United States 

Department of 

Agriculture 

Forest Service 

Pacific 

Northwest 

Region 

 

March 2009 

Wallowa-Whitman National 

Forest Invasive Plants 

Treatment Project 

Draft Environmental 

Impact Statement 

Volume II - Appendices 

Counties: Wallowa, Union, Baker, Malheur, Umatilla, and Grant Counties in 

Oregon, Adams, and Nez Perce Counties in Idaho 

Photo courtesy L. Dawson 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 

The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the 

basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, 

parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or 

part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply 

to all programs.) Persons with disabilities who require alternative means for communication of program 

information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 

(voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 

Independence Avenue, S.W., Washington, D.C. 20250-9410, or call (800) 795-3272 (voice) or (202) 720-

6382 (TDD). USDA is an equal opportunity provider and employer. 

 

 
Table of Contents 

Appendix A – Forest Plan

Appendix B – Botany

Appendix C – Wildlife

Appendix D – Soil and Water

Appendix E – Aquatics

Appendix F – Aerial Modeling Results and

Spray Guidelines

Appendix G – Adjuvants and Drift Reduction 

Agents

Appendix H – Social-Economics
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Appendix A – Forest Plan 

The Forest Plan 

Minimum Requirments Analysis 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 

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Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 Appendix A – Management Direction 

The Forest Plan 

This appendix has management direction from the 1990 Wallowa-Whitman Forest Land and 

Resource Management Plan (LRMP) (USDA 1990) as amended by the Pacific Northwest Region 

Invasive Plant Program, Record of Decision 2005. 

The 1990 LRMP goals and objectives that broadly govern the management of national forest 

lands are listed below. The LRMP also contains Standards and Guidelines that govern 

management more specifically in each resource area addressed by the goals. The Standards and 

Guidelines that deal with weeds are also listed in this appendix. 

The Forest Plan has a section called “Desired Future Condition.” This section acknowledges that 

noxious weeds will be part of forest even under desirable conditions. So even under the best 

scenarios it is understood that noxious weeds will be contained or controlled but in some areas 

cannot be eradicated completely. 

Wallowa Whitman Forest Plan- Forest Management Direction (USDA, 

1990) 

Diversity-Chapter 4 pg 2 

Goal: To maintain native and desirable introduced or historic plant and animal species and 

communities. Provide for all seral stages of terrestrial and aquatic plant associations in a 

distribution and abundance to accomplish this goal. Maintain or enhance ecosystem function to 

provide for long-term integrity and productivity of biological communities. 

Standards and Guidelines 

Project Analysis: Develop, during project planning, site-specific management prescriptions the 

goals for diversity and ecosystem function 

Vegetation Manipulation: Provide and maintain developing an ecologically sound distribution 

and abundance of plant and animal communities and species at the forest stand, basin, and Forest 

level. This distribution should contribute to the goal of maintaining all native and desirable 

introduced species and communities. Base tree species used in planting harvest units on the 

potential of the site as indicated by plant associations Consideration should be given to 

regenerating and maintaining a mixture of tree species, where appropriate for the site Retain, 

through precommercial and commercial thinning, a diversity of tree species based on site 

potential Allow for all natural species to function following vegetation manipulation. None 

should be eliminated from the site 

Threatened, Endangered, and Sensitive Species 

Goal: To protect and manage habitat for the perpetuation and recovely of plants and animals 

which are listed as threatened, endangered, or sensitive. (A list of these species can be found in 

the Forest Plan EIS) To assure that management activities do not jeopardize the continued 

existence of sensitive species or result in adverse modification of their essential habitat. 

Standards and Guidelines 

Review Biological Evaluations: Review all actions and programs, authorized, funded, or carried 

out by the Forest Service, to determine their potential effects on threatened, endan- gered, and 

sensitive species. Conduct these reviews, including biological evaluations, per direction in FSM 

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2670 and appropriate R-6 manual supplements: Prepare a biological evaluation during the 

environmental analysis of each project to determine possible effects of the proposed activity on 

threatened, endangered, and sensitive species. 

Other Activities: Restrict or prohibit other activities (e g , off road vehicles impacting plants or 

habitats) and monitor activities where necessary to protect threatened, endangered, or sensitive 

species. 

Cooperation: Cooperate with the States of Oregon, Washington, and Idaho in all aspects of 

sensitive plant management under the auspices of the Master Memoranda of Understanding The 

Oregon Natural Heritage Data Base and the Washington Natural Heritage Program will be 

contacted regarding sensitive species information. 

Cooperate with the US Fish and Wildlife Service, the States of Oregon, Washington, and Idaho 

and the Oregon Natural Heritage Data Base and the Washington Natural Heritage Program in the 

development of Species Management Guides for sensitive species adversely affected by standard 

management practices. 

Cooperate with the same agencies/organizations in the development and implementation of 

recovery plans for threatened and endangered species. Corrective measures to avoid possible 

adverse effects on recovery of populations will be implemented. 

Monitoring: Monitor known populations of sensitive species and their habitats in accordance 

with the Forest Monitoring Plan.

HCNRA Direction 

Direction from HCNRA Management Plan (Forest Plan Amendment # 

29, USDA 2003) 

Biologically Unique Species, Habitats, and Ecosystems Definition of Biologically Unique 

Species, Habitats, and Ecosystems 

Establishes criteria for identifying biologically unique species, habitats, and ecosystems as those 

that are: (1) limited in distribution solely or principally to the HCNRA; or (2) limited in 

distribution within the HCNRA, but may be relatively common within the neighboring 

ecoregions; or (3) relatively abundant in the HCNRA, but limited in distribution within the three 

neighboring ecoregions. 

Identifies biologically unique species, habitats, and ecosystems as rare plant species (including 

‘disjunct’ populations in the HCNRA that are geographically separated from the main distribution 

of a species); endemic plant species; rare combinations of aquatic, terrestrial, and atmospheric 

habitats; and rare combinations of outstanding and diverse ecosystems and parts of ecosystems. 

Rare plant species (137) are threatened, endangered, or proposed plants listed by U.S. Fish and 

Wildlife Service; sensitive species in Regions 1, 4, and 6; or disjunct plant species (separated 

geographically from the main range of species). 

Endemic plant species (9) are restricted to the HCNRA or immediate vicinity (defined as the 

Snake River Canyon from Oxbow Dam downriver to the Washington State border, the lower 
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Salmon River, the middle and lower portions of the Imnaha River including the tributaries of 

these river reaches). 

Rare combinations of aquatic, terrestrial and atmospheric habitats (6) principally reflect physical 

environmental features of the landscape that are produced from a unique combination of soils, 

climate, precipitation, and aspect. Rare combinations of outstanding and diverse ecosystems are 

plant community types and associations (16) that are biologically unique because they occur in 

the HCNRA and nowhere else or occur in limited amounts within the HCNRA. 

Management Direction Manages the HCNRA as an area of high biological diversity and 

endemism to ensure the maintenance and/or restoration of ecological function and sustainability 

of species, habitats, and ecosystems that contribute to its biological uniqueness. Provides specific 

direction for identification, protection, and mitigation of effects for biologically unique species, 

habitats, and ecosystems through identification, protection, and mitigation of effects during 

project-level planning. RNAs will continue to be managed under existing direction in the Forest 

Plan (MA 12) to preserve significant natural ecosystems for comparison with those influenced by 

humans; for provision of ecological and environmental studies; for preservation of gene pools for 

typical and rare and endangered plants and animals. In addition, RNAs will also be managed to 

protect rare combinations of outstanding and diverse ecosystems that occur within RNAs. 

Fuelwood cutting, commercial mushroom harvesting, and commercial collection of special forest 

products in proposed and established RNAs will be prohibited. 

Management Direction for Noxious Weeds 

Nox-O1: Manage noxious weeds to reduce negative impacts to native plants, wildlife, and other 

resources. Use all reasonable and feasible integrated weed management processes available under 

existing decisions and direction to prevent, restore, eradicate, control, contain, or otherwise 

reduce negative impacts of noxious weeds. 

Nox-O2: Evaluate extent of nonnative invasive plants, their relative impacts and potential for 

restoration. (New) Nox-O3: Evaluate the factors contributing toward the spread of nonnative 

invasive plants and implement appropriate prevention strategies. (New) 

Nox-G1: Conduct restoration activities on grassland sites in mid-seral or earlier status to improve 

the ability of native vegetation on site to resist invasion and occupancy by noxious weeds. (New) 

Nox-G2: Develop a public information and education program on preventing the introduction and 

spread of noxious weeds. Provide a reporting method for and encourage the public to report new 

weed sites. (New) Nox-G3: Provide for natural restoration of degraded sites by modifying 

management activities as necessary. (New 

Nox-G3: Consider quarantine or closure of some areas, trails, and/or roads to prevent the spread 

of noxious weeds to adjacent areas. (New) 

Nox-G3: Consider quarantine or closure of some areas, trails, and/or roads to prevent the spread 

of noxious weeds to adjacent areas. (New) 

Nox-G6: When planning PF projects, identify sites of known noxious weeds and/or invasive 

species of concern. Avoid burning through identified weed sites and/or prescribe management 

actions that will minimize the potential for creation of site conditions favorable to the spread of 

invasive weeds. (New) Nox-G7: Contain and/or control aggressive noxious weeds and other 

nonnative plants that reduce ground cover, reduce perennial plant cover, and accelerate erosion. 

(New) 

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Nox-G7: Contain and/or control aggressive noxious weeds and other nonnative plants that reduce 

ground cover, reduce perennial plant cover, and accelerate erosion. (New) 

Rec-S23: Outfitters and guides will be provided with simple noxious weed and invasive species 

identification handbooks and forms on which to report changes in the location or presence of 

noxious weeds and invasive species along their outfitting and guiding routes. As a condition of 

their permit, the permittee will complete and submit an HCNRA noxious weed form each month 

in which outfitting and guiding services are provided. 

Rec-S24: Noxious weed identification sheets/reporting forms will be offered to visitors in all 

visitor centers and trailheads. 

Wil-S4: Noxious weeds would be managed within the Wilderness using the minimum 

management tool to insure the most compatible, but effective means of meeting objectives. 

(INWMP Plan) 

Acc-G8: Manage roads and trails in coordination with the Integrated Noxious Weed Management 

Plan. Where roads or trails are to be maintained, ensure an up to date inventory of all noxious 

weed sites within the right-of-way and plan for appropriate treatment to prevent the spread of 

weeds during maintenance activities. Strive to maintain an effective ground cover on all adjacent 

disturbed surfaces, consistent with safety, to provide a degree of protection against the spread or 

invasion of noxious weeds. Where roads or trails are to be closed, ensure that pre-planning 

provides for an inventory of noxious weeds sites and for continued treatment of those sites. 

During closure activities, ensure that on-site or seeded native plant species are considered with 

the focus on minimizing bare ground. (INWMP Plan) 

Veg-S1: Follow the Integrated Noxious Weed Management Plan (USDA 1992) and the USFS 

Yellow Starthistle Management proposal to manage noxious weeds in the HCNRA. (INWM Plan) 

TES-O4: Conduct habitat improvement projects for federally listed species. These may include 

fencing, burning, closing roads, treatment of noxious weeds, plant propagation, or other actions. 

(New)

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The following standards have been adopted into the 1990 LRMP from the R-6 2005 ROD. 

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MINIMUM REQUIREMENTS 

DECISION GUIDE 

WORKSHEET 

Non-native Invasive Plants Treatment 

Hells Canyon Wilderness, Eagle Cap Wilderness and 

Monument Rock Wilderness 

Step 1: Determine if any administrative action is necessary. 

Description: 

The Hells Canyon Wilderness area on the Wallowa-Whitman National Forest in northeast Oregon and 

Central Idaho is experiencing a rapidly increasing outbreak of yellow star-thistle, a non-native invasive 

species (NNIS). The presence of this NNIS is the result of past human actions however factors such as the 

lack of treatment on adjacent public and private lands, and seed transport via recreation users along trail 

corridors, wind and wildlife have all contributed to the outbreak. As observed in the Salmon River 

drainage east of the Wallowa-Whitman NF, yellow star-thistle has rapidly spread creating monocultures in 

many ecotypes. At this time, the mapped infestations of yellow star-thistle in the Hells Canyon 

Wilderness Area are the only known infestations of these noxious weeds in the wilderness. None of the 

infestations are within active grazing allotments inside the wilderness. 

As part of the Hells Canyon National Recreation Area, the wilderness area was established, in part, for its 

ecological values. One of its key features is the presence of one of the largest contiguous areas of 

native bunchgrass grasslands in the Western United States. In order to manage the area to preserve it’s 

wilderness character and protect these natural conditions, NNIS will need to be treated. 

Over the last few years, a limited number of the approximately 530 infested acres of yellow star-thistle 

have been treated by hand pulling. This has been met with limited success. Herbicide use via back packs 

and mule packs along the main trail corridors have also been employed. These treatments have been 

aimed at reducing populations of this NNIS and its seed production as well as reduce the risk of spread 

outside the infested areas. Many other areas of infestations have not been treated because of their remote 

and rugged locations. Treatment in these areas will include more logistical support, safety mitigations 

and/or expense. 

In addition, to the Hells Canyon Wilderness, the Eagle Cap Wilderness and Monument Rock Wilderness, 

WWNF, have know populations of NNIS which will require occasional use of stock mounted spray 

pumps as a treatment method. 

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A. Describe Valid Existing Rights or Special Provisions of Wilderness Legislation 

Are there valid existing rights or is there a special provision in wilderness legislation (the 

Wilderness Act of 1964 or subsequent wilderness laws) that allows consideration of action 

involving Section 4(c) uses? Cite law and section. 

Yes: No: Not Applicable: 

Explain: 

There are no special provisions that apply in The Wilderness Act (1964). 

The Wilderness Act (1964) 

Section 2 (a) Wilderness “shall be administered ... in such manner as will leave them unimpaired for 

future use as wilderness, and so as to provide for the protection of these areas [and] the preservation of 

their wilderness character...” 

Section 2 (c) An area of wilderness is...an area of undeveloped Federal land retaining its primeval 

character and influence, without permanent improvements or human habitation, which is protected and 

managed so as to preserve its natural conditions and which (1) generally appears to have been affected 

primarily by the forces of nature, with the imprint of man's work substantially unnoticeable...” 

Section 4 (c) Prohibition of certain uses 

“...except as necessary to meet minimum requirements for the administration of the area for the purpose 

of this Act...there shall be no temporary road, no use of motor vehicles, motorized equipment or 

motorboats, no landing of aircraft, no other form of mechanical transport, and no structure or installation 

within any such area.” 

The Hells Canyon National Recreation Area Act (1975) 

Sec. 2. (a) “The lands depicted as the "Hells Canyon Wilderness" on the map referred to in subsection 

1(b) of this Act are hereby designated as wilderness. 

(b) The wilderness designated by this Act shall be administered by the Secretary in accordance with the 

provisions of this Act or in accordance with the provisions of the Wilderness Act (78 Stat. 890), 

whichever is the more restrictive, except that any reference in such provisions of the Wilderness Act to the 

effective date of that Act shall be deemed to be a reference to the effective date of this Act. “ 

Sec 7 (3) “ preservation, especially in the area generally known as Hells Canyon, of all features and 

peculiarities believed to be biologically unique including but not limited to, rare and endemic plant 

species...rare combinations of outstanding and diverse ecosystems anti parts of ecosystems associated 

therewith...” 

No additional provisions apply 

B. Describe Requirements of Other Legislation 

Do other laws require action? 

Yes: No: Not Applicable: 

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Explain: 

The Noxious Weeds Act of 1974 designates the FS as the lead agency for noxious weed coordination for 

USDA and requires establishment of integrated management. 

The Hells Canyon National Recreation Area Act (HCNRA) of 1975 states “ the Secretary shall 

administer the recreation area in accordance with the laws, rules, and regulations applicable to the 

national forests for public outdoor recreation in a manner compatible with the following objectives: . . . 

(3) preservation . . . of all features and peculiarities believed to be biologically unique including, but not 

limited to, rare and endemic plant species, rare combinations of aquatic, terrestrial, and atmospheric 

habitats, and the rare combinations of outstanding and diverse ecosystems and parts of ecosystems 

associated therewith.” 

The Executive Order of February 3, 1999 titled Invasive Species requires federal agencies to detect NNIS 

and respond quickly to infestations. 

Yes: No: Not Applicable: 

C. Describe Other Guidance 

Does taking action conform to and implement relevant standards and guidelines and direction 

contained in agency policy, unit and wilderness management plans, species recovery plans, tribal 

government agreements, state and local government and interagency agreements?

Explain: 

The Wallowa-Whitman National Forest Land and Resource Management Plan (LRMP) as amended by 

the Regional Invasive Plant EIS ROD: 

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

emphasizes prevention, early detection, and early treatment. 

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. 

HCNRA Comprehensive Management Plan 

Objective Nox O-1: Manage noxious weeds to reduce negative impacts to native plants, wildlife, and 

other resources. Use all reasonable and feasible integrated weed management processes available under 

existing decisions to prevent, restore, eradicate, control, contain, or otherwise reduce negative impacts of 

noxious weeds 

Forest Service National Weed Management Strategy 

Four primary goals of Integrated Weed Management are: 1) increase the understanding and 

awareness, 2) develop and implement integrated weed management at all levels, 3) institutionalize 

consideration of noxious weeds during the planning phase of projects, 4) develop strong partnerships. 

FS policy on Environmental Management – FSM 2150 

2150.3 (3) – Use pesticides in wilderness only when necessary to protect or restore significant resource 

values within wilderness or on public or private lands bordering wilderness after receipt of the public or 

private landowner’s permission. 

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2151.04a (1) – Regional Foresters. Regional Foresters are responsible for reviewing and approving or 

disapproving all proposed pesticide uses on National Forest System lands. The Regional Forester may 

delegate this authority to other line officers on a case-by-case basis or by supplement to this code, except 

for the following: 

1. Any pesticide use in Wilderness, which includes Wilderness study areas. 

Forest Service Policy on Wilderness Management - FSM 2320 

2320.3 - Policy 

 1. Where there are alternatives among management decisions, wilderness values shall dominate 

over all other considerations except where limited by the Wilderness Act, subsequent legislation, or 

regulations. 

 2. Manage the use of other resources in wilderness in a manner compatible with wilderness 

resource management objectives. 

2320.2 - Objectives 

 2. Maintain wilderness in such a manner that ecosystems are unaffected by human manipulation 

and influences so that plants and animals develop and respond to natural forces. 

2320.5 - Definitions 

 10. Indigenous Species. Any species of flora or fauna that naturally occurs in a wilderness area 

and that was not introduced by man. 

 11. Native Species. Any species of flora or fauna that naturally occurs in the United States and 

that was not introduced by man. 

 12. Naturalized Species. Any non-indigenous species of flora or fauna that is close genetically or 

resembles an indigenous species and that has become established in the ecosystem as if it were an 

indigenous species. 

 13. Exotic Species. Any species that is not indigenous, native, or naturalized. 

2323.04c – Regional Forester. Unless specifically reserved to the President (FSM 2323.04a_ or the 

Chief (FSM 2323.04b) or assigned to the forest Supervisor (FSM 2323.04d) or the District Ranger (FSM 

2323.04e), the Regional Forester is responsible for approving all measures that implement FSM direction 

on the use of other resources in wilderness. Specific responsibilities include but are not limited to: 

 9. Approving the use of pesticides within wilderness. 

Note – The Federal Insecticide, Fungicide, and Rodenticide Act of 1947 definition of ‘pesticide’ includes 

‘herbicides.’ 

Non-native invasive species are one of the Chief’s 4 Threats to the health of the National Forest System. 

D. Describe Options Outside of Wilderness 

Can this situation be resolved by an administrative activity outside of wilderness? 

 Yes: No: 

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 Explain: Control or containment activities outside the wilderness are important, but will not be 

sufficient to prevent the spread of existing infestations within the wilderness. These infestations are 

spreading farther into the wilderness each year. The area inside the wilderness must be treated in 

order to curtail or reduce the spread of the NNIS. 

E. Wilderness Character 

Is it necessary to take administrative action to preserve wilderness character, as described by the 

qualities listed below? 

Untrammeled: Yes: No: 

Explain: Whether any action is taken or not, the untrammeled quality of the wilderness is 

threatened. The spread of noxious weeds will reduce the plant and animal diversity of the wilderness, a 

key component of why the wilderness was created. The spread of invasive species into the wilderness has 

at least, in part, been inadvertently aided by human actions (seed introduction, spread along trails and into 

campsites, etc.); thus, allowing introductions to persist and spread is a direct result of human influence. 

But, to not interfere in some way to “correct” the problem would be a manipulation of the natural 

processes, because these species are exotic and, without natural or artificial controls, are capable of 

creating monocultures of non native plants that further impede the untrammeled quality of wilderness.

Undeveloped: Yes: No: 

 Explain: Treatment of NNIS will not increase or decrease any developments in the wilderness 

areas. 

Natural: Yes: No: 

 Explain: The presence of non-native invasive plants (noxious weeds) interferes with the natural 

conditions of the wilderness resource. Natural, native plant communities can become displaced by exotic 

species. These, in turn, impact habitat for native fish and wildlife, including invertebrate wildlife. 

Outstanding opportunities for solitude or a primitive and unconfined type of recreation: 

 Yes: No:

 Explain: Solitude and primitive types of recreation will not be changed. The unconfined aspect 

of recreation may be affected since the wilderness recreation experience is in part dependent on the 

wilderness setting representing a natural and native ecosystem. If non- native invasive species (NNIS) are 

allowed to spread and eventually replace native vegetation the human experience in wilderness will be 

effected. The effects include changes in vegetation type and also habitat and the fish and wildlife species 

that depend on the natural conditions. In turn recreationists may choose to avoid areas of NNIS 

infestations and choose sites not currently impacted 

Other unique components that reflect the character of this wilderness: 

 Yes: No: Not Applicable: 

 Explain: The Hells Canyon Wilderness Area, in particular, is noteworthy for its extensive stands 

of native grasslands. These bunchgrass plant communities are among the most vulnerable to invasion by 

non-native, invasive plant species. 

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F. Describe Effects to the Public Purposes of Wilderness 

Is it necessary to take administrative action in support of the public purposes for wilderness (as 

stated in Section 4(b) of the Wilderness Act) of recreation, scenic, scientific, education, 

conservation, and historical use? 

Recreation: Yes: No: Not Applicable: 

 Explain: The presence and spread of NNIS in the wilderness will degrade the quality of the 

recreation experience as native species are replaced. This may happen due to the changes in vegetation 

and effects on scenery, habitat, and capacity for grazing of recreational livestock. 

Scenic: Yes: No: Not Applicable: 

 Explain: Noxious weeds have the potential to lower the scenic quality of an area. This would 

occur with the displacement of diverse native species and replacement of monocultures of plants such as 

yellow star thistle as seen along the Salmon River. 

Scientific: Yes: No: Not Applicable: 

 Explain: The wilderness contains many long-term monitoring plots in native plant communities 

that serve as benchmarks, against which change to more intensively managed areas of the same 

community types, can be measured. If these native plant benchmarks change due to invading exotic 

plants, the ability to measure “natural change” is lost and comparisons of natural “pristine” conditions 

with managed sites become impossible. 

Education: Yes: No: Not Applicable: 

 Explain: The goals and standards as stated in the Region Plant EIS ROD provide direction for 

the protection of our native vegetation. The Wallowa-Whitman NF has been actively integrating this 

direction in its invasive plant programs. Prevention standards are included in the various management 

plans for activities that occur within or affect wilderness values. These include but are not limited to: 

range, fire, outfitter and guides, contractors. As of 2007, all wilderness trailheads have been posted with 

certified weed free feed requirements. Educational training products have been developed or obtained for 

fire crews, local fairs and activities, local visitor centers, as well as special group presentations. Invasive 

Plant management is done as a collaborative effort with various partners in order to manage on a larger 

landscape scale with long term strategies utilizing integrated weed management tools, including reseeding 

of natives to prevent encroachment of invasive species. 

Conservation: Yes: No: Not Applicable: 

 Explain: NNIS (Noxious weeds) compete with and can displace native plant species further 

degrading the habitat for native fish and wildlife species. The Eagle Cap and Hells Canyon Wilderness 

areas are important refuges for rare and endemic plants, some listed threatened under the Endangered 

Species Act (ESA), where invasion by non-native species is listed as a principal threat to their survival. 

This is true for both Mirabilis macfarlanei and Silene spaldingii, which both inhabit or have habitat in the 

Hells Canyon Wilderness. The spread of NNIS can imperil these rare plants. Furthermore, the diversity 

of other native plants, including less rare, but endemic, plants, as well as the more abundant native 

grasslands are significantly threatened by the invasion of non-native species. The Salmon River canyon, 

a short distance from the Hells Canyon Wilderness, has experienced significant alteration of native plant 

communities by non-native invasive species. 

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Historical use: Yes: No: Not Applicable: 

Explain: 

• Humans have occupied the HCNRA for at least 7,100 years and probably as long as 10,000 years. 

Populations increased in the canyon in the late 1800s during the gold-rush and homesteading eras. 

This era was short-lived and many ranch properties reverted to federal ownership. Some of these 

sites are still working ranches today. 

• Livestock grazing has occurred in the HCNRA for hundreds of years, first by American Indian 

horses as early as the 1730s. Homesteads and small ranches dotted the landscape in the late 

1800s, with cattle and sheep grazing beginning in the latter half of the 19th century. In 1905, over 

300,000 domestic sheep grazed Wallowa County, most grazing on NFS lands some part of the 

year. By 1920 when permits peaked at 108,000 animal unit months, historical photos indicate the 

range was in very poor condition, especially near homesteads. 

• From 1920 to the present, photos indicate gradual improvement of range condition as livestock 

numbers have decreased, grazing systems have been applied, and range improvements have been 

developed. In 1995, domestic sheep grazing ceased on the Oregon side of the HCNRA and, by 

1998 only 38,620 cattle AUMs were permitted. Some limited areas remain in poor condition 

because of persistent noxious weed invasion. Improvement in management standards for 

livestock grazing and riparian management have improved vegetative cover and retained soilprotecting vegetation. In vacant allotments, similar or even greater recovery has resulted except 

where big-game animal impacts have caused localized problems. 

• Three hydropower dams (Hell Canyon Complex) built on the Snake River in the 1960s and 1970s 

have contributed to altering river flow amounts and time, sediment delivery, water temperature, 

fish and invertebrate production, and waterfowl use. Other hydropower dams on the Snake River 

outside the HCNRA above and below these dams have also contributed to these cumulative 

effects. 

• Jet boat use started in the early 1960s and became popular in the late 1970s. Use steadily 

increased until the early 1990s when the Wild and Scenic Snake River Recreation Management 

Plan (1999 rev) limited jet boat use in the primary season from late May to early September. 

• The HCNRA designation in 1975 changed management emphasis from commodity production to 

providing quality recreation opportunities and meeting the objectives of the HCNRA Act. 

Designation of the Hells Canyon Wilderness at the same time formalized emphasis on primitive 

settings for over one third of the HCNRA. Wild and Scenic River designation (1975) also 

emphasized protecting outstandingly remarkable values for the Snake, Imnaha and Rapid rivers. 

• Watershed conditions have improved throughout much the HCNRA, but natural events including 

wildfire, heavy rainfall from summer thunderstorms, winter rain-on-snow events, and related 

flooding (including records floods in 1997) have worsened watershed conditions with some 

localized areas across the HCNRA. Several streams have limited water quality due to sediment. 

Historic fire exclusion has created a build up of fuels in both grasslands and forestlands. 

Approximately 325, 000 acres have burned across the HCNRA in the last 16 years. 

• Approximately 23,000 acres of forest was harvested for timber by various methods before the 

creation of the HCNRA in 1975. An estimated 31,472 acres has been harvested since using 

selective harvest methods. Approximately 20 percent of the forested areas have received some 

type of vegetative treatment to improve vigor. Ponderosa pine, western larch, and white pine have 

decreased across their range in the Interior Columbia Basin and transitioned to Douglas fir and 

grand/white fir, Engelmann spruce, and subalpine fir. Generally, mid-seral forest structures have 

increased in dry and moist forests with a loss of large, scattered trees that prefer open areas.

 A-15
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 Appendix A – Management Direction

Step 1 Decision: Is any administrative action necessary? 

Yes: No: More information needed: 

 Explain: Treatment of NNIS in wilderness is a non-emergency administrative action which has 

been delegated to the Forest Supervisor upon meeting national requirements.

The threats to the wilderness and adjacent lands from non-native invasive species are significant. These 

infestations are still relatively small, can be contained and, in some cases, eradicated. Without the use of 

herbicides to control these NNIS the natural quality of the wilderness character action is threatened. 

Therefore, action is necessary. 

If action is necessary, proceed to Step 2 to determine the minimum activity.

Step 2: Determine the minimum activity. 

Description of Alternatives 

For each alternative, describe what methods and techniques will be used, when the activity will take 

place, where the activity will take place, what mitigation measures are necessary, and the general effects 

to the wilderness resource and character. 

Actions common to all alternatives: 

Herbicide treatment of non-native invasive species covering 874 acres in the three wilderness areas - A 

total of 348 acres are accessible to ground-based packstock or backpack spray methods; and 526 acres are 

inaccessible to packstock due to rough terrain or remote distance from trailheads. 

Alternative # A 

Description: Hand pump-sprays mounted on backpack or livestock on 348 acres (265 ac. -Hells 

Canyon, 81 ac.- Eagle Cap, 2 ac. - Monument Rock). Manual methods would be used on 5 acres. 

Herbicide use by backpack and horseback spraying would occur at the appropriate time of the year to 

maximize the effectiveness of the treatment be it a manual hand pulling/ cutting treatment or herbicide 

treatment. 

Effects: 

 Wilderness Character 

• “Untrammeled” – Work crews would have small effect on the untrammeled quality of 

wilderness. Temporary dead or dying vegetation from herbicide application on 348 acres would 

have an effect on the “untrammeled” quality of the wilderness. This would last during the 

growing season when herbicides were applied. 

• “Undeveloped” – There is no effect on the undeveloped quality of wilderness character. 

• “Natural” – Effective NNIS treatment would enhance the natural quality by restoring native 

vegetation and reducing the influence of non-native species on all components of the wilderness 

resource. Inability to access 526 remote acres by livestock would allow for the spread of invasive 

plant populations to other areas, thereby decreasing “natural” quality of the wilderness. 

 A-16 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 Appendix A – Management Direction 

• “Outstanding opportunities for solitude or a primitive and unconfined type of recreation” –

In the short term- the presence of treatment crews may adversely affect the wilderness experience 

of those in the area. In the long-term the restoration of native vegetation will serve to enhance the 

wilderness recreation experience. 

Heritage and Cultural Resources – No effect 

Safety of Visitors, Personnel, and Contractors – The remoteness and extreme topography of 60% of the 

sites to be treated adds significant risks to personnel and contractors conducting spray operations. Some 

sites may not be accessible. Because of greater time involved in transporting herbicides (days as opposed 

to minutes) there is greater exposure to herbicide spills. 

Economic and Time Constraints – Because of the long distances from wilderness trailheads to the 

project sites, there would be significant costs in transporting project materials. Ground based herbicide 

treatments in Hells Canyon wilderness are estimated at $310 per acre. This would total about $271,000 

for 874 acres, assuming all sites could be accessed and treated with these methods. 

Additional Wilderness-specific Comparison Criteria – None identified

Alternative # B 

Description: Backpack or Packstock Herbicide Use 348 acres using battery-power pump sprayers (265 

ac. - Hells Canyon, 81 ac. - Eagle Cap, 2 ac.- Monument Rock). Manual methods would be used on 5 

acres. This alternative is identical to Alternative A except that power-pump sprayers would be used 

instead of hand-pump sprayers. 

Effects: 

Wilderness Character 

• “Untrammeled” – Work crews would have small effect on the untrammeled quality of 

wilderness. Temporary dead or dying vegetation from herbicide application on 348 acres would 

have an effect on the “untrammeled” quality of the wilderness. This would last during the 

growing season when herbicides were applied. 

• “Undeveloped” – There is no effect on the undeveloped quality of wilderness character. 

• “Natural” – Effective NNIS treatment would enhance the natural quality by restoring native 

vegetation and reducing the influence of non-native species on all components of the wilderness 

resource. The inability to access 526 remote acres by livestock would allow for the spread of 

invasive plant populations to other areas, thereby decreasing “natural” quality of the wilderness. 

• “Outstanding opportunities for solitude or a primitive and unconfined type of recreation” – 

In the short term- the presence of treatment crews may adversely affect the wilderness experience 

of those in the area. In the long-term the restoration of native vegetation will serve to enhance the 

wilderness recreation experience. The use of battery-powered pump sprayers may add slightly 

more noise than hand-powered pumps, but these style pumps are relatively quiet. Any noise 

generated by these sprayers would be restricted to the immediate area. Few visitors, if any, would 

have their experience disrupted by the noise of these sprayers. The pumps appear more or less 

the same as hand-powered pump sprayers. The use of battery-powered sprayers would decrease 

the amount of time spraying compared to hand-powered pumps, thus decreasing the amount of 

time crews spend in the wilderness and thereby reducing impacts to the opportunities for solitude 

and primitive recreation. 

Heritage and Cultural Resources – No effect 

 A-17
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 Appendix A – Management Direction

Safety of Visitors, Personnel, and Contractors – The remoteness and extreme topography of 60% of the 

sites to be treated adds significant risks to personnel and contractors conducting spray operations. Some 

sites may not be accessible. Because of greater time involved in transporting herbicides (days as opposed 

to minutes) there is greater exposure to herbicide spills. 

Economic and Time Constraints – Because of the long distances from wilderness trailheads to the 

project sites, there would be significant costs in transporting project materials. Ground based herbicide 

treatments in Hells Canyon wilderness are estimated at $310 per acre. This would total about $271,000 

for 874 acres, assuming all sites could be accessed and treated with these methods. Using battery 

powered sprayers would decrease project costs, though this is difficult to quantify. 

Additional Wilderness-specific Comparison Criteria – None identified 

Alternative # _C

Description: Packstock and backpack sprayers would be used to apply herbicides on 348 acres (265 ac. - 

Hells Canyon, 81 ac.- Eagle Cap, and 2 ac.- Monument Rock) and a helicopter would be used to apply 

herbicides on 526 acres in the Hells Canyon Wilderness. Manual methods would be used on 5 acres. 

Herbicide application would be by backpack and packstock using battery-powered sprayers and would 

occur at the appropriate time of the year to maximize the effectiveness of the treatment (depending on the 

species, late spring or fall. Non-mechanical transport methods (foot and stock travel) would be used to 

move herbicide, people, and supplies to treatment areas. Helicopter landings in the wilderness would not 

occur. 

Effects: 

Wilderness Character 

• “Untrammeled” – Treatment of invasive weed infestations within wilderness can be viewed as 

human manipulation. There will be short-term evidence of weed treatments including dead or 

wilting plants. These effects would persist only during the same growing season as the invasive 

plant treatment. Only 874 acres would be treated by both ground and aerial based methods out of 

a total 586,779 wilderness acres). In the Hells Canyon Wilderness, 796 acres of 214,994 acres 

would be treated. 

• “Undeveloped” – There is no effect on the undeveloped quality of wilderness character. 

• “Natural” – Using helicopters would enable 526 acres to be treated effectively. This would 

enhance the natural quality of the wilderness by restoring native vegetation and reducing the 

impacts of non-native invasive species on all other components of the wilderness resource. 

• “Outstanding opportunities for solitude or a primitive and unconfined type of recreation” – 

In the short term, the presence of treatment crews may adversely affect the wilderness experience 

of visitors in the area. The use of helicopters would adversely affect the experience of solitude 

and unconfined recreation. Most sites proposed for aerial application are within 1.5 miles of the 

Wild and Scenic Snake River corridor, an area authorized for jet boat use by permit: visitors in 

the Hells Canyon 

• Wilderness in areas near the river (up to 2 miles) already experience noise from jetboats. 

However, the use of helicopters would probably occur over far fewer days than in alternatives A 

or B. An analysis showed that the estimated time of helicopter flight time to treat 526 acres 

would not exceed 4 hours. Aerial application operations would probably occur over a one or twoday period during midweek. Trailheads leading to treatment areas would be posted with the dates 

of herbicide treatment, affording potential visitors to select another portion of the wilderness to 

recreate. 

 A-18 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 Appendix A – Management Direction 

Heritage and Cultural Resources – None identified 

Special Provisions - Section 4(d): “...the use of aircraft... may be permitted...subject to such restrictions 

as the Secretary of Agriculture deems desirable...” 

Safety of Visitors, Personnel, and Contractors - There is a risk to crews from working with herbicides, 

tools, and stock and from travelling over rugged terrain. Effects on visitors can be minimized by posting 

trailheads and visitor centers alerting them to the areas and dates of herbicide treatments. 

Economic and Time Constraints – Using helicopters for herbicide spraying would decrease project time 

considerably. The cost estimates for aerial herbicide treatments are $42/acre. This would total about 

$22,000 for 526 acres. Ground based herbicide treatments in Hells Canyon wilderness are estimated at 

$310 per acre. This would total about $108,000 for 348 acres. Implementing the treatment using only 

traditional non-motorized skills to deliver materials to the ground-based job sites would increase the 

project time and costs. For the wilderness cost estimates for Alternative C would total about $130,000, a 

figure less than half the costs estimated for Alternatives A and B. 

Additional Wilderness-specific Comparison Criteria – None identified. 

Alternative # __D _

Description: Packstock and backpack sprayers would be used to apply herbicides on 348 acres (265 ac. 

Hells Canyon, 81 ac. Eagle Cap, and 2 ac. Monument Rock) and a helicopter would be used to apply 

herbicides on 526 acres in the Hells Canyon Wilderness. Manual methods would be used on 5 acres. 

Herbicide application would be by backpack and packstock using battery-powered sprayers and would 

occur at the appropriate time of the year to maximize the effectiveness of the treatment (late spring or 

fall). Both non-mechanical and helicopters would be used to transport supplies. Helicopter landings in 

the wilderness would not occur. 

Effects: 

Wilderness Character 

• “Untrammeled” – Treatment of invasive weed infestations within wilderness can be viewed as 

human manipulation. There will be short-term evidence of weed treatments including dead or 

wilting plants. These effects would persist only during the same growing season as the invasive 

plant treatment. Only Only 874 acres would be treated by both ground and aerial based methods 

out of a total 586,779 wilderness acres). In the Hells Canyon Wilderness, 796 acres of 214,994 

acres would be treated. 

• “Undeveloped” – There is no effect on the undeveloped quality of wilderness character. 

• “Natural” – Using helicopters would enable 526 acres to be treated effectively. This would 

enhance the natural quality of the wilderness by restoring native vegetation and reducing the 

impacts of non-native invasive species on all other components of the wilderness resource. 

• “Outstanding opportunities for solitude or a primitive and unconfined type of recreation” – 

In the short term, the presence of treatment crews may adversely affect the wilderness experience 

of visitors in the area. The use of helicopters would adversely affect the experience of solitude 

and unconfined recreation. Most sites proposed for aerial application are within 1.5 miles of the 

Wild and Scenic Snake River corridor, an area authorized for jet boat use by permit: visitors in 

the Hells Canyon. Wilderness in areas near the river (up to 2 miles) already experience noise 

from jet boats. However, the use of helicopters would probably occur over far fewer days than in 

alternatives A or B. An analysis showed that the estimated time of helicopter flight time to treat 

526 acres would not exceed 4 hours. Aerial application operations would probably occur over a 

 A-19
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 Appendix A – Management Direction

one or two-day period during midweek. Additional helicopter flight time would occur from the 

transport of materials closer to the job sites in the wilderness. It’s difficult to quantify the flight 

time for this, but given the short distances from lift-off locations outside the wilderness to the job 

sites, the flights are not likely to exceed 30 minutes, probably less. Furthermore, trailheads 

leading to treatment areas would be posted with the dates of herbicide treatment, affording 

potential visitors to select another portion of the wilderness to recreate to avoid interruptions of 

solitude. 

Heritage and Cultural Resources – None identified 

Special Provisions - Section 4(d): “...the use of aircraft... may be permitted...subject to such restrictions 

as the Secretary of Agriculture deems desirable...” 

Safety of Visitors, Personnel, and Contractors - There is a risk to crews from working with tools and 

stock and from travelling over steep, rugged terrain with slopes exceeding 120%. The risk to employees 

and contractors would likely be less than other alternatives because the use of helicopters to transport 

materials to the job sites would reduce the exposure of crews to the hazards of haluling supplies over 

treacherous terrain. Effects on visitors can be minimized by notifying the public of the areas and times of 

treatment. 

Economic and Time Constraints - Using helicopters for herbicide spraying would decrease project time 

considerably. The cost estimates for aerial herbicide treatments are $42/acre. This would total about 

$22,000 for 526 acres. Ground based herbicide treatments in Hells Canyon wilderness are estimated at 

$310 per acre. This would total about $108,000 for 348 acres. These costs may be reduced using 

helicopters to transport supplies to the job site, though this would be difficult to quantify. This alternative 

would probably cost less than alternative C. 

Additional Wilderness-Specific Comparison Criteria – None identified. 

Alternative Acres treated Non-motorized methods Motorized/mechanized 

transport methods 

A 

348 acres: 

Hells Canyon = 265 

Eagle Cap = 81 

Monument Rock = 2 

(5 acres = hand treatment) 

All acres = herbicide application 

via backpack and horseback handpump spraying N/A 

B 

348 acres: 

Hells Canyon = 265 

Eagle Cap = 81 

Monument Rock = 2 

(5 acres = hand treatment) 

N/A 

All acres = herbicide 

application via powerpump backpack and 

horseback sprayers 

C 

348 acres: 

Hells Canyon = 265 

Eagle Cap = 81 

Monument Rock = 2 

(5 acres = hand treatment) 

526 acres = Hells Canyon 

Non-mechanical transport methods 

(foot and stock travel) would be 

used to move herbicide, people, 

and supplies to treatment areas 

No wilderness landings/transport 

348 acres = herbicide 

application via batterypump backpack and 

horseback sprayers 

526 acres =- aerial 

helicopter 

D 

348 acres: 

Hells Canyon = 265 

Eagle Cap = 81 

Monument Rock = 2 

(5 acres = hand treatment) 

526 acres = Hells Canyon 

No helicopter landings in the 

wilderness 

348 acres = herbicide 

application via batterypump backpack and 

horseback sprayers 

526 acres =- aerial 

helicopter 

Both non-mechanical and 

helicopters would be used 

to transport supplies. 

 A-20 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 Appendix A – Management Direction 

Step 2 Decision: What is the Minimum Activity? 

The selected alternative is: Alternative #D 

Herbicide use by backpack, horseback spraying and helicopter aerial application would occur at the 

appropriate time of the year to maximize the effectiveness of the treatment. When possible, high use 

periods of recreation will be avoided. The Forest will follow the Regional Guidelines and forest plan 

standards for effective public notification and all herbicide use applications. 

Describe the rationale for selecting this alternative:

This alternative provides effective control with the minimum use of herbicide and mechanical transport 

and aerial application methods. 

• Alternative D will effectively access and treat all invasive plant infestations in the wilderness thereby 

promoting and sustaining natural conditions for which the wilderness was established. 

• Alternative D reduces the exposure of forest crews and contractors to hazards associated with hauling 

supplies for great distances over rough terrain. 

• Alternative D will halve approximately the costs for managing invasive plants in the wilderness. 

• Alternative D will not substantially impact the untrammeled, natural, undeveloped, or outstanding 

opportunities for solitude or a primitive and unconfined type of recreation of the wilderness character 

of the Hells Canyon, Eagle Cap or Monument Rock Wilderness areas. 

Describe any monitoring and reporting requirements: 

Monitoring of all treatment areas will be conducted, as outlined in the EIS, in all areas to determine 

treatment effectiveness and to minimize future treatments. 

Please check any Wilderness Act Section 4(c) uses approved in this alternative: 

 Mechanical transport landing of aircraft 

 Motorized equipment temporary road 

 Motor vehicles structure or installation 

 Motorboats 

Be sure to record and report any authorizations of Wilderness Act Section 4(c) uses according to agency 

procedures. 

 

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Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 Appendix A – Management Direction

 A-22 

Approvals Signature Name Position Date 

Prepared by: 

Recommended: 

Recommended: 

Approved: 
Appendix B – Botany 

Herbicide Effects to Plants by Active Ingredient 

Potential Herbicide Effects to SOLI 

Determination Statements by Alternative for Each Individual SOLI 

Location 

Revegetation Guidelines Document 

 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 

This Page Left Blank Intentionally 

 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B - Botany 

Herbicide Effects to Plants by Active Ingredient 

This section summarizes the effects to plants by active ingredient. Effects are grouped by the mode of 

action (how the ingredient kills a plant). 

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; very low concentrations kill and damage plants. In some 

circumstances, these ingredients could damage non-target species more readily than the other groups of 

herbicides proposed. On the other hand, lower concentrations mean smaller amounts of chemical 

substances are released into the environment. 

The active ingredients and commercial formulations could be difficult to use in areas where native plants 

are a large component of a treatment area. These ingredients could be useful though, in situations where 

an invasive plant is the dominant cover species, or on some aggressive species that have not been 

effectively treated by other methods or herbicides. 

Chlorsulfuron 

Chlorsulfuron (used in Telar or Glean) is both a pre-emergent and post-emergent herbicide (i.e. it 

effectively inhibits seed germination and damages fully emerged plants). It could affect annual, biennial 

and perennial broadleaf species. Drift could cause damage to non-target plants at distances greater than 

900 feet from the application site during a ground based broadcast application. 

Chlorsulfuron is very potent relative to the application rate. The typical application rate proposed by the 

Forest Service for chlorsulfuron is greater than 6,000 times higher than the No Observed Effect 

Concentration (NOEC) in vegetative vigor studies on less tolerant species (sugarbeets and onions) 

(SERA, 2003-chlorsulfuron). This means that extremely small amounts will cause observable damage in 

these species. The risk assessment stated that a very broad range of sensitivities could occur, with grasses 

appearing far more tolerant than most other species. 

The NOEC values for soil exposure used for seedling emergence testing were found to be substantially 

higher than the vegetative vigor studies (i.e. it would take a higher concentration of the ingredient to 

cause an observable effect on emerging seedlings than on vegetative vigor of older plants). Nonetheless, 

offsite movement of chlorsulfuron in runoff could damage non-target plants under conditions that favor 

runoff. In arid regions, wind erosion of treated soil could also result in damage to non-target plants 

(SERA, 2003-chlorsulfuron). 

Chlorsulfuron has been shown to reduce non-target plant reproduction in a study done on cherry trees 

(Fletcher et al., 1993). The authors asserted that cherry tree reproduction displayed high sensitivity even 

when exposed to small quantities of chlorsulfuron, such as might be found in airborne particles traveling 

long distances, without altering vegetative growth. They postulated that drifting sulfonylureas might 

severely reduce both crop yields and fruit development on native plants. The same authors in another 

study compared three herbicides, atrazine, chlorsulfuron, glyphosate at low application rates (within the 

range of reported herbicide drift levels) to four other crop plants. Only chlorsulfuron was found to cause 

reduction in the yields of these crops if plants were exposured at critical stages of development (Fletcher 

et al., 1996). 

Metsulfuron methyl 

Metsulfuron methyl (used in Escort XP) is also a potent herbicide. It affects many broadleaf and woody 

species. 

 B-1
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 Appendix B - Botany

This ingredient could cause damage to non-target plants at distances of up to 500 feet using a ground 

based broadcast application. For metsulfuron methyl, the typical application rate is greater than 800 times 

higher than the NOEC for less tolerant plants (onions) (SERA, 2003). 

The offsite movement of this ingredient in runoff could damage non-target plants under conditions 

favorable to runoff, although this is less likely with metsulfuron methyl than chlorsulfuron. In arid 

regions, wind erosion could also result in damage to non-target species (SERA 2003). 

Sulfometuron methyl 

Sulfometuron methyl (used in Oust) is a broad-spectrum pre- and post-emergent herbicide. It is less 

selective than chlorsulfuron or metsulfuron methyl and is effective against broadleaf and grass species. 

Sulfometuron methyl drift could cause damage to non-target plants at distances greater than 900 feet from 

the application site during a ground based broadcast application. Typical application rate is greater than 

1875 times higher than the NOEC for less tolerant plants. The offsite movement of this ingredient in 

runoff could damage non-target plants under conditions favorable to runoff. This kind of offsite 

movement is more likely with sulfometuron methyl than with chlorsulfuron and metsulfuron methyl. In 

arid regions, wind erosion could also result in damage to non-target species (SERA, 2003). 

Imazapic 

Imazapic (used in Plateau) is a selective herbicide, but even tolerant plants that are directly sprayed at 

normal application rates are likely to be damaged (SERA 2003). Affected plants include annual, 

perennial broadleaf and grass species. Many native bunchgrasses are not affected. Less tolerant species 

can be affected by drift up to 50 feet from ground applications and up to 100 feet from aerial applications. 

In clay soils in areas of relatively high rainfall rates, conditions in which runoff is favored, there could be 

a slight risk to some susceptible terrestrial plants. Imazapic is more selective than imazapyr. It is less 

likely to harm native plants or plant communities. 

Imazapyr 

Imazapyr (used in Arsenal, Chopper and Stalker®) is a non-selective herbicide. Tolerant plants that are 

directly sprayed at normal application rates are likely to be damaged (SERA, 2003-Imazapyr). Less 

tolerant species can be affected by drift up to 500 feet by imazapyr. Imazapyr can also “leak” out of the 

roots of treated plants, and therefore can adversely affect the surrounding native vegetation (Tu et al., 

2001). When applied in areas in which runoff is favored, damage from runoff appears to pose a greater 

hazard than drift. Residual soil contamination could be prolonged in some areas. In arid areas, residual 

toxicity to susceptible plant species could last for several months to several years. Residual 

contamination could be much shorter in areas of relatively high rainfall (SERA, 2003-Imazypyr). 

Synthetic auxins 

Picloram, clopyralid, and triclopyr mimic naturally occurring plant hormones called auxins. They kill 

plants by destroying tissue through uncontrolled cell division and abnormal growth. 

Picloram 

Picloram (used in Tordon®) is selective for broadleaf and woody plants. It could impact non-target 

species particularily sensitive to this chemical at distances of nearly 1000 feet from the application site 

(SERA, 2003-Picloram). 

In their Pesticide Re-registration Fact Sheet (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 

 B-2 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B - Botany 

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, and distant areas where ground water is used for irrigation or 

is discharged into surface water (EPA, 1995). 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, urine may contain enough picloram to injure susceptible plants. To a lesser degree, this can 

occur with other active ingredients such as glyphosate and imazapic. 

Clopyralid 

Clopyralid (used in Transline) is more selective than picloram. As with picloram, clopyralid has little 

effect on grasses, but also does little harm to members of the mustard family. It is effective on the 

sunflower, legume, nightshade, knotweed and violet families. It is less persistent than picloram. Off-site 

drift may cause damage to susceptible plant species at distances of about 300 feet from the application 

site. Wind erosion of treated soil in arid climates could also cause damages in the range of 200 to 900 

feet. Use of clopyralid in a roadside revegetation project had mixed results (Tyser et al., 1988). Native 

grasses increased while native forbs decreased, which is typical for an ingredient that is selective against 

forbs. However, non-native annual grasses increased in this study. 

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). Sensitive 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. 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. 

They found that normal application rates (applied aerially) were found to reduce abundance by 75 

percent, variable by species. Colonists and drought-tolerant species were more resistant 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 four types of 

ectomychorrhizal fungi associated with conifer roots at concentrations of 1,000 parts per million (Estok et 

al., 1989). 

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 susceptible 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 pre-emergent vegetation. 

 B-3
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 Appendix B - Botany

 B-4 

Glyphosate strongly adsorbs to soil, and has a low potential to leaching into groundwater systems (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 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 as well could affect long term sustainability of 

populations of lichens and bryophytes. 

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). 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 

Potential Herbicide Effects to SOLI Herbicide effects are based on specific characteristics of the chemical, the target families, and restrictions of use based o

Regional FEIS guidelines. All methods of application are considered in effects analysis. N = Herbicide would not affect (reasons explained) Y = Herbicide could potentially affect this species and herbicide related PDF’s must be applied.

SOLI 

Chlorsulfuron 

PDFs to 

protect 

individual 

plants from 

direct spray, 

drift, runoff, 

wind erosion. 

No aerial 

application 

Clopyralid 

Targets 

Asteraceae, 

Fabaceae, 

Polygonaceae, 

Solanaceae 

Glyphosate 

Nonselective; 

PDFs to 

protect 

from direct 

sspray; 

runoff not 

a concern 

Imazapic 

Somewhat 

selective 

PDFs to 

protect 

from 

direct 

spray, 

drift, 

runoff and 

timing 

after use 

of other 

herbicides 

Imazapyr 

Nonselective; 

PDF’s to 

protect 

plants 

from 

direct 

spray, 

drift 

runoff 

Metsulfuron 

methyl 

Selective 

for some 

broadleaf 

and woody 

species 

and can 

damage 

conifers 

PDFs to 

protect 

individual 

plants from 

direct 

spray, drift, 

runoff, wind 

erosion. 

No aerial 

application 

Picloram 

Targets 

Asteraceae, 

Fabaceae, 

Polygonaceae, Apiaceae- also 

Brassicaceae, 

Liliaceae, 

Scrophulariaceae 

(less affected) 

PDFs to protect 

from direct spray 

drift, runoff, 

buffers, fall 

application by 

TES plants and 

other special 

situation 

Setho

Sele

for a

an

pere

gras

and t

inva

Achnatherum wallowaensis 

Not sure, assume worst case scenario and apply PDF’s and monitoring to determine potential impacts 

N  Poaceae is not a target and tolerant 

Y Y Y Not sure, 

assume worst case scenario and apply PDF’s and monitoring to determine potential impacts 

Not sure, assume worst case scenario and apply PDF’s and monitoring to determine potential impacts 

Y 

Allium geyeri var. geyeri 

Y N 

Liliaceae is not a target 

Y Y Y Y Y N 

Broadplants toleranthis herbic

Arabis Y N Y Y Y Y Y N 

B-5
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Metsulfuron 

methyl Picloram 

Selective Targets 

Imazapic for some Asteraceae, 

SOLI 

Chlorsulfuron 

PDFs to 

protect 

individual 

plants from 

direct spray, 

drift, runoff, 

wind erosion. 

No aerial 

application 

Clopyralid 

Targets 

Asteraceae, 

Fabaceae, 

Polygonaceae, 

Solanaceae 

Glyphosate 

Nonselective; 

PDFs to 

protect 

from direct 

sspray; 

runoff not 

a concern 

Somewhat 

selective 

PDFs to 

protect 

from 

direct 

spray, 

drift, 

runoff and 

timing 

after use 

of other 

herbicides 

Imazapyr 

Nonselective; 

PDF’s to 

protect 

plants 

from 

direct 

spray, 

drift 

runoff 

broadleaf Fabaceae, 

and woody 

Polygonaceae, 

species Setho

Apiaceae- also 

and can 

Brassicaceae, 

damage 

conifers 

PDFs to 

protect 

individual 

plants from 

direct 

spray, drift, 

runoff, wind 

erosion. 

No aerial 

application 

Liliaceae, 

Scrophulariaceae 

(less affected) 

PDFs to protect 

from direct spray 

drift, runoff, 

buffers, fall 

application by 

TES plants and 

other special 

situation 

Sele

for a

an

pere

gras

and t

inva

hastatula Crucifereaceae is 

not target 

Broadplants toleranthis herbic

Botrychium species: B crenulatum, B. minganese, B. montanum, and B. pinnatum 

Y N 

Ophioglossaceae is not target 

Y Y Y Y Not sure, assume 

worst case scenario and apply all PDF’s 

N Broad leaved plants toleratherbic

Calochortus longebarbatus var. longebarbatus 

Y N 

Liliaceae not target family 

Y Y Y Y Liliaceae less 

susceptible to this herbicide, monitoring indicates no effect 

N Broadplants toleratherbic

Carex hystericina 

Not likely due to species habitat preference for wetter habitat and herbicide 

N Cyperaceae not a target family 

Y Y Y Not sure, 

apply all PDF’s 

Not sure, assume worst case scenario apply all PDF’s 

N, Sedtoleratherbic

 B-6
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 

Metsulfuron 

methyl Picloram 

Selective Targets 

Imazapic for some Asteraceae, 

SOLI 

Chlorsulfuron 

PDFs to 

protect 

individual 

plants from 

direct spray, 

drift, runoff, 

wind erosion. 

No aerial 

application 

Clopyralid 

Targets 

Asteraceae, 

Fabaceae, 

Polygonaceae, 

Solanaceae 

Glyphosate 

Nonselective; 

PDFs to 

protect 

from direct 

sspray; 

runoff not 

a concern 

Somewhat 

selective 

PDFs to 

protect 

from 

direct 

spray, 

drift, 

runoff and 

timing 

after use 

of other 

herbicides 

Imazapyr 

Nonselective; 

PDF’s to 

protect 

plants 

from 

direct 

spray, 

drift 

runoff 

broadleaf Fabaceae, 

and woody 

Polygonaceae, 

species Setho

Apiaceae- also 

and can 

Brassicaceae, 

damage 

conifers 

PDFs to 

protect 

individual 

plants from 

direct 

spray, drift, 

runoff, wind 

erosion. 

No aerial 

application 

Liliaceae, 

Scrophulariaceae 

(less affected) 

PDFs to protect 

from direct spray 

drift, runoff, 

buffers, fall 

application by 

TES plants and 

other special 

situation 

Sele

for a

an

pere

gras

and t

inva

use and buffer restrictions. If treatment allowed follow all PDF’s. 

Carex interior Not likely due 

to species habitat preference for wetter habitat and herbicide use and buffer restrictions. If treatment allowed follow all PDF’s. 

N Cyperaceae not a target family 

Y Y Y Not sure, 

apply all PDF’s 

Not sure, assume worst case scenario apply all PDF’s 

N, Sedtoleratherbic

Carex cordillerana 

Not likely due to species habitat preference for wetter habitat and herbicide use and buffer restrictions. If 

N Cyperaceae not a target family 

Y Y Y Not sure, 

apply all PDF’s 

Not sure, assume worst case scenario apply all PDF’s 

N, Sedtoleratherbic

B-7
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Metsulfuron 

methyl Picloram 

Selective Targets 

Imazapic for some Asteraceae, 

SOLI 

Chlorsulfuron 

PDFs to 

protect 

individual 

plants from 

direct spray, 

drift, runoff, 

wind erosion. 

No aerial 

application 

Clopyralid 

Targets 

Asteraceae, 

Fabaceae, 

Polygonaceae, 

Solanaceae 

Glyphosate 

Nonselective; 

PDFs to 

protect 

from direct 

sspray; 

runoff not 

a concern 

Somewhat 

selective 

PDFs to 

protect 

from 

direct 

spray, 

drift, 

runoff and 

timing 

after use 

of other 

herbicides 

Imazapyr 

Nonselective; 

PDF’s to 

protect 

plants 

from 

direct 

spray, 

drift 

runoff 

broadleaf Fabaceae, 

and woody 

Polygonaceae, 

species Setho

Apiaceae- also 

and can 

Brassicaceae, 

damage 

conifers 

PDFs to 

protect 

individual 

plants from 

direct 

spray, drift, 

runoff, wind 

erosion. 

No aerial 

application 

Liliaceae, 

Scrophulariaceae 

(less affected) 

PDFs to protect 

from direct spray 

drift, runoff, 

buffers, fall 

application by 

TES plants and 

other special 

situation 

Sele

for a

an

pere

gras

and t

inva

treatment allowed follow all PDF’s. 

Erigeron engelmannii var. davisii 

Y Y 

Asteraceaea family is target 

Y Y Y Y Y N 

Broadplants toleranthis herbic

Leptodactylon pungens ssp. hazeliae 

Y N 

Polemoniaceaea not a target family 

Y Y Y Y Not sure, assume 

worst case scenario apply all PDF’s 

N Broadplants toleranthis herbic

Mimulus clivicola 

Y N 

Scrophulariaceae is not a target family 

Y Y Y Y Y N 

Broadplants toleranthis herbic

Mirabilis macfarlanei 

Y N 

Nyctaginaceae is not a target 

Y Y Y Y Not sure, assume 

worst case scenario apply all 

N Broadplants 

 B-8
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 

Metsulfuron 

methyl Picloram 

Selective Targets 

Imazapic for some Asteraceae, 

SOLI 

Chlorsulfuron 

PDFs to 

protect 

individual 

plants from 

direct spray, 

drift, runoff, 

wind erosion. 

No aerial 

application 

Clopyralid 

Targets 

Asteraceae, 

Fabaceae, 

Polygonaceae, 

Solanaceae 

Glyphosate 

Nonselective; 

PDFs to 

protect 

from direct 

sspray; 

runoff not 

a concern 

Somewhat 

selective 

PDFs to 

protect 

from 

direct 

spray, 

drift, 

runoff and 

timing 

after use 

of other 

herbicides 

Imazapyr 

Nonselective; 

PDF’s to 

protect 

plants 

from 

direct 

spray, 

drift 

runoff 

broadleaf Fabaceae, 

and woody 

Polygonaceae, 

species Setho

Apiaceae- also 

and can 

Brassicaceae, 

damage 

conifers 

PDFs to 

protect 

individual 

plants from 

direct 

spray, drift, 

runoff, wind 

erosion. 

No aerial 

application 

Liliaceae, 

Scrophulariaceae 

(less affected) 

PDFs to protect 

from direct spray 

drift, runoff, 

buffers, fall 

application by 

TES plants and 

other special 

situation 

Sele

for a

an

pere

gras

and t

inva

family PDF’s toleran

this herbic

Phacelia minutissima 

Y N 

Hydrophyllaceae is not a target family 

Y Y Y Y Not sure, assume 

worst case scenario apply all PDF’s 

N Broadplants toleranthis herbic

Phlox multiflora 

Y N 

Polemoniaceae is not target family 

Y Y Y Y Not sure, assume 

worst case scenario apply all PDF’s 

N Broadplants toleranthis herbic

Platanthera obtusata 

Y N 

Orchidaceae is not a target family 

Y Y Y Y Not sure, assume 

worst case scenario apply all PDF’s 

N Broadplants toleranthis herbic

Primula cusickiana 

Y N 

Primulaceae is not a target 

Y Y Y Y Not sure, assume 

worst case scenario apply all 

N Broadplants 

B-9
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Metsulfuron 

methyl Picloram 

Selective Targets 

Imazapic for some Asteraceae, 

SOLI 

Chlorsulfuron 

PDFs to 

protect 

individual 

plants from 

direct spray, 

drift, runoff, 

wind erosion. 

No aerial 

application 

Clopyralid 

Targets 

Asteraceae, 

Fabaceae, 

Polygonaceae, 

Solanaceae 

Glyphosate 

Nonselective; 

PDFs to 

protect 

from direct 

sspray; 

runoff not 

a concern 

Somewhat 

selective 

PDFs to 

protect 

from 

direct 

spray, 

drift, 

runoff and 

timing 

after use 

of other 

herbicides 

Imazapyr 

Nonselective; 

PDF’s to 

protect 

plants 

from 

direct 

spray, 

drift 

runoff 

broadleaf Fabaceae, 

and woody 

Polygonaceae, 

species Setho

Apiaceae- also 

and can 

Brassicaceae, 

damage 

conifers 

PDFs to 

protect 

individual 

plants from 

direct 

spray, drift, 

runoff, wind 

erosion. 

No aerial 

application 

Liliaceae, 

Scrophulariaceae 

(less affected) 

PDFs to protect 

from direct spray 

drift, runoff, 

buffers, fall 

application by 

TES plants and 

other special 

situation 

Sele

for a

an

pere

gras

and t

inva

family PDF’s toleran

this herbic

Rubus bartonianus 

Y N 

Rosaceae is not a target family 

Y Y Y Y Not sure, assume 

worst case scenario apply all PDF’s 

N Broadplants toleranthis herbic

Trifolium douglasii 

Y Y 

Fabaceae is target family 

Y Y Y Y Not sure, assume 

worst case scenario apply all PDF’s 

N, broadplants toleratherbic

Trollius laxus Y N 

Ranunculaceae is not a target family 

Y Y Y Not sure, 

assume worst case scenario and apply PDF’s and monitoring 

Not sure, assume worst case scenario apply all PDF’s 

N Broadplants toleranthis herbic

 B-10
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 

B-11

SOLI 

Chlorsulfuron 

PDFs to 

protect 

individual 

plants from 

direct spray, 

drift, runoff, 

wind erosion. 

No aerial 

application 

Clopyralid 

Targets 

Asteraceae, 

Fabaceae, 

Polygonaceae, 

Solanaceae 

Glyphosate 

Nonselective; 

PDFs to 

protect 

from direct 

sspray; 

runoff not 

a concern 

Imazapic 

Somewhat 

selective 

PDFs to 

protect 

from 

direct 

spray, 

drift, 

runoff and 

timing 

after use 

of other 

herbicides 

Imazapyr 

Nonselective; 

PDF’s to 

protect 

plants 

from 

direct 

spray, 

drift 

runoff 

Metsulfuron 

methyl 

Selective 

for some 

broadleaf 

and woody 

species 

and can 

damage 

conifers 

PDFs to 

protect 

individual 

plants from 

direct 

spray, drift, 

runoff, wind 

erosion. 

No aerial 

application 

Picloram 

Targets 

Asteraceae, 

Fabaceae, 

Polygonaceae, Apiaceae- also 

Brassicaceae, 

Liliaceae, 

Scrophulariaceae 

(less affected) 

PDFs to protect 

from direct spray 

drift, runoff, 

buffers, fall 

application by 

TES plants and 

other special 

situation 

Setho

Sele

for a

an

pere

gras

and t

inva

to determine potential impacts 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement

Appendix B - Botany

Determination Statements by Alternative for each individual SOLI 

location 

Determination statements 

derived from impacts from 

invasive plant treatments in 

combination with treatment 

effectiveness Site No GENUS SPECIES 

Invasive 

Plant 

Code 

Alt A Alt B Alt C Alt D 

Proposed 

treatment 

for 

Alternative 

B, C and D 

1st choice. 

Other 

methods 

also 

available 

0616020241 Achnatherum wallowaensis CEMA4 MIIH MIIH MIIH MIIH Chemical 

0616020502 Achnatherum wallowaensis CEDI3 MIIH MIIH MIIH MIIH Chemical 

0616041176 Allium geyeri CEDI3 MIIH MIIH MIIH MIIH Chemical 

0616041252 Arabis hastatula CEDI3 MIIH MIIH MIIH MIIH Chemical 

0616041347 Arabis hastatula CEDI3 MIIH MIIH MIIH MIIH Chemical 

0616012117 Botrychium crenulatum HYPE MIIH MIIH MIIH MIIH Chemical 

0616012102 Botrychium minganense HYPE MIIH MIIH MIIH MIIH Chemical 

0616012103 Botrychium minganense HYPE MIIH MIIH MIIH MIIH Chemical 

0616012118 Botrychium minganense CIAR4 MIIH MIIH MIIH MIIH Chemical 

0616060138 Botrychium minganense CEDI3 MIIH MIIH MIIH MIIH Chemical 

0616062224 Botrychium minganense CIAR4 MIIH MIIH MIIH MIIH Chemical 

0616012115 Botrychium montanum HYPE MIIH MIIH MIIH MIIH Chemical 

0616012124 Botrychium montanum HYPE MIIH MIIH MIIH MIIH Chemical 

0616012126 Botrychium montanum HYPE MIIH MIIH MIIH MIIH Chemical 

0616060178 Botrychium montanum CIAR4 MIIH MIIH MIIH MIIH Chemical 

0616062223 Botrychium montanum CIAR4 MIIH MIIH MIIH MIIH Chemical 

0616062225 Botrychium montanum CIAR4 MIIH MIIH MIIH MIIH Chemical 

0616012104 Botrychium pinnatum HYPE MIIH MIIH MIIH MIIH Chemical 

0616012125 Botrychium pinnatum HYPE MIIH MIIH MIIH MIIH Chemical 

0616012213 Botrychium pinnatum HYPE MIIH MIIH MIIH MIIH Chemical 

0616060158 Botrychium pinnatum SEJA MIIH MIIH MIIH MIIH Chemical 

0616060016 Calochortus longebarbatus CEDI3 MIIH MIIH MIIH MIIH Chemical 

0616060115 Calochortus longebarbatus CIAR4 MIIH MIIH MIIH MIIH Chemical 

0616060131 Calochortus longebarbatus CIAR4 MIIH MIIH MIIH MIIH Chemical 

0616060943 Calochortus longebarbatus CEDI3 MIIH MIIH MIIH MIIH Chemical 

0616060952 Calochortus longebarbatus CEDI3 MIIH MIIH MIIH MIIH Chemical 

0616040513 Calochortus macrocarpus CEDI3 MIIH MIIH MIIH MIIH Chemical 

0616041078 Carex hystericina CEMA4 MIIH MIIH MIIH MIIH Manual 

0616041364 Carex hystericina CEMA4 MIIH MIIH MIIH MIIH Chemical 

0616012151 Carex interior CIAR4 MIIH MIIH MIIH MIIH Chemical 

0616062226 Carex interior CIAR4 MIIH MIIH MIIH MIIH Chemical 

0616020247 Erigeron engelmannii CEDI3 MIIH MIIH MIIH MIIH Chemical 

0616020248 Erigeron engelmannii CEDI3 MIIH MIIH MIIH MIIH Chemical 

0616020249 Erigeron engelmannii CEDI3 MIIH MIIH MIIH MIIH Chemical 

0616020250 Erigeron engelmannii CEDI3 MIIH MIIH MIIH MIIH Chemical 

0616020251 Erigeron engelmannii CEDI3 MIIH MIIH MIIH MIIH Chemical 

0616021357 Erigeron engelmannii ONAC MIIH MIIH MIIH MIIH Chemical 

0616022087 Erigeron engelmannii ONAC MIIH MIIH MIIH MIIH Chemical 

0616022088 Erigeron engelmannii CEDI3 MIIH MIIH MIIH MIIH Chemical 

0616022089 Erigeron engelmannii CESO3 MIIH MIIH MIIH MIIH Chemical 

0616022090 Erigeron engelmannii CESO3 MIIH MIIH MIIH MIIH Chemical 

0616040469 Erigeron engelmannii CESO3 MIIH MIIH MIIH MIIH Chemical 

0616040480 Erigeron engelmannii ONAC MIIH MIIH MIIH MIIH Chemical 

0616040216 Leptodactylon pungens CEDI3 MIIH MIIH MIIH MIIH Chemical 

0616041141 Leptodactylon pungens CESO3 MIIH MIIH MIIH MIIH Chemical 

0616012134 Mimulus clivicola CYOF MIIH MIIH MIIH MIIH Chemical 

0616040294 Mimulus clivicola CIAR4 MIIH MIIH MIIH MIIH Chemical 

 B-12 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B - Botany 

Determination statements 

derived from impacts from 

invasive plant treatments in 

combination with treatment 

effectiveness Site No GENUS SPECIES 

Invasive 

Plant 

Code 

Alt A Alt B Alt C 

Proposed 

treatment 

for 

Alternative 

B, C and D 

1st choice. 

Other 

methods Alt D 

also 

available 

0616040295 Mimulus clivicola CIAR4 MIIH MIIH MIIH MIIH Chemical 

0616040296 Mimulus clivicola CIAR4 MIIH MIIH MIIH MIIH Chemical 

0616040297 Mimulus clivicola HYPE MIIH MIIH MIIH MIIH Chemical 

0616040382 Mimulus clivicola CIAR4 MIIH MIIH MIIH MIIH Chemical 

0616040385 Mimulus clivicola CIAR4 MIIH MIIH MIIH MIIH Chemical 

0616040539 Mimulus clivicola CEDI3 MIIH MIIH MIIH MIIH Chemical 

0616041039 Mimulus clivicola CIAR4 MIIH MIIH MIIH MIIH Chemical 

0616041045 Mimulus clivicola CIAR4 MIIH MIIH MIIH MIIH Bio-control 

0616041109 Mimulus clivicola HYPE MIIH MIIH MIIH MIIH Chemical 

0616041391 Mimulus clivicola HYPE MIIH MIIH MIIH MIIH Chemical 

0616041392 Mimulus clivicola HYPE MIIH MIIH MIIH MIIH Chemical 

0616040488 Mirabilis macfarlanei CESO3 LAA LAA LAA LAA Chemical 

0616040494 Mirabilis macfarlanei ONAC LAA LAA LAA LAA Chemical 

0616040217 Phacelia minutissima CIAR4 MIIH MIIH MIIH MIIH Chemical 

0616060123 Phlox multiflora CEDI3 MIIH MIIH MIIH MIIH Chemical 

0616060149 Phlox multiflora CIAR4 MIIH MIIH MIIH MIIH Chemical 

0616060150 Phlox multiflora CADR MIIH MIIH MIIH MIIH Chemical 

0616060151 Phlox multiflora CIAR4 MIIH MIIH MIIH MIIH Chemical 

0616060152 Phlox multiflora CIAR4 MIIH MIIH MIIH MIIH Chemical 

0616050462 Platanthera obtusata CEMA4 MIIH MIIH MIIH MIIH Chemical 

0616020286 Primula cusickiana CEMA4 MIIH MIIH MIIH MIIH Chemical 

0616020292 Primula cusickiana CYSC4 MIIH MIIH MIIH MIIH Chemical 

0616020339 Primula cusickiana CYSC4 MIIH MIIH MIIH MIIH Bio-control 

0616040300 Primula cusickiana HYPE MIIH MIIH MIIH MIIH Chemical 

0616041212 Primula cusickiana CIAR4 MIIH MIIH MIIH MIIH Chemical 

0616040218 Rubus bartonianus CESO3 MIIH MIIH MIIH MIIH Chemical 

0616040380 Rubus bartonianus LIDA MIIH MIIH MIIH MIIH Chemical 

0616060859 Trifolium douglasii PORE5 MIIH MIIH MIIH MIIH Chemical 

0616060860 Trifolium douglasii PORE5 MIIH MIIH MIIH MIIH Chemical 

0616060941 Trifolium douglasii CIAR4 MIIH MIIH MIIH MIIH Chemical 

0616060942 Trifolium douglasii CEDI3 MIIH MIIH MIIH MIIH Chemical 

0616062299 Trifolium douglasii CIAR4 MIIH MIIH MIIH MIIH Chemical 

0616040210 Trollius laxus CEDI3 MIIH MIIH MIIH MIIH Chemical 

 B-13
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement

Appendix B - Botany

 B-14 

Revegetation Guidelines Document 

United States 

Department 

Agriculture 

Forest Service 

Pacific 

Northwest 

Region 

2003 

Guidelines for Revegetation of Invasive Weed Sites 

and Other Disturbed Areas on National Forests and 

Grasslands in the Pacific Northwest 

Vicky J. Erickson 

Jean Wood 

Scott A. Riley 

 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B - Botany 

B-15

Introduction 

This document provides methods and guidance for revegetation of invasive weed sites and other disturbed 

areas on National Forests and Grasslands in the Pacific Northwest (Region 6). Steps are outlined for 

assessing existing and potential site conditions, and for developing long-term revegetation strategies that 

are effective, affordable, and consistent with the ecological context and land management objectives of 

the site and surrounding landscape. The need for this document was driven by relatively new policies and 

programs that promote the use of native plant materials in revegetation projects (Appendix A,B). 

Historically, resource managers in the western United States have relied on introduced species (e.g., 

smooth brome, orchardgrass, timothy, crested wheatgrass) that have been selectively bred for 

characteristics that, at least in the short-term, made them logical choices for revegetation projects. 

Although some introduced species will continue to play an important role in site restoration, it has 

become increasingly clear that the widespread and excessive use of highly competitive and persistent nonnative species has had adverse impacts on the diversity and health of our native forest, rangeland, and 

aquatic ecosystems (Detwyler 1971; Covington and Moore 1994; Kaufmann et al. 1994; Kay 1994; Mills 

et al. 1994; Brown 1995, Lesica and DeLuca 1996; Bartos and Campbell 1998; Schoennagel and Waller 

1999; Brown and Rice 2000) As a consequence, new direction for revegetation projects strives for a 

balance between rapid establishment of high levels of competitive plant cover, and broader, more longterm objectives aimed at restoring inherent ecosystem properties (e.g., genetic and species diversity, 

vegetation structure) and processes (e.g., disturbance regimes, succession patterns, hydrologic regimes, 

and nutrient cycles). 

Revegetation with carefully selected plant materials is a critical component of integrated weed 

management strategies. Commonly used control tactics, such as manual or chemical treatments, may 

eliminate or suppress invasive species in the short term, but the resulting gaps and bare soil create open 

niches that are susceptible to further invasion by the same or other undesirable plant species (Westman 

1990; Jacobs et al. 1999; D’Antonio and Meyerson 2002). On degraded weed sites where reproducing 

individuals of desirable species are absent or in low abundance, revegetation with well-adapted and 

competitive grasses, forbs, and legumes can be used to direct and accelerate plant community recovery, 

and achieve site management objectives in a reasonable timeframe (Hobbs and Mooney 1993; Sheley et 

al. 1996, Brown and Amacher 1998). This document incorporates a landscape ecology approach to 

revegetation that first considers and prioritizes individual projects in the context of watershed scales. 

More fine-scale elements of a successful revegetation design are also addressed, including evaluation of 

existing and potential site conditions, identification of realistic site goals, and development and 

implementation of appropriate action strategies. Because the science and practice of restoration is rapidly 

evolving, and the potential and most effective usage of many native species has not been fully explored, 

an experimental approach to revegetation is advocated. Sections and references on monitoring principles 

and techniques are therefore included to provide tools for resource specialists to evaluate the efficacy of 

alternative revegetation treatments, and gain insights into how methods may be refined to better achieve 

desired outcomes (i.e., adaptive management). 

The recommendations in this document follow National and Regional Forest Service authorities and 

policy guidelines (see Appendix A, B), and are intended to provide a conceptual framework from which 

site-specific revegetation prescriptions can be developed. A number of sections, including the Decision 

Matrix and Site Prescriptions, were initially developed by resource specialists on the Siuslaw National 

Forest (Region 6), and refined and augmented by multi-Forest revegetation teams in Region 2 in 

cooperation with the National Park Service (http://fsweb.arnfpng.r2.fs.fed.us/). Detailed treatment 

descriptions and management scenarios are beyond the scope of this document, and specialists including 

District and Forest botanists, silviculturists, geneticists, ecologists, soil scientists, and range 

conservationists should be consulted as necessary to refine revegetation prescriptions and identify the 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B-Botany 

 B-16 

most appropriate plant materials (species and seed sources) and revegetation methods for a particular site. 

Restoration of disturbed sites should be approached as a multi-disciplinary effort, and will be most 

successful when local knowledge and expertise are fully utilized and integrated into comprehensive 

revegetation strategies. 

Revegetation in a Landscape Context 

Revegetation programs and strategies should be developed using a landscape ecology approach that 

considers individual projects in the context of watershed scales. Thus, revegetation of invasive weed sites 

should fit into broader ecological strategies that address other major restoration issues of a given 

watershed, including departures from historical vegetative conditions, at-risk aquatic/wildlife/plant 

species, hydrology, uncharacteristic wildfire risks, etc.. Projects can then designed and prioritized so that 

they contribute to the overall goals for the particular watershed or landscape planning area. In addition, 

efforts should be taken to ensure that revegetation projects are fully integrated with the suite of other 

ongoing resource management projects, both spatially and temporally. One obvious example is that weed 

control operations must be tightly linked and coordinated with post-removal revegetation plans. A 

landscape ecology approach to revegetation also requires a thorough understanding of the underlying 

problems contributing to the need for revegetation, and how they interact with other processes within the 

watershed. This may be accomplished through assessments of the larger landscape area and its 

connection to the problem site. A key question is whether the site problem is unique, or symptomatic of 

other problems within the watershed that need to be addressed at a larger scale. Finally, in an era where 

the extent and intensity of management is declining and more aligned with natural processes, revegetation 

projects must be compatible with the dominant disturbance processes of the site and surrounding area 

(e.g., wildfire cycles, herbivory). 

