Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

CHAPTER 2 ALTERNATIVES, INCLUDING THE PROPOSED

ACTION 

 

2.1 Introduction 

Chapter 2 describes and compares the Proposed Action and three other alternatives (including 

No Action) for preventing and managing invasive plants in Region Six: Chapter 2.2 describes 

the alternatives considered; Chapter 2.3 discusses current management direction and the No 

Action alternative; Chapter 2.4 describes management direction common to the action 

alternatives; Chapter 2.5 displays management direction unique to each of the action 

alternatives; Chapter 2.6 compares the alternatives, including a summary (Table 2-6) of the 

environmental effects of implementing the alternatives; and Chapter 2.7 addresses several 

alternatives that were considered, but not developed for detailed study. 

2.2 Alternatives Considered in Detail 

Four alternatives are considered in detail: No Action, the Proposed Action, Alternative B and 

Alternative D, (hereafter referred to as the “alternatives”).16 All the alternatives follow the 

Integrated Weed Management (IWM)17 approach (Chapter 2.3). The three “action 

alternatives” (Proposed Action, B and D) were developed to meet the underlying need for 

action and address the issues identified in Chapter 1. The action alternatives would amend 

Forest Plans within the Region by approving four kinds of invasive plant management 

direction, including: a Desired Future Condition statement (DFC), goals, objectives, and 

standards. In addition, an inventory and monitoring plan framework is also included in each 

of the action alternatives (Chapter 2.4). 

The No Action alternative represents no change from the current direction. 

The Proposed Action would amend all Forest Plans to provide new management direction 

specific to prevention and management of invasive plants, and replace current Forest Plan 

direction, associated with invasive plant management. 

The Proposed Action emphasizes invasive plant prevention, early detection, early treatment, 

and restoration of affected habitat, monitoring, and long-term site management. A key feature 

16 In the early stages of alternative development the No Action alternative was labeled as Alt. A, and the 

Proposed Action was Alt. C. The switch was made mid-process to help reduce confusion for future readers 

regarding which is No Action, (current direction) and which is the Forest Service’s Proposed Action. 

17 Integrated Weed Management (IWM) - An interdisciplinary weed management approach for selecting 

methods for preventing, containing, and controlling noxious weeds in coordination with other resource 

management activities to achieve optimum management goals and objectives (FSM 2080.5). 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

of the Proposed Action is the requirement to develop long-term site goals for all invasive 

plant sites prior to treatment. Long-term site goals provide the mechanism to link treatment to 

prevention, revegetation/restoration and monitoring in an integrated and adaptive process for 

management of invasive plants. 

Alternative B responds to issues and suggestions received during scoping, including those 

received from a coalition of citizen’s groups interested in prevention and management of 

invasive plants on National Forest System lands. The coalition developed an alternative for 

consideration in this EIS (the “Restore Native Ecosystems Alternative”). The Regional 

Forester considered this alternative in total and decided to dismiss it from detailed study (see 

discussion in Chapter 2.9 for rationale). However, many elements of the coalition’s 

alternative are incorporated into the action alternatives, particularly Alternative B. 

Alternative B builds on the Proposed Action by increasing emphasis on reducing conditions 

that contribute to invasive plant introduction, establishment and spread. The standards 

included in Alternative B tend to be stricter and less flexible than in the other alternatives, and 

tend to apply to more acreage in the Region. Under Alternative B, invasive plant treatment 

tools associated in the scientific literature with human and/or ecological harm would be 

avoided where possible and herbicides would be a “tool of last resort 18.” Treatment projects 

would be prioritized to favor those projects with the highest likelihood of restoring native 

plant communities. 

Some standards in Alternative B include additional or alternate language when compared to 

the other alternatives. This additional or alternate language does not necessarily or in all 

cases change the intent of the standard. In some cases, the language was kept to maintain the 

flavor of the “Restore Native Ecosystems Alternative.” The differences in potential effects of 

the standards as worded in each alternative are disclosed in Chapter 4 and the numerous 

summary tables throughout the document. In many cases, these differences cannot be 

quantified at a Regional scale. 

Alternative D is similar to the Proposed Action with greater emphasis on maintaining 

planning and operational flexibility at the Forest/Ranger District level. Greater flexibility is 

intended to reduce the treatment costs and impacts on land uses and user groups. The 

language of some standards has been adjusted to reduce restrictions and allow local land 

managers a larger degree of discretion in how and when invasive plant prevention practices 

are implemented. 

 

18 “Tool of last resort” means that tool will be used only if all other methods for managing invasive plants are 

ineffective or too expensive. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Alternative D includes the use of two, less expensive and potentially more risky herbicides 

(2,4-D and Dicamba). In addition, as Alternative D places greater emphasis on reducing 

treatment costs; the use of broadcast and aerial application of herbicides is expected to 

increase under Alternative D. 

Table 2-1 displays key features of the alternatives. 

Table 2-1 Key Features of the Alternatives 

Key 

Feature No Action Proposed Action Alternative B Alternative D 

Overall 

Approach 

Adaptive 

management, 

focusing on 

prevention, early 

detection, early 

treatment of 

invasive plants. 

Adaptive 

management, with 

increased emphasis on 

prevention, updated 

treatment tools, 

restoration and longterm site management 

goals. 

Similar to the 

Proposed Action, 

increases the 

emphasis on 

reducing the 

conditions that 

contribute to 

invasive plants. 

Similar to the 

Proposed Action, 

with a less 

“prescriptive” 

approach to 

prevention and 

more flexibility in 

the use of 

herbicides. 

Inventory 

Emphasizes early 

detection. 

Emphasizes early 

detection and requires 

inventories be 

consistent with 

nationally accepted 

data structures. 

Same as the 

Proposed Action. 

Same as the 

Proposed Action. 

Prevention 

Direction for 

prevention is 

provided primarily 

by the 1988 

EIS/ROD and the 

1989 Mediated 

Agreement 

Requires the use of a 

suite of invasive plant 

prevention standards. 

Similar to the 

Proposed Action 

with additional, 

more prescriptive 

prevention 

standards. 

Similar to the 

Proposed Action, 

with fewer and 

less prescriptive 

prevention 

standards. 

Treatment 

Treatment methods, 

including five 

herbicides. 2,4-D is 

a tool of “last 

resort”. 

Treatment methods 

include ten herbicides, 

but not 2,4-D. 

Emphasis is on nonchemical methods. 

Includes four 

herbicides and they 

are considered 

“tools of last 

resort”. 

Treatment 

methods include 

twelve herbicides, 

including 2,4-D. 

Restoration 

Favors the use of 

native plants and 

allows the use of 

non-native plants in 

certain situations. 

Favors the use of 

native plants for 

restoration, allows use 

of non-invasive nonnative plants in certain 

situations. 

Requires use of 

native species for 

restoration, except 

as an intermediate 

step toward native 

restoration. 

Requires the use of 

plant species that 

do not invade or 

persist. 

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2.3 Current Direction and the No Action Alternative 

Forest Service Manual 2080.2 directs the Forest Service to use an integrated weed 

management (IWM) approach to control and contain the spread of noxious weeds on National 

Forest System lands and from National Forest System lands to adjacent lands. 

Forest Service Manual 2080.5 defines IWM as: “An interdisciplinary pest management 

approach for selecting methods for preventing, containing, and controlling noxious weeds in 

coordination with other resource management activities to achieve optimum management 

goals and objectives. Methods include: education, preventive measures, herbicides, cultural, 

physical or mechanical methods, biological control agents, and general land management 

practices, such as manipulation of livestock or wildlife grazing strategies, that accomplish 

vegetation management objectives.” 

Specific objectives to be achieved through integrated weed management include: 

• Prevention of the introduction and establishment of noxious weed infestations. 

• Containment and suppression of existing noxious weed infestations. 

• Formal and informal cooperation with State agencies, local landowners, weed control 

districts and boards, Native American tribes and other Federal agencies in the 

management and control of noxious weeds. 

• Education and awareness of employees, users of National Forest System lands, 

adjacent landowners, and State agencies about noxious weed threats to native plant 

communities and ecosystems. 

Additional direction for the management of invasive plants on the National Forests in Region 

Six has been established by the 1988 EIS and ROD for Managing Competing and Unwanted 

Vegetation and the 1989 Mediated Agreement, individual Forest Plans for the nineteen 

National Forests in Region 6, the Forest Service Manual, and letters of Regional policy. 

The following summarizes features of the No Action Alternative. For a complete listing of 

the existing Forest Plan Standards, and mitigation measures associated with the No Action 

alternative please refer to Appendix F. For further clarification, the 1988 ROD and 1989 

Mediated Agreement are included in Appendix K. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

2.3.1 Prevention 

The No Action alternative, in compliance with the 1989 Mediated Agreement, requires 

consideration of prevention. Prevention was defined as actions conducted “to detect and 

ameliorate the conditions that cause or favor the presence of competing or unwanted 

vegetation in the forests.” Specific guidance on how to actually prevent invasive plant 

introduction, establishment, and spread has been provided to National Forests in the USDA 

Forest Service Guide to Noxious Weed Prevention Practices (Appendix E). This national 

guidance is optional for use on National Forests. Examples of prevention practices 

recommended in the National Guide include cleaning off-highway vehicles, use of weed-free 

feed for horses and pack animals, use of weed-free straw, and closing sensitive habitat within 

National Forests to OHV use. The Mt. Baker-Snoqualmie National Forest is the only Forest 

in Region Six that has amended its Forest Plan to require use of some of these prevention 

practices. Other Forests, including the Colville, Okanogan/Wenatchee, and the Rogue River 

have developed their own guidelines for preventing and managing invasive plants, but they 

have not been incorporated in Forest Plan direction. 

All the Forest Plans in the Region were written before the National Prevention Guide was 

published. Some Forest Plans did consider invasive species when the plans were developed 

and incorporated some prevention requirements. For example: 

• Okanogan National Forest Plan prohibits use of unprocessed hay or feed in Wilderness 

Areas (USDA FS, 1989). 

• Winema National Forest Plan encourages use of certified pelletized feed for pack 

animals used in Wilderness Areas (USDA FS, 1990). 

• Mt. Baker-Snoqualmie National Forest Plan requires use of weed-free straw and 

mulch for revegetation actions (USDA FS, 1999). 

• Several National Forest Plans restrict OHV use in undeveloped areas, or where forage 

and other resources may be threatened by permitted activities: Mt. Baker Snoqualmie, 

Ochoco, Rogue River, Siuslaw, Umatilla, and Umpqua National Forests. 

The following sections provide a brief description of existing direction and current situation 

by land use activity. A listing of current Forest Plan standards and guidelines is included in 

Appendix F. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Timber and Other Vegetation Management 

Timber management contracts throughout Region Six currently include mandatory provisions 

that require off-road equipment be free of soil, seeds, vegetative matter, or other debris that 

could contain or hold seeds. Timber purchasers certify in writing that off-road equipment is 

free of invasive species prior to each start-up of operations and for subsequent moves of 

equipment within timber harvest areas.19 Equipment operating in areas infested with invasive 

plants is required to be cleaned prior to being moved from the infested area, unless the 

equipment is moving to an infested area containing the same invasive species. In some cases, 

vehicles must be cleaned on National Forest to avoid spreading invasive plants. These 

requirements apply only to activities associated with timber sales and do not apply to use of 

ground-based heavy equipment for mechanical site preparation, pre-commercial thinning, or 

other vegetation management projects. 

Road Management 

Best management practices related to roads management and invasive plants are outlined in 

the USDA Forest Service Guide to Noxious Weed Prevention Practices (Appendix E) and the 

USDA Forest Service Backcountry Road Maintenance and Weed Management publication 

(7100 Engineering July 2003 0371-2811-MTDC). 

The Mt. Baker-Snoqualmie National Forest has amended their Forest Plan to require the use 

of invasive plant prevention practices related to road management. Other Forests are 

implementing invasive plant prevention and treatment/restoration practices related to roads 

management to varying degrees. 

Cleaning equipment to avoid transporting invasive plants to other areas, is generally not 

required on road maintenance equipment, and clear direction for such washing does not 

currently exist. While some road contracts have clauses in place that can be used to control 

timing of operations, consistent coordination to schedule activities to prevent the spread of 

invasive plants is not occurring. 

Public works contracts currently have specifications that straw and mulch must be free from 

weeds, but no certification requirements are included in these specifications. Most straw and 

mulch used for Forest projects generally does meet some level of weed free criteria. Road 

related erosion control projects currently specify the use of seed mixes that include native 

type grasses. 

 

19 “Off-road equipment” includes all logging and construction machinery, except for log trucks, chip vans, 

service vehicles, water trucks, pickup trucks, cars, and similar vehicles. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Livestock Grazing 

Though not directly required, numerous annual operating instructions and grazing allotment 

management plans across the Region already include some consideration of invasive plant 

prevention measures and cooperative management goals. Direction requiring integration of 

invasive plant prevention measures and cooperative management goals into these documents 

has not been addressed on a Region-wide scale. Currently, invasive plant prevention 

measures, such as those provided in the USDA Forest Service Guide to Noxious Weed 

Prevention Practices (Appendix E), are not being consistently applied to livestock grazing 

within the Region. 

Fire and Fuels Management 

Fire and fuels management is designed to meet the goals of the National Fire Plan, 10-Year 

Comprehensive Strategy, and Healthy Forests Initiative. Post-fire restoration and hazardous 

fuel treatment projects are currently required to consider invasive plants and develop 

mitigation measures and project design criteria to prevent establishment of invasive species 

where an identifiable risk exists, and to reduce the risk of further spread of any such species 

already present in the project area. 

Currently, cleaning equipment to prevent the spread of invasive plants is not always required 

by National Forests for fire rehabilitation and restoration or fuels projects. Equipment 

cleaning on large fires where a Type 1 or 2 incident management team is in place is becoming 

standard practice, although cleaning usually occurs only during demobilization of equipment 

and not during mobilization and suppression operations. Equipment cleaning on smaller 

incidents is not a widespread practice. As better equipment is developed and invasive plant 

awareness increases, the use of equipment washing is expected to increase as a control 

measure during the suppression of large fires, and likely will become a standard operating 

procedure. No significant change in equipment washing practices on smaller, less complex 

fires, is expected under current direction and trends. 

Post-fire rehabilitation projects generally use some form of weed-free straw and mulch and 

native seed. Such projects are not bound by any Region-wide specific criteria or certification 

standards of weed-free or local native seed specifications. 

Recreation Management 

Invasive plant prevention measures are generally not a priority issue in current recreation 

management. Consistent direction for inclusion of invasive plant prevention measures in 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

recreation management and planning does not currently exist. Some Forests in the Region 

have adopted recreation related components of the USDA Forest Service Guide to Noxious 

Weed Prevention Practices. Several Forests within the Region requires pack and saddle stock 

use pelletized or certified weed-free feed when in Wilderness Areas. Forest Service offhighway vehicle (OHV) policy and implementation strategies for OHV management are 

currently being developed; this issue is among the agencies top priorities. 

Minerals and Mining 

For all types of mineral activities, submissions of plans of operation typically trigger an 

Environmental Assessment or other NEPA analysis. Depending upon the site-specific 

proposal, site conditions and risk, the Forest Service considers invasive plants when 

developing the terms and conditions or mitigation measures, associated with the approval of 

plans of operation, including the need for a reclamation plan and reclamation bond. 

2.3.2 Treatment and Restoration 

The process for determining treatment priority under the No Action Alternative is established, 

in general terms, through the 1988 ROD and 1989 Mediated Agreement. A process for 

determining priorities based on a Forest Service guide for how to prioritize sites and select 

treatment methods is shown in Chapter 3.3. 

The 1989 Mediated Agreement addresses processes which National Forests should use for 

selecting treatment strategies: “In planning for, and before proceeding with site-specific 

projects to treat competing or unwanted vegetation, another requirement is to analyze the 

proposed strategy.” The Mediated Agreement lists topics of consideration, including: the 

potential human health risks; potential environment effects; physical and biological 

characteristics of the site; etc. 

Table 2-3 lists methods to be used alone or in combination to treat invasive plants under the 

No Action Alternative. These treatment options apply to all the National Forests in the 

Region that have completed site-specific environmental analysis, except the Malheur National 

Forest, where only manual treatments are currently allowed as the result of a 2002 U.S. 

District Court decision20. 

These treatment options are available for consideration within all National Forest System 

lands, with the exception of Wilderness, which was not addressed in the 1988 EIS and ROD 

or the 1989 Mediated Agreement. 

 

20 Blue Mountain Biodiversity Project v. U.S. Forest Service – CV 01-703-HA, 2002. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Under the No Action Alternative, the use of biological control would continue on National 

Forest System lands in the Region with the exception of the Malheur National Forest. The 

1988 EIS authorizes the use of biological control in cooperation with USDA Agricultural 

Research Service or individual state programs. Allowable biological control agents include 

all agents approved by USDA Animal and Plant Health Inspection Service (APHIS). Any 

agents approved by APHIS, but not yet introduced into a given state, would require state 

approval before National Forests can use them. 

Region Six has a regional policy encouraging the use of native plants in revegetation. This 

policy was articulated in an April 1994 letter signed by Regional Forester, John E. Lowe: 

“Use local native plant species to meet management objectives. Follow appropriate 

seed and plant movement guidelines. Non-native plant species may be used when (1) 

needed to protect basic resources values (site productivity), (2) as an interim, nonpersistent measure designed to aid in the re-establishment of native plants, or (3) local 

native plant species are not available.” 

Policies for each National Forest vary on the emphasis placed on restoration of native plant 

communities after an infestation of invasive plants has been treated. For example, the 

Columbia River Gorge National Scenic Area requires re-establishment of native grasses in 

degraded areas that have been invaded by non-native plants. The Siuslaw National Forest 

Plan discourages the use of non-native plants for revegetation and, if seeding is needed, will 

use native species most of the time (Segotta, 2003 personal communication). 

The No Action alternative includes a list of required mitigation measures to reduce, avoid, 

minimize, rectify, or compensate for impacts on the environment and human health, which 

might result from treatment activities developed in the 1988 EIS. 

2.3.3 Inventory and Monitoring 

All National Forests have done some level of inventory and mapping of invasive plant sites, 

and have entered this information into Geographic Information Systems (GIS) and databases. 

Most Forests are beginning to use the Natural Resource Information System’s Terrestrial 

Module (NRIS /TERRA) data collection protocols for invasive plant inventory. 

In monitoring Forest-wide vegetation management programs, Forests are currently required to 

address the following points: 

• Describe the projected need for vegetative management by method, over the next three 

to five years. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

• Describe how the projected need for treatment can be reduced, and identify the steps 

that can be taken to reduce reliance on herbicides and prescribed burning. 

• Determine criteria that can be used to review progress on an annual basis toward 

reducing reliance on herbicides and prescribed burning. 

• Evaluate program success in achieving resource management goals, such as 

controlling invasive plants. 

In monitoring individual vegetation management projects, Forests must address the following 

considerations: 

• Site-specific post-treatment information should be used to aid future project planning. 

The information to be evaluated includes treatment effectiveness and cost. 

• Any impacts to human health from using herbicides and other methods of treatment. 

A five-step process for project development was adopted in the 1988 EIS and ROD (Figure 2-

1). It is an adaptive management approach that focuses attention on site-specific ecological 

features of the proposed treatment site and the Forest Plan goals for that site. It requires 

careful examination of what action is needed, prudent project design and implementation, and 

follow-up monitoring, learning and adjustment. 

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Figure 2-1 Five Step Approach for Managing Competing and Unwanted Vegetation 

2.4 Management Direction Common to All Action Alternatives 

The proposed management direction included in the action alternatives follows the IWM 

approach described in Chapter 2.3. The action alternatives build on the 1988 ROD and 1989 

Mediated Agreement emphasis on protecting ecosystem and human health. None of the 

alternatives release the Forest Service from the requirement to protect the health of people and 

the environment when implementing invasive plant treatment projects. The management 

direction common to all action alternatives is intended to increase the likelihood that invasive 

plant projects are safe and effective. All alternatives would still require site-specific analysis 

that addresses: the potential human health risks, potential environmental effects; and 

knowledge of the physical and biological characteristics of the site. All of the alternatives 

(except Alternative D) maintain the objective to reduce herbicide use over time. 

Four kinds of new management direction would be added to Forest Plans in Region Six under 

the action alternatives: A Desired Future Condition statement, goals and objectives, 

prevention and treatment/restoration standards, along with an inventory and monitoring plan 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

framework. This will meet the need for Forest Plan direction that will prevent or reduce the 

spread of invasive plants (see Chapter 1.2). 

Desired Future Condition (DFC) statement describe how National Forests should look and 

function in the future in relation to invasive plants, as opposed to dwelling on past problems. 

The description is optimistic, but attainable. The DFC represents a positive depiction of what 

would result from successful Forest Plan implementation. The DFC is common to all action 

alternatives. 

Goals are broad, general terms describing how to achieve the DFC, with no specific time 

frames by which the goals are to be achieved. Goal statements form the basis from which 

objectives are developed. The goals are common to all action alternatives. 

Objectives are specific statements of actions or results designed to help achieve goals. 

Objectives break down goals into components, and form the basis for project-level actions or 

proposals to help achieve Forest goals. The rate of achieving objectives is dependent on 

budgets and other variables. The time frame for achieving objectives is generally considered 

to be the planning period, or the next 10 to 15 years. The objectives (with the exception of 

Objective 3.2) are common to all action alternatives. Not all objectives are associated with 

specific proposed standards. In these cases, objectives would be met through adherence to 

existing standards, policies and laws. 

Standards are binding limitations placed on management actions, designed to contribute to the 

attainment of objectives. Standards must be within the authority and ability of the Forest 

Service to enforce. A project or action that varies from a relevant standard may not be 

authorized unless the Forest Plan is amended to modify, remove, or waive application of the 

standard. Each action alternative contains a unique suite of standards developed so that 

projects will contribute to meeting goals, objectives and desired conditions. 

2.4.1 Desired Future Conditions, Goals and Objectives 

The following Desired Future Condition (DFC), goals and objectives would be added to the 

already existing sets of DFCs, goals and objectives in Forest Plans across the Region. Unless 

specifically noted, they apply to all the action alternatives: 

Desired Future Condition - In National Forest lands across Region Six, healthy native plant 

communities remain diverse and resilient, and damaged ecosystems are being restored. High 

quality habitat is provided for native organisms throughout the region. Invasive plants do not 

jeopardize the ability of the National Forests to provide goods and services communities 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

expect. The need for invasive plant treatment is reduced due to the effectiveness and habitual 

nature of preventative actions, and the success of restoration efforts. 

Goal 1 - Protect ecosystems from the impacts of invasive plants through an integrated 

approach that emphasizes prevention, early detection, and early treatment. All employees and 

users of the National Forest recognize that they play an important role in preventing and 

detecting invasive plants. 

Objective 1.1 - Implement appropriate invasive plant prevention practices to help 

reduce the introduction, establishment and spread of invasive plants associated with 

management actions and land use activities. 

Objective 1.2 - Educate the workforce and the public to help identify, report, and 

prevent invasive plants. 

Objective 1.3 - Detect new infestations of invasive plants promptly by creating and 

maintaining complete, up-to-date inventories of infested areas, and proactively 

identifying and inspecting susceptible areas not infested with invasive plants. 

Objective 1.4 - Use an integrated approach to treating areas infested with invasive 

plants. Utilize a combination of available tools including manual, cultural, 

mechanical, herbicides, biological control. 

Objective 1.5 - Control new invasive plant infestations promptly, suppress or contain 

expansion of infestations where control is not practical, conduct follow up inspection 

of treated sites to prevent reestablishment. 

Goal 2 - Minimize the creation of conditions that favor invasive plant introduction, 

establishment and spread during land management actions and land use activities. 

Continually review and adjust land management practices to help reduce the creation of 

conditions that favor invasive plant communities. 

Objective 2.1 - Reduce soil disturbance while achieving project objectives through 

timber harvest, fuel treatments, and other activities that potentially produce large 

amounts of bare ground. 

Objective 2.2 – Retain native vegetation consistent with site capability and integrated 

resource management objectives to suppress invasive plants and prevent their 

establishment and growth. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Objective 2.3 - Reduce the introduction, establishment and spread of invasive plants 

during fire suppression and fire rehabilitation activities by minimizing the conditions 

that promote invasive plant germination and establishment. 

Objective 2.4 - Incorporate invasive plant prevention as an important consideration in 

all recreational land use and access decisions. Use Forest-level Access and Travel 

Management planning to manage both on-highway and off-highway travel and travel 

routes to reduce the introduction, establishment and spread of invasive plants. 

Objective 2.5 - Place greater emphasis on managing previously “unmanaged 

recreation” (OHVs, dispersed recreation, etc.) to help reduce creation of soil 

conditions that favor invasive plants, and reduce transport of invasive plant seeds and 

propagules. 

Goal 3 - Protect the health of people who work, visit, or live in or near National Forests, 

while effectively treating invasive plants. Identify, avoid, or mitigate potential human health 

effects from invasive plants and treatments. 

Objective 3.1 - Avoid or minimize public exposure to herbicides, fertilizer, and 

smoke. 

Objective 3.2 – Reduce reliance on herbicide use over time in Region Six (Proposed 

Action and Alternative B only). 

Goal 4 – Implement invasive plant treatment strategies that protect sensitive ecosystem

components, and maintain biological diversity and function within ecosystems. Reduce loss 

or degradation of native habitat from invasive plants while minimizing adverse effects from 

treatment projects. 

Objective 4.1 – Maintain water quality while implementing invasive plant treatments. 

Objective 4.2 - Protect non-target plants and animals from negative effects of both 

invasive plants and applied herbicides. Where herbicide treatment of invasive plants 

is necessary within the riparian zone, select treatment methods and chemicals so that 

herbicide application is consistent with riparian management direction, contained in 

Pacfish, Infish, and the Aquatic Conservation Strategies of the Northwest Forest Plan. 

Objective 4.3 - Protect threatened, endangered, and sensitive species habitat threatened 

by invasive plants. Design treatment projects to protect threatened, endangered, and 

sensitive species and maintain species viability. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Goal 5 – Expand collaborative efforts between the Forest Service, our partners, and the public 

to share learning experiences regarding the prevention and control of invasive plants, and the 

protection and restoration of native plant communities. 

Objective 5.1 - Use an adaptive management approach to invasive plant management 

that emphasizes monitoring, learning, and adjusting management techniques. 

Evaluate treatment effectiveness and adjust future treatment actions based on the 

results of these evaluations. 

Objective 5.2 - Collaborate with tribal, other federal, state, local and private land 

managers to increase availability and use of appropriate native plants for all land 

ownerships. 

Objective 5.3 - Work effectively with neighbors in all aspects of invasive plant 

management: share information and resources, support cooperative weed 

management, and work together to reduce the inappropriate use of invasive plants 

(landscaping, erosion control, etc.). 

2.4.2 Inventory and Monitoring Plan Framework 

In addition to the monitoring already required under various Forest Plans, an inventory and 

monitoring plan framework is part of all action alternatives. The framework would assist in 

developing detailed monitoring plans at the sub-regional or site-specific project level. A 

measure included within the monitoring framework that will improve the Forest’s ability to 

detect, respond rapidly to new infestations is the requirement to maintaining an invasive plant 

inventory consistent with nationally accepted (e.g., NRIS/Terra) protocols. 

Three different types of Monitoring are included in the framework: 

Implementation Monitoring - Adaptive management strategies require implementation 

monitoring to determine whether we did what we said we were going to do. This is a 

necessary step in order to determine whether actions are taking place as described in the 

environmental document. Monitoring needs to include the timing of actions and mitigation. 

If actions are not timely, they may not be effective. When mitigation measures are not 

implemented, effects may be different from what was predicted. 

Treatment Effectiveness Monitoring - A long-term adaptive management approach is based 

on changing conditions. The invasive plant infestation conditions need to be monitored in 

order to know when it is appropriate for action to be taken, and whether that action is 

effective. If treatment were not effective, the decision maker would review the strategy 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

outlined in the adaptive management decision to determine whether treatment actions need to 

be changed. 

Protection Measure Effects Monitoring – Were the standards and protection measures 

effective at reducing potential effects to ESA-listed species and/or designated critical habitat? 

It is important to evaluate the effectiveness of protection measures so the Forest Service can 

accurately report and predict the effects of our projects. 

The complete Inventory and Monitoring Plan framework is included in Appendix M. 

2.5 Management Direction Unique to Each Action Alternative 

All the action alternatives follow IWM approaches described in Chapter 2.3. The action 

alternatives represent different approaches to two of the key components of IWM: (1) 

prevention through land management and public-use activities, and (2) identification of 

treatment methods. The alternatives would provide different responses to the following key 

IWM questions: 

• How extensive and restrictive should invasive plant prevention practices be that are 

applied to National Forest management activities and public uses? 

• Under what circumstances and management restrictions should herbicides be used to 

treat invasive plant infestations? 

In addition to the management direction (DFCs, goals, objectives), and the Inventory and 

Monitoring Framework, the action alternatives contains a suite of new Forest Plan standards. 

These standards were designed in cooperation with Forest Service staff, to ensure that longterm multiple use goals and objectives would not be significantly altered through the 

alternatives developed (Forest Service Manual 1922.51/52). Table 2-2 displays and compares 

the alternative Forest Plan standards and the objectives each standard would address.21

 

21 The action alternatives do not always include distinct standards for implementing the objectives. In these 

situations, achievement of the goals and objectives rely on existing laws, policies and manual direction. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 2-2 Action Alternative Standards 

Standard 

(Objective 

Addressed) 

Proposed Action Alternative B 

Prevention Standards 

1 

(Objectives 

1.1, 1.2, 2.3, 

2.4, 2.5) 

Prevention of invasive plant introduction, establishment and spread will be addressed in 

watershed analysis; roads analysis; fire and fuels management plans, Burned Area Emergency Recovery Plans; emergency wildfire situation analysis; wildland fire implementation plans; grazing allotment management plans, recreation management plans, vegetation management plans, and other land management assessments. 

Same as Proposed Action, plus:These documents will address the conditions that spread invasive plants and emphasize 

maintaining/restoring healthy ecosystems as the first line of defense against their spread. 

Same as 

2 

(Objectives 

1.1, 1.2, 

2.3) 

Actions conducted or authorized by written permit by the Forest Service that will operate outside the limits 

of the road prism (including public works and service contracts), require the cleaning of all heavy equipment (bulldozers, skidders, graders, backhoes, dump trucks, etc.) prior to entering National Forest System Lands. This standard does not apply to initial attack of wildland fires, and other emergency situations where cleaning would delay response time. 

Actions conducted or authorized by written permit by the Forest Service that will operate outside the limits 

of the road prism (including public works and service contracts), require the cleaning of all equipment and vehicles prior to entering National Forest System land for all projects, and before leaving the project site, when operating in areas where invasive plants have been identified as present at a level where transport of 

invasive plant seed or vegetation propagules (root fragments) is likely and a concern. This standard would not apply to initial attack of wildland fires, and other emergency situations where 

cleaning would delay response time. 

Same as 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 2-2 Action Alternative Standards 

Standard 

(Objective 

Addressed) 

Proposed Action Alternative B 

3 

(Objectives 

1.1, 2.3) 

Use weed-free straw and mulch for all projects, conducted or authorized by the Forest Service, on 

National Forest System Lands. If State certified straw and/or mulch is not available, individual Forests should require sources certified to be weed free using the North American Weed Free Forage Program standards (see Appendix O) or a similar certification process. This standard may need to be phased in as a certification process is established. 

Same as Proposed Action. Same as 

4 

(Objectives 

1.1, 2.5) 

Use only pelletized or certified weed free feed in wilderness and wilderness trailheads. If state 

certified weed free feed is not available, individual Forests should require feed certified to be weed free using North American Weed Free Forage Program standards or a similar certification process. This standard may need to be phased in as a certification process is established. 

Use only pelletized or certified weed free feed on all National Forest System lands. If state certified weed 

free feed is not available, individual Forests should require feed certified to be weed free using North American Weed Free Forage Program standards or a similar certification process. This standard may need to be phased in as a certification process is established. Choose weed-free project staging areas, livestock and packhorse corrals, and trailheads. 

No corol(Same as 

5 

(Objective 

2.2) 

No corollary standard. 

(Addressed as Objective 2.2 and in the USDA Forest Service Guide to Noxious Weed Prevention Practices) 

Consistent with project objectives, retain native vegetation in an around project locations and 

minimize creating soil conditions that promote the establishment and spread of invasive plants. 

Same a P

6 

(Objectives 

1.1, 5.1, 

5.3) 

Through annual operating instructions, and the revision of grazing allotment management plans, 

incorporate invasive plant prevention practices that reduce the spread of invasive plants. Plan and implement practices in cooperation with the grazing permit holder. 

Same as Proposed Action, plus: 

Document consideration of the prevention practices included in the grazing management section of the USDA Forest Service Guide to Noxious Weed Prevention Practices, (Appendix E). 

Same as 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 2-2 Action Alternative Standards 

Standard 

(Objective 

Addressed) 

Proposed Action Alternative B 

7 

(Objectives 

1.1, 1.2, 

1.3) 

Inspect active gravel, fill, sand stockpiles, quarry sites, and borrow material for invasive plants before use and 

transport. Treat or require treatment of infested sources before any use of pit material. Use only gravel, fill, sand, and rock that is judged to be weed free by District or Forest weed specialists. 

Same as Proposed Action, plus: 

Strip and stockpile and treat infested sources before any use of material. Inspect active gravel, fill, sand stockpiles, quarries, and borrow material annually for invasive plants. 

Same as 

8 

(Objectives 

1.1, 1.2, 

5.1) 

Conduct road blading, brushing and ditch cleaning in areas with high concentrations of invasive plants in 

consultation with District or Forest-level invasive plant specialists, incorporate invasive plant prevention practices as appropriate. 

Same as Proposed Action, plus: Where possible, postpone this work until the invasive 

plants have been treated. In situations where road 

safety considerations dictate action, work from the edges of the infestation toward the center to avoid spreading invasive plants to relatively uninfested areas. Inspect and clean road graders, mowers, and other road blading, brushing and ditch cleaning equipment after operating in infested areas to remove plant seed and propagules. 

Same as 

9 

(Objectives 

1.1, 2.4) 

No corollary standard. Close or decommission non-essential1 roads where 

roads analysis indicates that the presence, type, use and location of roads may increase the introduction and spread of invasive plants; and such introduction adversely affect native plant and animal species and ecosystem function. Retain administrative access as needed for invasive plant treatment and site restoration. 

No corol

10 

(Objectives 

1.1, 2.4, 

2.5) 

Require the establishment of a system of roads, trails, and areas designated for motor vehicle use; and 

prohibit the use of motor vehicles off the designated system that is not consistent with the classes of motor vehicles and if applicable, the time of year, designated for use.2

Same as Proposed Action. No corol

Treatment and Restoration Standards 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 2-2 Action Alternative Standards 

Standard 

(Objective 

Addressed) 

Proposed Action Alternative B 

11 

(Objectives 

1.5, 5.1) 

Prioritize infestations of invasive plants for treatment at the landscape, watershed or larger multiple 

forest/multiple owner scale. 

Same as Proposed Action. Same as 

12 

(Objectives 

1.1, 5.1) 

Develop a long-term site strategy for restoring/revegetating invasive plant sites prior to 

treatment. 

Same as Proposed Action. Same as 

13 

(Objectives 

1.1, 1.4) 

Native plant materials are the first choice in revegetation for restoration and rehabilitation where 

timely natural regeneration of the native plant community is not likely to occur. Non-native, noninvasive plant species may be used when: 1) needed in emergency conditions to protect basic resource values (e.g., soil stability, water quality and to help prevent the establishment of invasive species), 2) as an interim, non-persistent measure designed to aid in the re-establishment of native plants, 3) native plant materials are not available, and 4) in permanently altered plant communities. Under no circumstances will non-native invasive plant species be used. 

Use local native seed and seedlings in revegetation of invasive plant sites, fire lines and burned areas. If 

native seeds/plants are not available, revegetation projects will rarely be undertaken until native plant seed or plants become available, except as an intermediate step toward native restoration. 

In re-vegspecies t

persist. such as cand rangdegraded persistento be unswith inv

14 

(Objectives 

1.4, 4.1, 

4.2) 

Use only APHIS and State-approved biological control agents. Agents demonstrated to have direct 

negative impacts on non-target organisms would not be released. 

Same as Proposed Action. Same as 

15 

(Objectives 

1.4, 3.1, 4.1, 

4.2) 

Application of any herbicides to treat invasive plants will be performed or directly supervised by a State or 

Federally licensed applicator. All treatment projects that involve the use of herbicides will develop and implement an herbicide transportation and handling safety plan. 

Same as Proposed Action. Same as 

16 

(Objectives 

Select from herbicide formulations containing one or more of the following 10 active ingredients: 

chlorsulfuron, clopyralid, glyphosate, imazapic, 

Select from herbicide formulations containing one or more of the following 4 active ingredients: 

clopyralid, glyphosate, sethoxydim, and triclopyr. No 

Select frcontainin

followin

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 2-2 Action Alternative Standards 

Standard 

(Objective 

Addressed) 

Proposed Action Alternative B 

1.4, 3.1, 4.1, 

4.2) 

imazapyr, metsulfuron methyl, picloram, sethoxydim, 

sulfometuron methyl, and triclopyr. Mixtures of herbicide formulations containing 3 or less of these active ingredients may be applied where the sum of all individual Hazard Quotients for the relevant application scenarios is less than 1.0. 3

All herbicide application methods are allowed including wicking, wiping, injection, spot, broadcast and aerial, as permitted by the product label. Chlorsulfuron, metsulfuron methyl, and sulfometuron methyl will not be applied aerially. The use of triclopyr is limited to selective application techniques only (e.g., spot spraying, wiping, basal bark, cut stump, injection). Additional herbicides and herbicide mixtures may be added in the future at either the Forest Plan or project level through appropriate risk analysis and NEPA/ESA procedures. 

mixtures of these herbicide formulations is permitted. All herbicide application methods are allowed including wicking, wiping, injection, spot, broadcast 

and aerial, as permitted by the product label. The use of triclopyr will be limited to selective application techniques only (e.g. spot spraying, wiping, basal bark, cut stump, injection). Additional herbicides, with the exception of picloram, sulfonylurea herbicides and acetolactate synthaseinhibiting herbicides, may be added in the future at either the Forest Plan or project level through appropriate risk analysis and NEPA/ESA procedures. 

2,4-D, chdicamba

imazapypicloramsulfometMixtures formulatactive inwhere thHazard Qapplicati1.0. 3All herbiare allowwiping, iand aeriaproduct Additionmixtures future at project lrisk analprocedur

17 

(Objective 

3.4) 

When herbicide treatments are chosen over other 

treatment methods, document the rationale for 

choosing herbicides. 

Choose non-herbicide treatment methods over herbicides, unless non-herbicide methods are known 

to be ineffective or unfeasible. Use herbicides as a tool of last resort. Reduce herbicide use over time at both the regional and local scale. 

No corol

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 2-2 Action Alternative Standards 

Standard 

(Objective 

Addressed) 

Proposed Action Alternative B 

18 

(Objectives 

3.1, 4.1, 

4.2) 

Use only adjuvants (e.g. surfactants, dyes) and inert ingredients reviewed in Forest Service hazard and risk 

assessment documents such as SERA, 1997a, 1997b; Bakke, 2002. 

Use only adjuvants and herbicide formulations for which all ingredients have been publicly identified. 

Same as 

19 

(Objective 

4.1) 

To reduce or eliminate direct or indirect negative 

effects to non-target plants, terrestrial animals, water 

quality and aquatic biota (including amphibians) from the application of herbicide, use site-specific soil characteristics, proximity to surface water and local water table depth to determine herbicide formulation, size of buffers needed, if any, and application method and timing. Only consider those herbicides and herbicide mixtures registered for aquatic use when evaluating herbicide use near streams or surface water. 

Same as Proposed Action, plus: Minimize application of herbicides and prohibit 

broadcast spraying in the riparian reserve land 

allocation and in known aquatic and terrestrial amphibian habitat, including breeding, rearing, and overland dispersal areas. Avoid application of herbicides with adverse effects on aquatic species and amphibians. 

Same as 

20 

(Objectives 

4.1, 4.2, 

4.3) 

Design invasive plant treatments to reduce or eliminate adverse effects to species and critical 

habitats proposed and/or listed under the Endangered Species Act. This may involve surveying for listed or proposed plants prior to implementing actions within unsurveyed habitat if the action has a reasonable potential to adversely affect the plant species. Use site-specific project design (e.g. application rate and method, timing, wind speed and direction, nozzle type and size, buffers, etc.) to mitigate the potential for adverse disturbance and/or contaminant exposure. 

Same as Proposed Action. Same as 

21 

(Objectives 

3.1, 4.2) 

Provide a minimum buffer of 300 feet for aerial application of herbicides near developed 

campgrounds, recreation residences and private land (unless otherwise authorized by adjacent private landowners). 

Same as Proposed Action, plus: Provide buffers to adequately protect culturally 

significant plant and wildlife resources during broadcast application of herbicides. 

Same as 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 2-2 Action Alternative Standards 

Standard 

(Objective 

Addressed) 

Proposed Action Alternative B 

22 

(Objectives 

4.1) 

Prohibit aerial application of herbicides within legally 

designated municipal watersheds. 

Same as Proposed Action. Same as 

23 

(Objective 

3.1) 

Prior to implementation of treatment projects, each 

Forest will develop a public information plan. The plan will ensure (at a minimum) that timely (normally 15 days) public notification will occur. Warning and information signs will be placed at appropriate locations (defined in the public information plan) to inform the public, and forest workers of herbicide application dates and herbicide used. If requested, individuals may be notified in advance of spray dates and times. 

Same as Proposed Action. Same as 

1. “Non-essential” is defined as not needed for future management. 2. Details, conditions, terms, definitions, etc. of this standard parallel those contained in Proposed Rule 36 CFR Parts 212, 251, 261, and 29Designated Routes and Areas for Motor Vehicle Use, Federal Register Vol. 69, No. 135, July 15, 2004 (See Appendix R). 3. ATSDR, 2004. Guidance Manual for the Assessment of Joint Toxic Action of Chemical Mixtures. U.S. Department Health and Human Service, Agency for Toxic Substances and Disease Registry. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

2.6 Comparison of Alternatives 

This section provides a comparison of the treatment methods/tools available under each 

alternative (Table 2-3), and a summary/comparison of the effects of implementing each 

alternative found in Chapter 4 (Table 2-4). Information in Table 2-4 is focused on activities 

and effects where different levels of effects or outputs can be distinguished quantitatively or 

qualitatively among alternatives. 

Herbicide risk assessments were used to evaluate the potential for harm to non-target plants, 

wildlife, human health, soils and aquatic organisms. Worst-case scenarios were considered 

(accidental exposures, application at maximum label rates) and evaluated. The comparison 

table displays the relative risks associated with each alternative based on the suite of 

herbicides and application methods allowed. The number of acres of annual herbicide use is 

based on current herbicide use on and off National Forest, applied to each alternative 

assuming a static budget. Under all alternatives, site-specific choices would be made to 

reduce potential for harm to non-target plants, wildlife, human health, soils and aquatic 

organisms. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 2-3 Treatment Methods Under the Alternatives 

No Action 

(Current Direction) Proposed Action Alternative B 

Manual Hand pulling and use of hand tools. 

All manual techniques known to be useful for treating invasive plants. 

Same as Proposed Action. Same as Pr

Mechanical Any mechanical tool that is known to be useful for treating invasive plants. 

Same as Current Direction, plus: foaming, streaming, infrared, and other 

techniques using heat. 

Same as Current Direction. Same as C

Biological Agents used would be APHIS and state approved (no use on the Malheur NF). 

Agents used would be APHIS and State-approved. Agents demonstrated 

to negatively impact non-target organisms would not be used. 

Same as Proposed Action Same as Pr

Cultural Grazing animals, addition of fertilizer/soil amendments, competitive planting, or any other cultural practice known to be useful for treating invasive plants. 

Same as Current Direction, plus mulching with a variety of materials 

and other local remedies that may be determined to be effective (e.g. spraying water/salt/sugar mixtures). 

Same as Proposed Action. Same as Pr

Herbicides 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 2-3 Treatment Methods Under the Alternatives 

No Action 

(Current Direction) Proposed Action Alternative B 

Herbicide formulations containing only the following 5 active active ingredients are permitted (except on the Malheur NF): glyphosate, picloram, triclopyr, dicamba, and 2,4-D (a “tool of last resort”). All application methods consistent with label requirements are permitted. 

Herbicide formulations and mixtures containing one or more of the 

following 10 active ingredients: chlorsulfuron, clopyralid, glyphosate, imazapic, imazapyr, metsulfuron methyl, picloram, sethoxydim, sulfometuron methyl, and triclopyr. All herbicide application methods are allowed including wicking, wiping, injection, spot, ground level broadcast and aerial, as permitted by product label. Chlorsulfuron, metsulfuron methyl, and sulfometuron methyl will not be applied aerially. The use of triclopyr is limited to selective application techniques only (spot spraying, wiping, basal injections). 

Herbicide formulations containing one or more of the following 4 active 

ingredients: clopyralid, glyphosate, sethoxydim, and triclopyr. No mixtures of these herbicide formulations is permitted. All herbicide application methods are allowed including wicking, wiping, injection, spot, ground level broadcast and aerial, as permitted by product label. The use of triclopyr will be limited to selective application techniques only (e.g. spot spray, wiping, basal bark, cut stump, injection). Herbicides are considered a tool of last resort. 

Herbicide containing 

12 active ichlorsulfurglyphosatemetsulfurosethoxydimtriclopyr. All of herbare alloweinjection, sand aerial, label. 

Prescribed Fire Broadcast and pile burning. Broadcast and pile burning, and flaming. Same as Proposed Action. Same as Pr

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 2-4 Summary of Environmental Effects of Implementing the Alternatives 

Factor 

For Comparison 

Current Direction/ 

No Action 

Proposed Action Alternative B 

Issue 1: Strategies to prevent and control invasive plants can vary in effectiveness Relative rate of invasive plant spread based on predicted effectiveness of prevention standards 

8-12% 

Moderate to high potential for 

reducing rate of spread from 

adherence to new prevention 

standards. 

Highest potential for reducing 

rater of spread from adherence 

to new prevention standards. 

Estimated acreage of invasive plants treated annually based on current herbicide use on and off National Forests applied to each alternative under a static budget 

25,000 Acres 30,000 Acres 20,000 Acres 

Number of years until invasive plants may be controlled assuming above areas are effectively treated and prevention standards reduce rate of spread 

Never 32 years if spread is reduced to 6% 

47+ years even if spread is 

reduced to 4%. This is because 

fewer treatments would be 

expected to occur annually, 

because the expense of treating 

each acre is highest under this 

alternative. 

Issue 2: Invasive plant treatments may harm non-target plants and native plant communities. Number of herbicides included in each alternative that have a relatively higher potential to harm non-target plants 

4 – picloram, glyphosate, 

triclopyr, dicamba 

3 – glyphosate, imazapyr, 

picloram 

Implementing Standard #16 

would mitigate potential effects 

of chlorsulfuron, metsulfuron 

methyl, sulfometuron methyl, 

and triclopyr. 

1 – glyphosate 

Implementing Standard #16 

would mitigate potential effects 

of triclopyr. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 2-4 Summary of Environmental Effects of Implementing the Alternatives 

Factor 

For Comparison 

Current Direction/ 

No Action 

Proposed Action Alternative B 

Number of herbicides included in each alternative that have known potential to cause toxic effects to honey bees 

3 – 2,4-D, glyphosate and 

triclopy 2 – glyphosate and triclopyr 1 –glyphosate 

Acres of annual herbicide treatment as an indicator of relative harm to nontarget plants 12,956 8,369 2,031 Issue 3: Application of certain herbicides may harm some vegetation-eating or insect-eating birds and mammals and/or amphibianThe number of plausible exposure scenarios in each alternative that could result in harmful doses to birds and mammals. 

25 21 12 

Acres of annual herbicide treatment as an indicator of relative harm to wildlife 

13,646 8,989 2,539 

Number of herbicides approved that may harm amphibians 

3 1 1 

Issue 4: Invasive plant treatments may result in risks to human health, including contamination of drinking water Number of worker days of exposure to manual treatment hazards 

36,593 30,719 44,948 

Number of herbicide and NPE worker scenarios exceeding reference dose (RfD) 

Typical 0 

Worst-Case 13 

0 

11 

0 7 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 2-4 Summary of Environmental Effects of Implementing the Alternatives 

Factor 

For Comparison 

Current Direction/ 

No Action 

Proposed Action Alternative B 

Total acreage where worker scenarios exceeding RfD may occur treatment as an indicator of relative potential harm to workers 

Typical 0 

Worst-Case 12,281 

0 

4,960 

0 

508 

Number of herbicide and NPE public scenarios exceeding RfD (other than drinking water contamination) 

Typical 0 

Worst-Case 9 

0 4 

0 4 

Total acreage where these public exposure scenarios exceeding RfD may occur as an indicator of relative harm to the public 

Typical 0 

Worst-Case 591 

0 

930 

0 

508 

Number of herbicide and NPE public scenarios exceed RfD for drinking water contaminated by herbicide runoff / leaching 

Typical 0 

Worst-Case 0 

0 0 

0 0 

Total acreage where risk of public drinking water contaminated by herbicide runoff / leaching exceeds RfD as an indicator of relative harm to the public 

Typical 0 

Worst-Case 0 

0 0 

0 0 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 2-4 Summary of Environmental Effects of Implementing the Alternatives 

Factor 

For Comparison 

Current Direction/ 

No Action 

Proposed Action Alternative B 

Number of herbicide and NPE public scenarios exceed RfD for drinking water contaminated by tanker spill into pond 

Typical 1 

Worst-Case 4 

1 6 

1 3 

Issue 5: Cost of Treatments and Effects on Land Uses Annual acres of treatment for each alternative as an indicator of relative costs 

24,606 29,058 20,310 

Estimated percentage increase in cost of heavy equipment work 

0% 2% 11% 

Tendency for standards to result in road closures and loss of off-highway vehicle access 

No Direct Effect. New 

restrictions on OHV use may 

occur from new national 

policy. 

No new road closures expected 

from invasive plant prevention 

standards. OHV use allowed 

only on specifically designated 

roads, trails, and areas based on 

implementation of draft national 

policy. 

Tendency for more roads to be 

closed or decommissioned due to 

wording of standards. OHV use 

allowed only on specifically 

designated roads, trails, and 

areas, based on implementation 

of draft national policy. 

Tendency for standards to affect grazing locations, timing , intensity and outputs 

Reduces grazing levels due to 

rangeland grazing capacities 

being diminished by invasive 

plants. 

Reduces grazing levels, due to 

more consistent applications of 

prevention measures. 

Highest tendency to reduce 

grazing levels due to more rigid 

and consistent application of 

prevention measures. 

Acres of National Forest where weed free feed would be required 2.5 million 

4.6 million (Wilderness Areas 

only). Increases costs of 

obtaining feed for pack stock, 

increases recreation 

administration costs 

accordingly. 

24.9 million (all National Forests 

in the Region). Increases costs 

of obtaining feed for pack stock, 

increases recreation 

administration costs more than 

the Proposed Action. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

2.7 Alternatives Considered but Eliminated From Detailed Study 

Federal agencies are required by NEPA to rigorously explore and objectively evaluate all 

reasonable alternatives and to briefly discuss the reasons for eliminating any alternatives that 

were not developed in detail (40 CFR 1502.14). Public comments received in response to the 

Proposed Action provided suggestions for alternative methods for achieving the purpose and 

need. Some of these alternatives may have been outside the scope of this EIS, not met the 

Purpose and Need for Action, not reasonably feasible or not viable, duplicative of the 

alternatives considered in detail, or were determined to cause unnecessary environmental 

harm. 

2.7.1 Prohibiting OHVs, Grazing, Logging, and other Land Management 

Activities 

A number of comments received during the scoping process suggested that the Forest Service 

consider prohibiting major land-use activities on National Forests in the Region, such as OHV 

use, logging, livestock grazing, and access for all motorized traffic. The Proposed Action and 

the other Alternatives (especially Alternative B) do include standards that place restrictions on 

some or all of these activities. The alternative of eliminating or prohibiting these activities 

was considered, but eliminated from further study. Eliminating these multiple-use activities is 

outside the scope of this Proposed Action and inconsistent with current laws governing the 

management of National Forest System lands. 

2.7.2 No Treatment of Invasive Plants 

Some public comments suggested that the Forest Service not take action to treat invasive 

plants, but rely only on prevention and passive restoration. An alternative of this nature was 

considered, but eliminated from detailed analysis. 

The purpose and need of this EIS includes making new practices, technologies, and chemical 

formulations of herbicides available for use on National Forests lands in Region Six. There is 

an abundance of scientific literature that supports the timely and appropriate treatment of 

invasive plants, and the active restoration of native plant communities as important tools for 

effective integrated management (See Chapters 3 and 4). Eliminating the consideration of 

these elements of IWM would not address the purpose and need for this action, and would 

likely cause unnecessary environmental harm. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

2.7.3 No Use of Herbicides 

Additional public comments suggested that the Forest Service consider an exclusively nonherbicide alternative. An alternative of this nature was considered, but eliminated from 

detailed analysis because a non-herbicide alternative would not meet the underlying need for 

action. Some invasive plants that infest or can be expected to infest National Forests in 

Region Six can only be effectively controlled with herbicides. 

The issue of scale needs to be considered when planning treatments of invasive species. 

Large populations of certain invasive species can only be effectively controlled with 

herbicides. At present, the only method to control large stands of Japanese knotweed is with 

repeated application of herbicides (Seiger, 1991). The potential for large-scale restoration of 

wildlands infested with quackgrass is probably low to moderately low, unless the infested 

area is tilled, treated with herbicide, and reseeded, or unless large-scale, resource-intensive 

prescribed burn programs, coupled with herbicide and other restoration programs are 

implemented (Batcher, 2002). The best control of perennial pepperweed seems to be from the 

use of herbicides (Morisawa, 1999). Renz (2000) states that many control methods are 

ineffective against perennial pepperweed or can only be used in specific areas. The only nonchemical control method effective against large populations is long-term flooding, but it is not 

known if plants will reestablish if the flooding regime is removed from these areas. Lyons 

(1998) states that the most successful control efforts for whitetop combine several 

management practices such as herbicide application and physical removal by hoeing or tilling 

followed by competitive species plantings. 

The purpose and need of this EIS includes making new practices, technologies, and chemical 

formulations of herbicides available for use on National Forests lands in Region Six. As 

explained in Chapter 1.2, the tools currently available to manage invasive plant infestations in 

the Region, are proving to be inadequate in the face of the complexity of the ecological 

problem that invasive plants incur on native ecosystems. Making additional herbicides 

available for use by National Forests will increase available options for controlling invasive 

species while protecting native plant communities and environmental quality. National 

Forests will still be required to do site-specific environmental analysis before using 

herbicides. By making additional herbicides available, it does not mean that Forests will be 

choosing to use herbicides over other types of control methods. Through this EIS, the Forests 

will be able to consider different herbicides with distinct properties that better address the 

balance of effective control and protecting the environment. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

2.7.4 Additional Use of Herbicides 

Some public comments request that the Forest Service consider the use of other herbicides, in 

addition to the herbicides being analyzed in the EIS. Additional herbicides were not studied 

in detail for the following reasons: 

Any herbicide considered for vegetation treatment of National Forest lands within the 

jurisdiction of the U.S. District Court of Oregon must comply with the requirements of the 

Court’s judgment in Northwest Coalition for Alternatives to Pesticides v. Block, Civil No. 83-

6272-E-BU (D. Ore., 1984). The judgment requires that the Forest Service must make its 

own evaluation of herbicides used in its programs, rather than depending solely on EPA 

evaluation and registration for these herbicides. 

The Forest Service has evaluated the twelve herbicides considered in the action alternatives, 

using its program of national peer-reviewed risk assessments. These twelve herbicides were 

selected for evaluation based on their applicability to Forest Service programs and their 

relatively benign environmental effects, compared to other EPA-registered herbicides. 

The twelve herbicides considered in this EIS will fully meet the purpose and need identified 

for the EIS. Among the twelve herbicides at least one, and generally two or more herbicides 

would effectively meet control objectives for all currently known invasive plants. Additional 

herbicides could be approved in subsequent NEPA decisions with appropriate analysis. 

2.7.5 No use of Biocontrol Agents 

Some public comments request that the Forest Service prohibit the use of biocontrol agents. 

An alternative of this nature was considered but eliminated from detailed analysis for the 

following reasons: 

Biological control of invasive plants is the deliberate use of natural enemies (parasites, 

predators, or pathogens) to reduce invasive plant populations. Natural enemies help prevent 

invasive plants from dominating native habitats. Biological control is self-perpetuating, 

selective, energy self-sufficient, economical, and well suited to integration in an overall 

invasive plant management program (Wilson and McCaffrey, 1999). Successful biological 

control is based on the idea that one of the reasons introduced plants become invasive is their 

natural enemies were left behind (Schooler et al., 1996). Many of the non-native plants that 

become invasive in this country are not invasive in their native lands and are only minor 

components of their native plant communities. Introducing predators, parasites, or pathogens 

from a plants country of origin does not eradicate, but controls any given invasive plant. 

Biological control is used when eradication is no longer deemed possible. The use of 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

biological control agents is an attempt to make an invasive plant a minor component of its 

newly adopted community. 

All agents considered for use in the United States undergo rigorous host-specificity testing, 

designed to ensure that introduced biological control agents are limited in host range and do 

not threaten native, nursery, or crop plants (see Chapter 3.3.2). This testing limits the 

introduction of organisms that will not survive or will not affect the target invasive plant, 

identifies non-target plants likely to become impacted, and examines the host-specificity of 

organisms closely related to the proposed agent. Testing also ensures that climatic and biotic 

constraints on the agent are considered. 

The use of bio-controls is an important tool in a complete program of IWM. Eliminating the 

consideration of bio-controls would not address the purpose and need for this action, and 

would likely cause unnecessary environmental harm. 

2.7.6 Prohibit Aerial Application Of Herbicides 

Some public comments suggested that the Forest Service prohibit the aerial application of 

herbicides (spray application from planes, or helicopter). An alternative of this nature was 

considered but eliminated from detailed analysis for the following reasons: 

The purpose and need of this EIS includes making new practices, technologies, and chemical 

formulations of herbicides available for use on National Forests lands in Region Six. A “no 

aerial application alternative” does not meet this underlying need for action. There are 

locations (Hell’s Canyon being the best example), where because of scale, topography and/or 

access, prohibiting the use of aerial application of herbicides to treat invasive plants would 

essentially mean no effective invasive plant control would occur. In these rare cases, aerial 

application of herbicides is the only effective control method. 

2.7.7 Restore Native Ecosystems Alternative (RNEA) 

The Restore Native Ecosystems Alternative (RNEA) was prepared by a coalition of citizens 

and citizen groups who are interested in prevention and control of invasive plants on National 

Forest, and other federally managed lands in the Region. The focus of RNEA is to enhance 

the ecological integrity of National Forests and grasslands by restoring natural processes, 

native species, ecosystem function, and resilience of plant and animal communities. 

Under RNEA, invasive plant treatment and restoration actions must utilize a precautionary 

approach (i.e., proceed experimentally and cautiously) using the best available science, 

incorporating information gained from local experts where applicable. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

RNEA would require an adaptive process that incorporates information learned from 

monitoring and evaluation. The public would be directly involved in the process. 

Under RNEA, those land management activities associated in the scientific literature with 

increases of invasive species (e.g., livestock grazing, logging, road maintenance and 

construction, and off-road vehicle travel), are avoided in favor of National Forest activities 

that are compatible with native vegetation and ecological integrity. 

RNEA requires use of the least intrusive techniques available to restore ecological integrity. 

Treatments methods associated in the scientific literature with human and/or ecological harm 

are avoided, wherever possible, in favor of treatments that are effective without causing 

collateral damage. 

Under RNEA the use of herbicides for treatment of invasive plants is a “tool of last resort” 

and the use of herbicides is mandated to decline within the Region over time. 

The Regional Forester considered this alternative in total, and decided to dismiss it from 

detailed study because certain components of RNEA were outside the scope of this EIS, not 

reasonably feasible or not viable, or duplicative of the alternatives considered in detail. 

However, many of the main concepts from RNEA, (e.g., proceeding experimentally and 

cautiously, favoring nonchemical over chemical treatments, reducing the amount of herbicide 

use over time, and reducing conditions that favor invasive plants) have been incorporated into 

the action alternatives, particularly Alternative B. 

Table 2-5 reviews the components of RNEA that were dismissed from detailed consideration. 

The items in parenthesis (e.g., ORV 1, MONITOR 1, etc.) refer to action items in RNEA. A 

full copy of RNEA is included in Appendix L. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 2-5 Components of the RNEA Dismissed From Detailed Consideration 

Component Reasons for Dismissal 

The scope of program funding is too large for Forest Plan 

management direction and is outside the decision space of this EIS. 

Congress is responsible for funding the Forest Service, thus the 

Regional Forester cannot base project approval on future funding. 

Include realistic and dedicated 

funding for monitoring and 

appropriate responses to monitoring 

(ORV 1). If baseline and posttreatment evaluation monies are not 

available, then the project shall not 

be approved (MONITOR 1). 

Eliminate funding based on acres of 

vegetation directly treated the 

previous year without: documented 

alternation of the conditions that 

favored the presence of invasive 

plants, and/or restoration programs to 

restore the site to native vegetation 

(CEPA 5). 

Develop a long-term (e.g., 100-year) 

plan for preventing and minimizing 

invasive plans and restoring 

ecosystem integrity (PRIORITIES 

9). 

National Forest Plans typically describe long-term (e.g. 50 years) 

desired conditions but include shorter-term (10-year) action plans. 

A 100-year plan is beyond the scope of management direction 

included in Forest Plans. 

Include new requirements for Fire 

Management Plans (PRIORITIES 12 

thru 17). 

Standard #2 requires consideration of invasive plant management 

in plans such as fire management plans. Additional requirements 

for Fire Management Plans are outside the scope of this action. 

Cease new road construction and 

most road reconstruction in riparian 

areas (PREVENTION 10). 

This EIS discusses management direction related specifically to 

invasive plant management on National Forest lands. Prohibiting 

road construction within riparian areas is outside the scope of this 

action. 

Implement home-site fuels 

treatments and restoration projects 

within the wildland-urban interface 

(PREVENTION 13, 15-17). 

This EIS discusses management direction related specifically to 

invasive plant management on National Forest lands. 

Implementation of vegetation treatments on private lands is outside 

the scope of this action. 

Herbicide treatments shall be used 

only in conjunction with eliminating 

or reducing the conditions that have 

favored the presence of invasive 

plants (PRIORITIES 4). 

Alternative B includes the following standard: “Use herbicides as a 

last resort, as part of a treatment regime that eliminates or reduces 

conditions that favor invasive plants and encourages conditions 

that resist invasive plants.” This standard reflects the concept 

behind PRIORITIES 4, without making it a hard and fast rule. 

There may be situations where no reasonable options exist to 

reduce or eliminate the condition that favors the presence of 

invasive plants (i.e. open road systems) where such a standard 

would be commensurate with a No Herbicide alternative. This 

component would not meet the purpose and need for action, which 

includes making new practices, technologies, and chemical 

formulations of herbicides available for use on National Forests in 

Region Six. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 2-5 Components of the RNEA Dismissed From Detailed Consideration 

Component Reasons for Dismissal 

Limit timber sale hauling to dry 

(where pathogens like Port-OrfordCedar root disease and laminated 

root rot can be spread) or frozen 

conditions. 

Root diseases and root disease mitigation are outside the scope of 

this action. 

Prohibit surface disturbance 

associated with oil and gas 

exploration, development, and 

production (PREVENTION 25, 27 

thru 30, 31, 35). 

This EIS discusses management direction related specifically to 

invasive plant management on National Forest lands. Regulations 

regarding surface disturbance related to oil and gas exploration, 

development and production is outside the scope of this action. All 

action alternatives require consideration of invasive plans during 

planning of projects approved by the Forest Service. 

Use existing data, map and describe 

the presence and integrity of 

biological crust at the ecoregion and 

watershed levels (PREVENTION 

36). 

This approach may be appropriate for site-specific projects, but not 

relevant or realistic at the Regional or Forest-wide scale. 

Prepare and implement a general 

plan for damaged biological crusts 

(PREVENTION 38). 

This approach may be appropriate for site-specific projects, but not 

relevant or realistic at the Regional or Forest-wide scale. 

Adopt a Carhart Model for 

completing minimum requirement 

analyses and minimum-impact tool 

analysis for Wilderness. 

This EIS discusses management direction related specifically to 

invasive plant management on National Forest lands. Designating 

decision making models for Wilderness management is outside the 

scope of this action. 

Use prescribed fire only in concert 

with a restoration assessment with 

clear objectives for native plant 

composition (PREVENTION 17). 

This EIS discusses management direction related specifically to 

invasive plant management on National Forest lands. Requiring 

use of prescribed fire solely as a restoration tool is beyond the 

scope of this EIS. 

Assure availability of native seed and 

plants (REVEGETION 4). 

The Regional Forester cannot ensure commercial availability of 

native seeds and plants. Alternatives PA and B emphasize use of 

native plants as available. 

Following fire or other disturbances, 

do not propose reseeding unless it 

can be shown that natural 

regeneration is unlikely (MONITOR 

1). 

This EIS discusses management direction related specifically to 

invasive plant management on National Forest lands; general 

direction related to responses to disturbance is outside the scope. 

All alternatives do require consideration of invasive plants in 

burned area emergency recovery plans. 

Offer simple invasive plant exotic 

species reporting forms to visitors 

(CEPA 1). 

This type of public involvement can be implemented thru routine 

program mechanisms that do not require a NEPA analysis or 

decision. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

CHAPTER 3 AFFECTED ENVIRONMENT 

Chapter 3 focuses on the invasive plant problem and the elements of the human environment 

that have been adversely affected by invasive plants. This chapter is organized into three 

parts: Chapter 3.1 discusses the current situation including the extent of invasive plants found 

in Region Six and the mechanisms by which these plants are spreading. Chapter 3.2 discusses 

the influence of invasive plants on ecosystem components. Chapter 3.3 describes current 

invasive plant management techniques. 

Terminology 

The many terms used to describe and discuss invasive plants may be confusing. Frequently used terms include: 

weed, exotic, alien, invasive, non-native, and noxious weed. While often used interchangeably, there are 

important distinctions between these terms. 

Weed is a human oriented term generally applied to any plant that is growing where someone doesn’t want it. 

Which plants are wanted and unwanted depends on the setting or on individual prejudices and taste (Randall 

1997). Not all weeds are non-native. The word weed is occasionally used in this document. 

Exotic and alien are often used interchangeably to describe an unwanted plant (weed) that has been introduced 

to an ecosystem, or is non-native. 

Invasive plants are distinguished from other non-native plants by their ability to spread (invade) into native 

ecosystems. Invasive plants are defined here as “a non-native plant whose introduction does or is likely to cause 

economic or environmental harm or harm to human health” (Executive Order 13122). 

Noxious weed is a legal designation that can be assigned at both the State and/or Federal level. Noxious weed 

lists vary by State and often focus on species that have a negative impact on commercial agriculture or 

rangelands. States have developed laws that require the control or elimination of noxious weeds by landowners. 

Not all invasive plants are designated as a State or Federal noxious weed. 

Naturalized species are non-native plants that reproduce consistently and sustain populations over many live 

cycles without direct intervention by humans (or in spite of human intervention); they often recruit offspring 

freely, usually close to adult plants, and do not necessarily invade natural, semi-natural or human-made 

ecosystems (Richardson et al 2000). 

Gross Infested Area- This area is defined by drawing a line around the outer perimeter of an infestation. The 

area within the line can have significant parcels of land that are not occupied by an invasive plant and can 

include more than one species. 

Infested Area- This is the contiguous area of land within a gross infested area that is occupied by a single 

invasive plant species (i.e. the infested area excludes the portion of the gross area that is not occupied by an 

invasive plant). The infested area is estimated through visual inspection of the gross area. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

3.1.1 Current Extent of Invasion 

National Forest System land in Region Six totals nearly 25 million acres. Many more 

millions of acres of federal, state, Tribal, and private lands are found interspersed with these 

lands. Invasive plant management involves a complex set of interactions between different 

land ownerships, and land uses that occur within and around National Forests. 

An estimated 420,000 acres22 of National Forests and Grasslands in Region Six are infested 

with invasive plants (See Figure 3-1). At least 107 species have been inventoried by Forest 

Service botanists and weed specialists using inventory and mapping protocols established by 

the Forest Service under the NRIS Terra Invasive Plant database (USDA Forest Service, 

2002-6161) (Appendix B). It is highly likely additional species are present on the National 

Forests in this Region, but have yet to be discovered. 

Invasive plant populations increase in acreage at an estimated rate of 8-12 percent per year on 

Forest Service System land (USDA Forest Service, 1999). Using this range, if one estimates 

spread at 10 percent per year, about 4, 200 acres of National Forest will be infested annually 

in Region Six. At the world-wide scale, this rate of invasion will likely increase exponentially 

during the next decade (Mack et al., 2000). 

From 1985 to 1996, invasive plants quadrupled to 17 million acres on western federal lands 

(Asher, 1998; Westbrooks, 1998). Distributions of invasive plants within the Region are 

increasing most rapidly in National Forests east of the Cascade crest (USDA Forest Service, 

2000-Montoring). 

 

22 Invasive plant surveys on National Forests in Region Six are not yet complete, and existing inventories vary 

from one National Forest to another. The estimate of 420,000 acres of invasive plants are based on the best 

information available from the 19 National Forests in the Region Six. 

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Willamette

National Forest

Deschutes

National Forest

Wenatchee

National Forest

Okanogan

National

Forest

Gifford Pinchot

National Forest

Mt. Hood

National Forest

Siskiyou

National Forest

Fremont

National Forest

Umpqua

National

Forest

Mt. BakerSnoqualmie

National Forest

Malheur

National Forest

Colville

National Forest

Winema

National

Forest

Wallowa-Whitman

National Forest

Umatilla

National Forest

Rogue River

National

Forest

Ochoco

National Forest

Siuslaw

National Forest

Olympic

National Forest

Columbia River Gorge

National Scenic Area

CALIFORNIA

No warranty is made by the US Forest Service as to the 

accuracy, reliability, or completeness of these data for 

individual or aggregate use with other data. Original data 

were compiled from various sources. This information may 

not meet National Map Accuracy Standards. This product 

was developed through digital means and may be updated 

without notification.

P a c i f i c 

O c e a n

NEVADA

WASHINGTON

IDAHO

0 20 40 80 120

Miles

0 30 60 120 180

Kilometers

Figure 3-1 Invasive Plants Inventory, April 2003

OREGON

CANADA

Albers Equal Area Projection centered on 120 degrees 30 minutes west

Standard parallels: 43 degrees 10 minutes north and 50 minutes north.

Invasive Plants EIS Project

USDA Forest Service

PO Box 3623

Portland, OR 97208

Legend

Invasive Plant Present
Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

3.1.2 Invasive Plant Species in Region Six 

There are 107 species of invasive plants reported in Region Six Forests (Appendix B). These 

species were added to the inventory in cooperation with local weed experts such as county or 

state weed coordinators23. 

The list of invasive plant species is not complete. Species known to be invasive may not be 

included on the list yet (such as Kentucky bluegrass or dandelion) because weed coordinators 

have not determined a strategy to treat them or may consider tolerating them due to the extent 

of their populations. The list of species provided is not meant to be static; it will evolve as 

inventories continue and species of high threat are discovered24. 

Species that cover the majority of known sites are (in order of most acres to least): diffuse 

knapweed, meadow hawkweed, small bugloss, spiny plumeless thistle, spotted knapweed, 

scotch broom, European beachgrass, musk thistle, Dalmation toadflax, Canada thistle, yellow 

starthistle, St. Johnswort, Himalayan blackberry, bull thistle, tansy ragwort, Scotch thistle, 

houndstongue, whitetop and medusahead. This list reflects the species found most often on 

Forests in Region Six, not necessarily the species of most concern throughout the Region and 

under different ownership. 

These nineteen species will have varying treatment objectives and priorities for treatment (see 

Chapter 3.3.2 for more details) throughout Region Six. Depending on their location, species 

such as St. Johnswort tend to be tolerated more readily because they may be considered 

naturalized. These species may be of higher concern where native grasslands are invaded or 

where populations threaten adjacent uninfested lands of other ownerships. 

Riparian species such as Japanese and giant knotweed or purple loosestrife, while not reported 

in the top nineteen, are usually underestimated due to the linear nature of their populations. 

These species are considered as very serious threats in both the Pacific Northwest in general 

and on National Forest System lands. An invasive grass such as cheatgrass, also not reported, 

 

23 The determination of invasiveness (see definitions) was made through assessment at the Forest level; 

examples of factors leading to such a determination include if the species was invading native plant communities 

or had been known to be an aggressive invader in similar habitat. Some species on this list may be considered 

naturalized and in lesser need of control efforts. They were added to the inventory because of their location; i.e., 

a small population of a naturalized species in a special area, for example, would be considered invasive for that 

particular project, but the control of the species throughout a Forest would not be considered. 

24 The list is updated annually when NRIS/Terra annual updates are completed. Prioritization for treatment of 

such species will vary by Forest and will be done under site specific projects at the Forest level (see Chapter 

3.3.2 for prioritization strategy). 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

is most likely underestimated because its ubiquitous nature on the eastside of the Cascades 

may make the species overlooked for treatment or considered untreatable in some situations. 

Other species that are starting to spread within the Region and considered by local authorities 

as important species to control before their acreage grows are: rush skeletonweed, perennial 

pepperweed, leafy spurge, orange hawkweed, common toadflax, slender false brome, meadow 

knapweed, reed canarygrass, and numerous other invasive knapweed species25. Any species 

on state noxious weed lists in Washington and Oregon, while perhaps not on National Forest 

System land yet, would be considered of high threat if found. 

Below, five species were selected to represent and portray the variety of plant types, growth 

and reproductive strategies, and control challenges faced by National Forests in the Region. 

These widespread species are of particular concern either because of the large number of 

acres they have invaded, their potential for further spread, and/or the difficulty associated with 

their control. They provide a picture of the variety of biological traits (see Table 3.1) that can 

be found in the invasive plants of Region Six. 

Dalmatian toadflax (Linaria dalmatica) 

Dalmation toadflax occurs on all but five National Forests in the Region and has been 

expanding rapidly in drier, eastside forests. 

Dalmatian toadflax is native to the Mediterranean region and is named for its occurrence 

along the (Dalmatian) coast of Croatia (Alex, 1962). Also known as broad-leaved toadflax, 

this species has been under cultivation in Europe for centuries and was introduced into North 

America as an ornamental. 

Dalmatian toadflax prefers sandy or gravelly soil, and tolerates low temperatures. It is most 

commonly found along roadsides, and in rangelands, dry forests, and pastures, but adapts to a 

wide range of habitats. It tolerates low temperatures. The species invades disturbed or 

cultivated ground, but can also invade relatively undisturbed native plant communities. 

Dalmatian toadflax reproduces by both seed and extensive horizontal roots. This species is an 

aggressive invader, capable of forming colonies through adventitious buds from creeping root 

systems (Carpenter and Murry, 1998). These colonies can push out native grasses and other 

perennials, thereby altering the species composition of natural communities. 

 

25 These species have invaded lower elevation lands under Bureau of Land Management, state and private 

ownership, but may still be controlled on Forest lands in Region Six. Also, any species on state noxious weed 

lists in Washington and Oregon, while perhaps not on Forest Service land yet, would be considered of high 

threat if found. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

The deep, extensive root systems of this perennial species make it difficult to control. The 

taproot may penetrate 1 meter into the soil and lateral roots may be several meters long 

(Carpenter and Murry, 1998). Vegetative reproduction can even occur from small root 

fragments (as short as 1 cm in length) left in the ground (Carpenter and Murry, 1998). 

Japanese knotweed (Polygonum cuspidatum) 

Though Japanese knotweed is currently reported on only five National Forests, the difficulty 

with control and the high potential for spread is of concern. While only Japanese knotweed is 

discussed here, other species in the Region are also of great threat including giant knotweed 

and Himalayan knotweed. 

Japanese knotweed is native to eastern Asia and was introduced from Japan as an ornamental 

garden plant in the late 1800’s. It is now widely distributed in much of the eastern U.S., and 

occurs in coastal areas of Oregon and Washington. Japanese knotweed is a riparian species 

that spreads quickly to form dense tall thickets that shade out other species and prevent 

regeneration of native plants. It reduces species diversity and damages wildlife habitat 

(Seiger, 1991). Japanese knotweed poses a significant threat to riparian areas where it can 

survive severe floods and is able to rapidly colonize scoured shores and islands (Alien Plant 

Working Group, 2004b). Once established, populations are extremely persistent. 

Rhizomes can regenerate from small fragments (Seiger, 1991). Dispersal can occur naturally 

when rhizome fragments are washed downstream and deposited on banks, or more 

commonly, when humans transport soil as fill dirt (Seiger, 1991). Monitoring for the 

introduction of Japanese knotweed and manually removing the entire plant can prevent 

establishment. Repeated cutting may control small stands, but the only known method to 

control large stands is with repeated application of herbicides (Seiger, 1991). Innovative 

herbicide applications such as stem injection are being used with success and can mitigate 

effects to non-target species (Soll, 2004). 

Medusahead (Taeniatherum caput-medusae) 

A winter annual native to the Mediterranean region of Eurasia, medusahead was introduced 

into the United States in the late 1880s and spread rapidly in the 1930s (Maurer et al., 1988). 

Since then it has become predominant on millions of acres of semi-arid rangeland in the 

Pacific Northwest (Whitson et al., 2001). 

This species is so competitive that it can replace other invasive species such as cheat grass 

(Bromus tectorum) on certain soils. It threatens native grasses in sparse rangelands, as well as 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

in more complex communities degraded by disturbances, such as overgrazing, fire, or 

cultivation (Maurer et al., 1988). Established populations form stem mats 5-12.5 cm thick 

which decompose slowly, due in part to the high amount of silica in the foliage. This dense 

litter cover enhances medusahead germination, ties up soil nutrients, and contributes to fire 

danger in the summer (Maurer et al., 1988). 

