United States 

Department of

Agriculture

Forest 

Service

Southwestern

Region

MB-R3-16-3

Final Environmental 

Impact Statement for 

the Invasive Plant 

Control Project

Carson and Santa Fe National Forests 

in Colfax, Los Alamos, Mora, Rio 

Arriba, San Miguel, Santa Fe, Sandoval,

and Taos Counties, New Mexico

i
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Printed on recycled paper – September 2005
Final Environmental Impact Statement 

for the

Invasive Plant Control Project

Responsible Agency: USDA Forest Service

Southwestern Region

Responsible Officials: Gilbert Zepeda, Santa Fe National Forest Supervisor

P.O. Box 1689, Santa Fe, NM 87504-1689

Martin D. Chavez, Jr., Carson National Forest Supervisor

208 Cruz Alta Road, Taos, NM 87571

For Information Contact: Sanford “Sandy” Hurlocker

P.O. Box 3307, Española, NM 87533

(505) 753-7331

Abstract: In northern New Mexico, invasive plants are impacting natural resources on more than 

7,300 acres of National Forest System lands within the Carson National Forest and Santa Fe 

National Forest (Forests). This final environmental impact statement (FEIS) discloses the analysis 

of a “no action” alternative (Alternative A) plus three management alternatives (Alternatives B, 

C, and D) that would eradicate, control or contain these populations to varying degrees using 

different treatment methods. In addition, each alternative includes an adaptive strategy for 

responding to infestations that have not yet been found, as well as permitting methods to be 

modified as needed based on monitoring results. Alternative B, the proposed action, would 

employ a combination of methods including: herbicide application, biological (insect) control 

agents, manual, mechanical, controlled grazing with sheep or goats, and prescribed burning. 

Alternative C would not use any herbicides, and Alternative D would use only herbicides. Those 

alternatives were developed based on issues raised about herbicide use. The Forest Plan for the 

Santa Fe National Forest would be amended if Alternative B or Alternative D were selected in 

order to allow use of herbicides in a few locations currently prohibited by the Forest Plan. The 

preferred alternative is the proposed action (Alternative B). It provides the level of protection 

necessary to maintain or enhance native plant communities and other natural resources on the 

Forests while minimizing the risk of adverse environmental or social impacts to the extent 

possible.

Contents

Summary of the Final EIS ........................................................................................................................... 1

Purpose and Need....................................................................................................................................... 1

Introduction ........................................................................................................................................... 1

Proposed Action..................................................................................................................................... 1

Purpose and Need for Action................................................................................................................. 2

Public Involvement and Issues .............................................................................................................. 3

Alternatives Considered in Detail .............................................................................................................. 3

Adaptive Strategy .................................................................................................................................. 4

Treatment Objectives and Decision Criteria.......................................................................................... 5

Mitigation and Monitoring..................................................................................................................... 6

Forest Plan Amendment......................................................................................................................... 7

Environmental Consequences and Comparison of Alternatives ............................................................... 8

Environmental Consequences Summary ............................................................................................... 8

Comparison of Alternatives................................................................................................................... 9

Chapter 1 • Purpose and Need ...................................................................................................................13

Introduction and Setting............................................................................................................................13

Purpose and Need for Action ....................................................................................................................13

Background: Existing Condition..............................................................................................................16

Management Direction - Desired Condition.........................................................................................27

Other Direction .....................................................................................................................................28

Proposed Action........................................................................................................................................28

Forest Plan Amendment........................................................................................................................30

Decisionmaking Framework .....................................................................................................................31

Public Involvement ...................................................................................................................................31

Issues.........................................................................................................................................................32

Issue 1: Human Health and Safety.......................................................................................................33

Issue 2: Wildlife and Fish ....................................................................................................................34

Issue 3: Native Vegetation...................................................................................................................34

Issue 4: Cost and Treatment Effectiveness..........................................................................................34

Chapter 2 • Alternatives, Including the Proposed Action.......................................................................35

Introduction...............................................................................................................................................35

Alternatives Eliminated from Detailed Study ...........................................................................................35

Aerial Herbicide Application................................................................................................................35

Weed Prevention...................................................................................................................................36

Organic Treatment Methods.................................................................................................................36

Alternatives Considered in Detail .............................................................................................................36

Alternative A: No Action......................................................................................................................36

Alternative B: Integrated Weed Control Strategy (Proposed Action)...................................................37

Alternative C: No Herbicides ..............................................................................................................41

Alternative D: Herbicides Only ............................................................................................................42

Adaptive Strategy—All Alternatives....................................................................................................42

Mitigation Measures and Monitoring Requirements.................................................................................47

Forest Plan Amendment............................................................................................................................53

Permits and Authorizations Required .......................................................................................................54

Comparison of Alternatives ......................................................................................................................59

Chapter 3 • Affected Environment and Environmental Consequences.................................................63

Cumulative Actions for Cumulative Effects Analysis ..............................................................................63

Vegetation Resource .................................................................................................................................67

Affected Environment - Vegetation......................................................................................................67

Environmental Consequences - Vegetation ..........................................................................................70

Affected Environment - Special Status Plants......................................................................................79

Final Environmental Impact Statement – Invasive Plant Control Project i
Contents

Environmental Consequences - Special Status Plants ..........................................................................79

Wildlife Resources....................................................................................................................................83

Affected Environment - Management Indicator Species......................................................................83

Affected Environment - Threatened, Endangered, and Sensitive Species............................................87

Affected Environment - Migratory Birds .............................................................................................93

Environmental Consequences - Wildlife (General)..............................................................................95

Environmental Consequences - Management Indicator Species ........................................................100

Environmental Consequences - Threatened, Endangered, Sensitive (TES) Species .........................101

Environmental Consequences - Migratory Birds................................................................................104

Fish and Aquatic Resources....................................................................................................................108

Affected Environment.........................................................................................................................108

Environmental Consequences.............................................................................................................110

Water Resources .....................................................................................................................................119

Affected Environment.........................................................................................................................119

Environmental Consequences.............................................................................................................123

Soil Resources.........................................................................................................................................129

Affected Environment.........................................................................................................................129

Environmental Consequences.............................................................................................................133

Air Quality ..............................................................................................................................................141

Affected Environment.........................................................................................................................141

Environmental Consequences.............................................................................................................143

Heritage Resources .................................................................................................................................146

Affected Environment.........................................................................................................................146

Environmental Consequences.............................................................................................................149

Recreation and Wilderness Resources ....................................................................................................153

Affected Environment.........................................................................................................................153

Environmental Consequences.............................................................................................................156

Visual Resources.....................................................................................................................................160

Affected Environment.........................................................................................................................160

Environmental Consequences.............................................................................................................160

Livestock Grazing ...................................................................................................................................163

Affected Environment.........................................................................................................................163

Environmental Consequences.............................................................................................................166

Social-Economics....................................................................................................................................169

Affected Environment.........................................................................................................................169

Environmental Consequences.............................................................................................................174

Human Health and Safety .......................................................................................................................180

Affected Environment.........................................................................................................................180

Environmental Consequences.............................................................................................................180

Other Required Disclosures ....................................................................................................................184

Short-term Uses and Long-term Productivity.....................................................................................184

Unavoidable Adverse Effects .............................................................................................................184

Irreversible and Irretrievable Commitments of Resources .................................................................184

Chapter 4 • List of Preparers and Document Distribution...................................................................185

List of Preparers......................................................................................................................................185

Document Distribution............................................................................................................................186

References Cited ........................................................................................................................................187

ii Final Environmental Impact Statement – Invasive Plant Control Project
Contents

Appendix 1 • Past, Present and Future Weed Control Activities.........................................................201

Appendix 2 • Weed Species Ecology and Impacts .................................................................................213

Black Henbane (Hyoscymas niger) (HYNI) ...........................................................................................213

Bull Thistle (Cirsium vulgare) (CIVU)...................................................................................................213

Canada Thistle (Cirsium arvense) (CIAR4)............................................................................................214

Dalmation Toadflax (Linaria dalmatica) (LIDA) and Yellow Toadflax (L. vulgaris) (LIVU2) ...........214

Diffuse Knapweed (Centaurea diffusa) (CEDI3) ...................................................................................215

Field Bindweed (Convolvulus arvensis) (COAR4).................................................................................215

Hoary Cress (Cardaria draba) (CADR) .................................................................................................216

Leafy Spurge (Euphorbia esula) (EUES) ...............................................................................................216

Musk Thistle (Carduus nutans) (CANU4)..............................................................................................216

Perennial Pepperweed (Lepidium latifolium) (LELA2) ..........................................................................217

Poison Hemlock (Conium maculatum) (COMA2)..................................................................................217

Russian Knapweed (Acroptilon repens) (ACRE3) .................................................................................218

Russian Olive (Elaeagnus angustifolia) (ELAN)....................................................................................218

Saltcedar (Tamarix spp) (TAMAR2)......................................................................................................219

Scotch Thistle (Onopordum acanthium) (ONAC) ..................................................................................219

Siberian Elm (Ulmus pumila) (ULPU)....................................................................................................220

Spotted Knapweed (Centaurea biebersteinii) (CEBI2) ..........................................................................220

Yellow Starthistle (Centaurea solstitalis) (CESO3) ...............................................................................221

Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments............................................223

Program Description ...............................................................................................................................224

Application Methods...............................................................................................................................224

Overall Conclusions............................................................................................................................228

Human Health Risk Assessment.........................................................................................................231

Factors Affecting Hazard of Herbicides.............................................................................................231

Wildlife Risk Assessment...................................................................................................................244

Aquatic Risk Assessments..................................................................................................................249

Specific Herbicide Characteristics and Environmental Effects..............................................................251

2,4-D...................................................................................................................................................251

Chlorsulfuron......................................................................................................................................253

Clopyralid ...........................................................................................................................................255

Dicamba..............................................................................................................................................257

Glyphosate ..........................................................................................................................................258

Hexazinone .........................................................................................................................................262

Imazapic..............................................................................................................................................265

Imazapyr.............................................................................................................................................266

Metsulfuron methyl ............................................................................................................................268

Sulfometuron methyl ..........................................................................................................................270

Triclopyr.............................................................................................................................................276

Inert/Other Ingredients........................................................................................................................280

Appendix 4 • Effects of Nonherbicide Weed Control Methods ............................................................287

Biological Control...................................................................................................................................287

Manual ....................................................................................................................................................288

Mechanical..............................................................................................................................................288

Controlled Grazing..................................................................................................................................288

Appendix 5 • Herbicide Model for Watershed Analysis .......................................................................291

Representative Watershed Selection .......................................................................................................291

Modeling Assumptions ...........................................................................................................................292

Modeling Calculations............................................................................................................................292

Final Environmental Impact Statement – Invasive Plant Control Project iii
Contents

Appendix 6 • Chemical Spill Prevention and Cleanup Plan .................................................................295

Herbicide Cleanup...................................................................................................................................295

Minor Spills........................................................................................................................................295

Major Spills ........................................................................................................................................295

Response Action Guide ......................................................................................................................295

Precautions..........................................................................................................................................296

Reporting ............................................................................................................................................296

Appendix 7 • Weed Populations and Treatments..................................................................................297

Appendix 8 • Implementation/Monitoring ..............................................................................................305

Appendix 9 • Response to Comments on the DEIS................................................................................307

Access.................................................................................................................................................308

Adaptive Strategy....................................................................................................................................308

Alternatives.............................................................................................................................................309

Alternative C Preference.....................................................................................................................310

Alternative B.......................................................................................................................................313

Analysis...................................................................................................................................................313

Cultural Resources..............................................................................................................................314

Drought...............................................................................................................................................314

Economics ..........................................................................................................................................315

Growth of the Invasive Weed Problem...............................................................................................315

IDT Qualifications..............................................................................................................................316

Inventory.............................................................................................................................................316

Plants ..................................................................................................................................................316

Riparian ..............................................................................................................................................317

Social Impacts.....................................................................................................................................317

Soils....................................................................................................................................................317

Soil Erosion ........................................................................................................................................318

Water ..................................................................................................................................................319

Wildlife...............................................................................................................................................320

Forest Plan Amendment..........................................................................................................................320

Herbicides...............................................................................................................................................322

2,4-D...................................................................................................................................................323

Clopyralid ...........................................................................................................................................323

Dicamba..............................................................................................................................................324

Glyphosate ..........................................................................................................................................324

Hexazinone .........................................................................................................................................324

Imazapic..............................................................................................................................................325

Imazapyr.............................................................................................................................................325

Metsulfuron methyl ............................................................................................................................326

Picloram..............................................................................................................................................326

Sulfometuron methyl ..........................................................................................................................326

Triclopyr.............................................................................................................................................327

Contaminants......................................................................................................................................327

Dose Response....................................................................................................................................327

Drift ....................................................................................................................................................328

Health Effects .....................................................................................................................................328

Inert Ingredients..................................................................................................................................329

Livestock ............................................................................................................................................330

Persistence ..........................................................................................................................................330

Registration System Flaws..................................................................................................................331

Safety..................................................................................................................................................331

Synergistic Effects..............................................................................................................................333

iv Final Environmental Impact Statement – Invasive Plant Control Project
Contents

Unreliable Information .......................................................................................................................334

Water Users ........................................................................................................................................335

Water/aquatic Effects..........................................................................................................................336

Wildlife...............................................................................................................................................336

Water/Aquatic Effects.........................................................................................................................337

Implementation/Mitigation/Monitoring ..................................................................................................337

Application Methods ..........................................................................................................................339

Budget.................................................................................................................................................339

Notice..................................................................................................................................................340

Plant Inventory/ID Process.................................................................................................................341

Safety..................................................................................................................................................341

Timing ................................................................................................................................................341

Watershed Thresholds.........................................................................................................................342

Wildlife...............................................................................................................................................342

Prevention ...............................................................................................................................................343

Procedure ................................................................................................................................................343

Purpose....................................................................................................................................................344

Costs ...................................................................................................................................................345

Cultural Resources..............................................................................................................................345

Emphasize Objectives.........................................................................................................................345

Saltcedar Objectives ...........................................................................................................................346

Technical Advice ....................................................................................................................................347

Corrections and Clarifications ............................................................................................................347

Other Corrections................................................................................................................................360

Non-substantive Comments....................................................................................................................362

General Comments .............................................................................................................................362

Alt C Preference .................................................................................................................................362

Volunteers...........................................................................................................................................362

Commenters............................................................................................................................................362

Comments Received on the Draft EIS from Federal, State, and Local Agencies and Elected Officials365

Index ...........................................................................................................................................................367

List of Figures

Figure 1. Project Area and Vicinity...............................................................................................................12

Figure 2. Weed Distribution ..........................................................................................................................20

Figure 3. Alternative B..................................................................................................................................56

Figure 4. Alternative C..................................................................................................................................57

Figure 5. Alternative D..................................................................................................................................58

Figure 6. Vegetation Types in the Project Area.............................................................................................69

Figure 7. Major Streams..............................................................................................................................116

Figure 8. Weeds in Valley Bottoms/Riparian Areas....................................................................................117

Figure 9. Watersheds, including Representative Watersheds......................................................................118

Figure 10. Soil Erosion Hazard ...................................................................................................................131

Figure 11. Soil Revegetation Potential ........................................................................................................132

Figure 12. Weeds Near Recreation Sites.....................................................................................................154

Figure 13. Weeds in or Near Wilderness.....................................................................................................155

Figure 14. Ethnicity.....................................................................................................................................170

Figure 15. Per Capita Income (U.S. Census Bureau 2001) and Population Percentage below Poverty Level 

(U.S. Census Bureau 1999).................................................................................................................171

Final Environmental Impact Statement – Invasive Plant Control Project v
Contents

List of Tables

Table 1. Weed Distribution by Species .......................................................................................................... 3

Table 2. Proposed Santa Fe National Forest Plan Amendment ...................................................................... 8

Table 3. Comparison of Alternatives by Issues and Objectives (Purpose and Need)..................................... 9

Table 4. General Groups of Weeds ...............................................................................................................17

Table 5. Weed Species: Locations and Impacts ............................................................................................21

Table 6. Alternative B Treatment Summary..................................................................................................41

Table 7. Alternative C Treatment Summary..................................................................................................41

Table 8. Alternative D Treatment Summary .................................................................................................42

Table 9. Additional Treatment Criteria and Limitations ...............................................................................46

Table 10. Mitigation Measures and Monitoring Requirements for All Alternatives.....................................47

Table 11. Proposed Santa Fe National Forest Plan Amendment ...................................................................54

Table 12. Comparison of Alternatives by Issues and Objectives (Purpose and Need)..................................59

Table 13. Summary of Cumulative Activities by Key Resource Issues........................................................64

Table 14. Weed Infestations by Vegetation Type..........................................................................................68

Table 15. Treatment Acres in Grassland .......................................................................................................73

Table 16. Treatment Acres in Sagebrush/Shrub ............................................................................................73

Table 17. Treatment Acres in Ponderosa Pine...............................................................................................73

Table 18. Treatment Acres in Oak Woodlands..............................................................................................74

Table 19. Treatment Acres in Pinyon-Juniper...............................................................................................74

Table 20. Treatment Acres in Riparian/Valley Bottoms ...............................................................................74

Table 21. Treatment Acres in Mixed Conifer................................................................................................75

Table 22. Treatment Acres in Spruce-Fir ......................................................................................................75

Table 23. Treatment Acres in Other (e.g. urban)...........................................................................................75

Table 24. Special Status Plant Species Habitat by Vegetation Cover Type ..................................................79

Table 25. Wildlife Management Indicator Species (MIS), Habitat and Weed Infestation ............................83

Table 26. Threatened, Endangered and Sensitive Species.............................................................................88

Table 27. Migratory Bird Habitat and Probability of Occurrence in Treatment Areas .................................94

Table 28. Effects to Management Indicator Species ...................................................................................100

Table 29. Effects to TES Species and Habitats ...........................................................................................102

Table 30. Effects to Migratory Birds and Habitats......................................................................................104

Table 31. Watersheds on or Intersecting the Forests...................................................................................119

Table 32. Characteristics of Representative Watersheds.............................................................................121

Table 33. Acres Treated by Soil Erosion Hazard Rating.............................................................................133

Table 34. Acres Treated by Severe Soil Erosion Hazard Rating.................................................................133

Table 35. Acres Treated by Moderate Soil Erosion Hazard Rating.............................................................134

Table 36. Acres Treated by Slight Soil Erosion Hazard Rating ..................................................................134

Table 37. Acres Treated by Revegetation Potential ....................................................................................134

Table 38. Acres Treated by Low Revegetation Potential ............................................................................135

Table 39. Acres Treated by Moderate Revegetation Potential ....................................................................135

Table 40. Acres Treated by High Revegetation Potential............................................................................135

Table 41. Ambient Air Quality Standards...................................................................................................141

Table 42. Air Quality 1999-2003: PM10 PM25 Pollutants............................................................................142

Table 43. Particulate Emissions in Northern New Mexico, 1999................................................................143

Table 44. Summary of Total Emissions by Alternative...............................................................................144

Table 45. Affected Heritage Resource Sites by Relative Site Size..............................................................147

Table 46. Grazing Allotments with Known Weed Infestations on the Carson National Forest ..................163

Table 47. Grazing Allotments with Known Weed Infestations on the Santa Fe National Forest................165

Table 48. Occupied Wild Horse Territories with Known Weed Infestations on the Forests.......................166

Table 49. Population Growth of Affected Counties by Census Year..........................................................170

Table 50. County Land Base and Population Density .................................................................................171

Table 51. Urban and Rural Populations.......................................................................................................172

Table 52. Estimated Treatment Costs..........................................................................................................176

Table 53. Present Net Value and Economic Efficiency...............................................................................178

vi Final Environmental Impact Statement – Invasive Plant Control Project
Contents

Table 54. List of Preparers ..........................................................................................................................185

Table 55. Acres Inventoried and Treated for Weeds on Nearby BLM Lands by Fiscal Year.....................207

Table 56. Methods of Addressing Weeds in 2003.......................................................................................208

Table 57. Herbicide Risk Assessment Information .....................................................................................223

Table 58. Herbicide Use Program Description............................................................................................224

Table 59. Herbicides Formulations, Application Rates, Target Plants........................................................225

Table 60. Herbicide Risk Assessment Standard Terminology ....................................................................227

Table 61. Herbicide Characteristics.............................................................................................................232

Table 62. Exposure Risk of Herbicides.......................................................................................................239

Table 63. Relative Risk of Each Herbicide .................................................................................................246

Table 63. (continued) Relative Risk of Each Herbicide ..............................................................................247

Table 64. Effects of Each Herbicide............................................................................................................248

Table 65. Level of Concern for Chemical Use Using the Risk Quotient Method .......................................250

Table 66. Herbicide formulations, impurities, other ingredients.................................................................281

Table 66. Herbicide Mixing Model Results ................................................................................................293

Table 67. Weed Populations and Proposed Treatments...............................................................................298

Table 68. List of People/Organizations who commented on the DEIS .......................................................362

Final Environmental Impact Statement – Invasive Plant Control Project vii

Summary of the Final EIS

Purpose and Need

This section describes the proposed action (project), purpose and need for the proposed action, 

public involvement, and issues identified. 

Introduction

In northern New Mexico’s Carson National Forest and Santa Fe National Forest, more than 7,300 

acres of invasive nonnative plant populations (i.e. weeds) are known to impact National Forest 

System lands. Although this amount represents less than 0.5 percent of the 3 million acres 

managed by these two forests, weed treatments are most effective when the areas affected are 

small and before weeds are well established. It is important to control weed infestations at an 

early stage, before costly large-scale treatments such as aerial spraying become necessary.

This document summarizes the “Final Environmental Impact Statement for the Invasive Weed 

Control Project.” It provides an overview of the proposed action; the purpose and need for the 

project; the public involvement effort to date; issue and alternative development; and a summary 

of the expected effects of alternatives on the human environment.

Proposed Action

The project focuses on controlling invasive plants designated by New Mexico as weeds. These 

weeds occur on the Forests in various locations. Treatments would begin in 2005 or 2006. During 

approximately the next 10 years, each forest anticipates treating 300 to 800 acres per year, based 

on anticipated funding. As many as 3,000 acres could be treated in a given year (1,500 acres on 

each forest) if funding permits. The implementation period could extend beyond 10 years if 

adaptive management monitoring shows the results lie within the expected sideboards.

Activities include eradication or control of weeds that pose a threat along riparian areas, roads, 

trails, recreation sites, administrative sites, gas/oil pads (and pipelines), and range improvements. 

Areas of recent disturbance—such as the Ponil Fire complex and other burned areas on the two 

forests—will also receive attention. The proposal employs the following methods: 

• Hand pulling, grubbing with hand tools or hand operated power tools, mowing and 

disking, or plowing with tractor-mounted implements; 

• Biological control using insects or plant pathogens introduced into the weed habitat; 

• Controlled grazing using goats and sheep to intensively and repeatedly graze weeds; 

• Herbicide application to weed populations using hand or vehicle-mounted sprayer 

applications; and 

• Prescribed burning using limited pile or broadcast burning to eliminate seed heads and 

resident populations of weeds. 

Cultural plant methods would also be used as a followup treatment. These methods use native or 

appropriate nonnative plant species to supplant target weed species.

The scope of the proposal includes treatments to existing weed infestations, as well as an adaptive 

strategy for responding to infestations that have not yet been mapped. The adaptive strategy 

would evaluate new weed threats and, if the effects fall within parameters described in this DEIS, 

permit immediate treatment. Failure to deal immediately with these new—usually small—

infestations is likely to lead to larger scale treatments with greater impacts later.

Final Environmental Impact Statement – Invasive Plant Control Project 1 
Summary of the Final EIS

Purpose and Need for Action

The primary purpose of and need for this project is to protect the abundance and biological 

diversity of desired native plant communities on the Forests, which in turn will help maintain and 

enhance wildlife and fish habitats, soil productivity and watershed conditions. This is especially 

important in the riparian areas and moist valley bottoms where critical habitat exists for many 

plant and animal species. Without effective control, weeds will increasingly impact natural 

resources on the Forests in the following ways: 

• Native plant communities will become more impacted as weeds gradually take over 

dominance of these communities. Weeds often form monocultures or greatly simplified 

ecosystems. Ecosystem processes become degraded, with evidence of slower nutrient 

cycling and lower hydrological stability. They prove less sustainable when confronted 

with natural disturbances such as fire. Weeds also threaten the continued existence of 

certain endangered, sensitive or rare plant species that occur on the Forests. 

• Erosion is increased by many weed species. Knapweeds and other weeds have a single, 

deep taproot and drive out native grasses that have better soil-holding root systems. 

Native riparian plants including rushes, sedges, willows and cottonwoods maintain 

streambank stability better than the weed species currently spreading through the Forests’ 

riparian zones. 

• Wildlife habitat quality decreases when weeds take over native plant communities. 

Palatable forage for game and nongame species of wildlife decreases as weeds like 

thistle, leafy spurge and toadflax take over. Weeds such as black henbane, poison 

hemlock and yellow starthistle can poison animals. Negative impacts to wildlife magnify 

in riparian areas because of the important role riparian vegetation plays for a large 

number of southwestern wildlife species. A large percentage of the known weed 

infestations occur in or near riparian areas.

• Recreation opportunities are lessened when dense weed infestations limit access to 

streams and riparian areas. Weed species with sharp thorns and stiff stems are reducing 

the quality of some recreation sites for picnicking and camping purposes. Some weeds 

cause allergies or skin irritations. Scenic values and wilderness characteristics also 

typically decline as weeds reduce the abundance and diversity of native plant 

communities. 

• Culturally important plants such as osha, wild spinach, willow, and purslane would 

decline where weed invasions occur. Because many of the invasive weeds occur near 

roads and trails, the ability to readily collect those plants would become more limited. 

• Wildland fires are known to burn more intensely and severely in areas where weed 

species like saltcedar, Siberian elm and Russian olive have taken over native riparian 

ecosystems. 

• Weeds primarily occur in the following locations (based on percent of inventoried weed 

infestations totaling approximately 7,350 acres): 

▪ Riparian areas and valley bottoms: 55 percent

▪ Scattered patches and along low-level roads and trails: 19 percent

▪ Major road corridors and recreation sites: 14 percent

▪ In or along access into wilderness: 12 percent 

2 Final Environmental Impact Statement – Invasive Plant Control Project 
Summary of the Final EIS

In terms of current weed species distribution, the most dominant weed species are the nonnative 

thistles, followed by the valley bottom species of saltcedar, Siberian elm, and Russian olive. Table 

1 below shows the weed species distribution by percent of inventoried weed infestations.

Table 1. Weed Distribution by Species

Weed Species Distribution

Thistles (biennials and perennials) 67%

Saltcedar and Siberian elm 28%

Knapweed 3%

Toadflax 2%

Hoary cress, field bindweed, leafy spurge and poison hemlock <1%

Perennial pepperweed, black henbane, and yellow starthistle <0.5%

Public Involvement and Issues

In 1996-1997, the Forests met with other Federal, State and county land management agencies to 

discuss the threat of weeds. From 1998-2000, the weed control proposal was developed and 

various methods were used to inform and involve the public about the proposed project. These 

included a newspaper supplement, public meetings held in Taos and Española, and a scoping 

letter sent to approximately 450 individuals, agencies, tribal governments and organizations to 

inform them about the proposal. At that time, the Forests were conducting independent 

environmental assessments of similar proposals. As a result of the March 2000 scoping efforts, a 

decision was made to combine the environmental analysis efforts of the two forests and write a 

single EIS. In December 2000, the Forests sent another scoping letter and published a Federal 

Register notice of intent to prepare an EIS. At the request of local citizens, a public field trip was 

conducted to discuss and visit weed impact sites on the Tres Piedras Ranger District of the Carson 

National Forest.

Issues were identified from comments received during scoping. The primary issues revolved 

around concerns about how herbicides might affect human health, wildlife, fish and desired plant 

communities. On the other hand, there was an important concern that where non-herbicide 

methods were used, there would be less effectiveness and the potential for weeds to spread at a 

faster rate than they can be controlled. As invasive plants become more dominant on the 

landscape, they have greater resource impacts and become more costly and difficult to treat in the 

long run. 

The draft environmental impact statement underwent public review in July/August 2004. 

Approximately 100 letters were submitted with most of them expressing a concern with the use of 

herbicides as a means of controlling invasive weeds. A response to these comments is included in 

the final environmental impact statement as an appendix.

Alternatives Considered in Detail

This section summarizes the four alternatives considered in detail in the DEIS, the adaptive 

management strategy, treatment objectives and decision criteria, mitigation and monitoring 

requirements, and associated Forest Plan amendment. 

Alternative A - No Action. This is the baseline for comparing the other alternatives and 

is the alternative where proposed weed control actions would not occur on the Forests. 

Final Environmental Impact Statement – Invasive Plant Control Project 3 
Summary of the Final EIS

Weed control would be limited to those actions previously approved on the Forests and 

those conducted by other jurisdictions and landowners in and around the Forests.

Alternative B - Integrated Strategy. This is the Agency’s proposed action as previously 

described, developed to fully meet the purpose and need for action while minimizing the 

risk of adverse impacts through mitigation measures and monitoring requirements.

Alternative C - No Herbicides. This alternative eliminates herbicide use and was 

developed in response to public concerns raised about potential effects of herbicides on 

human health, fish/wildlife, and nontarget native vegetation. 

Alternative D - Herbicides Only. This alternative exclusively relies on herbicides and 

was developed in response to the cost effectiveness issue associated with proposed nonherbicide treatments.

All action alternatives would employ the adaptive strategy to provide for timely response to 

newly discovered weed infestations, as well as changes to treatment methods as technology 

advances or as monitoring results indicate a need for change.

Adaptive Strategy

The action alternatives employ an adaptive strategy—especially Alternative B, but Alternatives C 

and D to a lesser extent. Using this adaptive strategy, weed treatments would be monitored, 

evaluated and modified as necessary to improve effectiveness of future treatments and/or reduce 

the potential for adverse effects to people and natural resources. This strategy also allows for 

applying the same weed control treatments to new weed infestation sites as long as the actions 

and effects (including decisionmaking criteria and limitations on treatments) are within the scope 

of the EIS and Record of Decision. 

While Alternatives C and D would also employ the adaptive strategy, changes in methods would 

be limited to the nonherbicide or herbicide-only methods (respectively). For those two 

alternatives, methods could be slightly modified as needed to improve efficiency or reduce 

negative impacts, such as by altering the timing, equipment, herbicide type or application rate. 

The adaptive strategy would also be used to treat newly discovered infestations. 

The adaptive strategy would cover weeds found in additional locations as well as new species 

found on the Forests. The Forests propose an adaptive strategy with the following actions: 

• Annually inventory portions of the Forests that are likely to have new infestations (e.g. 

areas burned by wildfires or recently disturbed) and map new weed infestations. Budgets 

will govern the extent of these inventories.

• Identify the weed treatment objective, priority and methods to use for newly mapped 

infestations, based on the specific criteria described in the FEIS.

• Monitor the effectiveness and effects of weed treatment activities and associated 

mitigation measures.

• Evaluate and disclose monitoring results, and use those results to determine appropriate 

modifications in treatment prescriptions, mitigation measures or implementation 

practices. 

4 Final Environmental Impact Statement – Invasive Plant Control Project
Summary of the Final EIS

• Implement modifications or other feasible and appropriate treatment methods based on 

monitoring results, as long as the action and its effects are considered by an 

interdisciplinary team and determined by the responsible official to be within the scope of 

actions and effects evaluated in the EIS (in accordance with Forest Service Handbook 

FSH 1909.15, Sec.18). 

Treatment Objectives and Decision Criteria 

Specific treatment objectives for a given weed species fall into one of the following categories:

• Eradication (elimination)

• Control (reducing the population over time) 

• Containment (preventing the population from spreading). 

Eradicating or controlling every weed infestation in 1 or 2 years is beyond the budget and 

personnel resources of the two forests. Therefore, a system for setting priorities is proposed so 

that treatment concentrates on invasive species that have the greatest impact on the resource base, 

and those invasive that become more difficult to control if action is delayed. Weeds become much 

more difficult to control once they have spread. Thus, the highest priority is to eradicate new 

species occurrences on the Forests, and then to keep existing populations from spreading or 

increasing in size. 

In addition, new weed infestations found in the following locations would be considered for a 

possible elevated priority ranking:

• Areas that are now relatively weed free and have little or no road access, such as areas 

designated as wilderness, roadless recreation or semiprimitive, nonmotorized, including 

the road corridors and trails that lead to those areas;

• Areas that are now relatively weed free that provide unique and desirable wildlife habitat, 

such as recovery habitat for threatened or endangered species, deer and elk winter range; 

and riparian habitat;

• Areas on the Forests with weed populations adjacent to other land ownerships where land 

managers have active weed control programs;

• Areas of high human use, including but not limited to administrative sites, developed 

recreation sites such as campgrounds, scenic viewpoints, interpretive sites, and trailheads.

Schedules for implementing weed treatments would be based first on the priorities just described, 

and spread out over time based on levels of funding and staffing on the Forests.

Selection of treatment method is based to a large extent on the priority ranking of the weed 

species and the objective for a particular site, which is dictated by factors such as proximity to 

water or roads (which increases chance of weed spread), and the size of the weed infestation 

(small sizes are easier to eradicate).

In addition to using treatment objectives, priority rankings, and infestation size, other specific site 

conditions would prescribe treatment method limitations. Where present, these conditions will 

dictate use of methods that have a low risk to the resource factor of concern:

Final Environmental Impact Statement – Invasive Plant Control Project 5
Summary of the Final EIS

• Areas of high human use such as a recreation site, administrative site, or area where 

people often collect plants.

• Areas with a shallow water table (less than 6 feet deep) and soil with a high permeability 

rate, where there may be a risk of an herbicide leaching through the soil to the ground 

water.

• Riparian areas or next to live water bodies containing aquatic species (fish and insects).

• Presence or proximity of threatened, endangered or sensitive plant species.

• Presence or proximity of threatened, endangered or sensitive wildlife species.

• Wilderness and designated nonmotorized areas.

Mitigation and Monitoring

The FEIS lists mitigation measures and monitoring requirements for all action alternatives. The 

mitigations were developed specifically for this project in order to avoid or minimize the risk of 

adverse project-related impacts to people or natural resources on the Forests, including potential 

impacts to human health and safety, native plants, special status plants or wildlife, soil, water, 

riparian and aquatic resources, and heritage resources. The bullets that follow summarize 

mitigation measures that are described in more detail in the FEIS. 

• Human Health/Safety and General Mitigations: These govern herbicide application and 

use, public notification, traffic control, and other health/safety protection measures.

• Native Vegetation and Treatment Effectiveness: These direct the treatments so that they 

have a minimal impact on native vegetation. They include cleaning equipment, 

revegetation (or mulching as appropriate), and use of proper seed to revegetate. 

• Threatened, Endangered and Sensitive Plants: These require survey and/or avoidance of 

occupied habitat. For Holy Ghost ipomopsis (the only federally listed species in the 

project area), buffers apply to treatments such as grazing, mowing, prescribed burning. 

The FEIS increased protection beyond that described in the DEIS by eliminating the use 

of herbicides within the boundary of the known population (FEIS page 49).

• Wildlife, Including Threatened, Endangered and Sensitive Species: Depending on the 

level of protection required by law, regulation and policy, these measures require surveys 

and/or avoidance, and use of seasonal restrictions to reduce impacts during breeding 

periods. For example, controlled grazing with sheep or goats is prohibited in Rocky 

Mountain bighorn sheep habitat.

• Air, Soil, Water, Riparian and Aquatic Resources: These measures restrict types of 

treatments in certain places, such as slope restrictions for mechanical treatments and 

herbicide use restrictions near water or high water table locations. Although most 

herbicides would be permitted near water if registered for such use by the EPA, no direct 

application of herbicide to water (e.g. for aquatic plants) is permitted as part of this 

project in order to avoid impacts to native fish. Procedural restrictions also apply. These 

include complying with smoke management for prescribed burns, and evaluating 

watersheds for total herbicide use before proceeding. Potential for accidental spills of 

herbicides, gasoline or other chemicals associated with treatments would be minimized 

by restrictions on where these chemicals can be handled. Spill prevention and cleanup 

plans and other established procedures also reduce the impacts to soil, water, and aquatic 

resources.

6 Final Environmental Impact Statement – Invasive Plant Control Project
Summary of the Final EIS

• Heritage Resources: A programmatic agreement among the Forests, State Historic 

Preservation Office and Advisory Council was developed for this project to ensure that 

heritage resources would be protected in accordance with applicable law, regulation and 

policy. The programmatic agreement spells out the requirements for conducting heritage 

resource inventories and evaluations for this project prior to implementation. It requires 

development of appropriate mitigation measures to avoid adverse impacts to heritage 

resources. Measures include limiting use of vehicles and other machinery that could 

disturb soil in sensitive areas, limiting herbicide use near certain sites, limiting controlled 

grazing near certain sites, and avoiding controlled fire within certain sites. Tribal 

consultation and pretreatment notification is included as an essential element. It describes 

requirements for consultation with the State and application of additional mitigation 

measures if adverse impacts cannot be avoided while meeting project objectives. 

• Monitoring and Adaptive Management: Weed inventories and mapping will be conducted 

annually. Treatment of newly found populations will be identified and prioritized. 

Treatments will be monitored for effectiveness and effects to other resources. If the 

treatments initially prescribed in the FEIS are not effectively meeting the given treatment 

objective, another method may be used as long as the action and effects are within the 

scope of effects considered in the FEIS. The evaluation and decision by the responsible 

official regarding consistency with the FEIS will be documented in the project record.

Forest Plan Amendment

Alternatives B and D would require an amendment to the Santa Fe National Forest Plan. These 

alternatives propose use of herbicides in places and under conditions that were not foreseen when 

the existing Forest Plan standards and guidelines were developed. The Forest Plan (page 76) 

currently prohibits herbicide use within municipal watersheds, in areas of human habitation, on 

soils with low regeneration potential or less than moderate cation exchange capacity (USDA FS 

1987). The proposed amendment would modify these standards in order to allow herbicides to be 

used where necessary in those situations, with specific limitations, including the close 

collaboration with the municipality involved when a water supply were considered for treatment. 

The Santa Fe National Forest Plan currently prohibits herbicide use if an environmental analysis 

shows that it is not “environmentally, economically or socially acceptable,” which is an 

ambiguous standard and subject to variable interpretations. The amendment would modify that 

standard so it is more consistent with environmental analysis requirements under NEPA. 

To meet the purpose and need for this project and protect ecosystem diversity and sustainability 

in the long term, it may be necessary to occasionally apply herbicides within those areas if they 

are infested with weed populations that cannot be effectively treated with other methods. The 

proposed amendment would continue to maintain adequate protection for municipal watersheds, 

soil productivity, and human health and safety. For instance, soil erosion rates would still be 

required to remain within tolerance levels based on the terrestrial ecosystem survey data, in order 

to maintain long-term soil productivity. The Forest Plan standard regarding cation exchange 

capacity is outdated and would be deleted from the Forest Plan, as that measurement is no longer 

used by the Forest Service. Table 2 uses italics to show the specific language changes in Forest 

Plan direction.

Final Environmental Impact Statement – Invasive Plant Control Project 7
Summary of the Final EIS

Table 2. Proposed Santa Fe National Forest Plan Amendment

Existing Forest Plan Direction Proposed Forest Plan Direction

Chemical treatments may be applied:

- When determined through an environmental 

analysis to be environmentally, 

economically, and socially acceptable.

- On areas outside municipal watersheds and 

areas of human habitation.

- On soils with moderate or high revegetation 

potential.

Chemical treatments may be applied:

- When determined through an environmental 

analysis to have no long-term adverse 

environmental, economic, or social 

impacts.

- Within municipal watersheds only when 

the municipality concurs with the proposed 

treatment prescription and mitigation 

measures to be implemented.

- On any soils provided that effective ground 

cover is quickly restored and soil erosion 

on that site is not reduced to below the 

tolerance level identified in the terrestrial 

ecosystem survey for the affected soil unit.

Environmental Consequences 

and Comparison of Alternatives

This section provides a comparative summary of the alternatives in terms of the most significant 

issues or effects anticipated, based on the analysis in the DEIS. The DEIS describes the affected 

environment and environmental consequences, including analysis methods, in detail.

Environmental Consequences Summary

The most noticeable consequences from weed treatment Alternatives B, C, and D would be the 

long-term beneficial improvements to native ground vegetation such as grasses, forbs and shrubs. 

Riparian vegetation such as rushes, sedges, willows and cottonwoods would particularly benefit 

from this project. Protecting and improving native plant communities would have positive effects 

on soil and water conditions, as well as wildlife and aquatic habitats (particularly due to 

enhancing riparian vegetation). 

Negative effects to native vegetation, soil, water and aquatic organisms would be minor and of 

short duration. The minor, short-term increases in sediment (more with Alternative C) and 

herbicide delivery to streams (Alternatives B and D) would have no significant consequences. 

There would be a low risk of adverse impacts to fisheries, including Rio Grande cutthroat trout (a 

sensitive fish species) or other aquatic organisms based on application of mitigation measures, 

risk assessment and EPA guidelines. Alternative C would cause more ground disturbance and 

associated impacts to soils, especially on soils with severe erosion hazard rating. However, all 

alternatives would remain with soil erosion tolerance levels needed to protect long-term soil 

productivity. Soils with low revegetation potential would receive herbicide treatments in 

Alternatives B and D, while reestablishing native vegetation would take longer under Alternative 

C. Mitigation requirements for all alternatives would ensure that vegetative ground cover is 

adequately reestablished. With the required mitigation measures, all soil and water quality 

standards would be met. 

8 Final Environmental Impact Statement – Invasive Plant Control Project
Summary of the Final EIS

Differences between alternatives in their effects to air quality, heritage resources, livestock 

grazing, recreation, wilderness and visual resources are expected to be negligible, such that they 

would not be given weight in the decisionmaking process. There would be minor increases in 

noise and traffic, although generally within background levels. 

By controlling the spread of weeds and protecting native plant communities, habitats and 

watershed conditions on the Forests, Alternatives B and D would maintain or enhance social or 

economic conditions, particularly for local rural communities in northern New Mexico who 

typically rely on the Forests’ natural resources for their livelihood, traditional culture and quality 

of life. 

Comparison of Alternatives

The alternatives are compared in terms of the significant issues, as well as how well they meet the 

purpose and need (objectives) for the project. Table 3 provides the comparison of alternatives, 

based on the detailed environmental analysis documented in the FEIS. The comparison table is 

intended to provide a clear basis for choice between alternatives. 

Table 3. Comparison of Alternatives by Issues and Objectives (Purpose and Need)

Significant 

Issues and 

Objectives

Alternative A Alternative B Alternative C Alternative D

Issue 1: 

Herbicides 

and Human 

Health

No risk of health 

impacts from 

herbicide exposure 

(0 acres treated with 

herbicides).

Low risk of health 

impacts from using 

herbicides, to 

workers or general 

public, based on risk 

assessments and 

other mitigation 

measures. 

Higher risk to people 

with multiple 

chemical 

sensitivities, 

although public 

notification 

requirement allows 

for avoidance of 

treated areas by 

people with this 

condition.

Approx. 70 percent 

of treatments include 

herbicides (5,150 

acres).

No risk of health 

impacts from 

herbicide 

exposure (0 

acres treated 

with herbicides).

Slightly 

increased risk of 

exposure to 

smoke from 

prescribed 

burning...

Same as Alt. 

B but slightly 

higher risk of 

exposure for 

people with 

chemical 

sensitivities.

One hundred 

percent of 

treatments 

include 

herbicides 

(5,435 

acres).

Final Environmental Impact Statement – Invasive Plant Control Project 9
Summary of the Final EIS

Significant 

Issues and 

Objectives

Alternative A Alternative B Alternative C Alternative D

Issue 2: 

Herbicides 

and Wildlife

No risk of herbicide 

impacts to wildlife. 

Weeds would 

degrade native plant 

habitats, especially 

riparian areas 

important to 

numerous species.

Low risk of herbicide 

impacts to wildlife 

based on risk 

assessment, and 

mitigation measures.

Native wildlife 

habitat quality 

(especially riparian 

habitat) would 

improve as weeds are 

eradicated and 

controlled.

No risk of 

herbicide 

impacts to 

wildlife.

Less 

improvement in 

wildlife habitat.

Same as Alt. 

B

Issue 3: 

Herbicides 

and Native 

Plant 

Communities

No short-term 

impacts from 

herbicides.

In the long term, 

weed-caused decline 

in abundance and 

diversity of native 

plant communities, 

especially native 

riparian plants.

Short-term reduction 

in some nontarget 

plant species.

Long-term 

improvement in 

abundance and 

diversity of native 

plant communities, 

especially riparian 

plants.

Similar shortterm reduction in 

nontarget plants.

Low to moderate 

long-term 

improvement in 

native plant 

communities. 

Weed spread 

rate may equal 

or exceed 

control rate 

without 

herbicide use.

Same as Alt. 

B

Issue 3: 

ContinuedRare or 

Sensitive 

Native Plant 

Species

No risk of 

treatment-related 

impacts. 

In the long term, 

weeds may cause a 

decline in federally 

listed or sensitive 

plant species.

No impact to 

threatened or 

endangered plants 

due to mitigation 

measure. For 

sensitive plants, 

treatments “may 

impact individuals 

but are not likely to 

result in a trend 

toward Federal 

listing or loss of 

population viability,” 

due to mitigation 

measures and species 

locations.

Same as Alt. B Same as Alt. 

B

10 Final Environmental Impact Statement – Invasive Plant Control Project
Summary of the Final EIS

Significant 

Issues and 

Objectives

Alternative A Alternative B Alternative C Alternative D

Issue 4: Cost 

and 

Treatment 

Effectiveness

(based on 

level of effort 

to meet 

objectives)

No cost 

effectiveness.

Would incur much 

higher costs in 

future. 

Moderately cost 

effective; 

$1,313,000 relative 

cost.

Least cost 

effective;

$1,585,000 

relative cost.

Most cost 

effective;

$550,000 

relative cost.

Objectives: 

Protect 

native plant 

communities, 

soil and 

water 

quality, 

wildlife 

habitat, and 

long-term 

ecosystem 

health

No protection; no 

effectiveness.

Weed-related 

impacts to 

vegetation, soil, 

water, riparian 

habitat, etc., would 

continue. 

Highest level of 

treatment 

effectiveness and 

resource protection 

from weed impacts 

due to combination 

of treatments 

including herbicides.

Lowest level of 

effectiveness 

and resource 

protection from 

weed impacts.

Fewer acres 

treated annually 

for a given 

budget due to 

need for repeat 

treatments on the 

same acreage.

High level of 

effectiveness 

and resource 

protection 

from weed 

impacts.

Not quite as 

effective as 

herbicides 

combined 

with other 

methods.

Final Environmental Impact Statement – Invasive Plant Control Project 11
Summary of the Draft EIS

Figure 1. Project Area and Vicinity

12 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 1 • Purpose and Need

Introduction and Setting

This final environmental impact statement describes how the Carson and Santa Fe National 

Forests (Forests) propose to control the spread of invasive, nonnative plants (hereafter referred to 

as weeds) on National Forest System lands within the Forests boundaries. This document was 

prepared in accordance with the National Environmental Policy Act and its implementing 

regulations (40 CFR 1500-1508), as well as other environmental laws and regulations, to evaluate 

and disclose the effects of weed control treatment activities. Additional documentation, including 

more detailed analyses of project-area resources, may be found in the project record, available for 

review upon request from the supervisor’s offices for either of the forests.

The Forests are located adjacent to one another in north-central New Mexico. Figure 1 is a map of 

the project area and vicinity. The physiography of the two forests is highly varied, consisting of 

mountains, mesas, hills, valleys, canyons and grasslands. The Forests are within the Southern 

Rocky Mountain physiographic province and Rio Grande Subsection of the Basin and Range 

Province (Williams 1986). The Sangre de Cristo, San Juan, Jemez, and San Pedro mountain 

ranges are dominating features of the landscape. Elevations range from approximately 6,000 feet 

in the grasslands to 13,000 feet at the summit of Wheeler Peak. Many peaks exceed 9,000 feet in 

elevation.

The climate varies from arid, semiarid highland, and humid to subtropical depending upon the 

elevation. Precipitation ranges from 10 to 35 inches per year with higher amounts received at 

higher elevations. Precipitation comes primarily in the form of short duration, high intensity 

storm events during July and August, along with winter snow accumulations at the higher 

elevations. Air temperatures vary from approximately 95 o

F in the summer to –25 oF in the winter 

(USDA FS 1986).

Purpose and Need for Action

The purpose of and need for controlling or eradicating weed infestations on the Forests is to 

maintain or improve the diversity, function and sustainability of desired native plant communities 

on the Forests. Protecting the abundance and diversity of native plant communities will also help 

maintain or enhance other natural resources that can be impacted by weeds and the loss of desired 

plant communities. Weeds are aggressive, undesirable plants that are a serious threat to the 

Forests. Weeds typically out-compete native plants for space, water, and nutrients, as they have 

characteristics that give them a competitive advantage over native plant species. They 

demonstrate high reproductive capacity through prolific seed production and root sprouting. If 

left uncontrolled, they tend to dominate areas and reduce the diversity and sustainability of native 

plant populations. In some areas, weeds have increased so dramatically that they create a 

monoculture by entirely taking over large areas.

The Forests have a narrow window of opportunity to initiate effective and cost-efficient actions to 

protect native plants and animals, and soil and water resources before the infestations become 

much more difficult and costly to control. Controlling the spread of weed species is now a 

regional and national priority in the Forest Service and other land management agencies. 

In general, weed invasion and spread results in a loss of natural diversity and reductions in the 

quality of wildlife habitat, soil stability and water quality. Weeds can alter ecosystems by 

changing the frequency and intensity of wildfires (Quigley and Arbelbide 1997, Tu et al. 2001). 

More specifically, where weeds occur and continue to spread over native grasslands, riparian 

Final Environmental Impact Statement – Invasive Plant Control Project 13
Chapter 1 • Purpose and Need

areas, rare plant areas, and other sites on the two forests, they are causing a reduction in the 

abundance and variety of native plants. This in turn impacts the abundance and diversity of 

wildlife species that depend on those native habitats. In addition, the root systems of some weed 

species do not hold the soil in place as well as native plants, resulting in increased soil erosion

and streambank instability (Lacey et al. 1989). Some weeds, such as saltcedar (also known as 

tamarisk) reduce water quantity, which is particularly critical to the arid lands in New Mexico.

In New Mexico, the occurrence of weed species is increasing exponentially. At the current rate of 

increase, several new weed species are projected to appear per year (Renz 2004). While the 

number of known weed infestation sites on the Forests is relatively small, occupying less than 

half of one percent of the 3 million acres of land on the Forests, there are likely many more weed 

infestation sites that have not yet been discovered, and weeds typically spread at a rate of between 

5 and 30 percent per year, depending on the plant species and site-specific conditions (Tu et al. 

2001). 

Without effective control treatments, the continued spread of weeds is likely to result in the 

following environmental impacts:

• Ecosystems dominated by invading plants tend to be lower in productivity, slower in

nutrient cycling, less stable hydrologically, and less sustainable when confronted with 

natural disturbances such as fire. Monocultures of single weed species replace natural, 

diverse ecosystems. The establishment and spread of weeds often signals the ecological 

decline of entire watersheds because of the detrimental impact of their spread on the 

diversity of plant communities (FICMNE, 1998). 

• Soil quality and stability are impacted by weeds. The Forests have areas of highly 

erodable soils, which are currently stabilized by vegetation such as bunch grass. 

Knapweed invasion in these sites has the potential to replace the fibrous rooted grass 

species that provide high soil retention with a plant that has a single, deep taproot, thus 

reducing the soil holding capacity of the vegetation (Lacey 1989). In addition, Russian 

knapweed and diffuse knapweed populations are found in scattered locations near 

campgrounds and along roads, which can lead to their rapid spread.

• Water quality is impacted by weeds. Across the two forests, more than 4,000 acres of 

known weed populations are found in valley bottom lands and along streamsides. Also as 

vegetation cover changes to one or more weed species, the amount of surface water 

runoff and stream sedimentation is likely to increase as well. Weeds that have been found 

to displace native rushes and sedges along streams typically reduce the soil stability of 

those streambanks. Water quality can become degraded from these changes in plant 

composition along streams. Previously approved treatments to remove saltcedar, Russian 

olive and Siberian elm from riparian areas along the lower Jemez River on the Santa Fe 

National Forest are showing good success in restoring native riparian vegetation such as 

willows, cottonwoods, sedges and rushes.

• Riparian areas that should provide excellent nesting habitat to wildlife species such as 

Southwestern willow flycatcher are dominated by saltcedar and Russian olive, which 

provide usable, but poor nesting habitat. The U.S. Fish and Wildlife Service found that 

the flycatcher “sometimes nests in saltcedar, but does so at lower densities, and 

apparently at lower success rates than native vegetation (60 FR 10699). Therefore, 

saltcedar invasion likely represents replacement of native habitat with lower quality 

habitat, rather than an increase in habitat availability” (60 FR 10699). For the flycatcher 

14 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 1 • Purpose and Need

and similar riparian-dependent species, continued decline in the native riparian plant 

species may have a detrimental impact. Saltcedar also reduces water availability in 

riparian habitats by as much as four times that of natural vegetation such as willow and 

cottonwood. In addition, saltcedar has a deep root system (as deep as 100 feet compared 

with cottonwood’s root depth of 6 feet) that allows it to spread quickly away from the 

immediate riparian area and into more terrestrial vegetation, where it can replace 

relatively dry site grasses (Colorado DNR 2004).

• Weeds impact the recovery and maintenance of threatened and endangered plants. The 

Holy Ghost ipomopsis is an endangered plant that occurs along a road on the Pecos/Las 

Vegas Ranger District. The road is a popular access route to the Pecos Wilderness, as well 

as other recreation activities. Without weed control treatment, populations of bull thistle

and scotch thistle are likely to invade the site where Holy Ghost ipomopsis grows. 

Because these weeds prefer similar conditions as the ipomopsis plant, an infestation 

would be a detriment to the Holy Ghost ipomopsis population. The threat of weeds taking 

over sites occupied by rare plant species is also of particular concern in designated 

botanical special interest areas on the Santa Fe National Forest. 

• Wildlife habitat is degraded or lost when weeds cause a decline in native ground 

vegetation that provides nesting cover, seed-producing foods, and habitat for small 

mammals. Large areas of weed infestations would likely lead to a reduction in 

populations of deer, elk and nongame wildlife populations (FICMNE 1998). Palatable 

forage for game and nongame wildlife species decreases as weeds take over. The North 

Ponil area on the Carson NF has more than 1,000 acres of bull thistle, along with small 

populations of knapweed and leafy spurge, threatening this area’s habitat quality. In 

addition, grazing and foraging animals (livestock, elk, deer, etc.) can be injured or die 

from weeds that are poisonous to animals that feed on them, such as black henbane and 

poison hemlock (FICMNE 1998). Yellow starthistle can induce a neurological disorder in 

wild or domestic horses that is usually fatal. 

• Weeds impact the quality of recreational activities on the Forests. Along trails, hikers 

encounter thistles and knapweeds that have spiny flowers and leaves. Dead weed stalks 

are known to impede access to meadows and riparian areas, or discourage return trips 

(FICMNE 1998). Increased weed spread is expected along popular recreation use 

corridors such as State Highway 38 (Questa Ranger District), State Highway 4 (Jemez 

Ranger District) and State Highway 63 (Pecos/Las Vegas Ranger District). The North 

Ponil area of the Questa Ranger District demonstrates this growing conflict as bull thistle

populations spread through the Ponil Fire burned area. Saltcedar is becoming so 

dominant along some streams that it is limiting public access to those popular streamside 

areas (USDA FS 1998b, USDA FS 1998c). In addition, forest visitors and workers may 

come in contact with some weeds such as black henbane, which pose a health threat. 

• Areas of high scenic value are becoming degraded as weeds tend to occur and spread 

along the sides of popular and visible roads and trails, as well as in riparian areas and 

grassy meadows. As single species weed monocultures continue to develop and replace a 

diverse composition of native plants, aesthetic or scenic values of these areas diminish. 

• Wilderness characteristics are threatened as weeds spread into these areas and form 

monocultures, reducing the natural diversity and integrity of native plants and animals. 

These changes in plant composition lead to detrimental changes in ecological processes 

and functions. Although wilderness areas on the two forests do not show high numbers of 

Final Environmental Impact Statement – Invasive Plant Control Project 15
Chapter 1 • Purpose and Need

infestations (about 25 acres found so far), routes into the wilderness areas exceed 800 

acres and have a high potential to spread into the wilderness areas.

• Culturally important plants such as osha, quelites (wild spinach), willow, chimaja, or 

purslane tend to decline where weed invasions occur (Bremer 2003). Because many of 

the known weeds occur near roads and trails where weed spread is most common, their 

availability will become increasingly more limited. 

• Local economies can be indirectly impacted as weeds, which cause declines in habitat 

quality for game animals and fish, reduce revenues from hunting and fishing. Declines in 

habitat and forage quality also reduce the economic value of our rangelands and pastures. 

In addition, weeds that cause a decline in native plants impact people who use native 

plants for making dyes and baskets. 

The Forests are in a good position to deal with these plants now because the weed problem on the 

Forests has not reached an epidemic level where it would take large-scale, costly efforts to solve. 

If the problem is treated in this early stage, using an integrated approach, it can be managed much 

more quickly, with less ground and habitat disturbance, and without the use of aerial herbicide 

spraying.

Background: Existing Condition

The New Mexico Department of Agriculture (NMDA) established a list of 32 weed species 

considered to be “noxious” and known to occur or with potential to occur within the State1

(NMDA 1999). The NMDA categorizes the weeds into three classes: 

• Class A weeds have very limited distribution in New Mexico, and include species 

threatening to invade the State; 

• Class B weeds have distribution limited to a particular area of the State; and

• Class C weeds are distributed throughout the State.

Of the 32 weeds listed with the State, the Forests targeted 19 species that are known to occur, and 

5 species that have potential to occur on the Forests. Some species were removed from the Forest 

lists because they are medicinal plants such as St. John’s wort (Hypericum perforatum) and wild 

licorice (Glycyrrhiza lepidota). Table 5 lists these species and their main threat to the Forests. 

Figure 6 displays the general distribution of weed species across the project area, although the 

points on the map do not accurately represent the size or extent of each weed infestation, and 

most infestations are currently relatively small.

In a broad sense, a weed may be thought of as simply a plant out of place. A plant may be 

desirable in one place and undesirable in another: For example, grass in a lawn compared with 

grass in a garden; or a Russian olive tree decorating a suburban home compared with invading a 

wildland riparian area. In land management terms, a more precise definition is “plants that 

interfere with management objectives for a given area of land at a given point in time” (Whitson 

1

 In a September 20, 1999 letter to the public, Frank A. DuBois, Director of the New Mexico Dept. of Agriculture, 

announced the selection of plant species to be targeted as noxious weeds pursuant to the New Mexico Noxious Weed 

Management Act of 1998. 

16 Final Environmental Impact Statement – Invasive Plant Control Project

 
Chapter 1 • Purpose and Need

2000). Federal law defines weeds in a similar way and provides national direction for dealing 

with weeds2

. 

For the last several years, resource specialists on both forests have noticed weed species 

increasing on the Forests. Weed surveys were initiated on both forests in 1997 and have continued 

up to the present. The first surveys sampled a portion of each ranger district and found 16 species. 

The surveys completed to date were primarily roadside surveys and did not cover the entire 

forest. Not all disturbed sites (such as recent fires) have been completely surveyed, but these 

areas serve as likely places for weeds to gain a foothold. As summarized in Table 4 and displayed 

in Figure 6, of the 3 million acres comprising the two forests, there are approximately 7,350 acres 

of known weed infestations in a wide range of sizes and a broad distribution. The size of each 

infestation currently varies from less than 1 acre to several hundred acres. Most infestations 

(more than 75 percent) are less than an acre in size. Appendix 7 provides a list of each mapped 

infestation, including weed species, infestation size, and location. It is important to note that the 

existing weed inventory probably represents a small sample of the acres where weed infestations 

may be found on the Forests.

The mapped weed sites do not reflect the density of weeds within each site. Most of the mapped 

weed sites include patches without weeds that would not be treated. Therefore, not all 7,350 acres 

would be treated. On the other hand, most weed-infested sites require repeat treatments of the 

same area in order to meet the treatment objectives (e.g. complete eradication or long-term 

control). 

Most of the weed populations on the Forests are along roads, in developed or dispersed 

(undeveloped) recreation sites, in valley bottoms and along streams. Weed infestations also occur 

on the roads and at trailheads leading into wilderness areas on the Forests and a few weeds have 

already spread into the wilderness areas.

Table 4. General Groups of Weeds

Infested Areas Estimated 

Acres*

Minimum 

Size

Maximum 

Size

Average 

Size

Along Roads/Trails 1,052 0.01 74.00 3.80

Valley Bottoms/Riparian Areas 4,032 0.01 1,035.00 10.40

Scattered 1,380 0.10 65.70 5.60

Well Pads (Jicarilla Ranger District) 12 0.20 0.40 0.30

Wilderness 25 0.10 5.60 0.90

Wilderness Boundary Roads/Trailheads 871 0.10 100.00 8.20

* Acre figures represent approximations in the category. Some invasive plant populations may fall into more than one 

category and so would be counted more than once.

2

 The Federal Noxious Weed Act of 1974 defines weeds as “any living stage (including but not limited to seeds and 

reproductive parts) of any parasitic or other plant of a kind, or subdivision of a kind, which is of foreign origin, is new to 

or not widely prevalent in the United States, and can directly or indirectly injure crops, other useful plants, livestock, or 

poultry or other interests of agriculture, including irrigation or navigation, or the fish or wildlife resources of the United 

States, or the public health.”

Final Environmental Impact Statement – Invasive Plant Control Project 17

 
Chapter 1 • Purpose and Need

Bull thistle is the most abundant weed on the Forests, covering a total of about 2,540 acres and 

ranging in population size from a few hundred square feet up to a 130-acre patch on the Questa 

Ranger District of the Carson NF. The combination of Canada thistle and musk thistle is quite 

common, with 1,930 acres found so far on the Forests.

Smaller populations of weed species (or groups of species) are, in order of abundance: knapweeds

(200 acres), toadflaxes (63 acres), hoary cress/field bindweed (54 acres), leafy spurge (42 acres) 

and poison hemlock (22 acres). Less than an acre each of yellow starthistle and perennial 

pepperweed are found on the Forests. Although small in size and number, these populations pose 

a threat because of their ability to take over a vegetation community and their potential to spread. 

Once they become established across large areas, these species become difficult to eradicate. 

Also, these weed survey results underestimate actual weed infestations on the Forests, since many 

areas have not been surveyed. 

In valley bottoms or in riparian areas, the saltcedar/Siberian elm/Russian olive/bull thistle

complexes predominate (about 2,000 acres), along with populations of bull thistle, Canada thistle

and musk thistle (about 2,100 acres of pure stands and intermixed thistle complexes). Hoary cress 

(29 acres), knapweeds (45 acres), leafy spurge (39 acres), yellow toadflax (47 acres) and poison 

hemlock (22) pose a special threat, even though the numbers are small, because of their ability to 

take over plant communities. 

Wildlife species depend heavily on these riparian areas in the arid Southwest, and so the weeds’ 

ability to reduce native plant diversity has a magnified impact on the Forest’s wildlife habitats. 

Along travel corridors, more than 5,000 acres of weeds are found that pose a threat of spreading 

into other places that have not yet been infested3

. Bull thistle (470 acres) and Canada thistle (266 

acres) are the most likely to spread, but small populations of leafy spurge found along Hwy. 285 

and Hwy. 64 near Tres Piedras also pose a threat of spread.

Away from valley bottoms, riparian areas, and main travel routes, Canada thistle/musk thistle

(1,320 acres) and bull thistle (1,300 acres) pose the largest threat of spreading because of their 

wide distribution. The largest concentration of known bull thistle lies in the Ponil Fire burn area 

in the Valle Vidal (1,250 acres). On the Jicarilla Ranger District, infestations of scotch 

thistle/musk thistle are found at natural gas wellheads and along roads leading to these facilities. 

Although the amount of scotch thistle is relatively small, the potential for spread is high because 

of the intermingled nature of land ownership and use in this area. Cooperation among all the land 

management agencies is particularly important in order to control this threat. Along the Rio Tusas

drainage, the amount of leafy spurge is relatively small, but when the threat is seen in the context 

of infestations on adjacent private land, the threat increases.

Weeds are projected to increase annually in the United States at a rate of 8 to 12 percent per year 

without treatment (FICMNE 1998). Projections on the two forests predict that the spread is 

expected to be between 5 and 30 percent annually, slightly lower than the national average for 

some species and conditions based on arid Southwestern growing conditions. Saltcedar found in 

riparian areas is expected to increase at a slower rate, and leafy spurge would likely increase at 

the higher rate. For purposes of this analysis, an estimate of 8 percent per year is used in order to 

account for growth without overstating the estimates in the face of the variable nature of the 

species and other conditions.

3 Some weed infestations along roads are also found near riparian areas and so total acres are not additive.

18 Final Environmental Impact Statement – Invasive Plant Control Project

 
Chapter 1 • Purpose and Need

Table 5 gives a brief description of known weed species. For a more detailed discussion, see 

Appendix 2, “Weed Species Ecology and Impacts.”

Final Environmental Impact Statement – Invasive Plant Control Project 19
Chapter 1 • Purpose and Need

Figure 2. Weed Distribution

20 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 1 • Purpose and Need

Table 5. Weed Species: Locations and Impacts

Weed Species Life Cycle4 Location Impact

Black henbane

(Hyoscymas niger)

HYNI

Biennial Found in pastures, fence rows, 

roadsides, and riparian areas.

Poisonous to livestock and a 

health threat to humans.

Bull thistle

(Cirsium vulgare)

CIVU

Biennial/annual or 

short-lived 

perennial

Grows on heavy, fertile soils 

and can dominate openings 

quickly. Often found in 

association with musk thistle. 

Reduces forage in natural areas by 

replacing usable forage with 

spiny, inedible vegetation.

4 Perennial plants persist year round and so have a high capacity to spread. Annuals grow and die after a year and so can reproduce fast, but are more vulnerable to actions that 

disrupt this pattern. Biennials take 2 or more years to complete their life cycle and so are the most susceptable to efforts that disrupt their reproductive pattern. These 

characteristics in combination with a plant species reproduction means (seed, root sprouting or both) factor in how fast weeds can take over a site and spread to new places, 

and how well it can be controlled.

Final Environmental Impact Statement – Invasive Plant Control Project 21

 
Chapter 1 • Purpose and Need

Weed Species Life Cycle4 Location Impact

Canada thistle

(Cirsium arvense)

CIAR4

Perennial with root 

sprouting

Found almost anywhere. Often 

found in association with musk 

thistle.

Competes with and displaces 

native vegetation. Decreases 

species diversity and changes the 

structure and composition of some 

habitats to reduce the 

effectiveness for native animal 

species.

Musk thistle

(Carduus nutans)

CANU4

Biennial or annual

Found in association with a 

number of other thistles. In 

disturbed areas but can invade 

native grasslands. Grows best in 

moist alluvial soils, but tolerates 

a wide range of conditions.

Chemically alters soil to inhibit 

germination and growth of other 

species. Weakens other species. 

Replaces forage with inedible 

vegetation.

Scotch thistle

(Onopordum 

acanthium)

ONAC

Biennial or shortlived perennialRoadsides/well pads on the 

Jicarilla Ranger District.

Reduces productivity and strongly 

competes with native plants for 

resources. Replaces desirable 

species.

22 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 1 • Purpose and Need

Weed Species Life Cycle4 Location Impact

Dalmation Toadflax

(Linaria dalmatica)

LIDA

yellow toadflax

(Linaria vulgaris)

LIVU2

Perennial

Found along road, in pastures 

along fences, rangelands and 

clearcuts.

Pushes out native grasses and 

other perennials to change the 

species composition of natural 

communities. Seedlings are less 

effective at competing for 

nutrients and moisture than 

developed plants.

Diffuse knapweed

(Centaurea diffusa)

CEDI3

Annual, biennial, or 

short-lived 

perennial.

Rights-of-way, farm roads. 

grasslands, shrub lands and 

riparian communities.

Forms dense colonies that reduce 

population of native species and 

serve as precursors to other weeds 

(like leafy spurge).

Spotted knapweed

(Centaurea 

biebersteinii)

CEBI2

Biennial or shortlived perennial.

Prefers disturbed areas to 

establish but can spread into 

undisturbed areas once in a site.

Highly adapted to capturing 

moisture and nutrients so it can 

spread and choke out native 

species. Decreases the water 

storage capacity of soil and can 

increase soil erosion potential by 

replacing native plants’ network 

root system with taproot.

Yellow starthistle

(Centaurea 

solstitalis)

CESO3

Annuals Open grasslands

Uses more water than native 

species and out-competes for it. 

Reduces wildlife habitat and 

forage. Can kill horses if ingested.

Final Environmental Impact Statement – Invasive Plant Control Project 23
Chapter 1 • Purpose and Need

Weed Species Life Cycle4 Location Impact

Field bindweed

(Convolvulus 

arvensis)

COAR4

Perennial vine Wide range

Takes nutrients and water to 

reduce the abundance and vigor of 

native plants and habitats

Hoary cress

(white top)

(Cardaria draba)

CADR

Perennial

Grows in nonshaded, disturbed 

areas, including roadsides, and 

watercourses (ditches).

Displaces native forage species 

and reduces forage quality 

because it is toxic to livestock.

Leafy spurge

(Euphorbia esula)

EUES

Perennial Pasture

Displaces all other vegetation in 

pastures, rangelands and native 

habitats. Hillsides and prairies. 

Can displace all forbs and grasses 

in natural areas. Root system 

allows persisting even after 

treatment. Chemically changes the 

soil to eliminate other competing 

plants.

Perennial 

pepperweed

(Lepidium 

latifolium)

LELA2

Perennial Riparian areas, wetlands and 

marshes.

Creates monoculture that displace 

native plants and reduces habitat 

effectiveness for native animals.

24 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 1 • Purpose and Need

Weed Species Life Cycle4 Location Impact

Poison hemlock

(Conium 

maculatum)

COMA2

Biennial or annual Roadsides, field margins, and 

ditchbanks.

Displaces native species after 

disturbance. Degrades habitat 

quality quickly. Poisonous to 

humans

Russian knapweed

(Acroptilon repens)

ACRE3

Perennial Found in grass and shrub lands 

as well as riparian forests.

Reduces desired vegetation such 

as perennial grasses. Chemically 

alters sites to eliminate 

competition.

Russian olive

(Elaeagnus 

angustifolia)

ELAN

Perennial shrub/tree Found in or near riparian 

vegetation.

Creates dense, monoculture stands 

that out-compete native 

vegetation, modifies vegetation 

structure and displaces native 

wildlife. Alters nutrient cycling 

and system hydrology by 

spreading through woodlands and 

connecting lowland riparian 

forests with more open, upland 

areas. This has an impact on longterm establishment of native 

riparian species, such as 

cottonwood.

Final Environmental Impact Statement – Invasive Plant Control Project 25
Chapter 1 • Purpose and Need

Weed Species Life Cycle4 Location Impact

Salt cedar 

(tamarisk)

(Tamarix spp)

TAMAR2

Perennial shrub Riparian areas

Replaces native wood species 

such as cottonwood, willow, and 

mesquite. Chemically alters the 

soil to eliminate competition from 

native species to reduce the 

habitat effectiveness for native 

wildlife species. Uses more water 

than native species and changes 

the flood/sediment deposition 

regime so that native species such 

as cottonwood cannot regenerate

Siberian elm

Ulmus punila)

ULPU

Perennial tree Near moist areas, riparian

Can out-compete native trees 

species such as cottonwood and 

willow. 

26 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 1 • Purpose and Need

Additional species of weeds on the NMDA list with potential for introduction and spread on the 

Forests (USDA NRCS 2002) would be prioritized for early detection and eradication, before they 

become well established and are more difficult to control. These species are:

• African rue (Peganum harmala), 

• Alfombrilla (Drymaria arenaroides), 

• Camelthorn (Alhagi pseudalhagi), 

• Dyers woad (Isatis tinctoria), 

• Eurasian watermilfoil (Eurasian spicatum),

• Halogeton (Halogeton glomeratus), 

• Hydrilla (Hydrilla verticillata), 

• Jointed goatgrass (Aegilops cylindrical),

• Malta starthistle (Centaurea melitensis),

• Onionweed (Asphodelus fistulosis), 

• Purple loosestrife (Lythrum salicaria), 

• Purple starthistle (Centaurea calcitrapa), and 

• Teasel (Dipsacus fullonum).

Management Direction - Desired Condition

The Forest Plans for the Forests established broad programmatic management direction (goals, 

standards and guidelines) applicable to this project. The Forest Plans contain numerous standards 

and guidelines (i.e. management direction) for maintaining biological diversity, long-term soil

productivity, water quality, stable and productive watershed conditions, habitat for rare plant and 

animal species, and visual quality—all resources that are threatened by continued weed 

infestation and spread. 

The Carson National Forest Plan describes a goal to “maintain genetic and ecological diversity” 

for sustaining the forestlands (USDA-FS 1986, Sustainable Forests Section, p. 2), as well as a 

vision statement in the wildlife and fish section that emphasizes biological diversity (USDA-FS 

1986, Wildlife and Fish Section, p. 1).

Several standards in the Santa Fe National Forest Plan emphasize promoting improvements in 

diversity and hydrologic conditions. For example, it states, “riparian areas will be enhanced 

through direct improvement projects,” and that the forest will “achieve satisfactory condition in 

riparian ecosystems.” (USDA FS 1987, p. 20).

The Santa Fe National Forest Plan has management direction specific to weed control treatments 

such as: “Select treatment methods for plant control according to the NEPA process and the 

following criteria.” The criteria include numerous limitations for each weed control method 

involved in the integrated weed treatment strategy: mechanical (large equipment), prescribed fire, 

biological, manual, and herbcides. (USDA FS 1987, pp. 75-76).

The Santa Fe National Forest Plan also describes the goal of maintaining diversity of plant 

communities and different ages (USDA FS 1987, p. 9). The Santa Fe Plan also states that it will 

“improve much of the unsatisfactory watershed condition by improving vegetative conditions”

(USDA FS 1986, p. 13).

Final Environmental Impact Statement – Invasive Plant Control Project 27
Chapter 1 • Purpose and Need

In order to follow Forest Plan direction and meet the purpose and need for this project, the desired 

condition of the Forests is to have minimal establishment or spread of weed infestations. It would 

be virtually impossible to eradicate all weeds within the forest boundaries. However, to meet 

Forest Plan goals for resource protection, it is important to control the establishment and spread 

of invasive weeds, particularly in special plant and wildlife habitats, riparian areas, wilderness 

areas and roads leading to them, livestock grazing allotments, recreation sites, and administrative 

sites.

Other Direction

Other management direction relevant to this project includes the following:

• “National Invasive Species Management Plan” (NISC 2000): Provides a blueprint for 

Federal agencies to manage invasive species. It provides guiding principles to all 

agencies and describes the roles and responsibilities of Federal agencies. The guiding 

principles as stated in the plan are: Take action now; be cautious and comprehensive; 

work smart, be adaptive; find balance; pull together; be inclusive and meet specific 

needs. The plan states that the Forest Service has broad authority to prevent the spread of 

invasive species on National Forest System lands and is authorized to assist Federal, 

State, and private entities on lands outside NFS lands.

• “Forest Service Manual 2080” (USDA FS 1995): This Forest Service policy regarding 

weeds was revised in 1995 to increase emphasis on integrated weed management in 

assessment and forest planning.

• “New Mexico Executive Order 00-22” (NMEO 2000): Directs State executive agencies 

to manage weed infestations designated by the New Mexico Department of Agriculture as 

Class A weed infestations on state land rights-of-way by making use of integrated pest 

management techniques. 

• “Noxious Weed Management Act” (NMSTATS 1978): The State of New Mexico enacted 

this legislation to recognize the adverse economic and environmental impacts of these 

weeds and the need for action to reduce this threat.

• “Forest Service Manual 2100” (USDA FS 1998a): Provides additional policy 

requirements for use of pesticides (or herbicides).

Other laws, regulations and policies will be followed as they apply to the control of weeds on 

National Forest System lands.

Proposed Action

The proposed action is an integrated set of weed control actions that will eradicate, control, or 

contain weeds. This integrated weed management approach is described in the USDA FS Manual 

2080 in managing weeds (USDA FS 1995). This approach recognizes that using only one 

management method is not likely to be effective, and flexibility is needed to address differences 

in site-specific conditions. 

The proposal involves applying one or more of the following treatment methods to each weed 

infestation:

• Manual methods with hand tools or hand-operated power tools.

28 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 1 • Purpose and Need

• Mechanical methods such as mowing to cut off plant tops, or disking to lift up roots using 

heavy machinery.

• Biological methods that involve releasing live insect or plant pathogens that selectively 

attack specific weed species.

• Controlled grazing using goats and sheep.

• Chemical methods using ground-based application of herbicides. 

• Prescribed burning using fire to kill weed populations.

• Cultural methods using native plants, seeds and/or soil cover mulches after weeds are 

removed using other methods, to re-establish native vegetation.

Treatments would begin in 2006. During the next 10 years, each forest anticipates treating 300 to 

800 acres per year, based on anticipated funding. Each forest expects a maximum of 1,500 acres 

per forest per year would be treated if funding permits.

Appendix 7 contains a list of known infestations and proposed treatments for each site-specific 

infestation. Newly discovered infestations would receive similar treatments following the 

conditions prescribed in the “adaptive management strategy.”

Adaptive management in project planning is a relative recent innovation. As noted by the Council 

for Environmental Quality’s Modernizing NEPA task force (USCEQ 2003), the term “adaptive 

management” was first suggested by the CEQ in 1997 as the result of an effectiveness study. In 

the 1997 study, the CEQ recognized that environmental protection afforded by the traditional 

environmental management model—that predicts, mitigates and implements—depends on the 

accuracy of the predicted impacts and expected results of any mitigation. The study concluded 

that a “major difficulty with the traditional environmental impact analysis process is that it is a 

one-time event; ... [requiring] research, modeling, and other computations or expert opinions 

[that] are analyzed... [T]he analysis of potential environmental impacts is prepared, mitigation 

measure are identified, and a document is released for public review.” The 1997 CEQ report 

noted that this process does not account for unanticipated changes in environmental conditions, 

inaccurate predictions, or subsequent information that might affect the original environmental 

protections. The adaptive management model—by adding a monitoring and adaptation 

component—was seen as a significant improvement. (USCEQ 1997).

The adaptive management approach was further defined in January 2005, when the Forest Service 

published planning rules that recognize the role of adaptive management in implementing forest 

plans: “Adaptive management is an approach to natural resource management where actions are 

designed and executed and effects are monitored for the purpose of learning and adjusting future 

management actions, which improves the efficiency and responsiveness of management.” (36 

CFR 219.16, 70 FR 1060)

The adaptive management approach is particularly well suited for weed control because of the 

need to respond quickly to changing conditions in order to meet the purpose of weed control 

projects. Controlling known weed populations is only effective if it can be accomplished by quick 

responses when new species or new populations of existing species are found. Weed infestations 

change over time, and even a comprehensive inventory cannot adequately find and map all 

existing weed sites on the 3 million acres comprising the two forests. A single plant can produce 

more than 100,000 seeds, and some plants can go to seed 3 times a year. Three plants can expand 

to half an acre within a single growing season; a half acre can grow to 10 acres during the same 

Final Environmental Impact Statement – Invasive Plant Control Project 29
Chapter 1 • Purpose and Need

period. It would take approximately a year or more for the Forests to complete an environmental 

assessment under NEPA for new infestations found. And new infestations and new species would 

usually be given the highest priority for treatment in order to quickly stop their spread. Failure to 

quickly treat new weed infestations leads to larger infestations requiring larger-scale, higher-cost 

treatments with greater environmental impacts. (USDA FS 2001b)

In order to avoid the adverse effects posed by rapid weed population expansion, this proposed 

project includes applying an adaptive strategy that allows for the same integrated weed control 

treatments analyzed in this document to be applied to newly discovered weeds in other locations 

on the Forests. Specific guidelines and criteria (defined in Chapter 2) would be followed to ensure 

that treatments applied to new sites are within the scope of the treatments and effects described in 

this FEIS. This strategy is consistent with Forest Service guidelines on applying adaptive 

management to site-specific environmental analysis for weed management projects (USDA FS 

2001b). 

The CEQ Task Force noted that “[t]o successfully implement adaptive management, monitoring 

must occur for long enough to determine if the predicted effects were achieved.” Therefore, as 

part of the proposed action, inventory and monitoring are proposed as methods to adapt 

components or parameters of this decision to future weed treatment areas. This strategy is 

described in detail in Chapter 2. 

The proposed weed control program involves the following steps: 

• Inventory by searching places with a high likelihood for finding new weed populations, 

and enter new weed locations in the Geographic Information System database.

• Prioritize and select appropriate treatment methods based on criteria in this DEIS 

(Chapter 2), including applicable mitigation measures based on site conditions.

• Develop an implementation plan that is reviewed and updated annually, including 

coordination with other agencies regarding weed control activities.

• Notify the public about the annual weed treatment schedule and site-specific locations.

• Implement weed control treatments.

• Monitor for: treatment effectiveness in meeting weed control objectives; effects on other 

resources relative to those predicted in this DEIS; and implementation and effectiveness 

of mitigation measure used to minimize adverse impacts.

• Evaluate and document monitoring results for use in future weed treatment prescriptions.

Forest Plan Amendment

The proposed action and all action alternatives include an amendment to the Santa Fe 

National Forest Plan that would allow the use of herbicides in places currently prohibited 

by Forest Plan standards and guidelines. These areas include municipal watersheds and 

soils with low revegetation potential. Chapter 2 describes the proposed amendment in 

detail. The Carson National Forest Plan does not prohibit the use of herbicides in any 

specific areas. 5

5 The Forest Planning rule published in January 2005 (70 FR 1022-1061) makes provision for forest plan amendments 

begun before these rules were put in place. Accordingly, this amendment will continue to use the provisions of the 

planning regulations in effect before November 9, 2000 (70 FR 1060).

30 Final Environmental Impact Statement – Invasive Plant Control Project

 
Chapter 1 • Purpose and Need

Decisionmaking Framework 

The forest supervisors for each forest are the responsible officials for decisionmaking on this 

project. They will decide which weed control alternative, if any, to approve for implementation, 

including approval of the proposed adaptive management strategy. Their decision includes 

consideration of the mitigation measures and monitoring requirements specific to this project. 

The forest supervisor for the Santa Fe NF will decide whether to approve the Forest Plan 

amendment as proposed or with modifications.

If a weed control alternative is selected, it will allow for treatment of the known weed populations 

as mapped and described in the EIS, as well as newly discovered weed populations. Treatment of 

new populations would adhere to the adaptive strategy criteria in the EIS, and would be reviewed 

per Forest Service Handbook 1909.15 (Section 18) to determine whether such actions are within 

the scope of the treatments and effects disclosed in the EIS, or whether additional environmental 

analysis under NEPA is needed.

The scope of this project and NEPA decision does not extend to weed prevention and education

activities. While the Forests recognize that prevention and education are essential components of 

an overall integrated weed management strategy, proactive weed prevention and educational 

activities are already being implemented and do not require additional environmental analysis and 

decisionmaking subject to the NEPA process. Weed prevention is considered and often included 

as a mitigation measure in many site-specific project EAs and EISs, such as for logging, facility 

construction, special uses and other activities that can contribute to the spread of weeds (USDA 

FS 2001a). Contractors are typically required to wash their vehicles and equipment to eliminate 

weed seeds prior to bringing them onto national forest lands. Outfitter/guides and others using 

wilderness areas are prohibited from bringing in hay or unprocessed feed for horses or other 

domestic animals.

Public Involvement

One of the first steps in the public involvement stage of project planning is to use public 

comments to determine the appropriate scope of the analysis. In the scoping process, the need, 

context, and issues related to a proposed action are considered by the public, sponsoring agency, 

and other agencies potentially affected by the proposed action.

In 1996 and 1997, the Forest Service met with other Federal, State and county agencies to discuss 

the threat of weeds and coordinate treatments. Newspaper articles were also published to inform 

the public about the threat of weeds and the full range of treatment options, such as those being 

considered by the Forests. In 1998, the Forests began scoping with the public for this project, 

starting with public meetings held in Taos and Espanola. In March 2000, a scoping letter was sent 

to approximately 450 individuals, agencies, tribes and organized groups to inform them about the 

Forest’s weed control treatment proposals. At that time, each forest was independently working 

on separate environmental assessments for forest-wide weed control projects. As a result of the 

March 2000 scoping, a decision was made to combine the efforts of the two forests and document 

the analysis in an EIS. 

In December 2000, the Forests sent another scoping letter to the public about the proposed actions 

and published a Federal Register Notice of Intent to Prepare an EIS. At the request of local 

citizens, a field trip was conducted to discuss weed infestations and show interested people the 

weed conditions on the Tres Piedras Ranger District.

Final Environmental Impact Statement – Invasive Plant Control Project 31
Chapter 1 • Purpose and Need

In December 2003, an additional letter was sent to all potentially affected tribal governments, to 

initiate consultation and solicit their comments about the proposed project. In May 2004, a 4-page 

update document was mailed to known interested or affected parties. It described the final issues 

and alternatives, as well as the status of the draft EIS and estimated release date. 

A total of 34 individuals and 30 organizations commented on the initial scoping letters. The 

largest number of comments questioned the need for treatment when other solutions were 

available, such as eliminating grazing and closing roads, which they suggested led to the weed 

problems. Education was also suggested as a means of dealing with the weed problem. For some 

respondents, education was suggested as a substitute for treatment, and for others education was 

suggested as a complementary activity.

A large number of comments expressed opposition to any herbicide use. Most opposition was 

based on concerns that herbicides could adversely impact human health, nontarget plants, and 

wildlife. Concerns with impact to water quality and fish were also mentioned. Some respondents 

voiced concerns that herbicides were too nonselective and would have too broad of impacts. 

Potential impacts to people with multiple chemical sensitivities were mentioned as reason to 

avoid using herbicides and any associated chemicals (e.g. inert ingredients in the formulations). 

Suggestions were made to use a wide variety of non-chemical methods, such as hand digging 

(possibly enlisting volunteers to do this work) and using goats to graze the weeds where possible. 

In addition to the letters responding to the scoping letters, a petition with approximately 1,000 

signatures was submitted stating opposition to the use of herbicides in managing weeds on the 

Carson National Forest.

One comment also raised concerns with using biological agents because of the possibility of 

introducing an insect that would have unforeseen effects (such as getting out of control itself).

Others with concerns about herbicides allowed that chemicals might be used under controlled 

conditions so that people who use the Forests to collect and use certain products would not be 

adversely impacted from herbicides (or that other methods would not destroy these culturally and 

economically important plants).

Another set of comments supported the need to treat weeds and supported use of the integrated 

approach (including herbicides), as long as appropriate oversight is given to the efforts so they are 

coordinated within the Forests and with other agencies conducting similar efforts. Some 

comments in this set also noted that strong monitoring should be a priority to be successful.

The Draft Environmental Impact Statement underwent public/agency review in July/August 

2004. Appendix 9 responds to comments received on the document.

Issues

The interdisciplinary team (IDT) used public comment to clarify issues relating to the effects of 

the proposed action. Significant issues versus insignificant issues were identified in accordance 

with Council for Environmental Quality (CEQ) NEPA regulations (40 CFR §1501.7 and 

§1506.3). Significant issues relate to those impacts related to the proposed action that cannot be 

avoided without substantially compromising project objectives. These issues drove the 

formulation of alternatives to the proposed action so that the decision maker and the public could 

see the tradeoffs among alternative ways of achieving the purpose and need.

32 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 1 • Purpose and Need

Some issues or concerns raised in comments were not considered significant for one of the 

following reasons:

• The concerns related to effects of the continued spread of weeds under the “no action” 

alternative. Those concerns were not identified as issues but rather as part of the project 

objectives or purpose and need.

• The action suggested or impact of concern is not relevant to (“outside the scope of”) the 

proposed action. For example, many comments suggested the use of prevention measures 

(e.g. eliminating livestock grazing or closing roads). However, the purpose and scope of 

this analysis is to control weeds that exist or become established in order to minimize 

their associated impacts to forest resources. Prevention and education are important and 

separate actions that will continue to be carried out by the Forests and do not need to be 

part of this NEPA project decision. The Forests will continue to participate with other 

land management agencies to coordinate weed control activities and provide public 

information on weed identification and treatment. 

• The impact of concern can be avoided or adequately minimized to a negligible level by 

incorporating appropriate mitigation measures into the proposed action.

• The impact of concern is already regulated by existing laws, regulations and policies.

A list of other issues and reasons for their categorization may be found in the project record.

The following issues provided the focus for developing a reasonable range of alternatives for 

meeting the purpose and need for this project. They reflect public concerns about effects that may 

result from proposed weed treatment actions, even though the magnitude of effects would be 

minimized by the proposed mitigation measures. Chapter 2 presents a detailed description of the 

proposed action, alternatives and associated mitigation measures and monitoring requirements. 

Issue 1: Human Health and Safety

Weed treatment activities have the potential to affect human health and safety in a number of 

ways, including exposure to machinery, equipment and/or chemicals. 

Although exposure to the machinery and equipment poses a safety risk, the larger public concern 

relates to the health risk posed by using herbicides. This risk is defined in three ways: 

• By direct exposure during applications, such as exposure to herbicide applicators from 

the backpack spray drift, or people walking through a recently sprayed area.

• By contact with vegetation that has been sprayed and then collected for use. Some tribes 

and northern New Mexico residents use many plants found on the Forests for food and 

medicine. Plants are also used for ceremonial, home decoration and artistic purposes. A 

number of these users expressed concern that their health will be affected because they 

will be exposed to herbicide residues when they collect and process their plants.

• By direct or indirect herbicide exposure for people with heightened chemical sensitivities. 

Although the Forests would only use herbicides determined by the Environmental 

Protection Agency (EPA) and other research studies to be safe (low risk) for use in areas 

where people live, work and recreate, a health risk would remain for individuals who are 

exceptionally sensitive to any exposure to chemicals in the environment. Some northern 

New Mexico residents moved to this part of the United States to reduce exposure to 

chemicals under the general assumption that this area has lower amounts of chemicals 

Final Environmental Impact Statement – Invasive Plant Control Project 33
Chapter 1 • Purpose and Need

than other places. Within this group are individuals who report varying levels of 

sensitivity to an herbicide or herbicides. Some individuals may not report sensitivity to an 

herbicide but to the additives that enhance an herbicide’s effectiveness (surfactant). Even 

when herbicide label instructions are followed, risk assessments note that some risk 

remains from herbicide use, even if the amount of risk is very low. The only way to 

completely eliminate these risk factors attributed to herbicides is to eliminate the use of 

herbicides altogether.

Issue 2: Wildlife and Fish

Weed treatments have the potential to affect various wildlife species in the following ways: 

• Habitat disturbance: Weed treatment activities such as vehicle use, equipment operation 

and other human activities would cause disturbance in or near habitat.

• Fish/wildlife health impacts from herbicides: Mammals, birds, amphibians, reptiles and 

fish would be exposed to herbicides by ingesting herbicides residing on plants, in the soil, 

and soil organisms, in streams or other water bodies. Concerns have been expressed about 

the potential for adverse impacts to fish or wildlife from single dose exposure or longterm accumulation of herbicides. 

• Habitat reductions: Wildlife could be affected by temporary reductions in vegetation 

brought about by weed treatments. 

Issue 3: Native Vegetation

Weed treatments have the potential to affect native vegetation in a number of ways. All treatments 

(manual, mechanical, grazing, fire, herbicide) could remove some nontarget native vegetation at 

least temporarily and within a relatively small geographic area, reducing the abundance and vigor 

of native plant populations. Of particular concern are potential impacts to plant species of limited 

abundance (threatened, endangered, or sensitive species), although mitigation measures minimize 

this risk.

Issue 4: Cost and Treatment Effectiveness

On weed infestation sites where nonchemical methods are proposed for use without supplemental 

herbicides, weed control effectiveness would be lower and treatment costs higher. Although 

herbicides often require repeated treatments for full eradication, when all things are equal for a 

given site, more frequent and repeated treatments are typically needed to control weeds where 

herbicides are not used, and weeds may spread at a faster rate than they could be controlled where 

herbicides are not used. 

34 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 2 • Alternatives, 

Including the Proposed Action

Introduction

This chapter contains the following key sections: 

• Description of alternatives considered but later eliminated from detailed study. 

• Alternatives considered in detail, which were developed to address one or more 

significant issues while meeting the purpose and need at least partially.

• Adaptive strategy for addressing new weed infestations or situations found on the 

Forests.

• Mitigation and monitoring requirements to avoid or minimize adverse effects.

• Forest Plan amendment for the Santa Fe National Forest Plan.

• Permits and authorizations required prior to implementing this project.

• Comparison of alternatives that provides a basis for choice among alternatives.

The Forest Service interdisciplinary team evaluated four alternatives for this project: 

Alternative A - No Action. This alternative is the baseline for comparing the other 

alternatives. Under this alternative, proposed weed control actions would not occur on the 

Forests, except those approved under previous environmental analysis documents.

Alternative B - Integrated Strategy (Proposed Action). This alternative was developed to 

fully meet the purpose and need for the weed control project while minimizing the risk of 

adverse impacts through mitigation measures and monitoring. It includes the full range of 

appropriate weed treatment methods, and often uses a combination of methods on the same 

site.

Alternative C - No Herbicides. This alternative was developed in response to issues related 

to effects of herbicides on human health, wildlife/fish, and nontarget native vegetation. It 

employs a variety of methods but does not allow herbicides to be used.

Alternative D - Herbicides Only. This alternative was developed in response to the cost and 

treatment effectiveness issue, as it would provide for a high level of effectiveness at a lower 

cost per treated acre compared to the proposed action. It would use herbicides exclusively. 

Alternatives Eliminated from Detailed Study

The following briefly describes three alternatives that were considered but eliminated from 

detailed study, along with the reasons for eliminating them (in accordance with NEPA regulations 

at 40 CFR §1502.14). 

Aerial Herbicide Application 

This alternative was considered but eliminated from detailed study because the extent of the 

current weed infestations on the Forests is relatively small, which indicates that such a broad 

approach would not be necessary to achieve the purpose and need of the project. Aerial 

application can be an effective means of controlling or eradicating very large infestations of 

weeds, particularly in areas that have steep slopes, rocky soils, and are too difficult to access to 

effectively treat from the ground. Aerial application provides a means to effectively treat 

Final Environmental Impact Statement – Invasive Plant Control Project 35
Chapter 2 • Alternatives, Including the Proposed Action

infestations in isolated areas, allowing rapid and efficient reduction of a threat of further 

establishment or expansion. However, given the public concern regarding this method and the 

expectation that ground-based applications can meet the purpose of the project, aerial application 

was not studied in detail.

Weed Prevention 

An alternative to use weed prevention rather than herbicides or other treatments was suggested by 

the public during project scoping. The intent of the alternative would be to take action on human 

activities that promote the spread of weeds, such as by closing roads, restricting or modifying 

livestock grazing permits, and altering existing timber, mining, and recreational off-road vehicle 

activities. However, this alternative would not meet the purpose and need because it would not 

effectively reduce existing weed infestations or address the detrimental impacts of those 

infestations. It would not reduce the threat from undiscovered weeds that exist now or are 

expected to invade despite preventative measures. Impacts from weeds would continue to spread 

at a rate of 5 to 30 percent annually and degrade resources on the Forests despite the best 

prevention measures being implemented. Weed prevention is already being used on both forests 

and is often integrated as a mitigation measure during planning for ground-disturbing projects, 

such as the requirement to wash vehicles prior to use on the Forests. Prevention actions typically 

do not require NEPA documentation for implementation, although some project decisions could 

include prevention measures in them (e.g. grazing allotment management planning or ATV 

management projects). Weed prevention and education are also part of interagency agreements 

being implemented, New Mexico Department of Agriculture calendars, national publications, and 

news media releases.

Organic Treatment Methods

A third alternative was eliminated that would use methods common in organic gardens and 

nurseries. These methods include covering weeds with newspaper and dirt, rubber mats, and other 

means without disturbing the ground. There is limited experience and little study to show that 

using these methods would be effective to meet the purpose and need on a landscape scale across 

portions of the 3 million acres comprising the two forests. In addition, these methods are not 

practical to use on Federal lands where weeds are scattered and isolated. Finally, the use of 

newspaper and dirt may create more suitable sites for weed infestations and items such as rubber 

mats would likely be stolen. If any of these methods can be shown to be effective and if they meet 

the criteria of the adaptive strategy described in this FEIS, then they could be used by the Forests.

Alternatives Considered in Detail

Alternative A: No Action 

Under the No Action Alternative, previously approved and ongoing management activities and 

land uses would continue on the Forests. This includes weed treatment activities previously 

approved such as those along the lower Jemez River and those being implemented by other 

jurisdictions within the Forest boundaries such as along Federal, State and county roads. Chapter 

3 and Appendix 1 describe past, present and foreseeable future activities including other weed 

treatment activities within and adjacent to the Forests. Weed inventories and prevention activities 

would also continue to occur. 

36 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 2 • Alternatives, Including the Proposed Action

Alternative B: Integrated Weed Control Strategy (Proposed Action) 

This alternative involves applying one or more methods to eradicate, control, or contain weeds 

where they occur on the Forests. A common element in all treatments is to destroy the plant, 

disrupt growth, or interfere with the reproduction cycle. Treatments are scheduled to begin in the 

spring of 2005, and would occur during the weed’s growing season—spring, summer or fall—

depending on the weed species and treatment method. Based on expected funding, each forest 

anticipates treating 300 to 800 acres annually, with an annual maximum of approximately 1,500

acres per forest, during the next 10 years. An adaptive strategy would be used to apply treatments 

to newly discovered weed populations or to modify treatment prescriptions based on results of 

monitoring. Treatment methods would need to be within the scope of the treatments and effects 

described in this document to be implemented under the adaptive strategy, and the same 

mitigation measure would apply to avoid or minimize adverse impacts. The adaptive strategy, 

including criteria and parameters that must be met in order to treat new weed sites or alter 

treatment prescriptions, are described later in this chapter.

This proposal applies a variety of methods including manual, mechanical, biological, cultural, 

prescribed fire, grazing, and herbicides, based on the most feasible and appropriate methods for 

meeting treatment objectives, primarily based on the particular weed species and population size, 

along with considerations about specific locations and public concerns. Selection of the most 

feasible and appropriate treatment also depends on the specific objective (eradication, control or 

containment), risk of weed expansion, weed species biology, time of year, and environmental 

setting. By proposing several methods for weed control, this approach recognizes that using only 

one management method is unlikely to be effective in all situations.

Figure 3 provides general locations for treatments of known weed populations, although the size 

of each weed population is significantly smaller than it appears on the map, due to the map size 

and scale. Appendix 7 lists each mapped weed population and the treatment method(s) proposed. 

The following describes proposed treatment methods:

Herbicides

Chemicals used to control plants are known as herbicides. Herbicides kill 

the existing plant but often allow remaining seeds to germinate. 

Herbicides are known through experience with similar Forest Service 

efforts to be the most effective treatment method for eradicating or 

controlling the weed species that currently exist on the two forests, 

especially when used in conjunction with an integrated treatment effort that improves the 

effectiveness of nonchemical treatments, either concurrently or as followup treatments.

Herbicides are being proposed for weed sites where nonherbicide methods do not seem 

feasible or appropriate, due to ineffectiveness of other treatments, species characteristics, 

population size, treatment priority and objective, or access or terrain limitations of other 

methods.

The primary herbicides proposed for use on the Forests have picloram, metsulfuron methyl, 

clopyralid, dicamba, triclopyr, imazapyr, imazapic, or glyphosate as their active ingredients. 

See Table 60 in Appendix 3 for general discussion of these chemicals and their properties. 

Mixtures of herbicides could be used where they provide more effective control, particularly 

for weeds that may have developed resistance to a particular chemical, but this is expected to 

Final Environmental Impact Statement – Invasive Plant Control Project 37
Chapter 2 • Alternatives, Including the Proposed Action

be a rare case on the two forests, given the weed species present and size of the populations. 

Repeated use of the same herbicide can result in weed resistance. This problem would be 

minimized by using herbicides in rotation and with different modes of action (Whitson 2000). 

Only herbicide formulations (products) that have been registered with the Environmental 

Protection Agency (EPA) for rangeland, forest land, or aquatic use would be applied. In 

addition, the Forest Service has completed risk assessments that have analyzed the risk of 

specific herbicides on human health and safety, on wildlife/fish, and on nontarget plants. Only 

herbicides with a completed risk assessment would be used. Herbicide mixtures may only be 

used when they have been registered with the EPA for the particular formulation. The 

products that include mixtures must have also been considered in Forest Service risk 

assessment reviews. These products would be selected to be the most effective for a given 

weed species that has the lowest risk. For example, those herbicide formulations determined 

to be lowest risk at effective application rates would be used in areas where people live, work,

or recreate, while products with higher risk ratings might be used in more remote locations.

See “Mitigation Measures” for more detail.

No aerial application of herbicides would be used for this project. Herbicides would be 

applied using ground-based methods such as: hand application using a glove, rag or wick to 

wipe the chemical onto the weed while preventing it from getting on nontarget vegetation or 

other resources; spray using a backpack containing the herbicide attached to a flexible 

sprayer, wand or other hand application device that directs the chemical onto the target weed. 

Vehicles may be used with a mounted herbicide tank and boom or wand spray device to direct 

the spray, provided that the conditions described in the mitigation measures can be met for 

each respective herbicide used. Booms or wands may be articulated or fixed. All these 

methods have turnoff capabilities in or near the operator’s hand. Herbicides (such as 

hexazinone) may also be applied in granular or pellet form.

Where the objective for a given population is eradication and the target weed species has 

developed a large seedbed, herbicide applications usually require a followup treatment, either 

as a second herbicide application or using another method. Because the herbicides proposed 

for use do not persist in the soil at effective levels for more than a few months (at the 

maximum), in many invasive plant populations with seedbeds established, the followup

treatments are needed to eliminate new sprouts that were in seed during the initial treatment.

Biological Methods 

Biological control methods include release of insects or plant pathogens 

that are proven natural control agents of specific weed species. The insect 

or plant pathogen would attack, weaken, and kill a targeted weed species 

and reduce its competitive or reproductive capacity. Biological controls 

would be used for reducing population densities and rates of spread 

(when the objective is containment), as they are not effective for eradicating or substantially 

controlling weeds. This treatment is most effective on dense infestations of a weed species 

covering large areas. It could take 10 to 20 years for some biological treatments to be 

effective (USDA FS 1999a). Other limitations in the use of biological controls include: weeds 

continue to spread while the biological controls are becoming established; some weed species 

do not have biological controls; populations of biological controls can fail (leave an area or 

die); and a mix of different species of biological controls is often necessary to effectively 

treat a given weed site. 