Some of the major issues to consider during the development of landscape-scale revegetation strategies 

for invasive weed sites include: 

 (the following section is not compete)

The current extent and patterns of spread of invasive species: Design projects to cut off or slow the spread 

paths and corridors using spatial strategies similar to those of wildfire management. Interrupt dominant 

vectors to minimize the degree and rate of propagule spread. Identify recurring points of invasion (e.g., 

roads/trails); revegetate the sites with highly competitive species. Tier revegetation to control 

prioritization scheme. Because funding for invasive spp. management efforts is typically limited, it is 

essential to prioritize revegetation of sites occupied by species and populations that are most important to 

control. Prioritization should be based on impacts of invader species, site characteristics, and potential for 

success. 

Grazing and hydrologic issues in riparian systems: Revegetion species should be chosen based on 

consideration of site and landscape level aquatic strategies and goals. Utilize the Rosgen or other 

hydrologic classification schemes to determine succession on the stream and physical site characteristics 

to help select species for revegetation that will be compatible with the dominant hydrologic disturbance 

processes. Design projects with hydrologic disturbance in mind. Ungulate herbivory can be the dominate 

disturbance process (e.g., in the Blue Mountains) and must be factored into design and cost of 

revegetation. 

Historical range of variability (HRV) and degree of departure: Quantify historical range and variability of 

landscape pattern dynamics to assess current landscape conditions and define limits of acceptable change. 

Design appropriate landscape vegetation treatments consistent with overarching ecosystem management 

goals. In upland settings, consider implications of fire regime (e.g., low intensity, frequent return interval 

versus infrequent high intensity). In high intensity fire areas, for example, revegetation efforts may 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B - Botany 

B-17

emphasize use of species that disperse and spread rapidly, have high seed production, and are tolerant of 

fire. 

Site Assessment 

Following the development of larger scale landscape strategies, site assessment is the next critical phase 

in the design of a successful revegetation project. There are 3 primary steps in determining whether a 

given site requires active revegetation. These include: 

• Evaluation of site history and existing conditions 

• Defining land management and site goals 

• Determining the need for action 

Site History and Existing Conditions: 

The evaluation of existing site conditions involves first determining what resources or values are at risk 

from degradation of the site. Example of site risks to be considered include: (1) erosion and soil loss 

potential, (2) the likelihood of invasion or re-invasion by undesirable plant species, (3) loss of cultural, 

visual, or social values, and (4) potential effects on threatened, endangered, or sensitive (TES) species, 

and their forage and habitat. 

Site dominated by invasive weed species may have an increased risk of surface run-off and soil erosion 

due to the loss of vegetative cover and native plants that have inherent soil stabilizing growth habits (e.g., 

extensive fibrous root systems). Risk of erosion will be higher on steep slopes (>40-50%) and sites with 

crusted, shallow, compacted, or highly erodible soils. Erosion can have negative effects on “downstream” 

ecosystem processes and species through sediment transport and deposition. On site, loss of the soil 

surface layer may strongly affect the degree and speed of revegetation due to depletion of organic matter, 

water holding capacity, and critical nutrient reserves. 

Risk of noxious weed invasion or re-invasion on a site is largely dependent on the abundance of 

undesirable species in the seed bank, the size and proximity of surrounding weed populations, the ease of 

seed movement to the site, and the growth and spread characteristics of any adjacent weed species 

(D’Antonio and Meyerson 2002). For example, a population of an aggressive knapweed less than a 

quarter mile down a well-traveled road renders a site highly susceptible to invasion. In contrast, a site 

surrounded by several miles of dense forest that separates it from a population of a rhizomatous weed 

species such as white top is at fairly low risk of invasion. Loss of native vegetative cover may negatively 

impact the availability and abundance of culturally important medicinal or food species. Artifacts present 

in the soil also may be at risk of being disturbed or transported by soil erosion accompanying the loss of 

vegetative cover. Aesthetics and recreational quality are diminished by patches of bare soil, as well as by 

unattractive invasive plants that have sharp spines or thorns. Wildlife species have co-evolved with native 

plant species and are highly dependent on them for food, or cover, or both. Of special concern are TES 

species that may be directly or indirectly affected by degraded vegetative conditions resulting from weed 

invasions. For example, listed fish species may be adversely affected by altered seasonal water flows or 

by increased sediment loads in streams due to erosion of disturbed weed sites. Propagules from weed 

sites in close proximity to special management areas of high social or ecological value can disperse and 

become established in the pristine habitats that often harbor TES plant species. Finally, revegetation of 

invasive weed sites with aggressive non-native cover species may unintentionally introduce equally 

invasive, though not officially designated as noxious, plants into the vicinity of TES plant populations 

resulting in excessive competition with rare native species that are already in decline or at risk of 

extirpation. 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B-Botany 

 B-18 

In additional to risk assessment, it is also important to determine the causes of site degradation. Broad 

categories include soil disturbance, loss of native species, and loss of whole plant communities whose 

structure normally regulates the processes of nutrient cycling and water retention. Within these broad 

categories, the agents contributing to disturbance and their relationship to ecosystem degradation should 

be identified and evaluated in terms of their continued presence and ongoing effects. For instance, if road 

construction has disturbed soils in the past, is the road still maintained (bladed annually, subject to ditch 

cleaning, sprayed annually to control existing weed infestations), or has it been closed or even 

obliterated? Or, if native plants have been lost due to heavy grazing pressure by domestic or wild 

ungulates, do those animals still have access to the area? Revegetation, especially with native species, is 

difficult to impossible in the face of continuing disturbance. Passive restoration (the removal of the 

disturbing agent so that unassisted site recovery can take place) will be the simplest and most costeffective step towards revegetation of some sites, and is requisite to the success of active revegetation 

methods. 

Desired Future Condition:

Defining revegetative goals, or desired future condition, for a given site is a crucial step in site 

assessment. In many cases, the recovery of natural ecosystem processes and pre-disturbance conditions, 

or some close approximation, will be assumed as the preferred state. This suggests a plant community that 

is structurally diverse, fully functioning in all ecosystem processes, and consisting of locally adapted 

native species. A knowledgeable botanist or a plant ecologist should be consulted at this stage to help in 

identifying realistic goals for site revegetation. In some cases, such as in the presence of ongoing 

degradation or large-scale infestations, complete recovery to pre-disturbance conditions may not be an 

appropriate objective. Revegetation goals must also be realistic, both in the sense that they may actually 

be achieved, and that they are affordable. Some common and overarching goals for revegetation of 

National Forests and Grasslands include: 

Contribute to the restoration of ecosystem structure and function. 

Minimize or contain surface erosion, particularly if the project or downstream area is susceptible to 

impacts of erosion and/or sedimentation. 

Maintain or re-establish nutrient cycling as quickly as possible through establishment of desirable 

vegetative cover for nutrient uptake, and placement of woody debris or mulch for nutrient input. 

Avoid or minimize stream or riparian area sedimentation 

Exclude noxious weeds and undesirable non-native species by revegetating sites with local native species 

or non-persistent cover crops that will not be overly competitive with native vegetation in the target area.

Give special consideration to sites of high ecological or social value, and areas containing TES species or 

habitat. Revegetation with local native species (local ecotypes) is a high priority within intact and pristine 

ecosystems, core conservation areas, and their buffers and connecting corridors. 

Need For Action:

Determining the need for action on a specific site requires consideration of the potential for natural 

recovery. For example, is there adequate moisture available to support natural regeneration, sprouting, 

and establishment of native vegetation within a reasonable period of time? The degree of disturbance, as 

indicated by the proportion of the existing plant cover that consists of desirable native species, will also 

affect revegetation outcome. Ten to twenty percent native cover is considered a minimum required to 

facilitate natural recovery of a site (James 1992, Sheley et al. 1996, Goodwin and Sheley 2003). The 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B - Botany 

B-19

diversity, abundance, and viability of plant propagules of desirable species in the seed bank or within the 

immediate vicinity are additional important determinants in natural recruitment and recovery. A novel 

method for quantifying site disturbance and the potential for natural recovery based on the plant cover of 

individual species, and their longevity and native/non-native status is described in McArthur et al. (1995). 

The formula1

 could easily be modified to incorporate information on additional life history traits such as 

root morphology (e.g,. rhizomatous vs. non-rhizomatous) and seral status. Sites dominated by propagule 

pools of early seral (pioneering) native species are predicted to have the greatest likelihood of natural 

colonization and recovery, while those reliant on late seral species for regeneration or dominated by 

undesirable rhizomatous species will generally be less successful. 

The size of the invasion and the length of time that weeds have been present may strongly influence 

revegetation strategies and the need for active manipulations. Very small sites are the most easily recolonized by the extant seed bank and by plant propagules dispersed from surrounding sources. 

Depending on the ecological setting, it is reasonable to allow revegetation to occur on its own on sites less 

than about 0.25 acres, or to possibly assist natural recovery through the redistribution of seed from 

surrounding plants by hand. The longer the site has been occupied by invasive plants, the greater the 

potential for the seed bank to become dominated by undesirable species, and for chemical or physical 

changes in soil conditions (e.g., shifts in nitrogen pools and pH) and associated microbial communities 

that may adversely affect species replacement dynamics and natural site recovery (Evans et al. 2001; 

Svejcar and Sheley 2001; D’Antonio and Meyerson 2002). 

Other soil conditions influencing outcome include the degree of substrate disturbance (loss or mixing of 

soil horizons) and seedbed physical characteristics, including the extent of crusting and compaction. As 

fertility and water holding capacity are lost with the A and B soil horizons it becomes increasingly 

difficult to establish vegetation. Regardless of the method of regeneration, cultural amendments and 

manipulations may be required on highly degraded sites to help decrease the competitive advantage of 

exotic species, and improve the number and condition of regeneration sites available for germination and 

root extension of desired species. Examples include topsoil replacement, incorporation of organic matter, 

mulching, seedbed disking and imprinting to aid water infiltration and soil aeration, liming to adjust pH, 

and nutrient enhancements/manipulations. An experimental technique of great promise in Bromus 

tectorum dominated communities is the application of sucrose to reduce plant-available nitrogen and 

create a soil environment more conducive to the establishment of native perennial vegetation (McLendon 

and Redente 1992; Young et al. 1999;Paschke et al. 2000). 

Selection of Plant Materials 

Regional Priorities and Guidelines:

When site assessment indicates a need for active revegetation, the next critical step is to determine the 

species and seed sources that will establish and perform well on the site without impeding natural 

community recovery and succession, or compromising the diversity, genetic integrity, and long-term 

viability of resident wild populations. The potential risks and impacts of revegetation treatments are 

greatest for seeding and planting projects that involve large acreages, or that occur in or near management 

areas of high social or ecological value. In 1994, Region 6 formulated revegetation policy that set 

general guidelines and priorities for plant material usage in disturbed areas on national forests and 

grasslands, including sites occupied by invasive exotic plants (see Appendix B). Regional priorities, as 

well as definitions and rational, are as follows: 

 

1

 Disturbance value = Sum[Cover*(Longevity-Origin Scores)]/Number of Species. Longevity: 1=annual, 

2=biennial, 3=biennial to perennial, 4=perennial. Origin: 1=native to local area, 2=exotic to the area, but native to 

North America, 3=exotic to North America. 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B-Botany 

 B-20 

Priority 1 - Local Native: Plant materials of native species that originate from genetically local sources. 

Benefits of use include high adaptation to spatial and temporal extremes, and low input requirements 

(e.g., supplemental water, fertilizer). Local native plant materials are recommended for projects of all 

sizes (Fig. 1, adapted from Lesica and Allendorf 1999), especially in and around pristine or relatively 

intact habitats and ecosystems such as designated or proposed wilderness, roadless areas, wild and scenic 

river corridors, Research Natural Areas (RNAs), Special Interest Areas (SIAs), riparian areas, wetlands, 

cultural use areas, TES species habitat and connecting corridors, etc. For severe and large-scale 

disturbances, a mixture of genotypes or seed sources from ecologically different populations has been 

suggested as a strategy for maximizing genetic variation and enhancing the likelihood of plant 

establishment and persistence in stressful environments (Fig. 1, adapted from Lesica and Allendorf 1999).

Fig. 1. Relationship between size and degree of disturbance and 

primary and secondary preferences for plant material for 

revegetation on National Forests and Grasslands in Region 6. 

(Adapted from Lesica and Allendorf 1999). 

The ecological and geographic boundaries 

that define a local population are 

determined primarily by the heterogeneity 

of the climate and habitat, the genetic 

structuring of the populations, the extent 

of local adaptation, and the consequences 

of mixing distant gene pools (Fenstar and 

Dudash 1994; Knapp and Rice 1994; 

Linhart 1995; Montalvo et al. 1997; 

Lesica and Allendorf 1999; Hufford and 

Mazer 2003). Although seed zones and 

transfer guidelines have been developed 

for most Pacific Northwest conifer species 

(USDA 1973; Randall and Berrang 2002), 

such information is generally lacking for 

other native plant species. As a 

consequence, elevational restrictions 

along with existing spatial frameworks 

such as EPA ecoregions, 5th field watersheds, 

and conifer seed zones are frequently used to 

guide seed movement in native shrubs, 

grasses, and forbs (Erickson et al., submitted). In the absence of supporting genetic data, the spatial scale 

of seed mixing and movement in the Pacific Northwest should be limited to geographic areas on the order 

of Level III ecoregions (Fig. 2; Omernik 1987, 1995), with additional restrictions based on elevation, cold 

hardiness, and local precipitation patterns. Area geneticists should be consulted for guidance in 

determining the most appropriate genetic sources of plant material for a particular restoration site. 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B - Botany 

B-21

Figure 2. Relationship between Level III ecoregions (in color) and R6 National Forest 

boundaries (outlined in black). 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B-Botany 

 B-22 

Use of local sources of native seed requires carefully coordinated and integrated programs to ensure 

adequate quantities of suitable seed are available at critical times for project work. A new 5-year 

Regional contract for native grass and forb seed production (53-04R3-03-14, 

http://www.fs.fed.us/r6/uma/native/) will help facilitate this process at reasonable cost. Table C-1 

(Appendix C) contains seed yield and cost figures for native grass and forb species included in the 

contract. Table C-2 (Appendix C) describes ecological attributes and suggested seeding rates for a broad 

array of native species that have successfully been used in revegetation projects in the Pacific Northwest. 

Priority 2 - Preferred Non-Native: The volume of seed needed for large-scale restoration may at times 

preclude the use of local native seed, particularly for unplanned events such as wildfires, or other 

disturbances where it is critical to quickly establish vegetation in order to protect basic resources values 

and prevent weed invasions. In these instances, a second choice would be sterile hybrids or 

annuals/biennial/perennial introduced plant species that are non-persistent and non-invasive (Fig.1, 

adapted from Lesica and Allendorf 1999). Preferred non-native species are those that will not 

aggressively compete with the naturally occurring native plant community, will not invade plant 

communities outside the project area, persist in the ecosystem over the long term, or exchange genetic 

material with local native plant species. Appendix D includes recommendations for non-native species 

that may be seeded as temporary ground cover for both erosion control and as noxious weed competitors 

until native species can become established and occupy the site. The list includes sterile hybrids, such as 

REGREEN and annuals such as white oats (Avena sativa) and winter wheat (Triticum aestivum). A more 

complete list of perennial non-natives that are suitably non-persistent may be developed on 

Districts/Forests by examining past revegetation efforts where the seeded species are known. Exotic 

species that have not already been introduced into the area, or that have been found to be aggressive 

and/or persistent, should be avoided. Table E-1 (Appendix E) provides a listing of non-native species 

that, although commonly used in the past, are generally no longer recommended due to their highly 

aggressive nature that has resulted in widespread loss or displacement of native species and plant 

communities in western wildlands. These include Kentucky bluegrass (Poa pratensis); smooth brome 

(Bromus inermis); crested wheatgrass (Agropyron cristatum); orchard grass (Dactylis glomerata); yellow 

and white sweetclover (Melilotus officinale and M. albus); alsike clover (Trifolium hybridum) and alfalfa 

(Medicago sativa to name a few. As a last resort, some of these “species-to-avoid” may play a limited 

role in revegetation of small, highly degraded sites where there is poor potential for native plant 

community recovery, or in settings where there is little risk of spread beyond the original site of 

introduction (e.g., seeding around buildings on administrative sites). 

Priority 3 - Non-local Native: This category includes native species that do not occur naturally in 

the local ecosystem, or native plant material that does not originate from genetically local sources. These 

types of plant materials, including most commercial cultivars (Table E-2, Appendix E), are generally not 

preferable for wildland use due to concerns over adaptability, genetic diversity level, and the potential for 

genetic contamination or “swamping” of local native gene pools, including those of TES plants (Millar 

and Libby 1989; Knapp and Rice 1994; Linhart 1995; Montalvo et al. 1997; Lesica and Allendorf 1999; 

Hufford and Mazer 2003). Because commercial cultivars are typically selected for agronomic traits such 

as high fecundity, vegetative vigor, and competitive ability, their use may also adversely impact resident 

natural populations through direct competition and displacement. Moreover, cultivars of native species 

(and introduced look-alikes such as sheep fescue, Festuca ovina) can be very difficult to distinguish from 

native germplasm, which could severely complicate efforts to collect and propagate local material and 

waste valuable economic resources. Because of these concerns, cultivars are recommended for use only 

on small, highly disturbed sites (Fig. 1, adapted from Lesica and Allendorf 1999) that are not in close 

proximity to areas of high social or ecological value such as designated or proposed wilderness areas; 

Research Natural Areas (RNAs); Special Interest Areas (SIAs), TES species habitat or corridors, and 

riparian/wetland areas. Where cultivars have been used, it is important to document and map their 

locations so these areas can be avoided during seed harvesting activities. 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B - Botany 

B-23

Designing Seed Mixes

The design of an effective seed mixes incorporates a number of factors, including land-use objectives and 

site characteristics such as existing and potential vegetation, weed density and biomass, 

precipitation/temperature regimes, soil characteristics, and shade conditions. In addition, short-term 

objectives of quick establishment of competitive plant cover must be balanced with more long-term goals 

of restoring fully functioning and self-sustaining plant communities that will be resilient to further 

disturbances (i.e., will not degrade to pre-treatment, weed-dominated conditions). This may be achieved 

by devising seed mixes containing compatible species that (1) maximally occupy available niches 

(enhance functional diversity), and (2) possess physiological and growth characteristics that facilitate 

their establishment, competitiveness, and tolerance of stress. 

Researchers have found that sites with high functional group diversity, especially with respect to native 

forbs, are more competitive and resistant to weed invasion and establishment because site resources are 

fully utilized (Carpinelli 2000; Symstad 2000; Pokomy 2002). Although the full spectrum and diversity 

of the desired plant community rarely will be achieved during revegetation, niche occupation and 

resources use can be enhanced by combining key species that vary in their seasonal growth pattern, seral 

status, reproductive mechanisms, and growth form and root morphology (e.g., fibrous-rooted grasses and 

forbs with deep taproots) (Panetta and Groves 1990; Jacobs et al. 1999; Goodwin and Sheley 2003). 

Example of native cool-season grasses (grow in the early spring/summer and utilize soil resources in the 

upper soil profile) that can be competitive against invasive weeds include blue wildrye (Elymus glaucus), 

squirreltail (Elymus elymoides), mountain brome (Bromus carinatus), thickspike wheatgrass (Elymus 

lanceolatus), slender wheatgrass (Elymus trachycaulus), bluestem or western wheatgrass (Pascopyrum 

smithii), and prairie junegrass (Koelaria macrantha), Sandberg bluegrass (Poa secunda) (Borman et al. 

1991; Brown and Amacher 1999; Goodwin and Sheley 2003). Idaho fescue (Festuca idahoensis), a coolseason bunchgrass, can also be a strongly competitive once mature stands are established. Competitive 

native forbs and legumes include blue flax, (Linum lewisii), common yarrow (Achillea millefolium), 

pearly everlasting (Anaphalis margaritacea), fireflower (Epilobium angustifolium) and various lupine 

(Lupinus) and vetch (Vicia) spp. 

Native grass-like species, such as sedges, spikerushes, rushes, and bulrushes, may be useful in 

revegetating riparian and wetland areas. Under these conditions, containerized seedlings often show 

better survival and establishment than seeding. Deep-rooted shrubs may also be seeded or planted to 

more fully utilize resources from the lower soil profile, especially late in the growing season. Shrub 

vegetation can facilitate the establishment of understory species by increasing water availability and 

reducing understory temperatures and evapotranspiraation. Over the long term, perennial shrubs will also 

enhance soil fertility and structure and increase nutrient cycling (West 1989). 

A more complete list of native species suitable for revegetation activities should be developed on 

Districts/Forests by knowledgeable plant resource specialists (i.e., range specialists, botanists, ecologists, 

etc.) through examination of target sites and nearby undisturbed reference areas. There’s a broad array of 

competitive native species that may be useful in revegetation; however, research efforts have not fully 

explored their potential or the conditions under which they would be most effective. In general, 

characteristics that make a species well-suited for revegetation include broad ecological amplitude, rapid 

germination and early seedling growth, and aggressive root systems. Such species are often early seral 

natural colonizers of disturbed sites. Late seral species often have lower growth rates than colonizers, but 

still can be an important component of a seed mix because they tend to be highly competitive and often 

have high root/shoot ratios (Brown and Amacher 1999). Combining native and non-native species in 

seeding or planting mixes, however, is generally not recommended due to incompatible growth and life 

history strategies. An exception would involve the mixing of one or two long-lived perennial native 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B-Botany 

 B-24 

species with a non-native temporary cover crop type species (e.g., from the list in Table D-1, Appendix D) 

that will rapidly colonize and occupy the site until the slower perennial species become established. 

Seed Labeling and Testing 

The genetic origin of all native seed used in restoration should be known; purchased seed should be 

certified as to source identity. Purchased seed, both native and non-native, must have documented and 

recent (<1 year old) germination, purity, and “All State’s Noxious Weed” test results. The more recent the 

test, the more likely it is to reflect the true condition of the seed . Testing should be conducted by a 

National Association of Official Seed Certification Analysis (AOSCA) approved seed testing laboratory 

(Table C-2, Appendix C). Copies of seed test results should be retained in associated project files. 

Purity testing verifies the proportion of pure seed contained in the seed lot and identifies contaminants, 

including other crop seed, weed seed, and inert matter (e.g, stems, chaff, small stones). Graminoid seed 

with more than 10-15 percent inert matter will be difficult to apply through a rotary seeder or rangeland 

drill. Germination tests provide information on how well the pure seed portion of the seed lot will 

perform under favorable field conditions. The percentage of pure live seed (PLS), calculated as the 

percent purity multiplied by the percent germination, is commonly used as a standardized indicator of 

seed quality. See Table C-2, Appendix C, for suggested minimum acceptable germination and purity 

standards for grass and forb seed. 

Many native species produce seeds that are dormant and won’t germinate without afterripening (time) or 

special germination enhancement treatments (stratification, scarification, gibberellic acid, etc.). In these 

cases, seed viability may be estimated using other procedures. Most widely used is the fast and 

inexpensive tetrazolium (TZ) test, which involves a biochemical staining technique with tetrazolium 

chloride that visibly stains live, germinable seed (Young and Young 1986). 

Seed test results should verify that the seed lot contain no “Prohibited” noxious weed seed, and that seed 

meets or exceed standards for “Restricted” or “Other Weed Seed” content according to Oregon and/or 

Washington State standards for Certified Seed (Table C-2, Appendix C). Because each state has 

different lists of prohibited and restricted noxious weeds, request that the seed be tested with an “AllStates Noxious Weed Exam”. The name and number of seeds per pound of weed and other crop seed will 

be listed on the seed label. Be on the alert for aggressive nonnatives that, although not prohibited or 

restricted by the State, may still pose a threat to native plant communities. 

Determining Seeding Rates

Seeding rates for grasses and forbs can vary greatly depending on site condition, species, and methods of 

application. Recommended seeding rates for pure grass seed mixtures are generally in the range of 20-50 

viable seeds per square foot (Goodwin and Sheley 2003); pure forb and shrub mixes will be lower (you 

wouldn't want 10 Elderberry shrubs in every square foot for example). Higher rates are often 

recommended for severely disturbed sites to compensate for high seedling morality due to limiting 

environmental factors and competition. Goodwin and Sheley (2003), for example, suggest a seeding rate 

of 80 PLS/ft2

 for perennial grasses in severely burned areas, and doubling or tripling rates when seeding 

to prevent weed invasions, or if broadcast seeding or hydroseeding. Brown and Amacher (1999) 

recommend 250-350 PLS seeds per ft2

 on severe disturbances. Increasing the seeding rate, however, will 

never make up for poor seedbed preparation, poor seeding methods, or improper timing of seeding. 

Seeding rates are calculated using the following information: 

total number of seeds per pound 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B - Botany 

B-25

percentage of each pound that is pure, live seed (PLS) 

number of acres to be treated 

target PLS /ft2

 after considering site conditions and seeding method 

Example calculations for a single species seed mix: seed 1 acre with blue wildrye which has 131,000 

seeds per pound and is 83% PLS to get a result of 20 PLS /ft2

:

 (1 acre) x (43,560 ft2

/acre) x (20 PLS/ft2) = 871,200 PLS 

 (131,000 seeds/lb) x (0.83) = 108,730 PLS/lb. 

 871,200 ÷ 108,730 = 8.01 lb. 

Example calculations for a multi-species seed mixture: seed 1 acre with 4 species at different rates (to 

equalize competition) to obtain a coverage of 40 PLS/ft.2

:

Species Seeds per pound PLS 

Target Coverage 

(PLS/ft2) 

Blue wildrye 131,000 0.83 10 

Mountain brome 81,500 0.86 10 

Prairie junegrass a 2,300,000 0.80 10 

Sandberg’s bluegrass 925,000 0.80 10 

Total Coverage: 40 PLS/ft2

a Bluebunch wheatgrass may be substituted on drier sites. Idaho fescue would be a good addition to this mix if available. 

Blue wildrye: (1 acres) x (43,560 ft2

/acre) x (10 PLS/ft2) = 435,600 PLS 

 (131,000 seeds/lb) x (0.83) = 108,730 PLS/lb. 

 435,600 ÷ 108,730 = 4.01 lb/acre. 

Mountain brome: (1 acre) x (43,560 ft2

/acre) x (10 PLS/ft2) = 435,600 PLS 

 (81,500 seeds/lb) x (0.86) = 70,090 PLS/lb. 

 435,600 ÷ 70,090 = 6.21 lb/acre. 

Prairie junegrass: (1 acre) x (43,560 ft2

/acre) x (10 PLS/ft2) = 435,600 PLS 

 (2,300,000 seeds/lb) x (0.80) = 1,840,000 PLS/lb. 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B-Botany 

 B-26 

 435,600 ÷ 1,840,000 = 0.24 lb/acre. 

Sandberg’s bluegrass: (1 acre) x (43,560 ft2

/acre) x (10 PLS/ft2) = 435,600 PLS 

 (925,000 seeds/lb) x (0.80) = 740,000 PLS/lb. 

 435,600 ÷ 740,000 = 0.59 lb/acre. 

 Total 

Mix = 11.05 lb/acre 

How to use PLS: If the plan calls for a certain amount of pounds of PLS seed per acre, how much bulk 

seed is needed? To calculate the corresponding bulk amount, divide the PLS percentage into the number 

of pounds recommended. Example: You want to plant 5 PLS pounds of Idaho Fescue per acre. The 

analysis label indicates 85% purity and the germination is 79%. .85 x .79 = .67 PLS. Divide .67 into 5 

lbs/acre = 7.5 lbs of BULK seed/acre. 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B - Botany 

B-27

Plant Material Establishment

Site Preparation: to be written

SAVE TOPSOIL (if weed-free) by stockpiling for later use (see Appendix _, for topsoil guidelines). 

Prepare seed bed by "roughing up" or terracing exposed soil surfaces so that broadcasted seed is caught 

and held on the slope. 

Where transplanting is a viable option, prepare a capillary bed for storage of transplants. Capillary beds 

are used to maintain the moisture of the salvaged plants for extended periods of time, minimizing labor 

and water usage. (See Appendix _, for more information of construction and use). 

Seed Treatments : to be written 

e.g,. seed priming; germinator enhancers (GERMINATE) 

Seeding Techniques: to be written 

Bareroot and Containerized Planting Stock: to be written 

Planting Techniques: to be written 

Mulching 1

A mulch is a non-living material placed on the soil surface primarily to protect the soil from wind and 

water erosion, facilitate infiltration, reduce evaporation and moderate soil temperatures. Mulching 

generally can improve overall germination and seedling establishment and protect the soil resource. 

Specific site conditions need to be examined to determine the potential effectiveness of a mulch. On 

shallow sites where soils are not highly erodible, soil moisture and organic matter are present, high winds 

are not a problem and no soil crusting is expected to occur, then mulching may not be necessary. Mulch, 

especially if applied at too high a rate, may inhibit germination and establishment of at least some native 

species by reducing temperature and light at the soil surface. 

Straw mulches consisting of wheat, barley and/or oats are the most common mulches. Application rates 

can vary, but average 2 tons per acre. Care must be taken to use certified (if available) weed free straw to 

prevent the introduction of noxious weeds onto the site. Stems need to be as long as possible to increase 

its life expectancy as a mulch. Straw can be placed on the site by hand or with a blower for large areas. 

Straw mulch often needs to be anchored to prevent being blown away or washed away by overland water 

flow. The use of tackifiers, plastic, or biodegradable netting is an effective way to retain the straw on the 

site. Mechanical crimpers have also been used to push the straw into the soil surface on sites where the 

use of heavy equipment is feasible. 

Native hay mulches have also been used but often contain high levels of noxious weed seed or other nondesirable plant species. Great care must be exercised when using native hay; if the introduced species are 

desirable, then native hay can result in increased diversity of the resulting plant community. 

Hydromulching with wood fiber or paper in a water slurry is another form of mulching. This requires the 

use of a machine called a hydromulcher or hydroseeder, and equipment access to the site. Wood fiber 

mulches are usually more effective than paper mulches because the longer wood fibers adhere to the soil 

 

1

 Taken in part from National Park Service, USDI, Revegetation and reclamation training workshop, April 1993, 

and from the R1 and R4 Native Plant Handbooks. 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B-Botany 

 B-28 

and are more resistant to wind and water erosion. Hydromulch is often applied at average rates of 1500 

lbs to the acre and a tackifier can be used to help it stay on the slope. Incorporation of seed and fertilizer 

in the mix is not a good idea because much of the seed will not be in contact with the soil and can be lost 

to desiccation. Fertilizer in the slurry can create a high salt concentration that can reduce water 

adsorption and kill the seed. 

Woodchips, sawdust and bark can also be used as a mulch. These can be quite inexpensive if local 

sources are present. Wood residues are very long lasting compared to other mulches. However nutrients 

like nitrogen can get tied up and immobilized in the wood during the decay process. The addition of 

fertilizer can help offset nitrogen deficiencies during decomposition. 

The use of pre-made erosion control mats are also effective for revegetation and rehabilitation projects. 

These mats come in a variety of types, sizes, strengths and can be expensive. Mats made from straw 

and/or coconut fiber with biodegradable netting are rolled onto the site and secured with metal staples. 

Stronger mats, either pure coconut fiber or synthetic fibers, need to be used on sites with high erosion 

hazards, high velocity overland flow rates, or steep slopes. 

Mulching after seeding can improve the success of the revegetation by keeping the seed in contact with 

soil, moderating temperatures, and reducing water loss necessary for the seed to germinate. Mulching 

around planted seedlings can also improve water availability and provide protection from the 

environment. 

Fertilizing: to be written 

Fertilizer should be used only in exceptional circumstances. Generally, exotic species respond more 

vigorously to added nutrients. Where fertilizer is used, its composition may favor particular groups of 

species (Panetta and Groves 1990). 

Fertilizer application is not recommended when: 

Soil does not show evidence of nutrient deficiency 

Seed or seedlings of locally native species, especially nitrogen-fixers (e.g. legumes), are introduced onto 

the site 

Seeding with sterile hybrids such as REGREEN 

Site is adjacent to a non-native or noxious weed seed source 

Site is adjacent to a waterway (e.g. culvert removal projects) 

Fertilizer application may be appropriate on sites in which biological indicators (e.g. chlorotic plants) and 

soil tests show a nutrient deficiency. Fertilizer has been found to increase growth of weedy annuals, 

which in turn inhibits the growth of slower growing perennial species (McLendon and Redente 1991, 

1992, 1994; Redente et al. 1992) 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B - Botany 

B-29

Monitoring and Evaluation 

This section is not complete 

Monitoring is necessary to assess if proposed treatments were properly implemented, if actual treatments 

were effective and if additional treatments or maintenance are needed to make the revegetation project 

successful in the long-term. 

The following information should be recorded as part of revegetation monitoring and evaluation: 

Species seeded, planted, or transplanted onto the project site; source and cost of species used (if 

applicable). 

Seed application rates; method of application (e.g. hydroseeding). 

Type of mulch and/or erosion control blanket used (if any), mulch application rate (percent cover). 

Fertilizer application rate (if applicable). 

Other site treatments used, including terracing and irrigation. 

Environmental conditions at the time of implementation. 

Results - what worked and what did not work. 

A Basic Monitoring Form has been included in Appendix _ as a starting point for recording and sharing 

information about the success (or failure) of treatments. 

Decision Matrix 

The Decision Matrix and associated Revegetation Prescriptions are being revamped 

The following decision matrix recommends revegetation options based on site characteristics, erosion 

potential, and presence/absence of noxious weeds. 

Site Characteristics 

Riparian Group I

Upland 

Erosion potential high (see guidelines, item 2A) Group II

Erosion potential low (see guidelines, item 2A) Group III

Wilderness, RNA or Botanical Special Interest Area Group IV

Group I: Riparian 

Erosion potential high 

Surface area of disturbance >0.25 acre; site forested (relatively cool and moist; receives some shading 

from adjacent stands) and has seed source of locally native woody species (e.g. red alder) available, or 

non-forested (open and relatively dry due to lack of shading; includes large forest openings, road projects 

(e.g. culvert removal), areas adjacent to clear-cuts, wet and dry meadows, and wetlands). Noxious weeds 

present or absent. Prescription A, pg. __ 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B-Botany 

 B-30 

Surface area of disturbance (project area) <0.25 acre; site forested or non-forested

Noxious weeds present Prescription A, pg. __ 

Noxious weeds absent Prescription B, pg. __ 

Erosion Potential low

Noxious weeds present; site forested or non-forested; surface area of disturbance (project area) variable

Prescription C, pg. __ 

Noxious weeds absent; site forested or non-forested; surface area of disturbance (project area) variable

Prescription D, pg. __ 

Group II: Upland, high erosion potential 

Noxious weeds present; site forested or non-forested; surface area of disturbance (project area) variable

Prescription A, pg. __ 

Noxious weeds absent; site forested or non-forested; surface area of disturbance (project area) variable

Prescription B, pg. __ 

Group III: Upland, low erosion potential 

Noxious weeds present; site forested or non-forested; surface area of disturbance (project area) variable

Prescription C, pg. __ 

Noxious weeds absent

Surface area of disturbance (project area) >0.25 acre; site forested or non-forested 

Prescription D, pg. __ 

Surface area of disturbance (project area) <0.25 acre

Site non-forested Prescription D, pg. __ 

Site forested Prescription E, pg. __ 

Group IV: Wilderness, RNAs and Special Interest Areas 

All types of sites, from forested to non-forested, low to high elevation, noxious weeds may be present, 

good native seed source in the area. Prescription F, pg __ 

Revegetation Prescriptions 

Prescription A 

Conditions: Forested and non-forested riparian and upland sites with steep slopes and high erosion 

potential. Noxious weeds present or absent. Surface area of disturbance variable. 

Objectives: Minimize surface erosion; stabilize slopes; minimize invasion by noxious weeds; 

maintain integrity of native plant communities. 

Prescription: 

Consult with Forest/District Soil Scientist on soil erosiveness and erosion control. 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B - Botany 

B-31

Seed with local native grasses if available or nonpersistent annual grass or sterile wheat. 

Apply erosion control materials (see Appendix _). In very critical areas, consider salvaging and 

replanting displaced woody species onto project site. Consult with Forest Ecologist, Botanist, or Range 

Conservationist. 

Do not fertilize. 

Plan for future planting of native species on the site; i.e., for each project area, outline (a) acreage and 

approximate dimensions requiring further revegetation with native stock, (b) dominant native species 

present, and (c) provide a map of project locations. Submit native revegetation needs to Forest Ecologist, 

Botanist, or Range Conservationist. 

Alternatives: 

Prescription B (erosion control materials only) 

Erosion control materials and transplants 

Woody Species: 

Forested Sites. On forested sites where seed source of locally native woody species is abundant, site 

should fill in naturally with trees and shrubs. Given that establishment of woody species may be delayed 

on these sites, especially if the project area is large, seedlings of woody species occurring within the 

vicinity of the project area may be collected and transplanted. 

Non-forested Sites. On non-forested sites where seed source of locally native woody species may be 

lacking, seedlings of woody species occurring within the vicinity of the project area may be collected and 

transplanted. Seed of locally native grasses and herbs may be collected and sent to a nursery to be 

increased for use on the site in the following years. 

Rationale: 

Seeding with non-persistent annuals or sterile wheat. Seeding of project area with a nonpersistent annual 

or sterile wheat is recommended to (a) provide short-term erosion control, and (b) discourage invasion by 

noxious weeds and other aggressive non-native species until native species can become reestablished. 

Seeding/transplanting native species: Seeding and transplanting of locally native herbaceous and woody 

species is recommended as needed in the future in order to provide native cover as quickly as possible, to 

discourage invasion by exotic species, and to maintain the integrity of native plant communities, 

structural and biological diversity, and wildlife values. 

Fertilizer is not recommended because application may facilitate invasion by noxious weeds and/and 

undesirable, persistent non-natives. Additionally, fertilizer can change the soil (microbiotic) ecosystem 

Advantages/Disadvantages: 

Advantages. Erosion control blankets are shown to be highly effective; seeding with non-persistent, nonnative grass (Regreen) provides quick vegetative cover & soil binding mechanism; Prescription A offers 

the greatest degree of erosion control. 

Disadvantages. High cost of erosion control blanket; possible inhibition of natural colonization created 

by presence of annuals or hybrids. 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B-Botany 

 B-32 

Prescription B 

Conditions: Forested riparian and upland sites with steep slopes and high erosion potential. Sites are 

small (disturbed area <0.25 acre), relatively moist, and have a good locally native, woody species seed 

source nearby. Noxious weeds are absent. 

Objectives: Minimize surface erosion; stabilize slopes; maintain integrity of native plant 

communities. 

Prescription: 

• Consult Forest/District Soil Scientist for soil erodibility/hazard analysis 

• Determine seeding needs 

• Do not fertilize. 

• Plan for future revegetation needs; see Prescription A. 

Alternatives: 

Prescription A: (erosion control materials & seed). 

Bioengineered erosion control structures (e.g. using hardwood cuttings). 

Erosion control materials plus transplants. 

Woody Species: 

Forested sites- on forested sites where seed source of locally native woody species is available, site 

should fill in naturally with trees and shrubs. Given that establishment of woody species may be delayed 

on these sites, especially if the project area is large, seedlings of woody species occurring within the 

vicinity of the project area may be collected and transplanted as funding becomes available. 

Rationale: 

Erosion control blanket: Erosion control materials alone should suffice in small, forested areas where a 

native seed source is readily available. Site may be sown with a nonpersistent annual or hybrid grass (see 

Appendix C) in critical areas. 

Fertilizer is not recommended because application may facilitate invasion by noxious weeds and/and 

undesirable, persistent non-natives. Additionally, fertilizer can change the soil (microbiotic) ecosystem 

Advantages/Disadvantages: 

Advantages- Less expensive than Prescription A due to elimination of seeding; absence of non-persistent 

annual grass or REGREEN on site may facilitate colonization by native species. 

Disadvantages- Less effective erosion control than Prescription A, lower aesthetic value for 1-3 years 

(depending on moisture), especially in visible areas (e.g. roadcuts), than Prescription A. 

Prescription C 

Conditions: Forested and non-forested riparian and upland sites with low erosion potential. Size of 

disturbed area variable. Noxious weeds present. 

Objectives: Minimize surface erosion; minimize invasion by noxious weeds; maintain integrity of 

native plant communities 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B - Botany 

B-33

Prescription: 

• Seed with nonpersistent annual or sterile wheatgrass (see Appendix A) as soon as possible after 

ground disturbance. 

• Do not fertilize. 

• Mulch with clean, weed-free wheat, oat, or barley straw/local native hay; crimp in mulch, if desired. 

• Consult with Forest Noxious Weed Coordinator regarding site-specific control of noxious weeds. 

• Plan for future revegetation needs; see Prescription A. 

Alternatives: n/a 

Woody Species: 

Forested sites. On forested sites, seeding and outplanting of locally native herbaceous and woody 

species should be accomplished as soon as possible to discourage invasion by noxious weed species.. 

Non-forested sites. On non-forested sites, seed of locally native grasses and forbs may be sown as early 

as possible, contingent on seed availability. Seedlings of locally native woody species adapted to drier 

sites should be collected and outplanted as soon as bare rootstock becomes available (see Prescription A). 

NOTE: Sites with low erosion potential should be given lower priority in revegetation projects than sites 

with high erosion potential; seedlings should not be allocated for low priority project sites until all high 

priority sites have been planted. Consult with Forest Noxious Weed Coordinator, Oregon or Washington 

State Weed Programs, or Forest Weed Strategy for site-specific control of noxious weeds. 

Rationale: 

Seeding with annual or REGREEN: Seeding of project area with a nonpersistent, annual or wheatgrass 

hybrid grass is recommended to (a) provide immediate erosion control in the short-term, and (b) 

discourage invasion by noxious weeds and other aggressive non-aggressive species until native species 

can become reestablished. 

Seeding/outplanting native species: Seeding and outplanting of locally native herbaceous and woody 

species is recommended as needed in order to provide native cover as quickly as possible, to discourage 

invasion by exotic species, and to maintain the integrity of native plant communities. 

Weed-free wheat, oat, or barley straw or weed-free local native hay: Any of these should effectively 

control surface erosion on relatively flat surfaces, and will be significantly less expensive than erosion 

control blanket/matting. 

Fertilizer is not recommended because application may facilitate invasion by noxious weeds and/or 

undesirable non-natives. 

Advantages/Disadvantages: 

Advantages. Non-native, non-persistent annuals or sterile wheat grass (see Appendix C,) provide quick, 

effective erosion control, less expensive than erosion control blanket. 

Disadvantages. Weed-free wheat, oat, or barley straw or weed-free local native hay plus non-persistent 

annuals or sterile wheat grass (see Appendix C) may inhibit colonization of site by native species; 

straw/hay and/or annuals and REGREEN may have mild allelopathic properties. 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B-Botany 

 B-34 

Prescription D 

Conditions: Forested and non-forested upland, and riparian sites with low erosion potential. Size of 

disturbed area variable. Noxious weeds absent. 

Objectives: Minimize surface erosion; maintain integrity of native plant communities 

Prescription: 

• If site <0.25 acres, rake in or collect plant materials from edges or mulch with weed-free wheat, 

oat, or barley straw or local native hay. Crimp in mulch, if desired. Let site revegetate on its own. 

Early seral plant species will recolonize these sites. 

• Do not seed with introduced species. 

• Plan for future revegetation needs; see Prescription A. 

Alternatives: 

Prescription C

Prescription E

Wheat, barley, or oat straw plus transplants 

Woody Species: 

Forested sites. On forested sites where seed source of locally native woody species is available, site 

should fill in naturally with trees and shrubs. Given that establishment of woody species may be delayed 

on these sites, especially if the project area is large, seedlings of woody species occurring within the 

vicinity of the project area may be collected and transplanted if possible. 

Non-forested sites. On non-forested sites where seed source of locally native woody species may be 

lacking, seedlings of woody species occurring within the vicinity of the project area may be transplanted 

as soon as bare rootstock and/or plugs are available. Seed of locally native grasses and herbs may be 

sown, contingent on seed availability. 

NOTE: Sites with low erosion potential should be given lower priority in revegetation projects than sites 

with high erosion potential; seedlings should not be allocated for these low priority sites until all high 

priority sites have been planted. 

Rationale: 

Wheat or oat straw mulch: Wheat or oat straw mulch should effectively control surface erosion on 

relatively flat surfaces, and will be significantly less expensive than erosion control blanket or matting. 

Fertilizer: Fertilizer application is not recommended. 

Advantages/Disadvantages: 

Advantages. Least expensive erosion control treatment; facilitates colonization of site by native species 

to a greater extent than does Prescription C. 

Disadvantages. Lower aesthetic value than Prescription C- may be a concern in highly visible areas. 

Potentially less effective erosion control measure than Prescription C. 

Prescription E 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B - Botany 

B-35

Conditions: Forested upland sites on relatively flat ground and with low erosion potential. Sites are 

small in area (less than 0.25 acre), relatively moist, and have a good native seed source nearby. Noxious 

weeds are absent. 

Objectives: Allow for natural recolonization of project site by native species; maintain integrity of 

native plant communities; determine natural, unimpeded rate of recovery of the site. 

Prescription:

No treatment (control) 

Alternatives: 

Prescription D

No mulch, plus transplant 

No treatment (control): 

Monitor site recovery; i.e., record species present; percent cover by species or canopy class; and mean 

stem height of tree seedlings/saplings by species (if applicable). 

Rationale: 

A no treatment control is required to determine the relative effectiveness of other treatments. In small, 

upland areas with low erosion potential, the “no treatment alternative” should not have significant 

adverse impacts on the surrounding environment. The no treatment alternative should be applied 

carefully, however, and only after all potential effects are considered. 

Advantages/Disadvantages: 

Advantages. Least expensive alternative. Under appropriate conditions, presents the least impact to the 

surrounding environment and permits unimpeded, natural recovery of the native community to proceed. 

Disadvantages. May be difficult to justify politically. May demand that public be educated about 

restoration alternatives. If not utilized under appropriate conditions, presents risk of surface erosion, and 

invasion by non-native species and noxious weeds. 

Prescription F 

Wilderness, RNA’s, and Special Interest Areas 

Conditions: All types of sites ranging from forested to non-forested, low elevation to high elevation, 

and steep to flat. Sites have a good native seed source in the area. Noxious weeds may be present. 

Objectives: Allow for natural recolonization of project site by native species; maintain integrity of 

native plant communities and native plant gene pools; determine natural, unimpeded rate of recovery of 

the site (see Authorities and Agreements, Appendix A). 

Prescription: 

• If low potential for erosion, no treatment or rake in/collect native plant materials from the edges of 

the disturbance to spread on the bare soil. 

• If high potential for erosion, work with Forest/District Soil Scientist to stabilize soils with erosion 

control materials. 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B-Botany 

 B-36 

• Check area for noxious weeds and contact Weed Coordinator if present. 

• Last option – “avoid persistent or invasive exotic plants” and “choose a short-lived ground cover that 

will not hybridize with local species, displace native species permanently, or offer serious long-term 

competition to recovery of local plants”. See Appendix B, R6 Revegetation Policy. 

Alternatives: 

Prescription D or E

No erosion control materials, plus local transplants from surrounding area 

No treatment: 

Monitor site recovery; i.e., record species present; percent cover by species or canopy class; and mean 

stem height of tree seedlings/saplings by species (if applicable). 

Rationale: 

A no treatment control is required to determine the relative effectiveness of other treatments. In small, 

upland areas with low erosion potential the “no treatment alternative” should not have significant adverse 

impacts on the surrounding environment. The no treatment alternative should be applied carefully, 

however, and only after all potential effects are considered. 

Advantages/Disadvantages: 

Advantages. Least expensive alternative. Under appropriate conditions, presents the least impact to the 

surrounding environment and permits unimpeded, natural recovery of the native community to proceed. 

Disadvantages. May be difficult to justify politically. May demand that public be educated about 

restoration alternatives. If not utilized under appropriate conditions, presents risk of surface erosion, and 

invasion by non-native species and noxious weeds. 

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to nutrient gradients. Plant and Soil 140:127-135. 

Schoennagel, T.L. and D.M. Waller. 1999. Understory responses to fire and artificial seeding in an 

eastern Cascades Abies grandis forest, U.S.A. Canadian Journal of Forest Resources 29:1393-1401. 

Sheley, R.T., T.J. Svejcar, and B.D. Maxwell. 1996. A theoretical framework for developing successional 

weed management strategies on rangeland. Weed Technol. 10:712-720. 

Symstad, A.J. 2000. A test of the effects of functional group richness and composition on grassland 

invasibility. Ecology 81:99-109. 

Svejcar, T. and R. Sheley, R. 2001. Nitrogen dynamics in perennial- and annual-dominated arid 

rangeland. Journal of Arid Environments 47:33-46. 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B - Botany 

B-39

USDA Forest Service. 1973. State of Oregon, tree seed zone map. Western Forest Tree Seed Council. 

USDA Forest Service, Portland, Oregon. 

Young, J.A. and C.G. Young. 1986. Collecting, processing, and germinating seeds of wildland plants. 

Timber Press, Inc. Portland, OR. 

Young, J.A., R.R. Blank, and C.D. Clements. 1999. Nitrogen enrichment and immobilization influences 

on the dynamics of an annual grass community. In: D. Eldridge and D. Freudenberger (eds). People and 

Rangelands – building the future. Proceedings of the VI International Rangeland Congress, Aitkenvale, 

Queensland, Australia. 

West, N.E. 1989. Spatial pattern-functional interactions in shrub-dominated plant communities. P. 283-

305. In: C.M. McKell (ed.). The Biology and Utilization of Shrubs. Academic Press, New York, NY. 

Westman, W.E. 1990. Park management of exotic plant species: problems and issues. Conservation 

Biology 4:251-259. 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B-Botany 

 B-40 

Internet Resources for the Revegetation Guidelines 

Weed Related Websites 

Weed ID Sites 

CropNet – Weeds http://www.crop-net.com/weeds.htm

American Cyanamid Weed 

Guide http://www.cyanamid.com/tools/weedguide/index.shtml

UC Pest Management Guidelines 

- Weed Photo Gallery http://www.ipm.ucdavis.edu/PMG/r785700999.html

FMC Weed ID http://ag.fmc.com/ag/weedbug

Idaho Noxious weeds http://www.oneplan.state.id.us/pest/nw00.htm

University of Illinois Weed ID http://web.aces.uiuc.edu/weedid.htm

Iowa State Weed ID http://www.weeds.iastate.edu/weed-id/weedid.htm

Noxious Weeds of Kansas http://www.ink.org/public/kda/phealth/phprot/weeds.html

Common Weed Seedlings of 

Michigan http://www.msu.edu/msue/iac/e1363.htm

Oregon State Weed ID site http://www.css.orst.edu/weeds/id.html

University of New England 

Weed ID http://www.une.edu.au/agronomy/weeds/photo_library/ph_lib.html

Rutgers Coop Extension - Weeds 

of New Jersey http://www.rce.rutgers.edu/weeds/index.html

Virginia Tech Weed 

Identification Guide http://www.ppws.vt.edu/weedindex.htm

WSSA Photo herbarium http://ext.agn.uiuc.edu/wssa/subpages/weed/herbarium0.html

Wyoming Noxious Weed Site http://www.uwyo.edu/plants/weeds/id

Weed Control 

ARS Exotic and Invasive Weeds 

Unit http://wric.ucdavis.edu/exotic.html

NC Aquatic Weeds (East) http://www.cropsci.ncsu.edu/aquaticweeds

Yellow Star thistle http://soils.ag.uidaho.edu/yst

Weeds of No-till Cropping 

Systems http://www.btny.purdue.edu/Extension/Weeds/NoTillD/NoTillWeed1.html

North Carolina Cotton Weed 

Control http://ipmwww.ncsu.edu/Production_Guides/Cotton/chptr10.html

New York Forage Crops Weed 

Control http://wwwscas.cit.cornell.edu/forage/recommends/recindex.html

Weeds of Minnesota Wheat http://www.smallgrains.org/techweed.htm

Agricultural Companies 

Aventis http://www2.aventis.com

BASF http://www.basf.com

Bayer http://www.agro.bayer.com/

Dow AgroSciences http://www.dowagrosciences.com

DuPont http://www.dupont.com

FMC Home Page http://www.fmc.com

Monsanto http://www.monsanto.com

Novartis http://www.novartis.com/agri/index.html

Rohm and Haas Home Page http://www.rohmhass.com
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B - Botany 

B-41

Zeneca Main page http://www.zeneca.com

Herbicide Company Geneology http://www.css.orst.edu/herbgnl/tree.html

Educational Resources 

American Society for the 

Advancement of Science http://www.aaas.org

1998 Weed Science 

Compendium http://www.agsci.kvl.dk/weedsci/teaching/weedbk98.htm

BLM environmental Education http://www.blm.gov/education/fire_and_weeds.html

K-8 Weed Projects http://www.sped.ukans.edu/~unitest/explorer-db/html/835851687-

81ED7D4C.html

National Science Foundation http://www.nsf.gov

Miscellaneous 

Council for Agricultural Science 

and Technology http://www.cast.science.org

The Environmental Weeds Home 

Page (Austrailia) http://weeds.merriweb.com.au

Sustainable Agriculture Network http://www.sare.org/san

University of New England, 

Australia http://www.une.edu.au/agronomy/weeds

WeedJobs (Jobs in Weed 

Science) http://www.NRCan.gc.ca/~bcampbel

University Weed Science Sites 

Auburn University http://www.ag.auburn.edu/dept/ay

University of California, Davis http://veghome.ucdavis.edu/weedsci/WWW/Welcome.html

Colorado State University http://www.colostate.edu/Depts/IPM/nipm/agwee.html

University of Georgia Weed 

Science http://mars.cropsoil.uga.edu/fac_weed.htm

University of Illonois, UrbanaChampaign http://w3.aces.uiuc.edu/CropSci/weed-lab

Iowa State Weed Science http://extension.agron.iastate.edu/extweeds/Default.htm

University of Maryland Weed 

Science http://www.agnr.umd.edu/users/weed

University of Missouri-Colunbia 

Weed Science http://www.psu.missouri.edu/agronx/weeds

University of Nebraska Weed 

Science http://ianrwww.unl.edu/ianr/agronomy/ws.htm

New Mexico State University 

Weed Science http://taipan.nmsu.edu/weeds/

North Dakota State University http://ncweeds@ndsuext.nodak.edu/extnews/weedpro/

Oregon State University http://www.css.orst.edu/weeds/

Rutgers University http://www.rce.rutgers.edu/weeddocuments/index.htm

Southern Illinois University http://www.siu.edu/~weeds/

Texas A&M http://aggie-horticulture.tamu.edu/plantanswers/turf/publications/weed2.html

Virginia Tech Weed Science http://www.ppws.vt.edu/

University of Wyoming http://www.uwyo.edu/plants/weeds/
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B-Botany 

 B-42 

U.S. Government Weed Related Sites 

BLM Weed Site http://www-a.blm.gov/weeds/

BLM Weed Hall of Shame http://www.blm.gov/education/weeds/hall_of_shame.html

Federal Interagency Committee 

FICMNEW http://bluegoose.arw.r9.fws.gov/FICMNEWFiles/FICMNEWHomePage.html

National Agricultural Pests 

Information System http://www.agnic.nal.usda.gov/agdb/napis.html

National Biological Control 

Institute http://www.aphis.usda.gov/nbci/

National Park IPM of Weeds http://www.colostate.edu/Depts/IPM/natparks/natpark.html

USDA ARS Southern Weed 

Science http://msa.ars.usda.gov/la/srrc

USDA ARS Weed Science 

Laboritory (Beltsville, MD) http://www.barc.usda.gov/psi/wsl/wsl.htm

Weed Science Societies and Organizations 

American Crop Protection 

Association http://www.acpa.org

Colorado Weed Management 

Assoc http://www.fortnet.org/CWMA

European Weed Research 

Society http://www.ewrs.ac.uk

Herbicide Resistance Action 

Committee http://www.PlantProtection.org/HRAC

International Weed Science 

Society http://www.css.orst.edu/weeds/iwss

International Weed Science 

Congress http://www.sercomtel.com.br/ice/plantas

North American Weed 

Management Association http://www.nawma.org

North Central Weed Science 

Society http://www.ncwss.iastate.edu

Northeastern Weed Science 

Society http://www.ppws.vt.edu/newss.htm

Southern Weed Science Society http://www.weedscience.msstate.edu/swss

Weed Science Society of 

America http://ext.agn.uiuc.edu/wssa

Weed Science Society of 

Victoria, Australia http://home.vicnet.net.au/~weedsoc

Western Society of Weed 

Science http://www.wsweedscience.org

Individual State Weed Sites 

Arizona Rangeland Weeds http://ag.arizona.edu/OALS/agnic/weeds/home.html

Colorado's 10 Most Wanted 

Weeds http://www.ag.state.co.us/commish/press/1999/weedweek.html

Control of Invasive Exotic Plants 

in the Great Plains http://www.npsc/nbs.gov/resources/literatr/exotic/exotic.htm

Kansas Noxious Weeds http://www.ink.org/public/kda/phealth/phprot/weeds.html

Michigan http://mel.lib.mi.us/science/weeds.html
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B - Botany 

B-43

North Dakota Weed Information http://www.ext.nodak.edu/extpubs/weeds.htm

Wyoming Weed and Pest 

Council http://www.wyoweed.org/
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B-Botany 

 B-44 

Appendix A for the Revegetation Guidelines Document 

Authorities, Policy, and Agreements Guiding Use of 

Native Species in Revegetation 

1. National Environmental Policy Act of 1969: “Prevent or eliminate damage to the environment and 

bioshpere...enrich...understanding of the ecological systems and natural resources important tot the 

Nation...”. 

2. Endangered Species Act of 1973 as Amended: “...Encouraging the states and other(s) ...to 

maintain conservation programs...to better safeguard the Nation’s heritage in fish, wildlife, and 

plants”. 

3. Federal Land Policy Management Act of 1976: “protect the quality of scientific...ecological, 

environmental...values, (and) where appropriate will preserve and protect certain public lands in their 

natural condition...” 

4. FEMAT (July, 1993): “Maintain and restore the species composition and structural diversity of plant 

communities in riparian zones and wetlands...”; “Maintain and restore habitat to support welldistributed populations of native plant, invertebrate, and vertebrate riparian –dependent species”. 

5. NFP ROD SEIS (April 1994): “Another goal of forest management on federal lands is to maintain 

the biological diversity associated with native species and ecosystems in accordance with laws and 

regulation.”; ACS Objective 9 “Maintain and restore habitat to support well-distributed populations of 

native plant, invetebrate, and vertebrate riparian-dependent species. 

6. NFP ROD SEIS Standards and Guidelines (April 1994): “In general, non-native species (Plant and 

animal) should not be introduced into LSR’s.”; “Evaluate the impacts of non-native species (plant and 

animal) currently existing within the reserves, and develop plans for eliminating or controlling nonnative species that are inconsistent with LSR objectives.” 

7. ICBEMP – Eastside Draft Environmental Impact Statement (May 1997): For Alternatives 3-7, 

Terrestrial Strategies TS-01 Objective: “Maintain and promote healthy, productive and diverse native 

plant communities as appropriate to soil type, climate, and land form.”; Terrestrial Strategies TS-03 

Objective:” Rehabilitate disturbed areas to restore native species, maintain productivity, and prevent 

soil loss”; Tribal Rights and Interests TI-03 Objective: “Recognize native plant communities as 

traditional resources that are important to tribes...”. 

8. Executive Order 11990 Protection of Wetlands (May 24, 1997): “Maintenance of natural systems, 

including conservation and long-term productivity of existing flora and fauna, species, and habitat 

diversity and stability...”. 

9. Executive Order 13112: Invasive Species (February 3, 1999): Directs actions to prevent 

introduction and spread of invasive species and restore native species. Revokes Executive Order 

11987. 

10. Emergency Fire Rehabilitation Manual FSM2523 (May, 2000): “...Natural recovery by native 

species is preferred....(When action is required) include native plant materials when possible to meet 

the objectives of the burned-area emergency rehabilitation. When practicable, use seeds and plants in 

burned-area emergency rehabilitation projects that originate from genetically local sources of native 

species. When native materials are not available or suitable, give preference to non-native species 

that meet the treatment objectives, are nonpersistent, and are not likely to spread beyond the treatment 

area.” 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B - Botany 

B-45

11. Native Plant Conservation Initiative National Strategy (1995): Ensure conservation and 

restoration of native plants and natural plant communities through ecosystem-based management. 

Educate the public, policymakers, and land managers about native plant conservation. 

12. 36 CFR 219.27; 42 U.S.C. 4321; 36 CFR 219.1, 5; 16 U.S.C. 1601 – 1614; 36 CFR 219.26, Part 

219: Preserve, maintain, and enhance the diversity [including genetic diversity] of plant communities. 

13. 7 CFR 650.23, Part 650:.Preserve examples of land and water ecosystems [in RNA’s] with their full 

range of genetic diversity of native plants. 

14. FSM 2323.52: “[In wilderness] permit ecological processes to operate naturally. Allow wherever 

possible, the natural process of healing in handling disturbed communities. Consider structural or 

vegetative assistance only as last resort”. 

15. FSH 2509.13-95-3, 26.6:. “[In wilderness] design treatments as temporary, short-lived actions that 

provide immediate protection but maintain wilderness integrity. Protect the genetics of endemic 

[confined geographically to a certain area, (Hitchcock, et al., 1969)] plants in wilderness. Choose a 

short-lived ground cover that will not hybridize with local species, displace native species 

permanently, or offer serious long-term competition to recovery of local plants” 

16. 7 CFR 650.23, Part 650, Subpart B, Sec. 650.23: “[Research] natural areas are established and 

maintained for...serving as a genetic base for native plants and animals. Natural areas may be 

established to preserve examples of land and water ecosystems with their full range of genetic 

diversity of native plants and animals including threatened and endangered species” 

17. Region 6 Policy on Use of Native and Nonnative Plants on National Forests and Grasslands, 

(April 12, 1994): Use local native plants as feasible; avoid persistent or invasive exotic plants (see 

Appendix B, this document). 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B-Botany 

 B-46 

Appendix B for the Revegetation Guidelines Document 

Regional and Forest Policy on Use of Native and Nonnative Plants on National Forests 

and Grasslands 

Reply to: 2600 Date:April14, 1994 

Subject: Use of Native and Nonnative Plants on National Forests and Grasslands 

 To: Directors and Forest Supervisors 

Sound vegetation management is the key to achieving many important objectives of ecosystem 

management, which include maintaining and enhancing biological diversity, sustaining longterm site productivity, and having healthy ecosystems. Successful vegetation management is 

dependent on: (1) Clearly defined objectives, (2) availability of adapted plant materials to 

achieve the objectives, and (3) knowledge of the soil and other environmental conditions where 

the plant material is to be used. Revegetation objectives must also be guided by law. For 

example, it would not be appropriate to respond to natural disturbance processes in wilderness 

with revegetation projects unless life or property outside of wilderness is jeopardized. 

The following direction is intended to guide the use of native and nonnative plant species to meet 

stated objectives of revegetation prescriptions and projects. Native plant vegetation has an 

intrinsic value as a component of forest and rangeland ecosystems. Nonnative plant species, 

although useful at times, have the potential to displace natural plant and animal communities, 

either through aggressive competition or through disease or insect introductions. 

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

seed and plant movement guidelines. Nonnative plant species may be used when: (1) Needed to 

protect basic resource 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. For example, massive soil loss can change sites so that native plant species cannot 

become established without interim ameliorating measures. As costs, availability, and technical 

knowledge permit, use of local native plant materials should become a more standard practice. 

Undesirable plants will not be used. 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B - Botany 

B-47

INTENT: The long-term goal is to use local native plant species as much as possible to meet 

management objectives. Areas that have the highest priority for using native plant species are 

those sites in and adjacent to wilderness (but only for restoration of unnatural disturbances), 

Research Natural Areas, National Parks, streams, wetlands, around documented sightings of 

sensitive plants, and in Native American cultural use areas. In areas that are in a permanently 

disturbed condition such as landing strips, powerline corridors, seed orchards, base areas in ski 

areas, or road cut and fill slopes, use of native plant species is a long-term goal but a lower 

priority. 

Enclosed are DEFINITIONS as further clarification of intent. 

/s/Robert Jacobs (for) 

JOHN E. LOWE 

Regional Forester 

Enclosure 

I CONCUR:R.SHAFFER:04/05/94 

cc: 

Dean Longrie, F&W 

Gene Silovsky, F&W 

Bob Meurisse, ERW 

Fred Hall, ERW 

Bernie Smith, Rec 

Susan Sater, Rec 

Margaret Peterson, Rec 

Jerry Beatty, FPM 

Fay Shon, FPM 

Sheila Martinson, TM 

Fred Zensen, TM 

Richard Shaffer, TM 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B-Botany 

 B-48 

Native: Plant species present in Oregon and Washington prior to European arrival, circa 1800. 

Example: fireweed (Epilobium angustifolium). 

Local Native: A population of a native plant species which originated, i. e., grew from seeds or 

cuttings, from genetically local sources. The geographic and elevational boundaries that define a 

species' genetically local source are determined by plant movement guidelines. 

Example: Douglas-fir (Pseudotsuga menziesii) seedlings grown from seed 

collected from the local seed zone. 

Non-local Native: This term has two meanings: (1) A population of a native plant species which 

does not occur naturally in the local ecosystem, and (2) plant materials of a native species that 

does not originate from genetically local sources. 

Examples: (1) black cottonwood (Populus trichocarpa) planted on an alpine 

ridge. (2) Douglas-fir (Pseudotsuga menziesii) seedlings originating from east 

of the Cascades planted in western Oregon or Washington. 

Non-local native should NOT be used because planting them can affect existing plant 

communities, plant-animal relationships, and the local gene pool. 

Acceptable Non-Native: Annual or short-lived perennial that is not persistent or competitive 

with native vegetation. These species are useful for erosion control or as noxious weed 

competitors. 

 Example: Sterile wheat. 

Naturalized species: Nonnative species that were introduced by humans to Oregon and 

Washington and have "gone wild" or become a part of natural communities. 

Example: Foxglove (Digitalis purpurea) 

Exotic species: Nonnative species that are not known to occur in Oregon or Washington except 

possibly in landscape plantings or botanical gardens. 

Example: Southern magnolia (Magnolia grandiflora

Undesirable Plant Species: Either one of the following: 

Plant species on the Oregon or Washington Department of Agriculture noxious weed list. 

Example: Hairy cats-ear (Hypochaeris radicata) 

*Horticultural varieties of native plant species. 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B - Botany 

B-49

Appendix C for the Revegetation Guidelines Document 

Native Species Production and Revegetation Information 

Table C-1. Number of pounds of wild-collected seed needed to establish a 1-acre 

production field for select native grass and forb species, estimated first and second year 

yields, and anticipated seed costs. 

SPECIES 

RECOMMENDED 

GOVT.-

FURNISHED 

LBS/ACRE a

AVERAGE 

GERM/PURITY 

AVG 

YIELD 

YEAR 1 b

AVG 

YIELD 

YEAR 2

AVG 

SEED/POUND 

COST PER 

POUND c

Bluebunch Wheatgrass 

(Pseudoroegneria spicata) 

10 80/90 300 300 140,000 $10.00-$12.00 

Blue Wildrye 

(Elymus glaucus) 

8 80/95 450 200 110,000 $7.00-$9.00 

Bottlebrush Squirreltail 

(Elymus elymoides) or 

Big Squirreltial 

(Elymus multisetus) 

8 80/90 0 125 110,000 $25.00-$30.00 

California Oatgrass 

(Danthonia californica) 

10 80/90 24 246 125,000 $15.00-$17.00 

Great Basin Wildrye

(Leymes cinereus) 

8 80/95 27 160 130,000 $10.00-$12.00 

Idaho Fescue 

(Festuca idahoensis) 

5 80/95 300 350 450,000 $11.00-$13.00 

Lemmon’s Needlegrass 

(Achnatherum lemmonii) 

8 50/95 150 750 150,000 $15.00-$18.00 

Mountain Brome 

(Bromus carinatus) 

10 80/95 800 800 70,000 $7.00-$9.00 

Needle and Thread Grass

(Hesperostipa comata) 

8 50/95 0 150 115,000 $25.00-$30.00 

Pinegrass 

(Calamagrostis rubescens) 

2 80/95 0 132 2,500,000 $27.00-$30.00 

Prairie junegrass 

(Koelaria macrantha) 

2 80/95 150 500 2,315,000 $12.00-$14.00 

Sandberg’s Bluegrass 

(Poa secunda) 

2 75/95 700 900 1,314,000 $8.00-$10.00 

Slender Wheatgrass 

(Elymus trachycaulus) 

8 80/90 50 350 130,000 $6.00-$8.00 

Thurber’s Needlegrass 

(Achnatherum thurberiana) 

7 50/95 0 150 225,000 $12.00-$14.00 

Tufted Hairgrass 

(Deschampsia cespitosa) 

2 80/90 109 509 2,500,000 $14.00-$16.00 

Western Needlegrass 

(Achnatherum occidentalis) 

8-10 50/95 103 189 275,000 $6.00-$8.00 

Common Yarrow 

(Achillea millefolium) 

2 85/95 165 165 3,000,000 $7.00-$9.00 

Pearly-everlasting 

(Anaphalis margaritacae) 

1 60/85 No Data No Data 8,000,000 $20.00-$25.00 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B-Botany 

 B-50 

a

 Quantity of Government furnished seed will need to be increased if germination and/or purity of seed are lower than recommended values. b

 Yield figures assume a late summer or fall sowing in year 0. 

C Estimated range of prices expected for task orders issued against R6 2003 grass and forb seed production contract (R6-14-03-14) 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Table C-2. Oregon and Washington State seed standards for Source Identified (SIA) class of seed. Where no standard exists, Kentstandards are frequently used for native grass seed, except Achnatherum and Hesperostipa species for which a minimum reasonable 

is 50.0%. 

Oregon State Standards Washington State Standards 

Factor Kentucky 

bluegrass 

ELGL BRCA5 Kentucky 

bluegrass 

ELGL BRCA5 FEID 

Pure Seed, Min. 92.0% 96.0% 90.0% 97% 90% 95% 97% 

Other Crop, Max. 0.25% 0.50% 0.50% 0.5% 0.5% 1.0% 0.5% 

Inert, Max. 8.0% 4.0% 10.0% 3% 10% 5% 3% 

Weed Seed*, Max. 0.30% 0.50% 0.30% 0.3% 0.3%a 0.3%a 0.3%a 

Weed Seed Max.**, 

Group A 

45/LB 27/LB 27/LB 

Germination, Min. 75% 65% 85% 80% 80% 85% 90% 

Max. seeds of other crop 

grass species 

0.25 0.25 0.25 0.25 

*

None of prohibited weeds in Section V, General standards, nor St. Johnswort, is allowed (Oregon). **

Group A: Buckthorn plantain, docks, sheep sorrel, bedstraw (Oregon). 

a A tolerance of 0.5% may be allowed for samples containing weedy Bromus spp. provided the total of all other weed seeds does not exceed 0.3%. b A tolerance of 0.8% may be allowed in certified wheatgrass containing small grain seed provided the total of all other crop seed does not ex

B-51
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B-Botany 

 B-52 

 

AOSCA Approved State Seed Testing Laboratories: 

Oregon State University Seed Testing Laboratory 

Oregon State University 

Campus Way 

Corvallis, OR 97331 

Telephone: 541-737-4464 

Fax: 541-737-2126 

Email: Seedlab@orst.edu

Website: www.css.orst.edu/seedlab

Washington State Department of Agriculture 

21 N. 1st Ave. #201 

Yakima, WA 

Telephone: 509-225-2630 

Fax: 509-454-4395 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Table C-3. Examples of some native grass and forb species useful for revegetation of disturbed sites on National Forests and Grass

Northwest. 

Species Preferred Soil Type Minimum Precipitatio n Pure Stand PLS Rate Per Acre Time of Seeding Comments 

Bluebunch 

wheatgrass 

Pseudoroegneria 

spicata 

Silt loam to 

clay 

10 inches 6-12 lbs. Fall/Spring Medium tall, tufted, cool season, long-lived perenni

deep roots and late phenology. Moderate establis

droughty and harsh sites with poor s

Blue Wildrye 

Elymus glaucus 

Sand to silt 

loam 

12 inches 10 lbs. Fall/Spring Cool season, tall, perennial bunchgrass. Adapted 

sites, moderately drought tolerant; productive on 

establishment; excellent for erosion co

Bottlebrush squirreltail 

Elymus elymoides 

Rocky/ 

sandy 

6 inches 8-10 lbs. Fall Medium tall, early to mid-seral, short-lived cool s

bunchgrass. Very drought tolerant; good establis

disturbed sites 

California oatgrass 

Danthonia californica 

Great Basin Wildrye 

Leymus cinereus 

Silt loam to 

clay 

8 inches 9-11 lbs. Fall/Spring Very tall and robust, long-lived cool season bunchg

by short rhizomes. Adapted to a wide range of sites

drought tolerant, but can also withstand periodic f

establish. 

Idaho Fescue 

Festuca idahoensis 

Silt loam to 

clay 

10 inches 8 lbs. Fall/Spring Short-medium, long-lived cool season bunchgra

drought tolerant. Slow to establish, but mature st

competitive. 

Lemmon’s 

needlegrass 

Achnatherum 

lemmonii 

Western needlegrass 

Achnatherum 

occidentale 

8-14 inches Strongly tufted, long-lived, cool season perennial b

and extensive fibrous root system. Strong seedling 

harsh and arid environments. Very good for e

Thurber’s 

needlegrass 

Achnatherum 

thurberiana 

6 inches 6-8 lbs. Fall/Spring Short, cool season bunchgrass. Drought 

B-53
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B-Botany 

 B-54 

Species Preferred Soil Type Minimum Precipitatio n Pure Stand PLS Rate Per Acre Time of Seeding Comments 

Mountain brome 

Bromus carinatus 

Silt loam to 

claay 

16 inches 19 lbs. Fall/Spring Tall, cool season, short-lived perennial bunchgrass 

range of sites. Rapid establishment; productive o

good for erosion control.. 

Needle and Thread 

Grass 

Hesperostipa comata 

Sand to silt 

loam 

10 inches 8-14 lbs. Fall/Spring Tall, long-lived (?) cool season bunchgrass. Very 

Pinegrass 

Calamagrostis 

rubescens 

Prairie junegrass 

Koelaria macrantha 

Sandy 12 inches 1-2 lbs. Fall/Spring Medium tall, cool season perennial bunchgrass. D

easy to establish; starts growth in very ear

Sandberg’s Bluegrass 

Poa secunda 

Sand to clay 8 inches 2-4 lbs. Fall/Spring Short, cool season perennial bunchgrass with shal

phenology. Drought tolerant and productive on po

establish, but mature stands are strongly c

Slender Wheatgrass 

Elymus trachycaulus 

Sand to clay 16 inches, or 

wetland/ripar

ian habitats 

12 lbs. Tall, cool season, short-lived perennial bunchgras

rhizomes. Adapted to a wide range of sites; mo

tolerance; saline tolerant. Establishes easily and q

for erosion control. 

Tufted Hairgrass 

Deschampsia 

cespitosa 

Silt loam to 

clay 

20 inches, or 

wetland/ripar

ian habitats 

1-2 lbs. Fall Medium tall, densely tufted cool season perennial b

to moist or riparian sites, but occurs on drier sites a

Performs well in standing water or periodic 

Slender hairgrass 

Deschampsia 

elongata 

Silt loam to 

clay 

20 inches, or 

wetland/ripar

ian habitats 

1-2 lbs. Fall Medium tall, cool season perennial bunc

Mannagrass 

Glyceria spp. 

Clay 18 inches, or 

wetland/ripar

ian habitats. 

12 lbs. Fall/Spring Medium tall, cool season, rhizomatous. Peren

streambank stabilization. 

Purple three-awn Aristida purpurea 

Sandy 10 inches 6 lbs. Fall/Spring Short-medium, warm season perennial bunchgrass

Rapid establishment. 

Sand dropseed 

Sporobolus 

cryptandrus 

Sand to 

sandy 

10 inches 1-2 lbs. Late summer Medium tall warm season perennial bunchgrass. D

easy to establish. Very good for erosion control an

establishing species. 

Western Yarrow 

Achillea millefolium 

Sand to 

sandy 

8 inches 1 lbs. Fall/Spring Mid-to-late seral, rhizomatous perennial forb. D

aggressive. Shade intolerant. 

Pearly -everlasting 20 0.5 Fall/Spring Requires full sun/shade intoleran
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Species Preferred Soil Type Minimum Precipitatio n Pure Stand PLS Rate Per Acre Time of Seeding Comments 

Anaphalis 

margartiacae 

Lupine spp. 

Lupinus spp. 

Silt loam to 

clay 

>10 inches 8-24 lbs. Fall/Winter Adapted to dry, open and shaded areas. Ni

B-55
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B-Botany 

 B-56 

Appendix D for the Revegetation Guidelines Document 

Non-native Species for Use in Revegetation 

Table D-1. Information on non-persistent non-native annuals and sterile hybrids that may be useful in revegetation/restoration i

settings. The level of persistence of these plant materials may vary depending on local climate and site conditions, and seedings 

natural recovery to some degree. Check with your Forest Botanist, Geneticist, Soil Scientist, Ecologist, Range Conservationisttheir appropriateness, and for the variety that will perform best given the elevation, climate, and moisture conditions of the plan

and varieties are best planted in the fall, while others do better when seeded in the spring/summer. 

Common or 

Trade Name 

Scientific Name Comments

Regreen Agropyron X 

Triticum 

wheatgrass x wheat hybrid 

• Synthetic inter-species hybrid, 1/4 wheatgrass and 3/4 wheat, male sterile, but can set s

from a source of wheat pollen, annual, under good growing conditions can persist 3 sea

• Recommended seeding rate pure live seed (PLS) pounds per acre is 10 - 40 pounds (Gr

• cheap and available in commercial quantities, use for reveg of disturbed logging sites in 

Washington has not been very promising, seeds are large, difficult to stabilize on slopeserosion cover not very dense (Crowder 1995). 

• Due to the large size and weight of this seed, the recommended lbs/acre (usually 12 lbs

be adequate, due to low germination, or predation (Sandoval 1997). 

• All I can say is that we didn't get very good results [from Regreen] at all in tractor cut f

using anymore (Yates 1997). 

• High predation, the Regreen distributor told us to not put the seed out until the rains cam

this problem. Apparently, when the seed gets wet it is less palatable (Grenier 1997). 

• Revisited test plots last summer (1 season after seeding); ZERO Regreen in the plots. (• Not impressed, tough to compare because we used the Regreen on firelines mostly and 

areas; typically poor results on firelines (Lillybridge 1997). 

• Seeded in spring and fall, germination >85% for both seasons, worked well on road pri

for reducing surface erosion/runoff, (grades not exceeding 10%...usually 4-5%). Regreyears with native veg established (Lewis 1997). 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Common or 

Trade Name 

Scientific Name Comments

• Regreen used on lime pit mine restoration project seeded heavy (30-50 lbs/ac), germina

but at high elevation substrate was lime, where soil was mixed with the lime by the cat, cover was good, uniform (Finch 1997). 

• Not much success with Regreen, one problem was seeding too late in the fall so it sprou

killed; high bird predation, all our seeding more successful w/a thin layer of mulch is u

• Poor germination (3-5%) with REGREEN under hydromulch on gentle to steep slopes 

9,600’ in elevation. Rocky poor soils on upper end of sale may have been part of the pr2000). 

• Fremont NF (Paisley/Silver Lake RD?) seeded with REGREEN after 2002 wildfires. R• Willamette NF has not had good results with REGREEN, and no longer recommends it

2003). 