Spotted knapweed (Centaurea biebersteinii) 

This species is reported to occur on every National Forest in Region Six. This native of 

Europe (named for the dark fringe on the flower head) is one of eight invasive Centaurea 

species reported to occur in the Region. Spotted knapweed infests a variety of habitats 

including roadsides, fields, forests, prairies, meadows, pastures, and rangelands. Its rapid 

establishment and spread are typically linked to some form of disturbance (Alien Plant 

Working Group, 2004c). 

Spotted knapweed out-competes native plant species, reduces native plant and animal 

biodiversity, and decreases forage production for livestock and wildlife (Alien Plant Working 

Group, 2004c). Sites infested with spotted knapweed have been shown to have higher than 

normal water runoff and stream sediment loads (Lacey et al., 1989). This species is an 

aggressive competitor and produces an allelopathic compound (cnicin). 

Spotted knapweed is a perennial that lives up to 9 years and is capable of producing seed each 

year (Sheley and Petroff, 1999). Literature suggests that seeds are viable in the soil for at 

least 8 years; therefore, treatments aimed at preventing seed production, such as manual 

treatments, must be a long-term. 

Yellow starthistle (Centaurea solstitialis) 

Occurrence of yellow starthistle is reported on eight forests in the region, and is rapidly 

expanding in eastern Oregon. Yellow starthistle is a winter annual that can form dense 

impenetrable stands that displace desirable vegetation in natural areas, rangelands, and other 

places (DiTomaso, 2001). This species was introduced into North America as a seed 

contaminant in Chilean-grown alfalfa seed sometime after 1849 (DiTomaso, 2001). In the 

past 40 years it has spread exponentially throughout the west. 

Yellow starthistle is best adapted to open grasslands with deep well-drained soils and annual 

precipitation between 10 and 60 inches, but competes successfully in a wide range of habitats 

(DiTomaso, 2001). It favors sites originally dominated by perennial grasses, primarily 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

bluebunch wheatgrass (Psuedoroegneria spicata), Idaho fescue (Festuca idahoensis), and 

Sandberg bluegrass (Poa secunda) (Sheley and Petroff, 1999). 

Yellow starthistle displaces native plant communities and reduces plant diversity (Sheley and 

Petroff, 1999). It forms solid stands that dramatically reduce forage production for livestock 

and wildlife (Sheley and Petroff, 1999). This species causes a fatal neurological disorder 

when ingested by horses called “chewing disease.” 

3.1.3 Mechanisms of Invasion 

The presence of invasive plants is not a new phenomenon. But the geographic scope, 

frequency, and the number of species involved have grown enormously as a direct 

consequence of expanding transport and commerce in the past 500 years, and especially in the 

past 200 years. Invasion occurs when non-native species are transported to new, often distant 

places where they proliferate, spread, and persist. For example, some invasive plants have 

been accidentally introduced to this country as contaminants among crop seed, ballast in 

cargo ships, or on other vessels (Mack et al., 2000). The rapid rate of human expansion 

accounts for a majority of the long-distance dispersal of newly invading species (Grime, 

2001). 

Purposeful and accidental introductions have occurred for centuries, but major introductions 

have occurred most rapidly over the past century. Introductions of invasive plants for forage 

(i.e. contaminated livestock feed), ornamental landscaping, road and dune stabilization, and 

erosion control have occurred throughout National Forest and adjacent lands in the Pacific 

Northwest. Most invasive plants have been introduced for horticultural use by nurseries, 

botanical gardens, and individuals (Reichard and White, 2001). Commercial landscape 

nurseries in Oregon and Washington sell, or once sold, exotic species for domestic 

landscaping that later were found to be invasive (e.g. butterfly bush, pampas grass, purple 

loosestrife, English ivy). These have been shown to spread to federal lands (Whitson, 2001). 

Pacific Ocean dune ecosystems were “stabilized” using beach grass; which has affected the 

distribution and demographics of many species inhabiting the dune habitat. Non-native 

species have been used in seed mixes on National Forests for erosion control, bank 

stabilization, and burned area rehabilitation. In many cases, these non-native species are not 

invasive. Timothy and Kentucky bluegrass, for example, are clear exceptions. 

The plant invasion process occurs in three phases: introduction, establishment, and spread. 

Once an introduction occurs, a delay or lag phase often occurs while the invasive plant 

becomes established (Figure 3-2). The length of this initial phase varies, but can last for up to 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

100 years (Hobbs and Humphries, 1995). This phase is followed by a period of rapid growth 

that continues until the invasive plant reaches the bounds of its new range (Mack et al., 2000). 

Figure 3-2 Three Phases of Invasion 

This model provides guidance for making timely and appropriate decisions for managing 

invasive plants. Preventing species in the lag phase from spreading should be a priority for 

managers. Controlling infestations during periods of establishment when enough residual 

desired vegetation remains in the understory is another crucial time. Once the majority of the 

area becomes dominated by invasive plants, control can be difficult and extensive 

restoration/rehabilitation is necessary. 

The study of biological invasion began in earnest with Charles Elton’s work, as described in 

the 1958 version of The Ecology of Invasions by Animals and Plants (Elton, 2000). Decades 

later, Grime (1974) proposed that a plant responds to stress, competition, and disturbance in 

its environment, and these factors drive the survival and invasion strategies a species might 

employ. Since then, other researchers have attempted to characterize the traits that make 

invasive species so successful (Hobbs, 1991; Perrins et al., 1992; Williamson and Fitter 1996; 

Reichard and Hamilton, 1997). 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Although biological traits of individual invasive plant species vary, most possess one or more 

of the following characteristics (Baker, 1974; Rejmanek and Richardson 1996; Rejmanek, 

2000). These traits (Table 3-1) enable invasive plants to rapidly colonize new areas and 

displace native vegetation. Plants that possess a combination of these traits are able to 

succeed in a wide variety of habitats. These biological traits are exemplified by invasive plant 

species described in Chapter 3.1.2. 

Table 3-1 Biological Traits That Enable Invasive Plants to Colonize New Areas 

• Early maturation, i.e., invasive plants grow and reproduce earlier in the year than do many native plants. 

• Long-lived seeds that can survive harsh conditions, and often have more than one inherent dormancy 

pattern; allowing for development of a long term viable seedbank. 

• Adaptations for spreading both long and short distance (e.g., hooks, bladders, and wings). Seeds are 

easily dispersed by human activity and natural vectors. 

• Capacity to produce many seeds, especially in favorable environmental circumstances. 

• Long-lived, often perennial plants (e.g., persisting for several years) annual or biennial species with the 

capacity to become perennial under the right conditions. 

• Ability to delay flowering until environmental conditions improve. 

• Able to reproduce vegetatively (i.e., without having to produce seed). 

• Hybrids of vegetatively reproducing species can develop viable seed (e.g. knotweeds). 

• Tolerate a wide range of physical conditions. 

• Rapid growth, often with high photosynthetic rates providing a competitive advantage. 

• Self-pollinating (i.e., able to produce seed without being cross-pollinated by another plant). 

• Compete intensely for nutrients. 

• Produce allelopathic (toxic) compounds that negatively affects neighbors. 

Natural Vectors 

Once introduced, natural vectors26 such as birds, insects, or wildlife, natural forces such as 

wind, and water assist in the distribution of invasive. Wind and water in particular, are major 

natural dispersal agents. For example, wind blown seed of rush skeleton weed can be 

dispersed up to twenty miles. Water is a primary aid in the dispersal of many species, 

including Japanese knotweed. In many situations, even upland invasive plants are 

disseminated along river corridors and then move upland (LeCain, 2000). Rivers and 

waterways may be one of the biggest spread mechanisms for invasive plants (Sheley et al., 

1995). 

 

26 For the purposes of this document, the term “natural vectors” will be used interchangeably with “natural 

forces” or simply “vectors. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Various wildlife species can contribute to the spread of invasive plant species by dispersing 

seeds in their dung, on their coats or feathers, or between their hooves. For example, birds 

feeding on the berries of English Ivy are the primary vectors for this invasive plant (Alien 

plants working group, 2004a). Scotch broom seeds are dispersed not only through birds, but 

also ants (Parker et al., 1998). Research has been conducted on seed dispersal by birds, 

rabbits (Malo et al., 2000), and ungulates (Bodmer, 1991; Gill and Beardall, 2001; Howe and 

Smallwood, 1982; Janzen, 1984; Malo and Suarez, 1995; Vickery, Phillips, and Wonsavage, 

1986). Viable seeds and subsequent plant germination have been documented from the dung 

of cattle, sheep, horses, deer, and pheasants (Gardner, McIvor, and Jansen, 1993; Malo, 

Jimenez, and Suarez, 2000; Thill, Zamora and Kambitsch, 1986; Welch, 1985). In the British 

Isles, over 60 plant species have been shown to germinate from deer fecal pellets (Gill and 

Beardall, 2001, citing Malo and Suarez, 1995; and Welch, 1985). 

Seed characteristics are important in determining the ability of viable seeds to be transported 

by or pass through digestive systems of wildlife or livestock (Gill and Beardall, 2001). Small 

hard seeds are more likely to survive mastication and digestive acids, enzymes, and bacteria 

(Gardner, McIvor; and Jansen, 1993). Seeds with hooks, spurs, or awns can attach to fur or 

wool and be transported farther than seeds without obvious means of attachment (Graae, 2000 

- cited in Gill and Beardall 2001). 

The Role of Disturbance in Invasion 

Invasion and dominance by invasive plants is highly correlated with soil disturbance, but are 

not limited to disturbed areas (Cox, 1999). Invasive plants readily invade, occupy and 

dominate conifer plantations, road prisms, trails and trailheads, mined sites, gravel pits, river 

corridors, wildlife wallows and bedding areas, and rangelands. Many invasive species can 

also establish in naturally occurring disturbances or small openings. For example, once 

highly competitive vegetative growth begins, the condition of rangeland, even if excellent, 

will probably do little to slow expansion of the infestation (Sheley and Petroff, 1999). Natural 

and human induced small-scale and large-scale disturbances create “safe sites” for invasive 

plant establishment, and in areas where desirable species are not available to occupy these 

sites, invasive species can dominate (Lukan, 1990). 

While characteristics that lead to invasiveness continue to be debated, many agree that 

understanding the biological traits of an invasive plant and the environmental (physical) 

factors that make a habitat susceptible is critical to understanding the process of invasion 

(Kimberling et al., 2003). Understanding this interaction will be critical for not only 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

managing current infestations, but also in predicting the location of the next invasion. 

Important environmental requirements for successful establishment of many invasive plants 

include increased light, bare ground, available water, and nutrients. 

All ecosystems are subject to natural and human caused disturbances (Lukan, 1990). Some 

type of disturbance usually precedes the establishment of most plant species. The greater the 

extent and intensity of ground disturbance, the more likely an invasive plant will be successful 

in a native plant community (Crawley, 1987; Evans and Young, 1972; Hobbs, 1989). 

Disturbance creates patches of open ground and increases the availability of one or more 

limiting resources. Disturbances can create conditions favorable for desired species, 

depending upon its size, severity, frequency, and timing (Sheley et al., 1996). Disturbance 

may be an essential precursor to invasive plant invasion (Fox and Fox, 1986; Hobbs, 1989; 

Hobbs and Huenneke, 1992). Even when invasions proceed without continuing disturbance, 

there is often an initial disturbance event that initiates the invasion (Hobbs, 1989). 

The requirement of ground disturbance while typical is not always the case. Such “super 

invaders” as false brome can invade low elevation closed canopy coniferous forests in the 

Willamette Valley and Cascade foothills and can become dominant in the understory, outcompeting native vegetation including rare species and can even out-compete tree seedlings 

(Kaye, 2001). 

Many forests experience multiple natural and human imposed disturbances, which have 

synergistic effects in altering native plant communities and increasing probabilities of 

invasive plant invasions. Fires have been implicated as a major natural disturbance, creating 

conditions favorable for invasive plants. For example, Jacobs and Sheley (2003) found that 

Dalmatian toadflax seeds increased 10-fold after a fire. In addition, tansy ragwort 

dramatically increased after wildfire (Trainor, 2003). Major efforts have been necessary to 

manage invasive plants after wildfires (Goodwin and Sheley, 2001). 

Hiking and wildlife trails, as well as roads and roadsides can pass through burned areas, 

increasing the susceptibility to plant invasions (Greenberg et al., 1997; Hobbs, 1991; Harrod, 

2001). Invasive roadside plants have become established in newly burned areas that were 

previously intact native communities (Milberg and Lamont, 1995). 

Despite the linkages between disturbance and invasive plants, much remains to be learned 

about invasion success. Some disturbance types can be managed to favor desired plant 

communities (grazing regimes, timber harvest, prescribed fire, road construction, etc.). For 

example, disturbance may be necessary for the restoration/rehabilitation of weed infested 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

rangeland. Other disturbance types, though, cannot be managed (floods, drought, storms, 

most wildland fire, etc.). The intensity and size of the activity can influence plant community 

composition, trajectories, and susceptibility to invasion. This susceptibility is also dependant 

on site conditions, invasive plant seed proximity, and a number of other variables. Not all 

disturbance levels lead to invasive plant invasions, especially if the disturbances that result 

from the activity are small and minimize soil displacement or seeds of invasive species are not 

available for colonization (Sheley et al., 1996). 

The following section summarizes land management and land use activities linked with 

ground disturbance and subsequent invasive plant invasion in Region Six. For a thorough 

discussion, see the PNW Research Station Causal White Paper, “Forest Service Land 

Management Actions as Contributors to Non-Native Plant Invasions in Pacific Northwest 

Forests and Rangelands: A Review” (Kimberling et al., 2003) and “Ungulates as Contributors 

to Non-native Plant Invasions in Western Landscapes: A Review” (Parks et al., 2003) in 

Appendix D. 

Timber and Other Vegetation Management Activities 

Timber harvest and other vegetation management activities (thinning, mechanical site 

preparation, hand scalping for conifer release, and pruning) can alter forest ecosystems. As 

habitats are altered, new generalist species or edge-adapted species, including invasive plants 

can be favored. The gaps in forest canopy created by these activities can increase the amount 

of light reaching the forest floor increasing the temperature, thus improving invasive seed 

germination and favoring early seral and invasive plants with rapid growth rates. Soil 

disturbances associated with vegetation management can create hospitable environments for 

establishment of invasive plants. For example, soil disturbance can stimulate the germination 

of invasive plant seeds in the seed bank. (Myers and Bazely, 2003). 

The intensity and size of a vegetation management project can influence susceptibility to 

invasion. Reader and Bricker (1994) examined the effects that plot size (amount of tree 

removal), increased light, and exposed mineral soil had on the establishment of non-forest 

species in a deciduous forest in southern Ontario, Canada. Non-forest plant species (native 

and exotic were not distinguished) were able to establish when 8 percent irradiance occurred 

at floor level. More non-forest species established in plots with higher percentages of 

exposed mineral soil, but there was no single minimum area required for establishment. They 

concluded that smaller disturbances are less susceptible to invasion, and that some 

disturbances do not lead to invasion. Deciduous forests may respond in different ways to 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

disturbance (e.g., logging) than coniferous forests, but the relationship between disturbance 

and plant invasions is consistent with other studies (Fox and Fox, 1986; Hobbs, 1991; Hobbs 

and Huenneke, 1992; Hodkinson and Thompson, 1997; Mack et al., 2000; Pickett and White, 

1985.) 

Ground-based heavy equipment used in vegetation management operations, operating in areas 

infested with invasive plants, can spread seeds contained in dust, mud, and slash on the 

equipment to new previously uninfested areas. Logs skidded through existing infested sites 

can catch seeds in the bark and in the accompanying slash. Skidding logs disturbs and 

displaces soil components exposing mineral soil. Logging landings can be a collection center 

for logs and slash, where material embedded with invasive plant seeds gets sorted for 

delivery. Debris from trucks, slash, bark pieces, and mud can spread seeds along roads 

establishing new populations of invasive plant sites. 

In the past, logging and clearcutting usually followed road building in forests. Clearcutting 

fragments forests, decreasing core areas, and increasing edge density (Tinker et al., 1998). 

The gaps in forest canopy created by roads and clearcuts increase the amount of light reaching 

the forest floor, which can increase seed germination and seedling establishment of exotic 

non-forest plants. 

As a result of changes and court interpretation in environmental laws, a shift to ecosystem 

management on public lands, and changing public attitudes, the nature of timber harvest on 

National Forests in Region Six has changed dramatically over the last 35 years. 

Consequently, clearcut acres on National Forests in Region Six have dropped from 

approximately 64,600 acres in 1967 to 718 acres in 2001 (USDA Forest Service, 2003), while 

the amount of acres thinned and treated with selection harvest have both increased. Overall, 

the amount of logging occurring on the National Forest has dropped significantly from 

354,400 acres in 1967 to 44,698 acres in 2001 (USDA Forest Service, 2003). 

Current vegetation management on National Forests in the Region is primarily thinning of 

densely canopied young forests, fuels reduction of over-stocked stands resulting from years of 

vigorous fire suppression, and/or uneven-aged stand management (selection and improvement 

cuts). Trees harvested in current timber sales are relatively small in diameter, as compared to 

the size of trees removed during the clearcutting years of 1960 thru 1990. The removal of 

these smaller diameter trees creates smaller gaps in the forest canopy, and creates less ground 

disturbance. The increased use of helicopter yarding and new log forwarding technology to 

transport logs also decreases the amount of ground disturbance created. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Road building for timber sales, which can spread seeds and create environments susceptible to 

invasive plants, has been reduced. Fewer new roads are being built; the roads that are built 

are typically low standard temporary roads, for one time use and are re-vegetated at the end of 

operations. 

Roads Management 

Region Six manages approximately 93,000 miles of roads, or about one-quarter of all roads in 

the National Forest system. These roads primarily provide access to National Forest system 

lands, but may also be used by private landholders to access their lands under various forms 

of cooperative agreements or easements. Most of the traffic on the road system is generated 

by recreation use, but commercial activities and local communities also use these roads. 

Forest Plans provide forest-level direction and guidelines for development, operation, and 

management of the transportation system. Data on the regional road network was compiled as 

of October 6, 2003, and is presented in Table 3-2 and Table 3-3. 

Table 3-2 Regional Road Mileage by Maintenance Level and Surface Type. 

Surface Type 

Operational 

Mtce Level Unknown Paved Aggregate Pit Run Native Total 

Unknown 11 1 12 

1 5 18 3,321 894 19,737 23,974 

2 7 483 19,897 4,770 29,094 54,251 

3 2 909 9,213 809 530 11,462 

4 1,677 557 5 1 2,241 

5 0 958 958 

Total: 13 4,044 33,000 6,478 49,363 92,898 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 3-3 Regional Road Mileage Summary 

Road Type Miles Percentage 

of System 

Percentage 

of Group 

Closed Surfaced 4,232 4.6 18 

Closed Unsurfaced 19,742 21.3 82 

Total 23,974 

High Clearance Surfaced 25,160 27.1 46 

High Clearance Unsurfaced 29,103 31.0 54 

Total 54,263 

Highway Safety Act Surfaced 14,128 15.2 96 

Highway Safety Act Unsurfaced 532 0.6 4 

Total 14,660 

Approximately 15,000 miles (16 percent) of roads within the region are designed and 

operated to allow travel by standard passenger cars (Maintenance level 3, 4, and 5). Most of 

these roads (96 percent) have hard pavements (normally asphalts) or aggregate surfacing. 

Traffic volumes range from less than 50 to several thousand vehicles per day on roads leading 

to major recreation attractors such at Mt. St. Helens. Several sections of the Highway Safety 

Act apply to these roads and the Forest Service spends most of its limited maintenance budget 

on this system. Some portion of this system may also have seasonal closures for wildlife or 

other reasons. However, there is no consistent data available at the regional scale on the 

extent of these seasonal closures. 

Approximately 54,000 miles (58 percent) of roads within the region are designed and 

operated to allow travel by high clearance highway vehicles. Approximately 46 percent of 

these roads have some type of surfacing (usually aggregate or pit run). These roads are 

maintained infrequently and have low daily traffic volumes, usually less than 30 vehicles per 

day. Some portions of these roads have seasonal closures for wildlife or other reasons. 

However, there is no consistent data available at the regional scale on the extent of these 

seasonal closures. 

About 24,000 miles (26 percent) of roads within the region are closed to highway vehicles for 

periods that exceed one year in length. The roads are closed by some form of physical barrier 

(earth berm, gate, concrete barrier, etc). These closed roads may be used as trails, and may be 

open to motorized trail vehicles, horses, and hikers. Only 18 percent of these roads have 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

some type of surfacing. These roads may be re-opened for their primary use some time in the 

future, and should be considered held in storage. 

There are an estimated 483 aggregate stockpiles in Region Six. Approximately 20 percent are 

used annually for road maintenance. There are an estimated 6,300 rock pits and quarries in 

Region Six, which are also used for road maintenance. Approximately 300 are actively in 

use. Because of the disturbed nature of these sites, invasive plants could easily invade or be 

brought in by equipment. Established populations would then become a seed source for more 

equipment to pick up and move to new locations. 

The region does not have the funding to maintain the road system to standard. The region 

spends approximately $10 million/year on road maintenance (based on FY 02 budget level). 

Condition surveys conducted on the road system from 1999 – 2003 indicate that the Region 

should be spending approximately $120 million/year to maintain the system to standard (2002 

Maintenance Needs Summary). It is estimated that there is a $950 million backlog of 

deferred maintenance and at current funding levels the situation will steadily grow worse. 

Roads and roadside habitats are particularly susceptible to plant invasions for a number of 

reasons. Roads eliminate some of the physical and environmental barriers that prevent plant 

invasions by increasing light availability and opportunities for dispersal. Microenvironmental changes along roads can provide opportunities for invasion because many 

invasive plants are favored by open, disturbed habitats. Disturbance closely associated with 

roads and the establishment and spread of invasive plants are vehicular traffic and 

maintenance activities, road grading, roadside mowing, and keeping roads free of fallen or 

overhanging vegetation. These activities can increase invasive plant introductions because 

vehicles can carry and distribute seeds and propagating plant parts. Because roads create new 

open spaces with higher light availability, invasive plants can follow roads by natural 

dispersal mechanisms or be transported along them by animals or humans. For this reason, 

roads are primary vectors for the spread of invasive species. 

There are several other pathways for introduction of invasive plants that are indirectly related 

to roads. Recreational use includes a number of activities that can negatively affect the 

integrity of native plant communities. OHV recreation can create soil disturbance and can be 

an effective means of invasive plant distribution. Use of road systems by horseback riders, 

pack animal users, hikers, and backpackers can also aid in creating soil disturbances and 

spreading invasive plants. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Studies have shown that motor vehicles can pick up and move invasive species seeds and that 

these seeds will germinate. Schmidt (1989) systematically sampled a car driving over 15,000 

kilometers during the growing season. He found 124 species of which he grew a total of 

3,926 seedlings. The majority of these were small seeds that tended to persist (remain viable). 

Though most were associated with roadside disturbed communities, a good portion also came 

from open grasslands, forest edges and woodlands, meaning that the motor vehicle was the 

main vector for their movement. 

Hodkinson and Thompson (1997) postulated that the maximum distance dispersed by cars is 

likely to be several orders of magnitude greater than by ‘conventional’ dispersal methods. 

They sampled mud from the undercarriages of cars of 201 cars split between the summer and 

fall seasons. They germinated seeds of 37 species from these deposits and found that the 

majority of seeds were small and persistent. They noted that a great majority of invasive 

species did not possess obvious dispersal adaptations for wind, animals or water and that 

motor vehicles may be used as plausible dispersal mechanisms. 

Livestock Grazing 

Domestic and wild grazing animals can both contribute to plant invasion through: (1) 

selective eating of native plants which means unpreferred invasive species would be left, thus 

favoring an increase in invasive plants; (2) ingesting invasive plant seeds in one area and 

spreading them to other areas through scat, digestive products, skin, fur and hooves, and (3) 

disturbing the soil and creating conditions favorable to invasive plants or the germination of 

invasive plant seed though scarification. 

Several intentional and unintentional introductions of invasive plants into native plant 

communities have been associated with livestock management, and some introductions have 

resulted in widespread invasions (Baker, 1974; Sheley and Petroff, 1999). Landscape spread 

of invasive plants can occur when seeds are moved along transportation corridors from 

infested sites or infested ungulate forage, attached to or held within animals, or attached to 

vehicles used to transport them. Both domestic and wild ungulates spread seeds by these 

means (Janzen, 1984). 

Direct effects of grazing can include plant trampling, disturbance of soil crusts and creation of 

bare soil, and high input rate of nitrogen to the soil by dung and urine; all of which play a role 

in limiting the abundance of palatable species (Augustine and McNaughton, 1998), and 

thereby increasing the “invasibility” of a plant community (Lonsdale, 1999). While 

management activities such as timber harvest provide episodic ground disturbance (i.e., 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

change in forest structure and composition dramatically at a given point in time), ungulate 

grazing and browsing can function as a chronic disturbance, exerting continuous influence 

over long periods (Parks et al., 2003). 

Prescribed grazing, when properly designed and implemented, can also be used as a tool to 

maintain healthy and vigorous vegetation that is capable of resisting invasion (Sheley et al., 

1996). Healthy plant communities can provide resistance to invasion (Sheley et al., 1996; 

Pokorny et al., 2004.) The influence of grazing on plant invasion is complex, the frequency, 

intensity, and season of grazing determine whether this disturbance assists in achieving a 

desired future condition or invites invasion (Heitschmidt and Stuth, 1991). 

Proper grazing can be successfully used to control some invasive plants once they are 

established (Bowes and Thomas 1978; Olson and Wallander, 2001; Olson, et al., 1997). For 

instance, sheep and goats prefer broadleaved weeds over many native species, especially 

grasses (Olson, 1999). Grazing is considered a treatment under the various alternatives in this 

EIS and is described in greater detail in Chapter 3.3.2. 

Table 3-4 displays the number and type of grazing permits and authorized use levels in 

Region Six. HM stands for “head months” and AUM stand for “animal unit months,” both 

measures of animal use. An AUM is the amount of forage needed by an "animal unit" (AU) 

grazing for one month. The animal unit in turn is defined as one mature 1,000 pound cow and 

her suckling calf. It is assumed that such a cow nursing her calf will consume 26 pounds of 

dry matter per day as forage. 

Table 3-4 Annual Grazing Statistical Detail (Grazing Season 2002) 

Region 6 

Authorized to Graze

Cattle Horses Sheep & Goats Total 

Forest Allot 

ments 

Permit 

tees HM AUMs HM AUMs HM AUMs HM AUMs 

Deschutes 26 6 7,205 8,271 7,205 8,271

Fremont 70 50 46,345 60,238 46,345 60,238

Gifford Pinchot 3 4 1,231 1,625 1,231 1,625

Malheur 79 83 71,574 93,938 22 26 4,504 1,351 76,100 95,315

Mt. Hood 6 8 3,924 5,180 3,924 5,180

Ochoco 83 44 30,122 39,761 17,918 5,375 48,010 45,136

Crooked River 

National Grass 

Land 

1 1 16,732 21,509 198 238 16,930 21,747

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 3-4 Annual Grazing Statistical Detail (Grazing Season 2002) 

Region 6 

Authorized to Graze

 Cattle Horses Sheep & Goats Total 

Forest Allot 

ments 

Permit 

tees HM AUMs HM AUMs HM AUMs HM AUMs 

Okanogan 69 53 33,022 42,148 33,022 42,148

Olympic 1 1 0 0 0 0

Rogue 21 16 7,235 9,507 37 44 7,272 9,551

Siskiyou 11 7 465 594 465 594

Siuslaw 2 1 11 15 11 15

Umatilla 45 44 29,214 38,562 13,991 4,197 43,205 42,759

Umpqua 7 4 604 797 604 797

Wallowa-Whitman 142 106 92,792 122,242 647 777 17,070 5,121 110,509 128,140

Wenatchee 39 11 1,992 2,631 10 12 20,623 6,187 22,625 8,830

Willamette 1 0 0 0

Winema 13 10 15,279 20,168 10,830 2,447 26,109 22,615

Colville 59 42 21,660 28,591 21,660 28,591

Columbia River 

Gorge 2 2 453 598 453 598

Total 680 493 379,860 496,375 914 1097 84936 24678 465,680 522,150

Fire and Fuels Management 

The number and intensity of wildland fires in the United States is increasing. The relationship 

between fire and exotic plant invasions is well known and continues to be explored 

(D’Antonio and Vitousek, 1992). After a fire, a site is often more susceptible to exotic plant 

invasions (Milberg and Lamont, 1995). The most important environmental requirements for 

successful establishment of many invasive plants are increased light, open ground, available 

water, and nutrients. Fire provides these conditions, thus providing an ideal place for invasive 

plants to establish in natural areas (Goodwin and Sheley, 2001; McDaniel et al., 2000; 

Morghan et al., 1999; Ojima et al. 1990; Trabaud, 1990). 

Fire initiates succession in a plant community. Invasive plants are often the pioneer species in 

this process (Koniak, 1985). There are three general types of species found after fire 

occurrences: (1) annuals or biennials that invade the area immediately after the fire and 

disappear with fire exclusion, (2) truly invasive species that persist once established, and (3) 

species that increase with fire (Trabaud, 1991). Pioneer species that inhabit a site for only a 

short period of time after fire are not as much of a concern as some other more persistent 

species, such as cheat grass (Bromus tectorum) (Keeley and Keeley, 1984). Plant community 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

succession can be impacted by the colonization of invasive plants that follow a fire (Sheley et 

al., 1996). 

Native plants are often at a disadvantage after an uncharacteristically severe fire. As fire 

severity increases, native survivorship declines, and invasion potential increases (Goodwin et 

al., 2002). Fires that are more severe reduce litter more completely, increase nutrient 

availability and turnover, and alter soil surface characteristics. Native species that are adapted 

to cooler fires cannot survive (Brooks, 2002). When invasive annual grasses reduce the fire 

return interval, woody plants, and many perennial grasses are unable to reestablish. 

The use of straw or mulch is common during wildland fire rehabilitation, when bare soil is 

covered to protect it from erosion or when re-seeded areas need protection from the elements. 

The use of non-native straw has led to the spread of non-native species, which has been 

documented through personal observation on the Biscuit Fire in Siskiyou National Forest 

(Hutchinson personal communication, 2004). 

Fuels management such as thinning, slash-busting/chipping, pile burning, and broadcast 

burning, while vital to reducing the intensity and threat of wildfire around communities will 

also provide new avenues of invasive plant introduction and spread. Ground disturbance from

heavy equipment related to thinning and brush cutting, as well as the creation of openings 

where the microsite has been changed from moister to drier conditions, will promote invasion. 

Movement of equipment, crews, and vehicles from infested to un-infested areas will 

contribute as well. Hand pile burning could create soils open to pioneer species, including 

invasive plants. Broadcast burning could in some cases reduce some species of invasive 

plants, but in other species could increase growth and competitive advantage. (Galley and 

Wilson, 2001). 

The National Fire Plan has resulted in significant increases in fuel reduction projects, greatly 

increasing the potential for introduction, establishment and spread of invasive plants within 

the Region. 

Fire can also be a tool in invasive plant management. It has been used in combination with 

other methods, serving to reduce biomass or weaken plants for subsequent herbicide 

treatments. Its effectiveness is usually limited to the above ground portions of plants. 

Although, its use has been limited in Region Six, it is considered as a treatment under the 

various alternatives in the EIS. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Recreation and Recreation Management 

The Forest Service is the largest provider of outdoor recreation opportunities in the country 

and in the Pacific Northwest. Recreational activities are influenced by, and have influence on, 

the rate and degree of invasive plant spread. National Forest System land in Region Six 

provide outdoor recreational opportunities of local, regional, national, and international 

importance. People can enjoy highly valued settings while participating in a variety of active 

or passive recreational activities such as hiking, camping, picnicking, climbing, boating, horse 

riding and packing, skiing, bicycling, OHV riding, hunting, fishing, wildlife viewing, 

ecotourism, and automobile touring. These and other recreational pursuits can promote the 

spread of invasive plant seeds and propagating plant parts. Recreational activities also have 

the potential to create ground disturbances that favor invasive plants. 

A recent study by the Oregon Parks and Recreation Department (2003) found that between 

1987 and 2002 the greatest percent increase in outdoor recreation in Oregon was in “nature 

study activities such as nature/wildlife observation” (+170 percent). Other activities with 

noteworthy growth include non-motorized boating (137.9 percent), snowmobiling (97.2 

percent), hunting (birds and small game, 30.1 percent; big game rifle, 69.5 percent; big game 

bow, 124 percent), RV/trailer camping (95.5 percent), fishing from a boat (44.3 percent), and 

ATV (3 and 4 wheeler) riding (38.4 percent). Activities (of relevance to national forest lands) 

with declining participation include horseback camping (-38.5 percent), dune buggy driving (-

32.7 percent), and horseback riding (-31.5 percent). 

The Region is home to 13 percent (24.8 million acres) of the nation’s National Forest System 

land (Burchfield et al., date unknown). Nineteen percent (4.6 million acres in 59 separate 

Wilderness areas) of the Region’s Forest land is designated Wilderness, comprising 13 

percent of the nations total Wilderness acreage (See Figure 3-1). The Region’s 1,179 miles of 

Wild and Scenic Rivers comprise 27 percent of the nation’s total. There are 3.5 million acres 

of inventoried roadless areas in the Region (areas outside of designated wilderness that do not 

contain roads), encompassing 14 percent of the Region’s National Forest land. About 13 

percent (17,149 miles) of all National Forest recreation trails are located in the Region, with 

6,510 miles of trail within designated Wilderness. There are 538 National Forest 

campgrounds in the Region, comprising 12 percent of the nation’s total. 

Invasive plants can detract from the desirability of using recreation sites and participating in 

certain recreational activities. For example, stiff plant stalks, thorns, sharp bristles, and 

allergies created by invasive plants can prevent humans from walking, sitting, setting up 

camp, and finding a place to fish or tie up a raft. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Many invasive plants most successfully propagate in recently disturbed areas, and recreational 

activities can, to varying degrees, create such disturbances. Heavy use areas such as 

trailheads, parking lots and riparian zones are easily denuded of their native vegetation, 

creating prime environment for invasive plants. Recreation users can also unknowingly 

spread invasive plant seeds and propagating parts across and between landscapes. With the 

most likely vectors of spread being roads, trails and riparian corridors. 

In this document, OHV refers to vehicles used for off-highway pursuits and may include 3 

and 4 wheelers, motorcycles, dune buggies, 4 x 4 vehicles, and others. OHV users (like other 

recreation users) are diverse in their activities, desired settings and trail types, and motivations 

for participation. OHV use remains a legitimate use of National Forest System lands, and the 

provision of high-quality motorized opportunities and balanced environmental impacts are 

among the agencies current goals (USDA Forest Service, 2000-Recreation). However, OHV 

use, compatibility, and management on National Forest lands is an issue requiring urgent 

attention for numerous reasons. OHV ownership and use is gaining in popularity. It was 

reported at the 2003 National OHV Managers Meeting that between 1997 and 2002 OHV 

sales increased in the western United States by 171 percent (Oregon Off Highway Vehicle 

Association, 2004). More OHV permits (9,178) were sold in Oregon in May 2003 than any 

other month ever (Oregon Parks and Recreation Department data, 2003). Oregon sold a total 

of 58,040 OHV permits in 2002, and Washington data shows that about 61,000 OHVs are 

currently owned in that state (Herbert Research Inc., 2003). About 72 percent of OHV 

recreationists ride on publicly owned lands (Oregon Off Highway Vehicle Association, 2004). 

The potential for OHVs to spread invasive plants has been tracked by studies in Montana, 

West Virginia, and Wisconsin; in each case, OHVs where shown to be effective vectors of 

invasive plant transport and dispersal (Lacey et al 1997; Stout, 1992; Rooney (pending 

publication)). OHVs allow recreationists to travel across many more miles in a given time 

than with non-motorized modes of transportation, greatly expanding the activities ability to 

spread invasive plants from one location to another. Also, OHV use, especially “crosscountry” (away from roads or designated trails) use, can create new soil and seedbed 

disturbances that can negatively affect the integrity of native plant communities and can favor 

establishment of invasive plants (Kimberling et al., 2003). 

Many people value National Forests as places where they can camp and travel using horses, 

mules, llamas, and other pack animals. Unfortunately, invasive plants can find their way onto 

National Forest lands in weed infested feed brought along for pack animals. These seeds are 

often deposited near disturbed areas such as trailheads, trails, watering holes, roads, horse 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

camps, and other disturbed areas where invasive plants are best suited to grow. Invasive plant 

seeds can also be spread in the manure of pack animals. 

One way for users of domestic animals to avoid spreading seeds is though the use of 

pelletized (processed) feed or feed that is certified to be weed and weed seed free by the State 

or organizations such as the North American Weed Management Association (NAWMA). 

Region Six is bordered in the United States by Idaho, Nevada, and California. Regional 

Forest Service direction in Idaho and Nevada requires that only certified weed free seed by 

used on all National Forest System lands in these States. 27 California is currently working on 

a certification program and similar requirements for National Forest System lands. Wallowa 

County Oregon has a working NAWMA certification program28 and the nearby Eagle Cap 

Ranger District and Hells Canyon National Recreation Area prohibit use of uncertified weed 

free feed. NAWMA certification is currently available in the three states that share borders 

with Region Six, as well as 9 other western states. Unfortunately, Oregon and Washington do 

not currently have state-wide certification programs in place. However, certified weed-free or 

pelletized feed is currently required on about 2.5 million acres of Nation Forest System land 

in Region Six (mostly in wildlerness and other specially designated areas; see discussion of 

Congressionally Designated Area in this Chapter for Specific closures). 

While OHVs and pack animal feed are clear modes of ground disturbance and/or invasive 

plant seed transport, other vectors also exist; including humans participating in a range of 

dispersed and concentrated recreational activities. People (and their pets) participating in 

recreational pursuits can unknowingly spread invasive plant seeds or propagating plant parts. 

Seeds stick to gear, clothing, hair, and other objects and are then easily transported and 

deposited. 

Scenery is among the most important amenity values provided by the Forests in Region Six 

(Quigley and Arbelbide, 1997). Humans are very sight oriented beings and visual quality is 

an important component of the recreation experience. Visual impacts of invasive plant 

populations are experienced primarily at the immediate foreground and middle ground rather 

than at the background level or at a “horizon” scale. Many recreational activities bring people 

into close physical contact with their immediate surroundings, where such amplified 

 

27 Intermountain Region’s Closure Order Number 04-00-097, states that “Possessing, storing, or transporting, 

non-pelletized hay, straw or mulch on National Forest System Lands without having each individual bale or 

container tagged or marked as weed free, or having original and current evidence of weed free certification 

documentation present. All markings must meet the State and/or County standards for certification as weed 

free.” 

28 Wallowa County Haygrowers Association has more information on details of a certification program 

working in Oregon (www.certifiedwallowacountyhay.com). 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

foreground and middle ground visual impacts are likely to be experienced. Since many 

recreational activities involve movement across landscapes, recreation participants are likely 

to experience increased exposure to invasive plant populations as they travel across the 

recreational landscape. Invasive plants can reduce the diversity of the types, forms, and colors 

of plants in an area, and also the experiences that those plants provide. The historic range of 

variability in landscape flora is also of value to many people. People who are unaware they 

are looking at invasive plants (unaware of their negative relationship to the ecosystem and 

potential economic effects) may find them to be attractive components of the landscape. They 

may even unintentionally spread seeds by gathering and transporting invasive plants to be 

visually enjoyed or studied elsewhere. Invasive plants also degrade the recreation experience 

by reducing and competing with the variety and amount of native flora available for 

observation or study. 

Minerals and Mining 

Minerals prospecting and exploration, and mining operations may be lead to conditions 

favorable to invasive plants. Typical surface disturbing activities include access road 

construction or reconstruction, excavating, clearing of vegetation and soil to facilitate mining 

operations, and to create drill pads, and reclamation of disturbed areas. Such surface 

disturbance and reclamation activities often create environments in which invasive plant 

species out-compete and overrun native plant communities. 

3.2 Influence of Invasive Plants on Ecosystem Components 

This section addresses the influence of invasive plants on specific components of the 

ecosystem. Each resource is discussed separately after the following introductory paragraphs 

beginning with the physical environment. Discussions include not only an affected 

environment description, but also information on how invasive plants affect each resource. 

Invasive plants can compromise healthy, native ecosystems if they persist and/or increase in 

abundance over time. Once established, they can be self-perpetuating, and can spread from 

site to site, often without human assistance (Randall, 1996). The impact of invasion can be 

permanent when economic and environmental factors limit the ability of a managing agency 

to restore the ecosystem to a healthy state (National Academy of Sciences, 2002). Invasive 

plants have already caused permanent damage to public lands across the western United 

States (Asher and Surrier, 1998). 

Human activities during the last 100 years have resulted in non-native species are invading 

continents at an increasing rate (Leibhold et al., 1995). These human-induced biological 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

invasions are occurring on a global scale, and are beginning to blur the regional 

distinctiveness of the Earth’s biota (Westbrooks, 1998). Escalating human population growth 

and improved transcontinental transport are the primary factors behind this increasing rate and 

scale of movement (Ewel et al., 1999). 

Invasive plants have cascading effects on ecosystems, and affect significant chemical, 

physical and biological components and processes (e.g. nutrient cycling, erosion, species 

competition). Currently, the following effects (Table 3-5) of invasive plants on native plant 

and animal species are known; these effects may act cumulatively and/or synergistically to 

disrupt extant ecological relationships. 

Table 3-5 Known Effects of Invasive Plants on Ecosystems 

Habitat change resulting from invasive plants 

• Alter forage quality 

• Decrease favored or nutritionally preferred food 

• Lack of use of favored forage may affect plants previously evolutionarily favored, and affect 

mutualistic relationship 

• Disrupt herbivore/plant ecological relationships 

• Disrupt insect composition and plant relationships (e.g. butterfly/bee/pollinator/plant relationships, with 

cascading effects to other pollinator/plants.) 

• Disrupt mychorrhizal fungi through plant changes; in turn, this may affect long-term habitat 

components pertaining to structure and function of vegetation 

• Alter fire behavior; which can affect fire intensity, duration, and frequency 

• Alter soil stability through loss of plant cover, debris, and detritus 

• Change in local ecology of keystone plant species that has cascading effects on plant and wildlife 

composition and habitat use (e.g. beach grass, Japanese knotweed) 

• Change in soil ph and chemistry 

• Change in soil biota 

• Habitat fragmentation and increased edge effect 

Other effects of invasive plants 

• Impact to ecosystems already undergoing climatic change 

• Direct and indirect changes in water availability and moisture regimes 

• Loss of biological diversity, ecological integrity, and ecosystem structure/function 

• Reduced population of native species with local extinctions and extirpations 

3.2.1 Soils 

Productive soil is fundamental to healthy, functional ecosystems and is dependent on a 

thriving subsurface ecosystem adapted to geology, hydrology, climate, and surface ecology. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Region Six includes a wide variety of soils, from shallow or deep; very young or ancient and 

well-developed; based on sedimentary, igneous, or metamorphic geology; and contain 

virtually no organic matter or covered with thick organic layers. Topography and climate 

within the Region is similarly diverse, ranging from steep to gently rolling; from sea level to 

over 10,000 feet in elevation; and annual precipitation from less than 20 inches per year to 

more than 100 inches per year. 

Land management activities such as road construction and maintenance, grazing, logging, 

burning (either prescribed or wildfire) and trail construction, can affect soil productivity by 

compaction or displacement of soil. Management impacts to soil productivity in the Region 

vary considerably, based on the intensity and sensitivity of the activities conducted. FSM 

2550 and FSH 2509.18, along with individual forest plans and region-wide forest plan 

amendments (e.g. the Northwest Forest Plan, Pacfish and Infish) provide varying degrees of 

guidance on protecting soil productivity in the Region. FSH 2509.18 (Chapter 2.2.1) 

recommends 15 percent reduction of soil productive capacity (soil productivity) as a guideline 

for determining when change becomes detrimental or significant. Individual forest plans may 

determine detrimental or significant change in soil productivity at a lower proportion. 

Invasive plants can have dramatic and irreversible effects on soil productivity due to changes 

in soil characteristics such as nutrient and water availability, organic matter in the soil, 

diversity and abundance of soil biota, and soil water holding capacity. Invasive plants can 

also increase the soil surface exposed to wind or water erosion, change fire frequency and 

frequency, and produce toxic chemicals that affect soil organisms. Some of these changes 

may be difficult to reverse and can result in difficulty in reestablishing native vegetation. In a 

few instances, invasive plants can positively affect soil through enrichment of certain 

nutrients and erosion control. Some examples of invasive plant effects on soil productivity 

follow. 

Lacey et al. (1989) found that rangelands infested with spotted knapweed had more bare 

ground than natural bunchgrass/forb grasslands. In a simulated rainfall test, they found that 

soil erosion more than doubled in knapweed-dominated areas compared to uninfested areas. 

Even modest losses of the soil surface can have large impacts on soil productivity, since most 

of the biologically active organic matter is concentrated in the top 1 to 4 inches of soil. Soil 

erosion also has negative impacts on water quality in associated aquatic systems. Lacey et 

al.(1989) additionally found significantly lower infiltration rates in the knapweed sites. 

Reduction of infiltration decreases groundwater recharge. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Tyser (1992) also observed low canopy cover of native forbs and low biological soil crust 

cover in stands invaded by spotted knapweed. He also found lower grass cover in stands 

invaded by common timothy. Low canopy cover can decrease soil moisture content, since 

more rain runs off as surface flow, and soil is directly exposed to solar radiation and dries 

rapidly. A dry soil surface hinders seedling establishment and will negatively impact plants 

with surface root systems, such as many native grasses. Exposure of the soil surface causes 

soil temperatures to be more extreme, due to solar heating during the day and greater 

irradiative cooling at night. These extreme temperatures make seedling establishment more 

difficult and may affect soil organisms (Sheley and Petroff, 1999). 

One function of soil is cycling nutrients from dead organic matter into forms that are available 

to plants. Nutrient cycling is essential for the health and productivity of the ecosystem, and is 

a complex process that depends on a multi-level food web that is specific to the site. Biota 

involved in nutrient cycling includes bacteria, actinomycetes, fungi (pathogenic, saprobic, and 

mycorrhizal), amoebas, and a wide range of invertebrates. Since this entire system is powered 

by root exudates and decomposing vegetation from the plant community, changes in plant 

communities caused by non-native invasion can have large effects on the soil food web 

(Hobbie, 1992; Van der Putten, 1997). 

A study that compared soil organisms in native grasslands in a natural state and after invasion 

by cheatgrass (Bromus tectorum), found that the cheatgrass caused changes in most levels of 

the soil food web (Belnap and Phillips, 2001). Although it is difficult to predict the specific 

effects of these changes, it is important to recognize that any change in the soil food web has 

the potential to interfere with critical nutrient cycling processes, and to threaten the long-term 

integrity of the ecosystem. For example, some reforestation failures in the Siskiyou 

Mountains have been attributed to a shift from soil biota high in fungal biomass, to a biota 

dominated by bacteria and actinomycetes due to management activities (Friedman, et al., 

1989). Reforestation of these clear cuts has failed after 4 or 5 attempts over 30 years (Perry, 

1994). 

A study found pronounced differences in soil properties when soil under non-native 

understory plants was compared to soil under native shrubs (Ehrenfeld, et al., 2001). Soil pH 

was significantly higher under the non-native plants, as was extractable nitrate. Net nitrogen 

mineralization was also higher under the non-native plants, indicating changes in the 

composition or activity of soil microbes caused by non-native plants. Over time, these 

changes may have effects on the ecosystem as a whole. Many invasive plants establish more 

readily on sites with high nutrient availability. Invasive plants that increase the availability of 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

nitrate in the soil may be promoting conditions that favor their own expansion at the expense 

of native plants that tolerate low nutrient levels. Increases in soil nutrient levels have been 

shown to favor the invasion and success of non-native species in a serpentine soil ecosystem 

where resources were limited (Huenneke, et al., 1990). 

On the other hand, many invasive species deplete soil nutrients. Spotted knapweed has been 

implicated in reducing available potassium and nitrogen (Harvey and Nowierski, 1989). A 

reduction in soil nutrient levels makes it difficult for native plants to compete with the 

invasive plants, and probably affects the soil biotic community. The long-term effects of 

these changes are not known. 

Some invasive plants produce secondary compounds that affect other plants (allelopathy) or 

soil organisms (Sheley and Petroff, 1999). If an invasive plant produces a secondary 

compound, the population of soil microbes that can metabolize this compound will increase, 

while the populations of other microbes will decrease (Sheley and Petroff, 1999). Again, 

these changes will affect the soil food web and nutrient cycling, impacting native plant 

communities. 

One group of soil organisms that is of particular concern is mycorrhizal fungi. These fungi 

form a mutualistic relationship with plants in nearly all ecosystems and are critical in 

supplying water and nutrients to plants, as well as protection from root pathogens. 

Mycorrhizal fungi also play an important role in creating soil structure, particularly in young 

or poorly developed soils. Mycorrhizal fungi can produce up to 200 meters of hyphae per 

gram of forest soil. This mass of hyphae binds soil particles together, stabilizing the soil 

system. Mycorrhizal fungi also produce polysaccharides that bind soil particles into 

aggregates. These aggregates increase the water holding capacity of the soil, improve oxygen 

penetration into the soil, and provide small sites for the normal development of communities 

of bacteria, actinomycetes, and amoebas. Mycorrhizal fungi appear to mediate the transfer of 

sugars and nutrients from one plant to another. This function may be important in 

maintaining diversity in the plant community, and in the recovery of the plant community 

after disturbance. The fruiting bodies produced by some mycorrhizal fungi are an important 

food source for a variety of animals, from invertebrates to large mammals. More than 70 

percent of the diet of some small mammals, including the northern flying squirrel, consists of 

fruiting bodies of mycorrhizal fungi. 

Research on the impact of invasive plants on mycorrhizal fungi is lacking, but since plants 

and mycorrhizal fungi are strongly dependent on each other, it seems likely that drastic 

changes in the plant community caused by the invasion of non-natives will be accompanied 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

by changes in the mycorrhizal fungus community. Sylvia and Jarstfer (1997) compared the 

mycorrhizal status of young slash pines (Pinus elliottii var. elliottii) in plots with weeds and 

plots that were kept weed free with herbicide treatment. After 3 years, the number of pine 

root tips colonized by mycorrhizal fungi was 75 percent lower in the weedy plots than the 

weed free plots. In addition, the species distribution of the mycorrhizal fungi associated with 

the trees had changed. 

In the Sylvia and Jarstfer study, the invasive plants were associated with different fungi than 

the trees. It is likely that competition from these introduced fungi, caused the decrease in the 

fungi associated with the trees. If mycorrhizal fungi associated with invasive plants 

successfully compete with native fungi, a redistribution of soil resources in favor of the 

invasive plant will occur. In addition, species of mycorrhizal fungi associated with native 

plants may be lost from the area of infestation. It may then be difficult to reestablish native 

vegetation on the site after the invasive plants are removed. 

Researchers have found that specific “helper” bacteria in the soil promote the establishment of 

mycorrhizae, and mycelial growth of mycorrhizal fungi (Garbaye and Bowen, 1989). 

Although little is known about the ecological requirements of these organisms, it is possible 

invasive plants do not support helper bacteria employed by native plants and fungi. 

Without treatment, invasive plants are likely to cause significant changes to the physical, 

chemical, and biological properties of soils. In some cases it may be difficult to reverse these 

changes and restore soil productivity. This legacy of disrupted soil function may increase the 

effort required to restore native vegetation long after invasive plants are removed. 

3.2.2 Water Quality 

National Forest watersheds provide drinking water to nearly 300 public water supply systems 

serving up to 2.9 million people in Oregon and Washington. Many others use smaller systems 

tapping water produced from National Forest lands for domestic use or irrigation. Rivers, 

streams and lakes within or downstream of the planning area are used for swimming, fishing, 

boating, and water sports. Additionally, National Forest streams provide habitat and clean 

water for fish and other aquatic biota, each with specific water quality requirements. The 

Clean Water Act protects water quality for all of these uses. 

The Clean Water Act requires States to set water quality standards to support water use within 

and downstream of planning areas. The Act requires States to identify the status of all waters 

and prioritize water bodies whose water quality is limited or impaired. The EPA approves 

both water quality standards and lists of water quality limited waters. Oregon Department of 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Environmental Quality, Washington Department of Ecology, Idaho Department of 

Environmental Quality, and California State Water Resources Control Board web-sites list 

water quality limited waters and water quality standards. 

By direction of the Clean Water Act, where water quality is limited, States develop plans to 

improve water quality to meet State water quality standards, and support beneficial uses of 

water. For water quality limited streams on national forest lands, the Forest Service provides 

information, analysis, and site-specific planning efforts to support state processes to protect 

and restore water quality. For streams on National Forest lands that meet or exceed water 

quality standards, anti-degradation rules in each State are supported by implementation of best 

management practices and management measures. The Northwest Forest Plan, Pacfish and 

Infish, all include management measures and best management practices designed to protect 

and improve water quality. In the past ten years, passive and active restoration of riparian 

processes and water quality has been conducted under these plans with subsequent water 

quality improvement. 

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Willamette

National Forest

Deschutes

National Forest

Wenatchee

National Forest

Okanogan

National

Forest

Gifford Pinchot

National Forest

Mt. Hood

National Forest

Siskiyou

National Forest

Fremont

National Forest

Umpqua

National

Forest

Mt. BakerSnoqualmie

National Forest

Malheur

National Forest

Colville

National Forest

Winema

National

Forest

Wallowa Whitman

National Forest

Umatilla

National Forest

Rogue River

National

Forest

Ochoco

National Forest

Siuslaw

National Forest

Olympic

National Forest

Columbia River Gorge

National Scenic Area

CALIFORNIA

No warranty is made by the US Forest Service as to the 

accuracy, reliability, or completeness of these data for 

individual or aggregate use with other data. Original data 

were compiled from various sources. This information may 

not meet National Map Accuracy Standards. This product 

was developed through digital means and may be updated 

without notification.

P a c i f i c 

O c e a n

NEVADA

WASHINGTON

IDAHO

0 20 40 80 120Miles

0 30 60 120 180

Kilometers

Figure 3-3 Occurrence of Listed Water Quality Limited Water Bodies

OREGON

CANADA

Albers Equal Area Projection centered on 120 degrees 30 minutes west

Standard parallels: 43 degrees 10 minutes north and 50 minutes north.

Invasive Plants EIS Project

USDA Forest Service

PO Box 3623

Portland, OR 97208

Legend

Temperature (OR,WA)

Dissolved Oxygen (OR,WA)

Turbidity/Fine Sedimentation (OR,WA)

Fish Habitat (WA)

Sedimentation (OR)

Biological Criteria (OR)
Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Invasive plants can create or exacerbate conditions that reduce water quality. Directly or 

indirectly, invasive plants can affect stream bank stability, sediment, turbidity, shade and 

stream temperature, dissolved oxygen, and pH. Once water quality is degraded, invasive 

plants can complicate or prevent water quality restoration. Invasive plants can also reduce 

water quantity. For instance, tamarisk (Tamarix spp.) and giant reed (Arundo donax) can 

alter stream form and use more water than native streamside plants, which can reduce, or even 

eliminate, the availability of surface water. 

Every National Forest within the Region has water bodies that are water quality limited, 

though not all limiting parameters are related to invasive plants. On National Forest System 

lands in Oregon and Washington, the most common water quality limiting parameter is 

elevated summer stream temperatures. In Washington State, invasive plants affect fish 

habitat, fine sediment, and dissolved oxygen water quality parameters; while in Oregon, 

sedimentation, turbidity, dissolved oxygen, and biological criteria (quantities and diversity of 

aquatic invertebrate species) are affected by invasive plants. Sediment is the most common 

water quality limiting parameter in California and Idaho. See Figure 3-3. 

Roots of riparian vegetation help prevent erosion, provide slope and stream bank stability, and 

reduce suspended sediment (FEMAT, 1993). Lacey et al. (1989) reported runoff and 

sediment yield were higher on sites dominated by spotted knapweed than on sites dominated 

by native bunchgrasses in a Montana study. Suspended sediment complicates treatment of 

water for human use and consumption, and can render water unsuitable for recreational 

activities. 

Invasive plants that form a monoculture in riparian areas can deposit large amounts of organic 

matter into streams over a short time. In contrast, diverse riparian communities deposit 

varying quantities and kinds of organic matter over a longer time period. Sudden introduction 

of large amounts of organic matter can influence pH by increasing the concentration of 

organic acids; increase biological oxygen demand, reducing the available oxygen for stream 

biota; and increase dissolved carbon dioxide due to respiration (Peters et al., 1976). 

3.2.3 Riparian 

Riparian vegetation plays a key role in forming aquatic habitat for fish and other aquatic 

species. Roots help hold stream banks, preventing accelerated bank erosion and providing for 

the formation of undercut banks, important cover for juvenile and adult fish. Riparian areas 

supply downed trees (large wood) to streams. In turn, downed trees in streams influence 

channel morphology characteristics such as longitudinal profile; pool size, depth, and 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

frequency; channel pattern; and channel geometry. Turbulence created by large wood 

increases dissolved oxygen in the water for use by fish, invertebrates and other biota. Large 

wood in streams creates complex aquatic habitat, provides cover from predators, acts as a 

substrate for biological activity, while it stores sediment and organic matter, slowing their 

movement in streams and providing substrate for fish and invertebrates (FEMAT, 1993). The 

extent of the hyporheic zone adjacent to and under the stream surface is increased by large 

wood in streams. Hyporheic zone influence on temperature, nutrients, and productivity is a 

topic of emerging understanding (Wordzell, personal communication, 2003; Fausch et al., 

2002). Additionally, riparian vegetation is an important energy source for aquatic 

ecosystems, providing leaf and other particulate organic matter to the food-web (FEMAT, 

1993). Invasive plants can prevent the establishment of native trees, decreasing or delaying 

the future supply of large wood in channels. 

Riparian forest canopy protects streams from solar radiation in summer, and can moderate 

minimum winter nighttime temperature, preventing the incidence of anchor ice or freeze-up in 

streams (Beschta, et al., 1987). Changes in water temperature regime can affect the survival 

and vigor of fish, and affect interspecies interactions (FEMAT, 1993). 

In Region Six inventoried gross weed-infested acres range from 0 percent to 47.5 percent 

within any single subbasin (Subbasin Report of Inventoried Invasive Plants Near Water 

Compared to Uplands, 2003). Estimating invasive plant infestation in riparian areas, 36,000 

inventoried acres of invasive plants are within 300 feet of water, representing 12 percent of 

land in the Region within 300 feet of water. However, inventories are incomplete in many 

subbasins and area within 300 feet of water may not include many small streams, so these 

numbers are approximate. 

Riparian areas are dynamic. Disturbances characteristic of uplands such as fire and 

windthrow, as well as disturbances associated with streams, such as channel migration, 

floods, sediment deposition by floods and debris flows, shape riparian areas (FEMAT, 1993). 

Frequently disturbed ground in riparian areas makes them especially vulnerable to plant 

invasion. The dynamic nature of riparian communities has produced unique adaptations in 

some riparian species. For example, many riparian hardwood species either require, or at 

least regenerate better on, disturbed or open ground (Winward, 2000). Seedlings of these 

species are often poor competitors in dense vegetation. This adaptation limits the ability of 

these species to compete with riparian invaders such as reed canary grass (Phalaris 

arundinacea) and purple loosestrife (Lythrum salicaria). These invasive plants are uniquely 

adapted to riparian habitat and once established can quickly dominate the landscape. Invasive 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

plants such as purple loosestrife can replace or suppress native vegetation in wetlands (Mullin 

et al., 2000; Duncan, 1997). Purple loosestrife crowds out native plants such as cattails and 

bulrush, provides neither food nor shelter for most wetland wildlife, occludes channels, 

increasing sediment deposition and decreasing channel capacity (Donaldson, 1997). 

The rapid growth of many invasive plants allows them to out-compete native vegetation. This 

competitive advantage results in the loss of functional riparian communities, loss of rooting 

strength and protection against erosion, decreasing slope stability and increasing sediment 

introduction to streams, and impacts on water quality (Donaldson, 1997). Invasive plants are 

especially difficult to control in riparian areas since weeds thrive in the moist environment 

and treatment measures are limited. 

Japanese knotweed is an example of an invasive plant with wide-ranging effects to riparian 

areas. Japanese knotweed leaves fall off in a short period in the fall, leaving soil beneath 

knotweed relatively unprotected from rain, leading to increased erosion and sediment delivery 

to streams. Leaves decomposing in streams could locally increase the biological oxygen 

demand and deplete dissolved oxygen for other organisms in the stream. Chemical 

characteristics such as pH can be affected by large, sudden inputs of organic material 

(MacDonald, et al., 1991). While these effects may be local or mitigated by dilution or 

turbulence, the potential for negative effects to aquatic ecosystems is plausible. 

3.2.4 Aquatics 

Fish are an important cultural, economic and recreational resource on the National Forests in 

Region 6. Declining populations of fish have been a management concern. The Northwest 

Forest Plan, Pacfish and Infish forest plan amendments responded to concern for the 

continued existence of a number of species. A number of species have special management 

status as endangered, threatened, or proposed under the ESA, or sensitive species identified 

by the Regional Forester. 

The Magnuson-Stevens Fishery Conservation Act requires the identification of habitat 

“essential” to conserve and enhance federal fishery resources that are commercially fished. 

Essential Fish Habitat (EFH) is defined as those waters and substrate necessary to fish for 

spawning, breeding, feeding, or growth to maturity (50 CFR 600.10). EFH is located on 

portions of fifteen National Forests and one Scenic Area. EFH for chinook, coho and Puget 

Sound pink salmon includes all streams, lakes, ponds, wetlands tributaries and other water 

bodies currently viable and most of the habitat historically accessible to these fish (Pacific 

Fishery Management Council, 2004). 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Due to the topographical, geological, vegetative, and climatic variation across the project 

area, considerable variation in aquatic systems also exists. Four general settings for aquatic 

systems are present on National Forest System lands within the project area: those occurring 

in the coast range mountains, Cascade Mountains, eastside range lands (National Grasslands), 

and east side mountains (Blue Mountains and Entiat Area). (See Figure 3-3). 

Coast range river systems are relatively short systems, with a high drainage density, and flow 

directly into the Pacific Ocean. Annual precipitation levels are high, with frequent high water 

events occurring throughout fall, winter, and spring seasons. Summer flows are provided by 

subsurface storage and thunderstorm events. Native fish species typically present include 

sculpin (cottidae sp.), coastal cutthroat trout (Oncorhynchus clarki clarki), coho salmon 

(Oncorhynchus kisutch), chinook salmon (Oncorhynchus tshawytscha), chum salmon 

(Oncorhynchus keta), rainbow trout and steelhead (Oncorhynchus mykiss), lamprey 

(Lampetra spp.), and a few minnow (Cyprinidae) and sucker (Catostomidae) species. As in 

all stream systems throughout the region, complex life history assemblages are often present 

for salmonid and lamprey species, including resident, fluvial, and anadromous life history 

strategies. Juvenile anadromous salmonids rear in fresh water for a few months to more than 

two years, depending on species and adult migration timing. Non-native species sometimes 

present include striped bass (Morone saxalis), smallmouth bass (Micropterus dolomieui), and 

American shad (Alosa sapidissima). Coastal aquatic food chains are generally more detritus 

based than inland systems. 

Cascade Mountain river systems are generally longer than coast range systems, with a 

moderate to high drainage density, and may drain directly into the Pacific Ocean, or to the 

Willamette or Columbia Rivers. Annual precipitation levels are moderately high, but vary 

considerably, depending on elevation. Summer flows are provided by snowmelt, subsurface 

storage, and thunderstorm events. At higher elevations, above migration barriers, native fish 

species typically present include coastal cutthroat trout, rainbow trout, and dace. Bull trout 

(Salvelinus confluentus) are also present in some locations. Below migration barriers, coho 

salmon, chinook salmon, and steelhead are generally present, and some minnow and sucker 

species occasionally present. Other less common native fish species are also present. Nonnative fish species often include brook trout (Salvelinus fontinalis), and occasionally brown 

trout (Salmo trutta). Food chains are more detritus based at higher elevations, with increasing 

contributions from primary production within the stream occurring at lower elevations. 

Stream systems occurring on rangelands east of the Cascade Mountains are longer river 

systems, have a low drainage density, with the vast majority draining into the Columbia River 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

and a few draining into the Klamath River. The climate is generally arid, and annual runoff 

patterns tend to be dominated by annual spring snowmelt. Many headwater channels are 

located in isolated mountain ranges. Summer flows are provided by snowmelt, subsurface 

storage, and thunderstorm events. Native fish species are generally rainbow trout, steelhead, 

chinook salmon, bull trout, and several minnow and sucker species. Other less common 

native fish species are also present. Non-native fish species often include smallmouth bass 

and westslope cutthroat trout (Oncorhynchus clarki lewisi). Primary production is important 

to the food chain in these stream systems. 

Eastside mountain streams occur in mountain ranges east of the Cascade Mountains. They are 

generally either the headwaters of eastside rangeland stream systems, or flow directly into the 

Columbia River system. Most precipitation occurs during the winter months as snow, and 

annual runoff generally follows a classic snowmelt pattern. Native fish species are generally 

rainbow trout and steelhead, but chinook salmon, bull trout, and a few minnow and sucker 

species may also be present. Food chains are similar to those found in the Cascade 

Mountains, but may have a higher primary productivity component. 

Invasive plant effects to aquatic ecosystems are indirect and are not fully appreciated. For 

instance, invasive plants that exclude trees decrease shade, increase bank erosion, and reduce 

large woody debris sources. Summer stream temperatures can be increased due to input of 

solar radiation due to lack of tree shade. Fine sediment deposition in spawning gravels can 

reduce survival of fish eggs and juveniles reduce primary production and benthic invertebrate 

abundance, thereby reducing food availability. Severe accelerated sediment delivery can also 

alter habitat by filling pools. Suspended sediment increases turbidity, which can disrupt fish 

feeding and social behavior (FEMAT, 1993). Large wood in streams is important to fish, as 

discussed earlier (Chapter 3.2.3). Invasive plants can complicate and delay restoration of 

stream characteristics that support native fish, decreasing the possibility that degraded 

ecosystems and reduced fish populations can successfully recover from disturbance due to 

management or natural events. One example may help to illuminate this concern. 

The function of headwater streams rely heavily on leaves falling into streams for energy and 

organic matter. Leaves are food for stream detritivores, which consequently provide food for 

other stream organisms. In riparian areas infested by Japanese knotweed, exchanging organic 

matter input from a variety of sources to Japanese knotweed leaves may be problematic for 

detritivores. Stream detritivores may be able to use the knotweed leaves, but it is also 

possible that they are toxic or inedible, though the relationship is unknown. In diverse 

ecosystems, emergence of leaves, flowering, seed set, and shedding of leaves occurs at 

3-39
Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

various times for different species. Timing and nutrient values of a single species is not likely 

to provide food for all native detritivores in and near streams, which in turn can affect other 

organisms in the food chain. If Japanese knotweed excludes trees, important riparian 

functions are affected locally and effects may persist for decades, until trees and other native 

vegetation can be reestablished. 

3.2.5 Native Plants and Plant Communities 

Plant communities can be classified by a variety of factors such as vegetation structure, site 

moisture, overstory and understory. Specific vegetation classification approaches were taken 

for this EIS. The potential vegetation modeling process developed by Forest Service 

Ecologist Jan Henderson was used for Oregon and Washington west of the Cascade crest. 

East of the Cascade Crest, potential vegetation groups developed for the Interior Columbia 

Basin Ecosystem Management Project (ICBEMP, 2000) were used (Hann et al., 1997). 

Terminology

The term potential vegetation type (PVT) is used to represent the combination of species that could occupy the 

site in the absence of disturbance. Potential vegetation differs from existing vegetation in that it represents the 

vegetation that could occupy a site versus the vegetation that actually occupies the site. These vegetation types 

can be further aggregated into potential vegetation groups (PVGs) based on similar moisture or temperature 

environments. In this document we use PVGs to discuss vegetation at the broad scale and examine current 

trends. 

High = high susceptibility to invasion. Invasive plant species invades the cover type successfully and becomes 

dominant or co-dominant even in the absence of intense or frequent disturbance. 

Moderate = moderate susceptibility to invasion. Invasive plant species is a “colonizer’ that invades the cover 

type successfully following high intensity or frequent disturbance that impacts the soil surface or removes the 

normal canopy. 

Low = low susceptibility to invasion. Invasive weed species does not establish because the cover type does not 

provide suitable habitat. 

A major conclusion of the ICBEMP analysis was that, in general, grasslands, riparian areas, 

and relatively dry, open forests are more susceptible to invasion than are dense moist forests, 

high montane areas, and serpentine areas. The former have frequent gaps in the plant cover, 

which favor invasive plant establishment, whereas the latter have relatively closed plant cover 

or have extreme climate or soils, which are tolerated by fewer invasive plant species. The full 

results of this analysis are available in An Assessment of Ecosystem Components in the 

Interior Columbia Basin and Portions of the Klamath and Great Basins, Volume II (Quigley 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

and Arbelbide, 1997). Across Region Six these conclusions may vary. For example, some 

serpentine areas in the Region are experiencing invasion at a greater pace than other 

serpentine areas. 

Table 3-6 and Figure 3-4 provide a summary of potential vegetation groups (PVG) found in 

Region Six, and their susceptibility to damage from invasive plants. The susceptibility of 

plant communities to invasion can be influenced by many factors, including disturbance 

levels, community structure (Orians, 1986), resource availability (Burke and Grime, 1996; 

Elton, 2000; Stohlgren et al., 1999), and the biological traits of the invader (Davis and 

Thompson, 2000). Approximately 51 percent of the Region contains potential vegetation 

groups that are highly susceptible to damage from invasive plants. 

Table 3-6 Potential Vegetation Groups 

Potential 

Vegetation 

Group 

(PVG) 

Description 

Percentage of 

PVG on 

National 

Forests 

Susceptibility 

to Invasion 

Rating 

Agricultural Cropland/hay/pasture less than 1 High 

Alpine Alpine shrub-herbaceous 2.3 Low 

Cold Forest Mountain hemlock, Pacific silver fir, Shasta red fir, 

Subalpine fir, Lodgepole pine (in SW Oregon), 

Western white pine 

26 Low 

Cool Shrub Characterized by mountain big sagebrush and shrubs, 

grasses, forbs, and sedges. Appears east of the 

Cascade crest. It is limited by moisture availability 

due to low rainfall and/or shallow soils. 

1.8 High 

Dry Grass Includes native grasslands, seeded grasslands, and 

cropland hay pasture. Characterized by bunchgrasses. 

Restricted to east of the Cascade crest, and most 

prevalent in the Blue Mountains. 

2.3 High 

Dry Shrub Dominated by sagebrush but bunchgrass/forbs 

present. East of the Cascade crest at lower elevations 

than the Cool Shrub PVG. 

less than 1 High 

Eastside Dry 

Forest 

Douglas-fir, Ponderosa pine, Lodgepole pine 29 Moderate to 

High

Eastside 

Moist Forest 

Vegetation includes transitional areas between drier, 

lower elevation forest, woodland types, and higher 

elevation forest types in cold forests. The dominant 

overstory species found in this group include grand 

fir, Douglas-fir, cedar and hemlock. 

18 Moderate to 

High

Riparian 

Shrub 

Mountain riparian low shrub, saltbrush riparian, 

willow, alder, sedge. The linear nature of the riparian 

corridor makes this PVG highly susceptible to 

invasion. 

less than 1 High 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 3-6 Potential Vegetation Groups 

Potential 

Vegetation 

Group 

(PVG) 

Description 

Percentage of 

PVG on 

National 

Forests 

Susceptibility 

to Invasion 

Rating 

Riparian 

Woodland 

Cottonwood with willow, ponderosa pine, Douglas fir, 

aspen. On many sites, the non-native species have 

become well established, commonly replacing native 

species or exerting large influences on the functional 

dynamics of existing habitats. 

less than 1 High 

Serpentine 

Forest 

Jeffrey pine, Western white pine, Port Orford Cedar less than 1 Low 

Serpentine 

Non-Forest 

Serpentine barrens and fens less than 1 Low 

Westside 

Dry Forest 

Although not described in ICEBMP, this group 

correlates with the Eastside Dry Forest PVG. The 

Douglas-fir and ponderosa pine series are included in 

this group. Douglas-fir, Ponderosa pine, Oregon 

white oak 

2 High 

Westside 

Moist Forest 

White/Grand fir, Tanoak (in SW Oregon) 5.4 Low 

Wet Forest Western hemlock, Sitka spruce 12 Low 

Woodland This group is represented only east of the Cascade 

crest, occurs mostly on forests in the Blue Mountains, 

and is dominated by juniper. These sites generally 

have low water availability due to shallow soils 

less than 1 Moderate to 

High

Total 100% or 

24,836,875 acres 

*Potential vegetation groups in the ICBEMP dataset were mapped at a 1 km resolution grid. Potential 

vegetation zones for the west of the Cascade crest were aggregated to be consistent with ICBEMP data and 

re-sampled to 1 km. Therefore, areas covering less than 1 km, such as small wetlands would not be included 

in the above acreage. 

3-42
CALIFORNIA

No warranty is made by the US Forest Service as to the 

accuracy, reliability, or completeness of these data for 

individual or aggregate use with other data. Original data 

were compiled from various sources. This information may 

not meet National Map Accuracy Standards. This product 

was developed through digital means and may be updated 

without notification.

P a c i f i c 

O c e a n

NEVADA

WASHINGTON

IDAHO

0 20 40 80 120

Miles

0 30 60 120 180

Kilometers

Figure 3-4 Potential Vegetation Groups

OREGON

CANADA

Albers Equal Area Projection centered on 120 degrees 30 minutes west

Standard parallels: 43 degrees 10 minutes north and 50 minutes north.

Invasive Plants EIS Project

USDA Forest Service

PO Box 3623

Portland, OR 97208

Legend

National Forest Boundary

Potential Vegetation Group

Agricultural

Alpine

Cold Forest

Cool Shrub

Dry Grass

Dry Shrub

Eastside Dry Forest

Eastside Moist Forest

Riparian Shrub

Riparian Woodland

Serpentine Forest

Serpentine Non-Forest

Water

Westside Dry Forest

Westside Moist Forest

Wet Forest

Willamette Valley Dry Grass

Woodland
Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

The impacts of invasive plants on native plants occur at multiple levels, including effects on 

individuals, genetics, populations, communities and ecosystem processes (Parker et al., 1999). 

Combinations of impacts at these various levels can result in rapid evolutionary changes in 

the native species (Sakai et al., 2001; Mooney and Cleland, 2001). 

Invasive plants can often impede the germination, growth, and development of native plants. 

They can reduce the vigor of, or eliminate, individual native plants through competition. 

Invasive plants often use more than their share of nutrients, thereby limiting opportunities for 

natives to establish and thrive (Olson, 1999). For some invasive plants, early maturation 

allows them to deplete soil moisture and nutrients before the native plants have the 

opportunity to take full advantage of soil moisture and nutrients (Bonnivier, 1999). Invasive 

plants dominate, in part, by suppressing recruitment of native plant species. This is especially 

true for slow growers and ones with small seeds, which accounts for most of the native flora 

in some areas (Panetta and Hopkins, 1991; Blossey, 1999). Suppression can be accomplished 

in a number of ways. For example, many invasive plants are allelopathic and produce 

chemicals that inhibit the growth of competing vegetation (Stevens, 1986). 

Invasives plants can eliminate native species through hybridization. For example, the North 

American codgrass (Spartina alterniflora), has hybridized with the European variety S. 

maritima to produce a new polyploid species (S. anglica) that is more invasive in Great 

Britain than the original form (Mack et al., 2000; Randall, 1996; Parker et al., 1999). 

All these factors lead to alterations in plant community composition (Mack et al., 2000, 

Randall 1996; Belcher and Wilson, 1989; Rice et al., 1994; Callihan et al., 1994; Tyser and 

Key, 1988). Changes in species composition can lead to such impacts as declines in the 

availability of native plant resources, such as special forest products or species collected by 

American Indian tribes (ICBEMP, 2000). Many tribes in the Pacific Northwest gather and 

harvest plants (Prouty, 1994). Ethnographers have catalogued hundreds of plant species used 

as food, medicine, or for other purposes by native people (Corliss and Keith, no date). 

Examples of native plants that are harvested for food include biscuitroots (Lomatium sp.), 

camas (Camassia quamash), bitterroot (Lewisia rediviva), Indian potato (Claytonia 

lanceolata), and huckleberries (Vaccinium sp.). Other species such as beargrass (Xerophyllum 

tenax) are gathered for ceremony or basketry. 

Invasive species invasions can alter ecosystem processes, slow or alter succession, and deflect 

or halt the normal dynamics of the community (Hobbs and Mooney, 1993; D'Antonio and 

Vitousek 1992; Tyser and Key, 1988). Some researchers have suggested that alteration of 

disturbance regime may be the most profound effect that a species can have on an ecosystem 

3-45
Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

(Mack and D'Antonio, 1998; Bright, 1996). The best regional example of this may be the 

changes to fire frequency and intensity that result from the invasion of cheatgrass (Bromus 

tectorum). This species has been shown to alter historic fire intensity and to create “flash” 

fuels that otherwise would not have contributed to large-scale conflagrations. 

Biological diversity is an indicator of healthy ecosystems, but not an indicator of resistance to 

invasive plants. High species diversity does not necessarily ensure less probability of 

invasion. In fact, diversity hotspots such as the tropics tend to have a higher percentage of 

exotics. Riparian areas which tend to have higher species diversity than uplands are also 

more susceptible (Planty-Tabacchi et al., 1996; DeFerrari and Naiman, 1994). 

Invasive plants threaten ecological diversity at varying scales by potentially changing the 

structure and function of native plant communities. Monocultures are being created where a 

heterogeneous landscape once naturally existed. Ecosystem transformation has been so 

complete due to invaders that the landscape itself is profoundly altered. For example, 

wholesale transformation of the landscape in the Florida Everglades has occurred where 

seasonally flooded marsh has been converted to a fire-prone forest of invasive trees. 

Transformation of Amazon forests through burning and planting of African grasses has meant 

the conversion of diverse communities into a more fire-prone system, where these invasive 

grasses can continue to spread. The reduction in neotropical forests in general means a 

reduction in plant biomass and a build up of carbon dioxide in the atmosphere (Mack et al, 

2000). 