38 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 2 • Alternatives, Including the Proposed Action

Most experts regard the introduction of biological controls as the best long-term solution 

where there are large, widespread populations of a specific noxious weed species that cannot 

be feasibly eradicated. The U.S. Department of Agriculture Animal and Plant Health 

Inspection Service (APHIS) rigorously screens and tests new biological agents for impacts on 

agricultural plants and on threatened, endangered, and sensitive plant species. It then prepares 

environmental assessments on the possible impacts of releasing those agents. Only APHISapproved and State-approved biological controls would be used on the Forests, and would be 

released according to APHIS requirements. 

Host-specific insects are proposed for use on some of the larger populations of riparian weeds 

like saltcedar, along with spotted knapweed (insects such as seed gall fly, root or seed head 

moth, flower or root boring weevil), and leafy spurge (e.g. flea beetles). In general, biological 

agents require an infestation large enough (more than 20 acres) to allow for the establishment 

of the controls to occur. For the Carson NF, weed infestations on adjacent lands could be 

added to the populations on National Forest System lands in order to make this treatment 

effective.

Manual Methods

Manual control methods involve hand pulling or digging with hand tools like 

shovels or hoes, or hand-operated power tools. It may also involve clipping or 

cutting off the tops of plants. If enough root mass is removed, the plant may 

be destroyed. Cutting plants reduces reproduction of plants by seeds. Cutting 

also depletes the carbohydrate reserves in roots, thereby weakening a plant’s 

competitive advantage on a site. This method would be most often applied to small 

populations (less than an acre) of herbaceous weeds that spread primarily by seeds rather than 

through root sprouts.

Controlled Grazing

Grazing with goats or sheep has been shown to suppress weeds in some 

prolonged applications (Shelley 1999). Goats have a digestive system that can 

handle most vegetation including weeds. Goats have been used on a limited 

basis in efforts to control weeds, using hay, water, or minerals to attract them to 

the weed patch. Other methods include herding and fencing to confine the 

goats/sheep within a specific area. For example, sheep can be induced to eat leafy spurge, 

which is toxic to cattle but not to sheep or goats. Sheep are known to suppress leafy spurge 

populations, but usually do not eradicate this weed. Most available information is anecdotal, 

but there are research projects currently in progress that will add to the scientific base. Herds 

of goats also trample and fertilize the treated areas, which in certain instances assists in 

revegetation efforts. The popularity of this method of weed control has been growing in the 

Western States in recent years, and the knowledge base of its effectiveness is also growing. 

Management considerations should include the fact that sheep and goats will not typically 

graze the target weed species to the exclusion of native plants. Another consideration is that 

weed seeds may adhere to the coats of long-haired breeds of goats, or the fleece of sheep, 

which could contribute to the spread of weed seeds if not addressed in the application of the 

method (i.e. require animals to be sheared prior to entering an infestation). Animals should be 

confined to a restricted area for an appropriate length of time after moving from an infested 

Final Environmental Impact Statement – Invasive Plant Control Project 39
Chapter 2 • Alternatives, Including the Proposed Action

area when there is a concern that viable weed seeds may be spread through the animals’ feces. 

Goats appear to effectively reduce the viability of seed moving through their digestive tract, 

due to the very small opening between the rumen and the small intestine.

This method may be used to reduce the vigor of some weeds where numerous, repeat 

treatments can be applied at the appropriate times. The availability of herds managed for this 

type of control may be limiting. This method is primarily proposed as a minor, incidental 

treatment method, and would be evaluated for effectiveness. Where appropriate, grazing 

would be integrated with other treatment methods to achieve more effective weed control. 

This weed control method would be conducted in accordance with Forest Service grazing 

regulations and regional policy. A site-specific project operation plan would be developed for 

the treatment area that would consider factors such as target weed species, type of livestock to 

be used, forage preference, planned grazing intensity, herding characteristics, topography, 

water availability, season of use, and a monitoring program. Forest Service regulations, 

policies, and the appropriate mitigation measures would be followed.

Mechanical

Mechanical control methods include actions such as mowing or root tilling. 

Mowing cuts plants off above ground while root tilling digs into the soil to 

unearth the roots. These methods employ large mechanized equipment such as 

tractors with specially designed attachments. These methods have not been 

demonstrated to be effective in eradicating or substantially reducing weed 

infestations, and typically require frequent repeat treatments. They do reduce 

plant and root vigor. Feasibility is also quite limited on the Forests due to the steep slopes and 

other common terrain features such as trees, boulders or logs. Thus, this method is only 

proposed for minor, incidental use, mainly along highways in conjunction with ongoing road 

maintenance actions. Most mechanical treatment is proposed in combination with another 

method.

Prescribed Burning 

Burning is similar to plowing or cutting the tops of weeds. It removes the seed 

heads and for some plants can reduce the seeds bank in soil. Broadcast burning 

weeds on the soil surface may be employed if there are sufficient fuels to carry 

a fire, or use of propone torches may be used on weeds where a surface fire 

would not carry through the weed population. Generally burning is not highly 

effective when used alone to eradicate or control most weed populations. Thus, it would 

typically be used in combination with other methods. 

Cultural Methods

Cultural methods are actions such as planting or seeding with desirable native plants immediately 

following a weed control treatment or other methods that allow desirable plants to out-compete 

the weed species. These methods are not proposed to be used alone to eradicate or control weed 

populations, but would be used where needed on treated sites as a followup method to favor 

native species and minimize subsequent weed infestation. This method would also be used where 

necessary to minimize soil erosion or stream sedimentation where needed following removal of 

weed species and exposure of bare soil.

40 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 2 • Alternatives, Including the Proposed Action

Table 6 summarizes treatment methods and acres for Alternative B. Acres shown are for the weed 

populations treated. The table shows some underestimation of treatment acres for weed sites 

where more than one method would be used to treat the same site. However, for some sites 

treated with multiple methods, the different methods would be applied on different portions of the 

site. On the other hand, the table shows some overestimation of treatment acres where the weeds 

are scattered among nontarget native plants or bare ground that would not be treated. Overall for 

the Forests, the table provides a rough estimation of weed treatment acres by method.

Table 6. Alternative B Treatment Summary

Treatment Population

Acres

Percent

Total

Biological-grazing 35 0.46%

Biological 135 1.83%

Biological in Jemez RD1 1,770 22.81%

Prescribed fire 82 1.13%

Grazing-herbicides 37 0.54%

Herbicide 3,508 48.27%

Manual 43 1.60%

Manual-grazing 90 1.21%

Manual-herbicide 1,485 19.33%

Mechanical 24 0.31%

Mechanical-biological-grazing 14 0.19%

Mechanical-herbicide 122 1.78%

Total 7,345

1 Area along the Jemez River, Santa Fe National Forest would add biological agents to already approved methods.

Alternative C: No Herbicides

This alternative involves conducting weed treatments over the same acres as Alternative B, except 

no herbicides would be used. Based on expected funding, each forest anticipates treating 150 to 

400 acres annually, with an annual maximum of approximately 1,000 acres per forest, during the 

next 10 years. This alternative treats fewer acres per year due to the need for more repeat 

treatments on the same sites in order to achieve some level of weed control or eradication. 

Otherwise, this alternative includes the same adaptive strategy as Alternative B.

Figure 4 shows the general locations where treatments would occur on known populations. 

Appendix 7 lists more details regarding Alternative C treatments, including the known weed 

species, treatment method(s), locations and acreages. 

Table 7 summarizes treatment acres by method for Alternative C. It includes the same over- and 

underestimations of treatment acres as described for Alternative B. 

Table 7. Alternative C Treatment Summary

Treatment Population

Acres

Percent

Total

Biological-grazing 34 0.46%

Final Environmental Impact Statement – Invasive Plant Control Project 41
Chapter 2 • Alternatives, Including the Proposed Action

Treatment Population

Acres

Percent

Total

Biological 255 3.46%

Biological in Jemez RD1 1,770 22.81%

Prescribed fire 2,048 27.62%

Prescribed fire-mechanical 82 1.13%

Grazing-mechanical 40 0.54%

Manual 1,541 20.93%

Manual-grazing 127 1.21%

Manual-mechanical 190 2.59%

Mechanical 1,283 18.99%

Mechanical-biological-grazing 16 0.19%

Total 7,345

1 Area along the Jemez River, Santa Fe NF would add biological agents to already approved methods.

Alternative D: Herbicides Only

This alternative would conduct weed treatments with herbicides only, over the same acres as 

Alternatives B and C except it eliminates the 1,690 acres of biological control treatments for the 

Jemez River/Rio Guadalupe riparian areas as they are currently undergoing authorized weed 

control with herbicides and other methods. Like Alternative B, each forest anticipates treating 300 

to 800 acres annually, with an annual maximum of approximately 1,500 acres per forest. This 

alternative involves use of the same herbicide application methods, same type of EPA-approved 

herbicides, etc. as was described for Alternative B. It also includes the same proposed Forest Plan 

amendment as Alternative B.

Table 8 summarizes treatment acres by method for Alternative D. Figure 5 shows general 

treatment locations for Alternative D. 

Table 8. Alternative D Treatment Summary

Treatment Population

Acres

Percent

Total

Herbicide1. 5,435 100%

Total 5,435

1 Area along the Jemez River, Santa Fe National Forest is under a decision to use herbicide treatments, and so would not 

be part of the “Herbicides-only” alternative.

Adaptive Strategy—All Alternatives

All alternatives would employ an adaptive strategy that has been determined to be necessary for 

the success of weed control projects and consistent with Forest Service policy (USDA-FS 2001b). 

As part of this adaptive strategy, weed treatments must be monitored, evaluated and modified as 

necessary to improve effectiveness of future treatments while reducing the potential for adverse 

effects to people and natural resources. This strategy allows for adopting findings from research 

studies on different practices or impacts, or changes in land or resource conditions. 

42 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 2 • Alternatives, Including the Proposed Action

Alternative C would employ this strategy, but would not include herbicides as a method in the 

array of tools. Alternative D also employs this strategy, but would still only use herbicides. Under 

Alternative D, adaptive management would be used to determine the effectiveness of herbicide 

applications (type of herbicide, application methods, timing, etc.). In all alternatives, the adaptive 

strategy would be key to finding and treating infestations that are not currently identified.

The adaptive strategy provides for flexibility to use the appropriate treatment method, based on 

the results of monitoring and evaluation. For Alternative B, the adaptive strategy would allow for 

any of the integrated weed control methods to be used on a given site. For example, if a few new 

weed plants are found on the roadside, this strategy would allow for the use of manual methods to 

dig them out. If monitoring indicates that weed control with herbicides would be just as effective 

with less impact on nontarget species with lower application rates, the lower application rates 

could be used. Another example would be that if monitoring reveals undesirable nontarget 

impacts on forbs from spring herbicide applications, herbicides might instead be applied during 

summer or fall if they are also effective on the target species. 

The adaptive strategy would cover weeds found in additional locations as well as new species 

found on the Forests. The Forests propose an adaptive strategy with the following actions: 

• Annually inventory portions of the Forests that are likely to have new infestations (e.g. 

areas burned by wildfires) and map any new weed infestations. Budgets will govern the 

extent of these inventories.

• Identify the weed treatment objective, priority and methods to use for newly mapped 

infestations based on the specific criteria described later in this section.

• Monitor the effectiveness and effects of weed treatment activities and associated 

mitigation measures.

• Evaluate and disclose monitoring results, and use those results to determine appropriate 

modifications in treatment prescriptions, mitigation measures, or implementation 

practices.

• New information (as described in Table 9) would supplement the EIS.

• Implement modifications or other feasible and appropriate treatment methods based on 

monitoring results, as long as the new or modified action and its effects are considered by 

an interdisciplinary team and determined by the responsible official to be within the 

scope of actions and effects evaluated in this FEIS (and in accordance with Forest Service 

Handbook FSH 1909.15 §18). 

Treatment Objectives, Priorities and Decision Criteria

Treatment objectives for a given weed species fall into one of the following three categories:

• Eradication (elimination)

• Control (reducing the population over time)

• Containment (preventing the population from spreading)

Eradicating or controlling every weed infestation at the same time is beyond the budget and 

personnel resources of the two forests. Eradication would be the objective applied to first priority 

species or situations, followed by control for second priority situations, and containment for third 

priority. Therefore, a system for setting priorities is proposed so that treatment concentrates on 

Final Environmental Impact Statement – Invasive Plant Control Project 43
Chapter 2 • Alternatives, Including the Proposed Action

species that have the greatest impact on the resource base, and those that become more difficult to 

control if action is delayed. Most weeds become much more difficult to control once they have 

spread.

Thus, the highest priority is to eradicate new species occurrences on the Forests, and then to keep 

existing populations from spreading or increasing in size. 

Weed species of limited extent are eradicated or controlled. Because the size threshold varies by 

weed species, this determination would need to be made based on site-specific conditions. 

Extremely widespread and common weeds are much more difficult to control, and so they are 

generally scheduled to “contain” as a Priority 3 species.

Treatment objectives and priorities are interconnected, and would be based on the following 

criteria, which is consistent with New Mexico’s weed control laws and procedures. 

Priority 1—Eradicate New Populations of High-Threat Species

This priority immediately eradicates new populations of species that pose a high threat to 

resources. Eliminating these populations while they are small creates the best opportunity to 

avoid impacts from these species. Eradication includes all viable seeds and vegetative 

propagules. High-threat species are those that can rapidly expand into native habitats and 

displace native vegetation throughout the Forests in a relatively short period of time. 

Eradicate all infestations of Class A weeds, which are those species exotic to New Mexico, 

but threatening to invade the State. Examples include black henbane, leafy spurge, and 

toadflax. They have limited distribution on the Forests (e.g. yellow toadflax), but if they 

become widespread, they pose a threat to agriculture crops, rangelands, plants listed as 

endangered, threatened or sensitive and other resources in the State.

Priority 2—Control Existing Populations of High-Threat Species

This priority gradually reduces existing populations of high-threat species. Control is 

accomplished by preventing seed production throughout the target area, decreasing the area 

coverage of the weed over time, and preventing the weed from dominating the area’s 

vegetation. This priority strives to achieve low levels of the weed populations if eradication is 

not feasible. For Class B weeds, this priority would decrease the population size and 

eventually eliminate this class of weeds, which are exotic (NMDA 1999) and of limited 

distribution in the Forests but are common in other parts of the State and so likely to appear. 

As a general rule, the objective would be to substantially reduce Class B weed infestations. 

For populations of 5 to 25 acres in size this means reducing the size by about 75 to 100 

percent. For Class B weed infestations greater than 25 acres in size, this means reducing the 

size by 50 percent. Examples of Class B weeds include bull thistle and musk thistle. 

Priority 3—Contain Existing Populations of High-Threat Species

This priority holds existing populations of aggressive weeds in check, so that they do not 

increase from their current size. Containing populations is accomplished by preventing weeds 

from expanding beyond the perimeter of the infestation, perhaps providing only limited 

treatment within the infestation, and treating to eradicate or control the weed outside the 

perimeter of the infestation. This priority would contain the spread of Class B weeds that are 

of limited distribution on the Forest (e.g. poison hemlock). For Class C weeds, which are 

widespread throughout the State and Forests, contain them to their present population size, or 

44 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 2 • Alternatives, Including the Proposed Action

for populations greater than 5 acres in size, strive to reduce by 50 percent. Examples include 

saltcedar, Russian olive, and Siberian elm.

Priority 4—Eradicate New Populations of Moderate-Threat Species

This priory eradicates new populations of less aggressive weeds. This priority immediately 

treats these new populations to eradicate them early, although they are not as high a priority 

as Priority 1 weeds. These populations expand into native habitats more slowly and/or are 

less successful than Priority 1 weeds in displacing native plants.

Priority 5—Control Existing Populations of Moderate-Threat Species

This priority gradually reduces existing populations of less aggressive weeds.

Priority 6—Contain Existing Populations of Moderate-Threat Species

This priority holds in place existing populations of less aggressive weeds.

Additional Criteria for Prioritizing and 

Determining Objectives and Methods 

In addition, weed infestations found in the following locations would likely be given an elevated 

priority ranking:

• Areas that are now relatively weed free and have little or no road access, such as areas 

designated as wilderness, roadless recreation or semiprimitive, nonmotorized, including 

the road corridors and trails that lead to those areas;

• Areas that are now relatively weed free that provide unique and desirable wildlife habitat, 

such as recovery habitat for threatened or endangered species, deer and elk winter range; 

and riparian habitat;

• Areas on the Forests with weed populations adjacent to other land ownerships where land 

managers have active weed control programs; and

• Areas of high human use, including but not limited to administrative sites, developed 

recreation sites such as campgrounds, scenic viewpoints, interpretive sites, and trailheads.

Schedules for implementing weed treatments would be based first on the priorities just described, 

and spread out over time based on levels of funding and staffing on the Forests.

Selection of treatment method is based to a large extent on the priority of the weed species and 

associated objective, along with site-specific factors such as proximity to water or roads (which 

increases chance of spread), and the size of the weed infestation (small sizes are easier to 

eradicate).

For example, a Priority 1 weed species (spotted knapweed) is found in a site that suggests 

eradication is the objective (it lays along a major highway). The size of the infestation is more 

than can be hand pulled (more than 2 acres). Therefore, an herbicide would be selected because 

that is the only method known to be highly effective and economically feasible for this weed 

population.

In addition to using treatment objectives, priority rankings, and infestation size, additional criteria

that would be used in selecting the most appropriate treatment method under the adaptive strategy 

is shown in Table 9.

Final Environmental Impact Statement – Invasive Plant Control Project 45
Chapter 2 • Alternatives, Including the Proposed Action

Table 9. Additional Treatment Criteria and Limitations

Weed Site Conditions Treatment Method Limitations

Area of high human use 

such as a recreation site, 

administrative site or area 

where people often collect 

plants.

Method(s) must have been documented to be low risk of causing 

harm to people. Examples include nonherbicide methods with 

lowest risk (e.g. those that avoid burning) or herbicide

formulations/application methods having the lowest risk of 

harmful effects to humans (for example, glyphosate, imazapyr, 

imazapic, metsulfuron methyl, clopyralid products would be 

available for use per risk assessment results found in Appendix 3). 

Also adhere to other mitigation measures that apply to protection 

of human health and safety (e.g. notification).

Area where there is a 

shallow water table (≤ 6 

feet deep) and soil with a 

high permeability rate, 

where there may be a risk of 

an herbicide leaching 

through the soil to the 

ground water.

Nonherbicide method(s) appropriate for the site conditions

(manual pulling or mowing), or an herbicide appropriately labeled 

for use in these locations (e.g. short-lived, nonleachable herbicides 

such as glyphosate, imazapic, imazapyr, metsulfuron methyl, 

clopyralid, chlorsulfuron) that has been registered by the EPA for 

use on permeable soils with shallow water tables. Herbicides that 

use picloram as their active ingredient (e.g. Tordon 22K) would 

not be used in these situations per risk assessment results). Also 

adhere to mitigation measures that apply to protection of soil and 

ground water resources.

In riparian areas or next to 

live water bodies containing 

aquatic species.

Method(s) determined and documented to have low risk to fish or 

other aquatic species. Examples include a nonherbicide method

(e.g. mowing) that avoids erosion/sediment production or 

herbicides registered by the EPA for aquatic habitats (e.g. 

chlorsulfuron, glyphosate formulations such as Rodeo (which does 

not use the surfactant POEA), imazapic, imazapyr). Also adhere to 

mitigation measures that apply to protection of riparian, water and 

aquatic resources.

Threatened, endangered or 

sensitive plant species are 

present.

Method(s) determined and documented to have low risk to native 

plant species, such as nonherbicide methods (hand pulling) with 

appropriate disturbance controls. Herbicide applications include

spot treatment (by hand or backpack spray) that avoid vehicle 

boom spray application of herbicides such as imazapyr, imazapic 

clopyralid, chlorsulfuron, because they have high potential to 

affect nontarget plants up to several hundred feet away. 

Herbicides, if used from boom spray, could be used if similar risk 

ratings to 2,4-D, which has low risk of impact beyond 25 feet of 

drift. For Holy Ghost ipomopsis, see specific mitigation measures

later in this section. Adhere to mitigation measures that apply to 

protection of threatened, endangered or sensitive plant species, 

including limitations on herbicide spraying from vehicles.

46 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 2 • Alternatives, Including the Proposed Action

Weed Site Conditions Treatment Method Limitations

Occupied threatened, 

endangered or sensitive 

wildlife species habitat.

Method(s) used must have been determined to have low risk to 

wildlife species. These methods include nonherbicide methods at 

the proper timing (e.g. burning outside seasonal restrictions). 

Herbicide applications must be shown to be below the level of 

concern through specific risk assessment for the herbicide used

when applied in these habitats (See Appendix 3). No direct 

application of herbicides to water would be permitted under the 

adaptive strategy even where formulations are registered for such 

use (e.g. AquaKleen formulation of 2,4-D). This restriction is 

imposed because of possible effects of direct application to Rio 

Grande cutthroat trout. Also adhere to other mitigation measures 

that apply to protection of threatened, endangered or sensitive 

wildlife species.

Wilderness and designated 

nonmotorized areas.

Motorized vehicles and mechanized equipment are prohibited in 

all wilderness areas. In the Pecos Wilderness, sheep or goat 

grazing for weed control would be prohibited by an existing 

closure order. In other locations of Rocky Mountain bighorn sheep 

habitat, controlled grazing for weed control would also be 

prohibited. See mitigation measures.

Mitigation Measures and Monitoring Requirements

Table 10 lists mitigation measures and monitoring requirements for all action alternatives, 

including best management practices (BMPs) for minimizing the risk of water pollution in 

accordance with Clean Water Act regulations. The mitigations were developed specifically for 

this project in order to avoid or minimize the risk of adverse project-related impacts to people or 

natural resources on the Forests, including potential impacts to human health and safety, native 

plants, special status plants or wildlife, soil, water, riparian and aquatic resources, and heritage 

resources. The table shows which alternatives each requirement applies to.

Table 10. Mitigation Measures and Monitoring Requirements for All Alternatives

Description of Mitigation Measure/Monitoring Alternatives

HUMAN HEALTH/SAFETY and GENERAL MITIGATIONS

Herbicide formulations (specific products including mixtures) will not be used 

unless they have been registered for use by the EPA and all EPA label 

requirements (including limitations) are strictly followed. Only herbicides with a 

completed risk assessment per Forest Service standards would be used.

B, D

In areas of human habitation or high use such as a recreation site, administrative 

site or area where people often collect plants, the treatment method must have low 

risk of harmful effects to humans. Examples include nonherbicide methods 

(manual/mechanical/grazing) or herbicides rated as having the lowest risk of 

harmful effects to humans (See Appendix 3).

B, D

Final Environmental Impact Statement – Invasive Plant Control Project 47
Chapter 2 • Alternatives, Including the Proposed Action

Description of Mitigation Measure/Monitoring Alternatives

Herbicide application will strictly adhere to EPA label instructions regarding 

temperature, humidity, wind speed and other weather variables, to avoid spray 

drift to nontarget plants or other resources while increasing treatment 

effectiveness.

B, D

Herbicide use will be restricted to EPA registered application rates (usually in 

terms of pound per acre of active ingredient applied) and conditions listed on the 

label. Followup application of a second herbicide to an area should be conducted 

only after reviewing best available information on compatibility with the previous 

application’s formulation.

B, D

Herbicides may only be applied by a trained applicator under supervision of a 

licensed applicator, in accordance with Forest Service directives. 

B, D

Herbicide use will comply with the direction contained in Chapter 2150 of FSM 

2100 - Environmental Management (USDA FS 1998a), including the requirement 

that a Pesticide Use Proposal (form FS-2100-2) be completed for all proposed 

pesticide (i.e. herbicide) uses on National Forest System lands.

B, D

Herbicide applicators will have the chemical spill plan and emergency cleanup kit 

onsite during treatments. The spill plan identifies methods to avoid accidental 

spills as well as how to report and clean up spills. The kit will contain appropriate 

spill cleanup supplies. (See Appendix 6)

B, D

Workers handling herbicides will be required to wear protective clothing, 

including long-sleeved shirt and long pants to reduce worker doses. For herbicides 

containing hexazinone, respiratory protection would also be required per label 

direction. Clothes should be cleaned daily. Workers will also wear waterproofed 

boots, gloves, and other safety clothing and equipment listed on the herbicide 

label. Workers mixing or loading herbicides will be required to wear eye 

protection (goggles or eye shields) and Tyvek suits or herbicide resistant aprons.

B, D

A pesticide application record (PAR) will be completed on a daily basis for each 

project area detailing the herbicide application, treatment area, target species 

distribution and density, weather conditions, and recommendations for followup

treatments or rehabilitation.

B, D

The Forests will provide public information about weed treatments using 

herbicides, including herbicide to be used, locations, application schedules, etc. 

This information will be posted on the Forest’s Internet Web sites and mailed to 

those who request it.

B, D

To further notify forest visitors and users, signs regarding herbicide use will be 

placed at access points to treatment areas prior to herbicide application. Signs will 

include the herbicide to be used, effective dates, and phone number for acquiring 

more information. 

B, D

Traffic control and signing during weed treatment operations will be used as 

necessary to ensure safety of workers and the public. Recreation sites, roads, trails 

or other areas scheduled for treatment may be temporarily closed during weed 

treatment activities to ensure public safety. 

B, C, D

48 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 2 • Alternatives, Including the Proposed Action

Description of Mitigation Measure/Monitoring Alternatives

Weed treatments will be coordinated with potentially affected adjacent landowners 

and range allotment permittees. Cooperative efforts on adjacent lands and range 

allotments would increase treatment effectiveness and the ability to meet weed 

control objectives.

B, C, D

NATIVE VEGETATION and TREATMENT EFFECTIVENES

Weed treatments will only be applied where weeds actually exist, not on areas 

with a potential for weed infestations.

B, C, D

Vehicles used for weed treatments will be properly cleaned prior to entering 

National Forest System lands and again before leaving the treated area to avoid 

further spread of weeds.

B, C, D

Where treatments result in exposing bare mineral soil, those sites will be evaluated 

to determine the need for revegetation (seeding, planting), mulching, or other 

erosion or sediment control measures. The evaluation would consider the potential 

for subsequent re-invasion by weed species, potential for erosion, water runoff, 

and/or stream sedimentation. Where seeding is used, certified “weed-free” seed 

will be required. Seed mixes will be based on site-specific conditions and 

objectives. 

B, C, D

Herbicides will not be applied if snow or ice covers the target weed plants, to 

avoid runoff into soil and onto nontarget vegetation.

B, D

After treatment, livestock grazing will be deferred where needed to achieve weed 

treatment objectives, based on site-specific conditions. This will be accomplished 

by working with permittees and adjusting their annual operating instructions as 

necessary. 

B, C, D

Biological agents will not be released until screened for host plant specificity and 

approved by the USDA Animal Plant Health Inspection Service and New Mexico 

Department of Agriculture.

B, C

All weeds that are mechanically or hand excavated after flower bud stage will be 

double bagged and properly disposed of at an approved facility (e.g. covered 

landfill).

B, C

Use of prescribed fire must adhere to restrictions contained in the Forest Plan and 

Agency directives, such as those for using fire within wilderness (FS Manuals 

2324.2 and 2324.04(b)), requirements for detailed burn prescriptions, and other 

requirements intended to avoid unexpected consequences.

B, C

THREATENED, ENDANGERED (T&E) and SENSITIVE PLANTS

If herbicides are to be sprayed within potential habitat for any T, E or S plant 

species, a survey of that habitat will be conducted if possible. If no survey is 

conducted, the potential habitat will be treated as if occupied by the T, E or S 

plant, and the mitigation that follows (for occupied habitats) applies. 

B, D

A 50-foot buffer applies to any prescribed fire or mowing within the habitat for the 

Holy Ghost ipomopsis.

B, C

Controlled grazing by goats will not be used within the habitat for the Holy Ghost 

ipomopsis.

B, C

Final Environmental Impact Statement – Invasive Plant Control Project 49
Chapter 2 • Alternatives, Including the Proposed Action

Description of Mitigation Measure/Monitoring Alternatives

Within the known population of Holy Ghost ipomopsis, herbicides will not be 

applied.

B, D

For other plants (sensitive) there will be no spraying of herbicides from vehicles 

(boom spray) within 25 feet of any occupied T, E or S plant species habitat if the 

herbicide formulation is low risk (e.g. 2,4-D). For herbicides that have a large area 

of potential impact if drift occurs (e.g. clopyralid), boom spray must be avoided or 

a larger (1,000-foot) buffer must be used. Within a sensitive plant population, 

herbicide formulations must be chosen that have low risk of migration through 

roots, and then must be applied by hand to individual weeds (e.g. wand from 

backpack sprayer, or on gloves, wicks, rags). (See Appendix 3).

B, D

No herbicides would be applied within the 200 acres of occupied Holy Ghost 

ipmopsis habitat. Controlled grazing (by goats) would be used within the occupied 

habitat.

B, C, D

Controlled grazing, mowing and prescribed burning will not occur within 50 feet 

of Holy Ghost ipomopsis or other Federally listed plant species.

B, C

Design ground-disturbing activities (tilling, pulling, digging, etc.) to avoid 

trampling or other direct impacts to individual Holy Ghost ipomopsis or other T, E 

or S plant species. The risk of this occurring will be prevented or reduced by the 

required presence of a Forest Service biologist or other qualified person who can 

identify the plant during any treatment activity in the occupied habitat.

B, C

Before implementing any weed control work in the occupied Holy Ghost 

ipomopsis habitat, the forest or district will coordinate with the New Mexico 

Environment Department and the U.S. Fish and Wildlife Service to use the most 

current survey information. 

B, C, D

WILDLIFE, including T & E and SENSITIVE SPECIES

In general, for treatment areas exceeding 1 acre in size within T&E species 

wildlife habitat, conduct surveys for the species prior to implementation, if 

feasible. If surveys are not feasible prior to implementation, that area will be 

treated as if occupied. Within “occupied” T&E species habitats, avoid loud, 

persistent noise disturbance or modifications of breeding habitat features. If a 

potentially adverse effect cannot be avoided, develop a supplemental biological 

assessment and consult with USFWS to determine the appropriate mitigation 

measures. 

B, C, D

For “occupied” Mexican spotted owl and Southwestern willow flycatcher habitat,

implement applicable breeding season restrictions as specified in forest plans and 

recovery plans for those species.

B, C, D

If bald eagle may be in an area proposed for treatment during the winter months 

(through March), a presence/absence survey must occur within a 0.5 mile radius of 

the work site before activity starts and following any breaks. If an eagle is present 

within the 0.5 mile radius, work must be suspended until the bird leaves of its own 

volition or if a Forest Service biologist in consultation with the USFWS, 

determines that the potential for harassment is minimal. If bald eagles nest on 

National Forest System land in proximity to areas planned for invasive plant 

treatment, the U.S. Fish and Wildlife Service will be contacted to determine if 

further consultation is needed.

B, C, D

50 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 2 • Alternatives, Including the Proposed Action

Description of Mitigation Measure/Monitoring Alternatives

For treatment units that are located within known Southwestern willow flycatcher 

habitat (Carson National Forest), the following measures apply: Survey to 

protocol before any treatment if the timing of the treatment coincides with dates 

the birds are likely to be in the area. If the flycatcher is found, no treatments can 

occur. If no flycatcher is found, treatment would proceed. 

B, C, D

No prescribed burns will be done within Mexican spotted owl PACs. B, C

For other “occupied” sensitive wildlife species habitat where individuals in the 

population may be negatively impacted, consult with the forest biologist and apply 

mitigation measures that minimize those negative impacts to individuals while 

continuing to maintain population viability and avoid a trend toward Federal 

listing.

B, C, D

Herbicide applications will be limited to those herbicides and application 

rates/methods documented to have a low risk to wildlife species.

B, D

In areas with bighorn sheep populations (high country/wilderness), controlled 

grazing with sheep or goats will be prohibited.

B, C

In Jemez Mountain salamander areas, no treatment would occur during the season 

when salamander are above ground. This is during late summer monsoon season. 

Rain for 5 consecutive days will be used as a measure to delay treatment until land 

surface conditions have dried. Areas to protect in this way will follow the 

cooperative management plan.

B, C, D

No herbicide treatment will occur within 50 feet of streams that are known to be 

occupied by Rio Grande cutthroat trout between June 1 and June 30 (spawning

season).

AIR, SOIL, WATER, RIPARIAN and AQUATIC RESOURCES

All prescribed burning must comply with the New Mexico smoke management 

requirements (permitting, monitoring, etc.) to maintain levels of these emissions 

within State and Federal air quality standards.

B, C

Heavy mechanized equipment such as tractors with tillers or mowers will not be 

used on slopes over 40 percent, to minimize erosion potential. 

B, C

Heavy equipment will not be used to mechanically dig up weeds within riparian 

zones unless a Forest Service soil, water or fisheries specialist examines the sitespecific conditions and determines that there would be no adverse impacts to water 

quality, stream morphology or aquatic resources.

B, C

Herbicide treatment areas that may be near water or have a high water table will be 

field checked to verify GIS data. If applying herbicides within 25 feet of a water 

body, or within a riparian area or other areas with a shallow water table, a shortlived, nonleachable herbicide that has been registered by the EPA for use on 

permeable soils, near water, or in areas having shallow water tables must be used 

(e.g. 2,4-D, glyphosate, triclopyr). Herbicides that use picloram as their active 

ingredient (e.g. Tordon 22K) will not be used in this situation.

B, D

Herbicide application within a riparian area or 50 feet of a water body is limited to 

hand application onto individual weed plants (using backpack spray wand, or 

glove, wick, or rag). 

B, D

Final Environmental Impact Statement – Invasive Plant Control Project 51
Chapter 2 • Alternatives, Including the Proposed Action

Description of Mitigation Measure/Monitoring Alternatives

Mixing and loading of herbicides will not occur within 200 feet of live water, and will 

adhere to the other mitigations measures listed in the chemical spill plan (see Appendix 6)

B, D

In riparian areas or next to live water bodies containing fish, methods used must 

have been documented to have low risk to aquatic species.

B, C, D

In riparian areas, prescribed burning will be incidental (e.g. pile burning slash from 

mechanical treatment of woody invasive species). No broadcast burning will be 

permitted.

B, C

HERITAGE RESOURCES

Adhere to the programmatic agreement developed for this project*, including 

requirements for conducting preimplementation heritage resource inventories and 

evaluations, consulting with the State Historic Preservation Office and tribes, 

applying appropriate mitigation measures to avoid adverse impacts, and 

monitoring treatment activities for effects to heritage resources. (Programmatic 

agreement is available in the project record.)

B, C, D

Herbicides applied from vehicles (e.g. trucks, off-road vehicles) will not occur 

within 25 feet of archeological remains consisting of perishable materials with 

analytic or information value, including wood, organic ceramic paints, datable 

materials, and residues on artifacts. Within 25 feet of such archeological remains, 

herbicides must be applied by hand to individual weeds (e.g. on gloves, wicks or 

rags) to avoid getting herbicides or carrier fluids onto those remains.

B, D

Adhere to the mitigations previously listed that minimize adverse impacts to 

nontarget native plants in order to reduce the risk to plants of ethnographic 

concern.

B, C, D

Notification of tribes and other traditional use groups will occur before herbicides 

are used to inform them of pending chemical treatment activities and schedules. 

This measure will reduce the risk to native plants used for traditional cultural 

purposes and the risk to the health of individuals who gather these plants.

B, C, D

Sheep or goat grazing will not be used on heritage resource sites easily damaged 

by trampling as identified through heritage resource inventories prior to 

implementation.

B, C

Avoid direct impacts to archeological sites by designing ground-disturbing 

activities to avoid archeological sites, and conduct archeological surveys for all 

ground-disturbing activities. Root tilling, mowing, hand pulling, digging or other 

weed treatments that disturb the soil, will be conducted in a manner that avoids 

heritage resource sites whenever possible. If avoidance is not possible, data 

recovery or another similar mitigation measure may be required. 

B, C

During prescribed burning, avoid perishable materials, conduct fuel assessments, 

and reduce fuels onsite without perishable materials, and develop prescriptions to 

ensure low temperature, low duration, low residence time and low intensity on 

sites to be burned.

B, C

MONITORING and ADAPTIVE MANAGEMENT

Weed inventories and mapping will be conducted annually, and treatment of newly 

found populations will be identified and prioritized based on criteria in the EIS.

B, C, D

52 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 2 • Alternatives, Including the Proposed Action

Description of Mitigation Measure/Monitoring Alternatives

Treated sites will be monitored and results evaluated (documented) to determine:

- Effectiveness of the method(s) used in meeting the objective;

- Whether impacts to resources or people were within the scope of EIS 

predictions; and 

- Implementation and effectiveness of mitigation measures, and whether 

mitigations should be modified or added to enhance effectiveness.

B, C, D

Changes in treatment prescriptions made as a result of monitoring and evaluation, 

and treatments prescribed for newly found weed populations must adhere to all 

mitigation and monitoring requirements in the EIS, and the actions and effects 

must be within the scope of those considered in the EIS. New information will be 

considered in accordance with FSH 1909.15, Sec. 18, to determine the need for 

additional environmental analysis under NEPA. The evaluation and decision by 

the responsible official regarding consistency with the EIS will be documented in 

the project record.

B, C, D

* Programmatic agreement between the USDA Forest Service, Carson and Santa Fe National Forests, USDA Forest 

Service Regional Office, and New Mexico State Historic Preservation Office, and other consulting parties, to comply 

with applicable portions of the National Historic Preservation Act, including Section 106 and its implementing 

regulations. 

Forest Plan Amendment

Alternatives B and D would require an amendment to the Santa Fe National Forest Plan in order 

to be approved as written. The current standards of the Forest Plan prohibit herbicide use within 

municipal watersheds, in areas of human habitation, on soils with low regeneration potential or 

less than moderate cation exchange capacity (USDA FS 1987). The amendment would relax these 

standards in order to allow herbicides to be used where necessary in those situations (while 

maintaining limitations listed in the “Mitigation” section of this document. The current Forest 

Plan also prohibits herbicide use if an environmental analysis shows that it is not 

“environmentally, economically or socially acceptable,” which is an ambiguous and 

nonquantifiable standard, subject to variable interpretations. The amendment would slightly 

modify that standard while continuing to focus on using the environmental analysis of 

environmental, economic and social impacts to determine the appropriateness of herbicide 

application. The specific language changes proposed for the amendment are italicized in Table 11. 

The need for the amendment is to help meet the purpose and need for this project. In order to 

achieve the desired ecological conditions described in the Forest Plan, including maintaining 

native vegetation and wildlife habitat quality, along with sustainable soil, water and riparian 

conditions that would otherwise be threatened by ineffective treatments and the continued spread 

of weeds, it may be necessary to have the flexibility to apply herbicides to weed populations that 

cannot be effectively treated with other methods. This could in some instances include herbicide 

applications within municipal watersheds, on National Forest System lands adjacent to human 

residences, and on some soils with a low revegetation potential or less than moderate cation 

exchange capacity. The amendment is made within the context of the mitigation measures and 

label instructions that apply to herbicide use, as well as the mitigation measure that requires 

sufficient ground cover to ensure that soil erosion does not exceed the tolerance level for that soil 

Final Environmental Impact Statement – Invasive Plant Control Project 53
Chapter 2 • Alternatives, Including the Proposed Action

type based on the Terrestrial Ecosystem Survey for the Santa Fe National Forest (USDA FS 

1993). This would ensure that long-term soil productivity would be maintained. In addition, the 

Forest Plan standard and guideline regarding cation exchange capacity is proposed for deletion 

because it is outdated. That particular soil measurement is not used by the Forest Service in the 

Southwestern Region. 

Table 11. Proposed Santa Fe National Forest Plan Amendment

Existing Forest Plan Direction 

(p.76) Proposed Forest Plan Direction

Chemical treatments may be 

applied:

- When determined through an 

environmental analysis to be 

environmentally, 

economically, and socially 

acceptable.

- On areas outside municipal 

watersheds and areas of 

human habitation.

- On soils with moderate or 

high revegetation potential.

Chemical treatments may be applied:

- When determined through an environmental analysis to 

have no long-term adverse environmental, economic, 

or social impacts.

- Within municipal watersheds only when the 

municipality concurs with the proposed treatment 

prescription and mitigation measures to be 

implemented. 

-On any soils provided that effective ground cover is 

quickly restored and soil erosion on that site is not 

reduced to below the tolerance level identified in the 

terrestrial ecosystem survey for the affected soil unit.

Permits and Authorizations Required

• Consult and obtain concurrence from the U.S. Fish and Wildlife Service on the Forest’s 

biological assessment and determinations of effects to threatened or endangered species. 

This will occur prior to signing a record of decision authorizing project implementation.

• Consult and obtain concurrence from the New Mexico State Historic Preservation Officer 

regarding identification, evaluation, and determination of effects of the project on 

heritage resources. Final consultation and concurrence from the State SHPO will occur 

prior to implementation, based on the programmatic agreement for this project that was 

approved by the New Mexico State Historic Preservation Officer. 

• Obtain concurrence from APHIS and the State of New Mexico for any biological control 

method to be used.

• Agency employees or contractors supervising application of herbicides must first be 

certified. Application must adhere to all other pre- and post-implementation requirements 

in FS Manuals 2080 and 2150 regarding weed management and coordination with other 

agencies.

• Following Forest Service policy and procedures, regional forester review and approval 

must be obtained before using herbicides in wilderness, and any other situations as 

directed.

• Comply with the New Mexico Pesticide Control Act governing public applicators, record 

keeping, etc.

• Prior to burning, a burn plan must be prepared and burn permit obtained from New 

Mexico Environmental Department Air Quality Bureau.

54 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 2 • Alternatives, Including the Proposed Action

Final Environmental Impact Statement – Invasive Plant Control Project 55
Chapter 2 • Alternatives, Including the Proposed Action

Figure 3. Alternative B

56 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 2 • Alternatives, Including the Proposed Action

Figure 4. Alternative C

Final Environmental Impact Statement – Invasive Plant Control Project 57
Chapter 2 • Alternatives, Including the Proposed Action

Figure 5. Alternative D

58 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 2 • Alternatives, Including the Proposed Action

Comparison of Alternatives

This section provides a comparative summary of the alternative treatments and effects of 

implementing each alternative. Information is focused on activities and effects where different 

levels of effects or outputs can be distinguished quantitatively or qualitatively among alternatives. 

Table 12 provides the comparison of alternatives based on the significant issues or effects as well 

as how well the alternatives meet the purpose and need (objectives) for the project. The 

comparison table is intended to provide the public and decision makers with a clear basis for 

choice between alternatives. 

Table 12. Comparison of Alternatives by Issues and Objectives (Purpose and Need)

Significant 

Issues and 

Objectives

Alternative A Alternative B Alternative C Alternative D

Issue 1: 

Herbicides 

and Human 

Health

No risk of 

health impacts 

from herbicide 

exposure 

(0 acres treated 

with 

herbicides).

Low risk of health 

impacts from using 

herbicides, to workers 

or general public, 

based on EPA 

registration, risk 

assessment analysis, 

and other mitigation 

measures. 

Higher risk to people 

with multiple 

chemical sensitivities, 

although public 

notification 

requirement provides 

a means for people 

with this condition to 

avoid exposure to 

treated areas.

Approx. 70 percent of 

treatments include 

herbicides (5,150 

acres).

No risk of health 

impacts from 

herbicide 

exposure (0 acres 

treated with 

herbicides).

Slightly increased 

risk of exposure 

to smoke from 

prescribed 

burning.

Same as Alt. B 

but slightly 

higher risk of 

exposure for 

people with 

chemical 

sensitivities as

100 percent of 

treatments 

include 

herbicides 

(5,435 acres).

Issue 2: 

Herbicides 

and Wildlife

No risk of 

herbicide 

impacts to 

wildlife. 

Weeds would 

degrade native 

plant habitats, 

especially 

riparian areas 

important to 

numerous 

species.

Low risk of herbicide 

impacts to wildlife 

based on EPA 

registration, risk 

assessments, and 

mitigation measures.

Native wildlife habitat 

quality (especially 

riparian habitat) would 

improve as weeds are 

eradicated and 

controlled.

No risk of 

herbicide impacts 

to wildlife.

Less 

improvement in 

wildlife habitat.

Same as Alt. B

Final Environmental Impact Statement – Invasive Plant Control Project 59
Chapter 2 • Alternatives, Including the Proposed Action

Significant 

Issues and 

Objectives

Alternative A Alternative B Alternative C Alternative D

Issue 3: 

Herbicides 

and Native 

Plant 

Communities

No short-term 

impacts from 

herbicides.

In the long 

term, weedcaused decline 

in abundance 

and diversity of 

native plant 

communities, 

especially 

native riparian 

plants.

Short-term reduction 

in some nontarget 

plant species.

Long-term 

improvement in 

abundance and 

diversity of native 

plant communities, 

especially riparian 

plants.

Similar to 

Alternative B for 

short-term 

reduction in 

nontarget plants.

Low to moderate 

long-term 

improvement in 

native plant 

communities. 

Weed spread rate 

may equal or 

exceed control 

rate without 

herbicide use.

Same as Alt. B

Issue 3: 

ContinuedRare or 

Sensitive 

Native Plant 

Species

No risk of 

treatmentrelated impacts. 

In the long 

term, weeds 

may cause a 

decline in 

federally listed 

or sensitive 

plant species

No impact to 

threatened or 

endangered plants due 

to mitigation measure. 

For sensitive plants, 

treatments “may 

impact individuals but 

are not likely to result 

in a trend toward 

Federal listing or loss 

of population 

viability,” due to 

mitigation measures 

and species locations.

Same as Alt. B Same as Alt. B

Issue 4: Cost 

and 

Treatment 

Effectiveness

(based on 

level of effort 

to meet 

objectives)

No cost 

effectiveness;

would incur 

much higher 

costs in future. 

Moderately cost 

effective; $1,313,000 

relative cost.

Least cost 

effective;

$1,585,000 

relative cost.

Most cost 

effective;

$550,000 

relative cost.

60 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 2 • Alternatives, Including the Proposed Action

Significant 

Issues and 

Objectives

Alternative A Alternative B Alternative C Alternative D

Objectives: 

Protect 

native plant 

communities, 

soil and 

water 

quality, 

wildlife 

habitat, and 

long-term 

ecosystem 

health

No protection; 

no 

effectiveness.

Weed-related 

impacts to 

vegetation, soil, 

water, riparian 

habitat, etc. 

would continue. 

Highest level of 

treatment 

effectiveness and 

resource protection 

from weed impacts 

due to combination of 

treatments including 

herbicides.

Lowest level of 

effectiveness and 

resource 

protection from 

weed impacts.

Fewer acres 

treated annually 

for a given 

budget due to 

need for repeat 

treatments on the 

same acreage

more often than 

when combined 

with other 

methods.

High level of 

effectiveness 

and resource 

protection from 

weed impacts.

Not quite as 

effective as 

herbicides 

combined with 

other methods.

In addition to the summarized comparison of alternatives related to significant issues and project 

objectives, there are a few other key differences between the effects of each alternative, based on 

the detailed effects analysis described in Chapter 3. The most noticeable consequences from weed 

treatment under Alternatives B, C, and D would be the long-term, beneficial improvements to 

native ground vegetation such as grasses, forbs and shrubs. Riparian vegetation such as rushes, 

sedges, willows and cottonwoods would particularly benefit from this project. Protecting and 

improving native plant communities would have positive effects on soil and water conditions, as 

well as wildlife and aquatic habitats (particularly due to enhancing riparian vegetation). 

Negative effects to native vegetation, soil, water and aquatic organisms would be very minor and 

of short duration. The increases in sediment (more with Alternative C) and herbicide delivery to 

streams (for Alternatives B and D) would have no measurable long-term consequences. There 

would be a low risk of adverse impacts to fisheries, including Rio Grande cutthroat trout (a 

sensitive fish species) or other aquatic organisms based on application of mitigation measures, 

risk assessment and EPA guidelines. Alternative C would cause more ground disturbance and 

associated impacts to soils, especially on soils with a severe erosion hazard rating. However, all 

alternatives would remain with soil erosion tolerance levels needed to protect long-term soil 

productivity. Soils with low revegetation potential would receive herbicide treatments in 

Alternatives B and D, while re-establishing native vegetation would take longer under Alternative 

C. Mitigation requirements for all alternatives would ensure that vegetative ground cover is 

adequately reestablished. With the required mitigation measures, all soil and water quality 

standards would be met. 

Differences between alternatives in their effects to air quality, heritage resources, livestock 

grazing, recreation, wilderness and visual resources were expected to be negligible, such that they 

would not be given weight in the decisionmaking process. There would be minor increases in 

noise and traffic associated with the action alternatives, although generally within background 

levels. 

Final Environmental Impact Statement – Invasive Plant Control Project 61
Chapter 2 • Alternatives, Including the Proposed Action

By controlling the spread of weeds and protecting native plant communities, habitats and 

watershed conditions on the Forests, Alternatives B and D would maintain or enhance social or

economic conditions, particularly for local rural communities in northern New Mexico who 

typically rely on the Forests’ natural resources for their livelihood, traditional culture and quality 

of life.

62 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment 

and Environmental Consequences

This chapter contains affected environment sections that summarize the physical, biological, 

social, and economic environments of the project area, as well as environmental consequences 

sections that describe the effects of implementing the proposed action and other alternatives. The 

environmental consequences focus on the project’s purpose and need as well as issues identified 

in Chapter 1, providing the scientific and analytical basis for the comparison of alternatives 

presented at the end of Chapter 2.

Specialists’ reports contained in the project record may contain more detailed information for the 

affected environment sections than what is contained in this document. The affected environment 

sections in this chapter provide succinct descriptions of affected resources commensurate with the 

relevance to and importance of the issues or impacts, in accordance with direction provided in 

NEPA implementing regulations at 40 CFR §1502.15.

An agency approved adaptive weed management strategy was incorporated into this proposed 

project to address uncertainties about new or undiscovered weed infestations as well as postimplementation monitoring results that may indicate a need to modify treatment methods in order 

to meet project objectives. In the context of this uncertainty, the effects described in this chapter 

include consideration of the adaptive strategy, including use of treatment method selection 

criteria, prioritization ratings, thresholds, limitations, mitigation measures, and monitoring 

requirements described in Chapter 2.

Cumulative Actions for Cumulative Effects Analysis

This section briefly discusses other activities and land uses occurring within and surrounding the 

project area that could contribute to cumulative effects when added to the effects of weed control 

treatments included in this project. Cumulative effects are those impacts on the environment that 

result from incremental impacts of the action when added to other past, present, and reasonably 

foreseeable future actions. While this section outlines these potentially cumulative actions used 

by the interdisciplinary team in their cumulative effects analysis, the actual analysis and 

estimations of cumulative effects for each affected resource is described in each separate resource 

section in this chapter.

The geographic extent for most resources for which cumulative effects have been evaluated 

consists of land administered by and immediately adjacent to the two forests, based on the area 

directly or indirectly affected by project activities. Project activities are anticipated to occur over 

approximately 10 years (or more), and would be well distributed spatially in localized weed 

infestation sites across the 3 million acres comprising the 2 forests.

The actions that would be expected to contribute most to potential cumulative effects are weed 

control actions being undertaken by other jurisdictions or on private lands in and around the 

Forests. However, other activities expected to occur on the Forests that affect similar resources 

are also included.

Past and present (ongoing) weed treatments on the Forests are:

• Manual control (hand digging rosettes and clipping seed heads) of thistles (musk, Scotch, 

and bull) on the Jicarilla, Questa, and Camino Real Ranger Districts, Carson National 

Final Environmental Impact Statement – Invasive Plant Control Project 63
Chapter 3 • Affected Environment and Environmental Consequences

Forest, and on the Espanola, Jemez, and Cuba Ranger Districts, Santa Fe National Forest. 

In fiscal year 2003, the Forests treated 238 acres.

• Herbicide, mechanical, and manual treatment of saltcedar, Siberian elm and Russian olive

in riparian areas on the Jemez Ranger District, Santa Fe National Forest.

• Goat grazing of yellow toadflax, Russian knapweed, and hoary cress within highway 

rights-of-way was used in 2002, just south of Tres Piedras, Carson National Forest.

• Mowing plants along U.S. Highways 64 and 285 by New Mexico State 

Highway/Transportation Department to maintain visibility for highway safety. When the 

mowing occurs prior to seed heads maturing, it limits the spread of weeds. When this is 

done after seed heads have matured, it tends to spread weed seeds to noninfested sites.

Foreseeable future weed control activities using biological, manual, mechanical and herbicides 

within the cumulative effects area would be conducted by private landowners, county, State and 

other Federal agencies. Appendix 1 describes these activities in detail. Acreage treated varies 

widely from year to year and tends to be small. These other agencies and landowners expect that 

weed control activities would increase over the next 10 years as the weed problem becomes more 

prominent. Based on conversations with other agencies and landowners in northern New Mexico, 

it is estimated that they would cumulatively treat approximately 5,000 to 8,000 acres per year 

over the next 10 years, although the acreage estimates vary widely by treatment method. Acreage 

estimates for nonaerial herbicide applications are generally quite small relative to the acreages 

estimated for biological control methods.

In addition to the weed control programs, other activities likely to be implemented by the two 

forests in the next 10 years include thinning/removing trees for hazardous fuels reduction, 

prescribed burning, trail reconstruction and restoration, wildfire burned area rehabilitation, fish 

habitat improvement, road and bridge maintenance and construction, recreation site and facilities 

reconstruction, and special use permits for various forest uses. The Forest Service has also 

continued to pursue a national emphasis to better manage access through road analysis (RAPs)

and subsequent road closure/decommissioning projects, which will include the two forests. A 

similar emphasis is expected toward off-road vehicle use to manage this relatively new activity 

more proactively.

Table 13 displays the main resources that would likely be affected by this proposed weed control 

project and the associated issues (effects) that were identified for those resources. The second 

column displays other actions considered by the interdisciplinary team in their cumulative effects 

analysis, which includes past, present or foreseeable future activities that are not part of the 

proposed project but could affect forest resources or visitors in a similar manner. In completing 

the cumulative effects analysis, the team not only considered other actions that could affect the 

resource in a similar manner as the project, but the effects associated with those actions.

Table 13. Summary of Cumulative Activities by Key Resource Issues

Resources 

and Issues Other Actions Contributing to Similar Effects

Human 

Health/Safety:

herbicide exposure 

and risk of health 

Other actions that introduce chemicals into the environment include, but 

are not limited to: herbicides recently applied or expected to be applied 

on thousands of acres in northern New Mexico by San Juan and Sandoval 

County Weed Management Areas, Soil and Water Conservation Districts, 

64 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

Resources 

and Issues Other Actions Contributing to Similar Effects

impacts Bureau of Indian Affairs, Valle Caldera National Preserve, Bureau of 

Land Management, National Park Service, Santa Fe Watershed 

Association, The Nature Conservancy, and Audubon Society. Other 

limited chemical introductions would come from: driving vehicles on or 

off roads, constructing facilities and roads, reconstructing and 

maintaining roads, extracting oil-gas or mineral resources, etc. Weed 

control activities on public and private lands also contribute to beneficial 

cumulative effects by reducing allergic reactions and skin irritations 

associated with specific weeds.

Vegetation: loss of 

native plants

Activities include: thinning/removing trees and prescribed burning for 

fuel hazard reduction; grazing livestock; camping outside developed 

sites; driving off existing roads or trails; constructing new facilities (e.g. 

Cow Creek Campground, Buckman water diversion facilities, power

lines, portions of roads to be rebuilt); and clearing vegetation from 

highway/road rights-of-way, etc. Weed control activities on public and 

private lands add to the beneficial cumulative effects of the project by 

restoring native vegetation being displaced by weeds. Wildfire burn area 

rehabilitation (seeding, planting, etc.), fuel reduction activities, meadow 

and riparian restoration projects, etc., on public and private lands also 

contribute to restoration of native vegetation.

Wildlife/Fish:

habitat disturbance

All projects and public land uses create noise and visual disturbance 

including, but not limited to: constructing new facilities or roads, 

reconstructing or maintaining roads, thinning projects, prescribed 

burning, creating habitat for reintroduction of Rio Grande cutthroat trout 

(killing domestic fish, creating barriers...), reintroductions of wildlife 

species or animal control actions conducted by State Department of 

Game and Fish, driving vehicles on or off roads and trails, group 

camping and partying, etc.

Wildlife/Fish:

herbicide-related 

health risk

Same actions as described for “Human Health/Safety.”

Wildlife/Fish:

native vegetation/ 

habitat reduction

Native vegetation cover that may provide nesting, foraging or hiding 

cover habitat for some species is temporarily removed (while maintaining 

long-term site productivity) during many forest activities such as thinning 

and burning projects and livestock grazing. Counties and other agencies 

clear vegetation along road and highways, and manual/mechanical weed 

control treatments listed in Appendix 7 remove some native vegetation. 

Weed control activities on public and private lands add to the beneficial 

cumulative effects of the project by restoring diverse vegetation/habitat 

that is being displaced by weeds. Wildfire burn area rehabilitation 

(seeding, planting, etc.), fuel reduction activities, meadow and riparian 

restoration projects, fish habitat improvement projects, etc., on public and 

private lands also contribute to restoration of high quality wildlife and 

fish habitat.

Soil and Water: risk 

of excessive erosion, 

sedimentation, or 

chemical load

Thinning, burning, grazing, constructing/reconstructing facilities or 

roads, driving off roads or trails, camping, etc., increase soil erosion and 

potentially cause sediment to move into streams. Actions previously 

described that include use of herbicides or other chemicals could add to 

chemical loading in soil, water or aquatic environments. Weed control 

Final Environmental Impact Statement – Invasive Plant Control Project 65
Chapter 3 • Affected Environment and Environmental Consequences

Resources 

and Issues Other Actions Contributing to Similar Effects

activities on public and private lands add to the beneficial cumulative 

effects of the project by reducing erosion caused by monocultures of 

weed replacing native plants. Wildfire burn area rehabilitation (erosion 

control), fuel reduction activities, meadow and riparian restoration 

projects, restoration of dispersed recreation sites that have been denuded, 

closure/decommissioning of unneeded roads and trails, etc., on public 

and private lands contribute to soil stabilization, soil productivity and 

water quality.

Air: smoke or dust 

particulates

Other prescribed burning, wildfires, and residential firewood burning add 

to regional haze, along with other sources of air pollution. Use of 

unsurfaced roads throughout the forest for all activities creates dust.

Heritage 

Resources: risk of 

damage or loss

Same activities as “Soil and Water” above that increase soil erosion pose 

a risk of inadvertent damage to heritage resource sites.

66 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

Vegetation Resource

Affected Environment - Vegetation

The first part of this vegetation resource section discusses the weeds known to occur as well as 

other potentially affected vegetation, then the second part focuses on special status plant species 

(threatened, endangered or sensitive plants).

The Forests lie within the Colorado Plateau Semi-Desert Province and Arizona-New MexicoMountains Semi-Desert-Open Woodland-Coniferous Forest-Alpine Meadow Province 

(Mountains Regime) of the Tropical/Subtropical Steppe Division; and the Great Plains-Palouse 

Dry Steppe Province and the Southern Rocky Mountains Steppe-Open Woodland-Coniferous 

Forest-Alpine Meadow Province (Mountains Regime) of the Temperate Steppe Division within 

the Dry Domain. Fire, insects, and disease are the primary natural sources of disturbance to 

vegetation (McNab and Avers 1994).

Vegetation cover follows altitudinal gradients similar to those in the southern Rocky Mountains. 

Dominant vegetative cover types occurring on the Forests include grasslands, sagebrush, 

shrublands, pinyon-juniper, oak, ponderosa pine, mixed conifer, spruce-fir and subalpine. 

Riparian vegetation is also found in valley bottom lands, and along streams and lakes within each 

of these cover types.

Weeds pose threats to biological diversity of native plant communities, altering of ecosystem 

processes, and loss of rare or special status plants. The weed species known to occur on the 

Forests were listed in Chapter 1 and are described in detail in Appendix 2. Weed populations are 

known to exist on approximately 7,350 acres within the Forests. The anticipated expansion rates 

vary between 5 and 30 percent annually, depending on weed species and ecologic conditions at 

each infestation site (Tu et al. 2001). At a conservative estimate of 8 percent of growth per year, 

the expected weed population is expected to exceed 15,000 acres in 10 years. A key concern is 

that weeds contribute to the decline in frequency of native plant species that depend on similar 

habitat as the weeds. Weeds also cause a decline in species richness overall. Weeds are highly 

adept at capturing available moisture and nutrients, and quickly spreading, choking out other 

vegetation. Displacement of native vegetation, decreased species diversity, and changing habitat 

structure and composition result from invasions by these species.

Infestations of Russian knapweed, hoary cress and yellow toadflax have been identified in 

highway rights-of-way within the Forests’ boundaries. Major wildfires have occurred on both 

forests in recent years. Monitoring of recent high severity burns has identified these areas as 

locations for new infestations.

The Jemez Ranger District (Santa Fe National Forest) completed NEPA analysis and began 

implementation of the Jemez Riparian Enhancement Project in 1999. The Jemez Ranger District 

has been successfully using herbicides to selectively control saltcedar, Russian olive and Siberian 

elm and restore native riparian plant species such as willows and cottonwoods. The lower 2 feet 

of small weed species are sprayed with a mixture of Garlon 4 (triclopyr) and vegetable oil. Larger 

weed trees are cut near the ground and their stumps are treated with Garlon 3A and water. 

Previously approved, small acreage weed control treatments have also occurred on the Carson 

National Forest, and on both forests where other agencies have jurisdiction such as along 

highway rights-of-way.

Final Environmental Impact Statement – Invasive Plant Control Project 67
Chapter 3 • Affected Environment and Environmental Consequences

Thirteen additional species of weeds have not been detected on the Forests, but are of concern in 

New Mexico and have potential for introduction and spread on the Forests (USDA NRCS 2002) 

as described in Chapter 1. The priority for management of these species is early detection and 

eradication.

Table 14 displays the total acres of known weed infestations by vegetation cover type.

Table 14. Weed Infestations by Vegetation Type

Vegetation Type Total Acres Acres 

Infested

Percent of Total 

Acres Infested

Grasslands 241,030 420 0.17

Sagebrush/Shrubs 95,713 20 0.02

Pinyon-Juniper 823,324 1,160 0.14

Oak Woodlands 29,600 50 0.17

Ponderosa Pine 640,500 1,920 0.30

Mixed Conifer 511,219 610 0.12

Spruce-Fir 348,815 230 0.07

Riparian/Valley Bottom Lands 343,431 2,850 0.83

The following paragraphs briefly describe each vegetation cover type and inventoried weed 

infestations within each type.

Grasslands 

Grasslands are widespread at all elevations within both forests, typically as openings within 

shrublands and forest cover types. Weed species include black henbane, bull thistle, Canada 

thistle, leafy spurge, musk thistle, scotch thistle, yellow starthistle and yellow toadflax. Weeds 

found to date cover 420 acres of grasslands (0.17 percent).

Sagebrush/Shrub Cover Types

Sagebrush and shrub cover types are widespread at lower and middle elevations (6,200-7,900 

feet) within both forests, typically as openings within forest cover types. Weed species known to 

be present include black henbane, bull thistle, Canada thistle, Dalmation toadflax, musk thistle, 

perennial pepperweed, Russian knapweed, Scotch thistle, and spotted knapweed. Weeds found to 

date cover 20 acres of shrublands (0.02 percent).

Pinyon-Juniper Cover Types

Pinyon-juniper cover types are widespread at lower and middle elevations (5,700-8,400 feet) 

within both forests. Weed species known to be present include bull thistle, Canada thistle, 

Dalmation toadflax, diffuse knapweed, leafy spurge, musk thistle, Russian knapweed, Scotch 

thistle, Siberian elm and spotted knapweed. Weeds found to date cover 1,160 acres of pinyonjuniper woodlands (1.21 percent).

68 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

Figure 6. Vegetation Types in the Project Area

Final Environmental Impact Statement – Invasive Plant Control Project 69
Chapter 3 • Affected Environment and Environmental Consequences

Oak Woodlands Cover Type

Oak woodlands are widespread at middle elevations (7,700-9,000 feet) within the Santa Fe 

National Forest and Carson National Forest. The most common oak species present in weed 

infested areas is Gamble oak. Weed species known to be present include bull thistle, Canada 

thistle, diffuse knapweed and musk thistle. Weeds found to date cover 50 acres of oak woodlands 

(0.17 percent).

Ponderosa Pine Cover Types

Ponderosa pine cover types are widespread at middle elevations (7,200-9,000 feet) within both 

forests. Weed species known to be present include bull thistle, Canada thistle, Dalmation toadflax, 

diffuse knapweed, leafy spurge, musk thistle, Russian knapweed, Russian olive, Scotch thistle 

and yellow toadflax. Weeds found to date cover 1,920 acres of the ponderosa pine forest (0.30 

percent).

Mixed Conifer Cover Types

Mixed conifer cover types are widespread at middle and upper elevations (6,900-11,200 feet) 

within both forests. Weed species known to be present include black henbane, bull thistle, Canada 

thistle, diffuse knapweed, leafy spurge, musk thistle, Russian knapweed, Scotch thistle, spotted 

knapweed and yellow toadflax. Weeds found to date cover 610 acres of mixed conifer forest (0.12 

percent).

Spruce-fir Cover Types

Spruce-fir cover types are widespread at upper elevations (8,700-11,500 feet) within both forests. 

Weed species known to be present include bull thistle, Canada thistle, musk thistle, Russian 

knapweed and yellow toadflax. Weeds found to date cover 230 acres of spruce-fir forest (0.17 

percent).

Riparian Areas/Valley Bottom Lands

Riparian areas and valley bottoms with wet soils are widespread throughout all elevations within 

both forests. Riparian areas often overlap other cover types at the mapping scale used for this 

analysis. Where information indicated riparian areas present, these acres were subtracted from 

other cover types so they were not counted twice. Weed species known to be present include bull 

thistle, Canada thistle, Dalmation toadflax, field bindweed, hoary cress, musk thistle, poison 

hemlock, Russian knapweed, Russian olive, saltcedar, Scotch thistle, Siberian elm, spotted 

knapweed and yellow toadflax. Weeds found to date cover 2,850 acres of riparian and valley 

bottom areas (0.17 percent), with saltcedar covering the most acres.

Environmental Consequences - Vegetation

Alternative A (No Action)

The No Action Alternative would not meet the purpose and need. It would not help to restore 

diverse, sustainable native plant communities in weed infested areas. It would result in continued 

invasion and spread of weeds throughout the Forests and particularly on and near the 7,350 acres 

proposed for treatment. The anticipated expansion rates vary between 5 and 30 percent annually, 

depending on weed species and ecologic conditions at each infestation site. Given a conservative 

70 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

estimate of 8 percent per year, the number of acres impacted by weeds would double over the 

next 10 years. The 7,350 acres of inventoried and mapped weed infestations underestimates 

existing weed infestation acres when the uninventoried areas are considered. There could easily 

be 10 to 20 percent more weed infested acres than those inventoried, which would spread 

exponentially to a minimum of 20,000 acres within 10 years, at an 8 percent spread rate.

As weed populations grow, weeds would contribute to the continuing decline in frequency of 

some native species and a decline in species richness overall. Weeds are highly adept at capturing 

available moisture and nutrients, and quickly spreading, choking out other vegetation. Once 

weeds begin to dominate native plant communities, a loss of species diversity, composition and 

ecosystem function could occur (USDA FS 2003c).

Overall, not treating weeds on the Forests would likely cause continued displacement of native 

vegetation and decreased species diversity. Thus, the historic trends and natural ecosystem 

functions and processes in native plant communities would incur negative, long-term impacts. 

This change in native plant diversity would affect the culturally important plants (osha, etc.) as 

they are replaced by invasive species.

For example, dense infestations of yellow starthistle would not only displace native plants and 

animals, but would threaten natural ecosystems and nature reserves by fragmenting sensitive 

plant and animal habitat. Bull thistle, Canada thistle, musk thistle, and Scotch thistle would 

threaten natural communities by directly competing with and displacing native vegetation, 

decreasing species diversity, and changing the structure and composition of some habitats. 

Riparian area communities would continue to be threatened by direct competition from Canada 

thistle, field bindweed, hoary cress, perennial pepperweed, poison hemlock, Russian olive, 

saltcedar and Siberian elm. These species displace native riparian vegetation and change the 

vegetation structure of these areas away from native species, which consequently changes the 

ecological processes (water flow for instance) which makes natural recovery more difficult if not 

impossible.

Ecosystem processes that involve water retention and nutrient cycling would also be impacted by 

weeds. A type of ground cover called cryptogrammic ground crust would be reduced by spotted 

knapweed. This ground crust is composed of small lichens and mosses and commonly covers 

undisturbed soil surfaces. This ground crust is important for soil stabilization, moisture retention, 

and nitrogen fixation. Spotted knapweed also increases erosion rates because of its taproot growth 

characteristics. Runoff was 56 percent higher and sediment yield was 192 percent higher on 

spotted knapweed plots compared to bunchgrass plots during a simulated rainfall period (Lacey 

1989). Knapweed infestations would have long-term detrimental effects on soil and water 

resources (USDA FS 2003a).

Introduction and spread of weeds threatens biological diversity of native plant communities, and 

can alter ecosystem processes such as intensity and frequency of fire, hydrologic cycles, and soil

erosion rates.

The following notes key differences in effects of Alternative A, based on vegetation type:

Grasslands: These habitats are highly vulnerable to weed invasion, especially when

considering the additive effects of drought and grazing. Many weed species would continue 

to out-compete grasses or excrete chemicals that eliminate grass from a weed infestation 

altogether.

Final Environmental Impact Statement – Invasive Plant Control Project 71
Chapter 3 • Affected Environment and Environmental Consequences

Sagebrush/Shrub: In many areas in the Intermountain West and the Great Basin, 

encroachment by cheatgrass (Bromus tectorum) and other weeds is rapidly displacing 

sagebrush/scrub communities (Sheley et al. 1999). This reduction in native shrub 

communities would continue on the Forests, and would reduce wildlife forage, nesting and 

hiding cover. In addition, fire regimes would become more frequent and occur earlier in the 

season in these altered communities, which promotes further weed establishment and 

spread.

Pinyon-Juniper: These habitats would continue to become more vulnerable to weed 

invasion due to large-scale die off of pinyon pine. The reduction of live vegetative cover 

and increased potential of wildfire leaves this community type at higher risk for further 

weed establishment and spread.

Oak Woodlands: This community would continue to be inherently at low risk for weed 

invasion because of the closed canopy nature of Gambel oak thickets and woodlands.

Ponderosa Pine: Weeds would invade ponderosa pine community types, especially those 

recently thinned out and opened up by fuel reduction activities. The effects of weeds 

typically affect the lower structure of this community type and would not impact the trees. 

Ponderosa pine grasslands are the most vulnerable to the effects from weeds. While the 

structure of the pine forests may remain intact for some time after weed invasion to this 

community type, changes in fire regimes (increased intensity) and future re-establishment 

of ponderosa pines may be retarded or prevented as openings necessary for the pine to 

regenerate do not develop.

Mixed Conifer and Spruce-fir: Many of the acres in this forest community are infested 

with thistles, although generally these are older forests with higher percentages of canopy 

cover that are not highly vulnerable to weed invasion. Ecological factors like a short 

growing season reduce the risk of weed spread and invasion. However, without weed 

control, weeds would continue to infiltrate this community, particularly in the younger 

stands, which could retard the development of mature mixed conifer communities.

Riparian and Valley Bottoms: Riparian communities would continue to be particularly 

vulnerable to weed infestations. Weeds like saltcedar (tamarisk spp.), Russian olive, 

Siberian elm, and bull thistle would expand their influence in riparian areas and valley 

bottoms on the Forests. They would eventually replace native riparian vegetation such as 

willows, cottonwoods, rushes, and sedges.

Alternative B (Proposed Action)

Tables 15 through 23 display the treatments proposed for these vegetation cover types. It should 

be noted that the acreages do not match precisely with weed occurrence or treatment tables in this 

DEIS due to rounding off to the nearest acre.

72 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

Table 15. Treatment Acres in Grassland

Treatment Alt. B Alt. C Alt. D

Biological 3 65

Biological: Jemez RD 63 63

Herbicides 251 0 354

Manual 6 72 0

Manual-Herbicide 68 0 0

Manual-Mechanical 0 8 0

Mechanical 2 175 0

Mechanical-Biological-Grazing 6 6 0

Mechanical-Herbicide 20 0 0

Prescribed Fire 0 28 0

Total 419 417 354

Table 16. Treatment Acres in Sagebrush/Shrub

Treatment Alt. B Alt. C Alt. D

Herbicides 18

Manual 1 2

Manual-Grazing

Manual-Herbicide 6 0 0

Manual-Mechanical 4

Mechanical 12 12

Total 19 18 18

Table 17. Treatment Acres in Ponderosa Pine

Treatment Alt. B Alt. C Alt. D

Biological-Grazing 13 13

Biological 6 38 0

Biological: Jemez RD 92 92

Grazing-Herbicides 20

Herbicides 1,179 1,823

Manual 3 608 0

Manual-Grazing 10 30

Manual-Herbicide 576 0 0

Manual-Mechanical 7

Mechanical 241

Mechanical-Biological-Grazing 6 6

Mechanical-Herbicide 10

Prescribed Burning 880

Total 1,915 1,915 1,823

Final Environmental Impact Statement – Invasive Plant Control Project 73
Chapter 3 • Affected Environment and Environmental Consequences

Table 18. Treatment Acres in Oak Woodlands

Treatment Alt. B Alt. C Alt. D

Biological 0 1

Herbicides 48 49

Manual 1 8 0

Manual-Grazing 1

Prescribed Burning 39

Total 49 49 49

Table 19. Treatment Acres in Pinyon-Juniper

Treatment Alt. B Alt. C Alt. D

Biological 20 36 0

Biological: Jemez RD 523 523 0

Herbicides 512 0 629

Manual 16 65 0

Manual-Grazing 41 41 0

Manual-Herbicide 15 0 0

Manual-Mechanical 11 0

Mechanical 9 392 0

Mechanical-Biological-Grazing 1 1

Mechanical-Herbicide 15

Prescribed Burning 85

Total 1,152 1,154 629

Table 20. Treatment Acres in Riparian/Valley Bottoms

Treatment Alt. B Alt. C Alt. D

Biological-Grazing 22 21 0

Biological 94 102 0

Biological: Jemez RD 1,050 1,050 0

Grazing-Herbicides 11 0 0

Grazing-Manual 38 49 0

Herbicides 554 0 1,630

Manual 7 704 0

Manual-Herbicide 774 0 0

Manual-Mechanical 141

Mechanical 1 192 0

Mechanical-Biological-Grazing 2 3 0

Mechanical-Herbicide 44 0 0

Prescribed Burning 335

Prescribed Burning-Mechanical 81 81

Total 2,678 2,678 1,630

74 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

Table 21. Treatment Acres in Mixed Conifer

Treatment Alt. B Alt. C Alt. D

Biological-Grazing

Biological: Jemez RD 41 41 0

Herbicides 524 564

Manual 5 35

Manual-Grazing 2 2

Manual-Herbicide 17 0 0

Manual-Mechanical 12

Mechanical 127

Mechanical-Biological-Grazing 1 1

Mechanical-Herbicide 15

Prescribed Burning 388

Total 605 606 564

Table 22. Treatment Acres in Spruce-Fir

Treatment Alt. B Alt. C Alt. D

Herbicides 205 0 228

Manual 3 19 0

Manual-Grazing 1 1 0

Manual-Herbicide 2

Manual-Mechanical 4

Mechanical 19

Mechanical-Biological-Grazing

Mechanical-Herbicide 18

Prescribed Burning 186

Total 229 229 228

Table 23. Treatment Acres in Other (e.g. urban)

Treatment Alt. B Alt. C Alt. D

Biological: Jemez RD 1 1 0

Herbicide 127 0 134

Manual 2 8 0

Manual-Herbicide 4 0 0

Manual-Mechanical 1

Mechanical 17

Mechanical-herbicide 1

Prescribed Burning 107

Total 135 134 134

Final Environmental Impact Statement – Invasive Plant Control Project 75
Chapter 3 • Affected Environment and Environmental Consequences

This alternative would improve native vegetation by suppressing, containing or eradicating weeds 

on treatment areas. Alternative B would assist the re-establishment of native plant communities 

by removing the dominant and aggressive weeds. Regardless of the methods used at each site, 

there would be a noticeable decline in weeds overall, and an increase in native plant abundance 

and vigor. As weeds are removed and the bare soil fills in with native plants, the plant community 

would become more resistant to re-establishment of weeds.

Alternative B would result in a reduction in individual, nontarget ground cover plants or small 

patches of these native plants if they are interspersed with weeds. However, the loss of native 

plants would be temporary and very small, estimated at less than an acre on the larger weed 

treatment sites. Temporary reductions in native plants would vary primarily by the weed 

treatment method used.

Biological methods avoid loss of nontarget plants altogether, as the insects cannot be released 

without APHIS approval, based on assurance that they would only consume the target weed 

species. The effectiveness of using biological methods to control weeds and restore native species 

would be more gradual and would not be detectable in the short term. Manual methods would be 

able to usually avoid cutting or digging up nontarget plants. Herbicides applied manually or with 

backpack sprayers would utilize directional spray devices that minimize herbicide spray on 

nontarget vegetation. Adherence to wind and weather condition requirements would minimize the 

amount of spray that would drift through the air onto nontarget plants. Vehicle-mounted herbicide 

spraying is less precise but includes a directionally controlled wand and on/off switch to 

minimize hits to nontarget vegetation. Mechanical, grazing and burning methods would impact 

entire roadsides or areas treated, unless a torch is used to burn just weed species. However, those 

3 methods would be used on less than 5 percent of the treatment acreage so would have very little 

effect on native vegetation across the Forests. In addition, because methods like burning, grazing 

and mowing only remove the tops of plants, they would have a less intense short-term effect on 

the ground cover. On a landscape level, the temporary reduction in native species would be 

negligible.

Herbicides would cause the more noticeable change in the composition of native plants that are 

sprayed with herbicides, since some herbicides would kill those plants entirely, depending on the 

selective nature of the herbicide used. However, applications at prescribed rates should not 

eliminate any native (or nonnative) populations from the plant community. Herbicides constitute 

a short-term disturbance to plant communities that have evolved to withstand and recover from 

long-term changes and disturbances (USDA FS 2003a). If infestations remain untreated, they 

would expand and reduce native vegetation through competition. Native plant communities are 

more at risk from competition by nonnative species than from changes resulting from herbicides.

Plants of special concern in Native American or traditional Hispanic cultures were also 

considered as special plants that may be impacted by weed control treatments. These plants 

would benefit from reduction in competition from invasive species over the long term; but there 

is a high likelihood that these plants in or near treated weed populations would be affected during 

the short term. 

The concern remains for individuals who collect plants from the Forests for use in medicines, 

handicrafts or other purposes (see “Human Health” section). As described in Chapter 2, 

“Mitigation Measures,” these individuals can obtain advance notification of treatments, including 

the method, location and timing. This may allow them to gather plants prior to weed control 

76 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

treatments and/or notify the Forest Service of any specific areas of concern or traditional use 

areas. Traditional cultural properties would be protected through the procedures outlined in the 

programmatic agreement developed for protection of heritage resources, including consultation 

with affected parties, as described in Chapter 2 and in the “Heritage Resources” section of this 

chapter.

Once the dominant weeds are removed or killed, community diversity is expected to be reestablished from the existing seeds in the soil and seeds from adjacent areas. It is expected that at 

least the grasses or other early-seral plants would recover within treated areas within the first 

growing season (typical for recovery on most sites), and abundance and diversity of native plants 

would increase over the following few years. Mitigation measures require revegetating areas 

where necessary following treatments, which would avoid creating or leaving bare soil 

conditions. Measures such as deferring grazing after treatment, monitoring, and the adaptive 

management approach would further enhance the effectiveness of treatments. For all treatments 

proposed, re-establishment of vegetative cover is key in prevention of weed reinvasion in all 

treatment types and plant communities (Sheley et al. 1999).

Treating weeds now while the infestations are relatively small would greatly increase the chance 

of effectiveness and reduce any negative effects to native plants, compared to delaying treatment 

for several more years. Overall, there would be no noticeable, long-term, or irreversible loss of 

native nontarget vegetation or native species diversity.

There are only a few minor differences in effects to native plants based on vegetation cover types. 

The current weed infestation is highest in riparian/valley bottoms dominated by saltcedar and 

other weeds, and much of those areas (about 1,140 acres of the total 2,680) would be treated with 

biological controls (alone or in combination with other methods). Proposed treatments would help 

restore riparian areas, which are particularly important elements in the ecosystem and account for 

much of the biological diversity of any given area. Riparian areas and valley bottoms would be 

expected to revegetate faster than adjacent uplands. Removal of saltcedar in particular would 

improve water availability and enhance the native riparian vegetation growth.

The ponderosa pine and pinyon-juniper communities, which are the most prevalent forest 

vegetation cover types on the Forests, would experience the next highest acres of weed treatment. 

Conifer tree seedlings and saplings are the most vulnerable to the effects of weed eradication, but 

they can re-establish quickly on exposed mineral soils. Larger conifer trees would not likely 

succumb to any of the weed control methods. Removal of weeds in the pinyon-juniper cover type 

is of increasing importance due to the current loss of pinyons resulting from the bark beetle 

epidemic. Weed treatments in this cover type would help prevent the spread of weeds in areas 

where pinyons have died and been removed. Grasslands, shrublands and higher elevation conifer 

forest communities would continue to be the least affected by weed infestations or weed 

treatment activities.

Alternative C (No Herbicides)

The most noticeable effects to native vegetation would be the beneficial increase in native species 

abundance and diversity on the treated acres, similar to effects described for Alternative B. The 

main difference with this alternative is that for a given budget, the expectation is that fewer acres 

would be treated each year with initial entry treatments. Many more repeat treatments on the 

same sites would likely be needed to control weeds without the use of herbicides as an adjunct 

method. In the short term, many of the nonherbicide methods would contain or control some 

Final Environmental Impact Statement – Invasive Plant Control Project 77
Chapter 3 • Affected Environment and Environmental Consequences

weed species with repeat applications. Biological controls would likely be effective in the long 

term, after biocontrol insect populations have grown enough to have a significant effect on weed 

populations, which could take years. The other nonherbicide treatment methods are generally not 

as effective against weed species as herbicide treatment in combination with these other methods. 

For a fixed amount of funding, the acres treated would logically be fewer in Alternative C than 

Alternative B. 

Therefore, there would be a high risk that the rate of weed spread would exceed the rate of weed 

control, and the Forests would not be able to get ahead of the weed problem. Thus, effects in the 

long term would be most similar to Alternative A (No Action).

Alternative D (Herbicides Only)

Beneficial effects to native vegetation abundance and diversity on the treated acres would be very 

similar to effects described for Alternative B. The key difference is the slightly reduced 

effectiveness of some herbicide treatments without the supplemental use of other methods. It is 

well known from past studies that the most effective weed control treatments are those that utilize 

a combination of herbicides with other nonherbicide methods. This reduced effectiveness means 

that repeated treatments may be required above what would be necessary if a combination of 

treatments were used.

Unlike Alternative C, this reduced effectiveness would not likely result in a reduction in the 

number of acres treated because the cost-effectiveness of treating with herbicides is high.

Cumulative Effects - Vegetation

The analysis area for cumulative effects on vegetation is the area in and immediately adjacent to 

the Forests. This boundary represents the areas where the actions proposed in this project are 

most likely to interact with other activities, in particular the weed treatments and ground 

disturbance on both forests and other lands (private, State, BLM, etc.).

In all action alternatives, cumulative impacts to nontarget plant species would stem from forest 

management activities, public land uses, and activities on other public and private lands, as 

described in the beginning of this chapter. For example, cumulative effects include potential 

short-term reduction in nontarget vegetation from herbicides applied in ongoing weed treatment 

projects on the forest, on private inholdings, and on other public lands in and around the Forests. 

There would also be continued spread of weeds through activities that disturb the soil, such as 

dispersed recreational activities.

However, forest projects to be conducted over the next 10 years would primarily be aimed at 

restoring native vegetation and ecosystem functionality, based on agency priorities and budgets. 

Long-term ecosystem restoration projects would compensate for activities that remove or damage 

native vegetation, including short-term removal of nontarget plants from this proposed project. 

Overall, the most noticeable cumulative effect on vegetation would be beneficial, especially over 

the long term. Forest management activities would result in increased abundance and diversity of 

riparian, grasslands and other ground vegetation, which would be enhanced by the effects of this 

weed control project.

78 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

Affected Environment - Special Status Plants

There is one federally listed (endangered) plant within the project area—Holy Ghost ipomopsis—

which occurs in one known location on the Santa Fe National Forest. No “threatened” plants 

occur on the Forests. There are seven plant species listed as sensitive in the Southwestern Region 

of the Forest Service that could exist on the Forests. Four of these plants—Arizona willow, 

Chiricahua dock, egg-leaf coral and hairless (pecos) fleabane—are located in high elevation 

alpine and subalpine communities where weed infestations are unlikely to occur. The vegetation 

specialist report in the project files has detailed habitat information for each species.

Table 24 identifies the special status plants likely to occur on the Forests, along with their 

associated vegetation cover types.

Table 24. Special Status Plant Species Habitat by Vegetation Cover Type

Nontarget Cover 

Types

Sagebrush/ 

Shrubs

Pinyon 

Juniper

Oak 

Woodland

Ponderosa 

Pine

Mixed 

Conifer Riparian

Arizona willow Subalpine

Chiricahua dock Subalpine

Egg-leaf coral Alpine 

Meadows

Hairless fleabane Subalpine 

meadows

Parish’s alkali grass X (b)

Ripley’s milkvetch X X X X

Holy Ghost 

ipomopsis X(a)

Small-headed 

goldenweed X (c)

Key: (a) Holy Ghost Canyon; (b)Alkaline springs and seeps; (c) Granitic rock crevices

Environmental Consequences - Special Status Plants

To summarize effects to special status plants, all alternatives would have “no effect” on the 

endangered Holy Ghost ipomopsis, and “no impact” on the four sensitive plants that occur in 

remote alpine and subalpine forest communities. For the other three sensitive plants, actions 

involved in Alternatives B, C, and D “may impact individuals or habitat but will not likely result 

in a trend toward Federal listing or reduced viability of the population or species,” primarily due 

to the mitigation measures required for protection of these plant species.

Alternative A (No Action)

The effects under this No Action Alternative would be the same as previously described for other 

native plant species. Without treatment, weeds would continue to spread throughout the Forests, 

displacing native understory vegetation. An increase in weeds would reduce the endangered and 

sensitive plants on the Forests. For certain sensitive species, especially those likely to occur in or 

near existing weed infestations, this would eventually lead to a downward trend in population 

viability and a trend toward Federal listing. The Holy Ghost ipomopsis, the very rare and 

endangered plant species on the Santa Fe National Forest, is located along a road and near a 

number of thistle populations along the same road system. It is likely that in the next 10 years 

Final Environmental Impact Statement – Invasive Plant Control Project 79
Chapter 3 • Affected Environment and Environmental Consequences

these weeds would migrate to this native plant population and, once established, have an adverse 

impact because they use similar habitats and compete for resources.

On the other hand, this No Action Alternative eliminates the risk of inadvertent damage to special 

status plants from weed control treatment activities such as mowing, grazing, burning, digging, or 

herbicides.

Alternative B (Proposed Action)

Any potential adverse impacts to individual special status plants as a result of weed control 

treatment actions would likely be avoided by following the pretreatment survey and avoidance 

procedures outlined in Chapter 2. Thus, there is a very low risk of accidental damage or mortality 

to individual plants during weed control treatments if the survey and avoidance procedures are 

not appropriately carried out. For example, special status plant species may be negatively 

impacted by herbicide spray drift, but it is unlikely to occur because mitigation measures prohibit 

use of herbicide within the known Holy Ghost ipomopsis population. For other sensitive plants, a 

general buffer of 50 feet is used as well as requiring herbicides to be applied by hand (gloves, 

wicks, rags, etc.) to individual weed plants. Herbicides with high risk of damage through drift 

would either not be used with boom spray vehicle systems or a larger buffer (1,000 feet) would be 

used to protect known sensitive plants. If herbicides are to be sprayed within potential habitat for 

any special status plant species, a survey of that habitat will be conducted if feasible. If no survey 

is possible, the potential habitat will be treated as if occupied by the species and avoided until 

surveys can be completed.

Biological control agents are extensively tested to ensure that they have a very narrow host range 

and would not pose a serious threat to nontarget plants. Although extensive screening and testing 

reduces the potential for injury to native plants, biological control is not risk free. Agents may 

attack plants closely related to the host weed. The State of New Mexico does not allow use of 

biological controls on thistle because of this possibility. Therefore, only agents approved for use 

in the State would be used in order to avoid this possibility.

Hand pulling and digging can be selective in terms of plants removed. Hand pulling may 

inadvertently destroy native or sensitive species growing in close proximity to weeds because of 

trampling by pulling crews. Damage may occur to the root systems of nontarget plants that are 

intermingled with the root systems of target species. Implementation of the listed mitigation 

measures will minimize the potential for negative effects to the Holy Ghost ipomopsis. An 

important one of these measures is the requirement to have a biologist or other qualified person 

who can identify the plant during treatment activity.

Other mitigation measures noted in Chapter 2 will further protect the Holy Ghost ipomopsis. 

Herbicide use and controlled grazing would not be permitted in the plants known population. 

Mowing and prescribed burning will not occur within 50 feet of Holy Ghost ipomopsis plants. 

Because of these mitigation measures, there would be no direct or indirect effects to this species 

from these treatments. These treatments may impact individuals or habitat of sensitive species, 

but they are not likely to result in a trend toward Federal listing or reduced viability for the 

population or species.

Implementation of Alternative B with appropriate mitigation would not contribute to a loss of 

population viability nor a trend toward Federal listing of any sensitive plant species. No negative 

impacts would be expected to the sensitive species that occur in the remote, high elevation 

80 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

forests, and may impact individuals or their habitat to a minor degree in areas where weed 

treatments are more likely to occur. This alternative would also be expected to have “no effect” 

on the endangered Holy Ghost ipomopsis based on mitigation measures and the high probability 

that they would be effective in protecting this plant population.

The most noticeable consequence of implementing this alternative would be the reduction in 

weed infestations that would otherwise take over sites currently occupied by some of the special 

status plants.

Alternative C (No Herbicide)

Implementation of Alternative C would result in no potential impact to endangered or sensitive 

plants relative to herbicide application. Individual sensitive plants such as the small headed 

goldenweed, Parish’ alkali grass and Ripley milk-vetch would have a moderate risk of negative 

impacts from mechanical, burning, grazing and manual treatment methods and little, if any, risk 

of impact from biological controls. However, implementation of Alternative C with identified

mitigation measures would not likely contribute to a loss of population viability nor contribute to 

a need for Federal listing of any sensitive plants.

Like Alternative B, implementing weed control treatments would reduce the magnitude of weed 

infestations that can out-compete and eventually extirpate special status plants. However, without 

use of herbicides, Alternative C would not be as effective in controlling or containing weeds away 

from the Holy Ghost ipomopsis population, and this could result in degradation of sensitive plant 

habitat by weed infestations similar to those described in Alternative A. For this reason, it would 

be especially important under this alternative to concentrate treatments on weed infestations that 

are threatening species such as Holy Ghost ipomopsis, small headed goldenweed, Parish’ alkali 

grass and Ripley milk-vetch, since these are the most vulnerable to competition.

Alternative D (All Herbicide)

Implementation of Alternative D would have very similar effects to those described for 

Alternative B. The difference is there would be no risk of negative impacts to special status plants 

from mechanical, burning, grazing or manual methods. No negative impacts to special status 

plants would be expected from herbicides either because no herbicides would be allowed in the 

Holy Ghost ipomopsis population. The effects of a weed infestation, if established, would 

therefore be similar to Alternative A (no action). If a weed infestation were found, likely a 

separate analysis would be initiated to deal with the specific problem.

For other special status plants, as with Alternative B, the most noticeable consequence of 

implementing this alternative would be the beneficial reduction in weed infestations that would 

otherwise take over sites currently occupied by some of the special status plants. Alternatives B 

and D in particular would contribute to maintaining or improving habitat for special status plants.

Cumulative Effects - Special Status Plants

The analysis area for cumulative effects on vegetation is the area in and immediately adjacent to 

the two forests. This boundary represents the areas where actions proposed in this project are 

most likely to interact with other activities, in particular the weed treatments and ground 

disturbance on both forests and other lands (private, State, BLM, etc.).

Final Environmental Impact Statement – Invasive Plant Control Project 81
Chapter 3 • Affected Environment and Environmental Consequences

In all action alternatives, cumulative impacts to nontarget plant species would stem from forest 

management activities and activities on other public and private lands as described in the 

beginning of this chapter.

Cumulative effects on vegetation were previously described in this “Vegetation Resource” section 

and apply equally to special status plants. The main difference is that special status plants would 

be protected more than other native vegetation during all forest management activities and special 

use authorizations. Thus, the likelihood of negative cumulative effects is even lower for the 

special status plants.

Based on the prediction that there would be little to no risk of negative consequences to special 

status plants from this proposed project, and minimal impacts to special status plants from other 

ongoing or future activities on the Forests, negative cumulative effects to special status plants 

would be insignificant.

Cumulative beneficial effects would be slightly more pronounced because management activities 

aimed at restoring ecosystem functionality, including interagency weed control programs, would 

result in increasing the abundance and diversity of native vegetation, including special status 

plants. Beneficial, long-term cumulative effects would greatly outweigh any minor or short-term 

reductions in native vegetation caused by ground-disturbing activities.

82 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

Wildlife Resources

The affected environment for wildlife resources is divided into three sections: management 

indicator species, special status species, and migratory bird species. The environmental 

consequences section begins with a discussion on wildlife in general followed by the same three 

sections on specific categories of wildlife species.

Affected Environment - Management Indicator Species

Management indicator species (MIS) were identified during development of Forest Plans, and are 

used to monitor effects of management activities on populations of wildlife and fish, including 

those that are socially or economically important. Species which are both an MIS and a TES 

species will be discussed in the “TES” section, and aquatic MIS species will be discussed in the 

“Fish and Aquatics Resources” section.

Table 25 displays the MIS identified on the Forests, estimated acres of existing habitat on the 

forest where it is a MIS, and the acres of weed infestations within those habitats, along with the 

probability that the species would be found within a proposed weed treatment area. There are 

additional descriptions of each MIS habitat and estimated population trend, based on MIS 

assessments conducted on each forest.

Table 25. Wildlife Management Indicator Species (MIS), Habitat and Weed Infestation

Species National

Forest Habitat

Estimated 

Acres of 

Habitat

Estimated 

Acres of 

Weed 

Infestation

Probability 

of MIS 

Occurrence 

in a 

Treatment 

Area

Brewer’s 

Sparrow

Carson Sagebrush 81,752 120 High

Juniper 

Titmouse

Carson Pinyon-Juniper 348,729 117 High

Abert’s 

Squirrel

Carson Ponderosa Pine 63,190 709 High

Hairy 

Woodpecker

Carson and 

Santa Fe

All forest types 

(Snags and down 

logs)

1,088,700 6,980 High

Red Squirrel Carson Mixed Conifer 217,606 187 High

Rocky 

Mountain Elk

Carson and 

Santa Fe

All Types 3,048,100 7,250 High

Merriam’s 

turkey

Carson and 

Santa Fe

Most habitat 

types

1,615,410 6,060 High

Rocky 

Mountain 

Bighorn sheep

Carson and 

Santa Fe

Alpine 78,900 5 Low

Pinyon jay Santa Fe Pinyon-Juniper 465,725 4,413 High

Mourning 

dove

Santa Fe Most habitat 

types

990,000 5,347 High

Final Environmental Impact Statement – Invasive Plant Control Project 83
Chapter 3 • Affected Environment and Environmental Consequences

Species National

Forest Habitat

Estimated 

Acres of 

Habitat

Estimated 

Acres of 

Weed 

Infestation

Probability 

of MIS 

Occurrence 

in a 

Treatment 

Area

Mexican 

Spotted Owl Santa Fe Mixed Conifer See TES Section

White-tailed 

Ptarmigan Carson Alpine See TES Section

1 Information from Santa Fe and Carson forest-wide MIS reports (Carson NF 2003, Santa Fe NF 2003). Acres of weed 

infestations are based on currently known populations. Forest-wide surveys have not been completed and weed 

populations are expanding.

Brewer’s Sparrow

Brewer’s sparrow is an indicator for sagebrush habitat on the Carson National Forest (USDA FS 

1986a). In northern New Mexico the habitat for Brewer’s sparrow is sagebrush, brushy plains and 

the interface of pinyon-juniper woodlands and sagebrush. Brewer’s sparrow is strongly associated 

with high sagebrush vigor throughout its range, preferring areas dominated by high shrub cover, 

large patch size and bare ground. The Carson National Forest has an estimated 81,752 acres of 

habitat for Brewer’s sparrow as of 2002 (USDA FS 2003a). The trend for habitat on the forest is 

increasing based on the gradual conversion of grasslands to sagebrush. The population trend for 

the Carson National Forest is considered stable.

Juniper (Plain) Titmouse

The plain titmouse is an indicator species for pinyon-juniper (PJ) canopies (USDA FS 1986a). 

Also known as “juniper” titmouse, the plain titmouse is a resident of deciduous or mixed 

woodlands, favoring oak and PJ. The titmouse usually nests in natural cavities or old woodpecker 

holes primarily in oak trees, but it is capable of excavating its own cavity in rotted wood. The 

species feeds mainly on insects, seeds and occasional fruits, and also is a bark gleaner. As a cavity 

nester, large, older trees are an important feature. The Carson National Forest shows a decrease in 

acres of habitat from 364,900 to 348,729 between 1986 and 2002. There is a downward trend in 

habitat with a loss of about 2 percent in the available habitat since 1986. Population trend for the 

Carson National Forest is also downward, although this is a common species on the forest (USDA 

FS 2003a).

Abert’s Squirrel

Abert’s squirrel principally utilizes the ponderosa pine forest type. The species is an indicator for 

the presence of interlocking canopies in ponderosa pine (USDA FS 1986a). Abert’s squirrel 

depends on ponderosa pine for basically all its life necessities and requires diversity of age 

classes and tree densities. Pine twigs, pine cones, pine seeds, pine bark, as well as truffles are 

used by Abert’s squirrel. In addition to pure ponderosa pine stands, Abert’s squirrels are also 

associated with gambel oak, true pinyon, junipers, quaking aspen and Douglas-fir. The Carson 

has an estimated 63,190 acres of ponderosa pine with interlocking habitat crowns. This is an 

increase of almost 20 percent from 1986. The habitat condition for the species is considered poor 

to fair, but in a slight upward trend. The Abert’s squirrel population on the Carson is considered to 

be stable but likely lower than potential. (USDA FS 2003a)

84 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

Hairy Woodpecker

The hairy woodpecker is a forest generalist, keying in on available snags and live aspen. On both 

forests this species is found in areas with abundant snags and downed logs. Nests are primarily in 

trees averaging 17 inches in diameter and approximately 60 feet high. It forages primarily on tree 

trunks averaging 17 inches in diameter and greater than 30 feet high. Down logs are important for 

foraging by providing insects. As noted in Bison-M, a study has found that hairy woodpecker 

densities were negatively correlated with aspen basal area in west-central Colorado. Removal of 

snags, large snags, future snags and down logs increases the probability of decreased population 

numbers of hairy woodpeckers.

The Santa Fe National Forest Plan modeling predicted that hairy woodpecker habitat quality 

would improve over time as young stands mature into diameter classes acceptable as cover. 

Nesting habitat was more limiting than feeding habitat. The Santa Fe National Forest contains an 

estimated 976,231 acres of hairy woodpecker habitat. The trend for habitat on the forest is 

considered stable (USDA FS 2003b). The Carson National Forest estimates 112,444 acres of 

habitat. This is up from 106,880 acres in 1986. The habitat trend on the Carson is considered 

upward (USDA FS 2003a). Population trends on both forests are considered stable.

Red Squirrel

Red squirrels are an indicator species for the mixed conifer habitat type on the Carson National 

Forest. The squirrels require mature coniferous trees as a source of cones and seed. The best cone 

production occurs in 200- to 300-year-old Douglas-fir, 40- to 300-year-old white fir, and 150- to 

200-year-old Engelmann spruce. The more diverse the tree species are, the more likely that the 

cone crop production will exist to sustain red squirrel populations. They are predominantly found 

in areas with greater than 60 percent canopy closure. Red squirrels utilize large diameter trees for 

nests that are located on big branches near the trunks of the tree. They may also use mistletoe 

formations in Douglas-fir. There are an estimated 217,606 acres of red squirrel habitat on the 

Carson National Forest. This is an increase of approximately 20 percent from 1986. The habitat 

condition is rated as relatively good, with an upward trend. The population trend for the Carson is 

considered stable. (USDA FS 2003a)

Rocky Mountain Elk

Rocky Mountain elk inhabit most forest types with good forage and cover. These ungulates utilize 

a variety of habitat types during the course of their life. They appear to be extremely adaptable to 

a variety of successional stages and vegetation types. Certain vegetation types are of limited value 

to elk due to aspect, elevation, snow depth, lack of water availability, and/or vegetation 

components. The Santa Fe National Forest Plan modeling predicted that elk were limited 

primarily by low forage availability. Creating a greater proportion of early-seral stage habitat and 

associated forage improved elk habitat. The Carson National Forest Plan identifies elk as an 

indicator of general forest habitat type. There are an estimated 1,624,026 acres of elk habitat on 

the Santa Fe, and 1,424,074 acres of elk habitat on the Carson. The habitat trend on the Santa Fe 

is rated as stable and increasing on the Carson. The population trend for elk is rated as increasing 

for both forests. (USDA FS 2003a, 2003b)

Merriam’s Turkey

Merriam’s turkey is a management indicator species for both forests. Merriam’s turkey has the 

widest distribution and is the most common subspecies of turkey. It is found in many 

mountainous areas of northern New Mexico. The bird utilizes ponderosa pine, a source of mast 

Final Environmental Impact Statement – Invasive Plant Control Project 85
Chapter 3 • Affected Environment and Environmental Consequences

(nuts and seed) and its favorite roosting tree. The ponderosa pine is an essential component of its 

permanent habitat, while surface water is a range requirement. Turkeys prefer to roost in tall 

mature or overmature ponderosa pines with relatively open crowns and large horizontal branches 

starting at 20 to 30 feet from the ground. Trees with a diameter of over 14 inches are used as 

roosts. These trees must have excellent protection from the wind, and must be located in sites 

with an open ridge or rocky ledge nearby to provide ease in entering and exiting the roost site. 