Pioneer 

Sterile triticale • May be used in plantings for short term erosion control by itself, or with slower to estab

Adapted to a wide range of soil and moisture conditions; advertised to perform better thsandy soils, infertilse soils, acid and alkaline soils (Landmark Seed Co.). , 

White oats, domestic oats, cultivated oats, white horse feed oats 

Avena sativa • The Federal Highway Administration seeded 20-seeds/square foot [100#'s/acre] of Cay

oats] and mulched with rice straw and tackifier along the edge of over a mile of Forest and it provided a good ground cover (Isle 1996). 

• On the 83,000 acre Fork Fire, found the oats that were sowed on steep chaparral slopes 

and uniformly, native seed sowed was much smaller and sparser, best erosion control wmulch, oats were sowed, and straw check dams and wattles in drainages (Isle 1997). 

• Oats germinate in fall but, if timed for a nurse crop for dormant natives it does not have 

obtain much growth before winter killed, not providing the best protection cover during advantage is no worry about competition from the oats the next spring; oat cover crop s1 to 1 1/2 bushels per acre (Hodges 1996). 

• Cool season, moderately drought tolerant annual, low competition to establishing peren

varieties not suitable for the northern temperate zones with long winters. In areas with should be planted in spring and in fall or spring in more temperate climates (Granite Se

• Quick, one year cover. Good for cool wet sites, but does well on dry sites too once it is 

Wayne Hamilton has be using it extensively on roadsides on MBRD and DRD [Mount NF] with great results if sowed in spring, fair in summer, poor in fall. 

B-57
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B-Botany 

 B-58 

Common or 

Trade Name 

Scientific Name Comments

Barley or cereal barley 

Hordeum vulgare • Disappeared the 2nd year except where salvage logging had occurred (Arch Rock Fire 1

had less erosion than unseeded plots in half the monitored areas, barley provided signifareas after 1st year on wildfire site (Cleveland Fire 1991), does not seem to persist beyo

disturbance (Beyers 1997). 

• Observations (Crystal Burn, Toiyabe NF, 1994) seeding with cereal barley inhibited the 

plant species in some areas in the short term, was still in evidence in areas that were disand areas that were not disturbed, in 1995-1996. In 1997, the amount of barley that waconsidered minimal. Those transects did not show native vegetation was inhibited. (V

• (The Eldorado NF) used [cereal] barley on a burn on 10/92. Where tractor logging has 

heads, a 2nd crop of barley is coming up. Elsewhere, 2nd year germination is poor, in so

annual flora took a hit, In 1995 the 1992 seeding of barley is now barely evident. Less ground cover is from barley and despite earlier concerns about the annuals; there was liimpact on the flora, not sure barley was cost-effective, not sure it really accomplished mproviding forage, barley may have some value on a very small scale on a case-by-case bwould be reluctant to use it on future fires (Foster 1995). 

• Sow winter barley or winter wheat, since it germinates in the cooler fall and gets better 

spring (Isle 1999). 

• Barley worked very well for us seeded in June/July along roadsides with no noxious we

plants such as fireweed began recolonizing the sites the same year we planted the barleyhave deeper root systems than others and some are better planted in the spring/summer some barleys are treated with a fungicide. Check with your local supplier before purch

• The Willamette commonly uses fall barley as a non-persistent annual with good results

with 1-2 local native species (Lippert 2003). 

• Used on 2002 Bisquit fire, Umpqua NF (Wayne.Rolle). Results pending. 

Cereal rye, common rye, or winter rye 

Secale cereale • Seeding rate is 55 lbs per acre, introduced, annual, but may occasionally act as biennial

crop, can contaminate wheat fields. Rye can be found throughout eastern CO in wheat fareas, major problem in the wheat fields in Colorado (CWMA 1997). Used for reveg, oand Dr. Weber says it is expanding its range in CO (Kratz 1995). 

• 9,000-acre fire from 1992 seeded with cereal rye, competed with the natives as well as 

2 years after the fire and STILL persists [1997] (Stubbs 1997). 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

B-59

Common or 

Trade Name 

Scientific Name Comments

• Have used on our district for 10+ years. The Sandhills soil tends to blow, especially in 

permittees hand sow around windmills, seeding rate high (55 lbs of seed/acre) we do Nwith any invasion of the rye into the native population of grasses, greens up really early pronghorn seem to appreciate it (Emly 1995). 

• Rye should not be used as temporary cover crop unless it can be mown prior to seed m

themselves and inhibit the germination of native perennials (Colorado Natural Areas Pr

• For the Mount Baker-Snoqualmie NF, the jury is still out on this species. Persists long

barley.

• Can be highly persistent in certain settings. Cures out early and is a high fire hazard.in 

regions.

Triticale Triticum aestivum X

Secale cereale 

• Use as cover crop in certain recreation and wildlife areas to provide temporary soil prot

to soil, and improve infiltration and aeration, use 25 - 40 pounds per acre (NRCS 1988)

• Cool season, drought tolerant, annual grass. Hybrid cross between common wheat and 

spring and winter varieties available. Seeding rate 60 - 100 pure live seed (PLS) poundrecommended (Granite Seed 2000). 

Winter wheat, soft white winter wheat, sterile wheat, common commercial wheat 

Triticum aestivum • Triticum aestivum strain 'madsen' used here with success, comes in thick the first year, 

pheasant and chukar food. Make sure it is sterile wheat (Brooks 1996). 

• Winter wheat continues to grow throughout the winter during any warm-ups, provides g

also compete against the natives in spring, and later shade out seedlings, the secret is to than you would for a commercial crop. 40 to 60 lbs/acre is recommended; helpful tool before the boot stage. This helps open the canopy, and stops volunteers (Hodges 1996). 

• Spring and winter varieties suitable for different climates. Seeding rate 60 - 100 (PLS) 

recommended (Granite Seed 2000). 

• Recommended in certain recreation and wildlife areas for soil protection and erosion co

-25 pounds per acre (NRCS 1988).

• UMA seeded after Tower and Wheeler fire, but at much reduced rates (20-30lb/acre)

Lolium perenne • Can be persistent in mesic environments. 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B-Botany 

 B-60 

References for the Table D-1:

Austin, Gay, Monitoring of timber sale, USDA Forest Service, Region 2, July 2000. 

Beyers, Jan L., "Use of Non-Persistent Non-Native Annuals for Fast Green-Up: How Much Do We Know About 

Their Effectiveness and Impacts?", USDA Forest Service, Pacific Southwest Research Station, Native 

Plant/Revegetation Workshop, Mt. Crested Butte, Co, August 1997. 

Brooks, Paula J., USDA Forest Service, Region 6, August 1997. Emly, Virginia, Computer message, USDA Forest 

Service, Region 2, September 1995. 

Clines, Joanna, Computer message, USDA Forest Service, Region 5, February 1997. 

CWMA (Colorado Weed Management Association), "Troublesome Weeds of the Rocky Mountain West", 4th 

edition, 1997. 

Crowder, Wayne, Computer message, Washington State University, September 1995. 

Finch, Doug W., "Comments on REGREEN - Results and Opinions", Paula Brooks, Region 6, February 1997. 

Foster, Mike, Computer message, USDA Forest Service, Region 5, Eldorado NF, July 1995. 

Granite Seed, "Granite Seed Catalog", Granite Seed Company, 2000. 

Grenier, Katie, "Comments on REGREEN - Results and Opinions", Paula Brooks, Region 6, February 1997. 

Hodges, Jeff, "Dormant Season Planting", The Native Grass Manager, September 1996. 

Isle, David, Computer message, USDA Forest Service, Region 5, September 1996. 

Isle, David, Computer message, USDA Forest Service, Region 5, February 1997. 

Isle, David, Computer message, USDA Forest Service, Region 5, June 1999. 

Johnny's Select Seeds, "Cover Crops", Spring 1999. 

Kratz, Andrew, Computer message, USDA Forest Service, Regional Office, Region 2, September 1995. 

Lewis, Lisa, "Comments on REGREEN - Results and Opinions", Paula Brooks, Region 6, February 1997. 

Lillybridge, Terry, “Comments on REGREEN - Results and Opinions", Paula Brooks, Region 6, February 1997. 

Lippert, Jenny, Computer email, USDA Forest Service, Region 6, February, 2003. 

Natural Resource Conservation Service, "Standard and Specifications Cover and Green Manure Crop - (Acre) 340", 

Technical Guide, Section IV, April 1988. 

Potash, Laura, "Comments on REGREEN - Results and Opinions", Paula Brooks, Region 6, February 1997. 

Potash, Laura, and Carol Aubry, “Memo To: “Owners of Mt Baker-Snoqualmie Native Plant Notebook, Second 

Edition””. November 18, 1998. 

Sandoval, Paul M., "Comments on REGREEN - Results and Opinions", Paula Brooks, Region 6, February 1997. 

Segotta, Dan, "Comments on REGREEN - Results and Opinions", Paula Brooks, Region 6, February 1997. 

Stanislaus National Forest, "Emergency Revegetation of the Stanislaus Complex Fire", H010 - VII - B2 - BAER, 

March 1989. 

Stubbs, Donna, Computer message, USDA Forest Service, Region 6, September 1997. 

Tasker, R.D., C.L. Curtis, and J. Stone, Wildfire, Ryegrass Seeding, and Watershed Rehabilitation. USDA Forest 

Service General Technical Report PSW - 109, pg. 115 - 124, 1989. 

Van Zuuk, Kathy, "Crystal Burn Monitoring", USDA Forest Service, Region 5, September 1997. 

Yates, Gene H., "Comments on REGREEN - Results and Opinions", Paula Brooks, Region 6, February 1997. 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B - Botany 

B-61

Appendix E for the Revegetation Guidelines Document 

Invasive Plant Species to Avoid or Minimize in 

in Revegetation and Landscaping Plantings 

Table E-1 contains a listing of non-native plant species that have commonly been used for decades in revegetation, landscaping, and 

wildflower/grass seed mixes. These species are no longer recommended for general use, however, because they are now known to be 

highly persistent and aggressive when introduced into native plant communities. In general, exotic species that have high reproductive 

output and are mid-to-late successional are among the most threatening and difficult to remove or control. 

Table E-1 was developed based on recommendations and findings from a variety of sources. 

On-line resources, including the Natural Resource Conservation Service’s PLANTS database and the 

USDA Agricultural Research Service’s INVADERS database, were searched for information on the 

invasiveness on each plant species (see Legend for web sites). Plant species marked with "CD" were 

chosen by 13 USFS botanists and range ecologists from 5 western states in the "Top 10 Intentionallysown Persistent Exotics" survey (Craig Dremann, 1998). They were noted for being especially 

aggressive in displacing native plant species and native plant communities throughout the western states. 

Species marked with "RMNP" were identified as "species of concern" (have the greatest potential for 

ecological impact) by researchers studying non-native vegetation the Rocky Mountain National Park. 

The Colorado Native Plant Society also developed a list of plants NOT recommended for use in 

revegetation, restoration, or gardening. 

On sites dominated by large populations of one or more of these aggressive exotics, plant materials of 

more desireable species may be extremely difficult to establish unless efforts are first taken to reduce or 

eliminate the unwanted species. In addition, some of the species listed in Table E-1 may continue to play 

an appropriate but limited role in revegetation of noxious weed sites in settings where more desirable 

species (native and non-native) are not anticipated to establish or compete well against the target weed 

species. These aggressive exotics should be used only after their risk to TES plant species and other 

components of biological diversity has been carefully evaluated.
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 

 B-62 Table E-1. Grass and forb species to avoid or minimize in revegetation/restoration projects. 

COMMON 

NAME 

SCIENTIFIC 

NAME NRCS INV RMNP NE & GP WISC C A CoNPS C D PCA R6 C

Canada bluegrass Poa compressa X X X X Crested wheatgrass 

Agropyron cristatum A. desertorum 

X X X 

Hard fescue or sheep fescue 

Festuca ovina var. ovina X X X 

Becoming natValley and vefrom native fefor use (B.Wi.Used in SW Odisturbed foreto persist once and shade it o

Intermediate wheatgrass 

Agropyron intermedium X X 

Kentucky bluegrass Poa pratensis X X X X X X X Red fescue Festuca rubra X Meadow fescue Festuca pratensis X X X Meadow foxtail Alopecurus pratensis X X Orchardgrass Dactylis glomerata X X X X X X X Quackgrass 

Agropyron repens (Elytrigia repens or Elymus repens) 

X X X X X X X 

Reed canarygrass 

Phalaris arundinacea (Phalarioides arundinacea) 

X X X X X X X 

Smooth brome or Hungarian brome grass 

Bromopsis inermis (Bromus inermis) X X X X X X X 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement A

B-63

COMMON 

NAME 

SCIENTIFIC 

NAME NRCS INV RMNP NE & GP WISC C A CoNPS C D PCA R6 C

Timothy Phleum pratense X X X X X Tall fescue 

Festuca arundinacea (Lolium arundinaceum) 

X X X 

Italian ryegrass common rye or annual ryegrass 

Lolium perenne ssp. 

Multiflorum X X X May be persis

environments 

Crab grass Digitaria sanguinalis XDogtail grass Cynosurus echinatus XAlfalfa Medicago sativa XSanfoin X Persistent Burnet XBirdsfoot trefoil Lotus corniculatus XDowny brome or cheatgrass Bromus tectorum X X X X X Common cont

seed and hay/

Rattail fescue X Common cont

seed and hay/

Wild oats Avena fatua X Common cont

seed and hay/

Tumbleweed mustard Sisymbrium loesellii X Common cont

seed and hay/

Conyza Canadensis X

Babysbreath Gypsophila paniculata X X X X X Sold in nurser

mixes 

Bouncing bet or soapwort 

Saponaria officinalis (Lychnis saponaria) X X X X X Sold in nurser

mixes 

Common yarrow (European variety) 

Achillea millefolium(European variety) X X X 

Note: there is variety of this species. 

Corn chamomile Anthemis arvensis X X Sold in nurser

mixes 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 

 B-64 

COMMON 

NAME 

SCIENTIFIC 

NAME NRCS INV RMNP NE & GP WISC C A CoNPS C D PCA R6 C

Dalmation toadflax 

Linaria dalmatica ssp. Dalmatica X X X X X Sold in nurser

mixes 

Dame’s rocket Hesperis matronalis X X X X X X Sold in nurser

mixes 

European wand loosestrife or Purple loosestrife 

Lythrum virgatum (see Lythrum salicaria) X X X X Sold in nurser

mixes 

Klamath weed or St. John’s wort 

Hypericum perforatum X X X X X X X X Sold in nurser

mixes 

Mayweed chamomile Anthemis cotula X X X Sold in nurser

mixes 

Oxe-eye daisy 

Leucanthemum vulgare (Chrysanthemum leucanthemum) 

X X X X X X X Sold in nurser

mixes 

Perennial sweetpea or perennial peavine 

Lathyrus latifolius X X X Sold in nurser

mixes 

Purple loosestrife Lythrum salicaria X X X X X X X X Sold in nurser

mixes 

Scentless chamomile, wild chamomile, or scentless mayweed 

Matricaria perforata (Matricaria inodora, Matricaria maritima, Tripleurospermum inodorum) 

X X X X Sold in nurser

mixes 

Toadflax or butter & eggs Linaria vulgaris X X X X X X Sold in nurser

mixes 

Sweet clover, white Melilotus alba X X X X X X X Sold in nurser

mixes 

Sweet clover, yellow Melilotus officianalis X X X X X X X Sold in nurser

mixes 

Bachelor button Centurea cyanus X Sold in nurser

mixes 

Forage kochia Kochia X Sold in nurser

mixes 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement A

B-65

COMMON 

NAME 

SCIENTIFIC 

NAME NRCS INV RMNP NE & GP WISC C A CoNPS C D PCA R6 C

Wild carrot Caucus carota XFoxglove Digitalis purpurea XWild radish Raphanus sativus XRed sorrel Rumex acetosella XCurly dock Rumex crispus XDandelion Taraxacum officinale XSalsify Tragopogon spp. XRed clover Trifolium pratense XVeronica Veronica serphyllifolia X
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B-Botany 

Legend for Table E-1:

NRCS --- Natural Resource Conservation Service’s PLANTS database, Invasive and/or noxious weed 

list, http://plants.usda.gov/plants/

INV --- USDA Agricultural Research Service’s INVADERS database for ID, MT, OR, WA, and WY, 

http://invader.dbs.umt.edu/Noxious_Weeds

RMNP --- Rutledge, et al., “An assessment of exotic plant species of Rocky Mtn National Park”. 

NE & GP - PLANTS database, “Invasive weeds of Nebraska and the Great Plains”, 

http://plants.usda.gov/plants/cgi_bin/invasive_all.cgi

WISC --- PLANTS database, “Invasive weeds of Wisconsin, WI”, 

http://plants.usda.gov/plants/cgi_bin/invasive_one.cgi?pub=WI

CA --- California Exotic Pest Plant Council, CalEPPC list, “Exotic pest plants of greatest ecological 

concern in California”, (http://www.caleppc.org/info/plantlist.html, October 19, 1999). 

CoNPS --- Colorado Native Plant Society, Boulder Chapter, 1997. Plant species not to use in gardening, 

reclamation and restoration. Handout from the Colorado Native Plant Society. 

CD --- Craig Dremann, 1999. Survey of Forest Service Botanists in the West, 

http://www.ecoseeds.com/weedmaps.html

PCA --- Plant Conservation Alliance, 2000. Invasive plants, http://www.nps.gov/plants/alien/ 

R6 – Recommendations for invasive plant species to avoid in seed mixes. Compiled by Forest Botanists 

botanists on Willamette and Umatilla National Forests . 

References for Table E-1

Barkworth, Mary, pers. com., 6/6/99. Dr. Barkworth is the Botanist in charge of the grasses for the Flora 

of North America, Intermountain Herbarium, Department of Biology, Utah State University. 

Bulkin, Steve. Personal communication. March, 2003 

California Exotic Pest Plant Council, 1999. “Exotic pest plants of greatest ecological concern in 

California”, Exotic pest plant list (http://www.caleppc.org/info/plantlist.html). 

Dremann, Craig, 1998. "Weeds & persistent exotics on public lands", Craig's Juicy Native Grass Gossip 

No.6, ( http://www.ecoseeds.com/juicy.gossip.six.html ). 

Colorado Native Plant Society, Boulder Chapter, 1997. "Plant species not to use in gardening, 

reclamation and restoration ", Ft. Collins, CO. 

Kratz, Andy, 2000. Editing comments, USDA Forest Service, Rocky Mountain Regional Office. 

Lane, Eric, 1998. "Rules and regulations pertaining to the administration and enforcement of the Colorado 

Seed Act". 

Natural Resource Conservation Service, 1999. PLANTS database, “Invasive weeds of Wisconsin, WI”, 

http://plants.usda.gov/plants/cgi_bin/invasive_one.cgi?pub=WI

Rutledge, Chris, Dr. McLendon, Terry, 1996. "An assessment of exotic plant species in Rocky Mountain 

National Park". 

USDA Agricultural Research Service, 2000. INVADERS database system. http://invader.dbs.umt.edu/

 B-66 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 

Table E-2. Grass cultivars historically used on USDA National Forest Lands in Oregon and Washington 1

Release Name Scientific Name Common Name Release Year Plant Type Origin 

Gen

Backg

and Se

Meth

Bromar Bromus marginatus 

Nees ex. Steud

mountain 

bromegrass 

1946 Short-lived 

perennial 

bunchgrass 

Pullman, WA Mass s

from 

tested 

yea

Canbar Poa secundaJ. Presl Canby bluegrass 1979 Perennial bunchgrass Blue Mts, WA 

Covar Festuca ovina L. sheep 

fescue 

1977 Perennial 

bunchgrass 

Konya, Turkey 

Critana Elymus lanceolatus 

(Scribn. & J.G. Sm.) 

Gould ssp. 

lanceolatus 

streambank 

wheatgrass 

1971 Perennial 

sod-former 

Havre, Montana 

Durar Festuca 

trachyphylla(Hack.) 

Krajina

hard fescue 1949 Long-lived 

perennial 

bunchgrass 

Introduced plants from 

Ashkhabad, Turkmenistan 

grown near Union, Oregon 

Elkton Elymus glaucus ssp.

Jepsonii 

blue wildrye 1997 Short-lived 

perennial 

bunchgrass 

Elkton, Oregon 1 pop

from 40

1 This table is part of an internal white paper and journal article being prepared by Forest Service geneticists and researchers to describ

and genetic constitution of cultivar releases that have been used on federal lines in the Pacific Northwest. 

B-67
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B-Botany A

 B-68 

Table E-2. Grass cultivars historically used on USDA National Forest Lands in Oregon and Washington 1

Release Name Scientific Name Common Name Release Year Plant Type Origin 

Gen

Backg

and Se

Meth

Goldar Pseudoroegneria 

spicata (Pursh) A. 

Love ssp. Spicata 

bluebunch 

wheatgrass 

1989 Long-lived 

perennial 

bunchgrass 

Malley Ridge, 

Umatilla National Forest, 

Asotin, WA 

Diploid (

Greenar Thinopyrum 

intermedium 

intermediate 

wheatgrass 

1945 Sod-former USSR 

Joseph Festuca idahoensis Idaho fescue 1983 Perennial 

bunchgrass 

Idaho 20 clon

pla

interpoll

greenho

3 one

cyc

Latar Dactylis glomerata orchardgrass 1957 Long-lived 

perennial 

sod-former 

USSR 

Luna Thinopyrum 

intermedium 

intermediate 

wheatgrass 

1963 Perennial 

wheatgrass 

Ashkhabad, Turkmenistan 

Magnar Leymus cinereus basin wildrye 1979 Perennial 

bunchgrass 

Saskatchewan, Canada 

Manchar Bromus inermis smooth 

brome 

1943 Long-lived 

sod-former 

Manchuria, China 

Oahe Thinopyrum 

intermedium 

intermediate 

wheatgrass 

1961 Perennial 

sod-former 

Russia 4 clone

self- an

pollinate
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 

B-69

Table E-2. Grass cultivars historically used on USDA National Forest Lands in Oregon and Washington 1

Release Name Scientific Name Common Name Release Year Plant Type Origin 

Gen

Backg

and Se

Meth

Primar Elymus trachycaulus 

(Link) Gould ex 

Shinners ssp.

trachycaulus 

slender 

wheatgrass 

1946 long-lived 

perennial 

Beebe, MT Selecte

orig

colle

Schwendimar Elymus lanceolatus (Scribn. & J.G. Sm.) 

Gould ssp. 

lanceolatus 

thickspike 

wheatgrass 

1994 Long-lived 

perennial 

sod-former 

The Dalles, OR 

Secar * Pseudoroegneria 

spicata (Pursh) A. 

Love ssp. spicata 

bluebunch 

wheatgrass 

1980 perennial 

bunchgrass 

Lewiston, ID Tetraplo

4x = 

Sherman Poa secunda J. 

Presl

big 

bluegrass 

1945 Long-lived 

perennial 

bunchgrass 

Moro, OR 

Sodar Elymus lanceolatus 

(Scribn. & J.G. Sm.) 

Gould ssp. 

lanceolatus 

streambank 

wheatgrass 

1954 Long-lived 

perennial 

sod-former 

Canyon City, OR 

Whitmar Pseudoroegneria 

spicata (Pursh) A. 

Love ssp. Inermis 

(Scribn. & J.G. Sm.) 

A. Love

bluebunch 

wheatgrass 

1946 Long-lived 

perennial 

bunchgrass 

Whitman County, WA Mass s

from w

Diploid (
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix B-Botany 

APPENDIX F for the Revegetation Guidelines Document 

MULCH TYPES 

TYPE DESCRIPTION REQUIRED 

EQUIPMENT 

APPLICATION 

RATE CONSIDERATIONS COST (in 1995) 

USEFUL 

LIFE 

Straw Certified 

Weedfree Straw 

Hand 

application; blown 

on or applied 

by helicopter 

4000 lbs/ac 

(4”) on north 

slopes; 5000 

lbs/ac (5”) on 

south slopes 

Tough to put on 

extremely steep 

slopes except by 

helicopter. 

Inexpensive; 

effective 

$1000/ac 

by hand; 

$3000/ac 

by 

helicopter 

2 years 

Hydroseed 

Wood 

Cellulose 

Mulch 

Hydro mulch 

with wood 

cellulose mulch 

Applied with 

hydroseeding 

machine 

$2000 lbs/ac Hydroseeders are 

expensive to move 

in and are in short 

supply in the fall. 

Seeding cannot be 

kept current with 

construction. Very 

effective 

$1000/ac 

by hand; 

$3000/ac 

by 

helicopter 

1 year 

Hydroseed 

Paper Mulch 

Hydro mulch 

with paper 

mulch 

Applied with 

hydroseeding 

machine 

$2000 lbs/ac Same as above $1000/ac 

plus 

mobilization 

1 year 

Blankets 

(some come 

impregnated) 

Various types 

of premade 

erosion control 

blankets 

Rolled out 

and staked 

or pinned 

down 

By the square 

foot 

Netting 

decomposes at a 

different rate than 

mulch. Effective; 

expensive 

$.49-

3.50/sq yd 

for material 

only; add 

labor 

2 years 

Netting Various types 

of 

biodegradable 

& non 

degradable 

netting 

Rolled out 

and staked 

or pinned 

down 

By the square 

foot 

Can trap animals; 

decomposes slowly; 

used over mulch; 

biodegradable types 

available 

$.20-.50/sq 

yd for 

material 

only; add 

labor 

2 years 

Channel 

Liners 

Various width 

heavy-duty 

blankets 

Rolled out 

and staked 

or pinned 

down 

By the square 

foot 

Usually left in place. 

Effective; very 

expensive 

$3.00-

3.50/sq yd 

for material 

only; add 

labor 

1 year 

Tackifiers Sprayed on 

material used 

to hold soil in 

place 

Sprayed on, 

usually with a 

truck 

mounted 

sprayer 

By the square 

foot 

Short term $800/ac 

plus 

mobilization 

3 years 

Sodding Grass sod Rolled out 

and pinned 

down 

By the square 

foot 

Used when instant 

plant establishment 

is important 

$.17/sq ft; 

add 

delivery 

and labor 

indefinite 

 B-70 
Appendix C – Wildlife 

Exposure Groups 

Tables 5 – 9 Herbicides 

Summary of Herbicide Effects to Wildlife – Shawna Bautista 

 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 

This Page Left Blank Intentionally
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

 C-1

Exposure Groups for Forest Service Sensitive Wildlife 

Table C-1 displays the species group and the exposure scenario used in the SERA risk 

assessments (2001, 2003, and 2004). The individual species evaluated in this analysis (TES, 

MIS, SOLI) were placed into these exposure groups based on body size and food habits. 

Grouping various wildlife species facilitates calculation of estimated exposures to herbicides. 

Table C- 1 - Exposure groups, exposure scenarios, and species included in each group. 

Exposure 

Group 

Exposure 

Scenarios Species 1 

Large 

herbivorous 

mammal 

Consumption of 100% contaminated 

grass 

Rocky Mountain bighorn sheep, Rocky 

Mountain elk. 

Carnivorous 

mammals 

Consumption of an entire days diet of 

prey that has been directly sprayed on 

50% of body surface 

gray wolf, California wolverine, Pacific fisher, 

pine marten, Canada lynx. 

Small 

Insectivorous 

mammals 

Consumption of an entire day’s diet of 

contaminated insects spotted bat 

Herbivorous 

birds 

Consumption of 100% contaminated 

grass 

Greater sage grouse (adults), sharp-tailed 

grouse (adults). 

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) 

Greater sage grouse (chicks), sharp-tailed 

grouse (chicks), gray flycatcher, upland 

sandpiper, greater yellow-legs, tricolored 

blackbird, bobolink, pileated woodpecker, 

primary cavity excavators, landbirds and 

focal species, 

Predatory birds2 

Consumption of an entire day’s diet of 

small mammal prey that has been 

directly sprayed 

American peregrine falcon, Northern 

goshawk 

Piscivorous 

birds 

Consumption of fish contaminated by an 

accidental spill 

bald eagle, horned grebe, bufflehead, 

greater yellowlegs 

Reptiles 

None available. Information from 

literature is used. Painted turtle 

Amphibians 

For sulfometuron methyl, used water 

concentrations from runoff and 

percolation estimates. 

For other herbicides, information from 

literature is used 

Northern leopard frog, Columbia spotted 

frog. 

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. 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife

 C-2 

The general effects to wildlife from invasive plant treatments, and treatment standards are 

displayed in Table C-4. For sensitive species, dose estimates for each exposure group were 

obtained from Forest Service/ SERA risk assessments or calculated in project file worksheets 

using the Forest Service/SERA exposure scenarios. The exposure estimates were then compared 

to wildlife toxicity indices. Results of exposure scenarios for birds and mammals are found below 

in Table C-2 and Table C-3. 

When data is insufficient to estimate doses, information from literature is used to evaluate toxic 

effects. These doses and information from the literature are subsequently used to evaluate effects 

to the members of each exposure group in conjunction with diet, plausibility of exposure 

scenario, behavior, etc. 

Scientific uncertainty exists in extrapolating laboratory data to specific species and wild 

conditions. Laboratory species, and soil/air conditions may not accurately reflect in situation 

scenarios. Herbicides considered in this EIS have had comparatively little testing and analysis for 

amphibians and virtually no data exists for reptiles found in the Region. Also, data is insufficient 

to evaluate effects to predatory birds that eat primarily birds (i.e. American peregrine falcon), and 

ducks feeding primarily on aquatic insects (i.e. Harlequin ducks and bufflehead which are not 

present on the Forest). All these species need to be evaluated at the site-specific scale to 

determine the likelihood of exposure. 

Effects of the Alternatives on Sensitive Wildlife 

The invasive plant treatments projects were designed to reduce or eliminate adverse effects to 

sensitive species, as required in Treatment and Restoration Standard 22 for all alternatives; 

however, short-term, minor adverse effects (See individual species discussions) could occur under 

any alternative from the herbicide treatment methods. There may be some instances where it is 

most prudent to conduct a project that has a short-term adverse effect in order to provide a longterm beneficial effect to the habitat 

Table C-2 and Table C-3 display the different herbicides that may be used, with restrictions, in the 

action alternatives. The No Action Alternative, which continues treatment under the existing 

1994 EA, is limited to Glyphosate or Picloram. Dicamba was originally included in the list of 

approved herbicides for the 1994 EA, but was removed from use by the R6 2005 ROD. The 

exposure scenarios were compiled from the FS and SERA risk assessment found in the R6 2005 

FEIS. 

Symbol meanings are as follows for Tables C-2 and C-3: 

• -- Exposure scenario results in a dose below the toxicity index 

• × •Exposure scenario results in a dose that exceeds the toxicity index 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

 C-3

 Table C- 2 - Exposure scenario results from FS/SERA risk assessments for mammals, birds, and 

honeybees using the typical application rate and upper residue rates 

Animal/Scenario 

Chlorsulfuron 

Clopyralid 

Glyphosate 

Imazapic 

Imazapyr 

Metsulfuron methyl 

Picloram 

Sethoxydim 

Sulfometuron 

methyl 

Triclopyr 

NPE Surfactant 

ACUTE EXPOSURES 

Direct spray, bee -- -- -- -- -- -- -- -- -- -- 

Direct spray, sm. 

mammal 

-- -- -- -- -- -- -- -- -- -- 1

Consume Contaminated Vegetation 

small mammal -- -- -- -- -- -- -- -- -- -- -- 

large mammal -- -- -- -- -- -- -- -- -- -- 1

large bird -- -- -- -- -- -- -- -- -- 1 1

Consume Contaminated Water 

Spill, sm. mammal -- -- -- -- -- -- -- -- -- -- -- 

Consume Contaminated Insects 

small mammal -- -- -- -- -- -- -- -- -- -- 1

small bird -- -- -- -- -- -- -- -- -- 1 1

Consume Contaminated Prey 

carnivore (sm. 

mammal) 

-- -- -- -- -- -- -- -- -- -- -- 

predatory bird 

(sm. mammal) 

-- -- -- -- -- -- -- -- -- -- -- 

predatory bird 

(fish) 

-- -- -- -- -- -- -- -- -- -- -- 

CHRONIC EXPOSURES 

Consume Contaminated Vegetation 

small mammal, on 

site 

-- -- -- -- -- -- -- -- -- -- -- 

lg. mammal, on 

site 

-- -- -- -- -- -- -- -- -- 1 -- 

lg. bird, on site -- -- -- -- -- -- -- -- -- 1 -- 

Consume Contaminated Water 

small mammal -- -- -- -- -- -- -- -- -- -- -- 

Consume Contaminated Insects# 

small mammal -- unk -- -- -- -- unk unk unk unk unk 

small bird -- unk unk -- -- -- unk unk unk unk unk 

Consume Contaminated Prey 

carnivore (sm. 

mammal)# 

-- -- -- -- -- -- -- -- -- 1 -- 

predatory bird 

(sm. mammal)# 

-- -- -- -- -- -- -- -- -- -- -- 

predatory bird 

(fish) 

-- -- -- -- -- -- -- -- -- -- -- 

*Includes scenario for direct spray of a rabbit-sized mammal. 

# Data is lacking regarding chronic exposures, so effects are assumed by comparing acute dose vs. chronic NOAEL, and 

will likely over-estimate actual risk. 

unk – unknown; insufficient data to assess risk 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife

 C-4 

Table C- 3 - Exposure scenario results from FS/SERA risk assessments for mammals, birds, and 

honeybees using the highest application rate and upper residue rates 

Animal/Scenario 

Chlorsulfuron 

Clopyralid 

Glyphosate 

Imazapic 

Imazapyr 

Metsulfuron methyl 

Picloram 

Sethoxydim 

Sulfometuron 

methyl 

Triclopyr 

NPE Surfactant 

ACUTE EXPOSURES 

Direct spray, bee -- -- ♦ -- -- -- -- -- -- ♦

Direct spray, sm. mammal -- -- -- -- -- -- -- -- -- -- ♦

Consume Contaminated Vegetation 

small mammal -- -- -- -- -- -- -- -- -- -- ♦

large mammal -- -- ♦ -- -- -- -- -- -- ♦ ♦

large bird -- -- -- -- -- -- -- -- -- ♦ ♦

Consume Contaminated Water 

Spill, sm. mammal -- -- -- -- -- -- -- -- -- -- -- 

Consume Contaminated Insects 

small mammal -- -- ♦ -- -- -- ♦ -- -- ♦ ♦

small bird -- -- ♦ -- -- -- -- -- -- ♦ ♦

Consume Contaminated Prey 

carnivore (sm. mammal) -- -- -- -- -- -- -- -- -- -- -- 

predatory bird (sm. mammal) -- -- -- -- -- -- -- -- -- -- ♦

predatory bird (fish) -- -- -- -- -- -- -- -- -- -- -- 

CHRONIC EXPOSURES 

Consume Contaminated Vegetation 

small mammal, on site -- -- -- -- -- -- -- -- -- -- -- 

lg. mammal, on site -- -- -- -- -- -- -- -- ♦ ♦ -- 

lg. bird, on site -- ♦ ♦ -- -- -- -- ♦ ♦ ♦ -- 

Consume Contaminated Water 

small mammal -- -- -- -- -- -- -- -- -- -- -- 

Consume Contaminated Insects# 

small mammal -- unk unk -- -- -- unk unk unk unk unk 

small bird -- unk unk -- -- -- unk unk unk unk unk 

Consume Contaminated Prey 

carnivore (sm. mammal)# -- -- -- -- -- -- -- -- -- ♦ ♦

predatory bird (sm. 

mammal)# 

-- -- -- -- -- -- -- ♦ -- ♦ ♦

predatory bird (fish) -- -- -- -- -- -- -- -- -- -- -- 

•Includes scenario for direct spray of a rabbit-sized mammal 

# Data is lacking regarding chronic exposures, so effects are assumed by comparing acute dose vs. chronic NOAEL, 

which will likely over-estimate actual risk. 

unk – unknown; insufficient data to assess risk 

In terms of effects to sensitive species, there are no substantial differences between the different 

standards and PDFs in the alternatives or the alternatives as a whole. Therefore, the following 

table, Table C- 4, summarizes the potential effects to each sensitive species group. 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

 C-5

Table C- 4 - Potential effects from invasive plant treatment methods to groups of sensitive species 

Sensitive 

Species 

Group 

Potential Effects Determination 

Large 

herbivorous 

mammal 

Worst-case exposure exceeds toxicity index 

from ingesting forage that has glyphosate, 

picloram, sulfometuron methyl, triclopyr, or 

NPE surfactants if broadcast sprayed. Worstcase herbicide exposure is highly unlikely for 

non-selective herbicides; more likely for 

selective herbicides. 

MINL* 

Bighorns utilize cheatgrass. Worstcase exposure can be reduced by 

project design (Standard 22). 

Small 

herbivorous 

mammals 

Mechanical treatments may reduce cover and 

increase incidence of cheatgrass in certain 

habitat. Worst-case exposure exceeds toxicity 

index from ingesting forage that has been 

sprayed with triclopyr, or NPE surfactants if 

broadcast sprayed. Worst-case herbicide 

exposure is highly unlikely for non-selective 

herbicides; much more likely for selective 

herbicides. 

MINL. 

Invasive plants threaten habitat. 

Short-term adverse effects provide 

long-term benefit. Worst-case 

exposure can be reduced by project 

design (Standard 22). 

Carnivorous 

mammals 

Infrequent and short-term disturbance from 

treatment projects could affect wolverines 

during breeding season. Worst-case exposure 

exceeds toxicity index from ingesting prey that 

has been sprayed with triclopyr. Worst-case 

herbicide exposure is highly unlikely. 

MINL. 

Invasive plants may degrade habitat 

for some prey. Short-term adverse 

effects provide long-term benefit. 

Worst-case exposure highly unlikely. 

Insectivorous 

mammals 

Mechanical treatments may reduce foraging 

areas over the short-term. Worst-case 

exposure exceeds toxicity index from ingesting 

prey that has been sprayed with clopyralid, 

glyphosate, picloram, sethoxydim, 

sulfometuron methyl, and triclopyr 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. Bats may forage 

over large areas, reducing exposure. 

Worst-case exposure can be reduced 

by project design (Standard 22). 

Herbivorous 

birds 

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, glyphosate, picloram, 

sethoxydim, sulfometuron methyl, and triclopyr 

if broadcast sprayed. Worst-case herbicide 

exposure is highly unlikely for non-selective 

herbicides; much more likely for selective 

herbicides. 

MINL. 

Invasive plants threaten habitat. 

Short-term adverse effects provide 

long-term benefit. Worst-case 

exposure can be reduced by project 

design (Standard 22). 

Insectivorous 

birds 

Manual and mechanical treatments 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, glyphosate, picloram, 

sethoxydim, sulfometuron methyl, and triclopyr 

if broadcast sprayed. Worst-case herbicide 

exposure is likely for grassland species on 

large projects. 

MINL. 

Invasive plants threaten habitat for 

some species. Short-term adverse 

effects provide long-term benefit. 

Worst-case exposure can be reduced 

by project design (Standard 22). 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife

 C-6 

Sensitive 

Species 

Group 

Potential Effects Determination 

Predatory birds 

Manual and mechanical treatments could 

disturb species during the nesting season or 

affect their prey base. Worst-case exposure 

exceeds toxicity index from ingesting prey that 

has been sprayed with sethoxydim, and 

triclopyr if broadcast sprayed. Worst-case 

herbicide exposure is unlikely except aerial 

spray of grasslands. 

MINL. 

Invasive plants may alter habitat for 

prey. Short-term adverse effects 

provide long-term benefit. Worst-case 

exposure can be reduced by project 

design (Standard 22). 

Piscivorous 

birds 

Manual and mechanical treatments could 

disturb species during the nesting season. 

Worst-case exposure does not exceed toxicity 

index for any herbicide. 

MINL. 

Invasive plants can reduce or eliminate 

preferred nesting habitat. Short-term 

adverse effects provide long-term 

benefit. 

Reptiles 

Mechanical treatments could trample or harm 

individuals. Insufficient data to determine 

potential effects from herbicides. 

MINL. 

Species have extensive distributions. 

Most adverse effects can be reduced 

by project design (Standard 22). 

Amphibians Applications or accidental spills of glyphosate 

or triclopyr, could harm or kill amphibians. 

MINL. 

Little overlap between invasive plants 

and amphibian habitat, except for 

riparian weeds. Herbicide exposure 

can be reduced by project design 

(Standard 22). 

* May Impact, Not likely to adversely impact 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

 C-7

 Tables C-5 – C-9 Herbicides 

Table C- 5 – Herbicides Analyzed in the Region 6 Invasive Plants EIS 

Chemical Name Selectivity Sample Trade Name 

Chlorsulfuron broad-leaf Telar, Glean, Corsair 

Clopyralid broad-leaf Transline, Stinger 

Dicamba* broad-leaf & woody Vanquish, Banvel 

Glyphosate No RoundUp, Rodeo, Accord, Aquamaster 

Imazapic some broad-leaf & 

some grasses 

Plateau 

Imazapyr No Arsenal, Chopper, Stalker, Habitat 

Metsulfuron methyl broad-leaf & woody Escort 

Picloram broad-leaf & woody Tordon 

Sethoxydim grasses Poast 

Sulfometuron methyl No Oust 

Triclopyr broad-leaf & woody Garlon, Pathfinder, Remedy 

* Not selected in the 2005 Record of Decision. Not currently available for use on forests in R6. 

Table C- 6 - Herbicide and nonylphenol polyethoxylate application rates to be used to treat invasive 

plants, including the incidental rates of application of the impurity hexachlorobenzene 

Herbicide 

Highest Application 

Rate 

Lbs. a.i./acre 

Typical 

Application Rate 

Lbs. a.i./acre* 

Lowest 

Application Rate 

Lbs. a.i./acre 

Chlorsulfuron 0.25 0.056 0.0059 

Clopyralid 0.50 0.35 0.10 

Glyphosate 7.00 2.00 0.50 

Imazapic 0.19 0.130 0.031 

Imazapyr 1.25 0.45 0.03 

Metsulfuron Methyl 0.15 0.03 0.013 

Picloram 1.00 0.35 0.10 

Sethoxydim 0.38 0.30 0.094 

Sulfometuron Methyl 0.38 0.045 0.03 

Triclopyr 6.00 1.00 0.10 

Nonylphenol Polyethoxylate 6.68 1.67 0.167 

Hexachlorobenzene# 0.000012 0.000004 0.0000024 

* pounds of active ingredient per acre 

#These application rates reflect the incidental rates of application of the impurity hexachlorobenzene. 

Source: USDA Forest Service 2003, SERA 1998, 2001, 2003 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife

 C-8 

An exposure scenario was developed when enough data was available for a particular type of 

animal, and a quantitative estimate of dose received by the animal type in the scenario was 

calculated (SERA 2007). The quantitative estimates of dose were compared to available toxicity 

data to determine potential adverse impacts. The most sensitive response (i.e. a sub-lethal effect 

that occurred at the lowest dose) from the most sensitive species was used to determine the 

“toxicity indices” (described below) for each herbicide. The following analysis relies on these 

types of effects and effects of possible herbicide toxicity to wildlife discussed throughout this 

analysis are based on this following terminology (USDA-FS 2005 appendix P). 

• NOAEL (No observed adverse effect level): An exposure level at which there is 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 analysis to determine a potential adverse effect 

when it is exceeded. Usually a NOAEL, but when data are lacking other values may be used. 

• Acute Exposure: A single exposure or multiple brief exposures occurring within a short time 

(24 hours for most species). 

• Chronic Exposure: Exposures that extend over the average lifetime or for a significant 

fraction of the lifetime of the species (exposure for 30 days for most species). Chronic 

exposure studies are used to evaluate the carcinogenic potential of chemicals and other longterm health effects. 

Whenever sufficient data was available to determine the dose that resulted in no observable 

adverse effects (NOAEL), the NOAEL was used as the toxicity index. If data were not sufficient 

to determine a NOAEL, other endpoints of toxicity were used, such as the lowest-adverse-effect 

level (LOAEL), or the dose that was lethal to 50 percent of the test population (LD50). When a 

LOAEL or LD50 was used as the toxicity index, standard EPA methods for applying an 

uncertainty factor to the toxicity index to determine a level of concern were used. The standard 

EPA method for listed terrestrial species is to take 0.1 of the LD50 (EPA/OPP 2004), which is the 

protocol used in this analysis when a NOAEL is not available. 

Table C- 7 - Toxicity indices for mammals used in the effects analysis. Indices represent the most 

sensitive endpoint from the most sensitive species for which adequate data are available 

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 

Dicamba 120 mg/kg 

Chronic NOAEL 45 mg/kg/day Rat Decreased pup growth at 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

 C-9

Herbicide Duration Endpoint Dose Species Effect Noted at LOAEL 

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 25 mg/kg Rat Decreased weight gain at 

500 mg/kg Metsulfuron 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, some dam 

Sethoxydim 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 

Sulfometuron 433 mg/kg 

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 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 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife

 C-10 

Table C-8 – Comparison Summary of Herbicides and NPE Surfactant 

Table C-8 categorizes the 10 herbicides considered in this analysis and displays their relative risk 

to wildlife from chronic and acute exposures. The categories are based on various criteria and 

while this information is displayed here to show relative risks associated with herbicides 

considered, it should be noted that risk from herbicide exposure from proposed activities were 

determined using data and methods outlined in the SERA risk assessments (2001, 2003, and 

2004). Also risks identified in Tables C-2 and C-3 do not take into account implementation of 

PDFs, species specific behavior or other factors that would reduce the likelihood that an animal 

would receive levels of herbicides used in the exposure scenarios.

Table C- 8 - Relative Comparison Summary of the 10 Herbicides and NPE Surfactant 

Herbicide & NPE Surfactant Wildlife Risk 

Chlorsulfuron, clopyralid, imazapic, imazapyr, 

metsulfuron methyl, sulfometuron methyl, 

sethoxydim 

LOWEST = Exposure scenarios result in doses 

below the toxicity indices for all acute exposures, 

even at highest application rates. 

Glyphosate, picloram 

MODERATE = Exposure scenarios result in doses 

that exceed the toxicity indices for some acute 

exposures, but only at highest application rates. 

Triclopyr, NPE-based surfactants 

HIGHER = Exposure scenarios result in doses that 

exceed the toxicity indices for some acute 

exposures at typical application rates. (Risk of 

chronic exposure is variable and depends on many 

factors, including life history of wildlife, and 

persistence and selectivity of herbicide. Most 

chronic exposure scenarios are highly unlikely.) 

It should be noted that broadcast applications would never exceed typical label rates shown in 

Table 6. Additionally for the purpose of this analysis it is assumed that the number of plausible 

exposure scenarios that exceed the toxicity indices is the same for the surfactant as it is for the 

herbicides. 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 no direct correlation between acres 

treated with herbicide and acres treated with NPE. 

Table C-9 – Exposure Scenarios 

For Table C-9 symbol meanings are as follows: 

-- Exposure scenarios result in a dose below the toxicity index at both the typical and highest 

application rates. 

1 Exposure scenarios result in a dose that exceeds the toxicity index at the typical and highest 

application rates. 

♦ Exposure scenarios result in a dose that exceeds the toxicity index at the highest application 

rate only. 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

 C-11

Table C- 9 - Summary of exposure scenario results for listed species 

SPECIES 

Chlorsulfuron 

Clopyralid 

Glyphosate 

Imazapic 

Imazapyr 

Metsulfuron methyl 

Picloram 

Sethoxydim 

Sulfometuron methyl 

Triclopyr 

NPE Surfactant 

Grizzly 

Bear -- -- ♦ -- -- -- -- -- ♦ 1 1

Gray Wolf -- -- -- -- -- -- -- -- -- 11 ♦

Canada 

Lynx -- -- -- -- -- -- -- -- -- 11 ♦

Woodland 

Caribou -- -- ♦ -- -- -- -- -- ♦ 1 1

American 

Brown 

Pelican 

-- -- -- -- -- -- -- -- -- -- -- 

No. Spotted 

Owl -- -- -- -- -- -- -- ♦1 -- ♦1 ♦1 

Marbled 

Murrelet -- -- -- -- -- -- -- -- -- -- -- 

Snowy 

Plover -- -- -- -- -- -- -- -- -- -- -- 

OSS 

butterfly2 -- -- ♦ -- -- -- -- -- -- ♦ ? 

Bliss R 

snail3 -- -- -- -- -- -- -- -- -- -- -- 

1 These scenarios exceed the toxicity index only for assumed chronic exposures, risks are 

actually unknown, but the chronic exposure scenarios are not plausible. 

2 Based on exposure scenario calculations for honeybee 

3 Based on water concentrations used to calculate exposure to fish, and information on toxicity to 

federally listed aquatic invertebrates from analysis used for the EIS. 

Source: SERA 1998, 2001, 2003, 2004 and USDA FS 2003. 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

 C-12 

Summary of Herbicide Effects to Wildlife – Shawna Bautista 

Summary of Herbicide Effects to Wildlife 

DRAFT 

Prepared by: Shawna L. Bautista, Wildlife Biologist, 

Invasive Plant EIS 

US Forest Service, Region 6 Regional Office, Portland, 

OR 

February 2005 

U.S. Fish and Wildlife Servic

Summary of Herbicide Effects to Wildlife 

This document is a summary of toxicity information presented in Forest Service Risk 

Assessments (SERA 1998, 2001, 2003) and some public literature. I summarized information 

found in the human health and ecological risk assessment sections of the risk assessments, and 

obtained literature published in peer-reviewed journals, from authors, and on the internet. I 

conducted the literature search primarily to verify figures in the risk assessments, or to find 

specific values - it was not a comprehensive search. Syracuse Environmental Research Associates 

(SERA) conducted very comprehensive searches of the literature when preparing the risk 

assessments, and also evaluated the research papers for quality of methods and analysis used. 

Citation Method Used in This Document 

Because a large number of risk assessments produced by SERA are the basis for this document, 

many of them were produced in the same year, and the inherent difficulty in accurately tracking 

citations designated by year and lower case letter (e.g. 2003a, 2003b, etc.), I have resorted to a 

different citation convention. For risk assessments produced by SERA, the author and year is 

followed by the chemical name analyzed in the cited risk assessment. For example, information 

taken from the glyphosate risk assessment produced by SERA in 2003 is cited as: (SERA 2003 

Glyphosate). Hopefully, this will avoid confusion when the inevitable rearranging of information 

takes place during editing. Information in this report is taken from risk assessments produced by 

SERA unless otherwise noted. 

Herbicides Analyzed 

The herbicides included in this summary are those being analyzed in the Region 6 Invasive Plant 

Environmental Impact Statement (EIS) (Table 1). These herbicides or formulations are registered 

for use in forestry applications, right-of-ways, or rangelands and are appropriate for use against 

invasive plant species in Region 6 of the USDA Forest Service. The mention of trade names or 

commercial products does not constitute endorsement or recommendation for use. 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

Table 1. Herbicides analyzed and some representative formulation names. 

Chemical Name Trade Name 

Chlorsulfuron Telar, Glean, Corsair 

Clopyralid Transline, Stinger 

Glyphosate RoundUp, Rodeo, Accord 

Imazapic Plateau 

Imazapyr Arsenal, Chopper, Stalker 

Metsulfuron methyl Escort 

Picloram Tordon 

Sethoxydim Poast 

Sulfometuron methyl Oust 

Triclopyr Garlon, Pathfinder, Remedy 

It is not feasible to evaluate specific effects to specific wildlife species at a regional scale. The 

effects of herbicide use must be evaluated at the site-specific scale before any projects involving 

herbicide use are authorized. However, it is useful to understand the general and relative risks that 

proposed herbicides pose to wildlife in the planning area. 

The following discussion will provide information on all herbicides considered in the USDA 

Forest Service, Pacific Northwest Region, Invasive Plant EIS. Refer to the following text box for 

terms and concepts about potential effects of herbicides. 

Terms and acronyms used in this document. 

Allometric = pertaining to allometry, the study and measure of growth. In toxicology, the study of 

the relationship of body size to various processes that may impact how chemicals affect the 

organism or how the chemicals are transported within the organism. 

bioconcentration = the net accumulation of a substance by an aquatic organism as a result of 

uptake directly from aqueous solution (i.e. water with other stuff mixed in). 

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). 

dose = the actual quantity of a chemical administered to, or absorbed by, an organism. 

gavage = a method of dose administration; the substance is placed directly in the stomach.. 

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Appendix C-Wildlife 

exposure = the amount of chemical in contact with an animal. 

LD

50 (lethal dose50) - The dose of a chemical calculated to cause death in 50% of a defined 

experimental animal population over a specified observation period. The observation period is 

typically 14 days. 

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. 

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. 

Toxicity index = in this document, it is the dose of herbicide used to determine the potential for 

an adverse effect to wildlife. It is the lowest dose reported to cause the most sensitive effect in the 

most sensitive species tested, and is usually a reported NOAEL for a sub-lethal effect, but may be 

an LD

50 (or a portion thereof) when data is lacking. 

a.e. = acid equivalent 

a.i. = active ingredient 

kg = kilogram, equivalent to 1000 grams or 2.2 pounds 

g = gram, equivalent to 1000 milligrams or about 0.035 ounce (28 g = 1 ounce) 

mg = milligram; 0.001 gram. 

mg/L = milligrams per liter; equivalent to ppm. 

mg/kg = milligrams per kilogram; equivalent to ppm. 

ppm = part(s) per million; equivalent to mg/L and mg/kg. 

ppb = part(s) per billion 

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 safety evaluation on wildlife including toxicity testing on representative species of 

birds, mammals, freshwater fish, aquatic invertebrates, and terrestrial and aquatic plants. An 

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Appendix C-Wildlife 

 C-15

ecological risk assessment uses the data collected to evaluate the likelihood that adverse 

ecological effects may occur as a result of herbicide use. 

The Forest Service conducts its own risk assessments, focusing specifically on the type of 

herbicide uses in forestry applications. The Forest Service contracts with SERA to conduct human 

health and ecological risk assessments for herbicides that may be proposed for use on National 

Forest System lands. The information contained in this EIS relies on these risk assessments. All 

toxicity data, exposure scenarios, and assessments of risk are based upon information in the 

SERA risk assessments unless otherwise noted. Typical application rates of herbicides and 

nonylphenol polyethoxylate (NPE) surfactant used in this analysis can be found in Table 2. 

Table 2. Herbicide and nonylphenol polyethoxylate application rates used to treat invasive plants. 

Included are the incidental rates of application of the impurity hexachlorobenzene. 

Herbicide 

Typical Application 

Rate 

lb ai/ac* 

Lowest Application 

Rate 

lb ai/ac 

Highest Application 

Rate 

lb ai/ac 

Chlorsulfuron 0.056 0.0059 0.25 

Clopyralid 0.35 0.1 0.5 

Glyphosate 2 0.5 7 

Imazapic 0.13 0.031 0.19 

Imazapyr 0.45 0.03 1.25 

Metsulfuron Methyl 0.03 0.013 0.15 

Picloram 0.35 0.13 1.0 

Sethoxydim 0.3 0.094 0.38 

Sulfometuron Methyl 0.045 0.03 0.38 

Triclopyr 1.0 0.1 10 

Nonylphenol Polyethoxylate 1.67 0.167 6.68 

Hexachlorobenzene# 0.000004 0.0000024 0.000012 

* pounds of active ingredient per acre 

#These application rates reflect the incidental rates of application of the impurity 

hexachlorobenzene. 

Source: USDA Forest Service 2003, SERA 1998, 2001, 2003 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

Herbicides are not pure compounds and they contain the active ingredient, impurities, adjuvants, 

inert ingredients, and may also contain surfactants. The effects of inert ingredients, adjuvants, 

impurities and surfactants to wildlife are discussed first, followed by a discussion of the effects of 

the active ingredients. 

Inerts, Adjuvants and Impurities 

Inert compounds are those that are intentionally added to a formulation, but have no herbicidal 

activity and do not affect the herbicidal activity. Inerts are added to the formulation to facilitate its 

handling, stability, or mixing. Impurities are inadvertent contaminants in the herbicide, usually 

present as a result of the manufacturing process. Adjuvants are compounds added to the 

formulation to improve its performance. They can either enhance the activity of an herbicide’s 

active ingredient (activator adjuvant) or offset any problems associated with its application 

(special purpose or utility modifiers). Surfactants are one type of adjuvant that makes the 

herbicide more effective by increasing absorption into the plant, for example. 

Inerts and adjuvants, including surfactants, are not under the same registration guidelines as are 

pesticides. The EPA classifies these compounds into four lists based on the available toxicity 

information. List 1 contains “inerts of toxicological concern”; List 2 contains “potentially toxic 

inerts, high priority for testing”; List 3 contains “inerts of unknown toxicity”; and List 4 contains 

“minimal risk inerts” or “inerts for which EPA has sufficient information to conclude that their 

current use patterns will not adversely affect public health or the environment.” If the compounds 

are not classified as toxic, then all information on them is considered proprietary and the 

manufacturer need not disclose their identity. Therefore, inerts and adjuvants generally do not 

have the same amount of research conducted on their effects, compared to active ingredients. 

Inert Ingredient Effects 

There is very little data regarding the effects to most wildlife species from inert ingredients 

contained in the 12 herbicides considered in this EIS. None of the inert ingredients included on 

EPA’s List 2, 3, or 4 need to be disclosed on the herbicide label, despite evidence that some 

compounds on these lists may cause adverse effects to laboratory animals and humans 

(Anonymous 1999; Cox 1999; Knight 1997; Knight and Cox 1998; Marquardt et al. 1998). EPA’s 

own website (http://www.epa.gov/opprd001/inerts/) states, “Since neither federal law nor the 

regulations define the term "inert" on the basis of toxicity, hazard or risk to humans, non-target 

species, or the environment, it should not be assumed that all inert ingredients are non-toxic.” 

Northwest Coalition for Alternatives to Pesticides (NCAP) obtained the identity of many inert 

ingredients through a Freedom of Information Act request; the list of inerts they obtained can be 

found at http://www.pesticide.org/FOIA/ 

Many of the inert ingredients are proprietary in nature and have not been tested on laboratory or 

wildlife species. SERA obtained clearance to access confidential business information (i.e. the 

identity of proprietary ingredients) and used this information in the preparation of the risk 

assessment. However, toxicity data to support any assessment of hazard or risk are usually very 

poor, even when the identity of the inert is known. 

Chlorsulfuron – The identity of inerts used in chlorsulfuron are confidential, but SERA reviewed 

them for preparation of the risk assessment (SERA 2003 Chlorsulfuron). EPA has not classified 

any of the inerts as toxic. These inert ingredients do not affect the assessment of risk 

Clopyralid – Identified inerts include monoethanolamine and isopropyl alcohol, both approved 

food additives. These inert ingredients do not impact the assessment of risk 5 

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Appendix C-Wildlife 

Glyphosate – There are at least 35 glyphosate formulations that are registered for forestry 

applications (SERA, 2003-Glyphosate) with a variety of inert ingredients. SERA obtained 

clearance to access confidential business information (i.e. the identity of proprietary ingredients) 

and used this information in the preparation of the risk assessment. Surfactants (discussed below) 

were the only additives identified that impact risk (SERA, 2003-Glyphosate). 

Imazapic - The identity of inerts used in imazapic formulations are confidential, but SERA 

reviewed them for preparation of the risk assessment (SERA, 2003-Imazapic). EPA has not 

classified any of the inerts as toxic. 

Imazapyr – The identity of inerts used in imazapic formulations are confidential, but SERA 

reviewed them for preparation of the risk assessment (SERA, 2003-Imazapyr). No apparently 

hazardous materials were identified in the review of inerts. The NCAP website 

(http://www.pesticide.org/FOIA/picloram.html) identifies only glacial acetic acid, an approved 

food additive, as an inert ingredient. Isopropanolamine is also present, and it is classified as a List 

3 inert. 

Metsulfuron methyl - The identity of inerts used in metsulfuron methyl formulations are 

confidential, but SERA reviewed them for preparation of the risk assessment (SERA, 2003-

Metsulfuron methyl). EPA has not classified any of the inerts as toxic. 

Picloram – The formulations Tordon K and Tordon 22K contain the following inerts: potassium 

hydroxide, ethoxylated cetyl ether, alkyl phenol glycol ether, and emulsified silicone oil (NCAP 

website; www.pesticide.org/FOIA/picloram.html). Potassium hydroxide is an approved food 

additive. The other compounds are all on EPA’s List 4B, inerts of minimal concern. They may 

also contain the surfactant polyglycol 26-2, which is on EPA’s List 3: Inerts of Unknown Toxicity, 

discussed in the following section. The toxicity data on the formulations encompasses toxic risk 

from the inerts. Inerts in picloram formulations do not appear to pose a unique toxic risk to 

wildlife (SERA, 2003-Picloram). 

Sethoxydim - The formulation Poast® contains 74 percent petroleum solvent that includes 

naphthalene. The EPA has placed this naphthalene on List 2 (“agents that are potentially toxic and 

a high priority for testing”). Petroleum solvents and naphthalene depress the central nervous 

system and cause other signs of neurotoxicity (SERA, 2001). Poast® has also been reported to 

cause skin and eye irritation. There is no information suggesting that the petroleum solvent has a 

substantial impact on the toxicity of sethoxydim to experimental animals, with the important and 

notable exception of aquatic animals (SERA, 2001). Poast® is much more toxic to aquatic 

species than sethoxydim. 6 

Sulfometuron methyl - The identity of inerts used in Oust are confidential, but SERA reviewed 

them for preparation of the risk assessment (SERA, 2003-Sulfometuron). EPA has not classified 

any of the inerts as toxic. Based on comparison of the toxicities of the active ingredient and the 

formulation, there is no reason to suspect that Oust contains other ingredients that substantially 

affect the potential risk to wildlife. 

Triclopyr - Formulations contain ethanol (Garlon 3A) or kerosene (Garlon 4), which are known 

to be neurotoxic. However, the toxicity of these compounds is less than that of triclopyr, so the 

amount of ethanol and kerosene in these formulations is not toxicologically significant (SERA, 

2003-Triclopyr) for wildlife. 

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Appendix C-Wildlife 

Surfactant Effects 

Surfactants, or surface-acting agents, facilitate and enhance the absorbing, emulsifying, 

dispersing, spreading, sticking, wetting, or penetrating properties of herbicides. There is a fair 

amount of research on the effects of surfactants to terrestrial and aquatic organisms because they 

are widely used in detergents, cosmetics, shampoos and other products designed for human 

exposure. 

The following information is taken from “Analysis of Issues Surrounding the Use of Spray 

Adjuvants With Herbicides” (USDA FS, 2002) and “Human and Ecological Risk Assessment of 

Nonylphenol Polyethoxylate-based (NPE) Surfactants in Forest Service Herbicide Applications” 

(USDA FS, 2003). Refer to these documents for more complete discussions. 

Some glyphosate formulations contain polyethoxylated tallow amine (POEA) surfactant, which is 

substantially more toxic to aquatic species than glyphosate or other surfactants that may be used 

with glyphosate (SERA, 2003-Glyphosate, p. 4-14). In the SERA risk assessment, the toxicity of 

glyphosate is characterized based on the use of a surfactant, either in the formulation or added as 

an adjuvant in a tank mixture (SERA, 2003-Glyphosate, p. 4-14). 

Polyglycol 26-2, used in picloram, will impact mitochondrial function in vitro, but information is 

insufficient to evaluate risks to wildlife in vivo from field applications at plausible levels of 

exposure (SERA, 2003-Picloram). 

The primary active ingredient in many of the non-ionic surfactants used by the Forest Service is a 

component known as nonylphenol polyethoxylate (NPE). NPE is found in these commercial 

surfactants at rates varying from 20 to 80 percent. NPE is formed through the combination of 

ethylene oxide with nonylphenol (NP), and may contain small amounts of un-reacted NP. The 

properties of the particular NPE depend upon the number of ethoxylate groups that are attached to 

the NP. The most common NPE used in surfactants with pesticides is a mixture that has, as a 

majority, 8-10 ethoxylate groups attached, and can be abbreviated NP9E. NP is a material 

recognized as hazardous by the U.S. EPA (currently on U.S. EPA’s inerts List 1). Both NP and 

NPE exhibit estrogen-like properties, although they are much weaker than the natural estrogen, 

estradiol. 

Potential effects of NPE were analyzed using exposure scenarios to quantitatively estimate the 

dose of NPE that birds and mammals may receive if they consumed contaminated vegetation or 

prey, or if a small mammal was directly sprayed. Each estimated dose was compared to toxicity 

levels reported from laboratory data and summarized in USDA FS 2003. Data is lacking on the 

toxic effects of NP or NPE to birds, with only the median lethal dose (LD50) identified in the 

literature. Risk to birds is therefore evaluated using the toxicity values from mammals, which 

introduces additional uncertainty into the conclusions regarding birds. Data for terrestrial 

invertebrates is lacking or insufficient, so risks cannot be adequately characterized. 

NP and NPE are weakly estrogenic in aquatic and terrestrial organisms (1000 to 100,000 times 

weaker than natural estrogen). NP and NPE are not toxic to soil microbes. NP is highly toxic to 

many aquatic organisms at low concentrations (currently on U.S. EPA’s Inert List 1). 

The use of NPE-based surfactants in any of the 12 herbicides considered in this EIS could result 

in toxic effects to some mammals and birds at typical and high application rates (project file 

worksheets; USDA, FS 2003). The exposure scenarios and calculated doses used in the analysis 

represent worst-case scenarios and are not entirely plausible. At the typical application rate, 

adverse effects could occur to small mammals that may be directly sprayed, large mammals and 

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Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

large birds consuming contaminated vegetation, and small mammals and small birds consuming 

contaminated insects. At the highest application rate, adverse effects could occur to small 

mammals that may be directly sprayed, large or small mammals and large birds consuming 

contaminated vegetation, small mammals and small birds consuming contaminated insects, and a 

predatory bird consuming a small mammal that has been directly sprayed. No chronic exposures 

result in plausible risk to mammals or birds. 

NP and NPE have been studied for effects to aquatic organisms. NP is more toxic than NP9E, by 

one to three orders of magnitude (USDA FS, 2003). The toxicities of the intermediate breakdown 

products, NPEC and others, are intermediate between NP and NPE. In the aquatic environment, 

the breakdown products NP1EC and NP2EC are likely to be present also. These two metabolites 

are known to affect vitellogenin (a precursor for egg yolk) production in male fish, but NP, which 

is a more potent estrogenic compound, did not cause vitellogenin increases in male Xenopus 

laevis, or leopard frogs (Selcer et al., 2001; cited in USDA FS, 2003). 

Mann and Bidwell (2000, 2001) tested several Australian frogs and Xenopus for effects to NP8E. 

They found that Xenopus was the most sensitive to toxic effects, with an LC50 of 3.9 ppm (3.9 

mg/L). Similar to studies with herbicides, the LC50 values for the frogs are comparable to those 

for fish (USDA FS, 2003). NP8E inhibited growth at concentrations as low as 1 ppm (Mann and 

Bidwell, 2000, 2001). Mild narcosis of tadpoles can occur at EC50 values as low as 2.3 ppm, and 

reduced dissolved oxygen content in the water lowered the EC50 values by about half as compared 

to normal oxygen levels. The tadpoles recovered from the narcosis. Malformations in Xenopus 

occurred at EC

50 values between 2.8 and 4.6 mg/L. 

NP may cause tail resorption with a 14-day NOEC of 25 ppb for Xenopus laevis (Fort and Stover, 

1997; cited in USDA FS, 2003). NP also increased the percentage of female Xenopus developing 

from tadpoles exposed to 22 ppb for 12 weeks, but did not produce this effect at 2.2 ppb. 

During operational use of NPE surfactant, ambient levels of NP9E (including a small percentage 

of NP, NP1EC, and NP2EC) could average 12.5 ppb (range 3.1 to 31.2 ppb). The duration of 

these exposures from Forest Service use would generally be much shorter than those used in 

laboratory experiments, due to transport by flowing streams, dilution, and environmental 

degradation. These levels are not likely to adversely affect amphibians found in the Pacific 

Northwest for normal operations. However, overspray or accidental spills could produce 

concentrations of NP9E that could adversely affect amphibians, particularly in small stagnant 

ponds. 

Effects of Impurities 

All herbicides likely contain impurities as a result of the synthesis or production process. The 

toxic effects of impurities are addressed in toxicity tests using the technical grade product, which 

would contain the impurities. 

Hexachlorobenzene is an impurity in the technical grade products of clopyralid and picloram. 

Hexachlorobenzene is a ubiquitous and persistent chemical in the environment, as it is used or 

present in a wide variety of manufacturing processes. It has been shown to cause tumors in mice, 

rats and hamsters, and EPA has classified it as a probable human carcinogen (SERA, 2003-

Picloram). The amount of hexachlorobenzene released into the environment from Forest Service 

use of picloram and clopyralid is inconsequential in comparison to existing background levels 

and the annual release from manufacturing processes (SERA, 2003-Picloram, pp. 3-25). The use 

of picloram and clopyralid in remote forest locations could constitute the primary source of 

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Appendix C-Wildlife 

localized contamination however. The projected amounts of hexachlorobenzene released during 

invasive plant treatments is calculated to be well below the level that poses a risk to cancer in 

mammals. 

POEA surfactant used in Roundup and Roundup Pro contain 1,4-dioxane as an impurity, which 

has been classified by EPA as a probable human carcinogen. Based on current toxicity data and an 

analysis by Borrecco and Neisess (1991), the potential effects of 1,4-dioxane are encompassed by 

the available toxicity data on the Roundup formulation (SERA, 2003-Glyphosate). Borrecco and 

Neisess (1991) also demonstrated that the upper limit of risk of cancer from this impurity was less 

than one in a million. 

Triclopyr contains an impurity, 2- butoxyethanol (aka EGBE), that is a major industrial chemical 

used in a wide variety of industrial and commercial applications. It is known to cause fragile red 

blood cells in rodents (Borrecco and Neisess 1991). EGBE has been classified as moderately 

toxic by EPA. Borrecco and Neisess (1991) found that potential doses of EGBE to mammals were 

less than 0.001 of the lowest LD

50 and did not substantially increase risk over the risk identified 

for triclopyr, even under worst case scenarios. Data on toxicity of EGBE to birds was lacking, but 

the authors conclude that comparative sensitivities between birds and mammals, and the 

extremely low doses indicated a low risk to birds. 

Metabolites 

Similar to impurities, the potential health effects of herbicide metabolites are often accounted for 

in the available toxicity studies, assuming that the toxicological effects of metabolism within the 

test animal species would be similar to those in other animals. The potential toxic effects of 

environmental metabolites (those formed as a result of processes outside of the body) may not be 

accounted for by laboratory toxicity studies. 

TCP (3,5,6-trichloro-2-pyridinol) is an environmental metabolite of triclopyr. In mammals, TCP 

has about the same toxicity as triclopyr. No quantitative estimate of exposure to mammals or 

birds was calculated in the SERA risk assessment, due to the lack of appropriate data. However, 

since TCP is as toxic as triclopyr, the risk characterization for triclopyr could be applied to TCP. 

Site-specific analysis is necessary to further evaluate the risk of toxic effects from TCP. 

Endocrine disruption 

Recent information has highlighted the potential for certain synthetic and natural chemicals to 

affect endocrine glands, hormones, and hormone receptors (endocrine system). The endocrine 

system helps control metabolism, body composition, growth and development, reproduction, and 

many other physiological regulators. An endocrine disrupter is a substance that may exert effects 

to the body by affecting the availability of a hormone to its target tissue(s) and/or affecting the 

response of target tissues to the hormone (SERA, 2002). Estrogen is a prominent hormone in 

animal systems and substances that mimic estrogen or stimulate similar responses in target tissues 

are referred to as “estrogenic.” 10 

Scientists have expressed concern regarding estrogenic effects of synthetic chemicals since before 

the 1970’s. The EPA (1997) reports effects of endocrine disruption in animals that “include 

abnormal thyroid function and development in fish and birds; decreased fertility in shellfish, fish, 

birds, and mammals; decreased hatching success in fish, birds, and reptiles; demasculinization 

and feminization of fish, birds, reptiles, and mammals; defeminization and masculinization of 

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Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

gastropods, fish, and birds; decreased offspring survival; and alteration of immune and behavioral 

function in birds and mammals.” 

Some of the more noted endocrine glands include gonads, adrenal, pancreas, thyroid and 

pituitary. Alteration in endocrine function may affect reproductive output (i.e. feminization, 

masculization), and therefore, could affect population numbers of affected species. 

Many of the known endocrine disrupting contaminants have been banned or are regulated (e.g. 

DDT/DDE, PCB, TCDD). Some endocrine disrupting compounds are persistent and are still 

found within the living tissue of wildlife; their decomposition half-life is lengthy, and they are 

bioaccumulatory and present at high background levels. A local example is the high level of 

DDT/DDE and PCB that are found within peregrine falcons in the Pacific Northwest (Pagel, 

unpub. data). Research has suggested that embryonic exposure to endocrine disrupters may cause 

permanent health effects to adult animals. Some of these effects may include altered blood 

hormone levels, reduced fecundity, reproductive behavioral alterations, reduced immune function, 

masculization and feminization, undescended testicles, increased cancer rates, altered bone 

density and structure, and malformed fallopian female reproductive tract (Kubiak et al., 1989; 

Colborn and Clement, 1992; White et al., 1994; Fry, 1995; LeBlanc, 1995). Examples of wildlife 

species that have been adversely affected by endocrine disrupters include wood ducks in 

Arkansas, wasting and embryonic deformities of Great Lakes piscivorous birds, reproductive 

abnormalities of snapping turtles, gulls, trout and salmonids, alligators, mink, and Florida panther 

(Bishop et al. 1991, Colborn, 1991; Facemire et al., 1995; Fox et al., 1978, 1981, 1991 (a, b); Fry 

and Toone, 1981; Fry et al., 1987; Giesyet et al., 1994; Gilbertson et al., 1991; Guillette et al., 

1994, 1995; Kubiak et al., 1989; Mac and Edsall, 1991, 1993; Leatherland, 1993; Peakall and 

Fox, 1987; White and Hoffman, 1995; and Wren, 1991). 

Of the chemicals analyzed in this DEIS, 2,4-D and NPE surfactants have been identified as 

potentially having estrogenic effects (USGS, 1998; Bakke, 2003). Triclopyr and glyphosate have 

been evaluated for endocrine disrupting effects, and the weight of evidence indicates that these 

herbicides cause no specific toxic effects on endocrine function (SERA, 2002). One study on 

glyphosate, Yousef et al. (1995), indicated that there may be some concerns with glyphosate, but 

the study was poorly conducted and results are not reliable. 

Sulfometuron methyl can cause malformations in amphibians (SERA, 2003-Sulfometuron), but 

whether the malformations are caused by endocrine disruption, cellular toxicity, or other pathway 

has not been reported. 

Synergistic Effects 

Certain chemicals may cause synergistic effects in the presence of other chemicals: that is, the 

total effect of two chemicals may be greater than that suggested by the sum of the effects from the 

individual components (USEPA, 2000). However, information regarding the existence or 

potential for synergistic effects from the herbicides discussed in this document is very limited. 11 

Some of the herbicides analyzed in this document (e.g. 2,4-D and picloram) have been 

investigated for possible synergistic effects but the study designs were insufficient for the 

assessment of toxicologic interactions (SERA, 2003-Picloram; p. 3-35) However, data on this 

potential effect is incomplete and not likely to be obtained in the foreseeable future: the sheer 

number of potential combinations of contaminants, environmental stressors, and wildlife species 

make it unfeasible to investigate thoroughly. 

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Appendix C-Wildlife 

USEPA (2000) did state that for exposures at low doses, with low risk for each component in the 

chemical mixture, that the likelihood of significant interaction (e.g. synergistic effects) is usually 

considered to be low. Likewise, a report by ATSDR (2004) cited several studies using rats that 

found no synergistic effects for mixtures of four, eight and nine chemicals at low (sub-toxic) 

doses. But statistically significant interactions (both syntergistic and antagonistic) have been 

noted in some studies. Unfortunately, even with excellent data, the uncertainties and complexities 

of chemical interactions create substantial uncertainty in the risk characterization for chemical 

mixtures (ATSDR, 2004; USEPA, 2000). 

Effects of Active Ingredients and Surrogate Species 

Generally, active ingredients have been tested on only a limited number of species and mostly 

under laboratory conditions. While laboratory experiments can be used to determine acute 

toxicity and effects to reproduction, cancer rates, birth defect rates, and other effects that must be 

considered, laboratory experiments do not account for wildlife in their natural environments. This 

leads to uncertainty in the risk assessment analysis. Environmental stressors can increase the 

adverse effects of contaminants, but the degree to which these effects may occur for various 

herbicides is largely unknown. Adverse affects to wildlife health such as lethargy, weight loss, 

nausea, and fluid loss due to diarrhea or vomiting, can affect their ability to compete for food, 

locate and/or capture food, avoid or fight off predators, or reproduce. The following analysis 

relies on these types of effects, when sufficient data exists, rather than lethal doses, to determine 

the potential for doses to cause an “adverse effect” to wildlife. 

FS/SERA risk assessments and published literature are the primary sources of information used to 

evaluate effects of herbicides to wildlife. First, we discuss field studies found in the published 

literature regarding potential effects of herbicide use to wildlife. Then, qualitative and 

quantitative information from the FS/SERA risk assessments and published literature regarding 

effects of active ingredients are discussed. 

Toxicity Data and Exposure Analysis 

The FS/SERA risk assessments present the toxicity data from studies conducted to meet EPA 

registration requirements and from published literature. In addition, exposure of various animals 

to herbicide is quantitatively estimated to characterize risk from the use of each herbicide. 

The Use of Surrogate Species 

Most toxicity testing utilizes surrogate species. Surrogate species serve as a substitute for the 

species of interest, because all species of interest could not be tested. Surrogate species are 

typically organisms that are easily tested using standardized methods, are readily available, and 

inexpensive. Rare species are not tested and the physiological requirements for some organisms 

prohibit their use in toxicity testing because these requirements cannot be met within the test 

system. Even when desired species are available (e.g. salmon), researchers may choose a 

surrogate, like zebrafish (Danio rerio)(aka zebra danio), because test results are more easily 

discerned with the surrogate, and reproductive capacity allows testing of large numbers of 

individuals, among other reasons (Scholz, unpublished. proposal, 2003). 

However, caution should to be taken when addressing ecological risk and the use of surrogates 

when analyzing those ecological risks. Some herbicides demonstrate more variation than others in 

effects among different species, and very limited numbers of species have been tested. 

 C-22 
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Appendix C-Wildlife 

Because of the variation of responses among species, and the uncertainty with regard to how 

accurately a surrogate species may represent other wildlife, the FS/SERA risk assessments use the 

most sensitive endpoint from the most sensitive species tested as the toxicity index for terrestrial 

wildlife. This does not alleviate concerns over interspecies variations in response, however. 

Doses and Responses 

The likelihood that an animal will experience adverse effects from an herbicide depends on: (1) 

the inherent toxicity of the chemical, (2) the amount of chemical to which an animal is exposed, 

(3) the amount of chemical actually received by the animal (dose), and (4) the inherent sensitivity 

of the animal to the chemical. 

The toxicity of the chemical is measured by laboratory tests required by EPA. The amount of 

chemical to which an animal may be exposed is influenced by several factors, discussed below. 

When an animal is exposed to a chemical, only a portion of the chemical applied or ingested is 

actually absorbed or taken in by the animal (the dose). Various absorption rates for wildlife are 

not available, so some scenarios use the same value for exposure and dose. Also, different species 

have different susceptibilities to various chemicals. This is discussed more in the section on 

surrogates. 

Factors that Influence Exposure and Dose 

The exposure of an animal to an herbicide is greatly influenced by relationships between body 

size and several physiological, metabolic, and pharmacological processes (allometry). For 

example, allometric relationship dictates that animals of smaller size have a larger amount of 

surface area for their mass than larger animals. This relationship greatly influences basic 

physiological properties, such as food consumption and thermoregulation. Some of the allometric 

factors that influence exposure to herbicides are detailed below. 