The impacts of invasion should not be misinterpreted to mean that protection of native plant 

communities from non-natives is hopeless. Daehler (2003) reviewed 79 independent nativeinvasive plant comparisons (i.e. studies that compared the performance of natives versus nonnatives under varying environmental conditions). Findings showed invaders were not 

statistically more likely to have higher growth rates, competitive ability or fecundity. Rather, 

the relative performance of invaders and co-occurring natives often depended on growing 

conditions. Such variables as resource availability and altered disturbance regimes associated 

with human activities often differentially increased the performance of invaders over natives. 

Such a conclusion affirms the need to reduce practices that are conducive to spread of 

invasive plants. 

3-46
Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

3.2.6 Wildlife 

Region Six provides diverse habitats, ranging from temperate rain forest to Great Basin 

desert, for a diverse array of wildlife species, including amphibians and reptiles.29 The 

Region is located within the Pacific Flyway, which is a major migratory route for thousands 

of migratory birds. Many species that do not reside in Oregon and Washington may be found 

here during migration. Oregon and Washington include Bird Conservation Regions Five 

(Northern Pacific Forest), Nine (Great Basin), and Ten (Northern Rockies) (USDI FWS, 

2002). Within these regions, National Forests may provide significant habitat for twenty or 

more species listed by the United States Department of Interior Fish and Wildlife Service 

(FWS) as “birds of conservation concern” (USDI FWS, 2002). 

Hunting of game species is a popular activity in the Region and the National Forests provide a 

substantial amount of public land available for this activity. Game species in Region Six 

include elk (Cervus elaphus), black-tailed deer (Odocoileus hemionus columbianus), mule 

deer (O. hemionus), and white-tailed deer (O. virginianus), bighorn sheep (Ovis canadensis), 

mountain goat (Oreamnos americanus), moose (Alces alces), black bear (Ursus americanus), 

cougar (Felis concolor), waterfowl (including coots and many species of ducks, geese, and 

swans), wild turkey (Meleagris gallopavo), common snipe (Gallinago gallinago), and upland 

game birds (grouse, quail, ring-necked pheasant, chukar, partridge, dove, pigeon). Wild 

turkey, chukar, pheasant, and gray partridge are not native to the Region. 

Some wildlife species utilize invasive plants for food or cover. For example, American 

goldfinch (Carduelis tristis), and red-winged blackbird (Agelaius phoeniceus) utilize purple 

loosestrife (Kiviat, 1996; Thompson, Stuckey, and Thompson, 1987), and non-native chukar 

(Alectoris chukar) and native bighorn sheep will utilize cheatgrass (Csuti et al., 1997). It has 

been reported that elk, deer and rodents eat rosettes and seed heads of spotted knapweed. 

Doves, hummingbirds, honeybees, and the endangered southwestern willow flycatcher 

(Empidonax trailii extimus) are known to use saltcedar (Barrows, 1996). However, the few 

uses that an invasive plant may provide do not outweigh the adverse impacts to an entire 

ecosystem (Zavaleta, 2000). 

Invasive plants have adversely impacted habitat for native wildlife (Washington Dept. of Fish 

and Wildlife, 2003). Any species of wildlife that depends upon native understory vegetation 

for food, shelter, or breeding, is or can be adversely affected by invasive plants. Species 

 

29 Refer to Marcot et al. (1998), ICBEMP, 2000, and NWFP, 1994 for thorough discussions of the wildlife 

resources on Forest Service administered lands in the Pacific Northwest. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

restricted to very specific habitats, for example pond-dwelling amphibians, are more 

susceptible to adverse effects of invasive plants. 

Displacement of native plant communities by non-native plants results in alterations to the 

structure and function of ecosystems (MacDonald et al., 1989), and constitutes a principle 

mechanism for loss of biodiversity at regional and global scales (Lacey and Olsen, 1991; 

Risser, 1988 as cited in Johnson et al., 1994). Mills et al. (1989) and Germaine et al. (1998) 

found that native bird species diversity and density, were positively correlated with the 

volume of native vegetation, but were negatively correlated or uncorrelated with the volume 

of exotic vegetation. Invasive plants can adversely affect wildlife species by eliminating 

required habitat components, including surface water (Brotherson and Field, 1987; Dudley, 

2000; Horton, 1977), reducing available forage quantity or quality (Bedunah and Carpenter, 

1989; Rice et al., 1997; Trammell and Butler, 1995); reducing preferred cover (Rawinski and 

Malecki, 1984; Thompson et al., 1987); drastically altering habitat composition due to altered 

fire cycles (D’Antonio and Vitousek, 1992; Mack, 1981; Randall, 1996; Whisenant, 1990); 

and physical injury, such as that caused by long spines or “foxtails” (Archer, 2001). In the 

case of common burdock (Arctium minus), the prickly burs can trap bats and hummingbirds 

and cause direct mortality to individuals (Raloff, 1998; and documented in photos by Clay 

Grove, USFS, and Rosa Wilson, NPS). Invasive plants that grow large and densely can act as 

physical barriers to water sources and essential habitat (Bautista, personal observation). 

Invasive plants can act as a population sink by attracting a species and then exposing them to 

increased mortality or failed reproduction (Chew, 1981). For example, Schmidt and Whelan 

(1999) reported that native birds increased their use of exotic Lonicera and Rhamnus shrubs 

over native trees, even though nests built in the exotic shrubs experienced significantly higher 

mortality rates. 

Some invasive plants (such as knapweed) contain chemical compounds that make the plant 

unpalatable to grazing animals. Chemical compounds in these invasive plants disrupt 

microbial activity in the rumen, or cause discomfort after being ingested, resulting in a 

reduced or avoided consumption of the invasive plant (Olson, 1999). 

Habitats that become dominated by invasive plants are often not used, or used much less, by 

native and rare wildlife species. Washington Department of Fish and Wildlife (2003) 

identified noxious weeds, such as yellow starthistle and knapweed, as threats to upland game 

bird habitat. Some hunters and wildlife managers are concerned that invasive plants are 

degrading the quality of remaining habitat for deer and elk and are adversely affecting the 

animal’s distribution and hunting opportunities. Trammell and Butler (1995) found that deer, 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

elk, and bison avoided sites infested with leafy spurge (Euphorbia esula). Tamarisk stands 

have fewer and less diverse populations of mammals, reptiles, and amphibians (Jakle and 

Gatz, 1985; Olson, 1999). Invasion by purple loosestrife makes habitat unsuitable for 

numerous birds, reptiles and mammals (Kiviat, 1996; Lor, 1999; Rawinski, 1982; Thompson, 

Stuckey, and Thompson, 1987; Weihe and Neely, 1997; Weiher et al., 1996). 

In summary, invasive plants are known or suspected of causing the following effects to 

wildlife (Table 3-7): 

Table 3-7 Known Effects of Invasive Plants to Wildlife 

• Embedded seeds in animal body parts (e.g. foxtails), or entrapment (e.g. common burdock) 

leading to injury or death. 

• Scratches leading to infection. 

• Alteration of habitat structure leading to premature predation (which alters population 

demography, and social breeding system). 

• Change to effective population through nutritional deficiencies or direct physical mortality. 

• Ingestion of plants or plant parts leading to poisoning. 

• Altered food web, perhaps due to altered nutrient cycling. 

• Source-sink population demography, with more demographic sinks than sources. 

• Lack of proper forage quantity or nutritional value at critical life periods. 

• Cascading effect of direct or indirect mortality on other species. 

3.2.7 Threatened, Endangered, Proposed and Sensitive Species 

The Endangered Species Act of 1973, as amended (ESA), requires federal agencies to insure 

that their actions do not jeopardize the continued existence of endangered or threatened 

species, or result in destruction or adverse modification of critical habitat. Region Six 

provides habitat for species that are proposed, and listed as threatened or endangered 

(hereafter referred to as “listed”) by the ESA. Currently, on National Forests with the Region, 

23 fish, 9 terrestrial wildlife species, 1 insect, 1 mollusk, and 14 plants are listed (See 

Threatened, Endangered, and Sensitive Plant and Animal List Locator, Appendix C). 

The Region also maintains a list of sensitive species30. The primary objectives of the program 

is to ensure that Forest Service actions do not contribute to a loss of viability, or cause a trend 

 

30 The Sensitive Species Program and the Regional Forester’s Sensitive Species List (RFSS) are proactive 

approaches for meeting the Agencies obligations under the Endangered Species Act (ESA) and the National 

Forest Management Act (NFMA), and National Policy direction as stated in the 2670 section of the Forest 

Service Manual and the U.S. Department of Agriculture Regulation 9500-4. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

toward listing under ESA. Species identified by the FWS as “candidates” for listing under the 

ESA, and meeting the Forest Service criteria for protection, are included on the Regional 

Forester’s Sensitive Species Lists (RFSS) (See Threatened, Endangered, and Sensitive Plant 

and Animal List Locator, Appendix C). 

Terminology 

Threatened Species = species likely to become endangered within the foreseeable future throughout all or a 

significant portion of its range (16 U.S.C. 1531 et seq.). 

Endangered Species = species in danger of extinction throughout all or a significant portion of its range (16 

U.S.C. 1531 et seq.). 

Sensitive Species = species identified by the Regional Forester for which population viability is a concern, as 

evidenced by significant current or predicted downward trends in population numbers or density; or significant 

current or predicted downward trends in habitat capability that would reduce a species existing distribution (FSM 

2670). 

Survey and Manage = mitigation measure adopted as a set of standards and guidelines within the Northwest 

Forest Plan Record of Decision intended to mitigate impacts of land management efforts on those species closely 

associated with late- successional or old growth forests whose long-term persistence is a concern. 

Federally Listed and Sensitive Plant Species 

Throughout the region, there are Threatened, Endangered, and Sensitive (TES) plant species 

being impacted by invasive plants. Most, but not all of the listed plants, are found in the dry 

grass or eastside dry forest vegetation group. Both of these vegetation groups are highly 

susceptible to weed invasions. 

Seven federally listed plants have been documented and seven additional are suspected on the 

National Forests in Region Six31. They are described in Table 3-8. Included in the table are 

the global/state rarity rankings. These rankings are part of an international system for ranking 

rare, threatened endangered species throughout the world. The system was developed by the 

Nature Conservancy and is now maintained by the Association for Biodiversity Information 

in cooperation with Heritage programs in all 50 states, in 4 Canadian provinces and in 13 

Latin American countries (Oregon Natural Heritage Program, 2001). The ranking is a 1-5 

scale, primarily based on the number of known occurrences, but also including threats, 

 

31 The Regional list of Threatened and Endangered Species (July 21, 2004 Memo) shows Thelypodium howellii 

spp. Spectabilis as “suspected” on the Wallowa Whitman . Recent correspondence from the U.S. Fish and 

Wildlife Service concludes that they no longer suspect it on National Forest System land in the Region. 

3-50
Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

sensitivity, area occupied, and other biological factors. The ranking definitions are provided 

at the end of the table. 

Table 3-8 Federally Listed Plant Species Documented or Suspected in Region Six 

Species 

Global/State Ranking 

Federal 

Protection Status Habitat 

Hackelia venusta 

G1/S1 Washington 

Endangered Dry, loose granitic sand and 

crevices 

Sidalcea oregana var. calva 

G1/S1 Washington 

Endangered - 

Critical habitat designated 

Moist meadows in eastside moist 

or dry forest 

Arabis macdonaldiana 

G1/S1 Oregon 

Endangered Rocky, serpentine soils, open 

woods/slopes 

Fritillaria gentneri 

G1/S1 Oregon 

Endangered Edges – oak woodlands or mixed 

hardwood/conifer 

Lupinus sulphureus ssp. kincaidii 

G2/S1-Washington, S2-Oregon 

Threatened Remnant grasslands, upland 

prairie, some serpentine, roadsides 

Mirabilis macfarlanei 

G2/S1 Oregon, S2 Idaho 

Threatened - 

Pesticide use limits (EPA) 

Low- to mid-elevation canyon 

grasslands 

Silene spauldingii 

G2/S1-Oregon, S2 -Washington 

Threatened Mesic grass communities, palouse 

prairie region 

Arenaria paludicola* 

G1/SX 

Endangered Freshwater marsh 

Howellia aquatilis* 

G2/SH-Washington, SX-Oregon 

Threatened Seasonal wetlands 

Lilium occidentale* 

G1/S1 Oregon 

Endangered Coastal wetlands 

Lomatium cookie* 

G1/S1 Oregon 

Endangered Moist, alluvial floodplains, 

grasslands 

Plagiobothyrus hirtus* 

G1/S1 Oregon 

Endangered Low elevations in highly 

specialized alluvial soils. 

Sidalcea nelsoniana* 

G2/S1 Washington),S2 Oregon 

Threatened Remnant native grasslands 

Spiranthes diluvalis** 

G2/S1 Washington 

Threatened Wet meadows 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 3-8 Federally Listed Plant Species Documented or Suspected in Region Six 

Species 

Global/State Ranking 

Federal 

Protection Status Habitat 

G= Global ranking, S=State ranking. 

X=presumed extirpated or extinct. 

H=historical occurrence. 

*=only suspected on National Forest lands. 

Five levels of ranking: 

1. Critically imperiled because of extreme rarity or because it is particularly vulnerable to extinction 

or extirpation; typically 5 or fewer occurrences, 

2. Imperiled because of rarity or because it is vulnerable to extinction or extirpation; typically 6 to 20 

occurrences, 

3. Either very rare and local throughout its range or found locally (even abundantly) in a restricted 

range; typically 21 to 100 occurrences, 

4. Apparently secure; typically 21 to 100 occurrences, 

5. Demonstrably widespread, abundant and secure. 

Figure 3-5 shows the location of the above listed plant species by forest and by the whether 

species have been documented or suspected to occur. 

3-52
Willamette

National Forest

Deschutes

National Forest

Wenatchee

National Forest

Okanogan

National

Forest

Gifford Pinchot

National Forest

Mt. Hood

National Forest

Siskiyou

National Forest

Fremont

National Forest

Umpqua

National

Forest

Mt. BakerSnoqualmie

National Forest

Malheur

National Forest

Colville

National Forest

Winema

National

Forest

Wallowa Whitman

National Forest

Umatilla

National Forest

Rogue River

National

Forest

Ochoco

National Forest

Siuslaw

National Forest

Olympic

National Forest

Columbia River Gorge

National Scenic Area

CALIFORNIA

No warranty is made by the US Forest Service as to the 

accuracy, reliability, or completeness of these data for 

individual or aggregate use with other data. Original data 

were compiled from various sources. This information may 

not meet National Map Accuracy Standards. This product 

was developed through digital means and may be updated 

without notification.

P a c i f i c 

O c e a n

NEVADA

WASHINGTON

IDAHO

0 20 40 80 120

Miles

0 30 60 120 180

Kilometers

Figure 3-5 Federally Listed Plant Species Occurrence

OREGON

CANADA

Albers Equal Area Projection centered on 120 degrees 30 minutes west

Standard parallels: 43 degrees 10 minutes north and 50 minutes north.

Invasive Plants EIS Project

USDA Forest Service

PO Box 3623

Portland, OR 97208

Full bars represent documented occurrence.

Half bars represent suspected occurrence.

Legend

LUPINUS

MIRABILIS

SIDALCEA_NEL.

SIDALCEA_ORE.

SILENE

LILLIUM SPIRANTHES

LOMATIUM

ARABIS

ARENARIA

FRITLLARIA

HACKELIA

HOWELLIA
Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Over 400 sensitive species (including vascular, non-vascular plant and fungi species) are on 

the Regional Forester’s Sensitive Species List (Appendix C). This list is developed from a 

common set of criteria and species occurrence is listed as either documented or suspected for 

each Forest. 

Invasive plants have been documented as threats in the final rulings of some of the federally 

listed plants in this Region. Listed species documented or suspected on Forest Service land 

(Table 3-8) have varying degrees of susceptibility to infestations. Species associated with 

wetlands could be threatened by species such as Canada thistle, canary reedgrass or purple 

loosestrife. Species associated with native prairie or oak woodlands could be threatened by 

yellow starthistle, knapweeds or non-native grasses. Species associated with eastside dry 

grass and shrub communities could be threatened by cheatgrass, medusahead rye, rush 

skeletonweed or perennial pepperweed. 

Specific examples of documented threats to federally listed species from invasive plants 

include: 

Showy Stickseed (Hackalia venusta) - This endangered species is threatened by spotted and 

diffuse knapweeds, dalmation toadflax, and kochia. Dalmation toadflax may be the primary 

problem because it has the ability to expand into relatively undisturbed areas. 

Wenatchee Mountains checker-mallow (Sidalcea oregano var.calva) - The invasive species, 

sulfur cinquefoil, threatens the endangered Wenatchee Mountains checker-mallow. Sulfur 

cinquefoil is a long-lived perennial that has become one of the most serious invaders of the 

Northern Rockies (Sheley and Petroff, 1999). The introduced sulfur cinquefoil is sometimes 

confused with native northwest cinquefoil (Potentilla gracilis) that grows at the same low and 

mid-elevations. The misidentification of sulfur cinquefoil as a native variety has contributed 

to the unchecked expansion of this introduced species (Sheley and Petroff, 1999). Within the 

Wenatchee Mountains checker-mallow populations, sulfur cinquefoil does occur interspersed 

with other native Potentilla species, making it more difficult to control. 

MacFarlane’s four-o’clock (Mirabilis macfarlanei) - Two of the most serious exotic species 

invading the habitat of this threatened plant are cheatgrass (Bromus tectorum) and yellow star 

thistle (Centaurea solstitialis) (USDI FWS, 2000). Continued invasion by weedy alien 

species has been an ongoing problem for MacFarlane’s four-o’clock; as a result, the inhibition 

of its growth and development has been noted (Baker, 1983 cited in USDI FWS, 1996-

Macfarlane’s). 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Spalding’s Catchfly (Silene spauldingii) - Invasion by non-native plants threaten virtually all 

of the remaining populations of this threatened species. Species that threaten it include yellow 

starthistle, leafy spurge, Canada thistle, sulfur cinquefoil, Russian knapweed and cheatgrass. 

Besides competition for water, nutrients and light, competition for pollinators from invasive 

plants has been documented for this species in the Federal Register, 2001. Also noted in the 

Federal Register was that herbicide applications and/or grazing, both potential invasive plant 

treatment methods, threaten this species. 

In Region Six, any sensitive species found in potential vegetation groups considered highly 

susceptible to invasion and/or where a high amount of ground disturbing activity takes place 

would be the most threatened by invasive plants. 

An example of documented threats to a sensitive species from invasive plants follows: 

Pale Blue Eyed Grass (Sisyrinchium sarmentosum) – Pale blue eyed grass is a narrow 

endemic member of the Iris family. There are very few populations occurring only in Oregon 

and Washington, and most are too small in numbers to be considered self-sustaining (Raven, 

2003). It is documented on the Gifford Pinchot and Mt. Hood National Forests. These forests 

harbor 15 of the known 19 occurrences for this species. Noxious weeds have been 

documented as a threat to populations located in the Cave Creek grazing allotment. Canada 

thistle, tansy ragwort and houndstongue compete for resources both in and outside of grazing 

exclosures. Preliminary baseline data collected on the frequency of Canada thistle and tansy 

ragwort showed that 40 percent of quadrats contained Canada thistle and 20 percent contained 

tansy ragwort. The main impact of these species is competition for space and resources to the 

detriment of pale blue eyed grass. This is compounded by the fact that cattle will avoid these 

invasive plants, therefore increasing their establishment and spread. 

Threatened, Endangered, and Sensitive Wildlife Species 

Table 3-9 and Figure 3-6 contain federally listed mammals, birds, and terrestrial invertebrates, 

their scientific name, and status, included in this document. Per Forest Service regulations, 

requests for lists of endangered, threatened, and proposed species within the Region were 

made, and lists were received from the FWS on August 16, 2002, and May 5, 2003. A request 

for updates to the list was sent to FWS on May 24, 2004; a reply is pending. Some species on 

the 2003 list received from the FWS do not occur on National Forests in the Region and will 

not be discussed further. Those species include all marine species, the short-tailed albatross 

(Phoebastria albatrus) and the Columbian white-tailed deer (Odocoileus virginianus 

leucurus). The Fender’s blue butterfly (Icaricia icarioides fenderi) is suspected to occur on 

3-56
Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

the Umpqua National Forest, but has not been confirmed. The host plant for the Fender’s 

blue butterfly, Kincaid’s lupine (which is listed as threatened), does exist on the Umpqua NF. 

Effects to the habitat for Fender’s blue butterfly are discussed in the sections on listed plants. 

Table 3-9 Federally Listed Mammals, Birds, and Invertebrates in Region Six 

Common Name Scientific Name Status 

Mammals 

Grizzly bear Ursus arctos horribilis Threatened 

Gray wolf Canis lupus Endangered 

Canada lynx Lynx Canadensis Threatened 

Woodland caribou Rangifer tarandus caribou Endangered 

Birds 

American brown pelican Pelecanus occidentalis Endangered 

Bald eagle Haliaeetus leucocephalus Threatened 

Northern spotted owl Strix occidentalis caurina Threatened 

Marbled murrelet Brachyramphus marmoratus Threatened 

Western snowy plover (coastal) Charadrius alexandrinus nivosus Threatened 

Invertebrates 

Oregon silverspot butterfly Speyeria zerene hippolyta Threatened 

Critical habitat is designated for the northern spotted owl, marbled murrelet, and Oregon 

silverspot butterfly. Previously designated critical habitat was vacated, and new critical 

habitat is currently proposed for the western snowy plover. Candidate species currently 

included on the Sensitive Animal List are the Mardon skipper, Oregon spotted frog, Columbia 

spotted frog (Great Basin Distinct Population Segment (DPS)), Pacific fisher and western 

(Mazama) pocket gopher, and western sage grouse (Columbia Basin DPS). Life history 

descriptions for federally listed and sensitive animals are found in the project file. 

Introduced species have adversely affected more than 50 percent of the species included on 

the Federal List of Threatened and Endangered Species (Flather et al., 1994), and are 

recognized as the second biggest threat to listed species worldwide (Wilcove et al., 1998). 

Specific information on the effects of invasive plants to a specific listed species is often 

unavailable. Research has been limited by the relative scarcity of endangered and threatened 

wildlife, and the attention to more immediate demographic threats. Some studies have 

documented effects or potential effects to listed species or their habitat. Endangered, 

threatened, and rare birds completely avoided invasive Phragmites while utilizing neighboring 

short grass wetlands (Benoit, 1997). 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Within Region Six, invasive plants are adversely affecting several animals that are federally 

listed, candidates for listing, or Forest Service sensitive. Invasive reed canarygrass has been 

implicated in local extirpations of Oregon spotted frog, a candidate for federal listing (Hayes, 

1996). Invasive cheatgrass adversely affects habitat for western sage grouse and sharp-tailed 

grouse. (Connelly et al., 2000) 

Orange and meadow hawkweeds have displaced the grass and bulbs used by grizzly bears in 

the spring, and the invasive plants are approaching a significant impact to grizzly bear habitat 

in some areas (Layser, personal communication). 

3-58
Willamette

National Forest

Deschutes

National Forest

Wenatchee

National Forest

Okanogan

National

Forest

Gifford Pinchot

National Forest

Mt. Hood

National Forest

Siskiyou

National Forest

Fremont

National Forest

Umpqua

National

Forest

Mt. BakerSnoqualmie

National Forest

Malheur

National Forest

Colville

National Forest

Winema

National

Forest

Wallowa Whitman

National Forest

Umatilla

National Forest

Rogue River

National

Forest

Ochoco

National Forest

Siuslaw

National Forest

Olympic

National Forest

Columbia River Gorge

National Scenic Area

CALIFORNIA

No warranty is made by the US Forest Service as to the 

accuracy, reliability, or completeness of these data for 

individual or aggregate use with other data. Original data 

were compiled from various sources. This information may 

not meet National Map Accuracy Standards. This product 

was developed through digital means and may be updated 

without notification.

P a c i f i c 

O c e a n

NEVADA

WASHINGTON

IDAHO

0 20 40 80 120

Miles

0 30 60 120 180

Kilometers

Figure 3-6 Federally Listed Terrestrial Wildlife Species Occurrence 

OREGON

CANADA

Albers Equal Area Projection centered on 120 degrees 30 minutes west

Standard parallels: 43 degrees 10 minutes north and 50 minutes north.

Invasive Plants EIS Project

USDA Forest Service

PO Box 3623

Portland, OR 97208

Full bars represent documented occurrence.

Half bars represent suspected occurrence.

Legend

Bald Eagle

Northern Spotted

Owl

Marbled Murrelet

Brown Pelican

Snowy Plover

Canada Lynx

Grizzly Bear

Gray Wolf

Woodland Caribou

Oregon Silver Spot

Butterfly

Fender's Blue Butterfly
Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

On the Colville National Forest, hawkweeds and knapweeds are infesting and expanding in 

some forest openings that provide summer forage for snowshoe hare, a primary prey for 

Canada lynx (Borgsewicz, personal communication.). The quantity and quality of elk forage 

has been reduced by many species of invasive plants, which may affect future use by gray 

wolves. Hawkweeds and knapweeds are also invading spring and summer foraging habitat 

for woodland caribou (Borgsewicz, personal communication). Elk are a primary prey for gray 

wolves, and invasive plants have contributed to changes in elk distribution and densities 

(Bedunah and Carpenter, 1989; Rice et al., 1997; Trammell and Butler, 1995). 

The FWS identified encroachment of European beachgrass (Ammophila arenaria) on sand 

dunes used by western snowy plover for nesting as an important threat to this species (USDI 

FWS, 2001). This beachgrass prevents regeneration of open expanses of sand, decreases the 

width of the beach, increases beach slope, and provides habitat for predators of snowy 

plovers, reducing nesting habitat and increasing mortality (USDI FWS, 2001). 

The larval food plant for the Oregon silver spot butterfly is threatened by competition from 

invasive and native plants on the Siuslaw National Forest (Frounfelker, personal 

communication; USDI FWS, 2001). 

Invasive plants are not affecting the following listed species or their habitat: brown pelican, 

bald eagle, northern spotted owl, and marbled murrelet. 

Invasive plants are adversely affecting, or have the potential to adversely affect, most species 

on the Regional Forester’s Sensitive Animal List. In particular, pygmy rabbit, greater sage 

grouse, sharp-tailed grouse, Columbian sharp-tailed grouse, most passerine type birds, frogs, 

turtles, and some salamanders are vulnerable to habitat changes created by invasive plants. 

Invasive plants have also adversely modified habitat for, and threaten the larval and adult food 

plants of, the Mardon skipper. 

Federally Listed and Sensitive Aquatic Species 

Fish species with complex life histories (such as Pacific salmonids) are often listed under the 

ESA by Evolutionarily Significant Unit (ESU) or Distinct Population Segment (DPA) 

(NOAA, 2000). There are six “endangered” and two “proposed” fish ESUs in Region Six. 

Fifteen fish ESUs and one mollusk species are threatened within the Region. See Table 3-10 

and Figure 3-7. Twenty-seven fish species are listed on the Regional Forester’s sensitive 

species list. The habitat and life history requirements for all of the species in Table 3-10 are 

located in the project file. No endangered, threatened, or sensitive aquatic plant species are 

found in Region Six. Amphibian species are discussed in the wildlife section. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 3-10 Endangered and Threatened Fish and Mollusks 

Common Name Scientific Name 

(Genus and species) Status 

Snake River Sockeye Salmon - Migratory Habitat Only Oncorhynchus nerka Endangered 

Upper Columbia River Spring Chinook Oncorhynchus tshawytscha Endangered 

Upper Columbia River Steelhead Oncorhynchus mykiss Endangered 

Lost River Sucker Deltistes luxatus Endangered 

Shortnose Sucker Chastistes brevirostris Endangered 

Oregon Chub Oregonichythys crameri Endangered 

Southern Oregon/Northern California Coast Coho Salmon Oncorhynchus kisutch Threatened 

Oregon Coast Coho Oncorhynchus kisutch Proposed 

Southwest Washington/Lower Columbia River Coho Oncorhynchus kisutch Proposed 

Snake River Spring/Summer Chinook Oncorhynchus tshawytscha Threatened 

Snake River Fall Chinook Oncorhynchus tshawytscha Threatened 

Puget Sound Chinook Salmon Oncorhynchus tshawytscha Threatened 

Upper Willamette River Chinook Oncorhynchus tshawytscha Threatened 

Lower Columbia River Chinook Oncorhynchus tshawytscha Threatened 

Snake River Steelhead Oncorhynchus mykiss Threatened 

Lower Columbia River Steelhead Oncorhynchus mykiss Threatened 

Mid Columbia River Steelhead Oncorhynchus mykiss Threatened 

Warner Sucker Catostomos warnerensis Threatened 

Hood Canal Chum Salmon Oncorhynchus keta Threatened 

Columbia River Chum Salmon Oncorhynchus keta Threatened 

Klamath River Bull Trout Salvelinus confluentus Threatened 

Columbia River Bull Trout Salvelinus confluentus Threatened 

Coastal/Puget Sound Bull Trout Salvelinus confluentus Threatened 

Bliss Rapids Snail Taylorconcha serpenticola Threatened 

3-62
Willamette

National Forest

Deschutes

National Forest

Wenatchee

National Forest

Okanogan

National

Forest

Gifford Pinchot

National Forest

Mt. Hood

National Forest

Siskiyou

National Forest

Fremont

National Forest

Umpqua

National

Forest

Mt. BakerSnoqualmie

National Forest

Malheur

National Forest

Colville

National Forest

Winema

National

Forest

Wallowa Whitman

National Forest

Umatilla

National Forest

Rogue River

National

Forest

Ochoco

National Forest

Siuslaw

National Forest

Olympic

National Forest

Columbia River Gorge

National Scenic Area

CALIFORNIA

No warranty is made by the US Forest Service as to the 

accuracy, reliability, or completeness of these data for 

individual or aggregate use with other data. Original data 

were compiled from various sources. This information may 

not meet National Map Accuracy Standards. This product 

was developed through digital means and may be updated 

without notification.

P a c i f i c 

O c e a n

NEVADA

WASHINGTON

IDAHO

0 20 40 80 120Miles

0 30 60 120 180

Kilometers

Figure 3-7 Federally Listed and Proposed Aquatic Species Occurrence

OREGON

CANADA

Albers Equal Area Projection centered on 120 degrees 30 minutes west

Standard parallels: 43 degrees 10 minutes north and 50 minutes north.

Invasive Plants EIS Project

USDA Forest Service

PO Box 3623

Portland, OR 97208

Legend

Shortnose Sucker

Sockeye Salmon

Steelhead Trout

WarnerSucker

Bliss Rapid Snail

BullTrout

Chinook Salmon

Oregon Chub

Chum Salmon

Coho Salmon

Lost River Sucker

Full bars represent documented occurrence

Half bars represent suspected occurrence
Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Both “critical habitat” and species have protection under the ESA. Critical Habitat is defined 

as: 

The specific areas within the geographical area occupied by the species, at the time it 

is listed, on which are found those physical or biological features (constituent 

elements) that are essential to the conservation of the species and which may require 

special management considerations or protection; and 

Specific areas outside the geographical area occupied by the species at the time it is 

listed upon a determination by the Secretary that such areas are essential for the 

conservation of the species [ESA 3 (5)(A)]. 

Critical habitat has been designated for the Lost River sucker, shortnose sucker and Warner 

sucker and is proposed for the Klamath and Columbia River bull trout. 

Reduction of trees along streams, resulting from increased invasive plants, reduces 

recruitment of large woody debris into streams and reduces the size, quality, and quantity of 

pool habitat. Loss of shade and stream structure provided by native trees can adversely affect 

stream temperatures and can decrease available rearing habitat for endangered, threatened, or 

sensitive juvenile salmon and steelhead. 

Increases in fine sediments that result from invasive plants can adversely affect endangered, 

threatened, or sensitive salmonids via reduced egg survival and fry emergence. Reductions in 

pool volume and frequency are also pathways through which sediment introduction can 

adversely affect endangered, threatened, or sensitive fish species. 

Endangered salmon in the Region might be negatively affected by purple loosestrife because 

the plant could disrupt the detritus-based food web upon which the salmon depend by 

changing the amount and timing of nitrogen input. (Grout et al., 1997). 

Several other pathways through which invasive plants could affect endangered, threatened, or 

sensitive fish species are possible, but have not been demonstrated. For example, allelopathic 

compounds produced by invasive plants may be delivered to aquatic systems, and have 

adverse affects on resident aquatic plants and animals. Little is known concerning the 

chemistry of invasive plant decomposition, or subsequent effects on aquatic systems. 

Terrestrial insects and leaves falling into streams are fundamental to the aquatic food web. 

Invasive plant infestations may cause shifts in terrestrial insect species present, altering the 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

aquatic food web. It is not known if invasive plants affect the Bliss Rapids snail, or its 

habitat. 

3.2.8 Social and Economic 

The social component of an ecosystem is comprised of a host of complex social and economic 

elements. These elements are interrelated, interdependent, and ultimately inseparable from 

the elements that comprise the biophysical environment. As Force and Machlis (1997) state, 

“People are an integral part of ecosystems, similar to other fauna, water, soil, flora, and so 

forth. Thus, indicators of human socioeconomic conditions are as necessary for ecosystem 

management as indicators of water quality, wildlife populations, and plant communities.” 

Changes in National Forest management may affect individuals and/or the families, groups, 

and communities to which they belong. 

More lengthy explorations of social considerations for a related project area can be found in 

the Interior Columbia Basin Supplemental Draft Environmental Impact Statement (ICBEMP, 

2000) and An Assessment of Ecosystem Components in the Interior Columbia Basin and 

Portions of the Klamath and Great Basin (Quigley and Arbelbide, 1997). Other key social 

elements including economics and recreation are explored elsewhere in this EIS. 

In decision making for both short and long term futures, natural resource managers must 

simultaneously consider local concerns and national environmental and economic issues 

(Force and Machlis, 1997). Of the four critical scales for ecosystem management noted by 

Force and Machlis (communities, counties, states, and regions), the “affected community” of 

this EIS refers to the multi-state region of impact. As direction in this EIS is implemented, 

more focused definitions of “affected community” will need to be explored at the site-specific 

levels, such as forest, watershed, county, city, community, group, etc. levels. 

This section briefly describes some population attributes for Oregon and Washington, as these 

populations are those most likely to be directly impacted by the management actions outlined 

in this document. Other populations (states, national, international) and individuals outside of 

these states are also likely to experience impacts or effects resulting from these actions, yet 

those populations are beyond the reasonable scope of this demographic briefing. Small 

portions of two national forests covered in this EIS extend into California or Idaho. It should 

be noted that those most directly impacted would likely be those who live in close proximity 

to the National Forests and those who depend on or visit the forests most often. Data for this 

section came from Census 2000 results (U.S. Census Bureau, 2003; Censusscope, 2003) 

unless otherwise noted. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Of Oregon’s 61.4 million total acres, about 60 percent (37 million) are under federal and state 

ownership; of which the Forest Service manages about 15.6 million acres. Of Washington’s 

42.6 million total acres, about 42 percent (17.8 million acres) are under federal and state 

ownership; of which the Forest Service manages about 9.3 million acres. 

The Pacific Northwest tends to have a dual east/west identity shaped by the Cascade mountain 

range that bisects the region. Generally the region has a wet-side (west) and a dry-side (east). 

The eastern portion of the region contains more rural and dispersed human settlement, while 

the westside is more urban, containing the regions most dense population centers: the Seattle 

and Portland metropolitan areas. Eighty-eight percent of the population lives on the 24 

percent of land that comprises the “west side” of Oregon and Washington. 

In 2000 the two-state region had a total population of about 9,315,520 people, with 3,421,399 

and 5,894,121 people in Oregon and Washington respectively. 

Between 1990 and 2000 the population grew by 20.4 percent in Oregon and 21.1 percent in 

Washington. Relatively, the United States population grew by 13.2 percent overall during 

that time period. Washington and Oregon ranked number 10 and 11, respectively, for growth 

rates in the United States during that decade. Growth in the western United States is projected 

to continue to grow at even faster rates in the next 25 years (Burchfield et al. date unknown). 

Oregon had an overall population density of 35.6 people per square mile in 2000. 

Washington had an overall population density of 88.6 people per square mile that year. A 

broad spectrum of population densities is represented throughout the two-state region, with 

the lowest county population density at 0.8 people per square mile in Harney County, Oregon 

and the highest county population density at 1,517.6 people per square mile in Multnomah 

County Oregon. 

Both states are predominantly white, followed by Hispanics, American Indians, and Asians. 

The number of Hispanics, as percent of population, nearly doubled in both states between 

1990 and 2000. In 2000 Hispanics represented 8.05 percent of Oregon population and 7.49 

percent of the Washington population. Oregon and Washington had unemployment rates of 

6.8 percent and 6.1 percent respectively as of May 2004; both higher than the national rate of 

5.6 percent (U.S. Department of Labor, Bureau of Labor Statistics, 2004). 

Just as the biophysical impacts of invasive plants do not end at the forest boundary, the 

socioeconomic effects of invasives also extend far beyond federal lands. For instance, public 

lands can act as a seed bank for invasive plants that can, through a variety of mechanisms, 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

make their way onto other public and non-public lands (and vise versa), sometimes resulting 

in significant socioeconomic impacts. 

Invasive plants have particularly significant impact on the agricultural sector. Invasive plants 

(and seeds) in harvested crops can result in direct monetary loss to farmers due to reduced 

crop values, increased spoilage rates, and prohibition of national and international trade of 

infested farm products. Invasive plants and other weeds can add significant expense to hand 

and mechanical harvesting of crops by making harvesting more difficult and adding 

unnecessary wear on machinery. Valuable irrigation water can be lost as invasive plants 

consume water intended for crops, cause water loss by seepage, and as plant mater slows 

water flow increasing evaporation. Invasive plants and other weeds can also reduce land 

values (both public and private) as a related loss of productive potential is recognized in 

appraisal (Westbrooks, 1998). In the U.S. agricultural sector alone, invasive plants cause an 

estimated $20 billion in loss of productivity annually (Oregon Department of Agriculture, 

2000). One preliminary analysis of economic impact of noxious weeds in Oregon estimated 

that Oregonians experience forgone income of $67 million annually from just 12 species of 

plants (Oregon Department of Agriculture, 2000). Farmers spend billions of dollars each year 

on herbicides to protect crops from invasive plants and other weeds (Westbrooks, 1998). 

Additionally, millions of dollars are lost each year in the unnecessary transport of invasives 

and other weeds in crop shipments and in additional costs to clean the product of unwanted 

plant material. 

Some direct socioeconomic impacts of invasive plants on National Forest lands include 

increased risk of wildfires and suppression costs and reduced productivity of forest nurseries 

and tree plantations. 

Invasive plants can also interfere with recreational opportunities, an increasingly demanded 

product of public lands. Since these lands are usually managed by public agencies, costs can 

be passed on to society in the form of higher taxes or fees or through access limitation. 

Invasive plants can have a negative effect on observation-based tourism, as the wildlife and 

wildflowers that people come to enjoy and photograph are crowded out by invasive plants 

(Westbrooks, 1998). Similar negative impacts to hunting and fishing revenues can be 

expected as invasive plants displace wildlife or impede access to wildlife and fish related 

recreation. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Tribes and Treaty Rights 

Within Region Six, 26 Indian tribes have treaty reserved or Executive Order rights outside the 

bounds of their respective Indian reservations (see Table 3-11). These rights include: fishing, 

hunting, gathering, grazing livestock, and trapping. The areas of interest to Indian tribes with 

off-reservation rights are the lands ceded to the U.S., often called “ceded lands.” 

Additionally, there are 13 Indian tribes without off-reservation reserved rights who continue 

to gather natural resources for traditional or cultural purposes. The land area includes most of 

the National Forests in Washington and Oregon. 

Invasive plants may interfere with treaty rights granted to Native American Tribes of the 

Pacific Northwest. Invasive plant can crowd out plants traditionally gathered for food, dress, 

or ceremonial purposes and can influence wildlife and fish behavior. Scoping comments for 

this EIS expressed that at least one tribe feels that invasive plants may be negatively 

impacting their ability to fully exercise their treaty rights. Additionally, invasive plants may 

have negative impacts on other groups or individuals that hunt or gather non-timber forest 

products and forest users seeking floral communities that are within the historic range of 

variability. 

Table 3-11 Tribes and Treaty Rights 

Tribes with Off-Reservation Rights Tribes without Off Reservation Rights 

Hoh Indian Tribe 

Confederated Tribes of the Colville Reservation 

Jamestown S’Klallam Tribe of Indians 

The Klamath Tribes 

Lower Elwha Tribal Community 

Lummi Tribe of the Lummi Reservation, 

Washington 

Makah Indian Tribe of the Makah Indian 

Reservation 

Muckleshoot Indian Tribe 

Nez Perce Tribe (reservation in Idaho) 

Nisqually Indian Community 

Nooksack Indian Tribe 

Port Gamble Band of S'Klallam Indians 

Puyallup Tribe of the Puyallup Reservation of the 

State of Washington 

Quileute Tribe of the Quileute Reservation 

Quinault Indian Nation 

Sauk-Suiattle Indian Tribe 

Skokomish Indian Tribe 

Squaxin Island Tribe 

Burns Paiute

Confederated Tribes of the Chehalis Reservation 

Confederated Tribes of the Coos, Lower Umpqua 

and Siuslaw Indians of Oregon 

Coquille Indian Tribes 

Cow Creek Band of Umpqua Tribe of Indians 

Cowlitz Indian Tribe 

Confederated Tribes of the Grand Ronde

Community of Oregon 

Kalispel Indian Community of the Kalispel 

Reservation 

Samish Indian Tribe 

Shoalwater Bay Indian Tribe of the Shoalwater Bay 

Indian Reservation 

Confederated Tribes of Siletz Indians of Oregon 

Snoqualmie Tribal Organization 

The Spokane Tribe 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 3-11 Tribes and Treaty Rights 

Tribes with Off-Reservation Rights Tribes without Off Reservation Rights 

Stillaguamish Tribe of Indians 

Suquamish Tribe of the Port Madison Reservation, 

Washington 

Swinomish Indian Tribal Community 

The Tulalip Tribes 

Confederated Tribes of the Umatilla Indian 

Reservation 

Upper Skagit Indian Tribe 

Confederated Tribes of the Warm Springs

Reservation of Oregon 

Confederated Tribes and Bands of the Yakama

Nation 

3.2.9 Congressionally Designated Areas 

Congress has designated numerous areas as unique for their special characteristics and the 

opportunities they offer. There are eighty-one congressionally designated areas (CDA) in 

Region Six. These include fifty-nine Wilderness Areas (4.6 million total acres), thirty-nine 

Wild and Scenic River corridors, and thirteen other areas including, National Recreation 

Areas, National Volcanic Monuments, National Scenic Areas, National Scenic and Research 

Areas, Special Management Areas, a Watershed Management Area, and a National Scenic 

Highway. CDAs provide unique values and experience opportunities, and they are managed 

under a suite of similarly unique laws and management policies. Figure 3-8 shows CDAs in 

Region Six. 

CDA land allocations do not change among the alternatives. This EIS does not alter statutory 

direction provided by congress and does not alter Forest Service regulations and policy for 

CDA. Management of CDAs will continue to follow applicable existing plans, except as 

those plans are specifically amended by this EIS. 

Although human-caused ground disturbing activities (such as those associated with motorized 

or mechanized vehicles) may be limited within some CDA boundaries, these areas are still at 

risk of invasive plant infestation. This risk is amplified in that the unique natural features and 

social values for which the CDA was originally designated, may be adversely affected by 

invasive plants, and that protection of these unique features and values is among the statutory 

responsibilities of CDA management. 

In Wilderness Areas motorized travel is prohibited and the ground disturbances and vectors of 

invasive plant seed spread associated with motorized vehicle use are greatly diminished. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

However, both natural and human caused ground disturbances and vectors of invasive plant 

seed spread still exist. Invasive plant inventories show that Wilderness Areas in Region Six 

have not yet been highly infiltrated by invasive plants. Unfortunately, invasive plants are 

gradually finding there way into Wilderness Areas, and have been identified mostly along 

trails, and more heavily used zones such as riparian zones. Prevention measures are 

especially important in areas where invasive plants are not yet well established and where 

once established, treatment can be particularly difficult and in conflict with the values the area 

was originally designated for. 

One invasive plant prevention strategy, currently in use on some National Forests, is to 

encourage or require the use of certified weed free hay or pelletized feed when using horses or 

other livestock in certain areas. Certified weed free hay or pelletized feed is currently 

required on about 2.5 million acres of Wilderness in Region Six. The following list shows 

National Forests in Region 6 that have weed-free feed requirements and where the 

requirements apply: 

• Mt. Baker-Snoqualmie: Wilderness Regulation: Possessing unprocessed hay, straw, 

or raw grain livestock feed is prohibited. Use processed feed to reduce the chance of 

introducing weeds into native ecosystems. 

• Rogue River-Siskiyou and Winema: For the Wild Rogue (35,818 acres, which 

includes a portion of BLM land administered by the FS), Grassy Knob (17,200 acres) 

and Kalmiopsis Wilderness (179,755 acres): Order No. SIF002 Prohibits: Possessing 

or storing hay or unprocessed (vialbe) grain. 36 CFR 261.58(cc). For the Sky Lakes 

(116,300 acres) and Red Buttes (19,940 acres): Order No. RRF-016 Prohibits: 

Possessing or storing hay or unprocessed (viable) grain. 36 CFR 261.58(cc). 

• Gifford Pinchot: Wilderness Regulation: Unprocessed hay, grain or other forms of 

livestock feed are prohibited. Processed feed includes pelletized feeds and irradiated 

grains in their original container. Any livestock feed that may serve as a seed source 

for non-native plants is considered unprocessed. 

• Olympic: 36CFR261.58(a and b) Prohibits the following acts in Wilderness Areas: 

Possessing and/or transporting unprocessed vegetative matter, such as hay, straw, 

grass or grain. 

• Wallowa-Whitman: Hells Canyon National Recreation Area (Rec-S7 of the Hells 

Canyon CMP applies to all acres in the NRA) Rec-S7: All users of pack and saddle 

stock must carry and use pelletized, or other certified weed-free feed. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

• Eagle Cap Ranger District: 36CFR261.58(t): Possessing, storing or transporting any 

supplemental livestock feed that is not free of all noxious weed seeds [is prohibited]. 

Other National Forests, including the Umatilla and the Wallowa-Whitman, encourage the use 

of weed-free or pelletized feed when using domestic animals in Wilderness Areas. 

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Willamette

National Forest

Deschutes

National Forest

Wenatchee

National Forest

Okanogan

National

Forest

Gifford Pinchot

National Forest

Mt. Hood

National Forest

Siskiyou

National Forest

Fremont

National Forest

Umpqua

National

Forest

Mt. BakerSnoqualmie

National Forest

Malheur

National Forest

Colville

National Forest

Winema

National

Forest

Wallowa Whitman

National Forest

Umatilla

National Forest

Rogue River

National

Forest

Ochoco

National Forest

Siuslaw

National Forest

Olympic

National Forest

Columbia River Gorge

National Scenic Area

CALIFORNIA

No warranty is made by the US Forest Service as to the 

accuracy, reliability, or completeness of these data for 

individual or aggregate use with other data. Original data 

were compiled from various sources. This information may 

not meet National Map Accuracy Standards. This product 

was developed through digital means and may be updated 

without notification.

P a c i f i c 

O c e a n

NEVADA

WASHINGTON

IDAHO

0 20 40 80 120

Miles

0 30 60 120 180

Kilometers

Figure 3-8 Congressionally Designated Areas

OREGON

CANADA

Albers Equal Area Projection centered on 120 degrees 30 minutes west

Standard parallels: 43 degrees 10 minutes north and 50 minutes north.

Invasive Plants EIS Project

USDA Forest Service

PO Box 3623

Portland, OR 97208

Legend

BULL RUN WATERSHED MGMT. AREA

RECREATION AREA

RESEARCH NATURAL AREA

NATIONAL RECREATION AREA

NATIONAL SCENIC AND RESEARCH AREA

NATIONAL SCENIC AREA

NATIONAL VOLCANIC MONUMENT

WILD AND SCENIC RIVER

WILDERNESS
Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

3.3 Invasive Plant Management 

Invasive plant management is based on ecological principles. Simply focusing on killing 

infestations, without considering the cause of invasion or successional processes occurring 

may not lead towards a desired plant community. Plant communities are dynamic; using 

methods that enhance natural processes and regulate vegetation change are the most likely to 

succeed. Moving an undesirable plant community towards a desired state takes a repeated, 

sequential process of: 

− designing a disruption to the undesired successional pathway, 

− controlling invasive species performance, and 

− controlling invasive colonization (Sheley et al., 1996). 

This means an effective strategy should include: (1) prevention of the conditions that favor 

invasive plants and encouragement of conditions that resist them (controlling invasive 

colonization), (2) treatments that not only control the invasive species (controlling invasive 

species performance), but also purposefully manage for desired vegetation (designing a 

disruption to the undesired successional pathway). 

The following describes how prevention, treatment and restoration techniques work to deter 

the introduction, establishment and spread of invasive plants. 

3.3.1 Prevention 

Prevention means limiting, managing or sometimes eliminating activities on National Forests 

so that invasive plants do not become established within un-infested areas, and the potential 

for reproduction and spread of existing invasive plants is reduced. In addition to 

implementing specific standards to prevent initial introduction, prevention involves 

developing management goals to prevent the spread of existing infestations to new sites 

(Mullin et al., 2000). 

The primary goal of prevention is to keep un-infested land from becoming infested (Asher, 

1998). Executive Order 11312 and Forest Service direction (FSM 2080.2) emphasize the 

priority of prevention in managing invasive plants. The recently released National Strategy 

and Implementation Plan for Invasive Species Management (USDA Forest Service, 2004) 

(Appendix S) also emphasizes the importance of prevention. 

One way to keep uninfested land from becoming infested is by altering the scale and scope of 

land management and use activities, that promote invasive plant establishment, especially in 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

the most susceptible habitats. Another way is to implement proactive prevention practices 

such as washing of equipment and off highway vehicles, restricting livestock feed to weedfree feed only, and eliminating invasive plant seed from gravel and rock before use on roads. 

3.3.2 Treatment and Restoration 

Treatment methods emphasized in this EIS include manual, mechanical, biological, cultural, 

prescribed fire, and herbicides. In many cases, these methods are most effective when used in 

combination with one another, as well as in combination with prevention activities in 

accordance with Integrated Weed Management principles. The location and size of the 

infestation, environmental factors, management objectives, and treatment costs all factor into 

the choice of treatment method(s); the wider the range of available methods, the more 

effective the alternative in treating invasive plants. For more detailed information on control 

of specific species, see “Common Control Measures for Invasive Plants of the Pacific 

Northwest Region” (Appendix N). This document provides guidance through literature 

review to the botanists and weed coordinators in Region Six. It is a constantly expanding 

document. 

Prioritizing Sites and Selecting Treatment Methods 

The following discussion summarizes methods for prioritizing invasive plant treatments. 

Invasive plant species listed in Appendix B should be considered the “first cut” for Forest 

weed coordinators when developing site-specific treatment projects. The relative priority for 

treating each species or situation varies substantially between sites in the Region depending 

on site-specific risks and values. 

In general, herbicides selected for use are those with the highest potential for success with the 

least amount of impact to non-target resources. Potency, selectivity and persistence of an 

herbicide are factors that influence its effectiveness and potential for adverse effects The 

choice of herbicide is based on characteristics of the invasive species; how is reproduces, its 

seed viability, the size of its population, site conditions, known effectiveness under similar 

site conditions and the ability to mitigate effects on non-target species. 

Often herbicides are used in combination with other methods. Treatment effectiveness may 

increase when herbicide formulations are mixed or herbicide use is integrated with manual or 

mechanical treatments. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

For example, initial treatment on an invasive species may be done by an herbicide, but then 

manual or mechanical methods would be implemented as maintenance treatments over the 

long-term. 

Application methods used are often based on site accessibility. Aerial spraying, for example, 

would only be used in areas where access is remote and difficult and populations are of the 

size that non-herbicide methods or selective herbicide application is not feasible. 

Prioritizing Species 

While state listed noxious weeds are always of high priority for control, the threat of species 

not necessarily on State lists, but that are known to cause substantial ecological impact should 

also be considered. An example would be a species known to alter fire regimes. Cheatgrass 

or medusahead may not necessarily be listed by a State. Their range is expansive and 

therefore beyond eradication in many locations, but if new infestations are detected in 

relatively intact native plant communities, such populations should be of highest priority for 

control due to their potential to alter the fire regime. 

A system for prioritizing invasive species for control and restoration of pre-invasion 

conditions at various stages of the invasive plant fire regime cycle is discussed in Brooks et 

al., (2004). This system is broken into four phases based on the potential of a species to 

cause significant ecological impact. Such a system could be used to direct prioritization 

decisions on any species and emphasizes the point that newly detected species must be 

assessed for their potential to naturalize, become invasive and alter ecosystem functioning. 

Such a system is not limited to fire regime-altering species, but could be used for any 

ecosystem where the potential for shifts in function could occur (such as riparian systems). 

Other tools exist for assessing the invasiveness of a species to assist in prioritizing. One 

recommended tool is the Invasive Species Assessment Protocol (Morse et al, 2004). The 

protocol uses both screening and assessment questions to understand ecological impact, trends 

in distribution and abundance and management difficulties. Questions have a varying point 

system to develop an invasive ranking for a species. Such a protocol may be useful for 

developing an invasiveness rank would be helpful when working with cooperators at the 

regional scale. Rankings developed by other agencies could be useful for Forest staff when 

invasiveness is of question. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Prioritizing Treatments 

Infestations need to be assessed when developing a treatment strategy as to whether they can 

be eradicated, controlled, contained, suppressed or tolerated. These terms are defined below. 

Terminology

The following terms may be found in the text when discussing treatment methods. They may be used as targets 

or objectives for developing site specific treatment strategies. Definitions are taken from the Lolo National 

Forest Noxious Weed Management FEIS ROD (USDA, 1991) and the Frank Church-River of No Return 

Wilderness Noxious Weed Treatments FEIS (USDA, 1999). Some expansion of these definitions for this 

document is included. 

Eradication: Attempt to totally eliminate an invasive plant species from a Forest Service unit, recognizing that 

this may not actually be achieved in the short term since re-establishment/re-invasion may take place initially. 

Control: Reduce the infestation over time; some level of infestation may be acceptable. 

Contain: Prevent the spread of the weed beyond the perimeter of patches or infestation areas mapped from 

current inventories. 

Suppress: Prevent seed production throughout the target patch and reduce the area coverage. Prevent the 

invasive species from dominating the vegetation of the area; low levels may be acceptable. 

Tolerate: Accept the continued presence of established infestations and the probable spread to ecological limits 

for certain species. Try to exclude new infestations through prevention practices. This is for species where other 

levels of effort have not been successful. 

Prioritization of infestation treatments should be based on the following decision pathway. 

Highest priority treatments should be focused on new invaders and early treatment of new 

infestations, followed in priority by containment, then control of larger established 

infestations. Moody and Mack (1988) demonstrated in a simple geometric model that small, 

new outbreaks of invasive plants eventually would occupy an area larger than the source 

population. Control efforts that focus on the large, main population rather than the new small 

satellites reduced the chances of overall success. The ability to detect and destroy the new, 

small infestation was crucial to control of invasive species and should be combined with 

efforts to control established populations. Another important point for consideration of 

treatments is control costs. A maintenance strategy focused on control may be more 

economically feasible than attempting to eradicate large populations. 

Another model being used is to apply the fundamentals of wildfire management to invasive 

plant control. Thinking of weeds as a slow-moving wildfire can provide a valuable 

perspective and generate useful ideas when developing and implementing invasive plant 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

strategies (Dewey, 2003). Prevention, early detection, rapid response, contain/control, and 

site restoration are terminologies that are interchangeable in wildfire management and 

invasive plant control. Focusing on spot fires (or new infestations), containing the size 

around the perimeter and mopping up (or returning to ensure all controlled sites are 

eradicated) may be a means to help focus planning efforts. 

The methods and factors for prioritizing invasive plant sites for treatments on the Forests in 

Region Six generally follow a similar decision-making model. Table 3-12 is based on a 

Forest Service guide for how to prioritize sites and select treatment methods (USDA Forest 

Service 2001). 

Table 3-12 Priorities for Treatment and Selection of Treatment Methods. 

Priority Description Treatment – choice based on site-specific 

conditions 

Highest 

Priority for 

Treatment 

* Eradication of new species (focus on 

aggressive species with potential for 

significant ecological impact including but 

not limited to State listed high priority 

noxious weeds) 

* New infestations (e.g. populations in areas 

not yet infested; “spot fires”; any State or 

Forest priority species). 

* Areas of concern such as: 

Areas of high traffic and sources of 

infestation (e.g. parking lots, trailheads, 

horse camps, gravel pits) 

Areas of special concerns: (e.g. botanical 

areas, wilderness, research natural areas, 

adjacent boundaries/access with national 

parks) Riparian corridors where high 

threat species such as knotweeds occur. 

1. Manual/mechanical - isolated plants or 

small populations. 

2. Herbicide treatment if manual/mechanical 

is known to be ineffective or population 

too large. 

3. Remove seed heads. This is an interim 

measure if cost/staff is an issue. 

4. Seed to restore treated areas; use native 

species when possible. 

Second 

Priority of 

Treatment 

* Containment of existing large infestations 

(e.g. focus on State-listed highest priority 

species or Forest priority species) – focus 

on boundaries of infestation. 

* Roadsides – focus first on access points 

leading to areas of concern. 

1. Manual/mechanical - isolated plants or 

small populations in spread zones. 

2. Herbicide treatment for larger populations 

along perimeter. 

3. Seed to restore treated areas to create a 

buffer from spread; use native species 

when possible. 

Third 

Priority of 

Treatment 

* Control of existing large infestations (e.g. 

State-listed and Forest second priority 

species) 

1. Disperse biocontrol agents on large 

infestations 

2. Livestock grazing 

3. Mechanical 

4. Herbicide application 

Fourth 

Priority of 

Treatment 

* Suppression of existing large infestations 

when eradication/control or containment is 

not possible. 

1. Biocontrol on large infestations 

2. Livestock grazing 

3. Mechanical 

4. Herbicide application along perimeters 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Manual and Mechanical 

Manual and mechanical treatments physically remove and destroy, disrupt the growth of, or 

interfere with the reproduction of invasive plants. These treatments can be accomplished by 

hand, hand tool (manual), or power tools (mechanical); and include pulling, grubbing, 

digging, hoeing, tilling, cutting, mowing, and mulching of the target plants. Thermal 

techniques such as steaming, super heated water and hot foam are also considered as viable 

treatments. 

Manual methods can be effective on small infestations if the entire root is removed. With 

new, small infestations, hand pulling can be the easiest and quickest method. Even larger 

populations, though, can be controlled with hand pulling if the workforce is available. The 

Bradley Method is one sensible approach to manual control of invasive plants (Fuller and 

Barbe, 1985). This method consists of hand weeding selected small areas of infestation in a 

specific sequence, starting with the best stands of native vegetation (those with the least extent 

of infestation) and working towards stands with the worst infestation. 

Manual methods are usually not as effective for deep-rooted or rhizomatous32 perennials such 

as leafy spurge where hand-pulling and hoeing often leave root fragments that can generate 

new plants. Hand-pulling or hoeing also disturbs the soil surface, which may increase 

susceptibility of a site to reinvasion by weeds (Brown et al., 2001; Duncan et al., 2001). 

Manual methods are labor-intensive and usually ineffective for the treatment of large, wellestablished infestations of perennial invasive plants with long term viable seed such as 

knapweeds (Brown et al., 2001). Hand-pulling trials conducted on spotted knapweed in 

western Montana and on diffuse knapweed in west-central Colorado were 35 percent and 0 

percent effective, respectively. The treatments were completed twice per year for two 

consecutive years, were found to significantly increase bare ground, and were expensive 

(Duncan et al., 2001). 

Test plots established on Blue Mountain (Lolo National Forest) and the Lee Metcalf National 

Wildlife Refuge near Stevensville, Montana, measured effects of hand-pulling on spotted 

knapweed. Spotted knapweed covered 76 percent and 53 percent of the two sites, 

respectively. Hand-pulling provided 100 percent flower control and 56 percent plant control 

at Blue Mountain, but resulted in an increase in bare ground from 2.7 percent to 13.7 percent 

during the first year after treatment (Brown et al., 2001). Local efforts where larger 

 

32 Rhizomes are horizontally creeping, underground stems, which bear roots and leaves. Rhizomatous species 

tend to spread very quickly because of these growth structures. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

community support or funding for hand crews exists do show promise, if efforts can be 

sustained (Henry 2004). 

Mowing or cutting is more effective on tap-rooted perennials such as spotted knapweed 

compared to rhizomatous perennials (Brown et al., 2001). Cutting or mowing plants can 

reduce seed production if conducted at the right growth stage. For example, a single mowing 

at late bud growth stage can reduce the number of seeds produced on spotted knapweed 

(Watson and Renny, 1974). Mowing can also weaken an invasive plant’s competitive 

advantage by depleting root carbohydrate reserves, but mowing must be conducted several 

times a year for consecutive years to reduce the competitive ability of the plant. 

Because invasive plants flower throughout the summer, it is difficult to time mechanical 

treatments to prevent flowering and seed production. Repeated mechanical treatment too 

early in the growing season can result in a low growth form that is still capable of producing 

flowers and seed (Benefield et al., 1999; Goodwin and Sheley, 2001). Mechanical treatments 

on some rhizomatous weeds, such as leafy spurge, can encourage sprouting and result in an 

increase in stem density (Goodwin and Sheley, 2001). 

Tillage methods are most effective for controlling tap-rooted invasive plant species on small 

acreages and level terrain, where infestations can be revisited on a regular basis to remove 

new germinants and resprouts over time. Tillage removes all vegetation and should be 

combined with seeding or planting of desirable species. Invasive plant seeds may remain 

viable in soil for several years (Davis et al. 1993; Selleck et al., 1962) and often may reinfest a 

tilled site, thus requiring continued follow-up treatments. 

Mulching with plastic or organic materials can be used on relatively small areas (less than 

0.25 acre), but will also stunt or stop growth of desirable native species. Mulching prevents 

seeds and seedlings from receiving sunlight necessary to survive and grow, and can smother 

some established invasive plants. Hay mulch was used in Idaho to reduce flowering of 

Canada thistle (Tu et al., 2001), but most rhizomatous perennial invasive plants cannot be 

controlled by this method or by shading because extensive root reserves allow regrowth 

through and around mulch or shade materials. A new mulch made from wood products is 

currently being tested by the Forest Service and shows promise as having equivalent or higher 

erosion control potential than regular straw mulch (Forest Concepts, 2004) 

Thermal techniques are being tested or used with some success throughout Region Six by 

such agencies as Oregon Department of Transportation (ODOT), the Nature Conservancy and 

the Bureau of Land Management (BLM). ODOT has converted a mowing unit to a thermal 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

heat unit for treating roadsides (Prull personal communication, 2004). It has been most 

successful when used for maintenance treatments instead of initial treatments. The Nature 

Conservancy (Tu et al., 2002) tested the Eco-Weeder, an infrared technology device that uses 

the combustion of liquid gas to reach extremely high temperatures that place intense radiation 

directly on weeds to explode plant cells. The tool could be useful for small area treatments, 

especially on sidewalks, but the effectiveness on deep-rooted plants, sedges or rhizomatous 

grasses may not be as high. The Nature Conservancy also tested hot water pressure washers. 

The brand tested could apply hot water through a pressure nozzle with a wide spray or intense 

stream which would act as an injection device for below ground portions of plants. They 

found it effective on seedlings and annual plants within reach of the washer, but the 

effectiveness on plants with extensive underground roots or rhizomes would be less. 

Hot foam has been tested by the Nature Conservancy and used by the BLM effectively on 

puncturevine and slender false brome. Again, this technique is limited to the reach of the 

foam generator, but is an excellent non-chemical method. It is effective on seedlings and 

annuals and can be applied under weather conditions including wind and light rain. It has 

shown some success with perennials and an injection tool has shown some success with 

knotweeds (Fairchild personal communication, 2004). 

Total acres of invasive plants treated in the Region with manual method were 11,167 in 2000, 

and 4,351 in 2001. Total acres of invasive plants treated in the Region using mechanical 

equipment were 555 in 2000, and 641 in 2001. 

See Appendix J for effects of these non-herbicide methods on non-target species. 

Cultural Methods 

Cultural methods of invasive plant management are generally targeted toward enhancing 

desirable vegetation to minimize invasion. Common cultural treatments include planting or 

seeding desirable species to shade or out-compete invasive plants, applying fertilizer to 

desirable vegetation, and controlled grazing. 

Native plant species usually do not out-compete invasive plants in disturbed habitat. 

Herbicide application after invasive plants have emerged, followed by tillage and drill 

seeding, can be effective in establishing desirable species on some sites (Sheley and Petroff, 

1999). This process, however, can lead to increased soil compaction (DiTomaso, 1999), and 

cannot be conducted on steep, remote, or rocky sites. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Seeding risks introduction of non-native and/or invasive species, but use of certified weedfree seed reduces this risk. The magnitude of the risk varies and may be determined by seed 

source, cleaning practices, and other factors (see Site Restoration/Revegetation for more 

discussion). 

Fertilization has had limited use in invasive plant management. It has been used on 

hawkweed species experimentally. Soluble nitrogen fertilizer applied after herbicide 

treatment could increase the competitiveness of perennial grasses and beneficial forbs. This 

method is most effective in pastures or rangelands where nitrogen levels are not high enough 

for optimum grass performance (Rinella and Sheley, 2002). 

Grazing can be used to manage several invasive plant species successfully. Grazing animals 

prefer certain forage, and selective use of preferred forage can shift the competitive balance of 

plant communities (Crawley, 1983; Lukan, 1990). For example, goats and sheep have been 

used in various areas for controlling knapweed and leafy spurge. Controlled, repeated grazing 

of spotted knapweed by sheep has been found to reduce the number of 1 and 2-year old 

spotted knapweed plants within an infestation (Olson et al., 1997). Sheep have been shown to 

provide control for cheatgrass if grazed twice after winter rosettes have greened up (Mosley, 

1996). Goats have been used to successfully control Himalayan blackberry using high 

stocking levels in small fenced areas (Peters personal communication, 2004). Other species 

including gorse, bull and Canada thistle, scotch broom, yellow starthistle and perennial 

pepperweed are being grazed mostly by goats under different grazing strategies. Efforts for 

these species were combine with sheep grazing, herbicide treatment, biocontrols and planting 

competitive vegetation. The breed, sex, age of the animal and timing of grazing as it related 

to weed development and desired vegetation development were important factors in the 

design of an effective grazing prescription for these species (Peters personal communication, 

2004). 

Appropriate grazing by animals preferring invasive species can shift the plant community 

toward more desired grasses (Lacey et al., 1989). Olson (1999) described three grazing 

strategies for managing weeds: (1) moderate grazing levels to minimize the physiological 

impact on native plants and to reduce soil disturbance; (2) intensive grazing to counteract 

inherent dietary preferences of cattle, resulting in equal impacts on forage species including 

weeds; and (3) multi-species grazing that distributes the impact on livestock grazing more 

uniformly among desirable and undesirable species. 

Use of grazing animals as an invasive plant management tool must be based on selecting the 

appropriate grazer for the target invasive plant species. Managers must also determine when, 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

how much, and how often to graze animals to have maximum impact on the invasive plant 

with minimum impact on desirable plant species (Olson, 1999). Research has been occurring 

through the collaborative program BEHAVE (Behavioral Education for Human, Animal, 

Vegetation and Ecosystem Management) which includes partners from the Universities of 

Idaho, Utah, Arizona and Montana State University, and the National Wildlife Research 

Center. Studies on the relationships between animal condition and circumstance and their 

propensity to graze weedy plants is one focus as well as how age and body condition can 

affect consumption (Utah State University, 2004). Specific research tied to this program also 

includes focus on providing incentives such as molasses to get animals to eat weeds and 

supplying anti-toxins to conteract the negative effects of weeds on animals. 

Grazing to manage weeds on roadsides, trailheads, and larger infestations on the forest is 

limited because of the difficulty of maintaining and managing the animals. A long-term 

commitment to small ruminant grazing is necessary for effective invasive plant management. 

Invasive plants can compensate quickly after the grazing pressure is removed because their 

seeds are long-lived in the soil, and because they can rapidly increase flower stem production 

once grazing pressure is removed (Olson et al., 1997 cited in Sheley et al., 1999). 

Most often, though, a single method is not effective to achieve substantial control of a range 

weed. A Successful long-term management program should be designed to include 

combinations of mechanical, cultural, biological, and chemical control techniques (DiTomaso, 

2000). 

Total acres of invasive plants treated with cultural methods were 317 in 2001 and none were 

reported for 2000. 

See Appendix J for effects of these non-herbicide methods on non-target species. 

Prescribed Fire Methods 

Use of prescribed burning for treatment of invasive plants has had limited application in 

Region Six. While fire is sometimes necessary to prompt the germination of some plant 

seeds, such as knobcone pine, fire can also cause sprouting of invasive plants, and create site 

conditions that are optimum for the spread of invasive plants. On the other hand, fire can 

sharply reduce the abundance of some species by preventing flower or seed set, destroying 

seeds, stimulating germination (for future seedling treatments), depleting carbohydrate 

reserves or killing perennating tissue (such as rhizomes, bulbs, or buds) (Rice, 2004). Fire 

can also be used to facilitate revegetation, increase herbicide efficacy, and remove litter to 

assist in emergence of desirable species (Rice, 2004) The weather, topography, and available 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

fuel will determine the temperature and intensity of the prescribed burn this along with the 

timing of the treatment, largely determine how the burn impacts the vegetation and the 

abundance of particular species. Studies cited in a literature review concerning the use of fire 

as a tool for controlling non-native invasive plants provides insight on such factors (Rice, 

2004). 

The effectiveness of fire as a tool is variable. Numerous research was cited in Rice (2004) 

regarding this effectiveness. Most studies focused on grassland habitats primarily in the Mid 

west, but some valuable information for western states was included. For example, fire was 

used as a means to stimulate germination from a persistent seedbank of French and scotch 

broom species. This allows for follow-up treatments of seedlings over the two to three years 

needed for the new plants to develop seeds. Burning killed some seed and stimulated 

germination through scarification of other seeds in lab and field experiments (Bossard 1993, 

2000). This was more successful in drier conditions than wetter conditions (Parker, 2001). 

The most effective fires for controlling invasive plant species are typically those administered 

just before flower or seed set, or at the young seedling/sapling stage. This timing may 

interfere with important growth periods for native species, though. Sometimes prescribed 

burns suppress an invasive species only as a side effect. In some cases, prescribed burns can 

unexpectedly promote other invasives, such as when their seeds are specially adapted to fire, 

or when they resprout vigorously which emphasizes the need for repeated burning (studies 

cited in Rice, 2004). Burning in the fall did show some success in reducing cover scotch 

broom in western Washington, but frequent burning would still be required (Tveten and 

Fonda, 1999). 

Many prescribed burn programs are designed to reduce the abundance of certain native woody 

species that spread into unburned pinelands, savannas, bogs, prairies, and other grasslands. 

Repeated burns are sometimes helpful in controlling invasive plants. Herbicide treatments 

may be required as a follow-up treatment to kill the flush of seedlings that germinate 

following a burn. 

Use of prescribed fire will also change soil chemistry and composition. Likewise, invasive 

seeds may germinate and some invasives will aggressively sprout after fire. Fire may 

encourage invasive plants even in communities that have evolved with fire. This could 

happen because plant communities develop not in association with fire per se, but with a 

particular fire regime. If the fire regime has been altered, vulnerability to exotic plant 

invasion increases (Keeley, 2001). Given these confounding factors, a combination of 

treatments (such as fire and herbicide or fire and manual) would be most successful. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Flaming is a tool of use for controlling invasive plants. Flaming is done with the use of 

propane torches. Such torching tools have been available for agricultural and roofing use. 

They can be purchased as portable backpack units. Flaming destroys cell structure in the 

plant, therefore reducing its energy towards growth. It will kill most small weeds and will at 

least stunt or kill larger weeds, depending on their root system (Flame Engineering, no date). 

Flaming is limited to conditions that would be too moist to carry a fire. They are useful for 

spot burning single plants or a small population of plants with little disturbance to the 

surrounding vegetation (Tu et al., 2001) 

Total acres of invasive plants treated in the Region with prescribed fire were 1,149 in 2000 

and 174 in 2001. 

See Appendix J for effects of these non-herbicide methods on non-target species. 

Biological Control 

For the purposes of this document, biological control is the deliberate use of natural enemies 

(parasites, predators, or pathogens) to reduce weed densities. Biological control is used when 

invasive plant populations have become so large that eradication or control is no longer 

deemed possible. The use of biological control agents reduces invasive plant vigor, and is an 

attempt to make an invasive plant a minor component of its newly adopted community. 

Introduced plants without desirable close relatives in the United States are generally chosen 

for biological control. Natural enemies that are restricted to one or a few closely related 

plants in their country of origin are targeted for biological control (Center et al., 1997; Hasan 

and Ayres, 1990). 

APHIS must approve the entry of all biological control agents into the United States (see 

Appendix J “Effects of non-herbicidal methods of invasive plant treatments” for a thorough 

discussion of testing). A Technical Advisory Group (TAG); consisting of representatives 

from all federal agencies with interests in invasive plant biological control) assists researchers 

and APHIS officials responsible for issuing permits for proposed biological control agents, 

throughout the biological testing and agency approval process. Once APHIS has approved 

entry into the United States, interstate movement of plant pests requires a USDA Plant 

Protection and Quarantine (PPQ) permit. Permits are only approved for states that have been 

covered by an Environmental Assessment and Endangered Species Act consultation. In 

addition, individual state departments of agriculture may also require permits for entry (all 

four states in the Pacific Northwest Region require permits). 

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All agents considered for use in the United States undergo rigorous testing, designed to ensure 

that introduced biological control agents are limited in range and do not threaten native, 

nursery, or crop plants. This testing also limits the introduction of organisms that will not 

survive or be ineffective on the target invasive plant. During testing non-target plants likely 

to be hosts are identified and tested for impacts. The host-specificity of organisms closely 

related to the proposed agent is examined to provide insight on the variability of life history 

traits and the possible breadth of host ranges. For more information, see Appendix H and 

Test Plant Lists at www.aphis.usda.gov/ppq/permits/tag. In addition to federal and state 

regulations, the International Code of Best Practices for biological control of weeds 

(Balciunas and Coombs, 2004) provides guidelines for all practitioners involved in 

redistributing agents. 

Climatic and biotic constraints on proposed agents are examined by studying the native 

habitat of the agent and that of the target invasive plant in the United States (including studies 

on exposure, elevation, temperature, humidity and host density, size or availability). If a 

proposed agent affects native or agricultural plants, it must be demonstrated that the candidate 

agent will not harm the population of desirable plants based on growth habit, climate, or 

geography (see, for example, Spencer and Prevost, 1993; USDA-APHIS, 2003). 

Management with biological agents is a slow process that reduces the vigor of the target and 

does not eradicate the invasive plant population. Biological agents may be ineffective without 

being integrated with other strategies. Researchers estimate 15 to 29 percent of biological 

control programs have been successful (DeLoach, 1991; Meyers et al., 1989). An invasive 

plant infestation may increase in density and area faster than the newly released biological 

agent populations; therefore, other control methods may need to be used in conjunction with 

the release of biological agents, such as herbicide spraying along the perimeter of the 

infestation. Total acres of invasive plants in the Region treated with biological control 

methods were 1,813 in 2000 and 889 in 2001. 

See Appendix J for effects of these non-herbicide methods on non-target species. 

Herbicides 

Refer to the following terminology box for terms and concepts about herbicides and risk 

assessments. 

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Terminology

Allometric= pertaining to allometry; the study of growth of one part in relation to growth of the whole organism. 

Bioconcentration = the net accumulation of a substance by an aquatic organism as a result of uptake directly 

from aqueous solution. 

Bioaccumulation = the net accumulation of a substance by an organism as a result of uptake directly from all 

environmental sources and from all routes of exposure (primarily from food or water that is ingested). 

Gavage = a method of dose administration; the substance is placed directly in the stomach, sometimes in a 

gelatin capsule. 

LOAEL = Lowest-observed-adverse-effect level; lowest exposure associated with an adverse effect. 

NOEL = No-observed-effect level; no effects attributable to treatment. 

NOAEL = No-observed-adverse-effect level: An exposure level at which there are no statistically or biologically 

significant increases in the frequency or severity of adverse effects between the exposed population and its 

appropriate control; some effects may be produced at this level, but they are not considered as adverse, or as 

precursors to adverse effects. In an experiment with several NOAELs, the regulatory focus is primarily on the 

highest one, leading to the common usage of the term NOAEL as the highest exposure without adverse effects. 

NOEC = No-observed-effect concentration; synonymous with NOEL. 

Persistent herbicide = a herbicide that, when applied at the recommended rate, will interfere with regrowth of 

native vegetation for an extended period of time. 

Potency = the measure of the relative strength of a chemical. 

RfD: Reference Dose, a numerical estimate of a daily exposure to the human population, including sensitive 

subgroups such as children, that is not likely to cause harmful effects during a lifetime. RfDs are generally used 

for health effects that are thought to have a threshold or minimum dose for producing effects. 

Selected herbicide = a chemical that is more toxic to some plant species than to others. 

Surfactant = surface acting agent; any substance that when dissolved in water or an aqueous solution reduces its 

surface tension or the interfacial tension between it and another liquid. 

Surrogate = a substitute; lab animals are substituted for humans or other wildlife in toxicity testing. 

a.e. = acid equivalent 

a.i. = active ingredient 

kg = kilogram, equivalent to 2.2 pounds 

g = gram, equivalent to about 0.03 ounce (28 g = 1 ounce) 

ppm = part(s) per million; equivalent to mg/L 

mg/L = milligrams per liter; equivalent to ppm 

ppb = part(s) per billion 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Herbicide treatment consists of applying chemicals, usually of a manufactured or synthetic 

origin, to a plant or to soil. The plant absorbs the herbicide through roots, leaves, or stems. 

The herbicide interferes with plant metabolic processes, stopping growth and usually killing 

the plant. A suite of available herbicides is needed to help meet the variety of long-term site 

goals and address the complex resource issues at the Forest level. Different herbicides vary in 

effectiveness and length of control on different invasive plants. Herbicides also vary in their 

effects to the environment and suitability to different environmental conditions. 

Herbicides vary in their environmental activity, physical form, and the equipment used to 

apply them. In combination with other site and biological factors, these characteristics 

influence both the probability of meeting site-specific goals for invasive plant control, and the 

potential of impacting non-target components of the environment. Soil properties impact the 

effectiveness of invasive plant treatment and restoration actions as well. 