Hens normally nest within a one-half mile radius of water. A good healthy ponderosa pine 

understory provides the turkey cover as well as forage. Turkeys forage in grasslands, brush 

communities, deciduous tree-brush and in ponderosa pine. They eat grasses and grasshoppers in 

the summer, oak nuts and pine seeds in the fall, and tall grasses in the winter. The Santa Fe 

National Forest Plan modeling determined that feeding habitat was the primary limiting factor for 

turkey and harvest patterns that promoted early-seral stages or provided an open canopy allowing 

grass, forbs and mast providing vegetation were the most beneficial for turkey. The turkey was 

used as an indicator for the presence of old-growth pine in the Carson National Forest Plan. The 

Santa Fe has an estimated 1,314,113 acres of turkey habitat, and the Carson an estimated 301,297 

acres. The Santa Fe rates the habitat trend for turkey as stable; and the Carson rates the trend as 

slightly upward. The Santa Fe MIS report (USDA FS 2003b) rates the turkey population as stable 

to slightly increasing. The Carson MIS report (USDA FS 2003a) indicates an upward trend for 

turkeys on that forest due to transplants into previously unoccupied habitat.

Bighorn Sheep

Rocky Mountain bighorn sheep are indicator species for both forests. These bighorn sheep inhabit 

the cliffs and crags or other extremely rocky areas in tundra and alpine areas from the summit 

peaks to around 200 meters below the treeline of the mountains of northern New Mexico. 

Bighorn prefer precipitous terrain adjacent to suitable feeding sites of high mountain meadows 

with grasses, forbs and browse species. Since bighorn are highly susceptible to the diseases 

carried by domestic sheep, the viability of the species is dependent on whether or not domestic 

sheep are present within their occupied habitat. Currently bighorn sheep occur in the Pecos, Latir 

Peak, and Wheeler Peak Wilderness areas and the Gold Hill area. The Santa Fe National Forest 

Plan estimated habitat capability for bighorn sheep based on the health of alpine and meadow 

areas and effects of encroaching canopy closure. The Carson uses bighorn as an indicator for the 

presence of alpine, subalpine tundra and mountain meadow grassland. There are an estimated 

58,505 acres of habitat on the Santa Fe; and 10,100 to 20,430 acres of habitat on the Carson. 

Habitat trend is considered stable on both forests. The population trend for the Santa Fe is stable 

to increasing. Population trend for the Carson is increasing. (USDA FS 2003a, 2003b)

White-tailed Ptarmigan 

See “TES” section for habitat description.

Pinyon jay

Pinyon jays are an indicator species for the Santa Fe National Forest. Pinyon jays nest mainly in 

stands of pinyon-juniper. It needs open woodlands for nesting and an adequate supply of seeds, 

especially nuts. They are gregarious and breed in colonies up to 150. They spend the winters in 

large flocks of tens or thousands moving in search of pinyon stands with a successful crop of 

pinyon nuts that are a primary food source along with other seeds, fruits and insects. The Forest 

Plan modeling predicted that pinyon jay habitat would improve by increasing foraging areas. 

Alternatives which favored a variety of mast (nut) producing plants found in early-seral stage 

forests were best for pinyon jays. The habitat trend for pinyon jay is ranked as stable on the 

86 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

forest. However, this trend is likely to change to declining in the next MIS assessment due to the 

recent die off of pinyon on the forest due to bark beetles. The population trend for the Santa Fe 

National Forest is ranked as stable to downward, based on the State trend and the breeding bird 

survey routes located near the forest. (USDA FS 2003b) 

Mourning Dove

Throughout the Santa Fe National Forest, mourning dove habitat is abundant. They are found in 

ponderosa pine, spruce-fir, aspen, and pinyon-juniper forest types. Coniferous trees and ground 

sites are preferred in the year before deciduous trees have developed leaves. In all situations, 

however, abundant food and water must be available within 20-30 km. These habitats and 

grassland habitats found on the forest meet the feeding requirements for mourning dove. Water 

developments and underburning in ponderosa pine create favorable feeding areas. Most nesting 

occurs in lower elevation habitats. The abundance of nesting and cover opportunities on the Santa 

Fe contribute to maintaining viable populations of mourning dove. In general, habitat affected by 

disturbance will have the canopy opened up allowing for the growth of more understory 

vegetation, improving mourning dove habitat. The habitat trend for mourning dove is considered 

stable to increasing across the forest. The population trend for mourning dove on the Santa Fe is 

ranked as stable based on the statewide trend and breeding bird surveys in and adjacent to the 

forest. (USDA FS 2003b)

Mexican Spotted Owl 

See “TES” section for a description of habitat for this species.

Affected Environment - Threatened, Endangered, and Sensitive Species

In this section, the threatened, endangered, and sensitive (TES) animal species on the Forests are 

described. TES plant species were addressed in the vegetation section. TES species that are 

strictly aquatic, such as fish and aquatic insects, are addressed in the aquatic section. For purposes 

of this analysis, the affected environment includes the TES species present on the two forests, the 

habitats they occupy, and habitats suitable for occupation. The list of species was developed from 

the USDA Forest Service Region 3 list of sensitive species and letters/information from the U.S. 

Fish and Wildlife Service (USFWS 2000a-c, 2003).

Table 26 lists TES wildlife species that are either known to occupy the Forests or could 

potentially occur based on the habitat on the Forests. It also summarizes their habitat, estimated 

acres of habitat, acres of weed infestations, and probability of occurring in areas planned for 

treatment.

Final Environmental Impact Statement – Invasive Plant Control Project 87
Chapter 3 • Affected Environment and Environmental Consequences

Table 26. Threatened, Endangered and Sensitive Species

Species Status Habitat

Estimated 

Acres of 

Habitat 1

Acres of 

Known Weed 

Infestations 2

Probability 

of TES 

Species 

Occurrence 

in 

Treatment 

Areas

Jemez 

Mountain 

Salamander

Sensitive Forested areas 

surrounding 

Valles Caldera

100,000 500 High

Northern 

Leopard Frog

Sensitive Associated with 

water

147,300 2,520 High

Western 

Boreal Toad

Sensitive

(Candidate)

High elevation 

lakes and forest

0 (possibly 

extirpated 

from New 

Mexico)

0 Low

Southwestern 

Willow 

Flycatcher

Endangered Low gradient 

riparian with 

open water and 

well developed 

willow patches

<10,000 <500 Moderate

Bald Eagle Threatened Primarily 

riparian areas 

along major 

river corridors

<100,000 <1,500 High

Mexican 

Spotted Owl

Threatened Old growth and 

mature mixed 

conifer habitat

<30,000 in 

PACs

<500,000 in 

potential 

habitat

<1 Acre in PACs

<2,000 acres in 

potential habitat.

Low

Least tern Endangered Wetlands (Does 

not nest on 

forest)

0 0 Low

American 

Peregrine 

Falcon

Sensitive Associated with 

cliffs

<100,000 <1,000 Low

Northern 

Goshawk

Sensitive Most forested 

habitats except 

pinyon-juniper

<50,000 in 

PFAs

2,441,000 in 

potential 

habitat

1,250 in PFAs

3,480 in 

potential habitat

High

Boreal owl Sensitive High elevation 

spruce-fir 

forests

422,800 100 Low

White-tailed 

ptarmigan

Sensitive Alpine areas 78,900 5 Low

88 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

Species Status Habitat

Estimated 

Acres of 

Habitat 1

Acres of 

Known Weed 

Infestations 2

Probability 

of TES 

Species 

Occurrence 

in 

Treatment 

Areas

Western 

Yellow-billed 

Cuckoo

Sensitive 

(Candidate)

Riparian areas 

along river 

systems

<100,000 <1,500 Low

Blue-black 

silverspot 

butterfly

Sensitive Wet alpine 

meadows

<5,000 Unknown but 

low probability 

due to limited 

weed infestations 

at high 

elevations

Low

Goat peak 

pika

Sensitive Talus slopes in 

the Jemez 

Mountains

<10,000 Unknown but 

low probability 

of weed 

infestations due 

to habitat type

Moderate

New Mexico 

jumping 

mouse

Sensitive Wet meadows in 

the Jemez and 

Sangre de Cristo 

Mountains

<10,000 <100 Moderate

Southwestern 

river otter

Sensitive Large Rivers 

(Currently not 

present in New 

Mexico)

0 (Extirpated 

from New 

Mexico)

0 Low

Swift fox Sensitive Short and mid 

grass prairie

381,700 1,290 Moderate

Linnaeus 

Ramshorn 

snail

Sensitive Seasonal ponds 

(Coyote Creek 

Near Carson)

0 (Only known 

location is not 

on the Forests)

0 Low

1 Acres of habitat are based on a combination of habitat type, known areas of occupancy, and/or proximity to habitat 

features.

2 Acres of weed infestations are based on currently known populations. Forest-wide surveys have not been completed 

and weed populations are expanding.

The following section provides some additional information about TES species habitats on the 

two forests.

Jemez Mountains Salamander (Plethodon neomexicanus)

The Jemez Mountain salamander is endemic to the Jemez Mountains in portions of Los Alamos, 

Sandoval, and Rio Arriba Counties. They occur in and under rotting coniferous logs or under 

rocks in coniferous forests where they feed upon invertebrates including ants and beetles 

(BISON-M 2001).

Final Environmental Impact Statement – Invasive Plant Control Project 89
Chapter 3 • Affected Environment and Environmental Consequences

Northern Leopard Frog (Rana pipiens)

Northern leopard frogs occur between 1,120 and 3,050 meters elevation in New Mexico. They 

can be found on both the Santa Fe and Carson National Forests. They are found associated with 

ponds, streams and other permanent water. Threats to local populations include changes in 

wetlands, especially the alteration of marshy ponds to reservoirs; stocking of predatory fish; 

natural local extinctions as ponds dry up during years of low precipitation; and predation and 

competition by introduced bullfrogs (BISON-M 2001).

Western Boreal Toad (Bufo boreas boreas)

The Western boreal toad is found in coniferous forest of Engelmann spruce, subalpine fir, 

Douglas-fir and lodgepole pine. It lives near springs, streams, ponds and lakes in foothill 

woodlands, mountain meadows, and moist, subalpine forest. In New Mexico, the species appears 

to be exclusively a high mountain form (i.e., above 2,600 m), and it is usually associated with 

beaver ponds. It is totally dependent on standing or running water for breeding. The western 

Boreal toad is not abundant over much of its extensive range. However, in New Mexico the 

species was quite peripheral and probably of low population density. It was first discovered in the 

State at Lagunitas Lakes in 1968. A second population was documented at Canjilon Lakes in 

1974, with a third found at Trout Lakes in 1978. Recent surveys indicate it is possible that the 

species has declined in New Mexico in recent years and is possibly extirpated. Any resource 

management activities that negatively affect alpine wetlands will negatively affect breeding 

habitat for boreal toads (BISON-M 2001). The Carson National Forest is working with the New 

Mexico Department of Game and Fish on potential reintroductions of boreal toad in the 

Lagunitas, Canjilon and Trout Lakes areas.

Southwestern Willow Flycatcher (Empidonax traillii extimus)

This federally endangered bird nests in dense riparian vegetation including box elders, saltcedar, 

and willows. Nest sites have been found in pure stands of saltcedar in New Mexico. However, the 

species prefers more diverse native riparian vegetation that includes willow and cottonwood. 

Suitable nesting habitat is in patches of vegetation that are more than 10 feet in diameter. Nest 

sites are located in close proximity to water. The Southwestern willow flycatcher is an 

insectivore. It is known to occur in Rio Arriba and Sandoval Counties (BISON-M 2001).

Bald Eagle (Haliaeetus leucocephalus)

Bald eagles nest in large trees in close proximity to rivers, lakes, or reservoirs. Night roost trees 

may be found in protected sites such as canyons in areas that include the Pecos Valley. Bald 

eagles winter in many areas of New Mexico including Taos, San Miguel, Sandoval, and Rio 

Arriba Counties (BISON-M 2001).

Mexican Spotted Owl (Strix occidentalis)

The Mexican spotted owl’s nesting and roosting habitat is characterized by steep topography, cool 

shady canyons, and mature mixed conifer forest having high canopy closure. Protected activity 

centers (PACs) are established to protect territories of individual Mexican spotted owl (MSO). 

Owls also use ponderosa pine and other vegetation types for foraging. On the Santa Fe National 

Forest there are 303,063 acres of MSO mixed conifer habitat (USDA FS 2003b). The Carson has 

very limited areas that are suitable for MSO (USDA FS 2003a). Currently there is less than 1 acre 

of weeds known to exist in PACs. Approximately 5,153 acres of weeds are located in mixed 

conifer habitat.

90 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

Least Tern (Sterna antillarum)

The interior least tern occurs in small remnant colonies along major river systems in the 

midwestern United States and winters in South America. In New Mexico, the least tern is a rare 

summer resident at wetland areas and nests only at or near Bitter Lake National Wildlife Refuge. 

(BISON-M 2001).

American Peregrine Falcon (Falco peregrinus)

The peregrine falcon lives at 6,500 to 9,000 feet in mixed conifer, ponderosa pine, and spruce-fir. 

They nest on high cliffs near water and forage over a very large area. Nesting cliff sites exist on 

both forests. Under the interagency agreement (USDA FS 1991) for peregrine falcon, a site plan 

is developed for each nesting area. Protective zones of sensitivity (A-D) are established in 

roughly concentric circles around these areas, and protective requirements are identified for each 

zone. (BISON-M 2001).

Northern Goshawk (Accipiter gentiles)

The northern goshawk in the Southwest occurs mainly in ponderosa pine forests, but also in 

mixed-conifer and spruce-fir. Foraging habitat consists of a mosaic of forest clearings, densely 

forested areas, and relatively open areas with grasses, forbs and shrubs. Nest areas are stands with 

large trees and relatively high canopy cover of 50 to 60 percent or higher (Reynolds, et al. 1987).

Inventories have been conducted on portions of northern goshawk habitat on both forests. The 

Forests establish post-fledgling areas (PFA) and foraging areas (GFA) around each goshawk 

nesting site. There are numerous PFAs and GFAs scattered throughout both forests. 

Approximately 1,243 acres of weeds are found in PFAs for northern goshawks. An estimated 

1,243 acres of weeds are found in habitat types preferred by the goshawk.

Boreal Owl (Aegolius funereus)

The Boreal owl has been found in small numbers on both the Santa Fe and Carson National 

Forests. Throughout its range, the Boreal owl occurs mainly above 2,900 m in climax spruce-fir

forests. The boreal owl is associated with relatively inaccessible tracts of high elevation 

coniferous forest, especially mature to old-growth spruce and fir. The Boreal owl is a secondary 

cavity nester and is dependent upon large cavities created by woodpeckers. Surveys in New 

Mexico indicate that present quantities of spruce-fir habitat in the isolated mountain ranges of 

New Mexico and Arizona are inadequate to host viable populations of Boreal owls. It seems the 

largely mixed conifer habitat of the mountain ranges peripheral to the Rockies (in these states) are 

more favorable for Northern saw-whet owls than Boreal owls. Recent New Mexico Department

of Game and Fish assisted surveys found this species to be resident in very small numbers in 

spruce-fir and similar habitats in the San Juan, Sangre de Cristo, and Jemez Mountains (BISONM 2001).

White-tailed Ptarmigan (Lagopus leucurus)

The white-tailed ptarmigan serves as an indicator species on the Carson National Forest. It is used 

as an indicator species for the presence of alpine tundra and subalpine deciduous shrub (USDA 

FS 1986a). It is also on the Region 3 sensitive species list. Little is known about this avian 

species in New Mexico, for it lives on the windswept tundra above 11,000 feet. The presence of 

high elevation shrubby willows (Salix spp.) is likely the most important factor for successful over 

wintering of the species. Buds and twigs of various species of willow provide the bulk of the food 

eaten by white-tailed ptarmigan. The shrubs should reach a minimum height of 0.5 meters. In 

Final Environmental Impact Statement – Invasive Plant Control Project 91
Chapter 3 • Affected Environment and Environmental Consequences

areas where willow is not readily available, alder catkins become the dominant dietary component 

along with some needles of spruces, pines and firs.

In New Mexico, white-tailed ptarmigan exist only on the peaks of the Sangre de Cristo Mountains 

from the vicinity of Santa Fe northward to the Colorado border. There are approximately 10,106 

acres of suitable alpine tundra on the Carson. On the Santa Fe, ptarmigan habitat approximately 

coincides with the habitat for bighorn sheep, as ptarmigan were reintroduced into the Pecos 

Wilderness in 1981. Ptarmigans are also considered to be present on Costilla, Latir, Wheeler, 

Truchas and associated peaks. The actual population and trend for this species in New Mexico is 

unknown, due to limited information available at this time (BISON-M 2001).

Western Yellow-Billed Cuckoo (Coccyzus americanus)

Yellow-billed cuckoos breed in riparian woodlands and similar habitats at lower (2,800-5,500 

feet) to middle (5,000-7,500 feet) elevations. It occurs at elevations where stream conditions 

provide sufficient permanent moisture for emergent plants or for a narrow band of deciduous 

trees and shrubs: at low elevation characterized by cottonwood and sycamore, at mid-elevation by 

white alder and bigleaf maple, and at high elevation by willow. Populations fluctuate substantially 

in response to fluctuations in caterpillar abundance. Declines resulting from loss or disturbance of 

riparian habitat have been consistently reported in the West: the greatest factors affecting the 

yellow-billed cuckoo have been the invasion of exotic woody plants into Southwest riparian 

systems, and clearing of riparian woodlands for agriculture, fuel, development, and attempts at 

water conservation (BISON-M 2001).

Blue-black Silverspot Butterfly (Speyeria nokomis nokomis)

This butterfly is an inhabitant of wet alpine meadows and seeps. It is unknown if this species 

occurs on the Forests, but there is suitable habitat present (BISON-M 2001).

Goat Peak Pika (Ochotona princeps nigrescens)

The goat peak pika inhabits volcanic talus slopes in the Jemez Mountains at elevations above 

approximately 8,800 feet. This species is an herbivore (BISON-M 2001).

New Mexican Jumping Meadow Mouse (Zapus hudsonius luteus)

The New Mexican jumping mouse occurs in streamside vegetation that is dense and diverse with 

grasses, sedges, and forbs. This species is known from the Jemez and Sangre de Cristo 

Mountains. They are active June-August (BISON-M 2001).

Southwestern River Otter (Lutra canadensis sonorae)

The southwestern river otter inhabits permanent water sources with high quality water and low 

sediment loads. This species feeds upon fish and crustaceans. Southwestern otters utilize den sites 

that include rock piles, vegetation, and natural cavities which may be located up to one-half mile 

from the water body. This species may have been extirpated from New Mexico, although there 

have been sightings reported without verification in Taos County (BISON-M 2001).

Swift Fox (Vulpes velox)

Swift fox has been recorded from San Miguel and Mora Counties. They could occupy small 

portions of the Santa Fe and Carson forests. Swift foxes have been found to inhabit Plains-Mesa 

Sand Scrub and grasslands habitat in New Mexico. It occupies shortgrass and midgrass prairies 

over most of the Great Plains. Swift and kit foxes are grassland and desert species, most common 

92 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

where soft soils support large populations of rodents, especially kangaroo rats, on which these 

foxes prey. Factors implicated in the decline of this fox have been intense trapping pressure, 

destruction of prairie habitat, rodent control programs, indiscriminant hunting, and capture by 

dogs (BISON-M 2001).

Linnaeus Ramshorn Snail (Gyraulus crista)

Linnaeus' ramshorn snail has a circumboreal distribution and, consequently, the species is found 

in a variety of habitat types (BISON-M 2001). In general, it is most common and characteristic of 

seasonal ponds—although also occurring rarely or sporadically in permanent water sites. In 

Michigan, this snail was found to be most active in spring in a temporary pond, spending the 

remainder of the time buried in the mud bottom (BISON-M 2001). The known location in New 

Mexico, which represents the southernmost known station in North America, is along Coyote 

Creek, a montane stream at about 2,680 meters. There the species was found in a single, pondlike backwater of the creek, but it may be more widespread in the area (BISON-M 2001).

Affected Environment - Migratory Birds

To meet Presidential Executive Order 13186 (January 2001) that emphasizes conservation of 

neotropical migratory birds, the Forest Service analyzes impacts of proposed forest management 

activities by addressing the following: (1) effects to “highest priority” species as identified by 

New Mexico Partners in Flight, (2) effects to important bird areas and (3) effects to important 

over wintering areas.

New Mexico Partners in Flight considers eight risk factors in identifying conservation priority 

species: (1) Global Abundance; (2) New Mexico Breeding Abundance; (3) Global Breeding 

Distribution; (4) New Mexico Breeding Distribution; (5) Threats to Breeding in New Mexico; (6) 

Importance of New Mexico to Breeding; (7) Global Winter Distribution; and (8) Threats on the 

Wintering Grounds. Species with the highest risk factors are classified as “highest priority” for 

conservation action. This evaluation addresses general effects to migratory birds, and specific 

effects to highest priority species for the main habitat types found in the project area.

Currently there are no designated important bird areas on the Forests. There are two areas that 

have been proposed for inclusion into the Important Bird Area system. These areas are the Chama 

River Gorge from El Vado to the north end of Abiquiu Reservoir, and the Caja del Rio and the 

Santa Fe River Canyon below the Caja del Rio.

Important over wintering areas are often large wetlands. The areas considered important on the 

Forests include the Rio Chama and Rio Grande corridors.

Table 27 lists high priority migratory bird species that are either known to occupy the Forests, or 

are likely to occur based on the habitat on the Forests, based on Partners in Flight (Web site) and 

potential habitat on the Forests. It also summarizes their habitat, estimated acres of habitat, acres 

of weed infestations, and probability of the bird species occurring in weed treatment areas.

Final Environmental Impact Statement – Invasive Plant Control Project 93
Chapter 3 • Affected Environment and Environmental Consequences

Table 27. Migratory Bird Habitat and Probability of Occurrence in Treatment Areas

Highest Priority 

Species

Primary 

Habitat

Estimated 

Acres of 

Habitat

Acres of 

Known 

Weed 

Infestations1

Probability of 

Occurrence in 

Treatment 

Areas

Black Swift

High elevation 

riparian 

woodland

~100,000 ~2,000 High

Red-naped sapsucker

Hammond’s Flycatcher

American Dipper

Veery

MacGillivray’s Warbler

Brown-capped rosy finch

Alpine Tundra 78,900 5 Low

White-tailed ptarmigan

Williamson’s sapsucker

Olive-sided flycatcher Mixed Conifer 553,900 1,910 High

Dusky flycatcher

Ferruginous hawk

Pinyon-juniper 823,900 350 High

Gray vireo

Black-throated gray 

warbler

Gray flycatcher

Bendires thrasher

Ferruginous Hawk

Plains and Mesa 

Grassland 236,200 1,252 High

Prairie Falcon

Bendires Thrasher

Long-billed curlew

Lark bunting

Lewis’s woodpecker Middle 

elevation 

riparian 

woodland

~50,000 ~1,000 High

Red-headed woodpecker

Blue grouse Spruce-fir 422,800 100 Low

Boreal owl

Flammulated owl

Virginia’s warbler Ponderosa pine 640,500 1,120 High

Grace’s warbler

94 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

Highest Priority 

Species

Primary 

Habitat

Estimated 

Acres of 

Habitat

Acres of 

Known 

Weed 

Infestations1

Probability of 

Occurrence in 

Treatment 

Areas

Bendire’s thrasher

Great Basin 

Desert Shrub 145,500 40 Moderate

Sage sparrow

Loggerhead shrike

Sage thrasher

MacGillivray’s warbler

Montane shrub 22,700 40 Moderate

Green-tailed towhee

Black swift

Cave/Rock/Cliff ~10,000 0 Low

Prairie falcon

1 Acres of weed infestations are based on currently known populations. Forest-wide surveys have not been completed 

and weed populations are expanding

Environmental Consequences - Wildlife (General) 

This section describes effects to all wildlife species, including mammals, birds, reptiles, and 

amphibians. The analysis focused on the key issues identified in Chapter 1, related to how the 

weed control project activities may cause: habitat disturbance (noise and visual disturbance), 

negative health impacts from herbicides used, or impacts to habitat quality from reductions in 

existing surface vegetation.

Alternative A (No Action)

As described in the “Vegetation” section of this FEIS, without control treatments, weeds would 

continue to reduce the abundance and diversity of native vegetation that provides habitat for 

native wildlife species. For wildlife species that rely on that habitat, a decline in habitat quality 

would occur. For species that do not rely on the displaced habitat, no effect would occur.

The No Action Alternative would allow weed populations to expand on and near the 7,350 acres 

proposed for treatment. The anticipated expansion rates vary between 5 and 30 percent annually 

(see “Vegetation Resources” section), dependent on the weed species and ecologic conditions at 

each infestation site. The anticipated effects of weed infestations on wildlife are typically a result 

of the loss of suitable habitat and the displacement of native forage. Large areas of monocultures 

of weeds can develop and biological diversity can be lost. The effects can ripple through the 

system causing habitat structure changes that can alter ecosystem interactions. Natural habitat for 

wildlife would be reduced, such as nesting and ground cover, grass production, seed producing 

food sources, and prey base. These effects can negatively affect populations of many big game, 

predator, small mammal, bird, reptile, and amphibian species.

Weed infestations have had documented detrimental impacts to wildlife, especially big game 

species that occupy foothill and mountain slopes as important winter range. For example, in 

Colorado the invasion of Russian knapweed has resulted in a large reduction in the availability of 

winter range for wildlife. It was estimated that there would be a loss of 220 elk annually in 

Montana due to weed invasions of big game winter ranges (FICMNE 1998). In Arizona, stands of 

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Chapter 3 • Affected Environment and Environmental Consequences

the weed Lehmann lovegrass have fewer quail, small mammals, and seed-harvesting ants 

(FICMNE 1998).

Alternative B (Integrated Methods)

The key effect this alternative would have is an overall improvement in wildlife habitat

conditions. Weeds would be eradicated or controlled on the acres treated, thus allowing for the 

restoration of native vegetation and improvements in biological diversity. The improvement 

would be seen mostly for wildlife species that rely on the displaced habitat. As weeds are 

removed, these species would benefit from the native, more usable habitat.

The treatment methods themselves pose a low risk to individual animals and no effect to 

populations. A small percentage of the 3 million acres on the Forests would be treated in a given 

year (a maximum of about 1,500 acres), and those acres would be widely distributed across the 

Forests. Many weed treatments would occur along roadsides and recreation sites that are 

frequently disturbed and receive little use by wildlife. The following describe effects specific to 

the key wildlife issues identified, considering all wildlife species including management 

indicators, special status species and migratory birds. In addition, a species-specific effects 

analysis for those particular groups of species is contained in subsequent sections.

Habitat Disturbance Effects: Disturbance in each treatment area would occur during both 

treatment and monitoring activities. Disturbance from vehicles, including trucks, offhighway vehicles, and humans on horseback or foot would increase during the activity 

periods. Effects of noise on wild animals can be classified as those affecting auditory 

physiology and sensory perception, those affecting behavior, and those affecting 

populations. Noise levels are expected to marginally increase with activity around the 

subject treatment areas for a very short period of time. As a result of increased human 

activity and noise from operation of vehicles and activities, some animals would avoid the 

local area during the period of treatment activity. However, due to the brief duration of the 

exposure, they would likely quickly resume their normal behavior after treatments were 

completed.

Fluctuating noise levels may elevate heart rate, catecholamine levels, and corticosteroid 

levels in wild animals, but these elevated levels are generally of short duration, and animals 

often habituate to these disturbances over time. Short-term increases in these measures do 

not correlate well with actual stress experienced by animals. As most wildlife would avoid 

the areas during treatment activities, this behavior would indirectly reduce the risk of direct 

herbicide exposure to those animals.

The mechanical methods (mowing, tilling), broadcast burning treatments, and vehiclemounted herbicide applications would cause the most noise disturbance while release of 

biological controls would cause little to no noise disturbance. Manual methods, controlled 

grazing, and manual application of herbicides would cause minimal noise and habitat 

disturbance. Typically, the duration of traffic would be limited to 1 or 2 days and once 

complete, wildlife would return to these areas. The level of affect also depends on the 

current level of background noise for an area. Since many areas with weed infestations are 

near roads, trails and high use recreation sites, wildlife that use these areas should be 

habituated to human use. Overall, habitat disturbance from treatments would not be 

expected to adversely impact wildlife species or populations.

96 Final Environmental Impact Statement – Invasive Plant Control Project
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Habitat Modification Effects: All treatment methods aim to have some impact on the 

vegetation in an area. In most cases, the changes in vegetation structure would be slight 

because the target weeds make up only a small part of that structure. In some cases, 

changes in the habitat structure could be significant if the target plant species (such as 

saltcedar) is dominant. These changes would benefit wildlife species, such as southwest 

willow flycatcher, that rely on a more diverse habitat structure.

Weed treatments would cause temporary and localized reduction in existing vegetation, 

including some native vegetation that could be killed or removed along with the weeds. 

This would not measurably impact wildlife habitat qualities, due to the relatively small 

acreages that would be treated in a given time and location, and the mitigation measure that 

requires prompt revegetation of treated sites. Ground cover vegetation would be expected 

to return by the first growing season after treatment, and the natural abundance and 

diversity of vegetation would gradually return over subsequent growing seasons.

Each method would have a slightly different and minimal effect on the structure and 

composition of wildlife habitat. None of the treatments would result in a loss of large trees, 

snags, or down log habitat components that are important for many species.

Controlled grazing with sheep or goats would change the structure of vegetation, but the 

magnitude of this change would be small. Risks to bighorn sheep would be avoided by 

restricting grazing in bighorn sheep areas.

Biological controls (introduction of insects) would not adversely affect habitat or wildlife 

since they have been studied to ensure that they are plant-host specific. Thus the insects 

would not impact native vegetation or other beneficial insects.

Manual methods of weed control such as hand pulling, cutting or digging would result in 

minimal changes in wildlife habitat quality, especially when conducted on such a small 

scale and spread widely across the Forests.

Mechanical methods would primarily involve mowing along existing road rights-of-way, in 

conjunction with roadside mowing done by other jurisdictions. Other mowing or 

mechanical weed treatments would not result in any major alteration in habitat quality. 

Burning of individual weeds with a propane torch would leave the remaining habitat 

structure and composition intact.

Broadcast burning weed infestations in grasslands or similar habitats conducive to burning 

would result in a minor and temporary change to the seral stage and vegetative community. 

A controlled surface burn would result in little, if any, loss of large snags or down logs, so 

would not impact the habitat trend or populations of snag dependent species such as hairy 

woodpecker.

Herbicide use impacts on vegetation structure depend on the specific application method, 

type of herbicide, rate of application, and season of application. Effects of herbicide 

application would be a change in composition of forbs, grasses, and shrubs in treatment 

areas. Nontarget plants could be damaged by unintentional application, drift, or residual 

soil activity of herbicides. These short-term impacts to plant composition and community 

diversity would likely be offset within as little as the first growing season. There would be 

no long-term loss of species diversity of native vegetation due to the proposed treatments, 

Final Environmental Impact Statement – Invasive Plant Control Project 97
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and species composition under most treatments is expected to resemble native plant 

assemblages within 1 to 3 years. For additional discussion relative to vegetation, see the 

“Vegetation Resources” section.

Herbicide Toxicity Effects: Risk assessments of the herbicide formulations proposed for 

use have considered the risk of harm that could be caused by their use. Appendix 3 

provides a more detailed discussion of these risks to a number of wildlife species (USDA 

FS 1992, SERA 1995, SERA 1996, SERA 1997, SERA 1998a, SERA 1998b, SERA 1999a, 

SERA 1999b, SERA 2000, SERA 2001, SERA 2002, SERA 2003a, SERA 2003b, SERA 

2003c, SERA 2004a, SERA 2004b, SERA 2004c, SERA 2004d, SERA 2004e, SERA 

2004f). The risk assessments concluded that potential risks of harm to most wildlife species 

are low for herbicide formulations proposed for use, at the rates proposed and given the 

application methods proposed.

Factoring in each formulations’ inherent toxicity, each herbicide was evaluated for risk by 

comparing the estimated exposure level with the “No Observable Adverse Effect Level” 

determined through available study information or extrapolation from study information. 

Risk was found to be low for all wildlife species using any of the proposed herbicide 

formulations, except for the effects to aquatic organisms caused by certain formulations of 

glyphosate and triclopyr, and all formulations of picloram. Risk assessments indicate that 

the proposed formulations of herbicides are either nontoxic or of low toxicity to birds, 

mammals, and insects. The risk assessments also indicate that none of the herbicide 

formulations proposed for use have been shown to cause cancer, birth defects, genetic 

defects, or problems with fertility or reproduction. Although a contaminate in two of the 

herbicides has links with cancer (hexachlorobenzene found in picloram and clopyralid), the 

risk assessments indicate that there are no direct links of the herbicides themselves. The 

risk assessments, nonetheless, analyze the risk of cancer from exposure to 

hexachlorobenzene to be less than 1 in a million.

The risk assessments found no evidence of synergistic effects or hormone disruption from 

these chemicals (SERA 1995, SERA 1996, SERA 1997, SERA 1998a, SERA 1998b, SERA 

1999a, SERA 1999b, SERA 2000, SERA 2001, SERA 2002, SERA 2003a, SERA 2003b, 

SERA 2003c, SERA 2004a, SERA 2004b, SERA 2004c, SERA 2004d, SERA 2004e, SERA 

2004f). Tests on the herbicide formulations include other ingredients (also referred to as 

“inert” ingredients). Risk assessments also evaluate the surfactants contained in the product 

used. For example, glyphosate with the surfactant “POE” shows high impacts to aquatic 

systems, amphibians in particular. This product, “Round Up” is, therefore, not proposed for 

use in riparian systems where aquatic effects could occur. On the other hand, a glyphosate 

formulation without “POE” is sold under the brand name of “Rodeo” and it is registered for 

use in or near these systems.

Thus, the herbicides proposed for use, when used at the application rates and concentrations 

listed on the labels, would have a very low risk of causing harm (short or long term) to 

wildlife species.

There is a general lack of data and some uncertainty relative to herbicide effects on 

amphibians, so there is the potential for an unquantifiable negative impact on amphibians 

from herbicide application. Based on mitigation measures and the risk assessment 

information, it is anticipated that there would be a low risk that the proposed herbicide use 

98 Final Environmental Impact Statement – Invasive Plant Control Project
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would be toxic to amphibians. Mitigations are required that minimize herbicide delivery in 

or near water bodies, limit the amount of herbicide used within a given watershed, and limit 

the type of application permitted in riparian areas. Also, the extent of proposed herbicide 

treatments within potential amphibian habitat areas is small. If herbicides were to impact 

individual amphibians on a local basis, it would not affect the population as a whole. 

Appendix 3 describes the herbicides and wildlife risk assessment in more detail.

Population or habitat trends would not be impacted for any of the wildlife species that 

occur on the Forests. 

Alternative C (No Herbicides)

Implementation of this alternative would improve native vegetation and help maintain or improve 

biological diversity, by suppressing, containing or eradicating weeds on treatment areas. 

However, given the same level of funding as Alternative B, the effectiveness of each treatment 

application would be less than Alternative B. For a number of weed species that resprout from 

roots left after mechanical/manual treatments (e.g. Canada thistle or spotted knapweed), even a 

greater number of return treatments would probably not be highly effective at reducing 

populations. The site objectives for a given area would require concentrated effort over several 

years. In the places where weed treatments are not successful, or if the spread rate of weeds 

continues to exceed the rate of control, the long-term effects would be similar to Alternative A 

(No Action). Thus, the beneficial improvements to native vegetation and wildlife habitat would 

be lower for this alternative.

Short-term disturbance effects and habitat alteration effects to wildlife would be the same as 

described for Alternative B, except there would be more repeat treatments to achieve the 

objective so recovery of native vegetation would probably take longer. The difference with this 

alternative is the elimination of the (low) risk to individual animals posed by herbicide toxicity 

effects.

Alternative D (Herbicides Only)

As with Alternatives B and C, implementation of this alternative would improve native vegetation 

and help maintain biological diversity by suppressing, containing or eradicating weeds on 

treatment areas. Some species of weeds do not respond to treatments that apply herbicides alone 

so for these sites a number of return treatments could be necessary, and expected effectiveness in 

meeting objectives would fall between Alternatives B and C.

Effects of this alternative associated with the key issues raised would be very similar to those 

described for Alternative B. One difference would be eliminating the risk to individuals posed by 

mechanical treatments. The level of noise and habitat disturbance would be slightly less than 

either Alternative B or C as the use of herbicides would result in a reduced need for repeat 

treatments on many sites.

Cumulative Effects - All Wildlife

The cumulative effects area for wildlife includes the two forests and immediately adjacent lands. 

Weeds are spread over both forests, from low elevation to high elevation and in nearly all habitat 

types. Weeds are spreading on surrounding private, Federal, State and county lands. Thus the 

effects of this project have the potential to interact with the whole suite of actions occurring on 

the Forests and surrounding lands. Actions considered that would have similar effects are listed in 

Final Environmental Impact Statement – Invasive Plant Control Project 99
Chapter 3 • Affected Environment and Environmental Consequences

the beginning of this chapter. Foreseeable future impacts on wildlife include increasing recreation 

on public land, increasing off-road vehicle use such as snowmobiles and ATVs, increasing 

potential for catastrophic fire, and continued spread of weeds.

Current disturbance to wildlife would have a cumulative effect throughout the Forests and on 

adjacent land caused by management activities, including disturbance from recreational uses, 

ranching, special uses, construction activities, and off-road motorized uses in summer and winter. 

As other agencies and private landowners continue to treat weeds in areas adjacent to the forest, 

wildlife would be exposed to short-term and localized habitat disturbance and to herbicides 

associated with those treatments. Those effects from other ongoing and foreseeable future 

activities would add to the effects predicted for each alternative.

The weed infestations occupy less than one-half of one percent of the Forests acreage and are 

well dispersed. Treatment projects will be spread out in both time and space. The actual direct and 

indirect effects of each alternative on MIS, TES and migratory bird species are predicted to be of 

such low magnitude that they cannot be measured. In all action alternatives, treatment in specific 

species habitat is limited to less than one-tenth of one percent of the habitat for any one species. 

The addition of this amount of disturbance to that caused by other activities will not be 

measurable.

Although some individual animals may be affected (primarily through short-term disturbance 

effects), no impacts to population or habitat trends is predicted, even when considering this 

project’s impacts in addition to other impacts occurring in the project area.

Environmental Consequences - Management Indicator Species

Effects previously described for all wildlife habitat and populations on the Forests apply to 

management indicator species. Table 28 provides additional disclosures of estimated effects of 

each alternative for each specific management indicator species on each forest.

Table 28. Effects to Management Indicator Species

Management 

Indicator 

Species

Alternative A 

(No Action)

All Weed Management Alternatives:

B, C, D

Brewer’s 

Sparrow

Weeds would continue 

to have little to no 

affect on sagebrush 

habitat used by this 

species.

Weed treatments would have little affect because 

the sagebrush component is not heavily threatened 

by weeds. No impacts to population or habitat 

trends are expected.

Juniper 

Titmouse

Weeds would continue 

to reduce seed and 

insect production in the 

understory, affecting 

food for this species. 

Weed treatments would benefit seed and insect 

production in the understory over the long term. 

Some loss of vegetation in the short term could 

cause temporary displacement. No impacts to 

population or habitat trends are expected.

Abert’s 

Squirrel

Weeds would not 

affect larger trees used 

by Abert’s squirrel.

Weed treatments would not affect larger trees used 

by Abert’s squirrel. Changes in understory structure 

would not affect population or habitat trends.

100 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

Management 

Indicator 

Species

Alternative A 

(No Action)

All Weed Management Alternatives:

B, C, D

Hairy 

Woodpecker

Weeds would not 

affect snags and down 

logs important to hairy 

woodpecker. 

Weed treatments have low potential to cause a loss 

of large snags or down log habitat components. 

Changes in understory structure would not affect 

population or habitat trends.

Red Squirrel Weeds would not 

affect mature mixed 

conifer trees used as 

primary red squirrel 

habitat. 

Weed treatments would not affect mature mixed 

conifer trees used as primary red squirrel habitat. 

Changes to understory structure would not affect 

population or habitat trends.

Rocky 

Mountain 

Elk

Weeds would continue 

to displace grasses 

used as elk forage so 

habitat would decline 

in quality and quantity.

Weed treatments would result in improving elk 

foraging habitat. No impacts to population or 

habitat trend are expected.

Merriam’s 

Turkey

Weeds would continue 

to displace native 

plants, grasses and 

insects used by 

turkeys, so habitat 

quality would decline. 

Weed treatments would result in improving native 

grasses and other surface vegetation so would 

improve turkey habitat. No impacts to population or 

habitat trend are expected.

Rocky 

Mountain

Bighorn 

Sheep

Weeds would continue 

to be very limited in 

high elevation bighorn 

sheep habitat so there 

would be little impact 

on their habitat.

Weed treatments would only improve bighorn 

sheep habitat to a small degree. Avoiding domestic 

sheep/goat grazing in bighorn habitat would avoid 

introducing disease to the bighorn sheep 

population. No impacts to population or habitat 

trend are expected.

Pinyon Jay Weeds would continue 

to be very limited in 

pinyon pine habitat, so 

there would be little to 

no effect. 

Weed treatments would not affect pinyon pine trees 

used by pinyon jay. Changes to understory structure 

would not effect population or habitat trends.

Mourning 

Dove

Weeds would continue 

to displace native 

habitat in a wide 

variety of habitats that 

this species depends 

upon. 

Weed treatments would restore native vegetation 

that this species uses. Since the dove uses a wide 

variety of habitats, changes to understory structure 

would not affect population or habitat trends.

Environmental Consequences - Threatened, 

Endangered, Sensitive (TES) Species

Effects previously described for all wildlife habitat and populations on the Forests apply to TES 

species. Table 29 provides additional disclosures of estimated effects of each alternative for each 

specific TES species on each forest. Effects are generally the same for all action alternatives other 

than the minor differences noted in the general wildlife effects, such as the slower rate of native 

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Chapter 3 • Affected Environment and Environmental Consequences

vegetation recovery under Alternative C. Also under Alternative C, the low risk of impacts to 

individual animals from herbicides would be eliminated, and under Alternative D, the low risk of 

impacts to individual animals from mechanical treatments would be eliminated. Action 

alternatives would not be likely to affect any species of threatened or endangered species (USDA 

FS 2005, USFWS 2005).

Table 29. Effects to TES Species and Habitats

TES Species Alternative A 

(No Action)

All Weed Management Alternatives:

B, C, D

Jemez 

Mountain 

Salamander 

(S)

Weeds would have no 

impact to rotting logs 

and undersides of rocks 

that salamanders 

depend on.

Treatments would have no impact to the logs and 

rocks that salamanders depend on; logs and rocks 

would not be removed. There is a low risk that 

some individual salamanders could be impacted by 

herbicides or mechanical treatments. No impacts to 

population or habitat trends are expected.

Northern 

Leopard

Frog (S)

Weeds would continue 

to expand and displace 

native vegetation in 

riparian areas and 

around ponds, which 

would reduce habitat 

quality and tend to dry 

out these wet areas.

Treatments would improve and increase native 

vegetation in riparian areas, wetlands and pond 

areas. Replacing saltcedar with native willows 

would benefit the leopard frog and help retain 

more water in these wet areas. No impacts to 

population or habitat trends are expected.

Western 

Boreal Toad 

(S/C)

Weeds would not 

preclude boreal toad 

reintroduction in 

potential sites.

Treatments would not preclude boreal toad 

reintroduction into suitable habitat. 

Southwestern 

Willow 

Flycatcher 

(E)

Weeds would continue 

to displace native 

riparian vegetation. 

While the flycatcher 

will nest in stands 

dominated by saltcedar, 

it is considered 

suboptimal habitat 

because it lacks the 

diversity and thermal 

cover found in native 

willow/cottonwwod 

habitats.

Treatments would improve native 

willow/cottonwood riparian habitats preferred by 

willow flycatchers. During treatments, some loss 

of existing vegetation would occur and could 

reduce their suitability for use by flycatchers until 

native vegetation is re-established. There would be 

a very low risk that some individual birds could be 

impacted by treatments, with this likelihood even 

lower given the mitigation measures requiring 

surveys prior to treatments in potential habitat. If 

surveys show habitat is occupied, measures would 

mitigate effects. No adverse effects to population 

or habitat trends are expected. 

Bald Eagle 

(T)

Weeds would not affect 

large trees and snags 

that bald eagles depend 

on in their winter range 

habitats. 

Treatments would not affect large trees and snags 

that bald eagles depend on in their winter range 

habitats. No impacts to population or habitat trends 

are expected given the mitigation measures to 

avoid disturbance.

102 Final Environmental Impact Statement – Invasive Plant Control Project
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TES Species Alternative A 

(No Action)

All Weed Management Alternatives:

B, C, D

Mexican 

Spotted Owl 

(T)

Weeds would continue 

to reduce understory 

vegetation used by 

owl’s prey, thereby 

reducing the owl’s prey 

base. 

Treatments would improve owl’s prey base habitat. 

No effect to population or habitat trends are 

expected given the mitigation measures that avoid 

disturbance during the breeding season and 

avoidance of burning in PACs.

Least Tern 

(E)

Weeds would not affect 

this species because of 

its life history and 

limited occurrence in 

New Mexico. 

Treatments would provide little benefit to the tern. 

No effect to population or habitat trends are 

expected.

American 

Peregrine 

Falcon (S)

Weeds would not alter 

habitat for this species. 

Treatments would not alter habitat for this species. 

No impacts to population or habitat trends are 

expected.

Northern 

Goshawk (S)

Weeds would reduce 

prey base habitat. 

Treatment would improve prey base habitat. No 

impacts to population or habitat trends are 

expected.

Boreal Owl 

(S)

Weeds would not likely 

be a problem in the 

mature, high elevation 

coniferous forests 

needed by this species. 

Treatments would not likely affect the mature, high 

elevation coniferous forests needed by this species. 

No impacts to population or habitat trends are 

expected.

White-tailed 

Ptarmigan 

(S)

Weeds would not affect 

this alpine habitat to 

any large degree. 

Weeds could reduce 

willows that could 

reduce over-wintering 

success.

Treatments would not affect this alpine habitat to 

any large degree, but could potentially improve 

over-wintering success in willow habitat. No 

impacts to population or habitat trends are 

expected.

Western 

Yellowbilled 

Cuckoo (S)

Weeds would continue 

to displace native 

riparian habitat for this 

species. 

Treatments would improve native riparian habitats 

for this species. Short-term loss of vegetation for 

1-2 years could reduce habitat suitability until 

willows/cottonwoods are re-established. No 

impacts to population or habitat trends are 

expected.

Blue-black 

Silverspot 

Butterfly (C)

Weeds would continue 

to reduce native 

riparian vegetation, 

increasing the potential 

for impacts to this 

species habitat.

Treatments would continue to improve native 

riparian vegetation, increasing the beneficial 

effects to this species habitat. No impacts to 

population or habitat trends are expected.

Final Environmental Impact Statement – Invasive Plant Control Project 103
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TES Species Alternative A 

(No Action)

All Weed Management Alternatives:

B, C, D

Goat Peak 

Pika (S)

Weeds would continue 

to reduce native 

vegetation used as

forage by this species. 

Treatments would increase forage availability for 

this species. No impacts to population or habitat 

trends are expected.

New Mexico

Jumping 

Mouse (S)

Weeds would continue 

to reduce native 

vegetation used as 

forage by this species. 

Treatments would increase forage availability for 

this species. No impacts to population or habitat 

trends are expected.

Southwestern 

River Otter 

(S)

Weeds would not 

impact this species. 

Treatments would not impact this species.

Swift Fox 

(S)

Weeds would continue 

to reduce native 

vegetation used by prey 

species for this fox, 

thereby reducing prey 

base. 

Treatments would increase prey base habitat for 

this fox. No impacts to population or habitat trends 

are expected.

Linnaeus 

Ramshorn 

Snail (S)

Weeds would not 

impact this species.

Treatments would not impact this species.

Environmental Consequences - Migratory Birds

Effects previously described for all wildlife habitat and populations on the Forests apply to 

migratory birds. Table 30 provides additional disclosures of estimated effects of each alternative 

for migratory birds associated with specific habitats on the Forests.

Table 30. Effects to Migratory Birds and Habitats

High Priority 

Species

Migratory Bird 

Habitat

Alternative A 

(No Action)

All Weed 

Management 

Alternatives:

B, C, D

Black Swift

High elevation 

riparian 

woodland

Weeds would continue 

to reduce riparian 

habitats and have a 

negative impact on 

these species. Weed 

species on the Forests 

are most prevalent in 

riparian areas (2 

percent of riparian 

areas have known 

infestations). 

Treatments would 

increase native 

riparian habitat 

vegetation and 

improve habitat for 

these species. No 

impacts to 

population or habitat 

trends are expected.

Red-naped Sapsucker

Hammond’s 

Flycatcher

American Dipper

Veery

MacGillivray’s 

Warbler

104 Final Environmental Impact Statement – Invasive Plant Control Project
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High Priority 

Species

Migratory Bird 

Habitat

Alternative A 

(No Action)

All Weed 

Management 

Alternatives:

B, C, D

Wilson’s Phalarope

Wet meadow

Weeds would continue 

to reduce riparian 

habitats and have a 

negative impact on 

these species. Weed 

species on the Forests 

are most prevalent in 

riparian areas (2 

percent of riparian 

areas have known 

infestations).

Treatments would 

increase native 

riparian habitat 

vegetation and 

improve habitat for 

these species. No 

impacts to 

population or habitat 

trends are expected.

Bobolink

Brown-capped Rosy 

Finch

Alpine tundra

Weeds would not occur 

to any large extent in 

this habitat, thus there 

would be no effects 

expected. 

Treatments would 

not likely occur in 

this habitat, thus 

there would be no 

effects expected.

White-tailed 

Ptarmigan

Northern Goshawk 

Mixed conifer

Weeds would continue 

to spread; 

approximately 0.3 

percent of this habitat 

type has inventoried 

weeds. Populations of 

these species would be 

negatively impacted by 

the loss of native 

vegetation and 

associated habitat.

Treatments would 

benefit these species 

as weeds are 

eliminated or 

controlled in these 

habitats. No impact 

to population or 

habitat trends.

Mexican Spotted Owl

Williamson’s 

Sapsucker

Olive-sided Flycatcher

Dusky Flycatcher

Ferruginous Hawk 

Plains/mesas 

grassland

Weeds would continue 

to spread; 

approximately 0.04 

percent of this habitat 

type has inventoried 

weeds. Populations of 

these species would be 

negatively impacted by 

the loss of native 

vegetation and 

associated habitat.

Treatments would 

benefit these species 

as weeds are 

eliminated or 

controlled in these 

habitats. No impact 

to population or 

habitat trends.

Prairie Falcon

Bendires Thrasher

Long-billed Curlew

Lark Bunting

Final Environmental Impact Statement – Invasive Plant Control Project 105
Chapter 3 • Affected Environment and Environmental Consequences

High Priority 

Species

Migratory Bird 

Habitat

Alternative A 

(No Action)

All Weed 

Management 

Alternatives:

B, C, D

Ferruginous Hawk 

Pinyon-juniper

Weeds would continue 

to spread; 

approximately 0.05 

percent of this habitat 

type has inventoried 

weeds. Populations of 

these species would be 

negatively impacted by 

the loss of native 

vegetation and 

associated habitat.

Treatments would 

benefit these species 

as weeds are 

eliminated or 

controlled in these 

habitats. No impact 

to population or 

habitat trends.

Gray Vireo

Bendires Thrasher

Black-throated Gray 

Warbler

Gray Flycatcher

Lewis’s Woodpecker

Mid-elevation 

riparian 

woodland

Weeds would continue 

to reduce riparian 

habitats and have a 

negative impact on 

these species. Weed 

species on the Forests 

are most prevalent in 

riparian areas (2 

percent of riparian 

areas have known 

infestations).

Treatments would 

increase native 

riparian habitat 

vegetation and 

improve habitat for 

these species. No

impacts to 

population or habitat 

trends are expected.

Red-headed 

Woodpecker

Blue Grouse

Spruce/subalpine 

fir

Weeds would continue 

to spread; 

approximately 0.02 

percent of this habitat 

type has inventoried 

weeds. Populations of 

these species would be 

negatively impacted by 

the loss of native 

vegetation and 

associated habitat.

Treatments would 

benefit these species 

as weeds are 

eliminated or 

controlled in these 

habitats. No impact 

to population or 

habitat trends.

Boreal Owl

Flammulated Owl

Ponderosa pine

Weeds would continue 

to spread; 

approximately 0.2 

percent of this habitat 

type has inventoried 

weeds. Populations of 

these species would be 

negatively impacted by 

the loss of native 

vegetation and 

associated habitat.

Treatments would 

benefit these species 

as weeds are 

eliminated or 

controlled in these 

habitats. No impact 

to population or 

habitat trends.

Virginia’s Warbler

Black-throated Gray 

Warbler

106 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

High Priority 

Species

Migratory Bird 

Habitat

Alternative A 

(No Action)

All Weed 

Management 

Alternatives:

B, C, D

Bendire’s Thrasher

Great Basin 

desert shrub

Weeds would continue 

to spread; 

approximately 0.03 

percent of this habitat 

type has inventoried 

weeds. Populations of 

these species would be 

negatively impacted by 

the loss of native 

vegetation and 

associated habitat.

Treatments would 

benefit these species 

as weeds are 

eliminated or 

controlled in these 

habitats. No impact 

to population or 

habitat trends.

Sage Sparrow

Loggerhead Shrike

Sage Thrasher

MacGillivray’s 

Warbler

Montane shrub

Weeds would continue 

to spread; 

approximately 0.2 

percent of this habitat 

type has inventoried 

weeds. Populations of 

these species would be 

negatively impacted by 

the loss of native 

vegetation and 

associated habitat.

Treatments would 

benefit these species 

as weeds are 

eliminated or 

controlled in these 

habitats. No impact 

to population or

habitat trends. Green-tailed Towhee

Black Swift Cave/rock/cliff

No weed infestations 

are known to occur on 

this habitat type.

No impacts

Important Bird 

Areas

No important bird areas 

are currently 

designated.

No impacts

Over-wintering 

Areas

Over-wintering areas 

are associated with 

large river riparian 

areas. These areas are 

among the most 

heavily impacted by 

weeds such as 

saltcedar, which reduce 

habitat suitability for 

many species.

Treatments would 

maintain or enhance 

suitability of overwintering areas as 

they would reduce 

weeds such as 

saltcedar.

Final Environmental Impact Statement – Invasive Plant Control Project 107
Chapter 3 • Affected Environment and Environmental Consequences

Fish and Aquatic Resources

Affected Environment

Proposed weed treatment would occur in the San Juan, Arkansas, and Rio Grande River basins of 

northern New Mexico, which is the affected environment for this proposed project. Refer to the 

“Water Resources” section for a map and description of the fifth-level watersheds and details 

about water quality.

Figure 9 shows the watersheds in the forests. Of the 55 fifth-level watersheds that drain the 

project area, 31 watersheds currently have weed infestations. Weed infestations within each 

watershed are relatively small, although a high percentage of acres infested with saltcedar or 

similar riparian weed species occurs within 300 feet of flowing waters.

This analysis will focus on the potential impacts to aquatic organisms, particularly those listed as 

Management Indicator Species (MIS) for either of the two forests. Aquatic organisms listed as 

MIS are the Rio Grande cutthroat trout (USDA FS 2003a, 2003b), resident trout (USDA FS 

2003a), and aquatic insects (macroinvertebrates) (USDA FS 2003a). The Rio Grande cutthroat 

trout is also listed as a sensitive species for the Southwestern Region of the Forest Service.

The Rio Grande cutthroat trout is one of 14 subspecies of cutthroat trout native to the Western 

United States. Rio Grande cutthroat trout are found primarily in clear, cold mountain lakes and 

streams in Colorado and New Mexico within the Rio Grande Basin. In New Mexico, Rio Grande 

cutthroat trout exist only in mountain streams in the Sangre de Cristo and Jemez Mountain ranges 

from the headwaters of the Rio Grande to tributaries in northern New Mexico, which include the 

Pecos, Chama, and Jemez Rivers. Currently, the Carson National Forest manages approximately 

360 miles of perennial streams as either known or potential Rio Grande cutthroat trout habitat. 

The Santa Fe National Forest manages approximately 600 miles of known or potential Rio 

Grande cutthroat trout habitat (USDA FS 2003b).

The Rio Grande cutthroat trout spawn from the middle of May to the middle of June after the 

peak runoff from snowmelt occurs. An average water temperature of about 10 °C (50 °F) appears 

to be a key factor initiating spawning of Rio Grande cutthroat trout. Male cutthroat trout typically 

mature sexually at 2 years of age; whereas, females usually mature at 3 years. Depending on size, 

an individual female may deposit 2,000 to 4,500 eggs into a gravel nest, or redd. Sediment-free 

depositional gravel beds that have a continuous flow of well-oxygenated water are required for 

successful development of the embryos. Suitable gravels range from 6-40 mm in diameter 

(Magee et al. 1996). Hatching of Rio Grande cutthroat trout is temperature dependent, occurring 

in 21 days at about 11 °C (52 °F). Juveniles need shallow, calm water that is protected from direct 

sun and other harsh weather elements. Side channels, undercut banks and overhanging vegetation 

or exposed roots along margins provide this type of habitat. Adult Rio Grande cutthroat trout need 

pools with residual depth greater than 1 foot in order to survive harsh winter conditions (USDA 

FS 2003b).

The decline in Rio Grande cutthroat trout numbers in New Mexico is attributed to many factors, 

which include but are not limited to: (1) introduction of nonnative trout species who either prey 

upon or hybridize with Rio Grande cutthroat trout; (2) dewatering of streams for irrigation; and 

(3) altered stream habitat.

108 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

Nonnative trout introductions are the major factor for decline of Rio Grande cutthroat trout. 

German brown trout were introduced in the early 1900s. They currently occupy most perennial 

streams on the Santa Fe National Forest, but are no longer stocked. They feed primarily on other 

fish, including Rio Grande cutthroat trout. This aggressive behavior limits productivity of Rio 

Grande cutthroat trout and eventually leads to extirpation of the native fish in a given stream 

segment. Rainbow trout have been stocked in New Mexico since 1896 and are distributed 

throughout the State (Sublette et al. 1990) in cold-water streams and lakes. New Mexico Game 

and Fish (NMG&F) continually supplement populations with stocking. Rainbow trout hybridize 

with cutthroat trout and compete for food. The key limitations to fully restoring Rio Grande 

cutthroat trout populations in New Mexico are the quality of the aquatic habitat or the presence of 

nonnative fish that compete with, prey on and hybridize with Rio Grande cutthroat trout.

Altered stream habitat is attributed to activities such as long-term fire suppression, timber harvest 

and firewood consumption, livestock grazing, road construction, dispersed and developed 

recreational activities including off-road-vehicle use in riparian areas. In addition, whirling 

disease was discovered in 1999 in New Mexico, including waters on the Santa Fe National Forest 

(Pecos River, Rio Cebolla, Cañones Creek, Jacks Creek) and Carson National Forest (Middle 

Ponil Creek). It is unclear at this time what effects this may have on the overall population of Rio 

Grande cutthroat trout over the long term.

Aquatic surveys on the Santa Fe National Forest show quality of habitat conditions primarily in 

the “less than moderate” category. In more remote, high elevation areas, stream habitat is 

“moderate to excellent.” Poor habitat conditions and water quality in the lower elevations are 

limiting factors to the size of Rio Grande cutthroat trout populations. Habitat and proper 

functioning condition surveys on the Carson National Forest indicate that streams are in 

“moderate to good condition.” The primary habitat concerns are the lack of large, woody debris 

and lack of pool development. These factors—along with competition and hybridization with 

nonnative trout—result in reduced numbers of populations of Rio Grande cutthroat trout and a 

lack of connectivity between populations.

Decreased water quality can be attributed but not limited to surface soil disturbance, soil 

compaction, road runoff, unstable banks, and delivery of pollutants from nonpoint sources. Poor 

habitat conditions can be attributed but not limited to a lack of instream structure (mostly missing 

large, woody debris), sediment-filled pools, loss of undercut banks, depletion of beaver 

populations, lack of side channel development, and poor riparian health.

Many contributing factors lead to each condition. For example, in the case of large woody debris, 

removal of riparian and instream wood from past timber and firewood practices is only one 

contributing factor. Fire suppression, grazing, and large wildfires also contributed. In addition, the 

agency removed large wood from streams up until the 1980s because of previous scientific 

thought that wood was a barrier to migration.

Stream habitat inventories conducted to assess fish habitat condition and flood plain function, as 

well as establishing baseline for future monitoring, confirmed that there is a lack of large wood in 

many streams outside higher elevation, wilderness streams. Surveys in 2002 noted that in isolated 

locations in wilderness, streams host nearly 70 pieces of large wood per mile. In similar stream 

types outside of wilderness, streams rarely reached 10 pieces per mile, in many cases going 

several miles without one piece of wood.

Final Environmental Impact Statement – Invasive Plant Control Project 109
Chapter 3 • Affected Environment and Environmental Consequences

Resident trout (rainbow, brown and brook) are Carson National Forest management indicator 

species for quality perennial streams and riparian vegetation. Rainbow trout were first introduced 

into New Mexico in 1896 and have subsequently been introduced into all major drainages of the 

State (USDA FS 2003b). Of particular importance relative to this species habitat needs and the 

proposed weed treatment, is the maintenance of riparian vegetative and structural cover, used as 

escape and resting cover and to maintain cool (generally <18 C) water temperatures (USDA FS

2003a). Brown trout were introduced into New Mexico during the early 1900s (USDA FS 2003a). 

This species typically inhabits cold-water streams and lakes, and tends to occupy deeper, lower 

velocity, and warmer waters than other trout. Brown trout prey on other trout species and compete 

for food and space. Riparian vegetation that provides canopy shade (between 50 and 70 percent) 

is desirable for this species (USDA FS 2003b). Brook trout were introduced into most major 

drainages of New Mexico during the early 1900s. They are found primarily in cold, clear 

headwater streams as well as lakes, and adapt well to a variety of freshwater environments 

(USDA FS 2003a).

Aquatic insects (macroinvertebrates) are found in aquatic environments and help to maintain 

ecosystem health by eating bacteria and dead or decaying plants and animals. In addition to their 

role in the food base for fish, populations of certain aquatic insects are indicators of high water 

quality, including overall aquatic condition, quality of fisheries and associated riparian habitat 

(USDA FS 2003b). In natural perennial streams, primary factors controlling distribution and 

composition of aquatic insects are temperature, flow, substrate, chemical condition, and 

aquatic/riparian vegetation. Of these factors, riparian vegetation, water chemistry, and 

temperature are of primary importance relative to potential impacts of the proposed weed 

treatment activities.

Environmental Consequences

The environmental consequences discussion focuses on the potential impact of herbicides and 

sediment on fish, since impacts on aquatic insects tend to be more short term. The analysis 

considered scientific research on the risks of herbicide use, along with watershed modeling to 

determine the risk of herbicide applications into aquatic systems at levels that could have an 

adverse impact. Appendix 3 contains more information regarding the risk assessment for fish and 

aquatic species.

The “Water Resources” section described the 11 representative watersheds selected for detailed 

analysis relative to estimate potential herbicide delivery into streams on the Forests. These 11 

watersheds were evaluated with a model developed to calculate picloram delivery via surface 

water runoff/overland flows to the aquatic system after application. Details of the methodology 

and associated assumptions are found in Appendix 5. Refer to Chapter 2 for a detailed description 

of treatments proposed for known weed infestations on the Forests, as well as the adaptive 

management strategy that would be used.

A “worst case analysis” method was used in modeling in order to consider a conservative acreage 

estimate where herbicide levels could have an impact to aquatic resources. Picloram was selected 

because it has a risk quotient categorized as “high,” and because of its mobility in soil. The risk 

quotient for glyphosate is “moderate” while all others are “low.” Risk of using picloram has been 

evaluated using literature review and conservative direct modeling. The model also used 

Alternative D (herbicide only) as if all 7,350 acres of inventoried weed infestations would be 

treated with herbicides only, and within the same year rather than being spread out over the next 

110 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

10 years. Detailed results of the analysis are presented in Appendix 5 and contained in the project 

record.

Alternative A (No Action Alternative)

Weed treatment activities including herbicide use would continue to be implemented by other 

jurisdictions along Federal, State, and county roads and on public and private lands within the 

same watersheds that overlap the Forests’ boundaries. These herbicide applications would not be 

expected to have any measurable adverse consequences to fish populations on the Forests, 

primarily due to the limited amounts and concentrations that would be used at one time within the 

same aquatic systems. The level would be well below thresholds shown by the watershed 

modeling to have a toxic impact to fish.

Without the proposed weed control treatments, weeds would continue to spread exponentially at a 

rate of approximately 5 to 30 percent annually. Minor but cumulative adverse impacts to aquatic 

habitat and fish populations would be expected to result over time from a combination of: (1) 

increased runoff, erosion, and sedimentation due to less overall vegetation density and diversity 

(See “Vegetation Resources” section); (2) reduced streambank stability where weeds eliminate 

native riparian vegetation along stream channels; (3) increased surface water temperature where 

saltcedar replaces native riparian shade species such as willows and cottonwoods; and (4) reduced 

organic matter entering surface waters.

A large portion of the weed infestation acreage on the Forests occurs along drainage bottoms. 

Weeds would be expected to reduce infiltration and increase runoff and sediment production in 

those areas because they reduce the vegetative ground cover and allow crusting of exposed soil

(Lacey et al. 1989). Tap rooted weeds reduce infiltration because they do not have the dense, fine 

root system of grasses. Water runoff was 56 percent higher and sediment yield was 192 percent 

higher on spotted knapweed plots compared to bunchgrass plots during a simulated rainfall period 

(Lacey et al. 1989). These conditions would have long-term, adverse effects on water resources 

on the Forests.

Increases in sediment would impact aquatic organisms in several ways. Resident trout, as well as 

many other aquatic species, require habitat with little sediment. Suspended sediment can impact 

the respiration of these species and an increase in embeddedness (sediment that fills the gaps in 

spawning gravels) can reduce the quality of spawning habitat for trout. Sediment increases can 

also negatively affect aquatic insects, either through reduction in the populations of these preybase species, or a change in species composition, which can then be amplified through other 

species higher up the food chain.

Alternatives B and D (Proposed Action and Herbicides Only)

Weed treatment on both forests, including use of herbicides, would occur on an estimated 600-

1,600 acres per year (maximum of 3,000 acres per year for both forests) over the next 10 years. 

Under Alternative B, approximately 60-70 percent of the treatment acres would involve the use of 

herbicides alone or in combination with other methods. Alternative D would use herbicides on all 

weed treatment sites.

Aquatic insects are an important food source for fish, so contaminants that affect the insects can 

affect the health of the fish that eat them. Since aquatic insects are adapted to highly variable 

stream environments, they would be better able to tolerate change on the Forests compared to 

those in more stable lake and pond environments (Mackie 1998), although their response to 

Final Environmental Impact Statement – Invasive Plant Control Project 111
Chapter 3 • Affected Environment and Environmental Consequences

pollutants can vary. The degree of impact to an aquatic system is dependent on the chemical and 

physical properties of the pollutant and the ability of a given species to tolerate an impact 

(Nimmo 1985). Impacts on species abundance and diversity resulting from catastrophic substrate 

loss or degradation are well documented. Aquatic insect community response studies have shown 

that recolonization within a few years generally results, though responses can vary within an 

individual species.

Risk assessments for the herbicides proposed for use identify those herbicides that would pose no 

threat to aquatic systems—even under spill scenarios that are plausible, but not likely to occur. 

Those with lowest risk would be favored when selection of an herbicide were made in 

circumstances that might affect aquatic systems. Some herbicides are not registered for use near 

water (e.g. Tordon 22 with picloram, or Round Up with glyphosate/POEA). Following label 

direction will assure that the proper formulations are used that will not have an effect on the 

aquatic plants/animals near a treatment site.

Since the timing of chemical releases and water conditions relative to the distribution and life 

cycles of organisms determines the potential exposure and, correspondingly, the biological effects 

of exposure, the effect of herbicides is more difficult to track. The effect on benthic species (i.e. 

species that live on the bottom of a water body) is determined primarily by the amount in the 

water and substrate. The composition and toxicity change rapidly and continuously as individual 

compounds are transported through the aquatic system and dispersed and degraded at differing 

rates by physical, chemical, and biological processes (Nimmo 1985). The rates of these 

weathering processes and population recolonization vary depending on temperature, currents, 

wind, and concentrations of suspended and dissolved components of the receiving water, 

sediment sorption, and biological activity.

Several potential risks to fish and aquatic organisms were considered in this analysis, including 

the risk of herbicides leaching through the soil into ground water, accidentally spilling in or near 

aquatic systems, or entering aquatic systems via overland flow events (major water runoffs). Most 

herbicides are applied in liquid formulations and are sprayed on the foliage of the target 

vegetation. Soils are rarely a major receptor, although it is possible for herbicides on the soil to 

leach through to ground water and ultimately reach the aquatic environment. This method of 

introduction usually poses the least amount of risk to the aquatic environment because chemicals 

typically disappear from the soil surface by either plant uptake of the chemical, volatilization, 

natural decomposition of the active ingredients, or adsorption of the herbicide by soil particles. As 

Norris et al. (1991) indicates, leaching of chemicals through the soil profile is a public concern, 

but is least likely to occur in undisturbed forest environments. The half-lives (e.g. the time for 

half the active ingredient to degrade) of most of the herbicides are 24 to 48 hours in water, 

although picloram ranges from 20 to 277 days, which is more than any of the other herbicides 

proposed for use. Picloram is also a restricted use herbicide and would not be used in an aquatic 

environment. Mitigation measures—such as limiting the use of picloram on highly permeable 

soils with shallow water tables, in riparian areas, or near water bodies—would minimize potential 

leaching effects.

Herbicide container leaks, spills, improper storage or handling, as well as rinsing of containers 

can potentially result in surface or ground water contamination. Mitigation measures in Chapter 2 

and described in a detailed chemical handling and spill prevention plan would reduce the risk of 

impacts from an accidental spill of herbicide in or near a water body. With mitigation measures

112 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

and other standard herbicide use and handling procedures in place, the risk of adverse impacts is 

considered very low.

Another mode of herbicide entry to the aquatic system includes overland flow from either 

precipitation events or irrigation. Risks vary depending on soil composition and the timing and 

intensity of the precipitation events after herbicide application. Risk of herbicide entry into 

aquatic systems from overland flow runoff tends to be lower on well-vegetated forests and 

rangelands. Norris et al. (1991) indicated that overland flow occurs infrequently on most 

undisturbed forest lands because the infiltration capacity of the forest floor and soils is usually far 

greater than the rate of precipitation. However, denuded and compacted soil such as along roads, 

trails, or at camping sites, typically provides increased potential for surface runoff. When highseverity wildfires reduce soil infiltration rates and hydrologic function, the magnitude of 

accelerated erosion and runoff temporarily increases. This effect is greatly diminished by the 

second year after a fire because vegetative recovery begins and soil erosion ceases once the 

erosion rills break through the soil hydrophobic layer (DeBano et al. 1998).

Results of picloram modeling for the representative watersheds receiving treatment are discussed 

in the following “Water Resources” section and in Appendix 5. Modeling shows that for two 

watersheds (Ponil Creek Watershed on the Carson National Forest and Lower Jemez River 

Watershed on the Santa Fe National Forest), if all the known weed infestations were treated with 

herbicides in the same year, the level of herbicide that could potentially reach the water could 

exceed the no effect threshold. Because weed infestations in these watersheds would not be 

treated 100 percent with herbicides within a single year, and many mitigation measures would be 

applied to mitigate potential impacts, the likelihood of this occurring is very low and no 

measurable effects would be expected to aquatic organisms.

The concentration of herbicide that would likely reach aquatic resources would be below the 

threshold where an adverse impact could be detected. This is based on the treatment acreage and 

spatial distribution across the Forests as proposed, which is expected to be spread out across a 

number of watersheds each year. As adaptive management is implemented over time, it is 

expected that future herbicide treatments under the adaptive strategy would have the same low 

risk of adverse effects.

This determination is also based on application of the mitigation measures designed to protect 

aquatic resources. These measures include prohibiting the use of picloram near water, avoiding 

the spaying of any herbicides near water bodies, using herbicide spill control measures, and 

others. Additional protective measures in Chapter 2 would be applied to streams with sensitive 

Rio Grande cutthroat trout species. Measures limit herbicide use to a short-lived, nonleachable 

herbicide registered by EPA for use on permeable soils with shallow water tables for areas where 

there is a highly permeable soil and shallow water table. This would help avoid the risk of an 

herbicide leaching through to the ground water, and would eliminate the use of picloram in those 

situations. Furthermore, methods selected for use in riparian areas or next to aquatic species 

habitats would be restricted to either nonherbicide methods or herbicides registered by EPA for 

use in aquatic habitats and documented as having a low risk to fish and other aquatic species. The 

mitigation measures have been successfully implemented on other forests and should be highly 

effective. Monitoring the effects of treatments and effectiveness of mitigation measures would 

further reduce the risk of unexpected impacts over the life of this project.

Final Environmental Impact Statement – Invasive Plant Control Project 113
Chapter 3 • Affected Environment and Environmental Consequences

Long-term, beneficial impacts to aquatic resources would likely result from effective weed 

treatment because of increased ground cover near streams (soil stabilization and maintenance of 

riparian vegetation) where treatments successfully return native vegetation to dominance.

In terms of other potential adverse effects from weed treatment methods, the minimal increases in 

soil erosion would be well within acceptable limits as described in the “Soil Resources” section 

of this DEIS, and heavy equipment would not be used on slopes over 40 percent. Based on the 

analysis presented in the soil, water and vegetation sections, along with mitigation measures to 

limit sediment impacts, there would be a minimal increase in sediment delivery to streams and no 

observable impact to aquatic habitat or species caused by increased sedimentation.

Alternative C (No Herbicide)

This alternative eliminates all risk of herbicide delivery to aquatic systems from implementing 

this project. The effects from the nonherbicide weed control methods would be similar to those 

described for Alternatives B and D in terms of the limited amount of soil erosion, runoff and 

sediment delivery to aquatic systems. However, because of the need to repeat treatments more 

often, and the larger number of acres where the soil surface would be disturbed, this alternative 

would result in a slightly higher rate of potential sediment delivery. Most of the treatments are in 

previously disturbed areas and mitigation measures would minimize long-term increases in 

erosion or sedimentation, so the increase in erosion and sediment movement over current 

conditions would still be quite small.

Beneficial, long-term effects on streams and aquatic organisms associated with controlling and 

eradicating weeds would be slightly less than the effects of implementing Alternatives B or D, 

since this alternative would not be as rapid or effective in reducing weed infestations.

Cumulative Impacts

The analysis area for cumulative effects on fisheries and aquatic resources is the area in and 

immediately adjacent to the two forests. This boundary represents the areas where the actions 

proposed in this project are most likely to interact with other activities, in particular the weed 

treatments and ground disturbance on both forests and other lands (private, State, BLM, etc.). The 

beginning of this chapter lists past, ongoing and foreseeable future activities considered in this 

cumulative effects analysis that could continue to impact water, soils and aquatic resources.

Herbicide applications ongoing by the Forest Service as well as by others on public and private 

lands in northern New Mexico can potentially have cumulative effects on aquatic resources. The 

potential cumulative effect to aquatic resources will be minimized by proper application 

procedures, such as to apply herbicides when rain is unlikely; that herbicides are applied in 

accordance with label direction; and that the lowest impact application methods should be 

preferred. This will greatly reduce the likelihood of the applied herbicide reaching the aquatic 

system. Aside from these mitigation measures under control of the Forest Service, information 

regarding the magnitude and extent of future herbicide application outside National Forest 

System lands is quite limited, including how much picloram is or will be used. Based on efforts to 

obtain this information, as contained in Appendix 1, picloram use would be fairly limited, and 

herbicide applications would continue to be implemented on small acreages without the use of 

widespread aerial application methods.

In terms of cumulative, long-term effects from chronic exposure to herbicides, there is a limited 

amount of research on this topic. Data collected under laboratory conditions does not account for 

114 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

environmental variables such as temperature, wind, photodegradation, soil permeability, 

precipitation frequency and intensity, local geochemical influences, stream volume (dilution 

factor) or water quality (Munn and Gilliom 2001). Woodward (1976) documented chronic 

exposure effects in lake trout (Salvelinus namaycush) fry after 60 days. It is unlikely that there 

would be any chronic exposure effects on the aquatic environment from this project given 

exposures of 1 or 2 days as opposed to 60. With mitigation measures in place as previously 

described, concentrations of herbicides and the duration of those concentrations on the aquatic 

environment would be small, below levels at which chronic exposure effects are documented. 

The risk assessments for each proposed herbicide formulation includes a review of the relevant 

information on an herbicides likely long-term effect, based on application rates used by the Forest 

Service.

Most of the jurisdictions that apply herbicides follow similar mitigation measures and have 

chemical spill plans in place to reduce potential adverse impacts. Government agencies applying 

herbicides must all meet acceptable levels of water quality protection. Most of the treatment by 

other jurisdictions and landowners would continue to primarily occur along highways and roads, 

and in valley bottoms, where soil conditions are more conducive to infiltration than runoff. If 

runoff were to occur, much of the private treatments occur low in the watersheds, where 

streamflow would likely be greater, allowing for faster dilution than those locations being treated 

in the headwaters.

The lands adjacent to the Forests are not used for intensive farming or agriculture, with small 

herd livestock grazing and hay growing as the largest use. These agricultural uses do not typically 

apply large amounts of herbicides (although this could increase as thistles and other weeds invade 

pasture lands). However, cumulatively, there is a very slight risk that herbicide use by the Forests 

along with adjacent landowners may exceed those “no impact” thresholds proposed by the 

Forests. It should be noted, however, that these threshold values are very conservative and have 

incorporated safety factors that mean little impact is expected even in the event a level exceeds 

the threshold. In addition, the contribution to cumulative impacts from weed control alternatives 

would be negligible, since the direct and indirect effects from the alternatives would be at 

immeasurable levels.

Other activities around the Forests that increase soil erosion and sedimentation would add to the 

negligible amount of erosion and sediment increase expected from proposed weed control 

activities. Since the direct and indirect effects from the alternatives are quite small, their 

contribution to cumulative impacts would also be minimal, especially since activities displacing 

soil near streams would occur at different times and in widely distributed sites across the Forests. 

Increases in sediment would most likely occur during significant rainfall and runoff events.

The most likely cumulative effects from all weed control treatments in northern New Mexico, 

together with other ecosystem restoration projects being planned or conducted on the Forests, 

would be the beneficial restoration of native plants and soil stability that reduce sedimentation 

and improve aquatic conditions. Invasive plant control efforts, implemented in conjunction with 

successful road closure and ATV management, would have an overall beneficial effect on the 

ecosystem diversity by eliminating existing invasive plant populations while limiting the 

introduction and spread of new populations or species.

Final Environmental Impact Statement – Invasive Plant Control Project 115
Chapter 3 • Affected Environment and Environmental Consequences

Figure 7. Major Streams

116 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

Figure 8. Weeds in Valley Bottoms/Riparian Areas

Final Environmental Impact Statement – Invasive Plant Control Project 117
Chapter 3 • Affected Environment and Environmental Consequences

Figure 9. Watersheds, including Representative Watersheds

118 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

Water Resources

Affected Environment

This section describes watershed characteristics, existing water quality, and analysis methods 

used.

Watershed Characteristics

The Forests are located within the Rio Grande, Arkansas, and San Juan Basins of northern New 

Mexico. These major basins are divided into smaller, fifth-level watersheds that are identified by 

their Hydrologic Unit Codes (HUCs).

Table 31 shows the fourth-level basins and fifth-level watersheds for the project area, and Figure 

9 shows the fifth-level watersheds including those selected as representative watersheds for this 

analysis. The project area intersects 55 fifth-level watersheds that total nearly 9.7 million acres 

(or about 15,160 square miles). The average size for these watersheds is 180,000 acres or about 

281 square miles. Table 31 and Figure 9 show all of the watersheds on or intersecting the Forests. 

Several of these watersheds intersect a small fraction of the Forests, and have very little influence 

on these watersheds. Watersheds that overlap less than 2 percent of the Forests include El Vado 

Reservoir, Van Bremer Canyon, North Pinos, San Antonio, Lower Jemez, Cimarron Creek, Lower 

Galisteo Creek, Upper Vermejo River, and the Rio Salado. Another 13 watersheds cover less than 

20 percent of the Forests, 20 watersheds cover 20 to 50 percent, and only 14 watersheds cover 

over 50 percent of the Forests. As many of these watersheds have headwaters sections on the 

Forests, activities on the Forests influence water quality downstream and outside the Forests’ 

boundaries.

Table 31. Watersheds on or Intersecting the Forests

Fourth-level 

Basin Fifth-level Watershed Map Number Acres FS Acres

Weed 

Acres

Canadian 

Headwaters

Upper Vermejo River A01 157,148 2,399 0

Van Bremmer Canyon A02 57,514 53 0

Cimarron

Ponil Creek A03 207,734 59,087 1,266

Cimarron Creek A04 217,293 2,212 0

Mora

Upper Mora River A05 171,078 37,881 276

Coyote Creek A06 158,777 8,169 0

Manuelitas Creek A07 222,573 27,086 120

AlamosaTrincheraSan Antonio-Rio Grande A08 191,837 944 0

Rio de las Pinos

San Antonio- No. Pinos B01 200,000 549 0

Rio San Antonio B02 243,338 126,428 2

Final Environmental Impact Statement – Invasive Plant Control Project 119
Chapter 3 • Affected Environment and Environmental Consequences

Fourth-level 

Basin Fifth-level Watershed Map Number Acres FS Acres

Weed 

Acres

Upper Rio Grande

Rio Costilla B03 137,720 39,824 52

Latir Creek B04 249,377 13,439 5

Red River B05 180,138 109,469 92

Rio Hondo B06 205,065 58,951 15

Rio Grande del Rancho B07 268,623 126,952 121

Rio Pueblo-Embudo 

Creek B08 204,690 158,490 72

Arroyo Aguaje de la 

Petaca-Rio Grande B09 211,078 125,432 54

Santa Cruz-Rio Grande B10 255,454 92,546 8

Pojoaque River-Rio 

Grande B11 249,848 77,709 5

Rio Chama

Rio Brazos B12 311,226 14,691 < 1

Rio Chama-El Vado 

Reservoir B13 250,904 193 0

Rio Nutrias-Rio Chama B14 229,954 81,871 19

Rio Gallina B15 179,843 131,582 566

Rio Puerco B16 130,821 95,258 788

Canjilon Creek-Rio 

Chama B17 271,162 221,194 530

El Rito Creek B18 85,941 73,021 < 1

Rio Tusas-Rio Vallecitos B19 249,949 230,265 89

Rio Ojo Caliente B20 117,901 50,066 0

Rio del Oso-Rio Chama B21 182,796 27,598 129

Middle Rio 

Grande

Frijoles Canyon C01 145,417 56,009 3

Cochiti Reservoir C02 80,115 39,285 0

Santa Fe River C03 165,050 33,451 0

Upper Galisteo Creek C04 110,178 24,105 243

Middle Galisteo Creek C05 246,762 12,899 0

Lower Galisteo Creek C06 73,569 881 0

Borrego Canyon C07 179,060 38,913 0

Jemez River

Rio Guadalupe C08 171,697 165,166 511

Upper Jemez River C09 129,234 121,394 1593

Middle Jemez River C10 83,611 47,820 10

Rio Salado C11 158,801 2,706 0

Lower Jemez River C12 119,338 1,140 0

Rio Puerco

Rio Puerco-Arroyo 

Chijuilla C13 165,489 54,944 169

Rio Puerco-Arroyo Balcon C14 112,181 5,480 22

120 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

Fourth-level 

Basin Fifth-level Watershed Map Number Acres FS Acres

Weed 

Acres

Pecos Headwaters

Pecos River Headwaters D01 183,620 154,435 115

Cow Creek-Pecos River D02 151,891 94,200 23

Upper Tecolote Creek D03 134,184 26,603 0

Lower Tecolote CreekPecos River D04 199,847 31,944 0

Upper Canon Blanco D05 214,193 43,234 241

Uper Gallinas River D06 200,317 30,836 0

Upper San Juan

Carracas Canyon E01 45,918 13,057 7

Canon Bancos E02 180,372 59,100 70

La Jara Canyon E03 237,436 52,306 37

Blanco Canyon

Canada Larga E04 190,216 7,928 0

Tapicito Creek E05 214,177 4,963 < 1

Cereza Canyon E06 204,015 31,069 44

Table 32 shows the characteristics of the 11 representative watersheds, including watershed name, 

HUC (watershed) number, total acres (within and outside the Forests), proposed weed treatment 

acres within the watershed, waterflows in cubic feet per second, and the gauging station number.

Table 32. Characteristics of Representative Watersheds

Stream Name

Fifth Level 

Watershed 

Number

Watershed 

Area

(acres)

Proposed 

Treatment 

Area 

(acres)

Q.20 Flow 

May/Sept 

(cfs)

USGS 

Gaging 

Station 

Number

Carson National Forest

Red River – Upper Rio 

Grande Basin (B05) 1302010104 180,137 93 254 / 77 08266820

Rio Hondo – Upper Rio 

Grande Basin (B06) 1302010105 205,064 15 1471 / 293 08268700

Rio Grande del Rancho –

Upper Rio Grande Basin

(B07)

1302010106 268,622 128 373 / 23 08276000

Canjilon Creek – Rio 

Chama Basin (B17) 1302010206 271,162 3 106 / 5 08287000

Rio Tusas / Rio Vallecitos 

– Rio Chama Basin (B19) 1302010208 249,948 88 6613/1072 08289000

Ponil Creek – Cimarron 

Basin (A03) 1108000201 207,733 1,266 79 / 8 07207500

Santa Fe National Forest

Santa Cruz – Upper Rio 

Grande Basin (B10) 1302010109 255,454 8 1679 / 554 08291500

Pojoaque River – Upper 

Rio Grande Basin (B11) 1302010110 249,848 5 571 / 16 08313000

Final Environmental Impact Statement – Invasive Plant Control Project 121
Chapter 3 • Affected Environment and Environmental Consequences

Stream Name

Fifth Level 

Watershed 

Number

Watershed 

Area

(acres)

Proposed 

Treatment 

Area 

(acres)

Q.20 Flow 

May/Sept 

(cfs)

USGS 

Gaging 

Station 

Number

Upper Jemez River –

Jemez Basin (C09) 1302020202 129,234 1,591 115 / 24 08321500

Pecos River Headwaters

(D01) 1306000101 183,620 116 512 / 96 08378500

Upper Gallinas River –

Pecos Headwaters Basin

(D06)

1306000107 200,317 0 24 /9 08382000

Note: HUC = hydrologic unit code; USGS = U.S. Geological Survey; cfs = cubic feet per second; Q.20 = value for mean 

monthly streamflow exceeded in 20 percent of the years. 

There are more than 1,000 miles of perennial streams on the Forests (refer to Figure 7 showing 

the major streams). The watersheds are snowmelt and rainstorm runoff dominated. Highest 

streamflows usually occur in May as a result of snowmelt runoff. Streamflows increase as 

snowmelt occurs, usually beginning in April or May, and reach peak levels typically in May, 

depending on weather conditions and temperature fluctuations. Highest precipitation typically 

occurs in July/August during short-duration, high-intensity rainstorms. Occasional brief, intense 

thunderstorms typically in July/August can cause sudden increases in runoff, sometimes causing 

flooding. Many drainages are ephemeral or intermittent—flowing primarily in response to storms 

and/or snowmelt runoff.

Average annual precipitation on the Forests ranges from about 10 to 35 inches, with the greater 

amounts occurring at higher elevations in the mountains (USDA FS 1986). The elevation range is 

approximately 7,000 to 12,000 feet. At lower elevations where valley bottoms widen and 

gradients become less steep, the streams generally are less confined and have developed flood 

plains. These lower stream segments usually carry sediment during high flow and deposit it 

during lower flow periods. The finer-grained alluvial deposits on beds and banks of wider valley 

bottom streams can be easily eroded each year during high flow. In these stream systems, 

streambank vegetation is important in maintenance of channel stability. Depending on condition 

of streambanks, bank erosion and channel migration may occur during periods of high flow.

Surface and Ground Water Quality

Surface water quality is generally good on the Forests. Sediment (suspended and bedload) and 

water temperature are the water quality parameters that most often can be affected by land 

management. Activities that disturb vegetation or soil surface have potential to produce sediment 

from increased erosion. Sediment in streams and rivers is naturally a highly variable parameter, 

with higher loads usually observed during spring runoff or summer storms.

Water uses on the forests include cold-water fisheries, livestock and wildlife watering, recreation, 

domestic uses, and irrigation diversion/supply. More common sources of increased sediment and 

other nonpoint impacts to streams include livestock grazing, off-road-vehicle use, and poorly 

located and/or maintained roads (USDA FS 1986a). Several stream or river segments within and 

near the Forests are on New Mexico’s 2002-2004 303(d) list of impaired water bodies (NMED 

122 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

2003). Most of these impaired water bodies have turbidity, stream bottom deposits, and/or 

temperature listed as probable causes of impairment. Commonly listed probable sources of 

impairment are related to grazing and agricultural activities, bank modification, and removal of 

riparian vegetation.

Ground water on the Forests is typically at depths of several hundred feet, but in general can be 

highly variable. Drinking water wells found on the Forests range in depth from 55 feet to 150 feet 

or more (USDA FS 2003e). Yield of ground water from these formations usually is low (< 25 

gallons per minute) (USDA FS 1986a). In contrast, most valley bottoms have shallow ground 

water in alluvial deposits. This ground water is most likely closest to ground surface in May/June, 

declining through the summer as streams approach low flow conditions.

Analysis Methods

Representative fifth-level watersheds were selected from each forest to perform appropriate 

analysis of water resources—six watersheds from the Carson and five from the Santa Fe. These 

watersheds were selected to represent the variety of conditions found on the Forests in terms of 

drainage area, aspect, geology, soil, vegetation, flow conditions and aquatic sensitivity. 

Information for watersheds was compiled from State and Federal agencies, including New 

Mexico Environment Department, U.S. Environmental Protection Agency (EPA), U.S. Geological 

Survey (USGS), and the Forest Service resource databases. The representative watersheds cover 

about 2,401,000 acres (about 3,752 square miles). The average size of the representative 

watersheds is 218,000 acres or about 341 square miles. As is the case with most of the watersheds 

in the analysis area, much of the total size of these watersheds lies outside and generally 

downstream from the Forests.

Drainage areas of each watershed were determined using geographic information systems (GIS) 

methods. Flow characteristics of streams were obtained from USGS gaging stations located near 

the subject watershed boundaries.

The analysis uses streamflow rates for two time periods of the year—spring high flow (May) and 

fall low flow (September)—to provide a range of dilution factors for herbicide runoff in the 

primary stream channels of each representative watershed. These two time periods approximate 

each end of the general season of herbicide application in the Forests. For each of the 2 months, 

the value for mean monthly streamflow exceeded in 20 percent of the years (Q.20) was used to 

simulate dilution of herbicide in each stream during that time of year. These flows were then used 

as input values to model resultant herbicide concentrations after mixing and diluting in the 

streams for each of the 11 representative watersheds (see Figure 9).

Environmental Consequences

Alternative A (No Action)

Without implementation of this weed control treatment project, water resource conditions would 

deteriorate. This alternative would not address Forest Plan goals for maintaining water quality 

and favorable water flows. Weeds would continue to spread and reduce the abundance and 

diversity of native riparian vegetation while destabilizating streambanks.

Where weeds invade areas along stream channels, riparian vegetative cover can be reduced or 

eliminated, causing greater streambank instability. Overall reductions in vegetative canopy cover 

can also cause increases in stream temperature and decreases in organic matter. The Forest 

Final Environmental Impact Statement – Invasive Plant Control Project 123
Chapter 3 • Affected Environment and Environmental Consequences

Service (USDA FS 2001a) noted that the establishment of weeds within or adjacent to riparian 

habitats was increasing overland runoff and sediment yield. Lacey et al. (1989) reported a threefold increase in sediment yield and a 50 percent increase in runoff at a knapweed-infested site 

compared to a noninfested site.

Studies on the Lolo National Forest in western Montana showed that a site with 80 percent 

knapweed cover yielded 5 times the amount of sediment as sites covered with bunchgrass (USDA 

FS 2003c). These same studies estimated the effects of a 20-minute thunderstorm (100-year event 

intensity) occurring on 1,648 acres of big game winter range infested with knapweed; such a 

storm could produce an additional 160 tons of sediment compared to a weed-free area. Increased 

sediment delivery to drainages can cause increased turbidity (suspended sediment) in a 

stream/river, as well as increased stream bottom deposits that may be detrimental to aquatic life

and overall stream stability.

Because of the reduced vegetative cover from forest fires in some watersheds, increased runoff 

and sedimentation is occurring and will continue until adequate vegetation cover is established. 

Treatment of weeds in these burn areas may further reduce vegetative cover for the short term; 

however, as weeds are replaced by native vegetation, the sedimentation problems would diminish. 

Also, refer to the related effects descriptions for Alternative A in the “Vegetation, Soils and 

Aquatic Resources” sections.

Without adopting the proposed amendment to the Forest Plan, weed control within the Santa Fe 

and Gallinas Municipal Watersheds would be very difficult, since the Santa Fe National Forest 

Plan currently prohibits the use of herbicides in municipal watersheds. The proposed amendment 

would allow herbicides to be used when city officials concur with the proposed treatment 

prescription and mitigation measures to be implemented. Herbicides are currently used by other 

agencies and environmental organizations in the lower portions of both watersheds (outside 

municipal watershed boundaries on national forest lands) in order to effectively control weeds in 

those areas. Prohibiting the use of herbicides would likely result in increased spread of saltcedar, 

Siberian elm, Russian olive and other weed species in the municipal watersheds, which would 

adversely impact water quality and quantity in the long term.

Alternatives B and D 

The primary herbicides currently EPA-registered for use on the Forests have picloram, 

metsulfuron methyl, clopyralid, dicamba, triclopyr, imazapic, imazapyr, or glyphosate as their 

active ingredients, and are described in detail in Appendix 3. Any liquid herbicide sprayed on 

weeds would fall primarily on the weed plant foliage with some landing on the surrounding soil. 

The fate and transport of herbicides include the following possible transfer and degradation 

mechanisms (Siegel 2000): 

• Adsorption and detoxification by plants;

• Photodegradation by sunlight;

• Volatilization;

• Adsorption to soil particles and organic matter;

• Chemical degradation;

• Microbial degradation;

• Solubilization and dilution in surface runoff; and

124 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

• Leaching through soil horizon and potentially to ground water.

The extent to which each of the mechanisms listed above occurs is dependent upon a variety of 

factors, including meteorological conditions (e.g., magnitude and distribution of precipitation, 

sunlight, and wind); soil conditions (e.g., thickness, permeability, and organic matter content); 

land slope; depth to ground water; and chemical characteristics of herbicide. The combination of 

these mechanisms influences both magnitude and duration of impacts on water resources. 

Microbial decomposition and volatilization are the predominant breakdown processes of 

herbicides in soil. Leaching of herbicides through the soil horizon is the least likely route for 

water resource impacts, particularly with the limitation on the type of herbicide that may be used 

on permeable soils with shallow water tables. Direct application of herbicides to surface water 

would be the route most likely to cause impacts on water resources; however, this is unlikely 

because the project prohibits application of herbicides to open water and mitigation measures are 

in place to avoid accidental introduction of herbicides into aquatic environments and live streams.

Mobilization in ephemeral channels also would affect water resources if runoff occurs soon after 

application. The combination of transfer and degradation factors previously listed, along with 

following label instructions and application rates, would likely result in herbicide concentrations 

that are not harmful to the environment. This determination is partly based on the results of the 

model used to simulate herbicide applications in 11 different types of representative watersheds.

Surface and Ground Water Impacts: Potential point-source impacts on surface or shallow

ground water resources include accidental leaks and spills of liquid herbicides, and improper 

storage, handling, or rinsing of herbicide containers. One of the mitigation measures described in 

Chapter 2 states that herbicides would be stored away from wells, pumps, and any water bodies. 

Mixing and loading of chemicals would not occur within 200 feet of a water body. In addition, 

herbicide applicators would have a chemical spill plan and emergency cleanup kit onsite during 

treatments. These measures would be expected to prevent point-source impacts from accidental 

herbicide releases to water resources. The spill plan identifies methods to avoid accidental spills, 

as well as how to report and clean up spills. The cleanup kit would contain appropriate spill 

cleanup supplies.

No aerial application of herbicides would occur for any alternative, which greatly limits the risk 

from spray drift entering water bodies. With mitigation measures in place, the amount of 

herbicide drift that could reach a stream or other water body would be very small. The small 

amount of herbicide in the drift would likely be diluted to very low, nonharmful concentrations.

Some of the mitigation measures in Chapter 2 are specifically designed as “best management 

practices” to ensure the project does not violate State and Federal water quality standards. They 

include limiting herbicide spraying within a riparian area (hand application only), prohibiting 

picloram use near water and shallow ground water, limiting herbicides to those specifically 

registered for application near water, and several to minimize erosion and sediment impacts. 

Herbicide label instructions typically include these additional mitigation measures/best 

management practices: (1) no spray if precipitation is occurring or imminent; (2) no spray if air 

turbulence would affect normal spray pattern; (3) no spray if snow or ice covers target foliage; 

and (4) use only water as a chemical carrier.

In addition to the qualitative analysis just described, a model was used to simulate the mixing of 

herbicides with surface water (as previously described in the “Fish and Aquatic Resources” 

Final Environmental Impact Statement – Invasive Plant Control Project 125
Chapter 3 • Affected Environment and Environmental Consequences

section, with details in Appendix 5). Two time periods were used (May and September) to 

calculate dilution of herbicides in streams for each representative watershed. Typical high and 

low flow conditions (Q.20)) were obtained from nearby USGS gauging stations for the two 

modeled time periods. The measured Q.20 flows were in the range of 9 to 6,613 cubic feet per 

second (cfs) for May, and 5 to 1,072 cfs for September.

The model assumes a “worst case” situation where during a single year all acres proposed for 

weed treatment within each watershed would be treated by picloram at an application rate of onehalf pound per acre per year. Picloram was used in the simulation as the target herbicide because 

it is the only chemical that has a “high risk quotient” for fish—a sensitive indicator of water 

quality. While the model results show that 2 of the 11 watersheds would exceed the “safety 

factor” for picloram toxicity to fish, picloram would not actually be used in or near water, and 

weed infested acres would not all be treated with herbicides within a single year. Also, for 

Alternative B, only 30 to 40 percent of the weed infested acres would likely be treated with 

herbicides, and again, treatments would be spread out over the next 5 to 10 years, not during a 

single year as modeled.

Since the modeling indicates low risk even under worst-case assumptions, implementing the 

alternatives as proposed is expected to have a very low risk of adversely impacting water quality. 

This low risk of adverse impacts applies to all surface water, wetlands and flood plains, including 

stream reaches identified as impaired in the State’s 303(d) report.

Adverse impacts on ground water from herbicides are also not expected primarily because of the 

depth to ground water in much of the project area (greater than 50 feet), the attenuation and 

degradation factors previously listed, and the mitigation measures outlined in Chapter 2. Shallow 

ground water occurs in most valley bottoms in alluvial deposits, especially in May-June when 

streamflows are highest. In areas of wetlands, flood plains, and near streams, the mitigation 

measures in Chapter 2 would prevent adverse impacts on ground water from herbicide application 

in these areas. The primary mitigation measure that addresses ground water is: herbicide 

treatment areas that may be near water or have a high water table will be field checked to verify 

GIS data. If applying herbicides within 25 feet of a water body, or within a riparian area or other 

areas with a shallow water table, the herbicide must be specifically registered for application near 

water or in areas having shallow water tables (e.g. other than picloram).

Sediment Impacts: If relatively large areas of weeds die rapidly from herbicides, mechanical 

methods, or burning, short-term increases in erosion and sedimentation may result until 

replacement vegetation is established. Due to the limited and widely scattered acreage proposed 

for treatment compared to total drainage areas, however, increases in runoff or sediment are 

expected to be too small to measure. In addition, most of the weeds occur on gentle terrain along 

roads, trails and in valley bottoms, which have lower runoff rates compared to steep slopes. The 

Forest Plan standards plus mitigation measures described in Chapter 2 include rapid revegetation 

of areas subject to excessive erosion or sedimentation. 

Restoration of ground cover vegetation that would minimize erosion would typically be expected 

within the first growing season. Seeding, mulching, planting and other cultural methods to restore 

ground vegetation would be used where needed to ensure that appropriate ground cover is rapidly 

re-established. Vehicle and foot traffic during treatment activities would be limited in extent and 

magnitude and, therefore, not likely to increase erosion and sedimentation. No new roads or trails 

would be constructed and overall ground disturbance from project activities would be negligible.

126 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

The proposed Forest Plan amendment would allow herbicides to be used when city officials 

concur with the proposed treatment prescription and mitigation measures to be implemented. 

Herbicide treatments currently applied by other agencies and environmental organizations in the 

lower watershed portions outside the national forest boundary would become more effective since 

weeds would be less likely to spread from the upper to lower watershed sections. Allowing the 

use of herbicides would likely result in effectively eradicating or minimizing spread of saltcedar, 

Siberian elm, Russian olive and other weed species in the municipal watersheds, which would 

contribute to improving water quality and quantity in the long term. The amendment would not 

change the Forest Plan standard that limits herbicide use to “areas where the chemicals will not 

violate State water quality standards.”

Alternative C (No Herbicides)

Alternative C utilizes nonchemical treatment methods that would also have a low risk of 

adversely impacting water resources because they would involve only short-term, low magnitude 

ground-disturbing activities that would occur in widely dispersed sites on the Forests.

Compared to Alternative B, this alternative would result in an additional 50 to 60 percent of the 

weed treatment acreage subject to somewhat greater ground disturbance. Reliance on these 

treatment methods would increase soil erosion and sedimentation because of the amount of 

burning, digging, pulling, mowing, grazing, etc. Because these methods are generally less 

effective than integrated methods that include herbicides, a higher frequency of repeat treatments 

would occur on the same sites. However, for the reasons described in Alternatives B and D, these 

disturbances would be relatively minor, especially within the context of treating 500 to 1,500 

acres per year scattered over a 3-million-acre project area.

The nonherbicide methods would be particularly difficult in controlling common species of 

weeds such as knapweeds and Canada thistle. If weeds are not controlled using nonherbicide 

methods, effects would be similar to Alternative A (no action). In those areas, weeds would 

continue to reduce native ground cover and increase the amount of erosion and runoff.

Alternative C would avoid the additional chemical loading to the environment from herbicide 

application. This would also avoid the risk of adverse effects on water resources from herbicides.

This difference is small because the additional chemical loading associated with Alternatives B 

and D is small, especially considering the limitation on the amount of herbicide application that 

may be used within each watershed.