Body Weight 

Several parameters used to estimate herbicide contact are reported on a “per body weight” basis, 

expressed in grams (g) or kilograms (kg). For example, both food and water ingestion rates are 

reported on a per body weight basis (such as gram of fresh food or water per gram of fresh body 

weight per day). Body weights, in units of mass, are reported as fresh weight that might be 

obtained by weighing a live animal in the field. Also, body weight data are used in empirical 

models to calculate some parameters, such as surface area, when there no specific measurements 

are available. Calculations of “potential dose to animal” use body weight of animals. 

Metabolic Rate 

Metabolic rate is not directly calculated in this document, or in the FS/SERA risk assessments, 

but reported values for various species are used to calculate food consumption requirements. It is 

reported on the basis of kilocalories per day for units of body weight (kcal/kg/day). Metabolic 

rate is closely related to body size, with smaller animals generally having higher metabolic rates 

than larger animals. 

Contact Rate 

Exposure involves direct contact with the herbicide, and wildlife may be exposed to herbicides by 

ingesting the chemical (oral) or by external contact (dermal). Oral exposures may occur from 

eating contaminated vegetation or prey, drinking contaminated water, or by grooming activities. 

Dermal exposures may occur from direct spray, or contact with contaminated vegetation or water. 

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Appendix C-Wildlife 

These contact routes are influenced by allometric relationships, as well as habitat preferences and 

feeding behaviors. 

Oral Routes 

Food ingestion: Small animals generally have higher caloric requirements than large animals, so a 

small animal ingests a greater amount of food per unit body weight compared to large animals. A 

20g mouse, for example, will generally consume an amount of food equal to about 15 percent of 

its body weight every day, depending on calorie content of the diet. A value of 3.6 g of food 

consumed per day for a 20g mouse is used in the FS/SERA risk assessments for calculating 

exposure from contaminated food. This is equivalent to 18 percent of the body weight and is 

generated from general allometric relationships for food consumption in rodents (US EPA/ORD, 

1993, p. 3-6, as cited in SERA, 2003-Glyphosate). This value may underestimate exposure to 

small mammals that consume primarily vegetation, rather than seeds (SERA, 2003a). Food 

consumption is calculated from caloric requirements for different sized animals for the various 

exposure scenarios in the FS/SERA risk assessments. 

Dietary composition: Dietary composition is an important consideration in exposure assessments 

because different foods have varying herbicide residues. Grasses may have substantially higher 

residues than fruits or other vegetation (Kenaga, 1973; Fletcher et al. 1994; Pfleeger et al., 1996). 

The FS/SERA risk assessments use data from Siltanen et al. (1981) for concentrations on fruit. 

Also, small insects may contain higher residues than large insects, based on empirical 

relationships (Pfleeger et al., 1996). Some herbicides have the potential to bioaccumulate in fish; 

therefore fish-eating birds may be exposed. Caloric content of various foods, with caloric 

requirements of animals, is used to estimate daily amount of food consumed based on data from 

US EPA/ORD 1993 (as cited in SERA, 2003-Glyphosate). In the FS/SERA risk assessments, 

exposure scenarios use a large herbivore consuming 100 percent grass diet, a large bird 

consuming grass, a small bird consuming small insects, and a predatory bird consuming 

contaminated fish (SERA, 2003-Glyphosate, p. 4-14 to 4-15). 

Water ingestion: There are well-established relationships between body weight and water 

consumption across a wide range of mammalian species. Mice, weighing about 20 g (0.02 kg) 

consume about 0.005 L of water/day (i.e. 0.25 L/kg/day). These values are used in the exposure 

scenarios for small mammals. Since the body size to volume relationship dictates that smaller 

animals will receive larger doses for a given exposure, consumption of contaminated water is not 

calculated for larger animals. Water ingestion is obviously influenced by environmental factors, 

such as heat and availability. But estimates for the variability in water consumption are not 

available for wildlife. 

Grooming: Birds and mammals may spend a great deal of time grooming fur or feathers. If the 

animal has been exposed to herbicide, some chemical may be absorbed through the grooming 

process. However, a study by Gaines (1969, as cited in SERA, 2001) suggests that grooming is 

not significant in the toxic response of small mammals. At any rate, the doses received from 

grooming would be less than those received through contaminated food or direct spray, given the 

assumptions in the exposure scenarios. See dermal exposure route information below. 

Dermal Route 

Dermal contact can occur from direct spray or contact with contaminated vegetation or water. 

Since only a small portion of an applied herbicide would be available as dislodgeable residue on 

vegetation, or in a water body where it was diluted, dermal exposure is modeled only for direct 

spray scenarios in FS/SERA risk assessments. The extent of dermal contact for an animal depends 

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Appendix C-Wildlife 

on the application rate of the herbicide, the surface area of the animal, and the rate of absorption. 

Since a larger proportion of a small animal’s body would be involved, relative to larger animals, 

direct spray scenarios are only conducted for a small mammal and a honeybee in FS/SERA risk 

assessment (SERA, 2001). Skin, fur and feathers provide some protection from chemicals, and 

not all of the chemical on an animal will be absorbed. Amphibians may be an exception, since 

their skin may be much more permeable than the skin of a mammal or bird. In this document, we 

assume that the skin affords no protection at all (e.g., 100 percent absorption). Scenarios with a 

different assumption regarding absorption may be found in the various FS/SERA risk 

assessments. The approach taken here (100 percent absorption) may account for multiple 

absorption pathways, such as dermal absorption plus that from grooming or preening. However, 

there is no quantitative data available regarding this assumption. The actual dose received after 

dermal exposure is also influenced by the specific herbicide considered since different herbicides 

have different dermal absorption rates and properties (SERA, 2001, section 3.9). 

Summary of Exposure Scenarios 

An exposure scenario was developed, and a quantitative estimate of dose received by the animal 

type in the scenario was calculated when enough data was available (SERA, 2001). While it is 

possible to model exposure in a very large number of non-target animals, highly species-specific 

exposure assessments are of little use in the absence of species specific dose-response data 

(SERA, 2001). The exposure assessment should not be more complicated than the dose-response 

assessment. Therefore, exposure scenarios used in this document are calculated when doseresponse data for specific herbicides indicate that one group and/or size of animal may be more 

sensitive than others. For example, if data indicates that larger mammals may be more sensitive 

than smaller mammals, separate exposure scenarios have been developed for each. In the absence 

of such data, only exposures for small mammals may be calculated because they would receive 

the highest dose per kg body weight. 

The exposure scenarios that are used in the Ecological Risk Assessments (SERA, 2001) and/or 

for this EIS (project file worksheets) are as follows: 

Acute Exposures 

20 g mammal: A mouse-sized mammal is directly sprayed over 50 percent of body surface area 

and 100 percent absorption occurs over one day. A “mouse” consumes contaminated vegetation, 

daily food consumption equal to 18 percent of body weight (a value between seed diet and 

vegetation diet needs), and one day’s diet is 100 percent contaminated. A “mouse” consumes 

contaminated insects, daily food consumption equals 50 percent of body weight, and one day’s 

diet is 100 percent contaminated. A “mouse” consumes contaminated water (volume water 

consumed is based on allometric relationship) after spill of 200 gallons into a small pond (with no 

dissipation or degradation of the herbicide). 

5 kg mammal: A fox-sized animal consumes small mammal prey that has been contaminated by 

direct spray. Daily food consumption equals 8 percent of body weight. 

70 kg mammal: A deer-sized animal consumes contaminated grass (grass has higher herbicide 

residues), daily food consumption is 14.16 kg/day (equal to 20 percent of body weight), and one 

day’s diet is 100 percent contaminated. 

4 kg bird: A goose-sized bird consumes contaminated grass and one day’s diet is 100 percent 

contaminated. 

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Appendix C-Wildlife 

 C-26 

10 g bird: A small, passerine-sized bird consumes contaminated small insects and one day’s diet is 

100 percent contaminated. 

Predatory bird: A bird-of-prey consumes fish that has been contaminated by an accidental spill of 

200 gal into a small pond. Assumptions used include no dissipation of herbicide, bioconcentration 

is equilibrium with water, contaminant level in whole fish is used, and upper estimate assumes 15 

percent of body weight eaten/day. A spotted-owl sized bird consumes small mammal prey that has 

been contaminated by direct spray. 

Terrestrial invertebrate: A honeybee (0.093g) is directly sprayed and 100 percent absorption 

occurs over one day. 

Chronic Exposures 

20 g mammal: A mouse-sized mammal consumes contaminated vegetation for 90 days (upper 

estimate assumes 20 percent of diet is contaminated), and the herbicide dissipates over time. A 

“mouse” consumes contaminated ambient water for an extended period. 

70 kg mammal: A deer-sized mammal consumes contaminated grass for 90 days (upper estimate 

assumes 100 percent of diet is contaminated), and the herbicide dissipates over time. 

16Preventing and Managing Invasive Plants Final Environmental Impact Statement April 2005 

DRAFT 

4kg bird: A goose-sized bird consumes contaminated grass for 90 days (upper estimate assumes 

100 percent of diet is contaminated), and herbicide dissipates over time. 

Predatory bird: A bird-of-prey consumes fish from contaminated water over a lifetime. 

Assumptions used include dissipation and degradation of herbicide is considered, 

bioconcentration is equilibrium with water, contaminant level in whole fish is used, and upper 

estimate assumes 15 percent of body weight eaten/day. 

No data are available to estimate chronic exposures from contaminated insects or mammal prey, 

so risk from chronic exposure is estimated using the acute dose compared to the chronic toxicity 

index. 

In this document, only the highest ranges of exposure assumptions are included, although a more 

complete range of possible values is included in the SERA risk assessments. For example, for a 

given herbicide, residues of the herbicide on vegetation that are reported in the literature will vary 

between studies and by vegetation type. A range of residue rates is used in the SERA risk 

assessment worksheets, but only the highest reported rates are used in the data reported here. 

Only the highest values are used here to reduce length and complexity of this document and also 

to present a reasonable “worst-case” exposure analysis. 

Estimated doses from the above exposure scenarios are compared to toxicity levels from 

laboratory research. The lowest reported dose that caused the most sensitive effect in the most 

sensitive species is used in this analysis to indicate the potential for an adverse effect when that 

dose is exceeded. These doses are referred to as “toxicity indices” in this document, and 

NOAEL’s are used whenever possible. If available data have not identified a NOAEL, then an 

LD

50 or other level may be used. Table 3 lists the toxicity indices for mammals and Table 4 lists 

the toxicity indices for birds. 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

Following the tables are summaries of herbicide effects to birds and mammals, reptiles, 

amphibians, and terrestrial invertebrates based on the results of the analysis and information in 

the literature. The likelihood that potential adverse effects would occur is then discussed followed 

by a brief summary of some of the available field studies. The document concludes with detailed 

descriptions of the exposure scenario results for each scenario and herbicide. 

Table 3. Toxicity indices for mammals used in the effects analysis. Indices represent the most 

sensitive endpoint from the most sensitive species for which adequate data are available. 

Herbicide Duration Endpoint Dose Species Effect Noted at 

LOAEL 

Chlorsulfuron Acute NOAEL 75 mg/kg Rabbit Decreased weight 

gain at 200 mg/kg 

Chronic NOAEL 5 mg/kg/day Rat Weight changes at 25 

mg/kg/day 

Clopyralid Acute NOAEL 75 mg/kg Rat Decreased weight 

gain at 250 mg/kg 

Chronic NOAEL 15 mg/kg/day Rat Thickening of gastric 

epithelium at 150 

mg/kg/day 

Dicamba Acute – 

larger 

mammal 

NOAEL 3 mg/kg Rabbit Weight loss, 

increased postimplant losses, 

decreased number 

of live young at 10 

mg/kg 

Acute – smaller 

mammal 

NOAEL

1

30 mg/kg Rat Neurotoxic effects (e.g. 

impaired gait) at 300 

mg/kg 

Chronic – all sizes NOAEL 3 mg/kg/day Rabbit Weight loss, increased 

post-implant losses, 

decreased number of live 

young at 10 mg/kg 

Glyphosate Acute NOAEL 175 

mg/kg 

Rabbit Diarrhea at 350 

mg/kg 

Chronic NOAEL 175 mg/kg/day Rabbit Diarrhea at 350 mg/kg 

Imazapic Acute NOAEL 350 

mg/kg 

Rabbit Decreased body 

weight at 500 

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Appendix C-Wildlife 

 C-28 

Table 3. Toxicity indices for mammals used in the effects analysis. Indices represent the most 

sensitive endpoint from the most sensitive species for which adequate data are available. 

Herbicide Duration Endpoint Dose Species Effect Noted at 

LOAEL 

mg/kg 

Chronic NOAEL

2

45 mg/kg Dog Microscopic muscle 

effects at 137 mg/kg 

Imazapyr Acute NOAEL 250 

mg/kg 

Dog No effects at 

highest doses tested 

Chronic NOAEL 250 mg/kg/day Dog No effects at highest 

doses tested 

Metsulfuron 

methyl 

Acute NOAEL

3

25 mg/kg Rat Decreased weight 

gain at 500 mg/kg 

Chronic NOAEL 25 mg/kg/day Rat Decreased weight gain at 

125 mg/kg 

Picloram Acute NOAEL 34 mg/kg Rabbit Decreased weight 

gain at 172 mg/kg 

Chronic NOAEL 7 mg/kg Dog Increased liver weight at 

35 mg/kg

4

Sethoxydim Acute NOAEL 160 

mg/kg

5 Rabbit Reduced number of 

viable fetuses, some 

dam mortality at 

480 mg/kg 

Chronic NOAEL 9 mg/kg/day Dog Mild anemia at 18 

mg/kg/day 

Sulfometuron 

methyl 

Acute NOAEL 87 

mg/kg 

Rat Decreased body weight at 

433 mg/kg 

Chronic NOAEL 2 mg/kg/day Rat Effects on blood and bile ducts 

at 20 mg/kg/day 

Triclopyr

6

Acute NOAEL 100 

mg/kg 

Rat Malformed fetuses at 300 

mg/kg 

Chronic

7

NOAEL 0.5 mg/kg/day Dog Effect on kidney at 2.5 

mg/kg/day 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

 C-29

2,4-D Acute “nonlethal” 10 

mg/kg 

Rat & 

Dog 

Effects on kidney, blood, 

and liver 

Chronic NOAEL 1 mg/kg/day Rat & 

Dog 

Effects on kidney, blood, and 

liver at 5 mg/kg/day 

NPE Surfactants Acute NOAEL 10 

mg/kg 

Rat Slight reduction of 

polysaccharides in liver at 

50 mg/kg/day 

Chronic NOAEL 10 mg/kg/day Rat Increased weights of liver, 

kidneys, ovaries, and decreased 

live pups at 50 mg/kg/day 

1 Small animals are less susceptible than larger animals. NOAEL estimated from LOAEL of 300 

mg/kg/day for neurotoxic effects, using safety factor of 10 to extrapolate from a LOAEL to a 

NOAEL. Identical to observed NOAEL for neurotoxicity in rabbits (Hoberman 1992). 

2 Imazapic – NOAEL calculated from a LOAEL of 137 mg/kg/day and application of a safety 

factor of 3 to 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 (BASF 1980, MRID 

00045864 cited in SERA, 2003-Triclopyr). 

6 Triclopyr BEE and TEA have equal toxicities to mammals (SERA, 2003a). 

7 Value taken from Quast et al. 1976 as cited in SERA Triclopyr 2003. 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. Toxicity indices for birds used in the effects analysis. Indices represent the most sensitive 

endpoint from the most sensitive species for which adequate data are available. 

Herbicide Duration Endpoint Dose Species Effects Noted at LOAEL 

Chlorsulfuron Acute NOAEL 1686 

mg/kg 

Quail No significant effects at 

highest dose 

Chronic NOAEL 140 

mg/kg/day 

Quail No significant effects at 

highest dose 

Clopyralid Acute NOAEL 670 

mg/kg 

Mallard & 

Quail 

No signs of toxicity 

reported, LOAEL not 

determined 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

 C-30 

Table 4. Toxicity indices for birds used in the effects analysis. Indices represent the most sensitive 

endpoint from the most sensitive species for which adequate data are available. 

Herbicide Duration Endpoint Dose Species Effects Noted at LOAEL 

Chronic

1

NOAEL 15 

mg/kg/day 

Rat Thickening of gastric 

epithelium at 150 mg/kg/day 

Chronic NOAEL 13.6 

mg/kg/day

2 Quail Neurotoxic effects at 27 

mg/kg/day 

Glyphosate Acute NOAEL 562 

mg/kg 

Mallard & 

Quail 

No effects at highest 

dose 

Chronic NOAEL 100 mg/kg Mallard 

& Quail 

No effects on reproduction at 

highest dose 

Imazapic Acute NOAEL 1100 

mg/kg 

Quail No effects at highest 

dose 

Chronic NOAEL 113 

mg/kg/day 

Quail Decreased weight gain in 

chicks at 170 mg/kg/day 

Imazapyr Acute NOAEL 674 

mg/kg 

Quail No effects at highest 

dose 

Chronic NOAEL 200 

mg/kg/day 

Mallard 

& Quail 

No effects at highest dose 

Metsulfuron 

methyl 

Acute NOAEL 1043 

mg/kg 

Quail No significant effects at 

highest dose 

Chronic NOAEL 120 

mg/kg/day 

Mallard 

& Quail 

No significant effects at 

highest dose 

Picloram Acute NOAEL 1500 

mg/kg 

Chicken & 

pheasant 

No effect to 

reproduction. LOAEL 

not reported 

Chronic

3

NOAEL 7 

mg/kg/day 

Dog Increased liver weight at 35 

mg/kg/day 

Sethoxydim Acute NOAEL >500 

mg/kg 

Mallard & 

Quail 

No or low mortality at 

highest doses tested. 

LOAEL not available. 

Chronic LOAEL

4

10 

mg/kg/day 

Mallard Decreased number of normal 

hatchlings at 10 mg/kg/day 

Sulfometuron Acute NOAEL 312 Mallard Decreased weight gain 
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Appendix C-Wildlife 

 C-31

Table 4. Toxicity indices for birds used in the effects analysis. Indices represent the most sensitive 

endpoint from the most sensitive species for which adequate data are available. 

Herbicide Duration Endpoint Dose Species Effects Noted at LOAEL 

mg/kg 

methyl at 625 mg/kg/day 

Chronic

5

NOAEL 2 mg/kg/day Rat Effects on blood and bile 

ducts at 20 mg/kg/day 

Triclopyr BEE

6

Acute LD

50

388 

mg/kg 

Quail 50% mortality at 388 

mg/kg 

Chronic NOAEL 10 mg/kg/day Mallard & 

quail 

Decreased survival of 

offspring, reduced 

eggshell thickness at 20 

mg/kg/day 

Triclopyr TEA Acute LD

50

535 

mg/kg 

Quail 50% mortality at 535 

mg/kg 

Chronic NOAEL 10 mg/kg/day Mallard & 

Quail 

Decreased survival of 

offspring, reduced 

eggshell thickness at 20 

mg/kg/day 

Chronic

7

NOAEL 1 mg/kg/day Rat & dog Effects on kidney, blood, 

and liver at 5 mg/kg/day 

NPE 

Surfactants

9 Acute NOAEL 10 mg/kg Rat Slight reduction of 

polysaccharides in liver 

at 50 mg/kg/day 

Chronic NOAEL 10 mg/kg/day Rat Increased weights of 

liver, kidneys, ovaries, 

and decreased live pups 

at 50 mg/kg/day 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

1 Chronic toxicity studies in birds are not available, so the value from mammal studies is used. 

2 Higher reported NOAEL for chronic dietary exposure is 92 mg/kg/day, with no signs of 

neurotoxicity. The lower value from acute exposures is used in FS/SERA risk assessment for 

chronic exposures as a more protective toxicity index. 

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. 

9 Data on birds is not available in published literature. This information from an unpublished 

study referred to in USDA FS 2003. Since information is lacking, this value is used for 

illustrative purposes only and no attempt is made to quantify risk to birds from NPE surfactants. 

Source: SERA 1998, 2001, 2003, 2004; USDA FS 2003; and Weed Science Society of America 

2002. 

Summary of Herbicide Effects to Birds and Mammals 

The data available for mammals are derived from numerous studies conducted to meet 

registration requirements, and primarily on laboratory animals that serve as surrogates. Data for 

mammals are available for more types of toxicity tests and often on a wider variety of species 

than are available for birds. 

Availability of information on the direct toxicological effects of the 12 herbicides on wild 

mammals varies by herbicide. Glyphosate and 2,4-D have been widely studied, including field 

applications. Little or no data on wildlife may exist for other herbicides. Herbicides have been 

tested on only a limited number of species under conditions that may not well-represent 

populations of free-ranging animals (SERA 1998, 2001, 2003). 

Toxicity data available for birds are derived from studies conducted to meet registration 

requirements, and primarily on domestic birds that serve as surrogates. There are typically fewer 

types of toxicity studies conducted on birds using a more restricted variety of species than are 

conducted for mammals. Almost all laboratory data is collected on mallards and northern 

bobwhite. How the sensitivities of different bird species to herbicides may vary from that 

reported for mallard and bobwhite is not known. 

Tables 5 and 6 summarize the results of exposure scenarios for the 12 herbicides and NPE 

surfactants considered in this analysis. Chlorsulfuron, imazapic, imazapyr, and metsulfuron 

methyl do not appear to pose any plausible risk to terrestrial wildlife or bees at either the typical 

or highest application rates. When an herbicide does pose plausible risk, it is consistently 

insectivorous and grass-eating animals that are most likely to receive doses above the toxicity 

index. Direct spray of mammals is a concern only for 2,4-D, and NPE surfactants at the typical 

application rate, and additionally, dicamba at the highest application rate. 

 C-32 
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Appendix C-Wildlife 

Fish-eating birds do not receive a dose above the toxicity index for any herbicide or application 

rate. Consumption of contaminated water, even as the result of an accidental spill, results in doses 

well below the toxicity index for all herbicides. For the herbicides considered in this analysis, 

birds are less sensitive than mammals to acute exposures. Chronic toxicity data on birds is often 

limited. 

Dicamba, triclopyr, and 2,4-D have the highest potential to adversely affect wildlife. Dicamba has 

a relatively low acute toxicity to adult animals, in terms of direct lethal doses, but adverse effects 

on reproduction and nervous systems occur at much lower doses. Dicamba shows a consistent 

pattern of increased toxicity to larger sized animals, across several species and animal types (i.e. 

birds and mammals). Dicamba exposures exceed the toxicity indices for five scenarios at the 

typical application rate, and nine scenarios at the highest application rate. 22 

Triclopyr TEA and BEE are somewhat more toxic to birds than triclopyr acid. The toxicities of 

these compounds to mammals show no remarkable differences. Triclopyr can be acutely lethal 

only at very high doses. However, indications of adverse effects to the kidney can occur at very 

low doses, at least in dogs. These adverse effects are indicated by increases in blood urea nitrogen 

and creatinine in dogs, but no histopathological changes to the kidneys were found. Triclopyr 

exposures exceed the toxicity indices for eight scenarios at the typical application rate, and 12 

scenarios at the highest application rate. 

2,4-D also has a relatively low acute toxicity to mammals in terms of direct lethal doses, but signs 

of adverse effects to the nervous system or internal organs may occur at very low doses. 2,4-D 

shows a consistent pattern of increased toxicity to larger sized animals. Birds appear somewhat 

less sensitive than mammals to acute toxic effects. The toxicity indices for 2,4-D in the risk 

assessment (SERA, 1998) are inconsistent with the most sensitive effects reported for mammals 

(SERA, 1998, p. 3-52). Relying on the most sensitive effects reported, 2,4-D use may produce 

exposures that can have adverse effects to terrestrial wildlife in 15 scenarios at the typical 

application rate, and 16 scenarios at the highest application rate. 

Glyphosate, applied at the typical application rate has little potential to adversely affect birds or 

mammals. An exception might be insectivorous birds that experience chronic exposures. There 

are no data available on the persistence or degradation of glyphosate residue on insects, so the 

acute dose is compared to the chronic toxicity index. This is an extremely protective approach 

and may greatly overestimate risk. However, it is worth noting so that appropriate protective 

measures may be taken when using glyphosate in the habitat of insectivorous birds. At the highest 

application rate, glyphosate has the potential to adversely affect large grass-eating mammals, and 

insectivorous birds and mammals in acute and chronic exposures. Additionally, grass-eating birds 

may be adversely affected in a chronic exposure. In total, glyphosate exposures exceed the 

toxicity indices for one scenario at the typical application rate, and eight exposures at the highest 

application rate. 

Clopyralid, applied at the typical application rate has little potential to adversely affect birds or 

mammals, except for insectivorous birds and mammals. There are no data available on the 

persistence or degradation of clopyralid residue on insects, so the acute dose is compared to the 

chronic toxicity index. This is an extremely protective approach and may greatly overestimate 

risk. However, it is worth noting so that appropriate protective measures may be taken when 

using clopyralid in the habitat of insectivorous birds and mammals. At the highest application 

rate, clopyralid may adversely affect grass-eating birds, insectivorous birds and mammals and 

predatory birds eating small mammal prey for chronic exposures. 

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Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

 C-34 

The same qualification for chronic exposure to insectivorous animals applies to predatory birds, 

in that the acute dose is compared to the chronic toxicity index. No acute exposures exceed the 

toxicity indices. In total, clopyralid exposures exceed the toxicity indices for one exposure at the 

typical application rate, and four at the highest application rate. 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

Table 5. Exposure scenario results from FS/SERA risk assessments for mammals, birds, and 

honeybees using the typical application rate 

The actual likelihood of exposing specific bird or mammal species depends on the application method, size of treatment 

area, habitat treated, and season of application, and must be analyzed at the site-specific levelTable 5. Exposure scenario 

results from FS/SERA risk assessments for mammals, birds, and honeybees using the typical application rate and upper 

residue rates. 

Symbol meanings are as follows: 

-- Exposure scenario results in a dose below the toxicity index. 

 Exposure scenario results in a dose that exceeds the toxicity index. 

Animal/ 

Scenario 

Chlorsulfuro

n 

Clopyralid 

Dicamba 

Glyphosate 

Imazapic 

Imazapyr 

Metsulfuron 

methyl 

Picloram 

Sethoxydim 

Sulfometuro

n methyl 

Tirclopyr 

2,4-D 

NPE 

Surfactant 

ACUTE EXPOSURES 

Direct 

spray, bee 

-- -- -- -- -- -- -- -- -- -- --  

Direct 

spray, sm. 

mammal 

-- -- --* -- -- -- -- -- -- -- --   

Consume contaminated vegetation 

small 

mammal 

-- -- -- -- -- -- -- -- -- -- --  -- 

large 

mammal 

-- --  -- -- -- -- -- -- -- --   

large bird -- --  -- -- -- -- -- -- --    

Consume contam. water 

Spill, sm. 

mammal 

-- -- -- -- -- -- -- -- -- -- --  -- 

Consume contam. insects 

small 

mammal 

-- -- -- -- -- -- -- -- -- -- --   

small bird -- --  -- -- -- -- -- -- --    

Consume contam. prey 

carnivore 

(sm. 

mammal) 

-- -- -- -- -- -- -- -- -- -- --  -- 

predatory 

bird (sm. 

mammal) 

-- -- -- -- -- -- -- -- -- -- -- -- -- 

predatory 

bird (fish) 

-- -- -- -- -- -- -- -- -- -- -- -- -- 

CHRONIC EXPOSURES 

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Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

 C-36 

Consume contam. veg. 

small mammal, on site -- -- -- -- -- -- -- -- -- -- --  -- 

lg. mammal, on site -- -- -- -- -- -- -- -- -- --   -- 

lg. bird, on site -- -- -- -- -- -- -- -- -- --   

Consume contam. water 

small mammal -- -- -- -- -- -- -- -- -- -- -- -- -- 

Consume contam. insects# 

small mammal --   -- -- -- --       

small bird --    -- -- --       

Consume contam. prey 

carnivore (sm. 

mammal)# 

-- -- -- -- -- -- -- -- -- --   -- 

predatory bird (sm. 

mammal)# 

-- -- -- -- -- -- -- -- -- -- --  -- 

predatory bird (fish) -- -- -- -- -- -- -- -- -- -- -- -- -- 

*Includes scenario for direct spray of a rabbit-sized mammal. 

# Data is lacking regarding chronic exposures, so effects are assumed by comparing acute dose vs. chronic 

NOAEL, which will likely over-estimate actual risk. 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Table 6. Exposure scenario results from FS/SERA risk assessments for mammals, birds, and honeybees using the highest applicat

Symbol meanings are as follows: 

-- Exposure scenario results in a dose below the toxicity index. 

♦ Exposure scenario results in a dose that exceeds the toxicity index. 

Animal/Scenario Chlorsulfuron Clopyralid Dicamba Glyphosate Imazapic Imazapyr Metsulfuron methyl Picloram Sethoxydim Su

ACUTE EXPOSURES 

Direct spray, bee -- -- -- ♦ -- -- -- -- 

Direct spray, sm. mammal -- -- ♦* -- -- -- -- 

-- 

-- 

Consume contaminated vegetation 

small mammal -- -- -- -- -- -- -- -- -- 

large mammal -- -- ♦ ♦ -- -- -- -- -- 

large bird -- -- ♦ -- -- -- -- -- -- 

Consume contam. water 

Spill, sm. mammal -- -- -- -- -- -- -- -- -- 

Consume contam. insects 

small mammal -- -- ♦ ♦ -- -- -- ♦ -- 

small bird -- -- ♦ ♦ -- -- -- -- -- 

Consume contam. prey 

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Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 

 C-38 

Table 6. Exposure scenario results from FS/SERA risk assessments for mammals, birds, and honeybees using the highest applicat

Symbol meanings are as follows: 

-- Exposure scenario results in a dose below the toxicity index. 

♦ Exposure scenario results in a dose that exceeds the toxicity index. 

Animal/Scenario Chlorsulfuron Clopyralid Dicamba Glyphosate Imazapic Imazapyr Metsulfuron methyl Picloram Sethoxydim Su

carnivore (sm. mammal) 

-- -- -- -- -- -- -- -- -- 

predatory bird (sm. 

mammal) 

-- -- -- -- -- -- -- -- -- 

predatory bird (fish) 

-- -- -- -- -- -- -- -- -- 

CHRONIC EXPOSURES 

Consume contam. veg. 

small mammal, on site -- -- -- -- -- -- -- -- -- 

lg. mammal, on site -- -- ♦ -- -- -- -- -- -- 

lg. bird, on site -- ♦ ♦ ♦ -- -- -- -- ♦ 

Consume contam. water 

small mammal -- -- -- -- -- -- -- -- -- 

Consume contam. 

insects# 

small mammal -- ♦ ♦ ♦ -- -- -- ♦ ♦ 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

C-39

Table 6. Exposure scenario results from FS/SERA risk assessments for mammals, birds, and honeybees using the highest applicat

Symbol meanings are as follows: 

-- Exposure scenario results in a dose below the toxicity index. 

♦ Exposure scenario results in a dose that exceeds the toxicity index. 

Animal/Scenario Chlorsulfuron Clopyralid Dicamba Glyphosate Imazapic Imazapyr Metsulfuron methyl Picloram Sethoxydim Su

small bird -- ♦ ♦ ♦ -- -- -- ♦ ♦ 

Consume contam. prey 

carnivore (sm. mammal)# -- -- -- -- -- -- -- -- -- 

predatory bird (sm. 

mammal)# 

-- -- -- -- -- -- -- -- ♦ 

* Includes scenario for direct spray of a rabbit-sized mammal. # Data is lacking regarding chronic exposures, so effects are assumed by comparing acute dose vs. chronic NOAEL, which will likely over-estimate actual risk. 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

Herbicide Effects on Reptiles 

There is almost no data available regarding the toxicity of herbicides to reptiles. In a review of 

pesticide effects to reptiles, Pauli and Money (2000) found very few studies, despite publications 

stating the need for such research dating back to Hall (1980). The only information available for 

herbicides included in this EIS is from two reports concerning 2,4-D. One study investigated the 

effects of 2,4-D on alligators (Crain et al. 1997, as cited by SERA 1998), and Willemsen and 

Hailey (1989, cited by Pauli and Money 2000) noted adverse effects to tortoises in Greece after 

application of 2,4,5-T and 2,4-D. Pauli and Money (2000) concluded, “it is remarkable that no 

data appear to exist concerning the effects on reptiles of field applications of... modern herbicides 

(e.g., glyphosate, sulfonylureas)...” 

Hall and Henry (1992) stated, “Susceptibility of reptiles to selective pesticides is virtually 

unknown.” 

Hall and Clark (1982) found that the green anole lizard (Anolis carolinenesis) had a similar 

sensitivity as mallards and rats to organophosphates. Conversely, reptiles were reported to be 

more sensitive to some pesticides than birds or mammals (Rudd and Genelly 1956, as cited in 

Hall 1980). Hall (1980) stated that reptiles are apparently less sensitive than fish. The FS/SERA 

risk assessments use amphibians and/or fish as surrogates for reptiles. An assumption is made that 

exposures and doses that are protective of amphibians and fish would also be protective of 

reptiles. Amphibians and fish have very permeable skin, more so than reptiles, so they are more 

likely to absorb contaminants from their environment. And their complicated life cycle that 

includes metamorphosis makes amphibians sensitive indicators for environmental effects 

(Cowman and Mazanti, 2000). However, the lack of data from reptiles leads to substantial 

uncertainty in the risk assessment for reptiles, since the response of these animals to doses of 

herbicide is not known. 

Many reptile species would likely be under some cover during the day, when herbicides may be 

applied. But diurnal reptiles, like lizards, could conceivably be sprayed during applications. 

Nocturnal and diurnal reptiles could be exposed through contact with contaminated vegetation 

and soil or ingestion of contaminated prey. Contaminated water or prey could expose aquatic 

reptiles, but direct spray is not likely. The actual likelihood of exposing reptiles depends on the 

application method, size of treatment area, habitat treated, and season of application, and must be 

analyzed at the site-specific level. 

Herbicide Effects on Amphibians 

Data on toxicity of herbicides to amphibians are limited. 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; Johnson 1976; Mayer and Ellersieck 1986; Perkins et al. 2000). Consequently, 

separate dose-response assessments from exposure scenarios have not been created for 

amphibians in the FS/SERA risk assessments. Available information on toxicity of herbicides to 

amphibians is summarized below. 

Neither the published literature nor the EPA files include data regarding the toxicity of 

chlorsulfuron, clopyralid, imazapic, imazapyr, metsulfuron methyl, picloram, or sethoxydim to 

amphibian species. However, data for other aquatic species indicate that chlorsufuron, clopyralid, 

imazapic, imazapyr, metsulfuron methyl, and picloram have a very low potential to cause any 

adverse effect in aquatic animals (SERA 2003 Chlorsulfuron; SERA, 2003-Clopyralid; SERA, 

2003-Imazapic; SERA, 2003-Imazapyr; SERA, 2003-Metsulfuron methyl; SERA, 2003-

Picloram). The formulation Poast is much more toxic to aquatic organisms than sethoxydim. 

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Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

However, even considering the higher toxicity of Poast, there is no indication that aquatic animals 

are likely to be exposed to concentrations that would result in toxic effects. There is a substantial 

limitation to this risk characterization in that no chronic toxicity studies on aquatic animals are 

available for either sethoxydim or Poast (SERA, 2001 Sethoxydim). 

Glyphosate 

Glyphosate isopropylamine (IPA), RoundUp and POEA surfactant used in RoundUp have been 

specifically tested for ability to cause malformations in the frog embryo teratogenesis assay using 

Xenopus (Perkins et al. 2000). Xenopus is a highly sensitive assay species for determining the 

teratogenicity of chemicals (Mann and Bidwell 2000, Perkins et al. 2000). No increases in 

malformations were noted at levels that were not also lethal to the embryos. The RoundUp 

formulation containing POEA surfactant was 700 times mores toxic than glyphosate IPA. POEA 

surfactant alone was more toxic than the RoundUp formulation. No statistically significant 

increases in abnormalities were seen in any groups exposed to POEA at levels that were not also 

lethal. The 96-hour LC

50 for glyphosate IPA was 7297 mg a.e./L, and that for RoundUp was 9.3 

mg a.e./L. Perkins et al. (2000) calculated that if RoundUp was applied at the highest application 

rate directly to water 15 cm deep (volumn not specified), the expected environmental 

contamination was less than the LC

50 

and the LC

5 

by a factor of about three. 

A study by Smith (2001) looked at effects to western chorus frog (Pseudacris tiseriata) and Plains 

leopard frog (Rana blairi) from a formulation of glyphosate that contains glyphosate IPA and 

ethoxylated tallowamine surfactant (Kleeraway Grass and Weed Killer RTU (Monsanto)). Smith 

exposed 1-week old tadpoles for 24-hours to the following concentrations of Kleeraway: 0.1 (1 

part Kleeraway to 9 parts deionized water), 0.1, 0.001, and 0.0001. These concentrations are 

equivalent to 560 mg a.e./L, 56 mg a.e./L, 5.6 mg a.e./L, and 0.56 mg a.e./L (SERA, 2003-

Glyphosate, p. 4-20). Smith reported some mortality at concentrations as low as 0.56 mg a.e./L 

for both species. Acute exposure to Kleeraway had no effect on growth or development of 

surviving tadpoles. Results found by Smith are not consistent with other information on the 

effects of glyphosate or other formulations to amphibians. However, other studies have found that 

different formulations can have different toxicities to frogs (Mann and Bidwell, 1999). 

Formulations containing surfactant are known to have much higher toxicity to amphibians than 

glyphosate. The Forest Service does not use the formulation used in the Smith study. 

Bidwell and Gorrie (1995; cited in SERA 2003 Glyphosate) reported 48-hour LC50 

values of 11.6 

mg a.e./L for the Roundup 360 formulation and 121 mg/L for technical grade glyphosate using 

four species of frogs from western Australia. 

At the typical application rate, expected water concentrations for acute and longer-term exposures 

are well below any reported LC50 for amphibians, with the exception of the study by Smith (2001) 

(SERA, 2003-Glyphosate, Worksheet G03). At the highest application rate, lethal doses could 

occur from formulations containing surfactant. 

Sulfometuron methyl 

The effect of sulfometuron methyl to amphibians was investigated in one study using Xenopus 

(Fort 1998; cited in SERA 2003 Sulfometuron methyl). Results of the study found that 

sulfometuron methyl exposure can cause moderately severe malformations in these frogs, 

including miscoiling of the gut, incomplete eye lens formation, abnormal craniofacial 

development, and decreased tail resorption. The concentration that produced these effects 

depended upon the length of exposure, with shorter exposures showing no effect at higher 

concentrations than longer exposures. The author did not sate whether data were reported in terms 

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Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

of mg of sulfometuron methyl or mg of Oust. The FS/SERA risk assessment assumes that data 

refer to mg of Oust, to provide the most protection. The NOAEC for malformations for 4-hour 

exposure is 0.38 mg a.i./L, and that for 30-day exposure is 0.0075. However, exposure to 0.0075 

mg a.i./L for 14 days was identified as the LOAEC for tail resorption rate effects. No mortality 

was observed at concentrations up to 7.5 mg a.i./L. 

Unlike the other FS/SERA risk assessments, a quantitative evaluation of exposure and risk from 

sulfometuron methyl was conducted for amphibians. SERA (2003 Sulfometuron methyl) 

compared estimated water concentrations for acute and chronic exposures to acute and chronic 

NOEC values for frogs, from Fort (1998). The estimated exposure is 0.002 of the acute NOEC, 

and 0.00075 of the chronic NOEC. Therefore, at the typical and highest application rates, there is 

no basis for asserting or predicting that adverse effects to amphibians are plausible. There is a 

substantial reservation in that this conclusion is based on data from one species, but other studies 

have indicated that Xenopus are a sensitive indicator for effects to amphibians (Mann and 

Bidwell 2000, Perkins et al. 2000). 

Triclopyr 

Triclopyr BEE is much more toxic to aquatic species that triclopyr TEA or triclopyr acid (SERA 

2003 Triclopyr). Triclopyr was specifically tested for ability to cause malformations in the frog 

embryo teratogenesis assay using Xenopus laevis (Perkins et al. 2000). Xenopus is a highly 

sensitive assay species for determining the teratogenicity of chemicals (Mann and Bidwell 2000, 

Perkins et al. 2000). No statistically significant increase in abnormalities were seen in any groups 

exposed to Garlon 3A or Garlon 4 at levels that were not also lethal to the embryos. Consistent 

with results for other aquatic species, Garlon 3A, containing triclopyr TEA, was 15 times less 

toxic than Garlon 4, containing triclopyr BEE. Garlon 4 reduced embryo growth at a 

concentration below the LC

50. Perkins et al. (2000) found that the 96-hour LC50 

for Garlon 4 was 

10 mg a.e./L, and that for Garlon 3A was 159 mg a.e./L. Perkins et al. (2000) calculated that if 

Garlon 4 was applied at the highest application rate directly to water 15 cm deep (volume not 

specified), the expected environmental contamination was less than the LC

50 

and the LC

5 

by a 

factor of about four and three, respectively. 30 

Berrill et al. (1994) conducted toxicity studies on eggs and tadpoles of leopard frog (Rana 

pepiens), green frog (Rana clamitans), and bullfrog (Rana catesbeiana) exposed to technical grade 

triclopyr BEE. The study was conducted in darkness to prevent hydrolysis of triclopyr BEE to 

tricolopyr acid. Exposure of eggs to concentrations up to 4.6 ppm triclopyr a.e. for 48 hours 

caused no effect on hatching success, timing, malformations or subsequent avoidance behavior of 

tadpoles hatched from exposed eggs (Berrill et al. 1994). Tadpoles were more sensitive; all 

bullfrog and green frog tadpoles exposed to 2.3 and 4.6 ppm triclopyr a.e. died. Leopard frogs 

were more tolerant and few died, but all were unresponsive to prodding at 2.3 and 4.6 ppm a.e. 

About half the bullfrog and most green frog tadpoles became unresponsive to prodding when 

exposed to 1.1 ppm a.e. Surviving tadpoles recovered after exposure was terminated. 

Water concentrations from application of triclopyr acid at the typical application rate are below 1 

mg/L (1 ppm), so acute and chronic risks to aquatic animals are low (SERA, 2003-Triclopyr, 

Worksheet G03). At the highest application rate, acute exposure from runoff could adversely 

affect responsiveness of some tadpoles, increasing the risk of predation. Despite the difference in 

toxicity, the conclusion is the same for triclopyr BEE, due to the difference in estimated water 

concentration. 

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Appendix C-Wildlife 

Herbicide Effects on Invertebrates 

Manufacturers are required to conduct toxicity tests on honeybees as part of the registration 

process. The estimated doses and toxicity values of the herbicides to honey bees are listed in 

Table 7. The inclusion of other terrestrial invertebrates in toxicity studies varies for each 

herbicide. However, even the most well-studied will include effects on only a small fraction of 

terrestrial invertebrate species potentially found in any diverse ecosystem. Risk to invertebrates 

can only be inferred based on the few test species for which data are available. 

Effects of chlorsulfuron to terrestrial invertebrates have been studied using a leaf beetle 

(Gastrophysa polygoni), large whitebutterfly (Pieris brassicae), and nemotodes (SERA, 2003-

Chlorsulfuron). Direct spray of first-instar larva and feeding of larva on treated plants did not 

produce significant changes in mortality, but did delay development of those feeding on treated 

plants. Placing eggs of the leaf beetle on treated plants significantly decreased survival (Kjaer and 

Elmegaard, 1996; cited in SERA, 2003-Chlorsulfuron). In another study (Kjaer and Heimbach, 

2001), newly hatched larvae of the leaf beetle and whitebutterfly were placed on treated plants 

and no significant effects on survival or relative growth rates were found. Two species of 

nematodes (Steinernema carpocapsae and S. feltiae) were exposed to chlorsulfuron in soil and no 

effect was observed on reproduction, viability or movement (Rovesti and Desco, 1990; cited in 

SERA 2003-Chlorsulfuron). A British publication (Tomlin, 2000) reports an LD50 > 25mg/kg for 

honey bees, but it is not clear what research provides the basis for this value. 

Clopyralid has been tested on a variety of terrestrial invertebrates. Standard bioassays on 

honeybees (LD50 >90 mg/kg) have been conducted as well as exposure of earthworms to 

clopyralid in soil (LC50 >1000 ppm). Also, Hassan et al. (1994) provided a summary of several 

bioassays and field trials using a variety of terrestrial invertebrates. Clopyralid produced some 

mortality in insect parasites, predatory mites, Semiadalia 11-notata (Coccinellidae), Anthocoris 

nemoralis (Anthocoridae), and Chrysoperla carnea (Chrysopidae). Pekar et al. (2002; cited in 

SERA 2003 Clopyralid) reported that clopyralid was “harmless” to wild immature spiders 

(Theridion impressum). 

Table 7. Potential herbicide doses for bees in a direct spray scenario, assuming 100% absorption. 

Herbicide Typical Application Rate Dose for Bee Toxicity Index for Bee 

Chlorsulfuon 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) 

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) 

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Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

 C-44 

Table 7. Potential herbicide doses for bees in a direct spray scenario, assuming 100% absorption. 

Herbicide Typical Application Rate Dose for Bee Toxicity Index for Bee 

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) 

NP9E 1.67 lbs/ac 268.00 mg/kg unknown 

Source: SERA 1996-2003 and USDA FS 2003. 

1 Standard acute toxicity studies using bees were not identified in a complete search of studies 

submitted to EPA. Tomlin (2000) reports bee LD50 > 25 mg/kg in a British pesticide manual. 

Another study found no mortality to a leaf-eating beetle directly sprayed at a rate corresponding 

to 107 lb/ac (SERA 2003 Chlorsulfuron). 

There is a low potential for glyphosate to adversely affect terrestrial invertebrates. The honeybee 

LD

50 for glyphosate is greater than 1075 mg/kg and the NOEC is 540 mg/kg. Mortality at 134 

mg/kg in one study was attributed to equipment failure (SERA, 2003-Glyphosate). Direct foliar 

spray had no effect on the spider mite (Tetranchys urticae). One-hundred percent mortality to 

spider mites was reported after application of RoundUp ULTRA at 3.6 kg a.i./ha, but it was 

attributed to the solution causing the mites to stick to the glass plates. Studies of the effects of 

glyphosate on the spider Lepthyphantes tenuis resulted in no effects that could be attributed to 

glyphosate toxicity. No significant effects were noted in studies on rove beetles, butterflies, or 

terrestrial snail (Helix aspersa). The soil LC50 for a worm common in Libya, Aporrectodea 

caliginosa, is 177-246 mg glyphosate/kg soil (Mohamed et al., 1995; cited in SERA, 2003-

Glyphosate). 

The standard acute toxicity study to honeybees is the only study found on the effects of imazapic 

to terrestrial invertebrates. At 387 mg/kg, mortality was not statistically significant (SERA, 2003-

Imazapic). 

Imazapyr has a low acute toxicity to bees with an LD50 >1000 mg/kg. No information on effects 

to other terrestrial invertebrates is available. 

Standard bioassays on effects of metsulfuron methyl to honeybees reported LD50 > 1075 mg/kg 

and a NOAEL of at least 270 mg/kg. Very high application rates (almost five times higher than 

the highest labeled application rate) resulted in a 15 percent reduction in eff hatching for rove 

beetle (Samsoe-Petersen 1995; cited in SERA 2003 Metsulfuron methyl). 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

Data on the toxicity of picloram to terrestrial invertebrates is available only for the honeybee and 

the brown garden snail (Helix aspersa). The honeybee LD50 is greater than 1000 mg/kg and 

dietary concentration of 5000 mg/kg over a 14-day period did not increase mortality for the snail. 

For sethoxydim, the honeybee NOAEL is 107 mg/kg. The only other study on invertebrates 

investigated effects to Mexican bean beetle (Epilachna varivestis) feeding on soybean and lima 

bean plants treated with the equivalent of 5-6 lbs/acre (15 times higher than the highest labeled 

application rate). There was a slight increase in days to pupation for larvae, but also significant 

increases in both the number of egg masses as well as total number of eggs produced by beetles 

feeding on sethoxydim treated plants (Agnello et al. 1986; cited in SERA 2001 Sethoxydim). 

Only two studies are available on the toxicity of sulfometuron methyl to terrestrial invertebrates 

and they both looked at effects to the honeybee. Sulfometuron methyl has a very low potential to 

adversely affect bees, with an acute NOAEL of 1075 mg/kg (SERA, 2001-Sulfometuron methyl). 

No mortality was reported at the highest doses tested. 

Honeybee assays provide the only information on the effects of triclopyr acid and triclopyr TEA 

to terrestrial invertebrates. In both bioassays, the LD50 is greater than 1075 mg/kg (SERA, 2003-

Triclopyr). 33 

The actual likelihood of exposing invertebrates depends on the application method, size of 

treatment area, habitat treated, and season of application, and must be analyzed at the site-specific 

level. 

Likelihood these exposures and effects will actually occur 

While the above exposure scenarios consider animal sizes, feeding habits, herbicide application 

rates, and toxicity data, they cannot account for all the variables found in the field during actual 

applications. Such factors as foliar interception, animal behavior (e.g. nocturnal versus diurnal 

activity), season of use, and selective application methods can significantly reduce or eliminate 

actual exposure to herbicides in field conditions. For example, while toxicity of some herbicides 

could pose a concern for the early stages of amphibian development, an actual application of 

herbicide occurring after mid-summer, well after this stage of development might be present at a 

specific location, could significantly reduce risk (Perkins et al., 2000). 

Direct spray of small mammals is very unlikely to occur, since they are typically nocturnal and 

spend the day in burrows, nests, or underneath dense vegetation. Diurnal small mammals, like 

ground squirrels, may be active in treatment areas, but would likely seek shelter or move away 

from the treatment activity. Aerial application could directly spray some diurnal small mammals. 

The likelihood that a predatory bird or mammal would prey on the same small mammal that had 

been directly sprayed is remote, and an entire day’s diet of contaminated small mammals is very 

remote. 34 

Direct spray of insects could occur, as they are present in vegetation and would not necessarily 

flee during treatment operations. However, foliar interception would reduce the actual amount 

sprayed on almost all insects present. Insectivorous birds may establish territories during the 

breeding season. If the treatment area involved most of one or several territories, it could be 

feasible for an insectivorous bird to consume all or most of its daily diet within the treatment area. 

The young of even herbivorous bird species are highly dependant upon insects for their growth 

and development. Therefore, while the actual doses received by insectivorous birds may be lower 

than the exposure scenarios predict, due to foliar interception, application method and other 

variables, the consumption of contaminated insects by young birds may offset this advantage. 

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Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

Consumption of contaminated insects remains a concern for some herbicides, and likelihood of 

exposure must be evaluated at the site-specific level. Insectivorous mammals may be less likely 

to consume a large amount of contaminated invertebrates, because they either forage over very 

large areas, like bats, or may forage on fossorial invertebrates, like shrews. 

Consumption of contaminated grass by large birds or mammals would depend on the habitat-type 

in the treatment area and whether these animals are likely to forage there. The application method 

would be very important in determining the amount of exposure. Selective foliar applications to 

target invasive plants are not likely to lead to exposure. But broadcast foliar applications of large 

areas, particularly aerial applications, could contaminate forage. Consumption of contaminated 

vegetation is a substantial concern for some herbicides, but the specific application methods and 

timing may easily avoid exposure to these animals. 

In order to evaluate how actual implementation can influence effects to wildlife, field studies for 

many of the above herbicides have been conducted. 

Field Studies 

Field studies can help evaluate the likelihood of population effects to wildlife from herbicides as 

applied. Some herbicides have been tested in many field studies on several groups of species with 

results published in open literature, while other herbicides have few or no field studies reported. 

Most field studies could only detect changes in population numbers and are not sensitive enough 

to detect sublethal effects to wildlife. Some studies have investigated sub-lethal effects (e.g. 

Sullivan et al., 1998). However, sublethal effects that resulted in indirect mortality or other 

population changes would produce effects that could be detected by most longer-term field 

studies. 

Chlorsulfuron 

No field studies are available. 

Clopyralid 

Rice et al. (1997) published results from an 8-year field study that found no significant effects on 

plant species diversity from the use of clopyralid, clopyralid plus 2,4-D, or picloram. Hassan et al. 

(1994) reported summary of effects to terrestrial invertebrates in field trials. 

Glyphosate 

Sullivan et al. (1998) looked at long-term influence of glyphosate treatment in a spruce forest on 

reproduction, survival, and growth attributes of deer mouse (Peromyscus maniculatus) and 

southern red-backed vole (Clethrionomys gapperi) populations. For all statistically significant 

differences in their study (e.g. successful pregnancies, survival), the differences between treated 

and untreated populations were within the range of natural fluctuations for these small mammal 

populations over a 5-year period. 

Sullivan et al. (1997) investigated the influence of aerial herbicide treatments on small mammal 

populations 9 and 11 years post-treatment. They found that glyphosate did not adversely affect 

reproduction, survival, or growth of deer mice or Oregon voles (Microtus oregoni) in coastal 

forest a decade after application. Species richness and diversity changed little over the decade 

after treatment and concluded that post-harvest successional change had more impact than that 

induced by herbicide treatment. 

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Appendix C-Wildlife 

A field study on effects to the spider Lepthyphantes tenuis attributed population decrease to the 

secondary effects from changes in vegetation (Haughton et al., 2001; cited in SERA, 2003-

Glyphosate). Bramble et al. (1997) investigated butterfly diversity and abundance on electric 

transmission right-of-ways treated with herbicides versus those treated with only mechanical 

methods. Herbicides used in the right-of-way treatments included a mixture of picloram and 

triclopyr, a mixture of triclopyr and metsulfuron methyl, a mixture of glyphosate and fosamine, a 

mixture of triclopyr and imazapyr, and glyphosate alone. They found no significant differences in 

diversity or abundance of butterflies between herbicide and no-herbicide units. 

Cole et al. (1998) found that small mammal capture rates in Oregon forests that were logged, 

burned and then sprayed with glyphosate did not differ from those that were just logged and 

burned. Other studies have found that numbers of some species appear to increase or remain the 

same after treatment with herbicides, while other species decrease (Anthony and Morrison 1985; 

Lautenschlager, 1993; Ritchie et al., 1987; Sullivan, 1990a). The same species might show all 

three responses in different studies with the same herbicide (see Sullivan, 1990a). In these 

studies, effects to small mammals occurred from habitat changes created by herbicide treatment, 

rather than from direct effects of herbicides (Santillo et al., 1989; Sullivan 1990a; Sullivan 1990b; 

Sullivan and Sullivan, 1981). 

Santillo et al. (1989) found a substantial decrease in herbivorous insects on glyphosate treated 

sites, while there was clearcut verses untreated, but no trend between treated and untreated sites 

for predatory insects. The overall decrease in insect numbers decreased available food for shrews. 

Cole et al. (1997) sampled amphibians in Oregon clearcuts with and without glyphosate 

applications. Capture rates did not differ between treated and untreated plots for rough-skinned 

newt, ensatina, Pacific giant salamander, Dunn’s salamander, western redback salamander, and 

red-legged frog. 

Imazapic, Sethoxydim, Sulfometuron methyl 

No field studies available. 

Imazapyr 

Imazapyr was used on a low volume retreatment in the Bramble et al. (1997) study mentioned 

above (see glyphosate) without apparent adverse effects to butterfly diversity and abundance on 

electric transmission right-of-ways. 

Metsulfuron methyl 

Metsulfuron methyl was in one of the mixtures used to treat electric transmission right-of-ways in 

the Bramble et al. (1997) study mentioned above (see glyphosate), which found no apparent 

adverse effects to butterfly diversity and abundance. 

Picloram 

Rice et al. (1997) published results from an 8-year field study that found no significant effects on 

plant species diversity from the use of clopyralid, clopyralid plus 2,4-D, or picloram. Brooks et al. 

1995 studied effects of picloram, imazapyr, and triclopyr mixtures on small mammals and found 

reduced numbers on sites after herbicide treatments. However, no control site (i.e. non-treated) 

was used so it is not possible to discern herbicide effects from normal population fluctuations that 

are common with small mammals. Nolte and Fulbright (1997) studied effects of an aerial 

application of picloram/triclopyr mixture on small mammals, birds, and rare plants. Effects to 

animal diversity or plant species richness or evenness were not found. 

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Appendix C-Wildlife 

Picloram was in some of the mixtures used to treat electric transmission right-of-ways in studies 

by Bramble et al. (1997, 1999). The 1997 study found no significant differences to butterfly 

diversity and abundance, while the 1999 study found significantly higher diversity and abundance 

of butterflies on herbicide-treated units than on handcutting units. 

Triclopyr 

There are a number of field studies reported in the open literature, most of which indicate no or 

beneficial effects (SERA 2003 Triclopyr). Refer also to the study by Brooks et al. (1995) 

mentioned above. In contrast, Leslie et al. 1996 found that white-tailed deer avoid areas that used 

a “brown and burn” technique, where the site is treated with herbicide followed by a prescribed 

burn. McMurray et al. (1993a; 1993b; 1994) reported no adverse effects to reproductivity in 

mammals. 

Triclopyr was in some of the mixtures used to treat electric transmission right-of-ways in studies 

by Bramble et al. (1997, 1999). The 1997 study found no significant differences to butterfly 

diversity and abundance, while the 1999 study found significantly higher diversity and abundance 

of butterflies on herbicide-treated units than on handcutting units. 

Results of Exposure Analysis for Each Herbicide 

Calculated doses for each herbicide at typical and highest application rates for each scenario are 

included in Appendix 1. 

CHLORSULFURON 

Small Mammal Directly Sprayed 

The acute NOAEL for mammals in laboratory toxicity tests is 75 mg/kg. For exposure scenarios 

that use the typical application rate of 0.056 lb/acre, if a small mammal is directly sprayed, and 

100 percent absorption is assumed, the animal would receive an acute dose of 1.36 mg/kg (SERA, 

2003-Chlorsulfuron, Worksheet F02a). This dose is 0.018 of the acute NOAEL, so there is no 

basis for asserting or predicting that adverse effects to small herbivorous mammals are plausible 

(SERA 2003 Chlorsulfuron, p. 4-27). 

At the highest application rate of 0.25 lb/acre, the animal would receive an acute dose of 6.06 

mg/kg (project file). This dose is 0.08 of the acute NOAEL, so there is no basis for asserting or 

predicting that adverse effects to mammals are plausible at any application rate. 

Small Mammal Drinking Contaminated Water 

The acute NOAEL for mammals in laboratory toxicity tests is 75 mg/kg. The estimated dose to a 

small mammal from drinking water contaminated by an accidental spill, assuming the highest 

levels of contamination, is 0.11 mg/kg for acute exposure (SERA, 2003-Chlorsulfuron, 

Worksheet F05). If a small mammal consumes contaminated water over time, accounting for 

dissipation, degradation, and other processes, the animal would receive a chronic dose of 

0.0000074 mg/kg/day (SERA, 2003-Chlorsulfuron, Worksheet F07). Doses to a large mammal 

would be even lower on a per kg body weight basis. These doses are 0.0015 of the acute NOAEL, 

and 0.000001 of the chronic NOAEL, respectively, so there is no basis for asserting or predicting 

that adverse effects to mammals are plausible (SERA, 2003-Chlorsulfuron, p. 4-27). 

At the highest application rate of 0.25 lb/acre, the acute dose from drinking water contaminated 

by a spill is 0.495 mg/kg (project file). This dose is 0.007 of the acute NOAEL. The chronic dose 

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Appendix C-Wildlife 

is also below the chronic NOAEL, so there is no basis for asserting or predicting that adverse 

effects to mammals are plausible, even in a worst-case scenario. 

Large Herbivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 75 mg/kg. For exposure scenarios 

that use the typical application rate of 0.056 lb/acre, if a 70 kg mammal consumed contaminated 

vegetation on site shortly after application, assuming the highest residue rates and 100 percents of 

the diet contaminated, it would receive an acute dose of 2.72 mg/kg (SERA 2003 Chlorsulfuron, 

Worksheet F10). This dose is 0.036 of the acute NOAEL, so there is no basis for asserting or 

predicting that adverse effects to large herbivorous mammals are plausible (SERA, 2003-

Chlorsulfuron, p. 4-27). The chronic NOAEL for mammals in laboratory toxicity tests is 5 

mg/kg/day. Chronic exposure from the consumption of contaminated vegetation for 90 days at the 

treatment site, assuming the highest residue rates, results in a dose of 1.14 mg/kg (SERA, 2003-

Chlorsulfuron, Worksheet F11a). This dose is 0.228 of the chronic NOAEL, so there is no basis 

for asserting or predicting that adverse effects to large herbivorous mammals are plausible 

(SERA, 2003-Chlorsulfuron, p. 4-27). 

Estimated doses using the highest application rate (0.25 lb/acre) are less than the acute NOAEL 

and equal to the chronic NOAEL for mammals. No exposure exceeds the NOAEL, so no adverse 

effects are plausible from acute or chronic dietary exposures. The assumptions in the chronic 

exposure scenario are very unlikely to occur in field conditions, so the weight of evidence 

suggests that no adverse effects are plausible using typical or worst-case exposure assumptions 

(SERA, 2003-Chlorsulfuron, p. 4-28). 

Medium Carnivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 75 mg/kg. For exposure scenarios 

that use the typical application rate of 0.056 lb/acre, if a 5 kg mammal consumed small mammal 

prey that has been contaminated by direct spray, assuming 100 percent absorption for the prey, it 

would receive an acute dose of 0.118 mg/kg (SERA, 2003-Chlorsulfuron, Worksheet F16a). This 

dose is 0.0016 of the acute NOAEL, so there is no basis for asserting or predicting that adverse 

effects to carnivorous mammals are plausible (SERA, 2003-Chlorsulfuron, p. 4-27). Doses to 

larger mammals would be even lower on a per kg body weight basis. 

Chlorsulfuron does not appear to accumulate or persist in animals following either single or 

multiple doses. The elimination of chlorsulfuron has been studied in rats, goats, cows, and hens 

(SERA, 2003-Chlorsulfuron). A combination of elimination and metabolism extensively and 

rapidly eliminated chlorsulfuron and its metabolites from the bodies of all mammalian species 

studied. The half-life for elimination in rats is less than six hours (Shrivastava, 1979 cited in 

SERA, 2003-Chlorsulfuron). Therefore, chronic exposures from contaminated mammal prey due 

to a single application of chlorsulfuron are unlikely to cause any adverse effect. In addition, the 

acute dose is much less than the chronic NOAEL for mammals, so there is no basis for asserting 

or predicting that adverse effects from repeated acute exposures from multiple applications of 

chlorsulfuron over time are plausible. 

Estimated doses using the highest application rate (0.25 lb/acre) are less than the acute and 

chronic NOAELs for mammals, so there is no basis for asserting or predicting that adverse effects 

are plausible using typical or worst-case exposure assumptions (SERA, 2003-Chlorsulfuron, p. 4-

28). 

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Appendix C-Wildlife 

Small Herbivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 75 mg/kg. If a small mammal 

consumes contaminated vegetation shortly after application, assuming the highest residue rates, 

the acute dose received is 0.15 mg/kg (SERA, 2003-Chlorsulfuron, Worksheet F03). This 

estimated dose is 0.002 of the acute NOAEL, so there is no basis for asserting or predicting that 

adverse effects to small herbivorous mammals are plausible (SERA, 2003-Chlorsulfuron, p. 4-

27). 

The chronic NOAEL for mammals in laboratory toxicity tests is 5 mg/kg/day. If a small mammal 

consumes contaminated vegetation at the treatment site for 90-days, assuming the highest residue 

rates, the animal would receive a chronic dose of 0.013 mg/kg/day (SERA, 2003-Chlorsulfuron, 

Worksheet F04a). This dose is 0.0026 of the chronic NOAEL, so there is no basis for asserting or 

predicting that adverse effects to small herbivorous mammals are plausible (SERA, 2003-

Chlorsulfuron, p. 4-27). 

Estimated doses using the highest application rate (0.25 lb/acre) are less than the acute and 

chronic NOAELs for mammals, so there is no basis for asserting or predicting that adverse effects 

are plausible using typical or worst-case exposure assumptions (SERA 2003 Chlorsulfuron, p. 4-

28). 

Small Insectivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 75 mg/kg. For exposure scenarios 

that use the typical application rate of 0.056 lb/acre, if a small mammal consumes contaminated 

insects shortly after application, assuming the highest residue rates, the acute dose received is 

3.89 mg/kg (SERA, 2003-Chlorsulfuron, Worksheet 14a). This dose is 0.052 

of the acute NOAEL, so there is no basis for asserting or predicting that adverse effects to 

insectivorous mammals are plausible (SERA, 2003-Chlorsulfuron, p. 4-27). 

Data on degradation of herbicide residues from insects is not available, so no chronic exposure 

scenario has been developed. However, the acute dose is much less than the chronic NOAEL as 

well, and chronic doses are much lower than acute doses. Therefore, there is no basis for asserting 

or predicting that adverse effects to insectivorous mammals from chronic exposures are plausible 

(SERA, 2003-Chlorsulfuron, p. 4-27). 

The estimated dose (17.3 mg/kg) using the highest application rate (0.25 lb/acre) is less than the 

acute and chronic NOAELs for mammals, so there is no basis for asserting or predicting that 

adverse effects are plausible using typical or worst-case exposure assumptions (SERA, 2003-

Chlorsulfuron, p. 4-28). 

Large Herbivorous Bird 

The acute NOAEL for birds in laboratory toxicity tests is 1686 mg/kg. For exposure scenarios 

that use the typical application rate of 0.056 lb/acre, if a 4 kg bird consumed contaminated grass 

on site shortly after application, assuming the highest residue rates and 100 percent of diet is 

contaminated, it would receive an acute dose of 4.26 mg/kg (SERA, 2003-Chlorsulfuron, 

Worksheet F12). This dose is 0.0025 of the acute NOAEL, so there is no basis for asserting or 

predicting that adverse effects to large grass-eating birds are plausible (SERA, 2003-

Chlorsulfuron, p. 4-27). 

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Appendix C-Wildlife 

The chronic NOAEL for birds in laboratory toxicity tests is 140 mg/kg/day. Chronic exposure 

from the consumption of contaminated grass for 90 days at the treatment site, assuming the 

highest residue rates and 100 percent of diet is contaminated, results in a dose of 1.79 mg/kg/day 

(SERA, 2003-Chlorsulfuron, Worksheet F13a). This dose is 0.013 of the chronic NOAEL, so 

there is no basis for asserting or predicting that adverse effects to large grass-eating birds are 

plausible (SERA, 2003-Chlorsulfuron, p. 4-27). 

Estimated doses using the highest application rate (0.25 lb/acre) are less than the acute and 

chronic NOAELs for birds, so there is no basis for asserting or predicting that adverse effects are 

plausible using typical or worst-case exposure assumptions (SERA, 2003-Chlorsulfuron, p.4-28). 

Large Fish-eating Bird 

Many chemicals may be concentrated or partitioned from water into the tissues of animals in the 

water. This process is referred to as bioconcentration. The potential for bioconcentration of 

chlorsulfuron in fish was studied in bluegill and channel catfish exposed to 

14

C-chlorsulfuron for 

28 days (Han 1981 and Priester et al., 1991, cited in SERA, 2003 Chlorsulfuron). In the SERA 

risk assessments, concentrations in viscera are considered to reflect concentration in whole fish. 

Bioconcentration factors (BCF) for bluegill were <1 L/kg in muscle and 4-6 L/kg in viscera and 

liver (SERA, 2003-Chlorsulfuron, Appendix 9). BCF for channel catfish were 1.5 L/kg in muscle 

and < 12 L/kg in viscera and liver (SERA, 2003-Chlorsulfuron, Appendix 9). In both studies, 

residue levels in live fish dropped 70-90 percent during a two-week cleansing period. No adverse 

effects on fish were observed during the studies. The exposure scenarios in the SERA risk 

assessment use a whole-fish BCF of 2.6 L/kg for acute exposure and 12 L/kg for chronic 

exposure. 

The acute NOAEL for birds in laboratory toxicity tests is 1686 mg/kg. For exposure scenarios 

that use the typical application rate of 0.056 lb/acre, if a predatory bird consumed fish from a 

pond contaminated by an accidental spill, assuming the highest concentrations in fish and highest 

intake on a body weight basis, it would receive an acute dose of 0.295 mg/kg (SERA 2003 

Chlorsulfuron, Worksheet F08). This dose is 0.00017 of the acute NOAEL, so there is no basis for 

asserting or predicting that adverse effects to fish-eating birds are plausible (SERA 2003 

Chlorsulfuron, p. 4-27). 

The chronic NOAEL for birds in laboratory toxicity tests is 140 mg/kg/day. If a predatory bird 

consumed fish contaminated by runoff for a lifetime, assuming the highest concentrations in fish 

and highest intake on a body weight basis, it would receive a chronic dose of 0.00009 mg/kg/day 

(SERA, 2003-Chlorsulfuron, Worksheet F09). This dose is 0.00000064 of the chronic NOAEL, 

so there is no basis for asserting or predicting that adverse effects to fish-eating birds are plausible 

(SERA, 2003-Chlorsulfuron, p. 4-27). 

Estimated doses using the highest application rate (0.25 lb/acre) are much less than the acute and 

chronic NOAELs for birds, so there is no basis for asserting or predicting that adverse effects are 

plausible using typical or worst-case exposure assumptions (SERA, 2003-hlorsulfuron, p.4-28). 

Large Predatory Bird 

The acute NOAEL for birds in laboratory toxicity tests is 1686 mg/kg. For exposure scenarios 

that use the typical application rate of 0.056 lb/acre, if a 0.6 kg bird consumed small mammal 

prey that has been contaminated by direct spray, assuming 100 percent absorption for the prey, it 

would receive an acute dose of 0.181 mg/kg (SERA, 2003-Chlorsulfuron, Worksheet F16b). This 

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Appendix C-Wildlife 

dose is 0.0001 of the acute NOAEL, so there is no basis for asserting or predicting that adverse 

effects to predatory birds are plausible (SERA, 2003-Chlorsulfuron, p. 4-27). 

Chlorsulfuron does not appear to bioconcentrate or persist in animals following either single or 

multiple doses. The elimination of chlorsulfuron has been studied in rats, goats, cows, and hens 

(SERA, 2003-Chlorsulfuron). A combination of elimination and metabolism extensively and 

rapidly eliminated chlorsulfuron and its metabolites from the bodies of all mammalian species 

studied. The half-life for elimination in rats is less than six hours (Shrivastava 1979 cited in 

SERA, 2003-Chlorsulfuron). Therefore, chronic exposures from contaminated mammal prey due 

to a single application of chlrosulfuron are unlikely to cause any adverse effect. In addition, the 

acute dose is much less than the chronic NOAEL for birds, so there is no basis for asserting or 

predicting that adverse effects are plausible (SERA, 2003-Chlorsulfuron, p. 4-27). 

Estimated doses using the highest application rate (0.25 lb/acre) are much less than the acute and 

chronic NOAELs for birds, so there is no basis for asserting or predicting that adverse effects are 

plausible using typical or worst-case exposure assumptions (SERA, 2003-Chlorsulfuron, p.4-28). 

Small Insectivorous Bird 

The acute NOAEL for birds in laboratory toxicity tests is 1686 mg/kg. For exposure scenarios 

that use the typical application rate of 0.056 lb/acre, if a 10 g bird consumed contaminated insects 

on site shortly after application, assuming the highest residue rates, it would receive an acute dose 

of 6.32 mg/kg (SERA, 2003-Chlorsulfuron, Worksheet F14b). This dose is 0.004 of the acute 

NOAEL, so there is no basis for asserting or predicting that adverse effects to insectivorous birds 

are plausible (SERA, 2003-Chlorsulfuron, p. 4-27). 

Data on degradation of herbicide residues from insects is not available, so no chronic exposure 

scenario has been developed. However, the acute dose is much less than the chronic NOAEL as 

well, and chronic doses are much lower than acute doses. Therefore, there is no basis for asserting 

or predicting that adverse effects are plausible (SERA, 2003-Chlorsulfuron, p. 4-27). 

Estimated doses using the highest application rate (0.25 lb/acre) are much less than the acute and 

chronic NOAELs for birds, so there is no basis for asserting or predicting that adverse effects are 

plausible using typical or worst-case exposure assumptions (SERA, 2003-Chlorsulfuron, p.4-28). 

CLOPYRALID 

Small Mammal Directly Sprayed 

The acute NOAEL for mammals in laboratory toxicity tests is 75 mg/kg. For, exposure scenarios 

that use the typical application rate of 0.35 lb/acre, if a small mammal is directly sprayed, and 100 

percent absorption is assumed, the animal would receive an acute dose of 8.49 mg/kg (SERA, 

2003-Clopyralid, Worksheet F02a). This estimated dose is 0.10 of the acute NOAEL, so there is 

no basis for asserting or predicting that adverse effects to mammals are plausible (SERA, 2003-

Clopyralid, p. 4-23). 

At the highest application rate of 0.5 lb/acre, the animal would receive an acute dose of 12.1 

mg/kg (project file). This dose is 0.2 of the acute NOAEL, so there is no basis for asserting or 

predicting that adverse effects to mammals are plausible at any application rate. 

Small Mammal Drinking Contaminated Water 

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Appendix C-Wildlife 

The estimated doses to a small mammal from drinking water contaminated by an accidental spill, 

assuming the highest levels of contamination, are 2.33 mg/kg for acute exposure (SERA, 2003-

Clopryalid, Worksheet F05). If a small mammal consumes contaminated water over time, 

accounting for dissipation, degradation, and other processes, the animal would receive a chronic 

dose of 0.00067 mg/kg/day (SERA, 2003-Clopyralid, Worksheet F07). Doses to a large mammal 

would be even lower on a per kg body weight basis. These doses are 0.03 of the acute NOAEL, 

and 0.00004 of the chronic NOAEL, respectively, so there is no basis for asserting or predicting 

that adverse effects to mammals are plausible (SERA, 2003-Clopyralid, p. 4-23). 

At the highest application rate of 0.5 lb/acre, the acute dose from drinking water contaminated by 

a spill is 3.32 mg/kg (project file). This dose is 0.04 of the acute NOAEL. The chronic dose is 

also below the chronic NOAEL, so there is no basis for asserting or predicting that adverse 

effects to mammals are plausible, even in a worst-case scenario. 

Large Herbivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 75 mg/kg. For exposure scenarios 

that use the typical application rate of 0.35 lb/acre, if a 70 kg mammal consumed contaminated 

vegetation on site shortly after application, assuming the highest residue rates and 100 percents of 

the diet contaminated, it would receive an acute dose of 17.0 mg/kg (SERA, 2003-Clopyralid, 

Worksheet F10). This dose is 0.2 of the acute NOAEL, so there is no basis for asserting or 

predicting that adverse effects to large herbivorous mammals are plausible (SERA, 2003-

Clopyralid, p. 4-23). 

The chronic NOAEL for mammals in laboratory toxicity tests is 15 mg/kg/day. Chronic exposure 

from the consumption of contaminated vegetation for 90 days at the treatment site, assuming the 

highest residue rates, results in a dose of 8.95 mg/kg/day (SERA, 2003-Clopyralid, Worksheet 

F11a). This dose is 0.6 of the chronic NOAEL, so there is no basis for asserting or predicting that 

adverse effects to large herbivorous mammals are plausible (SERA, 2003-Clopyralid, p. 4-23). 

Estimated doses using the highest application rate (0.50 lb/acre) are less than the acute and 

chronic NOAELs for mammals, although only marginally so for the chronic NOAEL. Since both 

doses are still below the NOAEL, there is no basis for asserting or predicting that adverse effects 

are plausible using typical or worst-case exposure assumptions (SERA, 2003-Clopyralid, p. 4-

23). 

Medium Carnivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 75 mg/kg. For exposure scenarios 

that use the typical application rate of 0.35 lb/acre, if a 5 kg mammal consumed small mammal 

prey that has been contaminated by direct spray, assuming 100 percent absorption for the prey, it 

would receive an acute dose of 0.734 mg/kg (SERA, 2003-Clopyralid, Worksheet F16a). Doses to 

a large mammal would be even lower on a per kg body weight basis. This dose is 0.02 of the 

acute NOAEL, so there is no basis for asserting or predicting that adverse effects to carnivorous 

mammals are plausible (SERA, 2003-Clopyralid, p. 4-23). 

Clopyralid does not appear to accumulate in animal tissues. The elimination and metabolism of 

clopyralid has been studied in rats, hens, lambs, and goats (SERA, 2003-Clopyralid). These 

animals rapidly excreted largely unmetabolized clopyralid. The half-life for elimination in rats is 

three hours (Dow AgroSciences 1998 cited in SERA, 2003-Clopyralid). Therefore, chronic 

exposures from contaminated mammal prey due to a single application of clopyralid are unlikely 

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Appendix C-Wildlife 

to cause any adverse effect. In addition, the acute dose is less than the chronic NOAEL of 15 

mg/kg/day for mammals, so there is no basis for asserting or predicting that adverse effects from 

repeated acute exposures from multiple applications of clopyralid over time are plausible. 44 

Estimated doses using the highest application rate (0.50 lb/acre) are less than the acute and 

chronic NOAELs for mammals, so there is no basis for asserting or predicting that adverse effects 

are plausible using typical or worst-case exposure assumptions (SERA, 2003-Clopyralid, p. 4-

23). 

Small Herbivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 75 mg/kg. If a small mammal 

consumes contaminated vegetation shortly after application, assuming the highest residue rates, 

the acute dose received is 0.938 mg/kg (SERA 2003 Clopyralid, Worksheet F03). This estimated 

dose is 0.01 of the acute NOAEL, so there is no basis for asserting or predicting that adverse 

effects to small herbivorous mammals are plausible (SERA 2003 Clopyralid, p. 4-23). 

The chronic NOAEL for mammals in laboratory toxicity tests is 15 mg/kg/day. If a small 

mammal consumes contaminated vegetation at the treatment site for 90-days, assuming highest 

residue rates, the animal would receive a chronic dose of 0.0987 mg/kg/day (SERA 2003 

Clopyralid, Worksheet F04a). This estimated dose is 0.007 of the chronic NOAEL, so there is no 

basis for asserting or predicting that adverse effects to small herbivorous mammals are plausible 

(SERA 2003 Clopyralid, p. 4-23). 

Estimated doses using the highest application rate (0.50 lb/acre) are than the acute and chronic 

NOAELs for mammals, so there is no basis for asserting or predicting that adverse effects are 

plausible using typical or worst-case exposure assumptions (SERA 2003 Clopyralid, p. 4-23). 

Small Insectivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 75 mg/kg. For exposure scenarios 

that use the typical application rate of 0.35 lb/acre, if a small mammal consumes contaminated 

insects shortly after application, assuming the highest residue rates, the acute dose received is 

24.3 mg/kg (SERA 2003 Clopyralid, Worksheet 14a). This dose is 0.30 of the acute NOAEL, so 

there is no basis for asserting or predicting that adverse effects to insectivorous mammals are 

plausible (SERA 2003 Clopyralid, p. 4-23). 

Data on degradation of herbicide residues from insects is not available, so no chronic exposure 

scenario has been developed. Residue on insects likely declines over time, but the extent of 

decline has not been quantified. The acute dose is greater than the chronic NOAEL (15 

mg/kg/day), so adverse effects to insectivorous mammals appear plausible from chronic dietary 

exposures. The dose is less than the chronic LOAEL of 150 mg/kg/day, however. The exposure 

scenario uses residue rates from small insects, which are substantially higher than those for large 

insects, and assumes that 100 percent of the daily diet is composed of insects that have been 

directly sprayed. For bats, in particular, the scenario is unlikely to occur in the field. It seems 

more plausible for shrews and small fossorial insectivores, however 

The estimated dose (34.7 mg/kg) using the highest application rate (0.50 lb/acre) is less than the 

acute NOAEL, but greater than the chronic NOAEL for mammals. The dose is less than the 

chronic LOAEL of 150 mg/kg/day, however. No adverse effects are plausible from acute 

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Appendix C-Wildlife 

 C-55

exposures, but adverse effects to insectivorous mammals are plausible from chronic dietary 

exposures. 