Herbicides may be selective or non-selective. This means they control all types of vegetation 

(non-selective), or they selectively control either some broadleaf plants or grasses while not 

affecting others (selective). Some herbicides may control only actively growing vegetation at 

the time of application, or they may provide invasive plant control through root uptake from 

the soil (short-term to over a few years). In soil and water, herbicides may persist or 

decompose by sunlight, microorganisms, or other environmental factors. 

Herbicides vary in selectivity of control for various plant groups. Those differences in 

selectivity are the basis for developing effective invasive plant control prescriptions while 

minimizing adverse effects and facilitating native plant community maintenance or 

restoration. Another variation among herbicides is the duration of control of the target 

invasive plant. Label application restrictions can also limit the number of herbicides available 

to control any site-specific invasive plant infestations. 

Physical form of herbicides varies. Some may be oil- or water-soluble molecules dissolved in 

liquids, or attached to granules for dry application to soil surface. Herbicides may move from 

their location of application through leaching (dissolved in water as it moves through soil), 

volatilization (moving through air as a dissolved gas), or adsorption (attached by molecular 

electrical charges to soil particles that are moved by wind or water). 

Herbicides may be applied with a variety of equipment and techniques. The techniques vary 

in effectiveness, environmental effects, and costs. Helicopters or fixed-wing aircraft are used 

for aerial application of sprays or granules for rapid broadcast coverage of large or 

inaccessible areas. 

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Herbicides may be sprayed via ground vehicles with hose sprayers or booms using an array of 

spray nozzles. This equipment is most commonly used for broadcast spraying of roads, but 

can also be used on all-terrain vehicles for broadcast or spot spray in remote areas. 

Some application equipment is often used for selective treatment and/or to minimize nontarget effects. Backpack sprayers are most frequently used to spray the foliage, stem, and/or 

surrounding soil of target invasive plants. Other equipment includes herbicide-soaked wicks 

or paintbrushes for wiping target vegetation, and lances, hatchets, or syringes for injection of 

herbicide into stems of target plants. Granular herbicides may be applied using hand-held 

seeders, or other specialized dispensing devices. 

Each herbicide is sold as one or more commercial products, called formulations. The product 

label for herbicide formulation provides legally binding direction on its use, including safe 

handling practices, application rates, and practices to protect human health and the 

environment. 

Table 3-13 lists the herbicides included in this EIS. These herbicides or formulations are 

registered by the EPA for use in forestry applications, right-of-ways, or rangelands and are 

appropriate for use against invasive plant species in Oregon and Washington. The 

characteristics listed are meant to give a general overview of the capabilities of each 

herbicide. More details on these herbicides can be found in the commercial labels provided 

on all EPA approved products and the Pacific Northwest Weed Management Handbook 

(Oregon State University, 2002). A document developed for this analysis, Common Control 

Measure for Invasive Plants of the Pacific Northwest Region (Mazzu, 2004) (see link in 

Appendix N) summarizes the vast information available on invasive plants control using 

resources from numerous authorities such as the Nature Conservancy, State noxious weed 

programs or county noxious weed coordinators. 

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Table 3-13 Herbicides included in this EIS and analyzed in Chapter 4. 

Chemical/Selected Brand 

Names/Action Properties General Uses/Known to be Effective on: 

Chlorsulfuron 

(Telar,Glean,Corsair)/ 

Sulfonylurea-Interferes with 

enzyme acetolactate synthase 

w/ rapid cessation of cell 

division and plant growth in 

shoots and roots. 

Glean -Selective pre-emergent or 

early post-emergent 

Telar – Selective pre- and postemergent. 

Both are for many annual, biennial 

and perennial broadleaf species. 

Safe for most perennial grasses, 

conifers. Some soil residue. 

Use at very low rates on annual, 

biennial and perennial species; 

especially dalmation toadflax, and 

houndstongue and perennial 

pepperweed. 

Clopyralid 

(Transline)/ 

Synthetic auxin -Mimics 

natural plant hormones. 

A highly translocated, selective 

herbicide active primarily through 

foliage of broadleaf species. Little 

effect on grasses. 

Particularly effective on Asteraceae, 

Fabaceae, Polygonaceae, 

Solanaceae. Some species include 

knapweeds, yellow starthistle, 

Canada thistle, hawkweeds. 

Provides control of new germinants 

for one to two growing seasons. 

Dicamba 

(Banvel , Vanquish) 

Synthetic auxin -Mimics 

natural plant hormones. 

Used for the control of a variety of 

broadleaf and woody vegetation. 

Banvel is more likely to generate 

dicamba vapor than Vanquish. 

Selective against many annual and 

perennial broadleaf species 

including woody and vine species 

(e.g. gorse, hawkweeds, tansy 

ragwort). 

Glyphosate 

(RoundUp, Rodeo etc.)/ 

Inhibits three amino acids and 

protein synthesis. 

A broad spectrum, non-selective 

translocated herbicide with no 

apparent soil activity. 

Adheres to soil which lessens or 

retards leaching or uptake by nontargets. 

Low volume applications are most 

effective. Translocates to roots and 

rhizomes of perennials. While 

considered non-selective, 

sensitivities do vary depending on 

species. Main control for purple 

loosestrife, herb Robert, English ivy 

and reed canarygrass. Aquatic 

labeled formulations can be used 

near water. 

Imazapic 

(Plateau)/Inhibits the plant 

enzyme acetolactate, which 

prevents protein synthesis. 

Used for the control of some 

broadleaf plants and some grasses. 

Use at low rates can control leafy 

spurge, cheatgrass, medusa head 

rye, toadflaxes and houndstongue 

Imazapyr 

(Arsenal, Chopper, Stalker 

Habitat)/ Inhibits the plant 

enzyme acetolactate, which 

prevents protein synthesis. 

Broad spectrum, non-selective preand post-emergent for annual and 

perennial grasses and broadleaved 

species. 

Most effective as a post-emergent. 

Has been used on cheatgrass, 

whitetop, perennial pepperweed, 

dyers woad, tamarisk, woody 

species, and spartina. Aquatic 

labeled formulations can be used 

near water. 

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Table 3-13 Herbicides included in this EIS and analyzed in Chapter 4. 

Chemical/Selected Brand 

Names/Action Properties General Uses/Known to be Effective on: 

Metsulfuron methyl 

(Escort)/ Sulfonylurea -

Inhibits acetolactate synthesis, 

protein synthesis inhibitor, 

block formation of amino 

acids. 

Used for the control of many 

broadleaf and woody species. Most 

susceptible crop species in the Lily 

family (i.e. onions, Allium). 

Safest sulfonylurea around non-target 

grasses. 

Use at low rates to control such 

species as houndstongue, sulfur 

cinquefoil perennial pepperweed. 

Picloram 

(Tordon) 

Restricted Use Herbicide 

Synthetic auxin - Mimics 

natural plant hormones. 

Selective, systemic for many annual 

and perennial broadleaf herbs and 

woody plants. 

Use at low rates to control such 

species as knapweeds, Canada 

thistle, yellow starthistle, 

houndstongue, toadflaxs, sulfur 

cinquefoil, and hawkweeds. 

Provides control of new germinants 

for two to three growing seasons. 

Sethoxydim 

(Poast)/ Inhibits acetyl coenzyme, a key step for 

synthesis of fatty acids. 

A selective, post-emergent grass 

herbicide. 

Will control many annual and 

perennial grasses such as 

cheatgrass. 

Sulfometuron methyl 

(Oust)/ Sulfonylurea -Inhibits 

acetolactase synthase, a key 

step in branch chain amino 

acid synthesis. 

Broad spectrum pre- and postemergent herbicide for both 

broadleaf species and grasses. 

Used at low rates as a pre-emergent 

along roadsides. Known to be 

effective on canary reedgrass. (but 

not labeled for aquatic use) 

cheatgrass, medusahead. 

Triclopyr 

(Garlon, Pathfinder, Remedy)/ 

Synthetic auxin - Mimics 

natural plant hormones. 

A growth regulating selective, 

systemic herbicide for control of 

woody and broadleaf perennial 

weeds. 

Little or no impact on grasses. 

Not for broadcast application under 

proposed action. Effective for 

many woody species such as scotch 

broom and blackberry. Also 

effective on English ivy, Japanese 

knotweed. Amine formulation may 

be used near water 

2,4-D 

(Weedone, Weedar, many 

more) 

Synthetic auxin - Mimics 

natural plant hormones. 

Readily absorbed and metabolized. 

Used for the control of many 

broadleaf species. 

Effective for many broadleaf 

species (such as Canada thistle, 

Russian knapweed, sulfur 

cinquefoil, hoary cress). Aquatic 

labeled formulations can be used 

near water. 

Risk information found in SERA documents (2,4-D 1998, Triclopyr 2003, Picloram 2003, Sethoxydim 2001, 

Glyphosate 2003, all others 2004) for each active ingredient. Information on species effectiveness in Tu et al. 

(2001) or from product labels. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

The Decision to Use Herbicides 

The choice of whether an herbicide is used over other control methods would be based on 

integrated weed management principles. Decisions would be made based on whether other 

methods or combination of methods are known to be effective on the species in similar 

habitat. The choice of herbicide would be based on the invasive species; how it reproduces, 

its seed viability, the size of its population, site conditions, known effectiveness under similar 

site conditions and the ability to mitigate effects on non-target species. 

In most cases, if an herbicide is selected, it would be used in combination with other methods. 

For example, initial treatment on an invasive species may be done by an herbicide, but then 

manual or mechanical methods would be implemented as maintenance treatments over the 

long term. Large established populations would be less apt to undergo herbicide treatment. 

Such populations may be controlled at their perimeters to maintain “weed-free” zones or may 

be candidates for biological control. The focus of any herbicide treatment would be on the 

species of highest concern (see Chapter 3.1) where the negative effects can be mitigated. 

Application methods used would be based on site accessibility. Aerial spraying, for example, 

would only be used in areas where access is remote and difficult and populations are of the 

size that non-herbicide methods or selective herbicide application are not feasible. 

Herbicide Resistance 

Herbicide resistance is the heritable (genetic) ability of an individual plant to survive a 

herbicide application to which the wild-type population is otherwise susceptible. Resistant 

individuals remain reproductively compatible with the wild-type, and may confer genetic 

resistance to their offspring. Non-native invasives that exhibit herbicide resistence are 

generally annual species (PNW Weed Management Handbook, 2004). 

Resistance may occur in plants by random and infrequent mutations. Through selection, 

where the herbicide is the selection pressure, susceptible plants are killed while herbicide 

resistant plants survive to reproduce without competition from susceptible plants. If the 

herbicide is continually used, resistant plants successfully reproduce and become dominant in 

the population. Thus the appearance of herbicide resistance in the populations is an example 

of rapid weed evolution (Prather et al., 2000). There are two pre-requisites for the evolution 

of herbicide resistance in an invasive plant population: the occurrence of heritable variation 

for resistance and selection for increased resistance by herbicide application (Cousins and 

Mortimer, 1995). 

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Herbicide resistance was first reported in 1957 in California with common groundsel (Senecio 

vulgaris) (Prather et al., 2000). Development of resistance occurs mostly in croplands where 

repeated applications of a single herbicide select for resistant survivors. However, resistance 

is known to occur in a few wildland invasives of concern in the Pacific Northwest, including 

yellow starthistle resistance to picloram and clopyralid (Fuerst et al., 1996; Sabba et al., 

2003). A resistant biotype was observed in Washington in a pasture subjected to intensive 

picloram selective pressure. Reports of resistant strains of perennial ryegrass (Lolium 

perenne) to sulfometuron methyl, Russian thistle (Salsola tragus) to chlorosulfuron and 

sulfometuron and rigid ryegrass (Lolium rigidum) to glyphosate have been found in California 

(Prather et al, 2000). Other resistant species were reported but not documented here since the 

herbicides of concern were not a part of this EIS. 

Resistance to glyphosate is debated in the literature (Owen and Zelaya, 2005). Arguments 

indicate that not only would the evolution of glyphosate resistance be an issue, but also weed 

populations shifts would occur in response to the adoption of glyphosate-resistant crops. For 

example, evolved glyphosate resistance was identified in horseweed (Conyza Canadensis (L)

Cronq) three years after the adoption of glyphosate-resistant soybeans (VanGessel, 2001). In 

field situations, resistance to sulfonylurea herbicides has been reported to occur after 3 to 5 

years of repeated use (Gunsolus, 1999). 

Herbicide factors that contribute to the potential for resistance include long soil residual 

activity, single target site and specific mode of action, and high effective kill of a wide range 

of weed species. All of these factors rapidly deplete susceptible genes from the population 

(Prather et al., 2000). Resistance is avoided or overcome by having multiple herbicides with 

different modes of action (plant-killing chemistries) available for use (PNW Weed 

Management Handbook, 2003). The use of short-residual herbicides also reduces selection 

pressure for herbicide resistance as well as integrating non-herbicide control techniques into a 

weed management program (Prather et al., 2000). 

The repeated use of one herbicide allows these few resistant plants to survive and reproduce. 

As the number of resistant plants increases, the efficacy of the herbicide diminishes until the 

herbicide no longer effectively controls the invasive plant populations. Where repeated 

herbicide use is predicted to be necessary to meet control objectives, strategies must be 

designed to minimize risk of developing resistance. 

To develop resistance avoidance strategies, long-term site plans should recognize which of the 

various herbicide families have available and effective herbicides if multiple applications are 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

expected to be necessary. Integrated chemical and non-chemical controls are highly effective 

where feasible because any surviving herbicide resistant plants can be removed from the site. 

Herbicide Risk Assessments 

As herbicides have the potential to adversely affect the environment, the U.S. Environmental 

Protection Agency (EPA) must register all herbicides prior to their sale, distribution, or use in 

the United States. In order to register herbicides for outdoor use, the EPA requires the 

manufacturers to conduct a lab evaluation of potential hazards to humans and on wildlife 

including toxicity testing on representative species of birds, mammals, freshwater fish, 

aquatic invertebrates, and terrestrial and aquatic plants. An ecological risk assessment uses 

the data collected to evaluate the likelihood that adverse ecological effects may occur as a 

result of herbicide use. 

The effects from the use of any herbicide depends on the toxic properties (hazards) of that 

herbicide, the level of exposure to that herbicide at any given time, and the duration of that 

exposure. The risk from herbicide use can be reduced by reducing exposure through sitespecific project design criteria, such as the use of streamside buffer zones, personal protective 

equipment for applicators, and posting of treated areas. Treatments under all alternatives 

would be accomplished according to strict safety and health standards. 

The Forest Service conducts risk assessments independent from EPA valuations for herbicide 

registration, focusing specifically on the type of herbicide uses in forestry applications. 

Estimates of potential environmental and human health risks for each herbicide as proposed 

for use in this EIS are based on herbicide risk assessments prepared for the Forest Service. 

The Forest Service contracts with Syracuse Environmental Research Associates, Inc. (SERA) 

to conduct human health and ecological risk assessments for herbicides that may be proposed 

for use on National Forest System lands. All toxicity data, exposure scenarios, and 

assessments of risk are based upon information in the Forest Service/SERA Risk Assessments 

unless otherwise noted. 

Forest Service/SERA Risk Assessments use peer-reviewed articles from the open scientific 

literature and current EPA documents, including Confidential Business Information. Specific 

methods used in preparing the Forest Service/SERA Risk Assessments are described in 

SERA, 2001-Preparation. Only information that is not derived from the relevant Forest 

Service/SERA Risk Assessments is specifically cited in this section. The risk assessments 

and associated documentation is available in total in the administrative record for this EIS. 

Estimates of risk are not absolute; rather, they are relative and based on assumptions and 

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evolving toxicity data. Risk assessments have inherent limitations; these are discussed later in 

this chapter. 

Toxicity studies were evaluated individually for scientific quality, and cumulatively for all 

similar studies to identify the No observed adverse effects level (NOAEL) and Reference 

Dose (RfD) for the most sensitive adverse effect on the test organism. Each Forest 

Service/SERA Risk Assessment contains citations for all studies that are reviewed. 

In addition to the analysis of potential hazards to human health from every herbicide active 

ingredient, Forest Service/SERA Risk Assessments evaluate any available scientific studies of 

potential hazards of these other substances associated with herbicide applications: impurities, 

metabolites, inert ingredients, and adjuvants. There is usually less information available on 

these substances (compared to the herbicide active ingredient) because they are not subject to 

the extensive testing that is required for herbicide active ingredients under FIFRA (Federal 

Insecticide, Fungicide, and Rodenticide Act). 

Other chemicals associated with the application of herbicides (Impurities, Metabolites, and 

Inert Ingredients) are discusses in Appendix Q. Potential human risk and environmental 

effects are analyzed in relevant sections of Chapter 4 and Appendices. 

Limitations of Risk Assessments 

The analysis in Chapter 4 refers extensively to Forest Service risk assessments (prepared by 

SERA, Inc.) for every herbicide considered in the alternatives. Risk assessments use 

information from laboratory and field studies of herbicide toxicity, exposure, and 

environmental fate to estimate the risk of adverse effects to non-target organisms. Risk 

assessments are often used to inform decision makers, notwithstanding the presence of some 

degree of uncertainty inherent in any methodology used to assess risk. When used in 

conjunction with information on local conditions and specific treatments, risk assessments 

become a more precise tool. There are advantages and disadvantages to the risk assessment 

process as it relates to natural resources. 

Advantages of risk assessment include: providing quantitative bases for comparing and 

prioritizing risks of alternatives; providing to decision makers and the public an estimate of 

the risk of the occurrence of an adverse effect under typical and extreme scenarios. 

Disadvantages include a high degree of uncertainty in interpretation and extrapolation of data. 

Uncertainty may result from a study design, questions asked (and questions avoided), data 

collection, data interpretation, and extreme variability associated with aggregate effects of 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

natural and synthesized chemicals on organisms, including humans, and with ecological 

relationships. Numbers used, particularly in ecological realms, are uncertain, and there are 

limits on our ability to understand or demonstrate causal relationships. Because of data gaps, 

assessments rely heavily on extrapolation from laboratory animal tests (Funke, 1995). 

Regardless of disadvantages and limitations of ecological and human health risk assessments, 

the analysis provided by Forest Service/SERA Risk Assessments is the most current and 

thorough that is available. Risk assessments can determine (given a particular set of 

assumptions) whether there is a basis for asserting that a particular adverse effect is plausible. 

The bottom line for all risk analyses is that absolute safety can never be proven and the 

absence of risk can never be guaranteed (SERA, 2001). 

Summary of Treatment Methods 

Table 3-14 summarizes some key points regarding the treatment methods. 

Table 3-14 Summary of Treatment Methods 

Treatment 

Method Discussion/Considerations 

Cultural 

Competitive Most effective after weed populations have been reduced by other control actions. 

Seeding 

Must match the species with the appropriate grazer for best success; treatment 

must occur during proper phenological stage; herding required; sometimes 

nonselective. 

Grazing Animals 

Could improve the success of desirable species; may be limited depending on 

species/soil characteristics. Fertilization 

Manual/Mechanical 

Mowing-Weed 

Whipping 

Limited to level and gently sloping smooth-surface terrain. Must be conducted 

for several consecutive years; treatment timing critical. 

Labor intensive; not effective on deep-rooted or rhizomatous perennials; causes 

ground disturbance that may increase susceptibility of site to reinvasion by weeds; 

effective on single plants or small, low-density infestations. 

Hand-Pulling 

/Grubbing 

Hot Foaming and 

other Thermal 

Methods 

Effective for spot burning single plants or small populations. Limited to 

conditions that would be too moist to carry a fire 

Most effective on seedlings and annuals; some success with perennials. Foaming 

and hot water techniques limited in distance to the reach of the applicator. Foaming 

Variable effectiveness. Most use has been in grassland restoration. May cause 

resprouting or stimulated germination of the treated vegetation. Most effective in 

combination with other treatments 

Prescribed Fire 

Biological Control 

Parasites, 

Predators, and 

Pathogens 

Most effective when integrated with other strategies; does not achieve eradication; 

not effective on all invasive plants; long term process required. 

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Table 3-14 Summary of Treatment Methods 

Treatment 

Method Discussion/Considerations 

Herbicides 

Not cost-effective on steep slopes; application timing limited based on plant 

phenology and weather conditions. Most appropriate for small, relatively 

accessible infestations, and areas where controlling off-site drift is critical. 

Ground 

Application 

Potential for off-site drift must be considered; application timing limited based on 

plant phenology and weather conditions. Most appropriate for large, relatively 

inaccessible infestations. 

Aerial Application 

Site Restoration/Revegetation 

Site restoration or revegetation is part of any long term strategy to reduce invasive plants. 

Determining the need for active restoration/revegetation versus passive restoration (allowing 

plants on site to fill in a treated area) is the first choice when addressing this need. Passive 

restoration may be appropriate where treated sites leave only small gaps of bare ground and 

native vegetation on site can provide adequate seed source to fill in such gaps. 

Promoting the establishment of desirable plant communities through the manipulation of 

species composition, plant density, and growth rate is a critical component of invasive plant 

management (Masters et al., 1996; Masters and Nissen, 1998; Masters and Shelly, 2001; 

Brooks et al., 2004). Three components of succession could be manipulated; site availability, 

species availability, and species performance (Cox and Anderson, 2004). Although single 

control tactics, such as treatment with herbicides, may eliminate or suppress invasive species 

in the short term, the resulting gaps and bare soil create niches that are conducive to further 

invasion by the same or other undesirable plant species. On degraded sites where desirable 

species are absent or in low abundance, revegetation with competitive grasses, forbs, and 

legumes may be necessary to direct and accelerate plant community recovery, and achieve 

site-management objectives in a reasonable timeframe. 

A two step approach, using a model of ‘assisted succession’ was used to accelerate recovery 

in sagebrush steppe invaded by cheatgrass. The first step was to convert a site from annual to 

perennial domination. The second step in the process was to insert native species into the 

stable perennial matrix using such seedbed techniques as tilling or treatment with herbicide 

(Cox and Anderson, 2004). 

The selection of appropriate species for revegetation is dependent on a number of factors, 

including management objectives and site characteristics such as soil texture, 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

precipitation/temperature regimes, and shade conditions. Seed availability and cost, ease of 

establishment, seed production, and competitive ability are also important considerations and, 

as a consequence, resource managers in the western United States have historically relied on 

introduced species that have been selectively bred and marketed for these attributes. 

Although some introduced species will continue to be used in site restoration, the extensive 

past use of highly competitive and persistent non-natives (e.g., smooth brome, orchardgrass, 

timothy, and crested wheatgrass) has had adverse impacts on the diversity and health of our 

native forest, rangeland, and aquatic ecosystems (Romo, 2005; Bartos and Campbell, 1998; 

Covington and Moore, 1994; Detwyler, 1971; Kay, 1994; Lesica and DeLuca, 1996; Mills et 

al., 1994). 

With that said, some success has been found using crested wheatgrass as in the ‘assisted 

succession’ model discussed above (Cox and Anderson, 2004). Success in establishing native 

species varied by precipitation patterns and seed bed preparation in plots dominated by 

crested wheatgrass verses cheatgrass. The study was based in the Great Basin in sagebrush 

steppe and covered only two years of measurements. While success was shown in amount of 

native species to germinate and establish when crested wheatgrass was the dominant species, 

this success was tired to seed bed preparation that created niches for native species 

development. Crested wheatgrass was not expected to be eliminated with such a strategy, but 

diversity, structure and function of the resulting community was considered more similar to 

the original native community. 

Numerous annual or sterile cereal grasses could be used instead of the above persistent nonnatives. For example, cereal wheat, barley, annual ryegrass or sterile wheatgrass have been 

used in restoration efforts. In the case of wildfire recovery (Burned Area Emergency 

Rehabilitation (BAER) programs, some studies are being done to assess the success of 

seeding with these species. Keeley (2004) found that seeding with cereal wheat, at high 

seeding rates, reduced invasive species after two years. The study also found decreases in 

species richness and ponderosa pine seedlings. The dense stands of wheat did appear to 

reduce erosion, but left thick thatch which increased fire hazard at least initially. Such studies 

suggest determining if seeding is necessary and the amount of seed per acre considered 

crucial for reducing disruption to ecosystem processes. 

In order to conserve and enhance the biodiversity and sustainability of wildland ecosystems, 

numerous authorities and policies are in place to promote the use of native species in 

restoration and revegetation. There is debate among restoration practitioners on how close in 

distance and genetics a seed source should be to the restoration site (Kaye, 2001). The 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

definition of what is ‘local’ varies and should be defined through specific project objectives. 

Genetically similar seed may have an advantage because it is from locally adapted plants, but 

could be more costly than using seed from a broader genetic pool such as a watershed or even 

an ecoregion that can be used for many projects. 

The successful use and incorporation of native species, in revegetation of impacted sites will 

require extensive ecological and biological knowledge and expertise in order to meet both 

short-term objectives of attaining adequate amounts and levels of competitive plant cover, and 

long-term objectives of physical and biological site recovery. Although agency knowledge 

and experience base is growing, education and training is still needed. There is also a critical 

need for research efforts that more broadly explore the array and combinations of native 

grasses and forbs that may be useful in restoration/revegetation. The effects of the timing, as 

well as the rate and methods of seeding on sites previously infested with invasive plants, have 

also not been fully examined for most species. 

In relation to the use of native plants, a draft policy for the use of native plant materials is 

currently under internal review. It was developed in response to Executive Order 13148 (the 

Greening of Government Agencies) and interagency, administration and congressional 

interest in developing native plant materials to meet the rising demand for restoration plant 

materials. 

The National Strategy for Invasive Species Management (2004) for the Forest Service also 

encourages the use of native species in rehabilitation and restoration. It encourages the 

shifting of restoration projects from the use of invasive non-natives to other less invasive and 

native species. 

Forest Service Manual 2523.2 under Watershed Protection and Management sets priorities for 

burned area emergency response treatments stating that natural recovery by native species is 

preferred. It states that when practical, use seeds and plants in these project areas that 

originate from genetically local sources on native species or when native materials are not 

available or suitable, give preference to non-native species that meet the treatment objectives, 

are non-persistent and are not likely to spread beyond the treatment area. 

Regional direction for the use of native plants was issued in 1994 with the PNW Revegetation 

policy. It set a long term goal for using native plant species as much as possible. It defined 

an acceptable, non-native as “an annual or short lived perennial that is not persistent or 

competitive with native vegetation that would be useful for erosion control or as noxious 

weed competitors”. 

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CHAPTER 4 ENVIROMENTAL CONSEQUENCES 

 

4.1 Introduction 

The environmental consequences section focuses on the key issues (Chapter 1.6), but also 

includes other issues and required NEPA disclosures. These analyses predicts future response 

to a suite of new management direction. The uncertainty in these predictions is relatively 

high given the complexity of the relationships between land management; uses on and off 

National Forest; the rate of introduction, establishment, and spread of diverse invasive plants; 

and unknown future funding scenarios. Each section in this document discusses how the 

analyst responded to uncertainty. 

Chapter 4 discloses the direct, indirect and cumulative effects of the alternatives on the 

environmental components described in Chapter 3. Broad, programmatic effects are 

considered. Site-specific effects cannot be meaningfully evaluated at a Regional scale, but 

will be addressed in subsequent site-specific NEPA analysis as projects are proposed. In this 

respect, the alternatives have no site-specific effects. Effects analysis in this EIS address what 

generally could occur as a result of invasive plant treatment projects that follow management 

direction under each alternative. 

4.1.1 Basis for Cumulative Effects Analysis 

The National Forests are intermingled with other federal, state, county and private 

ownerships. Herbicides are commonly applied on lands other than National Forest System 

land for a variety of agricultural, landscaping and invasive plant management purposes. 

No central source exists for compiling invasive plant management information off National 

Forests within Oregon and Washington. There is no requirement for private or corporate land 

owners, or counties to report invasive plant treatment information, thus an accurate 

accounting of the total acreage of invasive plant treatment for all land ownerships is 

unavailable. It is estimated that invasive plant control occurs on over 1,250,000 acres in 

Oregon and Washington and 90+ percent of this control is through the use of herbicides 33. 

Even the highest use estimates of herbicide use on National Forest System lands (Alternative 

D) would amount to less than three percent of the estimated total acres treated with herbicides 

in Oregon and Washington. Some of the herbicides proposed in this EIS are frequently 

applied on much larger acreages of agricultural lands. The herbicides imazapic, imazapyr, 

33 Based on informal discussions w/state and county agriculture and weed personnel. Includes all land

ownerships, not including small-scale private use. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

and sulfometuron methyl are not registered for agricultural uses other than rangeland and 

forestry. Landscaping is another large use of some herbicides. Other herbicide use occurs on 

other federal, State, and county ownerships, State and private forestry lands, rangeland, utility 

corridors, and road rights of way. 

The small contribution that Forest Service use of herbicide for invasive plant control makes to 

the statewide totals34 indicates that the potential contribution of Forest Service uses to 

cumulative effect from all herbicide use is very small. 

Table 4-1 displays the projected use of different herbicides on National Forest System lands 

included in the alternatives compared to the estimated total use (all land ownerships) within 

Oregon and Washington. All of the cumulative effects analyses apply this information. 

Table 4-1 Projected Use of Various Herbicides in Oregon and Washington 

Herbicide 

RateTypical 

Lb 

ai/ac 

RateHighest 

Lb 

ai/ac 

Maximum 

acres in 

any 

alternative 

Maximum 

lbs. 

Herbicide 

applied for 

alternatives 

Estimated 

total 

herbicide 

used (lbs) in 

WA+OR 

agriculture in 

1997 

Forest Service use 

of herbicides in

WA/OR as 

compared to twoState totals 

(Typical/worst 

case percentages) 

2,4-D 1.0 2.0 13,765 27,530 2,226,331 0.6%/ 1.2% 

Chlorsulfuron 0.056 0.25 1,147 286 9,358 0.7%/ 3.1% 

Clopyralid 0.35 0.5 4,648 2,324 3,486 5.2%/ 7.4% 

Dicamba 0.3 2.0 688 1,376 245,907 0.1%/ 0.6% 

Glyphosate 2 7 4,649 32,543 1,443,217 0.6%/ 2.3% 

Imazapic 0.1 0.19 3,441 654 0 n/a 

Imazapyr 0.45 1.25 930 1,163 0 n/a 

Metsulfuron Methyl 0.03 0.15 1,147 172 2,771 1.2%/ 6.2% 

Picloram 0.35 1.0 11,050 11,050 17,422 22.2%/ 63.4% 

Sethoxydim 0.3 0.38 930 353 20,569 1.3%/ 1.7% 

Sulfometuron 

Methyl 

0.045 0.38 1,147 435 0 n/a 

Triclopyr 1.0 10 930 9,300 94,075 1.0%/ 9.9% 

Nonylphenol 

Polyethoxylate 

1.67 6.68 n/a n/a 

Source: The National Center for Food and Agricultural Policy (NCFAP) Agricultural Pesticide Use Database 

for 1997. Washington DC. 1998. 

The proposed use of herbicides could result in cumulative doses of herbicides to workers, the 

general public, non-target plant species, and/or wildlife. Cumulative doses of the same 

 

34 National Center for Food & Agricultural Policy (NCFAP). 1997 Pesticide Use Database available online at 

www.ncfap.org/database/state/default.asp. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

herbicide result from (1) additive doses via various routes of exposure resulting from a single 

invasive plant treatment project and (2) additive doses if an individual is exposed to a 

herbicide treatment conducted under this EIS, and to another herbicide treatment. For 

additive doses to occur, the two exposures would have to occur closely together in time, since 

the herbicides proposed for use are rapidly eliminated from humans and do not significantly 

bioaccumulate. Additional sources of exposure include private use of herbicides. 

The potential for synergistic effects (where exposure to a combination of two or more 

chemicals could result in impacts that are greater than the sum of the effects of each chemical 

alone) were considered. Combinations of chemicals in low doses (less than one tenth of the 

RfD) have rarely demonstrated synergistic effects. Review of the scientific literature on 

toxicological effects and toxicological interactions of agricultural chemicals indicate that 

exposure to a mixture of pesticides is more likely to lead to additive rather than synergistic 

effects (ATSDR, 2004.; U.S.EPA/ORD, 2000.). Based on the limited data available on 

chemical combinations involving the twelve herbicides considered in this EIS, it is possible, 

but unlikely, that synergistic effects could occur as a result of exposure to the herbicides 

considered in this analysis. Synergistic or additive effects, if any, are expected to be 

insignificant. More information on this topic is included in Appendix Q: Human Health 

Assessment. 

Amendments to National Forest Plans in Region Six have been recently implemented. In 

March, 2004, the Secretaries of Agriculture and the Interior amended Forest Plans within the 

range of the northern spotted owl by removing the Survey and Management Mitigation 

measure and changing language related to the Aquatic Conservation Strategy. The 

cumulative effects of invasive plant management alternatives were considered in light of these 

other amendments. All invasive plant management alternatives are compatible with the other 

recent Forest Plan amendments. 

One National Forest recently amended its Forest Plan in light of new information related to 

management of Port-Orford-cedar. All invasive plant alternatives are compatible with the 

Port-Orford-cedar management strategy. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

4.2 Effectiveness of Preventing and Reducing the Spread of 

Invasive Plants 

4.2.1 Introduction 

The ability of the Forest Service to meet the purpose and need for action, achieve desired 

future conditions, and contribute to cooperative efforts throughout Oregon and Washington is 

directly correlated to the effectiveness of invasive plant prevention and control strategies in 

each alternative. Public comments associated with this issue focused on whether invasive 

plant treatments would actually succeed in making a difference, given the current level of 

infestation. People requested the Forest Service investigate various land management 

activities that could be causing the introduction and spread of invasive plants. To address this 

issue, white papers were developed to display the best available information regarding 

prevention and treatment effectiveness (see Appendix D). 

Each action alternative would add a Desired Future Condition (DFC) statement, several goals 

and objectives, and invasive plant management standards to Forest Plans in Region Six. 

Individual projects and programs would be designed to contribute to achieving goals and 

objectives35 and required to comply with standards. In this way, the application of standards 

has the greatest potential to affect invasive plant management across the Region. This 

analysis focuses on characteristics of the standards and how they influence the prevention and 

overall reduction of invasive plants. The alternatives vary in their potential to reduce the 

extent and spread of invasive plants, because the standards vary by degree of emphasis on 

prevention, treatment, and restoration/revegetation. 

The measuring factors used for comparing the alternatives are: 

• Relative change in rate of spread by alternative; 

• Estimated acreage of invasive plants treated annually; 

• Number of years until invasive plants are controlled. 

The current approach (No Action alternative) is not likely to effectively prevent or treat 

invasive plants. Alternative B is the most likely alternative to prevent the spread of invasive 

plants, but because it limits use of herbicides, it is the least effective of the action alternatives 

in treating invasive plants. The Proposed Action is less likely to be as effective at preventing 

the spread of invasive plants as Alternative B, but is more likely to effectively treat invasive 

 

35 Individual projects in themselves would not be required to or capable of achieving DFC’s, goals or objectives. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

plants. Alternative D is the least likely of the action alternatives to prevent the spread of 

invasive plants, but most likely to effectively treat invasive plants. A combination of the 

prevention standards of Alternative B and the treatment toolbox included in either the 

Proposed Action or Alternative D would be most likely to effectively prevent and treat 

(control) invasive plants. 

4.2.2 Background 

Past and Current Invasive Plant Control Efforts 

The prevention and management of invasive plants is not new to the Forest Service or other 

federal agencies. As early as 1939, the Federal Seed Act required reporting of percent 

noxious weed seed in seed mixes and listed invasive species of concern in seed mixes (7 USC 

1551-1611). The Federal Noxious Weed Act of 1974 (PL 93-629, Sec. 15) outlined the duties 

of federal agencies including the development of cooperative agreements with state agencies 

to coordinate integrated management of undesirable plant species. 

In 1990, the Department of Agriculture set forth a regulation for the coordination of invasive 

plant management activities among agencies of the USDA and other executive agencies, 

organization and individuals (USDA 9500-10). Forest Service policy was revised in 1995 

(FSM 2080) to emphasize the importance of integrating weed management in ecosystem 

analysis, assessment and forest planning. In 1998, the Federal Interagency Committee for the 

Management of Noxious and Exotic Weeds (FICMNEW) was formed from 17 agencies. The 

committee’s goal is to facilitate the development of biologically sound techniques to manage 

invasive plants on federal and private lands through partnerships, national strategies and 

promotion of weed management programs (FICMNEW, 1998). The Committee sponsored 

the “Pulling Together” national strategy that highlights as a national goal effective prevention 

through partnerships, education and research. 

In 1999, Executive Order 13122, signed by President Clinton, set forth the duties of all federal 

agencies in preventing and managing invasive plants. It also defined invasive species. In 

response to Executive Order 13112 on Invasive Species, the National Invasive Species 

Council was established. The Council prepared “Meeting the Invasive Species Challenge” 

(National Invasive Species Council, 2001), which emphasized prevention, early detection, 

rapid response, control, and restoration and called for international cooperation in the 

prevention of invasions. 

Current invasive plant management direction for the Forest Service is in “The National 

Strategy and Implementation Plan for Invasive Species Management” (USDA FS, 2004 – see 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Appendix S). The management direction proposed for the alternatives in this FEIS are 

consistent with this strategy. 

Other federal agencies have been active in prevention, treatment and restoration efforts. 

National guidance for the BLM includes using weed-free straw mulch (IM 99-076). The 

BLM has developed prevention education programs on invasive plants (e.g., “How to Prevent 

the Spread of Noxious Weeds” (USDI BLM, 1996)). The National Park Service has 

established a nationwide program of Exotic Species Management teams for rapid response to 

infestations. The Federal Highway Administration has developed a policy statement to 

proactively implement Executive Order 13122, encourages and funds the use and 

development of native plant materials for roadside landscaping, and recommends that state 

Departments of Transportation to be involved with state invasive species councils. Some 

actions taken by state level departments of transportation include use of weed-free mulches on 

construction and upgrade projects in Wyoming, use of weed-free sod in Florida, and the 

requirement to wash heavy equipment moving into and out of construction projects in Oregon 

(Turner-Fairbank Highway Research Center, 2000). 

Efforts are also underway in the western states surrounding Region Six. Certified weed-free 

forage and mulch programs have been established in 13 western states and Canadian 

provinces including Nevada, Idaho, and Montana (Schoenig, 2002). California is currently 

working on developing a weed-free forage and mulch program. Neither Oregon or 

Washington have State certified weed-free forage or mulch programs, but Wallowa County, 

Oregon, has developed its own weed free hay program. Oregon has statutes involving the 

cleaning of agricultural machinery in weed management districts (ORS 570.515 – 570.600). 

One source of direction for the prevention and management of invasive plants on National 

Forests in Region Six is the 1988 EIS and 1988 ROD for Competing and Unwanted 

Vegetation, and the associated 1989 Mediated Agreement.36 These documents require 

consideration of invasive plant prevention, but specific direction on how to actually prevent 

the spread of invasive plants is not provided.37 The 1988 ROD specified and limited the tools 

available for the treatment of competing and unwanted vegetation, but did not provide 

administrative mechanisms for adapting their requirements and adopting new technologies. 

Specific guidance on how to actually prevent invasive plant introduction, establishment, and 

 

36 These documents have been incorporated into the Forest Plans within the Region. 

37 A few National Forests, most notably the Mt. Baker-Snoqualmie, have moved forward in recent years to 

amend their Forest Plan to include specific direction for the prevention of invasive plants; most Forests have not. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

spread has been provided to National Forests as optional guidance in the USDA Forest 

Service Guide to Noxious Weed Prevention Practices (Appendix E). 

Social Acceptability and Effectiveness 

One immeasurable aspect of effectiveness is socially acceptability.38 Adverse public 

judgments on planning and management strategies have formidable potential to postpone, 

modify, or prevent their implementation (Shindler et al., 2002). Citizens and interest groups 

have brought court challenges, attracted media attention for their cause, and 

physically/verbally protested actions they considered to be unacceptable, effectively halting 

initial or ongoing implementation of Forest Service actions. 

Scoping and comments to the DEIS revealed at least two major and potentially conflicting 

perspectives on invasive plants. One perspective is that invasive plants are a major threat to 

forest ecosystems and that the situation warrants aggressive treatment, including the 

application of herbicides. This contingent expresses strong concern about placing arbitrary 

limitations on the tools available to effectively treat invasive plants. The other perspective 

acknowledges that invasive plants threaten forest ecosystems, but expresses strong concern 

and skepticism about the use of herbicides. Lawsuits, appeals, and protests can reduce the 

effectiveness of any alternative by delaying or stopping actions to control invasive plants. 

The management direction proposed in the action alternatives provides a framework for 

developing a socially acceptable program for controlling invasive plants. 

Partnerships and Collaboration in Invasive Plant Management 

Invasive plants spread across landscapes, unimpeded by municipal, state, international, and 

other physical and political boundaries. Behaviors of forest users and neighboring 

landowners influence the effectiveness of Forest Service actions to control invasive plants. 

Partnership and cooperation with forest users, neighboring landowners, and other stakeholders 

increase invasive plant prevention program effectiveness. Scoping and DEIS comments 

applauded partnership and collaboration efforts in invasive plant management, and expressed 

that such efforts should be increased. The 2004 “USDA Forest Service, Pacific Northwest 

Region Strategy for Supporting Invasive Plant Management on State and Private Forest 

Lands” clarifies and supports partnership and collaborative effects (Appendix I). The 2004 

“National Strategy and Implementation Plan for Invasive Species Management” (Appendix S) 

emphasizes partnerships and collaboration at all levels of the agency and across all programs. 

 

38 Social acceptability is defined as consistency with prevailing social norms (Firey, 1960). 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

4.2.3 Direct and Indirect Effects 

Introduction – Effectiveness Indicators 

This section compares the relative effectiveness of invasive plant management likely to occur 

under each alternative. First, prevention standards and practices are discussed and the rate of 

spread of invasive plants are estimated for each alternative. Next, each alternative is 

evaluated based on its likelihood to result in effective treatments. Finally, the acres that 

would be effectively treated each year under each alternative is compared to the spread rate to 

determine “years to control.” The methodology supporting this analysis is based on the 

report, Evaluation of Prevention Effectiveness by Alternative (Mazzu and Skrine, 2004) and 

summarized in Chapter 4.2.4. 

Invasive plants are considered to be effectively controlled when acres of plant spread is less 

than or equal to the annual acres successfully treated. Currently, invasive plants are estimated 

to spread by about 42,000 acres each year.39 Each year, the Forest Service treats about 25,000 

acres. At this rate, invasive plants would never be effectively controlled. 

Years to control could be reduced if fewer acres became infested each year (presumably 

through effective prevention practices) and/or more acreage is effectively treated. All of the 

action alternatives include prevention standards that are likely to decrease rates of spread 

compared to the current condition. Effective treatments are defined as those that reduce the 

extent invasive plants so that the area can reach its desired condition. 

Effectiveness of Prevention 

No Action 

Under No Action, no new prevention standards would be added to Forest Plans in Region Six 

as a result of this EIS. No Action would maintain the current low potential to slow the spread 

of invasive plants. 

Action Alternatives 

This section discusses the relationship between the standards in each of the action alternatives 

and the projected rate of spread of invasive plants. Please refer to Table 2-4 for the specific 

wording of each of the standards (Chapter 2.5). 

 

39 42,000 acres is based on an average 10 percent rate of spread applied to the current 420,000 acres of 

infestation (USDA FS, 1999-Stemming). 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Standard #1 as written under the action alternatives would reduce seed introduction or spread 

of invasive plants during Forest Service management activities and reduce conditions 

promoting invasive plants because it treats the problem of invasive plants at the earliest stages 

possible. Standard #1 requires planners to assess the invasive plant situation before activities 

begin. Planners can then develop management recommendations, mitigation measures, or 

project design criteria (depending on the type of document) that address reducing the potential 

for invasive plants before invasion can begin or before an established infestation can be 

spread. Depending on the scale of the document, the Forest Service would be proactive in 

reducing agency contributions at various levels; at the project, program, watershed, or larger 

scale. 

This standard is ranked as having high potential to change rate of spread because it affects 

planning across all Forest Service lands (Mazzu and Skrine, 2004). The added language in 

Alternative B does not substantially change the intent, effectiveness or ranking of this 

standard (ibid.). 

Standard #2 as written under the Proposed Action requires the cleaning of all heavy 

equipment working outside the limits of road prism prior to entering National Forest System 

lands. The standard would not affect emergency situations where equipment washing would 

delay response time. 

Standard #2 would reduce the amount of seed brought in by heavy equipment. Studies have 

shown (Schmidt, 1989; Hodkinson and Thompson, 1997, Rooney, unpublished) that motor 

vehicles can pick up and move invasive species seeds and that these seeds will germinate. 

Since heavy equipment moves between disturbed sites, it is a primary means of importing 

invasive species from outside sources. Although vehicle washing studies are not plentiful, 

Goheen et al. (2004) sampled the effectiveness of vehicle washing in decreasing Port-Orford 

cedar root rot spores. It showed that the washing of vehicles significantly reduced infection 

from 41.2 percent to 3.7 percent in sample trees and the washing of a road grader from 27.8 

percent infection to 2.2 percent infection. 

Standard #2, as written under the Proposed Action and Alternative D, is ranked as moderately 

effective because it would reduce spread of invasive plants from heavy equipment use, but 

would not necessarily reduce the spread from cars, pickup trucks, and other vehicles (Mazzu 

and Skrine, 2004). 

Alternative B includes the additional requirement to clean all equipment and vehicles 

authorized to operate outside the road prism prior to entry and before leaving the project site 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

or use area where invasive plants are present at a level where transport of seed or propagules 

is likely. Support vehicles that accompany heavy equipment would need to be washed more 

frequently, because they are generally used to access worksites, going in and out of National 

Forests on a daily basis, while the heavy equipment is moved in and out far less often. 

Standard #2, as written under Alternative B, is ranked as having high effectiveness (Mazzu 

and Skrine, 2004). This standard could substantially reduce the rate of spread both in and 

outside Forest Service land because it reduces long-distance dispersal, one of the main factors 

in invasion biology. However, this standard may be difficult to implement or enforce. Wash 

stations are not currently available away from populated area and administration costs may be 

cost prohibitive (for instance, contract field inspection to ensure washing is done between 

sites). These difficulties could result in reduced effectiveness of this standard. 

Standard #3 in all action alternatives requires use of weed-free straw or mulch to reduce 

introduction of invasive seeds from outside sources. If State certified straw or mulch is not 

available, individual forests would require sources to be certified using the North American 

Weed Management Association (NAWMA) standards (found at www.nawma.org and 

Appendix O) or a similar certification suite. 

Standard #3 is ranked as highly effective because it would reduce invasion potential of a 

broadly used product throughout National Forest System lands (Mazzu and Skrine, 2004). 

Tons of straw/mulch potentially providing invasive seed could be eliminated. 

An indirect effect would be reduced competition for resources between invasive and native 

plants within and adjacent to mulched areas. Another indirect effect could be an increasing 

market for weed-free straw and mulch, making supplies easier to obtain, and encouraging 

other land management entities to use this product. 

Implementation of this standard may need to be phased-in for the Proposed Action and 

Alternative B as weed certification programs become established. 

Standard #4 varies between the alternatives. As written for the Proposed Action, weed free 

feed would be required for horses, livestock and all pack stock using Wilderness areas. A 

similar requirement already applies to about 2.5 million acres of Wilderness in Region Six, 

which is reflected under No Action and Alternative D (see Chapter 3.2.9 – Congressionally 

Designated Areas). 

The Proposed Action requires weed free feed on about 4.6 million additional acres. 

Consistent use of weed free feed in Wilderness areas would reduce invasive plant introduction 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

along trails and in relatively undisturbed habitat. A substantial positive effect would be the 

protection of some of the most intact native plant communities in Region Six. 

Standard #4, as written for the Proposed Action, is ranked as moderately effective because the 

potential for spread would only be reduced in Wilderness areas only (ibid.). Spread would 

still occur under other land allocations where infestations developing could then be spread by 

natural forces to Wilderness areas. 

Alternative B would expand the weed free feed requirement to all National Forest lands. 

Alternative B also emphasizes keeping project staging areas, livestock and packhorse corrals, 

and OHV areas free of invasive plants. These areas would be inspected annually to detect any 

establishment or spread of invasive plants. 

Standard #4, as written for Alternative B, is ranked as having the highest effectiveness of all 

alternatives because of its comprehensive coverage of National Forest System lands (ibid.). 

Also, additional focus on early detection of invasive plants in staging areas would likely 

reduce the spread of invasive plants more substantially than the Proposed Action. 

Alternative D is the same as No Action with approximately 2.5 million acres using weed-free 

feed. This alternative is least effective of the action alternatives because it covered the fewest 

acres; potential for spread would still be high and both in and outside of Wilderness areas 

(ibid.). 

Implementation of this standard may need to be phased-in for the Proposed Action and 

Alternative B as weed certification programs become established. 

Standard #5 applies solely to Alternative B40. It would require that native vegetation be 

maintained in and around project areas. Cadenasso and Pickett (2001) demonstrated that an 

edge of intact vegetation could function as a physical barrier to invasive plant seed dispersal, 

especially to reduce movement of windblown seed into interior forest. Gelbard and Belnap 

(2003) also suggested that many invasive species had a low potential for spread away from 

road prisms into undisturbed habitat. Both studies concluded that healthy native communities 

could be used as barriers to spread of invasive plants. 

Standard #5, as written for Alternative B, is ranked as being highly effective in reducing the 

spread of invasive plants at the project level (ibid.). This standard is intended to reduce the 

disturbance “footprint” of an action, reduce the movement of windblown seed, and provide 

shade to newly disturbed areas which would discourage the success of invasive plants. 

 

40 Maintaining vegetation as a barrier to the expansion of invasive plant population is included as Objective 2.2 

under all action alternatives. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

The Proposed Action and Alternative D would be less effective in preventing the spread of 

invasive plants, because they lack a similar standard. However, current laws, policies, and 

plans already contribute to retaining native vegetation to achieve desired conditions as 

described in Objective 2.2 (see Chapter 2.4 for full text of Objective 2.2). 

Standard #6 varies between the alternatives. Under the Proposed Action and Alternative D, 

annual operating plan instructions and grazing allotment management plans are required to 

consider and incorporate invasive plant prevention measures. The planning and 

implementation of such measures would occur in cooperation with the permit holder. This 

standard would reduce the introduction and transport of invasive plant seed as a result of 

change in grazing practices where successfully implemented. Requiring the consideration of 

invasive plants and prevention measures during annual operation planning will aid in 

integrated weed management and reinforce the role of permittees as stewards of public lands. 

Prevention measures regarding cattle grazing have been published and are being used in other 

western states and intermittently in Region Six (Sheley in Montana Cooperative Extension, 

2002; Center for Invasive Plant Management, 2003; Sheley et al., in Sheley and Petroff, 1999; 

Wilson et al., in Nevada Cooperative Extension, 1999). 

Standard #6, as written for the Proposed Action and Alternative D, is ranked as moderately 

effective in reducing the spread of invasive plants (Mazzu and Skrine, 2004). While the 

“USDA Forest Service Guide to Noxious Weed Prevention Practices” (Appendix E) is 

recommended at all levels in the Forest Service, it is not required. 

Standard #6, as written for Alternative B, would elevate the importance of the USDA Forest 

Service Guide to Noxious Weed Prevention Practices in livestock grazing management while 

still allowing flexibility for grazing managers and grazing permittees to work together to 

choose effective prevention measures that best suit local allotment conditions, ecology, and 

desired future conditions. While prevention practices are not required in the Guide, managers 

and permittees will be required to document their consideration. Implementation of these 

practices will vary across the Region, but tracking of their implementation will provide much 

needed information on prevention methods being used. 

Standard #7, as written in the Proposed Action, requires the inspection of active gravel, fill, 

sand stockpiles, quarry sites and borrow material for invasive plants prior to use and transport 

on National Forest System lands. It would require materials be judged weed free by District 

or Forest weed specialists. Treatment of infested sources would be required. These material 

sources must be judged weed free by District or Forest weed specialists before use. It would 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

reduce the introduction of invasive plant seed by reducing the use of contaminated fill 

materials during road construction or road maintenance activities. Standard #7 is ranked as 

moderately effective in reducing the rate of spread (ibid.). Contaminated fill spread by road 

corridors is a classic example of long distance dispersal. By reducing the source of invasion 

along these pathways of invasion the domino effect of road equipment moving fill to one spot, 

then other motor vehicles moving the fill further would be reduced. Since the standard does 

not specifically require treatment or removal of contaminated fill, it leaves some question as 

to whether seed may still be moved inadvertently. 

Standard #7, as written for Alternative B, has the highest effectiveness of all the alternatives 

because annual inspections and treatment and stockpiling of infested material would be 

required (ibid.). This increases the likelihood that new infestations would be caught in early 

stages since a system of stockpiling contaminated fill for treatment will be in place. Standard 

#7 would reduce confusion regarding whether infestations have been treated and will ensure 

that contaminated materials are set in a distinct location away from actively used materials. 

Standard #8, as written for the Proposed Action and Alternative D, requires consultation with 

invasive plant specialists on road maintenance activities. While the language varies between 

the alternatives, the intent of the standard is the same. This standard is designed to elevate the 

importance of considering invasive plants in planning for road maintenance activities, while 

allowing flexibility for roads maintenance planners and invasive plant specialists to 

coordinate and plan road maintenance activities that minimize contributions to (and that may 

help to avoid) the spread of invasive plants and that best suit local site conditions, ecology, 

and desired future conditions. Alternative B includes additional language highlighting 

particular practices, but does not change intent or effects of this standard as quantifiable at the 

Regional level. All alternatives are considered equal and ranked as highly effective (ibid.). 

Standard #9 applies solely to Alternative B. This standard is ranked as highly effective 

(ibid.). It requires the consideration of road closures and/or road decommissioning for 

resource issues related to invasive plants. Roads are conduits for invasive species and these 

standards would reduce invasive plant movements along these conduits. Road improvements 

along non-essential roads or where invasive plants are a problem could exacerbate the 

invasion process. Gelbard and Belnap (2003) demonstrated in semi-arid landscape that roads 

improved from four-wheel drive tracks to paved roads tend to become wider and contain an 

increasing number of exotic plant species. Their results suggested that improving 10 

kilometers of four wheel drive tracks to paved roads converted an average of 12.4 hectares of 

interior native habitat to roadside plant communities that typically contain a substantially 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

greater richness and cover of non-native species. While focused on road paving, this study 

suggests that road improvement or maintenance can be considered a major agent of land cover 

change. Closing or decommissioning roads, minimizing the construction of new roads and 

minimizing the improvement or widening of existing roads would reduce ground disturbance 

and reduce the potential for vehicles to spread invasive plant seed. 

The Proposed Action and Alternative D would be less effective in preventing the spread of 

invasive plants because they lack a similar standard. However, the Proposed Action and 

Alternative D are ranked as moderately effective because Objective 2.4 (full text Chapter 2.4) 

focus on use of forest-level Access and Travel Management planning to manage OHV travel 

to reduce spread of invasive plants (Mazzu and Skrine, 2004). 

Standard #10, as written for the Proposed Action, follows draft Forest Service national 

policy, and restricts OHV use to designated routes. Restricting off road travel to designated 

routes would reduce the chances of invasive plant spreading from transportation corridors into 

less disturbed environments. Monitoring of spread of invasive plants from vehicles would be 

more efficient because it could focus on specific routes. Standard #10, as written in the 

Proposed Action and Alternative B, are ranked as having high effectiveness (ibid.). 

Alternative D does not have a corollary standard. 

Table 4-2 summarizes the effectiveness rankings for the prevention standards in the action 

alternatives. All of the action alternatives are likely to decrease rates of spread for invasive 

plants compared to the current rate of 8-12 percent (No Action). However, no data exists that 

allows for precise estimates of the reduction of rate of spread. Mazzu and Skrine (2004) 

considered how effectiveness of the prevention standards would result in reduced rate of 

spread, based on professional judgment. Potential for alternatives to reduce rate of spread is 

shown in Table 4-2. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 4-2 Relative Ranking of Prevention Effectiveness by Alternative Standards. 

Standard Proposed Action Alternative B Alternative D 

1 High High High 

2 Moderate High Moderate 

3 High High High 

4 Moderate High N/A 

5 N/A* High N/A 

6 Moderate High Moderate 

7 Moderate High Moderate 

8 High High High 

9 N/A High N/A 

10 High High N/A 

Overall 

Potential to 

Reduce Rate of 

Spread 

Moderate to high 

potential for reducing rate 

of spread from adherence 

to new prevention 

standards. 

Highest potential for 

reducing rate of spread from 

adherence to new 

prevention standards. 

Moderate potential for 

reducing rate of spread from 

adherence to new prevention 

standards. 

* N/A/ means the specific alternative does not have a corollary standard (Chapter 2.4). 

Effectiveness of Treatment and Restoration 

To a large degree, the effectiveness of an alternative to treat the diverse group of invasive 

plants known in Region Six depends on the variety of tools available. Thus, alternatives that 

limit variety of tools also limit the effectiveness of treatments. 

All of the alternatives promote integrated weed management principles. A study by Brown et 

al. (2001) showed that a combination of manual or mechanical and herbicide treatments was 

more effective than herbicides alone when dealing with such persistent species as spotted 

knapweed. Herbicide treatment alone was found to be most cost effective in the short-term 

but the combination of treatments could improve initial control or maintain control over a 

longer period of time. Biological control combined with herbicides could prove more cost 

effective if insects could establish and maintain long-term control. Thus, all alternatives 

would integrate treatment methods. 

However, the emphasis of each alternative would tend to result in different treatment mixes, 

which affects treatment costs and overall effectiveness. 

Effectiveness of the alternatives is based upon their capacity to offer a combination of 

prevention and treatment options that best allow the use of Integrated Weed Management 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

principles to reduce the spread of invasive plants. Having a wide variety of prevention 

strategies plus treatment tools combined with the ability to adequately restore or revegetate 

treated areas is key to an ecosystem management approach. 

No Action 

No Action approves five herbicides; glyphosate, picloram, triclopyr, dicamba, and 2,4,D (last 

resort). This suite of herbicides is too limited to effectively treat all known types of invasions 

across the region (Mazzu and Skrine, 2004). In particular, No Action does not include 

herbicides that selectively treat invasive grasses. 

Effectiveness herbicides are available under No Action. Picloram has been used successfully 

by the Nature Conservancy (Tu et al., 2001), on several invasive species. An eight year study 

done by Rice et al., (1997) has shown that by using low application rate and specific timing, 

picloram can be effective in maintaining levels of species diversity in grasslands invaded by 

spotted knapweed. Because of its persistence in soils, picloram helped suppress spotted 

knapweed seedlings for at least the first post-treatment growing season. 

Indirect effects of the limited suite of herbicides available include greater potential for 

herbicide resistance (see Chapter 3.3.2 for discussion about this topic). The No Action 

Alternative has two families of herbicides available, and thus has the greatest risk of all the 

alternatives in creating herbicide resistance in some invasive plant species 

Action Alternatives 

The following section discusses how the standards in each alternative influence treatment 

effectiveness. Please refer to Table 2-4 for the specific wording of each of the standards 

(Chapter 2.5). Treatment/Restoration Standards #11, #12, in all alternatives have the potential 

to influence treatment effectiveness. 

Standard #11, Requires the prioritization of treatment areas (Mazzu and Skrine, 2004)41. 

Deciding what and where treatments should occur first, given limited budgets, is a crucial first 

step in any integrated weed management program. Without prioritization, funding may be 

spent on the wrong species or site. Naturalized species or species with little chance for 

control may be treated over more aggressive species. For example, a large infestation where 

populations are scattered could be more effectively controlled from spread if outer perimeter 

populations are treated first. This standard is ranked as highly effective for all action 

alternatives (ibid.). 

 

41 . A suggested prioritization strategy is presented in Chapter 3.3.2. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Standard #12, as written under all the action alternatives, is ranked as highly effective (ibid.). 

By requiring a long-term site strategy, planning for revegetation or restoration needs is 

completed early in the process. This allows for timely development of adequate quantities of 

non-invasive plant materials for site restoration. Having the materials on hand immediately 

after treatment could make the difference in deterring re-infestation. 

Standard #13 as written under the Proposed Action adopts language from the draft Forest 

Service National Native Plant Materials Policy. It requires that native plant materials be the 

first choice for restoration and rehabilitation, but allows for the use of non-native, noninvasive species if necessary (see Chapter 2.5 for full standard language). 

Standard #13, as written in the Proposed Action, is ranked as having the highest effectiveness 

of the alternatives because it provides a means to restore or revegetate treated areas. It also 

provides guidance for the development of plant communities resistant to invasion. While the 

emphasis is on the use of native materials, the manager is not limited to native materials, 

which can be costly and time consuming to develop an adequate supply. This standard allows 

for the restoration of native grass communities more readily than the other alternatives. 

As written under Alternative B, Standard #13 limits managers to the use of native materials 

only. It explicitly states that revegetation projects will rarely be undertaken until a native 

materials supply is developed. This is contrary to the language in the draft Forest Service 

national policy, which allows the use of non-natives that are not persistent. While an 

exception of use for non-natives is given, the lack of detail makes interpretation difficult. The 

standard does not explicitly acknowledge that non-natives may serve a purpose towards 

restoration. 

Standard #13, in Alternative B, may also put other land ownerships susceptible to invasion 

following wildland fire on National Forest land if native materials were not available. Nonnative, non-invasive species revegetation with desirable non-natives can be appropriate where 

issues such as slope stability or the need to plant competitive species arise. Mixing nonnative annuals with native species, for example, can allow rapid coverage to control erosion 

and reduce invasion until slower germinating natives occupy a site. For example, Alternative 

B would eliminate use of non-native crested wheatgrass, which the Natural Resources 

Conservation Service (2003) considers well-adapted for stabilizing soils and competing with 

invasive plants. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Standard #16 has the greatest potential to affect treatment effectiveness of all the standards. 

Each alternative allows for the same group of mechanical, manual, cultural and biological 

techniques, but has a different array of herbicides. 

Standard #16 in all action alternatives meets the need for release from the Forest Plan 

direction established by the 1988 ROD and 1989 Mediated Agreement so that new practices, 

technologies, and herbicides are available for use by the Forests. 

Chapter 2.5 describes the suite of herbicides and application methods available in each 

alternative. Appendix N provides a link to the document, “Common Control Measures for 

Invasive Plants of the Pacific Northwest.” This document summarizes current knowledge 

about treating invasive plants. 

The ranking of effectiveness of the suite of herbicides included in Standard #16 is based on 

peer-reviewed journals, handbooks (e.g. The Nature Conservancy Weed Control Handbook 

and the PNW Weed Management Handbook), and/or websites of professional organizations. 

The herbicide listed in Standard #16 were evaluated based on their effectiveness in controlling 

the nineteen species covering the most acreage or considered of most threat in Region Six (see 

Chapter 3.1). In general, since the effectiveness of herbicides varies with site characteristics, 

alternatives that have the widest variety of herbicides and herbicide families available for use 

(Alternative D and Proposed Action) have the greatest potential to result in effective 

treatments. 

As written in the Proposed Action, Standard #16 allows for the use of ten herbicides. The list 

was developed to treat the broadcast array of invasive plants in Region Six and to also have 

the capability to treat new species that may enter from adjacent land ownerships that were 

known to be invasive (such as state designated Class A noxious weeds). The additional two 

herbicides in Alternative D allows treatment of some of these species at a lower cost per acre. 

The reduction in costs associated with the use of 2, 4-D may allow for more acres to be 

treated. 

The Proposed Action and Alternative D each have four families available to manage herbicide 

resistance. The additional two herbicides in Alternative D belong to the same family as do 

three herbicides in the Proposed Action, so there is no additional advantage in Alternative D 

for managing herbicide resistance. 

Alternative B is likely to be less effective because it lacks sufficient variety of tools for 

adapting to different environmental circumstances. For example, it provides only one tool, 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

sethoxydim, for invasive grass control. Success using sethoxydim on different grasses varies 

from good when treating reed canarygrass to no effectiveness on quackgrass (Tu et al, 2001). 

Alternative B also allows aerial spraying but limitations in ingredients that can be used would 

reduce its effectiveness in remote, difficult to access terrain. The Proposed Action and 

Alternative D would both allow for more aerial spraying than Alternative B. 

Alternative B also lacks the option to use imazapic and imazapyr, the latter of which has 

recently been labeled for aquatic use. These herbicide choices may be important for 

controlling knotweeds and purple loosestrife (Knezevic, no datea; Miller, 2004). Alternative 

B lacks use of chlorosulfuron, metsulfuron methyl or imazapyr, which are considered most 

effective for treating perennial pepperweed (Renz, 200; Kruger and Sheley, 1999). Similarly, 

with reed canarygrass, glyphosate is reported to have moderate effectiveness when combined 

with burning or when applied in high concentrations. Sulfometuron methyl (not included in 

Alternative B) provided more effectiveness when applied to pre-emergent or early postemergent plants (Lyons, 1998). 

Herbicide resistance may increase under Alternative B because there are fewer herbicide 

choices. Alternative B has three families available for managing herbicide resistance. There 

is greater risk that some invasive plant species will not be controlled (where only nonherbicide methods are available but are ineffective on some species or more costly on some 

sites, reducing total treatment of invasive plants). 

Table 4-3 below lists which invasive species of highest concern are likely to be effectively 

treated under each alternative, based on information about herbicide treatments in Chapter 3.42

Table 4-3 Invasive Plant Species Effectively Treated by Herbicides 

Allowed by Standard #16.

Proposed Action Alternative B Alternative D 

Suite of herbicides adequate to effectively treat 

knapweeds, hawkweeds, thistles, knotweeds, 

purple loosestrife, herb Robert, English ivy, 

scotch broom, false brome, rush skeletonweed, 

Himalayan blackberry, medusahead rye, yellow 

toadflax, Dalmation toadflax, leafy spurge, 

perennial pepperweed, tansy ragwort, sulfur 

cinquefoil, St. Johnswort, houndstongue, 

whitetop and cheatgrass 

Suite of herbicides adequate to 

treat knapweeds, hawkweeds, 

thistles, knotweeds, purple 

loosestrife, herb Robert, English 

ivy, scotch broom, false brome, 

rush skeletonweed, Himalayan 

blackberry, medusahead rye and 

reed canarygrass. 

Same as Proposed 

Action 

 

42 Table 3-12 provides more details on which active herbicide ingredients are effective on specific invasive 

species. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Standard #17, as written under the Proposed Action, requires that when herbicide treatment 

methods are chosen, the rationale for their choice would be documented. It also includes 

Objective 3.2, which calls for the reduction in herbicide use over time. No direct changes to 

treatment effectiveness are expected from this standard (Mazzu and Skrine, 2004). 

Standard #17, as written under Alternative B, requires reducing herbicide use over time and 

limits the use of herbicides as tools of last resort. Under Alternative B, this standard would 

require the use of other methods first until they are shown ineffective. The delay caused by 

determining ineffectiveness of other methods could cause an infestation to increase to the 

point where control is more difficult and, in extreme cases, impossible. Thus, Standard #17 in 

Alternative B reduces its overall effectiveness. 

No corollary standards or objectives apply to Alternative D. 

Standard #19, as written in Alternative B, requires that applications of herbicides in riparian 

areas be minimized and that broadcast spraying in riparian reserve land allocations be 

prohibited. This would decrease the effectiveness of riparian treatments for some of the most 

aggressive invasive plants (Mazzu and Skrine, 2004). If such herbicide treatments are 

avoided in riparian areas, where other methods are known to be ineffective, invasive plants 

would continue to have adverse effects. No other alternative restricts riparian herbicide use 

enough to reduce overall effectiveness. 

Effectiveness Indicator: Years to Control 

The “years to control” indicator compares the rate of spread predicted for each alternative 

based on prevention effectiveness (see Table 4.2) against the annual acres treated. Average 

cost of a treatment acre was calculated for each alternative based on the mix of treatment 

methods approved in each alternative (see Chapter 4.6.2). Annual treatment acres were 

projected by holding the current funding level constant and applying the average cost of an 

effectively treated acre. 

Table 4-4 displays how annual treatment acres can be compared to annual spread rates to 

arrive at years to control. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 4-4 Years to Control 420,000 Acres of Invasive Plants* 

Acres Treated Annual Spread Rate 

Annually 0% 3% 4% 6% 7% 8% 10% 12% 

15000 29 63 never never never never never never 

17500 25 44 84 never never never never never 

20000 22 35 48 never never never never never 

22500 20 29 37 never never never never never 

25000 18 25 30 never never never never never 

27500 17 22 26 44 never never never never 

30000 16 20 22 33 59 never never never 

32500 14 18 20 27 36 never never never 

35000 13 17 18 23 29 43 never never 

37500 13 15 17 21 24 31 never never 

40000 12 14 15 19 21 25 never never 

42500 11 13 14 17 19 22 48 never 

45000 11 13 13 16 17 19 30 never 

47500 10 12 13 14 16 17 24 never 

50000 10 11 12 14 15 16 21 never 

52500 9 11 11 13 14 15 18 30 

55000 9 10 11 12 13 14 17 23 

57500 9 10 10 11 12 13 15 20 

60000 8 9 10 11 11 12 14 18 

65000 8 9 9 10 10 11 12 15 

70000 7 8 8 9 10 10 11 13 

75000 7 8 8 9 9 9 10 11 

*This table was created using the spreadsheet formula: Infested acres (current year) = [Infested acres (previous 

year) divided by Spread rate]. Spread rate included infested acres [1.00] plus the spread [0.08]. The Spread rate 

and successfully treated acres were then changed. If the infested acres were increasing per year, invasive plants 

would never be controlled. If treatment or reduced rates of spread resulted in negative infested acres, it was 

assumed control was achieved one year before the infested acres became negative. 

Alternative B includes more emphasis on manual treatment that tend to be more expensive on 

a per acre basis. Thus, fewer acres would likely be achieved at a constant budget and the 

years to control increases proportionally. 

The analysis indicates that the Proposed Action and Alternative D have more potential to 

control invasive plants within the foreseeable future than Alternative B, which has more 

potential to control invasive plants within the foreseeable future than No Action. Given 

current spread rates, invasive plant control could not be achieved by any of the alternatives if 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

invasive plant treatment budgets decline as little as 25 percent. Table 4-5 summarizes the 

analysis findings. If prevention standards were combined with the treatment acreage 

associated with the Proposed Action or Alternative D, estimated years to control would likely 

decrease. 

Table 4-5 Years to Control at Current Funding Levels 

Alternative Effectiveness of 

Prevention 

Acres Treated 

Annually

Estimated Years to 

Control 

No Action 

Low potential to reduce rate 

of spread, current spread 

rate estimated at 8-12% 

25,000 Never unless acres 

treated increased to 

35,000 and rate of 

spread no more than 8% 

Proposed Action Moderate to high potential 

to reduce rate of spread 

30,000 32 years assuming 

spread reduced to 6% 

Alternative B High potential to reduce 

rate of spread 

20,000 47 years assuming 

spread reduced to 4% 

Alternative D Moderate potential to be 

reduce rate of spread 

40,000 21 years assuming 

spread reduced to 7% 

Prevention Standards from B 

Combined with Treatment 

Standards from the Proposed 

Action 

High potential to reduce 

rate of spread 

30,000 21 years assuming 

spread is reduced to 4% 

Prevention Standards from B 

Combined with Treatment 

Standards from Alternative D 

High potential to reduce 

rate of spread 

40,000 14 years assuming 

spread is reduced to 4% 

4.2.4 Cumulative Effects 

Under all alternatives, present and reasonably foreseeable future action will continue to cause 

ground disturbance on a landscape scale, resulting in introduction and spread of invasive 

plants. Roads will continue to be a major conduit for invasive plants. Forest Service 

projections suggest that recreation uses of National Forests will continue to increase. Other 

land management and use activities such as grazing, vegetation management, fuels 

management (Healthy Fuels Initiative), and fire suppression will continue to cause ground 

disturbances and contribute to the introduction, spread and establishment of invasive plants on 

National Forest System lands. 

Land uses and development on lands adjacent to or outside National Forest boundaries will 

likely continue to decrease effectiveness of Forest Service invasive plant management. For 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

example, the use of invasive plants by landowners for landscaping, while small individually, 

can collectively result in significant impacts, especially along riparian corridors. 

Positive cumulative effects could occur as Forest Service efforts are combined with other 

federal, state, county and private landowner efforts, reducing the rate of spread on a regional 

level. Actions proposed in all alternatives would complement the efforts of state control 

programs and community volunteer efforts. For example, the inclusion of English ivy on the 

state of Oregon noxious weed list has helped to reduce sale of this species in nurseries and 

prioritized funding for control of this species by the state. Local volunteer efforts to remove 

the species has not only decreased the extent of the species, but also educated the public on 

the problems associated with it, which in turn elicits control on the individual level in private 

backyards. 

Mack et al. (2001) found that effective prevention and control of biotic invasions require a 

long-term, large-scale strategy, rather than a tactical approach focused on battling individual 

invaders. Multiple species of invasive plants have spread throughout the region. Focusing 

solely on a single species or invasion site has the potential to trade one pest for another. By 

adding to the current efforts, the Forest Service would enhance the current Regional 

movement to prevent and control invasive plants. 

Herbicide use may be repeated over time on the same site. This cumulative effect would be 

most likely where the treatment toolbox is most limited, as in No Action and Alternative B. 

The Proposed Action and Alternative D, by virtue of including a greater variety of tools, 

would be less likely to result in repeated use of the same herbicides. For instance, glyphosate 

could be used for some aggressive species (e.g. perennial pepperweed, leafy spurge), but 

repeated treatments would likely be necessary (Mazzu, 2004). 

4.2.5 Methodology 

The following discussion summarizes the process used to determine effectiveness of the 

alternatives. 

Effectiveness of the alternatives is based upon their capacity to offer a combination of 

prevention and treatment options that best allow the use of Integrated Weed Management 

principles to reduce the spread of invasive plants. Having a wide variety of prevention 

strategies plus treatment tools combined with the ability to adequately restore or revegetate 

treated areas is key to an ecosystem management approach. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

The first step in assessing effectiveness was to develop of means of comparing rate of spread 

for invasive plants. Rate of spread has been modeled for some invasive plant species 

(Higgins and Richardson, 1996; Richards and Dean, 1998; Bergelson et al., 1993). Models 

will always be limited by how much the stochastic aspect of nature can be incorporated and 

how many biological interactions they can accommodate (Myers and Bazely 2003). Cousens 

and Mortimer (1995) point out that a lack of quantitative data hampers the precise 

calculations of the rates of spread of invasive plant species. 

All invasive plant species have unique strategies for spread and resistance to certain treatment 

methods. Spread of a particular species is based on a complexity of variables including, but 

not limited to, life history, population growth rate, reproductive capabilities, availability of 

area to invade, dispersal mechanisms, patterns of dispersal and long versus short-distance 

dispersal capabilities. It is of note that long distance dispersal mechanisms (movement by 

transport, animals etc), even if rare, govern the speed of invasion (Neubert and Caswell, 

2000). 

Additionally, the relative success of invasive plant species varies under different site and 

environmental conditions. Attempting to calculate the rate of spread of over 100 invasive 

plants operating independently under a wide variety of environmental conditions is not 

feasible. At this point, we can only rely on estimates published in the literature. The current 

rate of spread for invasive plants on National Forest land in the western United States is 

estimated to be 8-12 percent (USDA Forest Service, 1999-Stemming). This rate of spread is 

used in the Forest Service Strategy for Noxious and Non-native Invasive Plant Management 

(USDA Forest Service, 1999-Stemming) and has been validated as applicable for Region Six 

by the Region Six Noxious Weed Program Manager (Gary Smith, pers. Communication 

2004) and field-level botanists. 

To proceed with analysis, a set of assumptions related to rate of spread was developed: 

• Rate of spread is influenced by a complexity of factors that are not fully understood 

for the scale of this analysis; 

• Favorable conditions for spread of invasive plants on National Forest lands in Region 

Six are primarily related to management or recreational activities. Depending on the 

activity, the potential for providing long distance dispersal mechanisms exists; 

• The consistent reduction of activities that promotes favorable conditions or introduce 

invasive plant seed will reduce the potential for invasion; 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

• Natural vectors such as humans or animals, or natural forces such as wind or water, 

will continue to spread invasive plant seeds; reduction of spread to zero is not 

possible. 

Prevention Standards - Because rate of spread could not be quantitatively derived at this 

scale, a relative ranking of the effectiveness of prevention standards was developed. 

The relative change in rate of spread due to prevention standards for the action alternatives 

relative to No Action was estimated and a prevention effectiveness by alternative was ranked 

(Mazzu and Skrine, 2004). Following the above assumptions, the team evaluated every 

standard for individual contribution to reducing spread. A summary of the written rationale 

supporting the team’s evaluation is based on the direct and indirect effects provided in 

Chapter 4.2.3. 

Treatment standards – Since non-herbicide treatments available are the same for all 

alternatives, the effectiveness of these treatments would be equal for all alternatives. The main 

difference in treatment standards that could affect rate of spread has to do with herbicide 

choices and the potential for restoring native or desirable vegetation. Essentially the 

alternative offering the best suite of herbicides that would control the widest variety of species 

and the most potential for meeting restoration or revegetation needs would be the most 

effective. The alternative that best treats those difficult-to -control, aggressive species in the 

Region would also be most effective. A summary of the written rationale supporting the 

team’s evaluation is provided in Chapter 4.2.3. 

Treatment acreages - Treatment acreages by alternative for this analysis are consistent with 

those in Chapter 4.6.2. Acreages were estimated using best professional judgment based on 

effectiveness of each method of control. The following assumptions were made: 

• The effectiveness of the various treatment methods included in the EIS are well 

documented in the literature; 

• Treatment costs would be a factor in the amount of acreage that could be treated by 

alternative; 

• The more expensive a treatment, the less acreage could be treated; 

• The less acreage treated, the less reduction in spread (i.e. more plants left to produce 

seed or spread vegetatively); 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

• The more viable treatment options available for eradicating new infestations, 

controlling established infestations and restoring treated areas, the more reduction in 

infestation size would occur; 

• The amount of treatment done annually affects the number of years to control current 

infestations (i.e. the more treatment done per year, the less amount of years needed to 

get a handle on the current problem); 

• As an infestation is reduced in size, there will be less seed produced and less 

vegetative spread; The most viable treatment options available combined with the 

most reduction in seed introduction or spread should most effectively reduce 

infestation sizes and rate of spread. 