Cumulative Effects

The analysis area for cumulative effects on water resources is the area in and immediately 

adjacent to the two forests. This boundary represents the portions of the watersheds where the 

actions proposed in this project are most likely to interact with other activities, in particular the 

weed treatments on both forest and other lands (private, State, BLM, etc).

Direct and indirect effects estimated to occur from this project include an insignificant increase in 

ground disturbance and sediment transport. Nearly all other ongoing and foreseeable future 

activities on the Forests would continue to contribute to erosion and sediment, including 

vegetation and fuel management projects, road maintenance or reconstruction, wildland fires, 

livestock grazing, and all recreational uses (see cumulative actions listed at the beginning of this 

chapter).

Final Environmental Impact Statement – Invasive Plant Control Project 127
Chapter 3 • Affected Environment and Environmental Consequences

Other activities on the Forests that contribute to the spread of weeds would combine cumulatively 

with the effects of Alternative A (no action), and together would increase the loss of desirable 

plant species and biological diversity, which in turn results in increasing surface water runoff, 

erosion, and sedimentation in affected watersheds. Also, as weed infestations become more 

severe throughout the forest, more intensive and extensive herbicide applications (probably with 

aerial methods) would likely be required to control later stages of weed growth.

Herbicide application conducted by adjacent landowners and agencies would cumulatively result 

in minor and short-term herbicide loading to the environment. The additional acres add a small 

amount that would not exceed EPA standards (refer to Appendix 1 for a list of past, ongoing and 

foreseeable future weed control treatments in northern New Mexico).

Considering these additional impacts from other land use activities in or near the Forests, overall 

water quality and quantity goals for the Forest Plan would be met.

128 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

Soil Resources 

Affected Environment

Soil landscapes on the Forests can be subdivided into three provinces with distinct soil 

assemblages: Colorado Plateau Semi-Desert, Southern Rocky Mountain Steppe, and Southwest 

Plateau Provinces (Bailey, 1995). The Rocky Mountain Steppe assemblage dominates the northcentral region of New Mexico, the Colorado Plateau dominates the southern and western areas, 

and the Southwest Plateau occurs primarily in the Pecos-Canadian Plains and Valleys in the 

eastern part of the State. Specific soils associated with each assemblage on the Forests are 

described as follows.

• Colorado Plateau Province: Immature soils that lack vertical development of horizons 

occur along the flood plains of major streams. Soils having shallow development and 

limited humus addition from vegetation cover plateau tops, older terraces, and alluvial 

fans. Because of limited rain and high temperatures, soil water tends to migrate in these 

soils in an upward direction. This condition causes the deposition of salts carried by 

water at or near ground surface because of evaporation. These properties give soils in this 

assemblage a tendency to contribute to high runoff rates.

• Rocky Mountain Steppe Province: Soils in the montane zone tend to exhibit relatively 

high base saturation and range from soils with thick, dark surface horizons that are high 

in organic matter to those with relatively little organic matter. These soils tend to allow 

higher infiltration during storm events. In the foothill zone, there is a tendency toward 

poor and shallow soil horizon development with limited humus additions from 

vegetation. Because of limited rain and high temperatures, soil water tends to migrate in 

these soils in an upward direction. This condition causes the deposition of salts carried by 

water at or near ground surface because of evaporation. Areas above timberline or on 

steep slopes show evidence of the beginning of weathering processes on parent material. 

Soils include areas of young, poorly developed soils similar to those found in arctic 

tundra environments, and relatively recent deposits of stream alluvium.

• Southwest Plateau Province: Most soils in this province are relatively low in organic 

matter, but contain distinct developed soil horizons. Some exhibit an accumulation of 

clay in the subsurface. Many are calcareous and have a notable carbonate accumulation

layer. Some soils are high in soluble salts, but generally are well drained and moderately 

fine textured to moderately coarse textured. Many soils in this group are classified as 

having intermediate potential for transport of herbicide to surface water.

Major factors in soil formation include type of parent material, climate, overlying vegetation, 

topography or slope, and time. Type of parent material influences the soil pH, structure, color, etc. 

High rainfall climates tend to have more acidic and less fertile soils, due to leaching of nutrients 

to lower levels of the soil profile. Low rainfall climates tend to accumulate salts near the surface 

and have generally higher soil pH. Soils that form under coniferous forests tend to be more acidic 

than those under deciduous forests, and root action is also critical in soil formation. Soils 

generally have a harder time forming on steep slopes, due to runoff of soil particles during rain 

events. The longer a soil has to form, the deeper its profile will be.

Information about soil conditions on the Forests was determined using Forest Service Geographic 

Information System (GIS) and terrestrial ecosystem surveys (USDA FS 1987c and USDA FS 

Final Environmental Impact Statement – Invasive Plant Control Project 129
Chapter 3 • Affected Environment and Environmental Consequences

1993). This information includes soil type, texture class, mineral class, soil depth class, rock 

fragments, slope, and soil development class. Based on consideration of these soil conditions, it 

was concluded that soil development class established according to soil type sufficiently 

characterized soil conditions for the purposes of this analysis. Two other key soil properties in the 

terrestrial ecosystem surveys influence the expected impacts: the soil erosion hazard rating and 

revegetation potential.

Figure 10 shows the soils mapped according to erosion hazard rating, and Figure 11 shows soils 

by revegetation potential rating. Tables 33 through 40 show the respective treatments as described 

by these soil properties.

130 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

Figure 10. Soil Erosion Hazard

Final Environmental Impact Statement – Invasive Plant Control Project 131
Chapter 3 • Affected Environment and Environmental Consequences

Figure 11. Soil Revegetation Potential

132 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

Environmental Consequences

Alternative A (No Action)

Without the proposed weed control treatments, weeds would continue to spread where they occur 

and potentially invade other areas. Weeds would continue to affect soil because they can outcompete native species for water and nutrient resources in the soil (Olson 1999). Broadleaf weeds 

often produce deeper taproot systems and less canopy cover compared to the native species that 

they displace (DiTomaso 1999). Weeds often reduce organic matter and microbial biomass 

production such that weed-infested soils support smaller populations of microorganisms than 

noninfested soil (Brady and Weil 1999). In addition, weeds have high nutrient uptake rates and 

can deplete soil nutrients to very low levels (Olson 1999). Weeds would continue to reduce water 

infiltration to the soil and increase surface runoff and sediment production because weeds have 

lower canopy cover and allow crusting of exposed soil (Lacey et al. 1989; DiTomaso 1999; Olson 

1999). With less cover than native species, weeds are less able to dissipate the kinetic energy of 

rainfall, overland flow, and wind that cause soil erosion (Torri and Borselli 2000; Fryrear 2000). 

Tap-rooted weeds can reduce infiltration because they do not have the dense, fine root system of 

grasses. Due to these physiologic and morphologic differences, the uncontrolled expansion of 

weed infestations can have long-term and cumulatively adverse effects on soil properties, 

productivity, and overall soil quality.

Table 33. Acres Treated by Soil Erosion Hazard Rating

Erosion Class Alt. B Alt. C Alt. D

Slight 1,153 1,153 1,107

Moderate 4,112 4,113 2,623

Severe 2,077 2,077 1,704

Totals 7,342 7,342 5,434

Table 34. Acres Treated by Severe Soil Erosion Hazard Rating

Treatment Alt. B Alt. C Alt. D

Biological-grazing 0 0 0

Biological 28 79 0

Biological: Jemez RD 311 311 0

Prescribed fire 0 765 0

Prescribed Fire-mechanical 9 9 0

Herbicide 1,154 0 1,704

Herbicide-grazing 6 0 0

Manual 13 392 0

Manual-grazing 10 15 0

Manual-herbicide 469 0 0

Manual-mechanical 0 154 0

Mechanical 23 348 0

Mechanical-biological-grazing 4 4 0

Mechanical-herbicide 50 0 0

Totals 2,077 2,077 1,704

Final Environmental Impact Statement – Invasive Plant Control Project 133
Chapter 3 • Affected Environment and Environmental Consequences

Table 35. Acres Treated by Moderate Soil Erosion Hazard Rating

Treatment Alt. B Alt. C Alt. D

Biological-grazing 16 16 0

Biological 95 164 0

Biological: Jemez RD 1,459 1,459 0

Prescribed fire 0 1,283

Herbicide 2,349 0 2,623

Herbicide-grazing 21 0 0

Manual 28 171 0

Manual-grazing 48 69 0

Manual-herbicide 59 0 0

Manual-mechanical 0 12 0

Mechanical 1 931 0

Mechanical-biological-grazing 8 8 0

Mechanical-herbicide 28 0 0

Totals 4,112 4,113 2,623

Table 36. Acres Treated by Slight Soil Erosion Hazard Rating

Treatment Alt. B Alt. C Alt. D

Biological-grazing 18 17 0

Biological 12 12 0

Prescribed fire-mechanical 73 73 0

Herbicide 4 0 1,107

Herbicide-grazing 10 0 0

Manual 2 976 0

Manual-grazing 33 43 0

Manual-herbicide 955 0 0

Manual-mechanical 24 0

Mechanical 4 0

Mechanical-biological-grazing 2 4 0

Mechanical-herbicide 44 0

Totals 1,153 1,153 1,107

Table 37. Acres Treated by Revegetation Potential

Revegetation Class Alt. B Alt. C Alt. D

Low 2,307 2,310 1,288

Moderate 2,542 2,549 1,706

High 2,488 2,489 2,437

Totals 7,337 7,348 5,431

134 Final Environmental Impact Statement – Invasive Plant Control Project
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Table 38. Acres Treated by Low Revegetation Potential

Treatment Alt. B Alt. C Alt. D

Biological-grazing 2 2 0

Biological 119 207 0

Biological: Jemez RD 968 968 0

Prescribed fire 0 559 0

Prescribed fire-mechanical 4 4 0

Herbicide 1,008 0 1,288

Herbicide-grazing 26 0 0

Manual 27 152 0

Manual-grazing 15 41 0

Manual-herbicide 77 0 0

Manual-mechanical 0 40 0

Mechanical 1 336 0

Mechanical-biological-grazing 0 1 0

Mechanical- herbicide 60 0 0

Totals 2,307 2,310 1,288

Table 39. Acres Treated by Moderate Revegetation Potential

Treatment Alt. B Alt. C Alt. D

Biological-grazing 12 12 0

Biological 6 6 0

Biological: Jemez RD 802 802 0

Prescribed fire 0 1038 0

Prescribed fire-mechanical 6 6 0

Herbicide 1,377 0 1,706

Manual 6 368 0

Manual-herbicide 296 0 0

Manual-mechanical 0 20 0

Mechanical 0 285 0

Mechanical-biological-grazing 3 3 0

Mechanical-herbicide 34 0 0

Totals 2,542 2,549 1,706

Table 40. Acres Treated by High Revegetation Potential

Treatment Alt. B Alt. C Alt. D

Biological-grazing 21 19 0

Biological 10 43 0

Prescribed fire 0 447 0

Prescribed fire-mechanical 71 71 0

Herbicide 1,120 0 2,437

Herbicide-grazing 10 0 0

Final Environmental Impact Statement – Invasive Plant Control Project 135
Chapter 3 • Affected Environment and Environmental Consequences

Treatment Alt. B Alt. C Alt. D

Manual 10 1,020 0

Manual-grazing 75 86 0

Manual-herbicide 1,110 0 0

Manual-mechanical 0 130 0

Mechanical 23 662 0

Mechanical-biological-grazing 10 11 0

Mechanical- herbicide 28 0 0

Totals 2,488 2,489 2,437

Alternative B (Proposed Action)

Data indicate that herbicides can affect diversity and relative biomass of individual species of soil 

microorganisms. Exposure to herbicides can influence soil microbial populations (Forlani et al. 

1995, Ka et al. 1995, SERA 2003a). It is likely that a temporary shift in the soil microbial 

community would occur immediately following herbicide applications. Presumably, this is caused 

by microorganisms that are resistant or adapted to utilize the herbicide as an energy source, 

allowing them to gain a competitive advantage over nonadapted microorganisms.

However, other researchers found that herbicide additions had no effect on soil bacteria, 

nematodes, or collembola beyond what could be expected due to the associated reduction in 

ground cover (Wardle et al. 2001). Clearly, the complex interactions between soil biota, 

environment, and herbicide type make predictions of impacts on soil biota difficult.

While herbicide exposure can influence the diversity of soil microorganisms, the reported data 

indicate that this influence is transient as long as adequate time is allowed for the soil community 

to rebound between exposures. Brady and Weil (1999) report that negative effects of most 

pesticides on soil microorganisms are temporary and populations generally recover after a few 

days or weeks.

Considering this short recovery time, the soil microbial community is expected to return to preherbicide levels within a year of herbicide application under the proposed schedule. Even in the 

presence of more highly persistent herbicides, microbial populations are expected to rebound in 

the short term (1 to 3 years after treatment begins) once the herbicide application program enters 

the maintenance mode and applications occur less frequently. Additionally, only a relatively small 

portion (600 to 1,600 acres) of the 3-million-acre project area would be treated for weeds each 

year.

Certain herbicides, such as glyphosate and dicamba, have been observed to cause weight 

reductions or mortality in earthworms. Surviving earthworms would be expected to recover, but 

the population may be decreased after each herbicide application. Soils with reduced earthworm 

populations would exhibit reduced water infiltration, nutrient cycling, and fewer stable soil 

aggregates compared to similar soils with greater earthworm populations (Brady and Weil 1999). 

In areas where earthworms are susceptible to the type of herbicide applied, the population may 

remain suppressed until application ceases. A study of the effects of herbicide on soil arthropods 

found that no significant change in the arthropod population occurred due to herbicide exposure 

136 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

(Fuhlendorf et al 2001). The arthropod population was extremely variable from year to year 

regardless of herbicide application.

Surfactants may be used to increase the efficiency of herbicides. Limited data are available for 

use in predicting the effects of surfactants on soil quality. Oakes and Pollak (1999) found that the 

surfactant used in Tordon-75D caused damage to submitochondrial particles when applied in the 

presence or absence of the remaining ingredients of the herbicide. This indicates that damage to 

eucaryotic soil organisms would occur. However, in this case, it is presumed that the damage 

would be limited to that described above for herbicide effects on soil biota. It is unknown whether 

surfactants added to herbicides would cause additional impacts on soil quality beyond those 

already discussed for herbicides. Tordon-75D is a formulation that combines picloram with 2, 4-

D and is not used in Forest Service programs (see risk assessments).

Overall in the long term, herbicide applications would improve soil quality by controlling weeds 

and minimizing the negative effects of weeds (Lacey et al., 1989; Olson, 1999; Olson and Kelsey, 

1997).

The foot traffic, off-road vehicles and other ground disturbance associated with Alternative B

would expose soil to minor amounts of compaction and erosion in small, localized treatment sites. 

Some soil disturbance would occur on soils with a severe soil erosion rating. Treatments on soils 

having a severe erosion hazard rating include approximately 1,150 acres of herbicide methods, 

470 acres of manual-herbicide methods, and 80 acres of mechanical-herbicide methods.

A short-term increase in soil erosion would occur from ground-disturbing control methods where 

weeds are eradicated until native vegetation becomes established. Most of the known weed 

infestations lie near roads, camping sites, trails and other areas with a pre-existing level of soil 

disturbance. These weed infestation areas are also currently experiencing increased erosion and 

soil degradation as a result of weed infestation, so any additional increase in erosion resulting 

from weed removal should be inconsequential and would cease once native vegetation is 

established. The common presence of loam or sandy loam soils with rock fragments would also 

help minimize erosion and promote re-establishment of native vegetation. Mitigation measures 

prohibit the use of heavy equipment such as mowers or mechanized diggers, as well as off-road 

vehicles, on slopes over 40 percent which further reduces the potential for excess erosion to 

occur.

The mitigation measure and best management practice that requires revegetation of bare soil 

where needed following weed control treatments, would contribute to ensuring long-term soil 

productivity goals are met. Revegetating with mulch or seeds after weed control treatment would 

most likely occur on less than 1,000 acres of soils proposed for herbicide treatment on soils with a 

low revegetation potential. Where revegetation potential is moderate or high, there is an increase 

in the ability to re-establish and maintain the desired native plant communities. On soils with low 

revegetation potential, the preferred recovery is natural revegetation. Mulching of these sites with 

certified weed-free straw is preferred to provide surface soil cover, which will offer protection 

from surface soil erosion and encourage natural revegetation of the site. Where natural 

revegetation does not occur, seeding with certified weed-free seed would occur.

The magnitude of soil disturbance impacts would be limited to the treatment area and duration 

would be limited to the recovery period (typically ranging from a few months to a year). Erosion 

rates would not exceed tolerance threshold levels established in the Forest Plans (USDA FS 1986, 

Final Environmental Impact Statement – Invasive Plant Control Project 137
Chapter 3 • Affected Environment and Environmental Consequences

1987). The Santa Fe National Forest Plan (USDA FS 1987) requires the forest to be within 

tolerance for soil loss rates within 2 years. The Santa Fe National Forest Plan (USDA FS 1987) 

shows the expected annual soil loss as 20,000 to 24,000 tons per year, with about 3,500 tons per 

year being from natural erosion. The tolerance limit for the forest is 6,670,500 tons per year.

In summary, these soil disturbances or impacts would not be considered detrimental when 

considered together with the beneficial, long-term improvements in soil quality and productivity 

in areas where weeds are treated and native vegetative cover is re-established. The nonherbicide 

treatment methods would likely not be as effective as herbicide application in eradicating weeds 

and, therefore, may require more repeat treatments.

The proposed Santa Fe National Forest Plan amendment would slightly modify the soil resource 

standards and guidelines. This alternative would eliminate the prohibition on using herbicides on 

soils with a low revegetation potential, since it would be counterproductive to meeting the 

purpose and need for this project and is not necessary in order to adequately protect soil 

resources. The proposed amendment would instead allow herbicide use on any soil type 

“provided that effective ground cover is quickly restored and soil erosion on that site is not 

reduced to below the tolerance level identified in the terrestrial ecosystem survey for the affected 

soil unit.” The amended language would not be expected to result in adverse impacts to soil 

qualities or long-term productivity when vegetation management projects such as this are 

implemented. The proposed amendment also deletes a very outdated standard that prohibits 

herbicides on soils with low cation exchange capacity. Cation exchange capacity is not a measure 

used by the Forest Service and is, therefore, not appropriate as a criterion for vegetation 

management activities. Deleting that sentence in the Forest Plan would not be expected to result 

in an impact to soil resources when vegetation management projects such as this are 

implemented. 

Alternative C (No Herbicide)

As herbicides would not be used, this alternative would not result in any of the minor, short-term 

effects of herbicides on the soil microbial community that were described for Alternative B. This 

benefit to soil quality, however, would be minor compared to the positive effects to soil from 

more promptly reducing weed infestations using herbicides.

Since Alternative C involves more digging, mowing, burning, grazing and other nonherbicide 

treatment methods, and more repeated treatments on the same sites, more soil disturbance would 

result. In Alternative C, approximately 1,700 acres of mechanical, manual, burning and grazing 

treatments would be applied on soils with severe erosion hazard rating. Repeated treatments 

would continue to disturb the site and would extend the duration of time that these soils are 

vulnerable to erosion. However, the short-term effect on soil quality would be countered in the 

long term by the benefit of curtailing the ongoing spread of weed populations across the Forests. 

Desirable vegetation would have the chance to re-establish, thereby protecting against erosion. 

Mitigation measures that require revegetation by seeding or mulching where needed to prevent 

excess erosion would minimize the minor, short-term increases in erosion expected under this 

alternative, even on soil with low revegetation potential.

Because Alternative C would not eradicate or successfully control weeds across the Forests as 

quickly as the other action alternatives, weed populations would continue to spread and create a 

large impact to soils. In those areas, adverse effects on soil properties and quality would be 

similar to that described under Alternative A, although on fewer acres. These effects include 

138 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

reduced organic matter and microorganism populations, depleted soil nutrients, reduced water 

infiltration capacity, and increased evaporation.

Alternative D (Herbicide Only)

The effects of herbicides would be virtually the same as described for Alternative B, in terms of 

the low magnitude, short duration impacts on soil microorganisms and earthworms. There would 

be a much more significant beneficial effect from using herbicides to control and eradicate weeds 

in improving long-term soil quality and productivity.

As described for Alternative B, application of herbicides from ground-based vehicles has the 

potential to have minor soil disturbing or compacting effects. While 1,700 acres of treatment 

would be on soils with severe erosion hazard rating, a small portion of those acres would involve 

off-road-vehicle use that has the most effect on soil disturbance. Herbicide application conducted 

by personnel with backpack sprayers or from vehicles on existing roads would not noticeably 

increase soil disturbance. Native vegetation and other ground cover is expected to become 

established even on sites with low revegetation potential using the mitigation measures described 

for Alternative B in Chapter 2. Other effects would be similar to those described for Alternative 

D, erosion rates would be within “tolerance rates” for the Forests and long-term soil productivity 

would be maintained.

In considering potential effects of the proposed amendment to the Santa Fe National Forest Plan 

regarding herbicide use under specific soil conditions, there would be no impact to soil resources 

expected (as described for Alternative B).

Cumulative Effects 

The analysis area for cumulative effects on soil resources is the area in and immediately adjacent 

to the two forests. This boundary represents the areas where the actions proposed in this project 

are most likely to interact with other activities, in particular the weed treatments and ground 

disturbance on both forests and other lands (private, State, BLM, etc).

Past, present and foreseeable future actions that may have cumulative effects on soil are listed in 

the beginning of this chapter and include grazing, recreational uses, wildfire, and other vegetation 

altering activities. These actions may have a cumulative effect on soil erosion, compaction, or 

other indicators that define soil quality and provide for the spread of weeds.

Activities that contribute to the spread of weeds would add to effects of Alternative A (No 

Action), which would add to the reduction in soil quality caused by weeds. Soil degradation 

would increase commensurate with the amount of weed spread. For the short term, these additive 

effects would not cause a large-scale loss of soil productivity. Over the long term, as weed 

infestations become more dominant, loss of soil productivity would become evident.

All activities and land uses on the forest contribute to soil disturbance and some level of erosion. 

Those activities would add to the minor, short-term increases in erosion associated with the action 

alternatives. Because land management activities are controlled and mitigated to avoid excessive 

rates of erosion and maintain soil productivity, cumulative effects of weed treatments with these 

other activities is expected to be negligible. Cumulatively, soil erosion rates should remain within 

tolerance thresholds established in the Forest Plans and would not impair long-term soil 

productivity.

Final Environmental Impact Statement – Invasive Plant Control Project 139
Chapter 3 • Affected Environment and Environmental Consequences

In addition, most ongoing and foreseeable future activities have objectives aimed at enhancing 

and restoring ecosystem functionality and healthy water and soil conditions. Many recent projects 

have successfully improved soil productivity. These projects include road decommissioning and 

closures, reduced grazing in riparian areas, reduced motorized use, and reduced camping in 

riparian areas. These would cumulatively combine with the long-term beneficial effects of the 

proposed weed treatment project in reducing soil erosion and sediment sources.

Cumulative effects on soil quality also would occur for Alternatives B and D from the herbicide 

loading added from other public agencies and private landowners in the area. Cumulative effects 

may occur to soil organisms from herbicide applications; however, these adverse impacts are 

expected to be short term and limited in extent to the treatment sites. Cumulatively, treatments 

would not affect soil organisms located away from treatments (on forest or off). Beneficial 

cumulative effects would occur for weed treatment areas where native vegetation communities 

increase and long-term soil qualities improve.

Ongoing weed control programs conducted by State and Federal highway authorities and others 

in the general area have very similar effects, contributing to cumulative effects. Off-road vehicles 

used for weed treatment in particular would add to soil compaction caused by off-road vehicles

used in other recreational and land management activities throughout the Forests. The additional 

impact from this project would be undetectably small because off-road vehicles used for weed 

control would typically be a single pass through an area compared to the off-road vehicle trail 

creation that often results from recreational off-road-vehicle use.

140 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

Air Quality 

Affected Environment

New Mexico and the Federal Government have established air quality standards for specific 

criteria air pollutants. The criteria pollutants are carbon monoxide (CO), lead (Pb), sulfur dioxide 

(SO2), particulate matter smaller than 10 microns (PM10), and particulate matter smaller than 2.5 

microns (PM2.5), ozone (O3), and nitrogen dioxide (NO2). Of those seven criteria pollutants, the 

pollutants of concern for this project are the particulate matter pollutants PM2.5 and PM1010.

Air quality in the project area is classified as attainment for all criteria pollutants. A 

“nonattainment” designation means that violations of standards have been documented in the 

region. The only nonattainment areas in New Mexico are the southern part of the State.

Table 41 lists Federal and State air quality standards.

Table 41. Ambient Air Quality Standards

Pollutant/Time-weighted 

Period

Federal Standard 1

New Mexico 

Standard Primary 2 Secondary2

PM10

Annual Arithmetic Mean 50 μg/m3 50 μg/m3 (same as Federal)

24-hour Average 150 μg/m3 150 μg/m3 "

PM2.5

Annual Arithmetic Mean 15 μg/m3 15 μg/m3 "

24-hour Average 65 μg/m3 65 μg/m3 "

Sulfur Dioxide (SO2)

Annual Average 0.03 ppm - - 0.02 ppm

24-hour average 0.014 ppm - - 0.10 ppm

3-hour average - - 0.50 ppm - -

Carbon Monoxide (CO)

8-hour average 9 ppm - - 8.7 ppm

1-hour average 35 ppm - - 13.1 ppm

Ozone (O3)

1-hour average 0.12 ppm 0.12 ppm - -

8-hour average 0.08 ppm 0.08 ppm - -

Nitrogen Dioxide (NO2)

Annual Average 0.053 ppm 0.053 ppm

Annual Arithmetic Average - - - - 0.05 ppm

24-hour Average - - - - 0.10 ppm

Final Environmental Impact Statement – Invasive Plant Control Project 141
Chapter 3 • Affected Environment and Environmental Consequences

Pollutant/Time-weighted 

Period

Federal Standard 1

New Mexico 

Standard Primary 2 Secondary2

Lead (Pb)

Quarterly Average 1.5 μg/m3 1.5 μg/m3 - -

Total Suspended Particulate

24-hour average - - - - 150 μg/m3

7-day average - - - - 110 μg/m3

30-day average - - - - 90 μg/m3

Annual Geometric Mean - - - - 60 μg/m3

1 μg/m3 = micrograms per cubic meter; ppm = parts per million 2 Primary standards are set at levels to protect human health; secondary standards are set to protect public welfare

Source: EPA NAAQS, State of New Mexico

Areas within and around the project area are a mix of designated Class I and Class II airshed

areas as defined by the Federal Prevention of Significant Deterioration of Air Quality program. 

The Class II designation allows for moderate degradation of air quality within certain limits 

above baseline air quality. A Class I designation provides the most protection to pristine land, 

limiting the increment above baseline pollution levels. The standards are much stricter for Class I 

than Class II areas. Class I areas located near or within the project area include the Wheeler Peak 

Wilderness, Pecos Wilderness, and San Pedro Parks Wilderness, and Bandelier National 

Monument. Class II wilderness areas located in or near the project area are the Chama River 

Canyon Wilderness and Cruces Basin Wilderness.

Southwesterly winds typically blow across the mountainous region of northern New Mexico. 

Industry and power generation from as far away as California or as nearby as the Four Corners 

region contribute plume blight and haze. Temperatures vary from an average daily maximum of 

86 o

F in July in Jemez Springs to an average daily minimum of 3 oF in Dulce in January (data 

from Western Regional Climate Center).

Table 42 summarizes the range of PM2.5 and PM10 pollutants found in or near the project area 

from 1993-2003, from the State’s air quality monitoring data.

Table 42. Air Quality 1999-2003: PM10 PM25 Pollutants

Site Annual Geometric 

Mean (μg/m3)

24-Hour 

High (μg/m3)

24-Hour 2nd 

High (μg/m3)

Runnels Building, Santa Fe 13-14 34-71 28-42

Fire Station Santiago Road, Taos 14-21 33-67 31-66

Runnels Building, Santa Fe 4.6-4.9 11-19 10-15

PM10 = Particulate Matter < 10 Microns; PM2.5 = Particulate Matter < 2.5 Microns; μg/m3 = micrograms per cubic meter 

Source: EPA Ambient Air Quality Data

There are many offsite sources (facilities) capable of impacting air quality over the project area, 

such as power plants and oil and gas operations in the Four Corners area, natural gas compressor 

stations and refineries in the San Juan Basin, mining operations in Taos, Santa Fe, and Rio Arriba 

142 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

Counties, and other sources such as foundries and landfills (EPA National Emissions Inventory). 

Table 43 provides total particulate emissions from all sources in 1999 for selected northern New 

Mexico counties, from EPA National Emissions Inventory.

Table 43. Particulate Emissions in Northern New Mexico, 1999

County PM10 (tons per year) PM2.5 (tons per year)

San Juan 74,689 16,637

Rio Arriba 47,103 8,073

Taos 34,474 5,838

Colfax 11,245 2,213

McKinley 63,970 10,829

Sandoval 33,954 6,103

Los Alamos 1,551 350

Santa Fe 53,292 9,037

Mora 8,200 1,496

San Miguel 20,767 3,783

Environmental Consequences

Alternative A (No Action)

Under the No Action Alternative, there would be no impact to air quality.

Alternative B (Proposed Action)

Gaseous emissions, including sulfur dioxide (SO2), carbon monoxide (CO), oxides of nitrogen 

(NOx), and volatile organic compounds (VOCs), would result from combustion of fuel used to 

transport workers to and from project sites and during ground applications. The amount of 

gaseous exhaust emissions depends on size, age, and fuel efficiency of the engines. The amount 

of Hazardous Air Pollutants (HAPs) released during combustion of fossil fuels is very low and 

would pose no threat to health or the environment. Emissions from combustion of fossil fuels 

during vehicle applications would be insignificant.

Road dust would be generated from vehicle traffic on dirt roads during various weed treatment 

methods. Road dust during spraying activities would be limited due to relatively slow vehicle 

speeds necessary for herbicide application or other weed control treatments. Similarly, dust 

generated from mowing or root plowing would be limited due to relatively slow vehicle speeds.

During ground application, spray drift of herbicides is possible. This drift is not expected to 

produce any long-term ambient air quality impacts. Spray drift is short term in nature and limited 

to areas immediately adjacent to the plant populations being sprayed. The quantity of herbicide 

released to the atmosphere would not be expected to have a long-term impact on air quality.

Prescribed burning would result in particulate matter (PM10 and PM2.5) emissions in smoke. 

However, all prescribed burning must comply with the New Mexico smoke management system 

to maintain levels of emissions within standards, and burn permits are required prior to 

implementation of burning activities on the Forests.

Final Environmental Impact Statement – Invasive Plant Control Project 143
Chapter 3 • Affected Environment and Environmental Consequences

Criteria pollutant emissions have been estimated for alternatives based on treatment activities 

presented in Chapter 2. Since impacts will be distributed across both forests and over time, 

concentrations of air contaminants will not accumulate to the point of violating air quality 

standards for any area. Air quality standards identified in the previous section would all be met.

Emissions were calculated based on the proposed treatments for each area, with the exception of 

the particulate emissions from vehicles. For vehicle treatment areas, vehicle miles were estimated 

based on assumed travel of 1/8 mile per acre. Road dust emissions were calculated using unpaved 

road emission equations in EPA AP-42, Section 13.2.2. Calculations are based on uncontrolled 

road dust emissions, assuming no road watering or chemical dust suppression. This overestimates 

the likelihood of dust emissions as road watering to suppress dust emissions is often employed 

during forest management activities. Smoke emissions from prescribed burning of weeds were 

calculated using EPA’s AP-42 emission factors.

Table 44 summarizes total emissions for each alternative. The total estimated emissions are for 

the entire life of the project, estimated at approximately 10 years, not annual totals.

Table 44. Summary of Total Emissions by Alternative

Criteria Pollutant

Estimated Emissions (tons)

Alt. A Alt. B Alt. C Alt. D

PM10 0.00 0.54 5.1 0.18

PM2.5 0.00 0.32 4.1 0.03

Note: PM10 = particulate matter smaller than 10 microns

PM2.5 = particulate matter smaller than 2.5 microns

Visibility is one air quality related value that has been identified as being important for each of 

the three Class l areas. Visibility conditions are affected by scattering and absorption of light by 

particles and gases. Fine particles most responsible for visibility impairment are sulfates, nitrates, 

organic compounds, soot, and soil dust. Fine particles are more efficient per unit mass than coarse 

particles at scattering light. Emissions previously described would be very short term and not 

expected to degrade visibility. Emission reduction techniques would be employed during burning 

to mitigate smoke impacts to visibility.

Alternative C (No Herbicide)

Implementation of Alternative C would result in potentially greater amounts of dust from mowing 

and root plowing, and more particulate emissions from prescribed burning than Alternatives B or 

D. This would result in a slight increase in PM10 and PM2.5 from dust and smoke. Otherwise, 

effects would be similar to Alternative B. Because estimated emissions are low and these 

emissions would be distributed across the forest and over time, concentrations of air contaminants 

will not accumulate to the point of violating air quality standards for any area.

Alternative D (Herbicide Only)

Impacts on air resources from implementation of Alternative D would be similar to those under 

Alternative B, except less dust would be created and there would be no smoke emissions.

144 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

Cumulative Effects

Other activities and natural occurrences (such as wildfire) that occur at the same time as weed 

control activities and in the same general areas would add to the direct and indirect air quality

effects described. Those activities include all prescribed burning activities, and offsite activities 

such as upwind industrial sources. The dispersion in the air and the small amount of emissions 

produced by treatments at any given time and place would result in no noticeable cumulative 

increases in emissions within the airshed, even when considered with other ongoing and 

foreseeable future activities.

Final Environmental Impact Statement – Invasive Plant Control Project 145
Chapter 3 • Affected Environment and Environmental Consequences

Heritage Resources

Affected Environment

Introduction

The National Historic Preservation Act of 1966 (NHPA) and the Forests’ plans provide the 

primary requirements applicable to situations where proposed management activities could 

potentially affect heritage resources on the Forests. Other applicable requirements come from the 

Archeological Resources Protection Act, American Indian Religious Freedom Act, Executive 

Orders (11593, 13175 and 13287), and other laws, regulations and policies.

Under Section 106 of NHPA, the Forests are required to evaluate effects of proposed management 

activities to historic properties (archeological sites and ethnographic resources including 

traditional cultural properties). The Forests must also follow Forest Plan standards and guidelines 

for protecting heritage resources and coordinating with Native American tribes.

This document analyzes proposed weed treatment activities in accordance with NEPA, and tiers 

to a programmatic agreement developed for this project to address applicable Section 106 NHPA 

process requirements. The programmatic agreement between the Forests, New Mexico State 

Historic Preservation Office (SHPO) and the Advisory Council on Historic Preservation specifies 

that heritage clearance and/or survey will be completed prior to implementation of weed 

treatments. The programmatic agreement specifies the process to be followed prior to 

implementation to identify historic properties, evaluate the significance of a property, evaluate the 

effects from site-specific activities, and identify ways to avoid or mitigate adverse effects to 

heritage resources. Tribal consultation requirements are also addressed in the programmatic 

agreement, as well as monitoring requirements. If adverse effects cannot be avoided, then the 

Forests would consult with the SHPO, the Advisory Council and interested parties and develop an 

appropriate mitigation plan.

Weed control methods such as manual and mechanized ground-disturbing treatments would need 

to follow the steps outlined in the agreement. Other methods, such as biological methods or direct 

hand application of herbicides to target weed species, were considered to have little or no effect 

on heritage resources and are exempt from further consideration under Section 106. The 

agreement is available in the project record.

The affected environment considered for this weed control project includes all areas containing 

heritage resources (archeological and ethnographic resources) on the Forests, since new weed 

infestations may occur virtually anywhere on the Forests. However, the number of known 

heritage resource sites that overlap inventoried weed infestation sites is low.

Table 45 illustrates the number of known heritage sites intersected by currently inventoried weed 

infestations for three standardized site sizes. The point data are for the geographic center of the 

site and do not reflect site size but site location. For this analysis, however, each point is 

considered to represent 1 acre. The 50-meter data reflect standardized site size at a 50-meter

radius (1.9 acres) and the 100-meter data at a 100-meter radius (7.8 acres). The standardized site 

sizes do not represent the full variability of actual site size but are intended to be illustrative of the 

potential for sites to be affected by weed treatments.

146 Final Environmental Impact Statement – Invasive Plant Control Project
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Table 45. Affected Heritage Resource Sites by Relative Site Size

Known Sites Point Data 50-Meter Radius 100-Meter Radius

Forest Total 

Sites

No. of 

Sites 

Affected

Cumulative 

Size 

(acres)

No. of 

Sites 

Affected

Cumulative 

Size 

(acres)

No. of 

Sites 

Affected

Cumulative 

Size 

(acres)

Carson 4,156 13 (0.3%) 13 67 (1.6%) 127.3 187 

(4.5%) 1,458.6

Santa 

Fe 7,965 63 (0.7%) 63 169 (2.1%) 321.1 480 (6.0%) 3,744.0

Total 12,121 76 (0.6%) 76 236 

(1.9%) 448.4 667 (5.5%) 5,202.6

Heritage resource surveys have been conducted on approximately 150,000 acres (10 percent) of 

the 1.5-million-acre Carson National Forest, and 460,000 acres (30 percent) of the 1.6-millionacre Santa Fe National Forest. Approximately 4,200 heritage resource sites have been recorded on 

the Carson National Forest and 8,000 heritage resource sites have been recorded on the Santa Fe 

National Forest. It is estimated that the Forests have over 45,000 and 35,000 total heritage 

resource sites (respectively).

In general, the distribution of sites reflects the distribution of heritage resource survey, such that 

known sites that overlap inventoried weed infestations serve as an indicator of the extent of 

weeds within heritage resource sites. Since weeds have not been systematically inventoried and 

the distribution of heritage resource survey is a function of where projects have occurred, the 

existing sample of weed infestations compared to site distribution may not accurately reflect the 

true distribution of weeds across heritage resources.

Heritage resource site density across the Forests varies tremendously depending on a number of 

factors. Site density on the Carson National Forest averages approximately 18 sites per square 

mile. Site density on the Santa Fe National Forest may average 3 to 4 sites per square mile on the 

east side and 15 sites per square mile on the west side. Because of varying settlement factors, site 

density in ideal locations on either forest may be considerably higher. Some areas in the Jemez 

Mountains have a very high site density of 100 sites per square mile, and site density on the 

Jicarilla Ranger District can be comparable.

Heritage resource sites that may be affected by weed treatment activities fall broadly into two 

categories: archeological and ethnographic resources (including traditional cultural properties). 

These resources are described in the following two sections.

Archeological Resources

Archeological resources are generally defined as the nonrenewable evidence of human 

occupation or activity (as indicated by sites, buildings, structures, artifacts, ruins, objects, works 

of art, petroglyphs/pictographs, architecture, or natural features) that were important in human 

history at the State, local, or national level. Archeological resources consist of the material 

remains of human activities on the Forests, including prehistoric and historic sites. Generally, 

prehistoric sites include those dating to prior to the entrance of European populations in the area; 

prior to A.D. 1541. Historic sites include those dating after European contact from A.D. 1541 up 

to modern times, that are 50 years or older. The Forests have a long history of human use. Site 

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types are diverse across both forests and include, but are not limited to, small artifact scatters, 

agricultural fields, pit houses, field houses, quarry and other resource procurement sites, pueblos, 

historic cabins, logging camps, homesteads, and mines. Historic sites range from the Spanish 

exploration period, through the Pueblo Revolt, Spanish Colonial, Mexican, and American periods, 

representing a wide variety of activities that include logging, mining, ranching, exploration, trade, 

railroading, and homesteading.

Archeological sites occur in moderate to high site densities across the western portion of the 

Santa Fe National Forest. For the Carson National Forest, sites commonly occur along river 

corridors and on the Jicarilla Ranger District at lower elevations. Archeological sites are 

sometimes visible due to having weeds growing on the site, since many disturbance species thrive 

on soils that have been modified by human occupation and use. Artifact scatters and architectural 

remains often appear as ruined mounds covered with vegetation. At higher elevations, 

archeological site visibility decreases due to an increase in vegetative cover. Sites at higher 

elevations tend to be of shorter use and leave fewer material remains, and so are often more 

difficult to recognize. There also tend to be fewer weed infestations at higher elevations.

In Table 45, the 50-meter and 100-meter buffers are more accurate approximations of acres of

sites since sites generally have broader areas than what is reflected by the point data. In the case 

of the 50-meter buffer, approximately 450 acres of archeological sites may be currently affected 

by weeds. At the 100-meter buffer, approximately 5,200 acres of sites are affected by weeds. 

Since the Forests’ inventories of heritage resource sites and weeds are both incomplete, these 

numbers are used as approximations.

Both prehistoric and historic archeological sites may exhibit surface characteristics with the 

potential to be affected by weed treatments. Perishable remains that could be affected include 

wood, paint, and other organic materials. In addition, sites may contain sources of information 

that could be potentially affected, such as datable remains, including wood for C14 dating, 

obsidian for hydration dating, intact thermal surfaces for archaeomagnetic dating, and residual 

materials on artifact and feature surfaces.

Ethnographic and Traditional Cultural Property Resources

Ethnographic and Traditional Cultural Property (TCP) resources include sites and resources 

generally associated with living communities that have traditional and long-standing ties to an 

area. These remains must meet the definition of a TCP in Bulletin 38 of the National Register 

Guidelines to be considered under the implementing regulations of Section 106 of NHPA. The 

Forests will consider other traditional or tribal concerns, especially if they fall within the purview 

of executive orders and other legislation. These may consist of physical remains such as shrines 

and material procurement areas, but they can also include areas of cultural importance such as 

communal or ceremonial locations without an obvious physical context.

On the Forests these types of sites are generally associated with areas traditionally used by 

Hispanic or land grant communities (Abiquiu, Penasco, and Coyote for example), pueblos 

(Cochiti, Hopi, Jemez, Nambe, Picuris, Pojoaque, San Ildefonso, San Juan, Santa Clara, Santo 

Domingo, Taos, and Tesuque, Zia and Zuni), and other tribal communities (Jicarilla Apache, Ute, 

Kiowa, Comanche and Navajo). Indian reservations adjacent to the Forests include the Cochiti, 

Jemez, Nambe, Pojoaque, San Ildefonso, San Juan, Santa Clara, Santo Domingo, Tesuque, Zia, 

Taos, Picuris, Southern Ute and Jicarilla Apache.

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The Forests have a unique relationship with Federally recognized American Indian tribes, and 

other traditional communities. As Federal agencies undertake activities that may affect a tribe’s 

rights, property interests, or trust resources, they carefully implement those activities in a manner 

that respects the tribe’s sovereignty and resource needs. In addition, the NHPA requires an agency 

to evaluate effects to traditional cultural properties and practices within a project area.

There are no formal Indian Trust Assets on the Forests. However, the majority of the Forests 

cover traditional lands used by several tribes and other traditional communities. During 

consultation for this project, relevant concerns arose about the potential impacts from weed 

control treatments, such as: (1) potential loss of plant species that have a traditional, religious, or 

other use, and (2) potential health risks to those who collect herbicide-treated plants.

Native Americans and other groups use the Forests to collect plants and animals for food, 

medicine and religious ceremonies, clay for ceramics, minerals for ceramic paint, and wood for 

fuel and construction. Weed species proposed for treatment in the Forests do not appear to be 

those collected for traditional uses by Native American tribes located in the upper Rio Grande. 

However, Navajos traditionally use some of the weed species proposed for treatment, although 

individual species were not specifically identified (Begay 2000).

Recognition of traditionally used or sacred areas requires coordination with tribes and other 

traditional use groups. Places of elevation and line-of-sight connections are important in pueblo 

cosmology. The puebloan worldview includes specific places of traditional activity, considered to 

be historic properties. Similar concerns exist for other tribal communities that attach traditional 

and religious significance to parts of both forests. For Hispanic communities, areas of use in the 

Forests are tied to patterns of land tenure and land grant development. These areas continue to be 

used for ceremonial processions or gatherings.

Traditional cultural properties are often difficult to identify during standard heritage resource 

surveys, and none have been identified in the areas of potential affect during scoping and tribal 

consultation activities conducted to date for this project. Scoping and consultation for this project 

EIS was initiated in December of 2000, and an additional solicitation of comments was mailed to 

tribes in December of 2003, prior to release of the DEIS for public review.

Because the project can be designed to avoid direct impacts to archeological sites, it is anticipated 

that all sites will be avoided by mechanical treatments. If sites cannot be avoided, or if human 

remains are found during project implementation, the tribes, SHPO, and the Advisory Council 

will be contacted, and mitigation measures will be developed.

Environmental Consequences 

Alternative A (No Action)

If the proposed weed control project does not occur, there would be minimal, if any, impact to 

heritage resources. By not implementing proposed weed control actions, there would be no risk to 

heritage resource impacts from ground-disturbing activities.

All plant species are capable of disturbing soil stability and subsurface remains through invasive 

root growth. However, the effect of weed growth on the physical condition of sites has not been 

shown to be different than that of native plant growth.

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Weeds would continue to spread and over time would likely reduce or endanger native plant

species used traditionally. If weed removal is not implemented, then the Forests may be asked by 

traditional or tribal communities to eradicate weeds that threaten traditional use plants. If a weed 

is used traditionally, then no action may lead to enhanced growth and production of the plant, as 

well as use by the traditional community.

Alternative B (Proposed Action) 

Heritage resources are nonrenewable resources easily damaged by ground-disturbing activities. 

Although some artifacts are susceptible to damage from heavy equipment use, ground 

disturbance, or burning, it is the provenience of artifacts and features, or their horizontal and 

vertical location in relation to each other and to the soil deposits that is most important. 

Disturbance or movement of features and artifacts in relationship to each other disturbs or 

destroys the context of the information inherent in the site.

Impacts from weed control activities could lessen the value of heritage resources by destroying 

important scientific data and diminishing the physical setting of sites. Heritage resources can be 

diminished by any change in their historical, architectural, archeological, cultural character or 

ecological setting. Under the NHPA, an impact is considered significant if it results in an adverse 

effect to a heritage resource that is on or eligible for the National Register of Historic Places. An 

adverse effect would occur if a management activity alters the characteristics of a historic 

property that qualifies for inclusion on the National Register of Historic Places (NRHP).

Archeological Resources: Mechanical, manual, grazing and burning treatments have the highest 

potential for ground disturbance to archeological sites. Mechanical digging, mowing or tilling 

pose the greatest threat. Manually digging or pulling weeds could cause surface disturbance and 

displacement of buried archeological materials. Sheep or goat grazing could cause trampling of 

artifacts and disturbance to features. Prescribed burning could affect sites with fire-sensitive 

materials.

Herbicides and surfactants used with herbicides could impact the analytical potential of 

perishable materials such as wood, ceramic paint, and datable materials, although these effects 

have not been studied and the overall effect is not likely to be adverse. In general, herbicides do 

not have the persistence of pesticides and would not affect the chemical structure of archeological

remains. Biological methods would not be expected to damage sites, wooden beams or historic 

structures, since these herbivorous insects have a high degree of target host specificity.

Removal of weeds by any method could expose bare soil and increase soil erosion for a short 

time (typically a year or less), which could cause minor disturbance or damage to archeological

site features.

While the adverse effects described for archeological resources could potentially occur, there is a 

low risk of adverse impacts occurring. These effects would primarily be mitigated by avoidance 

of significant sites. Site-specific heritage resource survey and evaluation would be completed 

prior to implementing weed treatments (other than for exempt actions such as biological methods 

and hand application of herbicides). Sites would be identified for avoidance or other specific 

mitigation measures. The programmatic agreement requires forest archeologists to ensure that 

effects to historic sites are mitigated to avoid adverse effects while meeting weed control 

objectives. For example, if burning is used, fuel loading would be reduced on sites with firesensitive materials.

150 Final Environmental Impact Statement – Invasive Plant Control Project
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If based on survey and evaluation it is predicted that adverse effects to archeological resources 

cannot be avoided, the Forests would consult with the SHPO and other interested parties 

including tribes, concerning the steps to be taken to mitigate adverse effects. In addition, 

monitoring would be used to ensure that mitigation measures are followed and adequately 

protected heritage resources. If damage to an archeological site is discovered during 

implementation, the activity would be immediately halted and SHPO notified about the resolution 

of adverse effects. These and other requirements to protect heritage resources are spelled out in 

the programmatic agreement previously described.

Ethnographic Resources: Effects on ethnographic resources including traditional cultural 

properties are difficult to estimate because traditional communities are sometimes unwilling to 

provide location data as well as information on the nature of impacts. In some instances the mere 

presence of Forest Service workers or contractors in the area of a traditional cultural property can 

be an effect. Mitigation measures to alleviate auditory, visual, or other impacts on traditional 

cultural places require continuing consultation with traditional communities and flexibility in 

implementation.

The habitat of traditional plants would be affected by weed control activities that occur in the 

same area. The timing of weed treatment would take into account the traditional cyclic calendar 

of local communities as much as possible to still allow for effective treatment of a particular weed

species (e.g. if the time to treat is limited and corresponds to a traditional collection time). This 

timing would be accounted for through mitigation measures that include notification of tribes 

before use of herbicides occurs. This would also reduce the risk to those who use certain plants 

for traditional/cultural purposes and to the health of Native Americans who gather these plants. 

Treatment of the weeds would benefit these traditional use plants in the long run because of they 

would be better adapted in a native vegetation community and would be more sustainable in that 

ecological context.

Drift or chemical odor from herbicide applications or noise and dust from mechanical treatments 

may cause short-term adverse effects on traditional or religious sites. Mitigation measures that 

would minimize this impact include: using methods that reduce herbicide spray drift, posting 

signs during treatment activities, using direct hand application of herbicides onto target plants 

(avoiding surrounding plants), and notifying tribes.

Those same mitigation measures would be expected to greatly limit the risk of adverse impact to 

plants that have cultural importance. While there may be short-term removal of important plants, 

measures require re-establishment of desired vegetation, which would compensate for the shortterm reduction in the species, unless the treatment extirpates the plant species.

Mitigation measures would also be effective in avoiding impacts to fire sensitive areas of 

traditional concern if those areas are identified through additional consultation with traditional 

and tribal communities. A schedule of burning could be developed to reduce threats to 

traditionally used plant species or account for traditional practices in an area. For all treatment 

activities, monitoring will ensure that site treatment recommendations are followed and adequate 

to protect heritage resources.

Although effects to heritage resources associated with weed removal are estimated to be minor, 

they cannot be fully assessed until heritage resource survey and evaluation has been completed.

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Alternative C (No Herbicide)

Under this alternative, the greater reliance on mechanical, manual, grazing, and burning methods 

would slightly increase the risk that archeological sites would be damaged by ground-disturbing 

treatments. There would be no potential impacts from spraying herbicides under this no herbicide 

alternative. It eliminates the potential health risks to those who collect and use traditional plants. 

Otherwise, effects to both archeological and ethnographic resources would be the same as 

described for Alternative B.

Alternative D (Herbicide Only) 

Eliminating ground-disturbing weed control treatments (other than herbicide spraying using offroad vehicles) would reduce the risk of damage to archeological sites. Effects from herbicides on 

the analytical potential of perishable materials such as wood, ceramic paint, datable materials, and 

residues on artifacts has not been studied, but the overall effect is not likely to be adverse. No 

other effects would occur from herbicide application. Since little is known about the effects of 

herbicides on archeological sites, monitoring will be used to collect additional data on this 

treatment method.

Effects to ethnographic resources would be the same as those described for Alternatives B and C 

except this alternative would eliminate the noise, dust and visual impacts to traditional use areas 

associated with nonherbicide methods such as mechanical, grazing, or burning.

Cumulative Effects

Other past, ongoing and foreseeable future activities that could cumulatively impact heritage 

resources are listed in the beginning of this chapter and include: facility or road construction, 

maintenance, and use: thinning and prescribed burning projects, firewood harvest, livestock 

grazing and recreation activities. These activities all disturb plants and can impact both 

archeological and ethnographic resources. Livestock grazing and recreation activities may have a 

higher risk of impact as they tend to occur in the same location over a long period of time.

When added to effects of all the other public use and management actions on the forest, which all 

contribute to a risk of inadvertent impacts to heritage resource sites, the minimal effects from 

proposed weed treatment activities would increase the long-term risk of damage to heritage 

resources. However, the effects from this weed control project would not substantially increase 

the level of impact from ongoing and future activities. Because site avoidance is the typical 

method used during most land management activities on the Forests, and because the proposed 

treatment acreage is small relative to the total acreage on the Forests, the cumulative effects 

would be inconsequential. The same is true for ethnographic and traditional use areas.

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Recreation and Wilderness Resources

Affected Environment

Dispersed Recreation 

The Forests support a large demand for dispersed recreation activities such as hiking, driving for 

pleasure, viewing scenery and wildlife, riding horses, riding motorcycles, gathering forest 

products, water play, snowmobiling, bicycling, camping and picnicking, cross-country skiing, 

backpacking, and photography. It also includes a diverse array of hunting and fishing 

opportunities, as well as wildlife viewing, photography, painting or drawing. Much of the 

dispersed recreational uses originates in the small villages around the forest perimeter and 

contributes significantly to their way of life. The Forests are also a major attraction to the nearby 

population centers of Albuquerque, Santa Fe, Los Alamos, Espanola, Taos, and Farmington, as 

well as to visitors from west Texas, Oklahoma, southern Colorado, and Kansas.

There are 1,002 miles of Forest Service system trails on the Santa Fe National Forest and 540 

miles on the Carson, with over 50 percent in or adjacent to wilderness areas. The Carson National 

Forest also has 2,818 miles of system travel ways used as 4-wheel-drive roads for recreation, 

livestock trails, fire access routes, etc.

Three nationally designated scenic byways are located on the Forests: Enchanted Circle Scenic 

Byway, Jemez Mountain National Scenic Byway, and Santa Fe National Forest Scenic Byway.

Most of the dispersed recreation occurs along streams and around water bodies, as well as in 

wilderness and designated roadless recreation areas (see “Wilderness” subsection for more 

information on wilderness recreation). Camping and other recreational activities in undeveloped 

areas often result in removal of native vegetation and creation of disturbed soil conditions that are 

more susceptible to weed establishment. Horses and other pack animals frequently used for 

recreation tend to transport weeds, especially if hay and feed are brought in. Off-road-vehicle use 

is another common way for weed seeds to be spread throughout the forest.

Developed Recreation

Developed recreation facilities include campgrounds, picnic areas, trailheads, and other areas 

containing specialized recreation facilities that are planned to accommodate a fixed number of 

people at one time. Currently the Forests manage approximately 105 developed recreation sites. 

Developed recreation facilities include campgrounds, picnic areas, trailheads, and other areas 

containing specialized recreation facilities that are planned to accommodate a fixed number of 

people at one time. On the Santa Fe National Forest, most weeds mapped in or near developed 

recreation sites are located along the Jemez River, where saltcedar, Russian olive and Siberian 

elm have overgrown fishing access sites and campgrounds. Although there are limited 

populations currently mapped within developed recreation sites, the potential for expansion into 

more sites is high because of weed populations along roads leading to recreation facilities on the 

two forests. The Carson National Forest has weeds—including bull thistle and Canada thistle—in 

the June Bug, Elephant Rock and Cebolla Mesa Campgrounds (Questa Ranger District), and 

Canada thistle at the Santa Barbara Campground (Camino Real Ranger District). 

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Figure 12. Weeds Near Recreation Sites

154 Final Environmental Impact Statement – Invasive Plant Control Project
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Figure 13. Weeds in or Near Wilderness

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Ski areas on the Forests are: Santa Fe Ski Area, Taos Ski Valley, Red River Ski Area, Enchanted 

Forest Cross Country Area, and Sipapu Ski Area. There is one Boy Scout camp, one Girl Scout 

camp, one YMCA camp, and six recreation residences located within the Forests. Leafy spurge 

and bull thistle occur on the Philmont Boy Scout Ranch, and yellow starthistle is growing on the 

Rancho del Chaparral Girl Scout Ranch.

Wilderness

The seven congressionally designated wilderness areas on the Forests are: Wheeler Peak, Latir 

Peak, Cruces Basin, Pecos, Chama River Canyon, San Pedro Parks, and Dome, and there is one 

Wilderness Study Area—Columbine-Hondo. There are 25 acres of weeds mapped within 

wilderness areas on the Forests. Most of the weeds are bull thistle located near the boundaries of 

the wildernesses they are in, although there is a small patch, approximately 1.2 acres, of yellow 

toadflax mapped at the junction of Trails 69 and 71 within the Columbine-Hondo Wilderness 

Study Area. The largest is an approximately 5.6-acre patch of bull thistle in Latir Peak 

Wilderness. There is an approximately 3.4-acre patch of bull thistle in the northwest corner of 

Pecos Wilderness. The others are mostly 1 acre or less in size, located within the ColumbineHondo, Latir Peak, Wheeler Peak, or Pecos Wilderness areas. Approximately 300 acres of weed 

infestations (Canada thistle, musk thistle and Russian knapweed) are located 1 mile or less 

outside San Pedro Parks Wilderness.

While there are limited inventoried weed infestations within or just outside the wilderness areas, 

there is a high potential for further weed expansion into and within wildernesses due to the 

existence of numerous weed infestations along roads and trails that provide wilderness access.

Motorized and mechanized weed treatments are not allowed within wilderness. Forest Service 

Manual (FSM) 2323.26b allows control treatments of weeds by digging or with herbicides when 

they threaten lands outside wilderness or when they are spreading within wilderness, provided 

that it is possible to effect control without causing serious adverse impacts on wilderness values. 

Regional forester review and approval is required for any herbicide use in wilderness.

Environmental Consequences

Alternative A (No Action)

Weeds would continue to spread at rates from 5 to 30 percent per year. By out-competing and 

gradually reducing the abundance and diversity of native plants on the Forests, the spread of 

weeds would result in deteriorating the natural condition of recreational values for some people, 

within and outside wilderness. Weeds would reduce the variety and amount of native flora to 

observe, study, or photograph. Wildlife viewing and hunting opportunities would be reduced in 

the long term as weeds reduce the quality of forage and cover habitat for some wildlife species 

(refer to “Wildlife Resources” section).

Weeds such as spotted knapweed, Scotch thistle, and yellow starthistle would tend to diminish the 

desirability of using recreation sites because the stiff plant stalks, thorns, or sharp bristles can 

discourage or prevent walking, sitting, or setting up a camp. Recreational experiences and values 

would especially decline where tall, dense weeds such as saltcedar dominate and limit access to 

riparian areas. Recreational experiences for some people would be diminished by weed species

that create allergies or skin reactions.

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On the other hand, this alternative avoids any potential short-term, negative effects of weed 

treatments on recreational experiences, such as short-term increases in noise or traffic, and 

temporary closures of some recreation sites, trails or roads during and/or immediately after 

treatment activities.

Alternative B (Proposed Action)

Under Alternative B, weed treatments would decrease establishment and expansion of aggressive 

weed species and reduce weed related impacts that were described for Alternative A (No Action). 

In the long term, the currently diverse, noninfested plant communities within and outside 

wilderness areas would be protected by the proposed weed treatments, which would enhance 

wilderness and recreational experiences.

Herbicide applications and other treatments may cause temporary visual disturbances to some 

people who encounter weed treatment personnel, however, on most sites treatments would only 

last a few days or less. Temporary closure of roads, trails or recreation sites during and 

immediately after herbicide applications would have a minimal impact on recreational 

opportunities because they would not typically last more than a day or two, and would occur 

during the weekdays. Odors emitted by herbicides could cause anxiety in persons unaware of 

their presence, although it is unlikely that herbicides would be applied along trails or in recreation 

sites during a time when visitors are present. Signs would be posted at access points to recreation 

sites, roads or trails where herbicides would be used. (Refer to “Human Health and Safety” 

section regarding effects of herbicides on human health).

Areas of wilting, dying or dead weeds, and weeds removed, cut or burned, would be apparent for 

a short time in the localized treatment sites. Within a growing season or two, early-seral 

vegetation would fill in and become more noticeable than the dead plants or bare soil areas.

Impacts on recreation, both within and outside wilderness, resulting from implementation of the 

action alternatives would include short-term encounters with weed treatment crews and visual 

impacts from wilting plants. There would be an insignificant increase in the amount of noise and 

traffic associated with these treatment activities, primarily due to the short timeframe needed to 

treat weeds at most weed infestation sites, and the relatively small number of personnel needed to 

implement treatments. Proposed treatments typically do not require large crews of workers such 

as those frequently used on the Forests for thinning, prescribed burning, watershed restoration 

and other common projects. For some people, the sight of agency personnel spraying herbicides 

within a wilderness may diminish the quality of their wilderness experience. For others, 

wilderness values would be enhanced by the elimination of nonnative plants in or near wilderness 

areas.

Alternative C (No Herbicide)

Aggressive nonherbicidal treatments could, over time, reduce existing populations of some weed 

species and prevent establishment of new populations if detected early. However, this type of 

program would require a larger, more highly organized labor force, working throughout spring, 

summer, and fall months. Due to the need for additional repeat treatments, and in some cases 

nearly continuous or annual repeat treatments to contain or control weeds without herbicides, 

there would be a substantial increase in the amount of noise and traffic on the Forests.

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This alternative avoids having to temporarily close some roads, trails or recreation sites because 

herbicides would not be used, although the difference in impacts to recreational opportunities 

would be small due to the short closure times expected under Alternative B.

Nonherbicidal treatments are ineffective or very difficult on some species because they have very 

limited times when they can be manually treated (e.g. black henbane must be hand pulled within 

10 days of emergence) or they are aggressive root sprouters (such as Canada thistle) that are 

actually promoted by incomplete hand treatments. Subsequently, weed populations which are 

largely unaffected by these treatment methods would continue to expand. Populations of weeds 

which are located in remote, difficult to monitor sites would also be more likely to expand. In the 

long term, this alternative would not be effective and would contribute to the negative impacts to 

recreation experiences as described for Alternative A.

Other effects would be the same as those described for Alternative B.

Alternative D (Herbicide Only)

Effects under Alternative D would be most similar to effects under Alternative B. A slight 

difference in effects would involve the fact that ground-disturbing activities such as mowing, 

tilling, digging, or burning, which most often need to be repeated in order to meet objectives, 

would not be implemented. Thus, this alternative would result in less noise and traffic compared 

with the other two alternatives, which would improve the quality of the recreational experience 

for some people.

Cumulative Effects

The analysis area for cumulative effects on recreation/wilderness is the area in and immediately 

adjacent to the two forests. This boundary represents the areas where the actions proposed in this 

project are most likely to interact with other activities, in particular the weed treatments and 

ground disturbance on both forests and other lands (private, State, BLM, etc.).

The main past, present and foreseeable future activities affecting this same area that could 

cumulatively impact recreation opportunities or experiences are listed in a table at the beginning 

of this chapter. All forest management activities, particularly for large vegetation management 

projects, would continue to add to the noise and traffic levels in the forest environment. 

Motorized recreational activities such as use of off-road vehicles, snowmobiles and similar 

equipment would add to the noise in the environment. Motorized and nonmotorized recreational 

activities would continue to noticeably increase over the next 10 years. Spraying pine trees to 

prevent further spread of bark beetles is also occurring across all jurisdictions and on private 

lands in northern New Mexico. This would have some similar effects as spraying herbicides in 

terms of very temporary closures of certain recreation sites where and when spraying occurs, 

potential for odors, and the visual effect of people spraying chemicals onto plants.

Other agencies and landowners within and adjacent to the Forests would continue to treat weeds, 

primarily using herbicides, which would add to both the positive and negative effects described 

for the weed control alternatives. The most noticeable effect would be the long-term preservation 

of biologically diverse native plant communities outside and within wilderness. This cumulative 

and long-term effect would particularly enhance the natural integrity of and recreational 

experience in wilderness and back-country roadless areas. The beneficial cumulative effect, when 

combined with weed treatments on other land ownerships, would be much greater for Alternatives 

158 Final Environmental Impact Statement – Invasive Plant Control Project
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B and D than for Alternative C, because Alternative C would not be as effective in meeting weed 

treatment objectives.

Under Alternative A (No Action), other agencies and landowners who are investing in weed 

control efforts would probably become frustrated with the Forest Service for not participating in 

the collective effort that is needed to control the aggressive spread of weeds across all 

neighboring jurisdictions. Although biological control insects released on neighboring lands 

would likely have a beneficial effect in controlling the same weed species on the Forests, they 

would not be as effective if the Forest Service does not participate as a cooperating partner in 

biological weed control projects.

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Visual Resources

Affected Environment

The Forests contain a complex variety of landscapes, ranging from high alpine meadows and 

rugged peaks, forested mountains of spruce, fir, and pine, rolling grasslands dotted with piñon 

and juniper, to red rock formations, narrow canyons and tumbling mountain streams. People often 

derive pleasure and enjoyment from observing the intermingled patterns of old growth vegetation 

and landscape accents such as aspen, oak, grassland meadows, and geologic features. The 

presence of water is distinctive wherever it occurs, and people tend to congregate around streams 

and lakes.

Visual Quality Objectives (VQOs) were identified in the Forests’ plans, which categorize lands 

according to scenic quality and viewer sensitivity. The VQOs are: Preservation, Retention, Partial 

Retention, Modification, and Maximum Modification. On the Forests, Preservation is the VQO in 

wilderness areas, and Retention is the VQO in areas such as roadless areas managed for semiprimitive recreation opportunities, portions of wild and scenic river corridors, along scenic byways and in other sensitive viewsheds. See “The Visual Management System” (USDA FS 1984) 

for definitions and descriptions of the VQOs, and the Carson and Santa Fe Forest Plans (USDA 

FS 1986b and 1987b) for how VQOs were applied in each management area of the two forests.

There are four key visual elements used in describing landscapes with the visual management 

system—form, line, color and texture. They each exert differing degrees of visual influence, 

power or dominance.

• Form: Landscape forms are determined by topography and vegetative pattern.

• Line: Line is anything that is arranged in a row or sequence. It can be the silhouette of a

form, the edge of a meadow, a ridgeline, a tree trunk, a river, the path of an avalanche.

• Color: Color enables us to distinguish among objects of identical form, line and texture.

• Texture: Textures in the landscape are determined by geology, soils, topography and 

vegetation.

Weed infestations on the Forests are relatively small and visually indiscernible beyond the 

foreground views (up to one-half mile) or possibly middle ground views (up to 5 miles) and, 

therefore, do not dominate the viewpoint or viewshed. Weed infestations normally conform to 

texture, line, and color of surrounding vegetation throughout the seasons.

Environmental Consequences

Alternative A (No Action)

Under the No Action Alternative, weeds would spread unchecked, eventually infesting all suitable 

habitats within and outside the Forests, including sites that are presently weed free. Weeds would 

out-compete native vegetation and often form monocultures. The appearance of large 

monocultures of the same weeds and associated decline in the richness or diversity within native 

plant communities would have a long-term negative impact on visual quality.

Weeds primarily affect the foreground views rather than middle ground and background views, 

having both positive and negative effects. Weeds may appear to be out of scale, visually out of 

place, and often associated with land disturbance activities. To those unaware they are looking at 

160 Final Environmental Impact Statement – Invasive Plant Control Project
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weeds, the yellow toadflax, flowering musk thistle or lacy saltcedar may appear as attractive 

components of the landscape, whereas other weeds, such as Russian knapweed, may detract from 

the natural beauty of the landscape for some people. Landscapes where positive or negative 

effects of weeds would be seen by the most viewers tend to be along river corridors (which are 

often also highway or road corridors), lakes, main trails, dispersed recreation sites, and key 

destination points.

Alternatives B, C, and D

For all action alternatives, the visual impacts resulting from mowing, hand digging, and hand 

pulling would be a slight change in the form, color and texture in the foreground view because 

these methods not only kill or remove the weed plants, but also result in minor amounts of 

localized soil disturbance. If root plowing is used there would be more noticeable soil 

disturbance. Biological methods would not be visually noticeable in the foreground other than 

dead or dying weed plants. Use of prescribed fire would cause the burned vegetation to appear 

brown or blackened for a short period of time, and may result in patches of bare soil until the site 

is revegetated, similar to the visual effect of a naturally-caused surface fire. Herbicide use under 

Alternatives B or D would cause short-term visual impacts when treated vegetation turns brown, 

and there would be some patches of newly exposed soil until the site is revegetated. Selective 

herbicides such as picloram and 2,4-D would kill or burn broadleaf plants, leaving grasses 

unaffected. Overall, there would be a very short-term reduction in visual quality for some people 

associated with patches of dying, wilting, or dead weeds or exposed bare soil. The extent and 

duration of this effect would be minor, especially due to the small weed treatment sites and 

estimation that only 600 to 1,600 acres would be treated each year of the 3 million acres on the 

Forests.

Nontarget native plants would remain mostly unaffected by the ground-based herbicide 

applications proposed, assuming all EPA label limitations are adhered to. Visual effects would not 

be noticeable in the middle ground and background views such as from high elevation viewpoints 

overlooking forest landscapes. Overall, the weed control treatment sites are fairly small and 

localized, and would not alter overstory tree cover, thus there would be minimal changes in form, 

line, color or texture in the environment. In the long term, revegetation with more diverse native 

plant populations would enhance visual quality for most forest visitors.

All alternatives would be consistent with the VQOs assigned to specific areas throughout each 

forest, as well as other Forest Plan management direction for maintaining and enhancing visual 

resource values. Even weed control treatments applied in designated wilderness would be 

expected to conform to the VQO of Preservation, as treatments would not substantially alter the 

form, line, color or texture of the landscape, or create a stark contrast with the surrounding 

vegetation, and would enhance the diversity and growth of native plant communities.

Cumulative Effects

Other past, present and reasonable foreseeable activities that affect visual resources on the Forests 

were considered. They include public land use activities as well as resource management 

activities such as thinning and prescribed burning, and are listed at the beginning of this chapter.

The majority of vegetation management treatments that would alter the appearance of the 

landscape—such as thinning, prescribed burning other ecosystem restoration projects—typically 

enhance the visual diversity and quality of forested landscapes in the long run. Visual conditions 

Final Environmental Impact Statement – Invasive Plant Control Project 161
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are also being noticeably improved by current and future trends in recreation management. Most 

recreation projects are aimed at reducing soil, vegetative and watershed impacts caused by 

frequent camping and other recreational activities outside developed sites, along with off-road 

driving and off-trail hiking which create numerous new road and trail networks.

Past construction of forest roads added to many user-created, two-track roads, which together 

have negatively altered many viewsheds, as has the continued construction of homes and human 

developments on private lands within and surrounding the Forests. However, the current and 

future trend is toward closing and obliterating roads, which would continue to improve visual 

quality. The minor visual effects of this project would not noticeably add to the visual effects of 

these other activities that create more apparent changes in the natural landscape.

Current and future weed control treatments conducted by other government agencies and 

landowners in and around the Forests would cumulatively add to the beneficial visual effects of 

this weed treatment project. There would be a cumulative reduction in total acres infested with 

weeds and an increase in more diverse, native plant communities.

Alternative A, No Action, would cumulatively add to undesirable visual effects from other 

activities, due to the continued and exponential increase in the spread of weeds over time and the 

associated increases in soil erosion and degradation of water quality and wildlife habitat.

Cumulative impacts on visual resources resulting from implementation of the action alternatives 

would be an overall reduction in acres infested with weeds and an increase in native plant 

communities, which would have a positive impact on visual resources.

162 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

Livestock Grazing 

Affected Environment

Domestic livestock grazing on the Forests has not been found to be a major contributor to the 

spread of weeds within affected range allotments. The overall trends indicate that human activity 

along roads, trails, and recreation areas, along with disturbance at oil and gas well pads and the 

movement of seed or other vegetative propagules by water along riparian corridors, are the main 

transportation vectors at this time. However, this human activity can include the hauling of 

livestock on trailers which could contribute to the spread of weeds if the vehicle comes from an 

infested area or drives through an infested area. Livestock permittees are not allowed to feed hay 

to their livestock on National Forest System lands, which could be a potential source of new 

infestations if it was allowed.

The Carson National Forest administers 76 grazing allotments, of which 72 are active, 3 are 

vacant, and 1 is closed to permitted livestock grazing. There currently are weed populations 

mapped on 51 of these including on 1 of the vacant allotments and the closed allotment.

The Santa Fe National Forest administers 81 grazing allotments, of which 75 are active, 1 is 

vacant, and 5 are closed to permitted livestock grazing. There currently are weed populations 

mapped on 39 of these, including on the vacant allotment and 2 of the closed allotments. See 

Tables 46 and 47 below.

Table 46. Grazing Allotments with Known Weed Infestations on the Carson National Forest

Allotment Name Invasive Weed Species

Total 

Acres 

Infested1

Arroyo Hondo Bull thistle, Canada thistle 2.03

Bancos Musk thistle, Scotch thistle 0.12

Black Copper Bull thistle, Canada thistle 2.20

Bobcat Bull thistle, Canada thistle 2.66

Capulin Musk thistle 0.08

Cebolla Canada thistle 0.08

Deer Creek Complex Bull thistle, Canada thistle 1.13

English Musk thistle 0.08

Flechado Musk thistle 0.23

Goose Creek (closed) Bull thistle, Canada thistle 2.45

La Lama Bull thistle, Canada thistle 8.66

Lakefork Baldy Bull thistle, Canada thistle 28.16

Main Fork (vacant) Bull thistle, Canada thistle 2.07

Red River Bull thistle, Canada thistle 0.10

Rio Chiquito Musk thistle 5.97

Rio Pueblo Canada thistle 1.99

Rito Segundo Bull thistle, Canada thistle 5.29

San Antonio Mountain Black henbane 0.23

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Allotment Name Invasive Weed Species

Total 

Acres 

Infested1

San Cristobal Bull thistle, Canada thistle 10.40

Santa Barbara Canada thistle 97.65

Sublette Canada thistle 0.08

Apache Musk thistle, Canada thistle 0.05

Canjilon Musk thistle, Canada thistle 0.54

Columbine Bull thistle, Canada thistle, yellow toadflax 1.57

El Rito Lobato West Musk thistle, bull thistle 0.31

Jarita Mesa Musk thistle, leafy spurge 25.75

Jawbone Musk thistle, Canada thistle 0.54

Mesa Musk thistle, Canada thistle 0.54

Midnight Mallette Bull thistle, Canada thistle, 65.91

Miranda Musk thistle, Canada thistle 26.22

Mogote Musk thistle, Canada thistle 0.84

Mogotito Musk thistle, Canada thistle 0.15

Servilleta Russian knapweed, hoary cress 2.00

TCLP Russian knapweed, hoary cress 8.78

Cabresto Musk thistle, Scotch thistle, saltcedar 62.77

Carson Mojino Russian knapweed, hoary cress, musk thistle 10.75

E. Pinon Russian knapweed, field bindweed, yellow toadflax 0.56

Santos Russian knapweed, hoary cress, musk thistle 4.98

Vaqueros Musk thistle, field bindweed, saltcedar 7.43

Carracas Russian knapweed, musk thistle, Scotch thistle, bull thistle 15.14

Olla Ranchos Hoary cress, bull thistle, musk thistle, Scotch thistle 168.10

San Antone Hoary cress, musk thistle, Canada thistle, bull thistle 1.32

Tusas Hoary cress, Canada thistle, bull thistle, yellow toadflax 91.25

Spring Creek Russian knapweed, hoary cress, Canada thistle, leafy 

spurge, yellow toadflax 54.16

Tio Grande Hoary cress, musk thistle, black henbane, perennial 

pepperweed 0.77

Valle Vidal Musk thistle, yellow starthistle, Canada thistle, bull thistle, 

black henbane 1,805.23

Laguna Seca Russian knapweed, musk thistle, Scotch thistle, Canada 

thistle, field bindweed, saltcedar 36.47

Tio Gordito Russian knapweed, hoary cress, musk thistle, Canada 

thistle, leafy spurge, yellow toadflax 26.85

Valencia Russian knapweed, musk thistle, Scotch thistle, Canada 

thistle, field bindweed, saltcedar 41.06

1 Use of acreage figures carried out to the 1/100th acre does not reflect the precision of acreage estimates and is only 

used because many infestations are less than an acre or two in size.

164 Final Environmental Impact Statement – Invasive Plant Control Project
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Table 47. Grazing Allotments with Known Weed Infestations on the Santa Fe National 

Forest

Allotment Name Invasive Weed Species

Total 

Acres 

Infested

Barbero Bull thistle, Scotch thistle 432.2

Capulin Bull thistle 230.1

Cebolla San Antonio Russian knapweed 15.25

Chama Canyon Spotted knapweed, saltcedar 13.37

Chiquito Musk thistle, Canada thistle 4.71

Coyote Canada thistle, musk thistle 298.65

Cuba Mesa Musk thistle, Canada thistle 5.41

Erosion Saltcedar, Siberian elm 107.82

French Mesa Canada thistle, musk thistle 107.5

Gallina River Musk thistle, Canada thistle 293.21

Jarosa Musk thistle, Canada thistle, bull thistle 81.92

La Jara Russian knapweed, musk thistle 30.35

La Presa Canada thistle, musk thistle 110.57

Llaves Spotted knapweed, diffuse knapweed, Canada thistle, bull 

thistle 38.75

Los Indios Canada thistle, musk thistle 76.2

Macho Bull thistle, Scotch thistle 90.71

Mesa Alta Canada thistle, musk thistle 186.35

Mesa Del Medio Canada thistle, musk thistle 168.19

Mesa Poleo Canada thistle, musk thistle 119.07

Ojito Frio Musk thistle, Canada thistle, bull thistle, Dalmation toadflax 36.93

Oso Vallecitos Russian knapweed 0.46

Penas Negras Canada thistle, bull thistle, Dalmation toadflax, Scotch thistle 46.67

Pine Springs (closed) Musk thistle, Canada thistle, bull thistle 4.63

Pollywog Canada thistle, saltcedar 26.44

Polvadera Saltcedar, Russian knapweed 21.05

Quemado Bull thistle, Russian olive 7.52

Red Top Musk thistle, Canada thistle, Scotch thistle 8.98

Rio De La Casa Bull thistle 17.49

San Diego

Russian knapweed, hoary cress, field bindweed, musk thistle, 

bull thistle, Canada thistle, poison hemlock, Siberian elm, 

Russian olive, saltcedar

1,676.75

San Miguel Bull thistle, musk thistle 35.64

Santa Fe Watershed 

(closed) Canada thistle 3.2

Senorito Musk thistle, diffuse knapweed, bull thistle 129.4

Soldier Creek 

(vacant) Bull thistle, Scotch thistle 24.36

South Ojitos Musk thistle, Canada thistle, bull thistle 38.4

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Allotment Name Invasive Weed Species

Total 

Acres 

Infested

Springs Bull thistle 173.83

Vacas Musk thistle, Canada thistle 7.72

Youngsville Canada thistle, musk thistle 411.15

The tables show that the Valle Vidal (Carson National Forest) and San Diego (Santa Fe National 

Forest) Allotments have the largest weed infestations. This is primarily due to the extra large size 

of these allotments, and the fact that the majority of weed infestations on the Valle Vidal 

Allotment are within the 2002 Ponil Fire burn complex. Weeds tend to invade recently burned 

areas. Bull thistle is the primary species becoming established, primarily along drainages and at 

the base of burned evergreens within the high intensity burned areas (versus moderate or low 

intensity). Within the San Diego Allotment, the majority of the weed acreage consists of saltcedar

and other species along the Jemez River corridor. Permitted livestock grazing has not been 

allowed along the lower Jemez River area since 1980. Prior to that time, much of it was privately 

owned. Since then, it has been designated as a National Recreation Area and several recreation 

sites have been developed.

The Forests also administer five wild horse territories and one wild burro territory. Three of the 

wild horse territories are occupied and two are not occupied by wild horses. The wild burro 

territory is not occupied by wild burros. There currently are weed populations mapped on two of 

the occupied territories (see Table 48 below). As mentioned previously, certain weed species, 

such as Russian knapweed and yellow starthistle, are known to be toxic to horses, which could be 

a concern if they were to become widespread within a territory. The population of Russian 

knapweed mapped within the Jicarilla Wild Horse Territory is currently less than 1 acre in size.

Table 48. Occupied Wild Horse Territories with Known Weed Infestations on the Forests

Wild Horse Territory Name Invasive Weed Species Total Acres 

Infested

Jicarilla Wild Horse Territory Musk thistle, Scotch thistle, saltcedar, 

Russian knapweed, bull thistle

78.03

Jarita Mesa Wild Horse Territory Musk thistle, leafy spurge 25.75

Environmental Consequences

Alternative A (No Action)

Without treatment, weeds would likely continue to displace palatable native vegetation and 

reduce forage on affected grazing allotments and wild horse territories. As certain weed species 

are known to be toxic to various classes of permitted livestock, the continued spread of weeds in 

active allotments would be expected to result in some toxic impacts to livestock. Canada thistle

has the potential to concentrate nitrates and cause nitrate poisoning in ruminants. Field bindweed 

contains tropane alkaloids and may also accumulate toxic levels of nitrate. It is most likely to 

cause poisoning in animals when it becomes the predominant plant available for the animals to 

eat. Russian knapweed and yellow starthistle both produce a unique poisoning of horses that is 

166 Final Environmental Impact Statement – Invasive Plant Control Project
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generally fatal. Black henbane is a member of the nightshade family (Solanaceae) and has the 

potential to cause poisoning, but because it is unpalatable, it is rarely eaten. Poison hemlock is 

toxic to a wide variety of animals including man, birds, wildlife, cattle, sheep, goats, and horses. 

The poison can be transmitted through milk of animals that have eaten poison hemlock. Leafy 

spurge can cause excessive salivation and diarrhea in cattle. It does not appear to affect sheep and 

goats (Knight & Walter 2003).

Loss of native plant communities would continue to occur as weeds occupy and out-compete 

native grass and forb species. Once weeds begin to dominate these communities, a loss of species 

diversity, composition, and ecosystem function could occur. Weeds would continue to spread into 

areas that are not currently infested, such as recently burned areas, as witnessed in the Ponil Fire

Complex on the Valle Vidal Unit of the Carson National Forest, and areas of new disturbance, 

such as new oil and gas well pads on the Jicarilla or Cuba Ranger Districts. Once weeds become 

established, these areas would likely serve as weed seed source for other areas of the Forests.

Alternatives B and D

Alternative B, C, or D would result in long-term beneficial effects on 90 grazing allotments and 2 

wild horse territories. There would be increases in density and vigor of native and desired forage 

grasses within proposed treatment areas (See “Vegetation Resources” section for more detail). It 

would have beneficial effects on soil and water resources that are important in maintaining 

quality rangeland conditions (See “Water Resources” and “Soil Resources” sections for more 

detail). There would be a reduction in the risk of toxic effects of certain weed species, as 

previously described. The Forests are not currently at a level of infestation where weeds are 

displacing grazing opportunities except in very small, localized situations. Over the long term, 

control measures taken now would avoid more significant impacts in the future. 

The application of the herbicide 2,4-D has been shown to increase the nitrate content of plants 

and the palatability of the plants, increasing the potential for poisoning. Mitigation measures that 

defer the use of pastures treated with herbicides would avoid this impact.

Alternative C (No Herbicide)

Alternative C would result in the same type of beneficial effects as Alternatives B and D, but to a 

lesser extent. Because the effectiveness of Alternative C in eradicating or controlling weed 

establishment and spread is expected to be less than with alternatives that use herbicides, this 

alternative would not realize the same level of benefit. In the long term, weed spread could 

exceed the rate of weed control, so effects would be more similar to those described for 

Alternative A. Some weed species are not effectively controlled without herbicide methods and 

some weed infestations are too large to control without herbicides. Other weed infestations are 

too remote to consistently monitor for needed repeat treatments.

Cumulative Effects

Cumulative impacts relative to grazing resources include past, present, and future grazing and 

range management activities that occur on grazing allotments. In areas where cattle tend to 

concentrate, grazing by domestic livestock on the affected allotments would reduce native forage 

abundance and diversity, which would add to the reductions caused by the spread of weed species 

(under Alternative A). Livestock are probably a minor contributing factor in the spread of weed 

seed in the allotments, but add to other sources of weed spread by human activities, particularly 

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along roads, trails and water ways. Weed spread caused by other activities on the forest would 

cumulatively add to the risk of weed-related toxic effects to certain types of livestock.

Weed control treatments conducted by the Forest Service combined with those conducted by 

other entities would cumulatively and substantially improve vegetative conditions within the 

range allotments (see “Vegetation,” “Water,” and “Soil” resources sections for details on these 

improvements). Other rangeland improvement projects ongoing and planned in the foreseeable 

future would add to the beneficial effects to grasslands, meadows and other areas in the grazing 

allotments. Refer to the “Vegetation Resources” section for a more detailed description of effects 

to vegetation, including vegetation utilized for livestock grazing in allotments on the Forests.

168 Final Environmental Impact Statement – Invasive Plant Control Project
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Social-Economics

Affected Environment

Historic Context 

The social environment for this analysis comprises the people living in and adjacent to the Forests 

within northern New Mexico, hereafter referred to as the “study area.” Northern New Mexico can 

be described as mostly rural with large tracts of open lands and small communities that rely on 

commercial centers such as Taos, Espanola or Santa Fe to augment their lifestyles. (The affected 

social environment associated with human health and safety is described in a separate section that 

follows this socioeconomic discussion.)

People have lived on lands in the study area for over 12,000 years. The arrival of Europeans had a 

catastrophic effect on native populations, as was the case throughout the New World. During the 

colonization of the New World by Spain, the non-Indian population grew very slowly and was 

estimated to be no more than 20,000 to 25,000 by the late 18th century (Simmons 1979). 

Throughout this period, small nonintensive agriculture farms were the staple for the community 

and family. The basic goal of the village economy was for local subsistence, not for commercial 

production (Raish 1995).

There has been a long history of human use of the Forests. Prehistoric Anasazi made their homes 

on rivers and plateaus in the Sangre de Cristo Mountains from about A.D. 475 to 1100. Pueblo 

groups have farmed these lands for over 1,000 years. Spanish Land Grants were granted over 

many years until Mexico ceased to be part of the Spanish Empire. The land grant tradition 

continued with Mexico Land Grants. Former land grants include portions of both forests. The 

people influenced by forest resources live in nearby villages, rural areas, or urban areas. These 

communities are interwoven into the landscape, typically with private lands lying in the valley 

bottoms of the two mountainous forests.

Few generalizations can be made about the communities across the Southwest. They are as 

diverse as the people who live there. The ever increasing popularity of the Southwest as a highly 

desirable living location continues to increase the region’s diversity (see Table 49 for the 40-year 

trend in population growth). Within each community, there is a strong sense of independence and 

self-sufficiency. Most of the time people like to solve their own problems (Eastman and Gray 

1984, BeBuys and Harris 1990, DeBuys 1985, Horgan 1970). No matter what its size, there is no 

single viewpoint on most topics; each community has groups with varying opinions.

Demographics

The Forests cover portions of eight northern New Mexico counties: Colfax, Rio Arriba, Taos, Los 

Alamos, Santa Fe, San Miguel, Mora, and Sandoval Counties. The total populace of the study 

area is estimated to be 358,200 persons. The ethnic or racial makeup of populations in these 

counties is shown in Figure 14.

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Data from Census Bureau 2000

Figure 14. Ethnicity

Two racial groups comprise nearly equal proportions of the population of the study area, similar 

to the statewide population. No one group comprises over 50 percent of the State’s population. 

New Mexico is one of the few states where this occurs. A detailed breakdown of ethnicity by 

county is contained in the project record.

Population growth in these northern New Mexico counties are all increasing, but at different 

rates. The more urbanized areas such as Sandoval and Santa Fe Counties have experienced 

tremendous growth in the past 30 years (Sandoval averaged about 14 percent annually). Growth 

in the more rural counties has been slow to stagnant. The increase in population has resulted in 

greater demands for various recreational opportunities and other uses on the Forests. Table 49

shows the population growth in the eight affected counties through 2000, based on U.S. Census 

Bureau data.

Table 49. Population Growth of Affected Counties by Census Year

County 1970 1980 1990 2000

Colfax 12,170 13,667 12,925 14,189

Los Alamos 15,198 17,599 18,115 18,343

Mora 4,673 4,205 4,264 5,180

Rio Arriba 25,170 29,282 34,365 41,190

San Miguel 21,951 22,751 25,743 30,126

Sandoval 17,492 34,400 63,319 89,908

Santa Fe 54,774 75,519 98,928 129,292

Taos 17,516 19,456 23,118 29,979

The counties involved are not uniform in size. They vary in size from a mere 109 acres to nearly 

5,900 acres. Larger counties like Rio Arriba and San Miguel tend to have more lands included 

within the jurisdiction of the Forests. The population density within a county indicates the size of 

the county and the likelihood of urban areas. Table 50 shows the county land base in square miles 

and population per square mile of land in each of the affected counties (U.S. Census Bureau, 

2002). Los Alamos and Santa Fe, which have the highest population densities, have the largest 

urban areas.

White, 48% Hispanic, 43%

African 

American, 

Asian, Pacific 

Islander or 

Other, 2%

American 

Indian, 7%

170 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

Table 50. County Land Base and Population Density

County Land Area 

(sq. mi.) People Per Square Mile

Colfax 3,757 10.1

Los Alamos 109 167.8

Mora 1,931 2.7

Rio Arriba 5,858 7.0

San Miguel 4,717 6.4

Sandoval 3,709 24.2

Santa Fe 1,909 67.7

Taos 2,203 13.6

New Mexico State Total 121,356 15.0

County populations in and around the Forests differ widely in their income levels. Mora and Rio 

Arriba Counties have both the lowest per capita income level and the highest percentage of their 

residents living below poverty level. Los Alamos County is unique in northern New Mexico in 

terms of it’s higher than average income and education level, and primarily anglo ethnicity (82 

percent). The Los Alamos community was built and established around the Department of 

Energy’s Los Alamos National Laboratories, where most of its residents continue to work.

Figure 15 shows the per capita income and percent of the population living below the poverty 

level for each county involved. It is based on the most recent census data available (NMBRER 

2003). U

Figure 15. Per Capita Income (U.S. Census Bureau 2001) and Population 

Percentage below Poverty Level (U.S. Census Bureau 1999)

Another aspect to the demographics is where the people live or prefer to live. Within the study 

area comprising the Forests, approximately 67 percent live in urban zones and 34 percent live 

rurally. Mora County is unique in the study area since there is no defined urban zone. The other 

counties contain some areas defined as urban. Los Alamos, Sandoval and Santa Fe Counties are 

different in that less than 25 percent of their population lives in rural zones. Four counties have at 

least 50 percent of their population living rurally. Table 51 provides the breakdown between 

urban and rural populations.

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Table 51. Urban and Rural Populations

Geographic Area Total Population Percent Urban Percent Rural

Colfax County 14,189 48.5 51.5

Los Alamos County 18,343 88.5 11.5

Mora County 5,180 0 100

Rio Arriba County 41,190 43.2 56.8

Sandoval County 89,908 76.7 23.3

San Miguel County 30,126 59.4 40.6

Santa Fe County 129,292 75.4 24.6

Taos County 29,979 40.5 59.5

Study Area Totals 358,207 66.7 33.7

New Mexico 1,819,046 75.6 24.4

United States 281,421,906 79.9 20.1

Rural Forest Communities

Rural forest communities have long been known for their cultural distinctiveness, independent 

spirits and comparatively high poverty rates. The more rural counties have per capita incomes 

below the statewide average and a high percentage of persons living below poverty level (refer to 

Figure 15).

Forest resources play an important social and economic role, particularly for the rural residents of 

northern New Mexico. Rural areas contain primarily Hispanic-dominated villages and Native 

American pueblos. People from these communities utilize the Forests for livestock grazing, 

gathering essential firewood for heating and cooking, using and selling posts, poles, and other 

wood products. Studies of villages in the study area, such as Vallecitos, El Rito, La Madera, 

Canjilon, Mountainair and Coyote, support the contention that these rural communities depend 

heavily on the natural resources in the area. Subsistence uses of forest products can be critical to 

rural families, especially during difficult economic times (Emery 1999). These low-income rural 

residents also use the Forests to gather plants for arts, crafts, food, medicines and spiritual 

purposes. They hunt and fish on the Forests, and dig clay and rock materials.

Community pastures and woodlands were an integral part of the socioeconomic fabric of northern 

New Mexico during Spanish times (Emery 1999, deBuys 1985, Eastman and Gray 1987). At one 

time approximately 22 percent of the Forests were grant lands. Spanish is the main language 

spoken throughout many rural communities in the area. The Forests also contribute substantial 

employment in these communities through firefighting, timber crews, and rangeland work.

Forest products also have important cultural and traditional values. Most of these communities 

were established as Spanish or Mexican “colonies.” They developed a cultural value of land 

“stewardship” through generations of interacting with the natural resources in the area. Quite 

often it is imperative for these residents to have hands-on relationships with the forest that 

sustained them for generations, as it is part of their cultural identity. Another common thread 

woven through these communities is a sense of place. Few want to leave the area. For some, 

property has been handed down from one generation to another for centuries. Some regard the 

172 Final Environmental Impact Statement – Invasive Plant Control Project
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national forests as communal land once belonging to their ancestors (deBuys 1985). Activities 

such as gathering firewood, latillas or pinyon nuts are traditional recreational and subsistence 

activities in these communities (Eastman and Gray 1987).

In addition to using forest resources to support a subsistence rural lifestyle, many of the residents 

now commute to larger commercial centers for employment opportunities in manufacturing, 

construction, retail and government sectors. However, four of the affected counties—Colfax, 

Mora, Rio Arriba, and Taos—continue to have very high unemployment rates, averaging 20 

percent above the average unemployment rate for all states during the previous 2 years (NMDL 

2001).

Urban Forest Communities

Urban areas adjacent to forested communities have been known for their distinctiveness, 

independent spirits, and value placed on recreational opportunities on the Forests. These 

communities tend not to rely on economic opportunities found on the Forests. Los Alamos, 

Espanola, and Santa Fe County residents tend to rely on private business and government work in 

the cities for most of their income. Some use local forest products such as plant collecting to 

manufacture value-added items. Service industries also provide opportunities in the urban areas. 

The more urbanized counties are at or above the average statewide per capita income (refer to 

Figure 15).

Urban residents tend to use the Forests mostly for recreation or spiritual renewal opportunities 

(Leisure-Time Physical Activity among Adults: United States, 1997-1998, Department of Health 

and Human Services, Centers for Disease Control and Prevention, National Center for Health 

Statistics, April, 2002). However, most of these urban communities were also originally 

established as Spanish or Mexican “colonies” and many residents have established a traditional 

and cultural land “stewardship” value through many generations of interactions with the natural 

resources in the area.

As with their rural counterparts, a number of these residents enjoy having a hands-on relationship 

with the forest and share a sense of place similar to the rural residents. For some, property has 

been handed down from one generation to another for centuries. Some take advantage of the 

opportunities for gathering and selling or trading special forest products similar to the rural 

residents. However, as growth continues in Santa Fe, Taos and other urban centers, the proportion 

of residents who share these values and economic needs is declining.

Economic Efficiency

In addition to considering the socioeconomic history, demographics and rural versus urban 

community factors just described, the economic efficiency of the proposed project was also 

considered.

The economic efficiency consideration is not an exhaustive economic analysis and determination, 

but rather an estimate of economic efficiency from which alternatives may be compared. Some 

economic values are unknown, others are difficult to determine, still others depend on the 

individual gathering the data; therefore, readily available Forest Service publications and 

estimated values from the forest or district level experiences were used. It should be noted that 

the purpose and need for this project is based on ecological considerations rather than economics. 

Since the resource values and qualitative environmental factors are of primary importance for this 

Final Environmental Impact Statement – Invasive Plant Control Project 173
Chapter 3 • Affected Environment and Environmental Consequences

project, the economic efficiency analysis carries little weight relative to other considerations (per 

40 CFR 1502.23).

In addition, the environmental consequences of weed control project actions cannot be accurately 

expressed in monetary terms, and tend to lose meaning when put into an economic present-net 

value analysis. NEPA regulations make clear that an economic analysis of all impacts, values, and 

amenities associated with a project is not required, although due consideration was given to the 

key interactions between environmental, social and economic consequences. The Forest Service 

has established monetary values for several market and nonmarket outputs that were used in the 

cost/benefit and present-net-value estimates.

Economic efficiency relates to those items such as benefit-to-cost ratios (B/C), present net values 

(PNV), and other measures that can be expressed in quantitative monetary terms. Economic 

impacts are items such as sustainability, jobs, and incomes. The primary analysis tool used for 

economic efficiency was the Quicksilver program, which is readily available to the public. The 

Implan analysis tool was not used due to various limitations in its applicability to this type of 

project (see project record for details).

Table 52 presents the cost assumptions used in the economic estimates for this project.

Environmental Consequences

Alternative A (No Action)

With the No Action Alternative, weed expansion would continue and weeds would rapidly 

become more difficult to control. As weed infestations become more extensive and dominant on 

the landscape, more aggressive and higher cost methods (like aerial herbicide applications) may 

eventually need to be employed.

In the short term (approximately the next 5 to 10 years), this No Action Alternative would not 

have a measurable impact on the economy of northern New Mexico. In the long term (in 

approximately 20 or more years), weed populations would become much larger and more 

dominant components of plant communities throughout the Forests. Previous sections of this 

document described the negative long-term impacts that weeds have on rangelands, livestock, big 

game and other wildlife habitat, recreation experiences, riparian areas, water and fish habitats, 

and native plants that are traditionally collected and often used for food, medicines, arts, crafts 

and other income-producing uses. The adverse impacts to natural resources would reduce the 

social and economic values of the land. Rural, low-income residents—particularly Hispanic and 

Native American populations in the area—would primarily be affected due to the change in 

vegetation. Livestock grazing permittees and those who collect native plants would likely be the 

most impacted.

Alternatives B, C, and D

Weed treatments proposed in the action alternatives would provide little short-term economic

benefit. With the long-term control of weeds and restoration of desired plant communities, the 

local economy—particularly in rural areas—would benefit by avoiding the loss of economic 

opportunities tied to natural resource uses on the Forests. As Alternatives B and D would be more 

effective in eradicating or controlling weed infestations than Alternative C (as described in the 

“Vegetation Resources” section), those two alternatives would yield more positive social and 

economic benefits to forest-dependent communities over the long term.

174 Final Environmental Impact Statement – Invasive Plant Control Project
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The positive social and economic effects expected from this project would primarily benefit rural 

Hispanic and Native American populations who have a greater reliance on using forest and 

rangeland resources for social, cultural, economic and spiritual purposes. In consideration of 

environmental justice factors (in accordance with Executive Order 12898), there would be no 

significant adverse impacts anticipated from this project that would disproportionately fall on 

minority or low-income populations.

It is anticipated that this project would be implemented primarily by small numbers of Forest 

Service employees on a part-time basis, along with the possibility of using small crews of 

contractors or volunteers. Treatments would not be expected to provide a significant number of 

jobs to New Mexico residents or noticeable increases in indirect revenues to counties.

Table 52 gives a list of the rough estimated costs for each treatment method (details for cost 

assumptions are in the project record). These costs are neither exact nor all inclusive. They 

provide an indicator of relative treatment costs. They overestimate actual costs by multiplying the 

costs of several combinations of methods on the same treatment acreage, when often each method 

would be applied to a different acreage. Also, not every acre of a weed infestation site would be 

treated. 

The list of treatments is also not all inclusive of potential combinations or methodologies, but 

includes those most likely to be used. As implementation and monitoring progress, some of the 

methods may be shown to have limited effectiveness in eradicating or substantially controlling 

the spread of weeds, and treatment methods may need to be modified (discussed in the adaptive 

strategy discussion in Chapter 2).

Costs shown in the table assume a paid workforce for weed control efforts. Public interest has 

been expressed in reducing weeds through use of a volunteer workforce, and such an effort would 

help reduce costs on a case-by-case basis. However, a volunteer effort would require intensive 

management by the Forests and availability of a volunteer workforce would be highly variable 

from season to season. Weed control for many infestations are likely to be beyond the capabilities 

of volunteer efforts because of timing demands (treatments are applied during specific weed lifecycle stages), logistics, and long-term availability of volunteers (who may wear down if 

overused). Experience has shown that it may be difficult to get volunteers back on the regular and 

continuous basis needed to hand remove invasive plants. The effort to eliminate or control weeds 

on a given infestation could take several years (5 to 10) because of weed seeds remaining in the 

soil. Hence, volunteers would be used for some of the control efforts in certain circumstances, but 

this workforce option has not been considered as an economically influential factor. Although not 

a determining factor in the economic analysis, volunteer efforts could be used.

Additional startup costs for developing the necessary goat or sheep herds to meet project 

objectives were not factored in. Although some herds of sheep and goats currently exist in the 

project area, they are substantially reduced from historic levels. Several individuals have been 

reported to be developing herds of sheep and goats for weed control and so it is assumed that the 

resource would be available sometime during the next 10 years and beyond.

Final Environmental Impact Statement – Invasive Plant Control Project 175
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Table 52. Estimated Treatment Costs

Treatment

Cost ($) 

per Unit 

(rounded)

Cost Assumptions Used

Burning

Broadcast Burning 12/acre Crew of 1 GS-7, 1 GS-5, 2 GS-4; engine @ $100/day; total 

cost of $600/day; do 50 acres/day

Hand Torch/Spot 

Burning

22/acre Crew of 1 GS-7, 1 GS-5, 2 GS-4 @ $500/day + equipment @ 

$125/day (truck and burners); do 30 acres/day

Herbicide

Herbicide (backpacks, 

vehicle-mounted or 

other methods) 

87/acre Crew of 1 GS-7 applicator and 1 GS-5 @ $240/day; vehicle 

@ $15/day; herbicide @ $5.00/day; do 3 acres/day

Biological

Biological 100/acre 100 insects/acre @ $1/insect; do release in 1 day

Grazing

Goats, Sheep or Other 100/acre $1/head/day; 1,000 head eat 10 acres/day or 100 head/acre

Mechanical

Mowing or Tilling 37/acre Operator @ $90/day; equipment moving @ $45/day; tractormower @ $50/day; do 5 acres/day 

Mowing and Herbicide 123/acre Operator @ $90/day; equipment moving @ $45/day; tractormower @ $50/day; do 5 acres/day; + herbicide @ $87/acre

Manual

Hand Digging, 

Clipping, Girdling

240/acre Crew of 1 GS-5, 4 GS-4 @ $430/day; vehicle @ $15/day, 

tools @ $3/day; do 2 acres/day

Hand Pulling 430/acre Crew of 1 GS-5, 4 GS-4 @ $430/day; do 1 acre/day

Hand Digging, 

Clipping, Girdling and 

Herbicide

480/acre Crew of 1 GS-5, 4 GS-4 @ $430/day; vehicle @ $15/day; 

tools @ $3/day; + herbicide @ $87/day; do 1 acre/day

Hand Pulling and 

Herbicide

517/acre Crew of 1 GS-5, 4 GS-4 @ $430/day; herbicides @ $87/day; 

do 1 acre/day pulling, then 1 acre/day herbicides

Cutting (Chain saw) 800/acre 1 person cutting 1/4 acre/day (saltcedar) @ $200/day, 

includes chain saw, fuel, and transportation

Cultural

Seeding 105/acre 1 person @ $200/day; grass seed @ $10/acre; do 2 acres/day

Newspaper Mulching

and Unprinted 

Newspaper

or Printed Newspaper

445/acre

+120 tons

or +4 tons

Crew of 5 @ $430/day; vehicle @ $15/day; do 1 acre/day

+ 0.24 ton/acre @ $500/ton (no ink); 1,538,888 sheets

or 0.24 ton/acre @ $15/ton (with ink); 1,538,888 sheets

176 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 3 • Affected Environment and Environmental Consequences

Treatment

Cost ($) 

per Unit 

(rounded)

Cost Assumptions Used

Vinegar Application 

(acidic acid if > 8% 

solution) 

32/acre Same as hand torch/spot burning costs plus $10 for vinegar

(Note: use of vinegar or acetic acid as an herbicide has not 

been approved through Forest Service risk assessment and 

environmental review. This would need to occur before it 

could be applied, but the adaptive strategy permits this 

process.