Large Herbivorous Bird 

The acute NOAEL for birds in laboratory toxicity tests is 670 mg/kg. For exposure scenarios that 

use the typical application rate of 0.35 lb/acre, if a 4 kg bird consumed contaminated grass on site 

shortly after application, assuming the highest residue rates and 100 percent of diet is 

contaminated, it would receive an acute dose of 26.6 mg/kg (SERA, 2003-Clopyralid, Worksheet 

F12). This dose is 0.04 of the acute NOAEL, so there is no basis for asserting or predicting that 

adverse effects to large grass-eating birds are plausible (SERA, 2003-Clopyralid, p. 4-23). 

There is no chronic toxicity index available for effects of clopyralid to birds, so the mammal 

chronic NOAEL will be used. In acute dietary exposures, the bird NOAEL is about a factor of 

nine above the mammal NOAEL, suggesting that birds are less sensitive than mammals to 

clopyralid. The chronic NOAEL for mammals in laboratory toxicity tests is 15 mg/kg/day. 

Chronic exposure from the consumption of contaminated grass for 90 days at the treatment site, 

assuming the highest residue rates and 100 percent of diet is contaminated, results in a dose of 

14.0 mg/kg/day (SERA, 2003-Clopyralid, Worksheet F13a). This estimated dose is 0.90 of the 

chronic NOAEL for mammals, and birds appear to be less sensitive to clopyralid than mammals, 

so there is no basis for asserting or predicting that adverse effects to large grass-eating birds are 

plausible (SERA, 2003-Clopyralid, p. 4-23). 

Estimated doses using the highest application rate (0.50 lb/acre) are less than the acute NOAEL 

for birds, but greater than the chronic NOAEL for mammals. The chronic dose is less than the 

chronic LOAEL of 150 mg/kg/day, however. No adverse effects are plausible from acute 

exposures, but adverse effects to large herbivorous birds appear plausible from chronic dietary 

exposures. However, the assumptions in the chronic exposure scenario are very unlikely to occur 

in field conditions, so the weight of evidence suggests that no adverse effects are plausible using 

typical or worst-case exposure assumptions (SERA, 2003-Clopyralid, p. 4-23). 

Large Fish-eating Bird 

Many chemicals may be concentrated or partitioned from water into the tissues of animals in the 

water. This process is referred to as bioconcentration. Clopyralid does not appear to 

bioconcentrate, based on one study in sunfish (Bidlack 1982 as cited in SERA, 2003-Clopyralid). 

The exposure scenarios in the SERA risk assessment use a whole-fish BCF of 1 L/kg for acute 

and chronic exposures. 

The acute NOAEL for birds in laboratory toxicity tests is 670 mg/kg. For exposure scenarios that 

use the typical application rate of 0.35 lb/acre, if a predatory bird consumed fish from a pond 

contaminated by an accidental spill, assuming the highest concentrations in fish and highest 

intake on a body weight basis, it would receive an acute dose of 2.38 mg/kg (SERA, 2003-

Clopyralid, Worksheet F08). 

This dose is 0.004 of the acute NOAEL, so there is no basis for asserting or predicting that 

adverse effects to fish-eating birds are plausible (SERA, 2003-Clopyralid, p. 4-23). 

There is no chronic toxicity index available for effects of clopyralid to birds, so the mammal 

chronic NOAEL will be used. In acute dietary exposures, the bird NOAEL is about a factor of 

nine above the mammal NOAEL, suggesting that birds are less sensitive than mammals to 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

clopyralid. The chronic NOAEL for mammals in laboratory toxicity tests is 15 mg/kg/day. If a 

predatory bird consumed fish contaminated by runoff for a lifetime, assuming the highest 

concentrations in fish and highest intake on a body weight basis, it would receive a chronic dose 

of 0.000683 mg/kg/day (SERA 2003 Clopyralid, Worksheet F09). This estimated dose is 0.00005 

of the chronic NOAEL for mammals, so there is no basis for asserting or predicting that adverse 

effects to fish-eating birds are plausible (SERA, 2003-Clopyralid, p. 4-23). 

Estimated doses using the highest application rate (0.50 lb/acre) are less than the acute NOAEL 

for birds and chronic NOAEL for mammals, so there is no basis for asserting or predicting that 

adverse effects are plausible using typical or worst-case exposure assumptions. 

Large Predatory Bird 

The acute NOAEL for birds in laboratory toxicity tests is 670 mg/kg. For exposure scenarios that 

use the typical application rate of 0.35 lb/acre, if a 0.6 kg bird consumed small mammal prey that 

has been contaminated by direct spray, assuming 100 percent absorption for the prey, it would 

receive an acute dose of 1.13 mg/kg (SERA 2003 Clopyralid, Worksheet F16b). This is 0.002 of 

the acute NOAEL, so there is no basis for asserting or predicting that adverse effects to predatory 

birds are plausible. 

Clopyralid does not appear to bioconcentrate, based on one study in sunfish (Bidlack 1982 as 

cited in SERA 2003 Clopyralid). The elimination and metabolism of clopyralid has been studied 

in rats, hens, lambs, and goats ((SERA, 2003-Clopyralid). These animals rapidly excreted largely 

unmetabolized clopyralid. The half-life for elimination in rats is three hours (Dow AgroSciences, 

1998 cited in SERA, 2003). Therefore, chronic exposures from contaminated mammal prey due 

to a single application of clopyralid are unlikely to cause any adverse effect. In addition, the acute 

dose is less than the chronic NOAEL for birds, so there is no basis for asserting/predicting that 

adverse effects from repeated acute exposures from multiple applications of clopyralid over time 

are plausible. 

Estimated doses using the highest application rate (0.50 lb/acre) are less than the acute NOAEL 

for birds, and the chronic NOAEL for mammals, so there is no basis for asserting or predicting 

that adverse effects to predatory birds are plausible. 

Small Insectivorous Bird 

The acute NOAEL for birds in laboratory toxicity tests is 670 mg/kg. For exposure scenarios that 

use the typical application rate of 0.35 lb/acre, if a 10 g bird consumed contaminated insects on 

site shortly after application, assuming the highest residue rates, it would receive an acute dose of 

39.5 mg/kg (SERA, 2003-Clopyralid, Worksheet F14b). This dose is 0.06 of the acute NOAEL, 

so there is no basis for asserting or predicting that adverse effects to insectivorous birds are 

plausible (SERA, 2003-Clopyralid, p. 4-23). 

Data on degradation of herbicide residues from insects is not available, so no chronic exposure 

scenario has been developed. Residue on insects likely declines over time, but the extent of 

decline has not been quantified. The acute dose is greater than the chronic NOAEL (15 

mg/kg/day) for mammals, so adverse effects to insectivorous birds appear plausible from chronic 

dietary exposures. The dose is less than the chronic LOAEL of 150 mg/kg/day, however. 

The estimated dose (56.4 mg/kg) using the highest application rate (0.50 lb/acre) is less than the 

acute NOAEL for birds but greater than the chronic NOAEL for mammals. 

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Appendix C-Wildlife 

The dose is less than the chronic LOAEL of 150 mg/kg/day, however. No adverse effects are 

plausible from acute exposures, but adverse effects to insectivorous birds appear plausible from 

chronic dietary exposures. 

GLYPHOSATE 

Small Mammal Directly Sprayed 

The acute NOAEL for mammals in laboratory toxicity tests is 175 mg/kg. For, exposure scenarios 

that use the typical application rate of 2 lb/acre, if a small mammal is directly sprayed, and 100 

percent absorption is assumed, the animal would receive an acute dose of 48.5 mg/kg (SERA, 

2003-Glyphosate, Worksheet F02a). This estimated dose is 0.3 of the acute NOAEL, so there is 

no basis for asserting or predicting that adverse effects to mammals are plausible (SERA, 2003-

Glyphosate, p. 4-43). 

At the highest application rate of 7 lb/acre, the animal would receive an acute dose of 170 mg/kg 

(project file). This dose is 0.97 of the acute NOAEL, so there is no basis for asserting or 

predicting that adverse effects to mammals are plausible at any application rate. 

Small Mammal Drinking Contaminated Water 

The acute NOAEL for mammals in laboratory toxicity tests is 175 mg/kg. The estimated doses to 

a small mammal from drinking water contaminated by an accidental spill, assuming the highest 

levels of contamination, are 5.32 mg/kg for acute exposure (SERA, 2003-Glyphosate, Worksheet 

F05). If a small mammal consumes contaminated water over time, accounting for dissipation, 

degradation, and other processes, the animal would receive a chronic dose of 0.00234 mg/kg/day 

(SERA 2003 Glyphosate, Worksheet F07). Doses to a large mammal would be even lower on a 

per kg body weight basis. These doses are 0.03 of the acute NOAEL, and 0.00001 of the chronic 

NOAEL, respectively, so there is no basis for asserting or predicting that adverse effects to 

mammals are plausible (SERA, 2003-Glyphosate, p. 4-43). 

At the highest application rate of 7 lb/acre, the acute dose from drinking water contaminated by a 

spill is 18.6 mg/kg (project file). This dose is 0.1 of the acute NOAEL. The chronic dose is also 

below the chronic NOAEL, so there is no basis for asserting or predicting that adverse effects to 

mammals are plausible, even in a worst-case scenario. 

Large Herbivorous Mammal 54 

The acute NOAEL for mammals in laboratory toxicity tests is 175 mg/kg. For exposure scenarios 

that use the typical application rate of 2 lb/acre, if a 70 kg mammal consumed contaminated 

vegetation on site shortly after application, assuming the highest residue rates and 100 percents of 

the diet contaminated, it would receive an acute dose of 97.1 mg/kg (SERA, 2003-Glyphosate, 

Worksheet F10). This dose is 0.6 of the acute NOAEL, so there is no basis for asserting or 

predicting that adverse effects to large grass-eating mammals are plausible (SERA, 2003-

Glyphosate, p. 4-43). 

The chronic NOAEL for mammals in laboratory toxicity tests is 175 mg/kg/day. Chronic 

exposure from the consumption of contaminated vegetation for 90 days at the treatment site, 

assuming the highest residue rates, results in a dose of 53.2 mg/kg/day (SERA, 2003-Glyphosate, 

Worksheet F11a). This dose is 0.3 of the chronic NOAEL, so there is no/ basis for asserting or 

predicting that adverse effects to large grass-eating mammals are plausible (SERA, 2003-

Glyphosate, p. 4-43). 

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Appendix C-Wildlife 

Estimated doses using the highest application rate (7 lb/acre) result in doses greater than the acute 

and equal to the chronic NOAEL for mammals. The acute dose is equal to a LOAEL that resulted 

in some mortality to pregnant rabbits. Thus, while the acute dose to herbivorous mammals at the 

highest application rate is well below the LD50 (2,000 mg/kg), mortality in some animals would 

be plausible (SERA, 2003-Glyphosate, p. 4-44). 

Medium Carnivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 175 mg/kg. For exposure scenarios 

that use the typical application rate of 2 lb/acre, if a 5 kg mammal consumed small mammal prey 

that has been contaminated by direct spray, assuming 100 percent absorption for the prey, it 

would receive an acute dose of 4.2 mg/kg (SERA, 2003-Glyphosate, Worksheet F16a). Doses to a 

large mammal would be even lower on a per kg body weight basis. This dose is 0.024 of the acute 

NOAEL, so there is no basis for asserting or predicting that adverse effects to carnivorous 

mammals are plausible (SERA, 2003-Glyphosate, p. 4-43). 

Glyphosate does not appear to accumulate or persist in animal tissues. Only about 30 percent of 

ingested glyphosate is absorbed from the gastrointestinal tract (several studies by Davies 1996 

cited in SERA, 2003-Glyphosate). The glyphosate that is absorbed is distributed widely 

throughout the body, and then efficiently excreted. More than 97 percent of the administered dose 

is excreted unchanged, and glyphosate does not substantially concentrate or persist in any tissue 

(SERA, 2003-Glyphosate, p. 3-5). These conclusions are consistent with data from a field study 

that measured glyphosate residues in several small mammal species after an aerial application in 

Oregon (Newton et al. 1984). Newton et al. (1984) found that residues in small mammals were 

below 1 mg/kg for deermice and shrews, and below 2 mg/kg for voles, three days after treatment. 

Therefore, chronic exposures from contaminated mammal prey due to a single application of 

glyphosate are unlikely to cause any adverse effect. In addition, the acute dose is much less than 

the chronic NOAEL for mammals, so there is no basis for asserting or predicting that adverse 

effects from repeated acute exposures from multiple applications of glyphosate over time are 

plausible. 

The estimated dose using the highest application rate (7 lb/acre) is much less than the acute and 

chronic NOAEL for mammals, so there is no basis for asserting or predicting that adverse effects 

are plausible using typical or worst-case exposure assumptions. 

Small Herbivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 175 mg/kg. If a small mammal 

consumes contaminated vegetation shortly after application, assuming the highest residue rates, 

the acute dose received is 2.11 mg/kg (SERA, 2003-Glyphosate, Worksheet 

F03). This estimated dose is 0.01 of the acute NOAEL, so there is no basis for asserting or 

predicting that adverse effects to small herbivorous mammals are plausible (SERA, 2003-

Glyphosate, p. 4-43). 

The chronic NOAEL for mammals in laboratory toxicity tests is 175 mg/kg/day. If a small 

mammal consumes contaminated vegetation at the treatment site for 90-days, assuming highest 

residue rates, the animal would receive a chronic dose of 0.231 mg/kg/day (SERA 2003-

Glyphosate, Worksheet F04a). This estimated dose is 0.001 of the chronic NOAEL, so there is no 

basis for asserting or predicting that adverse effects to small herbivorous mammals are plausible 

(SERA, 2003-Glyphosate, p. 4-43). 

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Appendix C-Wildlife 

Estimated doses using the highest application rate (7 lb/acre) are less than the acute and chronic 

NOAEL for mammals, so there is no basis for asserting or predicting that adverse effects are 

plausible using typical or worst-case exposure assumptions. 

Small Insectivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 175 mg/kg. For exposure scenarios 

that use the typical application rate of 2 lb/acre, if a small mammal consumes contaminated 

insects shortly after application, assuming the highest residue rates, the acute dose received is 139 

mg/kg (SERA, 2003-Glyphosate, Worksheet 14a). This dose is 0.793 of the acute NOAEL, so 

there is no basis for asserting or predicting that adverse effects to small insectivorous mammals 

are plausible (SERA, 2003-Glyphosate, p. 4-43). 

Data on degradation of herbicide residues from insects is not available, so no chronic exposure 

scenario has been developed. Residue on insects likely declines over time, but the extent of 

decline has not been quantified. However, the acute dose is less than the chronic NOAEL as well, 

and chronic doses are much lower than acute doses. Therefore, there is no basis for asserting or 

predicting that adverse effects to insectivorous mammals from chronic exposures are plausible. 

The estimated dose (486 mg/kg) using the highest application rate (7 lb/acre) is greater than the 

acute and chronic NOAELs for mammals, so adverse effects to insectivorous mammals are 

plausible. This dose also exceeds the acute and chronic LOAEL (350 mg/kg) for diarrhea in 

mammals. The exposure scenario uses residue rates from small insects, which are substantially 

higher than those for large insects, and assumes that 100 percent of the daily diet is composed of 

insects that have been directly sprayed. For bats, in particular, the scenario is unlikely to occur in 

the field. It seems more plausible for shrews and small fossorial insectivores, however. (Check 

Newton et al 1984 paper). 

Large Herbivorous Bird 

The acute NOAEL for birds in laboratory toxicity tests is 562 mg/kg. For exposure scenarios that 

use the typical application rate of 2 lb/acre, if a 4 kg bird consumed contaminated grass on site 

shortly after application, assuming the highest residue rates and 100 percent of diet is 

contaminated, it would receive an acute dose of 152 mg/kg (SERA, 2003-Glyphosate, Worksheet 

F12). This dose is 0.3 of the acute NOAEL, so there is no basis for asserting or predicting that 

adverse effects to large grass-eating birds are plausible (SERA, 2003-Glyphosate, p. 4-43). 

The chronic NOAEL for birds in laboratory toxicity tests is 100 mg/kg/day. Chronic exposure 

from the consumption of contaminated grass for 90 days at the treatment site, assuming the 

highest residue rates and 100 percent of diet is contaminated, results in a dose of 83.2 mg/kg/day 

(SERA, 200X-Name, Worksheet F13a). This estimated dose is 0.8 of the chronic NOAEL, so 

there is no/ basis for asserting or predicting that adverse effects to large grass-eating birds are 

plausible (SERA, 2003-Glyphosate, p. 4-43). 

Estimated doses using the highest application rate (7 lb/acre) are less than the acute NOAEL, but 

greater than the chronic NOAEL for birds. LOAEL’s are not reported for birds in the sources I 

reviewed, presumably because of a lack of toxic responses in laboratory tests. No adverse effects 

are plausible from acute exposures, but adverse effects to large herbivorous birds appear plausible 

from chronic dietary exposures, based on dose exceeding the NOAEL. The assumptions in the 

chronic exposure scenario are unlikely to occur in field conditions, particularly because 

glyphosate is a non-selective herbicide and would kill most forage species at this application rate, 

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Appendix C-Wildlife 

making the forage unavailable or unpalatable. However, some monitored values for glyphosate 

residues on vegetation (Newton et al. 1994) are higher than those used in the SERA risk 

assessments. Therefore, the higher residue rates may offset the lack of forage availability, and 

adverse effects to herbivorous birds are plausible. 

Large Fish-eating Bird 

Many chemicals may be concentrated or partitioned from water into the tissues of animals in the 

water. This process is referred to as bioconcentration. The EPA uses a BCF for whole fish of 0.52 

L/kg based on a study by Forbis (1989 as cited in SERA, 2003-Glyphosate) and corroborated by 

Chamberlain et al. (1996, as cited in SERA, 2003). Therefore, exposure scenarios in the SERA 

risk assessment use a whole-fish BCF of 0.52 L/kg for acute and chronic exposures. 

The acute NOAEL for birds in laboratory toxicity tests is 562 mg/kg. For exposure scenarios that 

use the typical application rate of 2 lb/acre, if a predatory bird consumed fish from a pond 

contaminated by an accidental spill, assuming the highest concentrations in fish and highest 

intake on a body weight basis, it would receive an acute dose of 2.83 mg/kg (SERA, 2003-

Glyphosate, Worksheet F08). This dose is 0.005 of the acute NOAEL, so there is no basis for 

asserting or predicting that adverse effects to fish-eating birds are plausible (SERA, 2003-

Glyphosate, p. 4-43). 

The chronic NOAEL for birds in laboratory toxicity tests is 100 mg/kg/day. If a predatory bird 

consumed fish contaminated by runoff for a lifetime, assuming the highest concentrations in fish 

and highest intake on a body weight basis, it would receive a chronic dose of 0.00125 mg/kg/day 

(SERA, 2003-Glyphosate, Worksheet F09). This estimated dose is 0.00001 of the chronic 

NOAEL, so there is no basis for asserting/predicting that adverse effects to fish-eating birds are 

plausible. 

Estimated doses using the highest application rate (7 lb/acre) are much less than the acute and 

chronic NOAELs for birds, so there is no basis for asserting or predicting that adverse effects are 

plausible using typical or worst-case exposure assumptions. 

Large Predatory Bird 

The acute NOAEL for birds in laboratory toxicity tests is 562mg/kg. For exposure scenarios that 

use the typical application rate of 2 lb/acre, if a 0.6 kg bird consumed small mammal prey that has 

been contaminated by direct spray, assuming 100 percent absorption for the prey, it would receive 

an acute dose of 6.46 mg/kg (SERA, 2003-Glyphosate, Worksheet F16b). This is 0.0115 of the 

acute NOAEL, so there is no basis for asserting or predicting that adverse effects to predatory 

birds are plausible. 

Glyphosate does not appear to accumulate or persist in animals. Only about 30 percent of 

ingested glyphosate is absorbed from the gastrointestinal tract (several studies by Davies 1996 

cited in SERA, 2003-Glyphosate). The glyphosate that is absorbed is distributed widely 

throughout the body, and then efficiently excreted. More than 97 percent of the administered dose 

is excreted unchanged, and glyphosate does not substantially concentrate or persist in any tissue 

(SERA 2003 Glyphosate, p. 3-5). These conclusions are consistent with data from a field study 

that measured glyphosate residues in several small mammal species after an aerial application in 

Oregon (Newton et al., 1984). Newton et al. (1984) found that residues in small mammals were 

below 1 mg/kg for deermice and shrews, and below 2 mg/kg for voles, three days after treatment. 

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Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

Therefore, chronic exposures from contaminated mammal prey due to a single application of 

glyphosate are unlikely to cause any adverse effect. In addition, the acute dose is much less than 

the chronic NOAEL for birds, so there is no basis for asserting or predicting that adverse effects 

from repeated acute exposures from multiple applications of glyphosate over time are plausible. 

Estimated doses using the highest application rate (7 lb/acre) are less than the acute and chronic 

NOAELs for birds, so there is no basis for asserting or predicting that adverse effects are 

plausible using typical or worst-case exposure assumptions. 

Small Insectivorous Bird 

The acute NOAEL for birds in laboratory toxicity tests is 562 mg/kg. For exposure scenarios that 

use the typical application rate of 2 lb/acre, if a 10 g bird consumed contaminated insects on site 

shortly after application, assuming the highest residue rates, it would receive an acute dose of 226 

mg/kg (SERA, 2003-Glyphosate, Worksheet F14b). This dose is 0.4 of the acute NOAEL, so 

there is no basis for asserting or predicting that adverse effects to insectivorous birds are plausible 

(SERA, 2003-Glyphosate, p. 4-43). 

Data on degradation of herbicide residues from insects is not available, so no chronic exposure 

scenario has been developed. However, the acute dose is greater than the chronic NOAEL for 

birds. LOAEL’s are not reported for birds in the sources I reviewed, presumably because of a lack 

of toxic responses in laboratory tests. Adverse effects to insectivorous birds appear plausible from 

chronic dietary exposures, based on dose exceeding the NOAEL. 

The estimated dose using the highest application rate (7 lb/acre) is greater than the acute and 

chronic NOAELs for birds, so adverse effects to insectivorous birds appear plausible at the 

highest application rate. 

IMAZAPIC 

Small Mammal Directly Sprayed 

For, exposure scenarios that use the typical application rate of 0.1 lb/acre, if a small mammal is 

directly sprayed, and 100 percent absorption is assumed, the animal would receive an acute dose 

of 2.42 mg/kg (SERA, 2003-Imazapic, Worksheet F02a). This estimated dose is 0.007 of the 

acute NOAEL, so there is no basis for asserting or predicting that adverse effects to mammals are 

plausible (SERA, 2003-Imazapic, p. 4-21). 

At the highest application rate of 0.19 lb/acre, the animal would receive an acute dose of 4.36 

mg/kg (project file). This dose is 0.01 of the acute NOAEL, so there is no basis for asserting or 

predicting that adverse effects to mammals are plausible at any application rate. 

Small Mammal Drinking Contaminated Water 

The acute NOAEL for mammals in laboratory toxicity tests is 350 mg/kg. The estimated doses to 

a small mammal from drinking water contaminated by an accidental spill, assuming the highest 

levels of contamination, are 0.665 mg/kg for acute exposure (SERA, 2003-Imazapic, Worksheet 

F05). If a small mammal consumes contaminated water over time, accounting for dissipation, 

degradation, and other processes, the animal would receive a chronic dose of 0.000000439 

mg/kg/day (SERA, 2003-Imazapic, Worksheet F07). Doses to a large mammal would be even 

lower on a per kg body weight basis. 

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Appendix C-Wildlife 

 C-62 

These doses are 0.002 of the acute NOAEL, and 0.000000009 of the chronic NOAEL, 

respectively, so there is no basis for asserting or predicting that adverse effects to mammals are 

plausible (SERA, 2003-Imazapic, p. 4-21). 

At the highest application rate of 0.19 lb/acre, the acute dose from drinking water contaminated 

by a spill is 1.26 mg/kg (project file). This dose is 0.004 of the acute NOAEL. 

The chronic dose is also below the chronic NOAEL, so there is no basis for asserting or 

predicting that adverse effects to mammals are plausible, even in a worst-case scenario. 

Large Herbivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 350 mg/kg. For exposure scenarios 

that use the typical application rate of 0.1 lb/acre, if a 70 kg mammal consumed contaminated 

vegetation on site shortly after application, assuming the highest residue rates and 100 percents of 

the diet contaminated, it would receive an acute dose of 4.86 mg/kg (SERA, 2003-Imazapic, 

Worksheet F10). This dose is 0.01 of the acute NOAEL, so there is no basis for asserting or 

predicting that adverse effects to large grass-eating mammals are plausible (SERA 2003 

Imazapic, p. 4-21). 

The chronic NOAEL for mammals in laboratory toxicity tests is 45 mg/kg/day. Chronic exposure 

from the consumption of contaminated vegetation for 90 days at the treatment site, assuming the 

highest residue rates, results in a dose of 0.929 mg/kg/day (SERA, 2003-Imazapic, Worksheet 

F11a). This dose is 0.02 of the chronic NOAEL, so there is no/ basis for asserting or predicting 

that adverse effects to large grass-eating mammals are plausible (SERA, 2003-Imazapic, p. 4-21). 

Estimated doses using the highest application rate (0.1875 lb/acre) are less than the acute and 

chronic NOAELs for mammals, so there is no basis for asserting or predicting that adverse effects 

are plausible using typical or worst-case exposure assumptions (SERA, 20030-Imazapic, p. 4-21). 

Medium Carnivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 350 mg/kg. For exposure scenarios 

that use the typical application rate of 0.1 lb/acre, if a 5 kg mammal consumed small mammal 

prey that has been contaminated by direct spray, assuming 100 percent absorption for the prey, it 

would receive an acute dose of 0.21 mg/kg (SERA, 2003-Imazapic, Worksheet F16a). Doses to a 

large mammal would be even lower on a per kg body weight basis. This dose is 0.0006 of the 

acute NOAEL, so there is no basis for asserting or predicting that adverse effects to carnivorous 

mammals are plausible (SERA, 2003=-Imazapic, p. 4-21). 

Imazapic does not appear to accumulate or persist in animals following either single or multiple 

doses. The elimination of imazapic has been studied in rats, hens, and goats (Afzal, 1994; Cheng, 

1993; Gatterdam 1993a,b; Kao 1993a,b; Sharp and Thalacker, 1999; all as cited in SERA, 2003-

Imazapic). A combination of elimination and metabolism extensively and rapidly eliminated 

imazapic and its metabolites from the bodies of all species studied. 

Therefore, chronic exposures from contaminated mammal prey due to a single application of 

imazapic are unlikely to cause any adverse effect. In addition, the acute dose is much less than the 

chronic NOAEL for mammals, so there is no basis for asserting or predicting that adverse effects 

from repeated acute exposures from multiple applications of imazapic over time are plausible. 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

The estimated dose using the highest application rate (0.1875 lb/acre) is less than the acute and 

chronic NOAELs for mammals, so there is no basis for asserting or predicting that adverse effects 

are plausible using typical or worst-case exposure assumptions (SERA, 2003-Imazapic, p. 4-21). 

Small Herbivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 350 mg/kg. If a small mammal 

consumes contaminated vegetation shortly after application, assuming the highest residue rates, 

the acute dose received is 0.268 mg/kg (SERA, 2003-Imazapic, Worksheet F03). This estimated 

dose is 0.0008 of the acute NOAEL, so there is no basis for asserting or predicting that adverse 

effects to herbivorous mammals are plausible (SERA, 2003-Imazapic, p. 4-21). 

The chronic NOAEL for mammals in laboratory toxicity tests is 45 mg/kg/day. If a small 

mammal consumes contaminated vegetation at the treatment site for 90-days, assuming highest 

residue rates, the animal would receive a chronic dose of 0.0102 mg/kg/day (SERA, 2003-

Imazapic, Worksheet F04a). This estimated dose is 0.0002 of the chronic NOAEL, so there is no 

basis for asserting or predicting that adverse effects to herbivorous mammals are plausible 

(SERA, 2003-Imazapic, p. 4-21). 

Estimated doses using the highest application rate (0.1875 lb/acre) are less than the acute and 

chronic NOAELs for mammals, so there is no basis for asserting or predicting that adverse effects 

are plausible using typical or worst-case exposure assumptions (SERA, 2003-Imazapic, p. 4-21). 

Small Insectivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 350 mg/kg. For exposure scenarios 

that use the typical application rate of 0.1 lb/acre, if a small mammal consumes contaminated 

insects shortly after application, assuming the highest residue rates, the acute dose received is 

6.94 mg/kg (SERA, 2003-Imazapic, Worksheet 14a). This dose is 0.02 of the acute NOAEL, so 

there is no basis for asserting or predicting that adverse effects to insectivorous mammals are 

plausible (SERA, 2003-Imazapic, p. 4-21). 

Data on degradation of herbicide residues from insects is not available, so no chronic exposure 

scenario has been developed. Residue on insects likely declines over time, but the extent of 

decline has not been quantified. However, the acute dose is less than the chronic NOAEL for 

mammals as well, and chronic doses are much lower than acute doses. Therefore, there is no basis 

for asserting or predicting that adverse effects to insectivorous mammals from chronic exposures 

are plausible. 

The estimated dose using the highest application rate (0.1875 lb/acre) is less than the acute and 

chronic NOAELs for mammals, so there is no basis for asserting or predicting that adverse effects 

are plausible using typical or worst-case exposure assumptions (SERA, 2003-Imazapic, p. 4-21). 

Large Herbivorous Bird 

The acute NOAEL for birds in laboratory toxicity tests is 1100 mg/kg. For exposure scenarios 

that use the typical application rate of 0.1 lb/acre, if a 4 kg bird consumed contaminated grass on 

site shortly after application, assuming the highest residue rates and 100 percent of diet is 

contaminated, it would receive an acute dose of 7.6 mg/kg (SERA, 2003-Imazapic, Worksheet 

F12). This dose is 0.007 of the acute NOAEL, so there is no basis for asserting or predicting that 

adverse effects to large grass-eating birds are plausible (SERA, 2003-Imazapic, p. 4-21). 

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Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

The chronic NOAEL for birds in laboratory toxicity tests is 113 mg/kg/day. Chronic exposure 

from the consumption of contaminated grass for 90 days at the treatment site, assuming the 

highest residue rates and 100 percent of diet is contaminated, results in a dose of 1.45 mg/kg/day 

(SERA, 2003-Imazapic, Worksheet F13a). This estimated dose is 0.01 of the chronic NOAEL, so 

there is no/ basis for asserting or predicting that adverse effects to large grass-eating birds are 

plausible (SERA, 2003-Imazapic, p. 4-21). 

Estimated doses using the highest application rate (0.1875 lb/acre) are less than the acute and 

chronic NOAELs for birds, so there is no basis for asserting or predicting that adverse effects are 

plausible using typical or worst-case exposure assumptions (SERA 2003 Imazapic, p. 4-21). 

Large Fish-eating Bird 

Many chemicals may be concentrated or partitioned from water into the tissues of animals in the 

water. This process is referred to as bioconcentration. The potential for bioconcentration of 

imazapic in fish was studied in bluegill sunfish exposed to 

14

C-labeled imazapic for 28 days 

(Robinson, 1994, cited in SERA, 2003-Imazapic). In the SERA risk assessments, concentrations 

in viscera are considered to reflect concentration in whole fish. Bioconcentration factors (BCF) 

for bluegill were 0.11 L/kg in whole fish, indicating that the concentration of imazapic in the fish 

was less than the concentration of imazapic in the water (SERA, 2003-Imazapic). The exposure 

scenarios in the SERA risk assessment use a whole-fish BCF of 0.11 L/kg for acute and chronic 

exposures because of the rapid time it takes to reach a steady state and the very low BCF. 

The acute NOAEL for birds in laboratory toxicity tests is 1100 mg/kg. For exposure scenarios 

that use the typical application rate of 0.1 lb/acre, if a predatory bird consumed fish from a pond 

contaminated by an accidental spill, assuming the highest concentrations in fish and highest 

intake on a body weight basis, it would receive an acute dose of 0.0749 mg/kg (SERA, 2003-

Imazapic, Worksheet F08). This dose is 0.00007 of the acute NOAEL, so there is no basis for 

asserting or predicting that adverse effects to fish-eating birds are plausible (SERA, 2003-

Imazapic, p. 4-21). 

The chronic NOAEL for birds in laboratory toxicity tests is 113 mg/kg/day. If a predatory bird 

consumed fish contaminated by runoff for a lifetime, assuming the highest concentrations in fish 

and highest intake on a body weight basis, it would receive a chronic dose of 0.0000000495 

mg/kg/day (SERA, 200X-Worksheet F09). This estimated dose is 0.0000000004 of the chronic 

NOAEL, so there is no basis for asserting/predicting that adverse effects to fish-eating birds are 

plausible (SERA, 2003-Imazapic, p. 4-21). 

Estimated doses using the highest application rate (0.1875 lb/acre) also result in exposures much 

less than the acute and chronic NOAELs for birds, so there is no basis for asserting or predicting 

that adverse effects are plausible using typical or worst-case exposure assumptions (SERA, 2003-

Imazapic, p. 4-21). 

Large Predatory Bird 

The acute NOAEL for birds in laboratory toxicity tests is 1100 mg/kg. For exposure scenarios 

that use the typical application rate of 0.1 lb/acre, if a 0.6 kg bird consumed small mammal prey 

that has been contaminated by direct spray, assuming 100 percent absorption for the prey, it 

would receive an acute dose of 0.323 mg/kg (SERA, 2003-Imazapic, Worksheet F16b). This is 

0.0003 of the acute NOAEL, so there is no basis for asserting or predicting that adverse effects to 

predatory birds are plausible (SERA, 2003-Imazapic, p. 4-21). 

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Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

Imazapic does not appear to accumulate or persist in animals following either single or multiple 

doses. The elimination of imazapic has been studied in rats (Cheng 1993), hens 

(Afzal, 1994; Gatterdam, 1993a,b), and goats (Kao 1993a,b; Sharp and Thalacker, 1999; cited in 

SERA, 2003-Imazapic). A combination of elimination and metabolism extensively and rapidly 

eliminated imazapic and its metabolites from the bodies of all species studied. Therefore, chronic 

exposures from contaminated mammal prey due to a single application of imazapic are unlikely 

to cause any adverse effect. In addition, the acute dose is much less than the chronic NOAEL for 

birds, so there is no basis for asserting or predicting that adverse effects from repeated acute 

exposures from multiple applications of imazapic over time are plausible. 

The estimated dose using the highest application rate (0.1875 lb/acre) is less than the acute and 

chronic NOAELs for birds, so there is no basis for asserting or predicting that adverse effects are 

plausible using typical or worst-case exposure assumptions (SERA, 2003-Imazapic, p. 4-21). 

Small Insectivorous Bird 

The acute NOAEL for birds in laboratory toxicity tests is 1100 mg/kg. For exposure scenarios 

that use the typical application rate of 0.1 lb/acre, if a 10 g bird consumed contaminated insects 

on site shortly after application, assuming the highest residue rates, it would receive an acute dose 

of 11.3 mg/kg (SERA, 2003-Imazapic, Worksheet F14b). This dose is 0.01 of the acute NOAEL, 

so there is no basis for asserting or predicting that adverse effects to insectivorous birds are 

plausible (SERA, 2003-Imazapic, p. 4-21). 

Data on degradation of herbicide residues from insects is not available, so no chronic exposure 

scenario has been developed. Residue on insects likely declines over time, but the extent of 

decline has not been quantified. However, the acute dose is less than the chronic NOAEL for 

birds as well, and chronic doses are much lower than acute doses. Therefore, there is no basis for 

asserting or predicting that adverse effects to insectivorous birds from chronic exposures are 

plausible. 

The estimated dose using the highest application rate (0.1875 lb/acre) is less than the acute and 

chronic NOAELs for birds, so there is no basis for asserting or predicting that adverse effects are 

plausible using typical or worst-case exposure assumptions (SERA, 2003-Imazapic, p. 4-21). 

IMAZAPYR 

Small Mammal Directly Sprayed 

The acute NOAEL for mammals in laboratory toxicity tests is 250 mg/kg. For, exposure scenarios 

that use the typical application rate of 0.45 lb/acre, if a small mammal is directly sprayed, and 100 

percent absorption is assumed, the animal would receive an acute dose of 10.9 mg/kg (SERA, 

2003-Imazapyr, Worksheet F02a). This estimated dose is 0.04 of the acute NOAEL, so there is no 

basis for asserting or predicting that adverse effects to herbivorous mammals are plausible 

(SERA, 2003-Imazapyr, p. 4-25). 

At the highest application rate of 1.25 lb/acre, the animal would receive an acute dose of 30.3 

mg/kg (project file). This dose is 0.1 of the acute NOAEL, so there is no basis for asserting or 

predicting that adverse effects to mammals are plausible at any application rate. 

Small Mammal Drinking Contaminated Water 

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Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

The estimated doses to a small mammal from drinking water contaminated by an accidental spill, 

assuming the highest levels of contamination, are 1.22 mg/kg for acute exposure (SERA, 2003-

Imazapyr, Worksheet F05). If a small mammal consumes contaminated water over time, 

accounting for dissipation, degradation, and other processes, the animal would receive a chronic 

dose of 0.0000659 mg/kg/day (SERA 2003 Imazapyr, Worksheet F07). Doses to a large mammal 

would be even lower on a per kg body weight basis. These doses are 0.005 of the acute NOAEL, 

and 0.0000003 of the chronic NOAEL, respectively, so there is no basis for asserting or 

predicting that adverse effects to mammals are plausible (SERA, 2003-Imazapyr, p. 4-25). 

At the highest application rate of 1.25 lb/acre, the acute dose from drinking water contaminated 

by a spill is 3.39 mg/kg (project file). This dose is 0.005 of the acute NOAEL. The chronic dose is 

also below the chronic NOAEL, so there is no basis for asserting or predicting that adverse 

effects to mammals are plausible, even in a worst-case scenario. The acute NOAEL for mammals 

in laboratory toxicity tests is 250 mg/kg. For exposure scenarios that use the typical application 

rate of 0.45 lb/acre, if a 5 kg mammal consumed small mammal prey that has been contaminated 

by direct spray, assuming 100 percent absorption for the prey, it would receive an acute dose of 

0.944 mg/kg (SERA, 2003-Imazapyr, Worksheet F16a). (Doses to a large mammal would be even 

lower on a per kg body weight basis). This dose is 0.004 of the acute NOAEL, so there is no basis 

for asserting or predicting that adverse effects to carnivorous mammals are plausible (SERA, 

2003-Imazapyr, p. 4-25). 

Imazapyr does not appear to accumulate or persist in animals following either single or multiple 

doses (SERA, 2003-Imazapyr, p. 3-2). The elimination of imazapyr has been studied in rats and 

lactating goats and the studies reported that it is rapidly excreted, unchanged, in urine and feces 

(Mallipudi et al., 1983; and Zdybak, 1992 as cited in SERA, 2003-Imazapyr). No metabolites 

were identified. Therefore, chronic exposures from contaminated mammal prey due to a single 

application of imazapyr are unlikely to cause any adverse effect. In addition, the acute dose is 

much less than the chronic NOAEL for mammals, so there is no basis for asserting or predicting 

that adverse effects from repeated acute exposures from multiple applications of imazapyr over 

time are plausible. 

Estimated doses using the highest application rate (1.25 lb/acre) are less than the acute and 

chronic NOAEL for mammals, so there is no basis for asserting or predicting that adverse effects 

are plausible using typical or worst-case exposure assumptions (SERA, 2003-mazapyr, p. 4-25). 

The acute NOAEL for mammals in laboratory toxicity tests is 250 mg/kg. For exposure scenarios 

that use the typical application rate of 0.45 lb/acre, if a 70 kg mammal consumed contaminated 

vegetation on site shortly after application, assuming the highest residue rates and 100 percents of 

the diet contaminated, it would receive an acute dose of 21.9 mg/kg (SERA, 2003-Imazapyr, 

Worksheet F10). This dose is 0.09 of the acute NOAEL, so there is no basis for asserting or 

predicting that adverse effects to large grass-eating mammals are plausible (SERA, 2003-

Imazapyr, p. 4-25). 

The chronic NOAEL for mammals in laboratory toxicity tests is 250 mg/kg/day. Chronic 

exposure from the consumption of contaminated vegetation for 90 days at the treatment site, 

assuming the highest residue rates, results in a dose of 10.6 mg/kg/day (SERA, 200X-Name, 

Worksheet F11a). This dose is 0.04 of the chronic NOAEL, so there is no basis for asserting or 

predicting that adverse effects to large grass-eating mammals are plausible (SERA, 2003-

Imazapyr, p. 4-25). 

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Appendix C-Wildlife 

Estimated doses using the highest application rate (1.25 lb/acre) are less than the acute and 

chronic NOAEL for mammals, so there is no basis for asserting or predicting that adverse effects 

are plausible using typical or worst-case exposure assumptions (SERA, 2003-Imazapyr, p. 4.25). 

Medium Carnivorous Mammal 

Large Herbivorous Mammal 

Small Herbivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 250 mg/kg. If a small mammal 

consumes contaminated vegetation shortly after application, assuming the highest residue rates, 

the acute dose received is 1.21 mg/kg (SERA, 2003-Imazapyr, Worksheet F03). This estimated 

dose is 0.005 of the acute NOAEL, so there is no basis for asserting or predicting that adverse 

effects to herbivorous mammals are plausible (SERA, 2003-Imazapyr, p. 4-25). 

The chronic NOAEL for mammals in laboratory toxicity tests is 250 mg/kg/day. If a small 

mammal consumes contaminated vegetation at the treatment site for 90-days, assuming highest 

residue rates, the animal would receive a chronic dose of 0.117 mg/kg/day (SERA, 2003-

Imazapyr, Worksheet F04a). This estimated dose is 0.0005 of the chronic NOAEL, so there is no 

basis for asserting or predicting that adverse effects to herbivorous mammals are plausible. 

Estimated doses using the highest application rate (1.25 lb/acre) are less than the acute and 

chronic NOAEL for mammals, so there is no basis for asserting or predicting that adverse effects 

are plausible using typical or worst-case exposure assumptions (SERA, 2003-Imazapyr, p. 4-25). 

Small Insectivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 250 mg/kg. For exposure scenarios 

that use the typical application rate of 0.45 lb/acre, if a small mammal consumes contaminated 

insects shortly after application, assuming the highest residue rates, the acute dose received is 

31.2 mg/kg (SERA, 2003-Imazapyr, Worksheet 14a). This dose is 0.1 of the acute NOAEL, so 

there is no basis for asserting or predicting that adverse effects to insectivorous mammals are 

plausible (SERA, 2003-Imazapyr, p. 4-25). 

Data on degradation of herbicide residues from insects is not available, so no chronic exposure 

scenario has been developed. Residue on insects likely declines over time, but the extent of 

decline has not been quantified. However, the acute dose is less than the chronic NOAEL for 

mammals as well, and chronic doses are much lower than acute doses. Therefore, there is no basis 

for asserting or predicting that adverse effects to insectivorous mammals from chronic exposures 

are plausible. 

The estimated dose using the highest application rate (1.25 lb/acre) is less than the acute and 

chronic NOAEL for mammals, so there is no basis for asserting or predicting that adverse effects 

are plausible using typical or worst-case exposure assumptions (SERA, 2003-Imazapyr, p. 4-25). 

Large Herbivorous Bird 

The acute NOAEL for birds in laboratory toxicity tests is 674 mg/kg. For exposure scenarios that 

use the typical application rate of 0.45 lb/acre, if a 4 kg bird consumed contaminated grass on site 

shortly after application, assuming the highest residue rates and 100 percent of diet is 

contaminated, it would receive an acute dose of 34.2 mg/kg (SERA, 2003-Imazapyr, Worksheet 

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Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

F12). This dose is 0.05 of the acute NOAEL, so there is no basis for asserting or predicting that 

adverse effects to large grass-eating birds are plausible (SERA, 2003-Imazapyr, p. 4-25). 

The chronic NOAEL for birds in laboratory toxicity tests is 200 mg/kg/day. Chronic exposure 

from the consumption of contaminated grass for 90 days at the treatment site, assuming the 

highest residue rates and 100 percent of diet is contaminated, results in a dose of 16.5 mg/kg/day 

(SERA, 2003-Imazapyr, Worksheet F13a). This estimated dose is 0.08 of the chronic NOAEL, so 

there is no/ basis for asserting or predicting that adverse effects to large grass-eating birds are 

plausible (SERA, 2003-Imazapyr, p. 4-25). 

Estimated doses using the highest application rate (1.25 lb/acre) are less than the acute and 

chronic NOAEL for mammals, so there is no basis for asserting or predicting that adverse effects 

are plausible using typical or worst-case exposure assumptions (SERA, 2003-Imazapyr, p. 4-25). 

Large Fish-eating Bird 

Many chemicals may be concentrated or partitioned from water into the tissues of animals in the 

water. This process is referred to as bioconcentration. The potential for bioconcentration of 

imazapyr in fish was studied in bluegill sunfish exposed to 

14

C-labeled imazapyr for 28 days 

(McAllister et al., 1985, cited in SERA, 2003-Imazapyr). In the SERA risk assessments, 

concentrations in viscera are considered to reflect concentration in whole fish. Bioconcentration 

factors (BCF) for bluegill were 0.5 L/kg, indicating that the concentration of imazapyr in the fish 

was less than the concentration of imazapyr in the water (SERA, 2003-Imazapyr, p. 3-20). The 

exposure scenarios in the SERA risk assessment use a whole-fish BCF of 0.5 L/kg for acute and 

chronic exposures. 

The acute NOAEL for birds in laboratory toxicity tests is 674 mg/kg. For exposure scenarios that 

use the typical application rate of 0.45 lb/acre, if a predatory bird consumed fish from a pond 

contaminated by an accidental spill, assuming the highest concentrations in fish and highest 

intake on a body weight basis, it would receive an acute dose of 0.625 mg/kg (SERA, 2003-

Imazapyr, Worksheet F08). This dose is 0.0009 of the acute NOAEL, so there is no basis for 

asserting or predicting that adverse effects to fish-eating birds are plausible (SERA, 2003-

Imazapyr, p. 4-25). 

The chronic NOAEL for birds in laboratory toxicity tests is 200 mg/kg/day. If a predatory bird 

consumed fish contaminated by runoff for a lifetime, assuming the highest concentrations in fish 

and highest intake on a body weight basis, it would receive a chronic dose of 0.0000338 

mg/kg/day (SERA, 2003-Imazapyr, Worksheet F09). This estimated dose is 0.0000002 of the 

chronic NOAEL, so there is no basis for asserting/predicting that adverse effects to fish-eating 

birds are plausible. 

Estimated doses using the highest application rate (1.25 lb/acre) are less than the acute and 

chronic NOAEL for birds, so there is no basis for asserting or predicting that adverse effects are 

plausible using typical or worst-case exposure assumptions (SERA, 2003-Imazapyr, p. 4-25). 

Large Predatory Bird 

The acute NOAEL for birds in laboratory toxicity tests is 674 mg/kg. For exposure scenarios that 

use the typical application rate of 0.45 lb/acre, if a 0.6 kg bird consumed small mammal prey that 

has been contaminated by direct spray, assuming 100 percent absorption for the prey, it would 

receive an acute dose of 1.45 mg/kg (SERA, 2003-Imazapyr, Worksheet F16b). This is 0.002 of 

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Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

the acute NOAEL, so there is no basis for asserting or predicting that adverse effects to predatory 

birds are plausible. 

Imazapyr does not appear to accumulate or persist in animals following either single or multiple 

doses (SERA, 2003-Imazapyr, p. 3-2). The elimination of imazapyr has been studied in rats and 

lactating goats and the studies reported that it is rapidly excreted, unchanged, in urine and feces 

(Mallipudi et al., 1983; and Zdybak, 1992 as cited in SERA, 2003-Imazapyr). No metabolites 

were identified. Therefore, chronic exposures from contaminated mammal prey due to a single 

application of imazapyr are unlikely to cause any adverse effect. In addition, the acute dose is 

much less than the chronic NOAEL for birds, so there is no basis for asserting or predicting that 

adverse effects from repeated acute exposures from multiple applications of imazapyr over time 

are plausible. 

The estimated dose using the highest application rate (1.25 lb/acre) is less than the acute and 

chronic NOAEL for mammals, so there is no basis for asserting or predicting that adverse effects 

are plausible using typical or worst-case exposure assumptions (SERA, 2003-Imazapyr, p. 4-25). 

Small Insectivorous Bird 

The acute NOAEL for birds in laboratory toxicity tests is 674 mg/kg. For exposure scenarios that 

use the typical application rate of 0.45 lb/acre, if a 10 g bird consumed contaminated insects on 

site shortly after application, assuming the highest residue rates, it would receive an acute dose of 

50.8 mg/kg (SERA, 2003-Imazapyr, Worksheet F14b). This dose is 0.08 of the acute NOAEL, so 

there is no basis for asserting or predicting that adverse effects to insectivorous birds are plausible 

(SERA, 2003-Imazapyr, p. 4-25). 

Data on degradation of herbicide residues from insects is not available, so no chronic exposure 

scenario has been developed. Residue on insects likely declines over time, but the extent of 

decline has not been quantified. However, the acute dose is less than the chronic NOAEL for 

birds as well, and chronic doses are much lower than acute doses. Therefore, there is no basis for 

asserting or predicting that adverse effects to insectivorous birds from chronic exposures are 

plausible. 

The estimated dose using the highest application rate (1.25 lb/acre) is less than the acute and 

chronic NOAEL for birds, so there is no basis for asserting or predicting that adverse effects are 

plausible using typical or worst-case exposure assumptions (SERA, 2003-Imazapyr, p. 4-25). 

METSULFURON METHYL 

Small Mammal Directly Sprayed 

The acute NOAEL for mammals in laboratory toxicity tests is 25 mg/kg. For, exposure scenarios 

that use the typical application rate of 0.03 lb/acre, if a small mammal is directly sprayed, and 100 

percent absorption is assumed, the animal would receive an acute dose of 0.727 mg/kg (SERA, 

2003-Metsulfuron methyl, Worksheet F02a). This estimated dose is 0.03 of the acute NOAEL, so 

there is no basis for asserting or predicting that adverse effects to herbivorous mammals are 

plausible (SERA, 2003-Metsulfuron methyl, p. 4-26). 

At the highest application rate of 0.15 lb/acre, the animal would receive an acute dose of 3.64 

mg/kg (project file). This dose is 0.1 of the acute NOAEL, so there is no basis for asserting or 

predicting that adverse effects to mammals are plausible at any application rate. 

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Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

Small Mammal Drinking Contaminated Water 

The estimated doses to a small mammal from drinking water contaminated by an accidental spill, 

assuming the highest levels of contamination, are 0.0443 mg/kg for acute exposure (SERA, 2003-

Metsulfuron methyl, Worksheet F05). If a small mammal consumes contaminated water over 

time, accounting for dissipation, degradation, and other processes, the animal would receive a 

chronic dose of 0.00000176 mg/kg/day (SERA 2003 Metsulfuron methyl, Worksheet F07). Doses 

to a larger mammal would be even lower on a per kg body weight basis. These doses are 0.002 of 

the acute NOAEL, and 0.00000007 of the chronic NOAEL, respectively, so there is no basis for 

asserting or predicting that adverse effects to mammals are plausible (SERA, 2003-Metsulfuron 

methyl, p. 4-26, 4-27). 

At the highest application rate of 0.15 lb/acre, the acute dose from drinking water contaminated 

by a spill is 0.222 mg/kg (project file). This dose is 0.009 of the acute NOAEL. The chronic dose 

is also below the chronic NOAEL, so there is no basis for asserting or predicting that adverse 

effects to mammals are plausible, even in a worst-case scenario. 

Large Herbivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 25 mg/kg. For exposure scenarios 

that use the typical application rate of 0.03 lb/acre, if a 70 kg mammal consumed contaminated 

vegetation on site shortly after application, assuming the highest residue rates and 100 percents of 

the diet contaminated, it would receive an acute dose of 1.46 mg/kg (SERA, 2003-Metsulfuron 

methyl, Worksheet F10). This dose is 0.06 of the acute NOAEL, so there is no basis for asserting 

or predicting that adverse effects to large grass-eating mammals are plausible (SERA, 2003-

Metsulfuron methyl, p. 4-26). The chronic NOAEL for mammals in laboratory toxicity tests is 25 

mg/kg/day. Chronic exposure from the consumption of contaminated vegetation for 90 days at the 

treatment site, assuming the highest residue rates, results in a dose of 0.613 mg/kg/day (SERA, 

2003-Metsulfuron methyl, Worksheet F11a). This dose is 0.02 of the chronic NOAEL, so there is 

no basis for asserting or predicting that adverse effects to large grass-eating mammals are 

plausible (SERA, 2003-Metsulfuron methyl, p. 4-27). 

Estimated doses using the highest application rate (0.15 lb/acre) are less than the acute and 

chronic NOAEL for mammals, so there is no basis for asserting or predicting that adverse effects 

are plausible using typical or worst-case exposure assumptions (SERA 2003 Metsulfuron methyl, 

p. 4-27). 

Medium Carnivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 25 mg/kg. For exposure scenarios 

that use the typical application rate of 0.03 lb/acre, if a 5 kg mammal consumed small mammal 

prey that has been contaminated by direct spray, assuming 100 percent absorption for the prey, it 

would receive an acute dose of 0.0629 mg/kg (SERA, 2003-Metsulfuron methyl, Worksheet 

F16a). Doses to a large mammal would be even lower on a per kg body weight basis. This dose is 

0.003 of the acute NOAEL, so there is no basis for asserting or predicting that adverse effects to 

carnivorous mammals are plausible (SERA, 2003-Metsulfuron methyl, p. 4-26). 

Metsulfuron methyl does not appear to accumulate or persist in animal tissues. The elimination of 

metsulfuron methyl has been studied in rats, hens cows, and goats (SERA 2003 Metsulfuron 

methyl, citing Charlton and Bookhart, 1996; USEPA, 1998; Hershberger and Moore, 1985; 

Hundley, 1985; Hunt, 1984). A combination of elimination of the unchanged compound and 

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Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

metabolism rapidly eliminated metsulfuron methyl from the bodies of all species studied. The 

half-life for elimination in all species is one day or less (SERA, 2003-Metsulfuron methyl, p. 3-

3). Therefore, chronic exposures from contaminated mammal prey due to a single application of 

metsulfuron methyl are unlikely to cause any adverse effect. In addition, the acute dose is much 

less than the chronic NOAEL for mammals, so there is no basis for asserting or predicting that 

adverse effects from repeated acute exposures from multiple applications of metsulfuron methyl 

over time are plausible. The estimated dose using the highest application rate (0.15 lb/acre) is less 

than the acute and chronic NOAEL for mammals, so there is no basis for asserting or predicting 

that adverse effects are plausible using typical or worst-case exposure assumptions (SERA, 2003-

etsulfuron methyl, p. 4-27). 

Small Herbivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 25 mg/kg. If a small mammal 

consumes contaminated vegetation shortly after application, assuming the highest residue rates, 

the acute dose received is 0.0804 mg/kg (SERA, 200- Metsulfuron methyl, Worksheet F03). This 

estimated dose is 0.003 of the acute NOAEL, so there is no basis for asserting or predicting that 

adverse effects to herbivorous mammals are plausible (SERA, 2003-Metsulfuron methyl, p. 4-

26). 

The chronic NOAEL for mammals in laboratory toxicity tests is 25 mg/kg/day. If a small 

mammal consumes contaminated vegetation at the treatment site for 90-days, assuming highest 

residue rates, the animal would receive a chronic dose of 0.00676 mg/kg/day (SERA, 2003-

Metsulfuron methyl, Worksheet F04a). This estimated dose is 0.0003 of the chronic NOAEL, so 

there is no basis for asserting or predicting that adverse effects to small herbivorous mammals are 

plausible (SERA, 2003-Metsulfuron methyl, p. 4-27). 

Estimated doses using the highest application rate (0.15 lb/acre) are less than the acute and 

chronic NOAEL for mammals, so there is no basis for asserting or predicting that adverse effects 

are plausible using typical or worst-case exposure assumptions (SERA 2003 Metsulfuron methyl, 

p. 4-27). 

Small Insectivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 25 mg/kg. For exposure scenarios 

that use the typical application rate of 0.03 lb/acre, if a small mammal consumes contaminated 

insects shortly after application, assuming the highest residue rates, the acute dose received is 

2.08 mg/kg (SERA, 2003-Metsulfuron methyl, Worksheet 14a). This dose is 0.08 of the acute 

NOAEL, so there is no basis for asserting or predicting that adverse effects to insectivorous 

mammals are plausible (SERA, 2003-Metsulfuron methyl, p. 4-26). 

Data on degradation of herbicide residues from insects is not available, so no chronic exposure 

scenario has been developed. Residue on insects likely declines over time, but the extent of 

decline has not been quantified. However, the acute dose is less than the chronic NOAEL as well, 

and chronic doses are much lower than acute doses. Therefore, there is no basis for asserting or 

predicting that adverse effects to insectivorous mammals from chronic exposures are plausible. 

Estimated doses using the highest application rate (0.15 lb/acre) also result in an exposure less 

than the acute and chronic NOAEL for mammals, so there is no basis for asserting or predicting 

that adverse effects are plausible using typical or worst-case exposure assumptions. 

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Appendix C-Wildlife 

Large Herbivorous Bird 

The acute NOAEL for birds in laboratory toxicity tests is 1043 mg/kg. For exposure scenarios 

that use the typical application rate of 0.03 lb/acre, if a 4 kg bird consumed contaminated grass on 

site shortly after application, assuming the highest residue rates and 100 percent of diet is 

contaminated, it would receive an acute dose of 2.28 mg/kg (SERA, 2003-Metsulfuron methyl, 

Worksheet F12). This dose is 0.002 of the acute NOAEL, so there is no basis for asserting or 

predicting that adverse effects to large grass-eating birds are plausible (SERA, 2003-Metsulfuron 

methyl, p. 4-26). 

The chronic NOAEL for birds in laboratory toxicity tests is 120 mg/kg/day. Chronic exposure 

from the consumption of contaminated grass for 90 days at the treatment site, assuming the 

highest residue rates and 100 percent of diet is contaminated, results in a dose of 0.96 mg/kg/day 

(SERA, 2003-Metsulfuron methyl, Worksheet F13a). This estimated dose is 0.008 of the chronic 

NOAEL, so there is no basis for asserting or predicting that adverse effects to large grass-eating 

birds are plausible (SERA, 2003-Metsulfuron methyl, p. 4-27). 

Estimated doses using the highest application rate (0.15 lb/acre) are less than the acute and 

chronic NOAELs for birds, so there is no basis for asserting or predicting that adverse effects are 

plausible using typical or worst-case exposure assumptions (SERA, 2003-Metsulfuron methyl, p. 

4-27). 

Large Fish-eating Bird 

Many chemicals may be concentrated or partitioned from water into the tissues of animals in the 

water. This process is referred to as bioconcentration. The potential for bioconcentration of 

metsulfuron methyl in fish was studied in bluegill sunfish exposed to 

14

C-metsulfuron methyl for 

28 days (Han 1982, cited in SERA, 2003-Metsulfuron methyl). In the SERA risk assessments, 

concentrations in viscera are considered to reflect concentration in whole fish. Bioconcentration 

factors (BCF) reported for bluegill viscera were 0.21 L/kg after 24 hours and the highest BCF 

reported was 2.11 L/kg after 14 days (SERA, 2003-Metsulfuron methyl, Appendix 8). The 

exposure scenarios in the SERA risk assessment use a whole-fish BCF of 0.21 L/kg for acute 

exposure and 2.11 L/kg for chronic exposure. 

The acute NOAEL for birds in laboratory toxicity tests is 1043 mg/kg. For exposure scenarios 

that use the typical application rate of 0.03 lb/acre, if a predatory bird consumed fish from a pond 

contaminated by an accidental spill, assuming the highest concentrations in fish and highest 

intake on a body weight basis, it would receive an acute dose of 0.00954 mg/kg (SERA, 2003-

Metsulfuron methyl, Worksheet F08). This dose is 0.000009 of the acute NOAEL, so there is no 

basis for asserting or predicting that adverse effects to fish-eating birds are plausible (SERA, 

2003-Metsulfuron methyl, p. 4-26). 

The chronic NOAEL for birds in laboratory toxicity tests is 120 mg/kg/day. If a predatory bird 

consumed fish contaminated by runoff for a lifetime, assuming the highest concentrations in fish 

and highest intake on a body weight basis, it would receive a chronic dose of 0.0000038 

mg/kg/day (SERA, 2003-Metsulfuron methyl, Worksheet F09). This estimated dose is 

0.00000003 of the chronic NOAEL, so there is no basis for asserting/predicting that adverse 

effects to fish-eating birds are plausible (SERA 2003 Metsulfuron methyl, p. 4-27). 

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Appendix C-Wildlife 

Estimated doses using the highest application rate (0.15 lb/acre) are much less than the acute and 

chronic NOAELs for birds, so there is no basis for asserting or predicting that adverse effects are 

plausible using typical or worst-case exposure assumptions. 

Large Predatory Bird 

The acute NOAEL for birds in laboratory toxicity tests is 1043mg/kg. For exposure scenarios that 

use the typical application rate of 0.03 lb/acre, if a 0.6 kg bird consumed small mammal prey that 

has been contaminated by direct spray, assuming 100 percent absorption for the prey, it would 

receive an acute dose of 0.097 mg/kg (SERA, 2003-Metsulfuron methyl, Worksheet F16b). This 

is 0.00009 of the acute NOAEL, so there is no basis for asserting or predicting that adverse 

effects to predatory birds are plausible (SERA, 2003-Metsulfuron methyl, p. 4-26). 

Metsulfuron methyl does not appear to accumulate or persist in animal tissues. The elimination of 

metsulfuron methyl has been studied in rats, hens cows, and goats (SERA, 2003-Metsulfuron 

methyl, citing Charlton and Bookhart, 1996; USEPA, 1998; Hershberger and Moore, 1985; 

Hundley, 1985; Hunt, 1984). A combination of elimination of the unchanged compound and 

metabolism rapidly eliminated metsulfuron methyl from the bodies of all species studied. The 

half-life for elimination in all species is one day or less (SERA, 2003-Metsulfuron methyl, p. 3-

3). Therefore, chronic exposures from contaminated mammal prey due to a single application of 

metsulfuron methyl are unlikely to cause any adverse effect. In addition, the acute dose is much 

less than the chronic NOAEL for birds, so there is no basis for asserting or predicting that adverse 

effects from repeated acute exposures from multiple applications of metsulfuron methyl over time 

are plausible. 

The estimated dose using the highest application rate (0.15 lb/acre) is less than the acute and 

chronic NOAELs for birds, so there is no basis for asserting or predicting that adverse effects are 

plausible using typical or worst-case exposure assumptions. 

Small Insectivorous Bird 

The acute NOAEL for birds in laboratory toxicity tests is 1043 mg/kg. For exposure scenarios 

that use the typical application rate of 0.03 lb/acre, if a 10 g bird consumed contaminated insects 

on site shortly after application, assuming the highest residue rates, it would receive an acute dose 

of 3.38 mg/kg (SERA, 2003-Metsulfuron methyl, Worksheet F14b). This dose is 0.003 of the 

acute NOAEL, so there is no basis for asserting or predicting that adverse effects to insectivorous 

birds are plausible (SERA, 2003-Metsulfuron methyl, p. 4-26). 

Data on degradation of herbicide residues from insects is not available, so no chronic exposure 

scenario has been developed. However, the acute dose is less than the chronic NOAEL for birds 

as well, and chronic doses are much less than acute doses. Therefore, there is no basis for 

asserting or predicting that adverse effects to insectivorous birds from chronic exposures are 

plausible. 

The estimated doses using the highest application rate (0.15 lb/acre) is less than the acute and 

chronic NOAELs for birds, so there is no basis for asserting or predicting that adverse effects are 

plausible using typical or worst-case exposure assumptions. 

PICLORAM 

Small Mammal Directly Sprayed 

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Appendix C-Wildlife 

The acute NOAEL for mammals in laboratory toxicity tests is 34 mg/kg. For, exposure scenarios 

that use the typical application rate of 0.35 lb/acre, if a small mammal is directly sprayed, and 100 

percent absorption is assumed, the animal would receive an acute dose of 8.49 mg/kg (SERA, 

2003-Picloram, Worksheet F02a). This estimated dose is 0.2 of the acute NOAEL, so there is no 

basis for asserting or predicting that adverse effects to herbivorous mammals are plausible 

(SERA, 2003-Picloram, p. 4-29). 

At the highest application rate of 1 lb/acre, the animal would receive an acute dose of 24.2 mg/kg 

(project file). This dose is 0.7 of the acute NOAEL, so there is no basis for asserting or predicting 

that adverse effects to mammals are plausible at any application rate. 

Small Mammal Drinking Contaminated Water 

The estimated doses to a small mammal from drinking water contaminated by an accidental spill, 

assuming the highest levels of contamination, are 0.887 mg/kg for acute exposure (SERA, 2003-

Picloram, Worksheet F05). If a small mammal consumes contaminated water over time, 

accounting for dissipation, degradation, and other processes, the animal would receive a chronic 

dose of 0.000205 mg/kg/day (SERA, 2003-Picloram, Worksheet F07). 

Doses to a large mammal would be even lower on a per kg body weight basis. These doses are 

0.03 of the acute NOAEL, and 0.00003 of the chronic NOAEL, respectively, so there is no basis 

for asserting or predicting that adverse effects to mammals are plausible (SERA, 2003-Picloram, 

p. 4-29). 

At the highest application rate of 1 lb/acre, the acute dose from drinking water contaminated by a 

spill is 2.53 mg/kg (project file). This dose is 0.07 of the acute NOAEL. The chronic dose is also 

below the chronic NOAEL, so there is no basis for asserting or predicting that adverse effects to 

mammals are plausible, even in a worst-case scenario. 

Large Herbivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 34 mg/kg. For exposure scenarios 

that use the typical application rate of 0.35 lb/acre, if a 70 kg mammal consumed contaminated 

vegetation on site shortly after application, assuming the highest residue rates and 100 percents of 

the diet contaminated, it would receive an acute dose of 17.0 mg/kg (SERA, 2003-Picloram, 

Worksheet F10). This dose is 0.5 of the acute NOAEL, so there is no basis for asserting or 

predicting that adverse effects to large grass-eating mammals are plausible (SERA, 2003-

Picloram, p. 4-29). The chronic NOAEL for mammals in laboratory toxicity tests is 7 mg/kg/day. 

Chronic exposure from the consumption of contaminated vegetation for 90 days at the treatment 

site, assuming the highest residue rates, results in a dose of 2.18 mg/kg/day (SERA 2003 

Picloram, Worksheet F11a). This dose is 0.3 of the chronic NOAEL, so there is no basis for 

asserting or predicting that adverse effects to large grass-eating mammals are plausible (SERA, 

2003-Picloram, p. 4-29). 

Estimated doses using the highest application rate (1 lb/acre) are greater than the acute NOAEL 

and about equal to the chronic NOAEL for mammals. The acute dose (48.6 mg/kg) is less than 

the acute LOAEL for decreased weight gain in rabbits (USEPA/OPP, 1998). No adverse effects 

are plausible from chronic exposures, but adverse effects to large herbivorous mammals may be 

plausible from acute dietary exposures. 

Medium Carnivorous Mammal 

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Appendix C-Wildlife 

The acute NOAEL for mammals in laboratory toxicity tests is 34 mg/kg. For exposure scenarios 

that use the typical application rate of 0.35 lb/acre, if a 5 kg mammal consumed small mammal 

prey that has been contaminated by direct spray, assuming 100 percent absorption for the prey, it 

would receive an acute dose of 0.734 mg/kg (SERA, 2003-Picloram, Worksheet F16a). Doses to a 

larger mammal would be even lower on a per kg body weight basis. This dose is 0.0216 of the 

acute NOAEL, so there is no basis for asserting or predicting that adverse effects to carnivorous 

mammals are plausible (SERA, 2003-Picloram, p. 4-29). 

Picloram does not appear to accumulate or persist in animals. The elimination of picloram has 

been studied in humans, rats, dogs, and cattle (SERA 2003 Picloram). In humans, over 75 percent 

of the administered picloram was eliminated after six hours and over 90 percent was eliminated 

after 72 hours (SERA, 2003-Picloram citing Nolan et al. 1984). Therefore, chronic exposures 

from contaminated mammal prey due to a single application of picloram are unlikely to cause any 

adverse effect. In addition, the acute dose is much less than the chronic NOAEL for mammals, so 

there is no basis for asserting or predicting that adverse effects from repeated acute exposures 

from multiple applications of carnivorous mammals over time are plausible. 

The estimated dose using the highest application rate (1 lb/acre) is less than the acute and chronic 

NOAELs for mammals, so there is no basis for asserting or predicting that adverse effects are 

plausible using typical or worst-case exposure assumptions. 

Small Herbivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 34 mg/kg. If a small mammal 

consumes contaminated vegetation shortly after application, assuming the highest residue rates, 

the acute dose received is 0.938 mg/kg (SERA, 2003-Picloram, Worksheet F03). This estimated 

dose is 0.03 of the acute NOAEL, so there is no basis for asserting or predicting that adverse 

effects to herbivorous mammals are plausible (SERA, 2003-Picloram, p. 4-29). 

The chronic NOAEL for mammals in laboratory toxicity tests is 7 mg/kg/day. If a small mammal 

consumes contaminated vegetation at the treatment site for 90-days, assuming highest residue 

rates, the animal would receive a chronic dose of 0.024 mg/kg/day (SERA, 2003-Picloram, 

Worksheet F04a). This estimated dose is 0.003 of the chronic NOAEL, so there is no basis for 

asserting or predicting that adverse effects to small herbivorous mammals are plausible (SERA, 

2003-Picloram, p. 4-29). 

Estimated doses using the highest application rate (1 lb/acre) are less than the acute and chronic 

NOAELs for mammals, so there is no basis for asserting or predicting that adverse effects are 

plausible using typical or worst-case exposure assumptions. 

Small Insectivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 34 mg/kg. For exposure scenarios 

that use the typical application rate of 0.35 lb/acre, if a small mammal consumes contaminated 

insects shortly after application, assuming the highest residue rates, the acute dose received is 

24.3 mg/kg (SERA, 2003-Picloram, Worksheet 14a). This dose is 0.714 of the acute NOAEL, so 

there is no basis for asserting or predicting that adverse effects to insectivorous mammals are 

plausible (SERA, 2003-Picloram, p. 4-29). 

Data on degradation of herbicide residues from insects is not available, so no chronic exposure 

scenario has been developed. Residue on insects likely declines over time, but the extent of 

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Appendix C-Wildlife 

decline has not been quantified. The acute dose is greater than the chronic NOAEL (7 mg/kg), 

and near the chronic LOAEL (35 mg/kg/day) for increased liver weight. So adverse effects to 

insectivorous mammals appear plausible from chronic dietary exposures. The exposure scenario 

uses residue rates from small insects, which are substantially higher than those for large insects, 

and assumes that 100 percent of the daily diet is composed of insects that have been directly 

sprayed. For bats, in particular, the scenario is unlikely to occur in the field. It seems more 

plausible for shrews and small fossorial insectivores, however. 

The estimated dose (69.4 mg/kg) using the highest application rate (1 lb/acre) is greater than the 

acute and chronic NOAELs for mammals. It is less than the acute LOAEL for decreased weight 

gain, but is almost twice the chronic LOAEL for increased liver weight. So adverse effects to 

insectivorous mammals appear plausible from acute or chronic dietary exposures. 

Large Herbivorous Bird 

The acute NOAEL for birds in laboratory toxicity tests is 1500 mg/kg. For exposure scenarios 

that use the typical application rate of 0.35 lb/acre, if a 4 kg bird consumed contaminated grass on 

site shortly after application, assuming the highest residue rates and 100 percent of diet is 

contaminated, it would receive an acute dose of 26.6 mg/kg (SERA, 2003-Name, Worksheet 

F12). This dose is 0.02 of the acute NOAEL, so there is no basis for asserting or predicting that 

adverse effects to large grass-eating birds are plausible (SERA, 2003-Picloram, p. 4-29). 

There is no chronic toxicity index available for effects of picloram to birds, so the mammal 

chronic NOAEL will be used. Since the acute NOAEL for birds is greater than the acute NOAEL 

for mammals, the use of the chronic figure from mammals is likely to over-estimate risk to birds. 

The chronic NOAEL for mammals in laboratory toxicity tests is 7 mg/kg/day. Chronic exposure 

from the consumption of contaminated grass for 90 days at the treatment site, assuming the 

highest residue rates and 100 percent of diet is contaminated, results in a dose of 3.41 mg/kg/day 

(SERA, 2003-Picloram, Worksheet F13a). This estimated dose is 0.5 of the chronic NOAEL, so 

there is no/ basis for asserting or predicting that adverse effects to large grass-eating birds are 

plausible (SERA, 2003-Picloram, p. 4-29). 

Estimated doses using the highest application rate (1 lb/acre) are less than the acute NOAEL for 

birds, but greater than the chronic NOAEL for mammals. The chronic dose is less than the 

chronic LOAEL for mammals. No adverse effects are plausible from acute exposures, but adverse 

effects to large herbivorous birds appear plausible from chronic dietary exposures, based on dose 

exceeding the NOAEL. Since picloram does not kill grass, herbicide residues on grass may be 

more available for chronic ingestion than non-selective herbicides. 

Large Fish-eating Bird 

Many chemicals may be concentrated or partitioned from water into the tissues of animals in the 

water. This process is referred to as bioconcentration. The potential for bioconcentration of 

picloram in fish was studied in bluegill and channel catfish exposed to 

14

C-picloram for 28 days 

(Bidlack 1980a,b cited in SERA, 2003-Picloram). Only trace amounts of 

14

C-picloram were 

recovered in the fish, so the BCF for picloram appears to be substantially less than one (SERA 

2003 Picloram). The exposure scenarios in the SERA risk assessment use a whole-fish BCF of 1 

L/kg for acute and chronic exposures, which will over-estimate exposure. 

The acute NOAEL for birds in laboratory toxicity tests is 1500 mg/kg. For exposure scenarios 

that use the typical application rate of 0.35 lb/acre, if a predatory bird consumed fish from a pond 

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Appendix C-Wildlife 

contaminated by an accidental spill, assuming the highest concentrations in fish and highest 

intake on a body weight basis, it would receive an acute dose of 0.908 mg/kg (SERA, 2003-

Picloram, Worksheet F08). This dose is 0.0006 of the acute NOAEL, so there is no basis for 

asserting or predicting that adverse effects to fish-eating birds are plausible (SERA, 2003-

Picloram, p. 4-29). 

There is no chronic toxicity index available for effects of picloram to birds, so the mammal 

chronic NOAEL will be used. Since the acute NOAEL for birds is greater than the acute NOAEL 

for mammals, the use of the chronic figure from mammals is likely to over-estimate risk to birds. 

The chronic NOAEL for mammals in laboratory toxicity tests is 7 mg/kg/day. If a predatory bird 

consumed fish contaminated by runoff for a lifetime, assuming the highest concentrations in fish 

and highest intake on a body weight basis, it would receive a chronic dose of 0.000214 mg/kg/day 

(SERA, 2003-Picloram, Worksheet F09). This estimated dose is 0.00003 of the chronic NOAEL, 

so there is no basis for asserting/predicting that adverse effects to fish-eating birds are plausible 

(SERA, 2003-Picloram, p. 4-29). 

Estimated doses using the highest application rate (1 lb/acre) are less than the acute NOAEL for 

birds and chronic NOAEL for mammals, so there is no basis for asserting or predicting that 

adverse effects are plausible using typical or worst-case exposure assumptions. 

Large Predatory Bird 

The acute NOAEL for birds in laboratory toxicity tests is 1500 mg/kg. For exposure scenarios 

that use the typical application rate of 0.35 lb/acre, if a 0.6 kg bird consumed small mammal prey 

that has been contaminated by direct spray, assuming 100 percent absorption for the prey, it 

would receive an acute dose of 1.13 mg/kg (SERA 2003 Picloram, Worksheet F16b). This is 

0.000754 of the acute NOAEL, so there is no basis for asserting or predicting that adverse effects 

to predatory birds are plausible (SERA, 2003-Picloram, p. 4-29). 

Picloram does not appear to accumulate or persist in animals. The elimination of picloram has 

been studied in humans, rats, dogs, and cattle (SERA, 2003-Picloram). In humans, over 75 

percent of the administered picloram was eliminated after six hours and over 90 percent was 

eliminated after 72 hours (SERA, 2003-Picloram citing Nolan et al. 1984). Therefore, chronic 

exposures from contaminated mammal prey due to a single application of picloram are unlikely to 

cause any adverse effect. In addition, the acute dose is less than the chronic NOAEL for 

mammals, so there is no basis for asserting or predicting that adverse effects from repeated acute 

exposures from multiple applications of picloram over time are plausible. 

The estimated dose using the highest application rate (1 lb/acre) is less than the acute NOAEL for 

birds and chronic NOAEL mammals, so there is no basis for asserting or predicting that adverse 

effects are plausible using typical or worst-case exposure assumptions. 

Small Insectivorous Bird 

The acute NOAEL for birds in laboratory toxicity tests is 1500 mg/kg. For exposure scenarios 

that use the typical application rate of 0.35 lb/acre, if a 10 g bird consumed contaminated insects 

on site shortly after application, assuming the highest residue rates, it would receive an acute dose 

of 39.5 mg/kg (SERA, 2003-Picloram, Worksheet F14b). This dose is 0.03 of the acute NOAEL, 

so there is no basis for asserting or predicting that adverse effects to insectivorous birds are 

plausible (SERA, 2003-Picloram, p. 4-29). 

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Appendix C-Wildlife 

Data on degradation of herbicide residues from insects is not available, so no chronic exposure 

scenario has been developed. Residue on insects likely declines over time, but the extent of 

decline has not been quantified. However, the acute dose is greater than the chronic NOAEL for 

mammals, so adverse effects to insectivorous birds appear plausible from chronic dietary 

exposures. 

The estimated dose using the highest application rate (1 lb/acre) is less than the acute NOAEL for 

birds, but greater than the chronic NOAEL for mammals. The acute dose (113 mg/kg) is also 

greater than the chronic LOAEL for mammals (35 mg/kg/day), so adverse effects to insectivorous 

birds appear plausible from chronic dietary exposures. 

SETHOXYDIM 

Small Mammal Directly Sprayed 

The acute NOAEL for mammals in laboratory toxicity tests is 160 mg/kg. For, exposure scenarios 

that use the typical application rate of 0.30 lb/acre, if a small mammal is directly sprayed, and 100 

percent absorption is assumed, the animal would receive an acute dose of 

7.27 mg/kg (Project file, Sethoxdim Worksheet F02a). This estimated dose is 0.05 and 0.005 of 

the acute NOAEL, so there is no basis for asserting or predicting that adverse effects to 

herbivorous mammals are plausible (SERA 2001 Sethoxydim, p. 4-19). 

Small Mammal Drinking Contaminated Water 

The estimated doses to a small mammal from drinking water contaminated by an accidental spill, 

assuming the highest levels of contamination, are 0.997 mg/kg for acute exposure (Project file, 

Sethoxdim Worksheet F05). If a small mammal consumes contaminated water over time, 

accounting for dissipation, degradation, and other processes, the animal would receive a chronic 

dose of 0.0000527 mg/kg/day (Project file, Sethoxdim Worksheet F07). Doses to a large mammal 

would be even lower on a per kg body weight basis. These doses are 0.006 of the acute NOAEL, 

and 0.000006 of the chronic NOAEL, respectively, so there is no basis for asserting or predicting 

that adverse effects to mammals are plausible (SERA 2001 Sethoxydim, p. 4-19). 

At the highest application rate of 0.375 lb/acre, the acute dose from drinking water contaminated 

by a spill is 0.997 mg/kg (project file). This dose is 0.006 of the acute NOAEL. The chronic dose 

is also below the chronic NOAEL, so there is no basis for asserting or predicting that adverse 

effects to mammals are plausible, even in a worst-case scenario. 