Over time, as the chosen alternative is implemented, it is expected that the acres of invasive 

plants in Region Six will change. If appropriate prevention, treatment and restoration 

standards are implemented, it is reasonable to assume that the combined action of these 

measures will eventually reduce and overall size of the invasive plant infestations in Region 

Six. 

4.2.6 Incomplete and Unavailable Information 

What information is missing? 

No specific data exists regarding the effectiveness of prevention measures evaluated in this 

document. 

Is this relevant to reasonably foreseeable significant adverse impacts 

essential to a reasoned choice among alternatives? 

No. This section discusses the beneficial effects of the prevention standards. While 

conclusive research regarding the effectiveness of specific prevention practices is sometimes 

weak or lacking, enough basic information or studies are available to make professional 

judgments regarding likely effectiveness. For example, studies have shown motor vehicles 

can pick up and move invasive species seeds and that these seeds will germinate (Schmidt, 

1989; Hodkinson and Thompson, 1997; Rooney, unpublished). In addition, evidence linking 

ground disturbing activities or transportation corridors and the establishment of invasive 

plants has been gathered (Kimberling et al., 2003; Parks et al., 2003, see Appendix D). 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

4.3 Effects of Herbicides on Non-target Plants and Native Plant 

Communities 

4.3.1 Introduction 

The following section addresses the effects of the herbicides on non-target plants and native 

plant communities. Non-herbicide treatments can also affect non-target plants and plant 

communities; however, these impacts are not the focus of public concern. The effects of nonherbicide methods are disclosed in Appendix J. 

Herbicides have the potential to shift species composition and reduce diversity of native plant 

communities, as less herbicide-tolerant species are replaced by more herbicide-tolerant 

species. Certain herbicides and the methods by which they are applied could also harm plant 

pollinators. If reduction or shift in pollinator species occurs, changes to plant species 

composition or diversity could follow. 

The measuring factors used for comparing the alternatives are: 

• Number of herbicides included in each alternative that have a relatively higher 

potential to harm non-target plants; 

• Number of herbicides included in each alternative that have known potential to cause 

toxic effects to honey bees; and 

• Acres of annual herbicide treatment with these herbicides that have a relatively higher 

potential to harm non-target plants. 

The results of the analysis indicate Alternative D has the highest potential to harm non-target 

plants and native plant communities, as Alternative D includes the most herbicides with a 

higher potential for harm and would treat the most acres with these herbicides. The No 

Action has the next highest potential for harm to non-target plants, followed by the Proposed 

Action and Alternative B (in that order). Both Alternative D and No Action include three 

herbicides that have high potential to harm honeybees. 

4.3.2 Background 

The basis for protecting native plant species and habitats is found in Forest Service 

regulations. Department Regulation 9500-4 directs the Forest Service through Forest Service 

Manual 2620.1 to: 

1. Manage habitats for all existing native and desired non-native plants, fish and wildlife 

species in order to maintain at least viable populations of such species. 

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2. Habitat must be provided for the number and distribution of reproductive individuals 

to ensure the continued existence of a species generally throughout its current 

geographic range. 

In relation to the use of native plants, a draft policy for the use of native plant materials is 

currently under internal review. It was developed in response to Executive Order 13148 (the 

Greening of Government Agencies) and interagency, administration and congressional 

interest in developing native plant materials to meet the rising demand for restoration plant 

materials. 

Forest Service Manual 2523.2 under Watershed Protection and Management sets priorities for 

burned area emergency response treatments stating that natural recovery by native species is 

preferred. It states that when practical, use seeds and plants in these project areas that 

originate from genetically local sources on native species or when native materials are not 

available or suitable, give preference to non-native species that meet the treatment objectives, 

are non-persistent and are not likely to spread beyond the treatment area. 

4.3.3 Direct and Indirect Effects 

Herbicide Effects on Non-Target Plants 

All of the alternatives allow for the use of some herbicides that have potential to harm nontarget plants. The following bulleted statements apply to herbicide use in general: 

• Herbicides are designed to kill plants; some damage to non-target plant species is 

probable despite cautious planning and implementation. 

• Herbicide spray, drift, runoff, leaching, or groundwater movement may result in 

mortality to individuals, reduce their productivity, or lead to abnormal growth 

patterns. 

• For ground and aerial spray applications of herbicides, the closer the non-target 

species is to the application site, the greater is the likelihood of damage. 

• After broadcast application of herbicides, the level and extent of damage to non-target 

plants depends on site-specific conditions, including wind speed and foliar 

interception. 

• Herbicides can move off-site in water, soil and wind. Site-specific soil and water 

characteristics, as well as herbicide formulation characteristics, affect this movement. 

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Effects from herbicide movement are plausible for either ground or directed foliar 

application. 

• The potential to harm non-target species is dependent on herbicide characteristics. 

Herbicides vary as to their potency, selectivity, and persistence (these terms are 

defined in Chapter 3.3.2). These factors all play a role in how much harm can occur. 

• Measures taken to limit exposure, such as selective application methods (wiping or 

daubing), may reduce herbicide movement off-site. 

• Ectomycorrhizal suppression due to herbicides has not been demonstrated in the 

literature, however the applicability of these in vitro studies to field conditions is 

uncertain given the complexity of fungal communities, soil types, and environmental 

factors that influence forest ecosystems (Busse et al., 2004). 

The following section summarizes the effects to plants by active ingredient. The effects are 

grouped by the mode of action (how the herbicide works to kill target species). Chapter 3.3.2 

provides additional details on each active ingredient. 

Acetolactate Synthase (ALS) Inhibitors – Chlorsulfuron, metsulfuron methyl, sulfometuron 

methyl, imazapic, and imazapyr work by inhibiting the activity of an enzyme called 

acetolactate synthase, which is necessary for plant growth. These five active ingredients are 

very potent herbicides that in some circumstances could damage non-target species more 

readily than the other groups of herbicides proposed. They could be difficult to use in areas 

where native plants are a large component of a treatment area. 

These ingredients would only be used in situations where an invasive plant is the dominant 

cover species or on aggressive species (such as toadflaxes, houndstongue, perennial 

pepperweed or reed canarygrass) that have not been effectively treated by other methods or 

herbicides. 

Synthetic auxins – Picloram, clopyralid, triclopyr, 2,4-D, and dicamba mimic naturally 

occurring plant hormones called auxins. They kill plants by destroying tissue through 

uncontrolled cell division and abnormal growth. In the Pesticide Re-registration Fact Sheet–

Picloram (1995), the EPA noted that picloram poses very significant risks to non-target plants. 

Estimated concentrations of picloram in the environment are hundreds to thousands of times 

the “level of concern” at which 25 percent of seedlings fail to emerge. The EPA also noted 

that picloram is highly soluble in water, resistant to biotic and abiotic degradation processes, 

and mobile under both laboratory and field conditions. They stated that there is a high 

potential to leach to groundwater in most soils. Plant damage could occur from drift, runoff, 

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and distant areas where ground water is used for irrigation or is discharged into surface water 

(EPA, 1995). The contribution from irrigation is considered inconsequential relative to offsite drift and runoff (SERA, 2003-picloram). Labeling restrictions from these findings were 

implemented to reduce effects. 

Because picloram persists in soil, non-target plant roots can take up picloram (Tu et al, 2001) 

and could impact revegetation efforts. Lym et al. (1998) recommended that livestock not be 

transferred from treated grass areas onto sensitive broadleaf crop areas for 12 months or until 

picloram has disappeared from the soil without first allowing seven days of grazing on an 

untreated green pasture. Otherwise, cattle urine may contain enough picloram to injure 

sensitive plants. To a lesser degree, this can occur with other active ingredients such as 2,4-

D, glyphosate and imazapic. 

In summary, susceptible plant species could be adversely affected by the off-site transport of 

picloram under a variety of different scenarios depending on local site-specific conditions that 

cannot be generically modeled. More tolerant plant species are not likely to be affected 

unless they are directly sprayed or subject to substantial drift (SERA, 2003–picloram). 

Clopyralid (used in Transline®) is more selective and less persistent than picloram. As with 

picloram, clopyralid has little effect on grasses and members of the mustard family. 

Triclopyr 

Triclopyr (used in Garlon®) is a selective systemic herbicide. It is used on broadleaf and 

woody species. It is commonly used against woody species in natural areas (Tu et al., 2001). 

Susceptible species could be impacted by drift from 100 feet (typical Forest Service 

application rate) to 1000 feet (maximum US Forest Service application rate) (SERA, 2003-

triclopyr). 

Two forms of triclopyr could be used with differing degrees of effects. Triclopyr BEE 

(butoxyethyl ester) is more toxic to plants than triclopyr TEA (triethylamine salt). Triclopyr 

BEE formulations are more apt to damage plants from runoff than other formulations (SERA, 

2003 – triclopyr). 

Both formulations have been found to decrease the relative long-term abundance and diversity 

of lichens and bryophytes. Newmaster et al. (1999) stated drift from triclopyr could affect the 

sustainability of populations of lichens and bryophytes, where these ingredients reduced 

abundance. Normal application rates in aerial spraying were found to reduce abundance by 

75 percent, variable by species. Colonists and drought-tolerant species were more resistant 

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than the mesophytic forest species, which means that herbicide treatments could essentially 

push back the successional stage on a non-vascular community. 

Triclopyr was found to inhibit growth of three types of ectomychorrhizal fungi associated 

with conifer roots at concentrations of 1,000 parts per million in laboratory experiments 

(Estok et al., 1989). Busse et al (2004) found no inhibition of ectomychorrhizal formation in 

a laboratory experiment using this active ingredient. 

2,4-D 

2,4-D (used in 20 commercial formulations) is a selective herbicide that kills broadleaf plants, 

but not grasses. It has a long history of use and is relatively inexpensive. Direct spraying of 

non-target plant species is the highest potential for damage due to 2,4-D application. Drift 

could damage to non-target species at a distance close to the application site (much less than 

100 feet). If plants are accidentally sprayed at the application rates used by the Forest 

Service, they are likely to be damaged, particularly in the upper ranges of anticipated 

application rates. The extent and duration of damage will depend on the time of application 

and plant species (SERA, 1998 – 2,4-D). 

One study determined that 2,4-D could affect three species of ectomychorrhizal fungi in 

laboratory experiments (Estok et al., 1989). 

Dicamba 

Dicamba (used in Vanquish® or Banvel®) is a selective, systemic herbicide that can affect 

some annual, biennial, perennial broadleaf and woody species as well as annual grasses. Some 

tolerant plants directly sprayed at normal application rates are likely to be damaged. The 

greatest risks are associated with runoff but are highly site specific. Wind erosion may cause 

impacts in arid regions (SERA, 2004 – dicamba). Drift may cause damage to sensitive 

species at distances less than 100 feet from the application site. 

Vaporized or volatilized dicamba can affect non-target plants. Vaporization does impact 

vegetation, but much more study in air concentration-duration relationships needs to be done 

to quantify the level of effects. The impacts should be less pronounced with Vanquish than 

with Banvel (SERA, 2004-dicamba). Vaporization potential will be dependent on 

atmospheric stability and temperature. Dicamba vapor has been known to drift for several 

miles following application at high temperatures (NCAP, 1995). 

In summary, some susceptible plant species could be affected by runoff of dicamba. Damage 

associated with off-site drift of dicamba would depend on local site-specific conditions, but 

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could occur within a relatively small distance from the application site – i.e., up to 100 feet. 

Vapor exposures to offsite vegetation could also cause damage. While this cannot be well 

quantified, it is likely that this effect would be less pronounced with Vanquish than Banvel 

(SERA, 2004 – dicamba). 

EPSP Synthase Inhibitors – Glyphosate preventing plants from synthesizing three aromatic 

amino acids. The key enzyme inhibited by glyphosate is called EPSP. 

Glyphosate 

Glyphosate (used in 35 formulations including RoundUp® and Rodeo®) is a non-selective, 

systemic herbicide that can damage all groups or families of non-target plants to varying 

degrees, most commonly from off-site drift. Plants sensitive to glyphosate can be damaged 

by drift up to 100 feet from the application site at the highest rate of application proposed. 

More tolerant species are likely to be damaged at distances up to 25 feet (SERA, 2003-

glyphosate). 

Non-target species are not likely to be affected by runoff based on the NOEC for preemergent vegetation. Glyphosate strongly adsorbs to soil particles, which prevents it from

excessive leaching or from being taken up from the soil by non-target plants and has a low 

potential to leaching into groundwater systems (Tu et al., 2001; SERA, 2003-glyphosate). 

Because it adsorbs readily to soils, plant roots do not readily absorb it. Non-target species 

will not be impacted through their roots. 

Some field studies have been conducted using glyphosate. Miller et al. (1999) found no 

effects to plant diversity in an 11-year study on site preparation using herbicides, though the 

structural composition and perennial species presence were changed. Such differences in 

overstory and understory vegetation may have ecological or sociological implication. For 

instance, reductions in several species (Vaccinium and Prunus species) in the understory 

could affect wildlife species dependent on them for food, and could also affect traditional 

gathering of these species. As discussed in the effects summary of triclopyr, Newmaster et al. 

(1999) raised concern that drift from glyphosate could affect long term sustainability of 

populations of lichens and bryophytes. 

Glyphosate was found to inhibit growth of three types of ectomychorrhizal fungi associated 

with conifer roots at concentrations of 1,000 parts per million in laboratory experiments 

(Estok et al., 1989). 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Acetyl CoA Caroxylase (ACCase) Inhibitors – Sethoxydim inhibits acetyl CoA carboxylase, 

the enzyme responsible for catalyzing an early step in fatty acid synthesis. Non-susceptible 

species have a different CoA carboxylase binding site, rendering them immune to the effects. 

Sethoxydim 

Sethoxydim (used in Poast®) kills post-emergent annual and perennial grasses by preventing 

the synthesis of lipids. Because sethoxydim is water-soluble and does not bind strongly with 

soils, it can be highly mobile in the environment. Rapid degradation generally limits 

extensive movement. In water, sethoxydim can be degraded by sunlight within several hours 

(Tu et al., 2001). 

For relatively tolerant species, there is no indication that damage from drift would result at 

distances more than 25 feet from application sites. For susceptible species, there is a 

possibility of damage no greater than 50 feet from application sites. Runoff could cause 

damage to susceptible plants in areas of high rainfall (SERA, 2001-sethoxydim). 

See Appendix G “Herbicide Risk Assessment Locator” for the website location of the risk 

assessments for these Herbicides. 

Herbicide Effects on Pollinators 

Pollinators can be impacted, directly or indirectly, by any herbicide. This in turn can cause 

indirect effects on native plant communities. Plants that are dependent on a particular insect 

for pollination may experience a decrease in reproductive capabilities if their pollinator is 

impacted by herbicides. 

It is estimated that there may be between 130,000 and 200,000 invertebrate and vertebrate 

species that regularly visit the flowers of higher plants, which depend on these animals to 

assure cross-pollination. Beetles pollinate most of the flowering plants in the world. Bees are 

the third most common pollinator (16.6 percent of flowering plants) after the Hymenoptera or 

wasp group (18 percent) (Buchman and Nabhan, 1996). 

Very little information is available on the effect of herbicides on native pollinators. Most 

information is about the non-native honeybee. It is known that pollinators can be directly 

affected by spray or indirectly when plants needed as food for adults or larvae are eliminated 

by herbicides. The only known quantified effects covered in the risk assessment are from 

direct spray. The active ingredients used in the Proposed Action are not expected to have 

toxic effects when directly sprayed on honeybees at the typical Forest Service application 

rate. Table 4-6 lists the potential herbicide doses for bees in a direct spray scenario. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 4-6 Potential Herbicide Doses for Bees in a Direct Spray Scenario 

Herbicide Typical Application 

Rate Potential Dose for Bee Toxic Level for Bee 

Chlorsulfuron 0.056 lb/ac 8.98 mg/kg >25 mg/kg (LD50) 

Clopyralid 0.35 lb/ac 56.1 mg/kg 909 mg/kg (no mortality) 

Dicamba 0.3 lb/ac 48.1 mg/kg 1000 mg/kg (no mortality) 

Glyphosate 2.0 lb/ac 321 mg/kg 540 mg/kg (NOAEC) 

Imazapic 0.13 lb/ac 16 mg/kg 387 mg/kg (no mortality) 

Imazapyr 0.45 lb/ac 72.1 mg/kg 1000 mg/kg (no mortality) 

Metsulfuron Methyl 0.03 lb/ac 4.81 mg/kg 270 mg/kg (NOEC) 

Picloram 0.35 lb/ac 56.1 mg/kg 1,000 mg/kg (no mortality) 

Sethoxydim 0.3 lb/ac 60.1 mg/kg 107 mg/kg (NOAEL) 

Sulfometuron Methyl 0.045 lb/ac 7.21 mg/kg 1,075 mg/kg (NOEC) 

Triclopyr BEE 1.0 lb/ac 160 mg/kg >1,075 mg/kg (LD50) 

Triclopyr TEA 1.0 lb/ac 160 mg/kg >1,075 mg/kg (LD50) 

2,4-D 1.0 lb/ac 163 mg/kg 124 mg/kg (LD50) 

NPE 1.67 lbs/ac 268.00 mg/kg unknown 

Herbicide Effects on Plant Diversity and Culturally Important Plants 

Just as changes in plant diversity or species composition can occur due to invasive plants, 

changes can also occur due to treatments. Short-term changes in species dominance can lead 

to long-term shifts in plant community composition and structure. Repeated treatments over 

time could favor tolerant species, which in turn could shift pollinators available to a 

community. 

DiTomaso (2001) points out that continuous broadcast use of one or a combination of 

herbicides will often select for tolerant plant species. When broadleaf selective herbicides are 

used, noxious annual grasses such as medusahead, cheatgrass or barbed goatgrass may 

become dominant. Population shifts through repeated use of a single herbicide may also 

reduce plant diversity and cause nutrient changes. For example, legume species are important 

components of rangelands, pastures, and wildlands, and are nearly as sensitive to clopyralid as 

yellow starthistle. Repeated clopyralid use over multiple years may have a long-term 

detrimental effect on legume populations. Thus, a variety of integrated treatments would 

most likely avoid adverse impacts to native plant diversity. 

Naeem et al. (1999) summarized studies related to biodiversity and ecosystem functioning. 

Recent theoretical models predict that decreasing plant diversity leads to lower plant 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

productivity. These models also showed diversity and composition are equally important 

determinants of ecosystem functioning. Maintaining biodiversity is often one of the primary 

goals of ecosystem management. Reductions in diversity may destabilize trophic dynamics, 

alter wildlife populations and change nutrient cycles or decomposition rates (Walker and 

Smith in Luken and Thieret, 1997). 

Conifer forests are susceptible to changes in ectomycorrhizal fungi. Ubiquitous in most 

forests, their complex network of fungal hyphae increase the effective rooting area of host 

trees, often leading to improved nutrient uptake, seedling survival, and growth (Busse et al, 

2004). Adverse effects on ectomychorrhizal fungi and on edible mushrooms from herbicide 

use have not been demonstrated in laboratory studies (ibid.). 

Many culturally important species are associated with specific plant communities. For 

example, huckleberry at higher elevations (Vaccinium deliciosum) can be predictably found in 

mountain hemlock/subalpine meadow plant communities. The species can be found more 

predictably in this community than transitional, fire dependent openings (Mack, 2002), which 

is important information for gathering. Root plants such as Lomatium species are found in 

numerous plant communities in the Pacific Northwest. Distinct root plant associations were 

developed in the rocky scablands of the Warm Springs reservation (Helliwell, 1988a) to assist 

in land management actions to increase availability. Camas (Camassia species) and red 

yampa (Perideridia gairdneri) plant associations were developed in wetland areas for the 

Warm Springs reservation to also guide management practices (Helliwell, 1988b). 

Ando et al (2003) studied the residual time of glyphosate and triclopyr on the traditional use 

species, bracken fern roots, buckbrush shoots, golden fleece foliage and manzanita berries. 

Residual amounts were found for all species for at least 20 weeks when directly sprayed with 

glyphosate. Triclopyr amounts were also detected for at least this number of weeks as well. 

Ando et al. (2003) also accounted for off site drift by sampling twenty sites located along 

transects at various distances from the application site. Glyphosate was only detected on the 

day of application and only at three out of twenty sites. These sites were no more than 4.5 

meters from the application site (application rates ranged from 0.35 to 4.8 lb/acre; the highest 

rate was above the Forest Service typical application rate). Triclopyr was detected at seven 

sites ranging from 1.5 to 30 meters from the site on the day of application (application rates 

ranged from 0.27 – 1.78 lb/acre; the highest rate slightly above the typical application rate). 

By the fourth week of sampling, residual amounts could be found at two sites for glyphosate 

and no sites for triclopyr. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Alternative Comparison 

The following summarizes and compares the effects of the alternatives on non-target plants 

and native plant communities. Herbicide choice, application method and extent of herbicide 

use determine the relative risk. 

No Action 

Under No Action, the use of herbicides is the most common means of treating invasive plants, 

followed by manual treatments (see Chapter 4.5). The combination of glyphosate, picloram, 

dicamba, triclopyr and 2,4-D (as a last resort) does not provide as wide a range of tools as the 

Proposed Action or Alternative D. The combination is relatively non-selective. 

Because of the heavy reliance on picloram under No Action, the threat of off-site damage to 

native plants and plant communities under No Action would be higher than in the Proposed 

Action and Alternative B. Picloram was the most commonly used herbicide over a four year 

period in Region Six (Forest Service Pesticide Use Reports, 2004). Picloram is one of the 

more persistent herbicides. It can move readily to non-target native plants through root 

translocation or runoff. 

No Action could degrade the health of native plant communities near herbicide treatments 

where runoff or drift has occurred. Native plant families affected by these herbicides would 

be harmed, decreasing their dominance. Healthy native plant communities would continue to 

decrease in acreage, especially in highly susceptible plant communities (described in Chapter 

3) such as grasslands, westside dry forests and eastside dry forests, especially where difficult 

species to treat may be found, including sites with culturally important plants. 

Proposed Action 

Under the Proposed Action, herbicide use would continue to be the most common means of 

treating invasive plants. Standard #16 provides a ‘toolbox’ of ten herbicides under the 

Proposed Action. It offers more herbicide treatments options in regards to selectivity, potency 

and persistence than No Action or Alternative B, which directly affects the potential to harm 

non-target species. For example, selective herbicides could be used where the density of nontarget, desirable species is high. Herbicides that are more potent would also be available for 

treating highly aggressive species. Herbicides that persist in soil would be available to 

decrease re-infestation of invasive species with long-term viable seed, when the potential for 

other environmental impacts is minimized. Infestations found in highly susceptible 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

vegetation groups (e.g. grasslands, shrublands, dry forest or woodland communities of the 

east and west side) could be controlled before they become large. 

At the project scale, adherence to Standards #16, #19 and #20 would reduce the severity and 

extent of impacts associated with runoff or drift. Standard #16 restricts aerial applications for 

the sulfonylurea group to mitigate effects from offsite drift associated with this type of 

herbicide. Standard #16 also restricts triclopyr to selective applications, which would reduce 

direct effects to non-target woody species, culturally important species, and ectomychorrhizal 

fungi. Thus, projects that follow integrated weed management principles and adhere to the 

standards in the Proposed Action would largely avoid adverse effects to non-target plants 

(including culturally important plants) and fungi. 

Alternative B 

Alternative B restricts the number of available herbicides more than the other alternatives. 

Standard #16 would not allow the use of picloram or any of the five acetolactate synthaseinhibiting herbicides. Projects that adhere to the standards in Alternative B would largely 

avoid adverse effects to non-target plants (including culturally important plants) and fungi. 

However, the lack of herbicide variety in Alternative B could force the use of less selective 

herbicides, such as glyphosate. 

Alternative D 

Under alternative D, herbicide use could occur more frequently than under the other 

alternatives. Treatment Standard #16 under this alternative allows for the largest number of 

herbicides. It allows for all application techniques and does not limit aerial spraying for the 

sulfonylurea group or broadcast spraying for triclopyr, increasing the potential for drift of the 

more potent, non-selective or persistent herbicides. 

Projects that comply with Alternative D would follow integrated weed management 

techniques and avoid adverse effects in the majority of projects, however, it allows 

application techniques could lead to effects on non-target plants and plant communities 

(including culturally important plants and ectomychorrhizal fungi) that are greater in severity 

and/extent than the other alternatives. However, these same application techniques and 

herbicides allowed may result in less need for repeated treatments. 

Sprayed directly, pollinators could be affected by 2,4-D at the typical Forest Service 

application rate, or glyphosate or triclopyr at the maximum Forest Service application rate. 

Pollinators could be indirectly affected by reduction in plants required by the larvae of the 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

pollinators. Indirect effects of changes to pollinators would also lead to changes in species 

composition of native plant communities. Plant species with limited pollinators may be more 

apt to decrease in numbers; some rare plants fall in this category. Those plant species with a 

larger variety of pollinators would thrive. Overall, species diversity could change and most 

likely decrease. 

Comparison Factors 

The effects of the alternatives by the comparison factors are summarized in Table 4-7. The 

determination of “relative potential for harm” was based on potency, selectivity, persistence, 

and application method variations between alternatives. The herbicide use ratios in Chapter 

4.5 were used to calculate estimated acres treated by herbicide per year in each alternative. 

As stated in Chapter 4.5, herbicide use ratios are not exact. The acreages presented in this 

table are considered estimates only and are meant as a means for relative comparison only. 

Table 4-7 Summary of Effects by Measuring Factors 

Comparison Factor No Action Proposed 

Action 

Alternative B Alternative D 

Number of herbicides in each 

alternative that have a relatively 

higher potential to harm nontarget plants 

4 – picloram, 

glyphosate, 

triclopyr, 

dicamba 

3 – glyphosate, 

imazapyr, 

picloram* 

1 - glyphosate 5 –chlorsulfuron, 

metsulfuron methyl, 

sulfometuron 

methyl, picloram, 

glyphosate, 

triclopyr, dicamba 

Acres of annual treatment with 

these herbicides that have a 

relatively higher potential to 

harm non-target plants. 

12,956 8,369 2,031 15,428 

Number of herbicides included in 

each alternative that have known 

potential to cause toxic effects to 

harm honeybees. 

3 – 2,4-D, 

glyphosate and 

triclopyr* 

2 – glyphosate 

and triclopyr 

1-glyphosate 3 – 2,4-D, 

glyphosate and 

triclopyr* 

* Toxic effects for glyphosate and triclopyr show up only at the highest application rate. 

At the project scale, under all action alternatives, choices can be made to avoid situations that 

could potentially cause adverse effects to non-target plant species. For instance, certain 

herbicides can be avoided in specific areas or times of the year when/where these non-target 

plants may be at most risk, or more specific application methods may be used. All 

alternatives apply integrated weed management principles, so short-term adverse effects 

would largely be offset by the long-term benefits of treatment. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

4.3.4 Cumulative Effects 

Chapter 4.3 focuses on the potential effects to groups of native plants from herbicide use that 

could occur under each alternative. These effects are relatively limited in extent, and may be 

mitigated by selective application methods or use of herbicides that are less harmful to 

desired, non-target plants. All alternatives could lead to an eventual reduction in herbicide use 

on a larger scale, either by objective Standard #17 or by the fact that invasive plants are 

effectively controlled and less treatment is needed. Adjacent lands would need less treatment 

as new infestations and sizes of large infestation are reduced in the action alternatives. If 

chemicals and application methods that are less damaging to non-target plants are 

demonstrated to be cost-effective, adjacent landowners may be more likely to use the less 

damaging tools. 

There could be an additive cumulative effect to susceptible non-target plant species if 

herbicide use is repeated over time on the same site. This cumulative effect would be most 

likely where the treatment toolbox is most limited, as in No Action and Alternative B. The 

Proposed Action and Alternative D, by virtue of including a greater variety of tools, would be 

less likely to result in repeated use of the same herbicides. 

As made clear in Chapters 1 and 3, entire native plant communities may be degraded or 

destroyed from competition from invasive plants. In addition, many natural events (for 

instance, wildland fires) or human activities (for instance, land use and development) 

influence the distribution and health of native plant communities. 

Projects that comply with the standards in the action alternatives are not likely to significantly 

harm native plant communities; rather, all alternatives are intended and expected to restore 

native plant communities where they are being adversely affected by invasive plants. Over 

time, the prevention standards included in the action alternatives will help reduce the extent or 

intensity of land uses that spread invasive plants or otherwise those risks to native plants, such 

as grazing, OHV uses, and timber harvesting, resulting in a cumulatively beneficial impact as 

compared to No Action. 

Herbicide use and other activities on all land ownerships in Oregon and Washington pose 

risks to non-target plants. The choice of any alternative in this EIS would do little to affect 

these cumulative, ongoing risks. The level of risk associated with Alternative D, which has 

the highest potential for herbicide use and impacts to non-target species, is minor compared to 

herbicide use, which is minor compared to potential risks to native plant communities across 

the states of Oregon and Washington from other natural and human influences. 

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4.3.5 Methodology 

Forest Service/SERA Risk assessments provided the basis for the analysis of effects on nontarget plants. In these assessments, the potential for non-target effects through off-site drift 

from ground spray, aerial spray, and runoff were disclosed for each herbicide. Effects on 

pollinators were derived from risk assessment information on effects from direct spray on 

honey bees. 

Herbicide labels and the Nature Conservancy’s Weed Control Measures Handbook (Tu et al., 

2001) were also used for more species-specific information. By using label information about 

controlled species, effects to closely related species could be extrapolated. 

Effects were summarized based on the species groups used in the risk assessment. These 

groups are typically used on herbicide labels and weed management handbooks when 

describing the selectivity of various commercial formulations. These groups are broadleaf, 

grass and woody species. Broadleaf species, also known as dicots, are non-grass-like species. 

Grass-like species include all monocots. Monocots and dicots move water and nutrients in 

different ways, which can vary plant response to herbicides. Woody species are also dicots, 

but this group can also react differently. 

Herbicides were compared by their selectivity. The ability to damage a broad spectrum of 

plant species, families or groups would make an herbicide non-selective. The ability to 

damage only certain species or families within a group but not others makes an herbicide 

selective. The more selective an herbicide is, the less potential effects it would cause to nontarget plants. 

Herbicides were compared by their potency. Potent herbicides, which take a very small 

amount of active ingredient to cause damage, were considered to have the potential to affect 

non-target plants when application methods did not restrict drift. Potency was considered 

relative to the typical application rates used by the Forest Service in the risk assessments. 

Herbicides were also compared by the persistence in the environment and their ability to 

move off-site from where they were applied. An herbicide known to persist over more than a 

year would have the ability to affect non-target plants more than a non-persistent herbicide 

either directly through off site movement or indirectly through impeding native or desirable 

seed germination. This persistence characteristic could also benefit native plant communities 

by reducing the ability of the invasive plants to germinate. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

4.3.6 Incomplete and Unavailable Information 

What information is missing? 

Studies are not available regarding the effects of herbicides on native, non-target species. The 

EPA performs studies predominantly on crop species rather than native species. Boutin et al. 

(2004) concluded that it was likely that species tested were not representative of the habitats 

found adjacent to agricultural treatment areas, thus risk to native species may be 

underestimated. 

Is this relevant to reasonably foreseeable significant adverse impacts 

essential to a reasoned choice among alternatives? 

No. Herbicide effects to native species can be extrapolated from the risk assessment or 

herbicide labels. Standard #19 directs that site-specific information, including potential 

effects of specific herbicides on non-target species, be considered when making a decision to 

use herbicides. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

4.4 Effects of Herbicides to Certain Birds, Mammals and 

Amphibians 

4.4.1 Introduction 

The following terminology from Chapter 3.3 are repeated here for easy reference, these 

definitions apply to Chapters 4.4 and 4.5. 

Terminology

NOAEL – No-observed-adverse-effect level: An exposure level at which there are no statistically or biologically 

significant increases in the frequency or severity of adverse effects between the exposed population and its 

appropriate control; some effects may be produced at this level, but they are not considered as adverse, or as 

precursors to adverse effects. In an experiment with several NOAELs, the regulatory focus is primarily on the 

highest one, leading to the common usage of the term NOAEL as the highest exposure without adverse effects. 

LOAEL – Lowest-observed-adverse-effect level: The lowest dose associated with an adverse effect. 

Toxicity index: The benchmark dose used in this analysis to determine a potential adverse effect when it is 

exceeded. Usually a NOAEL, but when data are lacking other values may be used. 

Results of numerous field studies indicate the likelihood for direct adverse effects to wildlife 

from herbicide use is low (e.g. Marshall and Vandruff, 2002; Dabbert et al., 1997; Fagerstone 

et al., 1977; Rice et al., 1997; Sullivan et al., 1998; Cole et al., 1997; Cole et al., 1998; 

Johnson and Hansen, 1969; Nolte and Fulbright 1997, McMurray et al. 1993a; McMurray et 

al. 1993b). But the use of herbicides to treat invasive plants does have the potential to harm 

free-ranging wildlife. Certain herbicides have the potential, for example, to affect the vital 

organs of some wildlife species, change body weight, reduce the number of healthy offspring, 

increase susceptibility to predation, or cause direct mortality. Birds and mammals may ingest 

vegetation or insects that have been sprayed with some herbicides and potentially experience 

these types of effects. Herbicides may also cause some malformations or mortality to 

amphibians that have been exposed to herbicides or surfactants in water (Relyea, 2005). In 

addition, herbicides contain impurities and additives, and produce metabolites that could be 

toxic to wildlife. A metabolite of triclopyr, 3,56-trichloro-2-pyridinol (TCP), is toxic to 

animals. The impurity hexachlorobenzene, found in picloram and clopyralid, is carcinogenic. 

Surfactants added to herbicides can substantially increase toxicity to aquatic species, like 

amphibians. These substances were evaluated in the relevant risk assessments and, with the 

exception of surfactants, were found to not contribute substantially to toxic exposures or 

increase cancer risk (SERA, 2003-triclopyr; SERA, 2003-picloram; SERA, 2003-glyphosate; 

SERA, 2004-clopryalid). 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

The results of the herbicide analysis indicate that birds or mammals that eat grass or insects 

are most susceptible to harm from herbicides. Birds or mammals that eat vegetation 

(primarily grass) that has been sprayed with herbicide have relatively greater risk for adverse 

effects because herbicide residue is higher on grass than it is on other herbaceous vegetation 

or seeds (Kenaga, 1973; Fletcher et al., 1994; Pfleeger et al., 1996). Because of their small 

size and relatively larger surface area, herbicide residues on insects may also be higher 

(Kenaga, 1973). Some birds and mammals that eat grass include grizzly bears, elk, rabbits 

and hares, chukar, California quail43, and geese. Insect-eating mammals include bats and 

shrews. Insect-eating birds include a huge number of species, such as bluebirds, flycatchers, 

swallows, wrens, and others. 

The alternatives are evaluated for their potential to result in harmful doses, by comparing the 

different suites of herbicides allowed in each alternative and the standards within the 

alternatives that constrain herbicide use. The measuring factors used for comparing the 

alternatives are: 

• The total number of plausible exposure scenarios in each alternative that exceed the 

toxicity indices for birds and mammals that eat vegetation or insects44. 

• The number of acres projected to be treated with an herbicide that results in at least 

one plausible scenario, exceeding the lowest-observed-adverse-effect level (LOAEL) 

at typical or highest application rates. 

• The number of herbicides in each alternative that could adversely affect amphibians. 

Surfactants (NPE) added to herbicides also have the potential to result in harmful doses to 

birds and mammals that eat vegetation or insects that have been sprayed. The total number of 

plausible exposure scenarios that exceed the toxicity indices is also shown for each 

alternative. This number is the same for all alternatives. No estimate of acres treated using 

NPE surfactants is made because surfactants may not be used, or other additives may be used 

instead, so there is not a direct correlation between acres treated with herbicide and acres 

treated with NPE. 

The results of the analysis indicate that Alternative D poses the highest potential risk to 

wildlife from herbicides. It includes the greatest number of plausible scenarios (31 at typical 

 

43 Some bird species (like quail) are primarily herbivorous as adults but require insects as a primary food source 

as chicks. 

44 The calculation of number of plausible scenarios for typical and highest application rates includes any 

scenario where the estimated dose exceeds the “No-observable-adverse-effect-level (NOAEL)” or other 

benchmark dose, known as a toxicity index. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

application rates, and an additional 19 at highest rates45) that exceed the toxicity indices. 

Under Alternative D, approximately 27,300 acres are projected for annual treatment with 

herbicides46 where estimated doses exceed LOAEL’s for birds and mammals that eat 

vegetation or insects. Alternative D also includes use of three chemicals that could harm 

amphibians. 

In contrast, Alternative B poses the lowest potential risk to wildlife from herbicides. It is 

associated with 5 plausible exposure scenarios at typical application rates, and an additional 8 

at highest rates, that exceed the toxicity indices for birds and mammals; and includes one 

chemical that may harm amphibians. Under Alternative B, we predict that 2,539 acres will be 

treated with herbicides where estimated doses exceed LOAEL’s. 

These differences seem substantial, however in practice, the management direction included 

in all alternatives (including No Action), as well as environmental conditions and animal 

behavior, would tend to minimize actual impacts. At the project scale, choices can be made to 

avoid scenarios that could cause harm to wildlife. For instance, certain chemicals can be 

avoided in specific areas or times of the year, where/when grass-eaters or amphibians may be 

at risk. 

4.4.2 Background 

All invasive plant treatment methods have the potential to temporarily disturb, displace, or 

directly harm various wildlife species. However, the focus of this issue is the effects from 

herbicides on wildlife. The public expressed specific concern about chemicals and their 

effects on animals. Little concern was expressed about the effects of other kinds of treatment 

(manual/mechanical and biological). The effects of these other methods were considered and 

documented in Appendix J. The report concludes that these effects do not differ substantially 

between the alternatives, and that management direction common to all alternatives would 

effectively prevent significant effects from occurring. 

This analysis considers how animals may be exposed to herbicides or NPE (exposure routes), 

and the likelihood that this exposure might actually occur (plausible exposure scenarios). A 

plausible exposure scenario is used as a measure of potential effects to individual animals. 

For most species, the size and distribution of actual treatment areas, the dispersed populations 

of terrestrial wildlife, and the foraging area and behavior of individual animals eliminate the 

 

45 The “typical application rate” is the most common rate used for Forest Service applications. The “highest 

application rate” is the highest allowable rate printed on the herbicide label. 

46 The number of acres predicted to be treated with herbicides comes from the economic analysis done for this 

DEIS. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

potential for direct effects at the population level. Herbicide effects analysis relies on 

information in the Forest Service/SERA Risk Assessments (1998, 2001, 2003) unless 

otherwise noted. The risk assessments used peer-reviewed articles from public scientific 

literature, current Environmental Protection Agency (EPA) documents available to the public, 

and Confidential Business Information47 to evaluate toxicity and risk from the herbicides 

analyzed. Detailed information on the herbicide analysis conducted for this EIS, including the 

potential for endocrine disruption and synergistic effects, is documented in the “Summary of 

Herbicide Effects to Wildlife” report in the analysis file for this EIS. 

Quantitative estimates of worst-case doses of herbicide have been calculated using 

information such as body size, diet, and water concentrations to calculate the potential dose a 

certain type of animal might receive. The estimated dose was compared to the toxicity index 

(i.e., a threshold dose). An estimated dose less than the toxicity index resulted in no plausible 

adverse effect. An estimated dose greater than the toxicity index was called a potential 

adverse effect. If an estimated dose exceeded the toxicity index, it was further evaluated to 

determine if the dose exceeded a known LOAEL. Generally, this analysis was conducted for 

both acute and chronic exposures. 

When data were insufficient to develop an estimate of chronic dose, acute doses were 

evaluated against the chronic toxicity index. When the acute dose is less than the chronic 

toxicity index, there is no plausible risk to the animal, because actual chronic exposures 

would be less than acute exposures. When the acute dose is greater than the chronic toxicity 

index, no estimate of risk can be made and potential effects remain uncertain because existing 

data do not provide sufficient information. However, in this analysis, when an acute dose 

exceeded a chronic toxicity index, it was counted as exceeding the NOAEL or LOAEL, which 

overestimates actual risk, and possibly substantially. This situation occurs for clopyralid, 

dicamba, glyphosate, glyphosate picloram, sethoxydim, sulfometuron methyl, triclopyr and 

2,4-D. 

Data on toxicity of herbicides to amphibians are more limited than data for mammals and 

birds. Consequently, quantitative estimates of dose from exposure scenarios for all chemicals 

have not been created for amphibians in the Forest Service/SERA Risk Assessments.48 

Quantitative exposure scenarios were conducted for amphibians when sufficient data existed 

to support the scenario (e.g. sulfometuron methyl). Toxicity data and exposure scenarios for 

 

47 Confidential Business Information (CBI) is defined as information that contains trade secrets, commercial or 

financial information, or other information that has been claimed as confidential by the submitter (EPA/OPP 

website 2004). Individuals must apply for and be granted access to CBI. 

48 Amphibian exposure scenarios are available for sulfometuron methyl. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

fish provide a reasonable surrogate for effects on amphibians because several studies have 

found that amphibians are less sensitive, or about as sensitive, as fish to some herbicides 

(Berrill et al. 1994; Berrill et al. 1997; Perkins et al. 2000). Comparison of toxicity values for 

fish and amphibians for the herbicides analyzed indicate similar sensitivities (see Forest 

Service/SERA Risk Assessments). 

With a few exceptions, the toxicity index used in this analysis for each herbicide represents a 

sub-lethal effect. Tables 4-8 and 4-9 list the toxicity indices used in the analysis and the 

potential effects to wildlife at the lowest observable adverse effect level (LOAEL). All 

toxicity indices represent the lowest dose (e.g. most sensitive endpoint) from the species most 

sensitive to herbicide effects, for which adequate data are available. 

The same methodology was used to quantitatively estimate risk from the use of surfactants 

added to herbicides prior to their use. Most surfactants used are based on a component known 

as nonylphenol polyethoxylate (NPE). The use of NPE-based surfactants in any of the 12 

herbicides considered in this EIS could result in toxic effects to mammals and birds that eat 

contaminated vegetation or insects at typical and high application rates (project file 

worksheets; USDA Forest Service, 2003). Use of NPE is not likely to adversely affect 

amphibians found in the Pacific Northwest for normal operations. 

However, overspray or accidental spills could produce concentrations of NPE that could 

adversely affect amphibians, particularly in small stagnant ponds. 

The use of herbicide mixtures was also considered in the analysis. No mixtures are permitted 

in Alternative B, so no adverse effects from herbicide mixtures would occur. In the Proposed 

Action and Alternative D, Standard #16 limits mixtures to three or less active ingredients and 

allows use only when the sum of the individual hazard quotients is less than 1.0. This 

standard reduces the likelihood of adverse effects from herbicide mixtures, although some 

uncertainty remains for potential effects from mixtures. This method is a reasonable approach 

when analyzing mixtures of chemicals with different or unknown toxicity mechanisms, when 

expected doses will be below known toxic levels (ATSDR, 2004). It is not known which 

mixtures, if any, will be used during project implementation, so no quantitative estimates of 

exposure are calculated as the scale of this EIS. Standard #16 requires projects to conduct the 

analysis prior to implementation. 

Potential effects to Federally listed and Forest Service Sensitive species are discussed later in 

Chapter 4.7.3). 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 4-8 Toxicity indices used and LOAELs reported for Mammals. 

Classified by Herbicides Included in this EIS (SERA 1998, 2001, 2003, 2004) and NPE surfactants 

(USDA FS 2003). 

Herbicide Duration* Endpoint Dose Species Effect Noted at LOAEL 

Acute NOAEL 75 mg/kg Rabbit Decreased weight gain at 200 mg/kg Chlorsulfuron 

Chronic NOAEL 5 mg/kg/day Rat Weight changes at 25 mg/kg/day 

Acute NOAEL 75 mg/kg Rat Decreased weight gain at 250 mg/kg 

Clopyralid Chronic NOAEL 15 mg/kg/day Rat Thickening of gastric epithelium at 

150 mg/kg/day 

Acute NOAEL 45 mg/kg1 Rat Decreased pup growth at 120 mg/kg Dicamba 

Chronic NOAEL 45 mg/kg/day Rat Decreased pup growth at 120 mg/kg 

Acute NOAEL 175 mg/kg Rabbit Diarrhea at 350 mg/kg 

Glyphosate Chronic NOAEL 175 

mg/kg/day 

Rabbit Diarrhea at 350 mg/kg 

Acute NOAEL 350 mg/kg Rabbit Decreased body weight at 500 mg/kg 

Imazapic Chronic NOAEL2 45 mg/kg Dog Microscopic muscle effects at 137 

mg/kg 

Acute NOAEL 250 mg/kg Dog No effects at highest doses tested 

Imazapyr Chronic NOAEL 250 

mg/kg/day 

Dog No effects at highest doses tested 

Acute NOAEL3 Metsulfuron 25 mg/kg Rat Decreased weight gain at 500 mg/kg 

methyl Chronic NOAEL 25 mg/kg/day Rat Decreased weight gain at 125 mg/kg 

Acute NOAEL 34 mg/kg Rabbit Decreased weight gain at 172 mg/kg Picloram 

Chronic NOAEL 7 mg/kg Dog Increased liver weight at 35 mg/kg4

Acute NOAEL 160 mg/kg5 Rabbit Reduced number of viable fetuses, 

Sethoxydim some dam mortality at 480 mg/kg 

Chronic NOAEL 9 mg/kg/day Dog Mild anemia at 18 mg/kg/day 

Acute NOAEL 87 mg/kg Rat Decreased body weight at 433 mg/kg Sulfometuron 

methyl Chronic NOAEL 2 mg/kg/day Rat Effects on blood and bile ducts at 20 

mg/kg/day 

Acute NOAEL 100 mg/kg Rat Malformed fetuses at 300 mg/kg Triclopyr6

Chronic7 NOAEL 0.5 mg/kg/day Dog Effect on kidney at 2.5 mg/kg/day 

Acute “nonlethal” 10 mg/kg Rat & 

Dog 

Effects on kidney, blood, and liver 

2,4-D Chronic NOAEL 1 mg/kg/day Rat & 

Dog 

Effects on kidney, blood, and liver at 5 

mg/kg/day 

Acute NOAEL 10 mg/kg Rat Slight reduction of polysaccharides in 

liver at 50 mg/kg/day NPE 

Surfactants Chronic NOAEL 10 mg/kg/day Rat Increased weights of liver, kidneys, 

ovaries, and decreased live pups at 50 

mg/kg/day 

* An acute dose is one that occurs over a short time. A chronic dose is a smaller amount given repeatedly over 

time. 

1 Acute values are based on chronic values; if the dose does not cause an effect over a period of 21 weeks, it is 

reasonable to assume that it will not cause effects after one day of exposure (SERA 2004-dicamba). 

2 Imazapic – NOAEL calculated from a LOAEL of 137 mg/kg/day and application of a safety factor of 3 to 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 4-8 Toxicity indices used and LOAELs reported for Mammals. 

Classified by Herbicides Included in this EIS (SERA 1998, 2001, 2003, 2004) and NPE surfactants 

(USDA FS 2003). 

Herbicide Duration* Endpoint Dose Species Effect Noted at LOAEL 

extrapolate from a LOAEL to a NOAEL. 

3 The acute NOAEL of 24 mg/kg is very close to the chronic NOAEL, so chronic value is used for acute 

exposures as well. 

4 USEPA/OPP 1998. 

5 Source of the value used by EPA (180 mg/kg) is not well documented, so the lower value of 160 mg/kg from 

a rabbit study is used as the toxicity index for this analysis. 

6 Triclopyr BEE and TEA have equal toxicities to mammals (SERA, 2003a). 

7 Value taken from Quast et al. 1976 as cited in SERA, 2003-triclopyr. This represents an extremely 

conservative approach, explained in more detail in the write up on triclopyr later in this document. 

Source: SERA 1998, 2001, 2003, 2004 and USDA FS 2003. 

Table 4-9 Toxicity indices used and LOAELs reported for Birds 

Classified by the Herbicides Included in this DEIS. (SERA 1998, 2001, 2003, 2004) and NPE 

surfactants (USDA FS 2003).

Herbicide Duration* Enpoint Dose Species Effects Noted at LOAEL 

Acute NOAEL 1686 mg/kg Quail No significant effects at highest 

dose Chlorsulfuron 

Chronic NOAEL 140 

mg/kg/day 

Quail No significant effects at highest 

dose 

Acute NOAEL 670 mg/kg Mallard & 

Quail 

No signs of toxicity reported, 

LOAEL not determined Clopyralid Chronic1 NOAEL 15 mg/kg/day Rat Thickening of gastric epithelium 

at 150 mg/kg/day 

Acute NOAEL 92 mg/kg2 Mallard Decreased hatchability and 

survival of young at 184 mg/kg Dicamba 

Chronic NOAEL 92 mg/kg/day Mallard Decreased hatchability and 

survival of young at 184 mg/kg 

Acute NOAEL 562 mg/kg Mallard & 

Quail 

No effects at highest dose 

Glyphosate Chronic NOAEL 100 mg/kg Mallard & 

Quail 

No effects on reproduction at 

highest dose 

Acute NOAEL 1100 mg/kg Quail No effects at highest dose 

Imazapic Chronic NOAEL 113 

mg/kg/day 

Quail Decreased weight gain in chicks at 

170 mg/kg/day 

Acute NOAEL 674 mg/kg Quail No effects at highest dose 

Imazapyr Chronic NOAEL 200 

mg/kg/day 

Mallard & 

Quail 

No effects at highest dose 

Acute NOAEL 1043 mg/kg Quail No significant effects at highest 

Metsulfuron dose 

methyl Chronic NOAEL 120 

mg/kg/day 

Mallard & 

Quail 

No significant effects at highest 

dose 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 4-9 Toxicity indices used and LOAELs reported for Birds 

Classified by the Herbicides Included in this DEIS. (SERA 1998, 2001, 2003, 2004) and NPE 

surfactants (USDA FS 2003).

Herbicide Duration* Enpoint Dose Species Effects Noted at LOAEL 

Acute NOAEL 1500 mg/kg Chicken & 

pheasant 

No effect to reproduction. 

LOAEL not reported Picloram 

Chronic3 NOAEL 7 mg/kg/day Dog Increased liver weight at 35 

mg/kg/day 

Acute LOAEL >500 mg/kg Mallard & 

Quail 

No or low mortality at highest 

doses tested. LOAEL not 

Sethoxydim available. 

Chronic LOAEL4 10 mg/kg/day Mallard Decreased number of normal 

hatchlings at 10 mg/kg/day 

Acute LOAEL 312 mg/kg Mallard Decreased weight gain at 625 

Sulfometuron mg/kg/day 

methyl Chronic5 LOAEL 2 mg/kg/day Rat Effects on blood and bile ducts at 

20 mg/kg/day 

Acute LD50 388 mg/kg Quail 50% mortality at 388 mg/kg 

Triclopyr 

BEE6 Chronic NOAEL 10 mg/kg/day Mallard & 

quail

Decreased survival of offspring, 

reduced eggshell thickness at 20 

mg/kg/day 

Acute LD50 535 mg/kg Quail 50% mortality at 535 mg/kg 

Triclopyr 

TEA 

Chronic NOAEL 10 mg/kg/day Mallard & 

Quail 

Decreased survival of offspring, 

reduced eggshell thickness at 20 

mg/kg/day 

Acute LD50 562 mg/kg7 Mallard & 

Quail 

50% mortality at 562 mg/kg 

2,4-D Chronic8 NOAEL 1 mg/kg/day Rat & dog Effects on kidney, blood, and liver 

at 5 mg/kg/day 

Acute LOAEL 10 mg/kg Rat Slight reduction of 

polysaccharides in liver at 50 

NPE mg/kg/day 

Surfactants9 Chronic LOAEL 10 mg/kg/day Rat Increased weights of liver, 

kidneys, ovaries, and decreased 

live pups at 50 mg/kg/day 

* An acute dose is one that occurs over a short time. A chronic dose is a smaller amount given repeatedly 

over time. 

1 Chronic toxicity studies in birds are not available, so the value from mammal studies is used. 

2 Acute values are based on chronic values; if the dose does not cause an effect over a period of 21 weeks, it 

is reasonable to assume that it will not cause effects after one day of exposure (SERA 2004-dicamba). 

3 Chronic toxicity studies in birds are not available, so the value from mammal studies is used. 

4 Based on one study in which a NOAEL was not determined, so the LOAEL is used. 

5 Birds may be somewhat less sensitive than mammals, but data are limited, so the lower value from 

mammal studies is used. 

6 Unlike in mammals, the toxicities of triclopyr BEE and triclopyr TEA are different for birds, so the indices 

of the two forms of triclopyr are presented separately 

7 Weed Science Society of America 2002. 

8 No chronic toxicity data for birds is available; so the mammal chronic value is used. Acute toxicity of 2,4-

D to mammals is somewhat lower than it is for birds. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 4-9 Toxicity indices used and LOAELs reported for Birds 

Classified by the Herbicides Included in this DEIS. (SERA 1998, 2001, 2003, 2004) and NPE 

surfactants (USDA FS 2003).

Herbicide Duration* Enpoint Dose Species Effects Noted at LOAEL 

9 Data on birds is not available in published literature, so values from mammals are used. 

Source: SERA 1998, 2001, 2003; USDA FS 2003; and Weed Science Society of America 2002. 

4.4.3 Direct and Indirect Effects 

All of the alternatives are associated with plausible scenarios that exceed the toxicity indices 

for birds and mammals that eat grass or insects, acres treated by herbicide that result in 

exposures exceeding a LOAEL for some species, and herbicides that may adversely affect 

amphibians. 

The number of plausible scenarios is estimated for each alternative based on the suite of 

herbicides that could be used. It indicates the number of ways that animals could be exposed 

to a harmful dose of herbicide. “Plausible” includes worst-case scenarios, many of which are 

very unlikely to actually occur. Individual projects conducted are likely to involve small total 

acreages, or long narrow road shoulders.49 The default value used in aquatic exposure 

scenarios (e.g. amphibians) is a 10-acre treatment area. Herbicide application to larger areas 

will increase the likelihood of exposure, while a small number of acres will reduce likelihood 

of exposure, compared to that used in the exposure scenarios. The number of acres treated at 

one time within one project area is likely to influence the likelihood of exposure to herbicides 

for wildlife. 

Indirect mortality is possible from sublethal effects that could increase susceptibility to 

predation. Indirect effects to wildlife from cumulative herbicide exposure are also possible. 

For example, if a sublethal exposure affects an internal organ and the effect is not quickly 

reversed, then subsequent exposure could cause cumulative damage. All the herbicides in this 

EIS are excreted rapidly (often within 24-48 hours), and do not accumulate up the food chain, 

reducing, but not eliminating, the potential for these types of cumulative effects. 

The alternatives are discussed from least number of plausible exposure scenarios to most, 

based on the suite of herbicides selected. The herbicides with greatest potential for harm to 

 

49 A review of existing Environmental Assessments for invasive plant treatment in the region indicated that 

many treatment sites are less than one acre in size while projects exceeding 200 acres were not typical. There 

could be rare projects exceeding 1,000 acres during the time frame of this EIS. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

birds and mammals are dicamba, glyphosate, picloram, sethoxydim, sulfometuron methyl, 

triclopyr and 2,4-D. 

Alternative B 

The combination of herbicides in Alternative B has the least number of herbicide scenarios 

that exceed toxicity indices for birds or mammals that eat insects or vegetation (Table 4-10). 

The four herbicides (clopyralid, glyphosate, sethoxydim, and triclopyr) permitted in this 

alternative could result in five scenarios that may exceed the toxicity indices at typical 

application rates (Table 4-1). At the highest labeled application rates, an additional seven 

scenarios exceed the toxicity indices. 

Alternative B also has the least amount of acres treated with herbicides that exceed LOAELs. 

Sethoxydim use at the typical application rates may pose a risk to insectivorous birds and 

mammals. Glyphosate exceeds reported LOAELs only at the highest application rate. At that 

rate, adverse effects to large grass-eating mammals, small insect-eating mammals, large grasseating birds, and small insect-eating birds are plausible. The LOAEL for mammals represents 

a sub-lethal effect of increased incidence of diarrhea. For birds, there was no effect reported 

at the highest doses tested for glyphosate, so the mammal LOAEL is used as a surrogate, 

which likely over-estimates risk to birds. 

Approximately 508 acres are projected for treatment with sethoxydim and 2,031 with 

glyphosate under this alternative, for a total of 2,539 acres annually of herbicides associated 

with a plausible risk to wildlife. This likely over-estimates risk to wildlife because not all 

acres treated with glyphosate would be treated at the highest application rate, nor would they 

all be treated with large broadcast spray applications. For these animals to be exposed to 

potentially harmful doses, these herbicides would have to be broadcast sprayed over a large 

enough area that the animal could forage exclusively within the treatment area for one day 

and have 100 percent of their diet contaminated. In relation to the total acres of habitat 

available for insect and vegetation-eating birds and mammals within the project area (24.9 

million acres on National Forest System land), and the wide distributions of most of their 

populations, 2,539 acres represents a negligible potential risk to wildlife on a regional scale. 

All other scenarios in this alternative exceed only the toxicity indices, and do not approach a 

dose known to cause any adverse effect. The potential for some effects to occur, cannot 

however be ruled out. 

Potentially harmful scenarios from triclopyr are not plausible due to management direction in 

this alternative restricting use to selective application methods (Standard #16). Selective 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

applications are much less likely than broadcast sprays to contaminate forage vegetation or 

insects. Triclopyr scenarios are therefore not counted. All other bird and mammal scenarios 

that exceed the toxicity indices do not approach a dose known to cause any adverse effect (i.e. 

greater than NOAEL but less than LOAEL). But the potential for some effects to occur 

cannot be ruled out. 

Under Alternative B, only glyphosate has the potential for harmful doses to amphibians. The 

surfactant found in some glyphosate formulations is particularly toxic to aquatic species. At 

the highest application rate, some formulations of glyphosate that contain surfactant could be 

lethal to amphibians if the worst-case scenario of runoff from the treatment site were to occur 

(SERA, 2003-glyphosate). However, management direction in this alternative severely 

restricts herbicide use in amphibian habitat, so this scenario is not likely to occur. 

Although the use of herbicides represents potential risks to wildlife, in practice, the 

management direction included in this alternative, as well as environmental conditions and 

animal behavior, would tend to minimize actual impacts. At the project scale, choices can be 

made to avoid situations that could cause harm to wildlife. For instance, certain herbicides 

can be avoided in specific areas or times of the year where/when grass-eaters or amphibians 

may be at risk, or more specific application methods can be used. Actual adverse effects are 

therefore not likely to occur. Any short-term adverse effects would be largely offset by the 

long-term benefits to these species from protecting their habitat from loss due to invasive 

plants. 

Annual acres estimated per year are based on current herbicide use on and off National Forest 

System lands applied as predicted under Alternative B. Site-specific choices can be made at 

the project scale to avoid using herbicides associated with exposure scenarios that may cause 

harm to birds and mammals. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 4-10 Plausible Exposure Scenarios - Birds and Mammals - Alternative B 

Number of Plausible Exposure Scenarios 1

(Blank cells equal zero scenarios) 

(Areas exceeding LOAELs 

are in bold) 

Above NOAEL Above LOAEL 

Herbicide Included 

Estimated 

Acres 

Treated 

Per Year 

Typical 

Application 

Rate 

Highest 

Application 

Rate 

Typical 

Application 

Rate 

Highest 

Application 

Rate 

Clopyralid 2030 2 3 

Glyphosate 2031 1 6 6 

Sethoxydim 508 2 3 2 2 

Triclopyr* 508 2 3 2 2 

Total 5077 5 12 2 8 

Total acres > LOAEL 2,539 

NPE# N/A 4 5 4 4 

1 The number of plausible exposure scenarios is not influenced by the estimated areas treated per year. 

+ Highest Application Rate = total scenarios exceeding toxicity indices at the highest dose rate, which 

includes all those exceeded at the typical rate, plus the additional scenarios that are exceeded when the 

highest application rates are used. 

* Triclopyr not counted because restrictions on use in this standard make exposures exceeding the 

NOAEL or LOAEL very unlikely. 

# Number of scenarios is not included in totals for each alternative because they are the same for each 

alternative and potential effects are discussed in the “Background” portion of this section. 

Proposed Action 

The Proposed Action includes the second lowest number of plausible exposure scenarios that 

may cause harm to birds and mammals that eat grass or insects (Table 4-11). The ten 

herbicides permitted in this alternative could result in 9 scenarios that may exceed the toxicity 

indices at typical application rates. At the highest labeled application rates, an additional 12 

scenarios exceed the toxicity indices. Herbicides permitted in the Proposed Action include 

chlorsulfuron, clopyralid, glyphosate, imazapic, imazapyr, metsulfuron methyl, picloram, 

sethoxydim, sulfometuron methyl, and triclopyr. 

The Proposed Action also has the second lowest amount of acres treated with herbicides that 

exceed LOAELs. The scenarios that exceed the toxicity indices for some animals for 

sethoxydim and glyphosate are the same as discussed for Alternative B. Estimated doses of 

picloram exceed chronic LOAEL at typical application rate for insectivorous birds. At the 

highest rate, picloram exceeds the chronic LOAEL for insectivorous birds and mammals. 

Sulfometuron methyl exceeds the LOAEL for insectivorous birds at the highest application 

rate. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

We predict that 8,989 acres would be treated annually with glyphosate, picloram, sethoxydim 

and sulfometuron methyl in this alternative, posing a plausible risk to some wildlife on these 

acres. This likely over-estimates risk to wildlife because not all acres treated with glyphosate 

would be treated at the highest application rate, nor would all acres be treated by large 

broadcast spray applications. For these animals to be exposed to potentially harmful doses, 

these herbicides would have to be broadcast sprayed over a large enough area that the animal 

could forage exclusively within the treatment area for one day and have 100 percent of their 

diet contaminated. 

The Proposed Action represents a more than a threefold increase in higher risk acres 

compared to Alternative B. However, in relation to the total acres of habitat available for 

insect and vegetation-eating birds and mammals within the project area (24.9 million acres on 

National Forest Land), and the wide distributions of most of their populations, 8,989 acres per 

year represents a negligible risk to wildlife on a regional scale. 

All other scenarios in this alternative exceed only the toxicity indices and do not approach a 

dose known to cause any adverse effect. The potential for some effects to occur cannot be 

ruled out. However, potentially harmful scenarios from triclopyr are not plausible due to 

management direction in this alternative restricting use to selective application methods 

(Standard #16). Triclopyr scenarios are therefore not counted. All other bird and mammal 

scenarios in this alternative exceed only the NOAEL and do not approach a dose known to 

cause any adverse effect (LOAEL). Nevertheless, the potential for some effects to occur 

cannot be completely ruled out. 

Compared to the No Action alternative, the Proposed Action projects more acres treated with 

herbicide each year, but fewer exposure scenarios that may result exceed the NOAEL or 

LOAEL. This is due to the availability of herbicides in the Proposed Action that have little or 

no potential to result in a harmful dose to wildlife (chlorsulfuron, imazapic, imazapyr, and 

metsulfuron methyl). Acres treated with those herbicides do not contribute to the potential 

number of scenarios exceeding the NOAEL or LOAEL. In addition, the Proposed Action 

projects many fewer acres treated with picloram, no use of Dicamba, and restricted use of 

Triclopyr compared to No Action, so the number of scenarios exceeding NOAEL or LOAEL 

is lower for the Proposed Action, even though the projected number of acres treated is higher. 

High application rates of glyphosate with surfactant could be lethal to amphibians, as 

discussed in Alternative B. Management direction in this alternative requires the 

consideration of appropriate formulations to reduce or eliminate negative effects to aquatic 

biota, so this effect is not likely to occur. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

The above measures represent potential risk to wildlife. In practice, the management 

direction included in this alternative, as well as environmental conditions and animal 

behavior, would tend to minimize actual impacts. At the project scale, choices can be made to 

avoid situations that could cause harm to wildlife. For instance, certain chemicals can be 

avoided in specific areas or times of the year where/when grass-eaters or amphibians may be 

at risk, or more specific application methods can be used. Actual adverse effects are therefore 

not likely to occur. Any short-term adverse effects would be largely offset by the long-term 

benefits to these species from protecting their habitat from loss due to invasive plants. 

Annual acres estimated per year are based on current herbicide use on and off National Forest 

System lands applied as predicted under the Proposed Action. Site-specific choices can be 

made at the project scale to avoid using herbicides associated with exposure scenarios that 

may cause harm to birds and mammals. 

Table 4-11 Plausible Exposure Scenarios - Birds and Mammals - Proposed Action 

Number of Plausible Exposure Scenarios1

(Acres exceeding LOAELs are in bold) (blank cells indicated zero scenarios) 

Above NOAEL Above LOAEL 

Herbicide Included 

Estimated 

Acres Treated 

Per Year 

Typical 

Application 

Rate 

Highest 

Application 

Rate+ 

Typical 

Application 

Rate 

Highest 

Application 

Rate 

Chlorsulfuron 620 

Clopyralid 4,648 2 3 

Glyphosate 4,649 1 6 6 

Imazapic 1,860 

Imazapyr 930 

Metsulfuron methyl 620 

Picloram 2,790 2 5 1 2 

Sethoxydim 930 2 3 2 2 

Sulfometuron methyl 620 2 4 

Triclopyr* 930 

Total 18,579 9 21 3 11 

Total acres > LOAEL 8,989 

NPE# N/A 4 5 4 4 

1 The number of plausible exposure scenarios is not influenced by the estimated areas treated per year. 

+ Highest Application Rate = total scenarios exceeding toxicity indices at the highest dose rate, which 

includes all those exceeded at the typical rate, plus the additional scenarios that are exceeded when the 

highest application rates are used. 

* Triclopyr not counted because restrictions on use in this standard make exposures exceeding the NOAEL 

or LOAEL very unlikely. 

# Number of scenarios not included in totals for each alternative because they are the same for each 

alternative and potential effects are discussed in the “Background” portion of this section. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

No Action 

The combination of herbicides in No Action has the second highest total potential for adverse 

effects to birds or mammals that eat insects or vegetation (Table 4-12). The four herbicides 

used in this alternative (dicamba, glyphosate, picloram, and triclopyr) could result in 16 

scenarios that may exceed the toxicity indices at typical application rates. At the highest 

labeled application rates, an additional 14 scenarios exceed the toxicity indices. 

Under No Action, 2,4-D is considered an herbicide of “last resort” and is not to be used unless 

the other herbicides are ineffective. Since 1989, 2,4-D has not been used, or has been used on 

less than 1 acre in the Region. Therefore, effects from use of 2,4-D are not considered 

plausible in this alternative. 

No Action also has the second highest amount of acres treated with herbicides that exceed 

LOAELs. Estimated doses exceeding the LOAEL for glyphosate are discussed for 

Alternative B. Estimated doses exceeding the LOAEL for picloram are discussed in the 

Proposed Action. Under No Action, there are no restrictions on use of triclopyr, so the 

exposure scenarios for triclopyr that exceed a LOAEL are counted in the total. Estimated 

doses of triclopyr exceed LOAELs for large grass-eating mammals, insectivorous mammals, 

and large grass-eating and small insect-eating birds at the typical and highest application 

rates. Estimated doses for dicamba equal or exceed LOAELs for large mammals and birds 

that eat vegetation, and small mammals and birds that eat insects, but only at the highest 

application rate. 

Two of the four herbicides permitted in this alternative exceed LOAELs when used in 

broadcast applications at the typical application rate. Glyphosate and dicamba exceed 

LOAELs only at the highest application rate. We predict that 13, 646 acres will be treated 

annually with herbicides annually under the No Action alternative. This likely over-estimates 

risk to wildlife because not all acres treated with glyphosate would be treated at the highest 

application rate, nor would all acres be treated by large broadcast spray applications. For 

these animals to be exposed to potentially harmful doses, these herbicides would have to be 

broadcast sprayed over a large enough area that the animal could forage exclusively within 

the treatment area for one day and have 100 percent of their diet contaminated. 

No Action represents a fivefold increase in higher risk acres compared to Alternative B, and 

50 percent increase compared to the Proposed Action. However, in relation to the total acres 

of habitat available for insect and vegetation-eating birds and mammals within the project 

area (24.9 million acres on National Forest System land), and the wide distributions of most 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

of their populations, 13,646 acres annually represents a negligible risk to wildlife on a 

regional scale. 

All other scenarios in this alternative exceed only the toxicity indices and do not approach a 

dose known to cause any adverse effect. The potential for some effects to occur cannot be 

ruled out, however. 

For amphibians, triclopyr use at the highest application rate could adversely affect 

responsiveness of tadpoles, subjecting them to increased risk of predation. High application 

rates of glyphosate with surfactant could be lethal to amphibians, as discussed in Alternative 

B. Management direction in this alternative requires the consideration of appropriate 

formulations to reduce or eliminate negative effects to aquatic biota, so this effect is not likely 

to occur. 

The above measures represent potential risk to wildlife. In practice, the management 

direction included in this alternative, as well as environmental conditions and animal 

behavior, would tend to minimize actual impacts. At the project scale, choices can be made to 

avoid situations that could cause harm to wildlife. For instance, certain chemicals can be 

avoided in specific areas or times of the year where/when grass-eaters or amphibians may be 

at risk, or more specific application methods can be used. Actual adverse effects are therefore 

not likely to occur. Any short-term adverse effects would be largely offset by the long-term 

benefits to these species from protecting their habitat from loss due to invasive plants. 

Annual acres estimated per year are based on current herbicide use on National Forest System 

lands in the Region. 

Table 4-12 Plausible Exposure Scenarios - Birds and Mammals - No Action 

Number of Plausible Exposure Scenarios 1

(Acres exceeding LOAELs are in bold) (blank cells indicated zero scenarios) 

Above NOAEL Above LOAEL 

Herbicide Included 

Estimated 

Acres Treated 

Per Year 

Typical 

Application 

Rate 

Highest 

Application 

Rate+ 

Typical 

Application 

Rate 

Highest 

Application 

Rate 

Dicamba 182 6 6 

Glyphosate 1,365 1 6 6 

Picloram 11,050 2 5 1 2 

Triclopyr* 409 6 8 4 7 

Total 13,646 9 25 5 21 

Total acres > LOAEL 13,646 

NPE# N/A 4 5 4 4 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 4-12 Plausible Exposure Scenarios - Birds and Mammals - No Action 

Number of Plausible Exposure Scenarios 1

(Acres exceeding LOAELs are in bold) (blank cells indicated zero scenarios) 

Above NOAEL Above LOAEL 

Herbicide Included 

Estimated 

Acres Treated 

Per Year 

Typical 

Application 

Rate 

Highest 

Application 

Rate+ 

Typical 

Application 

Rate 

Highest 

Application 

Rate 

1 The number of plausible exposure scenarios is not influenced by the estimated areas treated per year. 

+ Highest Application Rate = total scenarios exceeding toxicity indices at the highest dose rate, which 

includes all those exceeded at the typical rate, plus the additional scenarios that are exceeded when the 

highest application rates are used. An acute dose is one large dose. A chronic dose is a smaller amount given 

repeatedly over time. 

* 2,4-D not counted in No Action because of the very rare and minor use over the last 15 years. 

# Number of scenarios not included in totals for each alternative because they are the same for each 

alternative and potential effects are discussed in the “Background” portion of this section. 

Alternative D 

The combination of herbicide in Alternative D has the highest total potential for adverse 

effects to birds or mammals that eat insects or vegetation (Table 4-13). The 12 herbicides 

used in this alternative could result in 25 scenarios that exceed the toxicity indices at typical 

application rates. At the highest labeled application rates, an additional 20 scenarios exceed 

the toxicity indices. Herbicides permitted in the Alternative D include chlorsulfuron, 

clopyralid, dicamba, glyphosate, imazapic, imazapyr, metsulfuron methyl, picloram, 

sethoxydim, sulfometuron methyl, triclopyr, and 2,4-D. There are no restrictions on use of 

triclopyr or the sulfonylurea group of herbicides in this alternative. 

Alternative D also has the highest amount of acres treated with herbicides that exceed 

LOAELs. Estimated doses exceeding LOAELs for dicamba, glyphosate, picloram, 

sethoxydim, sulfometuron methyl, and triclopyr are as discussed above. For 2,4-D, there is an 

unusual amount of variability in the data for potential toxic effects to mammals, making it 

difficult to determine a specific NOAEL or LOAEL. Effects noted on page 3-52 of the 2,4-D 

risk assessment (SERA, 1998-2,4-D) were counted as LOAELs for purposes of this analysis. 

Estimated doses of 2,4-D exceed LOAELs for all insect-eating and vegetation-eating birds 

and mammals evaluated in this analysis at typical and highest application rates. These results 

are consistent with EPA in their draft Registration Eligibility Document for 2,4-D which 

states that “use of 2, 4-D on terrestrial sites presents...potential risks to...mammals and 

birds...” (EPA/OPP, 2004). 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

We predict that 27,299 acres would be treated annually with dicamba, glyphosate, picloram, 

sethoxydim, sulfometuron methyl, triclopyr, and 2,4-D in this alternative. This likely overestimates risk to wildlife because not all acres treated with glyphosate would be treated at the 

highest application rate, nor would all acres be treated by large broadcast spray applications. 

For these animals to be exposed to potentially harmful doses, these herbicides would have to 

be broadcast sprayed over a large enough area that the animal could forage exclusively within 

the treatment area for one day and have 100 percent of their diet contaminated. 

Alternative D has more than double the number of higher risk acres in No Action, more than 

triple the number of higher risk acres in the Proposed Action, and more than 10 times the 

number of higher risk acres in Alternative B. However, in relation to the total acres of habitat 

available for insect and vegetation-eating birds and mammals within the project area (24.9 

million acres on National Forest System land), and the wide distributions of most of their 

populations, 27,299 acres represents a negligible risk to wildlife on a regional scale. 

All other scenarios in this alternative exceed only the toxicity indices but do not approach a 

dose known to cause any adverse effect. The potential for some effects to occur cannot be 

ruled out, however. 

For amphibians, the effects of glyphosate and triclopyr are as discussed above. 2,4-D is likely 

to adversely affect amphibians only in the case of an accidental spill, in which case mortality 

could occur. Because the ester form of 2,4-D is more toxic to aquatic organisms than the salt, 

mortality is much more likely with a spill of the 2,4-D ester. 

The above measures represent potential risk to wildlife. In practice, the management 

direction included in this alternative, as well as environmental conditions and animal 

behavior, would tend to minimize actual impacts. At the project scale, choices can be made to 

avoid situations that could cause harm to wildlife. For instance, certain chemicals can be 

avoided in specific areas or times of the year where/when grass-eaters or amphibians may be 

at risk, or more specific application methods can be used. Actual adverse effects are therefore 

not likely to occur. Under typical circumstances, any short-term adverse effects would be 

largely offset by the long-term benefits to these species from protecting their habitat from loss 

due to invasive plants. 

Annual acres estimated per year are based on current herbicide use on and off National Forest 

System lands applied as predicted under Alternative D (2,4-D use predicted to be extensive 

due to its high effectiveness and low cost). Site-specific choices can be made at the project 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

scale to avoid using herbicides associated with exposure scenarios that may cause harm to 

birds and mammals. 

Table 4-13 Plausible Exposure Scenarios - Birds and Mammals - Alternative D 

Number of Plausible Exposure Scenarios 1

(Acres exceeding LOAELs are in bold) (blank cells indicated zero scenarios) 

Above NOAEL Above LOAEL 

Herbicide Included 

Estimated 

Acres Treated 

Per Year 

Typical 

Application 

Rate 

Highest 

Application 

Rate+ 

Typical 

Application 

Rate 

Highest 

Application 

Rate 

Chlorsulfuron 1,147 

Clopyralid 688 2 3 

Dicamba 688 6 6 

Glyphosate 3,441 1 6 

Imazapic 3,441 

Imazapyr 688 

Metsulfuron methyl 1,147 

Picloram 6,882 2 5 1 2 

Sethoxydim 688 2 3 2 2 

Sulfometuron methyl 1,147 2 4 1 

Triclopyr* 688 6 8 4 7 

2,4-D 13,765 10 10 10 10 

Total 34,410 25 45 17 34 

Total acres > LOAEL 27,299 

NPE# 

1 The number of plausible exposure scenarios is not influenced by the estimated areas treated per year. 

+ Highest Application Rate = total scenarios exceeding toxicity indices at the highest dose rate, which 

includes all those exceeded at the typical rate, plus the additional scenarios that are exceeded when the 

highest application rates are used. 

# Number of scenarios not included in totals for each alternative because they are the same for each 

alternative and potential effects are discussed in the “Background” portion of this section. 

Alternative Comparison 

Table 4-14 compares the alternatives by the measuring factors. The number of plausible 

exposure scenarios for each alternative is based on the toxicity information presented above. 

Harmful doses are those displayed for “above the LOAEL” in the previous tables for each 

alternative. Table 4-14 also displays the number of acres where these scenarios could occur, 

projected annually for each alternative, based on current use on and off national forest applied 

to each alternative based on a static budget (see Chapter 4.6. for more information). 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

The more acres treated with a substance associated with plausible exposure scenarios, the 

greater the potential for a scenario to actually occur. Under all alternatives, site-specific 

choices can be made to avoid herbicides associated with exposure scenarios that may cause 

harm to animals. 

Table 4-14 Summary of Effects by Measuring Factors 

Measuring factor Alternative 

B 

Proposed 

Action 

No Action Alternative 

D 

The maximum number of plausible herbicide 

exposure scenarios in each alternative that could 

result in harmful doses to birds and mammals 

12 21 25 45 

Acres of annual herbicide treatment for each 

alternative where a plausible scenario could 

occur 

2,539 8,989 13,646 27,299 

Number of herbicides approved that may harm 

amphibians 

1 1 3 3 

4.4.4 Cumulative Effects 

Herbicide use occurs on lands other than National Forest System land (see Chapter 4.1 for 

more information). Herbicide use occurs on other federal, state, and county ownerships, state 

and private forestry lands, rangeland, utility corridors, and road rights of way, agricultural 

lands and private residences. Herbicide use on Region Six National Forests could contribute 

to some cumulative effects, but data is lacking that would permit any quantitative estimates of 

cumulative exposure or risk. 

Because wildlife move and migrate, they can be exposed to herbicides on adjacent lands or 

along their migration routes. They can be exposed to the same herbicide on multiple 

ownerships, or a combination of different herbicides within the National Forests or among 

different ownerships. Wildlife can also be exposed to other chemicals, such as insecticides, 

rodenticides, fungicides, and others. This project does not include the use of any other types 

of pesticides, but the herbicide triclopyr and the insecticide chlorpyrifos share a common 

metabolite, TCP, that is toxic to aquatic organisms50.