Weed Barrier Fabric 4,240/acre Crew of 1 GS-5, 4 GS-4 @ $430/day; fabric and pins @ 

$4,000/acre; vehicle @ $15/day; tools @ $3/day; do 2 

acres/day

Annual Monitoring 5,100/

Forest

1 GS-9 @ $200/day; vehicle @ $15/day; data entry 1 day for 

5 in field; visit 10 sites/day; do 20 days in field/forest

Using the cost assumptions in Table 52, the Quicksilver model was used to calculate present net 

value based on costs and benefits of the treatments contained in each alternative. Only costs and 

benefits contained in published Forest Service documents that relate directly to this project were 

included. Planning or other “sunk costs” were not part of the analysis. Nonmarket values such 

detoxification and decomposition of toxic waste or potential property value changes that are not 

in Forest Service publications were not used in the Quicksilver calculations (State of the Southern 

Rockies—San Juan-Sangre de Cristo Bioregion, 1998).

Using a benefit-to-cost (B/C) ratio for ecosystem restoration projects such as this one can be very 

misleading, since ecological and other resource and social benefits for this project are not readily 

quantifiable. The B/C ratio was often used in the past for timber sale projects as an indicator to 

determine whether the project pays for itself (e.g. a timber sale with a B/C of less than one was 

considered a “below cost sale,” where costs exceed expected revenues).

Many other factors enter into economic considerations for this weed control project, such as 

anticipated funding levels, timing of the treatments, and availability of qualified agency personnel 

(versus contracting). Since a B/C ratio for this weed treatment project would not represent a good 

measure of economic efficiency, it has not been included in this discussion. Details are found in 

the project record.

Table 53 shows the Quicksilver calculation results for present net value (PNV), which was driven 

by treatment cost and benefit variables including the anticipated timing of treatments. Present net 

values give an indication of costs and benefits in the future to the present. The time period used 

for this economic analysis is 20 years.

The base cost figures in Table 53 show the estimated cost-per-acre for a treatment, without 

accounting for differences in the effectiveness of methods used or need for repeat treatments. The 

economic efficiency cost figures show a more realistic cost estimate, accounting for the expected 

repeated treatments if some methods are used instead of others. For instance, an herbicide 

treatment in an established patch of Scotch thistle would require several repeat entries until the 

seeds stored in the soil are exhausted (6 to 10 years). Treating the same patch without herbicide 

would require more visits per year to accomplish the same objective. Thus, although Alternative 

C has a lower single treatment cost than Alternative B, its costs increase substantially when the 

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effectiveness (or repeat treatment cost) is factored in. Monitoring treated sites along with existing 

and new weed infestations was included as a cost for all alternatives.

Table 53. Present Net Value and Economic Efficiency

Alt. A Alt. B Alt. C Alt. D

Present Net Value ($) -$150,613 $1,235,649 $-769,878 $44,124

Base Costs of Treatments 0 $1,215,000 $758,000 $497,000

Economic Efficiency Cost of Treatments $1,313,000 $1,585,000 $550,000

Alternative A (No Action) has a negative present net value due to the need to continue to monitor 

known and new weed infestations. The Forests would also continue to treat weeds under 

previously approved environmental documents.

Alternative B has the highest present net value because it uses the integrated treatment strategy 

that uses different methods including herbicides. That strategy provides for more rapid treatments 

of infestation sites.

Alternative C, using no herbicides, has a lower net value and higher efficiency costs because 

treatments would need to be frequently repeated on the same sites. The treatments under this 

alternative would require a much longer timeframe to achieve effective control, if “effective 

control” could be achieved at all.

Alternative D, using primarily herbicides, allows for treatments to be of shorter duration and last 

for fewer years on the same site. However, some herbicide treatments are not as effective when 

used alone, without the addition of a manual, mechanical or other method.

Cumulative Effects

The analysis area for the social-economic cumulative effects includes the eight counties described 

in the demographics section that cover portions of the Forests. All ongoing and future activities 

on the Forests affect people socially. As described in “Affected Environment,” people from both 

rural and urban areas enjoy multiple uses on the Forests.

The only real measurable social or economic effects of the weed control project are the indirect 

beneficial, long-term effects of improving vegetative/ecological composition, structure and 

function. Thus, the effects of the project would have a cumulatively beneficial effect when 

combined with many other ongoing and foreseeable future activities on the Forests, such as: 

wildlife and fish habitat improvement projects, fuel and fire risk reduction projects, and other 

ecosystem restoration projects. The positive social and economic effects described for 

Alternatives B, C or D would also be magnified when added to past, current and future weed 

treatment and prevention activities conducted by the Forests, as well as by other adjacent 

jurisdictions and landowners.

The weed control alternatives would cause some minor, short-term increases in noise and traffic, 

adding cumulatively to other sources on the Forests (as described in the “Recreation Resources” 

section). Weed control activities would also result in minor exposure risks to human health and 

safety, cumulative when added to other weed control projects expected in northern New Mexico, 

as described in the subsequent “Human Health and Safety” section). In addition, effects of the 

178 Final Environmental Impact Statement – Invasive Plant Control Project
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weed control alternatives when considered with other actions occurring in the affected counties of 

northern New Mexico, would not have a disproportionate adverse impact on minorities and lowincome populations.

Alternative A (No Action), by contributing to a long-term decline in the health and sustainability

of native plant communities, would add to the effects of any other land use activities that reduce 

the abundance or diversity of native vegetation, such as construction projects, off-road vehicle 

use, dispersed camping activities, and others.

It should be noted that the proposed Santa Fe National Forest Plan amendment (applicable to 

Alternatives B and D) modifies the standard and guideline regarding limitations on herbicide use 

under certain social-economic conditions, for this project as well as foreseeable future projects 

that involve herbicide use on the Santa Fe National Forest. Rather than limiting herbicide use to 

“when determined through an environmental analysis to be environmentally, economically and 

socially acceptable,” the amendment limits herbicide use to “when determined through an 

environmental analysis to have no long-term adverse environmental, economic or social 

impacts.” The modified language would be more clearly and consistently interpreted than the 

vague original language. The modified language would also provide for greater consistency with 

environmental analysis requirements under NEPA and other regulations and policies, which is 

appropriately based on estimated impacts rather than on the “acceptability” of a proposed action. 

No other social or economic impacts would be expected.

Final Environmental Impact Statement – Invasive Plant Control Project 179
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Human Health and Safety

Affected Environment

Approximately 10 to 15 percent of the United States population suffers from allergy symptoms 

from weed species such as knapweed. Knapweed pollen is a common and powerful allergen that 

peaks in August and produces strong allergy symptoms. Knapweed pollen has been implicated in 

causing allergic rhinitis (Gillespie and Hedstrom 1979). Allergies to airborne seeds may also 

complicate or trigger asthma that may take up to 2 years to get completely under control (Nielsen 

1999). Highly allergic individuals can have serious complications when exposed to allergens 

(weeds or pollen), including constriction of the airway and anaphylactic shock. Some species of 

weeds, such as bull thistle and knapweeds, also cause minor scrapes and irritations. Leafy spurge

contains a latex-bearing sap that irritates human skin.

Weed infestations increase the risk of wildfire and where this fire risk increases in populated 

areas, it poses an increased risk to human health and safety. An example is the major saltcedar

invasion of riparian areas throughout New Mexico and other western states. Albuquerque’s 2003 

Bosque Fire burned at a much higher than normal intensity and severity due to the amount of 

saltcedar and other weeds that dominated the riparian area.

Herbicide formulations proposed for use in this project would be limited to those registered for 

use by the U.S. Environmental Protection Agency (EPA), and analyzed through the Forest Service 

risk assessment process. They pose little to no risk of adverse health impacts when the 

appropriate herbicide formulation is applied according to label instructions. However, a small 

percentage of the population reports a hypersensitivity to a wide variety of pesticides, perfumes,

household cleaners, construction products or industrial chemicals, including the herbicides 

proposed for use by the Forests (Gibson 2000, Barrett and Gots, 1998). A 1997 New Mexico 

Behavioral Risk Factor Survey completed by the New Mexico Department of Health, Office of 

Epidemiology indicates 2 to 3 percent of those responding to the survey instrument are 

chemically sensitive with up to 16 percent of the New Mexico population possibly sensitive 

(MCS Task Force 2000). However, according to the New Mexico Health Department, even 

though 16 percent of the respondents mentioned having some kind of allergy, far fewer mentioned 

a specific ailment. In addition, the Health Department noted that any survey questionnaire with 

fewer than 50 answers is considered unreliable. For these two questionnaires, both fell well below 

the threshold (Vorhees, 1997). The general survey was repeated in following years but these 

questions were not repeated on the survey and so a trend or more reliable information cannot be 

established.

Environmental Consequences

Alternative A (No Action)

Under this alternative, weeds would continue to spread and become more dominant on the 

Forests. As weeds spread, there would be an increase in the discomfort and ill health effects to 

people who get allergies, asthma, contact dermatitis or other skin irritations from certain weed 

species.

With this alternative, ongoing weed treatments on the Forests would continue. However, this 

alternative would avoid the potential for additional herbicide exposure that could affect 

chemically sensitive individuals.

180 Final Environmental Impact Statement – Invasive Plant Control Project
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Alternatives B and D (Proposed Action and Herbicide Only)

Alternatives B and D include the use of herbicides. Appendix 3 provides a review of the 

herbicides, including their relative risks of causing harm to people. For all of the proposed 

herbicides, the risk to human health for the general population is low. Despite the limited risk of 

adverse health effects predicted—based on information included in the Forest Service risk 

assessments reviewed in Appendix 3—people who suffer from hypersensitivity to chemicals in 

the environment may inadvertently receive exposure levels that could affect their health, 

especially if they use the localized sites where an herbicide has been applied. Individuals with this 

ailment are generally aware of their sensitivities and, if given notice, could avoid herbicide 

treated areas during the time that the herbicide residue remains at levels that might affect them. 

Some herbicides would only remain detectable in the environment for a few days while others 

remain active and detectable in the soil for longer periods. The exposure levels for sufferers of 

this ailment are so small that it is unknown how long a time must pass before the herbicides 

proposed for use would reach those levels. Herbicide exposure to chemically sensitive individuals 

would be minimized through the public notification requirements described in Chapter 2. 

Oftentimes because of the personal variability in the reaction to treatments, notification provides 

the best means of allowing people to determine when to enter such an area. Generally, a safe reentry period passes in treated areas after the herbicide has dried on the leaf surface (NCAP 2002)

At the same time the effects of herbicide may occur at very low levels, chemically hypersensitive 

individuals may also be subject to exposure and ill health effects from oil, gasoline, diesel, or 

propane engine fuels and exhaust from motorized equipment and vehicles used for other weed 

control activities. Oil, gas, diesel and propane fuels used in equipment and vehicles for 

management and recreational activities would occur as background exposure throughout the 

Forests and in surrounding public and private lands.

The risk of adverse health effects from herbicides for the general population would be low. 

(USDA FS 1992, USDA FS 1997, SERA 1995, SERA 1996, SERA 1997, SERA 1998a, SERA 

1998b, SERA 1999a, SERA 1999b, SERA 2000, SERA 2001, SERA 2002, SERA 2003a, SERA 

2003b, SERA 2003c, SERA 2004a, SERA 2004b, SERA 2004c, SERA 2004d, SERA 2004e, 

SERA 2004f).

Potential adverse effects would be minimized by using only herbicides registered with EPA and 

reviewed by the Forest Service and documented in a risk assessment for herbicide formulations 

proposed for use. Applicators would follow label instructions. No aerial spray would occur. Other 

measures described in Chapter 2 would be followed, including the requirement to notify the 

public so they can avoid treated areas for an appropriate amount of time (this amount of time 

would be determined by an individual’s own knowledge of his/her sensitivity). Label information 

and requirements include: user safety; first aid; environmental hazards; directions for use; storage 

and disposal; general information; mixing and application methods; approved uses; weeds 

controlled; and application rates. Additional mitigation measures developed by forest resource 

specialists and described in Chapter 2 that reduce herbicide risks to wildlife, fish and other natural 

resources would also reduce the risks of exposure to humans. It is assumed from past experience 

that the label requirements and other mitigation measures would be carefully followed, and that 

overall the mitigation measures would exceed the minimum requirements on product labels.

The general public may be secondarily exposed to a spill or release should it reach surface or 

ground water. Risk assessments for each herbicide formulation proposed for use indicate that 

even under such scenarios (drinking water contaminated with spilled herbicide), the level of 

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Chapter 3 • Affected Environment and Environmental Consequences

concern would not be exceeded for most of the herbicides. These scenarios represent a 

conservative estimate of risk because although plausible, they are not likely to occur in the project 

as it is proposed. The risk of an herbicide spill or accident would be greatest under Alternative D, 

which exclusively uses herbicides to treat weed infestations. The indirect effects of a spill in the 

form of public exposure and disruption would be commensurate with the proximity of the spill 

area to the public and public exposure pathways. The risk of exposure from this means is low due 

to mitigation measures that limit exposure of the herbicides to water and avoid accidental spills or 

leaks (refer to Chapter 2).

Workers applying herbicides, especially with backpack sprayers, have a greater potential for 

exposure to herbicides. They have less potential exposure when using vehicle-mounted spray 

equipment. Handling and mixing the herbicides or working in close proximity to the spray nozzle 

would result in a greater exposure and health risk to the worker. However, worker exposure to 

adverse effects would be limited as chemically-sensitive individuals would self-select out of the 

workforce that makes up herbicide spray crews. As noted in the risk assessments, human health 

risks associated with the herbicide application are generally low, although not without any risk. 

Risk assessments note that precautions need to be taken to avoid contact with eyes, skin, and that 

certain sensitive member of the populations (such as pregnant women) should avoid working as 

applicators to create an extra measure of safety. These precautions are discussed at length in the 

risk assessments.

A summary of the scientific information available from the risk assessments regarding human 

health risks from exposure to herbicides is contained in Appendix 3. Risk assessments indicate 

that there is no route of exposure or exposure scenario suggesting that the general public would 

be at risk from longer-term exposure to herbicides. However, there are too many variables 

(receptor sensitivity, dose received, use of personal protection, etc.) for precise predictions of the 

health effects from herbicide exposure. Given this uncertainty, the risk of adverse health effects is 

managed by following a process of continual review of toxicological data on herbicides. The 

EPA, using very conservative assumptions, has determined a dose they believe would not result in 

an adverse health effect for herbicides proposed for this project. The Forest Service develops and 

maintains risk assessments to determine the estimated dose a worker or person of the general 

public might be exposed to under varying exposure scenarios. A comparison of EPA established 

reference dose (RfD) and the plausible exposure dose under a number of scenarios concludes that 

the estimated dose that workers or the general public may be exposed to on this project would be 

below the level of concern (below the reference dose). Absolute safety is not guaranteed by this 

process but it can provide the greatest measure of certainty known to science. 

In addition to the risk associated with herbicide use, all weed treatment methods pose a risk of 

worker injuries from accidental slips or falls on rough mountainous terrain. This risk of accidental 

injury would be lessened by taking precautions including the use of personnel accustomed to 

working in rough terrain, protective equipment, and other standard safety practices.

Workers conducting weed treatments with mechanized equipment (to mow, till, or dig) could also 

potentially be harmed by breathing gas or diesel emissions, or getting cuts, burns, allergies, and 

skin irritations. Workers may also be exposed to dust and chaff during seeding operations. 

However, those risks would be very low due to the required personal protective equipment such 

as gloves, long sleeved shirts, boots, and safety glasses, along with not using workers having a 

heightened sensitivity to allergens or skin irritations. Risks to the general public during 

182 Final Environmental Impact Statement – Invasive Plant Control Project
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mechanical treatments would be mitigated by avoiding treatments during high use times or 

closing campgrounds during treatment.

As the abundance of weeds is diminished over time, there would be a decrease in the discomfort 

and ill health effects to people who get allergies, asthma, contact dermatitis or other skin 

irritations from certain weed species.

Alternative C (No Herbicides)

There would be minimal health and safety risks associated with implementing this alternative, as 

described for the mechanical and other nonherbicide treatments in Alternative B, due to the 

mitigation measures to be employed.

Without the use of herbicides, weeds would likely continue to spread on the Forests and impact 

individuals affected by allergies, asthma, and minor skin irritations caused by certain weed 

species, as previously described.

Use of prescribed burning is an emphasis of Alternative C not found in Alternative B or D. The 

burning of a large number of acres in this alternative adds to the health risks associated with fire 

and smoke. These risks are managed in the context of a prescribed fire and fire suppression 

program that includes safety measures for all prescribed burns and qualifications for all personnel 

who are involved in either the prescribed burning program or wildland fire fighting. These 

requirements would apply to all personnel involved in the invasive plant control using fire. Also, 

because the burning program would be managed to maintain air quality, this additional risk posed 

by additional smoke is not expected to be measurable.

Alternative C would require more repeated entries into the same weed infestation areas to achieve 

an acceptable level of weed control. Thus, there would be a slight increase in the risks to workers 

and the public from exposure to these hazards when compared with Alternative B or D.

Cumulative Effects

The analysis area for cumulative effects on human health and safety is the area in and 

immediately adjacent to the Forests. This boundary represents the areas where the actions 

proposed in this project are most likely to interact with other activities, in particular the weed 

treatments and ground disturbance on both forests and other lands (private, State, BLM, etc).

Past, present and reasonably foreseeable activities that may have cumulative effects on human 

health include weed control efforts (aerial and ground application of herbicides) on private and 

public lands in northern New Mexico, as outlined in Appendix 3. Potential for public exposure to 

weed treatments would come from other weed treatment activities currently underway and 

planned in the foreseeable future.

Cumulatively, risks to human health from the additive effects of herbicide exposure would likely 

remain low. Alternative B or D, combined with ongoing and foreseeable applications by other 

jurisdictions, would affect less than 0.5 percent of the Forests’ 3 million acres of public lands over 

the next 10 years, and the duration of potential human contact with wetted herbicides on plant or 

soil surfaces is typically less than a day. Once the formulation is dry and/or absorbed into the 

plant, the risk is lower than that assumed in the exposure scenarios analyzed in the risk 

assessments.

Final Environmental Impact Statement – Invasive Plant Control Project 183
Chapter 3 • Affected Environment and Environmental Consequences

Application rates have been registered using a process to determine toxicity and exposure, with 

the use of the “reference dose” to account for cumulative exposure. These doses represent a very 

small amount that, when given over a lifetime (70 years), would show no effect. Risk assessments 

indicate that when considered with each treatment under Alternative B or D and added to other 

herbicide treatments ongoing or foreseeable, the likelihood is extremely low that any individual 

would be exposed to an amount of herbicide that exceeds the reference dose. Workers who apply 

the herbicide are at the greatest risk, but with use of protective clothing and equipment along with 

following label restrictions, they are not expected to exceed this dose. The risk to the general 

public is even lower, even when all the amounts are considered cumulatively.

Both Alternatives B and D are consistent with EPA, OSHA and Forest Service regulations 

regarding herbicide use. All alternatives (B, C, and D) are consistent with OSHA guidelines for 

worker safety.

Other Required Disclosures

Short-term Uses and Long-term Productivity

NEPA requires consideration of “the relationship between short-term uses of man’s environment 

and the maintenance and enhancement of long-term productivity” (40 CFR 1502.16). All 

practicable mitigation measures were incorporated into this project design to create or maintain 

favorable environmental conditions and avoid adverse impacts. The project may cause some 

people to temporarily avoid specific areas on the Forests during implementation of weed control 

treatments, particularly for individuals with a hypersensitivity to chemicals. Some wildlife 

species would temporarily avoid treatment areas due to noise and human presence. Multiple-use 

activities on the Forests, including recreational activities, collection of wood and other forest 

products, livestock grazing, forest management activities, and others would not be substantially 

altered by this project. The analysis indicates that eradicating and controlling weeds on the 

Forests would provide substantial long-term benefits to forest and rangeland vegetation, soil and 

water quality, wildlife habitat, and the sustainability of ecosystem structures and functions.

Unavoidable Adverse Effects

Minor and short-term adverse effects predicted for this project would be a reduction in nontarget 

native vegetation, exposure of bare soil, and minor increases in erosion on a portion of the 600 to 

1,600 acres per year expected to be treated. However, the requirement to ensure recovery of 

desired vegetation where needed following treatment would limit these effects to typically less 

than a year, and soil erosion rates would remain within Forest Plan standards. No significant, 

long-term adverse effects were predicted for this project, and long-term soil productivity would 

be maintained or enhanced.

Irreversible and Irretrievable Commitments of Resources

Irreversible commitments of resources are those that cannot be regained, such as the extinction of 

a species or the removal of mined ore. Irretrievable commitments are those that are lost for a 

period of time such as the temporary loss of timber productivity in forested areas that are kept 

clear for use as a power line right-of-way or road. No irreversible and irretrievable commitments 

of resources have been identified through the analysis.

184 Final Environmental Impact Statement – Invasive Plant Control Project
Chapter 4 • List of Preparers 

and Document Distribution

List of Preparers

From 1999-2002, the Forest Service worked with a team of contractors to develop a preliminary 

draft of the EIS. Those contractors were: Bill Hevron (project manager/botanist), Mike Tremble 

(biologist), Phillips Banks (weed specialist), Roy Carson (forester), and Kenneth Brown 

(archeologist). From 2003-2004, an expanded IDT from the Forest Service along with additional

contractors conducted and completed the environmental analysis documented in this EIS. The 

table that follows lists the key individuals responsible for this EIS.

Table 54. List of Preparers 

Name Position Contribution Education and Experience

Lucy Aragon Natural Resources 

Planner, Carson 

National Forest

Livestock Grazing, 

Recreation and 

Wilderness

BS Range and Forest 

Management

13 years experience

Blaze Baker Botanist, USFST.E.A.M.S.Vegetation and 

Special Status Plants

BS Botany

12 years experience

Gretchen 

Barkmann

Air Quality Specialist, 

National Forests of 

New Mexico

Air Quality BA Biology; MS Environ. 

Engineering

15 years experience

Michael J. Bremer Forest Archeologist, 

Santa Fe National 

Forest

Heritage Resources BA Anthropology; MA 

Anthropology

28 years experience

Susan Bruin Forest Planner, Santa 

Fe National Forest

NEPA Compliance 

and Editing

BS Natural Resource Mgt.

MS Res. Policy and Law

18 years experience

Jack Carpenter Natural Resources 

Planner, Carson 

National Forest

Social-Economic, 

Health and Safety

BS Forestry

30 years experience

Daniel Erskine Senior Geochemist, 

Maxim Technologies, 

Inc.

Soil and Herbicide 

Delivery Calculations

BS Geology; MS Geol. and 

Geochemistry PhD Earth Sci. 

and Geochem.

16 years experience

David Highness GIS Programmer and 

Analyst; Maxim 

Technologies, Inc. 

Geographic Info. 

Systems Analysis and 

Maps

BS Anthropology; MA 

Geography

10 years experience

Sandy Hurlocker Natural Resources 

Planner, Santa Fe 

National Forest

Project Leader, 

NEPA Compliance, 

Writer/Editor

BS Science Education 

MS Journalism 

20 years experience

Barry Imler Forest Range Program 

Mgr., Santa Fe National 

Forest

Vegetation 

Resources, Livestock 

Grazing

BSR Renewable Natural 

Resources; MS Watershed 

Management 

13 years experience

David M. Johnson Forest Archeologist, 

Carson National Forest

Heritage Resources BA Anthropology; MA 

Anthropology 

29 years experience

Lee Johnson Forest Wildlife/Fish 

Biologist, Santa Fe 

National Forest

Wildlife Resources BS Fisheries

23 years experience

Final Environmental Impact Statement – Invasive Plant Control Project 185
Chapter 4 • List of Preparers and Document Distribution

Name Position Contribution Education and Experience

Greg Lind Natural Resources 

Planner, USFST.E.A.M.S.

Writer-Editor BS Botany 

20 years experience 

Alfred Medina GIS Specialist, 

Espanola Ranger 

District, Santa Fe 

National Forest

Geographic Info. 

Systems Analysis and 

Maps

BS Mgt. Info. Systems

12 years experience

Greg Miller Soil Scientist, Carson 

National Forest

Soil and Water 

Resources

BS Agriculture/Soils

20 years experience

Patrick Mullen Natural Resource 

Specialist; Maxim 

Technologies Inc., 

Fish and Aquatic 

Resources

BS Biology; MA 

Zoology/Wildlife Biology

16 years

Mary Orr Acting Forest Biologist, 

Santa Fe National 

Forest

Biological 

Assessment and 

Evaluation

BS Wildlife Biology 

24 years experience

Melissa Powell Forest Archeologist, 

Santa Fe National 

Forest

Heritage Resources Ph.D Archeology

10 years experience

David Rogness Senior Hydrologist, 

Maxim Technologies, 

Inc.

Water Resources BS Earth Sci./Geology; MS 

Hydrology

23 years experience

Document Distribution

This section discusses the agencies, organizations and persons to whom copies of the DEIS and 

FEIS are sent, in accordance with 40 CFR §1502.19.

Copies of the DEIS were furnished to appropriate government agencies and Native American 

tribe with a jurisdictional or other interest in the proposed project, as well as any person or 

organization requesting a copy of the DEIS. A Notice of Availability was published in the Federal 

Register as well as in the Albuquerque Journal in July 2004. A list of those who actually received 

a copy of the DEIS is found in the project record.

In May of 2004, a postcard was sent to over 300 potentially affected or interested parties on the 

project’s mailing list notifying them of the upcoming availability of the DEIS and DEIS Summary 

on the Internet or by mail as a paper copy (upon request). The mailing list for those who request a 

paper copy of the entire DEIS or DEIS Summary will be available for public review in the project 

record. Notice of the inclusion of an amendment to the Santa Fe Forest Plan was also included in 

the May 2004 notice and the cover letters for the DEIS.

As a minimum, copies of the entire DEIS were sent to agencies such as the U.S. Fish and Wildlife 

Service, U.S. Environmental Protection Agency, Bureau of Land Management, Bureau of Indian 

Affairs, National Park Service, New Mexico Game and Fish Department, New Mexico 

Environment Department, New Mexico Department of Agriculture, New Mexico State Historic 

Preservation Office, County Extension offices, and several others.

A similar agency distribution will be made for the FEIS, using electronic posting as much as 

possible. Those who commented on the DEIS will have the opportunity to receive the FEIS. 

186 Final Environmental Impact Statement – Invasive Plant Control Project
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Final Environmental Impact Statement – Invasive Plant Control Project 199

Appendix 1 • Past, Present 

and Future Weed Control Activities

Previous weed treatments on the two forests consisted of:

• Manual control (hand digging rosettes and clipping seed heads) of thistles (musk, Scotch, 

and bull) on the Jicarilla, Questa, and Camino Real Ranger Districts, Carson National 

Forest, and on the Espanola, Jemez, and Cuba Ranger Districts, Santa Fe National Forest. 

Ongoing, as labor has been available. (Totaled 88 acres for FY2003, Santa Fe National 

Forest and 150 acres for FY2003, Carson National Forest).

• Herbicide treatment of saltcedar on the Jemez Ranger District, Santa Fe National Forest. 

Started 1999, ongoing through 2002. (Equipment failure caused no acres to be treated on 

this project in FY2003).

• Goat grazing of yellow toadflax, Russian knapweed, and hoary cress on highway rightof-way south of Tres Piedras. One time treatment, 2002.

• Mowing of U.S. Highways 64 and 285 by NMSH&TD. Ongoing for visibility. When the 

mowing occurs prior to seed heads maturing, it assists in limiting the spread of the weed 

populations. When this is done at the “incorrect” time (seed heads already mature), it has 

the potential to exacerbate the weed problem by spreading the weed seeds to noninfested 

sites.

Reasonably foreseeable activities within the cumulative effects area include weed control projects 

proposed by private landowners, county, State and other Federal agencies:

• Cooperative Weed Management Areas (CWMAs): The New Mexico Department of 

Agriculture (NMDA) lists 12 CWMAs within the state of New Mexico. The following 

three are located in the northern portion of New Mexico, in the vicinity of the Forests: 

Colfax County Weed Management Area, San Juan County Weed Management Area, and 

Sandoval County Weed Management Area.

• Colfax County: There have been biological controls released on spotted knapweed and 

leafy spurge within Colfax County. These have also been treated with herbicide. Angel 

Fire also has a population of leafy spurge on which they have released biological control. 

There is spotted knapweed in Cimarron Canyon that had a biological control released on 

it. The Carson National Forest is a signer of the MOU for the Colfax County Weed 

Management Area.

• Colfax County: Their biggest concerns to date are musk thistle, leafy spurge, spotted 

knapweed and hoary cress. Water and roads are the primary transportation modes of the 

weeds. Money is a constraint and they are applying for a Pulling Together Grant this fall. 

The hoary cress has not been mapped, due to a lack of mapping labor in the spring, but 

has been noted as an increasing problem.

• San Juan County: During the past 3 years they have been conducting mapping on 3 

million acres. They have a National Fish and Wildlife Foundation “Pulling Together”

grant ($104,000) which they have been using to cost-share with private landowners on 

treatment of weeds. They have accomplished 1,872 acres of treatment on private lands 

(76 private landowners) within the CWMA in the past 3 years. Water appears to be the 

number one mode of weed seed transportation, especially along the San Juan, Animas, 

and La Plata Rivers. Off of the rivers, the weeds are primarily within 1 mile of each side 

of the river.

Final Environmental Impact Statement – Invasive Plant Control Project 201
Appendix 1 • Past, Present and Future Weed Control Activities

• San Juan County: The BLM oil and gas permittees have established target areas for 

treatment. There are weeds all over BLM lands, primarily at well pads, roads and along 

pipelines. The permittees provide funding for a variety of restoration/mitigation, with 

weed treatments included in the list of projects funded.

• San Juan County: Russian knapweed is the weed that they have the most acres of, 

along with musk thistle, and then Canada thistle. Their biggest concern, however, is small 

“hot spots” of leafy spurge. They also have spotted knapweed in a few spots and they 

found camelthorn near Upper Fruitland, which is a concern because it has adapted itself 

to live this far north (previously thought to be out of range) (1,900 acres plus).

• Sandoval County Weed Management Area: The Cuba Soil and Water Conservation 

District (SWCD) began a weed control project in 1999. They have primarily been 

targeting hoary cress and Russian knapweed, along with Canada thistle, musk thistle, and 

bull thistle. They provide chemical and technical assistance to private landowners to treat 

the weeds and have used Redeem and Escort brand herbicides. In 2003 they assisted in 

treating 65 acres total, and in 2002 did 30 acres. The highway department also treated 3 

miles of highway right-of-way in 2002. They are very involved in education and 

awareness activities, writing articles for the local newspaper and showing pictures with 

their displays (30-65 acres per year, 3 miles of highway).

• The Taos County Noxious Weed Alternative Management Committee is a volunteer 

Noxious Weed/Invasive Plant Management Organization in the northern New Mexico 

area, based in Taos, which emphasizes nonherbicidal control of weeds. They have been 

conducting education and awareness activities, demonstration projects, and mapping of 

existing infestations. In addition, a member has been actively coordinating the timed 

mowing of highway rights-of-way to insure it is done in a way to limit seed production 

and spread of weeds. The NMSH&TD entered into an agreement with this committee in 

2001 to put the money they would have spent on herbicidal control within Taos County 

toward the committee’s nonherbicidal control efforts.

• New Mexico Association of Conservation Districts (NMACD): Coordinating the New 

Mexico Saltcedar Control Project along the Pecos and Rio Grande Rivers, including the 

northern Rio Grande area. The NM State Legislature initially appropriated $5 million for 

nonnative phreatophyte control. This project will include aerial spraying and ground 

applications along the northern Rio Grande.

• Coronado SWCD has let bids out and plans to treat 25 acres south of 540 in Bernalillo. 

They also have tentative plans to work on the Sandia Pueblo and, possibly, the Santa 

Domingo Pueblo on Galisteo River. Additional work may be pursued on Coronado State 

Park, Jackalope and Coronado Restaurant lands. This could be as much as 25 acres of 

land.

• Valencia SWCD has awarded one contract for stump treatment within its district. This is 

the first site that is on Middle Rio Grande Conservancy District (MRGCD) lands. The 

final proposal price was $ 2,672 per acre. They have recently completed 10 acres on the 

Rio Grande in Valencia County. (This project also has an education component. A local 

school works in cooperation with the UNM Bosque Ecosystem Monitoring Project 

(BEMP) to do various types of monitoring in this area.) They are monitoring vegetation, 

wildlife and elevation in the water wells. Valencia has signed up additional acreage 

located on lands owned by two pueblos for aerial application. Isleta Pueblo has 1,300 

acres signed up plus another 355 acres that the pueblo will pay for. (This would amount 

to a match of approximately $65,000-80,000.) These acres are located in the Coyote and 

202 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 1 • Past, Present and Future Weed Control Activities

Comanche drainages that flow into the Rio Puerco. Laguna Pueblo has a total of 1,830 

acres spanning approximately 70 miles with about 805 acres of wetland areas that need 

treatment. The total of the 2 pueblos is approximately 6,000 acres. Valencia is planning 

on doing demonstration tracks of about 5 to 10 acres using different kinds of mechanical 

methods including mechanized mulchers, sheers, and dozers. The district is hoping to be 

able to evaluate the efficacy of different labor saving machinery. The goal is to reduce the 

per acre cost of treating phreatophytes and removing the excess fuel loads they create.

• Ciudad SWCD is in the process of awarding bids for work. They will be treating 

approximately 100 acres within the Rio Grande Nature Center. They have best and final 

offers for 40 acres and inmate work crews will do the remaining 60 acres of the nature 

center. On the west side of the river in Rio Rancho, 22 acres will be awarded to another 

local company. This is north of Corrales, east of Highway 3. This site is within the City 

of Rio Rancho. About $6,000 worth of in-kind services including labor, legal assistance, 

and environmental planning assistance and traffic control has been received on the 

project from the city. One city councilor is highly involved with the project. Another site 

is at the National Hispanic Cultural Center. This site is only about 2 acres and will be 

done by inmate crews. However, this site will also offer some unique opportunities for 

public awareness about bosque health and management.

• Santa Fe-Pojoaque SWCD issued RFPs in February and a contract was awarded to the 

Deveg Group in March. The bid ranged from $1,894 per acre for cut and pile to $2,294 

per acre for cut and chip. They have five sites. Santa Fe Pojoaque has 2 sites done on 

Simons in the La Cienega area and the Los Golondrinas area. On La Cienega, there are 

41 acres that have been treated. There are another 12 to 15 acres waiting for treatment. 

The district has also been in communication with Pojoaque Pueblo and the Pojoaque 

Irrigation District. There are approximately 20 acres on the pueblo, and the acreage has 

not yet been estimated for the irrigation district. Two additional groups that the Santa FePojoaque SWCD is working with are the La Cienega Watershed Group and El Rancho de 

los Golondrinas. These two participants provide public education about riparian 

restoration and outdoor learning experiences, respectively.

• East Rio Arriba SWCD has landowner agreements with 23 landowners, totaling 

approximately 60 acres. There is a possibility that some will be treated aerially along the 

Ojo Caliente River. The site identified for aerial treatment is approximately 2 miles by 

100 feet wide along the riparian corridor. The landowner is working to secure neighbor’s 

support to possibly extend the project to 10 miles in length, but this will also depend on 

what the native composition is in the area; there are some areas with dense cottonwood 

and willow that would not lend themselves to an aerial application. East Rio Arriba 

SWCD will let RFPs in July and work will begin in September. They are working with 

the Abiquiu land grant watershed that directly feeds the Rio Chama.

• Northern Rio Grande Saltcedar Control Project aims to eliminate the nonnative 

phreatophyte with money appropriated by the NM State Legislature. This project will 

offer to eliminate saltcedar on voluntary cooperators’ lands (private, pueblo, and Middle 

Rio Grande Conservation District). All herbicide applications are done by licensed 

applicators. From Bernalillo north, the predominant species treated is Russian olive, with 

the exception of a stretch of saltcedar in the Galisteo basin. From Bernalillo south, the 

predominant species treated is saltcedar. In 2003, acres treated as part of this project 

were:

Final Environmental Impact Statement – Invasive Plant Control Project 203
Appendix 1 • Past, Present and Future Weed Control Activities

▪ East Rio Arriba SWCD, 93 acres with Garlon 4 

▪ Santa Fe-Pojoaque SWCD, 94 acres with Garlon 4

▪ Coronado SWCD, 20 acres w/Garlon 4 and 670 acres w/Arsenal

▪ Ciudad SWCD, 70 acres w/Garlon 4

▪ Valencia SWCD, 30 acres w/Garlon 4 and 1,044 acres w/Arsenal 

Foreseeable future treatments include using large cutter machines, which chip the woody 

above ground material, then leave the chips on the ground. Very preliminary observations 

seem to show that it inhibits weeds but allows the grasses to become established. Goats 

are also a viable option for handling the treatment of resprouts (woody species). One 

organic farmer has requested this option down near Socorro.

• Mora and San Miguel Counties: The only weed work is being done by the NM State 

Highway and Transportation Department. The railroad may be doing a little work along 

the railroad tracks. The BLM gave the Adelante RC&D funds to establish a native plant 

seed source for reclamation projects. They are trying to produce mountain muhly and 

pine drop seed, plus a couple of native forbs. He noted that there is purple starthistle in 

Mora County, which has been present since the 1950s, possibly brought in at a sheep 

camp. It has remained fairly small, but it has begun to spread in the past few years. The 

counties are currently mapping weeds.

There was one cost-share in 2003; it was for control of 10 to 20 acres of Canada thistle. 

The private landowner most likely used Roundup for this project. They used goats in 

2002 on Carabajal Rd./Fred Baca Park. The goats grazed 10 acres in 5 days. There was a 

mixture of Canada thistle, musk thistle, bull thistle, and whitetop.

• Tierra y Montes SWCD: in the planning process to treat approximately 6 acres of 

saltcedar along the Pecos River. It is a cut stump treatment (Garlon). They are working 

with private landowners on this project.

• Upper Chama SWCD: NRCS has a cost-share program. Their cooperators have been 

concentrating on big sage control (native – 1000s of acres, Jicarilla Apache Reservation, 

private landowners, with Spike) and chicory control (nonnative but not yet listed as 

noxious in NM – 40 to 60 acres over the past couple of years, Cebolla area, with 

Picloram). Hoary cress (white top) is of high concern to them; there is a lot of it on the 

Jicarilla Reservation. Of lesser concern, is Dalmation toadflax, which is coming in on 

hay, and about five species of thistles. The SWCD has equipment (backpack sprayer) that

they loan out to individuals who need it and that they participated in an outdoor 

classroom-type outreach several years ago.

• Rio Arriba County Extension Service has proposed work in El Rito for perennial 

pepperweed, hoary cress, Russian knapweed, and chickweed. Along Hwy. 285, 

Dalmation toadflax has expanded to about 10 acres in the Tusas area. Several years ago 

Sam Martinez released biological controls on leafy spurge in the Tusas area. (The leafy 

spurge infestation started with some hay on his property....) Now that population of 

biological control is an “insectary” where you can collect from it in July to release in 

other patches of leafy spurge. There is no fee, just the time it takes to collect.

• New Mexico State Highway and Transportation Department (NMSHTD): The 

NMSHTD Vegetation Management page on the department’s Web site listed the weed 

spraying schedule for the State by route number and milepost information. The schedule 

204 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 1 • Past, Present and Future Weed Control Activities

for 2003 included the following areas in the general vicinity of the two forests. Portions 

of NMSHTD Districts 3, 4, 5, and 6 are near the Forests.

▪ District 3: On Interstate 25, Roundup and Velpar were scheduled to be applied 

on 6/19-6/20/2003 from mileposts: 248-264 (Algodones to Santa Fe County 

Line).

▪ District 4: The spraying within District 4 was all very distant from the forest 

boundaries, in the eastern part of the state, south of Interstate 40.

▪ District 5: The areas near the Forests include the following, and were all 

scheduled for application during the week of July 21-25, 2003.

▪ NM 106 from the junction with 84/285 and the junction with NM 76, mileposts 

0-0.7: .7 mile Roundup and Sahara. Espanola area - spraying medians. (Near 

Espanola RD, Santa Fe National Forest.) 

▪ NM 112: from Junction 64/112 to El Vado State Park, mileposts 30.2-44.6: 

approximately 14 miles guardrails and signs of 2,4-D Amine, Garlon 3A, 

Roundup, Sahara, Tordon. (North of the Cuba RD, Santa Fe National Forest and 

between the Jicarilla and Tres Piedras RDs, Carson National Forest). 

▪ N 41: From junction of U.S. 285 to the Junction with I-40, mileposts 62.09-28.2: 

approximately 34 miles spot spraying guardrails with Roundup and Sahara. 

(South and west of the Santa Fe National Forest.)

▪ U.S. 285: From the patrol yard to junction with NM 41, mileposts 249-283: 

approximately 24 miles spot spraying guardrails with Rodeo and Sahara. (South 

and west of the Santa Fe National Forest.)

▪ U.S. 64: From Jct. 84/64 to the end of the patrol yard, mileposts 171.7-198.5:

approximately 27 miles spot spraying guardrails and shoulders with 2,3-D 

Amine, Garlon 3A, Roundup, Sahara, Tordon. (Tierra Amarilla.)

▪ U.S. 84: Junction 84/NM 96-Junction 84/U.S. 64, mileposts 218.3-255: 

approximately 37 miles spot spraying guardrails and shoulders with 2,4-D 

Amine, 3A, Roundup, Sahara, Tordon (Tierra Amarilla – Abiquiu Dam.)

▪ U.S. 84: From NM 584 to Northwest Frontage Road, mileposts 190.6-194.3: 

approximately 4 miles spraying medians with Roundup and Sahara. (Espanola 

area.)

▪ U.S. 84: From entrance to patrol yard to Junction of NM 30/84, mileposts 177.6-

189.2: spraying median and sidewalk with Roundup and Sahara. (Espanola area.)

▪ District 6: The spraying within District 6 was all very distant from the forest 

boundaries, in the western and northwestern part of the State.

• Santa Fe Watershed Association/City of Santa Fe: used a cut stump herbicide 

treatment. Aquamaster (Round Up® with nearly 50 percent glyphosate) painted directly 

onto cut Siberian elm stumps The cut stump treatment of Siberian elm along the Santa Fe 

River was done along a stretch from Galisteo Street to St. Francis Drive (less than 1 mile) 

within Santa Fe city limits. The project was done in October/November 2003, so they 

don’t have any information on the effectiveness yet. This was not a comprehensive 

treatment designed to remove all of the Siberian elm; rather, it was designed to reduce the 

elms enough to give the native species a chance to more effectively compete against the 

elm and get established. Reduce the amount of seed source, as well as the density of trees 

Final Environmental Impact Statement – Invasive Plant Control Project 205
Appendix 1 • Past, Present and Future Weed Control Activities

along the river. He noted that they had also treated a 300- to 500-foot stretch of the Santa 

Fe River just below Adam Armijo Park early this spring, again at the request of citizens 

(the Canyon Road Association and Audubon Society), using the same cut stump 

treatment with Aquamaster. He noted that they had tried a nonherbicide control using a 

backhoe and an inmate crew a few years ago along a 100-yard stretch near St. Francis. At 

the end of the project, they decided the damage to the streambank outweighed the 

benefits.

• Nature Conservancy: a weed control project on their Santa Fe Canyon Preserve in 2001. 

It was a cut stump treatment of Russian olive and Siberian elm using Garlon 4 along an 

approximate quarter- to half-mile stretch of the Santa Fe River. There may also have been 

a little saltcedar in there. This project is sandwiched in between the work the city of Santa 

Fe did on city property and the project the Audubon Society did on private land.

• Audubon Society and Canyon Road Association: Aquamaster was used in the 

treatment in the east canyon where it crosses the Santa Fe River, and on private properties 

along a 2-mile stretch of the Santa Fe River, with the goal of removing exotic Siberian 

elm and Russian olives. They are also conducting inventory and identification of wildlife 

habitat.

• Earthworks Institute: coordinating the Galisteo Watershed Project. They have done 

work in enhancing the riparian conditions (induced meandering, etc.) in the watershed in 

favor of native species. They have used some prescribed grazing with goats in the 

grasslands within the project to remove dead material and weeds, including juniper. Due 

to the drought, the results are inconclusive at this time.

• Rio Grande Restoration: working on several projects over the past several years. 

Saltcedar control in this Chama Canyon project involved a small amount of mechanical 

control. They were trying to protect a spring by removing the saltcedar sprouting there. 

Mostly they have small emergent plants which can be hand dug. They also have a site 

they are working on along the Rio Grande: The Taos-Rio Arriba County Line Site. They 

have a more aggressive saltcedar control project there. Chain saw work with followup

hand digging with cutter hoes by numerous youth groups from around the country doing 

service projects in conjunction with river trips.

• Bureau of Indian Affairs: Eight Northern Pueblos Agency has not done any herbicide 

treatments on tribal lands in the past several years. The last time they did any herbicide 

treatment was on the Taos Pueblo approximately 10 years ago on a sagebrush control 

project.

• Valles Caldera National Preserve: approved a noxious weed control and eradication 

project on September 5, 2003. This project proposes to treat three species of thistles (bull, 

Canada, and musk) along 70 miles of roads using clopyralid. The project was scheduled 

to begin September 2003, and they hope to complete it by November 2006. They 

currently only have an estimated 5 acres of these species within the VCNP.

• National Park Service: Bandelier National Monument has not done any herbicide 

treatment for weed control for about 3 to 4 years. Then it was limited to about 10 

individual stumps using Pathfinder. He noted that they have a lot of Russian olive, 

Siberian elm, and saltcedar along a 6-mile stretch of river corridor (Rio Grande) (maybe 

10 years down the road). He is seeing the worst weed problems in the Cochiti Reservoir 

area, where they just located Russian knapweed last year. He said they treated Ailanthus 

(tree of heaven) about 6 years ago, but it wasn’t successful.

206 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 1 • Past, Present and Future Weed Control Activities

• Chaco National Historical Park: the park uses a prevention and early detection strategy 

to control their weeds. Cheat grass is the species they have the most acres of. They treat 

small isolated patches of saltcedar away from the wash with a cut stump treatment using 

Tordon in the fall. They estimate having treated no more than 10 acres with this method 

over the past 2 years.

• Pecos National Historical Park has been working on controlling Scotch thistle, Siberian 

elm, Russian olive, and saltcedar on the approximately 6,600-acre park for 3 years, using 

a Garlon 4a cut stump treatment on the woody species. Since initial treatment 3 years 

ago, it has been a minimal retreatment process on resprouts. Roundup is also used on 

scotch thistle early in the growing season, usually May and June, but sometimes as early 

as April, so that a minimal amount of Roundup will control the relatively small rosettes. 

About 5-10 gallons of Roundup is needed each year.

• Bureau of Land Management: There are three field offices (FO) with BLM lands near 

the Forests: Albuquerque FO, Farmington FO, and Taos FO. The totals of acres 

inventoried for weeds for each FO and the total weed acres treated for each FO, for the 

fiscal years 2000-2003 are shown in Table 55.

Table 55. Acres Inventoried and Treated for Weeds on Nearby BLM Lands by Fiscal 

Year

Field Office FY 2000 FY 2001 FY 2002 FY 2003

Acres Inventoried (total acres surveyed)

Albuquerque FO 4,800 26,700 5,500 4,000

Taos FO 500 1,080 12 204

Farmington FO 4,000 3,500 5,500 11,400

Acres of Invasive Weeds Treated

Albuquerque FO 60 303 96 857

Taos FO 10 0 1 0

Farmington FO 250 1,400 120 17

• Farmington FO: 11,400 acres surveyed in 2003 were part of a fairly systematic survey 

of San Juan County. Some acres were done in conjunction with general work activities. 

They have more acres of Russian knapweed than any other weed, but it is so widespread 

that their primary control strategy is “containment,” to reduce additional spread from 

known infestations. Their priority species for “rapid response” include: Scotch thistle, 

leafy spurge, toadflaxes and camel thorn. They work in conjunction with the highway 

department to notify each other of new infestations they find so they can be treated 

quickly. Oil and gas leases are responsible for treating well pads and pipeline rights-ofway. Some of the offsite mitigation funds go for weed control.

▪The acres treated in 2003 were: 20 acres of Russian knapweed - 15 with Grazon P+D, 

scattered populations in eastern San Juan County (Middle Mesa and Jarosa areas); and 5 

with Redeem; 3 acres of leafy spurge with Grazon P+D in the same general area as the 

Russian knapweed; 2 acres of Scotch thistle – hand grubbed; and 15 acres of buffalo bur 

(an invasive plant from the Midwest) with Grazon P+D, 4 miles east of Aztec. These 

were done from spring to early fall in 2003. These acres don’t match the 17 acres 

reported for 2003, due to the fiscal reporting year ending September 30.

Final Environmental Impact Statement – Invasive Plant Control Project 207
Appendix 1 • Past, Present and Future Weed Control Activities

• Albuquerque FO: weed inventories were conducted in conjunction with general work, 

as well as with permit lease renewal health assessments. In conjunction with the Cuba 

SWCD (BLM funded in part), they treated 2.5 acres of hoary cress, 60 acres of Russian 

knapweed, one-half acre of Canada thistle, and 4.5 acres of musk thistle in 2003. Of these 

acres, 64.5 were done with Redeem and Escort. The remainder was hand digging. The 

same acres reported under the Cuba SWCD were done on private lands within Sandoval 

County. In addition, they treated 110 acres of musk thistle and 5 acres of halogeton with 

Roundup in 2003 on BLM lands within Sandoval County. They also treated 300 acres of 

saltcedar in the Chico Drainage with an aerial application of Arsenal and Roundup in 

2003.

• Taos FO: limited time/funds to concentrate on weeds. Treated acres for the Taos FO are: 

2001 (0 acres), 2002 (1 acre), and 2003 (0 acres). The 1 acre of treatment in 2002 

included hand digging of black henbane in their north unit, and hand digging of hoary 

cress along the Orilla Verde Recreation Area along the Rio Grande. They did not use any 

herbicidal control.

• Southwest Strategy: USFS Riparian Invasive Species Interagency Plan that numerous 

agencies in the State are working on.

Table 56. Methods of Addressing Weeds in 2003

Agency or Organization

Education 

and 

Awareness

Manual Control 

(hand pulling, 

grazing, and 

mowing) and 

Biological Control

Herbicide 

Treatment

Carson National Forest Yes 150 acres 0 acres

Santa Fe National Forest Yes 88 acres 0 acres

Colfax County Weed 

Management Area

Yes

San Juan County Weed 

Management Area

Yes 1,872 acres (over the past 

3 years)

Sandoval County Weed 

Management Area

Yes 3 acres hand digging 65 acres (Redeem and 

Escort brand herbicides)

Taos County Noxious Weed 

Alternative Management 

Committee

Yes Coordinated timed 

mowing with the 

NMSH&TD

Northern Rio Grande Saltcedar Control Project

East Rio Arriba SWCD Yes 93 acres (Garlon 4)

Santa Fe-Pojoaque SWCD Yes 94 acres (Garlon 4)

Coronado SWCD Yes 20 acres (Garlon 4)

670 acres (Arsenal)

Ciudad SWCD Yes 70 acres (Garlon 4)

Valencia SWCD Yes 30 acres (Garlon 4)

1,044 acres (Arsenal)

208 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 1 • Past, Present and Future Weed Control Activities

Agency or Organization

Education 

and 

Awareness

Manual Control 

(hand pulling, 

grazing, and 

mowing) and 

Biological Control

Herbicide 

Treatment

NM Soil & Water Conservation District in the vicinity of the Carson and SF National Forests 

(separate work from the Northern Rio Grande Saltcedar Control Project above)

Colfax SWCD Yes

Cuba SWCD Yes Coordinating Sandoval 

County WMA work 

described above

East Rio Arriba SWCD Yes

Mora-Wagon Mound SWCD Yes

Western Mora SWCD Yes

Santa Fe-Pojoaque SWCD Yes

Taos SWCD Yes 10-20 acres (probably 

Roundup)

Tierra y Montes SWCD Yes

Upper Chama SWCD Yes 1000s of acres treating 

weeds on private and 

Jicarilla Apache lands 

(Spike)

40-60 acres over past 2 

years (Picloram)

New Mexico State Highway and Transportation Department

District 3 Along 16 miles of I-25 

(broadcast-Roundup and 

Velpar)

District 5 Along .7 mile of NM 106 

(spot spraying medians 

Roundup and Sahara)

Along 14 miles of NM 

112 (2,4-D Amine, 

Garlon 3A, Roundup, 

Sahara, Tordon - spot 

spraying guard rails and 

signs)

Along 34 miles of NM 

41 (spot spraying 

guardrails - Roundup and 

Sahara)

Along 24 miles of U.S. 

285 (spot spraying 

guardrails - Rodeo and 

Sahara)

Final Environmental Impact Statement – Invasive Plant Control Project 209
Appendix 1 • Past, Present and Future Weed Control Activities

Agency or Organization

Education 

and 

Awareness

Manual Control 

(hand pulling, 

grazing, and 

mowing) and 

Biological Control

Herbicide 

Treatment

Along 27 miles of U.S. 

64 (spot spraying guard 

rails and shoulders - 2,4-

D Amine, Garlon 3A, 

Roundup, Sahara, 

Tordon)

Along 37 miles of U.S. 

84 (spot spraying 

guardrails and shoulders 

- 2,4-D Amine, Garlon 

3a, Roundup, Sahara, 

Tordon)

Along 4 miles of U.S. 84 

(spot spraying medians -

Roundup and Sahara)

Along 12 miles of U.S. 

84 (spot spraying 

medians and sidewalks -

Roundup and Sahara)

Other Organizations and Agencies

Santa Fe Watershed 

Association/City of Santa Fe

Along a less than 1-mile 

stretch of the Santa Fe 

River within Santa Fe 

(cut stump treatment -

Aquamaster).

Nature Conservancy Yes None in 2003 

Audubon Society and 

Canyon Road Association

Yes Along 2 miles of the 

Santa Fe River on private 

land (cut stump treatment 

- Aquamaster); 300- to 

500-foot stretch on City 

land 

Bureau of Indian Affairs Yes

Valles Caldera National 

Preserve

Yes Plan to treat 5 acres with 

Clopyralid

Southwest Strategy Yes

Earthworks Institute

(Galisteo Watershed Project)

Yes Prescribed grazing with 

goats

Rio Grande Restoration Yes 5 acre chain saw work 

with followup hand 

digging

210 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 1 • Past, Present and Future Weed Control Activities

Agency or Organization

Education 

and 

Awareness

Manual Control 

(hand pulling, 

grazing, and 

mowing) and 

Biological Control

Herbicide 

Treatment

Rio Arriba County Extension 

Service

Yes Leafy spurge 

“insectary” – biological 

control source

Bureau of Land Management

Albuquerque Field Office Yes Sandoval County: 115 

acres (Roundup)

300 acres (Arsenal and 

Roundup)

Taos Field Office Yes 0 acres

Farmington Field Office Yes 2 acres 23 acres (Grazon P+D), 5 

acres (Redeem), in 

eastern San Juan County.

15 acres (Grazon P+D) 

just east of Aztec.

National Park Service

Bandelier National 

Monument

Yes None in 2003

Chaco National Historical 

Park

Yes Early hand pulling. 10 acres over past 2 

years (Tordon-cut stump 

treatment)

Pecos National Historical 

Park

Yes 7,000 individual Scotch 

thistle plants (5-10 

gallons of Roundup total 

in a backpack sprayerspot treatment);

Minimal retreatment with 

Garlon 4a (cut stump 

treatment)

Final Environmental Impact Statement – Invasive Plant Control Project 211

Appendix 2 • Weed Species 

Ecology and Impacts

This appendix provides a brief overview of the weeds known to exist on the Forests. The 

“References Cited” chapter provides sources for further information about these species.

Black Henbane (Hyoscymas niger) (HYNI)

Black henbane is a biennial forb member of the nightshade family. This 

species can be identified by its brownish-yellow flowers that have a 

network of purple veins. It has a characteristically foul odor. Black 

henbane usually emerges in May and flowers from June to September, with 

peak flowering usually in July. Two rows of pineapple-shaped fruits appear 

in the fall. Reproduction is by seed (Encycloweedia 2003).

Black henbane is commonly found in pastures, fence rows, roadsides, 

waste places, and riparian areas. It does well in most soils, and will grow in 

a variety of environmental conditions. Black henbane is poisonous to 

livestock. However, because of the foul odor of the plant, livestock will 

seldom graze it and few cases of livestock poisonings have been reported. 

Black henbane usually establishes on disturbed or heavily grazed sites where it competes for 

moisture and nutrients with desirable plants. All parts of the plant are potentially poisonous 

(Encycloweedia 2003). Black henbane is also known as insane root, stinking nightshade, fetid 

nightshade, hog’s beam.

Bull Thistle (Cirsium vulgare) (CIVU)

Bull thistle is a coarse biennial, annual, or short-lived perennial to ~ 2 

m tall, with stiff-hairy foliage and conspicuous prickly-winged stems. 

Flowering is from June through October. It can be found in open 

disturbed sites, roadsides, hillsides, rangeland and forest openings. 

Thistles typically do not tolerate deep shade or constantly wet soils. 

Bull thistle grows best on heavy fertile soils. Plants exist as rosettes 

until flowering stems develop at maturity. Seeds germinate in fall after 

the first rains or in spring (Encycloweedia 2003).

Bull thistle is a problem in natural areas because it competes with and 

decreases desirable forage. Sharp spines deter wildlife from grazing. 

Bull thistle often dominates recently clearcut forest areas and 

infestations may limit growth of replanted tree seedlings.

Bull thistle is also known as spear thistle, plume thistle, bur thistle, roadside thistle, bank thistle, 

bird thistle, blue thistle, black thistle, button thistle, common thistle and Fuller’s thistle. 

Synonyms are Carduus lanceolatus L., Carduus vulgaris Savi, Cirsium lanceolatum (L.) Scop., 

Cirsium lanceolatum (L.) Scop. var. hypoleucum DC., Cirsium abyssinicum Sch.Bip.ex A.Rich, 

Conicus lanceolatus (L.) Willd., and Ascalea lanceolata (L.) Hill (Encycloweedia 2003).

Final Environmental Impact Statement – Invasive Plant Control Project 213
Appendix 2 • Weed Species Ecology and Impacts

Canada Thistle (Cirsium arvense) (CIAR4) 

Canada thistle is an erect perennial rhizomatous thistle, usually 0.5 - 1.0 

m tall. It can be confused with other thistles, especially bull thistle

(Cirsium vulgare), and the closely related musk thistles (Carduus spp.). 

Shoots emerge March - May when mean weekly temperatures reach 5 °C. 

Rosette formation follows, with a period of active vertical growth (about 

3 cm/day) in mid- to late-June. Flowering is from June to August. 

Additional common names include creeping thistle and California thistle 

(Encycloweedia 2003, Nuzzo 1997).

Canada thistle threatens natural communities by directly competing with 

and displacing native vegetation, decreasing species diversity, and changing the structure and 

composition of some habitats. It occurs in nearly every upland herbaceous community within its 

range. Canada thistle invades natural communities primarily through vegetative expansion, and 

secondarily through seedling establishment. It invades along riparian areas and irrigation ditches. 

Canada thistle is shade intolerant. It grows along the edges of woods (both deciduous and 

coniferous), but is rarely found within forests (Nuzzo 1997).

Dalmation Toadflax (Linaria dalmatica) (LIDA) 

and Yellow Toadflax (L. vulgaris) (LIVU2)

Toadflax is a persistent, aggressive invader capable of forming colonies through adventitious 

buds from creeping root systems that rapidly colonize open sites. These colonies can push out 

native grasses and other perennials, thereby altering the species composition of natural 

communities. Toadflax is most commonly found along roadsides, fences, rangelands, croplands, 

clear cuts, and pastures. Disturbed or cultivated ground is a prime candidate for colonization. This 

species is capable of adapting growth to a wide range of environmental conditions (Carpenter et 

al. 1998b, Encycloweedia 2003).

The seedlings of toadflax are considered 

ineffective competitors for soil moisture with 

established perennials and winter annuals. 

However, once established toadflax suppresses 

other vegetation mainly by intense competition 

for limited soil water. Mature plants are 

particularly competitive with winter annuals and 

shallow-rooted perennials. Mature toadflax 

plants grow to be between 0.8 to 1.5 m tall. 

Flowers are bright yellow and typically appear 

from May to August. Seeds are produced from 

July to October (Carpenter et al. 1998b).

Additional common names include broad-leaved 

toadflax, butter and eggs, wild snapdragon and 

common toadflax.

214 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 2 • Weed Species Ecology and Impacts

Diffuse Knapweed (Centaurea diffusa) (CEDI3)

Diffuse knapweed is a highly competitive and aggressive 

plant that forms dense colonies in pastures, overgrazed 

rangelands, croplands, and along riverbanks. It is especially 

adept at spreading along rights-of-way and farm roads, and 

can spread rapidly. Disturbed or overgrazed lands are prime 

candidates for colonization, but diffuse knapweed will also 

invade undisturbed grasslands, shrublands, and riparian 

communities (although infestations are typically less dense). 

The plants first form low rosettes and may remain in this 

form for one to several years. After they reach a threshold 

size they will bolt, flower, set seed, and then die. Thus they 

may behave as annuals, biennials or short-lived perennials, 

bolting in their first, second, third, or later summer, 

respectively. Plants of this type are often called semelparous 

perennials or short-lived monocarpic perennials (Carpenter et 

al. 1998a, Encycloweedia 2003).

Diffuse knapweed is the most commonly used name in North America. Additional common 

names include spreading knapweed and tumble knapweed. Acosta diffusa is a synonym for this 

species (Carpenter et al. 1998a).

Field Bindweed (Convolvulus arvensis) (COAR4)

Field bindweed is a persistent, perennial vine of the morningglory family which spreads by rhizome and seed. It is a weakstemmed, prostrate plant that can twine and may form dense 

tangled mats. Stems can grow to 1.5 m or longer, and its 

underground rhizomes may range from 5 cm to 2.6 m long. The 

extensive roots can measure 6.6 m long and penetrate deeply into 

the soil. Seedlings emerge from the soil erect and ascending. 

Field bindweed may be confused with Polygonum convolvulus L. 

and with Calystegia sepium. Field bindweed begins growing in 

the late spring or early summer and may persist until the first 

frost (Lyons 1998a, Encycloweedia 2003).

Because of its wide distribution, abundance and economic 

impact, field bindweed is considered one of the ten “world’s 

worst weeds.” Field bindweed has deep roots that store 

carbohydrates and proteins. They help field bindweed spread 

vegetatively and allow it to resprout repeatedly following removal of above ground growth. Like 

other weeds, field bindweed takes nutrients and water that would otherwise be available to 

desirable species. It can reduce the available soil moisture in the top 60 cm of soil to below the 

wilting point for many species. Field bindweed is primarily a problem in riparian corridors and 

mountain-mahogany shrubland/grassland, where it can rapidly choke out native grasses and forbs. 

Field bindweed may be mildly toxic to some grazing animals (Lyons 1998a, Encycloweedia 

2003).

Final Environmental Impact Statement – Invasive Plant Control Project 215
Appendix 2 • Weed Species Ecology and Impacts

Hoary Cress (Cardaria draba) (CADR)

Hoary cress displaces valuable rangeland forage species and is toxic to 

livestock. It reduces native biodiversity and forage quality. Disturbed sites 

are the most threatened. This species can grow in a variety of nonshaded, 

disturbed conditions, including roadsides, waste places, watercourses, and 

along irrigation ditches. It is found in a variety of upland habitats 

including open grasslands, the edge of riparian habitats and as a minor 

component of aspen/willow communities. It is not particular about soil 

type, and can grow in heavy or light, sandy, or gravelly loams. It is salttolerant, but prefers nonacidic soils. It is most aggressive in irrigated 

conditions or during moist years (Lyons 1998b, Encycloweedia 2003).

Hoary cress is also known as white weed, white top, heart-podded hoary 

cress, perennial peppergrass and Cranson dravier (Lyons 1998b, 

Encycloweedia 2003).

Leafy Spurge (Euphorbia esula) (EUES)

Leafy spurge emerges earlier in spring than most other species and 

also shows allelopathy toward associated species as evidenced by 

bare ground and lack of other forbs in dense patches of leafy spurge. 

One of the most important aspects of leafy spurge biology (in 

addition to production of large amounts of seed) is its ability to 

reproduce and spread rapidly via vegetative reproduction. As patches 

develop, density reaches over 200 shoots/m2 in light soils, and up to 

2,000/m2 in heavy soils (Biesboer 1996, Encycloweedia 2003)

Leafy spurge presents a management problem because it is a longlived, aggressive perennial weed that tends to displace all other 

vegetation in pasture, rangeland, and native habitats. It is particularly 

aggressive in drier sites such as hillsides and prairies. Forbs and 

grasses in natural areas may be completely displaced by leafy spurge

in a few years if the infestation is left unchecked. Rapid reestablishment of dense stands will occur after an apparently 

successful management effort because of the long-lived root system 

present in the soil (Biesboer 1996).

Musk Thistle (Carduus nutans) (CANU4)

Musk thistle in the United States includes a complex of closely-related species of the Carduus 

nutans group. Under natural conditions, musk thistle most often functions as a spring biennial, 

fall biennial, or winter annual. Plants of all ages overwinter as rosettes. Seed maturity and 

dispersal occur within 7 to 10 days of flowering. The bulk of the seeds fall near the parent plant 

with less than 1 percent being carried further. Seeds have been reported to remain viable in the 

soil for periods as long as 10 years (Heidel 1987, Encycloweedia 2003).

Musk thistle is most prevalent in disturbed areas such as roadsides and grazed pastures, but can 

invade deferred pastures and native grasslands. Musk thistle grows best on moist alluvial soils but 

216 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 2 • Weed Species Ecology and Impacts

tolerates a wide range of conditions, from acidic to saline soils. Plants 

establish poorly on highly acidic or nutrient deficient soils or soils with 

extremes in moisture content. Musk thistle seeds appear to possess 

allelopathic qualities. They can inhibit germination and radicle growth 

in other pasture species, but stimulate or have no affect on other seeds 

of their own species. Emerged musk thistle plants can also weaken 

other pasture species by an allelopathic interaction at the early bolting 

stage, when the larger rosette leaves are decomposing and releasing 

soluble inhibitors, and at the stage when bolting plants are dying and 

releasing insoluble inhibitors (Heidel 1987, Encycloweedia 2003).

Perennial Pepperweed (Lepidium latifolium) (LELA2)

Perennial pepperweed is an herbaceous perennial that produces 

dense stands with stems reaching up to 1.5 meters in height. 

These stems originate from large perennial below ground roots 

and emerge in early spring/late fall. Shoots will remain in the 

rosette form for several weeks before stems elongate (bolt). 

Shoots flower and fruit during late spring and continue 

throughout much of the summer. Plants senesce by mid- to latesummer while fruits remain on the stem (Renz 2000, 

Encycloweedia 2003, Morisawa 1999).

Perennial pepperweed is a highly invasive herbaceous 

perennial. It can invade a wide range of habitats including 

riparian areas, wetlands, marshes, and flood plains. Once 

established this plant creates large monospecific stands that 

displace native plants and animals and can be very difficult to 

remove. These plants can act as “salt pumps” which take salt 

ions from deep in the soil profile, transport them up through 

their roots and deposit them near the surface. This can favor 

halophytes and put other species at a disadvantage, thereby 

shifting plant composition and diversity.

This plant is most commonly referred to as perennial pepperweed or tall whitetop. Several other 

common names are used throughout the U.S. such as giant whiteweed, perennial peppergrass, 

slender perennial peppercress, broadleaf or broadleaved pepperweed, and ironweed.

Poison Hemlock (Conium maculatum) (COMA2)

Poison hemlock is a highly toxic weed found in waste places throughout much of the world. 

Poison hemlock reproduces only from seed, both as a biennial and winter annual, and 

occasionally as a short-lived perennial. Seeds germinate in autumn and plants develop rapidly 

throughout the winter and spring. Some produce flowering stems in the first spring and die in the 

summer. Others remain in the vegetative stage without producing flowering stems until the 

second spring, thus becoming a biennial. Plants are more likely to be biennial in very moist 

situations (Pitcher 1989).

Final Environmental Impact Statement – Invasive Plant Control Project 217
Appendix 2 • Weed Species Ecology and Impacts

Poison hemlock commonly occurs in sizable stands of dense, rank growth 

along roadsides, field margins, ditchbanks and in low-lying waste areas. It 

also invades native plant communities in riparian woodlands and open flood 

plains of rivers and streams. It can be a tenacious weed particularly in moist

habitats and along streams. It may act as a pioneer species quickly colonizing 

disturbed sites and displacing natives during early successional seres. The 

presence of poison hemlock degrades habitat quality and could indicate a 

management problem on an ecological preserve. This species is poisonous to 

both humans and livestock (Pitcher 1989).

Russian Knapweed (Acroptilon repens) (ACRE3)

Russian knapweed is the most commonly used name in North America. 

Additional common names include Mountain Bluet, Turkestan thistle, and 

creeping knapweed. A synonym for this species is Centaurea repens (Carpenter et al Undated, 

Encycloweedia 2003).

Russian knapweed is a perennial herbaceous plant of the aster (sunflower) family. It is 

characterized by its extensive root system, low seed production, and persistence. Russian 

knapweed spreads through creeping horizontal roots and seed. 

Shoots emerge early in spring shortly after soil temperatures 

remain above freezing. All shoot development originates from 

root-borne stem buds. These buds arise adventitiously at irregular 

intervals along the horizontal roots. Plants form rosettes and bolt 

in late May to mid-June. Russian knapweed flowers from June to 

October (Carpenter et al. Undated).

Russian knapweed can commonly be found along roadsides, 

riverbanks, irrigation ditches, pastures, waste places and 

clearcuts. Russian knapweed invades many disturbed western 

grassland and shrubland communities, as well as riparian forests. 

Once established, it can dominate an area and significantly reduce 

desirable vegetation (e.g. perennial grasses). It is a strong 

competitor and can form dense colonies in disturbed areas. Once 

established, Russian knapweed uses a combination of 

adventitious shoots and allelopathic chemicals to spread outward 

into previously undisturbed areas (Carpenter et al. Undated,

Encycloweedia 2003).

Russian Olive (Elaeagnus angustifolia) (ELAN)

Russian olive is a shrub or small tree in the Oleaster family (Elaeagnaceae). It can grow up to 9 

meters (30 feet) in height and is often thorny. Although Russian olive establishes primarily by 

seed, vegetative propagation can also occur. Russian olive is sometimes confused with the closely 

related autumn olive, which is also a weed. It is relatively shade tolerant, and once established, 

can persist throughout seral stages and become the climax dominant species (Tu 2003).

Russian olive can invade both open upland and riparian bottom land (marshland and other 

wetland) communities, alter the course of plant succession, and ultimately result in lowered levels 

218 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 2 • Weed Species Ecology and Impacts

of native plant and animal diversity. It negatively impacts natural 

areas by creating dense, monotypic stands that out-compete native 

vegetation, modifying vegetation structure, and displacing native 

wildlife. Russian olive can also alter nutrient cycling and system 

hydrology by spreading throughout woodlands, connecting lowland 

riparian forests with more open, upland areas. This contributes to the 

stabilization of riverbanks against future flooding, increasing 

overbank deposition, and limiting the number of suitable sites for 

native cottonwood regeneration. Russian olive trees have high rates 

of evapotranspiration, utilizing more water resources than native species, and can eventually 

change riparian sites into relatively dry uplands with Russian olive as the climax species. Dense 

thickets of Russian olive can also increase fuel loads that may cause catastrophic wildfire (Tu 

2003).

Russian olive is the most common name used for this species. Other names are oleaster and 

silverberry. Synonymns for this species are Elaeagnus iliensis and Elaeagnus umbellate (Tu 

2003).

Saltcedar (Tamarix spp) (TAMAR2)

Saltcedar is an aggressive, woody invasive plant species. It is a relatively long-lived plant that can 

tolerate a wide range of environmental conditions once established. It produces massive 

quantities of small seeds and can propagate from buried 

or submerged stems. It can replace or displace native 

woody species, such as cottonwood, willow and 

mesquite, which occupy similar habitats, especially when 

timing and amount of peak water discharge, salinity, 

temperature, and substrate texture have been altered by 

human activities. Saltcedar is a facultative phreatophyte, 

meaning that it can draw water from underground sources 

but once established it can survive without access to 

ground water. It consumes large quantities of water, 

possibly more than woody native plant species that 

occupy similar habitats (Carpenter 1998).

Saltcedar possesses a number of undesirable attributes, according to a number of authorities. It: 

(1) crowds out native stands of riparian and wetland vegetation; (2) increases the salinity of 

surface soil rendering the soil inhospitable to native plant species; (3) provides generally lower

wildlife habitat value than native vegetation; (4) dries up springs, wetlands, riparian areas and 

small streams by lowering surface water tables; (5) widens flood plains by clogging stream 

channels; (6) increases sediment deposition due to the abundance of saltcedar stems in dense 

stands; and (7) uses more water than comparable native plant communities. However, data to 

support these claims by various authors do not always exist (Carpenter 1998).

Scotch Thistle (Onopordum acanthium) (ONAC)

Scotch thistle is a vigorous biennial or short-lived perennial with coarse, spiny leaves and 

conspicuous spiny-winged stems. Plants typically germinate in fall after the first rains and exist as 

rosettes throughout the first year until flowering stems develop during the second spring/summer 

Final Environmental Impact Statement – Invasive Plant Control Project 219
Appendix 2 • Weed Species Ecology and Impacts

season. Severe infestations can form tall (3 m), dense, 

impenetrable stands, especially in fertile soils. Scotch thistles

reduce productivity and strongly compete with native plants for 

resources. Onopordum thistles are distinguishable from other 

genera of thistles with spiny stern-wings and/or leaves by having 

receptacles that lack bristly chaff and have deep pits surrounded 

by membranous extensions (Encycloweedia 2003).

Infestations of Scotch thistle often start in disturbed areas such as 

roadways, campsites, burned areas and ditchbanks. This species 

adapts to riparian areas, but can be a serious problem in range 

areas.

Scotch thistle is also known as cotton thistle, woolly thistle, 

winged thistle, jackass thistle and heraldic thistle (Encycloweedia 

2003).

Siberian Elm (Ulmus pumila) (ULPU)

Siberian elm is a fast growing, small to medium size tree 

with an open, round crown of slender, spreading 

branches. Its spread is equal to three-fourths its height. Its 

rough bark is gray or brown and shallowly furrowed at 

maturity. Both the small blunt buds and slender, smooth 

twigs are nearly hairless. Siberian elm is distinguished 

from American elm and slippery elm based on its 

relatively small leaves that are symmetrical or nearly so 

at the base and are once serrate.

This tree can invade and dominate disturbed areas in just a few years. Seed germination rate is 

high and seedlings establish quickly in sparsely vegetated areas. It grows readily in disturbed 

areas with poor soils and low moisture. This species forms thickets of hundreds of seedlings.

Some Siberian elm have been found to grow taller than 40 feet in New Mexico; there are trees 

that are approaching 50 to 70 feet. Densities have been found to be as high as 5,000 stems per 

acre when counted in a riparian restoration project in Tijeras in 

Bernalillo County.

Spotted Knapweed (Centaurea biebersteinii) 

(CEBI2)

Spotted knapweed is a biennial or short-lived perennial composite with 

a stout taproot. It resembles other species in the genus, including diffuse 

knapweed, black knapweed, brown knapweed, short-fringed knapweed, 

and featherhead knapweed. The best way to distinguish spotted 

knapweed is by the dark tips and fringed margins of its phyllaries. All 

of these species are capable of becoming serious weed problems (Mauer 

1987, Encycloweedia 2003).

220 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 2 • Weed Species Ecology and Impacts

The competitive superiority of this species suggests preadaptation to disturbance. The initial 

invasion of spotted knapweed, like other weeds, is correlated highly to disturbed areas. Once a 

plant or colony is established though, it may invade areas that are relatively undisturbed or in 

good condition with gradual, broad, frontal expansion. This invasion is associated with a decline 

in the frequency of some species and a decline in species richness overall. The knapweed is 

highly adept at capturing available moisture and nutrients, and it quickly spreads, choking out 

other vegetation. The water storage capacity of the soil decreases, and soil erosion increases as 

the network root system of the native species is lost, replaced by the taproot of the knapweed 

(Mauer 1987).

Yellow Starthistle (Centaurea solstitalis) (CESO3)

Yellow starthistle is an erect winter annual (sometimes biennial) mostly to 1 m tall (occasionally 

to 2 m tall) with spiny yellow-flowered heads. Taproots grow vigorously early in the season to 

soil depths of 1 m or more, giving plants access to deep soil moisture during the dry summer and 

early fall months. Vigorous individuals of yellow starthistle may develop flower heads in branch 

axils. Plants usually senesce in late summer or fall. Often a dense layer of thatch develops on 

heavily infested sites (DiTomaso 2001, Encycloweedia 2003).

Yellow starthistle is best adapted to open grasslands with average 

annual precipitation between 10 and 60 inches (25 to 150 cm) per 

year. It is generally associated with deep, well-drained soils. 

Because of its high water usage, yellow starthistle threatens 

native plant ecosystems. Yellow starthistle infestations can reduce 

wildlife habitat and forage, displace native plants, and decrease 

native plant and animal diversity. Dense infestations not only 

displace native plants and animals, but also threaten natural 

ecosystems and nature reserves by fragmenting sensitive plant 

and animal habitat (DiTomaso 2001, Encycloweedia 2003).

When ingested by horses, yellow starthistle causes a neurological 

disorder of the brain called “chewing disease.” In most cases 

poisoning destroys the animal’s ability to chew and swallow and 

death occurs through starvation or dehydration. Other animals, 

including mules and burros, are not susceptible to the toxic effect 

of the weed (DiTomaso 2001, Encycloweedia 2003).

Yellow Starthistle quickly establishes monocultures, even in 

ungrazed and undisturbed areas, since it comes up before native plants in the spring.

Final Environmental Impact Statement – Invasive Plant Control Project 221

Appendix 3 • Herbicides: Characteristics, 

Effects and Risk Assessments

This appendix provides the FEIS reader with a summary of the available scientific information 

about the characteristics and effects of herbicides proposed for use in this project. More detailed 

information can be found in literature cited in the FEIS as well as on national and regional Web 

sites managed by other agencies and organizations including the Environmental Protection 

Agency (EPA), USDA Forest Service, The Nature Conservancy, and Colorado Department of 

Agriculture.

A key component of this analysis has been the individual risk assessments developed by the 

Forest Service for each herbicide. Each risk assessment discusses the formulations analyzed for 

use in this project. These risk assessments were developed to document the process for 

determining the risk of using each herbicide generally, with worksheets provided to evaluate the 

risk at project level circumstances (such as application rate and application method). The risk 

assessments provide Forest Service officials with a summary of the most relevant information 

available to the use of herbicides. They are not comprehensive summaries of all the available 

information. After comment on the DEIS raised concerns with adequate evaluation of the effects 

of the proposed use of herbicides, a further review of the risk assessments occurred. As a result, 

this appendix incorporates by reference the 12 risk assessments available to date: 

Table 57. Herbicide Risk Assessment Information

Herbicide Name Date Prepared Reference Pages 

1 2,4-D September 20, 1998 SERA 1998a 241

2 Clopyralid December 5, 2004 SERA 2004c 154

3 Chlorsulfuron November 21, 2004 SERA 2004a 180

4 Dicamba November 24, 2004 SERA 2004b 179

5 Glyphosate March 1, 2003 SERA 2003a 281

6 Hexazinone March 4, 1997 SERA 1997 161

7 Imazapic December 23, 2004 SERA 2004f 110

8 Imazapyr December 18, 2004 SERA 2004e 149

9 Metsulfuron December 9, 2004 SERA 2004d 152

10 Sulfometuron September 11, 1998 SERA 1998b 163

11 Picloram June 30, 2003 SERA 2003c 133

12 Triclopy March 15, 2003 SERA 2003b 264

Final Environmental Impact Statement – Invasive Plant Control Project 223
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

Program Description

Each risk assessment describes the general program, including the specific commercial 

formulations used by the Forest Service. The following table summarizes that information from 

the risk assessments.

Table 58. Herbicide Use Program Description

Herbicide Name Other Information

1 2,4-D Selective to broadleaf plants. Some formulations include dicamba, glyphosate, 

picloram, triclopyr and one (Aqua Kleen) has been labeled for aquatic weed 

control covered in the risk assessment, but this use is not considered in the 

Invasive Plant Project EIS because of potential impacts to sensitive fish.

2 Clopyralid Very selective herbicide used primarily to control broadleaf weeds such as 

spotted knapweed.

3 Chlorsulfuron Wide spectrum. Recommended for pre-emergent and early post-emergent control 

of many annual, biennial and perennial broadleaf weeds. Used only for weed 

control. 

4 Dicamba Selective for broadleaf and woody vegetation.

5 Glyphosate Wide spectrum, including grasses; 35 formulations registered for forestry use.

6 Hexazinone Selective for broadleaf; used for site preparation and conifer release.

7 Imazapic Selective for annual and perennial grasses and some broadleaf weeds.

8 Imazapyr Wide spectrum used on grasses, brush, conifer release, etc.

9 Metsulfuron methyl Selective to control brush and certain woody plants, annual and pereninnial 

roadleave weeds and annual grassy weeds. 

10 Sulfometuron methyl Nonselective used mainly for site preparation to reduce grasses. Slightly more 

selective than glyphosate.

11 Picloram Selective for broadleaf weeds and brush, but selectivity depends on application 

rate and season of use.

12 Triclopyr Selective for broadleaf and woody plants. One formulation (Renovate 3) has been 

labeled for aquatic weed control and is covered in the risk assessment, but is not 

considered in the plant EIS.

Application Methods

The risk assessments include reviews of the common application methods. For herbicides 

registered for aerial application, an assessment has been made of the risk of using these 

formulations. However, because this project anticipates separate analysis for this use, it has not 

been included in this summary in detail. In addition, as mentioned in the previous table, 

formulations of 2,4-D and triclopyr are registered for use in aquatic environments, but were not 

contemplated for use in the Invasive Plant Control Project because of potential to affect sensitive 

fish, such as the Rio Grande cutthroat trout.

Therefore, for the herbicide formulations considered, the major application methods are 

o Selective application directly to foliage (foliar), with a backpack sprayer

o Cut and squirt

o Boom spray along roads

The FEIS also includes use of direct application (rag/brush/wick), which have not been described 

in the risk assessments, but that will have lower risk than the spray methods (assuming the use is 

224 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

approved for the herbicide and that protective equipment is used to avoid additional exposure to 

workers).

Application rates are listed in the table below. The risk assessments describe a range based on 

label, or where information is available, identifies a typical rate to use based on known use 

patterns in the Forest Service. Each risk assessment also includes use statistics by Forest Service 

Region for each herbicide, where available.

Table 59. Herbicides Formulations, Application Rates, Target Plants

Herbicide 

Name Trade Name(s) Application Rate 

(pounds per acre) Target Invasive Plants

1 2,4-D No longer single 

manufacturer, 20 

formulations

0.5 to 2 

(1 typical)

Knapweeds, thistles, saltcedar, 

Siberian elm, Russian olive.

2 Clopyralid Transline 0.09 to 0.5 Spotted knapweed, thistles, black 

henbane

3 Chlorsulfuron Telar, Glean 0.056 Thistles in rangelands w/little 

effect on desirable perennial 

grasses

4 Dicamba Banvel, 

Vanquish

0.25 to 1

(0.3 typical)

Asteraceae (composite) and 

Fabaceae (legume) families 

knapweeds, thistles

5 Glyphosate Roundup, Rodeo 0.5 to 7

(2 is typical)

Grasses, forbs, vines, shrubs, 

trees. Good for saltcedar with 

formulations labeled for use in 

riparian zones.

6 Hexazinone Velpar, Pronone 4-6 Broad spectrum to control 

annual, perennial broadleaf, 

some grass, some woody species.

7 Imazapic Plateau 0.13 Leafy spurge, perennial 

pepperweed

8 Imazapyr Arsenal, 

Chopper, Stalker

0.45 Annual and perennial grasses, 

broadleaf herbs, woody species 

such as saltcedar, field bindweed.

9 Metsulfuron Escort, Ally 0.03 up to 0.15 Whitetop, houndstounge, 

pepperweed, hoary cress

1

0

Sulfometuron

methyl

Oust 0.1 Nonselective used mainly for site 

preparation. Grasses such as cheat 

grass.

1

1

Picloram Tordon, Grazon, 

Pathway

0.35 Thistles, knapweeds, poison 

hemlock, 

1

2

Triclopyr Garlon, 

Pathfinder II, 

Remedy RTU, 

1 Woody plants, broadleaf, with 

little impact to grasses. Saltcedar, 

Siberian elm, Russian olive.

In general, the selective herbicides would be preferred over the wide spectrum, especially where 

erosion is a concern because any existing non-target grasses would be left to hold soil. 

Final Environmental Impact Statement – Invasive Plant Control Project 225
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

revegetation efforts using grasses would also be more successful with the use of the selective 

herbicides for the same reason.

As noted in the table, the risk assessment preparation dates from 1997 through December 2004. 

Regardless of the completion date, each risk assessment follows a set method for analyzing the 

information. The following process applies to the human risk assessment:

o Describe use of the herbicide in Forest Service programs. This includes brand names of 

the registered herbicides, as well as the generally accepted application rates (assuming 

they are somewhat different from the permitted label rate but within those permitted 

under the label).

o Describe the hazards as best presented in the literature available, including “open 

literature” cited by a number of commenters on the Invasive Plant DEIS (e.g., Journal of 

Pesticide Reform).

o Describe potential exposure to workers, based on the proposed application methods, 

using two plausible exposure scenarios from normal application (from backpack spray, 

and from vehicle mounted boom spray), as well as a number of accidental exposure 

scenarios (wearing contaminated gloves, accidental spills on bare skin that includes 

hands, legs).

o Describe potential exposure to the general public, based on a number of possible 

scenarios, including direct accidental spray, walking through a sprayed area, eating 

contaminated vegetation, and drinking contaminated water.

o Describe the Reference dose (RfD), which may have both an acute and a chronic 

measure.

o Finally, a “hazard quotient” (HQ) is calculated by dividing the expected exposure by the 

RfD. A number less than one is considered below a level of concern. A number greater 

than one raises a concern, but may not pose a high risk if the length of the exposure is 

short term. An HQ greater than 10 raises a concern that would require further evaluation 

of the cause in order to avoid this scenario.

The outline for the ecological risk to animals is similar, except it includes specific information 

about the toxicity of each herbicide to various species of animals where information is available, 

as well as terrestrial and aquatic plants. The exposure is also evaluated based on a number of 

plausible scenarios, which include direct spray, the animal ingesting herbicide from vegetation or 

water. A hazard quotient is calculated by dividing the exposure by the reference dose (human risk 

assessment or other marker for animals (NOEL)).

Plant risks are also evaluated. Because herbicides are intended to kill plants, the possibility is 

much higher that non-target plants would be affected. Exposure scenarios in the risk assessments 

include accidental direct spray, drift during application, runoff, wind movement of soil containing 

the herbicide, and irrigation water. Hazard quotients are developed using the Lowest Observable 

Effect Concentration (LOEC) provided by available data.

Many comments on the DEIS raised similar scenarios (spills, drift, etc.), and so additional 

comparison of herbicides has been provided in this appendix to answer the questions raised.

Although not a comprehensive review of all study information about the respective herbicide, 

each assessment uses sources of information that are evaluated, along with any caveats that may 

226 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

apply to specific information/studies. In addition, the EPA includes peer reviewed studies when 

possible and continues to update the information as new data is shown to be relevant. When 

information is not available, the risk assessments state this and provide, if possible, inferences of 

risk from the available information.

These are standard risk assessment procedures, tested by several years of EPA use and scrutiny by 

the larger scientific community. As noted in a number of the risk assessments, the anticipated 

effects can be minimized or avoided by prudent industrial hygiene practices during proper 

handling of the herbicides. Typically, as noted in the clopyralid risk assessment, “the only 

reservation attached is that associated with any risk assessment: Absolute safety cannot be 

proven and the absence of risk can never be demonstrated. [emphasis in the original text]. No 

chemical, including clopyralid, has been studied for all possible effects and the use of data from 

laboratory animals to estimate hazard or the lack of hazard to humans is a process that is fraught 

with uncertainty. Prudence dictates that normal and reasonable care should be taken in the 

handling of this or any other chemical. Notwithstanding these reservations, the use of clopyralid 

does not appear to pose any risk of systemic toxic effects to workers or the general public in 

Forest Service programs.”

A few key terms used in the risk assessments to express their findings are provided here:

Table 60. Herbicide Risk Assessment Standard Terminology

Term Abbrev Explanation (see risk assessments for specific definitions)

Toxic The short-term effects of exposure to a chemical, which appear immediately upon 

exposure. See specific sections of the risk assessments for definition of the various 

“end points” of exposure, e.g. nervous system.

Subchronic The effects that do not appear immediately, but that will appear over a short period of 

time after exposure, or if exposure continues for a period of time.

Chronic Effects over a number of years (or over a lifetime) of repeated exposure.

No Observed 

Adverse Effect 

Level

NOAEL The amount of a substance that shows no toxic effects given short term (mg/kg body 

weight) or to show lack of chronic effects over long duration, may be expressed as a 

dose over time (mg/kg/day).

No Observed 

Effect 

Concentration

LOEC Used for plants to determine the lowest concentration at which a concentration of 

herbicide had no effect.

Safety Factor Once a no observable effect level is established, safety factors are applied for the 

human risk assessments in order to set a reference dose. Safety factors depend on the 

information used for the no effect finding. Factors include such circumstances as 

uncertainties in species-to-species extrapolation as well as accounting for sensitive 

individuals in the population. Each factor reduces the exposure dose by dividing by 

10, so that a NOAEL of 5 would become an RfD of 0.05 if three safety factors were 

applied.

Reference Dose RfD The amount of a substance that would not have an adverse effect if this dose were 

given every day over a lifespan of 70 years. It is measured in milligrams of substance 

per kilogram body weight of the person of concern, per day (mg/kg/day). An RfD is 

basically defined as a level of exposure that will not result in any adverse effects in 

any individual. The U.S. EPA RfDs are used because they generally provide a level of 

analysis, review, and resources that far exceed those that are or can be conducted in 

support of most Forest Service risk assessments. In addition, it is desirable for 

different agencies and organizations within the Federal government to use concordant 

risk assessment values. See EPA paper.

Hazard Quotient HQ The result of dividing the reference dose by the expected exposure to provide a 

measure of the hazard and so a relationship to the expected risk. 

Final Environmental Impact Statement – Invasive Plant Control Project 227
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

Term Abbrev Explanation (see risk assessments for specific definitions)

Level of 

Concern

This term suggests a point when hazard quotient reaches a level that should be noted. 

Any HQ below unity (1) is below the level of concern. A number less than one means 

the risk is lower than the RfD. The smaller the fraction, the lower the risk in relation 

to the RfD.

Overall Conclusions

Of the 12 herbicides considered in this analysis, a range of risks exists depending on different 

conditions and uses. The difficulty in drawing general conclusions lies in the complexity of the 

proposed use, the variety of the situations that will be involved, and a certain level of uncertainty 

that becomes inevitable when factoring in the numerous possibilities. Nonetheless, a number of 

general conclusions can be drawn, with the understanding that exceptions exist to these 

conclusions, but they represent a view with the totality of evidence taken into consideration.

In general the following conclusions can be made about the herbicides proposed for use:

o As with most chemicals, mild irritation to the eyes can result from exposure to relatively 

high levels of these herbicides. For all but one of the herbicides listed (the exception 

being hexazinone), eye irritation is likely to be the only overt effect as a consequence of 

mishandling these herbicides. These effects can be minimized or avoided by prudent 

industrial hygiene practices during the handling of the compound. Extra precaution is 

required when handling hexazinone.

o Acute effects of the herbicides are documented for animals and people. Many of the 

comments on the DEIS noted these acute effects, which have been supported by research 

noted in the respective risk assessments. What the comments do not include is the 

evaluation of the likely exposure scenarios, as well as the reference dose relationships 

that indicate when, if ever, a likely exposure scenario would result in an adverse acute or 

chronic effect. The risk assessments provide this full context for each of the 12 

herbicides.

o Of the 12 herbicides reviewed, 2 (clopyralid and picloram) contain hexachlorobenzene, 

which has been linked to cancer. Bio-assays of both of these herbicides do not indicate a 

similar correlation between the herbicides and cancer. The risk assessments undertook an 

evaluation of the cancer risk for theses two herbicides and found it to be below the 

threshold established by the Forest Service (1 chance in a million). Although any risk 

may seem too high, the background level of the contaminant causes a greater risk than 

either of the herbicides.

o No studies have shown a direct cause-effect link between the other herbicides proposed 

for use and cancer. Evidence provided in the comments on the DEIS indicate links to 

cancer of several of these herbicides. The risk assessments evaluate many of these studies 

cited and found them to rely on epidemiological methods. Because of the large number of 

variables involved in these types of studies, they cannot provide a direct cause-effect 

relationship, although they are useful for directing research to find more direct causes. Of 

the information available for the risk assessments, no bio-assays have established a 

definitive link.

o The risk assessments include the formulations used by the Forest Service in its programs 

and so includes the impurities/metabolites, as well as the “inert” ingredients (otherwise 

228 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

referred to as “other” ingredients) that make up the labeled products. The confidential 

ingredients are assessed (by the EPA and Forest Service risk assessment authors), but this 

information cannot be disclosed by the regulatory agency because of the confidentiality 

section of the FIRFA. Although some of the other ingredients are listed by EPA as 

unknown, or having some effect, these ingredients are also in wide use within other 

products (for example, isopropyl alcohol and ethanol are “other ingredients in some 

formulations). The risk assessments take these factors into account, and found no reason 

to assert that the ingredients in the formulations proposed for use will have any risks 

other than those disclosed.

o Comments on the DEIS not only mention hexachlorobenzene, but other contaminants as 

well, including 2,3,7,8 dioxin, an impurity in Agent Orange that has been linked to 

cancer, birth defects and other toxic or chronic effects. The risk assessment for 2,4-D 

discusses the historic context of Agent Orange and the lack of evidence that 2,4-D was 

the component of the herbicide that caused the effects. As a result of reviews, 2,4,5-T 

(which has dioxin as a manufacturing impurity) has been taken off the market and similar 

effects have not been reported for 2,4-D.

o Triclopyr includes a metabolite (TCP) that has been evaluated in the risk assessment and 

been determined to have a low risk of impact.

o A group of herbicides that is relatively low risk to people has high potency and so these 

pose the highest risk of affecting non-target plant species, in some cases up to 900 feet 

away from the site where a boom sprayer might be used. These herbicides should not be 

used with a vehicle mount boom spray unless drift is controlled. These herbicides would 

not be appropriate to use near sensitive non-target plant species.

o Although a number of comments on the DEIS stated that many of the herbicides caused 

reproductive problems, the risk assessments point to the two that specifically should be 

avoided by pregnant women as a precaution (dicamba and sulfometuron methyl). Other 

herbicides show no similar characteristics. Studies used as basis to make the comments 

on the DEIS appear to have used epidemiological methods that do not establish a direct 

cause-effect relationship.

o The risk assessments assume a certain level of water contamination in order to evaluate 

risk. Each risk assessment determines the likelihood that this amount would have an 

adverse acute or chronic effect. Spill scenarios (200 gallons of herbicide formulation into 

a small pond) are included to assess the concentration that might occur from improper 

handling, even though this scenario has a low plausibility. Not all of the herbicides rose 

above a level of concern, even under this scenario. Others show a short-term exposure 

above the level of concern. As unlikely as the accidental spill scenario is to occur once, it 

would need to occur repeatedly to pose a long-term risk, and so this exposure scenario is 

considered very unlikely to pose an actual risk. 

o The risk assessments also assume a number of accidental exposure scenarios for workers, 

for the general public, and for animals (terrestrial and aquatic) as well as non-target 

plants. The assessments have identified which application methods of which herbicides 

pose the greatest risk in a given circumstances (for example, near a campground vs. in 

rarely visited open country).

o Comments on the DEIS were critical of the concept of Reference Dose (RfD) because, as 

stated in comments, it does not adequately account for the sensitive segments of the 

population who may be affected by herbicides even if the RfD is not exceeded. The risk 

Final Environmental Impact Statement – Invasive Plant Control Project 229
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

assessments address this issue where possible, although acknowledging that the very 

small amounts that trigger these effects cannot be quantified or determined to be 

attributed to the herbicides under review. The EPA describes its use of RfD as the update 

of its previous methods, with this method have a more objective basis to describe risk. 

Thus the RfD concept is the state of the EPA’s technology, not outdated as comment on 

the DEIS states.

o Synergistic effects have been evaluated in the risk assessments to the extent possible 

from existing information. As noted in the risk assessments, however, no test regime can 

anticipate every possible combination. Still, because the EPA registers formulations that 

include mixtures of separate herbicides, the risks of these combinations is generally 

known. Two of these products (Tordon 202c and Tordon 75D) mix picloram with 2,4-D 

to achieve results. The risk assessments mention a level of uncertainty with theses 

formulations. Neither of these formulations is used by the Forest Service, however.

o Persistence of the various herbicides was a point of concern in several comments on the 

DEIS. Although important to understand in terms of how long the herbicide stays 

effective in controlling target plants, it is less useful in evaluating risk. The risk 

assessments determine risk based on exposure scenarios at full application strength, 

assuming no reduction in active ingredient over a period of several months, which is a 

conservative estimate since herbicides are most persistent in soil, where exposure is least 

likely. Persistence in water is lowest for most herbicides (a few days), but again the 

assessment of risk assumes no degradation occurs over the time of exposure. Even at 

those elevated levels, the level of concern is not reached. In the acute exposure scenario 

that includes drinking water from a pond that received a large (200 gallon) spill, the level 

exceeds the RfD for a short duration, not long term, and the acute exposure does not 

reach anywhere close to toxic levels. Exposure at levels known to cause harm, either 

short term acute exposures or long-term chronic exposures, do not occur.

o The likelihood of the exposure scenarios occurring in the project proposed for the Carson

or Santa Fe forests make them implausible. Stock tanks could be contaminated to a 

smaller degree than the scenario suggests, but the likelihood is remote. For the exposure 

scenario to occur, a small child would drink water from the stock pond immediately after 

a spill.

o Not all herbicides should be used along waterways, but several show low risk to aquatic 

plants and animals under the proposed use. As mentioned previously, two formulations 

are registered for aquatic use, but because of the potential to impact sensitive fish, have 

not been included in this project. Separate analysis would be conducted to use them. The 

herbicides that may be used in riparian areas have been registered for this application. 

The key to low risk use is selecting the formula based on registration, not simply the 

herbicide’s active ingredient. For example, Roundup and Rodeo both contain glyphosate

as an active ingredient. Roundup contains an ingredient polyoxyethyleneamine (POEA) 

that is extremely toxic to amphibians. Rodeo does not contain this ingredient and so has 

been registered for use in aquatic environments where Roundup has not. 

230 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

Human Health Risk Assessment

This discussion reviews the risks to people associated with herbicide application. The following 

referenced literature was used to analyze potential human health risks associated with herbicide 

application. Although the risk assessments consider aerial application of herbicides, this project 

does not propose such a use.

• The Risk Assessment for Herbicide Use in Forest Service Regions 1, 2, 3, 4 and 10 and 

on Bonneville Power Administration Sites (USDA FS 1992) (referred to as RAHUFS). 

This analysis was developed for the Forest Service specifically to address human health 

issues raised by use of herbicides.

• Assessing the Safety of Herbicides for Vegetation Management in the Missoula Valley 

Region – A Question and Answer Guide to Human Health Issues, referred to as ASH 

(Felsot 2001).

• Risk assessments completed by the Forest Service under contract with Syracuse 

Environmental Research Associates (shown in Table 57).

As noted above, the three levels of analyses to determine risk are as follows:

• Review of toxicity test data (i.e., acute, chronic, and subchronic) for herbicides proposed 

for use on the project to determine dosage that could pose a risk to human health. 

Toxicity test data on laboratory animals is available for herbicides proposed for use in 

this analysis. Most tests have been conducted under EPA pesticide registration/reregistration requirements for use in the United States. The EPA uses test data to determine 

conditions for use of herbicides in the United States.

• Estimate of exposure levels to which workers (applicators) and general public may be 

exposed during treatment operations. These exposure levels tend to be very conservative, 

with the highest doses expected multiplied by a factor of 100 to provide margins of 

safety.

• Determine potential health risks by comparing dose levels to toxicological thresholds 

developed by EPA.

Factors Affecting Hazard of Herbicides

Toxicity of Herbicides

A comparison of toxicity for herbicides proposed for use in this project is shown in Table 57. 

Toxicological studies using animals typically involve purposeful exposure to dosages (per unit of 

body weight) required to cause an effect (i.e. tumors, changes in immunity, etc.) or to establish a 

Lowest Observed Effect Level, known as a (LOEL) or a No Observed Effect Level (NOEL). This 

often requires administration of relatively high doses of a chemical in order to document an effect 

or lack thereof.

Acute Toxicity

Acute toxicity is measured by the LD50, defined as the dosage of toxicant expressed in milligrams 

per kilogram of body weight, which is lethal to 50 percent of animals in a test population within 

14 days of administration (USDA FS 1992). Risk assessments for the herbicides proposed for use 

Final Environmental Impact Statement – Invasive Plant Control Project 231
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

show that the likelihood of exposure at these acute levels is not plausible, even in an accidental 

spill scenario (Infoventures 1995a-j; EXTOXNET 1996a-h).