Large Herbivorous Mammal 79 

The acute NOAEL for mammals in laboratory toxicity tests is 160 mg/kg. For exposure scenarios 

that use the typical application rate of 0.30 lb/acre, if a 70 kg mammal consumed contaminated 

vegetation on site shortly after application, assuming the highest residue rates and 100 percent of 

the diet contaminated, it would receive an acute dose of 14.6 mg/kg (Project file, Sethoxdim 

Worksheet F10). This dose is 0.09 of the acute NOAEL, so there is no basis for asserting or 

predicting that adverse effects to large grass-eating mammals are plausible (SERA, 2001-

Sethoxydim, p. 4-19). 

The chronic NOAEL for mammals in laboratory toxicity tests is 9 mg/kg/day. Chronic exposure 

from the consumption of contaminated vegetation for 90 days at the treatment site, assuming the 

highest residue rates, results in a dose of 0.701 mg/kg/day (Project file, Sethoxdim Worksheet 

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Appendix C-Wildlife 

F11a). This dose is 0.08 of the chronic NOAEL, so there is no basis for asserting or predicting 

that adverse effects to large grass-eating mammals are plausible (SERA, 2001-Sethoxydim, p. 4-

19). 

Estimated doses using the highest application rate (0.375 lb/acre) are less the acute and chronic 

NOAELs for mammals, so there is no basis for asserting or predicting that adverse effects are 

plausible using typical or worst-case exposure assumptions (SERA 2001 Sethoxydim, p. 4-19). 

Medium Carnivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 160 mg/kg. For exposure scenarios 

that use the typical application rate of 0.30 lb/acre, if a 5 kg mammal consumed small mammal 

prey that has been contaminated by direct spray, assuming 100 percent absorption for the prey, it 

would receive an acute dose of 0.629 mg/kg (Project file, 

Sethoxdim Worksheet F16a). Doses to a large mammal would be even lower on per kg body 

weight basis. This dose is 0.004 of the acute NOAEL, so there is no basis for asserting or 

predicting that adverse effects to carnivorous mammals are plausible (SERA 2001 Sethoxydim, p. 

4-19). 

There is no information in the risk assessment (SERA 2001 Sethoxydim) on accumulation or 

elimination of sethoxydim in mammals. Therefore, the potential for chronic exposures from 

contaminated mammal prey due to a single application of sethoxydim cannot be deduced. 

However, the acute dose is less than the chronic NOAEL for mammals, so there is no basis for 

asserting or predicting that adverse effects from repeated acute exposures from multiple 

applications of sethoxydim over time are plausible. 

Estimated doses using the highest application rate (0.375 lb/acre) are less than the acute and 

chronic NOAELs for mammals, so there is no basis for asserting or predicting that adverse effects 

are plausible using typical or worst-case exposure assumptions. 

Small Herbivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 160 mg/kg. If a small mammal 

consumes contaminated vegetation shortly after application, assuming the highest residue rates, 

the acute dose received is 0.804 mg/kg (Project file, Sethoxdim Worksheet F03). This estimated 

dose is 0.005 of the acute NOAEL, so there is no basis for asserting or predicting that adverse 

effects to herbivorous mammals are plausible (SERA, 2001-Sethoxydim, p. 4-19). 

The chronic NOAEL for mammals in laboratory toxicity tests is 9 mg/kg/day. If a small mammal 

consumes contaminated vegetation at the treatment site for 90-days, assuming highest residue 

rates, the animal would receive a chronic dose of 0.00773 mg/kg/day (Project file, Sethoxdim 

Worksheet F04a). This estimated dose is 0.0009 of the chronic NOAEL, so there is no basis for 

asserting or predicting that adverse effects to herbivorous mammals are plausible (SERA, 2001-

Sethoxydim, p. 4-19). 

Estimated doses using the highest application rate (0.375 lb/acre) are less than the acute and 

chronic NOAELs for mammals, so there is no basis for asserting or predicting that adverse effects 

are plausible using typical or worst-case exposure assumptions (SERA, 2001-Sethoxydim, p. 4-

19). 

Small Insectivorous Mammal 

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Appendix C-Wildlife 

The acute NOAEL for mammals in laboratory toxicity tests is 160 mg/kg. For exposure scenarios 

that use the typical application rate of 0.30 lb/acre, if a small mammal consumes contaminated 

insects shortly after application, assuming the highest residue rates, the acute dose received is 

20.8 mg/kg (Project file, Sethoxdim Worksheet 14a). This dose is 0.10 of the acute NOAEL, so 

there is no basis for asserting or predicting that adverse effects to insectivorous mammals are 

plausible. 

Data on degradation of herbicide residues from insects is not available, so no chronic exposure 

scenario has been developed. Residue on insects likely declines over time, but the extent of 

decline has not been quantified. However, the acute dose is greater than the chronic NOAEL and 

the chronic LOAEL (18 mg/kg/day) for mild anemia. So adverse effects to insectivorous 

mammals appear plausible from chronic dietary exposures. The exposure scenario uses residue 

rates from small insects, which are substantially higher than those for large insects, and assumes 

that 100 percent of the daily diet is composed of insects that have been directly sprayed. For bats, 

in particular, the scenario is unlikely to occur in the field. It seems more plausible for shrews and 

small fossorial insectivores, however. 

The estimated dose using the highest application rate (0.375 lb/acre) is less than the acute 

NOAEL, but greater than the chronic NOAEL for mammals, so adverse effects to insectivorous 

mammals are plausible from chronic dietary exposures. 

Large Herbivorous Bird 

The acute NOAEL for birds in laboratory toxicity tests is 500 mg/kg. For exposure scenarios that 

use the typical application rate of 0.30 lb/acre, if a 4 kg bird consumed contaminated grass on site 

shortly after application, assuming the highest residue rates and 100 percent of diet is 

contaminated, it would receive an acute dose of 22.8 mg/kg (Project file, Sethoxdim Worksheet 

F12). This dose is 0.05 of the acute NOAEL, so there is no basis for asserting or predicting that 

adverse effects to large grass-eating birds are plausible (SERA, 2001-Sethoxydim, p. 4-19). 

The chronic LOAEL for birds in laboratory toxicity tests is 10 mg/kg/day. Chronic exposure from 

the consumption of contaminated grass for 90 days at the treatment site, assuming the highest 

residue rates and 100 percent of diet is contaminated, results in a dose of 1.10 mg/kg/day (Project 

file, Sethoxdim Worksheet F13a). This estimated dose is 0.1 of the chronic LOAEL. If we apply 

the standard EPA conversion for extrapolating from a LOAEL to a NOAEL, the NOAEL becomes 

1 mg/kg, and the dose is equal to the chronic NOAEL. At this dose, adverse reproductive effects 

to large grass-eating birds are not likely. 

Estimated doses using the highest application rate (0.375 lb/acre) are less than the acute NOAEL 

and chronic LOAEL. But the estimated dose is greater than the extrapolated chronic NOAEL for 

birds, so adverse effects to grass-eating birds is plausible from chronic dietary exposures at the 

highest application rate. 

Large Fish-eating Bird 

Many chemicals may be concentrated or partitioned from water into the tissues of animals in the 

water. This process is referred to as bioconcentration. The potential for bioconcentration of 

sethoxydim in fish was studied in bluegill and catfish. Bioconcentration factors (BCF) for catfish 

were 0.71 L/kg in muscle and 0.75 L/kg in whole fish (SERA, 2001-Sethoxydim, Appendix 3). 

BCF for bluegill sunfish were substantially higher, measuring 7 L/kg in muscle and 21 L/kg in 

whole fish (SERA, 2001-Sethoxydim, Appendix 3). The BCF for acute exposure is calculated 

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Appendix C-Wildlife 

using the elimination half-life of sethoxydim residue in fish, to adjust for the expected 

bioconcentration after one day (SERA, 2001-Sethoxydim, p. 3-16). The exposure scenarios in the 

SERA risk assessment use a whole-fish BCF of 3.6 L/kg for acute exposure and 21 L/kg for 

chronic exposure. 

The acute NOAEL for birds in laboratory toxicity tests is 500 mg/kg. For exposure scenarios that 

use the typical application rate of 0.30 lb/acre, if a predatory bird consumed fish from a pond 

contaminated by an accidental spill, assuming the highest concentrations in fish and highest 

intake on a body weight basis, it would receive an acute dose of 3.68 mg/kg (Project file, 

Sethoxdim Worksheet F08). This dose is 0.007 of the acute NOAEL, so there is no basis for 

asserting or predicting that adverse effects to fish-eating birds are plausible (SERA, 2001-

Sethoxydim, p. 4-19). 

The chronic LOAEL for birds in laboratory toxicity tests is 10 mg/kg/day. If a predatory bird 

consumed fish contaminated by runoff for a lifetime, assuming the highest concentrations in fish 

and highest intake on a body weight basis, it would receive a chronic dose of 0.00113 mg/kg/day 

(Project file, Sethoxdim Worksheet F09). This estimated dose is 0.0001 of the chronic LOAEL. If 

we apply the standard EPA safety factor for extrapolating from a LOAEL to a NOAEL, the 

NOAEL becomes 1 mg/kg. The dose is 0.001of the chronic NOAEL, so there is no basis for 

asserting/predicting that adverse effects to fish-eating birds are plausible (SERA, 2001-

Sethoxydim, p. 4-19). 

Estimated doses using the highest application rate (0.375 lb/acre) also result in exposures less 

than the acute and extrapolated chronic NOAELs for birds, so there is no basis for asserting or 

predicting that adverse effects are plausible using typical or worst-case exposure assumptions. 

Large Predatory Bird 

The acute NOAEL for birds in laboratory toxicity tests is 500 mg/kg. For exposure scenarios that 

use the typical application rate of 0.30 lb/acre, if a 0.6 kg bird consumed small mammal prey that 

has been contaminated by direct spray, assuming 100 percent absorption for the prey, it would 

receive an acute dose of 0.97 mg/kg (Project file, Sethoxdim Worksheet F16b). This is 0.002 of 

the acute NOAEL, so there is no basis for asserting or predicting that adverse effects to predatory 

birds are plausible. 

There is no information in the risk assessment (SERA, 2001-Sethoxydim) on accumulation or 

elimination of sethoxydim in mammals. Therefore, the potential for chronic exposures from 

contaminated mammal prey due to a single application of sethoxydim cannot be deduced. 

However, the acute dose is less than the chronic LOAEL, and the extrapolated NOAEL, for birds, 

so there is no basis for asserting/predicting that adverse effects from repeated acute exposures 

from multiple applications of sethoxydim over time are plausible. 

The estimated dose using the highest application rate (0.375 lb/acre) is less than the acute 

NOAEL and less than the chronic LOAEL. The dose (1.21 mg/kg) is greater than the extrapolated 

chronic NOAEL for birds. Therefore, adverse effects to predatory birds appear plausible from 

chronic dietary exposures at the highest application rate, base on dose exceeding an extrapolated 

chronic NOAEL. 

Small Insectivorous Bird 

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The acute NOAEL for birds in laboratory toxicity tests is 500 mg/kg. For exposure scenarios that 

use the typical application rate of 0.30 lb/acre, if a 10 g bird consumed contaminated insects on 

site shortly after application, assuming the highest residue rates, it would receive an acute dose of 

33.8 mg/kg (Project file, Sethoxdim Worksheet F14b). This dose is 0.07 of the acute NOAEL, so 

there is no basis for asserting or predicting that adverse effects to insectivorous birds are plausible 

(SERA, 2001-Sethoxydim, p. 4-19). 

Data on degradation of herbicide residues from insects is not available, so no chronic exposure 

scenario has been developed. Residue on insects likely declines over time, but the extent of 

decline has not been quantified. However, the acute dose is 3 times greater than the chronic 

LOAEL for birds, so adverse effects to reproduction of insectivorous birds are expected from 

chronic dietary exposures. The estimated dose using the highest application rate (0.375 lb/acre) is 

less than the acute NOAEL, but 4 times greater than the chronic LOAEL for birds. Therefore, 

adverse effects to reproduction of insectivorous birds are expected from chronic dietary exposures 

at the highest application rate. 

SULFOMETURON METHYL 

Small Mammal Directly Sprayed 

The acute NOAEL for mammals in laboratory toxicity tests is 87 mg/kg. For, exposure scenarios 

that use the typical application rate of 0.045 lb/acre, if a small mammal is directly sprayed, and 

100 percent absorption is assumed, the animal would receive an acute dose of 1.09 mg/kg (SERA 

2003 Sulfometuron methyl, Worksheet F02a). This estimated dose is 0.01 of the acute NOAEL, 

so there is no basis for asserting or predicting that adverse effects to mammals are plausible 

(SERA, 2003-Sulfometuron methyl, p. 4-30). 

At the highest application rate of 0.38 lb/acre, the animal would receive an acute dose of 9.21 

mg/kg (project file). This dose is 0.1 of the acute NOAEL, so there is no basis for asserting or 

predicting that adverse effects to mammals are plausible at any application rate. 

Small Mammal Drinking Contaminated Water 

The estimated doses to a small mammal from drinking water contaminated by an accidental spill, 

assuming the highest levels of contamination, are 0.122 mg/kg for acute exposure (SERA 2003 

Sulfometuron methyl, Worksheet F05). If a small mammal consumes contaminated water over 

time, accounting for dissipation, degradation, and other processes, the animal would receive a 

chronic dose of 0.461 mg/kg/day (SERA 2003 Sulfometuron methyl, Worksheet F07). Doses to a 

large mammal would be even lower on a per kg body weight basis. These doses are 0.001 of the 

acute NOAEL, and 0.0000002 of the chronic NOAEL, respectively, so there is no basis for 

asserting or predicting that adverse effects to mammals are plausible (SERA 2003 Sulfometuron 

methyl, p. 4-30 and 4-31). 

At the highest application rate of 0.38 lb/acre, the acute dose from drinking water contaminated 

by a spill is 1.03 mg/kg (project file). This dose is 0.01 of the acute NOAEL. The chronic dose is 

also below the chronic NOAEL, so there is no basis for asserting or predicting that adverse 

effects to mammals are plausible, even in a worst-case scenario. 

Large Herbivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 87 mg/kg. For exposure scenarios 

that use the typical application rate of 0.045 lb/acre, if a 70 kg mammal consumed contaminated 

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Appendix C-Wildlife 

vegetation on site shortly after application, assuming the highest residue rates and 100 percents of 

the diet contaminated, it would receive an acute dose of 2.19 mg/kg (SERA, 2003-Sulfometuron 

methyl, Worksheet F10). This dose is 0.03 of the acute NOAEL, so there is no basis for asserting 

or predicting that adverse effects to large grass-eating mammals are plausible (SERA, 2003-

Sulfometuron methyl, p. 4-30). 

The chronic NOAEL for mammals in laboratory toxicity tests is 2 mg/kg/day. Chronic exposure 

from the consumption of contaminated vegetation for 90 days at the treatment site, assuming the 

highest residue rates, results in a dose of 0.35 mg/kg/day (SERA, 2003-Sulfometuron methyl, 

Worksheet F11a). This dose is 0.2 of the chronic NOAEL, so there is no basis for asserting or 

predicting that adverse effects to large grass-eating mammals are plausible (SERA, 2003-

Sulfometuron methyl, p. 4-30). 

Estimated doses using the highest application rate (0.38 lb/acre) are less than the acute NOAEL, 

but greater than the chronic NOAEL for mammals. The chronic dose (2.95 mg/kg) is less than the 

chronic LOAEL (20 mg/kg/day) for effects to blood and bile ducts. No adverse effects are 

plausible from acute exposures, but adverse effects to large herbivorous mammals appear 

plausible from chronic dietary exposures, based on dose exceeding the chronic NOAEL. 

However, the assumptions in the chronic exposure scenario are very unlikely to occur in field 

conditions, so the weight of evidence suggests that no adverse effects are plausible using typical 

or worst-case exposure assumptions (SERA 2003 Sulfometuron methyl, p. 4-31). 

Medium Carnivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 87 mg/kg. For exposure scenarios 

that use the typical application rate of 0.045 lb/acre, if a 5 kg mammal consumed small mammal 

prey that has been contaminated by direct spray, assuming 100 percent absorption for the prey, it 

would receive an acute dose of 0.0944 mg/kg (SERA, 2003 Sulfometuron methyl, Worksheet 

F16a). Doses to a larger mammal would be even lower on a per kg body weight basis. This dose 

is 0.001 of the acute NOAEL, so there is no basis for asserting or predicting that adverse effects 

to carnivorous mammals are plausible SERA, 2003 -ulfometuron methyl, p. 4-30. 

Sulfometuron methyl is eliminated fairly rapidly and does not appear to accumulate in animal 

tissues (SERA, 2003-Sulfometuron methyl). The metabolism of sulfometuron methyl has been 

studied in lactating goats and rats. Goats eliminated 94-99 percent in the urine (Keoppe and 

Mucha, 1991 cited in SERA, 2003-Sulfometuron methyl). The half-life for metabolism in rats is 

28 hours after a gavage dose of 16 mg/kg and 40 hours after a dose of 3000 mg/kg (DuPont, 1989 

cited in SERA, 2003-Sulfometuron methyl). Therefore, chronic exposures from contaminated 

mammal prey due to a single application of sulfometuron methyl are unlikely to cause any 

adverse effect. In addition, the acute dose is much less than the chronic NOAEL for mammals, so 

there is no basis for asserting or predicting that adverse effects from repeated acute exposures 

from multiple applications of sulfometuron methyl over time are plausible. 

The estimated dose using the highest application rate (0.38 lb/acre) is less than the acute and 

chronic NOAELs for mammals, so there is no basis for asserting or predicting that adverse effects 

are plausible using typical or worst-case exposure assumptions. 

Small Herbivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 87 mg/kg. If a small mammal 

consumes contaminated vegetation shortly after application, assuming the highest residue rates, 

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the acute dose received is 0.121 mg/kg (SERA, 2003-Sulfometuron methyl, Worksheet F03). This 

estimated dose is 0.001 of the acute NOAEL, so there is no basis for asserting or predicting that 

adverse effects to herbivorous mammals are plausible (SERA, 2003-Sulfometuron methyl, p. 4-

30). 

The chronic NOAEL for mammals in laboratory toxicity tests is 2 mg/kg/day. If a small mammal 

consumes contaminated vegetation at the treatment site for 90-days, assuming highest residue 

rates, the animal would receive a chronic dose of 0.00386 mg/kg/day (SERA, 2003-Sulfometuron 

methyl, Worksheet F04a). This estimated dose is 0.002 of the chronic NOAEL, so there is no 

basis for asserting or predicting that adverse effects to herbivorous mammals are plausible 

(SERA, 2003-Sulfometuron methyl, p. 4-31). 

Estimated doses using the highest application rate (0.38 lb/acre) are less than the acute and 

chronic NOAELs for mammals, so there is no basis for asserting or predicting that adverse effects 

are plausible using typical or worst-case exposure assumptions. 

Small Insectivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 87 mg/kg. For exposure scenarios 

that use the typical application rate of 0.045 lb/acre, if a small mammal consumes contaminated 

insects shortly after application, assuming the highest residue rates, the acute dose received is 

3.12 mg/kg (SERA, 2003-Sulfometuron methyl, Worksheet 14a). This dose is 0.04 of the acute 

NOAEL, so there is no basis for asserting or predicting that adverse effects to mammal 

insectivores are plausible (SERA, 2003-Sulfometuron methyl, p. 4-30). 

Data on degradation of herbicide residues from insects is not available, so no chronic exposure 

scenario has been developed. Residue on insects likely declines over time, but the extent of 

decline has not been quantified. The acute dose is greater than the chronic NOAEL (2 

mg/kg/day), but less than the chronic LOAEL (20 mg/kg/day) for effects to blood and bile ducts. 

So adverse effects to insectivorous mammals appear plausible from chronic dietary exposures, 

based on dose exceeding the chronic NOAEL. The exposure scenario uses residue rates from 

small insects, which are substantially higher than those for large insects, and assumes that 100 

percent of the daily diet is composed of insects that have been directly sprayed. For bats, in 

particular, the scenario is unlikely to occur in the field. It seems more plausible for shrews and 

small fossorial insectivores, however. 

The estimated dose (26.4 mg/kg) using the highest application rate (0.38 lb/acre) is less than the 

acute NOAEL. But the acute dose is greater than the chronic NOAEL and the chronic LOAEL 

(20 mg/kg/day) for effects to blood and bile ducts. No adverse effects are plausible from acute 

exposures, but adverse effects to insectivorous mammals are plausible, and may be expected, 

from chronic dietary exposures at the maximum application rate. 

Large Herbivorous Bird 

The acute NOAEL for birds in laboratory toxicity tests is 312 mg/kg. For exposure scenarios that 

use the typical application rate of 0.045 lb/acre, if a 4 kg bird consumed contaminated grass on 

site shortly after application, assuming the highest residue rates and 100 percent of diet is 

contaminated, it would receive an acute dose of 3.42 mg/kg (SERA, 2003-Sulfometuron methyl, 

Worksheet F12). This dose is 0.01 of the acute NOAEL, so there is no basis for asserting or 

predicting that adverse effects to large grass-eating birds are plausible (SERA, 2003-

Sulfometuron methyl, p. 4-30). 

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There is no chronic toxicity index available for effects of sulfometuron methyl to birds, so the 

mammal chronic NOAEL will be used (acute toxicities of sulfometuron methyl to mammals and 

birds are of similar magnitude (SERA 2003 Sulfometuron methyl, p. 4-24)). The chronic NOAEL 

for mammals in laboratory toxicity tests is 2 mg/kg/day. Chronic exposure from the consumption 

of contaminated grass for 90 days at the treatment site, assuming the highest residue rates and 100 

percent of diet is contaminated, results in a dose of 0.547 mg/kg/day (SERA, 2003-Sulfometuron 

methyl, Worksheet F13a). This estimated dose is 0.3 of the chronic NOAEL for mammals, so 

there is no basis for asserting or predicting that adverse effects to large grass-eating birds are 

plausible (SERA, 2003-Sulfometuron methyl, p. 4-31). 

Estimated doses using the highest application rate (0.38 lb/acre) are less than the acute NOAEL 

for birds, but greater than the chronic NOAEL for mammals. The chronic dose (4.62 mg/kg/day) 

is less than the chronic LOAEL for mammals. No adverse effects are plausible from acute 

exposures, but adverse effects to large herbivorous birds appear plausible from chronic dietary 

exposures, based on dose exceeding a NOAEL. However, the assumptions in the chronic 

exposure scenario are very unlikely to occur in field conditions, so the weight of evidence 

suggests that no adverse effects are plausible using typical or worst-case exposure assumptions 

(SERA, 2003-Sulfometuron methyl, p. 4-31). 

Large Fish-eating Bird 

Many chemicals may be concentrated or partitioned from water into the tissues of animals in the 

water. This process is referred to as bioconcentration. The potential for bioconcentration of 

sulfometuron methyl in fish was studied in bluegill sunfish and channel catfish exposed to 

14

Csulformeturon methyl for 28 days (Harvey, 1981, cited in SERA, 2003-Sulfometuron methyl, p. 

3-21). In the SERA risk assessments, concentrations in viscera are considered to reflect 

concentration in whole fish. No bioaccumulation occurred in either muscle or viscera of bluegill. 

Bioconcentration Factors (BCF) for viscera of channel catfish after one day of exposure was 3.5 

L/kg, and 6 L/kg after 28 days (SERA, 2003-Sulfometuron methyl, Appendix 2). Therefore, 

exposure scenarios in the SERA risk assessment use a whole-fish BCF of 3.5 L/kg for acute 

exposure and 6 L/kg for chronic exposure. 

The acute NOAEL for birds in laboratory toxicity tests is 312 mg/kg. For exposure scenarios that 

use the typical application rate of 0.045 lb/acre, if a predatory bird consumed fish from a pond 

contaminated by an accidental spill, assuming the highest concentrations in fish and highest 

intake on a body weight basis, it would receive an acute dose of 0.437 mg/kg (SERA, 200X, 

Worksheet F08). This dose is 0.001 of the acute NOAEL, so there is no basis for asserting or 

predicting that adverse effects to fish-eating birds are plausible (SERA, 2003-Sulfometuron 

methyl, p. 4-30). 

There is no chronic toxicity index available for effects of sulfometuron methyl to birds, so the 

mammal chronic NOAEL will be used (acute toxicities of sulfometuron methyl to mammals and 

birds are of similar magnitude (SERA, 2003-Sulfometuron methyl, p. 4-24)). 

The chronic NOAEL for mammals in laboratory toxicity tests is 2 mg/kg/day. If a predatory bird 

consumed fish contaminated by runoff for a lifetime, assuming the highest concentrations in fish 

and highest intake on a body weight basis, it would receive a chronic dose of 0.000003 mg/kg/day 

(SERA, 200X-Worksheet F09). This estimated dose is 0.000001 of the chronic NOAEL for 

mammals, so there is no basis for asserting or predicting that adverse effects to fish-eating birds 

are plausible (SERA 2003 Sulfometuron methyl, p. 4-31). 

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Estimated doses using the highest application rate (0.38 lb/acre) also result in exposures much 

less than the acute NOAEL for bird and chronic NOAEL for mammals, so there is no basis for 

asserting or predicting that adverse effects are plausible using typical or worst-case exposure 

assumptions (SERA, 2003-Sulfometuron methyl, p. 4-31). 

Large Predatory Bird 

The acute NOAEL for birds in laboratory toxicity tests is 312 mg/kg. For exposure scenarios that 

use the typical application rate of 0.045 lb/acre, if a 0.6 kg bird consumed small mammal prey 

that has been contaminated by direct spray, assuming 100 percent absorption for the prey, it 

would receive an acute dose of 0.145 mg/kg (SERA, 2003-Sulfometuron methyl, Worksheet 

F16b). This is 0.0005 of the acute NOAEL, so there is no basis for asserting or predicting that 

adverse effects to predatory birds are plausible. 

Sulfometuron methyl does not appear to accumulate in animal tissues. The elimination of this 

herbicide has been studied in lactating goats and rats (SERA, 2003-Sulfometuron methyl). Goats 

eliminated 94-99 percent in the urine (Keoppe and Mucha 1991 cited in SERA, 2003-

Sulfometuron methyl). The half-life for metabolism in rats is 28 hours after a gavage dose of 16 

mg/kg and 40 hours after a dose of 3000 mg/kg (DuPont, 1989 cited in SERA, 2003-

Sulfometuron methyl). Therefore, chronic exposures from contaminated mammal prey due to a 

single application of sulfometuron methyl are unlikely to cause any adverse effect. In addition, 

the acute dose is less than the chronic NOAEL for mammals, so there is no basis for 

asserting/predicting that adverse effects from repeated acute exposures from multiple applications 

of sulfometuron methyl over time are plausible. 

Estimated doses using the highest application rate (0.38 lb/acre) are less than the acute NOAEL 

for birds and chronic NOAEL for mammals, so there is no basis for asserting or predicting that 

adverse effects are plausible using typical or worst-case exposure assumptions (SERA, 2003-

Sulfometuron methyl, p. 4-30 and 4-31). 

Small Insectivorous Bird 

The acute NOAEL for birds in laboratory toxicity tests is 312 mg/kg. For exposure scenarios that 

use the typical application rate of 0.045 lb/acre, if a 10 g bird consumed contaminated insects on 

site shortly after application, assuming the highest residue rates, it would receive an acute dose of 

5.08 mg/kg (SERA, 2003-Sulfometuron methyl, Worksheet F14b). This dose is 0.02 of the acute 

NOAEL, so there is no basis for asserting or predicting that adverse effects to insectivorous birds 

are plausible (SERA, 2003-Sulfometuron methyl, p. 4-30). 

There is no chronic toxicity index available for effects of sulfometuron methyl to birds, so the 

mammal chronic NOAEL will be used (acute toxicities of sulfometuron methyl to mammals and 

birds are of similar magnitude (SERA, 2003-Sulfometuron methyl, p. 4-24)). Data on degradation 

of herbicide residues from insects is not available, so no chronic exposure scenario has been 

developed. Residue on insects likely declines over time, but the extent of decline has not been 

quantified. The acute dose is greater than the chronic NOAEL for mammals (2 mg/kg/day), but 

less than the chronic LOAEL (20 mg/kg/day) for mammals. So adverse effects to insectivorous 

birds appear plausible from chronic dietary exposures, based on an acute dose exceeding a 

chronic NOAEL. 

The estimated dose using the highest application rate (0.38 lb/acre) is less than the acute NOAEL 

for birds, but greater than the chronic NOAEL for mammals. The acute dose (42.9 mg/kg/day) is 

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Appendix C-Wildlife 

also two times greater than the chronic mammal LOAEL for effects to blood and bile ducts. No 

adverse effects are plausible from acute exposures, but adverse effects to insectivorous birds are 

plausible, and may be expected, from chronic dietary exposures at the maximum application rate. 

TRICLOPYR 89 

Toxicity indices and doses are the same for triclopyr acid and triclopyr BEE for mammals, but 

they differ for birds. The EPA has used two different values for a reference dose on the effects of 

triclopyr to mammals. The FS/SERA risk assessment (2003 Triclopyr) relies on a chronic toxicity 

index (NOEL of 5 mg/kg/day) from a rat reproduction study. In this analysis, we will use a lower 

value from a 1-year feeding study of dogs (chronic NOEL of 0.5 mg/kg/day; Quast et al. 1976, 

cited in SERA, 2003-Triclopyr). Dogs were not considered by EPA to be a good model for human 

health effects, because they do not excrete weak acids as well as other animals (see Timchalk and 

Nolan 1997; Timchalk et al. 1997). Canids are, however, relevant for concerns about effects to 

wildlife. It may be argued that the use of the 0.5 mg/kg/day value for the toxicity index in this 

analysis is overly cautious, because it represents competition for excretion rather than a toxic 

effect (Timchalk et al. 1997), and because it is being applied to other animals besides canids. 

However, it meets the criteria for providing a data-based worst-case analysis for potential effects 

to wildlife, and is therefore consistent with the criteria for choice of other indices used in this 

analysis. 

Small Mammal Directly Sprayed 

The acute NOAEL for mammals in laboratory toxicity tests is 100 mg/kg. For, exposure scenarios 

that use the typical application rate of 1 lb/acre, if a small mammal is directly sprayed, and 100 

percent absorption is assumed, the animal would receive an acute dose of 24.2 mg/kg (SERA, 

2003-Triclopyr, Worksheet F02a). This estimated dose is 0.2 of the acute NOAEL, so there is no 

basis for asserting or predicting that adverse effects to mammals are plausible. 

At the highest application rate of 10 lb/acre, the animal would receive an acute dose of 242 mg/kg 

(project file). This dose is greater than the acute NOAEL but less than the acute LOAEL for 

malformed fetuses, although not substantially. So adverse effects are plausible from direct spray 

at the highest application rate, based on dose exceeding the NOAEL. 

Small Mammal Drinking Contaminated Water 

The estimated doses to a small mammal from drinking water contaminated by an accidental spill, 

assuming the highest levels of contamination, are 2.66 mg/kg for acute exposure (SERA, 2003-

Triclopyr, Worksheet F05). If a small mammal consumes contaminated water over time, 

accounting for dissipation, degradation, and other processes, the animal would receive a chronic 

dose of 0.00732 mg/kg/day (SERA, 2003-Triclopyr, Worksheet F07). Doses to a large mammal 

would be even lower on a per kg body weight basis. These doses are 0.03 of the acute NOAEL, 

and 0.01 of the chronic NOAEL, respectively, so there is no basis for asserting or predicting that 

adverse effects to mammals are plausible. 

At the highest application rate of 10 lb/acre, the acute dose from drinking water contaminated by 

a spill is 26.6 mg/kg (project file). This dose is 0.3 of the acute NOAEL. The chronic dose is also 

below the chronic NOAEL, so there is no basis for asserting or predicting that adverse effects to 

mammals are plausible, even in a worst-case scenario. 

Large Herbivorous Mammal 

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The acute NOAEL for mammals in laboratory toxicity tests is 100 mg/kg. For exposure scenarios 

that use the typical application rate of 1 lb/acre, if a 70 kg mammal consumed contaminated 

vegetation on site shortly after application, assuming the highest residue rates and 100 percents of 

the diet contaminated, it would receive an acute dose of 48.6 mg/kg (SERA, 2003-Triclopyr, 

Worksheet F10). This dose is 0.5 of the acute NOAEL, so there is no basis for asserting or 

predicting that adverse effects to large grass-eating mammals are plausible. 

The chronic NOAEL for mammals in laboratory toxicity tests is 0.5 mg/kg/day. Chronic exposure 

from the consumption of contaminated vegetation for 90 days at the treatment site, assuming the 

highest residue rates, results in a dose of 32.0 mg/kg/day (SERA, 2003-Triclopyr, Worksheet 

F11a). This dose is greater than the chronic NOAEL and 13 times greater than the LOAEL of 2.5 

mg/kg for effects to kidneys. Adverse effects to grass-eating mammals are plausible and of 

substantial concern with the use of triclopyr (SERA, 2003-Triclopyr, p. 4-28). 

Estimated doses using the highest application rate (10 lb/acre) are greater than the acute and 

chronic NOAELs for mammals. The acute dose is 486 mg/kg; which also exceeds the acute 

LOAEL for malformed fetuses. The chronic dose is 320 mg/kg; which exceeds the chronic 

LOAEL for effects to kidneys. Adverse effects to reproduction and internal organs of grass-eating 

mammals are plausible with acute and chronic exposures at the highest application rate. The 

potential for adverse effects are of substantial concern with the use of triclopyr (SERA, 2003-

Triclopyr, p. 4-28). 

Medium Carnivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 100 mg/kg. For exposure scenarios 

that use the typical application rate of 1 lb/acre, if a 5 kg mammal consumed small mammal prey 

that has been contaminated by direct spray, assuming 100 percent absorption for the prey, it 

would receive an acute dose of 2.10 mg/kg (SERA 2003 Triclopyr, Worksheet F16a). Doses to a 

larger mammal would be even lower on a per kg body weight basis. This dose is 0.021 of the 

acute NOAEL, so there is no basis for asserting or predicting that adverse effects to carnivorous 

mammals are plausible. 

Triclopyr acid and triclopyr BEE do not appear to accumulate or persist in animals. The 

elimination of triclopyr has been studied in rats and cattle (SERA 2003 Triclopyr). A study by 

Timchalk et al. (1990) found that the half-life for elimination in rats is 3.6 hours and that virtually 

all the ingested dose of triclopyr is excreted unchanged in the urine, although four minor 

metabolites are formed. In cattle, over 86 percent of the ingested dose was eliminated unchanged 

in the urine and almost all the dose was eliminated after 24 hours (Eckerlin et al. 1987, cited in 

SERA 2003). Therefore, chronic exposures from contaminated mammal prey due to a single 

application of triclopyr are unlikely to cause any adverse effect. However, the acute dose is 

greater than the chronic NOAEL for mammals, but slightly less than the chronic LOAEL, so 

adverse effects to carnivorous mammals appear plausible from chronic dietary exposures. 

The estimated dose using the highest application rate (10 lb/acre) is less than the acute NOAEL, 

but greater than the chronic LOAEL for effects to kidneys of mammals. No adverse effects are 

plausible from acute exposures, but adverse effects to carnivorous mammals appear plausible 

from chronic dietary exposures at the maximum application rate. 

Small Herbivorous Mammal 

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Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

The acute NOAEL for mammals in laboratory toxicity tests is 100 mg/kg. If a small mammal 

consumes contaminated vegetation shortly after application, assuming the highest residue rates, 

the acute dose received is 0.495 mg/kg (SERA, 2003-Triclopyr, Worksheet F03). This estimated 

dose is 0.005 of the acute NOAEL, so there is no basis for asserting or predicting that adverse 

effects to herbivorous mammals are plausible. 

The chronic NOAEL for mammals in laboratory toxicity tests is 0.5 mg/kg/day. If a small 

mammal consumes contaminated vegetation at the treatment site for 90-days, assuming highest 

residue rates, the animal would receive a chronic dose of 0.0652 mg/kg/day (SERA, 2003-

Triclopyr, Worksheet F04a). This estimated dose is 0.1 the chronic NOAEL, so there is no basis 

for asserting or predicting that adverse effects to herbivorous mammals are plausible. 

Estimated doses using the highest application rate (10 lb/acre) are less than the acute NOAEL, but 

slightly greater than the chronic NOAELs for mammals. The chronic dose (0.65 mg/kg/day) is 

less than the chronic LOAEL (2.5 mg/kg/day) for effects to kidneys. No adverse effects are 

plausible from acute exposures, but adverse effects to herbivorous mammals appear plausible 

from chronic dietary exposures at the maximum application rate, based on dose exceeding a 

NOAEL. 

Small Insectivorous Mammal 

The acute NOAEL for mammals in laboratory toxicity tests is 100 mg/kg. For exposure scenarios 

that use the typical application rate of 1 lb/acre, if a small mammal consumes contaminated 

insects shortly after application, assuming the highest residue rates, the acute dose received is 

69.4 mg/kg (SERA, 2003-Triclopyr, Worksheet 14a). This dose is 0.694 of the acute NOAEL, so 

there is no basis for asserting or predicting that adverse effects to insectivorous mammals are 

plausible. 

Data on degradation of herbicide residues from insects is not available, so no chronic exposure 

scenario has been developed. Residue on insects likely declines over time, but the extent of 

decline has not been quantified. However, the acute dose is much greater than the chronic 

LOAEL for mammals, so adverse effects to insectivorous mammals appear plausible from 

chronic dietary exposures. The exposure scenario uses residue rates from small insects, which are 

substantially higher than those for large insects, and assumes that 100 percent of the daily diet is 

composed of insects that have been directly sprayed. For bats, in particular, the scenario is 

unlikely to occur in the field. It seems more plausible for shrews and small fossorial insectivores, 

however. 

The estimated dose (694 mg/kg) using the highest application rate (10 lb/acre) is much greater 

than the acute and chronic NOAELs for mammals. The acute dose is more than two times greater 

than the acute LOAEL for malformed fetuses and more than 200 times greater than the chronic 

LOAEL for effects to kidneys. Therefore, adverse effects to insectivorous mammals may be 

expected if they feed on insects contaminated with triclopyr applied at the highest application 

rate. 

Large Herbivorous Bird 

Triclopyr BEE is slightly more toxic to birds in acute exposures than triclopyr acid. For triclopyr 

acid, the acute LD50 for birds in laboratory toxicity tests is 535 mg/kg and for triclopyr BEE the 

acute LD

50 is 388 mg/kg. For exposure scenarios that use the typical application rate of 1 lb/acre, 

if a 4 kg bird consumed contaminated grass on site shortly after application, assuming the highest 

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Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

residue rates and 100 percent of diet is contaminated, it would receive an acute dose of 76.0 

mg/kg (SERA 2003 Triclopyr, Worksheets F12). This dose is 0.1 of the acute LD50 for triclopyr 

acid and 0.2 of the acute LD

50 for triclopyr BEE. Since the acute exposure scenario for bird is 

based on an LD

50 rather than an acute NOAEL, the FS/SERA risk assessments base the level of 

concern on 0.1 of the LD

50 (SERA, 2003-Triclopyr), a factor used by EPA as a result of data 

analysis and modeling conducted by their Office of Pesticide Programs (Urban and Cook, 1986). 

Therefore, acute exposure from triclopyr acid is equal to the level of concern and that from 

triclopyr BEE is greater than the 

level of concern (SERA 2003 Triclopyr). Adverse effects to grass-eating birds are plausible and of 

substantial concern with the use of triclopyr (SERA, 2003-Triclopyr, p. 4-28). 

The chronic NOAEL for birds in laboratory toxicity tests is 10 mg/kg/day for both triclopyr acid 

and triclopyr BEE. Chronic exposure from the consumption of contaminated grass for 90 days at 

the treatment site, assuming the highest residue rates and 100 percent of diet is contaminated, 

results in a dose of 50.1 mg/kg/day (SERA, 2003-Triclopyr, Worksheets F13a). This estimated 

dose is greater than the chronic NOAEL and more than two times greater than the chronic 

LOAEL for decreased survival of offspring. The assumptions in the chronic exposure scenario are 

unlikely to occur in field conditions, however, adverse effects reproduction of grass-eating birds 

are plausible and of substantial concern with the use of triclopyr (SERA, 2003-Triclopyr, p. 4-28). 

At the highest application rate (10 lb/acre), the acute dose is 760 mg/kg, which is greater than the 

acute LD

50 for birds, for both triclopyr acid and triclopyr BEE. Mortality could be expected for 

birds feeding on vegetation contaminated with triclopyr applied at the highest application rate. In 

the case of the chronic exposures, the estimated dose (501 mg/kg/day) is much greater than the 

chronic LOAEL for decreased survival of offspring. Adverse effects, including mortality and 

decreased reproduction, to grass-eating birds are plausible and of substantial concern with the use 

of triclopyr (SERA, 2003-Triclopyr, p. 4-28). 

Large Fish-eating Bird 

Many chemicals may be concentrated or partitioned from water into the tissues of animals in the 

water. This process is referred to as bioconcentration. The potential for bioconcentration of 

triclopyr in fish was studied in bluegill sunfish exposed to 

14

C-triclopyr (Rick et al., 1996; and 

Lickly and Murphy, 1987; cited in SERA 2003 Triclopyr). Bioconcentration factors (BCF) of 

triclopyr and its metabolites (primarily TCP) for bluegill were 0.83 L/kg for whole fish, which is 

the figure used in the exposure scenarios in the SERA risk assessment for acute and chronic 

exposures. 

Triclopyr BEE is slightly more toxic to birds in acute exposures than triclopyr acid. For triclopyr 

acid, the acute LD50 for birds in laboratory toxicity tests is 535 mg/kg and for triclopyr BEE the 

acute LD

50 is 388 mg/kg. For exposure scenarios that use the typical application rate of 1 lb/acre, 

if a predatory bird consumed fish from a pond contaminated by an accidental spill, assuming the 

highest concentrations in fish and highest intake on a body weight basis, it would receive an acute 

dose of 2.26 mg/kg (SERA, 2003-Triclopyr, Worksheet F08). This dose is 0.004 of the acute LD50 for triclopyr acid, and 0.006 of the acute LD50 for triclopyr BEE. Since the acute exposure 

scenario for bird is based on an LD

50 rather than an acute NOAEL, the FS/SERA risk assessments 

base the level of concern on 0.1 of the LD

50 (SERA, 2003-Triclopyr), a factor used by EPA as a 

result of data analysis and modeling conducted by their Office of Pesticide Programs (Urban and 

Cook 1986). The resultant values are much less than the level of concern, so there is no basis for 

asserting or predicting that adverse effects to fish-eating birds are plausible. 

 C-90 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

The chronic NOAEL for birds in laboratory toxicity tests is 10 mg/kg/day for both triclopyr acid 

and triclopyr BEE. If a predatory bird consumed fish contaminated by runoff for a lifetime, 

assuming the highest concentrations in fish and highest intake on a body weight basis, it would 

receive a chronic dose of 0.00623 mg/kg/day (SERA, 2003-Triclopyr, Worksheet F09). This 

estimated dose is 0.0006 of the chronic NOAEL, so there is no basis for asserting/predicting that 

adverse effects to fish-eating birds are plausible. 

Estimated doses using the highest application rate (10 lb/acre) are less than 0.1 of the acute LD50 and the chronic NOAEL for birds, so there is no basis for asserting or predicting that adverse 

effects are plausible using typical or worst-case exposure assumptions. 

Large Predatory Bird 

Triclopyr BEE is slightly more toxic to birds in acute exposures than triclopyr acid. For triclopyr 

acid, the acute LD50 for birds in laboratory toxicity tests is 535 mg/kg and for triclopyr BEE the 

acute LD

50 is 388 mg/kg. For exposure scenarios that use the typical application rate of 1 lb/acre, 

if a 0.6 kg bird consumed small mammal prey that has been contaminated by direct spray, 

assuming 100 percent absorption for the prey, it would receive an acute dose of 3.23 mg/kg 

(SERA, 2003-Triclopyr, Worksheet F16b). This is 0.00604 of the acute LD50 for triclopyr acid and 

0.00833 of the acute LD

50 for triclopyr BEE. Since the acute exposure scenario for bird is based 

on an LD

50 rather than an acute NOAEL, the FS/SERA risk assessments base the level of concern 

on 0.1 of the LD

50 (SERA, 2003-Triclopyr), a factor used by EPA as a result of data analysis and 

modeling conducted by their Office of Pesticide Programs (Urban and Cook, 1986). The resultant 

values are much less than the level of concern, so there is no basis for asserting or predicting that 

adverse effects to predatory birds are plausible. 

Triclopyr acid and triclopyr BEE do not appear to accumulate or persist in animals. The 

elimination of triclopyr has been studied in rats and cattle (SERA, 2003-Triclopyr). A study by 

Timchalk et al. (1990) found that the half-life for elimination in rats is 3.6 hours and that virtually 

all of the ingested dose of triclopyr is excreted unchanged in the urine, although four minor 

metabolites are formed. In cattle, over 86 percent of the ingested dose was eliminated unchanged 

in the urine and almost all of the dose was eliminated after 24 hours (Eckerlin et al., 1990). 

Therefore, chronic exposures from contaminated mammal prey due to a single application of 

triclopyr are unlikely to cause any adverse effect. In addition, the acute dose is less than the 

chronic NOAEL for birds, so there is no basis for asserting or predicting that adverse effects from 

repeated acute exposures from multiple applications of predatory birds over time are plausible. 

Estimated doses using the highest application rate (10 lb/acre) are less than 0.1 of the LD50 

for 

both triclopyr acid and triclopyr BEE, although only marginally so for triclopyr BEE (acute dose 

of 32.3 vs. 38.8 for 0.1 of the LD

50). The acute dose (32.3 mg/kg) is greater than the bird chronic 

LOAEL (20 mg/kg) for decreased survival of offspring, so adverse affects to predatory birds are 

plausible from triclopyr at the highest application rate. 

Small Insectivorous Bird 

Triclopyr BEE is slightly more toxic to birds in acute exposures than triclopyr acid. For triclopyr 

acid, the acute LD50 for birds in laboratory toxicity tests is 535 mg/kg and for triclopyr BEE the 

acute LD

50 is 388 mg/kg. For exposure scenarios that use the typical application rate of 1 lb/acre, 

if a 10 g bird consumed contaminated insects on site shortly after application, assuming the 

highest residue rates, it would receive an acute dose of 113 mg/kg (SERA 2003 Triclopyr, 

Worksheet F14b). This dose is 0.2 of the acute LD50 for triclopyr acid, and 0.3 of the LD50 

for 

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Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

triclopyr BEE. Since the acute exposure scenario for bird is based on an LD

50 

rather than an acute 

NOAEL, the FS/SERA risk assessments base the level of concern on 0.1 of the LD50 (SERA 2003 

Triclopyr), a factor used by EPA as a result of data analysis and modeling conducted by their 

Office of Pesticide Programs (Urban and Cook 1986). Therefore, the acute dose is two times 

greater than the level of concern for triclopyr acid, and three times greater than the level of 

concern for triclopyr BEE (but less than both LD50s). Adverse effects to insectivorous birds are 

plausible, assuming the highest residue rates. 

Data on degradation of herbicide residues from insects is not available, so no chronic exposure 

scenario has been developed. Residue on insects likely declines over time, but the extent of 

decline has not been quantified. However, the acute dose is five times greater than the chronic 

LOAEL for decreased survival of offspring in birds, so adverse effects to insectivorous birds may 

be expected from chronic dietary exposures. 

Estimated dose from contaminated insects, assuming the highest residue rates, at the highest 

application rate (10 lb/acre) is 1,130 mg/kg. This dose is two times greater than the LD50 

for 

triclopyr acid and three times greater than the LD50 for triclopyr BEE. Mortality is expected if 

insectivorous birds feed exclusively within the treatment area on contaminated insects. 

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herbicide application: reproduction, growth, and survival. Can. J. Zool. 59:1148-1154. 

Sullivan, T.P., Sullivan, D.S., Lautenschlager, R.A., and Wagner, R. G. 1997. Long-term influence 

of glyphosate herbicide on demography and diversity of small mammal communities in coastal 

coniferous forest. Northwest Science 71(1): 6-17. 

Timchalk, C., D.R. Finco, and J.F. Quast. 1997. Evaluation of renal function in rhesus monkeys 

and comparison to beagle dogs following oral administration of the organic acid triclopyr (3,5,6-

trichloro-2-pyridinyloxyacetic acid). Fundamentals and Applied Toxicol. 36: 47-53. 

Timchalk, C., M.D. Dryzga, and P.E. Kastl. 1990. Pharmacokinetics and metabolism of triclopyr 

(3,5,6-trichloro-2-pyridinyloxyacetic acid) in Fischer 344 rats. Toxicology 62: 71-87. 

Timchalk, C., and R.J. Nolan. 1997. Pharmacokinetics of triclopyr (3,5,6-trichloro-2-

pyridinyloxyacetic acid) in the beagle dog and rhesus monkey: perspective on the reduced 

 C-96 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

capacity of dogs to excrete this organic acid relative to the rat, monkey, and human. Toxicol. and 

Applied Pharmacol. 144: 268-278. 

Urban, D.J, and N.J. Cook. Hazard Evaluation Division, Standard Evaluation Procedure, 

Ecological Risk Assessment. unpublished report. US EPA, Office of Pesticide Programs, Hazard 

Evaluation Division. Washington, D.C. 

US EPA/ORD (Environmental Protection Agency/Office of Research and Development). 1993. 

Wildlife Exposure Factors Handbook. Volumes 1 and 2. EPA/600/R-93/187a,b. Available NTIS: 

PB94-174778 and PB94-174779. 

USEPA (Environmental Protection Agency). 1997. Status of data for 2,4-D. Accessed at: 

http://www.epa.gov/ngispgm3/. 

USEPA (Environmental Protection Agency). 2000. Supplementary guidance for conductiong 

Health Risk Assessment of chemical mixtures. EPA/630/r-00/002. Washington, D.C. 143 pp. + 

appendices. 

USDA Forest Service. 2002. Analysis of Issues Surrounding the Use of Spray Adjuvants with 

Herbicides. David Bakke. Pacific Southwest Region. Vallejo, California. 

USDA Forest Service. 2003. Human and Ecological Risk Assessment of NPE Surfactants in 

Forest Service Herbicide Applications, 2003. David Bakke. Pacific Southwest Region. Vellego, 

California. 

Weed Science Society of America. 2002. Herbicide Handbook. 8

th 

edition. W.K. Vencill (ed.). 

Weed Science Society of America. Lawrence, Kansas. 493pp. 

Yu et al. 1975 bioconcentration of dicamba. 

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Appendix C-Wildlife 

APPENDIX 1 of Summary of Herbicide Effects to Wildlife 

Estimated doses for each exposure scenario for 12 herbicides. 

The upper estimate used for this analysis includes worst-case assumptions such as highest residue 

rates, highest food intake, etc. 

Chlorsulfuron / Typical Application Rate 

Only the Upper exposure estimates are used in this document. 

Worksheet G01 (modified): Summary of Exposure Scenarios for Terrestrial Animals 

Scenario Dose (mg/kg/day) 

Typical Lower Upper Worksheet 

Acute/Accidental Exposures 

Direct spray 

small animal, 100% absorption 1.36E+00 1.36E+00 1.36E+00 F02a 

bee, 100% absorption 8.98E+00 8.98E+00 8.98E+00 F02b 

Contaminated vegetation 

small mammal 7.00E-02 7.00E-02 1.50E-01 F03 

large mammal 9.63E-01 9.63E-01 2.72E+00 F10 

large bird 1.51E+00 1.51E+00 4.26E+00 F12 

Contaminated water 

small mammal, spill 1.11E-02 2.22E-03 1.11E-01 F05 

Contaminated insects 

small mammal 1.30E+00 1.30E+00 3.89E+00 F14a 

small bird 2.11E+00 2.11E+00 6.32E+00 F14b 

Contaminated prey 

predatory mammal (small 

mammal) 

1.17E-01 1.17E-01 1.17E-01 F16a 

predatory bird (small mammal) 1.81E-01 1.81E-01 1.81E-01 F16b 

predatory bird (fish) 1.97E-02 1.97E-03 2.95E-01 F08 

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 C-99

Chlorsulfuron / Typical Application Rate 

Only the Upper exposure estimates are used in this document. 

Longer-term Exposures 

Contaminated vegetation 

small mammal, on site 2.95E-03 1.47E-03 1.26E-02 F04a 

large mammal, on site 1.22E-01 4.05E-02 1.14E+00 F11a 

large bird, on site 1.90E-01 6.34E-02 1.79E+00 F13a 

Contaminated water 

small mammal 4.92E-06 8.20E-07 7.38E-06 F07 

Contaminated fish 

predatory bird 4.03E-05 3.36E-06 9.07E-05 F09 

Chlorsulfuron / Highest Application Rate 

Only upper exposure estimates are used in this document. 

Worksheet G01 (modified): Summary of Exposure Scenarios for Terrestrial Animals. 

Scenario Dose (mg/kg/day) 

Typical Lower Upper Worksheet 

Acute/Accidental Exposures 

Direct spray 

small animal, 100% absorption 6.06E+00 6.06E+00 6.06E+00 F02a 

bee, 100% absorption 4.01E+01 4.01E+01 4.01E+01 F02b 

Contaminated vegetation 

small mammal 3.13E-01 3.13E-01 6.70E-01 F03 

large mammal 4.30E+00 4.30E+00 1.21E+01 F10 

large bird 6.73E+00 6.73E+00 1.90E+01 F12 

Contaminated water 

small mammal, spill 4.95E-02 9.89E-03 4.95E-01 F05 

Contaminated insects 

small mammal 5.78E+00 5.78E+00 1.73E+01 F14a 
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Appendix C-Wildlife 

 C-100 

Chlorsulfuron / Highest Application Rate 

Only upper exposure estimates are used in this document. 

small bird 9.40E+00 9.40E+00 2.82E+01 F14b 

Contaminated prey 

predatory mammal (small 

mammal) 

5.25E-01 5.25E-01 5.25E-01 F16a 

predatory bird (small mammal) 8.08E-01 8.08E-01 8.08E-01 F16b 

predatory bird (fish) 8.79E-02 8.79E-03 1.32E+00 F08 

Longer-term Exposures 

Contaminated vegetation 

small mammal, on site 1.32E-02 6.58E-03 5.64E-02 F04a 

large mammal, on site 5.43E-01 1.81E-01 5.11E+00 F11a 

large bird, on site 8.50E-01 2.83E-01 8.00E+00 F13a 

Contaminated water 

small mammal 2.20E-05 3.66E-06 3.29E-05 F07 

Contaminated fish 

predatory bird 1.80E-04 1.50E-05 4.05E-04 F09 

Clopyralid / Typical Application Rate 

Only upper exposure estimates are used in this document. 

Worksheet G01 (modified): Summary of Exposure Scenarios for Terrestrial Animals 

Scenario Dose (mg/kg/day) 

Typical Lower Upper Worksheet 

Acute/Accidental Exposures 

Direct spray 

small animal, 100% absorption 8.49E+00 8.49E+00 8.49E+00 F02a 

bee, 100% absorption 5.61E+01 5.61E+01 5.61E+01 F02b 

Contaminated vegetation 

small mammal 4.38E-01 4.38E-01 9.38E-01 F03 
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Appendix C-Wildlife 

large mammal 6.02E+00 6.02E+00 1.70E+01 F10 

large bird 9.42E+00 9.42E+00 2.66E+01 F12 

Contaminated water 

small mammal, spill 4.65E-01 1.11E-01 2.33E+00 F05 

Contaminated insects 

small mammal 8.10E+00 8.10E+00 2.43E+01 F14a 

small bird 1.32E+01 1.32E+01 3.95E+01 F14b 

Contaminated prey 

predatory mammal (small 

mammal) 

7.34E-01 7.34E-01 7.34E-01 F16a 

predatory bird (small mammal) 1.13E+00 1.13E+00 1.13E+00 F16b 

predatory bird (fish) 3.18E-01 3.79E-02 2.38E+00 F08 

Longer-term Exposures 

Contaminated vegetation 

small mammal, on site 1.77E-02 7.04E-03 9.87E-02 F04a 

large mammal, on site 7.29E-01 1.94E-01 8.95E+00 F11a 

large bird, on site 1.14E+00 3.03E-01 1.40E+01 F13a 

Contaminated water 

small mammal 3.59E-04 5.12E-05 6.66E-04 F07 

Contaminated fish 

predatory bird 2.45E-04 1.75E-05 6.83E-04 F09 

Clopyralid / Highest Application Rate 

Only upper exposure estimates are used in this document. 

Worksheet G01 (modified): Summary of Exposure Scenarios for Terrestrial Animals 

Scenario Dose (mg/kg/day) 

Typical Lower Upper Worksheet 

Acute/Accidental Exposures 

Direct spray 

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Appendix C-Wildlife 

 C-102 

Clopyralid / Highest Application Rate 

Only upper exposure estimates are used in this document. 

small animal, 100% absorption 1.21E+01 1.21E+01 1.21E+01 F02a 

bee, 100% absorption 8.01E+01 8.01E+01 8.01E+01 F02b 

Contaminated vegetation 

small mammal 6.25E-01 6.25E-01 1.34E+00 F03 

large mammal 8.60E+00 8.60E+00 2.43E+01 F10 

large bird 1.35E+01 1.35E+01 3.80E+01 F12 

Contaminated water 

small mammal, spill 6.65E-01 1.58E-01 3.32E+00 F05 

Contaminated insects 

small mammal 1.16E+01 1.16E+01 3.47E+01 F14a 

small bird 1.88E+01 1.88E+01 5.64E+01 F14b 

Contaminated prey 

predatory mammal (small 

mammal) 

1.05E+00 1.05E+00 1.05E+00 F16a 

predatory bird (small mammal) 1.62E+00 1.62E+00 1.62E+00 F16b 

predatory bird (fish) 4.54E-01 5.41E-02 3.41E+00 F08 

Longer-term Exposures 

Contaminated vegetation 

small mammal, on site 2.52E-02 1.01E-02 1.41E-01 F04a 

large mammal, on site 1.04E+00 2.77E-01 1.28E+01 F11a 

large bird, on site 1.63E+00 4.33E-01 2.00E+01 F13a 

Contaminated water 

small mammal 5.12E-04 7.32E-05 9.52E-04 F07 

Contaminated fish 

predatory bird 3.50E-04 2.50E-05 9.75E-04 F09 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

Glyphosate / Typical Application Rate 

Only upper exposure estimates are used in this document. 

Worksheet G01 (modified): Summary of Exposure Scenarios for Terrestrial Animals 

Scenario Dose (mg/kg/day) 

Typical Lower Upper Worksheet 

Acute/Accidental Exposures 

Direct spray 

small animal, 100% absorption 4.85E+01 4.85E+01 4.85E+01 F02a 

bee, 100% absorption 3.21E+02 3.21E+02 3.21E+02 F02b 

Contaminated vegetation 

small mammal 8.57E-01 8.57E-01 2.11E+00 F03 

large mammal 3.44E+01 3.44E+01 9.71E+01 F10 

large bird 5.38E+01 5.38E+01 1.52E+02 F12 

Contaminated water 

small mammal, spill 2.66E+00 1.06E+00 5.32E+00 F05 

Contaminated insects 

small mammal 4.63E+01 4.63E+01 1.39E+02 F14a 

small bird 8.E+01 7.52E+01 2.26E+02 F14b 

Contaminated prey 

predatory mammal (small 

mammal) 

4.20E+00 4.20E+00 4.20E+00 F16a 

predatory bird (small mammal) 6.46E+00 6.46E+00 6.46E+00 F16b 

predatory bird (fish) 9.45E-01 1.89E-01 2.83E+00 F08 

Longer-term Exposures 

Contaminated vegetation 

small mammal, on site 4.69E-02 2.35E-02 2.31E-01 F04a 

large mammal, on site 5.65E+00 1.88E+00 5.32E+01 F11a 

large bird, on site 8.84E+00 2.95E+00 8.32E+01 F13a 

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Appendix C-Wildlife 

 C-104 

Glyphosate / Typical Application Rate 

Only upper exposure estimates are used in this document. 

Contaminated water 

small mammal 2.93E-04 2.93E-05 2.34E-03 F07 

Contaminated fish 

predatory bird 1.04E-04 5.20E-06 1.25E-03 F09 

Glyphosate / Highest Application Rate 

Only upper exposure estimates are used in this document. 

Worksheet G01 (modified): Summary of Exposure Scenarios for Terrestrial Animals 

Scenario Dose (mg/kg/day) 

Typical Lower Upper Worksheet 

Acute/Accidental Exposures 

Direct spray 

small animal, 100% absorption 1.70E+02 1.70E+02 1.70E+02 F02a 

bee, 100% absorption 1.12E+03 1.12E+03 1.12E+03 F02b 

Contaminated vegetation 

small mammal 3.00E+00 3.00E+00 7.38E+00 F03 

large mammal 1.20E+02 1.20E+02 3.40E+02 F10 

large bird 1.88E+02 1.88E+02 5.32E+02 F12 

Contaminated water 

small mammal, spill 9.31E+00 3.72E+00 1.86E+01 F05 

Contaminated insects 

small mammal 1.62E+02 1.62E+02 4.86E+02 F14a 

small bird 3.E+02 2.63E+02 7.90E+02 F14b 

Contaminated prey 

predatory mammal (small 

mammal) 

1.47E+01 1.47E+01 1.47E+01 F16a 

predatory bird (small mammal) 2.26E+01 2.26E+01 2.26E+01 F16b 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

Glyphosate / Highest Application Rate 

Only upper exposure estimates are used in this document. 

predatory bird (fish) 3.31E+00 6.61E-01 9.92E+00 F08 

Longer-term Exposures 

Contaminated vegetation 

small mammal, on site 1.64E-01 8.21E-02 8.07E-01 F04a 

large mammal, on site 1.98E+01 6.59E+00 1.86E+02 F11a 

large bird, on site 3.09E+01 1.03E+01 2.91E+02 F13a 

Contaminated water 

small mammal 1.02E-03 1.02E-04 8.20E-03 F07 

Contaminated fish 

predatory bird 3.64E-04 1.82E-05 4.37E-03 F09 

Imazapic / Typical Application Rate 

Only upper exposure estimates are used in this document. 

Worksheet G01 (modified): Summary of Exposure Scenarios for Terrestrial Animals 

Scenario Dose (mg/kg/day) 

Typical Lower Upper Worksheet 

Acute/Accidental Exposures 

Direct spray 

small animal, 100% absorption 2.42E+00 2.42E+00 2.42E+00 F02a 

bee, 100% absorption 1.60E+01 1.60E+01 1.60E+01 F02b 

Contaminated vegetation 

small mammal 1.25E-01 1.25E-01 2.68E-01 F03 

large mammal 1.72E+00 1.72E+00 4.86E+00 F10 

large bird 2.69E+00 2.69E+00 7.60E+00 F12 

Contaminated water 

small mammal, spill 2.42E+00 2.42E+00 2.42E+00 F05 

Contaminated insects 

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Appendix C-Wildlife 

 C-106 

Imazapic / Typical Application Rate 

Only upper exposure estimates are used in this document. 

small mammal 2.31E+00 2.31E+00 6.94E+00 F14a 

small bird 3.76E+00 3.76E+00 1.13E+01 F14b 

Contaminated prey 

predatory mammal (small 

mammal) 

2.10E-01 2.10E-01 2.10E-01 F16a 

predatory bird (small mammal) 3.23E-01 3.23E-01 3.23E-01 F16b 

predatory bird (fish) 1.67E-02 5.00E-03 7.49E-02 F08 

Longer-term Exposures 

Contaminated vegetation 

small mammal, on site 8.02E-04 1.20E-04 1.02E-02 F04a 

large mammal, on site 3.31E-02 3.31E-03 9.29E-01 F11a 

large bird, on site 5.18E-02 5.18E-03 1.45E+00 F13a 

Contaminated water 

small mammal 2.93E-07 1.46E-07 4.39E-07 F07 

Contaminated fish 

predatory bird 2.20E-08 5.50E-09 4.95E-08 F09 

Imazapic / Highest Application Rate 

Only upper exposure estimates are used in this document. 

Worksheet G01 (modified): Summary of Exposure Scenarios for Terrestrial Animals 

Scenario Dose (mg/kg/day) 

Typical Lower Upper Worksheet 

Acute/Accidental Exposures 

Direct spray 

small animal, 100% absorption 4.36E+00 4.36E+00 4.36E+00 F02a 

bee, 100% absorption 2.89E+01 2.89E+01 2.89E+01 F02b 

Contaminated vegetation 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

Imazapic / Highest Application Rate 

Only upper exposure estimates are used in this document. 

small mammal 2.25E-01 2.25E-01 4.82E-01 F03 

large mammal 3.10E+00 3.10E+00 8.74E+00 F10 

large bird 4.85E+00 4.85E+00 1.37E+01 F12 

Contaminated water 

small mammal, spill 4.21E-01 2.53E-01 1.26E+00 F05 

Contaminated insects 

small mammal 4.16E+00 4.16E+00 1.25E+01 F14a 

small bird 6.77E+00 6.77E+00 2.03E+01 F14b 

Contaminated prey 

predatory mammal (small 

mammal) 

3.78E-01 3.78E-01 3.78E-01 F16a 

predatory bird (small mammal) 5.82E-01 5.82E-01 5.82E-01 F16b 

predatory bird (fish) 3.16E-02 9.49E-03 1.42E-01 F08 

Longer-term Exposures 

Contaminated vegetation 

small mammal, on site 1.44E-03 2.16E-04 1.84E-02 F04a 

large mammal, on site 5.95E-02 5.95E-03 1.67E+00 F11a 

large bird, on site 9.32E-02 9.32E-03 2.62E+00 F13a 

Contaminated water 

small mammal 5.27E-07 2.64E-07 7.91E-07 F07 

Contaminated fish 

predatory bird 3.96E-08 9.90E-09 8.91E-08 F09 

3.38E-05 

F09 

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Appendix C-Wildlife 

Imazapyr / Typical Application Rate 

Only upper exposure estimates are used in this document. 

Worksheet G01 (modified): Summary of Exposure Scenarios for Terrestrial Animals 

Scenario Dose (mg/kg/day) 

Typical Lower Upper Worksheet 

Acute/Accidental Exposures 

Direct spray 

small animal, 100% 

absorption 

1.09E+01 1.09E+01 1.09E+01 F02a 

bee, 100% absorption 7.21E+01 7.21E+01 7.21E+01 

Contaminated vegetation 

small mammal 5.63E-01 5.63E-01 1.21E+00 F03 

large mammal 7.74E+00 7.74E+00 2.19E+01 F10 

large bird 1.21E+01 1.21E+01 3.42E+01 F12 

Contaminated water 

small mammal, spill 5.98E-01 2.99E-01 1.22E+00 F05 

Contaminated insects 

small mammal 1.04E+01 1.04E+01 3.12E+01 F14a 

small bird 1.69E+01 1.69E+01 5.08E+01 F14b 

Contaminated prey 

predatory mammal (small 

mammal) 

9.44E-01 9.44E-01 9.44E-01 F16a 

predatory bird (small 

mammal) 

1.45E+00 1.45E+00 1.45E+00 F16b 

predatory bird (fish) 2.04E-01 5.11E-02 6.25E-01 F08 

Longer-term Exposures 

Contaminated vegetation 

small mammal, on site 2.13E-02 6.66E-03 1.17E-01 F04a 

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Appendix C-Wildlife 

 C-109

Imazapyr / Typical Application Rate 

Only upper exposure estimates are used in this document. 

large mammal, on site 8.80E-01 1.83E-01 1.06E+01 F11a 

large bird, on site 1.38E+00 2.87E-01 1.65E+01 F13a 

Contaminated water 

small mammal 6.59E-06 6.59E-07 6.59E-05 F07 

Contaminated fish 

predatory bird 2.25E-06 1.13E-07 

Upper Worksheet Typical Lower 

Acute/Accidental Exposures 

Direct spray 

small animal, 100% absorption 3.03E+01 3.03E+01 3.03E+01 F02a 

Imazapyr / Highest Application Rate 

Only upper exposure estimates are used in this document. 

Worksheet G01 (modified): Summary of Exposure Scenarios for Terrestrial Animals 

Scenario Dose (mg/kg/day) 

bee, 100% absorption 2.E-01 2.E-01 2.E-01 F02b 

Contaminated vegetation 

small mammal 1.56E+00 1.56E+00 3.35E+00 F03 

large mammal 2.15E+01 2.15E+01 6.07E+01 F10 

large bird 3.37E+01 3.37E+01 9.50E+01 F12 

Contaminated water 

small mammal, spill 1.66E+00 8.31E-01 3.39E+00 F05 

Contaminated insects 

small mammal 2.89E+01 2.89E+01 8.67E+01 F14a 

small bird 4.70E+01 4.70E+01 1.41E+02 F14b 

Contaminated prey 

predatory mammal (small mammal) 2.62E+00 2.62E+00 2.62E+00 F16a 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

predatory bird (small mammal) 4.04E+00 4.04E+00 4.04E+00 F16b 

predatory bird (fish) 5.68E-01 1.42E-01 1.73E+00 F08 

Longer-term Exposures 

Contaminated vegetation 

small mammal, on site 5.92E-02 1.85E-02 3.24E-01 F04a 

large mammal, on site 2.44E+00 5.09E-01 2.93E+01 F11a 

large bird, on site 3.83E+00 7.97E-01 4.59E+01 F13a 

Contaminated water 

small mammal 1.83E-05 1.83E-06 1.83E-04 F07 

Contaminated fish 

predatory bird 6.25E-06 3.13E-07 9.38E-05 F09 

Metsulfuron methyl / Typical Application Rate 

Only upper exposure estimates are used in this document. 

Worksheet G01 (modified): Summary of Exposure Scenarios for Terrestrial Animals 

Scenario Dose (mg/kg/day) 

Typical Lower Upper Worksheet 

Acute/Accidental Exposures 

Direct spray 

small animal, 100% absorption 7.27E-01 7.27E-01 7.27E-01 F02a 

bee, 100% absorption 4.81E+00 4.81E+00 4.81E+00 F02b 

Contaminated vegetation 

small mammal 3.75E-02 3.75E-02 8.04E-02 F03 

large mammal 5.16E-01 5.16E-01 1.46E+00 F10 

large bird 8.08E-01 8.08E-01 2.28E+00 F12 

Contaminated water 

small mammal, spill 1.11E-02 1.11E-03 4.43E-02 F05 

Contaminated insects 

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Appendix C-Wildlife 

Metsulfuron methyl / Typical Application Rate 

Only upper exposure estimates are used in this document. 

small mammal 6.94E-01 6.94E-01 2.08E+00 F14a 

small bird 1.13E+00 1.13E+00 3.38E+00 F14b 

Contaminated prey 

predatory mammal (small 

mammal) 

6.29E-02 6.29E-02 6.29E-02 F16a 

predatory bird (small mammal) 9.70E-02 9.70E-02 9.70E-02 F16b 

predatory bird (fish) 1.59E-03 7.95E-05 9.54E-03 F08 

Longer-term Exposures 

Contaminated vegetation 

small mammal, on site 1.58E-03 7.89E-04 6.76E-03 F04a 

large mammal, on site 6.51E-02 2.17E-02 6.13E-01 F11a 

large bird, on site 1.02E-01 3.40E-02 9.60E-01 F13a 

Contaminated water 

small mammal 8.78E-07 4.39E-07 1.76E-06 F07 

Contaminated fish 

predatory bird 1.27E-06 3.17E-07 3.80E-06 F09 

Metsulfuron methyl / Highest Application Rate 

Only upper exposure estimates are used in this document. 

Worksheet G01 (modified): Summary of Exposure Scenarios for Terrestrial Animals 

Scenario Dose (mg/kg/day) 

Typical Lower Upper Worksheet 

Acute/Accidental Exposures 

Direct spray 

small animal, 100% absorption 3.64E+00 3.64E+00 3.64E+00 F02a 

bee, 100% absorption 2.40E+01 2.40E+01 2.40E+01 F02b 

Contaminated vegetation 

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Appendix C-Wildlife 

 C-112 

Metsulfuron methyl / Highest Application Rate 

Only upper exposure estimates are used in this document. 

small mammal 1.88E-01 1.88E-01 4.02E-01 F03 

large mammal 2.58E+00 2.58E+00 7.28E+00 F10 

large bird 4.04E+00 4.04E+00 1.14E+01 F12 

Contaminated water 

small mammal, spill 5.54E-02 5.54E-03 2.22E-01 F05 

Contaminated insects 

small mammal 3.47E+00 3.47E+00 1.04E+01 F14a 

small bird 5.64E+00 5.64E+00 1.69E+01 F14b 

Contaminated prey 

predatory mammal (small 

mammal) 

3.15E-01 3.15E-01 3.15E-01 F16a 

predatory bird (small mammal) 4.85E-01 4.85E-01 4.85E-01 F16b 

predatory bird (fish) 7.95E-03 3.97E-04 4.77E-02 F08 

Longer-term Exposures 

Contaminated vegetation 

small mammal, on site 7.89E-03 3.95E-03 3.38E-02 F04a 

large mammal, on site 3.26E-01 1.09E-01 3.07E+00 F11a 

large bird, on site 5.10E-01 1.70E-01 4.80E+00 F13a 

Contaminated water 

small mammal 4.39E-06 2.20E-06 8.78E-06 F07 

Contaminated fish 

predatory bird 6.33E-06 1.58E-06 1.90E-05 F09 

Picloram / Typical Application Rate 

Only upper exposure estimates are used in this document. 

Worksheet G01 (modified): Summary of Exposure Scenarios for Terrestrial Animals 

Scenario Dose (mg/kg/day) 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

Picloram / Typical Application Rate 

Only upper exposure estimates are used in this document. 

Typical Lower Upper Worksheet 

Acute/Accidental Exposures 

Direct spray 

small animal, 100% absorption 2.E-01 2.E-01 2.E-01 F02a 

bee, 100% absorption 6.E-02 6.E-02 6.E-02 F02b 

Contaminated vegetation 

small mammal 1.E-02 1.E-02 3.E-02 F03 

large mammal 2.E-01 2.E-01 5.E-01 F10 

large bird 6.E-03 6.E-03 2.E-02 F12 

Contaminated water 

small mammal, spill 5.E-03 1.E-03 3.E-02 F05 

Contaminated insects 

small mammal 2.38E-01 2.38E-01 7.14E-01 F14a 

small bird 9.E-03 9.E-03 3.E-02 F14b 

Contaminated prey 

predatory mammal (small mammal) 2.16E-02 2.16E-02 2.16E-02 F16a 

predatory bird (small mammal) 7.54E-04 7.54E-04 7.54E-04 F16b 

predatory bird (fish) 7.E-05 1.E-05 6.E-04 F08 

Longer-term Exposures 

Contaminated vegetation 

small mammal, on site 8.E-04 4.E-04 3.E-03 F04a 

large mammal, on site 3.E-02 1.E-02 3.E-01 F11a 

large bird, on site 5.E-02 2.E-02 5.E-01 F13a 

Contaminated water 

small mammal 7.E-06 7.E-07 3.E-05 F07 

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Appendix C-Wildlife 

 C-114 

Picloram / Typical Application Rate 

Only upper exposure estimates are used in this document. 

Contaminated fish 

predatory bird 5.E-06 3.E-07 3.E-05 F09 

Picloram / Highest Application Rate 

Only upper exposure estimates are used in this document. 

Worksheet G01 (modified): Summary of Exposure Scenarios for Terrestrial Animals 

Scenario Dose (mg/kg/day) 

Typical Lower Upper Worksheet 

Acute/Accidental Exposures 

Direct spray 

small animal, 100% absorption 2.42E+01 2.42E+01 2.42E+01 F02a 

bee, 100% absorption 1.60E+02 1.60E+02 1.60E+02 F02b 

Contaminated vegetation 

small mammal 1.25E+00 1.25E+00 2.68E+00 F03 

large mammal 1.72E+01 1.72E+01 4.86E+01 F10 

large bird 2.69E+01 2.69E+01 7.60E+01 F12 

Contaminated water 

small mammal, spill 4.43E-01 1.33E-01 2.53E+00 F05 

Contaminated insects 

small mammal 2.31E+01 2.31E+01 6.94E+01 F14a 

small bird 3.76E+01 3.76E+01 1.13E+02 F14b 

Contaminated prey 

predatory mammal (small 

mammal) 

2.10E+00 2.10E+00 2.10E+00 F16a 

predatory bird (small mammal) 3.23E+00 3.23E+00 3.23E+00 F16b 

predatory bird (fish) 3.03E-01 4.54E-02 2.60E+00 F08 

Longer-term Exposures 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

Picloram / Highest Application Rate 

Only upper exposure estimates are used in this document. 

Contaminated vegetation 

small mammal, on site 1.60E-02 8.01E-03 6.87E-02 F04a 

large mammal, on site 6.61E-01 2.20E-01 6.22E+00 F11a 

large bird, on site 1.04E+00 3.45E-01 9.74E+00 F13a 

Contaminated water 

small mammal 1.46E-04 1.46E-05 5.86E-04 F07 

Contaminated fish 

predatory bird 1.00E-04 5.00E-06 6.00E-04 F09 

Sethoxydim / Typical Application Rate 

Only upper exposure estimates are used in this document. 

Worksheet G01 (modified): Summary of Exposure Scenarios for Terrestrial Animals 

Scenario Dose (mg/kg/day) 

Typical Lower Upper Worksheet 

Acute/Accidental Exposures 

Direct spray 

small animal, 100% absorption 7.27E+00 7.27E+00 7.27E+00 F02a 

bee, 100% absorption 4.81E+01 4.81E+01 4.81E+01 F02b 

Contaminated vegetation 

small mammal 3.75E-01 3.75E-01 8.04E-01 F03 

large mammal 5.16E+00 5.16E+00 1.46E+01 F10 

large bird 8.08E+00 8.08E+00 2.28E+01 F12 

Contaminated water 

small mammal, spill 3.99E-01 6.21E-02 9.97E-01 F05 

Contaminated insects 

small mammal 6.94E+00 6.94E+00 2.08E+01 F14a 

small bird 1.13E+01 1.13E+01 3.38E+01 F14b 

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Appendix C-Wildlife 

 C-116 

Sethoxydim / Typical Application Rate 

Only upper exposure estimates are used in this document. 

Contaminated prey 

predatory mammal (small 

mammal) 

6.29E-01 6.29E-01 6.29E-01 F16a 

predatory bird (small mammal) 9.70E-01 9.70E-01 9.70E-01 F16b 

predatory bird (fish) 9.81E-01 7.63E-02 3.68E+00 F08 

Longer-term Exposures 

Contaminated vegetation 

small mammal, on site 1.80E-03 9.02E-04 7.73E-03 F04a 

large mammal, on site 7.44E-02 2.48E-02 7.01E-01 F11a 

large bird, on site 1.17E-01 3.88E-02 1.10E+00 F13a 

Contaminated water 

small mammal 3.51E-05 8.78E-07 5.27E-05 F07 

Contaminated fish 

predatory bird 5.04E-04 6.30E-06 1.13E-03 F09 

Sethoxydim/ Highest Application Rate 

Only upper exposure estimates are used in this document. 