 Thus, the use of triclopyr could add to 

TCP exposure resulting from the use of chlorpyrifos. Another example of a potential 

cumulative effect is from hexachlorobenzene, a ubiquitous industrial pollutant, which is found 

 

50 The combined risk from chlorpyrifos and triclopyr sources of TCP was considered quantitatively for fish in 

the triclopyr risk assessment (SERA, 2003-triclopyr). Combined application of chlorpyrifos and triclopyr did 

not result in concentrations of TCP that were toxic to fish (SERA, 2003-triclopyr, p. 4-31). 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

in both picloram and clopyralid. While the amounts of hexachlorobenzene added to the 

environment from Forest Service use of picloram and clopyralid do not represent a substantial 

addition in comparison to existing background levels (SERA, 2003-picloram, SERA, 2004-

clopyralid), it could be considered a cumulative effect. 

Eight of the twelve herbicides in this EIS are used for agricultural crops in Washington and 

Oregon. Over 2 million pounds of 2,4-D and over 1 million pounds of glyphosate were 

applied to agricultural land in these two states in 1997 (NCFAP, 1998). These totals do not 

include uses such as lawn care, road maintenance, utility corridors, or private forest land. The 

maximum estimated use on National Forest System land of these two herbicides for any 

alternative would be less than one percent of the agricultural use (see Chapter 4.5). For 

herbicides that have limited or no agricultural uses, Forest Service use would constitute a 

higher percentage of total use in the project area. 

Herbicide use for invasive plant control is estimated to occur on over 1.125 million acres 

annually outside of National Forest land within Oregon and Washington, based on informal 

discussions with State and county agriculture agency personnel. Even the highest use 

estimates of herbicide from Alternative D would only amount to about three percent of the 

total acres treated with herbicides in Oregon and Washington. More precise estimates of noncropland use of herbicides do not exist because there are no mandatory reporting 

requirements. 

A three percent increase in land treated with herbicides, spread across the two state project 

area will not significantly increase potential adverse effects to wildlife. Additive effects from 

herbicide exposure are not likely to occur, or would be minimal, because herbicides 

considered in this EIS do not accumulate in the body, do not concentrate up the food chain 

(see Forest Service/SERA Risk Assessments, 1998, 2001, 2003 and 2004). Also, adverse 

effects would occur to individual animals, rather than populations. 

The small contribution that Forest Service use of herbicide for invasive plant control makes to 

the statewide totals for herbicide use indicate that the potential cumulative effect on a regional 

scale is very small. Likewise, the relatively small differences between the alternatives, in 

comparison to the totals, make insignificant any differences between the alternatives in 

potential for cumulative effects to wildlife. The potential for cumulative effects at more local 

scales must be evaluated at the project level. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

4.4.5 Methodology 

The methodology for identifying this issue and narrowing the analysis to these animals and 

exposure routes is discussed in more detail in “Analysis Methods and Issue Identification 

Regarding Effects to Wildlife for the Invasive Plant EIS” located in the project analysis file. 

The calculation of number of plausible scenarios for typical and highest application rates 

includes any scenario where the estimated dose exceeds the “No-observable-adverse-effectlevel (NOAEL)” or other benchmark dose, known as the toxicity index. Usually, the toxicity 

index is a NOAEL. However, data for some herbicides is insufficient to determine a NOAEL, 

so an LD50 or other value may be use. When an LD50 is used, the potential adverse effect is 

determined to occur at any dose above 0.1 of the LD50. This value is typically used for 

regulatory purposes and appears to be a reasonably conservative level (Hill, 1994). It is also 

the level of concern used by EPA, Office of Pesticide Programs, Environmental Fate and 

Effects Division (EFED) for evaluating risks to federally listed wildlife (EPA 2004). Doses 

below this level would presumably not have any effects. Doses above this level may cause 

sub-lethal responses in the most sensitive bird or mammal species tested. The level at which 

effects begin to be discernable is called the “Lowest-observable-adverse-effect-level 

(LOAEL). Because of the design of toxicity studies, reported LOAEL values are often factors 

of three to ten times higher than the corresponding NOAEL values. Therefore, using 

NOAELs as the toxicity indices, and determining that an adverse effect may occur whenever 

the NOAEL is exceeded is a cautious approach and constitutes a reasonably protective 

“worst-case” analysis. Worst-case analysis is appropriate when there is a lack of data, as is 

the case for herbicide toxicity data and free-ranging wildlife species. 

The most sensitive sub-lethal effect noted for the most sensitive species was used as the 

“benchmark” value, or toxicity index, for each herbicide. Toxicity indices and LOAEL values 

used are located in the “Summary of Herbicide Effects to Wildlife” report (Appendix P). 

When enough data was available, quantitative estimates of dose were calculated using 

exposure scenarios. An example of an exposure scenario used for this analysis is as follows: 

A 70 kg mammal consumes one-day’s worth of contaminated (with herbicide residue) 

grass; daily food consumption is 20 percent of the body weight; and one day’s diet is 

100 percent contaminated. 

This type of scenario allows a quantitative estimate of dose from the herbicide, using 

information from the literature on levels of herbicide residue found on grass or insects, bodysize relationships in food consumption, and excretion or degradation rates of the herbicide. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

When a quantitative estimate of dose for an animal exceeded the toxicity index, we 

determined that the result was a potential adverse effect. 

Occasionally, estimated doses also exceeded known LOAELs. When herbicides exceeded a 

LOAEL, we further evaluated potential risk by using the number of acres likely to be treated 

annually with those herbicides. The predicted number of acres treated per year was taken 

from Chapter 4.6. 

Toxicity data for amphibians is much more limited than that available for mammals or birds. 

The data on amphibians for most herbicides are not sufficient to conduct quantitative 

estimates of exposure. The Forest Service/SERA Risk Assessments use information from the 

literature, when available, and the calculated concentrations of herbicide in water from runoff 

or accidental spill to determine risk to amphibians. When data on amphibian was not 

available, fish were used as a surrogate species. The total number of herbicides permitted in 

each alternative that could adversely affect amphibians was used as an indicator of risk for 

those species. 

4.4.6 Incomplete or Unavailable Information 

The following discussion responds to requirements found in CFR 1502.22. 

What information is missing? 

Invasive plant inventories on the National Forests are incomplete, so the locations of future 

projects cannot be predicted. Recently, a nation-wide database, NRIS/Terra, has been 

implemented that will allow the tracking of existing infestations, the addition of new 

inventory locations, and the aggregation of invasive plant data at regional and national scales. 

However, it is unlikely that budget or staff time allotted will ever be sufficient to have 

completely up-do-date inventories of invasive plants across the Region. 

Research has not been conducted on the effects of these herbicides to most free-ranging 

wildlife species, so the relevant data to specifically evaluate effects to different wildlife 

species is incomplete or unavailable. Species and herbicide combinations number nearly 

1,000 for just the terrestrial wildlife that are threatened, endangered, and Forest Service 

Sensitive species in Region Six. Each rigorous laboratory test conducted to determine the 

toxicity of a chemical to an animal is extremely expensive. Therefore, it is not possible to 

fund all of the expensive and time-consuming laboratory tests needed to provide all of the 

information required to fully evaluate risks to free-ranging wildlife. 

Specific, relevant data that are lacking include: 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

• For several herbicide/species group combinations, both NOAEL and LOAEL values 

have not been determined. 

• The toxicity of the herbicides to amphibians, reptiles, terrestrial invertebrates, birds, 

and other animals found in Region Six is either unknown or limited, and cannot be 

fully characterized with the available data on surrogate species. 

• Analysis of effects for any project involving herbicide use relies upon extrapolations 

from laboratory animals to free-ranging wildlife and controlled conditions to the 

natural environment. 

• There are less data available for birds than mammals, so mammal toxicity values must 

be used in bird exposure scenarios for some of the herbicides considered in this EIS. 

Is this relevant to reasonably foreseeable significant adverse impacts 

essential to a reasoned choice among alternatives? 

No. Inventorying invasive plants on National Forests is a never-ending job. Inventories will 

never be completely up-to-date due to the nature of invasive plant growth and expansion. 

Better estimates of risk could be calculated if laboratory data on the toxicity of the herbicides 

considered in this EIS were available for more groups of animals and more individual species. 

However, because of the dynamic nature of wildlife and their habitat (behavior, weather, 

nutrient availability, contaminant presence, etc.), significant uncertainties would remain for 

predicting short and long-term reactions to herbicide presence in natural settings even if more 

laboratory data were available. Additional field studies are desirable, but are considerably 

more costly than laboratory studies, and are difficult to conduct in such a way that conclusive 

data is produced (Grue, 1994). 

Limitations not withstanding, a substantial amount of scientific data on the toxicity of these 

herbicides to birds and mammals, and some amphibians and invertebrates exist. The data are 

generated by manufacturers to meet EPA regulations before an herbicide may be registered 

for use, and by independent researchers that have published findings in peer-reviewed 

literature. This data is then analyzed according to standard risk assessment methodology to 

reach a characterization of risk for each herbicide. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

4.5 Human Health and Safety Effects 

4.5.1 Introduction 

Invasive plant treatments may result in risks to human health, including contamination of 

drinking water. The health and safety of forestry workers may be at risk from exposure to 

herbicides, working on uneven/broken terrain, use of hand and power tools, inhalation of 

smoke, driving vehicles, exposure to fire, exposure to falling/rolling debris, and the other 

accidents. The public may be exposed to herbicides through direct contact, drift, eating 

contaminated foods, or drinking contaminated water. 

The public expressed particular concern about human health effects related to herbicide 

treatments in municipal watersheds, small watersheds with individual drinking water systems, 

or other areas where forest visitors may consume forest water. Public concerns focused on 

unintended public exposures to herbicides, and particularly upon risks associated with 

exposure to herbicides in drinking water. Public and internal Forest Service comments 

expressed concern about health risks from exposure of workers involved in herbicide 

treatments. All alternatives allow limited herbicide use but vary by the range of herbicides 

considered. 

Internal Forest Service comments expressed concern about health and safety risks to workers 

associated with manual and mechanical treatments. All alternatives include varying amounts 

of manual/mechanical treatments. All methods used to treat invasive plants have some 

potential risk to human health. For biological and cultural methods, most risks are those 

common to any human activities in a wildland environment. Prescribed fire treatments bring 

additional risks associated with fire, smoke and machinery uses, however fire methods are 

predicted to be a minimal part of the Region’s invasive plant treatment program (< 5 percent 

in every alternative). The principal potentially significant human health risks among 

alternatives result from the use of manual and mechanical methods, and from the use of 

herbicides. 

The use of manual/mechanical treatments generally increases as herbicide treatments 

decrease. Therefore, the response of the alternatives to the key issue of human health effects 

consists of two principal components: (1) Exposure for workers and the public to the 

potential risks associated with manual/mechanical treatments of invasive plants; and (2) 

Potential risks of health effects associated with worker and public exposures to herbicide use 

to treat invasive plants, particularly, but not limited to, drinking water exposures,. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

To address this issue, potential worker exposures to hazardous conditions, and toxicity data 

for various herbicides were analyzed for a variety of worker and public exposure scenarios. 

The factors for comparing alternatives are: 

• Number of physical injuries to workers during manual and mechanical invasive plant 

treatment projects 

• Number of NPE and herbicide worker exposure scenarios exceeding reference doses 

• Number of NPE and herbicide public exposure scenarios exceeding reference doses 

(other than drinking water contamination) 

• Number of NPE and herbicide public exposure scenarios for drinking water exceeding 

reference doses 

• Acres of annual herbicide use associated with any plausible worker or public 

contamination scenario 

4.5.2 Direct and Indirect Effects 

Exposure to Hazards from Manual and Mechanical Treatment Methods 

Manual (hand) and mechanical treatments pose hazards to forestry workers. Adverse weather 

and terrain commonly create unfavorable working conditions and increased hazards. Hazards 

associated with adverse weather conditions include extreme heat and cold, which can be 

exacerbated by very dry and very wet conditions. Other hazards include: falling objects 

(especially when cutting trees); tripping or slipping on hazards on the ground; protruding 

objects such as branches and twigs; poisonous plants and insects, and dangerous wildlife. 

Tools and equipment present inherent hazards such as sharp edges on the tools themselves, 

and the hazardous nature of fuels and lubricants used in mechanized equipment. Manual and 

mechanical methods present potential ergonomic hazards related to lifting and carrying 

equipment, and when pulling vegetation. 

Injuries can vary from minor cuts, sprains, bruises, and abrasions to major arterial bleeding, 

compound bone fractures, serious brain concussions, and death. Workers are subject to heatrelated illness or hypothermia when working in extreme weather conditions, and may incur 

musculo-skeletal injuries related to improper body mechanics. Equipment operators could be 

injured from improperly operating the equipment or losing control of equipment on steep or 

slippery terrain. Operators and nearby workers also can suffer hearing damage. Nearby 

workers and the public can be struck by flying debris around some machinery. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

The potential for hazard exposure, i.e. risk of injuries, is exacerbated when workers are 

fatigued, poorly trained, or poorly supervised, and do not follow established safety practices. 

Appropriate training, together with monitoring and intervention to correct unsafe practices, 

would minimize risk of worker injury and illness. Compliance with Occupational Health and 

Safety Administration (OSHA) standards, along with agency, industry and manufacturers’ 

recommendations reduces the potential exposure and risk of injury to workers. Members of 

the public are usually not at risk from manual and mechanical methods unless they are too 

close to machinery that is producing flying debris during treatment. 

Comparison of Alternatives - Exposure to Health Hazards for Workers 

with Manual Treatments 

Forest Service accident reports do not identify the type of work being done when an accident 

occurred, thus data on accidents related specifically to invasive plant treatment is not 

available. Worker exposure to hazards is the direct effect; exposure varies according to the 

amount of manual and mechanical treatment projected for each alternative. A quantified 

relationship between manual treatment acreage and worker exposure, expressed as 

productivity (time/acre pulled) was determined for a large, multiyear handpulling project on 

the Wenatchee National Forest (Henry, 2003). This relationship is applied to EIS alternatives 

to estimate the number of full-time worker equivalents needed to accomplish annual manual 

treatments projected for each alternative. No comparable productivity data is available for 

mechanical treatments. Table 4-15 compares the alternatives in terms of acres of nonherbicide treatments and worker days of exposure related to that acreage. 

Table 4-15 Acres of Treatment and Worker Days of Exposure, Manual Treatment

Alternative Acres of Non-Herbicide Treatment Worker Days of Exposure 

No Action 8,610 36,593 

Proposed Action 7,228 30,719 

Alternative B 10,576 44,948 

Alternative D 2,024 8,602 

Risks to Workers and the Public From Herbicides 

All alternatives allow limited herbicide use but vary by the range of herbicides considered and 

treatment/restoration standards that would apply to herbicide use. As with the previous issue 

about potential effects to wildlife, Forest Service/SERA Risk Assessments were used to 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

evaluate how many worker or public exposure scenarios that potentially exceed the RfD are 

plausible based on the relative mix of herbicides associated with each alternative and the 

toxicity of the chemicals involved. For a background discussion of all toxicological tests and 

endpoints considered in Forest Service/SERA Risk Assessments, refer to SERA, 2001-

Preparation. 

Herbicide application workers are exposed to the same hazards as manual/mechanical 

treatment workers associated with working in an outdoor wildland environment. They may 

also be exposed to machinery noise from pumps, vehicles, and aircraft. 

The human health hazards associated with each herbicide active ingredient were evaluated by 

a thorough review of available toxicological studies. Possible health effects may include 

short-term and long-term adverse effects. Short-term effects may include nausea, headache, 

dizziness, eye or skin irritation, and coughing. Long-term effects may include cancer, 

reproductive, endocrine, immunological, neurological effects; and genetic mutations. 

Toxicity studies were evaluated individually for scientific quality, and cumulatively for all 

similar studies to identify the NOAEL for the most sensitive effect. Precautionary factors are 

then applied to the NOAEL to develop a RfD (Reference Dose) to serve as a benchmark for 

estimating risk of health effects from herbicide application practices considered in the EIS. 

These procedures are detailed in the EIS Appendix Q: Human Health Risk Assessment. 

Appendix Q also details the potential for health effects on sensitive subgroups of the human 

population from the use of herbicides proposed in this EIS. 

Judgments about the potential hazards of herbicides to humans are necessarily based in large 

part on the results of toxicity tests on laboratory animals. Supplemental information on actual 

human poisoning incidents and effects on human populations is analyzed. For a background 

discussion of all toxicological tests and endpoints considered in Forest Service/SERA Risk 

Assessments, refer to SERA, 2001. 

Formulated herbicides as applied in Forest Service invasive plant treatments may contain 

additional compounds besides the active herbicide ingredient that are called impurities or inert 

ingredients. Other additives, called adjuvants, may be mixed with the diluted formulation 

before spraying to either enhance the herbicide activity, or to modify undesirable properties of 

the spray mixture. Additionally, when organisms in the environment internalize chemical 

herbicide formulation in their physiologic systems, they may transform them into other 

compounds called metabolites. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

In addition to the analysis of potential hazards to human health from every herbicide active 

ingredient, Forest Service/SERA Risk Assessments evaluate any available scientific studies of 

potential hazards of other substances associated with herbicide applications: impurities, 

metabolites, inert ingredients, and adjuvants. There is usually less information available on 

these substances because they are not subject to the extensive testing that is required for the 

herbicide active ingredients under FIFRA (Federal Insecticide, Fungicide, and Rodenticide 

Act). Under FIFRA, inerts are classified into one of four categories, called Lists, based on 

available toxicity information (see Appendix Q: Human Health Risk Assessment, Chapter 

5.1.2). In some cases, toxicity data on inerts and adjuvants is produced to comply with other 

federal laws, such as the Federal Food, Drug, and Cosmetic Act. 

Of these categories of substances, only the surfactant NPE has been tested and data produced 

that identify specific and quantifiable hazards to human health. The Forest Service risk 

assessment (Bakke, 2003) identified that NPE may contain nonylphenol, an EPA List 151

inert, which has potential for toxic effects, including endocrine disruption. Human health 

risks from exposure to NPE in invasive plant treatments are analyzed in the Appendix: 

Human Health Risk Assessment. 

The herbicides that would be available for invasive plant treatment under each alternative are 

compared based on Hazard Quotient (HQ), which is the ratio between the estimated dose (the 

amount of herbicide received from a particular exposure scenario) and the RfD. When a 

predicted dose is less than the RfD, then the HQ (estimated dose/RfD) is less than 1.0, and 

toxic effects are unlikely for that specific herbicide application. 

Herbicide Exposure Analysis 

Workers and the public may be exposed to herbicides. Workers are more likely to be exposed 

to herbicides, and risk assessments consider the exposure rates likely for workers. Workers 

include applicators, supervisors, and other personnel directly involved in the application of 

herbicides. The public could be exposed through the drift of herbicide spray through contact 

with sprayed vegetation, or by eating contaminated food items such as berries or edible 

mushrooms. The public may also be exposed by eating game or fish containing herbicide 

residues, or by drinking water that contains such residues. 

 

51 “List 1” inerts are “Inerts of toxicological concern” reference Appendix Q: Human Health Risk Assessment. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Worker Herbicide Exposure Analysis 

Herbicide applicators are most likely to be exposed to herbicides. Two types of worker 

exposure assessments are considered: occupational and accidental/incidental. Occupational 

exposure assessment is used to designate exposures that involve estimates of absorbed dose 

based on routine handling of a specified amount of a chemical during each of three 

application methods (backpack sprayer, ground boom, and aerial). The accidental/incidental 

exposure scenarios involve specific atypical but plausible events that could occur during any 

type of application. 

The exposure for workers is based on the application rate selected for the herbicide, modified 

by several operational and human factors: number of hours worked per day, acres treated per 

hour, and variability in human dermal absorption rates. Rather than focus on a single average 

value, each of these exposure factors involves a range of values, which when combined create 

a range of potential exposure rates for any given application rate. The human health risk 

assessment (Appendix Q) displays potential risks for each of two application rates: a Forest 

Service typical rate and the maximum label rate. For each of these application rates, 

exposures and HQ’s are displayed for two values from the potential range of exposures 

predicted for each herbicide: one typical of the average worker in average working 

conditions, and a maximum exposure value based on the maximum estimate for every 

exposure factor that is considered. Thus, this risk assessment presents four potential exposure 

levels for workers, ranging from the predicted average exposure (typical Forest Service ratetypical exposure variables) to a worst-case predicted exposure (maximum application rate, 

maximum exposure variables). 

Although herbicide application involves many different job activities, exposure rates can be 

defined for three categories: directed foliar applications involving the use of backpacks or 

similar devices including cut surface and streamline sprays; broadcast hydraulic spray 

applications; and aerial applications. In routine applications, workers may contact and 

internalize herbicides mainly through the skin, but also through the mouth, nose or lungs. 

Forest Service/SERA Risk Assessment methodology for estimating internalized worker 

exposures from typical operations encompasses the exposures predicted from multiple routes. 

Additionally, contact with herbicide formulations may cause irritation at the location of the 

exposure, especially the eyes, and also exposed skin. Accidental worker exposures are most 

likely to involve splashing a solution of herbicides into the eyes or on the skin. Two general 

types of exposure were modeled: one involving direct contact with a solution of the herbicide 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

and another associated with accidental spills of the herbicide concentrate onto the surface of 

the skin. 

Public Herbicide Exposure Analysis 

Under normal conditions, members of the general public should not be exposed to substantial 

levels of any of these herbicides. Members of the public would generally not be in areas 

infested with invasive plants during herbicide application. However, dispersed and developed 

recreation areas (trailheads, campgrounds, picnic areas, recreation sites, boat ramps, ski areas, 

work centers, etc) may occur in the vicinity of invasive plant infestations proposed for 

herbicide treatment. 

The Forest Service/SERA Risk Assessments developed two types of public exposure 

situations called scenarios: acute exposures and longer-term or chronic exposures. Acute 

exposures assume that a person has contact with the herbicide either during or shortly after an 

application. Acute scenarios estimate herbicide doses received from direct spray, from 

dermal contact with sprayed vegetation, or from short-term post-spray consumption of 

contaminated fruit or fish. Chronic exposure scenarios estimate doses from long-term 

consumption of fruit or fish following herbicide application. The risk assessments estimate 

risks from acute exposures to the public from drinking contaminated water from two sources: 

from a stream, which herbicide residues have contaminated by runoff or leaches from an 

adjacent herbicide application, and from a pond, which is contaminated by the spilled contents 

of a 200-gallon tanker truck that contains herbicide solution. Forest Service/SERA Risk 

Assessments also estimate risks from long-term exposures to the public from drinking water 

from a pond contaminated by runoff from an adjacent treated area. Some of these scenarios 

are realistic and plausible; others simulate extreme worst-case exposures from situations that 

are highly unlikely to ever be encountered in herbicide applications conducted under 

alternatives in this EIS. Detailed summaries of the public exposure scenarios can be found in 

Forest Service/SERA Risk Assessments. 

Estimates of public exposure from contact with direct spray or from different sources of 

herbicide residues are based on the application rate selected for the herbicide, modified by 

several operational and human factors. The EIS human health risk assessment displays 

potential risks for each of two application rates: a Forest Service typical rate and the 

maximum label rate. For each of these application rates, exposures and HQ’s are displayed 

for two values from the potential range of exposures predicted for each herbicide: one typical 

of the average estimates for each of the exposure factors, and a maximum exposure value 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

based on the maximum estimate for every exposure factor. The EIS effects analysis presents 

two potential exposure levels for members of the public, a predicted average exposure (typical 

Forest Service application rate-typical exposure variables) and a realistic worst-case predicted 

exposure (maximum application rate, maximum exposure variables). 

Comparison of Alternatives – Risks to Workers and the Public From Herbicides 

The human health effects from the use of any herbicide depends on the toxic properties 

(hazards) of that herbicide, the level of exposure to that herbicide at any given time, and the 

duration of that exposure. Both the suite of available herbicides and the restrictions on their 

use vary by alternative. Significant health effects are not expected from herbicide use 

scenarios with a HQ less than 1 (expected dose<RfD). As the treatment HQ for an invasive 

plant control project increases above 1, the margins of safety decrease, compared to the most 

sensitive toxic effect shown in laboratory animal studies. If a predicted dose is greater than 

the RfD (HQ is greater than 1), then the specific physiologic effect, the base NOAEL, and the 

uncertainty factors used in the RfD would be reviewed to refine the risk assessment for a 

particular project. Possible strategies for reducing human health risk at the project scale 

include: reducing the application rate of the herbicide; increasing personal protection or 

buffers; restricting applications to more favorable site conditions and/or using an application 

method with less human exposure. The EIS does not set an absolute threshold of 

unacceptable risk, however, treatments with estimated HQ’s >10 (i.e. one order of magnitude 

greater than the RfD) are of particular concern. The identified threshold for serious risks of 

potential health effects of HQ>10 is based on professional judgment rather than EPA 

regulations; EPA offers no further categorization of exceedances of the RfD. The threshold is 

intended to help reviewers distinguish moderate risks (HQ = 2-10), which could in most cases 

be mitigated through exposure-reducing project design criteria from significant health risks 

(HQ>10) that could be difficult to mitigate if Worst-Case situations occur at that the project 

level. For specific situations where a HQ>10 is identified, the specific physiologic effect and 

the relationship between the NOAEL and the LOAEL may be evaluated to more precisely 

determine whether a toxic effect is actually likely to occur (Durkin, personal communication). 

Potential techniques to minimize human exposures to herbicides include: selecting herbicides 

with low toxicity and low application rates; using application methods that minimize offtarget movement and non-target exposures; reducing contamination of potential drinking 

water by using streamside no-spray zones; providing personal protective equipment for 

applicators, public notification and posting of treated areas. Treatments under all alternatives 

would be accomplished according to strict safety and health standards as required by EPA 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

pesticide regulations and incorporated into herbicide label instructions. The following 

findings apply to herbicides proposed for use in the action alternatives: 

• Two herbicides, 2,4-D and triclopyr consistently have the greatest number of invasive 

plant treatment scenarios where both worker and public health risks exceed EPA target 

levels (i.e. the RfD’s52). These two herbicides also generate nearly all application 

scenarios where the Hazard Quotient (HQ) is predicted to be greater than 10 (i.e. 

expected dose exceeds the RfD by greater than one order of magnitude). The HQ>10 

incidences are all acute (short-term) exposures, and most result from accidents. 

• One herbicide, dicamba, and the adjuvant nonylphenol ethoxylate, have an 

intermediate number of scenarios where worker and public health risks exceed EPA 

target levels, and they have a few scenarios where the HQ exceeds 10. The dicamba 

HQ>10 scenarios are all acute exposures and result from accidents. Human health 

risks could generally be mitigated at the project level, but in some limited situations, 

their use might present significant health risks. 

• The remaining nine herbicides rarely and only minimally exceed the RfD’s established 

by EPA. The scenarios that may slightly exceed EPA target levels are only associated 

with worst-case exposure assumptions and/ or using maximum (rather than typical) 

application rates, except for exposure to NPE (HQ=5) from drinking spillcontaminated pond water. 

Because any risk assessment is based on a number of assumptions, readers and decisionmakers should not make the conclusion that the risk values are absolute. If the assumptions 

are changed, the risk values change. However, the relative risk among herbicides or 

application methods should remain the same unless new toxicity data becomes available. 

Some qualitative comparisons can be made among alternatives, based on the prevention and 

treatment emphases, and allowed herbicides and application methods for each. A table 

accompanies each alternative that displays the projected acres treated with each herbicide, and 

the number of associated worker and public exposure scenarios HQs that range between 1 and 

10, and the number of HQ’s that exceed 10. 

All estimates of herbicide treatment acreage used in alternative comparisons are based on 

current herbicide use on and off national forest, applied to each alternative assuming a static 

budget (see Chapter 4.6. for more information). The number of exposure scenarios shown for 

 

52 See glossary for definition of reference dose. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

each alternative is based on the herbicide and application methods allowed. The number of 

exposure scenarios is not influenced by the projected treatment acres displayed. 

The more acres treated with a substance associated with exposure scenarios, the greater the 

potential for a scenario to actually occur. Under all alternatives, site-specific choices can be 

made to avoid herbicides associated with exposure scenarios that may cause harm to human 

health. 

The EIS does not estimate the number of acres treated with NPE surfactants for each 

alternative. NPE is appropriate for some applications where the herbicide label requires the 

addition of a surfactant. NPE surfactants may also improve efficacy in other herbicide 

applications where addition of a surfactant is optional. In some, but not all of these situations, 

there are alternative surfactants that would be effective that do not contain NPE. For all these 

reasons, the tables identify the number of scenarios where NPE application would exceed HQ 

thresholds, but no meaningful associated acreage can be estimated. 

The tables that address the issue of potential drinking water contamination display the 

herbicide scenarios that may exceed the RfD by either drinking from a stream contaminated 

by runoff/leaching from an adjacent treated area from a herbicide application, or by drinking 

from a pond that is contaminated by a spill of a large tanker truck transporting herbicide mix. 

The EIS risk assessment found only one herbicide exposure scenario exceeds the RfD for 

drinking stream water contaminated by runoff/leaching from an adjacent treated area for any 

herbicide. The HQ for drinking stream water contaminated with drift from 2,4-D applied at 

the maximum allowable rate is projected to be 9. The herbicide 2,4-D is considered for use 

only in Alternative D, and the projected level of exposure is based on a single forest 

application monitoring study. 

The other herbicide application scenarios for contaminated drinking water that exceed the 

RfD involve drinking from a pond contaminated by a spill of a large tank of herbicide 

solution. The risk of a major accidental spill is not linked in a cause-and-effect relationship to 

how much acreage is treated with a particular herbicide; a spill is a stochastic event. A spill 

could happen whenever a tank truck involved in a herbicide operation passes a standing body 

of water. The tables display the number of scenarios for each herbicide that exceed the RfD 

for a child drinking from a spill-contaminated pond. These scenarios represent an extreme 

worst-case scenario that is unlikely to occur in any herbicide application conducted by the 

Forest Service. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Alternative B is considered the alternative with the overall least risk of herbicide-related 

health effects to workers and to the public. However, the only differences among Alternative 

B, No Action, and the Proposed Action, lie in potential risks associated with Worst-case 

scenarios. For typical Forest Service invasive plant treatment practices, No Action, 

Alternaitve B and Proposed Action are essentially equal. No significant health effects to 

workers, nor to the public from invasive plant treatment would be expected. The six 

herbicides added to Proposed Action do not significantly increase risks to workers or the 

public from routine operations. The only risk identified with these alternatives from typical 

operations is a moderate risk of health effects (HQ= 5) if water is consumed from a pond into 

which the surfactant NPE is spilled in association with a herbicide. 

The tables below sum the occurrences of HQ’s for all herbicides (plus NPE) considered for 

use in each alternative. The underlying scenarios and calculated HQ’s are documented in the 

Appendix Q-Human Health Assessment. 

No Action 

The No Action alternative continues the current invasive plant management program. The 

amount and proportion of invasive plant treatments by manual, mechanical, biological, 

cultural and herbicide methods would remain approximately constant to recent historic 

practices. 

The projected number of worker days of exposure to physical hazards during manual invasive 

plant treatment projects is 36,593. 

Four herbicides are available for invasive plant treatments, one of which contains the 

carcinogenic contaminant hexachlorobenzene (HCB). NPE, an adjuvant of potential 

toxicological concern, is also available. Refer to Tables 4-16, 4-17, 4-18, 4-28, 4-29, and 4-

30 for risks to workers and the public regarding the No Action alternative. 

For herbicide treatments assuming typical application rates and exposure factors no worker 

exposures exceed the RfD (i.e. HQ <=1). For herbicide treatments assuming typical 

application rates and exposure factors no public exposure scenarios (non-water) exceed the 

RfD. One accidental drinking water exposure (to NPE) to spill-contaminated water exceeds 

the RfD (HQ=5). 

For herbicide treatments assuming Worst-case (maximum application rates and exposure 

factors) there would be six worker exposures with HQ = 2-10 and five worker exposures with 

HQ > 10. One exposure (picloram) would result in a cancer risk probability of 2 in one 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

million, exceeding the EPA’s cancer risk benchmark of 1 in one million. For herbicide 

treatments assuming Worst-case (maximum application rates and exposure factors) there 

would be five public exposure scenarios with HQ = 2-10 and three public exposures with HQ 

> 10. Two accidental drinking water exposures to a spill-contaminated pond have HQ = 2-10, 

and three have HQ > 10. There are no exposure scenarios for drinking stream water 

contaminated by runoff/leaching from an adjacent treated area for any herbicide in this 

alternative that exceed the RfD. 

Number of Plausible Exposure Scenarios 

(Blank = No Hazardous Exposure Scenarios)

Table 4-16 Worker Potential Health 

Risks (No Action) 

HQ = 2 – 10 HQ > 10 

Herbicide Included Estimated Acres 

Treated Per Year1

Typical 

exposure 

scenario 

Worst Case 

exposure 

scenario 

Typical 

exposure 

scenario 

Worst Case 

exposure 

scenario 

Glyphosate 1365 

Picloram 11,050 1* 

Triclopyr 409 2 4 

Dicamba 182 3 

Total 13,646 

Annual Acres where 

Scenarios May Occur 

0 12,281 0 409 

NPE N/A 3 

* For ground broadcast application workers using picloram in this scenario, a cancer risk of 2 in one million 

is predicted, which exceeds the EPA cancer risk benchmark of 1 in one million. 

1 The number of exposure scenarios is not influenced by the estimated acres treated per year. 

Number of Plausible Exposure Scenarios 

(Blank = No Hazardous Exposure Scenarios) 

Table 4-17 Public Potential Health 

Risks (No Action) 

(Excluding Drinking Water) HQ = 2 – 10 HQ > 10 

Herbicide Included Estimated Acres 

Treated Per Year 

Typical 

exposure

scenario 

Worst Case 

exposure 

scenario 

Typical 

exposure 

scenario 

Worst Case 

exposure 

scenario 

Glyphosate 1365 

Picloram 11,050 

Triclopyr 409 2 3 

Dicamba 182 2 1 

Total 13,646 

Annual Acres where 

Scenarios May Occur 

0 591 0 591 

NPE N/A 1 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Number of Worst-case Exposure Scenarios 

(Blank = No Hazardous Exposure Scenarios) Table 4-18 Public Consumption 

of Contaminated Pond Water 

(No Action) HQ = 2 – 10 HQ > 10 

Herbicide 

Included 

Estimated Acres 

Treated Per Year* 

Typical 

application 

rate 

Maximum 

application 

rate 

Typical 

application 

rate 

Maximum 

application 

rate 

Glyphosate N/A 1 

Picloram 1 

Triclopyr 1 

Dicamba 1 

NPE 1 1 

* The number of exposure scenarios is not influenced by the estimated acres treated per year. 

Proposed Action 

The Proposed Action expands the use of invasive plant prevention practices, which may result 

in a decrease in new infestations needing treatment. Existing infestations would be treated 

with manual methods in greater proportions than in Alternative D, but probably less than 

Alternative B. The exposure to risks, of mostly physical injuries associated with using 

manual and mechanical methods, would be less than Alternative B, but more than Alternative 

D. 

The projected number of worker days of exposure to physical hazards during manual invasive 

plant treatment projects is 30,711. 

The additional herbicides available for treatment in the Proposed Action, compared to 

Alternatives A and B, have low predicted risks to human health, so the risks to workers and to 

the public are not significantly different. In contrast, health risks for the Proposed Action are 

significantly less than for Alternative D. 

Ten herbicides are available for invasive plant treatments, two of which contain the 

carcinogenic contaminant HCB. NPE, an adjuvant of potential toxicological concern, is also 

analyzed. Triclopyr is restricted to selective, directed spray applications (e.g., backpacks, 

directed stem spray, OHV methods); thus certain worker and public exposure scenarios do not 

apply. Worker occupational exposures using triclopyr with ground boom and aerial 

application are not considered. Public exposures to triclopyr through direct spraying of 

individuals are essentially impossible, and they are not considered in this analysis. Dermal 

exposures through vegetation contact is reduced when only target vegetation is sprayed, and 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

any accidental spill would be greatly reduced in magnitude and drinking water risk, compared 

to the tank truck example used in exposure modeling. Refer to Tables 4-19, 4-20, 4-21, 4-28, 

4-29, and 4-30, for risks to workers and the public regarding the Proposed Action. 

Aerial applications of the herbicides chlorsulfuron, metsulfuron methyl, and sulfometuron 

methyl will not be conducted, so aerial applicator HQ’s are not included. The risks of direct 

spray scenarios to the public is greatly reduced, but HQ’s are still calculated based on a 

possibility of accidental direct spray from a ground boom sprayer. 

For herbicide treatments assuming typical application rates and exposure factors no worker 

exposures exceed the target HQ <=1. For herbicide treatments assuming typical application 

rates and exposure factors no public exposure scenarios (non-water) exceed the target HQ 

<=1. One accidental drinking water exposure (to NPE) to spill-contaminated water exceeds 

the RfD (HQ = 5). 

For herbicide treatments assuming Worst-case (maximum application rates and exposure 

factors) there would be nine worker exposures with HQ = 2-10 and one worker exposure with 

HQ > 10. One exposure (picloram) would result in a cancer risk probability of 2 in one 

million, exceeding the EPA cancer risk benchmark of 1 in one million. For herbicide 

treatments assuming Worst-case (maximum application rates and exposure factors) there 

would be three public exposure scenarios with HQ = 2-10 and two public exposures with HQ 

> 10. Five accidental drinking water exposures to a spill-contaminated pond have HQ = 2-10, 

and two have HQ > 10. There are no exposure scenarios for drinking stream water 

contaminated by runoff/leaching from an adjacent treated area for any herbicide in this 

alternative that exceed the RfD. 

Number of Plausible Exposure Scenarios 

(Blank = No Hazardous Exposure Scenarios) 

Table 4-19 Worker Potential Health 

Risks (Proposed Action) 

HQ = 2 – 10 HQ > 10 

Herbicide Included Estimated Acres 

Treated Per Year1

Typical 

exposure 

scenario 

Worst Case 

exposure 

scenario 

Typical 

exposure 

scenario 

Worst Case 

exposure 

scenario 

Chlorsulfuron 620 1 

Clopyralid 4,648 

Glyphosate 4,649 

Imazapic 1,860 

Imazapyr 930 

Metsulfuron methyl 620 

Picloram 2,790 1* 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Number of Plausible Exposure Scenarios 

(Blank = No Hazardous Exposure Scenarios) 

Table 4-19 Worker Potential Health 

Risks (Proposed Action) 

HQ = 2 – 10 HQ > 10 

Herbicide Included Estimated Acres 

Treated Per Year1

Typical 

exposure 

scenario 

Worst Case 

exposure 

scenario 

Typical 

exposure 

scenario 

Worst Case 

exposure 

scenario 

Sethoxydim 930 

Sulfometuron methyl 620 2 

Triclopyr 930 2 2 

Total 18,597 

Annual Acres where 

Scenarios May Occur 

0 4,960 0 930 

NPE N/A 3 

* For ground broadcast application workers using picloram in this scenario, a cancer risk of 2 in one million 

is predicted, which exceeds the EPA cancer risk benchmark of 1 in one million. 

1 The number of exposure scenarios is not influenced by the estimated acres treated per year. 

Number of Plausible Exposure Scenarios 

(Blank = No Hazardous Exposure Scenarios) 

Table 4-20 Public Potential 

Health Risks (Proposed Action) 

(Except Drinking Water) HQ = 2 – 10 HQ > 10 

Herbicide Included 

Estimated Acres 

Treated Per 

Year* 

Typical 

exposure 

scenario 

Worst Case 

exposure 

scenario 

Typical 

exposure 

scenario 

Worst Case 

exposure 

scenario 

Chlorsulfuron 620 

Clopyralid 4,648 

Glyphosate 4,649 

Imazapic 1,860 

Imazapyr 930 

Metsulfuron methyl 620 

Picloram 2,790 

Sethoxydim 930 

Sulfometuron methyl 620 

Triclopyr 930 2 1 

Total 18,597 

Annual Acres where 

Scenarios May Occur 

0 930 0 930 

NPE N/A 1 

* The number of exposure scenarios is not influenced by the estimated acres treated per year. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Number of Worst-case Exposure Scenarios 

(Blank = No Hazardous Exposure Scenarios) Table 4-21 Public Consumption 

of Contaminated Pond Water 

(Proposed Action) HQ = 2 – 10 HQ > 10 

Herbicide Included 

Estimated Acres 

Treated Per 

Year* 

Typical 

application 

rate 

Maximum 

application 

rate 

Typical 

application 

rate 

Maximum 

application 

rate 

Chlorsulfuron N/A 1 

Clopyralid 1 

Glyphosate 1 

Imazapic 1 

Imazapyr 

Metsulfuron methyl 

Picloram 1 

Sethoxydim 

Sulfometuron methyl 

Triclopyr 

NPE 1 1 

* The number of exposure scenarios is not influenced by the estimated acres treated per year. 

Alternative B 

Alternative B expands the use of invasive plant prevention practices, which may result in a 

decrease in new infestations needing treatment. Existing infestations would be treated with 

manual, mechanical, and cultural methods in greater proportions due to increased restrictions 

on herbicide use. The mostly physical injuries associated with manual and mechanical 

methods would be the highest among the alternatives. 

The projected number of worker days of exposure to physical hazards during manual invasive 

plant treatment projects is 44,948. However, the total amount of treatment may be the lowest 

because the direct costs of manual treatment are higher per unit area than herbicide costs. 

The risk of herbicide exposures to workers and the public that could cause health effects, 

would be reduced compared to other alternatives. Biological control may increase somewhat 

as existing infestations increase in size where manual treatments are ineffective and/or 

prohibitively costly. 

Four herbicides are available for invasive plant treatments, one of which contains the 

carcinogenic contaminant HCB. NPE, an adjuvant of potential toxicological concern, is also 

analyzed. Triclopyr is restricted to selective directed spray applications (e.g. backpacks, 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

directed stem spray, ATV methods); thus certain worker and public exposure scenarios do not 

apply. This restriction is identical to the Proposed Action. Refer to Tables 4-22, 4-23, 4-24, 

4-28, 4-29, and 4-30 for risks to workers and the public regarding Alternative B. 

For herbicide treatments assuming typical application rates and exposure factors no worker 

exposures exceed the RfD (i.e. HQ is <=1). For herbicide treatments assuming typical 

application rates and exposure factors no public exposure scenarios (non-water) exceed the 

target HQ <=1. One accidental drinking water exposure (to NPE) to spill-contaminated water 

exceeds the RfD with a HQ=5. 

For herbicide treatments assuming Worst-case (maximum application rates and exposure 

factors) there would be five worker exposures with HQ = 2-10 and one worker exposures with 

HQ > 10. For herbicide treatments assuming Worst-case (maximum application rates and 

exposure factors) there would be three public exposure scenarios with HQ = 2-10 and two 

public exposures with HQ > 10. One accidental drinking water exposure to a spillcontaminated pond has HQ = 2-10, and two have HQ > 10. There are no exposure scenarios 

for drinking stream water contaminated by runoff/leaching from an adjacent treated area for 

any herbicide in this alternative that exceed the RfD. 

Number of Plausible Exposure Scenarios 

(Blank = No Hazardous Exposure Scenarios) 

Table 4-22 Worker Potential Health 

Risks (Alternative B) 

HQ = 2 – 10 HQ > 10 

Herbicide Included Estimated Acres 

Treated Per Year* 

Typical 

application 

rate 

Worst Case 

exposure 

scenario 

Typical 

application 

rate 

Worst Case 

exposure 

scenario 

Glyphosate 2031 

Clopyralid 2030 

Sexothydim 508 

Triclopyr 508 2 2 

Total 5077 

Annual Acres where 

Scenarios May Occur 

0 508 0 508 

NPE N/A 3 

* The number of exposure scenarios is not influenced by the estimated acres treated per year. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Number of Plausible Exposure Scenarios 

(Blank = No Hazardous Exposure Scenarios) 

Table 4-23 Public Potential Health 

Risks (Alternative B) 

(Except Drinking Water) HQ = 2 – 10 HQ > 10 

Herbicide Included Estimated Acres 

Treated Per Year* 

Typical 

exposure

scenario 

Worst Case 

exposure 

scenario 

Typical 

exposure 

scenario 

Worst Case 

exposure 

scenario 

Glyphosate 2031 

Clopyralid 2030 

Sexothydim 508 

Triclopyr 508 2 1 

Total 5077 

Annual Acres where 

Scenarios May Occur 

0 508 0 508 

NPE N/A 1 

* The number of exposure scenarios is not influenced by the estimated acres treated per year. 

Number of Worst-case Exposure Scenarios 

(Blank = No Hazardous Exposure Scenarios) Table 4-24 Public Consumption 

of Contaminated Pond Water 

(Alternative B) HQ = 2 – 10 HQ > 10 

Herbicide Included Estimated Acres 

Treated Per 

Year 

Typical 

application 

rate 

Maximum 

application 

rate 

Typical 

application 

rate 

Maximum 

application 

rate 

Glyphosate N/A 1 

Clopyralid 1 

Sexothydim 

Triclopyr 

NPE 1 1 

Alternative D 

Alternative D emphasizes local flexibility in implementing invasive plant prevention, and 

increased economic efficiency of treatments. The acreage treated with non-herbicide methods 

is predicted to be the lowest of all alternatives considered. Worker exposures to health 

hazards from manual treatment, would be correspondingly the lowest among alternatives. 

The projected number of worker days of exposure to physical hazards during manual invasive 

plant treatment projects is 8,602. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

The acreage likely to be treated with herbicides is the highest among alternatives. Twelve 

herbicides are available, including all higher-risk and intermediate-risk chemicals, without 

any restrictions to application methods (beyond those required by law and by the label). 

Existing infestations would be treated with manual and mechanical in lower proportions than 

other alternatives. The exposure to risks of mostly physical injuries associated with using 

manual and mechanical methods would be the lowest among alternatives. 

Herbicide treatment would be the highest among the alternatives. The additional herbicides 

available only in Alternative D have the highest risks of health effects to workers and the 

public, so overall herbicide health risks are likely to be greater than other alternatives. 

Twelve herbicides are available for invasive plant treatments, two of which contain the 

carcinogenic contaminant HCB. NPE, an adjuvant of potential toxicological concern, is also 

analyzed. Refer to Tables 4-25, 4-26, 4-27, 4-28, 4-29, and 4-30 for risks to workers and the 

public regarding Alternative D. 

For herbicide treatments assuming typical exposure factors for typical application rates, there 

is one occupational worker exposure and no accidental worker exposure that exceeds the 

target HQ <=1. For herbicide treatments assuming typical exposure factors for typical 

application rates, there are 3 operational public exposures and 2 accidental public exposures, 

and two public exposures that exceed the target HQ by a factor greater than 10. 

For herbicide treatments assuming typical application rates and exposure factors one worker 

exposure exceeds the target HQ <=1. For herbicide treatments assuming typical application 

rates and exposure factors there are two public exposure scenarios with HQ = 2-10 and one 

public exposure with HQ > 10. One accidental drinking water exposure to spill-contaminated 

water exceeds the RfD (HQ = 5). 

For herbicide treatments assuming Worst-case (maximum application rates and exposure 

factors) there would be twelve worker exposures with HQ = 2-10 and six worker exposures 

with HQ > 10. One exposure (picloram) would result in a cancer risk probability of 2 in one 

million, exceeding the EPA cancer risk benchmark of 1 in one million. For herbicide 

treatments assuming Worst-case (maximum application rates and exposure factors), there are 

nine public exposure scenarios with HQ = 2-10 and nine public exposures with HQ > 10. Six 

accidental drinking water exposures to a spill-contaminated pond have HQ = 2-10, and four 

have HQ > 10. Alternative D has the only herbicide exposure scenario among all alternatives 

that exceeds the RfD for drinking stream water contaminated by runoff/leaching from an 

adjacent treated area for any herbicide. The HQ for drinking stream water contaminated with 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

drift from 2,4-D applied at the maximum allowable rate is projected to be 9. (2,4-D is 

considered for use only in Alternative D). 

For all application rates, both typical and maximum exposure assumptions, Alternative D has 

many more exposure scenarios that exceed EPA target exposure levels than any other 

alternative. Alternative D also has many more worker, and public exposure scenarios that 

exceed EPA target levels by a factor of greater than ten. 

Annual acres estimated per year are based on current herbicide use on an off National Forest 

System lands applied as predicted under Alternative D (2, 4-D use herbicide predicted to be 

extensive due to its high effectiveness and low cost). Site-specific choices can be made at the 

project scale to avoid using herbicides associated with exposure scenarios that may cause 

harm to workers or the public. 

Number of Plausible Exposure Scenarios 

(Blank = No Hazardous Exposure Scenarios) 

Table 4-25 Worker Potential Health 

Risks (Alternative D) 

HQ = 2 – 10 HQ > 10 

Worst 

Case 

exposure 

scenario 

Herbicide Estimated Acres 

Treated Per Year1

Typical 

exposure 

scenario 

Worst 

Case

exposure

scenario 

Typical 

exposure

scenario 

2,4-D 13,765 1 3 

Chlorsulfuron 1,147 1 

Clopyralid 688 

Dicamba 688 3 

Glyphosate 3,441 

Imazapic 3,441 

Imazapyr 688 

Metsulfuron methyl 1,147 

Picloram 6,882 1* 

Sethoxydim 688 

Sulfometuron methyl 1,147 3 

Triclopyr 688 2 4 

Total 34,410 

Annual Acres where 

Scenarios May Occur 

Typical 13,765 

Worst-case 24,317 

13,765 10,552 0 14,453 

NPE N/A 3 

* For ground broadcast application workers using picloram in this scenario, a cancer risk of 2 in one 

million is predicted, which exceeds the EPA cancer risk benchmark of 1 in one million. 

1 The number of exposure scenarios is not influenced by the estimated acres treated per year. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Number of Plausible Exposure Scenarios 

(Blank = No Hazardous Exposure Scenarios) 

Table 4-26 Public Potential Health 

Risks (Alternative D) 

(Except Drinking Water) HQ = 2 – 10 HQ > 10 

Worst 

Case 

exposure 

scenario 

Herbicide Estimated Acres 

Treated Per Year* 

Typical 

exposure

scenario 

Worst 

Case

exposure

scenario 

Typical 

exposure

scenario 

2,4-D 13,765 2 3 1 3 

Chlorsulfuron 1,147 

Clopyralid 688 

Dicamba 688 2 1 

Glyphosate 3,441 

Imazapic 3,441 

Imazapyr 688 

Metsulfuron methyl 1,147 

Picloram 6,882 

Sethoxydim 688 

Sulfometuron methyl 1,147 

Triclopyr 688 2 3 

Total 34,410 

Annual Acres where 

Scenarios May Occur 

13,765 15,141 13,765 15,141 

NPE N/A 1 

* The number of exposure scenarios is not influenced by the estimated acres treated per year. 

Number of Worst-case Exposure Scenarios 

(Blank = No Hazardous Exposure Scenarios) 

Table 4-27 Public 

Consumption of Contaminated 

Pond Water (Alternative D) HQ = 2 – 10 HQ > 10 

Herbicide 

Estimated 

Acres Treated 

Per Year 

Typical 

application 

rate 

Maximum 

application 

rate 

Typical 

application 

rate 

Maximum 

application 

rate 

2,4-D N/A 1 1* 1 

Chlorsulfuron 1 

Clopyralid 1 

Dicamba 1 

Glyphosate 1 

Imazapic 1 

Imazapyr 

Metsulfuron methyl 

Picloram 1 

Sethoxydim 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Number of Worst-case Exposure Scenarios 

(Blank = No Hazardous Exposure Scenarios) 

Table 4-27 Public 

Consumption of Contaminated 

Pond Water (Alternative D) HQ = 2 – 10 HQ > 10 

Herbicide 

Estimated 

Acres Treated 

Per Year 

Typical 

application 

rate 

Maximum 

application 

rate 

Typical 

application 

rate 

Maximum 

application 

rate 

Sulfometuron 

methyl 

Triclopyr 1 

NPE 1 1 

* Alternative D has the only herbicide exposure scenario among all alternatives that exceeds the RfD for 

drinking stream water contaminated by runoff/leaching from an adjacent treated area for any herbicide. 

The HQ for drinking stream water contaminated with drift from 2,4-D applied at the maximum allowable 

rate is projected to be 9. All other exceedances result from the accidental scenario of drinking from a pond 

immediately after a large spill. 

Summary Tables 

Table 4-28 Number of Plausible Exposure Scenarios (excludes drinking water 

scenarios) 

Worker 

Herbicide 

Worker 

NPE 

Public 

Herbicide 

Public 

NPE 

Typical Exposure scenari

o

Maximum Exposure scenari

o

Typical Exposure scenari

o

Maximum Exposure scenarioTypical Exposure scenarioMaximum Exposure scenarioTypical Exposure scenarioMaximum Exposure scenario

 HQ 2- 10  HQ >10  HQ 2- 10  HQ >10  HQ 2- 10  HQ >10  HQ 2- 10  HQ >10  HQ 2- 10  HQ >10  HQ 2- 10  HQ >10  HQ 2- 10  HQ >10  HQ 2- 10  HQ >10 

No Action 6* 4 3 4 4 1 

Proposed 

Action 

6* 2 3 2 1 1 

Alternative B 2 2 3 2 1 1 

Alternative D 1 10* 7 3 2 1 7 7 1 

* One scenario (ground broadcast application workers using picloram), predicts a cancer risk of 2 in one 

million, which exceeds the EPA cancer risk benchmark of 1 in one million. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 4-29 Public Consumption of Contaminated Water: Herbicide + NPE 

Typical Exposure Scenario Maximum Exposure Scenario 

HQ 2 - 10 HQ > 10 HQ 2 - 10 HQ > 10 

No Action 1 2 2 

Proposed Action 1 6 

Alternative B 1 3 

Alternative D 1 2 6 3 

4.5.3 Alternative Comparison 

Table 4-30 Summary of Effects by the Measuring Factors 

Exposure 

Scenario

No 

Action 

Proposed 

Action 

Alternative 

B 

Alternative 

D 

Number of Worker Days of 

Exposure to Manual Treatment 

Hazards 

N/A 36,593 30,719 44,948 8,602 

Total Herbicide and NPE 

WORKER Scenarios that Exceed 

RfD 

Typical 

Worst-Case 

0 

13 

0 

11 

0 

7 

1 

20 

Total Acres Where Worker 

Scenarios > RfD May Occur 

Typical 

Worst-Case 

0 

12,281 

0 

4,960 

0 

508 

13,765 

24,317 

Total Herbicide and NPE PUBLIC 

Scenarios that Exceed RfD (other 

than drinking water contamination) 

Typical 

Worst-Case 

0 

9 

0 

4 

0 

4 

3 

15 

Total Acres Where Public 

Exposure Scenarios >RfD May 

Occur 

Typical 

Worst-Case 

0 

591 

0 

930 

0 

508 

13,765 

15,141 

Total Herbicide and NPE PUBLIC 

Scenarios that Exceed RfD for 

Drinking Water Contaminated by 

runoff / leaching 

Typical 

Worst-Case 

0 

0 

0 

0 

0 

0 

0 

1 

Treatment Acres where Risk of 

Public Drinking Water 

Contaminated by runoff / leaching 

>RfD 

Typical 

Worst-Case 

0 

0 

0 

0 

0 

0 

0 

13,765 

Total Herbicide and NPE PUBLIC 

Scenarios that Exceed RfD for 

Drinking Water Contaminated by 

Tanker Spill into Pond 

Typical 

Worst-Case 

1 

4 

1 

6 

1 

3 

2 

9 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Alternative B is considered the alternative with the overall least risk of herbicide-related 

health effects to workers and to the public. However, the only differences among Alternative 

B, No Action, and the Proposed Action, lie in potential risks associated with Worst-case 

scenarios. For typical Forest Service invasive plant treatment practices, Alternatives A, B and 

C are essentially equal. No significant health effects to workers, nor to the public from 

invasive plant treatment would be expected. The six herbicides added to the Proposed Action 

do not significantly increase risks to workers or the public from routine operations. The only 

risk identified with these alternatives from typical operations is a moderate risk of health 

effects for the surfactant NPE (HQ= 5) from an extreme accidental scenario: a child drinks 

from a small pond after an accidental spill of 200 gallons of a herbicide field solution 

containing NPE. 

4.5.4 Cumulative Effects 

Two related possible categories of potential human health effects comprise “cumulative 

effects”: synergistic effects from exposures to multiple chemicals that interact other than by 

additive effects; and additive cumulative effects resulting from multiple exposures to one 

herbicide chemical from multiple sources. Appendix G discusses the available data and risk 

analysis for each type of effect for each herbicide considered in this EIS. The potential for 

these effects from alternatives proposed in the EIS is discussed here. 

The potential for cumulative risks to workers from non-chemical treatment methods is 

significant. People may be injured more than once given the hazardous outdoor working 

conditions and use of chainsaws or heavy equipment. Some adverse health effects from 

operating motorized equipment are cumulative and non-reversible, such as hearing loss and 

repetitive stress injuries. Forestry workers may be exposed to these hazards on all land 

ownerships. No estimate of acreage of non-chemical invasive plant management is available. 

State Occupational Safety and Health Administration (OSHA) rules apply to non-herbicide 

work on all ownerships. The potential for cumulative risks to the public is insignificant, 

because they would not be operating the machinery and are unlikely to be in close proximity 

when invasive plant treatments are being conducted. 

Herbicide application workers will be exposed to some of the same hazards from working in 

an outdoor environment as those who are conducting manual/mechanical treatments. 

Workers exposed to pumps and aircraft engines are at risk of cumulative hearing loss, though 

exposures would likely be of shorter duration and frequency than for chainsaw or road 

brushing workers. The potential for cumulative health effects to workers and the public from 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

repeated exposures to the herbicides applied to treat invasive plants in EIS alternatives is 

insignificant. Most of these herbicides do not bioaccumulate in humans, are rapidly 

eliminated from the body, and they persist in the environment for a relatively short time 

(generally less than 1 year). No additive doses from re-treatments in subsequent years are 

predicted. The herbicides clopyralid, picloram and sulfometuron methyl persist in the 

environment for more than one year; however, re-treatment in the following year is not 

expected; thus no additive doses from re-treatment are predicted. 

The potential for cumulative human health effects from any herbicide use proposed in this 

EIS, combined with other potential herbicide applications in the analysis area, is encompassed 

in the chronic exposure scenarios, which consider the effect of repeated exposures. The risk 

of toxic health effects from repeated exposure to any of these herbicides at doses that are less 

than the chronic toxicity benchmark(chronic RfD) is low. These chronic scenarios previously 

identified for each alternative with moderate or high risks of health effects, would reflect 

moderate or high risks of cumulative effects, from multiple applications made in compliance 

with EPA label requirements, and result in comparable repeated doses. 

Herbicide use proposed in the alternatives would amount to less than three percent of total 

herbicide projected use in Oregon and Washington for invasive plant treatment. The quantities 

of herbicides proposed for use in EIS alternatives is further diminished in significance of their 

contribution to potential significant cumulative health effects in the context of all herbicide 

use in the analysis area. The choice between alternatives in this EIS would not substantially 

affect cumulative health risks from the overall use of these herbicides in the human 

environment. 

4.5.5 Methodology 

The methodologies used to assess human health risks from alternatives in this EIS are based 

in the Forest Service Herbicide Risk Assessments for each herbicide considered. For a 

background discussion of all toxicological tests and endpoints considered in Forest Service 

Risk Assessments, refer to SERA, 2001-Preparation. 

The risks of adverse health effects from the use of any herbicide depends on the toxic 

properties of that herbicide, the level of exposure to that herbicide at any given time, and the 

duration of that exposure. The EIS Human Health Effects section analyzes the potential for 

adverse health effects to workers and members of the public, from treatment of invasive 

plants using the herbicides as proposed in EIS alternatives. Most of the information and 

analysis used to estimate human health effects of EIS alternatives, is cited from risk 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

assessments prepared for each individual herbicide by Syracuse Environmental Research 

Associates, Inc. (SERA), under contract to the USDA-Forest Service. Specific methods used 

in preparing the Forest Service/SERA Risk Assessments are described in SERA, 2001-

Preparation. To evaluate potential risks to human health and the environment, Forest 

Service/SERA Risk Assessments use peer-reviewed articles from the open scientific literature 

and current EPA documents, including Confidential Business Information. Only specific 

information that is NOT derived from the relevant SERA Risk Assessments is specifically 

cited in this section. 

The analysis of the potential human health effects associated with the use of herbicides uses 

the methodology of risk assessment generally accepted by the scientific community (National 

Research Council, 1983; EPA, 1987 in SERA, 2001-Preparation). Forest Service/SERA Risk 

Assessments estimate doses to workers from herbicide application, and doses to the public 

from being on or near an application site. Estimated worker doses and public doses are 

compared to Reference Doses (RfD). Acute RfD’s are quantified levels of exposure 

established by the U.S. Environmental Protection Agency’s (EPA) to be considered protective 

of a single exposure. In EPA has not established an acute RfD for some herbicides considered 

in this EIS; Forest Service/SERA Risk Assessments will do so where available data are 

sufficient. Chronic RfD’s are quantified levels of exposure established by the U.S. 

Environmental Protection Agency’s (EPA) to be considered protective of lifetime or chronic 

exposures. RfD’s are based upon doses shown to cause no observed ill effects to test animals 

in either short-term (acute) or long-term (subchronic or chronic) studies. Human exposure 

doses are reduced from those found protective of test animals, based on possible variation 

between species and among individual people. Different types of possible effects are 

considered, including acute and chronic systemic effects, cancer and mutations, and 

reproductive effects. 

The Invasive Plant EIS uses the threshold levels for acceptable risk used by EPA: the RfD is 

the threshold level for exposure for non-carcinogenic health effects, and 1 chance in 1 million 

is the cancer risk benchmark level. A Hazard Quotient (HQ) has been computed for the 

exposures estimated for workers and members of the public by dividing the dose predicted 

from invasive plant treatment by the RfD. In general, if the HQ is less than or equal to 1, the 

risk of effects is considered negligible. 

One of the primary uses of a risk assessment is for risk management. Decision-makers can 

use the EIS human health risk assessment to identify those herbicides, application methods, or 

exposure rates that pose the greatest risks to workers and the public. Specific mitigation 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

measures can then be employed where the decision-maker feels the risks are unacceptably 

high. Reducing exposure can reduce risk. The use of streamside buffer zones, personal 

protective equipment for applicators, and posting of treated areas are all examples of ways to 

reduce exposure to workers and the public. Decision-makers would determine when to 

implement mitigation measures on specific treatment projects for herbicides available for use 

in the Record of Decision for the EIS. 

Because any risk assessment is based on a number of assumptions, readers and decisionmakers should not conclude that the risk values are absolute. If the assumptions are changed, 

the risk values change. However, the relative risk among herbicides or methods should 

remain the same unless new toxicity data becomes available. 

Refer to Chapter 3.3.2, Herbicide Risk Assessments for additional discussion of the 

methodologies used to estimate risks to human health in this EIS. 

4.5.6 Incomplete or Unavailable Information 

Forest Service/SERA Risk Assessments identify and evaluate incomplete and unavailable 

information that is potentially relevant to human health effects resulting from herbicide use in 

EIS alternatives. Information is necessarily incomplete on potential toxic doses of most 

herbicides in human, and on the variation in dos-response among individuals in the human 

population. SERA (2001) discuses how the Forest Service/SERA Risk Assessments apply 

generally-accepted scientific and regulatory methodologies to encompass these uncertainties 

in predictions of risk. 

Individual Forest Service/SERA Risk Assessments identify and evaluate missing information 

for that particular herbicide and its relevance to risk estimates. Such missing information may 

involve any of the three elements needed for risk assessments: hazard; exposure; or doseresponse relationships. A peer-review panel of subject matter experts reviews the 

assumptions, methodologies and analysis of significance of any such missing information. 

SERA addresses and incorporates the finding of peer review in the final herbicide risk 

assessment. 

The prediction of potential toxic effects from human exposure to multiple chemicals, natural 

and synthesized also involves necessarily incomplete and unavailable information, 

considering the complexity and unpredictability of potential multiple chemical exposures. 

Forest Service/SERA Risk Assessments evaluate the potential effects of exposure to multiple 

chemicals in herbicide formulations considered for use in this EIS. To estimate potential 

health effects for human dose-response combinations of multiple chemicals including 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

compounds not considered in the EIS, the EIS uses the generally-accepted peer-reviewed 

scientific methodology developed by the U. S EPA and the U.S. Public Health Service 

described in Appendix Q. 

4.6 Costs of Treatment and Effects on Land Use 

4.6.1 Introduction 

Management of invasive plants affects the goods, services, and uses provided by National 

Forest System land and the costs of managing those lands. Invasive plant management may 

compete with other important land management needs, resulting in cost tradeoffs. 

Management of timber, vegetation, roads, public access, range, recreation, lands, minerals, 

fire, and fuels may be affected by costs increases or loss of opportunity due to invasive plant 

management. For example, all action alternatives will require pack stock users to supply 

weed-free feed on some or all National Forest System lands, which will increase the cost of 

using pack stock and may restrict their ability to use these lands. 

Prevention and management of invasive plants can be costly and fiscal resources are always 

limited. Increased operating costs due to invasive plant management many result in direct or 

indirect transfer of costs to land management programs or users of National Forest System 

lands. 

Variations in standards between alternatives result in differences in the availability of 

management tools and the supply of goods, services, and uses. In turn, this affects the natural 

and human environment. Three categories of effects are considered for this issue: 

1. Direct financial costs of the invasive plant treatment program projected for each 

alternative; 

2. Direct and indirect costs to programs and outputs due to standards in each alternative; 

and 

3. Effects to forest users and permittees due to changes in access or other program 

adjustments influenced by standards. 

The measuring factors for the alternatives, related to these effects are: 

• Annual acres of treatment and average treatment cost per acre; 

• Percent increase in cost of heavy equipment work; 

• Tendency of standards to result in road closures or loss of roaded access; 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

• Tendency of standards to affect range allotments and permittees; and 

• Acres of National Forest land where weed-free feed is required. 

Existing data was used to estimate impacts in quantitative terms such as dollars or reduction 

of output, where possible. Where existing data were inadequate to estimate quantitative 

effects, effects were explored in a qualitative fashion, based in consultation with professionals 

in the respective resource areas. Whether explored quantitatively or qualitatively, the effects 

disclosed in this section are based on the best reasonably available information from managers 

and scientists. 

Chapter 4.6 is organized to display effects by the measuring factors. Chapter 4.6.2 discusses 

the cost of invasive plant treatment. Chapter 4.6.3 discusses the effects of the prevention 

standards. Chapter 4.6.4 discusses the cost of heavy equipment work. Chapter 4.6.5 

discusses weed free requirements. Chapter 4.6.6 discusses effects to range allotments and 

permittees. Chapter 4.6.7 discusses effects to road and off-road vehicle access, and finally, 

Chapter 4.6.8 compares the alternatives by the measuring factors. 

4.6.2 Costs Of Invasive Plant Treatment 

Direct and Indirect Effects 

The Forest Service currently spends about 4.8 million dollars annually treating about 25,000 

acres of invasive plants on National Forests in Region Six. 

Table 4-31 identifies the current treatment costs and acres treated. Costs vary from $40 per 

acre using fire, to $340 per acre using manual methods. Approximately 54 percent of current 

treatments are ground-based herbicide applications. Manual treatments account for about 61 

percent of total treatment expenditures. The action alternatives are compared to this baseline. 

Table 4-31 Current Annual Treatment Acreage and Cost 

Method Average Acres 

per year 

Percent Acres

by Method 

Cost Per 

Acre Total Cost Percent Cost by Method 

Herbicide- Ground 13,646 54% $125 $1,705,750 35% 

Herbicide- Aerial 0 0% $50 0% 

Manual 8,610 34% $340 $2,927,400 61% 

Mechanical 770 3% $100 $77,000 2% 

Biological 996 4% $70 $69,720 1% 

Fire 382 2% $40 $15,280 <1% 

Cultural 202 1% $50 $10,100 <1% 

Total 24,606 100% $4,805,250 100% 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

For the action alternatives, estimated costs are based on the first year of treating previously 

untreated areas. Some treatment methods (e.g. biological control) may be needed only one 

year. Other treatments may need to be reapplied at decreased levels (e.g. herbicides) and 

some treatments may need to be repeated annually with little or no reduction in application 

level (e.g. mechanical). 

Reapplication requirements and opportunities to use multiple treatment types on the same 

treatment are impossible to quantify at this scale. It is impossible to adequately consider how 

these variables would impact cost or how they might influence the number of treatable acres 

by each alternative. However, since it is assumed that reapplication requirements and 

opportunities to use multiple treatment types will be similar amongst the alternatives, this 

analysis adequately exposes each alternative’s relative ability to treat a certain number of 

acres. 

Standards in the action alternatives determine the suite of available treatment methods. Acres 

effectively treated change under each alternative when the budget is held constant. This is 

because costs vary by treatment method. Treatment costs per acre by method are based on 

costs reported by National Forests in Region six between 1997 and 2003, as well as estimates 

from other Regions. Manual treatment costs are $340 per acre for all alternatives except 

Alternative B. Costs are expected to be $400 per acre for manual treatments under 

Alternative B because areas that may be difficult to treat manually would be included, given 

its emphasis on non-chemical methods. The treatment cost per acre for all other nonherbicide treatment is constant across the alternatives. 

Available herbicides varied between alternatives. Choices of herbicides caused variation in 

treatment cost per acre and total acres treated between alternatives, though to a lesser degree 

than treatment method. Herbicide use ratios were estimated for each action alternative, No 

Action ratios are based on Region Six herbicide use from 1999 to 2002. 

No Action Average cost per acre is $25 based on: 

10% Glyphosate at $29.38/acre 

81% Picloram at $21.75/acre 

3% Triclopyr at $115.50/acre 

5% Dicamba at $17.35/acre 

Proposed Action Average cost per acre is $38 based on: 

25% Glyphosate at $29.38/acre 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

25% Clopyralid at $37.75/acre 

15 % Picloram at $21.75/acre 

10% Imazapic at $16.40/acre 

10% Sulfonyl mix at $26.40-$32.10/acre 

15% others at $24.06-$134.25/acre 

Alternative B Average cost per acre is $41 based on: 

40% Glyphosate at $29.38/acre 

40% Clopyralid at $37.75/acre 

10% Triclopyr at $115.50/acre 

10% Sethoxydim at $24.06/acre 

Alternative D Average cost per acre is $21 based on: 

40% 2,4-D at $7.48/acre 

20% Picloram at $21.75/acre 

10% Imazapic at $16.40/acre 

10% Sulfonyl mix at $26.40-$32.10/acre 

10% Glyphosate at $29.38/acre 

10% others at $17.35-$134.25/acre 

Average herbicide treatment costs per acre, by method, were then estimated for each 

alternative (Table 4-32). For all alternatives, ground application is estimated at $100 per acre 

in addition to herbicide costs, and aerial application is estimated at $25 per acre in addition to 

herbicide costs. 

Table 4-32 Average Per Acre Herbicide Treatment Costs by Alternative 

Method Current PA B D 

Herbicide cost + Ground application cost ($100) $125 $138 $141 $121 

Herbicide cost + Aerial application cost ($25) $50 $63 $66 $46 

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Holding the budget constant, differences in treatment costs per acre change the number of 

acres that can be treated each year. This affects the ability of the Forest Service to effectively 

control invasive plants. See Chapter 4.2. 

Table 4-33 displays the average annual acres treated and the percent of acres by treatment 

method under each alternative, given a constant annual budget of $4.8 million. Figure 4-1 

displays the average annual acres treated by alternative. 

Table 4-33 Treatment Acres by Alternative Holding Total Cost Constant at $4.8 MM 

No Action PA B D 

Method Acres % Acres % Acres % Acres % 

Herbicide- Ground 13,646 54% 15,401 53% 4,062 20% 29,957 74%

Herbicide- Aerial 0 0% 3,196 11% 1,015 5% 4,453 11%

Manual 8,610 34% 6,393 22% 9,342 46% 2,024 5%

Mechanical 770 3% 1,453 5% 2,031 10% 1,214 3%

Biological 996 4% 1,743 6% 2,031 10% 1,619 4%

Fire 382 2% 581 2% 812 4% 810 2%

Cultural 202 1% 291 1% 1,015 5% 405 1%

Total 24,606 100% 29,058 100% 20,310 100% 40,482 100%

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

NA PA B D

Cultural

Fire

Biological

Mechanical

Manual

HerbicideAerial 

HerbicideGround 

Figure 4-1 Acres Treated Annually by Type Holding Budget Constraint at $4.8 MM 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

4.6.3 Effects of Prevention Standards 

Prevention standards increase costs to National Forest users and change the requirements for 

land uses. The following summary describes the effects each prevention standard could have 

on land use activities and programs. 

Standard #1 applies to all action alternatives and calls for consideration of invasive plants in 

new planning and analysis. Its effect on land use programs and activities is not measurable. 

While consideration of invasive plants in planning documents already occurs to some degree, 

this standard facilitates application that is more consistent. Costs for planning management of 

timber, other vegetation, road, livestock grazing, fire, fuels, recreation, and minerals and 

mining programs and projects increase under this standard. Uses and outputs would tend to 

decline, but the extent is considered very limited and not measurable. The additional 

requirement in Alternative B to emphasize healthy forest maintenance and restoration could 

further increase costs or limit land uses. For all alternatives, flexibility in timing, location, or 

intensity of land use could be adjusted to minimize adverse effects to programs and uses. 

Standard #2 requires heavy equipment cleaning at varying levels based on the alternative. 

Implementation of this standard increases management costs for timber, other vegetation 

management, roads, livestock grazing, fire, fuels, recreation, and minerals and mining 

programs and projects. Currently, timber sale and road contracts contain equipment-washing 

clauses, but they are not universally applied. Other service contracts do not consistently 

contain these cleaning requirements. 

Alternative B includes the additional requirements for cleaning of all equipment and vehicles, 

as well as all heavy equipment, authorized to operate outside the road prism on National 

Forest System lands. Alternative B also requires that for actions conducted or authorized by 

the Forest Service in areas where invasive plants are present at a level where transport of 

invasive plant seed or vegetative propagules is likely and a concern, all equipment and 

vehicles that have operated outside the limits of the road prism will be cleaned before leaving 

the project site. 

Support vehicles that accompany heavy equipment would need to be washed more frequently, 

because they are generally used to access National Forest worksites on a daily basis. Heavy 

equipment is moved in and out far less often. Under Alternative B, this standard also results 

in increased initial costs to obtain or develop mobile washing stations. Until such stations are 

available, this standard in Alternative B may not be operationally feasible. 

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The costs of implementing this standard could lead to less heavy equipment work because 

costs may become prohibitive. Administrative costs for timber, other vegetation 

management, roads, livestock grazing, fire, fuels, recreation, and minerals and mining 

programs and projects in infested areas under Alternative B could increase to the point where 

programs and projects could not be funded. 

Standard #3 applies to all action alternatives and does not result in measurable cost increases. 

Most ground disturbing projects already have similar requirements for weed free straw and 

mulch in place. Weed free straw and mulch is preferred for projects in Region Six; this 

standard will facilitate consistency. This standard may need to be phased-in as programs to 

certify weed free straw and mulch become established. 

Standard #4 requires the use of certified weed free or pelletized feed with variations by 

alternative. For the Proposed Action, State, NAWMA, or similarly certified weed free or 

pelletized feed is required when used in Wilderness Areas or at Wilderness trailheads. 

Similar weed free feed standards already apply to about 2.5 million acres of National Forest 

system lands in the Region (mostly in Wilderness and other specially designated areas, see 

discussion of congressionally designated areas in Chapter 3). Weed free feed requirements 

can increase the cost of using pack stock because weed free feed is generally more expensive 

to purchase and distribution locations for weed free feed are limited, potentially resulting in 

additional purchase, travel and transportation costs to the user. The Proposed Action requires 

weed free feed on about 2.1 million additional acres when compared to No Action or 

Alternative D. Alternative B expands the weed free feed requirement to all 24.9 million acres 

of National Forest System lands in Region Six. 

Note regarding design of this standard: It is acknowledged in Chapter 3 (see Recreation and 

Recreation Management) that no formal state or NAWMA certification programs currently 

exist for Oregon or Washington. This limitation has not hindered weed free feed 

requirements from already being in place on about 2.5 million acres of National Forest 

System land in the Region or in keeping individual counties (Wallowa County, Oregon) and 

Forest Service Districts (Eagle Cap Ranger District, Wallowa-Whitman) from implementing 

such restrictions. Current weed free feed restrictions are in place to protect some of the 

unique characteristics for which these areas were designated. There has been expressed 

interest in creating weed free certification programs from farmers, livestock users, counties, 

and weed boards (see public comments). There has also been concern that Region Six is 

falling behind other western Forest Service Regions and States by not having more 

encompassing weed free feed requirements on National Forest System lands. Implementation 

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and enforcement of this standard may need to be phased-in as programs to certify weed free 

straw and mulch become established. 

The Forest Service acknowledges that enforcement of this standard will be difficult and 

partnerships and collaboration with livestock users and groups will be key in the programs 

success and in the protection of commonly valued resources. The alternatives represent an 

appropriate range, from weed free requirements on no additional acres in No Action and 

Alternative D, to such requirements for all National Forest System land in Alternative B. The 

Proposed Action takes a moderate approach by requiring weed free or pelletized feed at 

Wilderness trailheads and in Wilderness Areas; areas that currently have relatively low 

invasive plant infestation rates and have been designated as unique and worthy of added 

protections. 

Standard #5 applies solely to Alternative B. It requires that native vegetation and forest 

canopies be maintained within certain areas. This standard does not identify the specific areas 

where this may occur. Therefore, no estimates can be made about the extent of the impact. 

Vegetation management projects could cost more, or acres of accomplishment could be 

reduced. Fire and fuels management programs are affected by this standard, and in extreme 

cases, applying the standard results in less effective fuels treatments and increased risk for 

wildfire damage. Implementation of this standard potentially reduces the ability of the Forest 

Service to appropriately respond to changing fire condition classes and may conflict with 

achieving the goals of the Healthy Forests Restoration Act of 2003. 

Land managers may experience difficulty demonstrating they have complied with this 

standard if the public raises issues about where vegetation must be retained, how much 

vegetation must be retained, what vegetation must be retained, for how long vegetation must 

be retained, etc. This standard may become a point of litigation for projects, which would 

tend to increase costs or reduce the number of projects implemented. 