Subchronic and Chronic Toxicity

There is considerable information on subchronic and chronic effects due to exposure to herbicides 

in controlled animal studies. Subchronic and chronic effects are those that might occur over a 

long period of time, after weeks or years of exposure. Subchronic and chronic effects are 

reviewed in terms of potential impacts to their potential neurological or reproductive effects. 

These evaluations assume some lower threshold level below which these effects would not occur.

Other potential health effects evaluated include the herbicide potential to be carcinogenic, 

mutagenic, or teratogenic. These impacts are not threshold dependent, and so they are evaluated 

under the assumption that any level may cause the health effect. Hence, they rely on probability, 

based on exposure levels.

Considering anticipated exposure levels to workers and the public (Arbuckle 1999; Charles et al. 

1996; Faustini 1996; Ibrahim, et al. 1991; Mattsson 1997; Mustonen 1986; Infoventures 1995a-j; 

EXTOXNET 1996a-h; EPA 1990a; EPA 1990b; SERA 1995, 1996, 1997a, 1997b, 1998a, 1998b, 

1999a, 1999b, 2000, 2001, 2002, 2003a, 2003b, 2003c, 2004a, 2004b, 2004c, 2004d, 2004e,

2004f).

Table 61. Herbicide Characteristics

Herbicide Carcinogenic1 Mutagenic and 

Reproductive2

Acute oral LD50 for rats 

(mg/kg/day)

2,4-D D No 100 - 1,800

Clopyralid E No 2,675 - 5,000

Chlorsulfuron E No >5,000

Dicamba D No 757 - 1,701

Glyphosate E No 2,000 - 6,000

Hexazinone D No 1,690

Imazapic E No 5,000

Imazapyr E No >5,000

Metsulfuron methyl E No to slight >5,000

Sulfometuron methyl E No >5,000

Picloram E No 3,000 - 5,000

Triclopyr E No to slight 630 - 729

1

 EPA carcinogenicity classification based on daily consumption for a 70-year life span. D = Not 

Classifiable as to Human Carcinogenicity; E = Evidence of Non-Carcinogenicity 2

 Unlikely that compound is mutagenic or would pose a mutagenic risk to humans at expected exposure 

levels.

Source: Infoventures 1995a-j; EXTOXNET 1996a-h; EXTOXNET 2001; EPA 1990a; EPA; 1990b; SERA

1995, 1996, 1997a, 1997b, 1998a, 1998b, 1999a, 1999b, 2000, 2001, 2002, 2003a, 2003b, 2003c. 

2004a, 2004b, 2004c, 2004d 2004e, 2004f.

The Reference Dose (RfD) provides a measure of long-term exposure that could result in chronic 

toxic effects. Generally, the dose-response assessments used in Forest Service risk assessments 

232 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

adopt RfDs proposed by the EPA as indices of acceptable exposure. An RfD is a level of exposure 

that will not result in any adverse effects in any individual. The EPA RfDs are used because they 

generally provide a level of analysis, review, and resources that far exceed those that are or can be 

conducted in support of most Forest Service risk assessments. In addition, it is desirable for 

different agencies and organizations within the Federal Government to use concordant risk 

assessment values. (Infoventures 1995a-j; EXTOXNET 1996a-h, EXTOXNET 2001.)

The Reference Dose comparison is discussed in more detail with the exposure risks discussion 

later in this section.

Synergistic Interactions

Concerns are occasionally raised about potential synergistic interactions of herbicides with other 

herbicides in the environment or when they are mixed during application (tank mixing). 

Synergism is a special type of interaction in which the combined impact of two or more 

herbicides is greater than the impact predicted by adding their individual effects. The RAHUFS 

(USDA FS 1992) addresses the possibility of a variety of such interactions. These include the 

interaction of the active ingredients in an herbicide formulation with its inert ingredients, the 

interactions of these herbicides with other herbicides in the environment, and the cumulative 

impacts of spraying as proposed with other herbicide spraying to which the public might be 

exposed.

As noted in various risk assessments, no guarantee can be made regarding the effects of a 

chemical being zero (Infoventures 1995a-j; EXTOXNET 1996a-h, 2001, SERA 1995, 1996, 

1997a, 1997b, 1998a, 1998b, 1999a, 1999b, 2000, 2001, 2002, 2003a, 2003b, 2003c, 2004a,

2004b, 2004c, 2004d, 2004e, 2004f). Similarly, guarantee cannot be made about the absence of a 

synergistic interaction between herbicides and/or other chemicals to which workers or the public 

might be exposed. For example, exposure to benzene, a known carcinogen that comprises 1 to 5 

percent of automobile fuel and 2.5 percent of automobile exhaust, followed by exposure to any of 

these herbicides could result in unexpected biochemical interactions. Analysis of the infinite 

number of materials a person may ingest or be exposed to in combination with chemicals is not 

feasible. This being said, there is some indication that the co-exposure to 2,4-D and picloram may 

induce effects not associated with exposure to 2,4-D or picloram alone (SERA 2003c, Cox 1998; 

EXTOXNET 1996a). As noted in the picloram risk assessment, 2,4-D proposed for use by the 

Forests is an amine formulation which is water soluble. The risk assessments note formulations of 

picloram and 2,4-D that have somewhat higher suggested links to these effects. One called 

Tordon 75D and another called Tordon 202C are not proposed for use by the Forest Service 

(SERA 2003c). Moreover, the formulations where these effects have been noted are note risk 

assessments conclude, however, that the additive effect of Forest Service herbicide use lies below 

the background levels for many of these chemicals (SERA 1995, 1996, 1997a, 1997b, 1998a, 

1998b, 1999a, 1999b, 2000, 2001, 2002, 2003a, 2003b, 2003c, 2004a, 2004b, 2004c, 2004d, 

2004e, 2004f, EXTOXNET 1996a-h, 2001).

Impurities, Adjuvant and Inert ingredients in Herbicide Formulations

During commercial synthesis of some pesticides, byproducts can be produced and carryover into 

the product eventually formulated for sale. Occasionally byproducts or impurities are considered 

toxicologically hazardous, and their concentrations must be limited so that potential exposures do 

not exceed levels of concern (Felsot 2001).

Final Environmental Impact Statement – Invasive Plant Control Project 233
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

Technical grade picloram (prior to mixing with other inerts) and clopyralid contains 

hexachlorobenzene (HCB) as a byproduct of the synthesis of the active ingredients (USDA FS 

1999c). HCB is also a byproduct of chlorinated solvents used extensively in industry and 

occasionally around the home. Because of this chemical’s prevalence in the environment, it has 

been assigned a background level of 0.00001 (1 x 10-6

) mg/kg/day (picloram risk assessment p. 

xiv). HCB was registered as a fungicide until banned by EPA over concerns that it may be 

carcinogenic. As a result, EPA has imposed a limit of 100 parts per million (ppm) HCB in 

Tordon®. The manufacturer of Tordon® has set its own manufacturing standard even lower and 

reportedly maintains HCB levels in formulated picloram at 50 ppm or less (i.e., 50 milligrams per 

liter of formulation). Average concentrations of HCB in picloram have been estimated at 8 ppm 

(SERA 2003c). Therefore, HCB comprises only 0.000005 (5 x 10-6

) percent of the Tordon®

formulation, which is then further diluted when the spray solution is prepared in accordance with

the label.

Given the dilution of formulations by water in the final spray solution, estimates of HCB 

exposure from use of picloram or clopyralid-containing products have shown that resulting 

residues in the environment and bystander exposure levels do not exceed current background 

levels. Estimates for worker exposure range from 2 x 10-7 mg/kg/day to 4 x 10-7 mg/kg/day. For 

the public, the upper range of long-term exposure are about 1 x 10-10 mg/kg/day to as much as 2 x 

10-8

, which are below background levels. Longer-term dose estimates for the general public 

exposed to HCB in clopyralid were also below the general background exposure to HCB in the 

environment by factors of about 25,000 to several million (SERA 1999a, 2003c).

The estimates of worker exposure to HCB under normal conditions were expected to be lower 

than the background levels of exposure by factors of about 1,000. Likewise, the exposure 

assessments based on the use of picloram by the Forest Service have been estimated to result in 

long-term predictions for the general public that are below background doses of HCB due to 

environmental contamination by factors of about 1,400 to 7 million (SERA 1999a, 2003c). Thus, 

for commercially sold products which are more dilute than technical grade products, there 

appears to be no basis for asserting that the use of clopyralid or picloram in accordance with the 

label by the Forest Service would result in substantial increases in the general exposure of either 

workers or members of the general public to HCB.

Another concern is potential presence of dioxin in formulations containing chlorinated chemicals. 

Dioxins are a group of chemicals involving 76 different types of related molecules called 

congeners, each having from two to eight chlorine atoms. The toxicity of each of the types of 

dioxin molecules is different. The toxic potency is determined by spatial arrangement of the 

chlorine atoms in a molecule rather than mere presence of chlorine. Of all of the congeners, 

one—TCDD (2,3,7,8-tetrachloro-para-dibenzodioxin)—is the most potent. All 2,4-D products 

manufactured in the U.S. do not contain TCDD and so do not contaminate the environment with 

the dioxin congener of greatest regulatory concern (EPA 2000).

The proprietary nature of herbicide formulations limits the understanding of the risks posed by 

inert ingredients and adjuvant in herbicide formulations. Unless the compound is classified as 

hazardous by the EPA, the manufacturer is not required to disclose its identity. It could be 

suggested that the inert ingredients in these herbicides are not toxic, or their toxicity would be 

reported to the EPA. This would hold true if considerable toxicological testing of inert ingredients 

has been done. That, however, has not been the case. EPA is increasing the testing requirements 

for inert ingredients, but in many cases, the inert ingredients currently in use have not been tested 

234 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

rigorously and their toxicity is not well characterized. That being said, studies on the toxicity of 

technical grade formulations, which often contain the inert ingredients, account for the toxicity of 

the inert ingredients and, as has been reported here, these studies show that the use of herbicides 

by the Forests would not expose workers or the public to levels of concern.

Literature does report considerable information on types of inert ingredients and adjuvants 

present in herbicides proposed for use by the Forests. As noted in SERA (1997a), Velpar L®, the 

trade name for hexazinone, contains 40-45 percent ethanol, an eye irritant and a considerable 

toxin if ingested. It has been reported the most common impurities of technical grade 2,4-D 

include other phenoxyacetic acids, a variety of chlorinated phenols, and possibly low levels of 

nitrosamines in amine salts (Ibrahim et al. 1991). Transline, the commercial formulation of 

clopyralid, contains clopyralid as the monoethanolamine salt and isopropyl alcohol, an approved 

food additive (SERA 1999a). Both Tordon 22 and 22K contain the potassium salt of picloram

(24.4 percent), the remaining consisting of polyglycol 26-2, the DOW name for polyethylene 

glycol, a widely used family of surfactants considered to have low toxicity and frequently used in 

the formulation of ointments and cosmetics (MCCHB 2001).

SERA (2003b) reports that Garlon® formulations of triclopyr contain ethanol and kerosene. 

Technical formulations of imazapyr contain isopropyl alcohol and isopropanolamine salts of 

imazapyr (SERA 1999b, 2004e). Glyphosate has been reported to contain small amounts of 

nitrosamine, and N-nitroglyphosate (SERA 2003a). Roundup®, a formulation of glyphosate, 

contains the surfactant polyoxyethyleneamine (POEA) and 1,4-dioxane, classified by the EPA as 

a probable human carcinogen. However, carcinogenic studies of Roundup® by the EPA have

shown the herbicide to be noncarcinogenic (SERA 2003a). The inert ingredients in Escort®, 

which contains metsulfuron methyl, are confidential. The risk assessment preparers reviewed 

these ingredients as part of the evaluation and report that the inert ingredients in Escort® are not 

classified by EPA as toxic (SERA 2000, 2004c). 

Many herbicide formulations contain dyes. The use of dyes can be beneficial in that they can 

color vegetation, making it less likely for an individual to inadvertently or intentionally consume 

contaminated vegetation. The presence of a dye in herbicide formulations may also make it easier 

for workers to see when they have been contaminated and allow for prompt remedial action.

Dyes may also pose risks to humans and wildlife. The most common dyes used with herbicides 

are Milori blue, Heliogen blue, Lithol rubine, and Sico fast orange (SERA 1997b). Little 

information is available on the toxicity of the majority of dyes used in the industry. There has 

been considerable concern over the carcinogenic potential of less used dyes Rhodamine B and 

Basic Violet 3. Rhodamine B is a colorant used in some commercial herbicide dyes. Basic Violet 

3 is the colorant used in Colorfast Purple. Both have been used with glyphosate. The Forest 

Service completed a risk assessment of Rhodamine B and Basic Violet 3. It estimated the excess 

cancer risk for Rhodamine B, assuming a lifetime of occupational exposure, within the range of 8 

x 10-6 to 8 x 10-8 (SERA 1997b). The excess cancer risk for Basic Violet 3 was estimated to be 

about twice that of Rhodamine B. Both estimates suggest that use of these dyes does not pose an 

unacceptable health risk.

Dyes that are part of the registered formulations (e.g. in Arsenal and Roundup ) have been 

evaluated with the product for risk. Other dyes may be added at the time of application to make 

the area of application more visible, without substantially changing the risk (in fact reducing the 

risk by making the place of application more visible).

Final Environmental Impact Statement – Invasive Plant Control Project 235
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

Surfactants are also commonly used in herbicide formulations. Surfactants are added to 

herbicides to improve herbicide mixing and the absorption or permeation of the herbicide into the 

plant. Like dyes and other inert ingredients, there is often limited information on the types of 

surfactants used and the toxicity of surfactants, especially since the industry considers the 

surfactant to play a key role in the effectiveness of the herbicide formulations. Most knowledge of 

surfactants is kept as proprietary information and not disclosed. This is not always the case. A 

review that attempted to assess the effects of surfactant formulations on the toxicity of glyphosate 

(SERA 1997b) reported that the toxicity of glyphosate alone was about the same as the toxicity of 

the glyphosate and surfactant mixed, and greater than the toxicity of the surfactants alone. A more 

recent risk assessment (SERA 2003a) of glyphosate notes that the surfactant POEA has a 

pronounced effect on the acute lethal potency of glyphosate to aquatic systems. It is assumed that 

given the level of review of the risk assessments, the toxicological studies performed on herbicide 

formulations (which contain the inert ingredients and surfactants) portray the toxicity and risks 

posed by the surfactant to humans and other elements of the environment.

Endocrine Disruption 

The endocrine system includes tissues and hormones that regulate metabolism, growth, and 

sexual development. The Food Quality Protection Act (FQPA) requires that EPA develop tests to 

screen for chemicals with the potential to mimic hormones. Chemicals that do mimic hormones 

and cause biochemical changes in tissues are called endocrine disrupters or hormonally active 

agents (HAAs).

The concern over HAAs is due to the fact that the endocrine system is intimately linked with the 

brain and the immune system. All three systems communicate with one another to affect body 

development and functioning. Adverse effects on this network have been blamed for a variety of 

maladies ranging from cancer to infertility to behavioral problems (Felsot 2001).

Chemicals, other than our own hormones, can interact with components of the endocrine system. 

Scientists have discovered that many kinds of chemicals, including natural food biochemicals as 

well as industrial chemicals and a few pesticides, can mimic the action of the hormones estrogen 

or testosterone. Concern has also been expressed about potential effects on the thyroid hormone 

during early development (Felsot 2001).

Two general types of tests are used to screen chemicals for endocrine disrupting abilities. The 

most widely used tests are in vitro tests. These tests are conducted in a test tube or dish using cells 

and, in some cases, the actual protein receptors, enzymes, and genes involved in the biochemistry 

of the endocrine system. In vitro tests can be used to quickly screen large numbers of chemicals 

for their ability to interact with different biochemical components of the endocrine system (SERA 

2002).

Positive in vitro tests, however, do not necessarily indicate that a substance would actually disrupt 

hormone functioning in a whole organism. In vitro screening tests are properly used to determine 

which chemicals should be subjected to a second type of test, the in vivo or “live animal” test. In 

vivo tests use whole animals that are fed various doses of chemical. In some cases, the chemical 

is injected beneath the skin or directly into the body cavity. Developmental and reproductive 

toxicity studies with live animals over several generations are especially useful for determining if 

a substance adversely affects the endocrine system.

236 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

With one exception—the drug DES (diethylstilbesterol)—all chemicals that have been tested in 

vitro are thousands to millions of times less potent than the natural estrogen hormone (estradiol) 

(Felsot 2001). Also, as exhibited by estradiol, all chemicals tested in vitro appear to show 

definitive threshold effects (i.e., NOELs) for estrogenic activity. No pesticides, food 

biochemicals, or other synthetic chemicals have definitively shown greater and/or different in 

vitro effects at low doses as compared to higher doses. Although our natural hormones function at 

very miniscule levels in the body, endocrine disrupter tests have shown that interactions of 

hormone receptors with natural and synthetic chemicals are still related to dose during exposure. 

Even chemicals capable of interacting with the endocrine system at sufficiently high doses have 

not been found biologically active at low doses (EPA 1997a).

In the in vivo (live animal) studies to date, only a handful of chemicals, including natural food 

biochemicals, a few pesticides, and several industrial chemicals show endocrine disrupting effects 

(Felsot 2001). The in vivo experiments usually involve feeding pregnant rats or mice one or more 

doses of a chemical. With one exception, the drug DES, any effects that have been observed were 

in tests with doses at least thousands of times greater than environmental or dietary 

concentrations.

In virtually all published cases where a series of doses are tested in vivo, endocrine effects did not 

occur below some threshold dose (EPA 1997a). The EPA (1997a) concluded with few exceptions 

(e.g. diethylstilbestrol) a causal relationship between exposure to a specific environmental agent 

and an adverse effect on human health operating via an endocrine disruption mechanism has not 

been established.

The risk assessments have evaluated each herbicide established links to endocrine disruption, 

either directly or in the context of its toxicological studies. The available toxicity studies have not 

reported any histopathologic changes in endocrine tissues. Thus, no evidence was found to 

suggest that it occurs at the exposure anticipated by their use.

Potential for Exposure

While the toxicity of a substance is the first part of the risk assessment, the second equally 

important consideration is the potential for exposure. The dose level that causes an effect in many 

toxicological studies is exponentially greater than what an applicator might be exposed to while 

applying herbicides. The method of exposure to herbicides in animal studies is also different than 

that of a worker or the general public, which also magnifies the chemical effect. In animal 

studies, herbicides are commonly pumped into stomachs (gavage), put directly into food, or 

placed directly on shaved skin. Potential exposure levels to workers and the general public 

associated with use of herbicides on forest lands have been estimated to be at or below EPA RfDs 

(see Table 62). Therefore, dosages would not exceed acute toxicity dose levels when applying 

herbicides on forest lands.

Herbicide applicators and the general public are clothed and do not purposely ingest herbicides 

under the same conditions as animal studies of toxicological significance. Estimates of exposure 

to workers and the general public of herbicides applied to forest lands have been reported under 

various conservative exposure scenarios. The most reasonable interpretation of the risks 

associated with application of most herbicides on forest lands is that, except for accidental 

exposures or extremely atypical and perhaps implausible exposures scenarios (i.e. acute direct 

spray entirely covering a naked child), the use of herbicides on forest lands would not pose an 

identifiable risk to workers or the general public.

Final Environmental Impact Statement – Invasive Plant Control Project 237
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

Exposures under typical exposure scenarios (those following guidelines on the label) would be 

below the RfD, a dose level determined to be safe by EPA over a lifetime of daily exposure.

There are exceptions worth noting that may help identify protective measures that could be 

instituted when applying herbicides.

• USDA Forest Service (SERA 1997) reports that over a range of plausible application 

rates, workers may be exposed to hexazinone at levels that exceed the RfD.

• Likewise, there is reasonable concern that workers applying triclopyr over a prolonged 

period of time in the course of a single season and/or several seasons may be at risk of 

impaired kidney function. (SERA 2003b) 

• SERA (1998a) reports that if 2,4-D were applied directly to fruits and vegetables at 

anticipated application rates, the consumption of vegetables would be undesirable and 

could lead to health effects. These reports also point out that the likelihood of such an 

exposure seems remote when applying on forest lands. Given the concern with the 

consumption of forest vegetation by the local population, this route of exposure is more 

likely than elsewhere in the United States and should be considered in the 

implementation process to avoid these exposures.

• SERA (1998a) also reports that exposure levels for workers involved in ground or aerial 

application of 2,4-D may exceed the RfD slightly, based on central estimates of exposure, 

or substantially, based on upper limits of exposure. They go on to indicate that 2,4-D can 

be applied safely (exposure doses below the RfD) if effective methods are used to protect 

workers and minimize exposure (personal protective equipment).

• SERA (2003c) also reported that there is no evidence that typical exposures to picloram

would lead to a dose level that exceeds the RfD or level of concern with the exception of 

wearing contaminated gloves for 1 hour, which results in estimates of absorbed doses that 

exceed the RfD.

• SERA (2003b) also notes that exposure of workers to formulations of triclopyr over a 

long duration could exceed the level of concern, and so these levels should be avoided.

How herbicides are applied can have a direct impact on the potential for human exposure and 

subsequent adverse health effects. According to risk assessments completed on herbicide usage 

on forest lands, herbicide applicators are at a higher risk than the general public from herbicide 

use. The risk assessments compared risks to workers for all types of application, including aerial, 

backpack, ground-mechanical, and hand applications. Lower risks were estimated for aerial and 

ground-mechanical application as compared to other methods, even though the total amount of 

herbicide applied in a given day was higher (SERA 1995, 1996, 1997a, 1997b, 1998a, 1998b, 

1999a, 1999b, 2000, 2001, 2002, 2003a, 2003b, 2003c, 2004a, 2004b, 2004c, 2004d, 2004e, 

2004f).

Risks associated with backpack and hand application of herbicides were estimated to be the 

highest, due to workers being closer to the nozzle and to the containers from which the herbicides 

were sprayed. Backpack and hand application was also reported to increase the likelihood of a 

worker receiving repeated exposures that may remain on the worker’s skin for an extended time 

period. The EPA, in its re-registration of picloram (EPA 1995), also noted that the highest risk for 

herbicide applicators was for those using the backpack application method, the lowest for aerial 

and ground-boom applicators. Although this is true in general, risk assessments worksheets run 

238 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

on the likely application rates and methods for the two forests, found this exposure reversed for 

2,4-D applicators.

Route of Exposure

Substances tested for acute toxicity are usually administered by pumping a chemical down a tube 

into an animal’s stomach. From this route of exposure, an oral LD50 (lethal dose that kills 50 

percent of a test population, measured in one milligram of herbicide per kilogram of animal 

weight) can be estimated. Exposure during chronic testing usually involves placing the chemical 

in the animal’s food, and then measuring the amount of food eaten during each 24-hour period 

(EPA 1996a,b).

Table 62. Exposure Risk of Herbicides

Herbicide RfD1

(mg/kg/day)

Estimated Exposure 

to Public2

Estimated Exposure to 

Worker2

2,4-D 0.01 Less than RfD Below to slightly above RfD6

Clopyralid 0.5 Less than RfD Less than RfD

Chlorsulfuron 0.05 Less than RfD Less than RfD

Dicamba 0.03 Less than RfD Less than RfD

Glyphosate 0.1 Less than RfD Less than RfD

Hexazinone 0.03/0.055 Less than RfD Below to slightly above RfD4

Imazapic 0.05 Less than RfD Less than RfD

Imazapyr 2.57 Less than RfD Less than RfD

Metsulfuron methyl 0.25 Less than RfD Less than RfD

Sulfometuron methyl 0.027 Less than RfD Less than RfD

Picloram 0.2 Less than RfD Less than RfD3

Triclopyr 0.005 Less than RfD Less than RfD

1 RfD = Reference Dose. A daily dose expressed as milligrams of herbicide per kilogram of body weight = 

mg/kg 

2

 Exposures under typical exposure scenarios. Accidental and extreme exposure scenarios may exceed 

the RfD.

3

 SERA 1998a reports that worker wearing contaminated glove may received an absorbed dose greater 

than the RfD.

4

 SERA 2003c reports that over a range of plausible application rates, workers may be exposed to 

hexazinone at levels that exceed the RfD.

5

 Two RfDs reported.

6

 SERA 1998a reports that worker involved in ground or aerial application of 2,4-D may be exposed to 

levels above the RfD if effective methods to protect workers and minimize exposure are not employed.

7

 Provisional RfD, EPA has not derived RfD for this compound.

Source: Infoventures 1995a-j; EXTOXNET 1996a-h, 2001; EPA 1990a; EPA; 1990b; SERA 1995, 1996, 

1997a, 1997b, 1998a, 1998b, 1999a, 1999b, 2000, 2001, 2002, 2003a, 2003b, 2003c, 2004a, 2004b, 

2004c, 2004d, 2004e, 2004f.

Test substances are also applied to the shaved skin of an animal to estimate a dermal LD50. About 

10 percent of the animal’s body surface is exposed to a chemical covered by a patch for 24 hours. 

In acute exposure studies, whether by oral or dermal routes, animals are monitored for a range of 

adverse responses for 14 days following dosing (EPA 1996c).

Final Environmental Impact Statement – Invasive Plant Control Project 239
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

Required personal protective equipment (PPE) used by workers during pesticide application 

(gloves, waterproof boots, etc.) is designed to reduce exposure to sensitive areas on the body. Use 

of PPE as required by the Forest Service job hazard analysis would protect worker health.

Skin acts as a protective barrier to limit and slow down movement of a chemical into the body. 

Studies of pesticides applied to the skin of humans indicate that for many only about 10 percent 

or less passes into the blood. In contrast, absorption of chemicals from the small intestine is 

quicker and more complete than from the skin (Ross et al. 2000). For this reason, dermal LD50s 

are usually much higher than oral LD50s. A person can tolerate greater doses of a substance 

without becoming sick when exposure is through skin contact rather than through ingestion 

(Hayes 1991).

Test organisms are also administered substances in air to estimate an inhalation LD50. In this case, 

exposure units are expressed as milligrams of test substance per unit of volume (usually a liter of 

air which is equivalent to 0.035 cubic feet). The onset of illness can occur more quickly by 

inhalation exposure than by oral or dermal contact due to rapid entry of the substance into the 

bloodstream. However, studies with pesticide applicators (who receive higher exposures than the 

general public) indicate dermal exposures are greater than inhalation exposures (Ross et al. 2000).

Herbicide Drift

Spray drift is largely a function of droplet particle size, release height, and wind speed (Teske and 

Thistle 1999). Other factors that control drift to a lesser degree include the type of spray nozzle 

used, the angle of the spray nozzle, and the length of the boom. The largest particles, being the 

heaviest, would fall to the ground sooner than smaller sizes upon exiting the sprayer. Medium 

size particles can be carried beyond the sprayer swath (the fan shape spray under a nozzle), but all 

particles would deposit within a short distance of the release point. The physics of sprayers 

dictates that there would always be a small percentage of spray droplets small enough to be 

carried in wind currents to varying distances beyond the target area. Because the small droplets 

are a minor proportion of the total spray volume, their significance beyond the field boundary 

rapidly declines as they are diluted in increasing volumes of air (Felsot 2001).

Drift characteristics differ between pesticides. With herbicides proposed in this analysis, it is not 

critical to coat the entire leaf since some of the products can be absorbed by the plant roots and 

good efficacy can be achieved by larger droplets on leaves to the target plant. Therefore, herbicide 

drift can be intentionally reduced by generating larger droplets without reducing efficacy.

Spray nozzle diameter, pressure, amount of water in the tank mixture, and release height of the 

spray are important controllable determinants of drift potential by virtue of their effect on the 

spectrum of droplet sizes emitted from the nozzles (Felsot 2001; Teske and Thistle 1999). 

Meteorological conditions such as wind speed and direction, air mass stability, temperature and 

humidity and herbicide volatility also affect drift.

Commercial drift reduction agents are available that are designed to reduce drift beyond the 

capabilities of the determinants previously described. These products create larger and more 

cohesive droplets that are less apt to break into smaller particles as they fall through the air. They 

reduce the percentage of smaller, lighter particles that are the size most apt to drift off the 

treatment area.

240 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

Wind speed increases the concentration of drifting droplets leaving the treated area if the wind is 

adverse (blowing away from the release point in the treatment area). If the wind is favorable 

(blowing into the treatment area) drift can be reduced. Numerous studies have shown that over 90 

percent of spray droplets land on the target area, and about 10 percent or less move off target, and 

that the droplets that move off target most typically deposit within 100 feet of the target area 

(Felsot 2001; Yates et al. 1978; Robinson and Fox 1978; Teske and Thistle 1999).

RAHUFS Drift Estimations

The 1992 Risk Assessment for Herbicide Use in Forest Service Regions 1, 2, 3, 4 and 10 and on 

Bonneville Power Administration Sites (USDA FS 1992, referred to as RAHUFS), determined 

spray drift distances downwind of an application site for aerial, backpack, and ground-mechanical 

application equipment. The results of the RAHUFS spray drift analysis indicates “low” health 

risk to the public from ground and aerial (aerial application is not a consideration in this project) 

applied herbicides (USDA FS 1992). “Low risk” was defined in the study as drift from the 

herbicides that presents a less than one in a million systemic, reproductive or cancer risk. Spray 

drift from hand application equipment was found to be negligible.

AGDRIFT/Felsot Drift Estimations

Felsot (2001) used the EPA/USDA FS AGDRIFT model to simulate herbicide sprays for several 

application scenarios, including a truck mounted spray boom set at two heights and a helicopter 

(aerial application is not a consideration in this project) at two heights. These simulations 

included crosswinds blowing at 10 and 6 mph. The model output was an estimated amount 

(percent of that applied) that deposited a defined distance from the edge of a spray swath. A spray 

deposition curve was developed to calculate a dose that a bystander could potentially receive if 

standing within the drift zone of an application. The whole body surface area was assumed 

exposed to a drifting spray (highly conservative), and the bystanders were assumed to be an adult 

weighing 70 kg and a child weighing 10 kg. Absorption of the depositing dose was assumed to be 

10 percent. Calculations were made to determine the percentage of the depositing spray that a 

child could be exposed to on a daily basis over a 70-year lifespan and be within the EPA safety 

guidelines as defined by the RfD (i.e., the “safe dose”).

The study estimated that for aerial application, the equivalent safe deposits corresponded to 

distances from the edge of the spray field of 0, 0, and about 60 feet respectively, for clopyralid, 

picloram, and 2,4-D. For a ground application, the theoretical child would receive a safe dose of 

2,4-D at 27 feet from the sprayed field edge.

Other Means of Exposure

The risk assessments note that any number of exposure scenarios can be constructed for the 

general public, depending on various assumptions regarding application rates, dispersion, canopy 

interception, and human activity. Several highly conservative scenarios are developed for use in 

the risk assessments (SERA 1995, 1996, 1997a, 1997b, 1998a, 1998b, 1999a, 1999b, 2000, 2001, 

2002, 2003a, 2003b, 2003c, 2004a, 2004b, 2004c, 2004d, 2004e, 2004f).

The two types of exposure scenarios developed for the general public include acute exposure and 

longer-term or chronic exposure. All of the acute exposure scenarios are primarily accidental. 

They assume that an individual is exposed to the compound either during or shortly after its 

application. Specific scenarios are developed for direct spray, dermal contact with contaminated 

vegetation, as well as the consumption of contaminated fruit, water, and fish.

Final Environmental Impact Statement – Invasive Plant Control Project 241
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

Most of these scenarios should be regarded as extreme, some to the point of limited plausibility. 

The longer-term or chronic exposure scenarios parallel the acute exposure scenarios for the 

consumption of contaminated fruit, water, and fish but are based on estimated levels of exposure 

for longer periods after application. Most acute, accidental exposure scenarios for members of the 

general public are less than or similar to the general exposure scenarios in workers.

The major exception is the scenario for an accidental spill of 200 gallons of a field solution into a 

small pond. This leads to modeled estimates of exposure in the range of 0.3 to about 4 mg/kg/day. 

This is an extraordinarily extreme and conservative scenario that is used in all Forest Service risk 

assessments. Mitigation measures are designed to insure that the possibility of this scenario 

occurring is extremely low.

Most longer term estimates of exposure for members of the general public are much lower than 

exposure estimates for workers. The one exception involves the longer term consumption of 

contaminated fruit (see risk assessment for glyphosate). In all the scenarios for herbicides 

considered in this project, the risk to health are below the levels of concern identified for each 

herbicide (SERA 1995, 1996, 1997a, 1997b, 1998a, 1998b, 1999a, 1999b, 2000, 2001, 2002, 

2003a, 2003b, 2003c, 2004a, 2004b, 2004c, 2004d, 2004e, 2004f).

Length of Exposure

The magnitude of a dose that is hazardous to health depends on whether a single dose is given all 

at once (acute exposure); multiple doses are given over longer periods (chronic exposure); or, 

regularly repeated doses or exposures over periods ranging from several days to months (subchronic). The EPA develops Reference Doses (RfDs), which are an estimate of a daily dose over a 

70-year lifespan that a human can receive without an appreciable risk of deleterious effects (EPA 

1989). RfDs include a “safety factor” where the No Observable Effect Level (NOEL) is divided 

by a factor, usually 100, to account for uncertainty and hypersensitive individuals. The 100 value 

is derived by including a safety margin of 10 for extrapolating study results from mammals to 

humans, and an additional safety factor of 10 for variation in population response to a particular 

compound.

The RfD is a conservative toxicological threshold in relation to this analysis because it assumes 

daily exposure over a 70-year lifespan, and because the RfD is calculated from the No-ObservedEffect-Level (NOEL), assuming humans are 100 times more sensitive than animals (uncertainty 

factor of 100). Actual environmental exposures for herbicide treatments in this project would 

typically be a few days each year for substantially less than 70 years.

Potential doses to workers or the public from application of herbicides would be transitory. 

Lifetime RfDs are used here as a convenient and conservative comparison for determining 

significance of human doses. Lifetime RfD values are based on daily feeding studies, whereas 

workers and the general public would not be exposed daily over a lifetime. Maximum duration of 

exposure for workers on a yearly basis was estimated in the range of 10 to 40 days for 

commercial applicators (EPA 1995).

242 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

Uncertainty 

With the exception of accidental exposures or exposures under very conservative and somewhat 

implausible exposure scenarios, workers and the general public should not be exposed to a 

herbicide at concentrations that result in adverse health effects, either by short-term acute toxic 

effects or long-term exposure to low dosage levels.

This conclusion is predicated on Forest Service employees wearing appropriate personal 

protection, applying herbicides in accordance with the label, and implementing the job hazard 

analysis program to be used on this project. By doing so, possible exposure by contact or through 

drift would result in a potential dose below that determined to be safe by the EPA over a lifetime 

of daily exposure. It is also predicated on the findings, backed by toxicological studies, that a 

person can be exposed to some amount of a contaminant and not have an adverse effect (i.e. the 

dose determines the effect). 

All of the herbicides proposed for use by the Forests must be registered for use by the EPA and 

the New Mexico Department of Agriculture. Registration of these herbicides and Federal 

regulations adopted to protect workers and the general public has required more scientific 

information and justification for use of herbicides.

Nevertheless, there are many reports in the scientific literature and sections of this report that 

document associations between herbicide exposure and alterations of the immune system, 

autoimmune disorders, and increases in the probability of carcinogenesis. MCCHB (2001), Citron 

(1995), EPA (1995), Glover-Kerkvliet (1995) are just a few references that provide information 

on such effects. The body of literature on herbicide effects raises concerns about additive and 

synergistic effects of exposure to more than one herbicide, unstudied or unknown consequences 

of low-level chronic exposures, toxicity of inert ingredients, byproducts or contaminants of 

herbicides, and uncertainties about the health effects of sensitive populations. There is also the 

realization that it is difficult, if not impossible, for government or any scientific agency to fully 

evaluate a chemical and all the potential combinations of them to ensure that there would not be 

an adverse effect.

Risk assessments conducted by the Forest Service for each of the proposed herbicide 

formulations to be used has taken this uncertainty into account in order to evaluate theses 

potential effects. Studies that show possible links to serious health effects are assessed in the 

context the other information available to reach conclusions. As noted, even when these 

uncertainties are factored in, the risk of harm caused by use of the herbicides remains low as long 

as they are properly handled and applied (SERA 1995, 1996, 1997a, 1997b, 1998a, 1998b, 1999a, 

1999b, 2000, 2001, 2002, 2003a, 2003b, 2003c, 2004a, 2004b, 2004c, 2004d, 2004e, 2004f).

Use of herbicides presents some level of risk to workers and the general public. Yet, the weight of 

the scientific evidence presented in the risk assessments indicates that there is no route of 

exposure or exposure scenario suggesting that the general public will be at risk from longer-term 

exposure to herbicides. There are too many variables (receptor sensitivity, dose received, use of 

personal protection, etc.) for accurate predictions of the exact effects of herbicide use on every 

person who may be exposed to the herbicide as it is used, but the effects of exposure are known in 

general and the risks of these effects occurring for a low exposure are also known.

The risk of adverse health effects can, therefore, be managed as follows:

Final Environmental Impact Statement – Invasive Plant Control Project 243
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

• Through a process of continual review of toxicological data on herbicides, the EPA, using 

very conservative assumptions, has determined a dose they believe would not result in an 

adverse health effect for herbicides proposed for use on this project.

• Risk assessments have been completed to determine the estimated dose a worker or 

person of the general public might be exposed to under varying exposure scenarios.

• A comparison of EPA established safe doses and estimated exposures concludes that the 

estimated dose that a worker or person of the general public may be exposed to through 

use of a herbicide on this project would be below that determined to be safe by the EPA 

for a lifetime of daily exposure.

Wildlife Risk Assessment

Some studies on effects of herbicides to terrestrial and aquatic organisms were discussed in the 

previous section with respect to specific herbicides. Results from other risk assessment studies 

add to those effects described. Risk assessment studies indicate the potential for certain herbicides 

to cause a number of impacts including impaired kidney function, reproductive problems, eye 

irritation, and nontarget plant impacts. Establishing effects thresholds is usually performed on 

rabbits and rats, and then potential impacts on various other species are inferred. The problem 

with this type of analysis is that specific thresholds for a particular species are never truly 

quantified. Therefore, any data compiled that states exact toxicities of a given herbicide on a 

group of animals must be weighed in relation to the physiological similarities of the species in 

question and the species used in the testing.

In addition, the concentrations used in testing are typically at least 50 percent chemical. When 

actually implementing an herbicide application plan, concentrations come nowhere near these 

levels. Formulations of the proposed herbicides would likely be anywhere from tens to thousands 

of times below those resulting in impacts on animals and, often, concentrations would be similar 

to those experienced as background levels.

To determine the degree of impact on wildlife from herbicides, several factors need to be 

considered. There are twelve herbicides being considered for use. Each may have a different 

impact on different species or groups of species dependent upon:

• The proposed application rate of herbicide applied to an area;

• The persistence of the herbicide in the environment; and,

• The geographic extent of the proposed application.

Although there has been some concern regarding the synergistic effects associated with 

interactions between various chemicals (including herbicides), no evidence of synergistic effects 

with other chemicals has been demonstrated for any of these herbicides. No chronic effects 

analyses on terrestrial animals had been performed for glyphosate or triclopyr (Infoventures 

1995a and b), nor have any recent studies involving chronic toxicity to wildlife been conducted.

Various herbicide formulations have the potential to cause eye and skin irritation in the context of 

splash or spill scenario. The potential for eye and skin irritation to wildlife from normal 

application, while still possible, is expected to be less than that described because of the reduced 

concentration of herbicide in a spray scenario when compared to a spill or splash scenario. 

Mitigation measures aimed at controlling spills are found in Chapter 2.

244 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

A risk analysis of various herbicides to terrestrial wildlife species prepared for the Forest Service 

(USDA FS 1992) considered toxicity, potential dosage through various routes (ingestion, 

inhalation, dermal), and length of exposure to a number of vertebrate wildlife species and 

concluded that potential risks for most wildlife species are low for most herbicides and 

surfactants using recommended application rates. Risk was moderate to high for only a few 

species and a few herbicides under extreme situations that would not occur under typical 

application scenarios. Most of the proposed herbicides are either nontoxic or of low toxicity to 

birds, mammals, and insects. None of those tested have been shown to cause cancer, birth defects, 

genetic defects, or problems with fertility or reproduction. These conclusions have been examined 

in more recent risk assessments and found to continue to be reasonable conclusions to make 

based on the most recent information available (SERA 1995, 1996, 1997a, 1997b, 1998a, 1998b, 

1999a, 1999b, 2000, 2001, 2002, 2003a, 2003b, 2003c, 2004a, 2004b, 2004c, 2004d, 2004e, 

2004f). These and other sources indicate no evidence of synergistic effects or hormone disruption 

from any of these chemicals (EXTOXNET 1996a-h, SERA 2002).

Considering that the dosages after dilution with water are far below (often thousands of times 

below) concentrations of these chemicals that have demonstrated any level of acute or chronic 

toxicity in tests performed, it is very unlikely that any birds, mammals, or insects would be 

affected by herbicide use following recommended application rate procedures (Infoventures 

1995a-k). 

Triclopyr, while considered a moderately toxic compound does not pose a carcinogenic, 

mutagenic, reproductive, developmental risk to animals or humans at doses anticipated for this 

project (SERA 2003b).

Final Environmental Impact Statement – Invasive Plant Control Project 245
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

Table 63. Relative Risk of Each Herbicide Herbicide Worker Risk Public Risk Risk of Carcinogenicity

Risk to Plants, DirectRick to Plants, Drift/runoffAquatic Plants RiskAnimals Direct RiskAquatic Animal RiskNotes

2, 4-D ○

○

○

●

●

○

○

○

○

●

NA

○

○

○

●

●

○

○

○

○

●

○

○

○

○

●

○

○

○

●

●

●

●

●

●

●

Clopyalid ○

○

○

○

●

○

○

○

○

●

1:106

○

○

●

●

●

○

○

●

●

●

○

○

○

○

●

○

○

○

○

●

○

○

○

○

●

Cancer risk is 

less than 1 in a 

million

Chlorsulfuraon ○

○

○

○

●

○

○

○

○

●

NA

○

○

●

●

●

○

●

●

●

●

○

○

●

●

●

○

○

○

○

●

○

○

○

○

●

Dicamba ○

○

○

●

●

○

○

○

○

●

NA

○

○

●

●

●

○

●

●

●

●

○

○

○

●

●

○

○

○

○

●

○

○

○

○

●

Glyposate ○

○

○

○

○

○

○

○

○

●

NA

○

●

●

●

●

○

○

●

●

●

○

○

○

○

●

○

○

○

○

●

○

○

○

●

●

w/o POEA

(Rodeo)

Glyposate ○

○

○

○

○

○

○

○

○

●

NA

○

●

●

●

●

○

○

●

●

●

○

○

○

○

●

○

○

○

○

●

○

●

●

●

●

w/ POEA

(Roundup)

Hexazinone ○

○

●

●

●

○

○

○

○

●

NA

○

●

●

●

●

○

○

●

●

●

○

○

●

●

●

○

○

○

○

●

○

○

○

○

●

Key:

○

○

○

○

○

The greater the number of dark dots, the higher the relative risk for that 

area of concern.

246 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

Table 63. (continued) Relative Risk of Each Herbicide Herbicide Worker Risk Public Risk Risk of Carcinogenicity Risk to Plants, 

DirectRick to Plants, Drift/runoffAquatic Plants RiskAnimals Direct RiskAquatic Animal RiskNotes

Imazapic ○

○

○

○

○

○

○

○

○

●

NA

○

●

●

●

●

○

●

●

●

●

○

○

○

●

●

○

○

○

○

●

○

○

○

○

●

Imazapyr ○

○

○

○

○

○

○

○

○

○

NA

○

●

●

●

●

○

●

●

●

●

○

○

○

●

●

○

○

○

○

●

○

○

○

○

●

Mtsulfuron 

methyl

○

○

○

○

○

○

○

○

○

NA

○

●

●

●

●

○

●

●

●

●

○

○

○

●

●

○

○

○

○

●

○

○

○

○

●

Sulfometuron 

methyl

○

○

○

●

●

○

○

○

●

●

NA

○

●

●

●

●

○

●

●

●

●

○

○

●

●

●

○

○

●

●

●

○

○

○

○

●

Picloram ○

○

○

○

○

○

○

○

○

●

1:106

○

●

●

●

●

○

●

●

●

●

●

●

●

●

●

○

○

●

●

●

○

●

●

●

●

Cancern risk is 

less than 1 in a 

million

Triclopyr TEA ○

○

○

●

●

○

○

○

●

●

NA

○

○

○

○

○

○

○

●

●

●

○

●

●

●

●

○

●

●

●

●

○

●

●

●

●

Triclopyr BEE ○

○

○

●

●

○

○

○

●

●

NA

○

○

○

○

○

○

●

●

●

●

○

●

●

●

●

○

●

●

●

●

○

●

●

●

●

High rate (10 

lb/ac)

Key:

○

○

○

○

○

The greater the number of dark dots, the higher the relative risk for that 

area of concern.

Final Environmental Impact Statement – Invasive Plant Control Project 247
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

Table 64. Effects of Each Herbicide

Herbicide Carcinogen 

(Cancer)

Teratogen 

(Birth 

Defects)

Mutagen

(Genetic 

Damage)

Reproductive 

Inhibitor Skin Irritant EyeIrritant

BioAccumulateToxicity to 

Birds

Toxicity to 

Bees

Toxicity to 

Mammals Target Plants

Picloram No No No No Mild Moderate No Almost 

nontoxic

Relatively 

nontoxic

Low Broadleaf plants, brush, 

conifers and broadleaf 

trees

2,4-D Not tumor 

causing; 

kidney 

damage at low 

doses

No No No Mild to 

Moderate

Corrosive No Non to 

moderate 

based on 

form

Relatively 

nontoxic

Moderate Broadleaf weeds, 

grasses and other 

monocots, woody plants, 

aquatic weeds, and nonflowering plants

Dicamba No No No Little to No Mild Corrosive No Nontoxic Nontoxic Slight Broadleaf weeds, brush 

and vines

Metsulfuron 

methyl

No No No No Moderate Moderate No Nontoxic Nontoxic Nontoxic Brush and woody plants, 

annual and perennial 

broadleaf weeds, and 

annual grassy weeds

Glyphosate Not enough 

information to 

determine

No No No Mild Mild to 

Moderate

No Nontoxic Nontoxic Nontoxic Grasses, herbaceous 

plants, brush, some 

broadleaf trees and 

shrubs, and some 

conifers.

Hexazinone No No No No Mild Corrosive No Nontoxic Relatively 

nontoxic

Nontoxic Broadleaf weeds, 

grasses, and woody 

plants

Sulfometuron 

methyl

No No No Observed at 

maternally 

toxic doses

Mild Moderate No Slight No Info 

Available

Slight Grasses and broadleaf 

weeds

Triclopyr No No Not enough 

information 

to 

determine

No Mild to 

Moderate

Mild to 

Moderate

No Very Low Nontoxic Slight Woody plants and 

broadleaf weeds

Clopyralid No No No No Mild Moderate No Low Nontoxic Low Brush and weed species, 

broadleaf plants, thistle

Chlorsulfuron No No No No Mild Moderate No Nontoxic Nontoxic Nontoxic Broadleaf weeds and 

some annual grass 

weeds

Imazapic No No No No Nonirritating Nonirritating No Nontoxic Nontoxic Nontoxic Annual and perennial 

broadleaves and grasses

Imazapyr Not enough 

information to 

determine

No No Not enough 

information to 

determine

Moderate Moderate No Nontoxic Low Nontoxic Grass and broadleaved 

weeds, brush, vines, 

many deciduous trees

248 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

Aquatic Risk Assessments 

One of the primary means by which toxicological effects of specific contaminants on aquatic life 

are determined includes use of standardized laboratory bioassays. Sutter (1995) identified several 

shortcomings of bioassays; in particular, their applicability to expected field conditions. However, 

bioassays remain a useful tool in quantifying toxicological effects of specific contaminants on 

aquatic life in a consistent, relatively reproducible manner (Munn and Gilliom 2001). The way 

the bioassay information is used, is to develop a “threshold level” at which it is unlikely a species 

will suffer any effects—this is called the “No Observable Effect Level” or NOEL.

The maximum acceptable toxicant concentration (MATC) (Mayer and Ellersieck 1986) protocol 

was developed by the U.S. Fish and Wildlife Service to estimate the chemical concentrations in 

aquatic habitats. The Environmental Protection Agency (EPA) uses a safety factor of 1/20 the 

LC50, which they believe should not result in an unacceptable risk to endangered aquatic species 

(USFS 2001c). Therefore, this safety factor has been selected for delivery modeling.

Other important elements that come into play during a risk assessment include: how much 

chemical can reach the water; if it reaches the water, what would the concentration of the 

chemical be and how long would that concentration be maintained? There have been various 

approaches used to gauge this type of risk. Some models focus on the worst-case scenario for 

how much chemical can get into a water body.

In 2001, the Nez Perce National Forest prepared a biological assessment (USFS 2001b) for 

herbicide treatment of invasive weeds. As part of the aquatic analysis for herbicide application, a 

risk quotient was calculated for each herbicide proposed for use. This risk quotient was calculated 

from a no observable effect level (NOEL) divided by an expected environmental concentration 

(EEC). The risk quotient provides a reference from which a worst-case scenario can be viewed. If 

the risk quotient is greater than 10, the level of concern is categorized as “low.” If the risk 

quotient is between 1 and 10, the level of concern is “moderate.” If the risk quotient is less than 1, 

then the level of concern is “high.” [Note: this is similar to that used in the risk assessments, but 

reverses the numerator and denominator in the equation and so shows an inverse relationship to 

that shown in the risk assessments.].

The level of concern (risk) analysis is based on direct application of the active ingredient of a 

chemical product to a pond containing 1-acre-foot of water. This illustrates an extreme case, 

which should not occur during implementation. The risk of a direct application is mitigated by 

selecting appropriate application techniques (hand application vs. aerial spray), applying buffers 

adjacent to water, taking into account such factors as chemical volatility, wind speed and 

direction, temperature, precipitation, ground slope or use of chemicals that are approved for direct 

application to water. In some cases it may be appropriate to limit how much chemical is applied 

in any given drainage if it is a high risk chemical for aquatic species. Table 60 shows the risk 

analysis using the risk quotient method as identified in the Nez Perce National Forest biological 

assessment (USFS 2001b). Risk can be assessed based on the level of chemical considered to be 

reaching a stream as well as incorporating the chemical’s toxicological effects. Using the 

approach described for the Nez Perce National Forest to assess the high risk chemicals, the 

Carson National Forest and Santa Fe National Forest identified Picloram as falling into this 

category.

Final Environmental Impact Statement – Invasive Plant Control Project 249
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

Table 65. Level of Concern for Chemical Use Using the Risk Quotient Method

Chemical 1/20 Of LC50 

(ppm)1 EEC2 (ppm) Risk 

Quotient

Level of 

Concern

Chlorsulfuron (Telar) 12.5 0.0690 181.27 Low

Clopyralid 5.2 0.1398 37.21 Low

2,4-D 12.5 0.3677 33.99 Low

Dicamba (Banvel) 50 0.2758 181.27 Low

Dicamba (Vanquish) 6.75 0.2758 24.47 Low

Triclopyr (Garlon) 26.1 1.8389 14.19 Low

Hexazinone (Velpar) 16 1.4711 10.88 Low

Metsulfuron methyl 7.5 0.0114 657.84 Low

Imazapic 5 0.0919 539.40 Low

Imazapyr 5 0.0919 539.40 Low

Picloram 0.075 0.0919 0.82 High

Triclopyr (Redeem) 26.1 1.2872 20.28 Low

Sulfometuron (Oust) 0.625 0.0172 36.34 Low

Glyphosate 4.3 1.4711 2.92 Moderate

Note: 1 LC50 = Lethal Concentration where 50% mortality occurs ; 

2 EEC = expected environmental concentration; ppm = parts per million.

Although there remains considerable uncertainty relative to potential herbicide effects, aquatic 

organisms, including eggs and larvae of amphibians, could be directly exposed to herbicide 

formulations in water as well and could be impacted. The degree of exposure, however, would be 

extremely low based on recommended application rates already far below levels where impacts 

begin to surface. In addition, further dilution of the formulation by the water it enters would result 

in concentrations several hundred or thousand times below scientifically established tolerance 

levels. Mitigation measures, such as avoiding boom spraying of herbicides near open water and 

other restrictions on use (no direct application of herbicide to water, restrictions on herbicide 

loading and handling), means that the likelihood of aquatic impacts caused by herbicide use are 

not likely to be detectible.

250 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

Specific Herbicide 

Characteristics and Environmental Effects

2,4-D

2,4-D is used to control broadleaf weeds, woody plants, aquatic weeds, and non-flowering plants 

(Infoventures, 1995b). 2,4-D is a short-residual herbicide that remains active for 10 to 14 days. It 

can kill or injure many broadleaf plants depending on site conditions, plant growth stage, and 

herbicide application rate. However, broadleaf plants that germinate from seed, or that begin to 

grow more than 10 days following application should remain unaffected. On woody species, 

vegetative growth may be killed, but plants generally recover in a year or less (USDA FS 2003c).

The half-life of 2,4-D in the environment is relatively short, averaging 10 days in soils and less 

than 10 days in water and dependent upon other factors (e.g., temperature, soil condition) (Tu et 

al. 2001). In the environment, most formulations are degraded to the anionic form, which is 

water-soluble and has the potential to be highly mobile. The formulation proposed for use in this 

project is the amine salt. It may remain active for up to 6 weeks, though it ultimately metabolizes 

into harmless products (Infoventures 1995b).

The toxicity of 2,4-D varies by the form of the chemical and affected organism. Ester 

formulations are toxic to fish and aquatic invertebrates, but salt formulations are registered for 

use against aquatic weeds (Tu et al. 2001). Ester formulations have LC50 values (24 and 96 hour) 

for several species of fish (flathead minnows, bluegills, and rainbow trout) that ranged between 

260 and 358 mg/l, while the same values for amine salt formulations ranged from 250 to greater 

than 600 mg/l (SERA 1998a). The ester LC50 (24 hour) for Daphnia Magna was 100 mg/l and 

between 25 and 36.5 mg/l (48 hour), while an amine salt formulation had an LC50 of 406 mg/l 

(24 hour).

In birds, 2,4-D ranges from being virtually nontoxic in its butyl ester form to moderately toxic as 

an amine salt. Mammals are moderately sensitive to exposure. It is relatively nontoxic to bees. 

Most LD50 values for 2,4-D range from 300-1,000 mg/kg, though sensitivity varies greatly 

between animal groups and chemical form (Infoventures 1995b, SERA 1998a, Ecobichon 2001, 

Tu et al. 2001).

The World Health Organization (1984) concluded that 2,4-D does not accumulate or persist in the 

environment. The primary degradation mechanism is microbial metabolism, but mineralization 

and possibly light exposure may also play a role. Degradation rates are determined by the 

microbial population, environmental pH, soil moisture and temperature (Tu et al. 2001). The type 

of 2,4-D applied does not significantly affect the rate of degradation (SERA 1999a).

2,4-D will change form and function with changes in water pH (SERA 1999a). In alkaline waters 

(pH>7), 2,4-D takes the ionized (negatively charged) form that is water-soluble and remains in 

the water column. Theoretically, in water of lower pH, 2,4-D will remain in a neutral molecular 

form, increasing its potential for adsorption to organic particles in water and increasing its 

persistence (SERA 1999a).

2,4-D is considered to be moderately toxic to animals, although LD50 levels vary greatly between 

formulations and animal species (Ibrahim et al. 1991). 2,4-D can accumulate in organisms. 

Numerous studies on fish, amphibians and macroinvertebrates are summarized by the Syracuse 

Final Environmental Impact Statement – Invasive Plant Control Project 251
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

Environmental Research Institute (SERA 1999a). LC50s (96 hour) for bluegill sunfish and 

rainbow trout are 263 and 377 mg/L, respectively. One researcher studied bioaccumulation of 2,4-

D in carp and tilapia and found that accumulation of up to 18 times the ambient concentration 

occurred within 2 days of exposure. 2,4-D has been found in oysters and clams in concentrations 

up to 3.8 ppm and persisted for up to 2 months (Tu et al 2001). 2,4-D can accumulate in fish 

exposed to concentrations as low as 0.05 ppm (SERA 1998a) and concentrations of 1.5 ppm can 

kill the eggs of fathead minnows in 48 hours (Tu et al 2001). Contrary to this, older studies found 

that concentrations of 2,4-D up to 50 ppm had no visible effect on common frog tadpoles (Rana 

temporaria) after treatment for 48 hours (SERA 1998a).

Studies in rats suggested 2,4-D was not cancer causing, though liver damage was seen at 

relatively low dosages. Pregnant rats showed no evidence of birth defects, though fetuses showed 

evidence of toxic effects. No effect on reproduction or fertility has been demonstrated in rats and 

2,4-D did not cause genetic defects in most studies (Infoventures 1995b). While an association 

between 2,4-D exposure and canine malignant lymphoma has been reported (SERA 1998a), a 

causal mechanism was not identified. In a recent review of 2,4-D epidemiology and toxicology, 

Garabrant and Philbert (2002) concluded that the evidence that 2,4-D might be carcinogenic was 

“scant.” 2,4-D does not bioaccumulate in wildlife (SERA 1998a). Risk to browsing wildlife, 

however, appears to be low, as do risks to forging raptors. A study in Oregon after aerial spraying 

found concentrations on forest browse plants to be below those able to cause effects in mammals 

(Tu et al. 2001). Acid and salt formulations of 2,4-D have been shown in laboratory studies on 

rabbits to be eye irritants (Infoventures 1995k). In humans, 2,4-D has been found to rapidly 

distribute within the body with the greatest concentrations appearing in the kidneys and liver (Tu 

et al. 2001), which may also be the case for wildlife species.

The risk assessment for 2,4-D concludes that unless applied with effective protection methods, 

exposure levels for workers involved in ground or aerial application may exceed the reference 

dose and may result in covert (not immediately recognized) toxic effects. This underscores the 

importance of using personal protective equipment (PPE) and following appropriate handling 

methods. The risk of the general public experiencing any adverse effects is extremely low under 

normal conditions of exposure. Accidental levels of exposure to the public could result in 

equivalent exposure as workers. Consumption of contaminated vegetation over a period of 

several months may result in adverse health effects, but the likelihood of this occurring is remote 

since it would require repeated use of contaminated vegetation collected immediately after the 

application of herbicides in order for exposure to reach thus dose levels. This also assumes no 

breakdown of the 2,4-D after application and collection of the vegetation.

If plants are accidentally sprayed at the application rates used by the Forest Service, they are 

likely to be damaged, particularly in the upper ranges of anticipated application rates. This kind 

of exposure may be regarded as an accidental scenario, which is relatively easy to control with 

proper management of application. The extent and duration of damage will depend on the time of 

application and plant species. The extent of drift will depend on conditions during application, 

such as wind speed, wind direction, topography, the distance from the ground at which the 

herbicide is applied, and the droplet size of the herbicide spray. Nonetheless, as detailed in section 

4.2.2 of the risk assessment, off-site deposition at 100 feet (-30 m) downwind is likely to be about 

0.05 of the nominal application rate. Thus, at the high range of application contemplated by the 

Forest Service, 2 lbs a.e./acre, the deposition at 30 m would be -0.1 lb a.e./acre. This application 

is below the application rate recommended for the control of even very sensitive broadleaf 

species.

252 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

Except for accidental exposure scenarios, there is relatively little indication that 2,4-D 

applications are likely to cause any adverse effects in terrestrial animals. The direct spray scenario 

for the bee is less ambiguous: some populations of bees subject to a direct spray could evidence 

substantial mortality. Neither of the drinking water scenarios lead to hazard quotients that reach a 

level of concern. For the longer-term drinking water scenario, the anticipated exposures are far 

below a level of concern. As in the characterization of risk for potential human health effects, 

both the acute and longer term exposures of a small mammal to vegetation contaminated with 

2,4-D are of some concern. Nonetheless, if contaminated vegetation is the sole diet of the animal, 

some subclinical toxic effects could occur. No frank signs of toxicity, however, are likely. 

Although the data on avian species are not as extensive as those for mammals, acute toxicity 

studies in birds suggest that avian species are somewhat less sensitive than mammals. In addition, 

the available studies on the effects of 2,4-D on avian eggs suggest that no effects would be 

anticipated from a direct spray of avian eggs at application rates of up to 10 lb/acre, a rate that is 

far in excess of those anticipated by the Forest Service. The direct application of Aqua-Kleen to 

bodies of water for the control of undesirable vegetation may lead to concentrations where 

mortality might be expected in some sensitive fish or invertebrate species, particularly over the 

first day or two when a substantial proportion of 2,4-D could exist in the ester form. On the other 

hand, at least some fish species will avoid 2,4-D in water at subtoxic levels. Thus, the presence of 

toxic levels of 2,4-D in treated bodies of water would not necessarily lead to fish kills or other 

overt toxic effects. This method is not proposed for the Invasive Plant Control Project.

Chlorsulfuron

Chlorsulfuron is used for control of broadleaf weeds and some grasses. It is absorbed through the 

roots and foliage of plants. It inhibits susceptible plants from producing an essential amino acid, 

which inhibits cell division in the root tips and shoots. In nonsusceptible plants it is broken down 

to inactive products. Chlorsulfuron is generally used to combat thistles—including bull, Scotch, 

and musk thistles—in rangeland and noncrop areas. It is particularly useful in maintaining native 

perennial grasses (Sheley et al. 1999).

Chlorsulfuron is generally active in soil, and has a greater affinity to adsorb to soils having a 

higher organic content. It tends to leach in permeable soils, with leaching being reduced in soils 

having a pH of less than 6. Chlorsulfuron is degraded by soil microbes. The half-life has been 

reported from 1 to 3 months based on soil acidity (Infoventures 1995f). It does not easily 

evaporate and is relatively soluble in water.

Chlorsulfuron has a low order of acute toxicity; with oral LD50 levels in the male and female rat, 

bobwhite quail, and mallard duck reported to be >5,000 mg/kg (Infoventures 1995c). The acute 

dermal LD50 has been reported to be >3,400 mg/kg. It is considered to be a mild irritant to the 

skin and a moderate eye irritant. Chlorsulfuron is not considered to be a reproductive, mutagenic, 

or carcinogenic compound. Infoventures (1995f) reports that rats fed up to 5,000 ppm per day for 

up to 2 years did not show evidence of carcinogenicity. Teratology studies of rats and rabbits 

showed no evidence of developmental effects. A 3-generation study in rats show slight decreased 

fertility at the highest does of 2,500 ppm, but no decrease in fertility was observed at doses up to 

500 ppm. In their mutagenic tests, Chlorsulfuron did not cause genetic damage.

Chlorsulfuron is persistent in soils with a half-life of 1 to 3 months based on soil acidity. Low soil 

pH accelerates the hydrolysis of the chemical into nonherbicidal compounds.

Final Environmental Impact Statement – Invasive Plant Control Project 253
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

Higher soil temperatures, moisture and levels of oxygen increase the rate of hydrolysis. After 

hydrolysis, microbial metabolism breaks down the compound further. Photodegradation is minor. 

The chemical leaches in permeable soils but leaches less in soils with a pH of below 6 

(Infoventures, 1995f). The Glean® Weed Killer product is intended for use in soils with a pH of 

7.5 or less (PMEP 2001b). Because of its persistence and high mobility, chlorsulfuron has the 

potential to enter surface waters from runoff. However, due to its very low application rate of 

0.25 to 3 ounces formulated product per acre, it has little potential to enter ground water.

The technical grade of chlorsulfuron is practically nontoxic to fish and aquatic invertebrates. The 

LC50 (96 hr) for rainbow trout is 250 mg/L, for bluegill sunfish and fathead minnows is 300 

mg/L and for channel catfish is 40 mg/L (PMEP, 2001b). The 48 hr LC50 for Daphnia Magna is 

370 mg/L (PMEP, 2001b). There is no potential for bioaccumulation (USDOE, 2000).

For both workers and members of the general public, typical exposures to chlorsulfuron do not 

lead to estimated doses that exceed a level of concern. For workers, the upper range of is 

somewhat above the level of concern for ground broadcast applications at the highest application 

rate. For members of the general public, the upper limits are below a level of concern except for 

the accidental spill of a large amount of chlorsulfuron into a very small pond. Even this exposure 

scenario results in only a short-duration exposure above the acute reference dose and is not likely 

to be toxicologically significant, because of the short duration of exposure relative to those 

considered in the derivation of the reference dose.

Chlorsulfuron is an effective and potent herbicide and adverse effects on some nontarget plant 

species, both terrestrial and aquatic, are plausible unless measures are taken to limit exposure. For 

terrestrial plants, the dominant factor in the risk characterization is the potency of chlorsulfuron 

relative to the application rate, which is many times greater than the established level of no 

observable adverse effects to vegetation vigor. This potency indicates damage to nontarget plant 

species after ground broadcast applications could extend to distances of greater than 900 feet 

from the application site. This risk characterization applies only to ground broadcast applications. 

When used in directed foliar applications (i.e., backpack), offsite drift could be reduced 

substantially but the extent of this reduction cannot be quantified. The offsite movement of 

chlorsulfuron via runoff could be substantial under conditions that favor runoff, including rainfall 

at levels (15inches) found typically across the Carson and Santa Fe National Forests. In very arid 

regions in which runoff might not be substantial, wind erosion could result in damage to 

nontarget plant species. The probability of damage to aquatic plants, particularly macrophytes, is 

less substantial but still noteworthy. At the typical application rate, peak concentrations of 

chlorsulfuron in water could result in damage to aquatic macrophytes based on a growth 

inhibition. Thus, if chlorsulfuron is applied in areas where transport to water containing aquatic 

macrophytes is likely, it would be plausible that detectable damage could be observed. Aquatic 

algae do not appear to be as sensitive.

There is no clear basis for suggesting that effects on terrestrial or aquatic animals are likely or 

would be substantial. Adverse effects in mammals, birds, terrestrial insects, and microorganisms 

are not likely using typical or worst-case exposure assumptions at the typical application rate. As 

with the human health risk assessment, this characterization of risk must be qualified. 

Chlorsulfuron has been tested in only a limited number of species and under conditions that may 

not well-represent populations of free-ranging nontarget species. Notwithstanding this limitation, 

the available data are sufficient to assert that no adverse effects are anticipated in terrestrial 

animals that do not directly depend on the weeds that are targeted. Similarly, the risk 

254 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

characterization for aquatic animals is relatively simple and unambiguous. Chlorsulfuron appears 

to have a very low potential to cause any adverse effects in aquatic animals.

Clopyralid

Clopyralid is the most selective herbicide proposed for use. It is effective on spotted knapweed

and also affects members of four plant families: Asteraceae, Fabaceae, Solanaceae (nightshade) 

and Polygonaceae (SERA 19991a). Clopyralid does not affect conifers, including old-growth 

ponderosa pine or important browse species. The herbicide can be applied near or over conifers 

and many shrubs and forbs without damaging the native plant community. Clopyralid usually 

provides one growing season of control.

Weeds such as leafy spurge are not effectively controlled by clopyralid herbicides. If these 

species occur in a complex with spotted knapweed and infestations are treated only with 

clopyralid, the spurge would likely expand within the plant community even though spotted 

knapweed is controlled.

Commercial formulations of clopyralid methyl such as Reclaim®, Stinger®, and Transline® 

contain approximately 41 percent clopyralid methyl and 59 percent inert ingredients (water, 

isopropyl alcohol, and a surfactant).

It is chemically similar to picloram, but clopyralid has a shorter half-life, is more water-soluble, 

and has a lower absorption capacity than picloram. It may be persistent in soils with low 

microorganism content. The half-life can range from 15 to 287 days depending upon soil type and 

climatic conditions (Infoventures 1995e). It is degraded almost entirely by microbial metabolism 

in soils and aquatic sediments. It is not degraded by sunlight or hydrolysis. Its persistence implies 

that clopyralid has the potential to be highly mobile and a contamination threat to water resources 

and nontarget species (Tu et al. 2001).

Clopyralid is relatively nontoxic to birds, mammals and bees (SERA 1999a). It does not 

bioaccumulate in animal tissue. The acute oral toxicity in rats was LD50 greater than 4,300 

mg/kg (relatively nontoxic). In rabbits, clopyralid had a dermal LD50 of greater than 2,000 mg/kg 

(relatively nontoxic). Clopyralid caused slight skin irritation and eye irritation in rabbits. Rats 

showed no adverse effects after 4 hours of exposure to concentrations of 1.3 mg/L in air 

(Infoventures 1995e). Clopyralid showed no evidence of oncogenicity in a 2-year feeding study in 

mice or rats at the highest dose tested. It showed no evidence of developmental toxicity in mice 

and rabbits at the highest dosage tested. No effects on reproduction were observed in study of two 

generations of rats at the highest dose tested. No evidence of mutagenicity was observed in a 

number of laboratory studies on mice and rats. Based on the results of these animal studies, 

clopyralid is not classified as a carcinogen, teratogen, mutagen, or reproductive inhibitor 

(Infoventures 1995e). Technical grade clopyralid methyl is contaminated with hexachlorobenzene 

and pentachlorobenzene at average concentrations of < 2.5 ppm and <0.3 ppm, respectively 

(SERA 1999a). Hexachlorobenzene is potentially carcinogenic. However, because of the small 

proportion of hexachlorobenzene in clopyralid, the amount released into the environment from 

USFS programs contributes little to the background levels of hexachlorobenzene in the 

environment (SERA 1999a).

Clopyralid is of low toxicity to aquatic organisms. It’s LC50s (96 hour) for bluegill sunfish and 

rainbow trout are 125mg/L and 104 mg/L, respectively (SERA 1999a). Clopyralid is highly 

water-soluble and will not bind with suspended particles in the water column and as such can be 

Final Environmental Impact Statement – Invasive Plant Control Project 255
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

persistent in the aquatic environment. The half-life of Clopyralid in water ranges from 8 to 40 

days (SERA 1999a). Following aerial application to soils at a rate of 2.5 kilograms (kg) 

formulated product/hectare (ha) (more than two times the label rate application to soils for 

noncropland use in California), one study recorded peak concentrations of 0.017 mg/L in a nearby 

stream that drained the area (Leitch and Fagg 1985). Similar results were documented from a 

study in Australia (SERA 1999a). They estimated that a total of 12 grams (g) of Clopyralid (0.01 

percent of that applied) leached into the stream during the first significant rainfall (3 days after 

application). Bergstrom (1991) found a maximum of 0.02 percent of applied Clopyralid was lost 

to runoff from clay soils in Sweden.

Risk characterization for potential human health effects is relatively unambiguous for Forest 

Service programs. Based on the estimated level of exposure and the criteria for acute and chronic 

exposure, there is no evidence that typical or accidental exposures will lead to dose levels that 

exceed the level of concern for workers. For members of the general public, none of the longerterm exposure scenarios approach a level of concern and none of the acute/accidental scenarios 

exceed a level of concern, based on central estimates of exposure. The upper limit of the hazard 

for consumption of water after an accidental spill slightly exceeds the level of concern. (see 

cancer risk of hexachlorobenzene below).

The contamination of clopyralid with hexachlorobenzene and pentachlorobenzene does not 

appear to present any substantial cancer risk. Administratively, the Forest Service has adopted a 

cancer risk level of one in one-million (1÷1,000,000) as a trigger that would require special steps 

to mitigate exposure or restrict and possibly eliminate use. Based on relatively conservative 

exposure assumptions, the risk levels estimated for members of the general public are below this 

trigger level. The highest risk level is estimated at about 3 in 100 million, a factor of 33 below the 

level of concern. The exposure scenario associated with this risk level involves the consumption 

of contaminated fish by subsistence populations (i.e., groups that consume relatively large 

amounts of contaminated fish). The consumption of fish contaminated with hexachlorobenzene is 

a primary exposure scenario of concern because of the tendency of hexachlorobenzene to 

bioconcentrate from water into fish. This is also consistent with the general observation that 

exposure to hexachlorobenzene occurs primarily through the consumption of contaminated food. 

(SERA 1999a, page 3-22)

The most likely damage to nontarget species will involve terrestrial plants. Sensitive plant species 

could be adversely affected by the offsite drift of clopyralid under a variety of different scenarios 

depending on local site-specific conditions. If clopyralid is applied in the proximity of sensitive 

crops or other desirable sensitive plant species, site-specific conditions and anticipated weather 

patterns will need to be considered if unintended damage is to be avoided. More tolerant plant 

species are not likely to be affected unless they are directly sprayed or subject to substantial drift. 

Because of the tendency for clopyralid to move into soil rather than to be transported by runoff 

and because of the greater toxicity of clopyralid by foliar deposition compared to soil 

contamination, offsite movement of clopyralid by soil runoff does not appear to be a substantial 

risk to nontarget plant species. Aquatic plants do not appear to be at any substantial risk from any 

plausible acute or chronic exposures. In the very extreme case of an accidental spill of a large 

amount of the herbicide into a relatively small body of water, sensitive aquatic plants could be 

damaged.

No adverse effects are anticipated in terrestrial or aquatic animals from the use of clopyralid in 

Forest Service programs at the typical application rate. At the highest anticipated rate, the same 

256 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

qualitative assessment holds, except for scenario of a large bird feeding exclusively on 

contaminated vegetation over a 90-day period. Other more plausible scenarios—i.e., the longer 

term consumption of vegetation contaminated by drift or the longer term consumption of 

contaminated water or fish—yield hazard quotients that are far below a level of concern.

Dicamba

Dicamba is a selective broadleaf herbicide. It is effective on plants in the Asteraceae (composite) 

and Fabaceae (legume) families. Dicamba is the active ingredient in Banvel® and Vanquish®

formulations.

Dicamba is moderately persistent in soil, with a half-life of 1 to 6 weeks. Breakdown is slower 

with low soil moisture and low temperatures. The main metabolite of dicamba breakdown in soil 

is 3,6-dichlorosalicylic acid (Infoventures 1995g). Dicamba is soluble in water and microbial 

degradation is the main route of dicamba disappearance. Photolysis may also occur. Aquatic 

hydrolysis, volatilization, adsorption to sediments, and bioconcentration are not expected to be 

significant (Howard, 1989).

Dicamba is slightly toxic to mammals, nontoxic to birds, nontoxic to bees, and does not 

bioaccumulate. Based on results of animal studies dicamba does not cause birth defects, cancer, 

or genetic damage (Infoventures 1995g). Exposure to dicamba has been associated with 

reproductive and possibly neurotoxic effects in laboratory animals (SERA 1995). However, 

ecological risk assessment suggests no plausible or substantial effects to terrestrial or aquatic 

animals (SERA 1995). Concentrated solutions of dicamba have been shown to cause eye irritation 

in rabbits, which is a common test species for ocular effects. The extent to which actual 

formulations may cause dermal or ocular irritation during normal use cannot be determined from 

the available data, however. In addition, moderate dermal sensitization was observed in guinea 

pigs after contact with a 10 percent solution of dicamba (SERA 1995). The manufacturing 

process for dicamba has the potential to result in trace amounts of 2,7-dichlorodibenzo-p-dioxin 

as a contaminant. It may be present in concentrations up to 50 parts per billion (ppb). The dioxin 

isomer, 2,3,7,8-tetra-chlorodibenzo-p-dioxin has not been found at the limit of detection (2 ppb) 

and is not expected as an impurity in dicamba (PMEP 1983).

Dicamba is slightly toxic to fish and amphibians. The LC50 (48 hour) for technical Dicamba in 

rainbow trout and bluegill sunfish is 35 mg/L and 40 mg/L, respectively. The LC50s (48 hour) for 

other aquatic organisms include 465 mg/L in carp and 110.7 mg/L in Daphnia. The LC50 (96 

hour) for technical Dicamba in rainbow trout and bluegill sunfish is 135.4 mg/L and 135.3 mg/L, 

respectively. LC50s (96 hour) for other aquatic organisms include >100mg/L for grass shrimp, 

and >180mg/L for fiddler crab and sheepshead minnow (EXTOXNET 1996b). Power (1989) 

identified an LC50 (96 hour) for a tusked frog tadpole (Adelotus brevis) of 106 mg/L. 

Comparable studies on aquatic algae and aquatic animals indicate that some species of algae are 

much more sensitive to Dicamba compared with fish and aquatic invertebrates (SERA 1995). 

Dicamba does not accumulate or build up in aquatic organisms. However, its formulations have 

not been tested for chronic effects in aquatic organisms.

The use of dicamba in Forest Service programs may involve levels of exposure to workers and 

members of the general public that are of concern. At the typical application rate considered in 

this risk assessment, workers would not be exposed to levels of dicamba that are regarded as 

above levels of concern long term. At the maximum application, however, worker exposure to 

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Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

dicamba would exceed the level of concern at the upper range of plausible exposures. Members 

of the general public could be at some risk at the typical application rate only in the event of 

worst-case exposure assumptions for two accidental exposures involving children. Based on 

multiple sources of exposure, however, the levels of exposure would modestly exceed the level of 

concern for adults at the typical application rate. At the highest application rate that might be used 

in Forest Service programs, many of the acute exposure scenarios exceed the level of concern at 

the upper range of exposure. For longer term exposures, no risks are apparent at the typical 

application rate. The highest application rate, however, the consumption of contaminated 

vegetation exceeds the level of concern at the upper range of non-accidental and plausible 

exposures.

Dicamba is an effective herbicide and even some tolerant plants that are directly sprayed with 

dicamba at normal application rates are likely to be damaged. The greatest risks are associated 

with runoff but are highly site specific. Some sensitive plant species could be affected by runoff 

in areas in which runoff is favored, such as clay soil and surface conditions that are conducive to 

runoff. Damage associated with offsite drift of dicamba would also depend on local site-specific 

conditions but would most likely occur within a relatively small distance from the application 

site—i.e., up to about 100 feet. Vapor exposures to offsite vegetation could also cause damage. 

While this cannot be well quantified, it is likely that this effect would be less pronounced with 

Vanquish than with Banvel. Unlike the risk characterization for aquatic animals, the risk 

characterization for aquatic plants is based on relatively consistent and standard toxicity data. At 

the typical application rate, adverse effects in aquatic plants are not likely. At the maximum 

application rate, peak concentrations in water could be associated with transient effects in 

sensitive species of algae as well as macrophytes. These concentrations, however, would rapidly 

diminish to levels substantially below a level of concern.

For terrestrial vertebrates, some acute exposure scenarios but no chronic exposure scenarios 

exceed the level of concern but only at the highest application rate. At the typical application rate 

of 0.3 lb/acre, no adverse effects on mammals or birds are plausible for either acute or chronic 

exposures. There is little basis for asserting that adverse effects would be expected in terrestrial 

insects or soil microorganisms. The very limited data in insects suggest that no lethal effects are 

likely in a direct spray. There are no data on sublethal effects in insects. At the highest application 

rate, transient effects might be seen in some populations of soil microorganisms. A substantial 

limitation in the risk characterization is that no information is available on the chronic toxicity of 

dicamba to aquatic animals and the available acute toxicity data do not permit reasonable 

estimates of toxicity values for chronic toxicity. Within these very serious limitations, there is 

little basis for asserting that adverse effects in aquatic animals are plausible. This conclusion is 

consistent with a recent assessment by the U.S. EPA on the impact of dicamba on Pacific 

anadromous salmonids.

Glyphosate

Glyphosate is a broad spectrum, nonselective herbicide that damages all annual and perennial 

plants including grasses, broad-leaved weeds and woody plants. It is absorbed through the leaves 

of plants and is then transported throughout the whole plant. It controls weeds by inhibiting the 

synthesis of aromatic amino acids necessary for protein formation in susceptible plants, killing 

the entire plant. At low levels of application it regulates growth. Trade name herbicides that

contain Glyphosate include Roundup, Rodeo, Gallop, Ranger, Accord, Vision, Pondmaster, 

258 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

Landmaster and Touchdown. Glyphosate may also be an ingredient in the formulations of other 

types of herbicides.

Glyphosate itself is an acid, but is commonly used in isopropylamine salt form. When applied to 

foliage it is quickly absorbed by the leaves and rapidly moves through the plant.

Care should be taken, especially in natural areas, to prevent it from being applied to desirable, 

native plants because it will likely kill them. In terrestrial systems, glyphosate can be applied to 

foliage, green stems, and cut stems (cut stumps), but cannot penetrate woody bark. Only certain 

formulations of glyphosate (e.g., Rodeo®) are registered for aquatic use, as glyphosate by itself is 

essentially nontoxic to submersed plants, but the adjuvants often sold for use with glyphosate 

may be toxic to aquatic plants and animals.

Concentrations vary by target species and time of year. For the control of common agricultural 

weeds during the spring growing season concentrations of about 2 tablespoons per gallon is 

common, but for control of more persistent weeds such as Himalayan blackberry (Rubus discolor) 

concentrations of up to 4 tablespoons per gallon may be applied during late summer/early fall.

Glyphosate is one of the most commonly used herbicides in natural areas because it provides 

effective control of many species. Natural area weeds that have been controlled with glyphosate

include: bush honeysuckle (Lonicera maackii), cogon grass (Imperata cylindrica), common 

buckthorn (Rhamnus cathartica), glossy buckthorn (Frangula alnus), Japanese honeysuckle 

(Lonicera japonica), and smooth brome (Bromus inermis). In The Nature Conservancy preserves, 

glyphosate has been used to control dewberries (Rubus spp.), bigtooth aspen (Populus 

grandidentata), and black cherry (Prunus serotina) at Kitty Todd preserve in Ohio; sweetclover 

(Melilotus officinalis) in Indiana preserves; leafy spurge (Euphorbia esula) and St. John’s 

wort/Klamath weed (Hypericum perforatum) in Michigan preserves; and bindweed (Convolvulus 

arvensis) and velvetgrass (Holcus lanatus) in Oregon and Washington preserves.

In aquatic or wetland systems, glyphosate has successfully controlled common reed (Phragmites 

australis) in Delaware, Michigan, and Massachusetts preserves; purple loosestrife (Lythrum 

salicaria) in Indiana and Michigan preserves; reed canarygrass (Phalaris arundinacea) in Illinois 

preserves; and glossy buckthorn (Frangula alnus) and hybrid cattail (Typha x glauca) in 

Michigan preserves (Tu, et al. 2001).

Glyphosate is metabolized by some plants, while others do not break it down. Glyphosate would 

remain in soil unchanged for a varying length of time depending on soil texture and organic 

matter content. Half-life of glyphosate is reported to be from 3 to 130 days (Infoventures 1995a). 

Soil microorganisms break down glyphosate and the surfactant used in Roundup to carbon 

dioxide.

Glyphosate is strongly adsorbed to soil particles, which prevents it from excessive leaching or 

from being taken up from the soil by nontarget plants. It is degraded primarily by microbial 

metabolism, but strong adsorption to soil can inhibit microbial metabolism and slow degradation. 

Photo and chemical degradation are not significant in the dissipation of glyphosate from soils. 

The half-life of glyphosate ranges from several weeks to years, but averages 2 months. In water, 

glyphosate is rapidly dissipated through adsorption to suspended and bottom sediments, and has a 

half-life of 12 days to 10 weeks. Glyphosate by itself is of relatively low toxicity to birds, 

mammals, and fish, and at least one formulation sold as Rodeo® is registered for aquatic use. 

Some surfactants that are included in some formulations of glyphosate, however, are highly toxic 

Final Environmental Impact Statement – Invasive Plant Control Project 259
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

to aquatic organisms, and these formulations are not registered for aquatic use. Monsanto’s patent 

for glyphosate expired in 2000, and other companies are already selling glyphosate formulations.

Glyphosate is reported to be nontoxic, with a reported oral LD50 of 5,600 mg/kg in the rat, and 

over 10,000 mg/kg in mice, rabbits, and goats (EXTOXNET 1996b). Toxicity of technical grade 

acid of glyphosate and Roundup® are nearly the same. The oral LD50 for the trimethylsulfonium 

salt is reported to be about 750 mg/kg in rats, which indicates moderate toxicity (EXTOXNET 

1996b). Acute dermal LD50 for glyphosate and isopropylamine salt are reported to be >5,000 

mg/kg, and the dermal LD50 for the trimethlysulfonium salt are reported to be >2,000 mg/kg. 

Studies of glyphosate lasting up to 2 years have been conducted with rats, mice, dogs, and rabbits, 

and with few exceptions no effects were observed (EXTOXNET 1996b, Infoventures 1995c, 

SERA 2002, SERA 2003a). Some tests have shown reproductive effects may occur at high doses 

(over 150 mg/kg/day), but there have been little to no reports of mutagenic, developmental, or 

carcinogenic effects. In humans, glyphosate has been classified as a mild to moderate irritant to 

the skin and eyes, and there are no data indicating that it causes sensitization in either animals or 

humans (SERA 2002, SERA 2003a).

Glyphosate has a low acute toxicity (EPA Toxicity Category III for both oral and dermal toxicity). 

The acute oral LD50 in rats is 4,320 mg/kg (Infoventures 1995c). Its low toxicity can be 

attributed to it affecting the shikimic pathway that does not exist in animals, although it can 

disrupt the functions of some enzymes in animals at extremely high doses (several gm/kg body 

weight). There is little, if any, chronic toxicity. Glyphosate does not appear to cause birth defects, 

does not affect fertility, reproduction or development of offspring, and is classified as a 

noncarcinogen. Although glyphosate itself may have low toxicity, the surfactants used in many of 

the products can be serious irritants, toxic to fish and can contain carcinogens (Pesticide News, 

1996). The most widely used surfactants are ethylated amines, which are significantly more toxic 

than glyphosate. A new nonirritant formulation, Roundup Biactive®, has been developed. 

Rodeo® (Glyphosate 53.5 percent and water 46.5 percent) and Accord® (Glyphosate 41.5 

percent and 58.5 percent) are formulations which do not include a surfactant and are best for use 

in aquatic areas.

Glyphosate is strongly adsorbed to the soil, more so in organic soils where it becomes generally 

inactive. It is not absorbed from the soil by plant roots. Glyphosate remains unchanged in the soil 

until it is broken down by microorganisms. Microorganisms also break down the surfactants used 

in herbicide formulations. The half-life of glyphosate in soil ranges from 1 to 174 days, with an 

average of 47 days (Wauchope et al. 1992), depending on soil texture and organic matter content. 

Glyphosate inhibits nitrogen-fixing bacteria (SERA 2003a). In water, it adsorbs to suspended 

organic and mineral particles. In water, it is also broken down by microorganisms and has a halflife range from 35 to 63 days (Infoventures 1995c). Its toxicity in water is increased with higher 

temperatures and pH. Because it adsorbs strongly to soil particles, the potential for leaching is 

low, but it can be transported to surface waters by eroded soil.

The technical grade of glyphosate is no more than slightly toxic to fish and is practically nontoxic 

to aquatic invertebrates. The 96-hour LC50 of glyphosate is 120 mg/L for bluegill and is 86mg/L 

for rainbow trout (EXTOXNET 1996b). The 48-hour LC50 of glyphosate for Daphnia is 780 

mg/L (EXTOXNET 1996b). Some formulations are more toxic to fish and aquatic species due to 

the toxicity of the surfactants. The LC50 for Roundup® (Glyphosate 41 percent, polyethoxylated 

tallowmine surfactant 15 percent, water 44 percent) is 5-26 mg/L for fish and 4-37 mg/L for 

invertebrates (Infoventures 1995j). The Rodeo® and Accord® formulations (without a surfactant) 

260 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

have an LC50 of greater than 1,000 mg/L for fish and 930 mg/L for Daphnia (Infoventures 

1995c). Water temperature may affect the toxicity of the herbicide; Folmar (1979) found that the 

toxicity of glyphosate to bluegill and rainbow trout doubled when the water temperature was 

increased from 45 to 63 °F. 

The risk characterization for both workers and members of the general public are reasonably 

consistent and unambiguous. For both groups, there is very little indication of any potential risk at 

the typical application rate. Even at the upper range of plausible exposures in workers, exposure 

is below the level of concern, even at the upper levels when broadcast spray is used. For members 

of the general public, none of the longer-term exposure scenarios exceed or even approach a level 

of concern. Long-term consumption of contaminated fruit still falls within the level of concern. 

There is no route of exposure or exposure scenario suggesting that the general public will be at 

risk from longer-term exposure to glyphosate. Only exposure scenarios that contemplate 

consumption of water directly out of a pond immediately after a spill exceed the levels of 

concern.

For relatively tolerant nontarget species of plants, there is no indication that glyphosate is likely 

to result in damage at distances as close as 25 feet from the application site. For sensitive species 

at the upper range of application rates, there is a modest excursion about the NOEC at offsite 

distances of 100 feet or less. It should be noted, however, that all of these drift estimates are based 

on low-boom ground sprays. Many applications of glyphosate are conducted by directed foliar 

applications using backpacks. In such cases, little if any damage due to drift would be anticipated. 

Nontarget terrestrial plants are not likely to be affected by runoff of glyphosate under any 

conditions. There is no indication that adverse effects on aquatic plants are plausible.

The current risk assessment for glyphosate generally supports the conclusions reached by U.S. 

EPA: Based on the current data, it has been determined that effects to birds, mammals, fish and 

invertebrates are minimal. At the typical application rate, none of the levels of exposure 

approached the reference doses. For the application rate at the upper end of the range, estimates 

of the hazard levels somewhat exceed the level of concern for the direct spray of a honey bee. For 

the upper range of the exposure scenarios, the level of concern is exceeded modestly in acute 

scenarios for a large mammal consuming contaminated vegetation and a small bird consuming 

insects. In the chronic exposure scenarios, the hazard quotient for a large bird consuming

contaminated vegetation on site exceeds the level of concern threefold. As with all longer term 

exposure scenarios involving the consumption of contaminated vegetation, the plausibility of this 

exposure scenario is limited because damage to the treated vegetation, making it less likely to be 

consumed over a prolonged period of time. The primary hazards to fish appear to be from acute 

exposures to the more toxic formulations. At the typical application rate, the exposure to 

hazardous levels will be not reached or exceeded under worst-case conditions. At higher rates, the 

acute exposures are estimated to slightly exceed the toxic level for both sensitive species and for 

the typical, non-sensitive species. In these 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. This risk characterization strongly suggests that the use of the more toxic formulations 

near surface water is not prudent. The use of less toxic formulations result in an exposure that 

doesn’t approach a level of concern for any species. Thus, the use of glyphosate near bodies of 

water where sensitive species of fish may be found (i.e., salmonids) should be conducted with 

substantial care to avoid contamination of surface water. Concern for potential effects on 

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Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

salmonids is augmented by the potential effects of low concentrations of glyphosate on algal 

populations. The likelihood of direct acute toxic effects on aquatic invertebrates or longer term 

direct effects on any fish species seems extremely remote based on central estimates of the hazard 

quotient and unlikely base on upper ranges of the hazard quotient.

Hexazinone

Hexazinone is a broad spectrum herbicide used in the control of annual and perennial broadleaf 

herbaceous plants, some grasses and some woody species. It works by inhibiting photosynthesis 

in susceptible plants by destroying chloroplast and cell and organelle membranes. In 

nonsusceptible plants, hexazinone is broken down to less phytotoxic compounds. Hexazinone is 

absorbed through the roots and foliage of plants, and best results are obtained for herbaceous 

species when applied in moist soil conditions, as either a foliage spray or basal soil treatment. 

Larger woody species are best controlled by injection or hack-and-squirt techniques. Species that 

have been controlled by hexazinone include: tansy-mustard (Descurainia pinnata), cheatgrass 

(Bromus tectorum), filaree (Erodium spp.), shepards-purse (Capsella bursa-pastoris), false 

dandelion (Hypochaeris radicata), privet (Ligustrum spp.), and Chinese tallowtree (Sapium 

sebiferum).

Hexazinone is the active ingredient in the trade name herbicides DPX 3674, Pronone and Velpar. 

Hexazinone herbicides are available as a water-soluble powder (Velpar®; 90 percent hex, 10 

percent inerts), a water dispersible liquid (Velpar® L; 25 percent hex, 40-45 percent ethanol, and 

30-35 percent inerts), soluble granules (Velpar® ULW; 75 percent hex, 25 percent inerts) and 

granules (Pronone®; 10 percent hex, 90 percent inerts).

Hexazinone has an EPA Human Hazards Toxicity Category I rating, due to it being an eye irritant. 

It causes severe and irreversible corneal opacity and corrosion in rabbits (Infoventures, 1995k). It 

is slightly toxic via oral ingestion (LD50 of 1,690 mg/kg in rats, Toxicity Category III) and nearly 

nontoxic via dermal exposure (LD50 of > 5,278 mg/kg in rabbits, Toxicity Category IV) 

(Infoventures 1995k). Chronic toxicity is not apparent and it does not pose a risk to fertility, 

reproduction, or growth of offspring (NOEL of 100 mg/kg/day for development in rats, NOEL of 

50 mg/kg/day for development in rabbits) (PMEP, 2001a).

Hexazinone is water-soluble and does not bind strongly with soils, and so is of particular concern 

for ground water contamination. It can persist in soils and aquatic systems for some time (average 

half-life in soil is 90 days), increasing the likelihood of contamination. (Tu et al. 2001). 

Hexazinone can enter aquatic systems through surface and subsurface runoff following 

application and drift during application. It is degraded by microbial metabolism, but not readily 

decomposed chemically or by sunlight and can, therefore, persist in aquatic systems. The average 

half-life of hexazinone in soils is 90 days, but it can sometimes be found in runoff up to 6 months 

after application.

Although it is of relatively low toxicity to birds and mammals, legal application rates can leave 

residues that exceed EPA’s level of concern for aquatic and terrestrial plants and small mammals. 

It is of relatively low toxicity to fish and aquatic invertebrates but can be highly toxic to some 

species of algae. Hexazinone contamination has been detected in small water bodies in episodic, 

low-level pulses that were rapidly diluted in mainstream flows. High concentrations of 

hexazinone, however, could lead to significant losses of algae and macrophytic biomass, which 

could produce a ripple effect in the food chain that ultimately could impact fish and wildlife 

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Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

species. Although hexazinone can accumulate in treated crops, concentrations in vegetation are 

not likely to reach toxic levels for foraging animals when hexazinone is applied properly. Care 

should be taken in preparing and applying hexazinone as it can cause severe eye damage.

The half-life of hexazinone in soils ranges between 1 and 6 months with an average of 90 days 

(Tu et al. 2001). The half-life for Velpar® ULW in plants is 26-59 days and in litter is 55 days 

(Michael et al. 1999). Hexazinone is degraded by microbial metabolism in aerobic soils and may 

also be broken down by photodegradation. The chemical breakdown of Hexazinone leads to 8 

different metabolites, only one of which is known to be toxic to plants and at only 1 percent of the 

toxicity of Hexazinone (Tu et al. 2001). Hexazinone is stable in water without the presence of 

sunlight or microbes. In natural conditions, photodecomposition, biodegradation and dilution are 

methods of loss of activity in water. The half-life of Hexazinone in water can vary between 

several days (Solomon et al. 1988) to more than 9 months (Thompson et al. 1992).

Hexazinone is a triazine herbicide that acts by inhibiting photosynthesis. It is generally 

chemically stable, highly soluble in water, and relatively insoluble in various organic solvents. It 

has been reported that half of the applied dose is lost in soil after 1 to 6 months depending on 

climate and soil type (EXTOXNET 1996c). Hexazinone is broken down by soil microbes and 

sunlight. Hexazinone does not evaporate to any appreciable extent, and it can leach through the 

soil to the root zone. Hexazinone has a low order of acute toxicity; however, it can cause serious 

and irreversible eye damage. In rats, the LD50 was reported at 1,690 mg/kg (EXTOXNET 

1996c). Other LD50 reported for hexazinone are 860 mg/kg for guinea pigs and 3,400 mg/kg for 

beagle dogs. The LD50 for rabbits is reported to be greater than 5,278 mg/kg.

Studies of chronic toxicity of hexazinone in mammals show it to have a low order of chronic 

toxicity. Rats given moderate doses of hexazinone in their food for 2 weeks showed no evidence 

of cumulative toxicity (EXTOXNET 1996c). Rats and dogs fed high doses of the compound for 

90 days showed only slight decreased body weights. Very high doses did not appear to effect 

hamsters, and caused only increased liver weights in mice. It is generally not considered to be a 

reproductive, mutagenic, or carcinogenic compound based on chronic toxicological studies. 

Consumption of hexazinone granules by birds immediately after application could lead to 

reproductive effects or overt toxic effects. However, the plausibility of this risk is questionable, 

since there are no data indicating birds consume hexazinone granules (SERA 1997).

Hexazinone has low adsorption capacity in soils and sediment and does not volatilize readily. It 

is, however, highly soluble in water, which makes it very mobile through the soil. Due to its 

persistence and mobility through soil, there is potential for contamination of ground water and 

nearby surface water. As noted by Tu et al. (2001) some research has observed that after granular 

formulations were applied during the fall, surface runoff following spring melt contaminated 

nearby marsh reed grass. Michael et al. (1999) applied Hexazinone at a rate of 6.72 kg/ha (3 times 

the rate prescribed for the site) to a watershed in Piedmont, Alabama. During application, 

maximum stream concentration was 422 μg/L for Velpar® ULW and 473 μg/L for Velpar® L, 

due to direct overspray. During the first 30 days, stream concentrations peaked several times with 

stormflow (56-70 μg/L Velpar® ULW; 145-230 μg/L Velpar® L), but was diluted 3 to 5 times 1.6 

km downstream. In the upper Piedmont in north Georgia, low concentrations of hexazinone were 

found in storm runoff 7 months after application (Neary et al. 1986). In a steep watershed in 

north-central West Virginia, one study found that 4.7 percent of the Hexazinone applied leached 

into local streams (SERA 1997a).

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Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

The technical grade of hexazinone is only slightly toxic to fish species. The liquid and solid 

carriers in two commercial hexazinone formulations were found to be of extremely low toxicity 

to fish (Infoventures, 1995k). The technical grade of hexazinone has an LC50 for rainbow trout of 

320 mg/L, 370 mg/L for bluegill sunfish and 274 mg/l for the flathead minnow (SERA 1997a). 

These levels far exceed residue amounts found in streams in treated watersheds. For freshwater 

invertebrates hexazinone is practically nontoxic. The EC50 for Daphnia magna is 151 mg/L 

(SERA 1997a). Studies also found no significant changes in invertebrate species diversity or 

composition between treated and untreated sites (SERA 1997a). Several studies show that 

hexazinone is toxic to algae at 0.01 to 0.60 mg/L, and can slow growth after only 1 day of 

exposure (SERA 1997a). Although peak concentrations in streams from storm flow may exceed 

this threshold, chronic exposure at these levels is unlikely with appropriate application.

Hexazinone does not accumulate in fish. When Rhodes (1980) exposed bluegill sunfish to 

concentrations of 1 ppm for 28 days, levels in tissue peaked after 1 to 2 weeks of exposure and 

were completely eliminated 2 weeks after withdrawal. The threat of bioaccumulation is low as it 

is processed and excreted by animal systems.

The major hazard associated with the use of hexazinone will involve accidental or incidental 

ocular or respiratory exposure. As discussed in the hazard identification (SERA 1997a), 

hexazinone is a severe eye irritant. In addition, the California worker study suggests that 

respiratory irritation is plausible or even likely in the use of granular formulations of hexazinone 

that contain high levels of dust or fine particulates. Based on the exposure assessments and the 

dose-response assessments, the assessments determined that all worker groups may be exposed to 

hexazinone at levels that exceed the reference doses, with effects including irritation to the eyes, 

respiratory tract, and skin. In general, irritant effects on the eyes and respiratory tract are likely to 

be more severe than effects on the skin. Even under the most extreme exposure scenarios, frank 

toxic effects are not likely to be observed. In some accidental and extreme exposure scenarios, 

members of the general public may be exposed to levels of hexazinone above the reference dose, 

but still far below the levels projected for workers. While any exposure above the reference dose 

is considered unacceptable by definition, the exposure estimates for the general public are in a 

range where the occurrence and nature of potential toxic effects cannot be well characterized. As 

with workers, no signs of frank toxic effects are anticipated.

Nontarget terrestrial plants may be affected during the application of hexazinone. Direct 

deposition, from unintentional direct spraying or from spray drift is a plausible hazard for most 

herbicides, including those containing hexazinone. If plants are sprayed accidentally at the 

application rates used by the Forest Service, the plants, particularly hardwoods or sensitive pines, 

are likely to be damaged. During aerial applications at a rate of 1 lb a.i./acre and at distances less 

than 30 m from the application site, some damage to nontarget vegetation is plausible due to drift 

of liquid formulations. Ground applications of granular formulations or spot treatments with 

liquid applications of hexazinone should be associated with little significant drift. Soil 

contamination and transport of hexazinone to offsite nontarget vegetation, however, may occur. 

The magnitude of any observed effects will be highly dependent on local conditions, particularly 

soil type and rainfall. In porous and/or sandy soils with low levels of organic matter and under 

conditions of high rainfall, adverse effects on offsite vegetation are most plausible. Effects on 

algal species are virtually certain but are likely to be transient because of the transport and 

dilution of hexazinone in aquatic systems. Based on stream ecosystem studies, it is unclear that 

changes in the population of aquatic algae will lead to detectable secondary effects on aquatic 

animals.

264 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

Based on available toxicity data and the estimated levels of exposure, there is little indication that 

hexazinone is likely to cause adverse effects in terrestrial animal species. The consumption of 

contaminated water or vegetation yields hazard indices that are well below a level of concern at 

any plausible application rate either immediately after hexazinone applications or over prolonged 

periods after applications. A potential exception to this exposure assessment involves a scenario 

in which birds consume hexazinone granules immediately after application; in which case, 

reproductive effects and possibly overt signs of toxicity might occur. The plausibility of this risk 

for birds, however, is questionable. There are no data indicating that birds will consume any of 

the granular formulations that contain hexazinone. Thus, a lower limit on the exposure 

assessment is zero. If birds were to consume these granules preferentially, exposure levels could 

be much higher. In that case, toxic effects including mortality could occur. Without additional 

information with which to improve the exposure assessment, this risk cannot be characterized 

further. As discussed in the hazard identification, there is some evidence that the application of 

hexazinone at a rate of 0.89 lbs/acre affects soil microarthropods. It is not clear, however, if the 

noted effects—a deeper migration of soil mites into the soil layer—can be attributed to toxicity, 

avoidance, or other changes in soil characteristics. Under any plausible conditions of exposure, 

including accidental direct applications to a stream, effects on fish or aquatic invertebrates are 

unlikely. Conversely, effects on algal species are virtually certain but are likely to be transient 

because of the transport and dilution of hexazinone in aquatic systems. Based on stream 

ecosystem studies, it is unclear that changes in the population of aquatic algae will lead to 

detectable secondary effects on aquatic animals.