Worksheet G01 (modified): Summary of Exposure Scenarios for Terrestrial Animals 

Scenario Dose (mg/kg/day) 

Typical Lower Upper Worksheet 

Acute/Accidental Exposures 

Direct spray 

small animal, 100% absorption 9.09E+00 9.09E+00 9.09E+00 F02a 

bee, 100% absorption 6.01E+01 6.01E+01 6.01E+01 F02b 

Contaminated vegetation 

small mammal 4.69E-01 4.69E-01 1.00E+00 F03 

large mammal 6.45E+00 6.45E+00 1.82E+01 F10 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

Sethoxydim/ Highest Application Rate 

Only upper exposure estimates are used in this document. 

large bird 1.01E+01 1.01E+01 2.85E+01 F12 

Contaminated water 

small mammal, spill 3.99E-01 6.21E-02 9.97E-01 F05 

Contaminated insects 

small mammal 8.67E+00 8.67E+00 2.60E+01 F14a 

small bird 1.41E+01 1.41E+01 4.23E+01 F14b 

Contaminated prey 

predatory mammal (small 

mammal) 

7.87E-01 7.87E-01 7.87E-01 F16a 

predatory bird (small mammal) 1.21E+00 1.21E+00 1.21E+00 F16b 

predatory bird (fish) 9.81E-01 7.63E-02 3.68E+00 F08 

Longer-term Exposures 

Contaminated vegetation 

small mammal, on site 2.25E-03 1.13E-03 9.66E-03 F04a 

large mammal, on site 9.30E-02 3.10E-02 8.76E-01 F11a 

large bird, on site 1.46E-01 4.86E-02 1.37E+00 F13a 

Contaminated water 

small mammal 4.39E-05 1.10E-06 6.59E-05 F07 

Contaminated fish 

predatory bird 6.30E-04 7.88E-06 1.42E-03 F09 

Sulfometuron methyl / Typical Application Rate 

Only upper exposure estimates are used in this document. 

Worksheet G01 (modified): Summary of Exposure Scenarios for Terrestrial Animals 

Scenario Dose (mg/kg/day) 

Typical Lower Upper Worksheet 

Acute/Accidental Exposures 

 C-117
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Appendix C-Wildlife 

 C-118 

Sulfometuron methyl / Typical Application Rate 

Only upper exposure estimates are used in this document. 

Direct spray 

small animal, 100% absorption 1.09E+00 1.09E+00 1.09E+00 F02a 

bee, 100% absorption 7.21E+00 7.21E+00 7.21E+00 F02b 

Contaminated vegetation 

small mammal 5.63E-02 5.63E-02 1.21E-01 F03 

large mammal 7.74E-01 7.74E-01 2.19E+00 F10 

large bird 1.21E+00 1.21E+00 3.42E+00 F12 

Contaminated water 

small mammal, spill 4.43E-02 1.44E-02 1.22E-01 F05 

Contaminated insects 

small mammal 1.04E+00 1.04E+00 3.12E+00 F14a 

small bird 1.69E+00 1.69E+00 5.08E+00 F14b 

Contaminated prey 

predatory mammal (small 

mammal) 

9.44E-02 9.44E-02 9.44E-02 F16a 

predatory bird (small mammal) 1.45E-01 1.45E-01 1.45E-01 F16b 

predatory bird (fish) 1.06E-01 1.72E-02 4.37E-01 F08 

Longer-term Exposures 

Contaminated vegetation 

small mammal, on site 9.00E-04 4.50E-04 3.86E-03 F04a 

large mammal, on site 3.71E-02 1.24E-02 3.50E-01 F11a 

large bird, on site 5.81E-02 1.94E-02 5.47E-01 F13a 

Contaminated water 

small mammal 2.64E-07 6.59E-08 4.61E-07 F07 

Contaminated fish 

predatory bird 1.08E-06 1.35E-07 2.84E-06 F09 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

Sulfometuron methyl / Highest Application Rate 

Only upper exposure estimates are used in this document. 

Worksheet G01 (modified): Summary of Exposure Scenarios for Terrestrial Animals 

Scenario Dose (mg/kg/day) 

Typical Lower Upper Worksheet 

Acute/Accidental Exposures 

Direct spray 

small animal, 100% absorption 9.21E+00 9.21E+00 9.21E+00 F02a 

bee, 100% absorption 6.09E+01 6.09E+01 6.09E+01 F02b 

Contaminated vegetation 

small mammal 4.75E-01 4.75E-01 1.02E+00 F03 

large mammal 6.54E+00 6.54E+00 1.85E+01 F10 

large bird 1.02E+01 1.02E+01 2.89E+01 F12 

Contaminated water 

small mammal, spill 3.74E-01 1.22E-01 1.03E+00 F05 

Contaminated insects 

small mammal 8.79E+00 8.79E+00 2.64E+01 F14a 

small bird 1.43E+01 1.43E+01 4.29E+01 F14b 

Contaminated prey 

predatory mammal (small 

mammal) 

7.97E-01 7.97E-01 7.97E-01 F16a 

predatory bird (small mammal) 1.23E+00 1.23E+00 1.23E+00 F16b 

predatory bird (fish) 8.95E-01 1.45E-01 3.69E+00 F08 

Longer-term Exposures 

Contaminated vegetation 

small mammal, on site 7.60E-03 3.80E-03 3.26E-02 F04a 

large mammal, on site 3.14E-01 1.05E-01 2.95E+00 F11a 

large bird, on site 4.91E-01 1.64E-01 4.62E+00 F13a 

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Appendix C-Wildlife 

 C-120 

Sulfometuron methyl / Highest Application Rate 

Only upper exposure estimates are used in this document. 

Contaminated water 

small mammal 2.23E-06 5.56E-07 3.89E-06 F07 

Contaminated fish 

predatory bird 9.12E-06 1.14E-06 2.39E-05 F09 

Triclopyr acid / Typical Application Rate 

Only upper exposure estimates are used in this document. 

Worksheet G01 (modified): Summary of Exposure Scenarios for Terrestrial Animals 

Scenario Dose (mg/kg/day) 

Typical Lower Upper Worksheet 

Acute/Accidental Exposures 

Direct spray 

small animal, 100% absorption 2.42E+01 2.42E+01 2.42E+01 F02a 

bee, 100% absorption 1.60E+02 1.60E+02 1.60E+02 F02b 

Contaminated vegetation 

small mammal 3.30E-01 3.30E-01 4.95E-01 F03 

large mammal 1.72E+01 1.72E+01 4.86E+01 F10 

large bird 2.69E+01 2.69E+01 7.60E+01 F12 

Contaminated water 

small mammal, spill 5.32E-01 3.32E-01 2.66E+00 F05 

Contaminated insects 

small mammal 2.31E+01 2.31E+01 6.94E+01 F14a 

small bird 3.76E+01 3.76E+01 1.13E+02 F14b 

Contaminated prey 

predatory mammal (small 

mammal) 

2.10E+00 2.10E+00 2.10E+00 F16a 

predatory bird (small mammal) 3.23E+00 3.23E+00 3.23E+00 F16b 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

Triclopyr acid / Typical Application Rate 

Only upper exposure estimates are used in this document. 

predatory bird (fish) 3.02E-01 9.42E-02 2.26E+00 F08 

Longer-term Exposures 

Contaminated vegetation 

small mammal, on site 1.62E-02 6.20E-03 6.52E-02 F04a 

large mammal, on site 2.52E+00 6.46E-01 3.20E+01 F11a 

large bird, on site 3.95E+00 1.01E+00 5.01E+01 F13a 

Contaminated water 

small mammal 4.39E-03 1.17E-03 7.32E-03 F07 

Contaminated fish 

predatory bird 2.49E-03 3.32E-04 6.23E-03 F09 

Triclopyr acid / Highest Application Rate 

Only upper exposure estimates are used in this document. 

Worksheet G01 (modified): Summary of Exposure Scenarios for Terrestrial Animals 

Scenario Dose (mg/kg/day) 

Typical Lower Upper Worksheet 

Acute/Accidental Exposures 

Direct spray 

small animal, 100% absorption 2.42E+02 2.42E+02 2.42E+02 F02a 

bee, 100% absorption 1.60E+03 1.60E+03 1.60E+03 F02b 

Contaminated vegetation 

small mammal 3.30E+00 3.30E+00 4.95E+00 F03 

large mammal 1.72E+02 1.72E+02 4.86E+02 F10 

large bird 2.69E+02 2.69E+02 7.60E+02 F12 

Contaminated water 

small mammal, spill 5.32E+00 3.32E+00 2.66E+01 F05 

Contaminated insects 

 C-121
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Appendix C-Wildlife 

 C-122 

Triclopyr acid / Highest Application Rate 

Only upper exposure estimates are used in this document. 

small mammal 2.31E+02 2.31E+02 6.94E+02 F14a 

small bird 3.76E+02 3.76E+02 1.13E+03 F14b 

Contaminated prey 

predatory mammal (small 

mammal) 

2.10E+01 2.10E+01 2.10E+01 F16a 

predatory bird (small mammal) 3.23E+01 3.23E+01 3.23E+01 F16b 

predatory bird (fish) 3.02E+00 9.42E-01 2.26E+01 F08 

Longer-term Exposures 

Contaminated vegetation 

small mammal, on site 1.62E-01 6.20E-02 6.52E-01 F04a 

large mammal, on site 2.52E+01 6.46E+00 3.20E+02 F11a 

large bird, on site 3.95E+01 1.01E+01 5.01E+02 F13a 

Contaminated water 

small mammal 4.39E-02 1.17E-02 7.32E-02 F07 

Contaminated fish 

predatory bird 2.49E-02 3.32E-03 6.23E-02 F09 

Triclopyr BEE / Typical Application Rate 

Only upper exposure estimates are used in this document. 

Worksheet G01 (modified): Summary of Exposure Scenarios for Terrestrial Animals 

Scenario Dose (mg/kg/day) 

Typical Lower Upper Worksheet 

Acute/Accidental Exposures 

Direct spray 

small animal, 100% absorption 2.42E+01 2.42E+01 2.42E+01 F02a 

bee, 100% absorption 1.60E+02 1.60E+02 1.60E+02 F02b 

Contaminated vegetation 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

Triclopyr BEE / Typical Application Rate 

Only upper exposure estimates are used in this document. 

small mammal 3.30E-01 3.30E-01 4.95E-01 F03 

large mammal 1.72E+01 1.72E+01 4.86E+01 F10 

large bird 2.69E+01 2.69E+01 7.60E+01 F12 

Contaminated water 

small mammal, spill 5.32E-01 3.32E-01 2.66E+00 F05 

Contaminated insects 

small mammal 2.31E+01 2.31E+01 6.94E+01 F14a 

small bird 3.76E+01 3.76E+01 1.13E+02 F14b 

Contaminated prey 

predatory mammal (small 

mammal) 

2.10E+00 2.10E+00 2.10E+00 F16a 

predatory bird (small mammal) 3.23E+00 3.23E+00 3.23E+00 F16b 

predatory bird (fish) 3.02E-01 9.42E-02 2.26E+00 F08 

Longer-term Exposures 

Contaminated vegetation 

small mammal, on site 1.62E-02 6.20E-03 6.52E-02 F04a 

large mammal, on site 2.52E+00 6.46E-01 3.20E+01 F11a 

large bird, on site 3.95E+00 1.01E+00 5.01E+01 F13a 

Contaminated water 

small mammal 4.39E-03 1.17E-03 7.32E-03 F07 

Contaminated fish 

predatory bird 2.49E-03 3.32E-04 6.23E-03 F09 

 C-123
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix C-Wildlife 

Triclopyr BEE / Highest Application Rate 

Only upper exposure estimates are used in this document. 

Worksheet G01 (modified): Summary of Exposure Scenarios for Terrestrial Animals 

Scenario Dose (mg/kg/day) 

Typical Lower Upper Worksheet 

Acute/Accidental Exposures 

Direct spray 

small animal, 100% absorption 2.42E+02 2.42E+02 2.42E+02 F02a 

bee, 100% absorption 1.60E+03 1.60E+03 1.60E+03 F02b 

Contaminated vegetation 

small mammal 3.30E+00 3.30E+00 4.95E+00 F03 

large mammal 1.72E+02 1.72E+02 4.86E+02 F10 

large bird 2.69E+02 2.69E+02 7.60E+02 F12 

Contaminated water 

small mammal, spill 5.32E+00 3.32E+00 2.66E+01 F05 

Contaminated insects 

small mammal 2.31E+02 2.31E+02 6.94E+02 F14a 

small bird 3.76E+02 3.76E+02 1.13E+03 F14b 

Contaminated prey 

predatory mammal (small 

mammal) 

2.10E+01 2.10E+01 2.10E+01 F16a 

predatory bird (small mammal) 3.23E+01 3.23E+01 3.23E+01 F16b 

predatory bird (fish) 3.02E+00 9.42E-01 2.26E+01 F08 

Longer-term Exposures 

Contaminated vegetation 

small mammal, on site 1.62E-01 6.20E-02 6.52E-01 F04a 

large mammal, on site 2.52E+01 6.46E+00 3.20E+02 F11a 

large bird, on site 3.95E+01 1.01E+01 5.01E+02 F13a 

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Appendix C-Wildlife 

 C-125

Triclopyr BEE / Highest Application Rate 

Only upper exposure estimates are used in this document. 

Contaminated water 

small mammal 4.39E-02 1.17E-02 7.32E-02 F07 

Contaminated fish 

predatory bird 2.49E-02 3.32E-03 6.23E-02 F09 

Thank you 
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 C-126 
Appendix D – Soil and Water 

List of Municipal Water Sources 

General Herbicide Properties in Relation to Soil 

Sensitive Soil Sites Identified
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Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix D-Soil and Water 

List of Municipal Water Sources found on the WallowaWhitman National Forest 

Several towns, recreation sites and other infrastructure facilities found in or near National Forest 

System Lands rely on the Forest for municipal water. The following lists those drawing municipal 

or domestic water, the watershed source and acres, and the approximate population served

 D-1
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 D-2 

Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 D-2 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix D-Soil and Water 

General Herbicide Properties in Relation to Soil 

General characteristics for the proposed herbicides are displayed below; these were compiled 

from the R6 2005 FEIS, label information and SERA Risk Assessments, the Mount Hood 

National Forest and Columbia River Gorge National Scenic Area (Oregon side) Site-Specific 

Invasive Plant Treatment FEIS, and the Deschutes, Ochoco and Crooked River National 

Grasslands Invasive Plants EIS. 

Chlorsulfuron 

Studies on the effects of chlorsulfuron on soil biota include lab and field studies on nematodes; 

fungi; populations of actinomycetes, bacteria, and fungi; and soil microorganisms. 

• No effects of chlorsulfuron were found for soil biota at recommended application 

rates, with the exception of transient decreases in soil nitrification. 

• The ‘no observable effects concentration’ for soil is 10 mg/kg, based on cellulose 

and protein degradation. 

• Chlorsulfuron degrades in aerobic soil. 

• Non-microbial hydrolysis plays an important role in chlorsulfuron breakdown, 

and hydrolysis rates increase as pH increases. 

• Adsorption to soil particles, which affects the runoff potential of chlorsulfuron, is 

strongly related to the amount of organic material in the soil. 

• Chlorsulfuron adsorption to clay is low. 

• Chlorsulfuron is moderately mobile at high pH. 

• Leaching is reduced when pH is less than six. 

• Modeling results indicate that runoff would be negligible in sandy or loamy soils. 

• In clay soils, off-site loss could be substantial (up to about 55 percent of the 

applied amount) in regions with annual rainfall rates of 15 to 250 inches. 

Clopyralid 

Studies of clopyralid effects on soil invertebrates have been conducted, including field studies on 

the effects to microorganisms. 

• Soil concentrations from USDA Forest Service applications are expected to be 

1,000 less than concentrations that would cause toxic effects. Therefore, no 

effects to soil invertebrates or microorganisms are expected from use of 

clopyralid. 

• Clopyralid is degraded by soil microbes, with an estimated half-life of 14 to 29 

days, meaning that one-half of the amount applied remains in the soils after 90 

days, one-fourth of the applied amount remains after 28 to 58 days, one –eight 

after 42 to 87 days, and so on. 

• Increased soil moisture decreases degradation time. 

 D-3
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix D-Soil and Water 

• Clopyralid is weakly adsorbed and has a moderate leaching potential overall but 

high leaching potential in sandy soils. 

• Modeling results indicate clopyralid runoff is highest in clay soils with peaks after 

rainfall events. 

• Clopyralid percolation is highest in sandy loam soils. 

Glyphosate 

Numerous soil bacteria, fungi, invertebrates, and other microorganisms have been studied for 

effects of glyphosate application. 

• Studies suggest glyphosate does not adversely affect soil organisms. 

• Glyphosate is readily metabolized by soil microorganisms and some species can 

use glyphosate as a sole source of carbon. 

• It is degraded by microbial action in both soil and water. 

• Sylvia and Jarstfer (1997) found that after 3 years, pine trees in plots with grassy 

invasive plants had 75 percent fewer mycorrhizal root tips than plots that had 

been treated 3 times per year with a mixture of glyphosate and metsulfuron 

methyl to remove invasive plants. 

• Glyphosate degrades in soil, with an estimated half-life of 30 days. 

• Glyphosate is highly soluble, but adsorbs rapidly and binds tightly to soil. 

• Glyphosate has low leaching potential because it binds so tightly to soil. 

• Modeling results indicate glyphosate runoff is highest in loam soils with peaks 

after the first rainfall. 

Imazapic 

Imazapic is a relatively new herbicide, and there are no studies on the effects of imazapic on 

either soil invertebrates or soil microorganisms. 

• If imazapic was extremely toxic to soil microorganisms, it is reasonable to assume 

that secondary signs of injury to microbial populations would have been reported. 

• Imazapic degrades in soil, with a half-life of about 113 days. 

• Half-life is decreased by the presence of microflora. 

• Imazapic is primarily degraded by microbes and it does not degrade appreciably 

under anaerobic conditions. 

• Imazapic is weakly adsorbed in high soil pH, but adsorption increases with lower 

pH (acidic soils) and increasing clay and organic matter content. 

• Field studies indicate that imazapic remains in the top 12 to 18 inches of soil and 

do not indicate any potential for imazapic to move with surface water. 

• Modeling results indicate imazapic runoff is highest in clay and loam soils with 

peaks after the first rainfall. 

 D-4 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix D-Soil and Water 

• Imazapic percolation is highest in sandy soils. 

Imazapyr 

There are no studies on the effects of imazapyr on soil invertebrates, and incomplete information 

on the effects on soil microorganisms. 

• One study indicates cellulose decomposition, a function of soil microorganisms, 

can be decreased by soil concentrations higher than concentrations expected from 

USDA Forest Service applications. 

• There is no basis for asserting adverse effects to soil microorganisms. 

• Imazapyr degrades in soil, with a half-life of 25 to 180 days. 

• Degradation rates are highly dependent on microbial action. 

• Anaerobic conditions slow degradation. 

• Adsorption increases with time as soil dries and is reversible. 

• Field studies indicate that imazapyr remains in the top 20 inches of soil and do not 

indicate any potential for imazapyr to move with surface water. 

• In forest field studies, imazapyr did not run off and there was no evidence of 

lateral movement. 

• Modeling results indicate imazapyr runoff is highest in clay and loam soils with 

peaks after the first rainfall. 

• Imazapyr percolation is highest in sandy soils 

Metsulfuron methyl 

Studies on the effects of metsulfuron methyl on soil biota are limited to Pseudomonas species, 

though there are a few studies of insects that live in soil. The lowest observed effect concentration 

is 5 mg/kg, based on the Psuedomonas study. At recommended use rates, no effects are expected 

for insects. 

• Effects to soil microorganisms appear to be transient 

• Metsulfuron methyl degrades in soil, with a variable half-life up to 120 days. 

• Half-life is decreased by the presence of organic matter though microbial 

degradation of metsulfuron methyl is slow. 

• Non-microbial hydrolysis is slow at high pH but rapid at lower pH. 

• Adsorption to soil particles, which affects the runoff potential of metsulfuron 

methyl, increased with increased pH and organic matter. 

• Metsulfuron methyl has low adsorption to clay. 

• Modeling results indicate that off-site movement due to runoff could be 

significant in clay soils. 

• Metsulfuron methyl percolates in sandy soils. 

 D-5
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix D-Soil and Water 

Picloram 

Picloram is a restricted use pesticide in the state of Washington, meaning it may only be used by a 

certified applicator (this is also a standard for all herbicide use on the Gifford Pinchot National 

Forest and Columbia River Gorge National Scenic Area). The persistence of picloram increases 

with soil concentration, thus increasing the likelihood that it becomes toxic to soil 

microorganisms in the short-term (1 to 3 years). 

• Since picloram is toxic to microorganisms at low levels, toxic effects can last for 

some time after application. 

• Persistence in soils could affect soil microorganisms by decreasing nitrification. 

• Long-term effects to soil microorganisms are unknown. 

• Picloram applied at a typical application rate is likely to change microbial 

metabolism, though detectable effects to soil productivity are not expected. 

• Field studies have not noted substantial adverse effects associated with the normal 

application of picloram that might be expected if soil microbial activity were 

substantially damaged. 

• Substantial effects to soil productivity from the use of picloram over the last 40 

years have not been noted. 

• Picloram has been studied on a number of soil invertebrates. 

• Metabolites may increase toxicity for some soil microorganisms. 

• Picloram has a typical half-life of 90 days. However, picloram soil degradation 

rates vary in soil, depending on application rate and soil depth. 

• Picloram is water soluble, poorly bound to soils that are low in clays or organics, 

has a high leaching potential, and is most toxic in acidic soil. 

• Picloram should not be used on coarse-textured soils with a shallow water table, 

where groundwater contamination is most likely to occur. 

• Picloram percolation is highest in loam and sandy soils. However, modeling 

results indicate picloram runoff (not percolation) is highest in clay soils. 

Sethoxydim 

Sethoxydim has not been studied on soil invertebrates. 

• Assays of soil microorganisms noted transient shifts in species composition at soil 

concentration levels far exceeding concentrations expected from USDA Forest 

Service application. 

• No adverse effects to soil organisms are expected. 

• Sethoxydim is degraded by soil microbes, with an estimated half-life of 1 to 60 

days. Adsorption of sethoxydim varies with organic material content. 

• Modeling results indicate sethoxydim runoff is highest in clay and loam soils with 

peaks after the first rainfall. 

 D-6 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix D-Soil and Water 

Sulfometuron methyl 

There are no studies on the effects of sulfometuron methyl on soil invertebrates. However, it is 

toxic to soil microorganisms. Microbial inhibition is likely to occur at typical application rates 

and could be substantial. Soil residues may alter composition of soil microorganisms. 

Sulfometuron methyl applied to vegetation at rates to control undesirable vegetation would 

probably be accompanied by secondary changes in the local environment that affect the soil 

microbial community more certainly than direct toxic action of sulfometuron methyl on 

microorganisms. 

• The typical half-life for sulfometuron methyl varies from 10 to 100 days, 

depending on soil texture. Half-life decreases as soil particle size decreases. 

Presence of soil microorganisms also decreases half-life, though microbial 

breakdown occurs slowly. Sulfometuron methyl degradation occurs most rapidly 

at lower pH soils where rates are dominated by hydrolysis. 

• Sulfometuron methyl mobility is generally greater at higher soil pH and lower 

organic matter content. 

• Modeling results indicate sulfometuron methyl runoff is highest in clay and loam 

soils with peaks after the first rainfall. Sulfometuron methyl percolation is highest 

in sandy soils. Monitoring results generally support modeling results. 

• Sulfometuron methyl applied to vegetation at typical application rates would 

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. 

Triclopyr 

The five commercial formulations of triclopyr contain one of two forms of triclopyr, BEE 

(butoxyethyl ester) or TEA (triethylamine). Triclopyr BEE is much more toxic to aquatic 

organisms than triclopyr TEA. A breakdown product, TCP (3,5,6-trichloro-2-pyridinol), is more 

toxic than either form of triclopyr. Site-specific cumulative effects analysis buffer determinations 

need to consider the form of triclopyr used and the proximity of any aquatic triclopyr 

applications, as well as toxicity to aquatic organisms. 

• Triclopyr has not been studied on soil invertebrates. 

• Soil fungi growth was inhibited at concentrations 2 to 5 times higher than 

concentrations expected from USDA Forest Service application rates. 

• Triclopyr has an average half-life in soil of 46 days, while TCP has an average 

half-life in soil of 70 days. Warmer temperatures decrease the time to degrade 

triclopyr. 

• Soil adsorption is increased as organic material increases and decreased as pH 

increases. Triclopyr is weakly adsorbed to soil, though adsorption varies with 

organic matter and clay content. Both light and microbes degrade triclopyr. 

 D-7
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix D-Soil and Water 

 D-8 

Sites with Sensitive Soils Identified 

Sites were identified that have a high risk for either contamination to groundwater or relocation 

by wind for select herbicides. The risk for groundwater contamination is from soluble persistent 

herbicides as detailed in the hydrology analysis. The main risk is for picloram (Tordon K, 22K) 

and sulfometuron methyl (Oust, Oust XP) in soils coarser than loam, and chlorpyralid (Reclaim, 

Curtail, Transline) in loamy sand to sand soils according to herbicide labels. Also, there is a risk 

for wind relocation of chlorsulfuron (Telar, DF, and Glean) if applied on dry fine textured soils; 

chlorsulfuron has strong absorption, especially in clay soils. Where there is high risk, these 

herbicides were excluded from application unless site specific field verification proves lower risk. 

As a coarse guide, the site locations were correlated to soils from completed soil mapping as of 

June 2008 (Terrestrial Ecosystem Unit Survey for Wallowa Whitman NF Unpublished). Soil clay 

content, saturated conductivity and water table depth were key variables used to delineate high 

risk sites. Initially, drainage from shallow bedrock soils was considered, though feedback from 

Forest personnel suggested that risk would be low since most of the bedrock is not extensively 

fractured within range soils that are primarily targeted for chemical treatments (Busskohl 2008, 

personal communication). Soil drainage was also considered within the landscape context. 

Footslope and bottomland soils were deemed higher risk for groundwater contamination than 

upland ridges and steep sideslopes. 

The following sites represent an approximation since these findings rely on geographical 

information system analysis. Ultimately, the infield examination of soil texture and site context 

will prove the most reliable judgment for appropriate herbicide use. Table D-1 below shows 

weed sites with target weed species and appropriate herbicide alternatives. 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 

 Table D- 1 Wallowa Whitman NF chemical treatment sites with greater risk for groundwater contamination and wind trans

Site Plant Code Site Portion Acreage Herbicide1 Herbicide2 Herbicide3 Soi

6160600111 EUES 12 11 Glyphosate Imazapic Excessively Well D

table 

6160700017 CADR 27 6 Chlorsulfuron Imazapic Metsulfuron methyl Excessively Well D

table 

6160600183 CEDI3 134 13 Glyphosate Excessively Well D

table 

6160600049 EUES 2 2 Glyphosate Imazapic Excessively Well D

table 

6160600048 CEDI3 66 64 Glyphosate Excessively Well D

table 

6160600183 CEDI3 134 85 Glyphosate Excessively Well D

table 

6160900092 ONAC 13 9 Chlorsulfuron Metsulfuron methyl Shallow water table 6160600204 CIAR4 8 3 Chlorsulfuron Glyphosate Shallow water table 6160400007 CEMA4 232 47 Glyphosate Well Drained 6160400075 CIAR4 677 47 Chlorsulfuron Well Drained 6160400007 CEMA4 232 50 Glyphosate Well Drained 6160200024 CEDI3 1 1 Glyphosate Shallow water table 6160200141 CEDI3 4 3 Glyphosate Shallow water table 6160200142 CEDI3 1 1 Glyphosate Shallow water table 6160200227 CEMA4 58 11 Glyphosate Shallow water table 6160100154 HYPE 1 1 Metsulfuron methyl Glyphosate Shallow water table 

D-9
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 

 D-10 

Site Plant Code Site Portion Acreage Herbicide1 Herbicide2 Herbicide3 Soi

6160900097 CEDI3 8 8 Glyphosate Shallow water table 6160100076 HYPE 10 4 Glyphosate Well drained 6160100078 CEDI3 2 2 Glyphosate Well drained 6160100071 CYOF 7 3 Chlorsulfuron Imazapic Glyphosate Well Drained 6160500009 LIDA 3 1 

Metsulfuron 

methyl (forested 

sites) 

Imazapic (in 

native grasses) 

Aquatic labeled 

Glyphosate Well Drained 

6160400185 CEDI3 1 1 Glyphosate Well Drained 6160600265 CIAR4 6 6 Chlorsulfuron Well Drained 6160400075 CIAR4 677 42 Chlorsulfuron Well Drained 6160100001 CIAR4 9 5 Chlorsulfuron Well Drained 6160700172 CIAR4 3 3 Chlorsulfuron Glyphosate Shallow water table 6160200054 CYSC4 115 10 Triclopyr Glyphosate Well Drained 6160700123 CEDI3 2 2 Glyphosate Well Drained 6160700075 CYOF 3 3 Chlorsulfuron Imazapic Glyphosate Well Drained 6160700104 CYOF 50 21 Chlorsulfuron Imazapic Glyphosate Well Drained 6160700099 CYOF 10 3 Chlorsulfuron Imazapic Glyphosate Well Drained 6160700109 CYOF 51 45 Chlorsulfuron Imazapic Glyphosate Well Drained 6160900070 CEMA4 3 3 Glyphosate Well Drained 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 

Plant Sit Portion Site Herbicide1 Herbicide2 Herbicide3 Soi

Code e Acreage 

6160900213 CEDI3 2 2 Glyphosate Well Drained 6160900039 CEMA4 23 18 Glyphosate Well Drained 6160600240 CIAR4 88 18 Chlorsulfuron Well Drained 6160600241 CIAR4 9 4 Chlorsulfuron Well Drained 6160600248 CIAR4 28 14 Chlorsulfuron Well Drained 6160600248 CIAR4 28 5 Chlorsulfuron Well Drained 6160900108 LIDA 10 10 

Metsulfuron 

methyl (forested 

sites) 

Imazapic (native 

grasses) 

Aquatic labeled 

Glyphosate Clay 

6160900002 LIDA 50 37 

Metsulfuron 

methyl (forested 

sites) 

Imazapic (native 

grasses) 

Aquatic labeled 

Glyphosate Clay 

6160200007 CIAR4 50 22 Chlorsulfuron Glyphosate Shallow water table 6160900105 EUES 14 8 Picloram Glyphosate Imazapic Clay 6160600250 CIAR4 1 1 Chlorsulfuron Well Drained 6160600240 CIAR4 88 15 Chlorsulfuron Well Drained 6160400007 CEMA4 232 25 Glyphosate Well Drained 6160400007 CEMA4 232 13 Glyphosate Well Drained 6160400075 CIAR4 677 25 Chlorsulfuron Well Drained 6160400007 CEMA4 232 20 Glyphosate Well Drained 

D-11
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 

 D-12 

Site Plant Code Site Portion Acreage Herbicide1 Herbicide2 Herbicide3 Soi

6160600199 EUES 6 3 Glyphosate Imazapic Well Drained 6160600349 PORE5 9 5 Metsulfuron methyl Well Drained 6160900156 CIAR4 7 5 Chlorsulfuron Well Drained 6160900109 ONAC 9 7 Clopyralid Chlorsulfuron Metsulfuron Well Drained 6160900100 ONAC 10 5 Clopyralid Chlorsulfuron Metsulfuron Well Drained 6160900155 CYOF 7 7 Chlorsulfuron Imazapic Glyphosate Well Drained 6160900231 CADR 3 2 Chlorsulfuron Imazapic Metsulfuron methyl Well Drained 6160900027 CADR 10 3 Chlorsulfuron Imazapic Metsulfuron methyl Well Drained 6160900036 CEMA4 18 16 Glyphosate Well Drained 6160900157 CIAR4 7 4 Chlorsulfuron Well Drained 6160600216 CYOF 40 12 Chlorsulfuron Imazapic Glyphosate Well Drained 6160900056 CADR 10 5 Chlorsulfuron Imazapic Metsulfuron methyl Well Drained 6160700116 CEDI3 6 3 Glyphosate Well Drained 6160700052 CEDI3 13 8 Glyphosate Well Drained 6160700119 HYPE 1 1 Glyphosate Well Drained 6160700109 CYOF 51 6 Chlorsulfuron Imazapic Glyphosate Well Drained 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 

Plant Sit Portion Site Herbicide1 Herbicide2 Herbicide3 Soi

Code e Acreage 

6160700006 CADR 6 2 Chlorsulfuron Imazapic Metsulfuron methyl Well Drained 6160700078 CYOF 6 5 Chlorsulfuron Imazapic Glyphosate Well Drained 6160700076 CADR 1 1 Chlorsulfuron Imazapic Metsulfuron methyl Well Drained 6160700105 PORE5 3 3 Metsulfuron methyl Well Drained 6160700034 CIAR4 16 11 Chlorsulfuron Well Drained 6160700104 CYOF 50 29 Chlorsulfuron Imazapic Glyphosate Well Drained 6160700074 CADR 1 1 Chlorsulfuron Imazapic Metsulfuron methyl Well Drained 6160700033 CADR 20 9 Chlorsulfuron Imazapic Metsulfuron methyl Well Drained 6160700048 CEDI3 9 6 Glyphosate Well Drained 6160700061 TACA8 914 88 Imazapic Sethoxydim Glyphosate Well Drained 6160700027 CEDI3 30 23 Glyphosate Well Drained 6160700010 CEDI3 75 18 Glyphosate Well Drained 6160700091 CEDI3 3 2 Glyphosate Well Drained 6160700061 TACA8 914 53 Imazapic Sethoxydim Glyphosate Well Drained 6160700061 TACA8 914 33 Imazapic Sethoxydim Glyphosate Well Drained 6160600189 CEDI3 2 2 Clopyralid Picloram Glyphosate Clay 

D-13
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

 

 D-14 

Site Plant Code Site Portion Acreage Herbicide1 Herbicide2 Herbicide3 Soi

6160700033 CADR 20 8 Chlorsulfuron Imazapic Metsulfuron methyl Well Drained 6160700047 CADR 19 13 Chlorsulfuron Imazapic Metsulfuron methyl Well Drained 6160700012 CADR 6 3 Chlorsulfuron Imazapic Metsulfuron methyl Well Drained 6160700065 CEDI3 20 13 Glyphosate Well Drained 6160700145 PORE5 1 1 Metsulfuron methyl Well Drained 6160700062 CADR 8 8 Chlorsulfuron Imazapic Metsulfuron methyl Well Drained 6160700010 CEDI3 75 25 Glyphosate Well Drained 6160700055 CEDI3 9 9 Glyphosate Well Drained 6160100014 CEDI3 79 11 Glyphosate Well Drained 6160100058 CEDI3 20 6 Glyphosate Well Drained 6160100144 HYPE 2 2 Glyphosate Well Drained 
Appendix E – Aquatics 

List of Roads with Proposed Chemical Treatments within 100 

Feet of a Fish-Bearing Stream 

Effects of Active Ingredients in Herbicide to Aquatic 

Organisms 

INFISH goals and strategies adopted into the Forest Plan 

 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

This page left blank intentionally 

 

 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix E-Aquatics 

List of Roads with Proposed Chemical Treatments within 100 

Feet of a Fish-Bearing Stream 

Table E- 1- List of roads proposed for herbicide treatment within 100 feet of Class 1 & 2 Streams 

5th Field 

Watershed Stream Road ID 

Miles of 

road 

proposed 

for herbicide 

treatment 

within 100 

feet of Class 

1 & 2 

Streams 

TES Fish 

Species 

Present at 

Site 

TES Fish 

Species 

Present in 

Watershed 

Little Bear 

Saddle (8250) 1.30 SRS, BT 

8250060 0.05 SRS, BT 

8250134 0.01 SRS, BT 

8250000 1.87 SRS, BT 

8250060 0.05 SRS, BT 

Little Bear Creek 

8250134 0.01 BT 

Bear Creek 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams = 

3.33 Bear Creek 8250040 0.04 SRC, SRS, 

BT 

SRC, SRS, 

BT 

6700000 0.49 Big Creek 7055000 0.04 

Burn Creek 7055000 0.07 

Unnamed Trib to 

Velvet Creek 6700533 0.004 

6700791 0.004 

Velvet Creek 6700800 0.36 

6700881 0.01 

Big Creek 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams = 

1.00 Unnamed Trib to 

Big Creek 7746000 0.03 

NF 

1125055 0.03 Cornet Creek 1125050 1.29 

1110000 0.05 

1110165 0.34 

1110180 0.003 Auburn Creek 

1115000 0.02 

1115000 1.18 

1115070 0.003 Unnamed Trib to 

Auburn Creek 

1118040 0.02 

1115090 0.095 Mill Creek OR-245 0.79 

Burnt 

River/Auburn 

Creek 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams = 

4.84 

Unnamed Trib to 

Burnt River 1118000 1.02 

NF 

East Camp 1600000 0.05 

Creek 1600970 0.10 

1680000 0.09 

1680500 0.09 South Fork West 

Camp Creek 1680510 0.002 

1684000 0.05 

Camp Creek 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class Unnamed Trib to 

King Creek 1684245 0.06 

NF 

 E-1
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix E-Aquatics 

 E-2 

 

5th Field 

Watershed Stream Road ID 

Miles of 

road 

proposed 

for herbicide 

treatment 

within 100 

feet of Class 

1 & 2 

Streams 

TES Fish 

Species 

Present at 

Site 

TES Fish 

Species 

Present in 

Watershed 

1 & 2 Streams = 

0.44 

4600000 0.14 SRS 

4600185 0.07 SRS 

4600930 0.01 SRS 

Chesnimnus 

Creek 

4625423 0.004 SRS 

Unnamed Trib to 

Chesnimnus 

Creek 

4600975 0.01 

West Fork 

Peavine Creek 4665000 0.32 SRS 

Chesnimnus 

Creek 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams = 

0.57 Devils Run 

Creek 4695000 0.02 SRS 

SRS 

7015000 0.09 Eagle Creek 7700000 0.72 

Unnamed Trib to 

Eagle Creek 7015150 0.002 

7700000 1.28 Long Creek 7730000 0.003 

7700150 0.01 

Summit Creek 7715000 0.18 

7715020 0.01 

7700340 0.004 

7700360 0.01 

7700375 0.004 Paddy Creek 

7735000 0.08 

Packsaddle 

Creek 7700350 0.004 

7700400 0.03 O’Brien Creek 7750000 0.01 

7720000 0.31 

7735000 0.63 

7735375 0.11 

7735385 0.08 

Little Eagle 

Creek 

7735402 0.07 

Eagle Creek 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams = 

3.67 

East Fork Eagle 

Creek 7745000 0.03 

NF 

2100680 0.01 SRS 

2145000 0.01 South Fork 

Spring Creek 2145031 0.001 

Spring Creek 2100736 0.01 SRS 

Grande Ronde 

River/Beaver 

Creek 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams = 

Grande Ronde 

River 2440055 0.02 SRC, SRS, 

BT 

SRC, SRS, 

BT 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix E-Aquatics 

Miles of 

road 

proposed TES Fish TES Fish for herbicide 5th Field 

Watershed Stream Road ID treatment 

within 100 

feet of Class 

1 & 2 

Streams 

Species Species 

Present at Present in 

Site Watershed 

0.05 

Grande Ronde 

River/Five Points 

Creek 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams = 

0.04 

Pelican Creek 3106970 0.04 SRS SRC, SRS 

Grande Ronde 

River/Mud Creek 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams 

=0.44 

Wildcat Creek OR99063-501 0.44 SRC, SRS SRC, SRS 

P 0.01 MCC, 

MCS, RT 

FS-22 0.001 MCC, 

MCS, RT 

7300755 0.01 MCC, 

MCS, RT 

7300770 0.01 MCC, 

MCS, RT 

7300772 0.01 MCS, RT 

7300773 0.01 MCS, RT 

7370000 0.02 MCS, RT 

7375000 0.04 MCS, RT 

Bull Run Creek 

OR99023-24 2.35 MCC, 

MCS, RT 

Olive Creek 1305000 0.02 MCS, RT 

1900000 0.04 MCS Beaver Creek 4305270 0.004 MCS 

7300000 0.25 MCC, 

MCS, RT 

7300795 0.003 MCC, 

MCS, RT 

Granite Creek 

7355070 0.004 MCS, RT 

Granite Creek 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams = 

2.46 

Last Chance 

Creek 7355011 0.08 MCS, RT 

MCC, MCS, 

RT, BT 

4300000 0.20 

4300030 0.37 

Ladd Creek 

Total miles 

Unnamed Trib to 

Ladd Creek 

4300040 0.01 

SRS 

 E-3
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix E-Aquatics 

 E-4 

 

5th Field 

Watershed Stream Road ID 

Miles of 

road 

proposed 

for herbicide 

treatment 

within 100 

feet of Class 

1 & 2 

Streams 

TES Fish 

Species 

Present at 

Site 

TES Fish 

Species 

Present in 

Watershed 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams = 

0.65 

Ladd Creel 4300034 0.07 

FS-129 0.17 SRS 

3520000 2.08 SRS 

Lower Big Sheep 

Creek 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams = 

2.26 

Unnamed Trib to 

Little Sheep 

Creek 3520600 0.01 SRS 

SRC, SRS, 

BT 

Rhodes Creek 

Ranch 1 0.70 SRC, SRS 

Lightning Creek Rhodes Creek 

Ranch 2 0.02 SRC, SRS 

FS-103 0.01 SRC, SRS Cow Creek 4260000 0.01 SRC, SRS 

Lower Imnaha 

River 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams = 

0.78 

Horse Creek FS-104 0.04 

SRC, SRS 

Lower Joseph 

Creek 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams = 

0.02 

Horse Creek OR99063-699 0.02 SRS 

Deer Creek 8270000 0.41 SRS, BT 

Lower Wallowa 

River 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams = 

0.63 

Sage Creek 8270050 0.22 SRS 

SRC, SRS, 

BT 

Spring Creek 2100000 0.05 SRS 

McCoy Creek 2100000 0.05 SRS 

Unnamed Trib to 2125000 0.09 

McCoy Creek 2125230 0.01 

Meadow Creek 

Total miles 

proposed for 

herbicide 

South Fork 2100000 0.06 SRS 

SRC, SRS 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix E-Aquatics 

Miles of 

road 

proposed TES Fish TES Fish for herbicide 5th Field 

Watershed Stream Road ID treatment 

within 100 

feet of Class 

1 & 2 

Streams 

Species Species 

Present at Present in 

Site Watershed 

Spring Creek 

Waucup Creek 2100000 0.04 SRS 

2100000 0.04 SRS Meadow Creek 2120000 0.01 SRS 

Unnamed Trib to 2135000 0.04 SRS 

Meadow Creek 2135700 0.01 SRS 

210000 0.04 SRS Peet Creek 2100130 0.01 SRS 

2444000 0.74 SRS 

treatment within 

100 feet of Class 

1 & 2 Streams = 

1.26 

Burnt Coral 

Creek OR-244 0.08 SRS 

4200200 0.05 SRC, SRS, 

BT 

Middle Imnaha 

River 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams = 

0.78 

Imnaha River 

OR99063-727 0.73 SRC, SRS, 

BT 

SRC, SRS, 

BT 

1040020 0.01 

1900280 0.02 

1900281 0.03 

OR99001-503B 0.24 

North Fork Burnt 

River 

OR-99001-529 0.64 

1044065 0.02 Geiser Creek 1044120 0.01 

1060260 0.04 

Gimlet Creek 7386000 0.96 

7386535 0.03 

1200100 0.02 

2646000 0.19 

2646700 0.14 

Middle Fork 

Burnt River 

2665000 0.03 

1900160 0.01 Sheep Creek 1900268 0.03 

China Creek 1910000 0.03 

1940000 0.02 Mosquito Creek 1940101 0.04 

North Fork Burnt 

River 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams = 

2.51 

South Sister 

Creek 2695250 0.004 

NF 

Antone Creek 7300000 0.08 

Unnamed Trib to 

Antone Creek 7300100 0.05 

North Powder 

River 

Total miles 

proposed for 

Little Antone 

Creek 7302000 0.08 

BT 

 E-5
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix E-Aquatics 

 E-6 

 

5th Field 

Watershed Stream Road ID 

Miles of 

road 

proposed 

for herbicide 

treatment 

within 100 

feet of Class 

1 & 2 

Streams 

TES Fish 

Species 

Present at 

Site 

TES Fish 

Species 

Present in 

Watershed 

North Fork 

Antone Creek 7312000 0.02 BT 

Anthony Creek 7312065 0.34 BT 

North Fork 

Anthony Creek 7312190 0.04 BT 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams = 

0.62 

Dutch Creek 7312400 0.01 

3900000 1.60 

3900640 0.004 

3900668 0.01 

North Pine 

Creek 

3900671 0.001 

Lake Fork Creek 3900750 0.01 

6600100 0.07 BT 

6617000 0.05 BT 

6625270 0.01 East Pine Creek 

OR99001-1009 0.13 

6615075 0.01 

Beecher Creek 6617097 0.01 

6625160 0.07 

Pine Creek 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams = 

2.00 

Pine Creek OR-413 0.02 

BT 

6510000 0.21 

6510020 0.08 

6510100 0.10 Marble Creek 

6510110 0.005 

6530000 0.14 

Deer Creek 6530100 0.11 

6540000 0.17 

6540030 0.14 Lake Creek 6540090 0.05 BT 

West Fork Lake 

Creek 6540097 0.07 

Powder 

River/Rock Creek 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams = 

1.37 

Larkspur Creek 7000250 0.29 

BT 

Unnamed Trib to 7020033 0.002 

Goose Creek 7000200 0.08 

7000000 4.00 

7000270 0.002 

7025000 1.28 

7025020 0.11 

7025105 0.03 

7025130 0.04 

Goose Creek 

7025170 0.01 

East Fork Goose 7000332 0.02 

Creek 7000390 0.27 

Sawmill Creek 7025140 0.95 

Powder 

River/Ruckles 

Creek 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams = 

7.81 

Balm Creek 7040000 1.02 

NF 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix E-Aquatics 

Miles of 

road 

proposed TES Fish TES Fish for herbicide 5th Field 

Watershed Stream Road ID treatment 

within 100 

feet of Class 

1 & 2 

Streams 

Species Species 

Present at Present in 

Site Watershed 

2200B 0.01 

2200100 0.06 

2200100A 0.01 

2200150 0.01 

Powder River 

OR-7 0.52 

7225000 0.11 

7225500 0.33 

Powder 

River/Sutton 

Creek 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams = 

1.05 

Elk Creek 

7225700 0.002 

NF 

Wolf Creek 4315000 0.13 

4320000 0.08 

Powder 

River/Wolf Creek 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams = 

0.21 

East Fork Clear 

Creek 4320180 0.001 

NF 

Cherry Creek 4600788 0.03 

Jim Creek 4680250 0.09 

Snake 

River/Cherry 

Creek 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams = 

0.27 

Cache Creek 4680500 0.15 SRS 

SRC, SRS 

Snake 

River/Granite 

Creek 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams = 

0.02 

Hells Canyon 

Creek 3810000 0.02 SRS SRC, SRS, BT, WCT 

99049-493 0.05 BT Kurry Creek 493A1 0.05 

Temperance 

Creek FS-78 0.03 SRS 

Big Canyon 

Cree 1805 0.001 

Snake 

River/Temperance 

Creek 

Total miles 

proposed for 

herbicide 

treatment within Kirkwood Creek 2062 1.34 SRS 

SRC, SRS, 

BT 

 E-7
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix E-Aquatics 

Miles of 

road 

proposed 

for herbicide 

treatment 

within 100 

feet of Class 

1 & 2 

Streams 

TES Fish 

Species 

Present at 

Site 

TES Fish 

Species 

Present in 

Watershed 

5th Field 

Watershed Stream Road ID 

100 feet of Class 

1 & 2 Streams = 

1.47 

1695000 0.13 Amelia Creek 1695300 0.003 

Last Chance 2640000 0.03 

Creek 2640745 0.02 

South Fork 6005000 0.06 

Burnt River 6005432 0.02 

6005000 0.04 

South Fork Burnt 

River 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams = 

0.32 

Unnamed Trib to 

South Fork 

Burnt River 6005415 0.02 

NF 

FS-131 1.18 SRC, SRS, 

Big Sheep BT 

Creek 3900100 0.01 SRC, SRS, 

BT 

Unnamed Trib to 3900000 0.17 BT 

Salt Creek 3900060 0.01 BT 

3900000 0.04 SRC, SRS, 

BT 

3900170 0.08 SRC, SRS, 

BT 

3925000 0.55 SRC, SRS, 

BT 

Upper Big Sheep 

Creek 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 

Streams = 2.05 

Lick Creek 

3925015 0.01 SRC, SRS, 

BT 

SRC, SRS, 

BT 

Upper Catherine 

Creek 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams 

=0.08 

South Fork 

Catherine Creek 7706000 0.08 SRC, SRS, BT 

SRC, SRS, 

BT 

Unnamed Trib to 

Grande Ronde 

River 

4305000 0.01 SRC, SRS, 

BT 

5100000 3.47 SRC, SRS, 

BT 

5100035 0.01 SRC, SRS, 

BT 

5100045 0.003 SRC, SRS, 

BT 

5100055 0.005 SRC, SRS, 

BT 

Upper Grande 

Ronde River 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams = 

3.97 

Grande Ronde 

River 

5100100 0.04 SRC, SRS, 

SRC, SRS, 

BT 

 E-8 

 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix E-Aquatics 

Miles of 

road 

proposed 

for herbicide 

treatment 

within 100 

feet of Class 

1 & 2 

Streams 

TES Fish 

Species 

Present at 

Site 

TES Fish 

Species 

Present in 

Watershed 

5th Field 

Watershed Stream Road ID 

BT 

5100110 0.02 SRC, SRS, 

BT 

5100195 0.02 SRC, SRS, 

BT 

5115000 0.02 SRC, SRS, 

BT 

Unnamed Trib to 

Dry Beaver 

Creek 

5110210 0.05 SRS 

Whitehorse 

Creek 5110300 0.02 SRC, SRS, BT 

Limber Jim 

Creek 5130102 0.01 SRC, SRS, 

BT 

Meadowbrook 5178080 0.03 

Creek 5178095 0.01 

5182000 0.25 SRC, SRS Sheep Creek 5182640 0.01 SRC, SRS 

Gumboot Creek 3900000 2.41 SRS 

3900000 1.49 SRC, SRS, 

BT 

3900440 0.03 SRC, SRS, 

BT 

3900450 0.003 SRC, SRS, 

BT 

3955000 0.34 SRC, SRS, 

BT 

3955020 0.12 SRC, SRS, 

BT 

3960000 1.08 SRC, SRS, 

BT 

3960020 0.01 SRC, SRS, 

BT 

3960300 0.01 SRC, SRS, 

BT 

Imnaha River 

3960400 0.10 SRC, SRS, 

BT 

North Fork 

Gumboot Creek 3900400 0.01 SRS 

3900453 0.003 SRS 

3900455 0.01 SRS 

3900485 0.01 Dry Creek 

3965000 0.03 

Skookum Creek 3925000 0.05 SRS 

Upper Imnaha 

River 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams = 

5.78 

Crazyman Creek 3965125 0.07 

SRC, SRS, 

BT 

Upper Joseph 4600000 0.26 SRS 

Creek Elk Creek X19934600115 0.003 SRS 

SRS 

 E-9
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix E-Aquatics 

Miles of 

road 

proposed 

for herbicide 

treatment 

within 100 

feet of Class 

1 & 2 

Streams 

TES Fish 

Species 

Present at 

Site 

TES Fish 

Species 

Present in 

Watershed 

5th Field 

Watershed Stream Road ID 

Little Elk Creek 4600155 0.11 SRS 

4600190 0.02 SRS Cougar Creek 4600220 0.02 SRS 

Sumac Creek 4600347 1.20 SRS 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams = 

1.63 

Unnamed Trib to 

Elk Creek 4610000 0.02 SRS 

Hoodoo Creek 5185010 0.004 

7300000 0.06 

7300380 0.003 

Upper North Fork 

John Day River 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams = 

0.07 

Unnamed Trib to 

North Fork John 

Day River 7300409 0.006 

MCC, MCS, 

BT, RT 

Little Dean 

Creek 1100460 0.003 

2200900 0.19 

2200910 0.04 

7390000 0.03 

7390500 0.01 

7395000 0.01 

McCully Fork 

OR9901-520 1.03 

Clear Creek 2200000 0.09 

2225000 0.55 

Union Creek 7220420 0.002 

OR-7 0.05 

Unnamed Trib to 

McCully Fork 7300900 0.02 

OR99001-550 0.02 

Upper Powder 

River 

Total miles 

proposed for 

herbicide 

treatment within 

100 feet of Class 

1 & 2 Streams = 

2.12 

Cracker Creek OR99001-553 0.07 

BT 

 E-10 

 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix E-Aquatics 

Effects of Active Ingredients in Herbicide to Aquatic 

Organisms 

The most sensitive effect from the most sensitive species tested was used to determine the 

toxicity indices for each herbicide. Quantitative estimates of dose from each exposure scenario 

were compared to the corresponding toxicity index to determine the potential for adverse effect. 

Doses below the toxicity indices resulted in discountable effects. Table E-2 lists the toxicity 

indices for fish used for the R6 2005 FEIS BA. Values in bold are the values used to assess risk 

to fish from acute exposures. Indices represent the most sensitive endpoint from the most 

sensitive species for which adequate data are available. Numbers in bold indicate the toxicity 

index used in calculating the hazard quotient for exposures to listed fish. Generally, the lowest 

toxicity index available for the species most sensitive to effects was used. Measured chronic data 

(NOEC) was used when they were lower than 1/20th of an acute LC50 because they account for 

at least some sublethal effects, and doses that are protective in chronic exposures are more certain 

to be protective in acute exposures. 

Table E- 2 - Toxicity Indices for Fish Used for the R6 2005 FEIS 

Herbicide Duration Endpoint Dose Species 

Effect Noted at LOAEL 

(Lowest Observable 

Adverse Effect Level) 

Acute NOEC * 2 mg/L (1/20th

of LC50) Brown trout LC50 at 40 mg/L 

Chlorsulfuron 

Chronic NOEC1 3.2 mg/L Brown trout rainbow trout length 

affected at 66mg/L 

Acute NOEC 5 mg/L (1/20th

of LC50) 

Rainbow 

trout LC50 at 103 mg/L Clopyralid 

Chronic none available 

Acute NOEC 0.5 mg/L

(1/20th/LC50) 

Rainbow 

trout LC50 at 10 mg/L 

Glyphosate (no 

surfactant) Chronic NOEC 2.57 mg/L2 Rainbow 

trout 

Life-cycle study in 

minnows; LOAEL not 

given 

Acute NOEC 

0.065 mg/L

(1/20th of 

LC50) 

Rainbow 

trout 

LC50 at 1.3 mg/L for 

fingerlings (surfactant 

Glyphosate with formulation) 

POEA surfactant 

Chronic NOEC 0.36 mg/L salmonids 

estimated from full lifecycle study of minnows 

(surfactant formulation) 

Acute NOEC 100 mg/L all fish at 100 mg/L, no 

statistically sig. mortality Imazapic 

Chronic NOEC 100 mg/L fathead 

minnow 

No treatment related 

effects to hatch or growth 

Acute NOEC 5 mg/L (1/20th 

LC50) 

trout, 

catfish, 

bluegill 

LC50 at 110-180 mg/L for 

North American species 

Imazapyr 

Chronic NOEC 43.1 mg/L Rainbow 

“nearly significant” effects 

on early life stages at 92.4 

mg/L 

Acute NOEC 10 mg/L Rainbow lethargy, erratic swimming 

Metsulfuron methyl at 100 mg/L 

Chronic NOEC 4.5 mg/L Rainbow standard length effects at 

 E-11
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix E-Aquatics 

 E-12 

 

Herbicide Duration Endpoint Dose Species 

Effect Noted at LOAEL 

(Lowest Observable 

Adverse Effect Level) 

8 mg/L 

Acute NOEC 0.04 mg/L

(1/20th LC50) 

Cutthroat 

trout LC50 at 0.80 mg/L 

Picloram 

Chronic NOEC 0.55 mg/L Rainbow 

trout 

body weigh and length of 

fry reduced at 0.88 mg/L 

Acute NOEC 0.06 mg/L

(1/20th LC50) 

Rainbow 

trout LC50 of Poast at 1.2 mg/L Sethoxydim 

Chronic NOEC none available 

Acute NOEC 7.3 mg/L Fathead 

minnow 

No signs of toxicity at 

highest doses tested Sulfometuron 

methyl Chronic NOEC 1.17 mg/L Fathead 

minnow 

No effects on hatch, 

survival or growth at 

highest doses tested 

Acute NOEC 0.26 mg/L

(1/20th LC50) 

Chum 

salmon LC50 at 5.3 mg/L3

Triclopyr acid 

Chronic NOEC 104 mg/L Fathead 

minnow 

Reduced survival of 

embryo/larval stages at 

140 mg/L 

Acute -- 0.012 mg/L Bluegill 

sunfish LC50 at 0.25 mg/L 

Triclopyr BEE 

Chronic4 NOEC 104 mg/L Fathead 

minnow 

Reduced survival of 

embryo/larval stages at 

140 mg/L 

Acute5 NOEC 0.2 mg/L

(1/20th LC50) 

fathead 

minnow, 

rainbow 

trout 

LC50 at 4.0 mg/L NPE Surfactants 

Chronic6 NOEC 1.0 mg/L trout no LOEL given 

1 Chronic value for brown trout (sensitive sp.) was estimated using relative potency in acute and chronic values for rainbow 

trout, and the acute value for brown trout. 

2 Estimated from minnow chronic NOEC using the relative potency factor method (SERA Glyphosate 2003). 

3 Using Wan et al. (1989) value for lethal dose. 

4 Chronic and subchronic data for triclopyr are limited to triclopyr TEA. No data is available for triclopyr BEE. 

5 Exposure includes small percentage of NP and NP1-2E (Bakke, 2003). 

6 Chronic exposure is from degredates NP1EC and NP2EC, because NPE breaks down rapidly and NPEC’s are more 

persistent (Bakke, 2003). 

Indices represent the most sensitive endpoint from the most sensitive species for which adequate data are available. 

Numbers in bold indicate the toxicity index used in calculating the hazard quotient for exposures to listed fish. Generally, the 

lowest toxicity index available for the species most sensitive to effects was used. Measured chronic data (NOEC) was used 

when they were lower than 1/20th of an acute LC50 because they account for at least some sublethal effects, and doses that 

are protective in chronic exposures are more certain to be protective in acute exposures. 

*NOEC = No Observed Effect Concentration 

Results of the exposure scenarios as applied to listed fish on the Wallowa-Whitman National 

Forest are displayed in E-3. The R6 2005 FEIS Fish BA displayed the results by placing stars (*) 

and diamonds (♦) where there was an exceedence in the level of concern (LOC). For purposes of 

this BA, the table of stars and diamonds has been modified to show the hazard quotients (HQ) 

value in order to exemplify the magnitude of difference between typical and high application 

rates, and aquatic and non-aquatic formulations. The cells that contain a slash and no number 

mean that there was no exceedence in level of concern (LOC). 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix E-Aquatics 

The LOC exceedences occur when the HQ value exceeds 1. Exceedences in LOC indicate 

occasions where the expected exposure concentration (EEC) is greater than the no observable 

effect concentration (NOEC) value used for that aquatic species group, which may lead to an 

indirect effect to listed aquatic species if conditions were similar to what was modeled in the 

SERA risk assessments. To calculate an HQ, simply take the ratio of EEC/NOEC values. Toxicity 

indices used in the R6 2005 FEIS for aquatic organisms are NOEC values, refer to table above. 

Two types of indirect effects are possible, those toxic to the listed aquatic species, and those 

mediated by toxic effects to an ecosystem component that is part of the Primary Constituent 

Elements (PCE) or associated essential habitat features. 

Table E- 3 - Hazard Quotient Values for Acute Exposure Estimates for Sensitive Aquatic Organisms 

from the R6 2005 FEIS Broadcast Spray Scenarios 

Aquatic 

Species 

Group 

Application 

Rate 

Chlorsulfuron 

Clopyralid 

Glyphosate w/o 

surfactant8* 

Glyphosate w/ 

surfactant 

Imazapic 

Imazapyr** 

Metasulferon 

Methyl 

Picloram 

Sethoxydin 

Sulfometeron 

Methyl 

Triclopyr TEA* 

Triclopyr BEE 

NPE Surfactant 

High -- -- 6 43 -- -- -- 5 3 -- 15 125 -- Fish 

Typical -- -- 2 12 -- -- -- 2 2.5 -- 1.5 13 -- 

Aquatic High -- -- -- 2.5 -- -- -- -- -- -- -- 1.8 -- 

Invertebrate Typical -- -- -- -- -- -- -- -- -- -- -- -- -- 

High 5 -- -- 3.1 -- 5 -- -- -- 3 9.5 214 -- Algae Typical -- -- -- -- -- 2 -- -- -- -- -- 21 -- 

Aquatic High 1064 -- -- -- 1.4 8 9 2 -- 36 9.5 214 -- 

Macrophytes Typical 234 -- -- -- -- 3 2 -- 4 21 

‘--’ Predicted concentrations less than or equal to the estimated or measured ‘no observable effect concentration’ at both 

typical and high application rates. 

‘*’ Aquatic formulations analyzed in the R6 2005 FEIS. 

The exposure scenarios do not account for factors such as timing of application, animal behavior 

and feeding strategies, animal presence within a treatment area, or other relevant factors such as 

site-specific conditions. However, the SERA risk assessments do represent a worst-case scenario 

that is a good benchmark for assessing true concerns with actual application. Results of triclopyr 

exposures take into account the strict limitations on use identified in the forest plan standards, 

which makes the exposure scenarios implausible or impossible. Table E-3 displays the results of 

exposure if all “worst-case” conditions reflected in the scenario occur, which is highly unlikely 

for Wallowa-Whitman National Forest. 

Chronic and Acute Exposures 

The toxicity metric values (estimated or measured NOEC values) used in the R6 2005 FEIS 

analyses were selected as the most likely to protect against sub-lethal effects. For assessing 

potential risk to listed fish, while accounting for uncertainty regarding sub-lethal effects, the 

1/20th of the acute LC50 (U.S. EPA 2004) or a lower chronic NOEC value was used for the acute 

toxicity index. Therefore, a LOC exceedence listed in Table E-3 represents at least a greater than 

discountable risk of sub-lethal effects at the R6 2005 FEIS scale. For the action alternatives, 

effects analysis tiers to the results of the R6 2005 FEIS for chronic and acute exposures, and 

 E-13
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix E-Aquatics 

analyzes the potential for more than a discountable risk of sub-lethal effects as well as indirect 

effects from impacts to the food web. 

Results of the R6 2005 FEIS analysis indicates that chronic exposures to fish are not plausible, in 

other words not mathematically possible. Therefore, chronic exposures to fish for the action 

alternatives are unlikely to occur. It is safe to assume that it is highly unlikely to reach a LOC for 

chronic exposures herbicide treatments on UNF. 

The R6 FEIS identified three herbicides that mathematically exceeded the LOC for aquatic 

plants: Imazapyr, Metsulfuron, and Chlorsulfuron. The R6 2005 FEIS concluded that exposure of 

aquatic plants to chronic toxicity concentrations of imazapyr may be mathematically possible, but 

not plausible. Therefore, it is not plausible for the action alternatives to result in chronic toxicity 

of imazapyr for aquatic plants. For metsulfuron, the peak modeled stream concentration reported 

in the SERA risk assessment is 0.006 mg/l, which is approximately equal to the 0.005 mg/l that 

was calculated as the mathematically highest possible average stream concentration (with direct 

input). This indicates that the true 21 day concentration for non-fish species is likely much lower. 

Based on this, it is unlikely that exposure to chronic toxicity of metsulfuron to plants will occur 

for the action alternatives, even if there were no buffers. 

The risk assessment for chlorsulfuron lists the highest average modeled stream concentration as 

0.0022 mg/l, approximately 46 times higher than the estimated acute NOEC of 0.000047 mg/l. 

However, chronic toxicity to plants is unlikely to occur for the action alternatives because of 

Project Design Features that limit broadcasting chlorsulfuron. 

The effects analysis for this EIS focus on the probability and magnitude of acute exposures from 

herbicide treatments based on results from the SERA risk assessments. It must be made clear that 

the risk categories for herbicides identified in the R6 2005 FEIS Fish BA is risk to aquatic 

organisms (fish, invertebrates, algae, aquatic macrophytes) among the herbicides analyzed for the 

R6 2005 ROD. The herbicides analyzed in the R6 2005 FEIS were compared to each other and 

placed in a risk level category according to results from worst-case acute exposure scenario used 

in the SERA risk assessments. Herbicides analyzed in the R6 2005 FEIS were displayed in the 

following category of risk: 

• Lowest risk: results from SERA risk assessments indicated no risk or a plausible risk to 

aquatic macrophytes only (includes chlopyralid, imazapic and metsulfuron methyl), 

• Moderate risk: results from SERA risk assessments indicated a plausible risk to algae or 

invertebrates, in addition to plants (includes chlorsulfuron, imazapyr and sulfometeron 

methyl), 

• Highest risk: results from SERA risk assessments indicated a plausible risk to fish which 

may or may not be a risk to algae, invertebrates, or macrophytes (includes sethoxydim, 

picloram, non-aqueous glyphosate and triclopyr). 

The lowest risk group contains those herbicides for which LOCs were either not exceeded, or 

only exceeded the LOC for aquatic macrophytes. The moderate risk group contains those 

herbicides for which LOCs were exceeded for two aquatic species groups other than fish. The 

higher risk group contains those herbicides for which LOCs for fish were exceeded. 

The ability of herbicides to come in contact with water once in the soil depends on complex 

toxicological properties and environmental parameters. A discussion of herbicide characteristics 

in soil is discussed in the Watershed Analysis for this project. Understanding how the herbicide 

reacts in soil helps in understanding the probability of adverse effects to aquatic organisms should 

 E-14 

 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix E-Aquatics 

the herbicide come in contact with water. These characteristics were considered for the analysis 

of effects from the action alternatives on federally listed and sensitive fish and their habitat. 

Clopyralid (Lowest Risk Category) 

Studies of clopyralid effects on soil invertebrates have been conducted, including field studies on 

the effects to microorganisms. 

• Soil concentrations from USDA Forest Service applications are expected to be 1,000 less 

than concentrations that would cause toxic effects. Therefore, no effects to soil 

invertebrates or microorganisms are expected from use of clopyralid. 

• Clopyralid is degraded by soil microbes, with an estimated half-life of 14 to 29 days, 

meaning that one-half of the amount applied remains in the soils after 90 days, one-fourth 

of the applied amount remains after 28 to 58 days, one –eight after 42 to 87 days, and so 

on. 

• Increased soil moisture decreases degradation time. 

• Clopyralid is weakly adsorbed and has a moderate leaching potential overall but high 

leaching potential in sandy soils. 

Modeling results indicate clopyralid runoff is highest in clay soils with peaks after rainfall events. 

Clopyralid percolation is highest in sandy loam soils. There is no probability of exceeding levels 

of concern for aquatic organisms under the proposed action because expected exposure 

concentrations in the SERA risk assessments did not exceed any NOEC value for any aquatic 

organisms analyzed. In addition, there would be no impact to the food web. 

Imazapic (Lowest Risk Category) 

Imazapic is a relatively new herbicide, and there are no studies on the effects of imazapic on 

either soil invertebrates or soil microorganisms. 

• If imazapic was extremely toxic to soil microorganisms, it is reasonable to assume that 

secondary signs of injury to microbial populations would have been reported. 

• Imazapic degrades in soil, with a half-life of about 113 days. 

• Half-life is decreased by the presence of microflora. 

• Imazapic is primarily degraded by microbes and it does not degrade appreciably under 

anaerobic conditions. 

• Imazapic is weakly adsorbed in high soil pH, but adsorption increases with lower pH 

(acidic soils) and increasing clay and organic matter content. 

• Field studies indicate that imazapic remains in the top 12 to 18 inches of soil and do not 

indicate any potential for imazapic to move with surface water. 

• Modeling results indicate imazapic runoff is highest in clay and loam soils with peaks 

after the first rainfall. 

• Imazapic percolation is highest in sandy soils. 

There is no probability of exceeding levels of concern for fish, invertebrates, or algae under the 

proposed action because expected exposure concentrations in the SERA risk assessments did not 

exceed NOEC values. However, at the high application rate (keeping in mind worst-case scenario 

assumptions) the peak modeled stream concentration of 0.0018 Mg/L did exceed the NOEC value 

of 0.00127 Mg/L for aquatic macrophytes. The magnitude of difference between these two 

concentrations is extremely small, a difference of 0.00053. This indicates that the true 

concentration for aquatic macrophytes is likely to be much lower under the action alternatives, 

 E-15
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix E-Aquatics 

even if there were no buffers. Therefore, it is nearly impossible to indirectly adversely affect fish 

via the food web under the action alternatives. 

Metsulfuron methyl (Lowest Risk Category) 

Studies on the effects of metsulfuron methyl on soil biota are limited to Pseudomonas species, 

though there are a few studies of insects that live in soil. The lowest observed effect concentration 

is 5 mg/kg, based on the Psuedomonas study. At recommended use rates, no effects are expected 

for insects. 

• Effects to soil microorganisms appear to be transient 

• Metsulfuron methyl degrades in soil, with a variable half-life up to 120 days. 

• Half-life is decreased by the presence of organic matter though microbial degradation of 

metsulfuron methyl is slow. 

• Non-microbial hydrolysis is slow at high pH but rapid at lower pH. 

• Adsorption to soil particles, which affects the runoff potential of metsulfuron methyl, 

increased with increased pH and organic matter. 

• Metsulfuron methyl has low adsorption to clay. 

• Modeling results indicate that off-site movement due to runoff could be significant in 

clay soils. 

• Metsulfuron methyl percolates in sandy soils. 

There is no probability of exceeding levels of concern for fish, invertebrates, or algae under the 

proposed action because expected exposure concentrations in the SERA risk assessments did not 

exceed NOEC values. However, at the high and typical application rates (keeping in mind worstcase scenario assumptions) the peak modeled stream concentration of 0.0015 Mg/L for high 

application rate and 0.0003 Mg/L for typical did exceed the NOEC value of 0.00016 Mg/L for 

aquatic macrophytes. The magnitude of difference between these two concentrations is very 

small, a difference of 0.00053 for high application rates and 0.00284 for typical. Therefore, there 

is a very low probability of indirectly adversely affecting fish via the food web under the 

proposed action. 

Chlorsulfuron (Moderate Risk Category) 

Studies on the effects of chlorsulfuron on soil biota include lab and field studies on nematodes; 

fungi; populations of actinomycetes, bacteria, and fungi; and soil microorganisms. 

• No effects of chlorsulfuron were found for soil biota at recommended application rates, 

with the exception of transient decreases in soil nitrification. 

• The ‘no observable effects concentration’ for soil is 10 mg/kg, based on cellulose and 

protein degradation. 

• Chlorsulfuron degrades in aerobic soil. 

• Non-microbial hydrolysis plays an important role in chlorsulfuron breakdown, and 

hydrolysis rates increase as pH increases. 

• Adsorption to soil particles, which affects the runoff potential of chlorsulfuron, is 

strongly related to the amount of organic material in the soil. 

• Chlorsulfuron adsorption to clay is low. 

• Chlorsulfuron is moderately mobile at high pH. 

• Leaching is reduced when pH is less than six. 

 E-16 

 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix E-Aquatics 

• Modeling results indicate that runoff would be negligible in sandy or loamy soils. 

• In clay soils, off-site loss could be substantial (up to about 55 percent of the applied 

amount) in regions with annual rainfall rates of 15 to 250 inches. 

There is no probability of exceeding levels of concern for fish or invertebrates under the proposed 

action because expected exposure concentrations in the SERA risk assessments did not exceed 

NOEC values. However, at the high application rate the peak modeled stream concentration of 

0.05 Mg/L did exceed the NOEC value of 0.01 Mg/L for algae. For aquatic macrophytes, the 

NOEC value of .000047 Mg/L was exceeded at both typical and high application rates (keeping 

in mind worst-case scenario assumptions). The NOEC value used in the SERA risk assessment 

for aquatic macrophytes is 1/10th of the EC50, indicative of a conservative approach in the SERA 

risk assessments. The magnitude of difference between the expected exposure concentrations and 

the NOEC value for algae is small and unlikely to be reached under the action alternatives 

because of PDFs and buffers, as well as label directions. 

There is a large magnitude of difference for aquatic macrophytes because of the NOEC value 

used and the sensitive nature of aquatic macrophytes. Under the proposed action, there is a low 

risk of impacting aquatic macrophytes, however, impacts would be localized and directed at the 

individual macrophyte where chlorsulfuron comes in contact with water. However, it is very 

unlikely that chlorsulfuron would come in contact with water at peak modeled concentrations 

under the SERA risk assessment because of PDFs, buffers and label direction. If it were to come 

in contact with water under the proposed action, impacts would not be of any magnitude that 

would lead to an adverse affect on fish. Therefore, there is a very low probability of indirectly 

adversely affecting fish via the food web under the action alternatives. 

Imazapyr (Moderate Risk Category) 

There are no studies on the effects of imazapyr on soil invertebrates, and incomplete information 

on the effects on soil microorganisms. 

One study indicates cellulose decomposition, a function of soil microorganisms, can be decreased 

by soil concentrations higher than concentrations expected from USDA Forest Service 

applications. 

• There is no basis for asserting adverse effects to soil microorganisms. 

• Imazapyr degrades in soil, with a half-life of 25 to 180 days. 

• Degradation rates are highly dependent on microbial action. 

• Anaerobic conditions slow degradation. 

• Adsorption increases with time as soil dries and is reversible. 

• Field studies indicate that imazapyr remains in the top 20 inches of soil and do not 

indicate any potential for imazapyr to move with surface water. 

• In forest field studies, imazapyr did not run off and there was no evidence of lateral 

movement. 

• Modeling results indicate imazapyr runoff is highest in clay and loam soils with peaks 

after the first rainfall. 

• Imazapyr percolation is highest in sandy soils 

There is no probability of exceeding levels of concern for fish or invertebrates under the proposed 

action because expected exposure concentrations (EEC) in the SERA risk assessments did not 

exceed NOEC values. However, at high application rates the peak modeled stream concentration 

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Appendix E-Aquatics 

of 1.0 Mg/L did exceed the NOEC value of 0.02 Mg/L for algae and 0.013 Mg/L for aquatic 

macrophytes. At typical application rates the peak modeled stream concentration of 0.036 Mg/L 

also exceeded the NOEC values for algae and aquatic macrophytes. The NOEC value used in the 

SERA risk assessment for aquatic macrophytes is 1/10th of the EC50, indicative of a conservative 

approach in the SERA risk assessments. The magnitude of difference between the expected 

exposure concentrations and the NOEC values for algae and aquatic macrophytes is relatively 

small and unlikely to be reached under the proposed action because of PDFs and buffers, as well 

as label directions. 

Under the proposed action, there is little risk of impacting algae and aquatic macrophytes since 

emergent vegetation would not be treated. In the event that imazapyr did come into contact with 

water, impacts would be localized and of short duration, directed at the individual organism that 

were contacted. It is unlikely that impacts would be of a magnitude that would lead to an adverse 

affect on fish or invertebrates. Therefore, there is a very low probability of indirectly adversely 

affecting fish via the food web under the proposed action. 

Sulfometuron methyl (Moderate Risk Category) 

There are no studies on the effects of sulfometuron methyl on soil invertebrates. However, it is 

toxic to soil microorganisms. Microbial inhibition is likely to occur at typical application rates 

and could be substantial. Soil residues may alter composition of soil microorganisms. 

Sulfometuron methyl applied to vegetation at rates to control undesirable vegetation would 

probably be accompanied by secondary changes in the local environment that affect the soil 

microbial community more certainly than direct toxic action of sulfometuron methyl on 

microorganisms. 

• The typical half-life for sulfometuron methyl varies from 10 to 100 days, depending on 

soil texture. Half-life decreases as soil particle size decreases. Presence of soil 

microorganisms also decreases half-life, though microbial breakdown occurs slowly. 

Sulfometuron methyl degradation occurs most rapidly at lower pH soils where rates are 

dominated by hydrolysis. 

• Sulfometuron methyl mobility is generally greater at higher soil pH and lower organic 

matter content. 

• Modeling results indicate sulfometuron methyl runoff is highest in clay and loam soils 

with peaks after the first rainfall. Sulfometuron methyl percolation is highest in sandy 

soils. Monitoring results generally support modeling results. 

• Sulfometuron methyl applied to vegetation at typical application rates would 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. 

There is no probability of exceeding levels of concern for fish or invertebrates under the proposed 

action because expected exposure concentrations (EEC) in the SERA risk assessments did not 

exceed NOEC values. However, at high application rates the peak modeled stream concentration 

of 0.0076 Mg/L did exceed the NOEC value of 0.0025 Mg/L for algae and 0.00021 Mg/L for 

aquatic macrophytes. At typical application rates the peak modeled stream concentration of 

0.0009 Mg/L exceeded the NOEC value of 0.00021 Mg/L for aquatic macrophytes. The 

magnitude of difference between the expected exposure concentrations at the high application 

rates for aquatic macrophytes is 9 times that of the typical application rate. It comes as no surprise 

as sulfonureas are quite toxic to non-target vegetation. There was no concern for algae at the 

typical application rate. There is a very low likelihood of impacting algae and aquatic 

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macrophytes under the proposed action because of PDF and buffers, as well as label directions. If 

any sulfometuron methyl were to come in contact with water, impacts to aquatic macrophytes 

under the proposed action would be localized and of short duration, directed at the individual 

organism where the herbicide comes in contact with water. It is unlikely that impacts would be of 

a magnitude that would lead to an adverse affect on fish or invertebrates. Therefore, there is a 

very low probability of indirectly adversely affecting fish via the food web under the action 

alternatives. 

Sethoxydim (Poast product, Higher Risk Category) 

Sethoxydim was associated with some levels of concern in the R6 2005 FEIS; however risk 

assessments incorporated the toxicity of the naptha solvent in the Poast® formulation of this 

herbicide. The toxicity of the sethoxydim alone is about 100 times less for fish than that of the 

Poast® formulation. Since the naptha solvent tends to volatilize or adsorb to sediments, using 

Poast® formulation data to predict effects from runoff may overestimate potential effects (SERA 

2001). Adverse affects to fish and other aquatic organisms are not likely because the amount of 

sethoxydim used for this project would be lower than toxic levels, even if the Poast® formulation 

were used. 

• Sethoxydim is degraded by soil microbes, with an estimated half-life of 1 to 60 days. 

Adsorption of sethoxydim varies with organic material content. 

• Modeling results indicate sethoxydim runoff is highest in clay and loam soils with peaks 

after the first rainfall. 

There is no probability of exceeding levels of concern for invertebrates, algae, or aquatic 

macrophytes under the proposed action because expected exposure concentrations (EEC) in the 

SERA risk assessments did not exceed NOEC values. However, at both high and typical 

application rates the peaks modeled stream concentrations of 0.19 Mg/L and 0.15 Mg/L, 

respectively, did exceed the NOEC value of 0.06 Mg/L for fish and were nearly equal in 

difference between the EEC and NOEC value. There is very little concern for the magnitude of 

difference between the EEC and NOEC because it is highly unlikely that sethoxydim (Poast® 

formulation) would come in contact with water at toxic levels due to the restricted use in riparian 

areas. Therefore, there is a very low probability of adversely affecting fish. 

Picloram (Higher Risk Category) 

Picloram is a restricted use pesticide in the states of Washington and Oregon. The persistence of 

picloram increases with soil concentration, thus increasing the likelihood that it becomes toxic to 

soil microorganisms in the short-term. 

• Since picloram is toxic to microorganisms at low levels, toxic effects can last for some 

time after application. 

• Persistence in soils could affect soil microorganisms by decreasing nitrification. 

• Long-term effects to soil microorganisms are unknown. 

• Picloram applied at a typical application rate is likely to change microbial metabolism, 

though detectable effects to soil productivity are not expected. 

• Field studies have not noted substantial adverse effects associated with the normal 

application of picloram that might be expected if soil microbial activity were 

substantially damaged. 

• Substantial effects to soil productivity from the use of picloram over the last 40 years 

have not been noted. 

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• Picloram has been studied on a number of soil invertebrates. 

• Metabolites may increase toxicity for some soil microorganisms 

• Picloram has a typical half-life of 90 days. 

• Soil degradation rates vary in soil, depending on application rate and soil depth. 