Standard # 6 applies to all action alternatives. Standard #6 adds a requirement to incorporate 

invasive plant prevention practices (such as those in the USDA Forest Service Guide to 

Noxious Weed Prevention Practices (Appendix E)) into annual operating instructions and 

when revising allotment management plans. Planning and implementation of these measures 

will occur in cooperation with the grazing permit holder. This standard elevates the 

importance of invasive plant prevention practices and will contribute to a more consistent and 

appropriate application of prevention practices in livestock management that best suit local 

allotment conditions, ecology, and desired future conditions. Requiring incorporation of 

invasive plant prevention practices in range management may result in some limitations on 

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livestock grazing, including changes in grazing locations, timing, intensity, and outputs. 

However, specific effects of this standard are currently unknowable as they are dependent on 

individual forest implementation of practices that are appropriate for local conditions. 

Standard #7 varies by alternative and requires inspection and treatment of gravel, fill, sand, 

quarries, and borrow material for invasive plants. It increases costs of mineral source 

development and use depending on the extent of invasive plants in a given site. All 

alternatives increase costs of rock source development. Inspecting rock source areas before 

use results in a slight increase in rock source management costs. Under Alternative B, this 

cost is highest due to the requirement to inspect source sites annually. Alternative B also have 

the requirement to strip and stockpile material before use. This requirement results in 

additional costs of over $300,000 annually for Regions Six. Additional costs of Alternative B 

are incurred because herbicides are not used to treat mineral sources, but instead they are 

treated mechanically. 

Standard #8 requires consultation with invasive plant specialists on road maintenance 

activities. While the language varies between the alternatives (see explanation in Chapter 2.2) 

the intent of the standard is the same for all action alternatives. This standard is designed to 

elevate the importance of considering invasive plants in planning for road maintenance 

activities, while allowing flexibility for roads maintenance planners and invasive plant 

specialists to coordinate and plan road maintenance activities that minimize contributions to 

(and that may help to avoid) the spread of invasive plants and that best suit local site 

conditions, ecology, and desired future conditions. It increases the cost of these projects, 

reducing accomplishment where budgets remain static. Region Six currently completes 

approximately 7,470 “lane miles” of road maintenance and 3,600 miles of ditch maintenance 

(information in specialist report). The additional work estimated to result from this standard 

in all alternatives is nearly a one percent increase in road maintenance costs. This is due to 

increased work force needs so that appropriate consultation occurs. Alternative B includes 

additional language highlighting particular practices, but does not change intent or effects of 

this standard as quantifiable at the Regional level. All alternatives are considered equally 

effective. 

Standard #9 applies solely to Alternative B. It calls for the closure or decommissioning of 

nonessential roads where invasive plant spread is of high risk. Given the wide distribution of 

invasive plants, the effect of this standard could be extensive. This standard results in more 

road closures than proposed under current management. As roads are closed or 

decommissioned, public access is decreased. People have expressed concern about the effects 

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of road closure, including: making recreation areas inaccessible or less accessible, restricting 

access to areas for people with disabilities, reducing dispersed recreation opportunities, 

reduced fire suppression access, and increased costs of land use and management. The extent 

of these effects depends on the number of roads closed due to this standard, which cannot be 

quantified at this regional scale. 

Standard #10 applies to the Proposed Action and Alternative B. It limits OHV use to a 

system of designated roads, trails, and areas. This standard results in a shift away from “open 

to OHV use unless marked as closed” policy, to a policy where areas are considered “closed 

to OHV use unless marked as open.” The Forest Service is currently working on a national 

policy regarding OHV use. Comment period for the proposed rule, 36 CFR Parts 212, 251, 

261, and 295 (Travel Management; Designated Routes and Areas for Motor Vehicle Use, see 

Appendix R), closed in September 2004, but a final rule release has not been announced. In 

summary, the policy would require the establishment of a system of roads, trails, and areas 

designated for motor vehicle use; and prohibit the use of motor vehicles off the designated 

system, as well as motor vehicle use on the system that is not consistent with the classes of 

vehicles and if applicable, the time of year, designated for use. Under the Proposed Action 

and Alternative B, Region Six would in directly implement the proposed rule as it is currently 

drafted. All action alternatives address OHV use in Objective 2.5, only Alternative D 

includes no additional standard for OHV use. Rather, Alternative D and No Action rely on 

potentially forthcoming national Forest Service Policy for OHV management. 

The effects of the prevention standards that are the basis for alternative comparison in Chapter 

2.6 include: increased cost of heavy equipment; increased cost or decreased access for pack 

stock users; adjustments to grazing permits; and reduced access due to motor vehicle use. 

These effects are discussed in detail in Chapters 4.6.4 through 4.6.7. 

4.6.4 Costs of Heavy Equipment Work 

Direct and Indirect Effects 

Standard #2 increases costs of heavy equipment work through vehicle cleaning requirements 

that are not currently universally applied. Forest Service specialists estimate that costs, for 

programs that use heavy equipment outside the road prism, will increase by about 2 percent. 

This is based on 2003 competitive sourcing road maintenance studies that found that the 

Region completes approximately $9.9 million dollars of road maintenance work annually. 

This budget equates to the work of approximately 193 pieces of heavy-equipment pieces 

working all year. These figures provide the baseline for comparison of the potential for 

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Standard #2 to increase costs of heavy equipment work. Cost increases will apply to Forest 

Service and contract use of heavy equipment, thus contract bid prices will increase. 

Information about analysis methodology in the Engineering Specialist Report is in the project 

analysis files. 

Under No Action, Standard #2 does not apply. Under The Proposed Action and Alternative 

D, vehicle washing requirements are estimated to cost about $215,000 for road maintenance 

equipment, approximately a 2 percent increase to current program costs. A similar 2 percent 

increase in heavy machinery operating costs is expected for all programs that operate heavy 

equipment outside the road prism, such as timber and vegetation management. 

Alternative B further increases heavy equipment cleaning costs by approximately $1,125,000 

annually. This equates approximately to an 11 percent increase to current program costs. A 

similar 11 percent increase in heavy machinery operating costs is expected for all programs 

that operate heavy equipment outside the road prism. Table 4-34 and Figure 4-2 display 

annual costs associated with the use of heavy equipment. 

Table 4-34 Cost of Heavy Equipment 

Annual Heavy 

Equipment Cost 

Approximate Increase 

in Cost 

Approximate Percent 

Increase 

No Action $9,900,000 0 0% 

Proposed Action $10,115,000 $215,000 2% 

Alternative B $11,025,000 $1,125,000 11% 

Alternative D $ 10,115,000 $215,000 2% 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

$8

$10

$12

Annual Heavy Equipment

Cost in Millions

No Action

Proposed

Action

Alternative B

Alternative D

Figure 4-2 Annual Heavy Equipment Costs (in Millions) 

Cumulative Effects 

No additional costs to heavy equipment use are foreseeable from other actions. The recent 

Port-Orford-cedar decision applied standards similar to the Proposed Action for some portions 

of the Region. The invasive plant standards are compatible with the Port-Orford-cedar 

standards. 

4.6.5 Weed Free Feed Requirements 

Direct and Indirect Effects 

Weed-free feed requirements increase the cost of using horses and other pack stock because 

weed-free feed can be more expensive to purchase, distribution locations for weed-free feed 

may be limited, and pack stock users may have to plan ahead to obtain the feed, or to allow 

time for animals to adjust to a different feed type. The measure of this effect is acres of 

National Forest where weed free feed requirements apply. 

Pack stock users may experience additional travel costs to comply with this standard. Some 

people may also decide not to use certain National Forest System lands if they do not wish to 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

comply with weed free requirements. Thus, some users and use impacts may be displaced to 

other federal, state, or private lands. 

Alternative B requires the use of weed-free feed on all 24.9 million acres of National Forest 

System lands in the Region. Refer to Table 4-35. This alternative requires weed free feed on 

5 times as many acres as the Proposed Action and 10 times more than No Action and 

Alternative D. Thus, Alternative B has the greatest effects to pack stock users. 

The Proposed Action requires use of weed-free feed in approximately 4.6 million acres of 

Wilderness Areas and at Wilderness Trailheads. This alternative requires weed-free feed on 

not quite twice (about 2.1 million additional acres) as much land than the No Action 

Alternative or Alternative D. Thus the Proposed Action is less costly to pack stock users than 

Alternative B but more costly than the other alternatives. 

The No Action Alternative and Alternative D do not include weed free feed requirements. 

However, about 2.5 million acres in Region Six already require weed free feed under current 

direction. This direction will not change as a result of potential decisions associated with this 

EIS. 

Table 4-35 Acres Where Weed Free Feed Would Be Required 

Alternative Acres Where Weed-Free Feed is Required 

No Action 2.5 million 

Proposed Action 4.6 million 

Alternative B 24.9 million 

Alternative D 2.5 million 

The more acres where weed-free feed is required, the more likely that animal users will 

experience cost increases or loss of options for access to National Forests. The precise 

measure of the impact is not known, and depends on the availability and cost of weed-free 

feed compared to current feed costs. This requirement is expected to be implementable over 

time, and may require some phase in time as a weed-free feed certification, distribution and 

use becomes more widespread. Many pack stock users already comply with weed-free feed 

requirements as a part of special use permits on National Forests. 

Cumulative Effects 

Weed free feed use is common but not required throughout Oregon and Washington. No 

additional restrictions on pack stock and other livestock users are foreseeable. Regardless of 

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choice of alternative, pack stock and other recreational use will to some degree continue to be 

a source of invasive plant spread (see Chapter 3 for more discussion on this mechanism of 

dispersal). 

4.6.6 Tendency for Standards to Affect Range Allotments and Permittees 

Direct and Indirect Effects 

All the action alternatives require incorporation of invasive plant prevention practices in 

annual operating instructions and allotment management plans. Since invasive plants are 

already considered to some degree in many grazing management plans, the effect of this 

standard is mainly Regional consistency. Alternative B takes this standard a step further by 

requiring specific documentation of how practices from the USDA Forest Service Guide to 

Noxious Weed Prevention Practices (Appendix E) are considered in plans. 

The effects on livestock grazing levels and permttees under all action alternatives could 

include, but are not limited to: 

• Changes in livestock movement patterns that require additional labor or may reduce 

outputs for certain allotments. 

• Alterations to season of use (length, turn-on, turn-off, etc.) and intensity of use that 

could reduce outputs. 

• Resting of pastures resulting in reduction of livestock use and output. 

• Active restoration of native plant communities, which requires allotment resting for 

one to two seasons and could reduce livestock use and output. In some cases fencing 

can be used to mitigate impacts. 

• Delayed reintroduction of livestock following wildfires resulting in reduce livestock 

use and outputs over time. 

Ultimately, invasive plant prevention practices may result in some reduction to livestock 

grazing, but prevention of invasive plants is only one consideration; multiple factors including 

range condition, stream protection, and endangered species management will also influence 

allotment management. 

An actual reduction in Animal Unit Month (AUMs) attributed to invasive plant management, 

cannot be quantified at the Regional scale due to unavailable data, variability between 

allotments, and the ongoing process of Allotment Management Plan revision. Alternative B 

with its additional documentation requirements may tend to improve the consistency of 

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prevention application across the Forests and thus may be more likely to result in limitations 

on livestock grazing, including changes in grazing locations, timing, intensity, and outputs. 

Effects on grazing and range management are displayed in Table 4-36. 

Cumulative Effects 

The authorized number of AUMs has been in a fairly static for the past decade, with slight 

decreases during drought years and as some small allotments are retired over the past 40-60 

years, the trees and forest canopy have been increasing subtly, resulting in a reduction of 

forage and a decrease in available AUM levels. Thus, factors other than invasive plant 

management would continue to influence grazing levels regardless of alternative selected in 

this EIS. Invasive Plant management and other land management practices may positively 

influence forage quantity or quality and result in beneficial impacts to grazing. 

Table 4-36 Effects on Grazing and Range Management 

Alternative Effects on Grazing and Range Management 

No Action No Direct Effects. 

Proposed Action Some limitations on livestock grazing, including changes in grazing locations, 

timing, intensity, and outputs are anticipated. However, these effects are not 

quantifiable at the Regional scale. 

Alternative B Alternative B would likely increase consistency of application across the 

Forests, but this difference is not quantifiable at the Regional scale 

Alternative D Same as Proposed Action 

4.6.7 Tendency for Standard to Affect Road and Off-Highway Vehicle 

Access 

Direct and Indirect Effects 

The Proposed Action and Alternative B include standards that will result in OHV closures. 

Alternative B also requires use of weed-free corrals and OHV staging areas and calls for the 

closure or decommissioning of nonessential roads where invasive plant spread is of high risk. 

Alternative D possess no corollary standards. 

Standards restricting public access decrease some forest user sense of freedom to use public 

lands as they see fit or as they have done in the past. Some forest users may also be troubled 

by limited access to structures (roads) that already exist and are easily seen. These standards 

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also increase costs to forest users, by limiting access locations or by changing use patterns 

thus adding to user transportation costs. 

The actual results of implementing Standards #9 and Standard #10 are unknown and cannot 

be predicted due to the complexity of the factors as discussed in Chapter 3 and earlier in 

Chapter 4. Alternative B tends to results in more road closures than the other alternatives. 

Additional analysis and decision processes would be required before land use changes would 

become effective on any National Forest in the Region. 

Cumulative Effects 

Currently, OHV management is a priority issue within the Forest Service, and along with 

invasive plants, is included in the top four threats facing National Forest lands. National 

OHV policy, currently being drafted, would limit OHV use to designated roads, trails and 

areas, and have effects similar to the Proposed Action and Alternative B. There may be no 

differences between alternatives once this national policy is adopted and in place. 

OHV use outside of National Forest System lands would not be affected by the national 

policy. Invasive plant management or other factors may lead to reductions in public access 

throughout the states. The amount of access reduction triggered by this EIS is likely to be 

small compared to access reduced as a result of the national policy and other factors. 

Table 4-37 Effects of Road and OHV Use Closures 

Alternative Effects on Road and OHV use Closures 

No Direct Effect. New restrictions on OHV use may occur from new national 

policy. No Action 

No new road closures expected from invasive plant prevention standards. OHV 

use allowed only on specifically designated roads, trails, and areas, based on 

implementation of draft national policy. 

Proposed Action 

Tendency for more roads to be closed or decommissioned due to wording of 

standards. OHV use allowed only on specifically designated roads, trails, and 

areas, based on implementation of draft national policy. 

Alternative B 

Alternative D Same as No Action. 

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4.6.8 Alternative Comparison 

Table 4-38 compares the alternatives by the measuring factors. 

Table 4-38 Summary of Effects by Measuring Factors 

No Action Proposed Action Alternative B Alternative D 

Annual acres of 

treatment for each 

alternative as an 

indicator of relative 

costs 

24,606 29,058 20,310 40,482 

Estimated 

percentage increase 

in cost of heavy 

equipment work 

0% 2% 11% 2% 

Tendency for 

standards to result 

in road closures 

and loss of offhighway vehicle 

access 

No Direct Effect. 

New restrictions 

on OHV use may 

occur from new 

national policy. 

No new road closures 

expected from invasive 

plant prevention 

standards. OHV use 

allowed only on 

specifically designated 

roads, trails, and areas, 

based on implementation 

of draft national policy. 

Tendency for more roads 

to be closed or 

decommissioned due to 

wording of standards. 

OHV use allowed only on 

specifically designated 

roads, trails, and areas, 

based on implementation 

of draft national policy. 

Same as No 

Action. 

Tendency for 

standards to affect 

grazing locations, 

timing, intensity 

and outputs 

Reduces grazing 

levels, due to 

rangeland 

grazing 

capacities being 

diminished by 

invasive plants. 

Reduces grazing levels, 

due to more consistent 

applications of 

prevention measures. 

Highest tendency to 

reduce grazing levels, due 

to more rigid and 

consistent application of 

prevention measures. 

Same as 

Proposed 

Action 

Acres of National 

Forest where weed 

free feed would be 

required 

2.5 million 4.6 million 24.9 million 2.5 million 

4.7 Other Issues 

4.7.1 Soil Productivity 

Introduction 

Herbicides have the potential to affect soil and soil organisms, including mycorrhizal fungi. 

Soil organisms perform important roles supporting plant growth and thus are fundamental to 

soil productivity. Some organisms convert nutrients to a usable form, some create soil 

structure and allow water and air to reach plant roots, while others interact with specific 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

species and are necessary for survival of some plants. Regional soil productivity protection 

standards were originally implemented in 1976 and have been revised several times since. 

The risk assessments (SERA, 1999, 2001, and 2003) included information about potential 

effects to soil organisms when it was available, which confirmed the relevance of the issue to 

this analysis. 

All alternatives, including the No Action alternative, allow the use of herbicides in treatment 

of invasive plants. Transient effects to soil microorganisms from use of herbicides. Soil 

texture, organic matter content, and soil moisture level, among others factors, influence the 

persistence of herbicide and longevity of the effects. Successful restoration of native 

vegetation to areas infested with invasive plants is dependent, in part, on healthy soil 

organisms. Negative effects to soil organisms and soil productivity can complicate restoration 

and could delay restoration of native vegetation for a year or more. Successful restoration of 

native vegetation to areas infested with invasive plants is dependent, in part, on healthy soil 

organisms. Negative effects to soil organisms and soil productivity can complicate restoration 

and could delay restoration of native vegetation for a year or more. 

Picloram and sulfometuron methyl are of particular concern, due to their toxicity to soil 

microorganisms and persistence in the soil. Picloram is toxic to some soil organisms, even at 

low levels, based on increasing persistence with increasing application rates. Picloram is 

most toxic in acidic soil. Picloram has a typical half-life of 90 days, meaning that one-half of 

the amount applied remains in the soil after 90 days, one-fourth of the applied amount 

remains after 180 days, one-eighth after 270 days, and so on. Because picloram is toxic to 

microorganisms at low levels, toxic effects can last for some time after application. Field 

studies (Brooks et al., 1995; Nolte and Fulbright, 1997) have not noted substantial adverse 

effects associated with the normal application of picloram, that might be expected if soil 

microbial activity were substantially damaged (SERA, 2003-picloram). Picloram, applied at 

typical rates, may change microbial metabolism, however, detectable effects to soil 

productivity are not expected. Persistence in soils could affect soil microorganisms by 

decreasing nitrification. Long-term effects to soil microorganisms are unknown (ibid.). 

Similarly, sulfometuron methyl is toxic to soil microorganisms. Microbial inhibition is likely 

to occur at typical application rates and could be substantial. The typical half-life for 

sulfometuron methyl varies from 10 to 100 days, depending on soil texture. Soil residues may 

alter composition of soil microorganisms. Sulfometuron methyl applied to vegetation at rates 

that control undesirable vegetation would probably be accompanied by secondary changes in 

the local environment affecting the soil microbial community to a greater extent or at least 

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more certainly than any direct toxic action by sulfometuron methyl on the microorganisms 

(SERA, 2003-sulfometuron). Changes to mychorrhizal fungi from sulfometuron methyl can 

affect the productivity of native plant communities. 

Sulfometuron methyl applied to vegetation at typical application rates will probably be 

accompanied by secondary changes to vegetation that affect the soil microbial community 

more certainly than direct toxic action of sulfometuron methyl on soil microorganisms 

(SERA, 2003-sulfometuron methyl). Arthur and Wang (1999) found that a formulation of 

sulfometuron methyl had a negative impact on the abundance of microorganisms and 

decreased soil nitrogen content on a Christmas tree farm. 

Direct and Indirect Effects 

Table 4-39 displays annual acreage of herbicide use on National Forest System lands in 

Region Six, predicted for picloram and sulfometuron methyl, along with other herbicide use 

for each alternative. The acreage estimates are based on current herbicide use on and off 

National Forest System lands, given static budget and the standards under each alternative. 

The effects of using picloram and/or sulfometuron methyl in the No Action, Proposed Action, 

and Alternative B and Alternative D are not expected to be significant, particularly at this 

Regional scale. All action alternatives include a standard requiring a long-term strategy for 

restoring infestations of invasive plants, which necessarily includes protecting, or improving 

soil productivity and conditions for soil microorganisms (Standard #12). Adherence to this 

standard is expected to effectively reduce risk of significant adverse effects to soils. 

Table 4-39 Predicted Annual Acreage of Herbicide use - NFS lands, Region Six 

Total Annual 

Acreage – All 

Herbicides 

Annual Acreage 

Picloram 

Annual Acreage 

Sulfometuron 

Methyl 

Annual Acreage 

Other Herbicides 

No Action 11,000 0 2,600 13,600 

Proposed Action 3,000 600 15,200 18,800 

Alternative B 0 0 5,100 5,100 

Alternative D 6,900 1,100 26,400 34,400 

Cumulative Effects 

Both picloram and sulfometuron methyl are relatively water soluble and could move off-site 

in water. These herbicides are moderately adsorbed to soil particles and could be moved off4-111
Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

site with wind or mass soil movement. It is possible these herbicides could be introduced to 

National Forest System lands from other sources, though it is more likely that they would 

move off National Forest System lands to other ownerships. Nation-wide, Forest Service use 

of picloram is less than one percent of agricultural use (SERA, 2003-picloram), while Forest 

Service use of sulfometuron methyl nationwide is less than one percent of all use in California 

(SERA, 2003-sulfometuron methyl). Agricultural use of herbicides does not likely influence 

soils on National Forest System lands. 

Many other natural (i.e., wildland fire) and human influences (land development and use) may 

result in adverse effects on soils and soil productivity. The potential adverse effects to soils 

from these alternatives are small in comparison to the potential effects of invasive plants 

themselves (see Chapter 3) and other influences. In the long run, restoration of healthy native 

plant communities envisioned under all alternatives in this EIS will have beneficial impacts 

on soils. 

Unknown Information and Approach to Uncertainty 

What information is missing? 

Information about specific herbicide effects to each of the myriad of soil organisms is not 

available. Much of the research is based on indirect effects such as changes in persistence or 

metabolism of nutrients. The observed changes may mean a temporary depression in the 

activity of existing soil organisms, or could signal a complete change in the organisms 

present. 

Is this relevant to reasonably foreseeable significant adverse impact 

essential to a reasoned choice among alternatives? 

Soil organisms are important to the human environment because they can affect soil 

productivity, and none of the herbicides under consideration has notable effects to soil 

productivity. Hence, the unavailable information is insignificant in terms of providing a clear 

basis for choice between alternatives. 

The analysis file contains the soil scientist specialist report. Individual risk assessments 

contain more details about the toxicity of individual herbicides to soil organisms, information 

about studies considered in the risk assessment, modeling of individual herbicide movement, 

and specific information about herbicide properties such as persistence, adsorption to soil, and 

solubility in water. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

4.7.2 Aquatic Organisms 

Introduction 

All alternatives (including No Action) allow herbicide use near streams and other water 

bodies. During scoping, the public expressed concern that herbicide use, especially in 

riparian areas, could contaminate water and harm fish and other aquatic species. Concerns 

about sub-lethal53 effects to fish from herbicides were also expressed. The Fisheries 

Biological Assessments (BAs) and Appendix J, Effects of Non-Herbicide Methods of 

Invasive Plant Treatments on Wildlife, Fish and Plants, address the effects of non-herbicide 

treatment on aquatic organism and their habitat. 

Treatment of aquatic invasive plants (invasive plants that are submerged in or float on water) 

is outside the scope of this analysis. 

Below is a discussion of how aquatic organisms are likely to be exposed to herbicides as a 

result of future invasive plant treatments, followed by discussions of potential direct, indirect, 

and cumulative effects on the aquatic community. No treatments are authorized to be 

implemented by this EIS; each site-specific project must conclude appropriate NEPA and 

Endangered Species Act consultation before implementation. 

Likelihood of Exposure to Herbicides 

Herbicides used to control terrestrial invasive plants can enter water through atmospheric 

deposition (from large scale agriculture operations), spray drift, surface water runoff, 

percolation, groundwater contamination, and direct application. These routes may result in 

indirect effects to aquatic organisms and their habitat. Standards #18 through #22 in all action 

alternatives are designed to minimize or avoid water contamination from herbicides. These 

standards include: herbicides and herbicide mixtures; application methods and timing of 

application; and project design/mitigations, including treatment buffers. 

The likelihood of herbicides entering the water depends on the type of treatment and mode of 

transport, which are described below. 

Water Contamination from Drift. Herbicide drift is one of the mechanisms of herbicide 

movement when applied as a spray. Drift or off-target movement can result in unintended 

injury to native plant species, contamination of surface waters, and contamination of 

 

53 Sub-lethal effects are those that may lead to harmful, but non-lethal effects that may impact the ability of fish 

and wildlife species to maintain normal populations. Examples include changes in behavior that make the fish 

more vulnerable to predation or illness, and hormonal effects that change reproductive success. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

ecologically sensitive areas. Drift occurs when fine droplets of liquid herbicide become 

windborne and are transported to adjacent areas. It is a physical process that depends on 

droplet size and weather conditions rather than specific properties of an herbicide. The 

herbicide droplets can be subsequently deposited on surface waters that either contain aquatic 

species or serve as runoff conduits to water containing aquatic species. Risk assessments 

made for this EIS modeled off-site drift using AgDRIFT (Teske et al., 2001). Further details 

of AGDRIFT are available at www.agdrift.com . 

Drift associated with backpack (directed foliar applications) is likely to be low although 

studies quantitatively assessing drift after backpack applications have not been encountered. 

Application pressure, nozzle size, nozzle type, spray angle, and spray volume are all factors in 

determining droplet size. The risk of direct effects from herbicide treatment is expected to be 

limited to off-site drift from spray applications (aerial, boom, and backpack). Standards #20 

through #22 in all of the alternatives will reduce the risk of surface water contamination from 

spray drift. 

In certain situations, contamination of sensitive areas, wetlands and open waters may occur 

during aerial spraying. Three herbicides included in the Proposed Action and Alternative D 

(chlorsulfuron, metsulfuron methyl, and sulfometuron methyl) are of particular concern 

because of the higher potential for impacts to non-target vegetation. Standard #16 in the 

Proposed Action prohibits aerial application of these herbicides:. Alternative B does not 

allow the use of chlorsulfuron, metsulfuron methyl, and sulfometuron methyl at all. In 

addition, the use of triclopyr is limited to selective application techniques only (e.g., spot 

spraying, wiping, basal bark, cut stump, injection) under both the Proposed Action and 

Alternative B. These restrictions under the Proposed Action and Alternative B will decrease 

the likelihood of any contamination of sensitive aquatic areas. The likelihood of 

contaminating sensitive areas is greater under Alternatives D because aerial application of the 

above three mentioned herbicides, and the possibility of broadcast application triclopyr. 

Water Contamination from Runoff, Leaching, and Percolation. All herbicides can potentially 

enter streams and other water bodies through water transported by runoff, leaching, or 

percolation. Water contamination from rain events could transport chemicals to waterways, 

and convey them to aquatic species habitat. Soil type and chemical stability, solubility, and 

toxicity can determine the extent to which an herbicide will migrate and impact surface waters 

and groundwater. For example, picloram is highly soluble and readily leaches through sandy 

soil. It is also resistant to biotic and abiotic degradation processes. It can also move from 

target plants, through roots, down into the soil, and into nearby non-target plants. Given this 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

capability, Standard 19 under all of the action alternatives helps protect riparian vegetation 

when using picloram by recommending treatment buffers. Glyphosate and 2,4-D, though 

very soluble, bind well with organic matter in soils and are not easily leached. All of the 

herbicides proposed for use under all of the alternatives are susceptible to transport in surface 

runoff, especially if applications are followed immediately by high rainfall events. 

Table 4-40 below shows the likelihood of herbicide exposure based on differences within 

each alternative under Standard #16. Key differences between the alternatives are the number 

and type of herbicides proposed, and limitations of application methods. 

Table 4-40 Factors for Determining Herbicide Exposure to Aquatic Organisms. 

Factors No Action Proposed Action Alternative B Alternative D 

12 Active 

Ingredients: 2,4-D, 

chlorsulfuron, 

clopyralid, dicambia, 

glyphosate, imazapic, 

imazapyr, metsulfuron 

methyl, picloram, 

sethoxydim, 

sulfometuron methyl, 

and triclopyr 

Number of 

Herbicides 

Proposed 

5 active ingredients

are permitted (except 

on the Malheur NF): 

glyphosate, picloram, 

triclopyr, dicamba, and 

2,4-D. 

10 Active Ingredients:

chlorsulfuron, clopyralid, 

glyphosate, imazapic, 

imazapyr, metsulfuron 

methyl, picloram, 

sethoxydim, 

sulfometuron methyl, 

and triclopyr. 

4 Active 

Ingredients:

clopyralid, 

glyphosate, 

sethoxydim, and 

triclopyr. 

Same as No Action 

Application 

Methods 

All application 

methods consistent 

with label 

requirements are 

permitted. 

All application methods 

consistent with label 

requirements are 

permitted. Chlorsulfuron, 

metsulfuron methyl, and 

sulfometuron methyl will 

not be applied aerially. 

Use of triclopyr limited 

to selective application 

techniques. 

All application 

methods 

consistent with 

label 

requirements 

are permitted. 

Use of triclopyr 

limited to 

selective 

application 

techniques 

Likelihood of 

Exposure to 

Herbicides 

Likely – No specific 

restrictions on 

herbicide use, but 

fewer choices of 

herbicides. Anticipate 

some risk of exposure 

depending on the 

choice of herbicides 

and application 

method 

Likely – less risk of 

exposure because of 

restrictions on the use of 

chlorsulfuron, 

metsulfuron methyl, 

sulfometuron methyl, 

and triclopyr 

Less likely – 

less risk of 

exposure 

because of less 

herbicide use 

overall, the 

absence of 

chlorsulfuron, 

metsulfuron 

methyl, 

sulfometuron 

methyl, and use 

restrictions on 

triclopyr 

Most likely – higher 

potential for exposure, 

particularly from the 

aerial application of 

chlorsulfuron, 

metsulfuron methyl, 

sulfometuron methyl 

and broadcast 

application of 

triclopyr. 

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Exposure to herbicides is plausible for aquatic organisms under each alternative. Alternative 

D poses the highest likelihood of exposing aquatic organisms to herbicides, and Alternative B 

has the lowest likelihood of exposure. Actual effects will vary depending on site-specific 

conditions and the design of the site-specific project. Appropriate project design and 

application of Standards 18-22 will minimize or avoid exposure of aquatic organisms to 

herbicides under all the action alternatives. 

Effects on the Aquatic Community 

The aquatic community consists of macrophytes (large aquatic plants) and phytoplankton 

(free floating algae), macroinvertebrates (aquatic insects and clams), fish, birds, and mammals 

(such as muskrats and otters). All of these organisms are interrelated in the aquatic 

community through the food chain. Organisms that play a role in the aquatic community 

require a certain set of physical and chemical conditions to exist, such as nutrient 

requirements, oxygen, light, and space. For purposes of this analysis, discussions will focus 

on fish, aquatic invertebrates, algae, and aquatic plants. 

Aquatic food chains are dependent on primary production as a source of energy within the 

ecosystem. For aquatic systems, primary production can occur in the water or out of the 

water in riparian areas. Numerous invertebrate species feed directly on primary producers 

through feeding functions such as grazing, scraping, shredding, and collecting. Other 

invertebrate and fish species feed on these invertebrates, which then become food for fish or 

other predators. For example, the Bliss Rapids snail (federally listed species) is known to 

graze on microscopic organisms found on the upper most surfaces of rocks. Any impact to 

the growth or availability of these organisms could ultimately impact the Bliss Rapids snail. 

Herbicides may be toxic to aquatic plants and invertebrates, thus indirectly affecting fish by 

reducing primary production or the trophic structure of invertebrate communities. Low 

concentrations of herbicides can affect benthic algae communities (NOAA, 2002). The 

variation in toxicity to aquatic organisms between different formulations for the same 

herbicide can be substantial (SERA, 2003-glyphosate). In addition, timing of application can 

result in different effects. For example, a springtime application of glyphosate, at 

recommended rates, in a lake ecosystem, where dissolved oxygen levels are low or water 

temperatures are elevated, could be hazardous to young of the year fish (Folmar et al., 1979). 

Forest Service/SERA Risk Assessments modeled exposures for each herbicide considered 

under all of the alternatives (SERA, 1998; 2001; 2003; 2004). These risk assessments model 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

the amount of chemical that can reach water under several different scenarios, then compares 

results to existing monitoring data to check the accuracy of the model. Both acute and 

chronic exposures to representatives of the aquatic community were evaluated. Acute 

exposures are short-term while chronic exposures occur over time. These exposure scenarios 

include herbicide entering water through erosion, run off and/or drift. Table 4-41 summarizes 

the results of the exposure scenarios for application at the typical and highest allowable 

application rate. Refer to previous table for type of herbicide included under each alternative. 

Table 4-41 Forest Service SERA Exposure Results for Sensitive Aquatic Organisms Chlorsulfuron Clopyralid Dicamba Glyphosate Imazapic Imazapyr Metsulfuron Methyl Picloram Sethoxydim Sulfometron Methyl Triclopyr 2,4-D 

ACUTE EXPOSURES – short term 

Fish -- -- -- ♦ -- -- -- -- -- -- -- -- 

Aquatic 

invertebrates 

-- -- -- -- -- -- -- -- -- -- -- -- 

Algae ♦ -- ♦ -- -- -- -- ♦ -- 

Aquatic plants * -- -- -- ♦ * * ♦ -- * * * 

CHRONIC EXPOSURES – over time 

Fish -- -- -- -- -- -- -- -- -- -- -- -- 

Aquatic 

invertebrates 

-- -- -- -- -- -- -- -- -- -- -- -- 

Algae -- -- -- -- -- -- -- -- -- -- -- -- 

Aquatic plants -- -- -- -- -- -- -- -- -- -- -- -- 

‘—’ Predicted concentrations less than the estimated or measured ‘no observable effect concentration’ 

(NOEC) 

‘*‘ Predicted concentrations greater than the estimated or measured ‘no observable effect concentration’ at 

typical application rates. 

‘♦’ Predicted concentrations greater than the estimated or measured ‘no observable effect concentration at 

highest allowed application rates only. 

Proposed Action. Under the Proposed Action, acute exposures of clopyralid and sethoxydim 

are less than the estimated or measured NOEC for all representatives of the aquatic 

community. Herbicides that result in predicted concentrations greater than the estimated or 

measured NOEC at the highest allowable application rate only are: glyphosate for fish, 

chlorsulfuron and sulfometron methyl for algae, and imazapic and picloram for aquatic plants. 

At typical application rates chlorsulfuron, imazapyr, metsulfuron methyl, sulfometron methyl, 

and triclopyr predicted concentrations are greater than the estimated or measured NOEC for 

aquatic plants only. The majority of herbicides under the Proposed Action may impact 

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aquatic plants. However, these impacts would be indirect because this EIS does not include 

the treatment of floating or submerged aquatic plants. None of the herbicides included under 

the Proposed Action exceeded the NOEC for aquatic invertebrates tested. Chronic exposures 

for all herbicides did not exceed the NOEC for any of the representatives of the aquatic 

community. 

Alternative B. Under Alternative B, acute exposures of clopyralid and sethoxydim are less 

than the estimated or measured NOEC for all representatives of the aquatic community. 

Glyphosate is the only herbicide that results in predicted concentrations greater than the 

estimated or measured NOEC at the highest allowable application rate only for fish. 

Triclopyr results in predicted concentrations greater than the estimated or measured NOEC at 

typical application rates for aquatic plants only. None of the herbicides exceeded the NOEC 

for aquatic invertebrates tested. Chronic exposures for all herbicides did not exceed the 

NOEC for any of the representatives of the aquatic community. 

Alternative D. In addition to the results for all herbicides mentioned in the Proposed Action 

and Alternative B, dicamba results in predicted concentrations greater than the estimated or 

measured NOEC at the highest allowable application rate only for algae. For aquatic plants, 

2,4-D results in predicted concentrations greater than the estimated or measured NOEC at 

typical application rates for aquatic plants only. None of the herbicides exceeded the NOEC 

for aquatic invertebrates tested. Chronic exposures for all herbicides did not exceed the 

NOEC for any of the representatives of the aquatic community. 

No Action. No Action includes the use of five herbicides - glyphosate, triclopyr, dicamba, 

picloram and 2,4-D (a tool of last resort). Results of their continued use would be similar to 

what was identified for each herbicide under the above alternatives. None of the herbicides 

exceeded the NOEC for aquatic invertebrates tested. Chronic exposures for all herbicides did 

not exceed the NOEC for any of the representatives of the aquatic community. 

While the alternatives vary in terms of numbers of herbicides available for use, all alternatives 

result in potential effects to aquatic organisms. However, acute exposures to aquatic 

organism are not likely to result in harm under foreseeable conditions. 

The treatment/restoration standards in all action alternatives are designed to minimize sitespecific effects from herbicides to aquatic organisms and other non-target species. All action 

alternatives include Standard #15 to ensure herbicide applicators are licensed and herbicide 

transportation and handling plans are in place prior to treatment. Standard #18 requires risk 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

assessment of herbicide formulation additives. Standard #19 requires the use of site-specific 

information to choose herbicide formulations, buffers, application methods, and timing. 

Direct Effects 

Application of herbicides under the Proposed Action, Alternative B, Alternative D, and No 

Action are not expected to result in mortality to aquatic species other than algae and aquatic 

vascular plants. While the amount of herbicides or chemicals expected to reach water are 

expected to be very low under the Proposed Action and Alternative B, the Forest Service 

cannot conclude with certainty that the levels of chemicals that could potentially reach 

streams with aquatic organisms will be zero. 

Aquatic Plants and Algae. Toxic levels for algae and vascular plants may be of concern 

because they form a food supply, habitat, or both for aquatic organisms. Aquatic plants are a 

natural, and important, component of aquatic communities. Aquatic plants, especially 

phytoplankton, are consumed by small invertebrate animals, which are in turn consumed by 

larger animals such as birds or fish. Phytoplankton can also be consumed directly by certain 

fish. Small fish can be consumed by larger fish and by birds. Any impact to a component of 

the aquatic community may have a ripple effect on the food web. 

Based on the risk assessments used for this EIS, typical application rates of chlorsulfuron, 

imazapyr, metsulfuron methyl, sulfometron methyl, triclopyr, and 2,4-D result in exposures 

that exceed the NOEC for aquatic plants. Whereas only the highest allowed application rates 

for imazapic and picloram result in acute exposure to aquatic plants. Using appropriate 

application rates, timing and application techniques of herbicides can have minimal impact on 

aquatic plant populations. Effects can be avoided through adherence to Standards #16, #18, 

#19, and #20. 

Fish and Invertebrates. Most direct effects from all of the alternatives on aquatic fish and 

invertebrates are likely to be from sub-lethal herbicide effects, rather than from direct 

mortality as a result of herbicide exposure. This is discussed further in Chapter 4.7.3. 

It is unlikely that the use of herbicides proposed in this EIS would cause fish kills at the 

concentrations of the active ingredients likely to occur in water. Mortality to fish is not 

expected, or likely from operational use because dilution, degradation, adsorption and other 

factors reduce the amount of herbicide that could enter a water body. In rare circumstances, 

high concentrations of herbicides could wash into streams from rainfalls shortly after 

herbicide application along road ditches or other surfaces that rapidly generate overland 

flows, or as a result of an accidental spill. In such instances, localized fish kills are plausible 

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in small tributary streams or small, enclosed water bodies where contaminated flows would 

not be readily diluted. 

Indirect Effects 

Identified inert ingredients and adjuvants found in herbicide formulations include some 

relatively innocuous substances, such as distilled water. Ingredients found in herbicide 

formulations could also include toxic substances, such as kerosene and naphthalene. Risk 

assessments discuss the effects of inert ingredients to aquatic biota. Inert ingredients found in 

herbicide formulations are known to and classified by the US EPA and the risk assessors 

(SERA, 2003, Risk Assessments). Effects of inert ingredients are included in risk assessment 

of specific formulations. 

Effects of surfactants to aquatic species have received some study. In general, aquatic species 

are more susceptible to adverse effects from surfactants than terrestrial species. At least some 

of the aquatic sensitivity to surfactants is due to irritation of gill membranes and alteration of 

their permeability and molecular exchange properties. Concern has been expressed about the 

potential for surfactants increasing the movement of other harmful materials, such as 

pesticides, into soils. Herbicide mobility can be increased by the use of surfactants, but effects 

to mobility are unlikely due to the relatively low concentration of surfactants in the soil/water 

matrix at Forest Service application rates (Bakke, 2003). Forest Service use of surfactants is 

not likely to reach levels of concern for estrogenic effects to fish (Bakke, 2003). 

Nonylphenol polyethoxylate-based (NPE) surfactants are commonly used as an additive in 

Forest Service herbicide applications. A separate risk assessment (Bakke, 2003) for NPE 

surfactants was completed because concerns have been expressed about the acute toxicity to 

aquatic organisms of the chemical components and breakdown products of NPE surfactants. 

Most studies of herbicide effects on fish observe the effect of short-period exposure to high 

concentrations of herbicides, rather than the low concentrations over an extended period more 

likely to be found in forest streams, lakes and ponds. Therefore, direct effects to fish would 

not be readily apparent. The potential for an accidental spill or improper use of herbicides 

may result in the contamination of water, thereby adversely affecting fish and invertebrates. 

The combination of POEA surfactant and glyphosate may be harmful to fish other 

invertebrates because they breathe by movement of water, The combination of POEA 

surfactant and glyphosate has been shown to cause inflammation of gill tissue in fish, and to 

reduce survival rates especially for young fish (Folmar et al, 1979; Servizi, 1987). Folmare 

demonstrated that the surfactant POEA is actually more toxic to fish than the herbicide it is 

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mixed with (Folmar, 1979). This agrees with the conclusion in the SERA Risk Assessment 

for glyphosate (SERA, 2003). One formulation of glyphosate (with POEA surfactants) 

resulted in observable, sub-lethal effects to fish at maximum label doses. Formulations of 

glyphosate that do not contain POEA surfactants are available and labeled for aquatic use, and 

may be used near water as needed under all alternatives. Thus, the risks associated with 

glyphosate will depend largely on formulations applied in the vicinity of streams, and 

application rates and methods specified for site-specific projects. 

The Garlon IV formulation of triclopyr contains either kerosene or diesel fuel, both of which 

are know to be toxic to fish. Analysis conducted for site-specific projects should provide a 

greater understanding of the true risks associated with triclopyr under the Proposed Action. 

Improper application of herbicides may cause changes in the quality of water in and near 

sprayed areas. After herbicide applications, nutrients are lost from soil into water at a greater 

rate. Acting as fertilizers, these nutrients encourage growth of algae, which decrease the 

oxygen content of the water. Air, soil and runoff temperatures may increase due to significant 

losses of ground cover in significantly large sprayed areas. The decrease in dissolved oxygen 

in the water, along with an increase in temperature affects the survival of cold water fish 

species. Herbicides like imazapyr at concentrations greater than NOEC are stable in 

conditions at the bottom of ponds, and will continue to kill aquatic plants growing there until 

degradation of the herbicide occurs. The decomposition of plants compromises water quality, 

alters pH, and changes habitat conditions for all aquatic species. It is unlikely that this would 

occur as a result of this EIS because imazapyr is not labeled for use in riparian areas. 

As noted previously, risk assessments indicate that a formulation of glyphosate resulted in 

predicted concentrations greater than the estimated or measured NOEC for fish at highest 

allowed application rates. The use of glyphosate is included in all alternatives. Aquatic 

plants are more susceptible to herbicides than fish, thus effects on the aquatic food web may 

occur. 

Indirect effects on aquatic organisms depend on the timing of application and amount and 

type of herbicides, inerts, metabolites, and/or adjuvants that reach aquatic habitats. Where 

herbicides are applied at recommended rates, the toxic effects to aquatic life may be 

insignificant and non-measurable. 

Aquatic Plants and Algae. Herbicides used in riparian areas for weed management may 

indirectly impact aquatic vegetation and phytoplankton. Emergent aquatic vegetation 

provides hiding cover or refuge for aquatic organisms. Herbicides leaching into surface water 

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can result in indirect effects to aquatic species via adverse effects to phytoplankton, algae, 

rooted aquatic macrophytes, and other aquatic plants. A significant reduction of primary 

productivity or aquatic plants and algae could decrease oxygen levels and indirectly impact 

other aquatic organisms and their habitat. 

When significant amounts of aquatic vegetation are killed the plant nutrients, nitrogen and 

phosphorus, which are often limiting to phytoplankton growth, can be released into the water. 

These nutrients can allow excessive phytoplankton growth, called blooms, that cause the 

water to take on a green coloration and water clarity is decreased. Blooms such as this, can 

also occur naturally, are sometimes considered undesirable but are temporary. Substantial 

mortality to aquatic vegetation is not expected, or likely from operational use because 

dilution, degradation, adsorption and other factors reduce the amount of herbicide that could 

enter a water body. 

Fish and Invertebrates. The most common reason for fish-kills due to herbicide application is 

the indirect effect of lowered dissolved oxygen (DO) in the water. Fish populations can 

withstand the everyday fluctuations of DO but many types of fish cannot tolerate prolonged 

periods of low DO. Natural fish-kills can occur in highly productive waters when 

phytoplankton populations die and cease producing oxygen after prolonged cloudy warm 

weather. When large amounts of aquatic plants are killed by an herbicide application the 

decaying vegetation and lack of oxygen production may cause DO to become so low that fish 

cannot survive in the water and a fish-kill occurs. If an herbicide that is effective on higher 

plants and not phytoplankton is used the potential for a fish-kill can be minimized because 

phytoplankton will continue to produce oxygen. Also, the likelihood of fish-kills is less in 

cooler water because it can hold more oxygen than warm water. It is very unlikely that 

implementation of projects under all of the alternatives result in fish-kills. Fish have 

avoidance mechanisms and are mobile allowing them to move to other parts of a lake or 

stream in order to avoid adverse conditions. However, under certain circumstances such as an 

accidental spill in an enclosed water body, fish-kills could occur. The likelihood of a fish-kill 

happening as a result of any alternative in this EIS is extremely low given the proposed 

standards and the exclusion of treatment for floating or submerged invasive plants. 

Cumulative Effects 

National Forests occupy large percentages of headwater watersheds in the region. Most, but 

not all, National Forest lands in Region Six are upstream of other sources of herbicides. 

Water flowing off National Forest System lands in the region often flow into larger stream 

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networks with mixed ownership. Poorly-maintained dirt roads and ditches on National Forest 

System lands can route sediments, nutrients, and herbicides directly into surface waters. 

Thus, roads and ditches have replaced headwater streams but rather than filter and process 

pollutants, they deliver them directly to surface waters (Larimore and Smith, 1963). 

The herbicides considered in this EIS are eliminated rapidly from the bodies of aquatic 

animals and do not bio-accumulate up the food chain. Therefore, cumulative effects are 

unlikely to be different from the direct and indirect effects of each application. Forest Service 

use of herbicides is typically a small percent of the herbicides used in a large watershed of 

mixed ownership (see Basis for Cumulative Effects Analysis Chapter 4.1.1.) and such use is 

unlikely to contribute substantially to downstream effects because the concentrations would 

be very low. 

Monitoring has occurred to determine whether detectable levels of herbicide reach streams in 

a field situation. In the Klamath River watershed (California), detectable levels of 2,4-D and 

triclopyr were found in streams following heavy rainfall (Wofford et al., 2001). However, 

concentrations of these herbicides were ten to one thousand times less than the estimated 

NOEC for aquatic species. Rashin and Graber (1993) also found triclopyr, 2,4-D, and 

glyphosate in surface water following aerial application, attributed to off-target swath 

displacement and drift. Environmental concentrations of these herbicides were four to ten 

times less than the estimated NOEC for aquatic species. 

Methodology, Unknown Information and Approach to Uncertainty 

Forest Service/SERA Risk Assessments for this EIS were modeled for each herbicide 

considered under this EIS (SERA, 1998; 2001; 2003; 2004). The risk assessments model the 

amount of chemical that can reach water under several different scenarios, then compares 

results to existing monitoring data to check the accuracy of the model. A stream or water 

body contaminated by runoff and percolation immediately after application of an herbicide is 

the scenario used to predict acute exposure to aquatic species (Worksheet F06 and Tables 3-1 

and 3-2, risk assessments). Herbicide concentration levels in water are estimated from 

monitoring and modeling data. Dissipation, degradation and other environmental processes 

are considered to predict chronic exposure for aquatic species (Worksheet F09 and Tables 3-1 

and 3-2, risk assessments). Calculations are detailed in worksheets, which can be duplicated 

using site-specific information to predict potential concentrations of chemicals in surface 

water. This information can then be used to evaluate the potential effects to aquatic 

organisms and water quality. 

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Under the risk assessments, three types of estimates were used for the concentration of each 

herbicide in ambient water: acute, accidental, and longer-term exposure. The accidental 

exposure scenario is based on a spill of a fixed amount of herbicide into a water body of a 

fixed size (0.25 acres in surface area and 1 meter deep) assuming instantaneous mixing. The 

acute exposure scenario is associated with peak concentrations in a pond or lake that might be 

expected after the application of an herbicide to a 10 acre block that is adjacent to and drains 

into a small stream or pond. The longer-term exposure scenario is based on average 

concentrations that might be expected after a similar application – i.e., a 10 acre block that is 

adjacent to and drains into a small stream or pond. 

What information is missing? 

Studies of effects to aquatic fungi or unicellular organisms are generally not available. 

Herbicide effects to these organisms are likely, though the available information shows both 

benefits and negative effects. Effects to aquatic fungi and unicellular organisms are likely to 

be transient and localized. Standards that protect other aquatic organisms should also serve to 

protect these organisms. Similarly, information about herbicide effects to amphibians is 

limited. See the discussion of effects in Chapter 4.4 for more information. 

Contamination of water by herbicides and changes in water chemistry and temperature all 

increase stress on fish. Although herbicides are widely used in forestry, their overall impact 

on water quality, and fish breeding and survival has not been studied thoroughly. 

Information about sub-lethal herbicide effects to fish is also limited. For some herbicides, the 

risk assessments were based on studies that identified the NOEC for sublethal effects directly 

(See SERA, 2003-chlorsulfuron; 2003-imazapic; 2003-metsulfuron methyl; 2003-

sulfometuron methyl; 1998-2,4-D; and Bakke, 2003). These risk assessments were most 

likely to adequately encompass risk of sub-lethal effects to fish, and their significance to fish 

populations. For other herbicides, the risk assessment estimated NOECs from lethal doses 

(LC50’s, which may not encompass concern for sub-lethal effects. The estimated NOECs are 

very conservative, in part to take into account potential sub-lethal effects. 

Is this relevant to reasonably foreseeable significant adverse impacts 

essential to a reasoned choice among alternatives? 

No, the approach of using worst-case scenarios and applying strict standards for use of 

herbicides resolves the need for additional information. Reasonably foreseeable adverse 

impacts are fully disclosed. 

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The aquatic resources specialists’ report contains information about herbicide effects on water 

quality, riparian function, and aquatic biota, which can be found in the analysis file. 

Appendix J, the Effects of Non-Herbicide Methods of Invasive Plant Treatments on Wildlife, 

Fish and Plant addresses the effects of non-herbicide treatment. 

4.7.3 Threatened, Endangered and Sensitive Species 

Introduction 

Invasive plant management has the potential to affect federally listed and Forest Service 

Sensitive (TES) plant, wildlife, and fish species. Forest Service policy related to the National 

Forest Management Act, the Endangered Species Act (ESA), and manual direction (FSM 

2670) require analysis of effects to threatened, endangered, and sensitive species. Any 

practice focused on reducing introduction and spread of invasive plants will indirectly benefit 

threatened, endangered or sensitive species, or critical habitat adversely affected by 

infestations. 

Effects determinations for TES plants, animals and fish are the same for all alternatives, even 

though the alternatives result in different kinds of risk, as described in Chapters 4.3, 4.4, and 

4.7. The vast majority of invasive plant treatment and restoration projects can be designed to 

reduce or eliminate adverse effects to some TES species. Standard #20 was specifically 

developed to ensure that such mitigation takes place. However, adverse effects could occur 

under any alternative for some treatment methods on individuals. Some projects must have a 

short-term adverse effect to individual plants in order to provide a long-term benefit to listed 

and TES species. 

Threatened and Endangered Plants 

Direct and Indirect Effects 

Direct and indirect effects of non-herbicide treatments to non-target plants are disclosed in 

Appendix J. Direct and indirect effects from herbicide treatments to non-target plants are 

disclosed in Chapter 4.3. Treatments to control invasive plants may indirectly harm native 

plants as discussed under Issue #2. However, invasive plant treatments are more likely to 

benefit listed plant species. Careful treatment around listed populations would reduce 

competition from invasive plants for resources, increase habitat quality, and improve chances 

for expansion of listed plant species. 

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Herbicide treatments have the potential to affect listed species in Region Six. As mentioned 

in Chapter 3.2, herbicides that target broadleaf plants in general, tend to more negatively 

affect plants in the sunflower, legume, and mustard families. Therefore, there may be the 

potential for increased risk for such listed species as Kincaid’s lupine (legume family) and 

McDonald’s rock-cress (mustard family) when herbicides are part of the treatment strategy in 

potential habitat. Damage to Kincaid’s lupine from herbicide spraying has already been 

documented under its Federal Register listing (USDI FWS, 2000-Erigeron). Some of the 

sulfonylurea group of herbicides, known to be harmful to commercial onions (members of the 

lily family), may more readily affect Gentner’s fritillary, also a member of that family. 

Damage to individuals in a single population may adversely affect these individuals, but 

would not affect the species as a whole. This is primarily because very little habitat for the 

above three species exists on National Forest System lands; the vast majority of the species is 

found outside of the project area. In the case of McDonald’s rock-cress, even though invasive 

plant seed may be brought in to its habitat from OHVs or equipment related to fire 

suppression, the high serpentine content and barren, rocky soils would limit the spread of 

invasives. What species could germinate would be easily identified and treated because very 

little plant cover exists in the habitat for this species. 

Given the beneficial effects from restoring native habitat and reducing competition from 

invasive species, individual impacts would not affect the species as a whole. In most cases, 

these effects on individuals could be mitigated through Standard #20 by such means as 

buffering, timing of treatments during dormancy, exclosures or flagging of individuals before 

treatments. 

The following table (Table 4-42) summarizes the effects determinations made on federally 

listed documented and suspected plant species for this EIS in Region Six. The differences 

between the alternatives (including No Action) do not result in different effects 

determinations for federally listed plans at this programmatic scale. All action alternatives are 

likely to adversely affect some listed species. No Effect determinations were given to those 

species with no known locations on National Forest System lands and little to no habitat 

available. Not Likely to Adversely Affect (NLAA) determinations are applied to those 

species that had very little habitat on National Forests in Region Six, were not in habitats 

susceptible to invasive plants, or were known to tolerate herbicide treatments without effects. 

Aerial spraying, especially in Alternative D would tend to make adverse effects more 

plausible. Two federally-listed species documented in Region Six are most likely be 

adversely affected by invasive plant treatments under aerial spray treatments circumstances in 

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Alternative D. McFarland’s four o’ clock and Spaulding’s Catchfly could be affected if 

specific populations or suitable habitat are located on steep, inaccessible canyon terrain, 

where aerial spraying would most likely occur. Because no restriction on aerially spraying 

sulfonylurea active ingredients is required in Alternative D, there may be more risk to listed 

plants from drift of these potent substances. 

The EPA has issued pesticide use limitations for Wallowa County, Oregon to protect 

MacFarlane’s four-o’clock. These limitations are currently voluntary, but may become a 

requirement in the future. A list of herbicides and corresponding buffers was issued by the 

agency and most recently updated in 2003. The herbicides on the list covered under this EIS 

are dicamba, picloram, sulfomethuron methyl and 2,4-D. This group of herbicides cannot be 

applied within 100 yards of species habitat for aerial application or within 20 yards of species 

habitat for ground applications. Also, sulfomethuron methyl cannot be applied on rights-ofway within species habitat. These limitations are required in two specific areas in the county 

(www.epa.gov/espp/oregon/wallow.htm). This extra restriction would limit adverse effects 

on this species in these specific areas, if instituted. 

One species documented in Region Six is also most likely to be adversely affected by invasive 

plant treatments, but not because of aerial spraying. Showy stickseed has only one known 

occurrence on theWenatchee National Forest. Its habitat consists of unstable, rocky slopes 

that are difficult to traverse without causing soils to move and potentially damage individuals. 

Adverse impacts could occur from the application of any type of treatment. Without such 

treatments, though, the dalmation toadflax present would threaten to outcompete individuals 

and invade its only known population, hence affecting the species as a whole. While some 

effects may occur, the benefits would outweigh individual damage. 

Table 4-42 Potential Effects and Determination Statements for Federally Listed Plants 

Effects Determinations apply to all alternatives. 

LAA = Likely to Adversely Affect; NLAA = Not Likely to Adversely Affect; NE = No Effect 

S = Suspected; not documented on Forest Service lands

Species and Listing Category Determination and Basis for Determination 

Showy Stickseed 

Hackelia venusta 

Endangered 

LAA. 

One known site currently threatened by invasive plants. Difficult 

terrain and loose soils may cause damage to plants downslope. 

Wenatchee Mountain Checkermallow 

Sidalcea elissa var. calva 

Endangered 

NLAA. (for species and critical habitat). 

One site on Forest Service land with no current invasive plant 

problems. Invasive plant treatments occurring on DNR land have 

shown no negative effect. 

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Table 4-42 Potential Effects and Determination Statements for Federally Listed Plants 

Effects Determinations apply to all alternatives. 

LAA = Likely to Adversely Affect; NLAA = Not Likely to Adversely Affect; NE = No Effect 

S = Suspected; not documented on Forest Service lands

Species and Listing Category Determination and Basis for Determination 

MacDonald’s Rockcress 

Arabis macdonaldiana 

Endangered 

NLAA. 

Very small portion of known populations found in the project area. 

Habitat is in a plant community with low susceptibility to invasive 

plants. If invasives were brought it, effects would be easily 

mitigated due to sparse nature of plant cover. 

Gentner’s fritillary 

Fritillaria gentneri 

Endangered 

NLAA. 

Found in plant communities susceptible to invasion, but majority of 

populations are not on Forest Service land. Potential habitat is 

present, but limited. Surveys completed regularly. 

Kincaid’s Lupine 

Lupinus sulphureus ssp. Kincaidii 

Threatened 

NLAA. 

Found in plant communities susceptible to invasion (roadsides), but 

only one population on Forest Service land with no current invasive 

plant problems. Surveys completed regularly. 

MacFarlane’s Four O’Clock 

Mirabilis macfarlanei 

Threatened 

LAA. 

Although the species should benefit from invasive plant treatments 

in its habitat, adverse effects could occur especially under aerial 

spray conditions if accidental drift occurs. Damage from herbicide 

drift to this species has already been documented in Idaho (Federal 

Register 1996). 

Spaulding’s Catchfly 

Silene spauldingii 

Threatened 

LAA. 

In canyon grassland habitat threatened by invasives. Although the 

species should benefit from invasive plant treatments in its habitat, 

adverse effects could occur especially under aerial spray conditions 

if accidental drift occurs. 

Marsh Sandwort 

Arenaria paludicola 

Endangered (S) 

NE. 

Considered extirpated in Region Six. Closest population in San Luis 

Obispo county, CA. 

Water howellia 

Howellia aquatilis 

Threatened (S) 

NE. 

Closest known location is downstream of the Columbia River Gorge 

National Scenic Area. 

Western Lily 

Lilium occidentale 

Endangered (S) 

NE. 

All known locations are south of Siuslaw National Forest. Potential 

habitat exists but susceptibility to invasion is low. 

Cook’s Lomatium 

Lomatium eliss 

Endangered (S) 

NLAA. Found in plant communities susceptible to invasion, but 

very little potential habitat on Forest Service land. Surveys 

completed regularly. 

Rough Popcorn Flower 

Plagiobothyrus hirtus 

Endangered (S) 

NE. Highly unlikely to be found. Species requires unique soil 

requirements in low elevation floodplains not found near Forest 

Service land. 

Nelson’s Checkermallow 

Sidalcea nelsoniana 

Threatened (S) 

NE. 

No known locations and very little potential habitat exists on Forest 

Service land. Surveys completed regularly. 

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Table 4-42 Potential Effects and Determination Statements for Federally Listed Plants 

Effects Determinations apply to all alternatives. 

LAA = Likely to Adversely Affect; NLAA = Not Likely to Adversely Affect; NE = No Effect 

S = Suspected; not documented on Forest Service lands

Species and Listing Category Determination and Basis for Determination 

Ute Ladies Tresses 

Spiranthes diluvalis 

Threatened 

NLAA. No known locations on Forest Service land and habitat very 

limited. Surveys completed regularly. 

Cumulative Effects 

Herbicide treatments in Oregon and Washington have the potential to damage federally listed 

species. Multiple incidents of damage to federally listed plants are extremely unlikely, but 

possible, especially for species that occur in roadside habitat (e.g. Kincaid’s lupine). Damage 

to Kincaid’s lupine from roadside herbicides spraying has already been documented under its’ 

Federal Register listing (2000). 

Other federal agencies (such as Bureau of Land Management) adhere to Endangered Species 

Act requirements and other TES species policies, ensuring protection of native plants and 

threatened, endangered or sensitive species. State agencies follow state policies. For 

example, the Oregon Endangered Species Act (OAR 603-073) protects state listed threatened 

and endangered plants on state-owned and state-managed lands. Protection and conservation 

programs are managed by the Oregon Department of Agriculture (the same entity managing 

invasive plants). 

In Washington, a similar act does not exist, but the Washington Natural Heritage program is 

required by law (RCW 79.70) to manage a statewide system of natural areas. A biennial 

Natural Heritage plan lays out such a system based on prioritization of rare plants and plant 

communities in need of protection. It is administered by the Washington Department of 

Natural Resources. Oregon also has a Natural Heritage Plan using a similar approach to 

protection of priority plants and plant communities as Washington. Both states maintain a 

Natural Heritage list of rare plants and animals, ranked by level of threat, following the same 

global ranking used by the Nature Conservancy (described in Chapter 3). 

Increased herbicide use by the Forest Service, combined with increased use by adjacent 

landowners, would create the highest potential for adverse effects to individuals of federally 

listed species under all land ownership. The restoration of native habitat due to these 

combined treatments would provide a beneficial cumulative effect to listed species. 

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Regional Forester’s Sensitive Plants 

The potential to affect documented and suspected sensitive plants in Region Six varies by 

plant family. Species within the sunflower, legume or mustard family may be the most 

sensitive to herbicide treatment in general. Numerous genera from these families occur on the 

list including Arabis, Erigeron, and Astragalus. Species in the lily family may be more 

sensitive to some of the sulfonylurea herbicides. The lily family is a large component of the 

Region Six sensitive species list. The genus Calochortus (or Mariposa Lily) alone has eight 

species on the list. 

Any species along roadsides or where activities occur that disturb native plant communities 

will be threatened by not only invasive plants, but by invasive plant treatments. Some 

sensitive plants actually do well in disturbed areas because the natural processes which 

created openings or gaps have been eliminated. For example, the species Sophora leachiana 

in the legume family, which occupies a very narrow range in southwestern Oregon, has 

moved into roadside and skid trail areas since gaps in forest canopy have been reduced due to 

lack of natural fire. 

Recently, 80 fungi and non-vascular (lichens and bryophytes) plants have been added to the 

regional sensitive species list. Some species and their communities could be negatively 

affected by at least two active ingredients (triclopyr and glyphosate). Fungi could be 

negatively affected by herbicides known to affect soil mycorrhizae (sulfometuron methyl, 

picloram, glyphosate, triclopyr), but studies are laboratory based and results difficult to 

extrapolate to field situations (see Chapter 4.3 or soils analysis). These species are associated 

with late successional forest ecosystems, which are not usually of high susceptibility to 

invasion and would not contain the vegetation communities most likely to be treated by aerial 

application of herbicides. 

Direct and Indirect Effects 

The Proposed Action may impact individuals, but is not likely to lead to federally listing any 

sensitive plants. Alternative B may impact individuals, but is not likely to lead towards a trend 

to federally list any sensitive plants. Alternative D has the most potential to impact 

individuals, due to more reliance on aerial application of herbicide, but is not likely to lead to 

federally list. Aerial spraying could be problematic to non-vascular or fungi species in 

general, but habitat for these species is not likely to occur where conditions are most 

appropriate for use of aerial application methods. 

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Cumulative Effects 

Cumulative effects on sensitive species are the same as those described previously under 

federally listed species. More information on sensitive plants can be found in the project 

analysis file. 

Threatened and Endangered Wildlife 

Invasive plants are adversely affecting habitat for grizzly bear, woodland caribou, western 

snowy plover, and Oregon silverspot butterfly. Invasive plants are adversely affecting the 

habitat of prey for the gray wolf and Canada lynx. See Chapter 3 for more information about 

how invasive plants affect wildlife.54

The primary impacts that could lead to adverse effects on wildlife are from ground 

disturbance related to manual/mechanical treatments, and noise/human activity that disturbs 

individual wildlife. All of the alternatives approve similar non-chemical methods of 

treatment, and would result in similar potential for impacts to listed species. The effects 

determinations reflect potential effects from a small number of future projects; the vast 

majority of invasive plant treatments are expected to have no or discountable effects to listed 

species. If there is any possibility of an adverse effect from any future project, then the 

effects determination in this plan-level EIS was listed as “likely to adversely affect.” The 

potential for adverse effect occurs in all alternatives, so there is no difference between the 

alternatives in the effects determinations. 

The discussions about potential adverse effects of herbicides to federally listed species, (and 

Region Six sensitive species discussed later in this section) are based on Forest Service/SERA 

Risk Assessments that correlate laboratory results to wildlife using exposure scenarios. 

Potential effects from NPE-based surfactants were adapted from USDA Forest Service, 2003. 

Results of exposure scenarios were applied to federally listed species of similar type (i.e. 

mammal, bird, etc.), body size, and diet55. The scientific uncertainty discussed in Chapter 4.4 

also applies to the discussions on federally listed species. 

Direct and Indirect Effects 

 

54 Life history information on wildlife species listed as threatened or endangered under the provisions of the 

Endangered Species Act are included in a report in the project file (“Brief Life History Narratives for Federally 

Listed and Forest Service Sensitive Animals and Plants in Region Six”) and in the Biological Assessment for this 

EIS. 

55 Results of exposure scenarios are detailed in a report in Appendix P, “Summary of Herbicide Effects to 

Wildlife”. 

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No direct effects on threatened or endangered wildlife are associated with prevention 

standards, because they deal with procedural requirements. To the extent they are effective, 

prevention standards would have positive indirect effects by reducing the damage to habitat 

caused by invasive plants. No suite of prevention measures will be completely successful at 

protecting habitat for threatened and endangered species, because invasive plants can be 

introduced and spread by means other than those within management control (natural vectors, 

illegal disposal or introduction, adjacent land activities, etc.). Successful control of invasive 

plant infestations provides long-term benefits to populations of listed species, by restoring 

native habitat and preventing future degradation of habitat. 

Methods used to treat invasive plants or restore habitat may affect federally listed wildlife. 

The effects of each method to wildlife are discussed in Appendix J, “The Effects of NonHerbicidal Methods of Invasive Plant Treatment on Wildlife, Fish and Plants,” and Appendix 

P, “Summary of Herbicide Effects to Wildlife”. 

Direct effects from invasive plant treatment include disturbance caused by noise, smoke, 

aircraft, people and vehicles. These activities could potentially disturb grizzly bear, gray 

wolf, Canada lynx, woodland caribou, bald eagle, northern spotted owl, marbled murrelet, and 

western snowy plover during the breeding season, causing the birds to leave nests, or 

mammals to change feeding or denning location. The absence of parent birds, or disturbance 

of a parent bird on the nest, may result in mortality to eggs or young. However, invasive plant 

projects involve very short-term disturbance with few people, and might only be repeated 

once in the same growing season. The life history traits of the species, current literature, 

existing guidelines, and expert opinion of biologist’s familiar with the species, indicate that 

the level of disturbance expected from any invasive plant project is not likely to adversely 

disturb grizzly bear, gray wolf, Canada lynx, or woodland caribou. 

Oregon silver spot butterfly adults appear to be unaffected by disturbance (Frounfelker, 

personal communication). The butterfly larvae are underground or near ground-level when 

mowing is conducted to improve habitat for the food plant, Viola adunca. But, mowing, other 

machinery, foot traffic, or other cultural methods have the potential to trample butterfly 

larvae. Livestock used specifically for invasive plant control are not likely to adversely affect 

any listed species within the Region. 

American brown pelicans do not occur in the vicinity of invasive plant infestations, and will 

not be directly or indirectly affected by treatment methods. Fender’s blue butterfly has not 

been documented on National Forest System land. The one locations of its food plant, 

Kinkaid’s lupine, on National Forest System land is not currently affected by invasive plants. 

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Therefore, invasive plant treatments are not likely to adversely affect Fender’s blue butterfly. 

Potential effects to the food plant of the Fender’s blue butterfly (Kincaid’s lupine) are also 

discussed in the section on federally listed plants. 

The vast majority of invasive plant treatment and restoration projects can be designed to 

reduce or eliminate adverse effects to listed species, as required in Standard 20 for all 

alternatives. However, invasive plant projects that benefit wildlife in the long run may have 

short-term adverse effects. For example, short-term disturbance near snowy plovers may be 

warranted if it allows treatment of invasive plants that threaten the long-term viability of the 

plover’s habitat. 

Little research has been done on the direct effects of specific herbicides, NPE, or other control 

techniques on listed species. The ESA often prohibits experimental testing directly on a listed 

species. On the rare occasions that samples could be taken from listed species, the limited 

conditions under which they are taken may bias the results (see Wiemeyer et al., 1993 for 

example). For this analysis, toxicity data collected using surrogate species were applied to 

similar types of wildlife. 

The use of herbicide mixtures was also considered in the analysis. No mixtures are permitted 

in Alternative B, so no adverse effects from herbicide mixtures would occur. In the Proposed 

Action and Alternative D, Standard #16 limits mixtures to three or less active ingredients and 

allows use only when the sum of the individual hazard quotients is less than 1.0. This 

standard reduces the likelihood of adverse effects from herbicide mixtures, although some 

uncertainty remains for potential effects from mixtures. But this method is a reasonable 

approach when analyzing mixtures of chemicals with different or unknown toxicity 

mechanisms, when expected does will be below known toxic levels (ATSDR, 2004). It is not 

known which mixtures, if any, will be used during project implementation, so no quantitative 

estimates of exposure are calculated as the scale of this EIS. Standard #16 requires projects to 

conduct the analysis prior to implementation. 

Actual herbicide or NPE exposure to most of these listed species is very unlikely due to their 

diets, behavior, distribution, and the life history traits of their prey. Effects from disturbance 

are the most likely to occur. Alternative B has a higher likelihood of disturbance than other 

alternatives due to the increased number of acres projected to be treated manually or 

mechanically. However, the total number of acres treated in close proximity to listed species 

is likely to be very low for all alternatives, because most species distributions are limited in 

the project area, and projects can be designed to avoid these effects as required by Standard 

#20. Therefore, the minor differences in acres treated by the various methods, do not result in 

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any substantial differences in potential effects to listed species between the alternatives. 

Exposure scenarios used to analyze potential effects from herbicides are discussed in 

“Summary of Herbicide Effects to Wildlife” (analysis file). 

Results of worst-case scenarios applied to species listed under the ESA are displayed in Table 

4-43. The potential effects displayed are not likely to occur under actual field conditions, 

because the worst-case scenarios do not account for plausibility of exposure, differences in 

application methods and timing, seasonal presence, species behavior, current protection 

measures in place, the current distribution of the species, or the standards included in each 

alternative in this EIS. 

Grizzly bears and woodland caribou forage on vegetation in the spring, so they could be 

exposed to herbicide or NPE residues on vegetation from broadcast spray applications. 

Estimated doses to a grizzly bear- or caribou-sized herbivore for triclopyr, 2,4-D, and NPE 

exceed known LOAEL’s for these chemicals. 

Grizzly bears are unlikely to be exposed to doses of herbicide or NPE that would exceed the 

toxicity indices, or cause adverse effects because grass is not usually intentionally treated by 

herbicides in their habitat; they eat other items besides grass, meadows are not broadcast 

sprayed, and these herbicides are generally not used on the invasive plants in meadows that 

grizzly bears use. Also, the bears would avoid treatment areas because of disturbance, they 

have extremely large home ranges, are unlikely to intersect treatment areas, and Standard #20 

requires projects to be designed to mitigate the potential for adverse contaminant exposure. 

Caribou may forage on grasses and broad-leaved herbaceous plants during the spring. 

Treatment of meadows used by caribou in the spring does not occur until later in the year 

(Ridlington, personal communication). Caribou are not likely to receive doses exceeding the 

toxicity indices, or that cause adverse effects, because they range over very large areas, would 

not forage solely within the treatment area, herbicide use and their presence would occur at 

different times of the year, and Standard #20 requires projects to be designed to mitigate the 

potential for adverse contaminant exposure. 

Projects in grizzly bear and caribou habitat that treat invasive plants with herbicide are 

ongoing and have been able to avoid any potential adverse effects to these two species 

(McGowan, personal communication). 

Gray wolf and Canada lynx would have to eat an entire day’s supply of prey that had been 

directly sprayed to receive doses exceeding the toxicity indices. This is extremely unlikely 

because their prey are not susceptible to inadvertent direct spraying. Similarly, the prey of 

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spotted owls is mostly arboreal and/or nocturnal, making it highly unlikely that it could be 

directly sprayed. The ocean fish that marbled murrelets and American brown pelicans feed on 

will not be exposed to herbicides from invasive plant control on the National Forests. 

Western snowy Plovers feed upon insects along the surf-line, which will also not be exposed 

to herbicides. Bald eagles could ingest fish that have been exposed to herbicide that entered 

the water through runoff or accidental spill. However, the herbicides considered in this EIS 

do not concentrate up the food chain, and none of the contaminated fish scenarios exceed the 

toxicity indices. 

Herbicides have not been used in habitat for the Oregon silver spot butterfly, but they may 

need to be used in the future if invasive plants with thickly matted root systems threaten the 

butterfly’s food plant. Potential effects to butterfly larvae or eggs, or food plants, may occur 

from herbicide use in their habitat. Sucoff et al. (2001) found that spraying eggs of Karner 

blue butterfly (Lycaeides elissa samuelis) with a glyphosate- triclopyr mixture reduced egg 

hatching, but other herbicides and mixtures did not affect egg hatching. Herbicides have been 

used in some butterfly habitat without apparent adverse effects to butterfly populations 

(Bramble et al., 1997; Bramble et al., 1999). 

Table 4-43 Summary of Worst-Case Exposure Scenarios for Federally Listed Wildlife 

Symbol meanings are as follows: 

 Exposure scenarios result in a dose below the toxicity index at typical and highest application rates. 

1 Exposure scenarios exceed the toxicity indices at the typical and highest application rates. 

♦ Exposure scenarios exceed the toxicity indices at the highest application rate only. 

? No reliable data exists. 

Italicized herbicides are not included in the Proposed Action. 

SPECIES 

Chlorsulfuron Clopyralid Dicamba Glyphosate Imazapic Imazapyr Metsulfuron  methyl Picloram Sethoxydim Sulfometuron methyl Triclopyr 2,4-D NPE 

Grizzly Bear -- -- 1♦ ♦ -- -- -- ♦

-- -- ♦ 1 1 1

Gray Wolf -- -- -- -- -- -- -- -- -- -- 12 1 ♦2

Canada Lynx -- -- -- -- -- -- -- -- -- -- 12 1 ♦2

Woodland 

Caribou -- -- 1♦ ♦ -- -- -- ♦

-- -- ♦ 1 1 1

American 

Brown Pelican -- -- -- -- -- -- -- -- -- -- -- -- -- 

Bald Eagle -- -- -- -- -- -- -- -- -- -- -- -- -- 

No. Spotted -- ♦ -- -- -- -- -- -- ♦2 -- ♦2 12 ♦2

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 4-43 Summary of Worst-Case Exposure Scenarios for Federally Listed Wildlife 

Symbol meanings are as follows: 

 Exposure scenarios result in a dose below the toxicity index at typical and highest application rates. 

1 Exposure scenarios exceed the toxicity indices at the typical and highest application rates. 

♦ Exposure scenarios exceed the toxicity indices at the highest application rate only. 

? No reliable data exists. 

Italicized herbicides are not included in the Proposed Action. 

SPECIES 

Chlorsulfuron Clopyralid Dicamba Glyphosate Imazapic Imazapyr Metsulfuron  methyl Picloram Sethoxydim Sulfometuron methyl Triclopyr 2,4-D NPE 

Owl -- 

Marbled 

Murrelet -- -- -- -- -- -- -- -- -- -- -- -- -- 

Western 

Snowy Plover -- -- -- -- -- -- -- -- -- -- -- -- -- 

OR Silver 

Spot Butterfly1 -- -- -- ♦ -- -- --- -- -- -- ♦ 1 ? 

1 There are no exposure scenarios for butterflies, so the honeybee scenario is used as a surrogate for this table. 

Toxicity data for butterflies is not available, so while a “diamond” or “star” indicates a definite concern for 

terrestrial invertebrates, a “minus” does not necessarily indicate an absence of concern. 

2 These scenarios exceed the toxicity index only for assumed chronic exposures. There is no chronic exposure 

estimate available, so acute exposure was compared to the chronic toxicity index, which overestimates risk, and 

likely substantially so. It is more accurate to state that risks are unknown, but in keeping with the “worst-case” 

analysis presented here, the scenarios are counted as exceeding the toxicity index. 

Indirect effects to federally listed species would consist of changes to their habitat. Invasive 

plant treatments will not remove or degrade suitable habitat for any federally listed species. 

Successful control of invasive plant infestations provides long-term benefits to populations of 

listed species, by restoring native habitat and preventing future degradation of habitat. 

Indirect effects of herbicide are not likely for any listed species because exposure for these 

species is so unlikely. 

The following table (Table 4-44) summarizes the potential effects to each listed species. 

Determinations are based on the possibility of adverse effects at the project level, when the 

standards in this EIS are implemented, rather than only on the effects of the standards 

themselves. The uncertainty regarding herbicide exposure or proximity of disturbance 

prevent making a determination of “not likely to adversely affect” (NLAA) for some species. 