Imazapic

Imazapic is a selective herbicide for both pre- and post-emergent control of some annual and 

perennial grasses and some broadleaf weeds (Tu et al. 2001). It works well on species such as 

leafy spurge. Imazapic also controls annual grasses and can be used for restoration of native 

bunchgrass sites. The effect of the herbicide on perennial grasses and broadleaf weeds can vary 

within a plant family. In general, plants in the Brassicaceae (mustard) family, leafy spurge, and 

some cool-season perennial grasses are sensitive to the herbicide. Fall applications increase 

tolerance of cool season grasses, such as mountain brome, to imazapic. Warm season grasses and 

plants in the Asteraceae and Fabaceae family are very tolerant. Woody species are generally 

tolerant due to poor translocation of imazapic to meristem and lack of herbicide uptake through 

woody stems or roots.

Imazapic has an average half-life of 120 days in soil, is rapidly degraded by sunlight in aqueous 

solution with a half-life of 1 to 2 days, but is not registered for use in aquatic systems (Tu et al. 

2001).

Imazapic is essentially nontoxic to terrestrial mammals, birds, amphibians, aquatic invertebrates, 

and insects. It has a half-life of 7 to 150 days, depending upon soil type and climatic conditions. It 

is degraded primarily by soil microbial metabolism. It does not bioaccumulate in animals, as it is 

rapidly excreted in urine and feces (Tu et al. 2001, SERA 2001)). It has a half-life of 7 to 150 

days, depending on soil type and climatic conditions.

It is degraded primarily by soil microbial metabolism. The oral LD50 of imazapic is greater than 

5,000 mg/kg for rats and 2,150 mg/kg for bobwhite quail, indicating relative nontoxicity by 

ingestion. The LD50 for honeybees is greater than 100 mg/bee, indicating that imazapic is 

nontoxic to bees. Imazapic is nonirritating to eyes and skin, even in direct applications. The 

Final Environmental Impact Statement – Invasive Plant Control Project 265
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

inhalation toxicity is very low. Chronic consumption in rats for 2 years and in mice for 18 months 

elicited no adverse effects at the highest doses administered. Chronic consumption by dogs for 1 

year caused minimal effects (Tu et al. 2001, SERA 2001). Imazapic may be mixed with other 

herbicides such as picloram or 2,4-D. Combining imazapic with other herbicides should not 

increase the toxicological risk over that of either herbicide when used alone (Tu et al. 2001).

It is, therefore, essentially nontoxic to a wide range of nontarget organisms including mammals, 

birds and insects (Tu et al. 2001). However, imazapic itself is of low toxicity to fish. The LC50

(96 hour) for technical grade imazapic for bluegill sunfish and rainbow trout are >100 mg/L. 

American Cyanamid Company indicated that degradation in aqueous solution renders imazapic 

relatively safe to aquatic animals (Tu et al 2001).

Typical exposures to imazapic do not lead to estimated doses that exceed a level of concern. For 

workers, no exposure scenarios, acute or chronic, exceed the reference dose even at the upper 

ranges of estimated dose. For members of the general public, the upper limits for exposure to 

hazard are below a level of concern except for the accidental spill of a large amount of imazapic 

into a very small pond. Based on the available information and under the foreseeable conditions 

of application, there is no route of exposure or scenario suggesting that workers or members of 

the general public will be at any substantial risk from longer-term exposure to imazapic.

Imazapic is an effective herbicide and even tolerant plants that are directly sprayed with imazapic 

at normal application rates are likely to be damaged. Some sensitive plant species could be 

affected by the offsite drift of imazapic depending on local site-specific conditions within a 

relatively small distance from the application site—i.e., up to about 50 feet in ground applications 

and somewhat over 100 feet in aerial applications. Damage to terrestrial plants from runoff is 

possible in some areas but is not likely to be substantial. Under conditions in which runoff is 

favored—i.e., clay soils and relatively high rainfall rates—some aquatic macrophytes could also 

be affected by peak concentrations of imazapic. No effect in unicellular algae are anticipated.

Adverse effects in terrestrial or aquatic animals do not appear to be likely. The weight of evidence 

suggests that no adverse effects in mammals, birds, fish, and terrestrial or aquatic invertebrates 

are plausible using typical or worst-case exposure assumptions at the typical application rate of 

0.1 lb/acre or the maximum application rate of 0.1875 lb/acre. As in any ecological risk 

assessment, this risk characterization must be qualified. Imazapic has been tested in only a limited 

number of species and under conditions that may not well represent populations of free-ranging,

nontarget animals. Notwithstanding this limitation, the available data are sufficient to assert that 

no adverse effects on animals are anticipated based on the information that is available.

Imazapyr

Imazapyr is strongly adsorbed by soils, found only in the top few inches of the soil. Imazapyr is 

broken down by exposure to sunlight and soil microorganisms (Infoventures 1995j). As such, it 

has a low potential for leaching to ground water, but may reach surface water during storm events 

over recently treated land.

Because imazapyr is a weak acid herbicide, environmental pH will determine its chemical 

structure, which in turn determines its environmental persistence and mobility. Below pH 5 the 

adsorption capacity of imazapyr increases and limits its movement in soil. Above pH 5, greater 

concentrations of imazapyr become negatively charged, fail to bind tightly with soils, and remain 

mobile in the environment. In soils imazapyr is degraded primarily by microbial metabolism. It is 

266 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

not, however, degraded significantly by photolysis or other chemical reactions. The half-life of 

imazapyr in soil ranges from 1 to 5 months. In aqueous solutions, imazapyr may undergo 

photodegradation with a half-life of 2 days. Imazapyr is not highly toxic to birds and mammals, 

but some formulations can cause severe, irreversible eye damage. Studies indicate imazapyr is 

excreted by mammalian systems rapidly with no bioaccumulation. It has a low toxicity to fish, 

but studies on the effects of imazapyr to other aquatic species are lacking. Because imazapyr can 

be highly mobile, persistent, and can affect a wide range of plants, care must be taken in the 

application of this herbicide to prevent accidental contact with nontarget species. Additionally, 

recent studies report that imazapyr can “leak” out of the roots of treated plants and adversely 

affect the surrounding native vegetation.

Very little is lost by evaporation. Imazapyr is practically nontoxic to mammals and birds 

(Infoventures 1995j; SERA 1999b). In birds, the LD50 was reported to <2,150 mg/kg and in 

mammals between 4,800 and 5,000 mg/kg (Infoventures, 1995g). Imazapyr has not been found to 

be mutagenic and there has been no evidence to support developmental effects. Imazapyr can 

cause irritant effects in the skin and eyes (SERA 1999b). The EPA has classified imazapyr as a 

Class E compound, one having evidence of noncarcinogenicity. Under typical and conservative 

worst-case exposure assumptions, the evidence suggests that no adverse effects would be 

expected from the application of imazapyr (SERA 1999b).

Imazapyr is “rain-fast” in 2 hours. Also, since imazapyr is used at extremely low concentrations 

(e.g., 1 percent Arsenal for foliar applications), only those applicators actually mixing the 

herbicide would be at risk.

Imazapyr and its formulations are low in toxicity to invertebrates and practically nontoxic to fish. 

Acute oral toxicity in rates tested LD50 greater than 5,000 mg/kg, dermal toxicity was greater than 

2,000 mg/kg in rabbits. Chronic toxicity is not apparent and shows no evidence of developmental 

effects and there is not enough information available at this time to determine whether it causes 

cancer or adverse reproductive or fertility effects (Infoventures 1995k).

Typical exposures to imazapyr do not lead to estimated doses that exceed a level of concern for 

either workers or members of the general public at either the typical or highest application rate.

For workers and the general public, the upper limits of exposure when compared with reference 

dose are sufficiently below a level of concern that the risk characterization is relatively 

unambiguous. Based on the available information and under the foreseeable conditions of 

application, there is no route of exposure or scenario suggesting that the workers or members of 

the general public will be at any substantial risk from longer term exposure to imazapyr even at 

the upper range of the application rate considered in this risk assessment.

Imazapyr is an effective herbicide and even tolerant plants that are directly sprayed with imazapyr 

at normal application rates are likely to be damaged. Some sensitive plant species could be 

affected by the offsite drift or by offsite movement in runoff of imazapyr depending on sitespecific conditions. When applied to areas in which runoff is favored, damage from runoff 

appears to pose a greater hazard than drift. Residual soil contamination with imazapyr could be 

prolonged in some areas. In relatively arid areas in which microbial degradation may be 

predominant factor in the decline of imazapyr residues in soil, residual toxicity to sensitive plant 

species could last for several months to several years. In areas of relatively high rainfall rates, 

residual toxicity to sensitive plant species would be much shorter. This characterization of risk for 

residual soil contamination is general rather than site-specific. The persistence and movement of 

Final Environmental Impact Statement – Invasive Plant Control Project 267
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

imazapyr in soil is highly complex and substantially different estimates of persistence and 

transport could be made if different site-specific factors were considered. Thus, these estimates of 

risk should be considered only as crude approximations of environmentally plausible 

consequences. Some effects are also plausible in aquatic plants. Aquatic macrophytes appear to 

be more sensitive to imazapyr than unicellular algae. Peak concentrations of imazapyr in surface 

water could be associated with adverse effects in some aquatic macrophytes. Longer term 

concentrations of imazapyr, however, are substantially below the level of concern.

Adverse effects in terrestrial or aquatic animals do not appear to be likely. The weight of evidence 

suggests that no adverse effects in mammals, birds, fish, and terrestrial or aquatic invertebrates 

are plausible using typical or worst-case exposure assumptions at the typical application rate or 

the maximum application rate. As in any ecological risk assessment, the risk characterization 

must be qualified. Imazapyr has been tested in only a limited number of species and under 

conditions that may not well represent populations of free-ranging, nontarget organisms. 

Notwithstanding this limitation, the available data are sufficient to assert that no adverse effects

on animals are anticipated based on the information that is available.

Metsulfuron methyl

Metsulfuron methyl is a selective herbicide used to control brush and certain unwanted woody 

plants, annual and perennial broadleaf weeds, and annual grassy weeds. It can control plants in 

the mustard and borage families including whitetop and houndstongue, respectively.

Commercial formulations of metsulfuron methyl (Escort®, Ally®) contain 60 percent 

metsulfuron methyl and 40 percent inert ingredients.

Metsulfuron is water-soluble and remains in the soil unchanged for varying lengths of time, 

depending on soil type and moisture availability. The half-life can range from 120 to 180 days. 

Soil microorganisms and chemical hydrolysis break it down (SERA 2000, Infoventures 1995d). 

Metsulfuron methyl is practically nontoxic to birds, mammals, invertebrates, and bees (SERA 

2000). Acute oral LD50 was greater than 5,000 mg/kg in rats and 2,000 in mallard ducks; acute 

dermal LD50 was greater than 2,000 mg/kg in rabbits (Infoventures 1995d). Based upon the 

results of animal studies, metsulfuron methyl is not classified as a carcinogen, mutagen, 

teratogen, or reproductive inhibitor (Infoventures 1995d, SERA 2000). The primary adverse 

effect from exposure to metsulfuron methyl appears to be weight loss (SERA 2000).

The chemical is stable to hydrolysis at neutral and alkaline pHs.

Metsulfuron methyl has very low toxicity to aquatic organisms. LC50 (96 hour) for rainbow trout 

and bluegill sunfish are both >150 mg/L. A LC50 (48 hour) for Daphnia was also >150 mg/L 

(EXTOXNET 1996c). It appears that compound related mortality after acute exposure is not 

likely to be observed in fish exposed to concentrations less than or equal to 1,000 mg/L (SERA, 

2004d). As noted in SERA 2004d, a study regarding the toxicity of metsulfuron methyl to fish, 

eggs and fry, observed no effects on rainbow trout hatchling, larval survival or larval growth over 

a 90-day exposure period at a concentration of up to 4.7 mg/L. Concentrations greater that 8 mg/L 

resulted in small but significant decreases in hatching and survival of fry.

Metsulfuron methyl appears to be relatively nontoxic to aquatic invertebrates based on acute 

bioassays in Daphnia with an acute LC50 value for immobility of 720 mg/L and a NOEL for 

reproduction of 150 mg/L (SERA 2000/2004b). The only effect seen in a 21-day Daphnia study 

268 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

was a decrease in growth, which was observed at concentrations as low as 5.1 mg/L (SERA 

2004b). At concentrations less than 30 mg/L, the effect was not statistically significant.

Typical exposures to metsulfuron methyl do not lead to estimated doses that exceed a level of 

concern. For workers, no exposure scenarios, acute or chronic, exceeds the reference dose, even 

at the upper ranges of estimated dose. For members of the general public, all upper limits for 

hazard quotients are below a level of concern. Thus, based on the available information and under 

the foreseeable conditions of application, there is no route of exposure or scenario suggesting that 

workers or members of the general public will be at any substantial risk from acute or longer term 

exposures to metsulfuron methyl.

Metsulfuron methyl is an effective and potent herbicide. Adverse effects on some nontarget 

terrestrial plant species and, to a lesser degree, some aquatic plant species are plausible under 

some conditions. For terrestrial plants, the dominant factor in the risk characterization is the 

potency of metsulfuron methyl relative to the application rate. The typical application rate 

considered in this risk assessment is many times greater than the level of no observable adverse 

effect and so the likelihood is high that the herbicide will impact the vigor of the most sensitive 

nontarget species. Given these relationships, damage to sensitive nontarget species could be 

expected in ground broadcast applications at distances up to about 500 feet from the application 

site in areas in which offsite drift is not reduced by foliar interception. This risk characterization 

applies only to ground broadcast applications. When used in directed foliar applications (i.e., 

backpack), offsite drift could be reduced substantially, but the extent of this reduction cannot be 

quantified. The offsite movement of metsulfuron methyl via runoff could be substantial under

conditions that favor runoff—i.e., clay soils—with risk of impacts to vegetation occurring even 

where rainfall is relatively slight (15 inches per year). In very arid regions in which runoff might 

not be substantial, wind erosion could result in damage to nontarget plant species. The plausibility 

of observing such damage would, however, be highly dependent on local conditions. This risk 

characterization for the potential effects of runoff would be applicable to either broadcast ground 

or directed foliar applications. Thus, if metsulfuron methyl is applied in areas where transport to 

water containing aquatic macrophytes is likely, it would be plausible that detectable but transient 

damage could be observed. Aquatic algae do not appear to be as sensitive as aquatic macrophytes 

to metsulfuron methyl.

There is no clear basis for suggesting that effects on terrestrial or aquatic animals are likely or 

would be substantial. Adverse effects in mammals, birds, terrestrial insects, and microorganisms 

are not likely using typical or worst-case exposure assumptions at the typical application rate or 

the maximum application rate. As with the human health risk assessment, this characterization of 

risk must be qualified. Metsulfuron methyl has been tested in only a limited number of species 

and under conditions that may not well represent populations of free-ranging, nontarget species. 

Notwithstanding this limitation, the available data are sufficient to assert that no adverse effects 

are anticipated in terrestrial animals. Similarly, the risk characterization for aquatic animals is 

relatively simple and unambiguous. Metsulfuron methyl appears to have a very low potential to 

cause any adverse effects in aquatic animals. All of the hazard quotients for aquatic animals are 

extremely low, with a range in fish from 0.0000000003 (acute exposures in tolerant fish) to 

0.00003 (longer term exposures to sensitive fish). It should be noted that confidence in this risk 

characterization is reduced by the lack of chronic toxicity studies in potentially tolerant fish – i.e., 

bluegill sunfish trout. At the maximum application rate of 0.15 lbs/acre, all of the hazard 

quotients would be increased by a factor of about 5. However, this difference has no impact on 

the risk characterization for fish. Hazard quotients in aquatic invertebrates range from 

Final Environmental Impact Statement – Invasive Plant Control Project 269
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

0.0000000007 (acute exposure in Daphnia) to 0.0000007 (acute exposure in Daphnia). Thus, 

there is no basis for asserting that adverse effects on aquatic animals are likely.

Sulfometuron methyl

Sulfometuron methyl is more selective than glyphosate and is useful in controlling weedy grasses, 

in particular cheat grass. Native grass seeding should follow spraying within 1 year to prevent 

reestablishment of cheat grass (Sheley et al 1999).

Sulfometuron methyl herbicides are sold under the trade names Oust® Weed Killer and DPX 

5648. It is a general use pesticide used to control annual and perennial broadleaf weeds and 

grasses and some woody tree species. Sulfometuron methyl inhibits plant growth of the root and 

shoot by blocking the production of three amino acids needed for growth. It works by blocking 

cell division in the active growing regions of the stem and root tips. It may also have the same 

inhibitory effect on many fungi and bacteria, such as the bacteria Salmonella typhimurium

(Infoventures 1995h).

It is generally active in soil, and is broken down by microbes, hydrolysis, and sunlight. It has 

been reported that half of the compound degraded within 30 days in silt loam soils. It has a field 

half-life in the range of 20 to 28 days (EXTOXNET 1996g). It is more strongly adsorbed to acidic 

soils and soils with a high organic content than to alkaline soils or soils with low organic content. 

Sulfometuron methyl is practically insoluble in water, and it mainly decomposes to carbon 

dioxide (Infoventures 1995h). Sulfometuron methyl is a slightly toxic compound. Burnet and 

Hodgson (1991) found 5 out of 11 typical soil microorganisms were inhibited by Oust®.

The oral toxicity of this compound is very low, reported to have oral LD50 levels in rats of 

>5,000 mg/kg (EXTOXNET 1996g). Acute toxicity LD50 values for the bobwhite quail and 

mallard duck were reported to be <5,000 mg/kg, respectively (Infoventures 1995h). The acute 

dermal LD50 has been reported to be >2,000 mg/kg in female rabbits and >8,000 mg/kg in male 

rabbits. It is considered to be a mild irritant to the skin and a moderate eye irritant. Some 

immunological toxic effects have been reported with chronic exposure to sulfometuron methyl in 

test animals. Dogs have experienced reduced red blood cell counts and increased liver weights at 

exposures of 25 mg/kg/day for a year (EXTOXNET 1996g ). SERA 2000 also reported reduced 

red blood cell counts and increased liver weights at doses of 50 mg/kg/day.

While there is some concern of reproductive and teratogenic effects from exposure to 

sulfometuron methyl in laboratory animals, the results of the studies are somewhat unclear 

(SERA 2000, Infoventures 1995h) and EXTOXNET 1996g reports that sulfometuron methyl is 

unlikely to pose a mutagenic, carcinogenic or reproductive risk to animals and humans.

Sulfometuron methyl has a half-life in soils of approximately 30 days (Infoventures 1995h). Its 

adsorption is stronger in acidic soils and soils with high organic matter. It is practically insoluble 

in water. Oust® is a dispersible granule that can be suspended in water. Sulfometuron methyl’s 

half-life in acidic water is 10 days and in more alkaline water is about 8 months (EXTOXNET 

1996g). It is degraded by soil microorganisms, hydrolysis and photodegradation. There is 

potential for sulfometuron methyl to leach through the soils and be displaced by surface runoff to 

contaminate surface waters. However, due to its very low application rate (one-quarter to 8 

ounces formulated product per acre) and subsequent microbial breakdown, there is little potential 

for contamination of ground water.

270 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

Sulfometuron methyl has an acute oral Toxicity Category IV, no toxicity (EPA Human Hazards 

Toxicity Category; 40 CFR 162, July 3, 1975). It has an acute dermal toxicity Category II and an 

eye irritation Toxicity Category III. The sulfometuron methyl compound is slightly toxic to fish 

with an LC50 of 12.5 mg/L for both the rainbow trout and bluegill sunfish (EXTOXNET 1996g). 

Although it may not be a threat to adult fish, the compound is highly toxic to the embryo hatch 

stage of fathead minnow at low concentrations of 0.71 mg/L (SERA 2000). The LC50 for 

Daphnia Magna is 125 mg/L (EXTOXNET 1996g).

There is little potential for bioaccumulation. Bluegill sunfish exposed to 1 mg/L for 28 days had 

no accumulation of the compound in their muscle or viscera (SERA 1998b). The compound is 

absorbed by the gastrointestinal tract and is broken down and excreted.

In general, workers will be exposed to sulfometuron methyl at higher levels of exposure than 

members of the general public and will be subject to greater potential risk. The upper limit of 

general exposure scenarios for backpack and boom spray applications results in a modest 

excursion above the provisional reference dose. These upper limits of exposure are constructed 

using the highest anticipated application rate, the highest anticipated number of acres treated per 

day, and the upper limit of the occupational exposure rate. If any of these conservative 

assumptions are modified (e.g., the compound is applied at the typical rather than the maximum 

application rate) the hazard indices would be at or below the reference dose or level of concern. 

Given the conservative nature of the reference dose itself, it is unlikely that there would be any 

signs of toxicity in workers applying sulfometuron methyl. For the general public, none of the 

longer term exposure scenarios approach a level of concern. In addition, none of the 

acute/accidental scenarios exceed a level of concern, based on central estimates of exposure, 

although a hazard index of unity is reached for the consumption of water after an accidental spill. 

The potential of sulfometuron methyl to induce reproductive effects—fetal mortality or 

abnormalities—suggest that pregnant women should avoid exposure to sulfometuron methyl. 

Based on the available dose/duration/severity data, however, it appears that exposure levels below 

those associated with the most sensitive effect (i.e., anemia) are not likely to be associated with 

reproductive toxicity. In addition, the available dose-response data regarding the reproductive 

effects of sulfometuron methyl in rabbits are weak (i.e., there are no statistically significant doseresponse relationships). The major study on which the hazard identification for reproductive 

effects is based, nonetheless, did note adverse reproductive effects at all dose levels of 

sulfometuron methyl exposure. Thus, although the qualitative decision to consider sulfometuron 

methyl a potential reproductive hazard may be regarded as extremely conservative, this 

determination seems prudent at this time.

The primary concern with sulfometuron methyl is that the application rate used to control the 

growth of target plant species is many times greater than the rate that may damage non-target 

species. Various kinds of exposure to non-target terrestrial plant species are considered, including 

direct spray, drift, wind erosion, and water erosion. Direct deposition through unintentional direct 

spraying presents a clear hazard in the application of sulfometuron methyl and almost all other 

herbicides. If non-target plants are accidentally sprayed at application rates that effectively 

control weeds, they are likely to be damaged, particularly in the upper ranges of anticipated 

application rates. Although spray drift could cause damage to vegetation, the impact would be 

limited and damage to non-target species probably could be minimized or avoided during the 

application process. Wind erosion is, at least potentially, a much more serious problem. Although 

no significant transport of sulfometuron methyl by soil erosion is anticipated under conditions 

that inhibit wind erosion of soil (i.e., a rough gravely surface or heavy vegetation covering or 

Final Environmental Impact Statement – Invasive Plant Control Project 271
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

when the sulfometuron methyl is incorporated relatively fast into the root zone by irrigation or 

rainfall), substantial erosion could occur under arid conditions in flat sandy or otherwise fine soil 

with a sparse covering of vegetation. Consistent with a reported incident in the literature, the 

transport of sulfometuron methyl by wind erosion of soil could lead to overt signs of damage in 

non-target vegetation. Offsite soil contamination with sulfometuron methyl by soil runoff is 

another mechanism that might cause effects in nontarget vegetation. Damage due to inadvertent 

contamination of soil with sulfometuron methyl generally will take from a few to several months 

to recover. Under some extreme conditions, recovery could occur within a matter of weeks; 

however, under other conditions, recovery might take more than 1 year and possibly several 

years. Like terrestrial plants, aquatic plants are very sensitive to sulfometuron methyl. Under 

normal and anticipated conditions of use, it is plausible that sulfometuron methyl contamination 

of water will cause adverse effects (i.e., reduction in growth and biomass) in sensitive aquatic 

macrophytes and algal species. The duration of these effects will depend mostly on the dilution 

rates of the contaminated body of water and weather conditions. For less sensitive species, the 

occurrence of adverse effects is far less likely. For relatively brief periods shortly after 

application, a much broader range of aquatic plants might be affected, and the duration of these 

effects is likely to vary considerably.

Compared with the potential effects on non-target vegetation, the risk characterization for 

terrestrial animals is of less concern. The weight of the data suggests that frank or even 

observable effects in terrestrial mammals exposed to sulfometuron methyl are not expected under 

most conditions of use. At the highest anticipated application rate and under conservative 

assumptions of exposure, short-term and probably transient changes in the blood are plausible for 

mammals that consume vegetation primarily. Nonetheless, the possibility of adverse reproductive 

effects in some potentially sensitive species cannot be dismissed. These qualifications and 

uncertainties cannot be resolved with the available data. Similarly, while the data on potential 

effects on soil microorganisms is far less complete than the data on non-target vegetation or 

terrestrial animals, this paucity of information has relatively little impact on the risk assessment. 

For aquatic animals, the risk characterization is unambiguous. There is no evidence that 

concentrations of sulfometuron methyl in the range of those likely to be found in ambient water 

after any plausible application program or those that might occur after a spill will cause adverse 

effects in fish or aquatic invertebrates. As with any attempt to characterize effects in numerous 

species using data on a relatively small number of species, this risk characterization is tempered 

by the limited number of test species and the paucity of field studies on aquatic animals. 

Nonetheless, this assessment is based on apparently well conducted studies that include sensitive 

life stage testing of both invertebrates and fish. Notwithstanding the low potential for direct toxic 

effects on aquatic animals, effects on fish and invertebrate populations are plausible, given the 

toxicity of sulfometuron methyl to aquatic plants.

Picloram

Picloram generally affects members of the Asteraceae (composite), Fabaceae (legume), 

Polygonaceae (buckwheat), and Apiaceae (parsley) families. Members of the Brassicaceae

(mustard), Liliaceae (lily), and Scrophulariaceae (figwort) families are less affected. The 

selectivity of picloram is rate and season dependent. Spring and fall applications at 1 pint per acre 

would have a short-term effect on native broadleaf plants (SERA 2003c).

Fall applications would be more selective at rates up to 11⁄2 pints per acre because many nontarget 

native plants are dormant and herbicide uptake is reduced. Rates under 1 quart per acre generally 

272 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

do not kill woody plants. Impacts to nontarget native plants from picloram would be offset by 

reduction of weed competition and an increase in vigor and abundance of surviving species. 

Picloram can control weeds for 2 to 4 growing seasons depending on weed biology and site 

conditions that would allow plant communities to become more resistant to weed invasion.

Picloram is the active ingredient in a number of herbicide formulations including Tordon®, 

Grazon®, and Pathway®. Tordon K®, Tordon 22K®, and Grazon PC® are picloram salt 

formulations and inert ingredients, primarily water and dispersing agents. Tordon RTU® and 

Grazon P+D® include picloram and 2,4-D salts as well as inert ingredients (Tu et al. 2001, 

Infoventures 1995a).

Picloram can stay active in soil for relatively long periods of time, maintaining toxicity to plants 

for up to 3 years. The half-life can vary from 1 month to 3 years (Tu et al. 2001) though long-term 

buildup in soil generally does not occur. Carbon dioxide is the major end product of breakdown 

of picloram (Infoventures 1995a).

Picloram does not bind strongly with soil particles and is not degraded rapidly in the environment 

allowing it to be highly mobile and persistent. However, in soils with high clay content or organic 

matter, adsorption is increased and its leaching capacity is reduced. In Picloram application, 

Watson et al. (1989) cited several past studies where 1 to 6 percent of picloram applied mobilized 

from the treatment areas and reached drainage channels.

Picloram is water-soluble and is readily degraded when exposed to sunlight in water or on the 

surface of plant foliage and soils (Tu et al. 2001). Photodegradation will occur most rapidly in 

clear, moving water (Tu et al. 2001). Studies have found the half-life of Picloram in water was 2 

to 3 days. Picloram can move offsite through surface or subsurface runoff and may also “leak” 

out of the roots of treated plants (SERA 2003c).

Picloram is almost nontoxic to birds, relatively nontoxic to bees, and low in toxicity to mammals. 

Mammals excrete most picloram residues unchanged and it does not bioaccumulate in animal 

tissue. Formulated products are generally less toxic than picloram (Infoventures 1995i). Tu et al. 

(2001) and Infoventures (1995a) report an acute oral LD50 for rats for picloram of greater than 

4,000 milligrams per kilogram (mg/kg). LD50s were reported to be greater than 2,500 and 5,000 

mg/kg for mallard ducks and the bobwhite quail, respectively. The acute dermal LD50 in rabbits 

was reported to be greater than 2,000 mg/kg. In laboratory tests with rabbits, picloram was not 

shown to be a skin irritant, but was a moderate eye irritant. Weight loss and liver damage in 

mammals has been reported following long-term exposure to high concentrations of picloram. 

Picloram is classified as a Class E carcinogen, a compound having evidence of 

noncarcinogenicity (Felsot 2001). Picloram showed no evidence of birth defects in rats or rabbits, 

and it was negative in two tests for mutagenicity (Infoventures 1995a). Male mice receiving 

picloram at dietary doses of 1,000 to 2,000 mg/kg/day over 32 days showed no clinical signs of 

toxicity or changes in blood chemistry, but females did show decreased body weight and 

increased liver weights. Liver effects were also seen in rats at very high doses of 3,000 mg/kg/day 

over an exposure period of 90 days, and above 225 mg/kg/day for 90 days.

Dogs, sheep, and beef cattle fed low levels of picloram for a month experienced no toxic effects. 

The ester and triisopropanolamine salt showed low toxicity in animal tests (EXTOXNET 1996a). 

Based on these studies, picloram does not appear to cause genetic damage or birth defects, has 

little or no effect on fertility and reproduction, and is not carcinogenic (Infoventures 1995a, Felsot 

Final Environmental Impact Statement – Invasive Plant Control Project 273
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

2001). There have been some concerns expressed that picloram acts synergistically with 2,4-D or 

other ingredients to cause chronic effects on wildlife.

There is some evidence that high concentrations of picloram and 2,4-D esters (fat soluble) have 

an additive, but not synergistic, effect as they can accumulate in the body. Picloram and 2,4-D are 

both rapidly excreted in an unchanged form by mammals, reducing the risk of their interaction. In 

one study, a test group of sheep was fed a single dose of picloram (72 mg/kg) and 2,4-D (267 

mg/kg) and others were fed a mixture of 7.2 mg/kg of picloram and 27 mg/kg 2,4-D for 30 days. 

There was no evidence of toxicity in any of these sheep (SERA 2003c). No adverse effects on 

endocrine activity have resulted from numerous studies conducted on mammals and birds to 

determine picloram toxicity values.

Note: 2,4-D proposed for use by the forest is an amine formulation which is water soluble. The 

risk assessments note formulations of picloram and 2,4-D that have higher suggested links to the

above-mentioned effects. One called Tordon 75D and another called Tordon 202C are not 

proposed for use by the Forest Service, as noted in the risk assessment.

The evidence indicates that the endocrine system in birds and mammals is not affected by 

exposure to picloram at expected environmental concentrations (SERA 2003c). One byproduct in 

the manufacture of picloram is hexachlorobenzene (HCB). As there has been some concern that 

HCB is carcinogenic, the EPA has required that there be a maximum concentration of 100 ppb 

(parts per billion) in picloram.

The manufacturer of Tordon has set its own limit at 50 ppb (50 micrograms per liter of 

formulation). In practice, the formulation is further diluted by a factor of 350 for spraying (Felsot 

2001). As a result, residues of picloram after spraying do not contain more HCB than background 

levels (Felsot 2001).

Toxicity to aquatic species varies depending on the formulation used and the species involved. 

Some salmonids (such as brook and brown trout) have been found to have a moderate tolerance 

for Picloram with LC50s (96 hour) of 91 and 52 parts per million (ppm), respectively (Norris et 

al. 1991). The LC50 (96 hour) reported for rainbow trout, bluegill sunfish and flathead minnow 

are 19.3 milligrams per liter (mg/L), 14.5 mg/L and 55 mg/L, respectively (EXTOXNET 1996a, 

SERA 2003c). Other reports present LC50s (96 hour) for cutthroat, rainbow and lake trout as 1.5, 

2.0, and 3.1 ppm, respectively (Woodward 1979). Mayes et al. (1987) evaluated the toxicity of 

Picloram to rainbow trout and found that the 96-hour LC50 for fry was 16.5 mg/L while the 

chronic NOEL based on egg hatching and growth was 0.55 mg/L. Growth and survival of fry was 

reduced at concentrations of 0.88 mg/L and 1.34 mg/L, respectively. Mayes et al. (1987) 

concluded that Picloram is not an acute or chronic hazard to aquatic species when used as 

directed. However, Woodward (1976) found even very low concentrations of Picloram (35 

micrograms per liter) reduced survivability and growth of lake trout fry after 60 days of exposure. 

Gersich et al. (1985) evaluated the acute and chronic toxicity of Picloram to the aquatic 

macroinvertebrate Daphnia Magna and found an LC50 (48 hour) of 68.3 mg/L and a chronic 

NOEL of 11.8 mg/L. The authors concluded that these findings corroborated the low toxicity 

rating of Picloram to wildlife and aquatic species. One study identified an LC50 (96 hour) for a 

tusked frog tadpole (Adelotus brevis) of 95 mg/L. Other aquatic macroinvertebrates such as 

Pteronarcys spp. (stonefly) and Gammarus spp. (crustacean) had LC50s (96 hour) of 48 and 27 

ppm, respectively (SERA 2003c).

274 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

Typical exposures to picloram do not lead to estimated doses that exceed a level of concern. For 

workers, no exposure scenarios, acute or chronic, exceeds the reference dose even at the upper 

ranges of estimated dose. For members of the general public, the upper limits for hazard quotients 

are below a level of concern except for the accidental spill of a large amount of picloram into a 

very small pond. Even this exposure scenario results in only a small excursion above the chronic 

RfD and is not likely to be toxicologically significant, because of the short duration of exposure 

relative to those considered in the derivation of the RfD. Thus, based on the available information 

and under the foreseeable conditions of application, there is no route of exposure or scenario 

suggesting that workers or members of the general public will be at any substantial risk from 

longer term exposure to picloram.

Based on the standard assumptions used in this and other Forest Service risk assessments, the 

contamination of picloram with hexachlorobenzene does not appear to present any substantial 

cancer risk even at the upper ranges of plausible exposure. Administratively, the Forest Service 

has adopted a cancer risk level of 1 in 1 million (1÷1,000,000) as a trigger that would require 

special steps to mitigate exposure or restrict and possibly eliminate use. Based on relatively 

protective exposure assumptions and at the typical application rate of 0.35 lb a.e. picloram/acre, 

the highest cancer risk is about 0.7 in 1 million—i.e., for workers involved in broadcast ground 

spray. At the upper range of the application rate—i.e., 1 lb a.e./acre—this risk would scale to 2 in 

1 million. This is not, however, an appropriate approach for risk scaling because it would assume 

that the same worker applies picloram at an atypically high application rate over a lifetime. For 

members of the general public, the highest cancer risk is estimated at 0.1 in 1 million at the 

typical application rate of 0.35 lb a.e./acre. Scaled to an application rate of 1 lb/acre, the cancer 

risk would be about 0.3 in 1 million.

Picloram is an herbicide and the most likely damage to nontarget species will involve terrestrial 

plants. As is the case with any herbicide, the likelihood of damage to nontarget plant species is 

related directly to the difference between the sensitivity of target species—which dictates the 

application rate—and the sensitivity of the potential nontarget species. Sensitive plant species 

could be adversely affected by the offsite transport of picloram under a variety of different 

scenarios depending on local site-specific conditions that cannot be generically modeled. If 

picloram is applied in the proximity of sensitive crops or other desirable sensitive plant species, 

site-specific conditions and anticipated weather patterns will need to be considered if unintended 

damage is to be avoided. More tolerant plant species are not likely to be affected unless they are 

directly sprayed or subject to substantial drift. A detectable inhibition of the activity of soil 

microorganisms is also likely at application rates used in Forest Service programs. These changes 

could lead to an increase in the persistence of picloram in soil and/or a more general decrease in 

microbial activity. That this inhibition would be associated with detectable changes in soil 

productivity or other undesirable gross effects is much less certain.

A detectable inhibition of the activity of soil microorganisms is likely at application rates used in 

Forest Service programs. These changes could lead to an increase in the persistence of picloram 

in soil and/or a more general decrease in microbial activity. That this inhibition would be 

associated with detectable changes in soil productivity or other undesirable gross effects is much 

less certain. The potential for adverse effects on other terrestrial nontarget animal species appears 

to be remote. The weight of evidence suggests that no adverse effects in terrestrial animals are 

plausible using typical or even very conservative worst-case exposure assumptions. There is 

substantial variability in the toxicity of picloram to aquatic species. While this variability adds 

uncertainty to the dose-response assessment, it has no substantial impact on the risk 

Final Environmental Impact Statement – Invasive Plant Control Project 275
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

characterization. None of the hazard indices for fish, aquatic invertebrates, or aquatic plants 

exceed a level of concern. The risk characterization for both terrestrial and aquatic species is 

limited by the relatively few animal and plant species on which data are available compared to the 

large number of species that could potentially be exposed. This limitation and consequent 

uncertainty is common to most if not all ecological risk assessments.

Triclopyr

Triclopyr is a selective systemic herbicide used to control woody and herbaceous broadleaf plants 

along rights-of-way, in forests, and in grasslands and parklands. It has little or no impact on 

grasses. Triclopyr controls target weeds by mimicking the plant hormone auxin, causing 

uncontrolled plant growth. It is absorbed through the roots, foliage and green bark of plants. 

Within the plant, triclopyr mimics an auxin growth hormone—indoleacetic acid—causing 

uncontrolled and disorganized growth of the plant and plant cells, leading to withering and death. 

Grasses are able to quickly convert triclopyr to compounds that do not mimic growth hormones.

Triclopyr herbicides come in one of two formulations, a triethylmine salt (triclopyr amine or salt) 

or a butoxyethyl ester (triclopyr ester). Trade names for triclopyr herbicides are Access, 

Crossbow, ET, Garlon, PathFinder, Redeem, Rely, Remedy and Turflon.

Triclopyr is particularly effective at controlling woody species with cut-stump or basal bark 

treatments. Triclopyr ester formulations are especially effective against root- or stem-sprouting 

species, and so likely species to treat on the two forests include saltcedar (Tamarisk spp.) and 

Siberian elm (Ulmus pumila) because triclopyr remains persistent in plants until they die.

There are two basic formulations of triclopyr—a triethylamine salt and butoxyethyl ester. In soils, 

both formulations degrade to the parent compound, triclopyr acid. Degradation occurs primarily 

through microbial metabolism, but photolysis and hydrolysis can be important as well.

The average half-life of triclopyr acid in soils is 30 days. Offsite movement through surface or 

subsurface runoff is a possibility with triclopyr acid, as it is relatively persistent and has only 

moderate rates of adsorption to soil particles. In water, the salt formulation is soluble and, with 

adequate sunlight, may degrade in several hours. The ester is not water-soluble and can take 

significantly longer to degrade. It can bind with the organic fraction of the water column and be 

transported to the sediments.

Both the salt and ester formulations are relatively nontoxic to terrestrial vertebrates and 

invertebrates. The ester formulation, however, can be extremely toxic to fish and aquatic 

invertebrates. Because the salt cannot readily penetrate plant cuticles, it is best used as part of a 

cut-stump treatment or with an effective surfactant. The ester can be highly volatile and is best 

applied at cool temperatures on days with no wind. The salt formulation (Garlon 3A®) can cause 

severe eye damage.

It is active in soil and rapidly broken down by microbes, particularly in warm climates. The 

average half-life of the compound in soils is 46 days, with a range of 30 to 90 days (Infoventures, 

1995i) in natural soil and aquatic environments, the ester and amine salt formations convert to the 

acid, which is neutralized to a nontoxic salt.

276 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

Even though offsite movement of triclopyr acid through surface or subsurface runoff is a 

possibility, triclopyr is one of the most commonly used herbicides against woody species in 

natural areas.

On preserves across the U.S., triclopyr has provided good control of tree-of-heaven (Ailanthus 

altissima), saltcedar (Tamarix spp.), glossy buckthorn (Frangula alnus), common buckthorn 

(Rhamnus cathartica), sweet fennel (Foeniculum vulgare), Brazilian peppertree (Schinus 

terebinthifolius), and Chinese tallow tree (Sapium sebiferum). The Nature Conservancy Preserves 

in Hawaii have successfully used triclopyr to control blackwood acacia (Acacia melanoxylon), 

bush honeysuckle (Lonicera maackii), Chinese banyan (Ficus microcarpa), corkystem 

passionflower (Passiflora suberosa), eucalyptus (Eucalyptus globulus), Florida prickly 

blackberry (Rubus argutus), Mexican weeping pine (Pinus patula), Monterey pine (Pinus 

radiata), strawberry guava (Psidium cattleianum), tropical ash (Fraxinus uhdei), and velvet leaf 

(Miconia calvescens). Triclopyr can also be used in forest plantations to control brush without 

significant impacts to conifers (Kelpsas & White). Spruces (Picea spp.) can tolerate triclopyr, but 

some species of pine (Pinus spp.), however, can only tolerate triclopyr during the dormant fall 

and winter months (Tu et al. 2001). Others suggest the effectiveness of triclopyr on Siberian elm 

(Ulmus pumila).

Both the salt and ester formulations are relatively nontoxic to terrestrial vertebrates and 

invertebrates. The ester formulation, however, can be extremely toxic to fish and aquatic 

invertebrates. Because the salt cannot readily penetrate plant cuticles, it is best used as part of a 

cut-stump treatment or with an effective surfactant.

The ester can be highly volatile and is best applied at cool temperatures on days with no wind.

The two formations act very differently in soils and water. The salt formations do not readily 

adsorb with soil and are water-soluble and, therefore, quite mobile. The ester formations bind 

readily with organic material in soils and are not water-soluble causing them to be less mobile.

However, both rapidly degrade to the parent compound—triclopyr acid—by photolysis, microbial 

metabolism and hydrolysis. Triclopyr acid has intermediate soil adsorption capacity and binds 

with clay particles and organic matter in the soil. Leaching potential into ground water and 

surface water is moderate. Triclopyr acid is further broken down through photodegradation, 

microbial degradation and chemical decomposition. The acid can have as short a half-life as 2 

hours in soil (McCall and Gavit 1986) and 12 hours in water (Johnson et al. 1995) on a sunny 

day, due to photolysis and microbial activity.

Other reports of the half-life of the acid in soils vary from 3.7 to 314 days, with an average of 30 

days. Its half-life in water may range from 2.8 to 14.1 hours (EXTOXNET 1996e). The 

degradation time depends on many variables such as moisture, temperature, pH and light 

intensity. While concentrations of triclopyr acid in soil may degrade, the acid tends to remain in 

plant tissue until they die or drop their leaves (Newton et al. 1990). This litter adds a new source 

of triclopyr acid to the soil at time of litter drop. Triclopyr acid itself degrades to several 

metabolites, the major product being Trichloropyridinol (TCP). TCP further degrades to carbon 

dioxide and organic matter, and has a half-life of 30 to 90 days (Infoventures 1995g).

Triclopyr has an acute oral toxicity of slightly toxic (EPA Human Hazards Risk Category III), 

acute dermal toxicity of slightly toxic (Toxicity Category III), and is a slight to moderate eye 

irritant (Toxicity Category III to IV) (Infoventures, 1995i). Triclopyr has not been shown to cause 

Final Environmental Impact Statement – Invasive Plant Control Project 277
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

birth defects or cancer, and has little or no effect on fertility and reproduction (Infoventures 

1995g). The salt formulation (Garlon 3A®) can cause severe eye damage.

Triclopyr acid and the salt formation herbicide are only slightly toxic to fish. The LC50 for the 

acid is 117 mg/L for rainbow trout and 148 mg/L for bluegill sunfish (Tu et al. 2001). The LC50 

for the salt formation is 552 mg/L and 891 mg/L for rainbow trout and bluegill sunfish, 

respectively (Tu et al. 2001). The ester formulation, however, is highly toxic to fish, with an 

LC50 of 0.74 mg/L for rainbow trout and 0.87 mg/L in bluegill sunfish (SERA 2003b). The ester 

formulation was also found to be toxic to some species of frog tadpoles (LC50 = 1.2 mg/L). 

Tadpoles exposed to one-half or one-quarter the lethal dose levels exhibited loss of avoidance 

behavior when prodded, which may affect survival (SERA 2003b). The high toxicity of the ester 

formulation is compounded by the fact that this form is hydrophobic and, therefore, is readily 

absorbed into fish tissue where it is degraded to triclopyr acid. This provides a means by which 

fish can acquire high levels of triclopyr acid that may reach or exceed the LC50. Although the 

ester formulation degrades rapidly to triclopyr acid, Kreutzweiser et al. (1994) has shown that 

there is a significant chance that fish may acquire acute lethal doses when exposed to high 

concentrations of the ester formulation for more than 6 hours. Application procedures of the ester 

formulation (e.g., overspray) and factors affecting the rate of breakdown of ester formulations 

(soil type, moisture, temperature, pH and light) determine the risk of lethal exposure for fish. 

Triclopyr is practically nontoxic to aquatic invertebrates. The triclopyr LC50 for Dafphnia Magna

is 1,140 mg/L (Infoventures 1995i, SERA 2003b). After treating a stream with Garlon, a study 

found aquatic invertebrate species composition did not significantly change in treated and control 

sites (SERA 2003a).

Triclopyr has little if any potential to bioaccumulate. The bioconcentration factor in whole 

bluegill sunfish is 1.08 (EXTOXNET 1996e). Petty et al. (2001) found that concentrations of 

triclopyr and its byproduct, TCP, in fish were cleared from their systems in relation to the 

concentrations found in the water.

Triclopyr is a slightly toxic compound (SERA 2002, SERA 2003b). The oral LD50 levels in rats 

have been reported in the range of 630 to 729 mg/kg (EXTOXNET 1996e). Acute toxicity LD50 

values for mammals are reported to be 310 to 713 mg/kg, and ducks were reported to have an oral 

LD50 of 1,698 mg/kg (Infoventures, 1995b). The acute dermal LD50 has been reported to be 

>2,000 mg/kg in rabbits. Triclopyr is considered to be a slight irritant to the skin and eye. Studies 

summarized in EXTOXNET (1996e), Infoventures (1995i) and SERA (2002/2003a) indicated 

that triclopyr does not pose a carcinogenic, mutagenic, reproductive, developmental risk to 

animals or humans at doses anticipated for this project.

There is no indication that workers will be subject to hazardous levels of triclopyr at the typical 

application rate and under typical exposure conditions. Nonetheless, at the upper range of 

exposures, all application methods exceed the level of concern based on the chronic reference 

dose (but not the acute RfD). Thus, for workers who may apply triclopyr repeatedly over a period 

of several weeks or longer, it is important to ensure that work practices involve reasonably 

protective procedures to avoid the upper extremes of potential exposure. At higher application 

rates, particularly rates that approach the maximum application rate of 10 lbs/acre, measures 

should be taken to limit exposure. These measures would need to be developed on a case-by-case 

basis depending on the specific application rates that are used and the type of the applications that 

are employed. For members of the general public, the risk characterization is relatively 

unambiguous at the typical application rate and under the foreseeable conditions of exposure. 

278 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

There is no route of exposure or exposure scenario suggesting that the general public will be at 

risk from longer term exposure to triclopyr. Even at the maximum projected application rate of 10 

lbs/acre, the only long-term scenario that exceeds the level of concern is the consumption of 

contaminated fruit. Several acute exposures also lead to exposure to levels that are above the level 

of concern. For instance, accidental spray over the lower legs as well as contacting contaminated 

vegetation both exceed the level of concern at the central estimate of exposure. When the highest 

application rate is considered (10 pounds per acre), all of dermal exposures exceed the level of 

concern. These dermal exposure assessments are extremely conservative and designed to identify 

which possible types of exposure would be most hazardous. For triclopyr, such scenarios include 

dermal contact and accidental spills into water.

Triclopyr degrades into a soil metabolite referred to as TCP. The U.S. EPA (1998a, 2002) has 

conducted extensive analyses of dietary exposure to TCP from the use of triclopyr as well as the 

aggregate risks from exposure to TCP from the use of both triclopyr and chlorpyrifos. While these 

dietary exposures appear to be substantially below a level of concern, the risk assessment by EPA 

does not specifically address concerns for contamination of water with TCP as a soil metabolite 

of triclopyr and chlorpyrifos. As part of the current risk assessment, exposures to TCP based on 

modeling of water contamination from the application of both triclopyr and chlorpyrifos indicate 

that the peak exposure to TCP in water is below the concentration associated with the chronic risk 

value for TCP. Thus, there is no basis for asserting that the use of triclopyr with or without the use 

of chlorpyrifos will result in hazardous exposures of humans to TCP.

Some effects may be anticipated on nontarget vegetation under some conditions. Because of the 

relatively low toxicity of triclopyr TEA compared to triclopyr BEE, the risk characterization for 

triclopyr TEA is much less severe than that of triclopyr BEE. At an application rate of 1 lb/acre, 

potentially damaging runoff from triclopyr TEA would be anticipated only at relatively high 

rainfall rates. While a lesser amount of triclopyr BEE will runoff, the higher toxicity of triclopyr 

BEE leads to hazard quotients above the level of concern starting are relatively modest rainfall 

rates—i.e., 20 to 25 inches per year. At an application rate of 10 lbs per acre, damage due to 

runoff after the application of triclopyr TEA would be expected at annual rainfall rates as low as 

20 inches per year. For triclopyr BEE, the hazard quotients are of concern for all but the most arid 

areas. The potential impact of offsite drift of triclopyr varies substantially with the application 

rate. At an application rate of 1 lb. a.e./acre, potentially damaging exposures could occur within 

about 100 feet of the application site. At the maximum application rate of 10 lbs. a.e./acre, 

damaging drift could occur at distances of over 1,000 feet from the application site. The risk 

characterization for aquatic organisms differs for triclopyr TEA and triclopyr BEE. For triclopyr 

TEA, risks to aquatic species are low over the entire range of application rates that may be used 

in Forest Service programs. At the highest projected application rate, the hazard quotient for acute 

risks to aquatic plants from runoff into streams would reach unity. For acute risks to aquatic 

plants in the application of triclopyr TEA directly to water for the control of submerged weeds, 

the hazard quotient of 0.6 is based on the targeted water concentration given on the product label. 

Although triclopyr BEE is much more toxic to aquatic species than triclopyr TEA or triclopyr 

acid, the projected levels of exposure are much less even for acute scenarios 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. Nonetheless, triclopyr BEE is projected 

to be somewhat more hazardous when used near bodies of water where runoff to open water may 

occur. At an application rate of 1 lb. a.e./acre, the level of concern for acute exposure to aquatic 

plants is exceeded at the upper range of projected concentrations. At an application rate of 10 lbs.

Final Environmental Impact Statement – Invasive Plant Control Project 279
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

a.e./acre, the level of concern for acute exposure to aquatic plants is exceeded at the central 

estimate as well as the upper range of projected concentrations.

For terrestrial mammals, the typical hazard quotient does not exceed the level of concern for any 

exposure scenarios. At the upper range of exposures, the level of concern is exceeded for large 

mammals and large birds consuming contaminated vegetation exclusively at the application site. 

At higher application rates, concern for exposure scenarios involving the consumption of 

contaminated vegetation is augmented substantially. At the maximum application rate of 10 

lbs./acre, the hazard level is exceeded in other scenarios, including the direct spray of a small 

mammal assuming 100 percent absorption, a large mammal consuming contaminated vegetation, 

and a small bird consuming contaminated insects. The level of concern is exceeded for the 

chronic consumption of vegetation for a large mammal and a large bird and the upper range on 

the hazard exposure is tenfold over the level of concern. This risk assessment is consistent with 

the risk characterization given by U.S. EPA indicating that contaminated vegetation is a primary 

concern in the use of triclopyr, and that high application rates will exceed the level of concern for 

both birds and mammals in longer term exposure scenarios. The risk characterization for TCP is 

considered quantitatively only for fish because toxicity data are available only for fish. At the 

typical application rate, the worst-case exposure levels are below the level of concern. At the 

maximum application rate of 10 lbs. a.e./acre, the hazard quotients would be a factor of 10 higher 

and the hazard level for longer term exposure would be substantially more. Thus, if triclopyr is 

applied at higher rates of exposure in areas where surface water contamination is plausible, sitespecific modeling and/or environmental monitoring would be useful to ensure and verify that 

concentrations of TCP do reach harmful concentrations. Concentrations of TCP in surface water 

after the application of triclopyr at 1 lb. a.e./acre and chlorpyrifos at 1 lb. a.e./acre are well below 

a level of concern. Thus, the concern for TCP residues in surface water appears to be associated 

with high application rates of triclopyr rather than applications triclopyr and chlorpyrifos in the 

same area.

Inert/Other Ingredients

Herbicide manufacturers add inert ingredients (or “other ingredients”) to enhance the action of 

the active ingredient. Inert ingredients may include carriers, surfactants, preservatives, dyes, and 

antifoaming agents among other chemicals. Inert refers to any ingredient that is not intended to 

affect the target species and does not convey any information regarding the toxicity of the 

chemical (EPA 2003a). The term “inert” is found in the Federal law governing pesticide use, but 

the EPA has allowed manufacturers to use the term “Other” ingredients instead of inert in order to 

reflect the circumstances where ingredients in an herbicide formulation may have some active 

effect or may be active in other ways than the effects to the target plants. 

Federal law does not require listing these ingredients unless they have been listed as hazardous 

chemicals. “The lack of disclosure of specific inert ingredients indicates that none of the inerts 

present at a concentration of 0.1 percent or greater is classified as hazardous” (SERA 1997b). 

Listed inert ingredients for the herbicide formulations being considered include water, ethanol, 

isopropanol, isopropanolamine, kerosene, polyglycol 26-2, and polyoxyethylamine (USFS 1992,

USFS 1997, SERA 1995, 1996, 1997a, 1997b, 1998a, 1998b, 1999a, 1999b, 2000, 2001, 2002, 

2003a, 2003b, 2003c, 2004a, 2004b, 2004c, 2004d, 2004e, 2004f). None of these chemicals are 

listed as Level 1 or Level 2 compounds (i.e., “Inert Ingredients of Toxicological Concern” or 

“Potentially Toxic Inert Ingredients,” respectively) (EPA 2003a). Although there is some concern 

regarding the toxicity of polyoxyethylamine (POEA), a surfactant included in a formulation of 

280 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

glyphosate—Roundup—(Ecobichon 2001; SERA 2003a) there is no anticipated increase in 

toxicity of the glyphosate formulation as a result of POEA (SERA 1997c).

Many manufacturers consider the inerts in their herbicide formulations to be Confidential 

Business Information (CBI) and do not list specific ingredients in labels. The EPA registration 

process as well as the risk assessments, have access to this information, but are not allowed to 

disclose it. EPA regulations require disclosure if these “other ingredients” are considered 

hazardous.

The risk assessments have reviewed the other ingredients found in the herbicide formulations 

proposed for use. Details are found in the risk assessments, with a summary provided here (Note 

that citations in this summary refer to citations in the risk assessments, not the FEIS).

Table 66. Herbicide formulations, impurities, other ingredients

Herbicide 

Name 

Hazard Identification

1 2,4-D

(3-30)

Impurities, adjuvants and metaobolites are considered together in the risk assessment. 

Because the toxicity studies of the 2,4-D used in the risk assessment would include the 

impurities, effects are encompassed. Contamination with chlorinated dioxins is a 

concern. Agent Orange used in Vietnam contained 2,3,7,8-TCDD as an impurity. 

Commercial formulations of 2,4,5-T also contained 2,3,7,8-TCDD as well. 2,4-D 

formulations were shown not to contain 2,3,7,8-TCDD. Some commercial samples of 

2,4-D have been shown to contain polychlorinated dibeno-p-dioxins at less than 1 

microgram per liter (ppb). Greater levels from 0.1 to 23 mg/L (ppm) have been found 

in 2,4-D esters. Additional studies are not available.

2 Clopyralid

(3-8)

Inert ingredients in Transline are monoethanolamine and isopropyl alcohol, both 

approved food additives, and there is no evidence that these compounds will materially 

impact the risks associated with the use of clopyralid. Polyglcycol is classified as an 

inert/other ingredient that has insufficient information to categorize it as either 

hazardous or non-toxic. Polyglcycol inhibited oxidative function in vitro, but 

implications for potential effects in humans at plausible levels of exposure are not 

apparent.

3 Chlorsulfuron

(3-8)

The formulation of chlorsulfuron used by the Forest Service contains materials other 

than chlorsulfuron that are included as adjuvants to improve either efficacy or ease of 

handling and storage. The identity of these materials is confidential. The inerts were 

disclosed to the U.S. EPA and were reviewed in the preparation of this risk 

assessment. All that can be disclosed explicitly is that none of the additives are 

classified by the U.S. EPA as toxic. 

4 Dicamba

(3-12)

As noted in Section 2.2 of the dicamba risk assessment, the identity of inerts in both 

Banvel and Vanquish has been disclosed to the U.S. EPA and this information has 

been reviewed as part of this risk assessment. This information, however, is protected 

under FIFRA (Section 10). Other than to state that no apparently hazardous materials 

have been identified, which is consistent with the MSDS for both Banvel and 

Vanquish (C&P Press 2003), the information on the inerts in these formulations cannot 

be detailed. The potential toxicologic significance of inerts in Banvel can be inferred 

from a comparison of the toxicity data on Banvel with corresponding toxicity data on 

dicamba, where in terms of acute lethal potency, no substantial differences are 

apparent between the a.i. in Banvel (the DMA salt of dicamba) and the Banvel 

formulation. Some differences are noted in severity of skin irritation. For Vanquish, 

commercial searches of the studies available in the FIFRA CBI files as well as 

supplemental searches that were kindly provided by the U.S. EPA Office of Pesticides 

did not identify specific mammalian toxicity studies using Vanquish.

5 Glyphosate

(3-20)

Various glyphosate formulations contain a polyethoxylated tallow amine (POEA) 

surfactant at a level of up to about 20 percent (200 g/L) and Roundup Pro contains a 

phosphate ester neutralized polyethoxylated tallow amine surfactant at a level of 14.5 

Final Environmental Impact Statement – Invasive Plant Control Project 281
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

Herbicide 

Name 

Hazard Identification

percent (145 g/L). Tallow contains a variety of fatty acids including oleic (37–43 

percent), palmitic (24–32 percent), stearic (20–25 percent), myristic (3–6 percent), and 

linoleic (2–3 percent) acids as well as small amounts of cholesterol, arachidonic, 

elaidic, and vaccenic acids (Budavari 1989). The other formulations of glyphosate 

recommend the use of a surfactant to improve the efficacy of glyphosate. There is an 

extensive amount of literature on glyphosate indicating that the addition of surfactants 

can greatly enhance phytotoxicity of herbicides. While surfactants are typically 

classified as “inert” ingredients in herbicides, these compounds are not toxicologically 

inert. Some surfactants may be more toxic than the herbicides with which they are 

used in some instances. While a number of surfactants may be used in conjunction 

with glyphosate, the most important to this risk assessment is the POEA or phosphate 

ester neutralized POEA. The risk assessment notes that POEA together with 

glyphosate may have a greater toxicity than either one by itself.

6 Hexazinone

(3-20)

Hexazinone is metabolized extensively in plants and animals, with little parent product 

recovered in tissue. The relative paucity of information about the toxicity of these 

metabolites does not have a significant impact on this risk assessment. 

There is no information available on the identity or toxicity of any impurities in 

hexazinone. Most toxicity studies use what is referred to as technical grade hexazinone 

containing about 98 percent hexazinone. Thus, the presence of impurities may be 

inferred. Although the lack of information on impurities adds some uncertainty to this 

risk assessment, the use of technical grade hexazinone in the toxicity studies on which 

the dose-response assessment is based (section 3.3) is likely to encompass any 

potential toxic effect of the impurities. 

Velpar L contains 40-45 percent ethanol. The toxicity of ethanol is extremely well 

characterized in humans, and the hazards of exposure include intoxication from acute 

exposure as well as liver cirrhosis and fetal alcohol syndrome (WHO 1988). For 

chronic exposure, the alcohol (30-35 percent w/w) contained in Velpar L is not likely 

to be of toxicological significance because of the rapid breakdown of alcohol in the 

environment and the relatively high levels of alcohol associated with chronic alcohol 

poisoning. For acute dermal exposure, ethanol will volatilize rapidly from the surface 

of the skin and toxicologically significant effects are not anticipated. Acute oral 

exposure is implausible, except in cases of accidental or suicidal ingestion. In such 

cases, the amount of ethanol could be significant.

The risk assessment notes that based on the acute toxicity of hexazinone, no adverse 

effects are anticipated. Thus, in the case of acute oral exposure to Velpar L, ethanol is 

the toxic agent of primary concern. This scenario is not of substantial concern to this 

risk assessment because, this type of exposure will be associated only with massive 

oral doses of Velpar L, which are plausible only with suicide attempts or other extreme 

exposure scenarios. Ethanol is a strong eye irritant, and the presence of ethanol may 

contribute to the irritant effects of Velpar L.

Based on references from the published literature, the major component of granular 

formulations of hexazinone appears to be clay. Based on the acute toxicity of these 

formulations relative to technical grade hexazinone, there is no indication that the 

carriers contribute to the toxicity of the granular formulations of hexazinone. For 

example, the acute LD50 values for a 20 percent gridball formulation range from 

about 6,300 to 12,000 mg/kg (Schneider and Kaplan 1983) or 1,260 to 2,400 mg/kg of 

hexazinone. As noted in section 3.1.2, the acute LD50 of technical grade hexazinone 

(98 percent pure) to the rat ranges from about 530 to 1,700 mg/kg (Kennedy 1984). 

Thus, if anything, the granular formulations of hexazinone appear to be slightly less 

toxic than hexazinone itself. This is also evident in the aquatic toxicity studies using 

formulations relative to hexazinone itself (section 4.3.3.1).

7 Imazapic

(3-7)

Plateau and Plateau DG, the commercial formulations of imazapic used by the Forest 

Service, contain materials other than imazapic that are included as adjuvants to 

improve either efficacy or ease of handling and storage. The identity of these materials 

is confidential. The additives were disclosed to the U.S. EPA and were reviewed in the 

preparation of this risk assessment. All that can be disclosed explicitly is that none of 

282 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

Herbicide 

Name 

Hazard Identification

the additives is classified by the U.S. EPA as toxic. This is consistent with the MSDS 

for Plateau (American Cyanamid Company 1997) that does not disclose the 

occurrence of toxic inerts in the formulation. Because none of the studies in 

experimental animals specifically tested Plateau or Plateau DG as the subject 

compound, a comparison of relative toxicity of technical imazapic and Plateau 

formulations cannot be used to assess the potential for inerts to affect the toxicity. 

Note that the identity of the inert ingredients in several herbicides has been obtained 

by the Northwest Coalition for Alternatives to Pesticides (NCAP) under the Freedom 

of Information Act and this information is publicly available at 

http://www.pesticide.org/FOIA/inertslinks.html. Imazapic, however, is not among the 

herbicides whose inert ingredients are listed by NCAP. As reviewed by Levine (1996), 

testing requirements for pesticide inerts that have been used as additives or adjuvants 

for many years are minimal, and the scarcity of information on the toxicity of inert 

ingredients in pesticide formulations is a general problem in many pesticide risk 

assessments. For new inerts, the U.S. EPA does require more extensive testing (Levine 

1996).

8 Imazapyr

(3-9)

Information on inerts in imazapyr formulations have been reviewed as part of this risk 

assessment. The risk assessment note toxicity studies in which information on inerts is 

specified. This information, however, is considered proprietary under FIFRA. Other 

than to state that no apparently hazardous materials have been identified, this 

information cannot be detailed. All of the technical formulations of imazapyr covered 

in this risk assessment involve the isopropyl or isopropanolamine salts of imazapyr. 

Little toxicity information is available on these compounds. Isopropanolamine is 

classified by the U.S. EPA (1998) as a List 3 inert. These are compounds that the U.S. 

EPA cannot classify as hazardous or non-hazardous based on the available 

information. Isopropyl alcohol, isopropylamine, and a large number of other 

derivatives of isopropanol are used as food additives and classified as GRAS 

(generally recognized as safe) compounds. Isopropyl alcohol is classified as a List 4B 

inert and isopropanolamine as well as a large number of related compounds are 

classified by U.S. EPA as List 3 inerts.

The Northwest Coalition for Alternatives to Pesticides (NCAP) has obtained 

information on the identity of the inerts in Arsenal AC from U.S. EPA under the 

Freedom of Information Act and has listed this information on the NCAP Web site 

(http://www.pesticide.org/FOIA). The only inert listed at this site other than water is 

glacial acetic acid (CAS No. 64-19-7). Dilute acetic acid is an approved food additive 

and is also classified as a GRAS compound (Clydesdale 1997). Acetic acid is a major 

component of vinegar and is a List 4B inert (U.S. EPA/OPP 2003). The minimal 

testing requirements for compounds that have been used as inerts or adjuvants for 

many years is a general problem in many pesticide risk assessments. For new inerts, 

the U.S. EPA does require more extensive testing (Levine 1996). Notwithstanding this 

uncertainty, none of the inerts used in any of the imazapyr formulations have been 

classified by the U.S. EPA as hazardous (List 1 or List 2).

9 Metsulfuron

(3-8)

Escort, the commercial formulation of metsulfuron methyl used by the Forest Service, 

contains materials other than metsulfuron methyl that are included as adjuvants to 

improve either efficacy or ease of handling and storage. 

The Northwest Coalition for Alternatives to Pesticides (NCAP) has obtained 

information on the identity of the inerts in Escort from U.S. EPA under the Freedom of 

Information Act and has listed this information on the NCAP Web site 

(http://www.pesticide.org/FOIA/clopyralid.html). The inerts listed on this Web site are 

sodium naphthalene sulfonate-formaldehyde condensate, mixture of a sulfate of alkyl 

carboxylate and sulfonated alkyl naphthalene (sodium salt), polyvinyl pyrrolidone, 

trisodium phosphate, and 3-9 sucrose. Both trisodium phosphate (CAS No. 7601-54-9) 

and sucrose (CAS No. 57-50-1) are classified by the U.S. EPA as List 4 inerts and,

therefore, are generally recognized as safe compounds and are approved as food 

additives (U.S. EPA 2003, Clydesdale 1997). There is no evidence to assert that these 

compounds will materially impact the risks associated with the use of metsulfuron 

Final Environmental Impact Statement – Invasive Plant Control Project 283
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

Herbicide 

Name 

Hazard Identification

methyl. Polyvinyl pyrrolidone (CAS No. 88-12-0) is classified as a List 3 inert.

In other words, there is insufficient information to categorize this compound as either 

hazardous (Lists 1 or 2) or non-toxic (List 4). Sodium naphthalene 

sulfonateformaldehyde condensate and the mixture of a sulfate of alkyl carboxylate 

and sulfonated alkyl naphthalene (sodium salt) were not identified in the EPA Inert 

List. Other naphthalene derivatives identified on the EPA Inert List are classified as 

List 3 or List 4; no naphthalene derivatives are classified as List 1 or List 2 inerts (U.S. 

EPA 2003). Thus, there is insufficient information available to assess the impact of

either polyvinyl pyrrolidone or the naphthalene derivatives on the risks associated with 

the use of metsulfuron methyl. However, as noted above, the toxicity of a formulated 

product that is comparable to Escort appears to be comparable to that of technical 

grade metsulfuron methyl (as noted in the risk assessment).Therefore, there is no 

plausible basis for asserting that these inerts are present in Escort in toxicological 

amounts. Although the identity of inerts has been disclosed, the quantity of the inert 

agents in Escort is confidential and cannot be disclosed. The amount of each inert 

agent in Escort was disclosed to the U.S. EPA (Du Pont 1985b, c) and reviewed in 

preparation of this risk assessment. As noted in Section 2.2, the manufacturer 

recommends that Escort be mixed with a surfactant for application. There is no 

published literature or information in the FIFRA files that would permit an assessment 

of toxicological effects of metsulfuron methyl mixed with surfactant.

10 Sulfometuron

(3-10)

The identity of all inerts in Oust XP has been disclosed to the U.S. EPA as part of the 

registration process and this information has been reviewed in the preparation of this 

risk assessment. This information is classified as CBI (confidential business 

information) under Section 7(d) and Section (10) of FIFRA. Except as noted below, 

this information cannot be specifically disclosed in this risk assessment. Since the 

inerts are not identified on the general product label (Du Pont 1999) or the general 

material safety data sheet (Du Pont 2002), the lack of disclosure indicates that none of 

the inerts are classified as hazardous. Nonetheless, as discussed by Levine (1996), the 

testing requirements for inerts are less rigorous than the testing requirements for active 

ingredients (i.e., sulfometuron methyl). The identity of inert ingredients for the 

sulfometuron methyl formulation Oust have been disclosed. The Northwest Coalition 

for Alternatives to Pesticides (NCAP) has obtained information on the identity of the 

inerts in Oust from U.S. EPA under the Freedom of Information Act and has listed this 

information on the NCAP Web site (http://www.pesticide.org/FOIA/clopyralid.html). 

The inerts listed in this Web site are sucrose, sodium salt of naphthalene-sulfonic acid 

formaldehyde condensate, polyvinyl pyrrolidone, sodium salt of sulfated alkyl 

carboxylated and sulfated alkyl naphthalene, and hydroxypropyl methylcellulose. 

However, the quantity of these inerts compounds in the formulation is confidential and 

cannot be disclosed. 

The potential risks associated with the inerts in Oust formulations are discussed in the 

risk assessment in the context of their use for forestry applications to control the 

growth of broadleaf weeds and grasses. Oust XP has no labeled uses for crops. 

According to the product label, when Oust XP is used in forest planting sites, periods 

of 60 days to13 months after treatment are recommended before planting conifers. The 

use of a surfactant with Oust XP is not recommended. A cautionary note on the 

product label indicates that if a surfactant is used with Oust XP, contact with tree 

foliage may result in tree injury or death. 

11 Picloram

(3-9)

The commercial formulation of picloram used by the Forest Service is in the form of 

the potassium salt of picloram. Both of the Tordon formulations also contain 

Polyglycol 26-2 (CAS No. 069029-39-6). This compound is classified by the U.S. 

EPA (2003) as a List 3 inert. In other words, there is insufficient information to 

categorize this compound as either hazardous (Lists 1 or 2) or 3-10 non-toxic (List 4). 

Other inerts used in Tordon K and Tordon 22K have been publicly disclosed by 

Northwest Coalition for Alternatives to Pesticides 

(http://www.pesticide.org/FOIA/picloram.html). These include emulsified silicone oil 

(CAS No. 63148-62-9), ethoxylated cetyl ether (CAS No. 9004-95-9), and potassium 

284 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

Herbicide 

Name 

Hazard Identification

hydroxide (CAS No. 1310-58-3). All of these compounds are classified by U.S. EPA 

(2003) as List 4B, inerts of minimal concern. Potassium hydroxide is a GRAS 

(generally recognized as safe) compound and is approved as an indirect food additive. 

Both formulations also contain water as an inert. The limited toxicity data on 

formulations of picloram do not suggest any substantial differences between the 

toxicity of the formulations and the toxicity of picloram when expressed in units of 

acid equivalents. 

12 Triclopyr

(3-12)

Garlon 3A contains the triethylamine salt of triclopyr (44.4 percent) as well as 

emulsifiers, surfactants, and ethanol. Garlon 4 contains the butoxyethyl ester (BEE) of 

triclopyr (61.6 percent) as well as inerts (38.4 percent) that include deodorized 

kerosene. As reviewed by U.S. EPA triclopyr TEA dissociates extremely rapidly to 

triclopyr acid and triethanolamine and triclopyr BEE hydrolyzes to triclopyr acid and 

2- butoxyethanol. Relatively little information is available on the toxicity of 

triethanolamine. This compound is classified as a list 3 inert by U.S. EPA (2001). The 

List 3 classification reflects the limited toxicity data on triethanolamine and indicates 

that U.S. EPA was not able to classify this compound as toxic (List 1), potentially 

toxic (List 2), or essentially nontoxic (Lists 4a or 4b). There is an extensive database 

on the toxicity of 2- butoxyethanol and much of the available information relating to 

potential human health effects has been reviewed. The risk assessment notes that In 

terms of a practical impact on the risk assessment, the most relevant factor is that both 

triethanolamine and 2-butoxyethanol will mineralize very rapidly in the environment –

i.e., be completely degraded to CO2. As discussed further in the assessment, this is not 

the case for triclopyr or TCP, a metabolite of triclopyr. Thus, the uncertainties 

associated with the toxicity of triethanolamine and the comparable toxicity of 2-

butoxyethanol to triclopyr have relatively little impact on this risk assessment. 

Because triclopyr and the TCP metabolite of triclopyr persist in the environment much 

longer than triethanolamine or 2-butoxyethanol, it is triclopyr and the TCP metabolite 

that are the major quantitative focus of the risk assessment. This approach is identical 

to the position taken in U.S. EPA. The toxicity of ethanol is extremely well 

characterized in humans, and the hazards of exposure include intoxication from acute 

exposure as well as liver cirrhosis and fetal alcohol syndrome. For chronic exposure, 

the alcohol contained in Garlon 3A will not be of toxicological significance because of 

the rapid breakdown of alcohol in the environment and the relatively high levels of 

alcohol associated with chronic alcohol poisoning. Similarly, alcohol is not likely to 

pose an acute toxic hazard. Approximately 15 mL of alcohol is contained in 1 oz of an 

alcoholic beverage containing 50 percent alcohol (100 proof) [0.5 @ 1 oz. @ 29.6 

mL/oz ï 14.8 mL]. This level may cause mild intoxication in sensitive individuals. 

Each mL of Garlon 3A contains 0.01 mL of ethanol. Therefore, 1,480 mL, or 

approximately 1.5 L, of Garlon 3A must be consumed to equal the amount of alcohol 

contained in 1 oz of an alcoholic beverage. 

The importance of kerosene in assessing the potential toxicity of Garlon 4 is more 

difficult to assess. Deodorized kerosene is classified by U.S. EPA as a List 3 Inert. 

This list contains pesticide inerts that the U.S. EPA considers lacking in toxicological 

data. At sufficiently high doses, kerosene can cause many gastrointestinal, central 

nervous system (CNS), and renal effects. Although some of the effects observed are 

consistent with the effects (e.g., diarrhea, lethargy, tremors, etc.) observed in mammals 

given large oral doses of Garlon 4, the same effects are observed in animals given 

triclopyr alone or Garlon 3A. The acute lethal dose of kerosene for humans ranges 

from approximately 2,000 to 12,000 mg/kg; the acute oral LD50 values in 

experimental mammals range from approximately 16,000 to 23,000 mg/kg. 

As discussed in the risk assessment, there is no information regarding the acute lethal 

potency of triclopyr to humans. In experimental mammals, acute oral LD50 values for 

triclopyr range from approximately 600 to 1,000 mg/kg. Thus, the acute lethal potency 

of kerosene is approximately 16 times less than the acute lethal potency of triclopyr. 

Given the relative potency of kerosene, the acute effects associated with exposure to 

Garlon 4 are probably attributable to triclopyr and not to kerosene. 

Final Environmental Impact Statement – Invasive Plant Control Project 285
Appendix 3 • Herbicides: Characteristics, Effects and Risk Assessments

Herbicide 

Name 

Hazard Identification

Although some components of kerosene are known to be carcinogenic to humans (e.g., 

benzene) kerosene is not classified as a carcinogen, and quantitative risk assessments 

have not been conducted on kerosene.

286 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 4 • Effects of 

Nonherbicide Weed Control Methods

Biological Control

Biological control agents are extensively tested to ensure that they have a very narrow host range 

and would not pose a serious threat to nontarget plants. The testing process for a biological 

control agent is typically 3 to 4 years and involves 50 to 75 test plant species. Final approval is 

granted by USDA, Animal Plant Health Inspection Service. Although extensive screening and 

testing reduces the potential for injury to native plants, biological control is not risk free. Agents 

may attack plants closely related to the host weed.

Biological control is the use of animals, fungi, or other microbes to feed upon, parasitize or 

otherwise interfere with a targeted pest species. Successful biological control programs usually 

significantly reduce the abundance of the pest, but in some cases, they simply prevent the damage 

caused by the pest (e.g. by preventing it from feeding on valued crops) without reducing pest 

abundance. Biological control is often viewed as a progressive and environmentally friendly way 

to control pest organisms because it leaves behind no chemical residues that might have harmful 

impacts on humans or other organisms, and when successful, it can provide essentially 

permanent, widespread control with a very favorable cost-benefit ratio. However, some biological 

control programs have resulted in significant, irreversible harm to untargeted (nonpest) organisms 

and to ecological processes. Of course, all pest control methods have the potential to harm 

nontarget native species, and the pests themselves can cause harm to nontarget species if they are 

left uncontrolled. Therefore, before releasing a biological control agent (or using other methods), 

it is important to balance its potential to benefit conservation targets and management goals 

against its potential to cause harm.

It is hypothesized that some nonnative plants become invasive, superabundant and damaging, at 

least in part because they have escaped the control of their “natural enemies,” the herbivores and 

pathogens that checked their abundance in their native ranges. Biological control addresses this 

by locating one or more herbivore and/or pathogen species from the weed’s native range and 

introducing them so they can control the pest in its new range. These herbivores and pathogens 

are carefully selected and screened to determine if they will attack crops or other nontarget plant 

species. Successful classical biological control programs result in permanent establishment of the 

control agent(s) and consequent permanent reduction in the abundance or at least the damaging 

impacts of the weed over all or part of its introduced range. Biological control is not expected to 

eliminate the pest species completely, and it often takes years or even decades after the initial 

release of control agents before their effects are obvious. Biological control programs may fail for 

a variety of reasons. Some biological control agents never establish, or it may take repeated 

releases to establish viable populations.

Some of biological control’s greatest strengths are that once an agent is established, it will persist 

forever and it may spread on its own to cover most or all of the area where the pest is present, 

generally with little or no additional cost. On the other hand, these strengths can become great 

liabilities if the agent also begins to attack desirable species. Because of this, weed biological 

control researchers take pains to locate and use agents that are specific to the targeted weed and 

will not attack other important plant species. This screening process contributes to the high cost 

and long time required for the discovery, testing, and approval of new biological control agents 

(Tu, et al. 2001).

Final Environmental Impact Statement – Invasive Plant Control Project 287
Appendix 4 • Effects of Nonherbicide Weed Control Methods

Manual

Hand pulling and digging can be selective in terms of plants removed. Mowing and hand pulling 

activities may disturb soil and provide sites for continued weed invasion. Hand pulling may 

inadvertently destroy native or sensitive species growing in close proximity to invasive weeds 

because of trampling by pulling crews.

Mechanical

Mechanical treatments would reduce weed seed production for the season they were treated. Most 

weed species are prolific seed producers and have the ability to regenerate and produce seed 

following removal of top growth. For some species, a population’s spread could actually be 

accelerated if mechanical treatments are applied to creeping perennials and rhizomatous species, 

since any root parts remaining in the ground could resprout. Residual seed in soil can also 

germinate and allow populations to maintain or expand. Mechanical treatments would be 

combined with reseeding or other restoration efforts.

Controlled Grazing

Controlled grazing is often employed in small areas that are intensely infested with weeds. Goats 

in particular are employed in such circumstances, but depending on the weed present, other 

livestock can prove effective. Repeated treatment with livestock or livestock treatments in 

conjunction with other methods such as biological controls, manual eradication, and herbicides is 

usually necessary. With the use of grazing, the need for other eradication resources (herbicides, 

manual labor, etc.) is usually reduced. Nontarget species are often impacted, and materials to 

prevent erosion (weed-free seed mixes and mulches) may be needed if the eradication area is 

large or near an area sensitive to erosion. Revegetation can prevent reinvasion (of weeds) and can 

lead to the extinction of remnant weed populations (Sheley et al. 1999).

Grazing can either promote or reduce weed abundance at a particular site. By itself, grazing will 

rarely, if ever, completely eradicate invasive plants. However, when grazing treatments are 

combined with other control techniques, such as herbicides or biological control, severe 

infestations can be reduced and small infestations may be eliminated. Grazing animals may be 

particularly useful in areas where herbicides cannot be applied (e.g., near water) or are 

prohibitively expensive (e.g., large infestations). Animals can also be used as part of a restoration 

program by breaking up the soil and incorporating seeds of desirable native plants.

When not properly controlled, however, grazing or other actions of grazing animals (wallowing, 

pawing up soil) can cause significant damage to a system and promote the spread and survival of 

invasive weeds. Overgrazing can reduce native plant cover, disturb soils, weaken native 

communities, and allow exotic weeds to invade. In addition, animals that are moved from pasture 

to pasture can spread invasive plant seeds.

In general, the specific weed and desirable native plants will determine the number and species of 

animal grazers and the duration and frequency of grazing.

Cattle, goats, sheep, and even geese may be used to control weeds. Cattle will graze invasive 

grasses, can trample inedible weed species, and can incorporate native seeds into the soil. Horses 

can also be used to control invasive grasses, but horses tend to be more selective than cattle. 

Geese are also useful for the control of invasive grasses, but are more subject to predation than 

288 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 4 • Effects of Nonherbicide Weed Control Methods

other animals. Predation problems in many areas may dictate the type of grazing animals that can 

be used.

Sheep and goats prefer broadleaf herbs and have been used to control leafy spurge (Euphorbia 

esula), Russian knapweed (Acroptilon repens), and toadflax (Linaria spp.). These animals appear 

to be able to neutralize the phytochemicals toxic to other animals that are present in these and 

other forbs. Goats can control woody species because they can climb and stand on their hind legs, 

and will browse on vegetation other animals cannot reach. Goats, additionally, tend to eat a 

greater variety of plants than sheep (Tu et al. 2001).

Prescribed Burning

Prescribed burning is sometimes necessary to prompt the germination of some plants, including a 

number of rare and endangered species. On the other hand, fire can also sharply reduce the 

abundance of some species. The weather, topography, and available fuel will determine the 

temperature and intensity of the prescribed burn and this, along with the timing of the treatment, 

largely determines how the burn impacts the vegetation and the abundance of particular species.

The most effective fires for controlling invasive plant species are typically those administered just 

before flower or seed set, or at the young seedling/sapling stage. Sometimes prescribed burns that 

were not originally designed to suppress weeds have that happy side effect. But in some cases, 

prescribed burns can unexpectedly promote an invasive, such as when their seeds are specially 

adapted to fire, or when they resprout vigorously. These prescriptions must be modified or other 

management actions taken to undo or reverse the promotion of the invader.

Most successful weed control efforts that result from burning are due to the restoration of 

historical (natural) fire regimes, which had been disrupted by land use changes, urban 

development, firebreaks, or fire suppression practices. Many prescribed burn programs are, in 

fact, designed to reduce the abundance of certain native woody species that spread into unburned 

pine lands, savannas, bogs, prairies, and other grasslands (Tu et al. 2001). Prescribed burning is 

often used where it will allow other treatments to be more effective. Persistent shrubby species 

such as saltcedar are effectively killed by the use of herbicides on small plants or ones that 

resprout from overstory removal from cutting or burning. Burning is also used in situations to 

reduce the seed crop of a generation of weeds. This is effective for example in yellow starthistle 

(Centaurea solstitialis) infestations in annual grasslands. Burning annual grasslands after they are 

dry, but before the yellow starthistle has set seed kills the year’s crop and reduces the seedbank. 

The following year’s infestations of yellow starthistle are reduced and allow mechanical or 

herbicide treatments to be more effective. The potential erosion effects from prescribed fire can 

be similar to grazing, and erosion control materials (weed-free seed mixes and mulches) may be 

needed to reduce the effects from erosion.

Final Environmental Impact Statement – Invasive Plant Control Project 289

Appendix 5 • Herbicide 

Model for Watershed Analysis

This appendix describes the herbicide mixing calculations that were performed to simulate the 

potential concentrations of herbicide in a stream draining a watershed subject to weed treatment. 

Values used to calculate flow in each of 11 representative watersheds are presented in this 

appendix. Also included in the appendix are resultant flow rates for two time periods (May and 

September) used to calculate dilution of herbicides in primary streams for each representative 

watershed. Input data and calculation results are summarized in Table 61.

Picloram was used in the simulation as the target herbicide because it is the only chemical that 

has a “high risk quotient” for fisheries. The model assumes a “worst case” condition where all 

acres within each proposed treatment polygon would be treated by picloram for weeds at an 

application rate of one-half pound per acre per year. This would not be the case for Alternative B

(Proposed Integrated Strategy), however, because approximately 3,000 acres (of the 7,345) would 

be treated using other nonchemical methods.

Representative Watershed Selection 

Delivery rates of herbicides to surface water depend on each component chemical’s interaction 

with soil properties and resulting attenuation or lack of attenuation of that component. 

Consequently, selection of watersheds for modeling herbicide delivery to surface waters requires 

consideration of the widest possible range of soil properties.

Major factors in soil formation include type of parent material, climate, overlying vegetation, 

topography or slope, and time. Type of parent material influences the soil pH, structure, color, etc. 

High rainfall climates tend to have less fertile soils, due to leaching of nutrients to lower levels of 

the soil profile, and have more acidic soils. Low rainfall climates tend to accumulate salts near the 

surface and have generally higher soil pH. Soils that form under coniferous forests tend to be 

more acidic than those under deciduous forests, and root action is also critical in soil formation. 

Soils generally have a harder time forming on steep slopes, due to runoff of soil particles during 

rain events. The longer a soil has to form, the deeper its profile is going to be. Therefore, 

selection of representative watersheds to include in the watershed sensitivity analysis considered 

the following factors and data sources:

• Soil Taxonomy - Carson and Santa Fe National Forests GIS databases

• Geologic Parent Material – Data From New Mexico Bureau of Mines & Mineral 

Resources STATEMAP & EDMAP Programs, including watersheds influenced by:

▪ Volcanic Geology – lava flows and ash deposits

▪ Coarsely Crystalline Igneous and Metamorphic Geology

▪ Sedimentary Rocks

▪ Unconsolidated Sediments 

• Vegetative Basal Area - Carson and Santa Fe National Forests GIS databases

• Vegetative Canopy Cover - Carson and Santa Fe National Forests GIS databases

• Soil Reaction Class - interpreted data element from the soil taxonomic description and 

forest specific field data sheets

For the purpose of the herbicide mixing analysis, each of these factors was integrated into an 

interpreted data element provided specifically for modeling herbicide interaction with soil 

Final Environmental Impact Statement – Invasive Plant Control Project 291
Appendix 5 • Herbicide Model for Watershed Analysis

characteristics and resultant runoff. The interpretation groups soils in the representative watershed 

into three classes (minimal, intermediate and well developed) describing the “degree of soil 

development,” representing the tendency of herbicide to attenuate (high attenuation for well 

developed soils and low attenuation for minimally developed soils).

Modeling Assumptions

For modeling purposes, the following assumptions were made based on discussions with Santa Fe 

and Carson watershed/soils representatives:

• Picloram is the only herbicide modeled for a “worst case” analysis.

• Delivery rate to surface water from soils determined to have a high potential for runoff 

(i.e., those with little vegetative cover, poor soil development, on steep slopes, or alkaline 

pHs) equals 2 percent of chemical applied over a period of 6 hours.

• Delivery rate for all other treatment areas equals 1 percent of chemical applied over a 

period of 24 hours.

• Flow during two treatment periods was evaluated:

▪Spring flows were calculated by using mean monthly discharge in May that was 

exceeded 20 percent of the time (Q.20). (Note: These calculations are based on 

data available from USGS gaging stations located downstream of the forest 

boundary in each of the representative 5th level HUC watersheds modeled. Flows 

were normalized by multiplying flow at the gaging station by the percentage of 

the area occupied by the modeled watershed relative to the total area drained by 

flow at the gaging station.)

▪Fall flows were calculated by using mean monthly discharge in September that 

was exceeded 20 percent of the time (Q.20). (Note: These calculations are based 

on data available from USGS gaging stations located downstream of the forest 

boundary in each of the representative 5th level HUC watersheds modeled. Flows 

were normalized by multiplying flow at the gaging station by the percentage of 

the area occupied by the modeled watershed relative to the total area drained by 

flow at the gaging station.)

• The model assumes that all acres within weed treatment polygons will be treated at a rate 

of one-half pound of picloram per acre. (Note: This likely overestimates the amount of 

herbicide to be used, especially in ground-based treatment. Where weeds are scattered, 

spot-spraying may result in treatment of a very small percentage of the acres in the 

polygon. Weed density is highly variable within an infestation and, therefore, difficult to 

measure or to portray on a map or in a database.)

Modeling Calculations

Calculations to determine maximum probable concentrations of picloram in surface water 

included the following steps:

• Determine P, the total amount of herbicide to be applied in a watershed. P (lbs) = R 

(lbs/ac) x A (ac) where R is the application rate of active ingredient and A is the total 

acreage treated.

• Determine if the soil properties of the site would facilitate attenuation of herbicide or 

allow runoff, based on the “degree of soil development.” Well developed soil acres are 

292 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 5 • Herbicide Model for Watershed Analysis

assigned to a 1 percent herbicide concentration and runoff acres assigned a 2 percent 

herbicide concentration. Half of intermediate acres were assigned a 2 percent herbicide 

concentration and half a 1 percent herbicide concentration.

• Determine Y, the maximum yield in pounds of herbicide that could potentially reach 

surface waters. Y (lbs) = P (lbs) x D (%) where D is the delivery ratio or the maximum 

fraction of the applied herbicide reaching surface waters. On sites producing overland 

flow, D is expected to be 2 percent or less. The delivery ratio of 2 percent was assumed to 

be representative of Carson and Santa Fe National Forest conditions. On sites likely to 

allow infiltration, D is not expected to exceed 1 percent and in fact is zero for most sites, 

but a delivery ratio of 1 percent is used to provide a safety factor.

• Determine the worst case (minimum capacity (C) for dilution in pounds of water of the 

surface water system in the watershed where the application is to occur).

• C (lbs) = F (cfs) x 62.43 lbs/cfs x T (sec) where F, the flow rate of the stream is expressed 

in cubic feet per second, and T denotes the time period in seconds over which the flow 

discharge yielding herbicide is being estimated. Flow can be estimated by multiplying: 

width x average depth x average velocity in feet per second. A cubic foot of water weighs 

62.43 pounds. The minimum delivery time for overland flow dominated systems is 

assumed to be 6 hours (21,600 sec), and 24 hours (86,400 sec) for infiltration-dominated 

sites.

• Estimate M the maximum possible concentration in parts per million: M (ppm) = 

[Y(lbs)/C(lbs)] x 1,000,000.

The resulting value can then be compared to known toxicity levels for aquatic organisms.

The results of this analysis for the 11 representative watersheds is shown in Table 61. In two 

watersheds (Ponil Creek and Upper Jemez), if all the acres proposed for treatment were sprayed 

with picloram in 1 year, each watershed would exceed the recommended threshold and some 

effect to the water and aquatic resources would be expected (e.g. loss of fish or aquatic insects).

Table 66. Herbicide Mixing Model Results

Forest/Stream Name Acres 

in Soil 1

Acres 

in Soil 2

Runoff 

Threshold

Infiltration 

Threshold

Carson National Forest 

CanjilonCreek-Rio Chama (Fall) 1 1 113 902

Canjilon Creek-Rio Chama (Spring) 1 500 2,425 19,397

Ponil Creek (Fall) 584 682 43 NA

Ponil Creek (Spring) 584 682 1,398 9,377

Red River-Rio Grande (Fall) 24 55 1,181 9,167

Red River-Rio Grande (Spring) 24 55 3,899 30,911

Rio Grande del Rancho (Fall) 54 73 263 1,901

Rio Grande del Rancho (Spring) 73 500 4,401 35,009

Rio Hondo-Rio Grande (Fall) 4 9 107 818

Rio Hondo-Rio Grande (Spring) 4 9 543 4,303

Rio Tusas-Rio Vallencitos (Fall) 0 0 296 2,369

Rio Tusas-Rio Vallencitos (Spring) 0 0 1,827 14,612

Final Environmental Impact Statement – Invasive Plant Control Project 293
Appendix 5 • Herbicide Model for Watershed Analysis

Forest/Stream Name Acres 

in Soil 1

Acres 

in Soil 2

Runoff 

Threshold

Infiltration 

Threshold

Santa Fe National Forest

Pecos River Headwaters (Fall) 68 47 1,462 11,603

Pecos River Headwaters (Spring) 68 87 7,849 62,697

Pojoaque River-Rio Grande (Fall) 1 3 146 1,157

Pojoaque River-Rio Grande (Spring) 1 3 5,382 43,045

Santa Cruz-Rio Grande (Fall) 8 0 1,490 11,927

Santa Cruz-Rio Grande (Spring) 8 0 4,518 36,149

Upper Gallinas River (Fall) 0 0 239 1,909

Upper Gallinas River (Spring) 0 0 92 738

Upper Jemez River (Fall) 584 317 192 NA

Upper Jemez River (Spring) 584 317 1,267 4,099

294 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 6 • Chemical Spill 

Prevention and Cleanup Plan

The following equipment will be available with vehicles or pack animals that are used to 

transport herbicides and in the immediate vicinity of all sites where herbicides are applied: 

shovel, broom, 10 pounds of absorbent material, box of large plastic garbage bags, safety 

goggles, rubber gloves, protective overalls and rubber boots. All personnel involved in the 

handling of pesticides will review relevant material safety data sheets.

Information in the following section of this appendix are derived from the EPA document, 

“Applying Pesticides Correctly: A Guide for Private and Commercial Applicators.” This 

information will be reviewed by all workers that handle herbicides.

Herbicide Cleanup

Minor Spills

Areas where chemicals are spilled will be roped off and flagged to warn people and restrict their 

entry. Someone should always be on the site to confine the spill and warn of danger until it is 

cleaned up. Herbicides which have spilled on someone should be washed off immediately.

The spill should be confined. It should be diked with sand or soil if it starts to spread. The spill 

should be soaked up with absorbent material such as sawdust, soil, or clay. Contaminated material 

should be shoveled into a leak proof container for disposal. Contaminated material should be 

disposed of using the same method as for herbicides. The spill area should not be hosed down.

Major Spills

People should be kept away from the spill and the spill should be confined. Then the local fire 

department and State pesticide authorities should be called. Call the Chemical Transportation 

Emergency Center (Chemtrec). This is a public service of the Manufacturing Chemicals 

Association. It provides immediate advice for emergencies. Chemtrec operates 24 hours per day, 

7 days a week, to respond to emergency calls. Chemtrec can be reached at 1-800-424-9300. 

If the spill occurs on a highway, then call the highway patrol or sheriff. Someone should remain at 

the site until help arrives. Emergency phone numbers should be carried by the herbicide 

applicators to activate emergency response actions that would include appropriate local, State, 

and Federal agencies. 

With respect to any discharge in such quantity as may with reasonable probability injure or be 

detrimental to human health, animal or plant life, or property, or unreasonably interfere with the 

public welfare or the use of property, the New Mexico Environment Department Ground Water 

Quality Bureau chief must be notified, and corrective actions may be required (20.6.2.1203 

NMAC).

Response Action Guide

A Forest Service employee’s primary responsibility when encountering a hazardous materials 

emergency such as a chemical spill is to report accurately and completely to the appropriate 

authorities in a timely manner.

Final Environmental Impact Statement – Invasive Plant Control Project 295
Appendix 6 • Chemical Spill Prevention and Cleanup Plan

An incident command role for a hazardous materials emergency is not assumed by the Forest 

Service employee but rather by a State or local authorized authority, or Federal On-Scene 

Coordinator. Forest Service employees may take actions to include:

• Public warning and crowd control

• Retrieval of information for reporting the emergency

• Rescue anyone in danger

• Take measured actions to mitigate the emergency

Precautions

• Approach the incidents from an upwind direction

• Move people and keep them away from the incident scene

• Do not touch or move or walk across the spilled material

• Do not inhale fumes, vapor, and smoke

• Do not assume that odorless gases or vapors are harmless

• Do not smoke tobacco; remove all ignition sources

Reporting

The following lists information needed for chemical spill incident reports. Incidents should be 

reported even if there is doubt as to whether it is an emergency or whether someone else has 

reported it.

• Date

• Time of Release

• Time Discovered

• Time Reported

• Duration of Release

• Location (State, county, route, milepost)

• Chemical name

• Chemical identification number

• Chemical data

• Known health risks

• Precautions to be taken

• Cause and source of release

• Estimated quantity released

• Quantity which has reached water

• Name of affected watercourse

• Number and type of injuries

• Potential threats to environment or health

• Your name

• Telephone numbers

• Address

• Name and address of the carrier

• Truck or vehicle number

296 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 7 • Weed Populations 

and Treatments

This appendix provides details regarding the weed populations that are the basis for the analysis. 

Approximately 1,080 separate weed populations have been mapped on the Forests. For this 

appendix, weed populations have been grouped into potential treatment units that have common 

treatment methods and locations that make their being treated together likely.

Unit numbers shown in Table 62 reflect the watershed locations (the first three characters of unit 

numbers align with the map numbers shown with Figure 9 for watershed locations).

Each unit displays the species present, estimated acres of the area, and the proposed treatment by 

each alternative.