• Picloram is water soluble, poorly bound to soils that are low in clays or organics, has a 

high leaching potential, and is most toxic in acidic soil. 

• Picloram should not be used on coarse-textured soils with a shallow water table, where 

groundwater contamination is most likely to occur. 

• Picloram percolation is highest in loam and sandy soils. However, modeling results 

indicate picloram runoff (not percolation) is highest in clay soils. 

There is no probability of exceeding levels of concern for invertebrates or aquatic macrophytes 

under the proposed action because expected exposure concentrations (EEC) in the SERA risk 

assessments did not exceed NOEC values. However, at high and typical application rates the peak 

modeled stream concentrations of 0.20 Mg/L and 0.07 Mg/L, respectively, did exceed the NOEC 

value of 0.04 Mg/L (1/20th LC50) for fish. The HQ at typical application rate is 2 compared to 5 

at the high application rate for fish, suggesting that exceedances are within the same low range of 

difference. 

Acute exposures can affect fish development, growth, swimming response, and liver 

histopathology; all referred to as sublethal effects. To account for the potential of sublethal 

effects, the 1/20th of the LC50 was used in the SERA risk assessment. Exposures that lead to 

such sublethal effects use an amount of picloram much greater than what would be applied at 

each treatment site on the Wallowa-Whitman National Forest. 

Acute toxicity of picloram varies considerably with formulation and with fish species. 

Formulations like Tordon 22K (potassium salt) is known to be considerably less toxic to several 

fish species compared to ester formulations. Although leached picloram may be transported to 

aquatic ecosystems as a result of rainfall, studies have shown that less than 5 percent of the 

picloram applied to a watershed are transported in surface runoff (Norris et al. 1991). Where soil 

compaction has occurred or where intermittent streams have been treated, residues of picloram 

could be mobilized following heavy rainfalls. 

The PDFs and buffers established for picloram greatly reduce the potential for drift, leaching, and 

runoff. Any amount of picloram in water as a result of drift from spot spray or hand/select 

applications would be negligible and more than likely not detected because of vegetation 

interception and distance from the ordinary high water line or bankfull. 

For aquatic macrophytes, only the high application rate exceeded the NOEC value of 0.10 

(LOEC), resulting in a HQ of 2. Given the low magnitude of difference in EEC and NOEC, as 

well as the low range of HQs for picloram, it is unlikely that NOEC values for fish and aquatic 

macrophytes would be exceeded under the proposed action because of the PDFs and buffers 

established for streams and roads with high potential for herbicide delivery. 

Glyphosate (Higher Risk Category) 

Glyphosate has been extensively studied and is commonly used by State and Federal agencies 

within riparian areas. This section includes more information than for previous herbicides 

because of it’s proposed use within aquatic influence zones with spot and hand/select applications 

of aquatic formulations. 

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Glyphosate is highly soluble in water but much less so in organic solvents. In general, it is very 

immobile in soil, being rapidly adsorbed by soil particles, and subject to some degree of 

microbial degradation. The degree of glyphosate decomposition varies by soil types. Glyphosate 

is readily metabolized by soil microorganisms and some species can use glyphosate as a sole 

source of carbon. 

• It is degraded by microbial action in both soil and water. 

• Glyphosate degrades in soil, with an estimated half-life of 30 days. 

• Glyphosate is highly soluble, but adsorbs rapidly and binds tightly to soil. 

• Glyphosate has low leaching potential because it binds so tightly to soil. 

• Modeling results indicate glyphosate runoff is highest in loam soils with peaks after the 

first rainfall. 

The SERA 2003 risk assessment provides results for two formulations of glyphosate; glyphosate 

with surfactant (terrestrial formulation, most toxic formulation) and glyphosate without surfactant 

(aquatic, less toxic formulation). 

In aquatic species, the acute lethal potency of glyphosate and glyphosate formulations has been 

relatively well-defined. The formulation of glyphosate with surfactants, especially the POEA 

surfactant commonly used in glyphosate formulations, has a pronounced effect on the acute lethal 

potency of glyphosate. 

The primary hazards to fish appear to be from acute exposures to the more toxic formulations. At 

high and typical application rates, the hazard quotients for the more toxic formulation at the upper 

ranges of plausible exposure indicate that the 1/20th LC50 values for listed fish will be exceeded 

under worst-case conditions. The more toxic formulation did exceed the toxicity endpoints for 

invertebrates and aquatic plants at the high application rate of 7 lbs a.e./acre. In the worst-case 

scenarios, the exposure estimates are based on a severe rainfall (about 7 inches over a 24 hour 

period) in an area where runoff is favored – a slope toward a stream immediately adjacent to the 

application site. This is a standard worst-case scenario used in Forest Service risk assessments to 

guide the Forest Service in the use of herbicides. The SERA 2003 risk assessment strongly 

suggests that the use of the more toxic formulations near surface water is not prudent. Therefore, 

the proposed action has included a 100 ft buffer for broadcast applications and a 50 foot buffer for 

spot and hand/select applications for the more toxic formulations of glyphosate. In addition, no 

broadcasting is permitted on roads with high potential for herbicide delivery. This greatly lowers 

the probability of toxic formulations of glyphosate coming in contact with water at levels of 

concern. 

The less toxic formulation did slightly exceed the toxicity endpoint used for fish at high and 

typical application rates, 6 and 2 respectively. However, there are no exceedances for 

invertebrates or aquatic plants. Exceedance is based on the 1/20th LC50 value rather than a 

NOEC. Thus, the use of less toxic formulations of glyphosate (aquatic) near bodies of water 

where salmonids may be found is limited to spot and hand/select methods up to the edge of water. 

Sub-lethal Effects 

In the SERA 2003 risk assessment, the term “sub-lethal” is intended to designate effects that may 

impact reproduction, behavior, or the ability to respond to other stressors. For chronic exposures 

to glyphosate, the most relevant study remains the life cycle toxicity studies done in fathead 

minnow. As summarized in the U.S. EPA/OPP (1993c), no effect on mortality or reproduction 

was observed at a concentration of 25.7 mg/L using 87.3% pure technical grade glyphosate. The 

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Appendix E-Aquatics 

full life-cycle toxicity study was conducted in fathead minnow, a standard chronic toxicity that 

was required by and accepted by the U.S. EPA (1993a). In this study, the NOEC was 25.7 mg/L 

(U.S. EPA, 1993a, p. 41). It is important to note that the NOEC from this full life-cycle toxicity 

study not only indicates a lack of mortality but also indicates that the fish were able to reproduce 

normally. The life cycle NOEC of 25.7 mg/L was used as the most appropriate basis for risk 

characterization in the SERA 2003 risk assessment. 

To account for uncertainty regarding sub-lethal effects, an amount of 0.5 Mg/L was used as the 

toxicity threshold for listed fish under the R6 2005 FEIS. This amount is the 1/20th of the acute 

LC50 (U.S. EPA, 2004) for glyphosate, which is 51 times less than the chronic (long-term 

exposures) toxicity threshold of 25.7 Mg/L. 

If a full life-cycle of fish showed no adverse affects at a long-term exposure of 25.7 Mg/L (NOEC 

endpoint), the probability of a fish adversely affected at short-term exposure of 0.5 Mg/L is low 

(See the BE for this EIS, available upon request from the Project Record at the WallowaWhitman NF in Pendleton, OR). 

Effects of Surfactants 

Appendix 3c of the SERA 2003 risk assessment summarizes the available ecological information 

from all of the Material Safety Data Sheets (MSDS) for the formulations that are labeled for 

forestry applications. It is apparent that these formulations fall into relatively clear groups. The 

most toxic formulations appear to be Credit Systemic, Credit, Glyfos, Glyphosate, glyphosate 

Original, Prosecutor Plus Tracker, Razor SPI, Razor, Roundup Original, Roundup Pro 

Concentrate, and Roundup UltraMax. It may be presumed that these formulations contain the 

most toxic surfactants. Other formulations such as Aqua Neat, Aquamaster, Debit TMF, Eagre, 

Foresters’ Non-Selective Herbicide, Glyphosate VMF, and Roundup Custom are much less 

acutely toxic. 

For the SERA 2003 risk assessment, the uncertainties involving the presence or absence of a 

surfactant and the possibly differing effects of using various surfactants cannot be resolved with 

certainty. Toxicity of glyphosate is characterized based on the use of a surfactant, either in the 

formulation or added as an adjuvant in a tank mixture. The R6 2005 FEIS addresses this 

uncertainty through Standard #18. 

The polyethoxylated tallow amine (POEA) surfactant used in some glyphosate formulations is 

substantially more toxic to aquatic species than glyphosate and substantially more toxic than 

other surfactants that may be used with glyphosate. Two aquatic toxicity studies (Folmar et al. 

1979, Wan et al. 1989) have been conducted on glyphosate, the POEA surfactant, and a Roundup 

formulation which permit a quantitative assessment of the relative toxicities of glyphosate and 

POEA as well as an assessment of potential for toxicologic interactions (i.e., synergism or 

antagonism) in combined exposures to these agents. Both of these studies indicate that POEA is 

substantially more toxic than glyphosate and that POEA surfactant is the primary toxic agent of 

concern. Therefore, the proposed action PDF F3 does not allow the use of POEA within 150 feet 

of surface water, wetlands, or on roads with high potential for herbicide delivery. 

Toxicity of Roundup to aquatic organisms because of the POEA surfactant was known by 

Monsanto when Roundup was originally labeled in 1978 and data were provided to the 

Environmental Protection Agency (EPA). This is why the formulation was not registered for 

aquatic use; nor are glyphosate-containing products with POEA now registered for aquatic use. 

Most glyphosate-containing products that are registered for aquatic use are manufactured without 

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Appendix E-Aquatics 

surfactant. Standard #18 of the R6 2005 FEIS states that only those surfactants reviewed in 

Forest Service hazard and risk assessment documents would be approved for use. 

Nonyphenol polyethoxylate (NPE) based surfactants were also analyzed under the R6 2005 FEIS 

and did not exceed any LOC for fish, invertebrates, algae, or aquatic macrophytes. 

Off-site drift 

Estimates of drift for ground applications are included in the SERA risk assessments. In ground 

broadcast applications, glyphosate will typically be applied by low boom ground spray and thus 

these estimates are used in the SERA risk assessment. Drift associated with backpack (directed 

foliar applications) are likely to be much less than from broadcast. 

In typical backpack ground sprays, droplet sizes are greater than 100 μ, and the distance from the 

spray nozzle to the ground is 3 feet or less. In mechanical sprays, raindrop nozzles might be used. 

These nozzles generate droplets that are usually greater than 400 μ, and the maximum distance 

above the ground is about 6 feet. In both cases, the sprays are directed downward. 

For most applications, the wind velocity will be no more than 5 miles/hour, which is equivalent to 

approximately 7.5 feet/second (1 mile/hour = 1.467 feet/second). Assuming a wind direction 

perpendicular to the line of application, 100 μ particles falling from 3 feet above the surface could 

drift as far as 23 feet (3 seconds @ 7.5 feet/second). A raindrop or 400 μ particle applied at 6 feet 

above the surface could drift about 3 feet (0.4 seconds @ 7.5 feet/second). This suggests that 

there is a reasonable probability of some off-site drift from spot applications that occur up to the 

water’s edge. Label requirements as well as PDFs and buffer distances account for significant offsite drift that could occur from broadcasting under the proposed action. For spot applications, the 

amount of drift is likely to be significantly less than from broadcast, therefore, the magnitude of 

effects on fish, invertebrates, and aquatic plants as a result of drift is very low. When spot 

treatments of herbicide using hand-held equipment are made, the applicator has direct control of 

where the spray solution is applied and little, if any, herbicide comes in contact with standing 

water. 

Runoff 

Glyphosate or any other herbicide may be transported to off-site soil by runoff or percolation. 

Both runoff and percolation are considered in estimating contamination of ambient water. For 

assessing off-site soil contamination, however, only runoff is considered. This is similar to the 

approach used by U.S. EPA (1995) in their exposure assessment for terrestrial plants. The 

approach is reasonable because off-site runoff will contaminate the off-site soil surface and could 

impact non-target plants. Percolation, on the other hand, represents the amount of the herbicide 

that is transported below the root zone and thus may impact water quality but should not affect 

off-site vegetation. 

Based on the results of the GLEAMS modeling for the Blue Mountain Ecotype, the proportion of 

the applied glyphosate lost by runoff was estimated for clay, loam, and sand at rainfall rates 

ranging from 5 inches to 250 inches per year. Results indicate that there is the potential for 

glyphosate to reach streams at or above the toxicity value for fish, invertebrates, and aquatic 

plants under the worst-case scenario model. 

In the flatter areas of UNF, such as valley bottoms, slope is likely to be less than the 10% 

modeled, decreasing the potential for stream herbicide concentrations. In the upper portions of the 

watersheds on UNF slopes exceed the 10% modeled, therefore there would be an increase of the 

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Appendix E-Aquatics 

potential for herbicide delivery from broadcast situations. However, it is highly unlikely that 

estimates from the GLEAMS model scenarios would be reached under the proposed action 

because actual application does not match well the scenario used in the model. Examples of 

scenario inputs that would differ at actual treatment sites include: interception of herbicide by 

vegetation, prohibited use of broadcasting in riparian areas, and the presence of organic matter in 

the soil. The presence of organic matter in soil significantly reduces delivery of glyphosate to 

streams. 

Dose Response Assessment 

The U.S. EPA/OPP (1993c) classified technical grade glyphosate as non-toxic to practically nontoxic in freshwater fish and LC50 values for glyphosate are in the range of 70 to 170 mg/L. In 

addition, the U.S. EPA/OPP (1993c) used the NOEC of 25.7 mg/L from life cycle toxicity study 

on technical grade glyphosate using fathead minnow and concluded that: “technical glyphosate 

should not cause acute or chronic adverse effects to aquatic environments. Therefore, minimal 

risk is expected to aquatic organisms from the technical glyphosate”. 

The selection of the 1/20th of the LC50 as the toxicity values by U.S. EPA (2004) addresses the 

higher sensitivity of some species of fish to technical grade glyphosate. Trout and other salmonids 

have much lower LC50 than those cited by U.S. EPA/OPP in 1993, with the lowest LC50 value 

for salmonids of 10 mg glyphosate/L, for trout in soft-water. The use of 0.5 Mg/L for the less 

toxic formulation was used as the toxicity value for listed fish and accounts for potential sublethal effects. For the more toxic formulation a toxicity value of 0.065 Mg/L was used. 

There is a magnitude of difference in toxicity between glyphosate without surfactant and 

glyphosate with surfactant. Using the toxicity values, glyphosate with surfactant is more toxic 

than glyphosate without surfactant by a factor of about 8 (HQ 43 ÷ HQ 6). It is unlikely that the 

proposed action would result in HQ of 6 for the less toxic formulation because of the limitations 

on application methods. In addition, field studies done by DOA support the expectation that 

amounts would not exceed any level of concern. 

Eyed eggs of fish seem to be a resistant life stage, with sensitivity increasing as the fish enters the 

sac-fry and swim-up stages. 

For invertebrates and algae, there is a very low probability of adverse affects at the highest 

application rates for glyphosate with surfactant. Results for the worst-case scenario using the 

1/10th of the LC50 for invertebrates (1.1 Mg/L) and 0.89 NOEC for aquatic plants are not likely 

to be reached because there will be no broadcasting within riparian areas. 

Triclopyr (Higher Risk Category) 

Five commercial formulations of triclopyr, either as the triethylamine (TEA) salt or the 

butoxyethyl ester (BEE) are currently registered for forestry applications and are covered in the 

SERA 2003 risk assessment. Physical, chemical, and biochemical properties of triclopyr can be 

found on page 2-10 and 2-11 in the SERA 2003 Triclopyr Risk Assessment. This section includes 

more information than for previous herbicides because of its proposed use within aquatic 

influence zones with spot and hand/select applications of aquatic formulations. For aquatic 

formulations, there is a 15 ft buffer on waterbodies for spot applications and hand/select methods 

can be used up to the water’s edge. 

Triclopyr BEE is much more toxic to aquatic organisms than triclopyr TEA. A breakdown 

product, TCP (3,5,6-trichloro-2-pyridinol), is more toxic than either form of triclopyr. 

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In forestry applications, the primary concern is the formation of TCP as a soil metabolite. TCP is 

more persistent than triclopyr in soil and is relatively mobile in soil, thus able to come in contact 

with water near the site of application. TCP is of concern to the SERA 2003 risk assessment both 

because it is a metabolite of triclopyr and because the aggregate risks of exposure to TCP from 

the breakdown of both triclopyr and chlorpyrifos (insecticide) must be considered. 

Data indicate that Garlon 3A (the triethylamine salt of triclopyr) is only slightly toxic or 

practically non-toxic to organisms tested. Garlon IV (butoxyethyl ester of triclopyr), however, is 

highly toxic to fish, whereas unformulated triclopyr is only slightly toxic. Project Design Features 

do not allow the use of Garlon IV within 50 feet of surface waters, thereby reducing the 

probability of fish coming in contact with Garlon IV. The long-term persistence of triclopyr does 

not seem to be a significant problem in forest settings because of its rapid disappearance. Photodegradation is a major reason for the disappearance of triclopyr from water (Norris et al. 1991). 

Exposure scenarios modeled in the SERA risk assessments are likely to significantly 

overestimated the risk of acute adverse affects from the application of triclopyr because triclopyr 

would only be applied by spot or hand methods (as per R6 2005 ROD standard 16), and not 

broadcast sprayed over 10 acres as depicted in the model scenario. The likelihood of toxic levels 

of triclopyr coming in contact with water is very low. 

• Triclopyr has an average half-life in soil of 46 days, while TCP has an average half-life in 

soil of 70 days. Warmer temperatures decrease the time to degrade triclopyr. 

• Soil adsorption is increased as organic material increases and decreased as pH increases. 

Triclopyr is weakly adsorbed to soil, though adsorption varies with organic matter and 

clay content. Both light and microbes degrade triclopyr. 

Fish - There is a substantial difference between the toxicity of triclopyr acid and the toxicity of 

triclopyr BEE formulations, and the difference is reflected in the toxicities of the Garlon 

formulations (SERA 2003). As shown by Wan et al. (1989), Garlon 4 is more toxic than Garlon 

3A by a factor of about 200 (150-230). This difference in toxicity is substantially greater than the 

difference in toxicity between triclopyr BEE and triclopyr acid. As indicated by Wan et al. (1989), 

the increased difference appears to be attributable to the toxicity of Garlon 3A, based on the level 

of triclopyr acid in this formulation. The level of triclopyr BEE in Garlon 4 appears to account for 

practically all of the toxicity of Garlon 4 (i.e., the ratios of observed to predicted LC50 values do 

not vary remarkably from unity for Garlon 4). Although Garlon 4 contains kerosene (see section 

2.2 of the SERA 2003), the toxicity of kerosene to aquatic species is approximately 100-1,000 

fold less than triclopyr BEE [LC50 values of approximately 200-3,000 mg/L (SERA 2003)], 

supporting the observation that the toxicity of Garlon 4 can be completely accounted for by the 

toxicity of triclopyr BEE. 

Sub-lethal Effects 

The sublethal effects of Garlon 4 on salmonid (rainbow trout) has been examined by Johansen 

and Geen (1990) using flow-through systems. Fish were found to be lethargic at concentrations of 

0.32-0.43 mg/L. At levels <0.1 mg/L, fish were hypersensitive over 4-day periods of exposure. 

This is reasonably consistent with the threshold for behavioral changes in rainbow trout for 

Garlon 4 of 0.6 mg/L (Morgan et al. 1991). The corresponding threshold for behavioral changes 

to Garlon 3A was 200 mg/L (Morgan et al. 1991) is consistent with the relative acute lethal 

potencies of these two agents (SERA 2003). 

Subchronic toxicity data are available only on the triethylamine salt of triclopyr and only in 

fathead minnows (Mayes et al. 1984; Mayes 1990c). 

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In this study, fathead minnow eggs were exposed to concentrations of 26, 43, 65, 104, 162, and 

253 mg/L for 28 days covering the development from egg to fry. The survival of fathead minnows 

(embryo-larval stages) was significantly reduced at 253 mg/L compared with control animals. At 

162 mg/L, there was a slight decrease in body length. No effects were noted at any of the lower 

concentrations (SERA 2003). Janz et al. (1991) noted that sublethal exposures of coho salmon to 

various formulations of triclopyr do not appear to cause signs of physiological stress. 

To account for uncertainty regarding sub-lethal effects from triclopyr acid and triclopyr BEE, the 

toxicity values of 0.26 Mg/L and 0.012 Mg/L, respectively, was for the R6 2005 FEIS. Both 

amounts are the 1/20th of the acute LC50 (U.S. EPA, 2004) for triclopyr, compared to the chronic 

NOEC of 104 Mg/L. 

Aquatic Invertebrates 

The available LC50 values cited in SERA 2003 suggest that most invertebrates are about equally 

or somewhat less sensitive than fish to the various forms of triclopyr. Some families of 

invertebrates (Ephemeroptera, Plecoptera, Trichoptera, Odonata) are much more resistant than 

fish to Garlon 4 (SERA 2003). The 1/10th of the LC50 (0.855 Mg/L) was used for the R6 2005 

FEIS and was barely exceeded by 0.645 for triclopyr BEE at the high application rate. 

Aquatic Plants 

Triclopyr and triclopyr formulations have been subject to a standard set of bioassays in aquatic 

plats, both algae and macrophytes, that are required for the registration of herbicides. Based on 

EC50 values, triclopyr TEA is about equally toxic to both algae (lowest EC50 of 5.9 ppm a.i.) and 

macrophytes (lowest EC50 of 8.8 ppm a.i.). As with toxicity to fish and invertebrates, triclopyr 

BEE is more toxic with EC50 values as low as 0.88 ppm a.i. for macrophytes and 0.1 ppm for 

algae (SERA 2003). The R6 2005 FEIS used a toxicity value of 0.007 Mg/L (1/10th of EC50) for 

triclopyr BEE and 0.42 Mg/L (1/10th of EC50) for aquatic plants. There is a magnitude of 

difference between the exposures of triclopyr BEE and triclopyr acid at high application rates. 

Off-site Drift 

This is the same as for glyphosate. Under the proposed action, spot applications have a 15 foot 

buffer from the ordinary high water mark or bankfull. 

Run-off 

This is the same as for glyphosate. There are also substantial differences in the environmental fate 

of triclopyr TEA and triclopyr BEE. Both of these factors were considered in the SERA risk 

assessment. Triclopyr TEA will dissociate almost instantaneously to triclopyr acid in water. Thus, 

the toxicity of triclopyr TEA and triclopyr acid are essentially the same when expressed as acid 

equivalents. Triclopyr BEE, on the other hand, will degrade quickly but not instantaneously to 

triclopyr acid. This makes a substantial difference in the results from acute toxicity bioassays 

because, as summarized in the SERA 2003 risk assessment, the octanol water partition coefficient 

for triclopyr BEE (about 10,233) is higher than that of triclopyr acid (about 0.35 at pH 7) by a 

factor of nearly 30,000 [10,233÷0.35=29,237]. The much higher octanol water partition 

coefficient for triclopyr BEE will lead to much more rapid uptake of this form relative to triclopyr 

acid and this probably accounts for the much higher acute toxicity of triclopyr BEE relative to 

triclopyr acid. 

Both forms of triclopyr will rapidly leach in very sandy soils after heavy rainfall. Since the 

maximum concentrations from the GLEAMS modeling is based on a rainfall event that occurs 

 E-26 

 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix E-Aquatics 

one day after application, relatively little triclopyr BEE is transformed to triclopyr acid and the 

peak concentrations are essentially equivalent. For both clay and loam soils, the maximum 

concentrations of triclopyr BEE (66 ppb in clay and 92 ppb in loam) are less than that of triclopyr 

acid (428 ppb for clay and 308 ppb for loam) because of the somewhat higher binding to organic 

matter in soil and consequent lesser runoff of triclopyr BEE relative to triclopyr acid in these 

soils. Triclopyr BEE will rapidly hydrolyze to triclopyr acid in water and “chronic” exposure to 

triclopyr BEE is not possible. 

Dose Response Assessment 

The acute risks associated with the use of triclopyr TEA are extremely low but the risks 

associated with the use of triclopyr BEE are obvious. TCP is about as acutely toxic to fish as 

triclopyr BEE. 

Although triclopyr BEE is much more toxic to aquatic species than triclopyr TEA or triclopyr 

acid, the potential for exposure under the proposed action is much less because of the rapid 

hydrolysis of triclopyr BEE to triclopyr acid as well as the lesser runoff of triclopyr BEE because 

of it’s lower water solubility and higher affinity for soils. Buffers and PDFs will reduce the 

likelihood of triclopyr BEE coming in contact with water. 

TCP 

TCP (3,5,6-trichloro-2-pyridinol) is a major metabolite of triclopyr and is found in both soil and 

water. In mammals, TCP has about the same toxicity as triclopyr. Whereas, in fish TCP is 

substantially more toxic than either triclopyr acid or triclopyr TEA, with acute LC50 values in the 

range of about 2 to 10 ppm, similar to the toxicity of triclopyr BEE. An early life-stage study has 

been conducted in rainbow trout by Marino et al. 1999 (SERA 2003). The most sensitive endpoint 

involved growth – i.e., length and weight– with an NOEC of 0.0808 mg/L and an LOEC of 0.134 

mg/L. Thus, TCP appears to be much more toxic than triclopyr TEA, for which the 

corresponding values in an early life stage study in the fathead minnow are 104 mg/L and 162 

mg/L. 

Because triclopyr and chlorpyrifos degrade at different rates, maximum concentration in soil, and 

hence maximum runoff to water, will occur at different times. Thus, in order to provide the most 

conservative estimate of exposure to TCP, the maximum concentrations reported in SERA 2003 

reflect applications of triclopyr and chlorpyrifos spaced in such a way as to result in the 

maximum possible concentrations of TCP in water. This extremely conservative approach is 

discussed further in SERA 2003. 

There are substantial differences in the toxicity of triclopyr TEA and triclopyr BEE to aquatic 

species and substantial differences in the environmental fate of triclopyr TEA and triclopyr BEE. 

Thus, the SERA Risk Assessment for Triclopyr ran a separate set of GLEAMS models using 

triclopyr BEE as the parent compound and triclopyr acid as the metabolite. 

Barron et al. (1991) investigated the pharmacokinetics and metabolism of triclopyr (BEE) in 

yolk-sac fry of the coho salmon (Oncorhynchus kisutch) and found that the accumulation of 

triclopyr BEE was limited in the fish due to rapid hydrolysis to triclopyr acid, which was the 

principal metabolite in fish and water, accounting for over 99% of total residue. No TCP was 

detected in any residue or in test water. 

The risk assessment by EPA does not specifically address concerns for contamination of water wit 

TCP as a soil metabolite of triclopyr and chlorpyrifos. 

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Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix E-Aquatics 

 E-28 

 

Concentrations of TCP in a small stream could reach up to 11 ppb from the use of triclopyr at a 

rate of 1 lb/acre and up to 68 ppb in a small stream from the use of triclopyr at a rate of 1 lb/acre 

and chlorpyrifos at a rate of 1 lb/acre. Much lower peak concentrations would be expected in 

small ponds. 

There is very little monitoring data with which to assess the plausibility of the modeling for TCP 

(SERA 2003). As discussed by U.S. EPA/OPP (1998a, p. 65ff), TCP is seldom detected in surface 

water after applications of triclopyr that result in triclopyr concentrations of up to about 25μg/L, 

with a limit of detection (LOD) for TCP of 10 μg/L. Thompson et al. (1991) examined the 

formation of TCP from triclopyr in a forest stream. Consistent with the results reported by U.S. 

EPA, these investigators failed to detect TCP (LOD=50 μg/L) in stream water with concentrations 

of triclopyr up to 140 μg/L. This is at least consistent with the GLEAMS modeling of both 

triclopyr and TCP. As shown in SERA 2003, the maximum modeled concentrations of triclopyr in 

stream water range from about 161 to 428 μg/L (for sandy and clay soils respectively) and the 

corresponding maximum modeled concentration of TCP in stream water range from about 5 to 11 

μg/L. Thus, given the LOD of 50 μg/L in the study by Thompson et al. (1991), the failure to find 

TCP in stream water is consistent with the GLEAM modeling (SERA 2003).
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix E-Aquatics 

INFISH Goals and Strategies Adopted into the Forest Plan 

Riparian Management (INFISH A-1) 

Goals call for the maintenance or restoration of the following: 

• water quality to a degree that provides for stable and productive ecosystems (i.e. timing and 

character of temperature, sediments and nutrients) 

• stream channel integrity, channel processes and sediment regime under which the ecosystems 

developed (e.g. timing, volume, and character of sediment input and transport) 

• instream flows to support desired riparian and aquatic habitats, stream channel stability and 

effective function, and ability to route flood discharges 

• natural timing and variability of the water table elevation in meadows and wetlands 

• diversity and productivity of native and desired non-native plant communities 

• riparian vegetation so the amount and distribution of large woody debris is characteristic of 

natural riparian and aquatic ecosystems 

• habitat for populations contributing to viability of riparian-dependent communities (i.e. native 

and desired non-native plants, vertebrates, and invertebrates) 

• riparian vegetation for adequate summer and winter thermal regulation 

• riparian vegetation so the rates of surface and bank erosion and channel migration are similar 

to the rates under which the communities developed, and 

• riparian and aquatic habitats for the unique genetic stocks that evolved within that specific 

geo-climatic region. 

Interim Riparian Objectives serve as measurable indicators for "good" habitat at the watershed 

scale. Until refined on the basis of more specific local information, "good" habitat is assumed to 

be met when all five features are above the following threshold levels: 

Pool Frequency (pools per mile). 

Table E-4 Pool frequency (pools / mile) based on channel width in a properly functioning stream. 

From PACFISH (199x) 

Wetted 

Width 10 20 25 50 75 100 125 150 200 

Pools / 

mi, 96 56 47 26 23 18 14 12 9 

Water Temperature: No measurable increase in max water temp. Max water temp below 59 0 

F within adult holding habitat and below 48 0 F within spawning and rearing habitat. 

Large Woody Debris: The amount of large woody debris needed varies by geographic location. 

East of the Cascades: greater than 20 pieces per mile that exceed a 12 inch diameter and 35 foot 

length. 

 E-29
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix E-Aquatics 

 E-30 

 

Bank Stability and Lower Bank Angle (for non-forested settings): Bank stability exceeds 

80%, and 75% of banks should be undercut. Width to Depth Ratio: less than 10 in all systems 

(measured as mean wetted width divided by mean depth).
Appendix F – Aerial Modeling Results and 

Spray Guidelines 

Proposed Aerial Sites, Modeling Results, and Common 

Practices 
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Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix F – Aerial Modeling and Spray Guidelines 

Proposed Aerial Sites, Modeling Results and Common 

Practices 

Table F- 1 – Proposed Aerial sites for the Wallowa Whitman Invasive Plant EIS 

Inv ID Species1 Proposed Treatment Alternative 

Treatment Acres 

06160400070 CESO3 Chemical Bio-control 9.2 

06160400088 CESO3 Chemical Bio-control 7.4 

06160400112 CESO3 Chemical Bio-control 35.7 

06160400130 ONAC Chemical 7.3 

06160400210 CESO3 Chemical Bio-control 7.9 

06160400212 CESO3 Chemical Bio-control 11.3 

06160400213 CESO3 Chemical Bio-control 12.2 

06160400222 CESO3 Chemical Bio-control 8.6 

06160400242 CESO3 Chemical Bio-control 10.4 

06160400297 ONAC Chemical 18.8 

06160400370 CESO3 Chemical Bio-control 41.8 

06160400441 CESO3 Chemical Bio-control 5.7 

06160400442 CESO3 Chemical Bio-control 51.3 

06160400443 CESO3 Chemical Bio-control 107.8 

06160400444 CESO3 Chemical Bio-control 34.5 

06160400445 CESO3 Chemical Bio-control 259.1 

06160400448 CESO3 Chemical Bio-control 37.3 

06160400454 CESO3 Chemical Bio-control 0.2 

06160400536 CESO3 Chemical Bio-control 19.3 

06160400540 ONAC Chemical 6.3 

06160600042 CESO3 Chemical Bio-control 19.3 

06160600162 CESO3 Chemical Bio-control 3.7 

06160600166 CESO3 Chemical Bio-control 4.0 

06160600168 CESO3 Chemical Bio-control 23.7 

06160600169 CESO3 Chemical Bio-control 38.0 

06160600170 CESO3 Chemical Bio-control 6.5 

06160600171 CESO3 Chemical Bio-control 17.8 

06160600172 CESO3 Chemical Bio-control 5.3 

06160600173 CESO3 Chemical Bio-control 75.1 

06160600176 CESO3 Chemical Bio-control 57.8 

06160600177 CESO3 Chemical Bio-control 15.5 

TOTAL = 31 958.5 

Total acres treated 875.5 

1Note that approximately 83 acres within proposed aerial sites cannot be treated due to riparian buffer restrictions and 

would need alternative treatments (i.e ground based treatments: chemical, biological, physical). 

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Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix F – Aerial Modeling and Spray Guidelines 

Aerial Drift Modeling Results for Wallowa Whitman National Forest 

Spray Drift Summary. Based on the aerial drift modeling results that depict worst case scenarios 

allowable under PDF’s, the use of picloram and clopyralid for treatment of yellow starthistle and 

scotch thistle as proposed in Alternatives B, and C may cause a short-term impact to non-target 

native plants that are sensitive to small concentrations of applied herbicides. Picloram and 

clopyralid are both selective herbicides for use on broadleaved species. Clopyralid is somewhat 

more selective within the broadleaved species than picloram as described in Appendix D of this 

document. Off site drift of these two chemicals could potentially impact broadleaved species 

especially species particularly sensitive to low concentrations either of these two chemicals and 

also leaving native and non-native grasses non-impacted. Under worst case scenarios, 

concentrations of these two herbicides at a distance of 100 feet from the aerial application site 

are anticipated to be between approximately 18 to 25 times lower in proposed application rates at 

the treatment site. Although some broadleaved species may be impacted and grasses would 

remain non-impacted by the off site drift, it is expected that because of the remote locations of 

these sites, a resident native seedbank is sufficient enough to re-establish a native plant 

community in the upcoming years. Additionally, PDFs that establish monitoring guidelines and 

implementation of restoration actions including reseeding of native plants (if necessary) far 

outweighs the disadvantages of allowing the invasive plant site to continue to grow and spread. 

Introduction 

AGDISP is a mathematical model used to evaluate the potential for herbicides to move off site. 

This model was first developed by NASA, improved by the USDA Forest Service and 

implemented by the Spray Drift Task Force and the U.S. Environmental Protection Agency into a 

regulatory version (Teske et al.2003). 

Results from the output of this model that incorporates numerous factors affecting off-site drift is 

then used to predict possible impacts. A full description of the model can be found at the end of 

this discussion as well as at http://www.epa.gov/nerl/research/2000/html/g1-12.html. AGDISP 

Input Data Summary (example for Picloram at release height of 50 feet with swath displacement) 

can be found in the Botany Report. 

Site specific conditions associated with the proposed aerial sites were used as input parameters 

into the model. Slope, vegetation, and weather conditions were factors in the model, with spray 

application height, wind speed and droplet size as the three most significant factors impacting 

drift distance and the potential to affect non-target areas. Numerous iterations of the model were 

evaluated. Worst case scenarios were evaluated to develop PDFs that protect sensitive resources. 

In the case of aerial applications, the worst-case scenario is an adverse wind (meaning wind 

blowing from the point of release toward the resource or area you are trying to avoid). Spray 

droplet size and wind speed was modeled at the lowest mean droplet size (500μm) and wind 

speeds of 8mph allowable under PDFs. Three release heights were modeled for the largest aerial 

site (Table F-2). Clopyralid at 0.35 lb ai/acre and Picloram at 0.25 lb ai/acre are the highest 

amounts of chemical proposed for treatment of aerial sites. 

Conditions 

• 8 mile an hour cross winds toward the stream 

• median droplet size is approximately 500 microns 

• Release height 25, 35 and 50 feet off the ground 

• Side slope terrain angle of 40 degrees 

 F-7
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix F – Aerial Modeling and Spray Guidelines 

• Hiller 12E Solloy Helicopter 

• Spray nozzles located no less than 3⁄4 rotor distance (recommended to reduce drift and 

EPA label restriction for Picloram) 

• Vegetation 0.2 to 1meter in height 

• Swath width of 60 feet 

• Picloram at 1pt/acre (0.25lb ai/acre), clopyralid at 1.4 pt/acre (0.35lb ai/acre) 

Table F- 2 – Release heights and buffers 

25 ft release height 35 feet release height 50 feet release height 

Buffer width at 7-8 

mph 

Designated buffer – no 

swath width added 

Add 1 swath widths to 

buffer 

Add 2 swath widths to 

buffer 

Table F- 3 – Summary of AGDISP output 

Measurement Picloram 25’ Picloram 35’ with 1 

swath PDF 

Picloram 50’ with 2 

swath PDF 

Mean deposition 0.244 lb ai/acre 0.249lb ai/acre 0.245 lb ai/acre 

Efficiency 97.2% 98% 97% 

Airborne drift 0.32% 0.74% 1.32% 

Deposition at a terrestrial point 100’ 

from edge of application 0.01lbs ai/acre 0.01lbs ai/acre 0.017lbs ai/acre 

Measurement Clopyralid 25’ Clopyralid 35’ with 1 

swath PDF 

Clopyralid 50’ with 2 

swath PDF 

Mean deposition 0.341lb ai/acree 0.329lb ai/acre 0.337lb ai/acre 

Efficiency 97.3% 98.4% 97.2% 

Airborne drift 0.18% 0.451% 0.91% 

Deposition at a terrestrial point 100’ 

from edge of application 0.014lb ai/acre 0.015lb ai/acre 0.025 lb ai/acre 

Project Design Features for Wallowa Whitman National Forest 

PDFs for protection of resources include swath width set back in wind speeds of 8mph and 

release honolo of 35 feet and 50 feet as well as spray cards that are placed at certain distances 

around the site to estimate the quantatitive deposition of drift during actual applications. The use 

of drift reduction technology which includes specific nozzle design and or drift reduction 

additives (approved by the Regional FEIS) can also be used in conjuction or in replacement of 

swath width adjustments if spray card detection determines spray deposition remains within 

buffer limits. These PDF’s are fully described in Chapter 2 of this EIS. 

Monitoring Results from Other Studies 

Modeling results has been collected from the Lolo and Bitterroot National Forests in Montana. 

These results are expected to be similar to the results anticipated from aerial application on sites 

proposed on the Wallowa-Whitman National Forest. A full description of this modeling results is 

available in the Botany Report. 

 F-8 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix F – Aerial Modeling and Spray Guidelines 

AGDISP Model History (derived from users manual) 

To predict aerial spray deposition and drift with a computer model, we must first approximate the 

background atmospheric and aircraft wake behavior, in an effort to determine the effects of the 

atmosphere and aircraft wake on the released spray material. The approaches considered when 

aerial spray models were first developed included both Gaussian and Lagrangian formulations. 

By the late 1960s provision had been made in the U. S. Army’s Gaussian modeling techniques to 

account for the loss of material by gravitational setting of droplets from elevated spray clouds, 

and to predict the resulting surface deposition patterns. Additional algorithms considered the 

penetration of droplets into canopies, simple expressions for wake effects of spray aircraft, and 

droplet evaporation. This work was largely a collaboration by the USDA Forest Service and the 

U. S. Army with H. E. Cramer and his associates (Cramer et al. 1972; Dumbauld et al. 1977, 

1980). The computer code that resulted was called FSCBG (for Forest Service Cramer-BarryGrim after its developers), detailed in Teske et al. (1993). 

In 1979 Continuum Dynamics, Inc. began developing a Lagrangian model for the dispersal of 

spray material, utilizing the equations for particle motion first suggested by Reed (1953), and 

culminating in a model for NASA (Bilanin and Teske 1984) known as AGDISP (for Agricultural 

DISPersal). This approach included models for aircraft wake effects (vortices, propellers, and jet 

engines) and evaporation (Bilanin et al. 1989), and subsequently became the near-wake model for 

FSCBG. The AGDISP technology has now become the computational engine of choice in all 

active near-wake models in the United States, Canada, and New Zealand. Further development 

and refinement by the Spray Drift Task Force (SDTF) led to its regulatory version AgDRIFT 

(Teske et al. 2002a), by the New Zealand Forest Research led to its efficacy version SpraySafe 

Manager (Richardson et al. 1996), by the USDA Forest Service led to its ArcView/GPS version 

GypsES Spray Advisor (Teske and Curbishley 1998), and now to this, the latest version of 

AGDISP (Teske et al. 2003a). 

Both FSCBG and AGDISP (as well as all subsequent models) trace their origins to 1981, when 

the USDA Forest Service contracted with Ketron, Inc. to review the potential for developing and 

implementing a consistent and inclusive aerial spray model, using as a basis the first released 

version of FSCBG (Dumbauld et al. 1980). The final report (Weeks et al. 1982) is most 

impressive for the vision included in its recommendations. Those familiar with the model at that 

time were perhaps unaware of its potential in the areas suggested, especially as a predictive 

platform for the development of decision support. Subsequent tasking – funded for the most part 

by the USDA Forest Service – implemented many of the report’s suggestions, and brought model 

development to an operational level that permitted subsequent and ongoing model extension. A 

complete review of scientific research associated with testing this model can be found at: 

http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&DbFrom=pubmed&Cmd=Link&LinkNa

me=pubmed_pubmed&LinkReadableName=Related%20Articles&IdsFromResult=11878480&or

dinalpos=1&itool=EntrezSystem2.Pentrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVAbstractPl

us 

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Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix F – Aerial Modeling and Spray Guidelines 

Aerial Spray Guidelines 

These guidelines are intended as a practical field guide for weed managers who may be 

considering use of aerial herbicide application as part of an integrated pest management program. 

Some of the terminology and work force, fiscal year, planning references are specific to Forest 

Service project planning. The information and observations in this guide are specific to large 

droplet liquid herbicide applications and does not address pellet, insecticide or other fine droplet 

aerial application projects. 

Why Aerial Spray? 

Scale: The impacts of weeds on native vegetation, wildlife, soils, fisheries, aesthetics, wilderness 

and a host of other resources are widely recognized by both the public and land managers. At the 

same time, the invasive plant problem in the northern Rockies has grown beyond the scale of 

ground based weed control. 

While ground based and biological weed management practices still are important elements in an 

IWM program, they have site and species limitations. Ground based application methods such as 

truck, ATV, horseback, backpack or atomizer applications are generally most effective on: 

• New or small infestations or 

• Infestations on flat and/or open ground and 

• Near a road or trail 

Biological control alone, while effective and applicable in certain situations, is: 

• Often cyclic, 

• Not available for many weed species, 

• Not as effective on weed infestations with several weed species and 

• Not effective for small or pioneering infestations scattered over a large landscape. 

• Not effective on complex terrain with a wide range of slope, aspect, soil and canopy 

combinations. 

Aerial application is an efficient and useful method land mangers can add to their IWM toolboxes 

for weed infestations involving: 

• Multiple weed species, 

• At landscape scale, and 

• On steep and remote areas 

Cost: Aerial application reduces costs in at least two ways. Helicopter aerial application in the 

area costs around $42 / acre. Ground based applications can range from $100 to $125 / acre for 

truck based broadcast spraying or backpack applications. The lower application cost combined 

with the growing scale of the problem puts aerial application in a useful position when we 

consider that weed infestations are growing faster than any anticipated increases in weed budgets. 

Access: Many wildland infestations are occurring in remote and/or very steep topography. Aerial 

application can quickly (in terms of application time), safely (in regards to applicator and public 

exposure) and efficiently (in terms of infested area coverage) treat infestations far from roads and 

trails and in steep or otherwise undrivable terrain. 

 F-10 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix F – Aerial Modeling and Spray Guidelines 

Safety: Exposure: Aerial application improves safety and reduces worker and public exposure to 

herbicides. Worker exposure and risk are influenced by the: 

• Time a worker is exposed to a product, 

• Physical proximity and exposure to a product, 

• Personal protective equipment and safe handling practices, 

• Toxicity of the product, 

• Terrain, hazards, and weather in the treatment area. 

Aerial application reduces application time and the time a worker is exposed to a product. It also 

reduces the number of applicators needed to accomplish a project and the chance of slips, falls 

and spills associated with ground based treatments in steep, remote or hazardous terrain. 

Aerial applications require All aviation activities shall be in accordance with FSM 5700 (Aviation 

Management), FSH 5709.16 (Flight Operations Handbook)FSM 2150 (Pesticide Use 

Management and Coordination), , FSH 2109.14, 50 (Quality Control Monitoring and PostTreatment Evaluation). 

Public impacts are influenced by: 

• The time it takes to treat an area and the resulting limitations on public use / access, 

• Individual physical or philosophical sensitivity to a product, and 

• Toxicity of the product. 

Aerial application reduces the time that a treatment area is unavailable to the public. It also 

provides an aerial platform from which an applicator can see people who may have unknowingly 

entered a treatment area. 

Weather and wind patterns also affect worker and public exposure. Aerial application reduces the 

potential for both worker and public exposure from weather related factors because you can 

accomplish more acres in less time and thereby capitalize on favorable weather conditions. 

Worker and public exposure are reduced when it takes less time to treat a larger area. 

Efficacy: Aerial application allows a manager to quickly complete projects when the target 

weed(s) is at the most susceptible honological stage and weather conditions are most favorable 

for efficacy. This maximization of efficacy factors can reduce the number and scale of follow up 

treatments. 

Overgrazing and Grazing Animal Distribution: Lower application costs allow for more 

ecologically compatible weed management. With lower application costs, a manager can afford to 

treat a larger project area at once. Higher treatment costs may necessitate treatment of only a 

portion of a project area each year. This can inadvertently attract big game or livestock to the 

treated area and result in overgrazing. Overgrazing in turn can reduce the retreatment interval. By 

treating larger areas at one time, big game and livestock will be better distributed over a larger 

area as they express preference for the improved forage resulting from the treatment. 

Reduced Wildlife Disturbance: The short operational time needed for aerial treatment 

minimizes wildlife disturbance and use of an area. Aerial applications may typically take only one 

operational day compared to a week to a month for ground-based treatments. 

Visual Quality: Lower application costs that allow treatment of larger areas with a single entry 

reduce the visual impacts that result from annual treatment of only a portion of the project area. 

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Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix F – Aerial Modeling and Spray Guidelines 

The color and texture of a landscape scale treatment is homogeneous rather than broken up by 

color, texture and straight lines. 

Aerial Spray Control Strategies 

Weed management objective: Weed managers should develop realistic and obtainable weed 

management objectives before beginning a direct weed control program. Even selective 

herbicides will affect non-target forbs. The effect of invasive weeds on native or desirable 

vegetation needs to be recognized and considered in relation to the effect of herbicides on nontarget vegetation. Aerial application is a general treatment and it can be difficult to avoid small or 

isolated non-target vegetation. Non-target vegetation can be flagged and smaller sites can be 

tarped to avoid treatment, but the effect of weed control on individual non-target plant species 

should be carefully weighed in relation to the effect of unchecked weed spread on the overall 

population viability of non-target species both on and off the treatment site. 

The herbicides and rates used for weed control in the area are generally selective (depending on 

rate) and many do not generally kill woody vegetation or grasses. While woody vegetation may 

show short-term effects, widespread mortality or damage is uncommon. Forbs are the non-target 

plants most at risk from the use of wildland weed herbicides. Whether native forb impacts are 

long term or short term depends on the rate and frequency of treatment, which is influenced by 

size of the infestation and whether you have rhizomatous or non-rhizomatous weeds. 

While an objective to “Restore native plant communities” may be desirable, it may be unrealistic 

or unobtainable on widespread or rhizomatous weed infestations. More realistic and obtainable 

objectives may include: 

• Improving or protect existing or adjacent native plant communities, 

• Improving wildlife forage areas, 

• Preventing new weed species from establishing in an area, 

• Containing or reducing the acreage of difficult to control weeds (such as rhizomatous 

species) and/or 

• Controlling areas of weeds growing in large difficult terrain to access by ground. 

• Controlling widespread weeds on areas with high resource value (such as concentrated 

public recreation areas, big game winter ranges, or adjacent to neighboring landowners 

with active weed control programs). 

Spring vs. Fall Treatments 

Both spring and fall treatments have advantages and disadvantages. Fall treatments have less 

effect on non-target forbs. Climatologically, the weather is more consistent in the fall, but may be 

consistently too cold, especially in the morning. A drawback is that there is greater annual 

variability in the fall treatment window. It is difficult to know (and plan) when the fall treatment 

window will arrive. On some years there may be no fall treatment window due to warm weather 

and no rainfall. If it does arrive, it may last only a week or as long as several weeks. The end of 

the fall window can arrive abruptly with the snowfall and cold windy weather. 

The spring treatment window is relatively long and dependable in terms of start and end date and 

falls at a time when you know and can plan for budget and staff. The days are longer in the 

spring, which allows more application time (and acres) each day. Late sunset gives application 

operations the option of shutting down midday if the wind comes up and resuming in the evening 

 F-12 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix F – Aerial Modeling and Spray Guidelines 

when the wind dies down. Both seasons can conflict with aircraft availability as a result of 

prescribed burning or wildfires. 

Re-treatment Considerations 

Before beginning an aerial treatment program, re-treatment needs, funding and scheduling should 

be considered. Keep in mind that the objective is not to simply kill the existing standing weed 

crop, but to: 

• Restore and/or encourage desirable and competitive vegetation and 

• Deplete the weed seed soil bank. 

With these objectives in mind, a single treatment may be insufficient. As with all weed control 

methods, initial herbicide treatments should include planning for follow up treatments. Follow up 

treatment frequency should be influenced by the soil seed life of the most abundant and longestlived weed on the site and the residual control provided by the herbicide selected. Spotted 

knapweed for example, has a soil seed life of about eight to 10 years. Once a treatment program 

begins, managers should plan for follow up treatments based on the soil seed life of the weeds 

present and the residual control of the herbicide selected. 

For example, if spotted knapweed is being treated with picloram, a manager may consider follow 

up treatments every three growing seasons (the approximately residual control period for 

picloram) for three to four cycles (3 growing seasons x 3 to 4 cycles = 9 to 12 years – the 

approximately soil seed life for knapweed). Commitment to this program is important because if 

a cycle is missed and a weed seed crop is allowed to develop, the treatment cycle may have to be 

extended. 

Pre-field Project Preparation 

It is helpful to develop a checklist of the protection measures and management requirements. This 

checklist should clearly identify tasks and provide a place to date and sign off as each task is 

completed. This checklist should be filed in the project file. Some of the items that can go on the 

checklist include: 

• Protection Measures from NEPA decision. 

• Pesticide Use Proposal 

• Notification of neighbors (Note: neighboring landowners may want to treat their lands 

when they learn a project is scheduled next to them) 

• Pretreatment monitoring plots (these plots should be established during the growing 

season prior to the treatment) 

• Designation of Aerial Equipment Manager (helicopter manager) 

• Recon and selection of a helibase (close to treatment area, good road access, away from 

waterways, reviewed and OK’d by pilot) 

• Posting of the area to be treated 

• Establish temporary closure orders, when needed. 

• Identification and marking of sensitive areas to be avoided 

• TES plant and animal considerations 

 F-13
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix F – Aerial Modeling and Spray Guidelines 

Field Project Layout 

It is difficult to pre-determine the treatment day due to weed phenology, weather, and aircraft 

availability. It is recommended that aerial spray projects be prepped well in advance (2 to 4 

weeks) of the anticipated treatment date. 

Ground truthing: Treatment units should be carefully ground truthed prior to treatment to 

determine: 

• Weed species and distribution • 

• Road system and any differences in roadside infestations in relation to off road 

infestations 

• Herbicide prescription considering both weeds and native vegetation 

• Live water, wet areas or other sensitive resources you want to avoid 

• Overstory canopy closure 

This information can be recorded on aerial photographs that include project boundaries and other 

adjacent or in holding ownerships. Two copies of these aerial photos should be made, one copy 

for the project manager and one set for the application pilot to have on board the aircraft. When 

possible, geo-reference the aerial photo information in order to be able to give the pilot GPS 

location information. 

Buffers and No Treatment Areas: Buffer and no treatment areas should be established around 

any sensitive resource you want to avoid. These areas may include live water, wet areas, other 

land ownerships, TES plants or occupied areas. Aerial treatment buffer zones may vary 

depending on site characteristics. Treatments may also be designed to avoid any aerial treatment 

near sensitive resources. The width of an aerial treatment buffer zone near sensitive resources 

should consider: 

• Slope (steeper = wider) 

• Vegetation (less overstory vegetation = wider) 

• Wind prescription (applications should be made only with low upslope winds) 

• Overstory vegetation (which determines release height – higher release height = wider 

buffer) 

• Use of a drift agent (no drift agent = wider buffer- drift reduction agents are 

recommended near buffer areas) 

• Droplet size (smaller droplet size = wider buffer) 

• Topographic position (narrow deep draws = wider buffer areas) 

• Sensitivity of neighboring landowners (more sensitive = wider buffer) 

Buffer Monitoring: Water sensitive “drift cards” can be placed as needed within the buffer zones 

to document herbicide placement. The number of drift card lines should be determined by the 

sensitivity of the resource and the size of the area. The number of card lines should be considered 

carefully because they are time intensive and require additional project staff. Cards should: 

• Be placed equidistance within the buffer from the sensitive resource to the beginning of 

the treatment area. 

• Have the Line # and location on the line recorded on each card at the time of placement. • 

be placed 10 feet to 10 yards apart depending on the width of the buffer area. 

• Be placed on drift cardholders. 

 F-14 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix F – Aerial Modeling and Spray Guidelines 

• Be placed immediately before application and picked up and stored in waterproof bags 

immediately after treatment. 

• Not be placed the day or evening before early morning applications due to dew, fog or 

humidity contamination. 

• Be laid out in a dry office setting in the order they were placed and interpreted as soon as 

practical. (Cards often come with interpretation information and sampling square 

templates.) 

• Filed in waterproof bags in the project file. 

It is critical that those placing drift cards be briefed on handling, placement, contamination, 

collection and storage of the cards. Those placing and picking up the cards should carefully check 

the card condition as they are placed and picked up and note any non-herbicide contamination. 

Contamination can include fog, high humidity, dew droplets off leaves, moisture on your hands, 

improper card handling, rodent urine or foot prints, wildlife or insect moisture and/or feeding on 

the cards. 

If drift cards are used, card lines should also be placed in treatment areas under full spray 

conditions to serve as a reference for determining percentage of full spray on cards in buffer areas 

that have detection. The purpose of buffers is to protect the resource that is at the end of the buffer 

area, so detection within the buffer areas may be acceptable as long as the sensitive area itself is 

protected. 

In-stream water sampling has limitations in that it is expensive, should be sterile and automated to 

avoid contamination, only indicates whether herbicide reached a water way in detectable 

quantities, does not indicate how close herbicide may have come to the sensitive resource and is 

subject to dilution depending on stream volume and velocity. 

Drift Mitigation Measures: Drift mitigation measures may include: 

• Use of a drift agent 

• Use of buffer areas next to sensitive resources 

• On site weather monitoring 

• Treatment next to sensitive areas when wind is upslope and gentle 

• No treatment during inversions 

• No treatment when winds in the project area are > 6 mph 

• No treatment when weather forecasts predict rain in next 24 hours 

Unit Marking Strategies: In agricultural or residential settings treatment area boundaries are 

clearly defined by fences, roads and / or buildings. Wildland project managers should identify 

treatment areas on the ground and be sure the application pilots know where treatment and no 

treatment areas are. Wildland unit marking strategies fall into two general categories: 

• Identification of specific treatment polygons and delineation of where to treat within a 

larger project area, or 

• Identification of the general project area and delineation of areas not to treat. 

Large wildland treatment areas that include many polygons and a mix of timbered and open areas 

may be difficult to mark and find from the air. If treatment units are large and there are only three 

to five in the project area it may be practical to mark each individual unit. If there are many units 

in a large area, it may be more efficient to mark the project area boundary and buffers and instruct 

the pilot which areas not to treat within the larger project area. The no treatment areas could 

 F-15
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix F – Aerial Modeling and Spray Guidelines 

include marked buffer areas (which would include waterways and wet areas), talus, rock and 

cliffs and areas with a closed overstory canopy. 

On the Ground Unit Marking: Technology is rapidly developing that allows managers to mark 

treatment units digitally. On the ground block marking is the most expensive part of project 

layout and through the use of digital marking may be eventually eliminated. Some on the ground 

features and topography may require some degree of on the ground marking. 

When on the ground marking is needed, uniform unit marking is recommended to ensure 

consistency between treatment blocks, different ranger districts and to reduce pilot workload. 

Unit marking can be done with high contrast, high strength flagging staked or rocked to the 

ground or with aerosol survey paint. Markings should be kept as simple as possible. Frequency of 

marking should depend on the specific site and site features. Some suggested unit markings are: 

• Treatment unit boundary: The vertical line should be on the unit boundary with the 

perpendicular line pointing into the treatment unit. These markings can also be places 

were roads enter and leave the treatment units. A unit number can be added for further 

aerial orientation. 

• A horizontal line to mark the edge of a buffer or area to be avoided. The line should be 

parallel to the feature inside the buffer area. 

All ground marking schemes should be closely coordinated with the application pilot. 

Digital Unit and Treatment Marking: GPS guided navigational devices are available that allow 

an aircraft to develop a digital treatment polygon file from either a recon flight or an on the 

ground unit layout. These digital shapes appear on a navigational screen in the aircraft and are 

used to guide the pilot to the units. GPS line files are collected for each spray swath and are 

displayed on the polygon on the screen during application. These swath lines can be printed after 

application to provide a digital map record of the treated area. The swath width can be loaded into 

the program to generate area treated based on swath length and width. 

Pretreatment Recon Flight: On or before treatment day, the pilot and project manager should fly 

the project area with aerial photos in hand to review and discuss treatment area, boundaries, other 

ownerships, buffer zones and on the ground marking. It is helpful for the project manager to GPS 

key project locations (such as unit corners or sensitive areas) prior to the flight to allow the pilot 

and project manager to quickly and efficiently orient from within the aircraft. Things can look 

different from an aircraft than from the ground and this step can save flight time. 

Equipment 

Helicopter and fixed wing aircraft are available for aerial application work. Helicopters have been 

better suited to the steep topography and diverse vegetation. 

Aerial applicators typically come with a mix truck equipped with aviation fuel tanks, water tanks, 

a mix tank and a mix master. Water can be supplied by the Forest Service or by the applicator. 

Applicator mix trucks are not typically suited to travel over rough or steep forest roads so it is 

recommended to select a mix site / helibase with relatively easy road and water access. Forest 

Service rented water tenders can add expense to the project and Forest Service engines may be 

difficult to schedule during wildfire or prescribed burning season. Pump and hose fitting need to 

be compatible between Forest Service engines and mix trucks. Water should be clean or potable 

to avoid plugging up the spray system. 

 F-16 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix F – Aerial Modeling and Spray Guidelines 

Aerial Spray Recommendations 

The treatment block should be marked with flagging to mark the block corners or clearly 

described and reviewed with applicator. It is be desirable to have a GPS system on board to 

record helicopter swaths, position, and boom on and off times and location. 

In canyon areas, winds should follow the typical diurnal pattern of upslope during the day and 

down slope during the night. These diurnal winds result from heating and cooling of the surface. 

Clear skies with solar radiation reaching the surface during the day cause up canyon and upslope 

winds. Cooling that occurs after sunset generates upslope or drainage winds. Given that 

waterways/riparian areas are often located in the bottom of canyon areas, it is essential to avoid 

drift down canyon and downslope. Down canyon and downslope winds will likely occur on clear 

days following daytime hours. To prevent spray from drifting down canyon/downslope, winds 

should be up canyon and upslope. Also, inversion can result in spray drifting off site; winds 

indicate that an inversion is not present. 

Avoid spray drift impacting non-target sites by taking the following steps: 

• When treating next to sensitive areas spray in the morning when up canyon and upslope 

winds are well established and blowing up canyon (most sensitive areas are down 

canyon). The specific time will need to be determined by real-time weather monitoring. 

• Maintain boom pressure at less than 40psi. 

• Monitor spray pressure during flight, since changes in pressure can change the 

application rates and may change the drop size. 

• Use nozzles designed for medium to coarse droplet size (240 to 400 microns) 

• Use drift agent to help maintain large droplet size. 

• Check nozzles and review calibration with pilot. 

• Begin the first swath 300 feet from any sensitive area. 

• Mark boundaries so they are clearly understood by the pilot. Fly area with pilot prior to 

treatment to verify location. Use GPS to document boundaries and record treatment flight 

paths. 

• Monitor treatment boundaries next to sensitive areas with spray deposit cards to detect 

any possible drift. Train people in how to handle the cards, interpret the cards (many 

things can contaminate the cards such as dew, moisture from hands, insects) and also 

document results. Card lines should also be placed in treated areas under full spray to 

serve as a reference. 

• Monitor and record weather in the area. The weather should be monitored in real time for 

operational control and to help with the post-spray analysis. Strive for winds from 3 to 6 

miles per hour or per label instruction. Do not treat if rain is predicted within next 24 

hours. 

• Consider using Forest Service Cramer-Barry-Grim (FSCBG) or AGDISP computer 

models to evaluate drift potential and to develop operational and drift protection 

measures prior to treatment. 

Post Treatment Considerations and Tasks Post treatment tasks may include: 

• Monitor and document in the project file daily rainfall for up to a week after treatment 

 F-17
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix F – Aerial Modeling and Spray Guidelines 

 F-18 

• Schedule reading of monitoring plots between 1 growing season and 1 year after 

treatment 

• Read drift cards and complete a drift report 

• Compile a treatment project file for reference for the next retreatment 

• Add the project to the retreatment schedule • Pick up ribbon and any other unit markings 

• Complete contract daily diary and submitting original to the Contracting Officer • 

Completing a Post Treatment Evaluation (FSH 2109.14 Ch 72.1) 
Appendix G – Adjuvants and Drift Reduction 

Agents 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix G-Adjuvants and Drift Reduction Agents 

 G-2 

This Page Left Blank Intentionally 
Wallowa Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix G-Adjuvants and Drift Reduction Agents 

Table G-1 – Adjuvants and Drift Reduction Agents Approved for Use on the Wallowa Whitman 

National Forest (Derived from R6 2005 FEIS). 

Formulations Ingredients of Adjuvants 

(aka Category)) Manufacturer 

Washington 

State 

Approved 

for Aquatic 

Areas 

Risk Assessment 

ID 

(comment) 

Activator 90® 

Alkylphenol ethoxylatebased wetter/spreaders 

(non-ionic) aka NPE 

Loveland Products 

 

Activator N.F. 

Alcohol ethoxylate-based 

wetter/spreaders (nonionic) 

Loveland Products 

may no longer be 

available 

Agri-dex® Crop Oils and Crop Oil 

Concentrates 

Helena Chemical 

Co. YES 

Bond® Sticker/Spreaders Loveland Products YES 

Cide Kick® IITM Vegetable or Seed Oils Brewer 

International 

 

Cide-Kick® Vegetable or Seed Oils Brewer 

International 

 

Class Act® Next 

Generation 

Fertilizer/Surfactant 

Mixtures Agrilliance, LLC 

Class Act® Next 

Generation in 

section 1 

Cohere® Sticker/Spreaders Helena Chemical 

Co 

 

ColorfastTM

Purple Colorants and Dyes BeckerUnderwood, Inc 

Contains Gentian 

Violet, potential 

carcinogen. Refer 

to SERA, 1997 

Competitor Vegetable or Seed Oils Wilbur-Ellis 

Company 

 

Cygnet Plus Vegetable or Seed Oils Brewer 

International YES 

Dyne-Amic® Vegetables Oils and 

Silicone Blends 

Helena Chemical 

Co YES 

Ethoxylated fatty amines 

(Cationic) EntryTM II 

aka POEA 

Monsanto 

Company 

 

First Choice®

Exciter 

Fertilizer/Surfactant 

Mixtures 

Western Farm 

Service YES 

FoaminatorTM Defoamers Agrilliance, LLC 

Freeway® Silicone-based 

wetter/spreaders Loveland Products 

Hasten® Vegetable or Seed Oils Wilbur-Ellis 

Company 

 

Herbimax® Crop Oils and Crop Oil 

Concentrates Loveland Products 

Hi-LightTM Blue Colorants and Dyes BeckerUnderwood, Inc 

Not durable. Lasts 

hours. 

Improved JLB 

Oil Plus Vegetable or Seed Oils Brewer 

International 

 

In-Place® Drift reduction agents Wilbur Ellis 

Company 

Efficacy of drift 

reduction agents is 

unknown 

 G-1
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix G-Adjuvants and Drift Reduction Agents 

 G-2 

Formulations Ingredients of Adjuvants 

(aka Category)) Manufacturer 

Washington 

State 

Approved 

for Aquatic 

Areas 

Risk Assessment 

ID 

(comment) 

Intensify Fertilizer/Surfactant 

Mixtures West Link Ag YES 

InterLock® Drift reduction agents Agrisolutions YES 

Efficacy of drift 

reduction agents is 

unknown 

Kerosene, 

deodorized 

Crop Oils and Crop Oil 

Concentrates 

found in the 

triclopyr 

formulation Garlon 

4 

 

KineticTM Silicone-based 

wetter/spreaders 

Helena Chemical 

Company YES 

Alkylphenol ethoxylatebased wetter/spreaders 

(non-ionic) Latron AG-98 

(N)® 

a NPE 

Dow AgroSciences 

LLC 

may no longer be 

available 

Alkylphenol ethoxylatebased wetter/spreaders 

Latron AG-98® (non-ionic) 

aka NPE 

Dow AgroSciences 

LLC 

may no longer be 

available 

LI-700® Acidifiers Loveland Products YES 

Liberate® Drift reduction agents Loveland Produnts YES 

Efficacy of drift 

reduction agents is 

unknown 

Magnify Fertilizer/Surfactant 

Mixtures 

Monterey 

AgResources YES 

MSO® Vegetable and Seed Oils Loveland Products 

No Foam Defoamers Wilbur Ellis 

Company 

 

No Foam Dry Defoamers Wilbur Ellis 

Company 

 

No Foam® B Defoamers Creative Marketing 

and Research 

 

PhaseTM Vegetables Oils and 

Silicone Blends Loveland Products 

Alkylphenol ethoxylatebased wetter/spreaders 

(non-ionic) Pro-Spreader 

Activator 

aka NPE 

Target Specialty 

Products, Inc. 

 

Alkylphenol ethoxylatebased wetter/spreaders 

R-11® (non-ionic) 

aka NPE 

Wilbur-Ellis 

Company 

 

R-56® Sticker/Spreaders Wilbur-Ellis Co. 

Red-Top MorAct® Crop Oils and Crop Oil 

Concentrates 

Wilbur-Ellis 

Company 

 
Wallowa Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix G-Adjuvants and Drift Reduction Agents 

 G-3

Formulations Ingredients of Adjuvants 

(aka Category)) Manufacturer 

Washington 

State 

Approved 

for Aquatic 

Areas 

Risk Assessment 

ID 

(comment) 

Ethoxylated fatty amines 

(Cationic) Roundup® has 

15% POEA in 

this formulation aka POEA 

 

 

Silwet L-77® Silicone-based 

wetter/spreaders 

Loveland and 

Helena 

 

Sinker Drift reduction agents Helena Chemical 

Company YES 

Efficacy of drift 

reduction agents is 

unknown 

Sylgard ® 309 Silicone-based 

wetter/spreaders 

Wilbur-Ellis 

Company 

 

Syl-tacTM Vegetables Oils and 

Silicone Blends 

Brewer 

International 

 

TacticTM Sticker/Spreaders Loveland Products YES 

The surfactant 

in PathfinderTM 

II (a triclopyr 

formulation) 

Oils Dow AgroSciences 

 

Tri-fol® Acidifiers Wilbur Ellis 

Company 

 

Alkylphenol ethoxylatebased wetter/spreaders 

(non-ionic) X-77® 

aka NPE 

Loveland Industries 

 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix G-Adjuvants and Drift Reduction Agents 

This Page Left Blank Intentionally

 G-4 
Appendix H – Social-Economics 

Retricted Use Alternative Analysis Model

 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement

 

This Page Left Blank Intentionally 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix H-Social Economics 

Chapter 2.3.5 Restricted Use Alternative Analysis Model 

The Restricted Use Alternative attempts to control weeds over the 10- to 15-year life of the 

project by using all available treatment methods. Its distinction from the proposed action is that 

herbicide treatment would not be allowed in riparian and special areas including wilderness, wild 

and scenic river corridors, municipal watersheds, and within 100 feet of SOLIs. The strategy 

would be to treat as many infested acres as early as possible. Therefore the initial emphasis is on 

broadcast herbicide applications in the uplands because broadcast application of herbicide is the 

most cost effective way to treat the most acres. Once the uplands are treated the emphasis shifts to 

treating riparian and special areas using manual/mechanical methods. During all years of the 

project, some of all treatment methods may be used, however the clear strategy emphasizes 

herbicides early in the project, then progressively moves away from herbicide treatments in favor 

of manual/mechanical and biocontrol methods as time goes on. 

This spreadsheet models the Restricted Use Alternative discussed in section 2.3.5 of chapter 2. 

Like the Proposed Action, the model begins in year 1 (row 7 of the spreadsheet below) of the 

project with 22,842 acres of known invasive plant infestations to be treated (column B). In the 

first year available funding is spent using herbicides to treat approximately 4000 infested acres in 

the uplands. Years 2 and 3 (row 8 and 9) similarly treat approximately 3200 acres of previously 

untreated weeds (column E) and 800 acres previously treated (column G). At the same time, a 

minor acreage of manual/mechanical treatments may also occur in riparian and special areas (see 

alternative description in 2.3.5). The funding, acres treated and treatment methods in the first 

three years is virtually the same as the Proposed Action (Alternative B) except that treatment 

location is entirely in the uplands and not in any special areas, whereas Alternative B may treat in 

riparian and special areas with herbicides, as well as in the uplands. 

Beginning in year 4 (row 10), differences between the Restricted Use Alternative and Alternative 

B begin to emerge. Sometime during year 4, herbicide treatment of the 11,179 acres of targeted 

upland areas not previously treated is completed. The herbicide retreatment continues and the 

remaining budget is spent on treating riparian or special areas using manual/mechanical and 

biocontrol methods. By year 5 (row 11), project emphasis is shifting from herbicide treatment 

methods to manual/mechanical methods. Treatment locations are also changing; shifting away 

from the uplands and focusing on riparian and special areas. 

Because manual/mechanical methods cost more per acre, fewer acres can be treated given the 

same annual project budget. Per acre costs for each treatment method (columns Y – AK) used for 

this model are detailed in Chapter 2 of this EIS and are used to analyze Alternative B. Besides 

being more expensive, manual/mechanical methods are also less effective than herbicide 

treatments. Again the same assumptions of treatment method effectiveness used to analyze 

Alternative B were used to analyze this alternative. That is, 80 percent effective for herbicide 

treatments (column H) and 25 percent effective for manual/mechanical treatments (column I) (see 

Chapter 3.2 of this EIS for a more detailed discussion of effectiveness assumptions). 

Initially, acres of weed infestation are reduced suggesting that the project purpose and need of 

eradicating, containing, and controlling weeds would be accomplished. However beginning in 

year 5, as herbicide use is curtailed and manual/mechanical methods are emphasized, the trend of 

weed reduction reverses and acres of weed infestation forestwide begin to increase. Ultimately, 

by the end of the project the area of weed infestation would roughly double from the present 

infestation level. 

 H-1
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statement 

Appendix G-Adjuvants and Drift Reduction Agents 

 H-2 

This spreadsheet is an approximation. Its purpose is not to precisely predict acres of weed 

infestation during the life of the project. Its purpose is to show trends of this alternative compared 

to the Proposed Action Alternative. 
Wallowa-Whitman National Forest Invasive Plants Treatment Draft Environmental Impact Statemen

H-3

Year

Total 

Remainin

g 

Untreated 

Acres 

Total 

Remainin

g 

Untreated 

Upland 

Acres

Total 

Remainin

g NonUpland 

Acres

Upland 

Acres 

Treated 

First time

NonUpland 

Acres 

Treated 

(First 

Time) 

Total acres retreated

Acres 

Retreated 

(c = 20% 

of prior 

year's e)

Acres 

Retreated 

(Manual.

Mechanic

al, 75% 

of prior 

year M/M 

treatment

s) 

Total 

Acres 

Treated 

(c+d)

Remainin

g 

Untreated 

Acres (bc)

Estimated 

Acres of 

spread 

(Est. 10 

% of 

untreated 

acres and 

5% of 

treated 

areas) 

(.10*f+.o

5*(.2*e))

Acres of 

Manual/Mechanical 

and or 

Herbicide 

Treatment (e*16.899

%)

Acres of 

Herbicide -

spot 

(e*3.984

%)

Acres of 

Manual 

only 

treatments 

(e*0.306%

)

Acres of Biocontrol.Manual, Mechanical, Chemical (e*0.263%)

Acres of Biocontrol (e*0.376%)

Acres of 

Aerial 

(e*23.785

%)

Acres of 

Manual/Mechanical 

and or 

Herbicide 

Treatment (e*39.077

%)

Acres of 

Herbicide -

spot 

(e*6.948

%)

Acres of 

Manual 

only 

treatments 

(e*0.179%

)

Acres of Biocontrol.Manual, Mechanical, Chemical (e*0%)

Acres of Biocontrol (e*8.182%)

Acres of 

Aerial 

(e*0%)

Acres of 

Manual/Mechanical 

and or 

Herbicide 

Treatment 

(i*$313)

Acres of 

Herbicide 

- spot 

(j*$350)

4000 2400

1 22,842 11,179 11,663 4,000 0 0 0 4,000 22,842 2,324 676 159 12 11 15 951 1,563 278 7 0 327 0 $211,575 $55,776 2 21,166 7,579 12,829 3,200 800 800 0 4,000 21,166 2,157 676 159 12 11 15 951 1,563 278 7 0 327 0 $211,575 $55,776 3 20,123 4,739 14,112 3,200 800 800 0 4,000 20,123 2,052 676 159 12 11 15 951 1,563 278 7 0 327 0 $211,575 $55,776 4 18,975 1,899 15,523 1,899 780 800 800 0 3,479 18,195 1,854 511 108 229 7 13 720 1,109 188 311 0 285 0 $159,850 $37,635 5 18,930 230 16,296 230 1,350 1,125 540 585 2,705 17,580 1,785 266 31 549 2 10 377 436 53 760 0 221 0 $83,108 $10,733 6 20,486 50 16,605 50 825 1,605 154 1,451 2,480 19,661 1,991 194 8 643 1 9 276 239 14 893 0 203 0 $60,659 $2,843 7 22,426 13 17,513 13 660 1,748 41 1,707 2,421 21,766 2,201 175 2 669 0 9 249 187 4 928 0 198 0 $54,694 $746 8 23,967 3 18,689 3 611 1,786 11 1,775 2,400 23,357 2,360 169 1 674 0 9 242 172 1 935 0 196 0 $53,018 $195 9 25,716 1 20,036 1 607 1,792 3 1,789 2,400 25,110 2,535 168 0 677 0 9 241 169 0 939 0 196 0 $52,698 $51 

10 27,645 0 21,523 0 602 1,798 1 1,797 2,400 27,043 2,728 168 0 677 0 9 240 168 0 940 0 196 0 $52,614 $13 11 29,771 0 23,163 0 600 1,799 0 1,799 2,400 29,171 2,941 168 0 678 0 9 240 168 0 941 0 196 0 $52,592 $4 12 32,112 0 24,969 0 600 1,800 0 1,800 2,400 31,511 3,175 168 0 678 0 9 240 168 0 941 0 196 0 $52,586 $1 13 34,687 0 26,956 0 600 1,800 0 1,800 2,400 34,087 3,433 168 0 678 0 9 240 168 0 941 0 196 0 $52,585 $0 14 37,519 0 29,141 0 600 1,800 0 1,800 2,400 36,919 3,716 168 0 678 0 9 240 168 0 941 0 196 0 $52,584 $0 15 40,635 0 31,545 0 600 1,800 0 1,800 2,400 40,035 4,028 168 0 678 0 9 240 168 0 941 0 196 0 $52,584 $0 16 44,063 0 34,190 0 600 1,800 0 1,800 2,400 43,463 4,370 168 0 678 0 9 240 168 0 941 0 196 0 $52,584 $0 17 47,833 0 37,099 0 600 1,800 0 1,800 2,400 47,233 4,747 168 0 678 0 9 240 168 0 941 0 196 0 $52,584 $0 18 51,980 0 40,298 0 600 1,800 0 1,800 2,400 51,380 5,162 168 0 678 0 9 240 168 0 941 0 196 0 $52,584 $0 19 56,542 0 43,818 0 600 1,800 0 1,800 2,400 55,942 5,618 168 0 678 0 9 240 168 0 941 0 196 0 $52,584 $0 20 61,560 0 47,690 0 600 1,800 0 1,800 2,400 60,960 6,120 168 0 678 0 9 240 168 0 941 0 196 0 $52,584 $0 21 67,080 0 51,949 0 600 1,800 0 1,800 2,400 66,480 6,672 168 0 678 0 9 240 168 0 941 0 196 0 $52,584 $0 22 73,153 0 56,634 0 600 1,800 0 1,800 2,400 72,553 7,279 168 0 678 0 9 240 168 0 941 0 196 0 $52,584 $0 23 79,832 0 61,787 0 600 1,800 0 1,800 2,400 79,232 7,947 168 0 678 0 9 240 168 0 941 0 196 0 $52,584 $0 24 87,179 0 67,456 0 600 1,800 0 1,800 2,400 86,579 8,682 168 0 678 0 9 240 168 0 941 0 196 0 $52,584 $0 25 95,261 0 73,692 0 600 1,800 0 1,800 2,400 94,661 9,490 168 0 678 0 9 240 168 0 941 0 196 0 $52,584 $0 26 104,151 0 80,551 0 600 1,800 0 1,800 2,400 103,551 10,379 168 0 678 0 9 240 168 0 941 0 196 0 $52,584 $0 27 113,930 0 88,096 0 600 1,800 0 1,800 2,400 113,330 11,357 168 0 678 0 9 240 168 0 941 0 196 0 $52,584 $0 28 124,687 0 96,396 0 600 1,800 0 1,800 2,400 124,087 12,433 168 0 678 0 9 240 168 0 941 0 196 0 $52,584 $0 29 136,520 0 105,525 0 600 1,800 0 1,800 2,400 135,920 13,616 168 0 678 0 9 240 168 0 941 0 196 0 $52,584 $0 30 149,536 0 115,568 0 600 1,800 0 1,800 2,400 148,936 14,918 168 0 678 0 9 240 168 0 941 0 196 0 $52,584 $0 31 163,853 0 126,615 0 600 1,800 0 1,800 2,400 163,253 16,349 168 0 678 0 9 240 168 0 941 0 196 0 $52,584 $0 32 179,603 0 138,766 0 600 1,800 0 1,800 2,400 179,003 17,924 168 0 678 0 9 240 168 0 941 0 196 0 $52,584 $0 33 196,927 0 152,133 0 600 1,800 0 1,800 2,400 196,327 19,657 168 0 678 0 9 240 168 0 941 0 196 0 $52,584 $0 

19,235 53,654 72,888 Total acres 7,543 627 19,743 41 321 10,719 11,034 1,094 27,366 0 6,994 0 

Cost by me $2,360,809 $219,549 $6,712,486 $2,899 $22,500 $450,194 $1,368,274 $160,813 $9,304,458 $0 $489,604 $0 

Average Annual Acres of Treatment G=1st 6 years, H= remaining years Percentages above must total to 100 percent.

ESTIMATED ANNUAL ACRES OF TREATMENT ESTIMATED ACRES BY TREATMENT BY METHOD ESTIMATED ACRES BY TREATMENT BY METHOD ESTIMAT