The vast majority of projects conducted under this EIS are not likely to adversely affect listed 

species. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Critical habitat is designated for the northern spotted owl, marbled murrelet, western snowy 

plover, and Oregon silverspot butterfly. Invasive plant treatment and restoration projects will 

not affect any of the primary constituent elements for critical habitat for the northern spotted 

owl (USDI FWS, 1992-Northern), or marbled murrelet (USDI FWS, 1996-Murrelet). 

Invasive plant treatment projects in western snowy plover critical habitat are implemented to 

restore the function of the primary constituent elements, which have been eliminated by 

invasive European beach grass. These projects will beneficially affect critical habitat for the 

western snowy plover. Disturbance to snowy plover habitat does occur during the removal of 

the European beach grass, which is interpreted here to be an adverse effect. Invasive plant 

treatment projects in Oregon silverspot butterfly critical habitat are implemented to protect 

and restore the larval food plant populations and nectar sources for this species. These 

projects beneficially affect critical habitat for the Oregon silverspot butterfly, but could create 

adverse effects during implementation. 

Table 4-44 Potential effects and Determination Statements for Federally Listed 

Wildlife 

Effect determination apply to all alternatives 

LAA = Likely to adversely affect; NLAA = Not likely to adversely affect; NE = No effect. 

Species and 

Listing 

Category 

Potential Effects Determination and Basis for 

Determination 

Grizzly bear 

Threatened

Infrequent and short-term disturbance 

from treatment projects. Herbicide 

exposure possible, but not very plausible. 

NLAA. 

Interagency guidelines reduce disturbance 

potential to NLAA Herbicide exposure 

highly unlikely due to feeding behavior 

and home range size. 

Gray wolf 

Endangered 

Infrequent and short-term disturbance 

from treatment projects could occur. 

Worst-case herbicide exposure is highly 

unlikely. 

NLAA. 

Wolves are rare in the Region Disturbance 

not of a magnitude or intensity that would 

adversely affect wolves. 

Canada lynx 

Threatened

Infrequent and short-term disturbance 

from treatment projects could occur. 

Worst-case herbicide exposure is highly 

unlikely. 

NLAA. 

Canada lynx are rare in the Region. 

Disturbance not of a magnitude or intensity 

that would adversely affect the lynx. 

Woodland 

caribou 

Endangered 

Infrequent and short-term disturbance 

from treatment projects could occur. 

Forage on plants similar to broad-leaved 

forbs that might be treated (e.g. 

hawkweeds). 

NLAA. 

Disturbance regulated by Interagency 

Grizzly Bear Guidelines (caribou habitat is 

completely encompassed by grizzly bear 

recovery areas). Herbicide exposure 

highly unlikely due to feeding behavior 

and home range size. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 4-44 Potential effects and Determination Statements for Federally Listed 

Wildlife 

Effect determination apply to all alternatives 

LAA = Likely to adversely affect; NLAA = Not likely to adversely affect; NE = No effect. 

Species and 

Listing 

Category 

Potential Effects Determination and Basis for 

Determination 

American 

brown pelican 

Threatened

No effects are likely because of seasonal 

occurrence, prey will not be exposed, 

loafing and foraging sites are far 

removed from invasive plant locations. 

No Effect. 

Invasive plant treatments do not occur in 

pelican habitat and prey will not be 

exposed to herbicide. 

Bald eagle 

Threatened

Infrequent and short-term disturbance 

near nests. Worst-case exposure does not 

exceed toxicity index from ingesting 

contaminated fish. 

LAA. 

Disturbance closer than acceptable limits to 

nest or roost sites may occur. Frequency of 

LAA projects is expected to be very rare. 

Northern 

spotted owl 

Threatened

Infrequent and short-term disturbance 

near nests. Exposing Direct spray of prey 

to with herbicide is not plausible due to 

arboreal and/or nocturnal habit of prey. 

LAA. 

Disturbance closer than acceptable limits to 

nest and roost sites may occur. Frequency 

of LAA projects is expected to be very 

rare, if at all, because weeds are minimal in 

late-successional habitats. 

Marbled 

murrelet 

Threatened 

Infrequent and short-term disturbance 

near nests. Prey will not be exposed. 

LAA. 

Disturbance closer than acceptable limits to 

nest sites may occur. Frequency of LAA 

projects is expected to be very rare, if at 

all, because weeds are minimal in latesuccessional habitats. 

Snowy plover 

Threatened 

Infrequent and short-term disturbance 

near nests. Prey will not be exposed. 

LAA. 

Disturbance closer than acceptable limits to 

nest sites may occur. Current projects 

mitigate potential effects, reducing 

determinations to NLAA. Frequency of 

LAA projects is expected to be rare due to 

habitual nature of current protection 

measures. 

Oregon 

silverspot 

butterfly 

Threatened

Butterfly and their larvae appear to be 

insensitive to disturbance. Data on the 

effects of herbicides or NPE to 

butterflies are almost non-existent. 

Herbicide use may affect food plants. 

LAA. 

Herbicide use may affect food plants or 

larvae. Frequency of LAA project is 

expected to be rare. 

Fender’s blue 

butterfly 

Endangered 

None anticipated because habitat is not 

currently affected by invasive plants. 

NLAA 

This species has not been documented to 

occur on National Forest Land. Projects 

adjacent to habitat might have indirect 

effects, but effects are not likely because 

current monitoring would provide very 

early detection of invasive plants and allow 

low-impact removal. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Cumulative Effects 

Herbicide and NPE use on Region Six National Forests could contribute to some cumulative 

effects, but data is lacking that would permit any quantitative estimates of cumulative 

exposure or risk. All the federally listed species in the project area, except Oregon silverspot 

butterfly, migrate or move large distances across multiple ownership boundaries, potentially 

increasing the likelihood that they would be exposed to multiple uses of herbicide and other 

chemicals, as well as several instances of disturbance. Forest Service Region Four 

(Intermountain Region) is immediately adjacent to the project area and includes populations, 

recovery areas, and/or habitat for grizzly bear, woodland caribou, Canada lynx, and gray wolf. 

Region Four has an active program to control invasive plants and is conducting projects 

within the habitats of these species. Herbicide exposure to American brown pelican, Fender’s 

blue butterfly, gray wolves, Canada lynx, grizzly bear, woodland caribou, western snowy 

plover, marbled murrelet, and northern spotted owl are unlikely to occur for invasive plant 

treatment projects, so there will be minimal potential for cumulative effects from herbicide or 

NPE due to projects conducted under this EIS. Minimal herbicide and NPE exposure is 

possible for bald eagle, for projects conducted under this EIS. However, the herbicides in this 

document are excreted rapidly and do not accumulate up the food chain (“Summary of 

Herbicide Effects to Wildlife”, Appendix P), reducing, but not eliminating, the potential for 

cumulative effects from exposure. 

Oregon silverspot butterfly do not migrate and appear to be limited to existing sites. Potential 

herbicide use within their critical habitat in the project area is likely the only herbicide to 

which they could be exposed. Therefore, there will be no cumulative effects from herbicide 

exposure. These butterflies are not sensitive to disturbance, so there will not be any 

cumulative effects from disturbance either. 

Listed species can also be exposed to other chemicals, such as insecticides, rodenticides, 

fungicides, and others. This project does not include the use of any other types of pesticides, 

but the herbicide triclopyr and the insecticide chlorpyrifos share a common metabolite, TCP. 

Thus, the use of triclopyr could add to TCP exposure resulting from the use of chlorpyrifos. 

Another example of a potential cumulative effect is from hexachlorobenzene, a ubiquitous 

industrial pollutant, which is found in both picloram and clopyralid. While the amounts of 

hexachlorobenzene added to the environment from picloram and clopyralid do not represent a 

substantial addition in comparison to existing background levels (SERA, 2003-picloram; 

SERA, 2004-clopyralid), it could be considered a cumulative effect. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

The small contribution that Forest Service use of herbicide for invasive plant control makes to 

the statewide totals for herbicide use indicate that the potential cumulative effect on a regional 

scale is very small. Likewise, the relatively small differences between the alternatives, in 

comparison to the totals, make insignificant any differences between the alternatives in 

potential for cumulative effects to wildlife. The potential for cumulative effects a more local 

scales must be evaluated at the project level. 

The short-term and infrequent disturbance from invasive plant treatment projects is managed 

as part of the total allowable disturbance for grizzly bear, and indirectly for woodland caribou. 

It will not contribute to adverse cumulative effects. The short-term and infrequent 

disturbance from invasive plant treatments for other listed species is also insignificant 

compared to that occurring from existing roads (where most of the invasive plant infestations 

occur), recreation, and other activities. 

Forest Service Sensitive Wildlife 

Direct and Indirect Effects 

Invasive plants are currently adversely affecting some sensitive wildlife species. Chapter 3 

discusses the effects on habitats from invasive plants. The effects of invasive plant treatments 

to wildlife are discussed in two reports in the project file (“Summary of Herbicide Effects to 

Wildlife” and “The Effects of Non-herbicidal Methods of Invasive Plant Treatments on 

Wildlife, Fish and Plants”). The environmental effects to Forest Service Sensitive Species56

do not vary between the alternatives. 

No direct effects on Region Six Sensitive wildlife are associated with the prevention standards 

because they deal with procedural requirements. To the extent they are effective, prevention 

standards would have positive indirect effects by reducing the damage to habitat caused by 

invasive plants. No suite of prevention measures will be completely successful at protecting 

habitat for sensitive species, because invasive plants can be introduced and spread by means 

other than those within management control (natural vectors, illegal disposal or introduction, 

adjacent land activities, etc.). 

Indirect effects to Forest Service Sensitive species would consist of changes to their habitat. 

Invasive plant treatments will not remove or degrade suitable habitat for any sensitive species. 

 

56 Life history information on Forest Service Sensitive wildlife species (including former Survey and Manage 

Species) are included in a report in the project file (“Brief Life History Narratives for Federally Listed and Forest 

Service Sensitive Animals and Plants in Region Six”). 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Successful control of invasive plant infestations provides long-term benefits to populations of 

sensitive species, by restoring native habitat and preventing future degradation of habitat. 

The types of and potential for direct and indirect effects to wildlife are discussed in more 

detail in Chapter 4.4; these effect apply to Forest Service Sensitive species as well. Direct 

effects from non-herbicidal methods of invasive plant treatment include disturbance caused by 

noise, smoke, aircraft, people and vehicles. Results of numerous field studies indicate the 

likelihood for direct adverse effects to wildlife from herbicide use is low (e.g. Marshall and 

Vandruff, 2002; Dabbert et al., 1997; Fagerstone et al., 1977; Rice et al., 1997; Sullivan et al., 

1998; Cole et al., 1997; Cole et al. 1998; Johnson and Hansen, 1969; Nolte and Fulbright, 

1997, McMurray et al., 1993a; McMurray et al., 1993b). But the use of herbicides to treat 

invasive plants does have the potential to harm free-ranging wildlife. 

Since data do not exist regarding the toxicity of herbicides to most individual wildlife species 

in the Region, the Forest Service Sensitive wildlife species evaluated in this EIS were placed 

into exposure groups of similar niche, body size, and food habits. Table 4-45 lists the 

exposure groups, the exposure scenarios and the members of each group used for this 

analysis. Exposure scenarios are described in Appendix P. 

Table 4-45 Exposure Groups, Exposure Scenarios, and Species Included 

Exposure Group Exposure Scenarios Species Included 

Large Herbivorous 

Mammal 

Consumption of 100% contaminated 

grass 

Rocky Mountain bighorn sheep 

Small Herbivorous 

Mammals 

Consumption of 100% contaminated 

leaves and leafy vegetables 

Direct spray on 50% of body, complete 

absorption 

Consumption of water contaminated by 

an accidental spill. 

Western gray squirrel, pygmy rabbit, 

Western (Mazama) pocket gopher, 

Oregon red tree vole 

California wolverine, Pacific fisher Carnivorous 

Mammals 

Consumption of an entire days diet of 

prey that has been directly sprayed on 

50% of body surface 

Small Insectivorous 

Mammal 

Consumption of an entire day’s diet of 

contaminated insects 

Pacific pallid bat, Townsend’s bigeared bat, spotted bat, Pacific fringetailed bat, bats, Baird’s shrews, 

Pacific shrews 

Herbivorous Birds Consumption of 100% contaminated 

grass 

Greater sage grouse1

, sharp-tailed 

grouse, Columbian sharp-tailed grouse 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 4-45 Exposure Groups, Exposure Scenarios, and Species Included 

Exposure Group Exposure Scenarios Species Included 

Insectivorous Birds 

Consumption of an entire days diet of 

contaminated small insects using 

empirical relationships for residues in 

vegetation (no data available on 

concentrations of pesticides in insects) 

black swift, gray flycatcher, ashthroated flycatcher, green-tailed 

towhee, tricolored blackbird, 

bobolink, greater yellowlegs, upland 

sandpiper, yellow rail, bufflehead, 

harlequin duck 

Predatory Birds 

Consumption of an entire day’s diet of 

small mammal prey that has been 

directly sprayed 

northern goshawk, ferruginous hawk, 

American peregrine falcon2

, great 

gray owl, greater sandhill crane 

Fish-eating Birds 

Consumption of fish contaminated by an 

accidental spill 

common loon, Clark’s grebe, eared 

grebe, red-necked grebe, horned 

grebe, least bittern 

Reptiles 

None available. Information from 

literature is used. 

Sharptailed snake, California 

mountain kingsnake, common 

kingsnake, striped whipsnake, 

Northwestern pond turtle, painted 

turtle 

Amphibians 

For sulfometuron methyl, used water 

concentrations from runoff and 

percolation estimates. For other 

herbicides, information from literature is 

used. 

California slender salamander, Oregon 

slender salamander, black salamander, 

Cope’s giant salamander, Del Norte 

salamander, Larch Mountain 

salamander, Siskiyou Mountain 

salamander, Van Dyke’s salamander, 

Cascade torrent salamander, Columbia 

torrent salamander, Olympic torrent 

salamander, southern torrent (seep) 

salamander, foothill yellow-legged 

frog, northern leopard frog, Columbia 

spotted frog, Oregon spotted frog 

Mardon skipper Insects Direct spray of bee with 100% 

absorption, and literature 

Terrestrial 

mollusks 

None available. Information from 

literature is used. 

Puget Oregonian, Columbia 

Oregonian, evening field slug, Oregon 

shoulderband, Burrington’s jumping 

slug, warty jumping slug, Malone’s 

jumping slug, panther jumping slug, 

Chace sideband, Dalles sideband, 

Chelan mountainsnail, Crater Lake 

tightcoil, blue-gray taildropper, Hoko 

vertigo 

1 Most animals will eat more than one type of food. Species were placed in groups that represented the 

majority of their diet, or the type of diet that would pose the most risk. 

2 No scenario is yet available for animals that feed primarily on birds, so exposures from mammal prey are 

used. 

The following table (Table 4-46) summarizes the potential effects to each sensitive species 

group. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 4-46 Potential Effects to Sensitive Species. 

Impact determinations apply to all alternatives. 

Sensitive 

Species Group Potential Impacts Determination 

Large 

herbivorous 

mammal 

Fire may increase incidence of cheatgrass 

reducing forage diversity. Worst-case exposure 

exceeds toxicity index from ingesting forage that 

has dicamba, glyphosate, sulfometuron methyl, 

triclopyr, 2,4-D, or NPE if broadcast sprayed. 

Worst-case herbicide exposure is highly unlikely 

for non-selective herbicides; more likely for 

selective herbicides. 

MINL1

Bighorns utilize cheatgrass, 

reducing somewhat the effects of 

fire. Worst-case exposure unlikely 

to occur in most cases, but is 

possible for some large-scale 

broadcast applications. 

Small 

herbivorous 

mammals 

Fire and mechanical treatments may reduce 

cover and increase incidence of cheatgrass in 

pygmy rabbit habitat. Worst-case exposure 

exceeds toxicity index from ingesting forage that 

has been sprayed with 2,4-D, or NPE if broadcast 

sprayed. Worst-case herbicide exposure is 

highly unlikely for non-selective herbicides; 

much more likely for selective herbicides. 

MINL. 

Short-term adverse effects provide 

long-term benefit. Worst-case 

exposure unlikely to occur in most 

cases, but is possible for some 

large-scale broadcast applications. 

Carnivorous 

mammals 

Infrequent and short-term disturbance may occur. 

Worst-case exposure exceeds toxicity index from 

ingesting prey that has been sprayed with 

triclopyr 2,4-D, or NPE. 

No Effect. 

Disturbance unlikely to reach an 

intensity or duration that would 

cause an adverse affect. Worstcase herbicide exposure is not 

plausible for these species. 

Insectivorous 

mammals 

Fire and mechanical treatments may reduce 

foraging areas. Worst-case exposure exceeds 

toxicity index from ingesting prey that has been 

sprayed with clopyralid, dicamba, glyphosate, 

picloram, sethoxydim, sulfometuron methyl, 

triclopyr 2,4-D, and NPE if broadcast sprayed. 

Worst-case herbicide exposure is highly unlikely 

for bats, somewhat more likely for shrews. 

MINL. 

Little overlap between invasive 

plants and shrew habitat. Field 

study showed lower concentrations 

of herbicide residue in shrews than 

worst case scenario (Newton et al. 

1990). Bats may forage over large 

areas, reducing exposure. 

Herbivorous 

birds 

Fire, grazing, and mechanical treatments may 

reduce cover and increase incidence of 

cheatgrass within grouse habitat. Worst-case 

exposure exceeds toxicity index from ingesting 

forage that has been sprayed with clopyralid, 

dicamba, glyphosate, sethoxydim, sulfometuron 

methyl, triclopyr 2,4-D, or NPE, if broadcast 

sprayed. Worst-case herbicide exposure is 

highly unlikely for non-selective herbicides; 

much more likely for selective herbicides. 

MINL. 

Adverse effects to individuals are 

possible, but all species are wideranging, occurring in several states, 

so effects from isolated invasive 

plant treatments are not likely to 

lead to a trend toward federal 

listing. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 4-46 Potential Effects to Sensitive Species. 

Impact determinations apply to all alternatives. 

Sensitive 

Species Group Potential Impacts Determination 

Insectivorous 

birds 

Manual, mechanical, grazing and fire could 

trample or harm eggs or young of ground- or 

low-nesting species during the breeding season. 

Worst-case exposure exceeds toxicity index from 

ingesting prey that has been sprayed with 

clopyralid, dicamba, glyphosate, picloram, 

sethoxydim, sulfometuron methyl, triclopyr, 2,4-

D, or NPE if broadcast sprayed. Worst-case 

herbicide exposure is plausible for grassland 

species on large projects. 

MINL. 

Adverse effects to individuals are 

possible, but all species are wideranging, occurring in several states, 

so effects from isolated invasive 

plant treatments are not likely to 

lead to a trend toward federal 

listing. 

Predatory 

birds 

Manual, mechanical, and fire treatments could 

disturb species during the nesting season. Worstcase exposure exceeds toxicity index from 

ingesting prey that has been sprayed with 

sethoxydim, triclopyr, 2,4-D, or NPE if broadcast 

sprayed. 

MINL. 

Disturbance possible, but would be 

short-term and low intensity. 

Worst-case exposures to herbicides 

not plausible. 

Fish-eating 

birds 

Manual and mechanical treatments could disturb 

species during the nesting season. Worst-case 

exposure does not exceed toxicity index for any 

herbicide. 

MINL. 

Disturbance possible, but would be 

short-term and low intensity. 

Reptiles Mechanical and fire treatments could trample or 

harm individuals. Insufficient data to determine 

potential effects from herbicides. 

MINL. 

Adverse effects to individuals are 

possible, but all species are wideranging, occurring in several states, 

so effects from isolated invasive 

plant treatments are not likely to 

lead to a trend toward federal 

listing. 

Amphibians Manual or mechanical treatments could trample 

some individuals. Applications or accidental 

spills of glyphosate, triclopyr, or 2,4-D could 

harm or kill amphibians. NPE is likely to harm 

amphibians only in an accidental spill (USDA FS 

2003). 

MINL. 

Treatment areas would be very 

small relative to species 

distributions. Riparian weeds are 

usually treated with selective 

methods. Potential remains for 

some adverse effects to individuals. 

Insects Manual, mechanical, and fire treatments could 

trample or harm Mardon skipper larvae. If bees 

are suitable surrogate, worst-case exposure 

exceeds the toxicity index if directly sprayed 

with glyphosate, triclopyr, and 2,4-D. Data is 

insufficient to evaluate risk from NPE. 

Herbicides could kill larval food plants and/or 

adult nectar plants. Effects must be evaluated at 

project level. 

MINL. 

Mardon skipper occurs in Oregon, 

Washington, and California. 

Invasive plant treatments would be 

conducted to protect skipper habitat 

from invasive plants, providing 

long-term benefits to population. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Table 4-46 Potential Effects to Sensitive Species. 

Impact determinations apply to all alternatives. 

Sensitive 

Species Group Potential Impacts Determination 

Mollusks Most species very susceptible to heat and drying 

caused by fire. Exposure to picloram did not 

increase mortality to brown garden snail (Helix 

aspersa). Terrestrial slugs (Deroceras 

reticulatum) can absorb 2,4-D through contact 

with contaminated soil. No other data is 

available for herbicide effects to terrestrial 

mollusks. Must be evaluated at project level to 

determine likelihood of exposure. 

MINL. 

Little overlap between most 

habitats and invasive plant 

occurrences, but specific data is 

lacking. Risk from herbicides 

largely unknown. Risks must be 

further evaluated at the project 

level. 

1 MINL = may impact individuals, but not likely to lead to a trend toward federal listing 

Cumulative Effects 

Several of the sensitive species within the project area have relatively small home ranges, like 

shrews and salamanders for example, so individual animals are not likely to be exposed to 

multiple invasive plant treatment projects. 

For wide-ranging species, like insectivorous birds, bats, ducks, and large mammals, 

cumulative effects are similar to those discussed for wildlife in Chapter 4.4. 

Herbicide use occurs on lands other than National Forest System land. Agricultural, lawn 

care, forest and rangeland improvement, utility corridors, and road rights of way account for 

large amounts of herbicide use. Some of the sensitive species in the project area move long 

distances or migrate, so they can be exposed to herbicides on adjacent lands or along their 

migration routes. 

The small contribution that Forest Service use of herbicide for invasive plant control makes to 

the statewide totals57 for herbicide use indicates that the potential cumulative effect from 

Forest Service actions is very small. Likewise, the relatively small differences between the 

alternatives, in comparison to the total herbicide use within Oregon and Washington, make 

any differences in potential for cumulative effects to sensitive wildlife insignificant. 

 

57 National Center for Food & Agricultural Policy (NCFAP). 1997 Pesticide Use Database. available online at 

www.ncfap.org/database/state/default.asp. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Federally-Listed Fish, Mollusks, and Critical Habitat 

Coordination with the U.S. Fish and Wildlife Service and the National Oceanic and 

Atmospheric Administration - Fisheries Division - has occurred for this EIS. The effects 

determinations made for Essential Fish Habitat (EFH)58, federally listed fish and mollusks 

(Bliss Rapids Snail), are discussed in this section and are further elaborated on in the 

Biological Assessment (BA) for this EIS. For purposes of this EIS, effects to listed aquatic 

species are determined by assuming a worst case scenario, which leads to an adverse affect 

determination based on the possibility of an adverse affect at the project scale. 

Life history information on fish and mollusk species listed as threatened, endangered, or 

proposed under the provisions of the Endangered Species Act are included in a report in the 

project file (“Brief Life History Narratives for Federally Listed and Forest Service Sensitive 

Animals and Some Plants in Region Six”) and in the Fisheries BA. These documents also 

address the effects of non-herbicide treatment methods on PETS species. Because these nonherbicide treatment effects were not the focus of concern, this section will discuss effects of 

herbicide treatment only. 

Additional supporting information for direct and indirect effects to PET species is found in 

the Aquatic Organism section Chapter 4.7.2). Discussions on the likelihood of herbicide 

exposure to aquatic organisms are also covered in Chapter 4.7.2. 

Proposed Standards #15 through #22 relate to herbicide treatment and restoration. Standards 

#18 through #22 can be considered as mitigations to herbicide treatment. Non-herbicide 

treatment and restoration Standards #11 through #14, #17, and #23 were determined to have 

no effects on aquatic listed species because these standards apply to the administrative aspect 

of treating invasive plants and not implementation. 

Because this EIS does not include project-level information, there is not sufficient information 

on how these herbicides will be applied to determine that there would be no effect whatsoever 

on PETS species and their habitat. The primary concern is that herbicides may enter the water 

body and could directly or indirectly impact PETS species as discussed below and in the 

Aquatic Organism section, Chapter 4.7.2. 

The greatest likelihood of effects to PETS species and their habitat is associated with “high 

risk” treatment projects in sensitive areas. High risk projects are defined as projects that are 

 

58 Essential Fish Habitat (EFH) is defined as those waters and substrate necessary to fish for spawning, 

breeding, feeding , or growth to maturity (50CFR 600.10). Essential Fish Habitat includes all streams, lakes, 

ponds, wetlands, tributaries, and other water bodies currently viable and most of the habitat historically 

accessible to these fish. 

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treated with aerial herbicide applications, treated with broadcast herbicide applications (e.g. 

backpack or boom spray), the use of heavy equipment in riparian areas, and indirect treatment 

of water corridors (i.e. ditches) directly feeding streams with federally-listed aquatic species 

or critical habitat. Invasive plant treatment projects that pose a high risk to federally listed 

species will be monitored. 

Standards #15 and #17 are unrelated to changes in on-the-ground activities that would result 

in effects to listed species and their habitat. Standards #18 through #22 provide mitigation 

direction that are intended to avoid, eliminate, or reduce potential effects from implementing 

herbicide-related treatments. Standard #16 was determined to have the potential for direct 

and indirect effects to PETS species and their habitat. However, Standards #18 through #22 

would mitigate these potential effects. The majority of this section will focus on the effects 

from herbicide treatment on listed aquatic species and their habitat via components of 

pathway indicators. 

Direct Effects 

Application of herbicides under all of the alternatives is not expected to result in mortality to 

aquatic PETS species. While the amount of herbicides or chemicals expected to reach water 

are expected to be very low under the Alternative B and the Proposed Action, the Forest 

Service cannot conclude with certainty that the levels of chemicals that could potentially 

reach streams with PETS species and critical habitat will be zero. 

Most direct effects from all of the alternatives on PETS species are likely to be from sublethal herbicide effects, rather than from direct mortality as a result of herbicide exposure. 

Sub-lethal effects are considered under the ESA to constitute “take”, if the sub-lethal effect 

“harms” a listed aquatic species (50 CFR 222.102). The ecological significance of sub-lethal 

effects depends on the degree to which they influence behavior essential to the survival and 

reproductive potential of individual listed aquatic species. Sub-lethal effects are not readily 

apparent. When small changes in the health of individual fish are observed (e.g., a small 

percent change in the activity of a certain enzyme, an increase in oxygen consumption), it 

may not be possible to infer a significant loss of essential behavior patterns of aquatic PETS 

species in the wild. 

Product formulations sometimes include unspecified inactive ingredients and adjuvants with 

unknown toxic effects to listed fish. For example, the combination of POEA surfactant and 

glyphosate has been shown to cause inflammation of gill tissue in fish, and to reduce survival 

rates especially for young fish (Folmar et al, 1979; Servizi, 1987). Roundup is known to have 

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the POEA surfactant and is therefore toxic to fish, while the product Rodeo, which contains 

the same active ingredient (glyphosate), but no surfactants, has very low toxicity. 

The risk of direct effects from drift as a result of “high risk” broadcast spray applications 

(aerial, boom, and backpack) from overspray is likely to occur in small streams and stream 

margins, and small, enclosed water bodies. Higher herbicide concentrations can result in 

smaller streams with limited dilution capacity. Stream margins providing rearing habitat to 

fry and juveniles are often poorly mixed relative to the main stream channel, and high 

herbicide concentrations can result from overspray/drift exposure. Thus, direct exposure of 

stream or lake margins to overspray or drift can result in a high risk potential to vulnerable 

aquatic PETS species life stages. 

Project design and/or mitigations required under Standard #20 will reduce the risk of surface 

water contamination from spray drift. Standard #20 requires that site-specific project design 

use wind speed and direction, nozzle type and size, buffers, and other unspecified factors to 

reduce or eliminate the risk of effects to aquatic PETS species from herbicide exposure 

resulting from spray applications. The site-specific design criteria employed will be specified 

at the project level. 

Indirect Effects 

Indirect effects are analyzed and discussed below by addressing certain components of the 

matrix of pathway indicators and cross-walking those indicators with critical habitat elements 

or primary constituent elements. 

Chemical Toxicity. Herbicides (along with inert ingredients, adjuvants, metabolites, and 

impurities) can indirectly enter surface water through a variety of routes. Plants treated with 

herbicides may release chemicals into the soil via root systems or rinsing during rainfall 

events, treated plant biomass containing slowly decaying herbicides can become incorporated 

with soil organic matter, or overspray onto soil can result in soil contamination. Soil can be 

moved into surface water through wind erosion, soil movement, or leaching. 

The Forest Service risk assessments conducted by Syracuse Environmental Research 

Associates (SERA) include extensive review of the available literature regarding the effects of 

herbicides and herbicide formulations to aquatic species. The concentration resulting in lethal 

effects to fifty percent of fish exposed to an herbicide or herbicide formulation (LC50 value) is 

the most commonly identified toxicity level for each herbicide. The chronic no observed 

effect concentration (NOEC) was identified where data was available, and estimated using a 

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variety of methods when chronic toxicity data was not available. This is explained further in 

the Fisheries BA. 

Effects can include changes in behaviors or body functions that are not directly lethal to the 

aquatic PETS species, but could have reproductive, juvenile to adult survival, or other 

consequences. The most common sub-lethal effect was changes in the size of liver or 

kidneys, the organs primarily responsible for xenobiotic metabolism and excretion. One or 

two herbicides had behavioral effects. In no instance have aquatic PETS species analyzed in 

this EIS been directly tested for these levels of toxicity, so estimated toxicity is extrapolated 

using data from sensitive or closely related fish species or invertebrates. 

Herbicide treatment methods can result in indirect introduction of chemicals to surface water. 

Chemical concentrations, duration of exposure, sensitivity of the species to the chemical 

(which can vary with life stage) all affect the level of toxicity to aquatic PETS species. 

Chemical characteristics such as decay rate and strength of bond to soil particles affect the 

concentration of the chemical in water. Environmental factors such as soil particle size, 

amount of organic matter in the soil, moisture level, and temperature affect decay rate, which 

in turn affects chemical concentrations in water. 

Dissolved Oxygen and Nutrients. Significant herbicide treatment in riparian areas could result 

in increases in nutrient delivery and have possible effects on dissolved oxygen. However, 

treatments are generally not confined to riparian areas and typically do not negatively impact 

significant portions of the total riparian vegetation resulting in a sudden influx of nutrients to 

surface water. 

Herbicides leaching into surface water can result in indirect effects to aquatic PETS species 

via adverse effects to phytoplankton, algae, rooted aquatic macrophytes, and other aquatic 

plants. A significant reduction of primary productivity or aquatic plants and algae could 

decrease oxygen levels and indirectly impact aquatic PETS species and their critical habitat. 

Water Temperature. Depending on site-specific conditions, intensive and extensive herbicide 

treatment immediately adjacent to surface water can result in the loss of enough riparian 

vegetation to affect summer or winter water temperatures. 

Aquatic PETS species have specific needs in term of water temperature, which affects 

metabolism and food requirements. In the summer, increasing water temperatures decreases 

the solubility of dissolved oxygen in water, decreasing dissolved oxygen and affecting aquatic 

PETS species. In the winter in cold climates, riparian vegetation aids in moderating radiant 

heat loss from the stream. 

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Many factors affect water temperature. Herbicidal treatments may likely decrease riparian 

vegetative shading in certain areas thereby increasing the amount of solar radiation striking 

the water resulting in a warming effect. This loss of shade can persist for a year to several 

years, depending on the success of invasive plant treatment, stream size and location, growing 

conditions for the replacement plants, and the density and height of the invasive plants when 

treated. The reason for treatment of invasive plants is to improve ecosystem and riparian 

function by removing invasive plants and supporting the growth of native vegetation. Any 

loss of shade is expected to be temporary, until appropriate vegetation reaches and surpasses 

the height of the invasive plants that were removed. This warming effect would be 

insignificant and short-term and not enough to adversely affect aquatic PETS species and their 

habitat. 

Turbidity and Fine Sediment. Herbicide treatments do not kill invasive plants immediately. 

As treated vegetation dies and loses root strength, soil can be moved into surface water 

through water movement, soil movement, or wind. There would have to be a significant 

amount of vegetation die-off next to the stream in order to significantly increase levels of 

turbidity and fine sediment. 

Instream Habitat and Riparian Structure. Invasive plant treatment in riparian areas is 

intended to change the vegetative composition to restore the structure and function of riparian 

areas. Loss or reduction in riparian vegetation due to treatment of invasive plants is expected 

in the short-term. The length of time before suitable vegetation returns to perform important 

riparian functions will vary considerably across Region Six. Emergent aquatic vegetation can 

be affected indirectly and riparian vegetation can be affected directly by herbicide treatment. 

In general, improved riparian structure and function due to invasive plant treatment will 

benefit listed aquatic species, though there could be localized, short-term effects to their 

habitat. 

Food Resources. Aquatic PETS species are indirectly affected when their food source is 

impacted. Aquatic food chains are dependent on primary production as a source of energy 

within the ecosystem. For aquatic systems, primary production can occur in the water or out 

of the water in riparian areas. Numerous invertebrate species feed directly on primary 

producers through feeding functions such as grazing, scraping, shredding, and collecting. 

Other invertebrate and fish species feed on these invertebrates, which then become food for 

fish or other predators. For example, the Bliss Rapids snail is known to graze on microscopic 

organisms found on the upper most surfaces of rocks. Any impact to the growth or 

availability of these microscopic organisms will ultimately impact the Bliss Rapids snail. 

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Inputs of plant matter and insects are important sources of nutrients and energy in some 

aquatic systems, particularly small, heavily vegetated headwater streams. Changes in the 

composition of riparian vegetation due to invasive plant treatment could potentially cause 

short-term changes in the timing and composition of these food sources. However, these 

changes are expected to favor native food sources and ultimately benefit aquatic PETS 

species. 

The significance of effects to aquatic PETS species is related to the intensity and extent of 

invasive plant treatment in riparian areas. Because aquatic plants are an important food 

source for some aquatic PETS species and their prey, it is important to consider the feeding 

habits of aquatic PETS species when assessing indirect impacts via food resources. For 

example, the feeding habits of the Warner sucker mainly depend on habitat and life history 

stage, with adult suckers becoming more generalized than juveniles. Invertebrates, 

particularly planktonic crustaceans, make up most of the larvae stage diet because of their 

physiology. As the suckers grow, they gradually become generalized benthic feeders on 

diatoms, filamentous algae, and detritus. Any negative impacts to aquatic plants or 

macrophytes will ultimately impact the Warner sucker. 

Chronic and Acute Exposure 

The potential for adverse effects from exposure to herbicides was analyzed using exposure 

estimates in the Forest Service/SERA Risk Assessments and comparing those estimates to 

toxicity thresholds for each herbicide. Toxicity thresholds (or “toxicity indices”) were 

determined using EPA protocol for effects to federally-listed aquatic organisms59. The results 

of the analysis indicate that modeled concentrations of glyphosate, picloram, sethoxydim, 

triclopyr, and 2, 4-D ester exceed the toxicity indices for fish at typical and highest 

application rates. 2,4-D amine does not exceed the toxicity index for any application rate or 

exposure assumption60, Table 4-47. 

 

59 These results differ slightly from the results displayed in Table 4-41 (Chapter 4.7.2) because of differences in 

the protocol used for the calculations. 

60 Details of the analysis can be found in the project files, the Forest Service/ SERA Risk Assessment , and the 

Fisheries Biological Assessment. 

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Table 4-47 Acute Exposure Results for Sensitive Aquatic Organisms - EPA Protocol Chlorsulfuron Clopyralid Dicamba Glyphosate w/o Surfactant Glyphosate with Surfactant Imazapic Imazapyr Metsulfuron Methyl Picloram Sethoxydim Sulfometron Methyl Triclopyr TEA Triclopyr BEE 2,4-D ester 

2,4-D amine 

ACUTE EXPOSURES – short term 

Fish -- -- -- * * -- -- -- * * -- * * * -- 

Aquatic 

inverteb

rates 

-- -- -- -- ♦ -- -- -- -- -- -- -- ♦ -- -- 

Algae * -- -- -- ♦ -- * -- -- ♦ * * * * 

Aquatic 

plants 

* -- -- -- -- ♦ * * ♦ -- * * * * * 

‘—’ Predicted concentrations less than the estimated or measured ‘no observable effect concentration’ (NOEC) 

‘*‘ Predicted concentrations greater than the estimated or measured ‘no observable effect concentration’ at typical 

application rates. 

‘♦’ Predicted concentrations greater than the estimated or measured ‘no observable effect concentration at highest 

allowed application rates only. 

The toxicity metric values (estimated or measured NOEC values) used in the analysis were 

selected as the most likely to protect against acute sub-lethal effects (for a more complete 

explanation, see Fisheries BA). Therefore, exceedence levels shown in Table 4-47 above 

represents at least a greater than discountable risk of acute sub-lethal effects. For aquatic 

species, exposure above the chronic toxicity concentrations is not mathematically possible for 

any of the herbicides modeled. Results for chronic exposures are not shown in the table 

above because predicted concentrations are less than the estimated or measured NOEC for all 

herbicides. 

Proposed Action. Under the Proposed Action, herbicides that could plausibly cause acute 

adverse effects to fish are glyphosate (with and without surfactant), triclopyr (TEA and BEE), 

picloram, and sethoxydim. Predicted concentrations for glyphosate with surfactant are greater 

than the estimated or measured NOEC at the highest allowable application rate for aquatic 

invertebrates and algae. The combination of POEA surfactant and glyphosate has been shown 

to cause inflammation of gill tissue in fish, and to reduce survival rates for juvenile fish 

(Folmar et al, 1979; Servizi, 1987). Folmare (1979) demonstrated that the surfactant POEA is 

actually more toxic to fish than glyphosate. The LOC exceedences for glyphosate without 

surfactant appear to be a function of the high glyphosate application rates, rather than 

glyphosate being more toxic. Thus, the risks associated with glyphosate will depend largely 

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on formulations applied in the vicinity of streams, and application rates and methods specified 

for site-specific projects. 

The exposure scenario modeled in the Forest Service/SERA Risk Assessments probably 

significantly overestimates the risk of acute adverse effects resulting from triclopyr 

application, under the Proposed Action. Standard #16 of the Proposed Action states that 

triclopyr will only be used in spot applications, thus the risk assessment scenario of treating a 

plot of 10 acres at the maximum application rate of 10 lbs. a.e. per acre is likely to be in 

excess of actual use. However, the Garlon IV formulation of triclopyr contains either 

kerosene or diesel fuel, both of which are know to be toxic to fish, and could be a concern. 

Alternative B. Under Alternative B, predicted concentrations for clopyralid for any of the 

aquatic groups tested were less than the estimated or measured NOEC. Herbicides that 

resulted in predicted concentrations greater than the estimated or measured NOEC at typical 

application rates to fish are glyphosate (with and without surfactant), triclopyr (TEA and 

BEE), and sethoxydim. Glyphosate with surfactant also exceeded the NOEC at the highest 

allowable application rate for aquatic invertebrates and algae. The same discussion related to 

these specific herbicides under the Proposed Action applies. The exposure scenario modeled 

in the Forest Service/SERA Risk Assessments are overestimated for acute adverse affects 

from triclopyr application. Adverse effects are unlikely because treating 10 acres at the 

maximum application rate of 10 lbs. a.e. per acre is likely to be in excess of actual use. 

Alternative D. In addition to the results for all herbicides mentioned in the Proposed Action 

and Alternative B, predicted concentrations for dicambia for any of the aquatic groups were 

less than the estimated or measured NOEC. For aquatic plants and algae, 2,4-D ester and 2,4-

D amine results in prediction concentrations greater than the estimated or measured NOEC at 

typical application rates. 

No Action. No Action includes the use of five herbicides - glyphosate, triclopyr, dicamba, 

picloram and 2,4-D (a tool of last resort). Results of their continued use would be similar to 

what was identified for each herbicide under the above alternatives. 

Effects to Critical Habitat 

Under current Forest Service management direction (NWFP Aquatic Conservation Strategy 

(ACS) and Pacfish/Infish) and the standards proposed in the action alternatives, site-specific 

projects cannot have a negative impact, in the long term, on riparian-dependent resources or 

ecological processes at the watershed scale. Each site-specific project must maintain or 

restore the physical and biological processes required by riparian dependent resources at the 

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watershed scale or broader to comply with ACS and Pacfish/Infish. Management direction 

prohibits activities in riparian areas that retard or prevent attainment of these objectives. 

These objectives address all of the physical and biological features that are essential to the 

conservation of bull trout (e.g. primary constituent elements) or anadromous fish (e.g. 

essential features). 

The potential, site-specific effects from the implementation of invasive plant projects on 

critical habitat will be evaluated at the project level at the time specific actions are proposed. 

Currently, the FWS and/or NOAAF Matrix of Pathways and Indicators are used in every 

7(a)(2) consultation to assess the effects of a proposed action on habitat important to listed 

fish species. The habitat indicators in the Matrix of Pathways and Indicators are nearly 

identical to the physical and biological features addressed by the primary constituent elements 

(PCEs) and essential features of critical habitat. 

Although, some PCEs and essential features are not directly identified in the “Matrices,” the 

existing indicators indirectly address them. All of the PCEs or essential features have been 

and will continue to be indirectly or directly assessed using the “Matrices” or alternative 

analysis tools. 

The implementation of mitigation Standards 18-22, in addition to project level mitigation 

measures will reduce adverse affects to listed species’ habitats during herbicide and nonherbicide treatment methods to a very minimum, as discussed in the Aquatic Organism 

section, Chapter 4.7.2. 

Water Quality Indicators. Changes in water temperature resulting from herbicide use to 

control invasive plants would be negligible to non-existent. Invasive plants provide little to 

no shade to streams, and the risk for adverse affects to native vegetation is low with backpack 

or hand operated sprayers. In those rare instances where solid patches of riparian vegetation 

is removed by herbicide treatment, short-term, increases in surface erosion may result. These 

impacts will likely not be significant and will diminish as vegetation re-establishes treated 

areas. No large-scale changes in vegetation cover or stand structure (e.g. timber to grass) will 

result from the herbicide treatment proposed in this EIS. Herbicide treatment of invasive 

plants is expected to result in a low risk of water contamination because of the new Forest 

Plan standards included under all of the action alternatives, and the additional site-specific 

mitigations developed at the project level. Mitigations developed at the project level will 

apply Standard #19, which provides direction for reducing or eliminating adverse affects: 

“...use site-specific soil characteristics, proximity to surface water and local water table depth 

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to determine herbicide formulation, size of buffers needed, and application method and 

timing. Only those herbicides and herbicide mixtures registered for aquatic use will be 

considered when evaluating herbicide use near streams or surface water.” 

Habitat Access Indicators. The application of herbicides would not create physical barriers to 

aquatic PETS species. 

Habitat Element Indicators. Herbicide use would not affect substrate, large woody debris, 

pool quality, off-channel habitat, and refugia. Large trees that provide shade and large wood 

would not be impacted by the use of herbicides as proposed under the alternatives. 

Channel Condition Indicators. Ground based herbicide application would result in reduction 

of invasive plants within riparian areas and along stream banks. No adverse impacts to stream 

bank stability are expected. Reduction of invasive plants along stream banks and riparian 

areas will benefit native plant species and result in improved stream bank stability and 

riparian condition in the long-term. 

Flow/Hydrology Indicators. Chemical treatment of invasive plants is expected to result in no 

measurable effect to peak/base flow or water yield of watersheds. 

Watershed Condition Indicators. No new roads or watershed scale disturbances will result 

from the use of herbicides to treat invasive plants. Invasive and noxious plants are a threat to 

overall watershed ecological condition. Long-term beneficial effects from the reduction of 

invasive plants in riparian areas, wetlands, and streams and subsequent increases in desirable 

vegetation will result in improved watershed conditions. 

Conclusion 

Allowing the use of herbicides for invasive plant treatment and resulting site-specific projects 

may cause some short- and long-term adverse effects on aquatic PETS species even though 

the projects will eventually provide important long-term benefits. Most of these potential 

adverse effects will be eliminated or minimized through application of current management 

direction (e.g. ACS, Pacfish/Infish) and the new Forest Plan standards proposed in this EIS. 

Effect determinations at the project level are expected to vary. Some projects conducted 

according to the standards proposed in this EIS are not likely to adversely affect aquatic PETS 

species and their habitat because they will avoid the addition of significant amounts of 

sediment into aquatic habitats, and minimize the introduction of herbicides into these same 

habitats. Toxic levels of herbicides are unlikely to enter streams or lakes (i.e., noxious weeds 

are removed by mechanical means or with herbicides applied with hand sprayers at a 

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sufficient distance from the water body). For example, application of herbicides at the lowest 

application rate consistent with the intended purpose using spot application with a lowpressure backpack sprayer away from the water body is not likely to result in an adverse 

affect to aquatic PETS species. 

Activities under all of the action alternatives include bank stabilization or shaping following 

the removal of invasive plants, or preparation of planting areas. These activities could have 

direct or indirect, negative short-term impacts to aquatic PETS species during critical life 

stages such as migration, breeding/spawning, and juvenile rearing. Effects may result in 

disturbance (i.e., physical, behavioral, or physiological stressors), displacement, or alteration 

of habitats. Such impacts include physical interaction with eggs, juveniles, adults, and shortterm sedimentation during any near stream work associated with invasive plant treatment and 

removal. 

Effects on aquatic PETS species from all invasive plant treatments would be evaluated more 

precisely at the project scale. Treatments would not be expected to remove or degrade 

suitable habitat for any listed aquatic species because (1) suitable habitat would not be 

considered a target for elimination, and (2) management direction in all alternatives require 

treatments to avoid or reduce effects to species. 

In terms of effects to aquatic PETS species, there are no substantial differences between the 

alternatives. Herbicide exposure to aquatic PETS species is possible in all alternatives, 

though concentrations of concern are unlikely because Standards #19 and #20 provide general 

direction on how to mitigate effects. Fine sediment introduction to streams due to soil 

disturbance or temporary loss of vegetative cover, is the most likely effect of any invasive 

plant treatment or restoration method. The total number of acres treated in riparian areas near 

listed aquatic species is likely to be very low for all alternatives, and projects can be designed 

to avoid these effects as required by Standard #20. Therefore, the minor differences in acres 

treated by different methods would not result in any substantial differences in potential effects 

to listed species between the alternatives. 

The following Table 4-48 summarizes the potential effects to each listed aquatic species. The 

determination for all listed fish is either “not likely to adversely affect” (NLAA) or “likely to 

adversely affect” (LAA) because some projects could be conducted in riparian areas adjacent 

to habitat for listed aquatic species, and the uncertainty that all adverse effects can be 

mitigated for all projects. At the project scale, potential effects will be more precisely 

analyzed and adverse effects will be avoided or minimized as required by Standards #19 and 

#20. 

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Table 4-48 Potential Effects to Proposed, Endangered, and Threatened Aquatic 

Species. 

Species ESA Status ESA 

Determination 

Snake River Sockeye Salmon Endangered LAA 

Upper Columbia River Spring Chinook Endangered LAA 

Upper Columbia River Steelhead Endangered LAA 

Lost River Sucker Endangered LAA 

Shortnose Sucker Endangered LAA 

Oregon Chub Endangered LAA 

Southern Oregon/Northern California Coast Coho Salmon Threatened LAA 

Snake River Spring/Summer Chinook Threatened LAA 

Snake River Fall Chinook Threatened LAA 

Puget Sound Chinook Salmon Threatened LAA 

Upper Willamette River Chinook Threatened LAA 

Lower Columbia River Chinook Threatened LAA 

Snake River Steelhead Trout Threatened LAA 

Lower Columbia River Steelhead Threatened LAA 

Mid Columbia River Steelhead Threatened LAA 

Warner Sucker Threatened NLAA 

Hood Canal Chum Salmon Threatened LAA 

Columbia River Chum Salmon Threatened LAA 

Klamath River Bull Trout Threatened LAA 

Columbia River Bull Trout Threatened LAA 

Coastal/Puget Sound Bull Trout Threatened LAA 

Bliss Rapids Snail Threatened LAA 

Oregon Coast Coho Proposed NLJ 

Southwest Washington/Lower Columbia Coho Proposed NLJ 

NLJ = Not likely jeopardize the continued existence of 

Cumulative Effects 

Cumulative effects were discussed for aquatic organisms in Chapter 4.7.2. Chinook salmon, 

steelhead trout, coho salmon, and chum salmon migrate across multiple ownership 

boundaries. The Bliss Rapids Snail has a relatively small home range, so they are not likely 

to be exposed to multiple invasive plant treatment projects. All other endangered or 

threatened species move over shorter distances, and may cross ownership boundaries. Most, 

but not all, streams on National Forest System lands are upstream from other sources of 

herbicides or sediment. Migration and exposure to water that flows through other ownerships 

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increase the likelihood that fish would be exposed to multiple uses of herbicide and/or sources 

of sediment. 

It is unlikely that herbicide exposure from invasive plant projects would add to or accumulate 

with past or future herbicide exposures on other projects because the herbicides considered in 

this EIS do not bioaccumulate. The alternatives considered do not include the use of any 

other types of pesticides, but the herbicide triclopyr and the insecticide chlorpyrifos share a 

common metabolite TCP, that is toxic to aquatic organisms61.

 Thus, the use of triclopyr could 

add to TCP exposure resulting from the use of chlorpyrifos. Another example of a potential 

cumulative effect is from hexachlorobenzene, a ubiquitous industrial pollutant, which is found 

in both picloram and clopyralid. While the amounts of hexachlorobenzene added to the 

environment from Forest Service use of picloram and clopyralid do not represent a substantial 

addition in comparison to existing background levels (SERA, 2003-picloram; 2003-

clopyralid), it could be considered a cumulative effect. 

Herbicide use for invasive plant treatment, within the project area, is insignificant in 

comparison to total herbicide use on other ownerships and for other purposes (NCFAP, 1998) 

(Chapter 4.1.1). 

If effects to aquatic PETS species do occur, they will most likely be sub-lethal rather than 

direct mortality from herbicide exposure, with the exception of an accidental spill. Sub-lethal 

effects include changes in behavior that render ESA species susceptible to predation, 

compromised immune system, and effects to organs. The ultimate consequence of many 

“sub-lethal” effects to juveniles may not manifest until later in the life cycle (smoltification, 

ocean survival, reproductive success, etc). 

Most of the potential sublethal effects to aquatic PETS species from the herbicides and 

adjuvants proposed for use have not been investigated in regards to toxicological endpoints 

that are generally considered important to the overall health and fitness of aquatic PETS 

species. These toxicological endpoints are defined as: 

• Direct and indirect mortality at any life history stage 

• Increase or decrease in growth 

• Changes in reproductive behavior 

• Reduction in number of eggs produced, eggs fertilized, or eggs hatched 

 

61 The combined risk from chlorpyrifos and triclopyr sources of TCP was considered quantitatively for fish in 

the triclopyr risk assessment (SERA, 2003-tricloypr). Combined application of chlorpyrifos and triclopyr did 

not result in concentrations of TCP that were toxic to fish (SERA, 2003-triclopyr). 

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• Developmental abnormalities, including behavioral deficits or physical deformities 

• Reduced ability to osmoregulate or adapt to salinity gradients 

• Reduced ability to tolerate shift in other environmental variables 

• Increased susceptibility to disease and/or predation 

• Changes in migratory behavior 

To address uncertainties relating to sublethal effects, project-level planning documents should 

incorporate additional mitigation or conservation measures. 

Implementation of any of the alternatives may produce actions that will either have no effect 

or some adverse affect on ESA listed aquatic species. However, the ultimate effect of 

implementing any of the alternatives is likely to be a benefit to aquatic species by restoring 

native vegetation and thereby restoring riparian vegetative structure and ecosystem function. 

Consequently, most potential adverse effects are expected to be short-term and serve to 

improve the long-term viability of listed species. 

Forest Service Sensitive Aquatic and Commercially Important Fish Species 

Direct, Indirect and Cumulative Effects 

Effects on sensitive and commercially important fish species are similar to those discussed 

under Aquatic Organism (Chapter 4.7.2) and Federally-listed Aquatic Species (Chapter 4.7.3). 

Table 4-49 summarizes the potential effects to each sensitive species. 

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Table 4-49 Potential Effects to Sensitive Fish Species 

Sensitive Species Determination 

Pit-Klamath Brook Lamprey MINL* 

Goose Lake Lamprey MINL 

Klamath River Lamprey NE* 

Malheur Mottled Sculpin MINL 

Margined Sculpin MINL 

Pit Sculpin MINL 

Slender Sculpin MINL 

Olympic Mud Minnow MINL 

Pit Roach MINL 

Pygmy Whitefish MINL 

Oregon Lakes Tui Chub NE* 

Goose Lake Tui Chub MINL 

Blue Chub MINL 

Umpqua Chub MINL 

Goose Lake Sucker MINL 

Klamath Largescale Sucker MINL 

Salish Sucker NE* 

Chinook Salmon - WA Coast MINL 

Chinook Salmon - OR Coast MINL 

Chinook Salmon - Southern OR/Northern CA MINL 

Chinook Salmon - Mid-Columbia Spring Run MINL 

Chinook Salmon - Deschutes River Summer/Fall Run MINL 

Chum Salmon- Puget Sound MINL 

Chum Salmon-Pacific Coast MINL 

Coho Salmon - Puget Sound MINL 

Sockeye Salmon - Lake Pleasant MINL 

Sockeye Salmon - Quinalt Lake MINL 

Sockeye Salmon - Baker River MINL 

Steelhead Trout - Oregon Coast MINL 

Steelhead Trout - Klamath Mountain Province MINL 

Coastal Cutthroat Trout - Puget Sound MINL 

Coastal Cutthroat Trout-Olympic Peninsula MINL 

Coastal Cutthroat Trout - OR Coast MINL 

Coastal Cutthroat Trout - Southern OR/CA Coasts MINL 

Westslope Cutthroat Trout MINL 

Interior Redband Trout MINL 

Umpqua Dace MINL 

Klamath pebblesnail MINL 

tall pebblesnail MINL 

Klamath Rim pebblesnail MINL 

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Table 4-49 Potential Effects to Sensitive Fish Species 

Sensitive Species Determination 

basalt juga MINL 

Columbia duskysnail MINL 

Washington duskysnail MINL 

Sinitsin rams-horn MINL 

MINL = May impact individuals, not likely to lead to a trend toward Federal Listing. 

* NE = These species are not believed to be present on any National Forests in Region Six. 

Magnuson-Stevens Fishery Conservation and Management Act 

The Magnuson-Stevens Fishery Conservation and Management Act (MSA), as amended by 

the Sustainable Fisheries Act of 1996 (Public Law 104-267), established procedures designed 

to identify, conserve, and enhance essential fish habitat (EFH) for those species regulated 

under a Federal fisheries management plan. 

The objective of this EFH assessment is to determine whether or not any of the action 

alternatives “may adversely affect” designated EFH for relevant commercially, federallymanaged fisheries species within the proposed action area. 

Identification of EFH. Pursuant to the MSA the Pacific Fisheries Management Council 

(PFMC) has designated EFH for federally managed fisheries within the waters of 

Washington, Oregon, and California. Designated EFH for groundfish and coastal pelagic 

species encompasses all waters from the mean high water line, and upriver extent of saltwater 

intrusion in river mouths, along the coasts of Washington, Oregon and California, seaward to 

the boundary of the U.S. exclusive economic zone (370.4 km)(PFMC, 1998, 1998a). 

Freshwater EFH for Pacific salmon includes all those streams, lakes, ponds, wetlands, and 

other water bodies currently, or historically accessible to salmon in Washington, Oregon, 

Idaho, and California, except areas upstream of certain impassable artificial barriers (as 

identified by the PFMC 1999), and longstanding, naturally-impassable barriers (i.e., natural 

waterfalls in existence for several hundred years)(PFMC, 1999). In estuarine and marine 

areas, designated salmon EFH extends from the nearshore and tidal submerged environments 

within state territorial waters out to the full extent of the exclusive economic zone (370.4 km) 

offshore of Washington, Oregon, and California north of Point Conception to the Canadian 

border (PFMC, 1999). 

Detailed descriptions and identifications of EFH are contained in the fishery management 

plans for groundfish (PFMC, 1998), coastal pelagic species (PFMC, 1998a), and Pacific 

salmon (PFMC, 1999). 

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Effects 

As described in detail in the Fisheries BA and the Aquatic Organism section (Chapter 4.7.2), 

activities under all of the alternatives may result in short-term adverse effects to a variety of 

habitat parameters. The assessment of potential adverse effects from elements of the 

alternatives on EFH is based on information in Section 5.0 of the Fisheries BA. Essential fish 

habitat could be impacted in the same manner as critical habitat. 

Most of these potential short-term adverse effects will be avoided through the incorporation of 

Standards #18 through #22. Potential effects on habitat include: 

• Temporary loss of riparian function in areas under heavy mechanical treatment. 

• Short-term increases in turbidity pursuant to manual and mechanical treatment 

activities. 

• Potential introduction of herbicides into water bodies through atmospheric deposition, 

spray drift, surface water runoff, percolation, groundwater contamination, and direct 

application. 

Conclusion 

All alternatives are expected to adversely affect EFH for Pacific salmon species listed in 

Table 4-50. These adverse effects, however, will be short-term in nature and avoided or 

minimized to the extent possible through application of Standards #18 through #22 and 

additional mitigations at the project scale. The long-term effects of any of the alternatives 

will be to improve essential fish habitat throughout Region Six. 

Table 4-50 Potential Effects to Commercially Important Fish Species 

Species Magnuson-Stevens EFH Determination 

Upper Columbia River Spring Chinook May Adversely Affect Habitat 

Southern Oregon/Northern California Coast Coho Salmon May Adversely Affect Habitat 

Southwest Washington/Lower Columbia Coho May Adversely Affect Habitat 

Oregon Coast Coho May Adversely Affect Habitat 

Snake River Spring/Summer Chinook May Adversely Affect Habitat 

Snake River Fall Chinook May Adversely Affect Habitat 

Puget Sound Chinook Salmon May Adversely Affect Habitat 

Upper Willamette River Chinook May Adversely Affect Habitat 

Lower Columbia River Chinook May Adversely Affect Habitat 

Puget Sound Pink Salmon May Adversely Affect Habitat 

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4.7.4 Environmental Justice and Tribal/Treaty Rights 

Executive Order 12898 ordered federal agencies to identify and address the issue of 

environmental justice (i.e., adverse human health and environmental effects of agency 

programs that disproportionately impact minority and low income populations). Executive 

Order 12898 also directs agencies to consider patterns of subsistence hunting and fishing 

when an agency action may affect fish and wildlife. Such “Attention to minority and lowincome communities and the natural resource upon which they depend is necessary because 

actions that adequately protect the general population may not always protect discrete 

segments of the population” (Hill and Targ, 2001). 

For the scale of this analysis disproportionate impacts of treatments to minority and low 

income populations are difficult to identify and quantify. Such impacts will need to be 

reconsidered at district, forest, community or other relevant site-specific levels as projects that 

tier to this EIS go through relevant environmental analysis. 

American Indians and Hispanics are groups that may be disproportionately affected by the 

standards proposed in the action alternatives. American Indian tribes may be 

disproportionately affected because they are dependent on native plants for cultural and 

traditional uses and because they may consume more fish (that could be contaminated with 

herbicides) than the general public (see Human Health and safety effects). Hispanics may be 

more likely, than the general population, to be injured during manual treatments or by 

exposure to chemical treatments, because they may be disproportionately represented on some 

work crews (see Human Health and Safety Effects). Hispanics are a growing population in 

Region Six and will need to be considered in future project planning. Other 

ethnic/socioeconomic groups may be disproportionately affected by the standards proposed in 

the action alternatives, however at the Regional scale, these groups and effects are not 

reasonably identifiable. Examples of other affected or perceived to be affected groups may 

include those recreating on National Forest System lands, those gathering and using 

mushrooms, beargrass, and other ethnically related forest products and those who hunt, fish or 

ingest wildlife or fish harvested on or near National Forest System lands. For instance, 

harvesters of matsutake mushrooms represent a diverse group of often mobile and lowincome harvesters. Members of the Crescent Lake Mushroom Monitoring Project have 

expressed interest in project level planning that will tier to this EIS. 

No significant, discernible differences between alternatives relative to environmental justice 

were found at the Regional scale. Environmental justice issues must be further analyzed 

through NEPA related analyses at the site-specific level before projects related to this 

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document are undertaken. Environmental justice issues will be much more reasonably 

identifiable, and changes to projects made (plans, mitigation, extended consultation, etc.) at 

the site-specific level. 

Members and/or decision makers of the Native American groups listed in Chapter 3 were sent 

a scoping letter (Appendix A) seeking their input for the preparation of this EIS. The Bureau 

of Indian Affairs also received the tribal comment scoping letter. In total 107 tribal scoping 

letters were sent and personal contact was pursued with each tribe. 

Scoping comments expressed overwhelming support for region-wide action to reduce and 

control of invasive plants. The letters expressed a need to address invasive plants on forest 

lands, as invasive plants have (or may in the future) negatively impacted treaty rights of 

Native Americans. Impacts to cultural plants were of specific concern. Comments expressed 

support for components of some of the alternatives including: commitment to adaptive 

management, inventory and early detection, coordination/partnerships with neighboring land 

owners and managers, and restricted road building, road maintenance, and access. Concerns, 

specifically related to environmental justice of treatments were focused on water quality; 

namely, that invasive plant treatments should not degrade or compromise water quality for 

salmon and steelhead fisheries, which are an important part of Native American tradition and 

a major source of food and income for many Native Americans in the Pacific Northwest and 

elsewhere. 

None of the alternatives, including No Action, would change, restrict or abrogate treaty 

reserved or Executive Order rights. However, implementation of the standards may affect 

natural resources on which the tribes depend. Consultation with tribal governments would 

occur during site-specific project planning in all alternatives, so that adverse effects to 

traditional uses and treaty and other rights are avoided or appropriately mitigated. 

Invasive plant treatments may also have the potential to affect traditional cultural properties or 

Indian gravesites. Compliance with the National Historic Preservation Act (NHPA) and the 

Native American Graves Protection and Repatriation Act is accomplished through 

consultation with the respective tribe or elders or religious leaders. Consultation with tribal 

elders and spiritual leaders takes place early in the planning process. Consistency with the 

American Indian Religious Freedom Act must be discussed in project environmental 

documents. Individual Indian interests as provided for in NHPA are a separate from the tribal 

consultation process. Where individual interests may be affected, such as traditional cultural 

properties, the agency must consider appropriate mitigation or provide for protection 

measures. 

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Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

Consultation with tribes and consideration about the potential for disproportionate effects is 

required under current direction. Worker health and safety standards are also common to all 

alternatives. 

4.8 Specifically Required Disclosures 

4.8.1 Adverse Environmental Effects that Cannot be Avoided 

Table 4-51 below summarizes the unavoidable potential adverse effects to environmental and 

human health associated with the invasive plant management alternatives considered in this 

EIS. Significant environmental impact would not be expected under reasonably foreseeable 

circumstances, as the standards applied to projects under all alternatives are expected to be 

effective. However, some potential effects are not, or cannot be fully mitigated. An 

accidental herbicide spill, for instance, may kill non-target species even though a spill plan is 

in place. 

All reasonable mitigation measures appropriate to this regional scale were considered in the 

development of the standards. Additional mitigation at this scale would unreasonably hamper 

land manager’s ability to treat invasive plants and meet desired conditions, goals and 

objectives. 

Table 4-48 focuses on adverse effects, the numerous beneficial effects of the alternatives 

(such as reduced spread of invasive plants) are not evaluated here. 

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Table 4-51 Adverse Effects that Cannot be Avoided 

Forest Service In

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Adverse Effect Magnitude of Effect without Additional Mitigation 

Herbicide Effects on Non-target Species and Fungi (Chapter 4.3) 

Herbicides have the potential to shift species composition and reduce diversity of native plant communities, as less herbicide-tolerant species are replaced by more herbicidetolerant species. Alternative D has the highest potential to harm non-target plants and 

native plant communities. Under both No Action and Alternative D, native plant families affected by these herbicides could be harmed, decreasing their dominance. Healthy native plant communities would continue to decrease in acreage, especially in highly susceptible plant communities where difficult-to-treat species, including sites with culturally important plants. Adverse effects would most likely be localized and short term, although an accidental spill could result in more intense effects (greater number or extent of non-target plants and fungi affected). 

At the project scale, undchoices can be made to 

potentially cause adversspecies. Short-term advbe offset by the long-terProjects that follow inteprinciples and adhere to Proposed Action and Aavoid adverse effects to fungi. 

Herbicide effects on pollinators (Chapter 4.3.3) 

Plants that are dependent on a particular insect for pollination may experience a decrease in reproductive capabilities if their pollinator is impacted by herbicides. All 

alternatives allow herbicide use that at maximum label rates could harm honeybees. The active ingredients used in the Proposed Action and Alternative B are not expected to have toxic effects when directly sprayed on honeybees at the typical Forest Service 

application rate. 2-4,D, which is approved in No Action and Alternative D could affect pollinators at the typical Forest Service application rate. Adverse effects would most likely be localized and short term, although an accidental spill could result in more intense effects (more honeybees killed). 

Follow standards that aalternative. Develop m

to reduce effect of herbFor instance, certain hespecific areas or times othese non-target plants more specific applicatioAt the project scale, undchoices can be made to potentially cause advers

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Table 4-51 Adverse Effects that Cannot be Avoided 

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Adverse Effect Magnitude of Effect without Additional Mitigation 

Herbicide Effects on wildlife and Amphibians (Chapter 4.4) 

Birds or mammals that eat grass or insects are most susceptible to harm (death, illness or other adverse effect to individual animals) from herbicides. Alternative D poses the 

highest potential risk to wildlife from herbicides. In contrast, Alternative B poses the lowest potential risk to wildlife from herbicides. The management direction included in all alternatives (including No Action), as well as environmental conditions and animal behavior, would tend to minimize the magnitude of actual impacts. The Proposed Action represents a more than a threefold increase in higher risk acres compared to Alternative B. However, in relation to the total acres of habitat available for insect and vegetation-eating birds and mammals within the project area (24.9 million acres on National Forest Land), and the wide distributions of most of their populations, the estimated herbicide use under the Proposed Action represents a negligible risk to wildlife on a regional scale. Adverse effects would most likely be localized and short term, although an accidental spill could result in more animals affected over a larger area. 

Follow standards that aalternative. Develop m

scale. At the project scale, choscenarios that could cauinstance, certain chemicspecific areas or times ograss-eaters or amphibiterm adverse effects wolong-term benefits to ththeir habitat from loss d

Herbicide Effects on Human Health (Chapter 4.5) 

Invasive plant treatments may result in risks to human health, including contamination of drinking water. Possible health effects may include short-term and long-term 

adverse effects. Short-term effects may include nausea, headache, dizziness, eye or skin irritation, and coughing. Long-term effects may include cancer, reproductive, endocrine, immunological, neurological effects; and genetic mutations. Workers and the public may be exposed to herbicides. Workers are more likely to be exposed to herbicides, and risk assessments consider the exposure rates likely for workers. Workers include applicators, supervisors, and other personnel directly involved in the application of herbicides. The public includes non-project forestry workers, forest visitors or nearby residents who could be exposed through the drift of herbicide spray droplets, through contact with sprayed vegetation, or by eating, or placing in the mouth, contaminated food items or other plant materials, such as berries or shoots growing in or near forests, by eating game or fish containing herbicide residues, or by drinking water that contains such residues. One herbicide exposure scenario exceeds the “reference dose” for drinking stream water contaminated by runoff/leaching from an adjacent treated area for any herbicide. 

Decision-makers would implement mitigation m

treatment projects. A pwould be required in aluse of streamside buffeequipment for applicatoareas are all examples oto workers and the publOccupational Health an(OSHA) standards, alonand manufacturers’ recopotential exposure and No mitigation measures eliminate risks. No additional mitigatioeliminate risk to human 

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Table 4-51 Adverse Effects that Cannot be Avoided 

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Adverse Effect Magnitude of Effect without Additional Mitigation 

Alternative B is considered the alternative with the overall least risk of herbiciderelated health effects to workers and to the public. The only differences among Alternative B, No Action, and the Proposed Action, lie in potential risks associated with Worst-case scenarios. For typical Forest Service invasive plant treatment practices, No Action B and Proposed Action are essentially equal. No significant health effects to workers, nor to the public from invasive plant treatment would be expected. For all application rates, both typical and maximum exposure assumptions, Alternative D has many more exposure scenarios that exceed EPA target exposure levels than any other alternative. Alternative D also has many more worker, and public exposure scenarios that exceed EPA target levels by a factor of greater than ten. Adverse effects to people would most likely be localized and short term, although an accidental spill could result in greater harm, especially to workers. 

herbicide use, with the use at all. At the project scale, chochemical exposures tha

Effects of Manual Labor on Workers (Chapter 4.5) 

Worker injuries associated with invasive plant treatments vary from minor cuts, sprains, 

bruises, and abrasions to major arterial bleeding, compound bone fractures, serious brain concussions, and death. Workers are subject to heat-related illness or hypothermia when working in extreme weather conditions, and may incur musculoskeletal injuries related to improper body mechanics. Risk to workers is directly 

correlated with acres of manual treatment; which range from 8,600 acres per year in Alternative D to over 44, 000 acres per year under Alternative B. 

Compliance with OccupAdministration (OSHA

agency, industry and mrecommendations reducand risk of injury to womeasures are known to risk to workers is inhereWorkers on Forest ServOSHA standards. 

Relative Costs (Chapter 4.6.2) 

Alternative B has the potential adverse effect of increasing average cost of treatments 

and reducing the acreage that could be treated in a given year. 

Cost-effectiveness wouproject scale so that trea

alternatives are done as 

Effect of Prevention Standard 1 on land users and uses (Chapter (4.6.3) 

Costs for planning management of timber, other vegetation, road, livestock grazing, fire, fuels, recreation, and minerals and mining programs and projects increase under 

this standard in all action alternatives, especially Alternative B. Uses and outputs would tend to decline, but the extent is considered very limited and not measurable. 

For all alternatives, flexor intensity of land use 

minimize adverse effecfurther mitigation neede

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Table 4-51 Adverse Effects that Cannot be Avoided 

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Adverse Effect Magnitude of Effect without Additional Mitigation 

Effect of Prevention Standard 2 on land users and uses (Chapter 4.6.3) 

Implementation of this standard increases management costs for timber, other vegetation management, roads, livestock grazing, fire, fuels, recreation, and minerals 

and mining programs and projects. Under Alternative B, this standard also results in increased initial costs to obtain or develop mobile washing stations. Until such stations are available, this standard in Alternative B may not be operationally feasible. 

No reasonable way to ebusiness. If Alternative 

washing stations would standard feasible. No fu

Effect of Prevention Standard 4 on land users and uses (Chapter (4.6.3) 

Weed free feed requirements can increase the cost of using pack stock because weed 

free feed is generally more expensive to purchase and distribution locations for weed free feed are limited, potentially resulting in additional purchase, travel and transportation costs to the user. The Proposed Action requires weed free feed on about 2.1 million additional acres when compared to No Action or Alternative D. Alternative B expands the weed free feed requirement to all 24.9 million acres of National Forest lands in Region Six. 

Enforcement of weed fr

standard would be phascertification processes areasonably available. No further mitigation n

Effect of Prevention Standard 5 on land users and uses (Chapter (4.6.3) 

Applies solely to Alternative B. Vegetation management projects could cost more, or acres of accomplishment could be reduced, but adjustments may be made at the 

regional scale (e.g. overall sale size increased to maintain board feet output) to minimize the actual effects. Fire and fuels management programs are affected by this standard, and in extreme cases, applying the standard results in less effective fuels treatments and increased risk for wildfire damage. Implementation of this standard potentially reduces the ability of the Forest Service to appropriately respond to changing fire condition classes and may conflict with achieving the goals of the Healthy Forests Restoration Act of 2003. 

At the project scale, mideveloped that reduce c

standard and other vegeand objectives. No furt

Effect of Prevention Standard 6 on land users and uses (Chapter (4.6.3) 

Some limitations on livestock grazing, including changes in grazing locations, timing, intensity, and outputs may occur. The extent of the effect is determined by multiple 

factors that could not be predicted at the regional scale. Changes in livestock movement patterns that require additional labor or may reduce outputs for certain allotments. Alterations to season of use (length, turn-on, turn-off, etc.) and intensity of use that could reduce outputs. Resting of pastures resulting in reduction of livestock use and output. Retirement of grazing allotments directly reducing the number of livestock (commonly measured by Animal Unit Months or AUMs) permitted on National Forest lands. 

At the project scale, mideveloped that reduce c

standard and livestock omitigation needed. 

Effect of Prevention 

All alternatives increase costs of rock source development. Under Alternative B, this 

cost is highest due to the requirement to inspect source sites annually. 

No reasonable way to ebusiness. No further mi

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Table 4-51 Adverse Effects that Cannot be Avoided 

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Adverse Effect Magnitude of Effect without Additional Mitigation 

Standard 7 on land users and uses (Chapter 4.6.3) Effect of Prevention Standard 8 on land users and uses (Chapter 4.6.3) 

The additional work estimated to result from this standard in all alternatives is nearly a one percent increase in road maintenance costs. 

No reasonable way to ebusiness. No further mi

Effect of Prevention Standard 9 and 10 on land users and uses (Chapter 4.6.3) 

Implementation of this standard would likely result in more road closures than proposed under current management. As roads are closed or decommissioned, public access is 

decreased. People have expressed concern about the effects of road closure, including: making recreation areas inaccessible or less accessible, restricting access to areas for people with disabilities, reducing dispersed recreation opportunities, reduced fire suppression access, and increased costs of land use and management. The extent of these effects depends on the number of roads closed due to this standard, which cannot be quantified at the regional scale. 

Road closures would be travel management proj

Effects on land users wextent possible. At the pmade to minimize effecpeople with disabilitiesopportunities, fire suppland use and manageme

Herbicide Effects on Soil Productivity (Chapter (4.7.1) 

Picloram, applied at typical rates, may affect microbial metabolism, though detectable 

effects to soil productivity are not expected. Other herbicides have been shown to affect soil microorganisms for a few days. 

Applied thoughtfully, hbenefits while minimizi

organisms. All action alternatives ia long-term strategy for invasive plants, which nprotecting or improving conditions for soil micr

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Table 4-51 Adverse Effects that Cannot be Avoided 

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Adverse Effect Magnitude of Effect without Additional Mitigation 

Herbicide Effects on Aquatic Organisms (Chapter 4.7.2) 

Herbicides have direct effects on algae and aquatic vascular plants (Anton, et al. 1994; Roshon, et al. 1999). Since these form a food supply, habitat, or both for aquatic 

organisms, this toxicity may be problematic. Glyphosate does degrade relatively quickly and for acute exposures, at the highest allowable application rates, concentrations of chlorsulfuron, dicamba, imazapic, imazapyr, metsulfuron methyl, picloram, sulfometuron methyl, triclopyr, and 2,4-D could exceed the NOEC for 

aquatic plants (macrophytes or algae). Whereas, glyphosate was the only herbicide that could potentially exceed the NOEC for fish at the highest allowable application rate. None of the herbicides exceeded the NOEC for aquatic invertebrates tested. 

Sub-lethal herbicide effects that have been recorded include reductions in reproductive success, weight loss, physiological effects, as well as reductions in growth, prey capture 

ability and swimming ability (NOAA, 2002). Herbicides may be toxic to aquatic plants and invertebrates, thus indirectly affecting fish by reducing primary production or the trophic structure of invertebrate communities. 

Timing of application ceffects. For example, a 

Glyphosate, at recommecosystem, where dissoor water temperatures ahazardous to young of t1979). Applied thoughtfully, hbenefits while minimiziorganisms. The herbicides considereliminated rapidly from animals and do not bio-chain. 

Effects to Special Status Species (Chapter 4.7.3) 

All alternatives are associated with “likely to adversely affect” findings for some 

species listed under the Endangered Species Act. Sensitive species are similarly potentially affected. 

Biological evaluations aoccur at the project scal

status species minimizeaction alternatives. No at the regional scale. Ato special status species potential for adverse eff

Effects on Tribes and Treaty Rights (Chapter 4.7.4) 

American Indians and Hispanics are groups that may be disproportionately affected by the standards proposed in the action alternatives. No significant, discernible differences 

between alternatives relative to environmental justice were found at the Regional scale. None of the alternatives, including No Action, would change, restrict or abrogate treaty reserved or Executive Order rights. However, implementation of the standards may affect natural resources on which the tribes depend. 

Continue working with understood and can be m

scale. Worker health anprotected by adherence standards. Ongoing conothers during all phases implementation effectiv

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4.8.2 Short-term Uses and Maintenance of Long-term Productivity 

The continued expansion of invasive plants within the National Forests of Region Six would 

result in serious, long-term adverse effects on a broad range of resources, reducing the longterm productivity of the forests. Neighboring private and other public lands would also be 

affected. Invasive plants spread across landscapes, unimpeded by ownership boundaries. All 

land ownerships (private, corporate, tribal, and government) in the Pacific Northwest are 

affected by invasive plants. All land ownerships have the potential to spread invasive plants 

from their property to the property of their neighbors. A sustainable solution to the problem 

will require cooperation and a long-term commitment from all landowners. 

The relationship between uses and long-term productivity as it relates to invasive plant 

management is described throughout this EIS. The DFC, goals and objectives common to all 

action alternatives in Chapter 2 recognize the relationship between land uses and potential 

loss of productivity. Chapter 3 discusses the relationship between land management and use 

activities and invasive plants. Chapter 4 describes the effects of the proposed invasive plant 

management direction on land management and use activities. 

4.8.3 Irreversible or Irretrievable Impacts 

Implementation of the Proposed Action would not produce irreversible or irretrievable 

commitment of resources. The management direction adopted through this action would 

apply to site-specific projects and activities, and would be conducted within the constraints of 

the amended Forest plans and other national and regional management direction (which 

incorporates applicable law, regulation, and policy). Management direction adopted through 

this action would guide (rather than mandate) a particular site-specific project; hence, there 

would be no change in the physical environment. Any subsequent site-specific federal action 

that may change the environment would be subject to NEPA and other relevant planning 

regulations. 

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