the annual treatment area thresholds) to

consider a variety of pest control options including such options as no action, mechanical or

physical control methods, or cultural methods. In selecting the pest control method, the Operator

should consider the impact to water quality and non-target organisms, pest resistance, feasibility,

and cost effectiveness. The most efficient and effective means of pest management that

minimizes discharges of pesticides to waters of the U.S. must be chosen. The evaluation of pest

control methods must be documented in the pesticide discharge management plan along with a

description of how the selected control measure will be implemented to comply with the PGP.

DEQ believes these draft final PGP requirements adequately satisfy the antidegradation

requirement of ensuring that any potential degradation of high quality water is necessary.

Second, DEQ believes that pesticide application results in social and/or economic benefits to the

community affected by the application. Controlling target pests is beneficial for economic and

social reasons. For example, mosquito control reduces the potential risk of community members

becoming infected with West Nile Virus. Treating lakes impacted with aquatic weeds such as

Eurasian watermilfoil enhances recreational opportunities (such as boating or swimming) and

can be beneficial to aquatic life uses (removing milfoil can prevent dissolved oxygen sags at the

end of the growing season). Controlling weeds in agricultural water conveyances improves

water delivery and helps to minimize loss of water, thereby benefiting the water users.

DEQ also believes that public involvement is provided for in connection with the draft final

PGP. The draft final PGP and DEQ's certification, including this antidegradation review, are

subject to public notice and comment. In addition, for Operators required to submit a Notice of

Intent (NOI) the public has the opportunity to access and review an Operator’s NOI and may

contact the regulatory agencies if they have concern about a pesticide application program. In

response to these comments, or based upon its own determination, EPA may determine that

additional technology-based or water quality-based effluent limitations are necessary for a

particular project (Draft Permit, Section 1.2.3).

Before DEQ can authorize a lowering of water quality, DEQ must assure that the highest

statutory and regulatory requirements of point sources and cost-effective and reasonable best

management practices for non point sources shall be achieved in the watershed. DEQ believes

that this evaluation can be done on a statewide basis for both point and nonpoint sources of
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pesticides. Aside from the draft final PGP, there are no other point source discharge permits that

have effluent limitations for pesticides. Thus, DEQ concludes that the highest statutory and

regulatory requirements of point sources are already in place. If a point source will discharge

pesticides, then the discharge permit for that point source will require the highest regulatory and

statutory control. For non point sources of pesticides, DEQ believes that compliance with the

label use directions and restrictions constitutes the most cost-effective and reasonable best

management practice for pesticide application. The Idaho State Department of Agriculture

(ISDA) is the agency responsible for ensuring compliance with federal and state laws and rules

governing the use of pesticides. To do this, ISDA actively implements various programs such as

applicator licensing, pesticide registration, inspections, water quality monitoring, education, and

enforcement. The public outreach and education program is aimed at ensuring users understand

label instructions and use BMPs that effectively minimize drift and runoff. Furthermore, the

federal pesticide re-registration process constitutes another layer of best management practices

that will aid in controlling nonpoint sources of pesticides to waters of the U.S. EPA continues to

review the registrations of pesticide products and active ingredients. If evidence suggests

unacceptable environmental or human health risks based on new information (e.g. new toxicity

studies or newly evaluated exposure pathways), EPA will not re-register active ingredients or

pesticide products or EPA will change the label restrictions to minimize such risks.

In summary, DEQ concludes the permit requirements coupled with the requirements of this

certification will ensure that high quality waters will likely be maintained and protected. Where

projects may result in degradation of high quality waters, DEQ concludes: 1) such projects are

necessary for important social or economic development and 2) the highest statutory and

regulatory controls on point source discharges and cost-effective and reasonable best

management practices of nonpoint sources of pesticides are being achieved in the State.

Protection of Outstanding Resource Waters (Tier 3)

Idaho’s antidegradation policy requires that the quality of outstanding resource waters be

maintained and protected form the impacts of point source discharges. As mentioned previously,

no water bodies in Idaho have been designated as outstanding resource waters to date; however,

it is possible that waters may become designated during the term of the PGP. Because of this

possibility, DEQ evaluated whether the draft final PGP complies with the ORW antidegradation

provision.

The draft final PGP only authorizes discharges to ORWs when specific conditions are met.

Those conditions are: 1) the application must be made to restore or maintain water quality or to

protect public health or the environment and 2) water quality must not be degraded on a longterm basis. Pesticide applications to, or near ORWs that do not meet these conditions are not

eligible for coverage under the draft final PGP and will be required to obtain authorization under

an individual permit. This requirement complies with Idaho’s antidegradation provisions

concerning ORWs.