Abbreviation keys:

Weed Name Abbreviation

Black henbane ..................................................................................BH

Bull thistle ........................................................................................ BT

Canada thistle ................................................................................... CT

Diffuse knapweed.............................................................................DK

Dalmation toadflax........................................................................... DT

Field bindweed ..................................................................................FB

Hoary cress (white top) ....................................................................HC

Leafy spurge......................................................................................LS

Musk thistle ......................................................................................MT

Musk thistle/Scotch thistle ..........................................................MTST

Poison hemlock ................................................................................ PH

Perennial pepperweed........................................................................ PP

Russian knapweed ............................................................................RK

Russian olive ....................................................................................RO

Saltcedar............................................................................................SC

Siberian elm ......................................................................................SE

Spotted knapweed ............................................................................ SK

Complex of elm, saltcedar, Russian olive ...................................... SSR

Complex of elm, saltcedar, Russian olive, bull thistle .............. SSRBT

Scotch thistle .....................................................................................SC

Yellow Starthistle............................................................................. YS

Yellow toadflax ................................................................................ YT

Treatment Method Abbreviation

Manual............................................................................................. MA

Mechanical .......................................................................................ME

Herbicides ........................................................................................ HE

Grazing.............................................................................................GR

Prescribed fire ...................................................................................FR

Biological .............................................................................. BI or BIO

Biological at Jemez Ranger District..............................................BIO2

Final Environmental Impact Statement – Invasive Plant Control Project 297
Appendix 7 • Weed Populations and Proposed Treatments

Table 67. Weed Populations and Proposed Treatments

Unit Weed 

species Alt. B Alt. C Alt. D Acres

A03.01a BT MA MA HE 0.3

A03.01a YS MA MA HE 0.6

A03.01b BT MA-HE MA HE 1256.2

A03.01b CTBT MA-HE MA HE 0.1

A03.01b MT MA-HE MA HE 1.0

A03.01c CTBT ME-HE MA-ME HE 3.3

A03.09a BH MA MA HE 0.3

A03.09a BT MA MA HE 0.3

A03.09c CT ME-HE MA-ME HE 1.2

A03.09c CTBT ME-HE MA-ME HE 1.7

A03.09d BT MA-HE MA HE 0.2

A05.02 BT HE ME HE 17.5

A05.03 BT HE ME HE 258.1

A07.03 BT HE ME HE 119.9

B02.02a BH MA MA HE 0.1

B02.02a BT MA MA HE 0.1

B02.02a CT MA MA HE 0.0

B02.02b CT ME-HE MA HE 1.1

B02.02c HC MA-GR MA HE 0.2

B02.02d CT ME-HE MA HE 0.1

B02.02e HC MA-HE MA HE 0.2

B02.02f MT MA MA HE 0.2

B02.02g PP HE MA HE 0.1

B03.09b CTBT ME-HE MA HE 39.2

B03.09c CTBT ME-HE MA-ME HE 13.0

B04.02 CTBT ME-HE MA HE 2.0

B04.02 CTBT ME-HE MA-ME HE 1.4

B04.03 CTBT ME-HE MA HE 1.8

B04.11 BH MA MA HE 0.2

B05.03 BT ME-HE MA HE 0.1

B05.03 CTBT ME-HE MA HE 1.5

B05.04a BT HE ME HE 43.9

B05.04b BT MA MA HE 1.8

B05.04c BT ME-HE MA-ME HE 0.1

B05.04c CT ME-HE MA-ME HE 0.1

B05.04c CTBT ME-HE MA-ME HE 13.7

B05.05 BT ME-HE MA-ME HE 7.4

B05.05 CTBT ME-HE MA-ME HE 6.0

B05.06 CTBT ME-HE MA-ME HE 2.7

B05.07a CTBT ME-HE MA-ME HE 2.1

B05.07a YT MA-HE MA HE 1.2

298 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 7 • Weed Populations and Proposed Treatments 

Unit Weed 

species Alt. B Alt. C Alt. D Acres

B05.07b CTBT ME-HE MA HE 2.6

B05.15b BT ME-HE MA HE 0.1

B05.15b CTBT ME-HE MA HE 3.0

B05.15b CTBT ME-HE MA-ME HE 3.6

B05.19 CTBT ME-HE MA HE 0.5

B05.19b CTBT ME-HE MA HE 2.2

B06.07a CTBT ME-HE MA HE 2.0

B06.07b CTBT ME-HE MA HE 1.1

B06.15a BT MA MA HE 0.3

B06.15a CTBT MA MA HE 0.5

B06.15b CTBT ME-HE MA HE 5.0

B06.15b CTBT ME-HE MA-ME HE 6.6

B07.12 MT MA MA HE 0.2

B07.12a CTBT ME-HE MA HE 1.0

B07.13 CT FR FR-ME HE 20.6

B07.14a CT ME-HE MA HE 1.1

B07.14b HC GR-HE GR-MA HE 16.1

B07.14b MT MA MA HE 0.1

B07.14c MT MA-GR MA-GR HE 26.3

B07.14c ST MA-GR MA-GR HE 53.6

B07.14d ST MA MA HE 2.0

B08.01a CT FR FR-ME HE 62.8

B08.01b CT MA-GR MA HE 0.1

B08.01b YT MA-GR MA HE 0.6

B08.01c MT MA-GR MA-GR HE 6.0

B08.02c CT ME-HE MA HE 2.0

B09.02a BT MA MA HE 0.2

B09.02b CT ME-HE MA HE 0.2

B09.02c HC MA-GR MA HE 0.2

B09.02c RK MA-GR MA HE 0.2

B09.02d CT ME-HE MA HE 0.1

B09.02e HC MA-HE MA HE 0.5

B09.04a RK MA MA HE 0.1

B09.04b HC MA-HE MA HE 0.2

B09.04b YT MA-HE MA HE 0.1

B09.04c YT ME-BI ME-BI HE 6.0

B09.04d HC GR-HE GR-MA HE 20.6

B09.06b HC MA-GR MA HE 0.2

B09.06b HC MA-HE MA HE 0.3

B09.06c HC MA-HE MA HE 1.1

B09.06d MT MA MA HE 0.2

B09.06e RK ME ME HE 23.9

Final Environmental Impact Statement – Invasive Plant Control Project 299
Appendix 7 • Weed Populations and Proposed Treatments

Unit Weed 

species Alt. B Alt. C Alt. D Acres

B09.06f YT MA-HE MA HE 0.2

B09.06g YT ME-BI ME-BI HE 0.2

B10.02a BT MA MA HE 1.5

B10.02a RO MA MA HE 0.1

B10.02b BT HE ME HE 5.9

B10.02b RK HE MA HE 0.5

B11.01a BT MA MA HE 0.2

B11.01b CT HE FR HE 4.7

b12.02a CT MA MA HE 0.0

b12.02f MT MA MA HE 0.0

B14.08a CT ME-HE MA HE 0.1

B14.08b CT ME-HE MA HE 0.4

B14.08c CT HE FR HE 16.6

B14.08c MT HE FR HE 1.6

B14.08d MT MA MA HE 0.2

B15.02a CT HE FR HE 23.0

B15.08a BT HE ME HE 15.0

B15.08c CT HE FR HE 8.9

B15.08c DK HE FR HE 5.4

B15.08c SK HE FR HE 9.5

B15.08e SC MA-HE BIO HE 13.0

B15.10a CTMT HE FR HE 426.9

B15.10a DT HE FR HE 2.7

B15.10a MT HE FR HE 61.3

B16.01b CTMT HE FR HE 62.0

B16.01d BT HE ME HE 17.4

B16.12 CT HE FR HE 49.7

B16.12 CTMT HE FR HE 621.9

B16.12 MT HE FR HE 36.5

B17.01b CT HE FR HE 6.9

B17.07a MT MA MA HE 0.8

B17.07b CT ME-HE MA HE 0.5

B17.07c CT ME-HE MA-ME HE 0.2

B17.10a CTMT HE FR HE 262.5

B17.10d SK HE FR HE 13.2

B17.12 CT HE FR HE 44.8

B17.12 CTMT HE FR HE 201.5

B17.13b SC MA-HE BIO HE 0.2

B18.07a BT MA MA HE 0.1

B18.07c MT ME-HE MA-ME HE 0.1

B19.01a HC MA-HE MA HE 0.1

B19.01a YT MA-HE MA HE 0.7

300 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 7 • Weed Populations and Proposed Treatments 

Unit Weed 

species Alt. B Alt. C Alt. D Acres

B19.01b YT BI-GR BI-GR HE 34.5

B19.02b CT ME-HE MA HE 0.5

B19.02f MT MA MA HE 0.3

B19.04b HC MA-HE MA HE 0.4

B19.04c YT ME-BI ME-BI HE 7.9

B19.05a CT ME-HE MA HE 0.1

B19.05b LS BIO BIO HE 43.0

B19.05c MT MA MA HE 1.0

B19.06a CT ME-HE MA HE 0.2

B19.06g YT ME-BI ME-BI HE 0.1

B21.07c CT ME-HE MA-ME HE 0.2

B21.07c MT ME-HE MA-ME HE 0.1

B21.13a SCRK MA-HE BIO HE 21.1

B21.13a SE MA MA HE 15.9

B21.13c SC BIO BIO HE 91.9

C01.03 CT HE FR HE 2.5

C01.03 MT HE FR HE 0.5

C04.05a BT MA MA HE 0.2

C04.05b BT HE ME HE 343.2

C08.01b CT HE FR HE 27.5

C08.01b CTMT HE FR HE 33.6

C08.01b MT HE FR HE 37.4

C08.01c DT HE MA HE 9.6

C08.01c RK HE MA HE 15.3

C08.01c ST HE MA HE 1.7

C08.01d BT HE ME HE 38.2

C08.04a CT HE FR HE 14.9

C08.04a MT HE FR HE 8.8

C08.04b RK HE MA HE 18.2

C08.04c BT HE ME HE 5.1

C08.04c MTBT HE ME HE 45.8

C08.04c PH HE ME HE 22.3

C08.05a MT HE FR HE 3.3

C08.05b SE BIO2 BIO2 NT 8.1

C08.05b SSR BIO2 BIO2 NT 140.6

C08.05c SE MA MA HE 80.5

C09.01b CT HE FR HE 12.5

C09.05a CT HE FR HE 4.8

C09.05a HC HE MA HE 5.4

C09.05a HCFB HE MA HE 4.2

C09.05a MTBT HE ME HE 35.4

C09.05b SE BIO2 BIO2 NT 495.7

Final Environmental Impact Statement – Invasive Plant Control Project 301
Appendix 7 • Weed Populations and Proposed Treatments

Unit Weed 

species Alt. B Alt. C Alt. D Acres

C09.05b SSRBT BIO2 BIO2 NT 1035.1

C10.05b SE BIO2 BIO2 NT 10.0

C13.01a DK HE BIO HE 100.1

C13.01b DK HE FR HE 3.4

C13.01b MT HE FR HE 10.8

C13.01c DK HE MA HE 0.2

C13.01d BT HE ME HE 18.6

C13.02a CT HE FR HE 0.1

C13.03a MT HE FR HE 21.4

C13.03b RK HE MA HE 14.3

C14.01d BT HE ME HE 21.7

D01.04a BT HE ME HE 33.5

D01.04a BTST HE ME HE 77.9

D01.04b ST MA MA HE 3.7

D02.01b BT HE ME HE 23.2

D05.01a BTST HE MA HE 1.9

D05.01b BT HE ME HE 239.5

D05.12 MTST MA-GR MA HE 0.4

E01.02 BT MA-GR MA HE 0.2

E01.02 MTST MA-GR MA HE 4.7

E01.02 ST MA-GR MA HE 0.2

E01.05 MTST MA-GR MA HE 1.6

E01.18 MTST MA-GR MA HE 0.3

E02.02 MT MA-GR MA HE 0.5

E02.02 MTST MA-GR MA HE 1.0

E02.02 ST MA-GR MA HE 0.2

E02.03 MTST MA-GR MA HE 1.0

E02.04 MTST MA-GR MA HE 2.7

E02.04 RK MA-GR MA HE 0.4

E02.06a SC MA-HE BIO HE 37.4

E02.06b MTST MA-GR MA HE 0.7

E02.07 MTST MA-GR MA HE 0.6

E02.07a SC MA-HE BIO HE 22.8

E02.07b MTST MA-GR MA HE 0.2

E02.13 ST MA-GR MA HE 0.1

E02.18 MTST MA-GR MA HE 1.9

E03.01a FB HE MA HE 0.2

E03.01b MTST MA-GR MA HE 1.3

E03.09a SC MA-HE BIO HE 30.5

E03.09b CT MA-GR MA HE 0.3

E03.09b MTST MA-GR MA HE 0.6

E03.09b RK MA-GR MA HE 0.2

302 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 7 • Weed Populations and Proposed Treatments 

Unit Weed 

species Alt. B Alt. C Alt. D Acres

E03.10 CT MA-GR MA HE 0.2

E03.10 MT MA-GR MA HE 0.8

E03.10 MTST MA-GR MA HE 0.4

E03.10 RK MA-GR MA HE 0.6

E03.13 FB HE MA HE 0.1

E03.13 MTST MA-GR MA HE 1.5

E06.01a FB HE MA HE 0.2

E06.01b MTST MA-GR MA HE 0.7

E06.10 MTST MA-GR MA HE 1.9

E06.10 ST MA-GR MA HE 0.1

E06.11 MTST MA-GR MA HE 0.3

E06.11a SC MA-HE BIO HE 37.5

E06.11b MTST MA-GR MA HE 0.7

E06.12 CT HE MA HE 0.2

E06.12 FB HE MA HE 0.1

E06.12 MTST MA-GR MA HE 1.1

E06.12 RK HE MA HE 0.2

E06.12 SC MA-HE BIO HE 0.6

E06.12 ST HE MA HE 0.3

Final Environmental Impact Statement – Invasive Plant Control Project 303

Appendix 8 • Implementation/Monitoring

This appendix provides general guidance for the implementation of this project. Because two 

national forests are involved, each with its own set of ranger districts and programs to coordinate, 

this guidance is intended to assure consistency and coordination. An Invasive Plant Treatment 

Project Work Plan (“project work plan”) (as described in FSH 219.14, Chapter 10) will be 

prepared annually for each forest and approved by the appropriate forest supervisor. As a 

minimum, a project work plan will consist of:

o A precise statement of target species, project location(s), and specific treatment 

objective(s).

o A description of equipment, materials, and supplies to be used, and treatment method to 

be applied.

o If herbicides are to be used, include herbicide formulation and application methods to be 

used. Also, a copy of the Pesticide–Use Proposal Form (Form FS-2100-2) for the 

project.

o A description of the organization of field crews and lines of responsibility.

o A description of interagency coordination.

o A description of the process by which treatment effectiveness will be determined.

o A description of personal protective clothing and equipment required.

o A copy of the job hazard analysis for the project.

o A copy of appropriate emergency procedures.

o Applicable mitigation measures as listed in Table 10 of the FEIS.

o Public notification plan.

Each forest supervisor is responsible for oversight of the respective forest’s portion of the 

Invasive Plant Control Project. This entails accepting yearly treatment priorities, and reviewing 

summary reports of control efforts.

District rangers are responsible for implementing the inventory efforts, coordinating with other 

districts and other agencies in developing joint implementation areas, proposing treatment plans, 

carrying out treatment project work plans, and monitoring results. These implementation 

responsibilities are separate from any target reporting that occurs as a function of the budget 

process.

Final Environmental Impact Statement – Invasive Plant Control Project 305

Appendix 9 • Response to 

Comments on the DEIS

The comment period for the Invasive Plant Control Project began on July 16, 2004, with 

publication of the Notice of Availability in the Federal Register. The comment period ended 

August 30, 2004. During the comment period, 99 comment letters/e-mails were submitted. A 

petition was also submitted during the comment period. After the comment period ended, another 

7 letters/e-mails were submitted by interested people and organizations. Those who submitted late 

comments have not established standing for appeal, but in order to keep the process as open as 

possible, their comments have been considered and responses developed as appropriate.

In total, about 750 separate comment statements were identified, with 650 judged substantive. 

The substantive comments were organized into topical areas and then grouped into 214

statements, which in some instances incorporate more than one comment because of the similarity

of the response. For example, more than half the comments fall within the following 12 issue 

categories:

Category No. of 

Comments

Herbicides 249

Alternatives 162

Technical advice 67

Mitigation/Monitoring 39

Analysis 37

Prevention 34

Forest Plan Amendment 22

Implementation 16

Purpose 16

Procedure 12

Access 6

Adaptive strategy 4

Herbicide use and using alternative methods other than herbicides dominated the number of 

comments. Because of the similarity of many of these comments, they have been grouped the 

most. The rest of the substantive comments tend to focus on one particular aspect of the 

project/analysis or another, with some comments offering very specific recommendations or 

“technical advice” for changes in the document. The trend in these comments is for the FEIS to 

be clearer about how the project would mitigate, monitor, notify the public, and work with other 

agencies to deal with the invasive plant problem. Comments also offered technical corrections.

The response has been organized by these general categories. The parenthetical numbers at the 

end of each issue statement are codes to track back to the original comment, with a complete list 

located in the project record. Final environmental impact statement page numbers referred to in 

this appendix are approximate because of possible changes during final printer formatting, but for 

the most part they should be accurate.

A table with the names of commenters is found at the end of this appendix. Copies of each 

comment letter and a petition are found in the project record.

Final Environmental Impact Statement – Invasive Plant Control Project 307
Appendix 9 • Response to Comments

Access

1. Because herbicides use would affect my health, my access to the forest would be 

limited. (1-1)

The DEIS/FEIS describes the expected effects to human health and safety from use of herbicides. 

For the general public and workers, risk assessments for each proposed herbicide indicate that a 

low probability exists that exposure will occur at levels that will result in either short-term or 

long-term harm. For the segment of the population at risk from exposure through collecting forest 

plants, notice procedures have been included in the FEIS to describe how they might be included 

on a notice list, but this section has also been left open for developing the most effective process 

with those who expect to be affected. The risk assessments discuss sensitive segments of the 

population. Several risk assessments include those people who have identified themselves as 

extremely sensitive to chemical exposure, which would be several magnitudes below the levels 

that indicate low risk to the general population.

For most people the proposed application rates, the method of application, the expected risk of 

exposure, and the mitigation measures will assure a low risk of harm. Provisions for notification 

of the public include people who use the forest who may have a high sensitivity to herbicide 

treatments. They can, therefore, avoid areas where herbicides have been used for the length of 

time they feel is appropriate for their sensitivity. The mitigation measures, including notice 

measures, are expected to reduce the risk associated with herbicides to very low levels. The FEIS 

notes that with Alternative C, even though no herbicides are used, some exposure to potentially 

harmful substances is potential. These include substances such as vehicle exhaust and smoke 

from prescribed burning.

Although this will mean the treatment areas would not be available for use by the public for a 

certain amount of time, this is not unique to invasive plant treatment with herbicides. Often 

activities of one type (thinning for instance) can mean the general public does not use certain 

areas of the forest for safety’s sake.

Adaptive Strategy

2. Herbicides may be used for purposes other than for the eradication of nonnative 

invasive plants. A possible example would be for the maintenance of firebreaks in 

the Gallinas watershed and elsewhere in the Santa Fe National Forest. (2-3)

The FEIS states that purpose of this proposal is to control invasive plants (p. 13). When an area 

(including firebreaks) has invasive plants, this project authorizes control activities. The comment 

does not list other activities that would not be authorized under this project.

3. Herbicides other than those mentioned may be used. For example, atrazine is the 

most widely used herbicide in the U.S., although it has been banned by the 

European Union. It obviously still is accepted in the U.S. although it has been linked 

to human infertility and degenerative diseases and cancer in animal studies. This is 

an example of how “approved” chemical agents can nevertheless be very dangerous. 

(3-4)

The FEIS describes the process for using a different herbicide from those listed (p. 47-48). Any 

proposed herbicide would need to meet the same level of review before it could be used. The 

analysis has relied on EPA registration information as well as an independent risk assessment for 

308 Final Environmental Impact Statement – Invasive Plant Control Project
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each herbicide before it is used (DEIS/FEIS pp. 47-48). Atrazine has not been proposed for use 

and has no risk assessment prepared.

4. We recommend that provisions be made to cover additional invasive species not 

identified in this document should they appear on the Forests. That is critical to the 

“prevention” aspect of invasive species control. (4-6)

The adaptive strategy discussion in the DEIS/FEIS includes criteria that would be followed when 

new species are found on the Forests. Chapter 2 describes how new species that may be 

introduced would be prioritized (FEIS p. 42).

5. On page 16, Background: Existing Condition - We recommend that the DEIS also 

include St. John’s wort (Hypericum perforatum) and wild licorice (Glycerrhiza 

lepidota) in the list. St. John’s wort has been causing the National Park Service in 

Colorado considerable problems, and harvesting by permittees has been ineffective 

in stopping it from spreading. (5-53)

The “Purpose and Need” section describes why those two plants were taken off the list (FEIS p. 

16). However, the adaptive strategy would allow for treatment if these species begin to show 

resource damage similar to other invasive plants.

Alternatives

6. The DEIS should consider other methods that have been shown to work locally. 

When compared with herbicides, these other methods can be as effective and cost 

less. (204-507)

Methods outside those mentioned in the EIS may in fact be useful and effective under certain 

circumstances, but many of them are not expected to be effective across the Forests. The 

DEIS/FEIS explain why the inclusion of herbicides is considered necessary to the success of the 

project. Comparison with Alternative C explains specifically where the different advantages lie 

(DEIS pp. 55-56; FEIS pp. 57-59).

7. The DEIS goes into lengthy discussion to justify using herbicides. However 

alternative treatments to herbicides have not been adequately researched. 

Discussions under Alternative C are vague and often contain wrong information, or 

information based on improper use of a treatment. The DEIS is strongly biased 

against non-herbicide treatments, see Issue 4, page 32, and Comparison of 

Alternatives, pages 55 and 56. Discussion of Alternative C under Environmental 

Consequences on Page 122, and Environmental Consequences - Vegetation is totally 

inadequate in view of all the available information about alternative treatments to 

herbicides. Treatments such as using a flamethrower to kill weeds and seed heads, 

improving soil fertility, or timed-interval mowing are not discussed. Examples of 

non-herbicide treatments which are discussed negatively are for situations where 

they were used inappropriately. (217-317)

The DEIS/FEIS describe the methods reviewed (DEIS/FEIS pp. 34-38). A great advantage of the 

adaptive strategy is that it could include a number of the methods proposed as long as they are 

demonstrated to be effective in accomplishing the plant control objective for a given infestation. 

Each of the methods mentioned in the comment have potential to be used under the adaptive 

strategy. The description of the other methods found in the DEIS was compared with the 

information provided during public comment. Timed mowing and burning were considered as 

Final Environmental Impact Statement – Invasive Plant Control Project 309
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part of Alternatives B and C. The DEIS/FEIS compare the estimated effects of Alternative C with 

Alternative B in terms of ground-disturbing activities. The comment provides no alternative 

source of information to change this conclusion.

Alternative C Preference

8. The adverse effects of herbicides on the forest (including wilderness, riparian areas

etc.), the community, and personal health means that herbicides should not be used. 

The risk of harm is too high to justify any benefit. There are enough chemicals in 

use in the society. Using herbicides as part of this project will increase the toxicity of 

the world and so should be avoided. (6-7)

The DEIS describes the differences in the alternatives, including the expected effectiveness of 

each alternative in controlling invasive plant populations. The DEIS, Appendix 3 describes the 

likely effects of the herbicides as proposed for use. The FEIS has incorporated more specific 

information into Appendix 3 for each herbicide. This information comes from respective risk 

assessments to more clearly explain the conclusion that there is a low probability that use of 

herbicides would cause harm to people or animals. As described in the FEIS, the likelihood that 

nontarget plants could be harmed is higher, but mitigation, including using the appropriate 

herbicide for the appropriate place will minimize that risk. For instance, in an area near sensitive 

nontarget plants, an herbicide would be used that is less likely to cause effects if drift occurs (e.g. 

2,4-D would have lower risk than chlorsulfuron).

Another change made between the DEIS and FEIS was to clarify that herbicides would not be 

used within the population of Holy Ghost ipmopsis on the Pecos-Las Vegas district of the Santa 

Fe National Forest. Because no invasive plants have been inventoried there and because of an 

existing monitoring plan as part of the plant’s recovery program, newly introduced species could 

be managed before they pose a threat to the plant. If an invasive plant takes hold in this area that 

requires herbicide treatment to remove, a separate analysis would be needed.

9. Herbicides are not necessary to accomplish the project objectives. Other methods 

(including prevention) should be used so that the potential harm done by herbicides 

to people and the forest can be avoided. The alternatives to using herbicides should 

receive more consideration. Timed manual treatments and specific treatments for 

specific plant species could be effective. Smothering has worked in test plots. 

Herbicides are not necessary on biennial weeds. (7-8)

The DEIS/FEIS explain the differences in effectiveness between Alternative B (with herbicides) 

and Alternative C (without). EPA registration, followed by risk assessments developed for the 

Forest Service indicate low risk of harm from use of herbicides. The DEIS/FEIS described those 

methods that are currently accepted to be effective for the conditions found on the Forests. The 

adaptive strategy allows for use of new methods (including organic methods) as they prove 

themselves effective in meeting the needs of the Forests. Methods that might work on a garden 

plot near someone’s home would not be as effective at a distance. Biennial treatment could work 

if the weeds are discovered during the correct part of their life cycle, but as weeds are found on 

the Forests, this may not be the case. As another example, vinegar may prove a useful herbicide 

under certain conditions, but the higher concentration mentioned in the comments (above 8 

percent) is more accurately described as acetic acid, require handling similar to any other 

herbicide because of the hazards associated with the product (eye and skin irritant, etc.). 

310 Final Environmental Impact Statement – Invasive Plant Control Project
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Currently, acetic acid is not labeled for use as an herbicide, but if it were evaluated by the Forest 

Service risk assessment process, it could conceivably be adopted for use.

10. Herbicides are not necessary because of the small amount of areas infested with 

invasive plants. Other methods would be effective on these small patches. Learning 

more about natural systems and using this knowledge would allow control without 

chemicals. Spraying in riparian areas poses an unacceptable risk of contamination. 

(8-9)

The DEIS/FEIS “Purpose and Need” section describes the reason why the two forests have 

pursued this project. As noted, the small amount of infestations can be controlled now rather than 

later, so that the impacts of treatment would be smaller and the costs lower. The DEIS/FEIS

examines three alternatives to controlling these (and newly found) infestations. Comparison of 

effectiveness of the three alternatives is provided. The risk assessments provide a review of the 

use of herbicides in riparian areas and the potential impact to aquatic plants and animals. 

Selecting the proper herbicide formulation for the situation and then following label directions 

assures this risk remains low.

11. Simply because herbicides are a cheaper alternative does not mean this should be 

the favored method. Consider economic benefits of other methods, such as manual 

pulling. (9-11)

The economic comparison of the alternatives is included in the DEIS/FEIS. The effectiveness of 

those various treatments is also included in the DEIS/FEIS. The relatively small size of the effort 

(up to 1,600 acres per year) indicates that the workforce needed would be small (DEIS p. 169; 

FEIS p. 175). The rationale for preferring Alternative B over Alternative C is not simply the 

lower cost. Alternative D, all herbicides, has the lowest cost and is not identified as the preferred 

alternative. Therefore, simple economic benefit is not the reason for including herbicides in the 

preferred alternative.

12. The Extensive Uncertainties Present Makes the Decision to Use Herbicides 

Arbitrary and Capricious. The following uncertainties are identified in the DEIS: 

“There are too many variables (receptor sensitivity, dose received, use of personal 

protection, etc.) for accurate predictions of the potential health risk of herbicide use 

and exposure. Given this uncertainty, ... “ (p. 248) “While there is some concern of 

reproductive and teratogenic effects from exposure to sulfometuron methyl in 

laboratory animals, the results of the studies are somewhat unclear...” (p. 233) 

“Although there remains considerable uncertainty relative to potential herbicide 

effects, aquatic organisms, including eggs and larvae of amphibians, could be 

directly exposed to herbicide formulations in water ... and could be impacted.” (p. 

253) “The proprietary nature of herbicide formulations limits the understanding of 

the risks posed by inert ingredients and adjuvant in herbicide formulations.” “ ... in 

many cases, the inert ingredients currently in use have not been tested rigorously 

and their toxicity is not well characterized.” (p. 240) “Limited data are available for 

use in predicting the effects of surfactants on soil quality.” (p. 131) “Clearly, the 

complex interactions between soil biota, environment, and herbicide type make 

predictions of impacts on soil biota difficult.” (p. 130) “There is a general lack of 

data and some uncertainty relative to herbicide effects on amphibians, so there is 

the potential for an unquantifiable negative impact on amphibians from herbicide 

application.” (p. 93) “ ... these weed survey results underestimate actual weed 

infestations on the Forests, since many areas have not been surveyed.” (p.18) (10-14)

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The context of quoted statements is this: “With the exception of accidental exposures or 

exposures under very conservative and somewhat implausible exposure scenarios, workers and 

the general public should not be exposed to a herbicide at concentrations that result in adverse 

health effects, either by short-term acute toxic effects or long-term exposure to low dosage 

levels.” The statement goes on to described how the EPA (and Forest Service through renewal of 

risk assessments) will manage risk through continual review of toxicological data, evaluating the 

expected dose people may be exposed to, and comparing the expected dose with the dose that 

raises a concern. The analysis shows that the dose that a worker or general public would be 

exposed to by this project would be below that determined to be the level of concern.

13. Other methods of treating invasive plants that have been effective and economically 

viable in other national forests and communities such as propane (portable 

backpack) torches were not even analyzed. The City of Santa Fe currently is 

treating invasive plants along roads using these propane torches and it is an ideal 

treatment. (Early spring or during rainy seasons when fire risk is low is ideal for 

this method and a good time to treat invasive plants.) We recommend an alternative 

that analyzes using propane torches and this alternative would address concerns 

regarding costs and environmental effects. (202-302)

The level of detail was not included in the DEIS and is not considered necessary for the FEIS. As 

noted in Chapter 2 (DEIS p. 38; FEIS p. 40), burning may include methods that use a propane 

torch. The restrictions on timing required by burning (generally can occur during early spring, 

late fall and winter) may not present the best opportunity for every weed species (e.g. timing to 

burn after spring growth begins but before seed set).

14. Using non-herbicide methods would be consistent with Santa Fe programs, which 

have been successful in the city. (208-308)

The City of Santa Fe has limited herbicides in its invasive plant control for the past few years. 

They report an increase in costs associated with weed control, as well as a higher danger factor 

with rocks being thrown from mowing equipment, resulting in numerous broken vehicle 

windows. The New Mexico State Highway Department has implemented a moratorium on the use 

of herbicides along highway rights-of-way within Taos County for several years. Many nonherbicide methods require repeat treatments aimed at depleting the root reserves of the target 

weeds. Boulder, Colorado—in contrast—provides an example of a city that has successfully 

implemented urban weed control using herbicides, while protecting the health and welfare of its 

citizens.

Although possible to implement non-herbicide invasive plant control programs in an urban 

setting, where access to the areas is relatively easy, some sites on the Forests are remote and 

accessibility to them is difficult. Regardless of the programs, the conditions on the two forests 

would not always lend themselves to similar methods and intensity. The distance traveled to an 

invasive plant population may indicate the need to apply a method with longer term results 

(herbicide on perennial species), whereas a more accessible site may be effectively controlled by 

several return trips using a method that isn’t as long lasting (e.g. hand pulling or mowing). The 

adaptive strategy provided in Alternative B and the wider range of tools means that the most 

effective method can be used for the particular circumstances.

15. The Weed Committee acknowledges that these weeds are tough to control, and so 

we have initiated some experiments to advance our understanding. One field test 

312 Final Environmental Impact Statement – Invasive Plant Control Project
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established a legume/grass plant community that has successfully excluded Canada 

thistle despite the presence of many thousands of thistle plants on its perimeter. 

Another test successfully eliminated a Russian knapweed infestation 300 feet in 

diameter by smothering with heavy plastic, and a third successfully eradicated a 

smaller patch using Dewitt mulch mat, a polyester fabric that is available in 1-footwide rolls by 250 feet for 8 cents per square foot from Greenhouse and Garden 

Supply in Albuquerque (345-6700). From our tests we determined that it is possible 

to eliminate very difficult weeds that spread from their roots by smothering, and we 

determined that it is possible to exclude weeds that spread by roots and by seed with 

a dynamic and diverse plant community. These dramatic results came from the 

efforts of a small group of volunteers using very little money. We look forward with 

great enthusiasm to the success that can be achieved with the resources and 

creativity of the largest land management agencies in our area. (219-319)

The adaptive strategy allows for using a number of methods such as these, if they can be shown 

to be effective for the circumstances. Planting perennial nonnatives on National Forest System 

lands may not be appropriate to achieve ecologically sustainable conditions if it replaces one 

patch of unwanted vegetation with another. As part of implementing the adaptive strategy, this 

method would be reviewed for its effectiveness at meeting long-term objectives.

Alternative B

16. The Native Plant Society of New Mexico supports the preferred Alternative B. 

Nonnative noxious weeds are invading native habitats across the state and are 

becoming problems by altering the natural ecological composition of native plant 

communities. Consequently, we support the Forest Service’s proposal to amend the 

current Forest Service plan to be able to use herbicides as another means to control 

noxious weeds. But, we do recommend that when and where herbicides are used, 

that they be used judiciously, responsibly, and with accurate knowledge of what 

plants and ecosystems are being treated. For example, we are aware of four exotic 

thistles on these two forests (musk thistle, bull thistle, Canada thistle, Scotch thistle). 

However, there are at least seven native thistle species (Cirsium drummondii, C. 

neomexicanum, C. ochrocentrum, C. pallidum, C. parryi, C. scopulorum, C. 

undulatum) within this same area. We advise that all herbicide operators know how 

to identify all thistles so that they do not inadvertently spray native species of thistle. 

(11-12)

See the DEIS/FEIS “Implementation/Mitigation” section for description of the methods that will 

be used to avoid impacts to nontarget plants. The potential to impact native species of thistles 

exists for other methods, including mowing, hand pulling and burning and so is not simply a 

concern for herbicide use. The effects of the treatments (including herbicides) are described in the 

DEIS/FEIS.

17. The preference is that if herbicides are necessary, they should be held out to the last 

resort. (12-10)

The effects of the treatments (including herbicides) are described in the DEIS/FEIS.

Analysis

18. The DEIS lacks clarity about who has the authority to treat along forest roads and 

highways. The State or Forest Service? (13-26)

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Appendix 9 • Response to Comments

Management of state highways crossing the two forests is subject to the terms and conditions of 

either easements or special use permits. These may vary slightly, depending on the authority they 

were issued under. Control of weeds within these rights-of-way would be implemented according 

to the Invasive Plant Control FEIS, with specific adaptations to fit the situation for each highway 

as defined by the terms and conditions. In other words, the NM DOT could not apply a treatment 

method outside the FEIS on National Forest System lands.

19. Under Strategy for Weed Treatment of Infestations by Alternative (Chapter 2). The 

basis for identification of acreages of treatment using the various methods for each 

alternative needs to be explained. For example, in other parts of the West where 

IWM programs have been implemented for many years, herbicide use constitutes 

over 75 percent of the acres treated. So, what is difference in New Mexico and what 

is the strategic basis for the acreages listed in Table 6, page 39? In addition, it 

appears that the saltcedar leaf beetle is being considered for release on the Jemez 

River, although the environmental assessment prepared by APHIS states that this 

area is currently excluded from consideration as a release site. No reasonable 

rationale is provided to support the acreage figures provided for each alternative 

covered in Chapter 2. (14-31)

The DEIS/FEIS explain how the infestations were identified for treatment (DEIS pp. 39, 265; 

FEIS pp. 41, 303). The outcome of 70 percent was not a target or preconceived amount, only the 

result of looking at where herbicides would be used as the main treatment (about 50 percent), and 

where herbicides are expected to be used in combination with another method, such as hand 

pulling (followed by herbicide treatment to assure effectiveness of pulling), which adds another 

20 percent. These are estimates used to conduct the analysis and at the time of actual 

implementation are likely to be different.

Cultural Resources

20. Lack of information on the cultural resources of areas affected by this project 

means the analysis is inadequate. (15-16)

Mitigation measures for the adaptive strategy for cultural resources are described in the DEIS (pp.

48,49; FEIS p. 52) In addition, the Forests have completed an agreement with the State Historic 

Preservation Office that will require a procedure to follow. This procedure requires survey before 

ground/site disturbing treatments and then protection of sites if any are found.

Drought

21. The DEIS fails to mention treatments in light of drought conditions. While plants 

are stressed by drought, non-herbicidal treatments such as timed-interval mowing 

can be highly effective on weeds. (16-46)

The DEIS/FEIS explain how many of the invasive plants of concern tend to be better adapted to 

drought conditions and can actually increase as drought affects native and desired nonnative 

plants (DEIS p. 68; FEIS p. 72).

22. The DEIS does not account for the drought conditions, which will make 

revegetation much more difficult to achieve after treatments occur. (17-60)

Revegetation is considered in the DEIS/FEIS as a factor. Drought effects on vegetation make 

them more susceptible to being overtaken by invasive species because invasive plants tends to be 

314 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 9 • Response to Comments

more adapted to harsh conditions than native species. With all things equal, the potential exists 

that invasive plants may return to an area during drought conditions more quickly than native 

plants and this could slow revegetation of a site. However, the mitigation measures described in 

Chapter 2 will provide guidance on the conditions when a treatment would be used and when it 

should be postponed to make sure recovery occurs to assure adequate ground cover within a 

specific timeframe.

DEIS page 121 states: “Restoration of ground cover vegetation that would minimize erosion 

would typically be expected within the first growing season. Seeding, mulching, planting and 

other cultural methods to restore ground vegetation would be used where needed to ensure that 

appropriate ground cover is rapidly re-established.” The FEIS has been supplemented to indicate 

that this may often be the case under drought conditions, which might hinder natural restoration 

unless seeding, planting, mulching and other erosion control measures are used as a followup. 

The guidance of the FEIS Chapter 2 mitigation measures will minimize this occurrence (FEIS p. 

48).

23. Climatic events like sudden record rainfall events are not predictable, and high 

runoff could wash away soils and herbicides. Droughts, insects, winds, microclimatic events are all unpredictable, and could hamper reseeding and revegetation 

efforts. (216-316)

The season of use for herbicides is typically spring and fall, two periods when sudden rainfalls do 

not occur. Weather reports will be reviewed before application operations commence in order to 

be sure that these events are avoided (reduces the effectiveness of the herbicides as well). See 

response to comment 22 for discussion of revegetation. The mitigation measures outlined in the 

FEIS for native vegetation include a requirement to evaluate sites to determine the need for 

revegetation.

Economics

24. Please clarify the costs of plan B and D and acres treated. The relative costs of D 

should be adjusted to reflect the cost of the remaining 2,000 acres were included. 

(18-18)

As noted on DEIS page 40 the 1,690 acres has already been included under another decision that 

uses herbicides along the Jemez River, Santa Fe National Forest. Therefore, in the “only 

herbicides” Alternative (D), these areas would not be included. The FEIS has an added footnote 

to clarify this situation.

25. The DEIS does not disclose all of the costs associated with the use of herbicides, 

including training, injuries, costs of the DEIS, etc. (19-68)

The economic analysis looked at the costs outlined in the DEIS. Other costs are speculative and 

not predictable. The comment does not provide any specific costs associated with a project of this 

scope and scale. Furthermore, in the analysis, not all costs for all methods could be included. For 

instance, in the analysis for controlled grazing, startup costs for goat herds were not included.

Growth of the Invasive Weed Problem

26. The analysis does not reflect how dynamic the problem is. Better describe the 

dynamics of the problem you are trying to deal with. (120-20)

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The “Purpose and Need” describes how fluid the problem is. The discussion on the need for the 

adaptive strategy also highlights the changing conditions. Growth rates are discussed in the 

“Vegetation” section of the FEIS, and as described, the rates are variable per species of plant as 

well as specific site conditions (moisture, light, competition). The discussion notes that even at a 

conservative measure of 8 percent, the weed populations would double in size in 10 years.

27. The use of an 8 percent growth rate would be better if a range is used instead 

because the single does not provide a proper representation of the situation. (20-21)

Because of the variability among invasive plants, especially when coupled with the various 

conditions, the analysis used a single rate. The range of growth rates depend on a number of 

factors, including the invasive plant species, climate of the site, availability of water, and soil 

characteristics (pH, etc.). The use of this rate is explained in the DEIS/FEIS (page 18). The 

purpose of the project is to control existing populations. The adaptive strategy sets priorities 

based on these characteristics (and others). Although using one growth rate rather than a range 

may underestimate the effects of no action, it places a more clear focus on the effects of the 

action alternatives.

IDT Qualifications

28. The planning team for this project was not qualified to address all the issues raised. 

(21-51)

The list of preparers includes several people who have knowledge of herbicides (DEIS page 179-

180; FEIS p. 185).

Inventory

29. The DEIS relies on inventory data that is wrong. For future inventories, the project 

must enlist skills that include basic plant identification. Old information needs to be 

updated and species identification needs to be improved. The inventory methods 

have not found all the invasive species nor reflect the growth that has occurred since 

the project first began in 1998. (22-42)

Forest Service protocols are established at the national level through the national resource 

inventory system (NRIS). The adaptive strategy calls for inventory (DEIS p. 41; FEIS p. 43). 

Each administrative unit has responsibility for assuring qualified personnel are available to meet 

policy, procedure and law.

Plants

30. The DEIS fails to disclose several threatened and sensitive plant species that occur 

in areas analyzed for this invasive plant control project. The Rocky Mountain 

Spotted Wood Lily was not mentioned at all in the DEIS. I have documented (and 

photographed) this plant on the Santa Fe National Forest, on both the Pecos and the 

Jemez Ranger Districts. One is in an area mentioned in the DEIS for treatment 

(near recreation and wilderness areas) and the other in old logging sites and 

recreation areas being considered for treatments. This is a major omission in the 

DEIS and needs to be analyzed and effects disclosed for this plant of concern. (23-

35)

316 Final Environmental Impact Statement – Invasive Plant Control Project
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The DEIS/FEIS discuss the plants currently found on Federal and state lists of threatened, 

endangered or sensitive species. The Rocky Mountain spotted wood lily has not been listed for a 

number of years.

Riparian

31. It is particularly critical that no herbicides be used in these treatments because the 

DEIS indicates that much of the area to be treated is riparian, which means that 

these poisons could potentially be broadcast throughout an entire watershed. 

Tragically, in the past, the Forest Service, using the same rationale that there wasn’t 

any evidence of these chemical agents being a potential health hazard, assured forest 

adjacent communities that the use of certain herbicides or chemicals such as DDT 

would pose no threat to their health. It seems clear from the response of the Taos 

community, where petitions against the use of herbicides in the Carson are already 

circulating, that the public adamantly opposes the preferred Alternative B and 

endorses Alternative C, which relies on mechanical, manual, grazing, and burning 

methods of treatment. (503-503)

The evidence and analysis used in the DEIS, FEIS and risk assessments describe the low risk 

associated with using the herbicides as proposed along water ways and in riparian areas/valley 

bottoms. DDT has not been used in the United States without severe restrictions for a number of 

years because of the testing that has occurred and the evidence of its effects. That same level of 

testing occurs on herbicides being proposed for use. Unlike DDT, which was used before this 

level of knowledge existed, the currently registered herbicides have received extensive tests 

before they have been allowed for use. Therefore, the comparison does not support the conclusion 

that herbicides used today may cause certain unknown effects yet to be discovered.

Social Impacts

32. This public opposition belies the DEIS analysis that “positive social and economic 

effects expected from this project would primarily benefit rural Hispanic and Native 

American populations who have a greater reliance on using forest and rangeland 

resources for social, cultural, economic, and spiritual purposes.” In fact, the 

preferred alternative would place these populations in much greater risk of adverse 

impacts to their health. Moreover, since the DEIS concedes that “22 percent of the 

Forests were grant lands” the Forest Service has a special obligation to manage 

these areas in accordance with the wishes of community members. (404-504)

Economic effects, including benefits, are listed in the DEIS/FEIS and associated risk assessments. 

The potential effects to health and safety are included in the analysis, which states that use of 

herbicides would not cause a substantially greater risk of harm. Lack of effective invasive plant 

control would have economic effects as described in the DEIS (page 163-168; FEIS pp. 170, 

173). The lands are managed under the mandate of law, policy and procedure, which also 

accounts for the land status. The Forest Plans for the two forests dictate how they are to be 

managed, with each plan acknowledging the place of the local communities in decision-making. 

Policy guidance is described in the FEIS (pp. 27-28).

Soils

33. The DEIS states on page 36, that repeated use of several different herbicides in 

yearly rotation would be necessary in order to avoid herbicide resistance and to 

Final Environmental Impact Statement – Invasive Plant Control Project 317
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treat emerging seedlings. Cumulative effects of toxic soils and repeated defoliation 

on sites are not disclosed. Other statements in the DEIS state that herbicide 

treatments are superior because of less soil disturbance and rapid return of native 

or planted vegetation. These statements are inconsistent considering the use of 

broad-spectrum herbicides to treat infestations. (26-48)

Soil erosion is described as a concern when comparing alternatives. The DEIS is not stating this 

difference will be large among alternatives, but is pointing out an expected effect of driving 

vehicles over soils a number of times every year (mechanical) versus a single pass repeated over a 

number of years (herbicide). Under “Water Resources,” the DEIS mentions that Alternative C 

would have a low risk of adversely impacting water resources because treatments would only 

involve short-term, low magnitude ground-disturbing activities that would occur over widely 

dispersed sites. Relative to Alternative B, some increase in soil erosion is expected (DEIS p. 122; 

FEIS p. 127-128). The DEIS also notes (DEIS p. 132; FEIS p. 138) that avoiding use of 

herbicides as proposed in Alternative C is likely to result in more ground disturbance from 

digging, mowing, burning, grazing, with more repeat treatments per invasive plant site than if 

herbicides are used. No claim of more rapid return of vegetation is made as a comparison among 

alternatives. However, most of the herbicides proposed for use are selective, not broad spectrum 

and so would have more effect on broadleaf and woody plants than on grasses, and so in these 

circumstances might improve return of native grasses sooner than non-herbicide methods.

34. Soil impacts in the DEIS are not accurately portraying the herbicide vs. nonherbicide comparisons. Soil loss from non-herbicides treatments would not 

necessarily be greater than with herbicides. Use of herbicides will have more impact 

to soils than described in the DEIS. Cumulative effects of herbicides to soils and of 

repeated defoliation on sites is not disclosed in the DEIS. Herbicides do more 

damage since they exacerbate runoff, while manual controls such as cutting the 

weeds at the ground, leaving the stalks for mulch, effectively hold the soil in place. 

(27-49)

See response to comment 33. In addition, cumulative effects are discussed (DEIS pp. 133-134; 

FEIS pp. 1398-140). The DEIS states that 1,700 acres of soils with a severe erosion hazard rating 

would be treated in Alternative C using mechanical, manual, burning and grazing (p. 132). 

Repeated treatments would prolong the disturbance and extend the duration of time that these 

soils are vulnerable to erosion. It does not provide an absolute measure of impact, but presents a 

comparative risk. Alternative B proposes approximately 550 acres of similar treatments on 

similar soils. The best available information indicates that herbicides can be used in a way to 

avoid total loss of vegetation on a site where invasive plants are not dominant (e.g. using a 

selective herbicide would leave nontarget vegetation onsite). Non-herbicide methods do not have 

that selectivity.

Soil Erosion

35. The plan gives too little attention to soil restoration. Weeds are symptomatic of 

disturbed soils. Using herbicides only disturbs the soil further and makes reseeding 

more difficult, especially if time must pass for the herbicide to leach from the soil or 

during periods of sustained drought. Add to this your own research, which concedes 

that some weeds develop a resistance to herbicides, necessitating more frequent and 

more lethal applications of herbicides. (113-52)

318 Final Environmental Impact Statement – Invasive Plant Control Project
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Soil erosion is described as a concern when comparing alternatives. No quantitative comparison 

of alternatives was conducted. Instead, the DEIS/FEIS simply described a qualitative difference 

based on known factors, such as the number of times an area would be treated to achieve the 

same result (generally more times without herbicides than with herbicides) (DEIS p. 131-132; 

FEIS p. 138).

Water

36. The water on national forests is expected to be the cleanest found anywhere, not 

contaminated with herbicides. How are the levels of concern defined? (28-30)

The mitigation measures described in the DEIS/FEIS are designed to assure that herbicides do not 

enter the waterways of the two forests. The risk assessments take this a step farther by assuming 

spill scenarios for the sake of determining if an exposure to the herbicides would result, and if so, 

if that exposure would exceed the levels of concern. The confidence in the mitigation measures 

has been born out with several years of experience and monitoring in similar circumstances. 

Nevertheless, if they do fail to perform as expected, the harmful effects resulting is extremely low 

for all of the herbicides proposed for use. In the event of a spill into a pond with water taken 

immediately after, the level of concern for long-term effects would be exceeded for a number of 

the herbicides. However, the likelihood of this occurring over a long period of time is extremely 

low because it would require repeated exposures to these spill events, which is extremely unlikely 

given the oversight of herbicide use (so that even one spill may be plausible but not likely).

37. Herbicide Model for Watershed Analysis (pages 259-264). It appears that the 

assumptions in the analysis in Appendix 5 are based on speculation and are not 

supportable by published information. If picloram is used as an example, literature 

citations should be provided to show overland movement or movement downward 

in various soil types. Picloram can be highly leachable in some soils, but most 

residues are found in the top 24 inches (Vincell 2002, Herbicide Handbook, Weed 

Science Society of America; Watson, Rice, and Monnig. 1989). The significance of 

this analysis for specific herbicides is unclear. It appears the conclusion that each 

watershed would exceed the recommend threshold and some effect to water and 

aquatic resources would be expected (e.g. loss of fish or aquatic insects) is highly 

questionable, especially when the analysis is not supported by published 

information. Importantly, if proper mitigation measures and best management 

practices were included in the analysis, there should be only negligible amounts of 

specific herbicides that would have the potential to get into water, and the effect on 

fish and aquatic insects would be below measurable levels In areas next to water, 

another mitigation would be to use products approved up to the edge of a stream or 

aquatically labeled products to avoid any adverse environmental effects. This 

analysis is unacceptable and should be removed from the document. (220-320)

The reasons behind the watershed model are described in Appendix 5 (DEIS p. 259; FEIS p. 295)

because it is the only herbicide of those proposed that has a high hazard quotient, based on the 

risk assessments conducted by the Forest Service. It is also very mobile and so has the greatest 

risk of reaching water in watersheds where runoff prone soils exist. The aim of this analysis was 

to assess the likelihood of a harmful concentration of herbicide in project area waters. The effects 

describe a threshold level where the potential for effects to occur would be reached. At levels 

below that threshold, there would be almost no chance of having an effect on the waters of the 

project area because the analysis uses the most sensitive species as well as the herbicide that has 

Final Environmental Impact Statement – Invasive Plant Control Project 319
Appendix 9 • Response to Comments

the lowest levels where effects could be established. Even when considered as a worst-case 

scenario, the likelihood of reaching levels that can affect fish is low. The description has been 

clarified for Appendix 5 and the FEIS (pp. 113, 114, 129).

38. Page 70 (and 69 and 71) of the DEIS describe acres to be treated under the 

“Proposed Alternative B” with herbicides. In “Riparian Areas and Valley Bottoms 

with Shallow Ground Water” nearly 1,100 acres are proposed to have some type of 

treatment with herbicides (and mechanical or manual combined with chemicals). 

This is a tremendous concern, yet no mention is made in the DEIS regarding 

possible contamination of shallow surface or ground water in these areas. (201-301)

The DEIS/FEIS discuss impacts to ground water (DEIS pp. 120-122; FEIS pp. 125). Risk 

assessments based on an assumption of a certain level of contamination (not expected in the 

actual project), note that even if a spill scenario were to occur, there would be a very low risk of 

exposure to levels that would cause acute effects. Under the spill scenario, exposure to several of 

the herbicides proposed for use would exceed the level of concern for long-term exposure. 

However, this exposure would require repeated spills at the same place and the same amount 

repeatedly during a long period of time. Therefore, the likelihood of a repeated spill is not 

plausible and so this long-term risk of harm from this source is almost nil. Ground water effects 

are considered as well (DEIS p. 121; FEIS p. 125). No impact to ground water from herbicide use 

is expected because of the depth of ground water. Where ground water is near the surface 

(wetlands, flood plains and near streams), mitigation measures call for field verification as well as 

use of the herbicide that is specifically labeled for near-water use. 

Wildlife

39. The DEIS does not mention the Southwest willow flycatcher’s dependence on 

saltcedar for nesting. The value of saltcedar to Southwest willow flycatcher needs to 

be clarified. (29-37)

The DEIS/FEIS and the BA/BE discuss the flycatcher’s use of potential habitats for nesting. The 

known habitat has been protected as described in the FEIS (page 51-52) and BA/BE.

40. The DEIS does not fully analyze the effects of using herbicides on insects and 

beneficial pollinator species such as bees, moths, butterflies, and some birds. 

Combined with drought conditions, the assurance is needed that there will be no 

harm to these species. (200-300)

The DEIS/FEIS, Appendix 3 discusses the known effects to a variety of species. The summary in 

Appendix 3 reflects knowledge presented in the risk assessments. The most likely known 

information involves honey bees because the EPA requires tests on bees as part of the product 

registration process. The risk assessments describe known effects of the proposed herbicides to a 

variety of other species, where studies have been conducted. Indirect effects of the vegetation 

treatments have also been included for MIS and TES species as directed. The risk assessments 

present information about other species, including beneficial invertebrates.

Forest Plan Amendment

41. Application of herbicides may be too non-specific. Although the DEIS states that 

aerial dispersal is not contemplated, the amendment to the Forest Plan does not 

320 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 9 • Response to Comments

prevent such a method in other applications. Even vehicle-mounted sprayers may 

disperse the herbicides so widely as to kill non-targeted plants. (30-5)

Chapter 1 describes the scope of the project. The amendment would not permit use of herbicides 

other than those described in the FEIS. The analysis includes the predicted effects of using truckmounted equipment and some impact to nontarget plant species could occur. Mitigation 

measures, risk assessment information, and label directions for each herbicide define the 

conditions where they may be used. In addition, the mitigation measures included in the 

DEIS/FEIS would avoid use of herbicides or they would require buffers to avoid impacts to 

plants listed as threatened (Holy Ghost ipmopsis). Impact to other nontarget species of plants 

would be minimized but some effects would likely occur. As noted in Chapter 2, no spraying 

from the air is included in this project. If such a need arose, a separate review would be 

necessary.

42. There is no cause to change the Santa Fe National Forest Plan considering the 

impacts of allowing herbicides to be used in the watershed. The Forest Service has 

not established a need to amend the plan. The Forest Plan amendment may allow 

for herbicide use outside that otherwise allowed or disclosed. (31-80)

The DEIS/FEIS describes the need to change the standard to one that can be used more clearly.

43. The use of herbicides in the watersheds will have effects to health and safety of the 

people who rely on that water. (32-81)

The need for the amendment is discussed in Chapter 1. See the “Herbicide” section for discussion 

of the expected effects and risks of effects caused by the use of herbicides. The amendment 

includes a provision for involvement of the appropriate municipality to assure community 

involvement in any actual treatments using herbicides.

44. The existing standard in the Santa Fe Forest Plan reflects existing regulations, is 

clear and should not be changed. (33-83)

The standards in the Forest Plan represent specific ways for the general goals to be achieved 

through the Forest Plan. The amended language is intended to provide a more useful on-theground definition and measure for meeting these goals.

45. Amend the Carson Forest Plan to eliminate the use of herbicides within municipal 

watersheds there. (34-85)

As described, the impact to water quality is of a very low risk. In addition the Carson National 

Forest does not have similarly designated municipal watersheds.

46. The Forest Plan Amendment does not provide for adequate public notification that 

is consistent across the Forest. One city may involve citizens while another does not. 

(35-87)

The provision to involve the affected municipality was considered adequate because of the citizen 

involvement in city government.

47. The amendment does not include safeguards to prevent indiscriminate use of 

herbicides in the watersheds. (36-88)

Chapter 2 describes the mitigation measures that will accompany use of herbicides. Risk 

assessments provide information to indicate the types of conditions when herbicides can be used 

Final Environmental Impact Statement – Invasive Plant Control Project 321
Appendix 9 • Response to Comments

while maintaining a very low risk of harm. City governments will be involved before herbicides 

are used in the watersheds.

Herbicides

48. The analysis and disclosure of effects lacks specifics to know which herbicide will be 

used on which plants and so is difficult to evaluate. (37-19)

The effects of the various herbicides were considered after mitigation measures and label 

instructions are followed. For instance, herbicides used near water would need to be labeled for 

such a use. Label directions for handling and use would be followed. Appendix 3 of the FEIS has 

incorporated information from the risk assessments to describe the differences among the 

herbicides more clearly than the DEIS. Estimates of specific herbicide use based on effectiveness 

against target plants has been provided, with the caveat that these are estimates and during actual 

implementation, they may be used differently, as long as the predicted effects do not change.

49. The effects of the use of herbicides has not been fully disclosed. Use of herbicides has 

inherent risk that should be avoided. Use near people is hazardous. Outcome of 

their use is unclear, with much uncertainty about the effects to people, animals and 

non-target plants. Variability of how people respond to these herbicides is 

inadequately accounted for. They have been linked to cancer, endocrine disruption, 

kidney and liver damage, and eye damage. In particular, use near riparian and 

water bodies may cause them to be spread throughout the watershed. (38-150)

Appendix 3 describes the predicted effects based on the expected use of each herbicide under 

consideration. These discussions have been expanded between the DEIS and FEIS to include 

additional information from risk assessments. At expected application rates, with application 

methods, and with mitigation for exposure in place, the likelihood that the herbicides will cause 

harm to people, animals or nontarget plants is very low. Human variability is taken into account, 

as well as sensitive segments of the population (such as children, pregnant women, and in some 

assessments, the chemically sensitive). The risk assessments review available literature regarding 

cumulative effects, synergy and environmental fate of the herbicides, including any potentially 

harmful breakdown products. In responding to comments on the DEIS, available information was 

reviewed. The risk assessments have considered much of this material in drawing conclusions. 

Many of the studies cited as opposition views do not support the conclusions drawn. Some have 

not been accepted by the scientific community as supporting the conclusions drawn. Others have 

broader conclusions than those described in the study and do not present a clear cause-effect 

relationship as implied. One often cited reference (the Journal of Pesticide Reform or JPR) is not 

a peer reviewed science-based journal, but presents information from an advocate’s perspective. 

Thus, although many single conclusions are presented in the comments on the DEIS in order to 

prove harm, they do not counter the weight of evidence presented in the context of the expected 

herbicide use, the required restrictions, and a number of plausible exposure scenarios.

50. The use of herbicides will have consequences to air, soil, water because most of the 

herbicides do not reach the intended target. Roundup and other herbicides are 

banned in foreign countries. (39-200)

See response to comment 49. A review of the information provided does not support the 

conclusions offered.

322 Final Environmental Impact Statement – Invasive Plant Control Project
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51. p. 35 How do you know herbicides are known to be the most effective method? 

There are other methods that will work better (83-485)

In the DEIS, page 35, the statement has been clarified in the FEIS (p. 37) to indicate that 

experience with using a number of invasive plant treatment methods indicates that herbicides are 

often the most effective means.

2,4-D

52. The effects of 2,4,D have not been adequately disclosed, including effects to bird 

eggs, food, nesting habitat. It causes cancer and contains contaminants, such as 

dioxin. (41-152)

Appendix 3 of the FEIS and the 2,4-D risk assessment describe the toxicity, the likely means of 

exposure, the dose at which harm occurs, and the risk that use at proposed application rates would 

reach such a level. The risk assessment concludes that the risk of reaching levels of exposure that 

would cause harm to people, animals or nontarget plants are low. The risk assessment has also 

concluded that links to cancer have not been established. The risk assessment also notes that 2,4-

D does not contain dioxin, that Agent Orange contained 2,4,5-T, which had a form of dioxin as a 

byproduct of 2,4,5-T manufacture. Herbicides using this active herbicide ingredient are no longer 

sold for use in the U.S.

53. Page 238 says 2,4-D is not classified as a human carcinogen. This is not realistic. 

Although links to human cancer are increasing, the EPA lists it as a class D. But a 

link to non-Hodgkin’s lymphoma has been demonstrated. (76-477)

The risk assessment for 2,4-D has evaluated the information that links 2,4-D to cancer and finds 

the EPA conclusion reasonable (2,4-D Risk Assessment p. 3-2).

54. Appendix 3 - Herbicides: Characteristics, Effects, and Risk Assessments Page 220, 

2,4-D - It should be mentioned that when fetuses showed evidence of toxic effects it 

was at laboratory levels many times greater than those that would be found under 

correct field application. (155-430)

In the FEIS, Appendix 3 has been augmented with more information from the risk assessments to 

provide a broader context for the conclusions presented.

Clopyralid

55. The effects of clopyralid have not been adequately disclosed. Clopyralid causes 

reproductive problems. (43-63)

The clopyralid risk assessment describes the toxicity, the likely means of exposure, the dose at 

which harm occurs, and the risk that use at application rates proposed would reach such a level. 

The risk assessments have concluded that no links to reproductive problems were established at 

the doses that would occur even when considering very unlikely exposure scenarios (e.g. directly 

spraying a person with the herbicide).

56. Page 238 does not give a fair characterization of clopyralid carcinogenic properties 

(should not be an E). The EPA has not evaluated clopyralid’s ability to cause 

cancer. It has not been determined. (75-476)

Final Environmental Impact Statement – Invasive Plant Control Project 323
Appendix 9 • Response to Comments

The risk assessment for clopyralid has evaluated the information to reach the conclusion that the 

risk is less than one in a million. This is not because of any carcinogenic properties of clopyralid 

itself, but because of the potential posed by the impurity, hexachlorobenzene. Tests of clopyralid 

show no carcinogenic properties, but because of the presence of the impurity, the risk assessment 

included an assessment of the carcinogenic risk as well.

Dicamba

57. The effects of dicamba have not been adequately disclosed. Dicamba inhibits liver 

function. (44-153)

The dicamba risk assessment describes the toxicity, the likely means of exposure, the dose at 

which harm occurs, and the risk that use at application rates proposed would reach such a level. 

Nitrosamines and dioxin are not reported as impurities in the risk assessment (3-13) as they have 

been in the Journal of Pesticide Reform. The most recent risk assessment has reviewed the 

conclusions offered by Cox and notes that the conclusions are not supported by the data in the 

study (SERA 2004b pages 1-1, 2-2).

58. P 238 dicamba listed as a D is bad testing. Inadequate tests exist to show whether it 

causes cancer or not. (80-481)

The risk assessment has evaluated the information to reach the conclusion that supports the EPA 

decision to classify dicamba at a Level D. The Journal of Pesticide Reform reference (Cox) offers 

a concern without discussing a mechanism or other means to consider validity of the hypothesis 

(SERA 2004b pages 3-1, 3-9, 3-10).

Glyphosate

59. The effects of glyphosate have not been adequately disclosed. (45-156)

The glyphosate risk assessment describes the toxicity, the likely means of exposure, the dose at 

which harm occurs, and the risk that use at application rates proposed would reach such a level. 

Glyphosate and its formulations have very low toxicity. Information provided in the comments 

that glyphosate has a high potential for causing cancer has presented a factual basis to dispute the 

risk assessment (Glyphosate Risk Assessment p. 3-17), which concurred with the EPA conclusion 

that this type of epidemiological study could not establish a definitive link to cancer. No link is 

established in dose-response tests and so the risk assessment concludes the EPA finding seems 

reasonable. The impacts of the surfactant “POEA” have been included in the risk assessment, 

which recommends that the formulation that includes this substance (brand named Round Up) 

should be avoided near water. Another registered product, however, does not include this 

ingredient (brand named Rodeo) and so is available for use near water.

60. Page 240 the statement that Roundup is non-carcinogenic is not acceptable. Other 

studies have linked glyphosate to cancer. (73-474)

The risk assessment has drawn these conclusions based on the evidence presented from studies 

described in the risk assessment. See previous comment response.

Hexazinone

61. The effects of hexazinone have not been adequately disclosed. It is an eye irritant. 

(48-159)

324 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 9 • Response to Comments

The hexazinone risk assessment describes the toxicity, the likely means of exposure, the dose at 

which harm occurs, and the risk that use at application rates proposed would reach such a level. It 

notes the risk of eye and lung irritation from improper use. The risk assessment notes that no links 

to cancer have been established. Effects to human health, animals and nontarget plants are also 

discussed in Appendix 3 of the FEIS.

Imazapic

62. The effects of imazapic have not been adequately disclosed. (49-158)

The imazapic risk assessment describes the toxicity, the likely means of exposure, the dose at 

which harm occurs, and the risk that use at application rates proposed would reach such a level. 

Although this is a potent herbicide, studies have not shown any links between this herbicide and 

human harm at the levels proposed for use and at the likely exposure scenarios. Effects to human 

health, animals and non-target plants are also discussed in Appendix 3 of the FEIS.

63. Page 238 Imazapic is listed with an E for “Evidence of non-carcinogenicity” but this 

is wrong. (references provided). (71-472)

The risk assessment explains the conclusion of non-carcinogenicity, based on review of the 

studies available. The references cited in the comment were reviewed and do not convincingly 

dispute the information found in the risk assessment.

64. The active ingredient alone is used in most testing but that’s not what you spray. 

Crystalline silica is an inert and it is classified as carcinogenic to humans. (72-473)

The risk assessments and EPA product registration are based on the ingredients of the specific 

herbicide formulations proposed for use. Active ingredients are used for toxicity testing of 

technical grade product. However, the registered product undergoes testing as well before it can 

be registered for a specific use. Silica is listed on the EPA inert list as diatomaceous earth (1 

percent crystalline silica) as List 4a, which is not considered toxic. No information was presented 

with the comment to indicate where the link of crystalline silica is made to cancer.

Imazapyr

65. The effects of imazapyr have not been adequately disclosed. (50-164)

The imazapyr risk assessment describes the toxicity, the likely means of exposure, the dose at 

which harm occurs, and the risk that use at application rates proposed would reach such a harmful 

level. As with other herbicides listed, this has a low risk of people, animals or plants receiving 

exposure at levels high enough to cause harm. Effects to human health, animals and non-target 

plants are also discussed in Appendix 3 of the FEIS.

66. p. 238 imazapyr has similar problems as 2, 4-D toxicology (references included). (81-

482)

Risk assessments have evaluated the information available including studies noted in the 

comment. The risk assessments support the conclusion that use of the imazapyr has a low risk of 

harm.

Final Environmental Impact Statement – Invasive Plant Control Project 325
Appendix 9 • Response to Comments

Metsulfuron methyl

67. Metsulfuron methyl may injure or kill nontarget plants. This herbicide leaches 

through silt loam and sandy soils and has the potential to contaminate ground 

water. Surface water contamination is possible because of its solubility. (52-157)

The metsulfuron methyl risk assessment describes the toxicity, the likely means of exposure, and 

the dose at which harm occurs, and the risk that uses at application rates proposed would reach 

such a level. As with other herbicides listed, this has a low risk to people or animals, but because 

of its potency as an herbicide, has the potential to affect nontarget plants at some distance under 

certain conditions (e.g. boom spray from vehicle could affect plants up to 500 feet away), while 

direct foliar application (backpack applicators) does not carry this risk. The product registration, 

label instructions and mitigations measures for this FEIS take these factors into account when 

describing use restrictions. Effects to human health, animals and nontarget plants are also 

discussed in Appendix 3 of the FEIS.

Picloram

68. The effects of picloram have not been adequately disclosed. (54-155)

The picloram risk assessment describes the toxicity, the likely means of exposure, the dose at 

which harm occurs, and the risk that use at application rates proposed would reach such a level. 

This herbicide includes more restrictions than some of the others because of its persistence and 

mobility. The risk of cancer has been evaluated because of the presence of the impurity 

hexachlorobenzene, with that risk being very low (less than one in a million). As with other 

herbicides listed, this has a low risk of people, animals or plants receiving exposure at levels high 

enough to cause harm. Effects to human health, animals and nontarget plants are also discussed in 

Appendix 3 of the FEIS.

69. It should also be mentioned here that the majority of studies have found the half-life 

of picloram to be less than 90 days, the exceptions being in very arid sites probably 

not typical of these national forests. (55-415)

The information about picloram has been reviewed and the FEIS has been clarified where 

appropriate. The risk assessments explain how the persistence of the herbicides factor into the 

assessment of risk. Exposure scenarios evaluate the effects immediately after application and 

because those effects do not exceed the level of concern in most scenarios, the addition of time 

only reduces that risk further below the level of concern.

Sulfometuron methyl

70. Sulfometuron methyl has caused anemia, atrophied testicles, and testicular lesions, 

and increased incidence of fetal loss. A breakdown of this herbicide causes DNA 

damage in the colon of laboratory animals. Drift from roadside and noxious weed 

applications of this product has resulting in widespread plant damage. (61-168)

The sulfometuron methyl risk assessment describes the toxicity, the likely means of exposure, 

and the dose at which harm occurs, and the risk that uses at application rates proposed would 

reach such a level. The analysis includes breakdown products and metabolites. As noted in the 

risk assessment, the potency of this herbicide has a high risk to nontarget plants, and even at 

concentrations expected at a distance after drift, there is a potential to affect nontarget plants. The 

label directions along with mitigation measures included in the FEIS would limit the impact to 

326 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 9 • Response to Comments

nontarget plants, but as noted here and elsewhere, some impact would occur to vegetation in the 

immediate treatment location. Also as noted in the risk assessment, this product should not be 

applied by pregnant women because of a higher risk found for the herbicide to have reproductive 

effects. This is a conservative recommendation in order to assure no effects to workers.

71. P 238 sulfometuron methyl as an E is not fair. An inert ingredient in Oust ® was 

tested for carcinogenicity and a link was established. (78-479)

Risk assessments have evaluated the information to develop this ranking of “E.” Other 

ingredients are included in the risk assessment and nothing described in the risk assessment leads 

to the conclusion of carcinogenicity.

Triclopyr

72. The effects of Triclopyr have not been adequately disclosed. (63-151)

The triclopyr risk assessment describes the toxicity, the likely means of exposure, the dose at 

which harm occurs, and the risk that use at application rates proposed would reach such a level. 

The risk is generally low, although at the highest application rates considered, some workers 

could be exposed to levels that could cause concern. These factors would be taken into account as 

the product is used. The risk of exposure to the metabolite TCP has been discussed in the risk 

assessment. As with other herbicides listed, this has a low risk of people, animals or plants 

receiving exposure at levels high enough to cause harm. Effects to human health, animals and 

nontarget plants are also discussed in Appendix 3 of the FEIS.

73. P 238 triclopyr’s carcinogenicity has been studied in rats and mice and found to be a 

link. EPA has not properly evaluated these links. Since you rated triclopyr as E, 

perhaps the revolving door had an influence. (77-478)

The risk assessment considered the information and conclusions by the EPA on the cancer 

causing potency of triclopyr and found the evidence does not suggest a link between triclopyr and 

cancer. The risk assessment concurs with the EPA finding. See response to comment 99.

Contaminants

74. P 238 EPA considers picloram a cancer risk because of hexachlorobenzene, a 

contaminant. There is a link from picloram to tumors in rats. (79-480)

The picloram risk assessment has evaluated the available information and notes that although 

hexachlorobenzene has been linked to carcinogenicity, picloram has not. The presence of 

hexachlorobenzene does not establish the link suggested at the levels used for this project. Risk 

levels are set at less than 1 in a million. As noted in the risk assessment some risk exists, but 

considering the background presence of this substance, the additional risk is below background 

levels. Appendix 3 of the FEIS has been expanded to include more information from the risk 

assessments regarding how contaminants were considered in the risk assessments.

Dose Response

75. Page 238 says the reference dose provides a measure of long-term exposure that 

could result in chronic toxic effects. This is out of date. See updated reference. (84-

486)

Final Environmental Impact Statement – Invasive Plant Control Project 327
Appendix 9 • Response to Comments

The reference dose methodology is described in an EPA paper that explains why it was adopted. 

Reference dose is considered by the EPA to be a more objective evaluation of the risk because it 

avoids terms such as “acceptable dose” and “unacceptable dose” and establishes levels of 

concern, based on studies that show the lowest effect level (LOEL), and the highest level where 

no adverse effects were observed (NOAEL). The NOAEL is then adjusted with safety factors to 

establish the reference dose (RfD). See next response for more detail.

76. The use of the RfD is a limited method that does not account for small doses (parts 

per trillion). Those limitations are not discussed in the DEIS. (66-505)

EPA has developed a methodology to allow the use of the best available science to determine the 

risk of harm, either short term or long term. As noted in the EPA paper, the dose-response method 

is widely accepted in the scientific community. It isn’t clear from the comment what more 

modern technology is available. Limitations of the method are described by the EPA. For 

example, the reference dose applies to effects that are threshold related (e.g. Assumed that below 

some threshold, no effects will occur). Therefore, for mutagenic and carcinogenic relationships, 

the RfD method makes assumptions as stated in the paper, but for threshold level evaluation (e.g. 

does not apply to potential carcinogenic and mutagenic effects), this is the standard for the EPA. 

The assumptions have been tested over a number of years. Safety factors are incorporated. 

Assumptions are reasonable and supported by facts. The EPA states that the RfD is an estimate 

(with uncertainty spanning perhaps an order of magnitude) of a daily exposure to the human 

population (included sensitive subgroups) this is likely to be without an appreciable risk of 

deleterious effects during a lifetime.

Several of the specific risk assessments recognize that there may be some population subgroups 

that are more sensitive to the substance than can be established with current methods. This 

segment of the population may experience some effect, even with the safety factors in place to 

establish the RfD. This does not alter the state of the science. The alternative for evaluating 

effects does not have a comparable standing with the scientific community. For this selfidentified segment of the population, mitigation measures including notification of interested 

people about herbicide activities will reduce or avoid these effects.

Drift

77. Drift away from the site of use causes effects that have not been analyzed in the 

DEIS. (209-309)

The issue of drift is discussed in the DEIS/FEIS as well as each risk assessment for the herbicides 

proposed for use. The FEIS has had additional information included (Appendix 3) to clarify the 

various risks associated with the herbicides proposed for use. With all herbicides, the risk of drift 

would be reduced through appropriate mitigation measures. Selection of the appropriate herbicide 

for the application is also a part of that risk management strategy and has been incorporated into 

the mitigation measures.

Health Effects

78. The health effects have not been fully disclosed, in particular the effects of endocrine 

system disruption. (46-166)

The documents provided by the commenter were reviewed and compared with the information 

available in the risk assessments. The risk assessments for each of the herbicides proposed for use 

328 Final Environmental Impact Statement – Invasive Plant Control Project
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includes a discussion of the latest information available for the possible effects of endocrine 

system disruption. The suggested references have been reviewed in context of the risk 

assessments, and although epidemiological studies have raised a concern, a clear link has not 

been established between the effects cited and the herbicides proposed for use in this project at 

the application rates allowed under the product labels. Appendix 3 has been revised to include 

more information from the risk assessments regarding health issues.

79. People with multiple chemical sensitivity make up a larger portion of the population 

than the DEIS discloses and so the risks of exposure should be given a greater 

consideration before herbicides are used. Other vulnerable populations, such as 

children, the elderly and those with respiratory conditions need to be considered. 

Effects to these people occur at levels not analyzed in the DEIS, or considered by 

EPA. (47-201)

The review of literature regarding health effects is documented in the risk assessment for each 

herbicide proposed for use. Appendix 3 provides a summary for the FEIS. The risk assessments 

include population segments that are regarded as most vulnerable, such as children. In the risk 

assessments, the effects to children are particularly considered under the exposure scenarios (e.g. 

direct spray and children drinking water immediately after a spill). For people who have been 

diagnosed or identified themselves as being sensitive to multiple chemicals (MCS), there is no 

measurable level that they find acceptable. Therefore, the mitigation measures located in the FEIS 

provide a notification procedure to let anyone who wishes to avoid all exposure the opportunity. 

The comments rely on a survey to suggest that more people are chemically sensitive than reported 

in the DEIS. On review, the survey has been considered in the context offered by the New 

Mexico Health Department official who released it, stating that although 16 percent of the 

respondents mentioned having some kind of allergy, far fewer mentioned a specific ailment. In 

addition, the Health Department noted that any survey questionnaire with fewer than 50 answers 

would be unreliable. For these two questionnaires, both fell well below the threshold. The survey 

was repeated in following years but these questions were not repeated on the survey and so a 

trend cannot be established. The reference to Gibson 2000 has been corrected to Pamela (from 

Paula as in the DEIS).

Inert Ingredients

80. The effects of inert ingredients in herbicides have not been adequately disclosed. 

(51-154)

Risk assessments describe the formulations that are registered for use. The EPA has 

acknowledged that not all of these ingredients are inert and has suggested (but not required) that 

the terminology be changed on labels to describe them as “other” ingredients instead. The EPA 

classifies these other ingredients into four levels, from those with known toxicity to those without 

any known adverse effects. Those with known toxicity that require a material safety data sheet 

(MSDS) are required to be disclosed. Others are not disclosed because they may be confidential 

business information (CBI). This information is disclosed to EPA and to the authors of the risk 

assessments, but not to the general public. Therefore, the determination of effects has included 

the products to be used, not simply the herbicide.

81. Almost all herbicides have inert ingredients and some inerts are solvents. Some are 

active ingredients in other pesticides. (70-471)

Final Environmental Impact Statement – Invasive Plant Control Project 329
Appendix 9 • Response to Comments

See response to 80 for description of the inert/other ingredient requirement. By law (FIFRA) the 

term “inert” is defined in relation to the particular action considered in a particular product, and 

so from that perspective, an ingredient that does not pursue the effect desired is considered inert. 

EPA gave manufacturers the opportunity to use the term “other” ingredients to be clearer that 

these may have effects. However, this does not change the regulator requirements for disclosing 

these other ingredients if they have been found to be hazardous. The EPA classifies four levels of 

other ingredients. Those that clearly have toxic effects; those that have similar properties as 

known toxic materials; those that have not been shown to have an effect (but may have some 

effect); and those that do not have a toxic effect.

82. Page 238 for tests to be useful, they should test the formulas that include the inert, 

not just active ingredients. (82-483)

Risk assessments are developed for the herbicide formulations proposed for use. EPA registers 

formulations of products for specific uses, not the herbicide in general. Tests are conducted 

before the product is registered for use. This includes all ingredients, the active and other 

ingredients. The risk assessments look at the exposure risk using most likely application methods. 

Although toxicity studies may be conducted on pure herbicides, the product formulations must be 

tested as well if the EPA regards tests as necessary before registration. These tests may include 

further toxicity studies.

83. How can you be certain of the synergistic effects, the inert ingredients? (210-310)

The risk assessments have been conducted for the herbicide formulations proposed for use, not 

simply for the herbicides themselves. Therefore, the other ingredients have been accounted for in 

the assessment.

Livestock

84. Little is known about effects on fish and livestock as chemicals are ingested in 

insects, water, and forages, and move up the food chain. For example, beef cattle 

graze on forest allotments, and they could potentially ingest grass forages which are 

not killed by herbicide uptake. (215-315)

The risk assessments review information about the effects of each respective herbicide to 

mammals, fish, invertebrates, etc. A determination regarding the herbicide’s potential for 

bioaccumulation is considered as well. Exposure scenarios for each herbicide include the 

potential for herbicides to be ingested by wildlife (and by inference, cattle). For each herbicide, 

even if this exposure were to occur, the amount ingested would be far below a level where an 

effect could be observed. Once ingested, herbicides are metabolized or passed through the system 

of animals and do not accumulate.

Persistence

85. The DEIS does not take the persistence of the various herbicides into account. This 

persistence will have effects to organic farmers and others. The DEIS 

underestimates the persistence of the herbicides. Terminology needs to be correct. 

Half-life is not the same as persistence. (53-169)

Where appropriate, the FEIS has corrected the terminology to clarify that half-life is the time 

taken for half the active ingredient to dissipate in a respective medium (plant, water, soil). 

Comments note the more relevant term is the persistence, which is noted in the respective risk 

330 Final Environmental Impact Statement – Invasive Plant Control Project
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assessments. At the same time, persistence is mainly relevant to the effectiveness of the herbicide, 

since the risk assessments indicate that the level of exposure at the time of application (wetted 

herbicide on vegetation) is below the level of concern for most herbicide in almost all scenarios. 

Therefore, as time goes by, the persistence measures the time the herbicide remains on the site in 

ever-lower levels. The persistence also depends on a number of environmental factors (moisture, 

soil pH, etc.) Assuming little or no breakdown in the herbicide, exposure levels remain below the 

RfD, which means the likelihood of an adverse effect is a very low probability. Persistence is 

accounted for in the risk assessments for each herbicide. Risk assessments note half-life, and 

discuss persistence. The risk assessments also have half-life noted in soil conditions, in or out of 

water and the like. The text of the FEIS has been revised to clarify the discussion of persistence 

and the number of factors that cause the wide variability for some herbicides. The half-life 

numbers have been left because each is based on the best available information.

Registration System Flaws

86. The EPA registration process is flawed because the EPA is not allowed to use some 

information in making its evaluation of the risk. For example, in its review of 

atrazine having a disruptive effect to the endocrine system of amphibians, the EPA 

disregarded this because of data quality issues. (56-202)

The registration process by the EPA is outside the scope of this analysis. As background, 

however, the EPA provides documents that describe the scientific basis for review and risk 

analysis of each substance they register. The EPA is required by law to review based on the 

science. The EPA is required to evaluate based on the best evidence available. Atrazine and the 

data quality issues are outside the scope of this analysis.

Safety

87. The EPA registration process does not assure safety and so the terminology in the 

DEIS should be corrected to reflect this. EPA uses risk-benefit analyses so could be 

toxic. Language in the DEIS implies that these herbicides are safe (e.g. page 174). 

This terminology is incorrect because no persistence can be guaranteed as safe. (57-

148)

EPA registration includes an assessment of risk, given the toxicity of a substance and expected 

use/exposure. EPA regulates the use of registered products so that the more likely a dose exceeds 

the level of concern (RfD), the more heavily regulated the use. This provides an overall level of 

assurance that no harm will come to people or animals from use of the products. Language in the 

FEIS has been revised as appropriate to clarify this understanding.

88. The methods for assessing risk are not adequate for saying that the use of herbicides 

is risk free or safe. EPA information is linked to the chemical industry. (58-180)

Scientific review of the information provided occurs by the EPA and it is evaluated for particular

herbicide formulations in the risk assessments. The integrity of laboratories performing the tests, 

etc., is outside the scope of this analysis. In cases where such ethical lapses occur, they are 

brought to light by the self-policing efforts of the scientific community. Where the conclusions of 

a study have come into question, the risk assessments note these cases, which is generally when a 

study proposes a conclusion that is not supported by the data, not a case where data is falsified. 

The EPA does not make the claim that use of herbicides is risk free or “safe.” Language in the 

FEIS has been revised as appropriate to clarify this understanding.

Final Environmental Impact Statement – Invasive Plant Control Project 331
Appendix 9 • Response to Comments

89. Herbicides are more hazardous than shown because accidents are under reported. 

(59-193)

Forest Service employees will need to meet all requirements that apply to pesticide applicators 

before they are allowed to apply herbicides. These requirements include accident reporting and 

amount of use per year.

90. Page 175, not true that potential adverse effects would be minimized by using 

herbicides having a low risk. Registration is no guarantee of safety. (68-468)

Different herbicides have different risks, as noted in the risk assessments. A product such as 

Roundup (glyphosate) has the lowest risk to human health of the 12 under consideration, while a 

product such as Oust, Garlon, Velpar or Tordon (sulfometuron, triclopyr, hexazinone, picloram 

respectively), have higher risks for certain potentially adverse health effects, and so need to be 

used accordingly. These risks are managed through using the product as directed on the label and 

through other mitigation measures included in the FEIS. Language in the FEIS has been revised 

as appropriate to clarify this understanding.

91. The best available science is not what the EPA produces. I can’t agree that 

herbicides are safe. (69-469)

The EPA has the mandate to work with the best information available. As mentioned previously, 

the safety of products cannot be proven except in rare cases when the use has been so extensive 

and the effects so minimal that there is no dispute about the effects. Even then (as with the use of 

fluoride in water supplies) these conclusions are often disputed.

92. Safety to employees using herbicides is a concern since they will be subject to 

possible long-term exposure. Accidents or spills may not be reported if an employee 

is concerned that it might affect their future employment. There is no guarantee 

that employees will do what they are supposed to do. (214-314)

The risk assessments assume for the sake of the exposure scenarios that spills would occur or that 

employees would apply herbicides without appropriate personal protective equipment (PPE), 

such as gloves, goggles, long-sleeve shirts etc., or that some other inappropriate use occurs (using 

gloves soaked in the product). Doses for these scenarios for most herbicides result in no exposure 

above the level of concern. The exceptions are 2,4-D, triclopyr, sulfometuron, and hexazinone, 

which are noted in the respective risk assessments. Using appropriate PPE would be adequate for 

2,4-D, but as noted in the risk assessments, extreme care must be exercised for use of hexazinone, 

where misuse may result in severe acute impacts, including to the eyes. For triclopyr, exposure 

beyond the level of concern may occur even with appropriate gear and following label directions 

where upper application levels occur (10 pounds per acre). Mitigation measure in the FEIS will 

require workers who apply these herbicides to follow extra precautions, such as limiting 

consecutive working periods if necessary to avoid exposure to that particular formulation that 

raises these concerns.

93. We strenuously object to the use of herbicides. On page 248 of the DEIS the 

document states, “There are too many variables (receptor sensitivity, dose received, 

use of personal protection, etc.) for accurate predictions of the potential health risk 

of herbicide use and exposure. ...There is also the realization that it is difficult, if not 

impossible, for government or any scientific agency to fully evaluate a chemical and 

all the potential combinations of them to insure that there would not be an adverse 

332 Final Environmental Impact Statement – Invasive Plant Control Project
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effect.” On page 252, the DEIS speaks of “acceptable level of risk.” We feel, given 

the “uncertainty” of these chemical applications, there is no “acceptable level of 

risk” if even one person or animal could be exposed to potentially healththreatening herbicides. In fact, the entire discussion of safety issues with regard to 

herbicide use is peppered with statements revealing how unclear the outcomes of 

these herbicidal applications may be. (502-502)

See the uncertainty response (comment 12). The terminology in the FEIS has been clarified to 

align more closely with the EPA position, which is to avoid terms such as “acceptable” levels of 

risk. The EPA has adopted a system of assessing risk that denotes a reference dose, and then after 

evaluating plausible exposure scenarios, compares the likely exposure scenarios with the RfD. A 

“hazard quotient” is defined as the exposure dose under a given scenario divided by the RfD, so 

that the smaller the hazard quotient, the less hazard, while a number greater than one (referred to 

as “unity”) indicates an exposure that exceeds the level of concern. The intent of this revision in 

the terminology is to eliminate the idea of an “acceptable” or “unacceptable” level of exposure, 

and present the risk in terms of being above or below an established level of concern.

Synergistic Effects

94. Pages 236-253 describing the risk assessments do not account for mixtures. This is a 

waste unless you consider synergy in the tank mixtures and list something about the

inert ingredients. (62-488)

Risk assessments account for the products used and the most likely mixtures permitted by the 

label (including allowable surfactants and other additives). Only formulations that are considered 

in risk assessments would be used (FEIS pp. 38, 47). As discussed in the DEIS/FEIS and risk 

assessments, every possible combination is not analyzed or accounted for and so some risk exists 

that someone would combine products that should not be mixed. Although this is considered a 

possibility, it is less probable that this would happen (given supervision by certified herbicide 

applicators), than the hazardous mixing of unregistered household products, which have high 

proven potential for harm. For instance, chlorine bleach mixed with an ammonia-based cleaner 

will emit a toxic gas. The DEIS/FEIS describe the training and controls on those people using the 

herbicides in order to minimize the risk of such accidents from occurring.

95. The DEIS lacks analysis of the effects of using two herbicides together on the same 

place. (205-305)

Some registered products include more than one herbicide as an active ingredient (FEIS p. 38, 

47). The effects of these products and the risk of use are evaluated during the registration process. 

The risk assessments have used this information to describe any extra risks associated with these 

mixtures. For different products that would be applied on the same area in separate applications, 

the risk assessments only discuss cumulative effects, with the assumption being that an 

application of one after another does not add any measure of risk. This conclusion is based on the 

low level of active ingredient being left onsite by the time the second application is applied. A 

mitigation measure has been added to the FEIS to assure that any followup application of a 

second herbicide to an area is conducted after reviewing best available information on 

compatibility with the previous application.

96. The DEIS does not adequately explain the effects of synergistic reactions when 

herbicides are mixed with other herbicides or what the effects of the actual mixture 

being used will be. For example, the mixing of 2,4-D and picloram has effects 

Final Environmental Impact Statement – Invasive Plant Control Project 333
Appendix 9 • Response to Comments

greater than either alone (DEIS p. 239), which is inconsistent with the statement on 

page 249 that says no evidence of synergistic effects with other chemicals has been 

demonstrated for any of these herbicides.” (206-306)

The risk assessments note that there is little information available to show adverse interactions 

between each herbicide and another. The information mentioned in the DEIS (page 248) refers to 

a formulation of 2,4-D and picloram (Tordon 202C) that is not used by the Forest Service. The 

FEIS has included more information from the herbicide risk assessments, which include 

discussion of mixtures when they are part of products considered for use.

Unreliable Information

97. The dangers of herbicide use have not been thoroughly analyzed and disclosed 

because the DEIS relies on information developed by the chemical industry. Sources 

of information about herbicides are biased and use unsound science. Biased by 

chemical company influence. The sources used to support the evaluation of the 

herbicide effects are sponsored by the chemical industry and so should not be used 

without other sources. (64-44)

Risk associated with herbicides is evaluated in the risk assessments, which uses EPA information 

as well as other sources. Peer review occurs for many of these papers. Financial interest 

disclosure is also often required in the peer review process. In generally accepted practice, 

researchers do not select the referees who review their research. The companies who develop 

these products are not included in the peer review groups. Members of boards of directors, etc.,

are not relevant to the scientific validity of this information.

98. Picloram analysis is an example of the flaws of using industry related opinions. 

Other sources show that picloram has a longer half-life and other impacts not 

mentioned in the DEIS. (65-304)

Information used in the risk assessment, EPA registration, and DEIS has undergone peer review 

for determining the soundness of the information and conclusions. The FEIS will be clarified to 

indicate the half-life in line with the best available information. The watershed modeling 

described in Appendix 5 will also be revised to clarify that although picloram is not likely to be 

used heavily, given the weeds present, it was selected for the modeling because it is the only one 

that has a risk quotient high enough to indicate a possible effect to fish (see Appendix 5, page 

259).

99. The EPA does not take all available information into account when making its 

registration decisions. Information is ignored if it is not considered up to standard 

and so weight of evidence links are not considered. (67-510)

The risk assessments used the available science to reach their conclusions. Where they had to 

reconcile different evidence, this has been explained in the text of the documents. An example is 

the differences in analysis regarding the carcinogenicity of triclopyr: 

Cox (2000) has suggested that since triclopyr has been shown to cause a statistically 

significant dose-related increase in mammary gland tumors in both mice and rats, the 

U.S. EPA guidelines for cancer risk assessment indicate that triclopyr should be

classified as a carcinogen. Cox (2000) cites the 1984 guidelines issues by U.S. EPA. 

The Agency has since issued additional draft guidelines in both 1996 and 1999. The 

1984 guidelines do clearly indicate that a compound will be classified as a carcinogen if 

334 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 9 • Response to Comments

it has been shown to cause cancer in two species of laboratory animals. The more recent 

guidelines, however, are less proscriptive and allow the Agency to exercise substantial 

judgment based on the nature and quality of the data. Notwithstanding the evolution of 

the U.S. EPA guidelines for cancer risk assessment, the basic point raised by Cox 

(2000) is well taken and is the substantial concern to the current risk assessment. 

Triclopyr has been shown to cause the same type of tumors in two species. In addition, 

while all cancers are a public health concern, the particular tumor type noted in rats and 

mice (breast cancer) is a common and important form of cancer in humans. 

Nonetheless, it is worth noting that none of the dose groups in either rats or mice 

evidenced a statistically significant pair-wise increase in breast tumors. In other words, 

the magnitude of the response was not substantial. (SERA 2003b page 3-9)

A similar example can be found in the metabolites section for glyphosate. The conclusions 

presented by the comments have not received peer review. On review of the references cited in 

the comments on the DEIS, the Journal of Pesticide Reform presents a review of existing 

information without the context and analysis provided in the risk assessments. Although this 

information has been included in discussions as part of the open literature, it does not carry the 

same weight of evidence as the risk assessments and EPA evaluation during registration.

100. Statements by the EPA cannot be trusted. [The comment also raised specific topics 

in reference to specific herbicides, doses-response, etc. Responses are covered in 

those topic areas.] (74-475)

EPA has the legal mandate to evaluate and register the products for use. See specific topics for 

more detailed response.

101. Using information for the 1980s cannot be relied on without testing to see the effects 

of inhalation, which could affect not only those who disperse the chemicals but also 

those hiking through the area. (213-313)

The information included in the risk assessments comes from the most recent studies available at 

the time the assessments are prepared. If some of that information is dated into the 1980s that’s 

because no more recent studies have superceded its findings. Each risk assessment considers the 

likelihood of exposure through inhalation.

Water Users

102. Consider the New Mexico Water Quality Standards, which include general 

provisions to protect aquatic life from the effects of toxic pollutants. Do not impact 

acequias, organic farmers, riparian areas and ground water. (85-66)

Water quality protection measures are included in the alternatives and mitigation. Organic 

certification could be affected by drift or by contaminated water. As noted in the FEIS, Chapter 2, 

the appropriate herbicides will be used so that in these situations there is a low possibility of 

affecting adjacent land or water through drift. The DEIS/FEIS predict that these effects can be 

avoided through using the herbicides following label directions and with additional mitigation 

measures. The effects of no action are also described. Water moves weed seed from national 

forest into irrigated fields which may induce use of more herbicide closer to the organic farms 

than if the weeds are controlled on National Forest System lands farther upstream.

Final Environmental Impact Statement – Invasive Plant Control Project 335
Appendix 9 • Response to Comments

Water/aquatic Effects

103. If herbicides were to be used, they should not be used near waterways. Dispersal 

should be only by hand or with back-mounted sprayers. (86-192)

Mitigation measures for use of herbicides near water are described in the DEIS/FEIS. As 

proposed, no aerial broadcast spray of herbicides is going to occur as part of this project. 

Application near water would be limited to those methods discussed in Chapter 2, mitigation 

measures.

104. Herbicides pose a risk to water quality through drift, leaking from roots, runoff, 

and attached to contaminated soils that are then washed into water. Herbicides will 

have impacts to aquatic organisms. (87-205)

The risk assessments provide detailed information regarding the exposure risk associated with 

drift and other offsite movement of the herbicides after they have been applied. This includes drift 

and movement in soils. In all cases, the land/water movement of the herbicides is expected to be 

extremely small, and so the risk of effects is also small. Product labels account for these 

variations among the herbicides by allowing only less mobile products to be used in areas where 

movement may have an adverse effect. For a number of the more potent herbicides the risk of 

adverse effects to nontarget plants if drift occurs is high. The FEIS identifies these herbicides and 

notes restriction to their use (Chapter 2 and Appendix 3).

105. With 55 percent of the area to be treated within riparian ecosystems. The Proposed 

Action within the EIS indicates that a regimen of herbicides would have effects to 

riparian areas/water because triclopyr and clopyralid affect aquatic ecosystems in a 

number of ways, from being highly toxic to fish and birds, to being highly volatile 

and mobile, increasing the chance that they will move away from where they are 

applied and affect nontarget plants, animals (including amphibians) and water. 

(221-321)

The risk assessments for these two herbicides describe the expected effects if used following label 

directions. Under the most likely use scenario, however, neither herbicide would be applied by 

broadcast spray near water/aquatic systems. In particular, triclopyr would be used by backpack 

pump or brushed on stumps after mechanical treatment, thus limiting the exposure to nontarget 

areas. Clopyralid has low potential to impact aquatic animals and plants. Because it binds with 

soil, the likelihood of movement away from the application site is low. The risk assessments 

assume a certain level of herbicide enters the water systems, and based on those scenarios 

(especially the spill scenario), some level of effect would be expected. However, the risk of this 

scenario occurring is slight because of the methods proposed (no broadcast, no mixing near water 

bodies, etc.)

Wildlife

106. Herbicides have impacts to wildlife habitat that must be avoided. Do not apply 

herbicides near Pot Creek (Carson National Forest). (88-13)

Impacts to wildlife habitat are discussed in the DEIS/FEIS. Risk assessments for each herbicide 

also indicate that at the application rates proposed, no impacts to wildlife (vertebrate or 

invertebrate) are likely. As discussed in the DEIS/FEIS, all methods have some indirect impact to 

wildlife habitat because of the changes they will cause to the vegetation, but this effect is not 

unique to herbicides and in the long term will be a beneficial effect to those species that depend 

336 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 9 • Response to Comments

on vegetation threatened by the invasive plants. Any invasive plant control would change the 

habitat conditions. Because of the added effectiveness of herbicide treatments (less need for 

repeated entry, especially on perennial species), the overall indirect effect would be smaller, but 

probably not significant enough to cause a change in habitat effectiveness for better or worse. The 

Pot Creek invasive plant populations are proposed for herbicide treatment in the preferred 

alternative and no specific reason was given in this comment to alter that proposal.

Water/Aquatic Effects

107. Amigos Bravos is concerned about the 3,313 acres of infestations proposed for 

treatment in riparian areas. [This number was taken from the sum of the proposed 

treatment areas in Table 32. As the total area of weed infestation in the forest is 

listed as “more than 7,300 acres” and the number in this watershed table includes 

only 3,313 acres it is assumed that these areas are close to or adjacent to a water 

body since presumably all 7,300 acres do occur somewhere within the listed 

watersheds even though the remaining 4,000 acres are not listed in this watershed 

table.] (508-508)

Table 32 displays the representative watersheds and not the entire forest area. So, the 3,300 acres 

of invasive plants is in fact the total number of acres known in these watersheds. As described in 

the DEIS, the other watersheds also contain invasive plant infestations. The acres of 

riparian/valley bottomlands affected are described in the DEIS/FEIS (p. 17, Table 4). In the FEIS, 

Table 31 (pp. 119-120) has been modified to show acres treated per 5th level watershed.

Implementation/Mitigation/Monitoring

108. Treatments need to avoid impacting native plants, especially where native thistles 

are mixed with invasive. These need to be very careful treatments where both 

invasive and native thistles are mixed. Unit of concern: b017, c395, c586, c396, d 

275, 277, 278. (96-212)

As described in the DEIS/FEIS, a treatment plan for this area would be developed before any 

treatment occurs. Some nontarget impacts are expected, however, whether herbicides are used or 

not. As noted in previous comments, providing personnel with adequate plant identification skills 

will be included in implementation of any action alternative.

109. Several management measures listed in Table 10 in the section on human health 

apply to protecting aquatic species also. Risk to aquatic species may be reduced near 

application areas with additional management measures such as avoiding 

application upwind of surface waters, avoiding application when precipitation is 

likely to occur, and limiting application to periods in the life cycle of the target 

species when the herbicide is known to be most effective, thus reducing the effective 

application rate. (97-214)

The measures were not repeated for each resource area, but they would apply to benefit more than 

one resource.

110. Appendix 3 provides a useful review of information that can be used to assess risk to 

aquatic and other species associated with several herbicides proposed for use. Table 

10 states that air, soil, water, riparian and aquatic resources would be protected by 

employing methods that have been documented to have low risk to aquatic species 

(p. 48). Are these methods described in a document that the EIS could cite and 

Final Environmental Impact Statement – Invasive Plant Control Project 337
Appendix 9 • Response to Comments

summarize? How specifically would the information in Appendix 3 be used to 

minimize risk to aquatic species? Possible criteria might include estimating 

concentrations in adjacent surface water that may result following proposed 

herbicide application, and comparing to concentrations with toxic effects identified 

in Appendix 3. To comply with 20.6.4.12.F NMAC, these determinations may need 

to be made on a site-specific basis rather than on a watershed basis as described in 

the DEIS. (98-215)

The FEIS, Table 9 (p. 46-47) has been clarified with more examples of “low risk” methods. This 

combined with a more full description of the risk assessment process found in Appendix 3 

provides a description of how a selection would be made based on the risk for a given situation. 

The Forest Service risk assessments provide a mechanism for evaluating the risk of a given 

herbicide formulation to aquatic and other species.

111. Mitigations, Conservations Measures, and Best Management Practices (page 45-49). 

Some of the listed mitigations are requirements of law or policy, which can be 

identified mitigations, but more specific measures need to be listed. These could 

include buffers for specific herbicides related to surface water or ground water. 

How about weather aspects like rain, wind, and high temperatures as they relate to 

herbicide uses? In addition, the buffers (conservation measures) for threatened and 

endangered species appear to be contrary to what would be acceptable to the U.S. 

Fish and Wildlife. These deficiencies are an indication of the lack of having an 

herbicide expert on the IDT. (99-217)

In order to focus the EIS on issues that are key to the decision, mitigation measures key to the 

decision have been described. In Table 10, the first measure under Human Health/Safety is that 

herbicides would be used following label requirements (p. 47), which include the specific 

elements mentioned in this comment, and so are not necessary to include in the FEIS. The 

mitigation measures (including buffers) regarding TES species have been updated based on 

advice from the U.S. Fish and Wildlife Service and public comment on the DEIS.

112. Monitoring must include success of all methods (100-221)

Monitoring will be a key element in project implementation. Case studies may not be developed 

as such but the monitoring information would likely be shared between the Forests.

113. Mitigation measures must be reliable, funded, and implementable. Application 

directions are very complex and difficult to carry out. How can you insure no risk to 

the public or wildlife from herbicide use. You should avoid areas frequented by the 

public. There should be more emphasis on signs and proper notification. Label 

directions won’t be followed and can’t be monitored closely enough to ensure they 

can be followed. Prescribed burns must be far enough away to avoid harm to 

sensitive people caused by smoke. (101-222)

Mitigation measures are described that have a reasonable chance of success. As a matter of 

policy, if necessary mitigation measures listed were not funded, the project would not proceed. 

The notification described in Chapter 2 gives an outline of the objectives for notification. The 

implementation may vary from place to place and over time in order to be as effective as possible.

114. We suggest that the percentage of acres treated with herbicides and the percentage 

subject to manual treatments be monitored and disclosed so that the agency can be 

338 Final Environmental Impact Statement – Invasive Plant Control Project
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held accountable to its estimate that 70 percent of invasive weed projects will be 

treated with herbicides. (102-223)

The 70 percent is intended only to show the conditions as they are known now. It is not intended 

to be a limit.

115. Lack of Detail about the Alternative and Proposed Program (procedural 

deficiency). It is impossible for the reader to determine what might be done, where it 

will occur, what methods will be used, the timing, or other important aspects. For 

example, what herbicides are being considered for management of each weed 

species under the proposed action, where will the products be applied (sites), how 

will they be applied, what is the management strategy and possible success rates, 

and how long will it take to achieve the desired objectives? No such information is 

provided for any alternative. It’s stated that biological control will be used, but 

there is no information about the weed species or agents that are being considered. 

The use of prescribed fire is identified, but there is no information about the weeds 

that will be treated with this approach and the efficacy of the method. There is no 

specific information about mechanical or hand-treatment methods. In fact, no 

specific information has been addressed in the analysis; thus, the analysis is 

incomplete and unacceptable. (501-501)

The detail in the DEIS is considered adequate to analyze and disclose the likely effects of 

implementation of the proposed action and alternatives. A list of which herbicides might be used 

on each species of invasive plant has been added to the FEIS for clarity, but this is intended as a 

summary of label directions, not a requirement. Restrictions associated with each herbicide would 

dictate the use, season of use, and method of application of each (for example, the herbicides with 

high risk of impacting non-target plants if applied with a boom spray would not be used where 

sensitive nontarget plants are located near the invasive plant population). This clarification in 

Appendix 3 (Table 59 p. 228) is intended to provide additional information to the public about 

possible distribution of the different herbicides. However, it would remain non-prescriptive under 

the adaptive strategy. The exact treatment prescription would be determined at the site when the 

unit treatment plan is developed. 

Application Methods

116. Using herbicides from vehicles would cause effects that should be avoided. (94-38)

Chapter 2 describes the mitigation measures associated with herbicide treatments. In some 

instances, the use of certain herbicides from vehicles would not be permitted because of potential 

impacts to sensitive plants. Chapter 2 lists these herbicides and instances. However, in general, 

these restrictions would not be applied.

Budget

117. The implementation of the project is questionable because of funding short-falls. 

Implementation needs to be more clearly spelled out in the DEIS, including priority, 

funding sources, etc. The budget and funding is necessary to achieve the project 

targets. How will you ensure the budget is there? (90-32)

Implementation teams will be set up by each forest that will best work with their organizations, 

depending on such factors as personnel staffing and budgets. The DEIS describes the standards to 

be met, regardless of the team organization. Targets are dependent on budget. Absolute budget 

Final Environmental Impact Statement – Invasive Plant Control Project 339
Appendix 9 • Response to Comments

figures are not available, but for a given budget, regional priorities indicate that dealing with 

invasive plants would be funded at some level each year into the foreseeable future.

118. The DEIS proposes an ambitious program of treatments with monitoring to check 

effectiveness of treatments with no assurances that the Forests will have the staffing 

to accomplish monitoring. (91-211)

Budget for monitoring will be integral for the treatments. Without the monitoring, the treatments 

would not occur.

Notice

119. Will the notification mitigation measures really work? How will people know? (104-

170)

Notification procedures have been used effectively in other weed management programs, for 

example, Boulder County, Colorado. The two forests anticipate that a similar notification 

program can be effective here also. The FEIS notes that the notification measures will be adapted 

to find the most effective methods. Treatment personnel will follow established weed treatment 

procedures.

120. We strongly urge the Forest Service to consult directly with the Boy Scouts at 

Philmont Ranch regarding any treatments using herbicides in the Ponil 

Creek/Cimarron Canyon area. No mention is made in the DEIS that these 

consultations have occurred. (105-213)

Appropriate consultation with Philmont Ranch would occur as treatments are considered near that 

area.

121. The types of notification offered do not cover most of the population. In the Las 

Vegas area, the only way to reach people with information is via the local 

newspaper, and the 2 local radio stations. This is the minimum that should be done 

to inform the public. (106-216)

The Las Vegas Ranger District would coordinate using the methods described in the DEIS/FEIS, 

as well as other means developed during the preparation phase of implementation.

122. Rather than ask for comments from individuals, why not appoint a community 

working group to represent the public, and let us discuss and document the pros 

and cons? (114-17)

The process for the environmental impact statement is established in law, regulation and policy. 

The Federal Advisory Committee Act (FACA) dictates the involvement in decisionmaking by 

such working groups in order to limit the influence of any one group. The decisionmaking 

process followed by Forest Service policy intends to provide the broadest participation.

123. The public has a right-to-know when herbicides are used in the Forest, but the 

proposed notification plan is inadequate (p.45). Because of the long persistence of 

most of the herbicides proposed for priority use, posted signs should remain in place 

for at least a month following their application, and not removed after the herbicide 

has dried as implied in the DEIS (“Generally a safe re-entry period passes in treated 

areas after the herbicide has dried on the leaf surface.” p. 175). (207-307)

340 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 9 • Response to Comments

As noted in the FEIS, the notification methods are not spelled out in detail in order to provide the 

most effective means for a particular situation. The FEIS allows for each district to use the 

available means to provide notice. The DEIS/FEIS and the risk assessments take into account the 

exposure that would occur by walking through an area immediately after spray, when vegetation 

is still wet. After that period, the exposure is greatly reduced. Other segments of the population 

who are more sensitive to exposure would be notified with signs as well as other means that can 

be developed for each area.

Plant Inventory/ID Process

124. The DEIS lacks specific descriptions of the way the adaptive strategy will be 

implemented, which leaves it inadequate. Need to assure us that employees will be 

able to identify plants to avoid harm to native species. How will the adaptive 

strategy allow for not using herbicides in those locations around Taos and Santa Fe 

County where there is a long history of objections to herbicide use. (89-2)

Each forest would be responsible to implement the adaptive strategy based on its organization, 

depending on such factors as available personnel and budget. The DEIS/FEIS describe the 

parameters and criteria to be met, regardless of the organization structure.

Safety

125. The DEIS fails to adequately insure that the public will be protected from herbicide 

exposure, including the exposure of those collecting and using plants for traditional 

cultural use. Drift from nearby use could affect plants outside the immediate 

treatment area and cause exposure to people who will become ill from this exposure. 

(107-72)

Notice measures are described in Table 10 of the DEIS/FEIS. The risk assessments analyze an 

exposure scenario in which vegetation is ingested immediately after application of herbicides. In 

those cases, the level of exposure did not exceed the level of concern, usually by factors of 

several thousand. Therefore, even in the unlikely instance when a collector ignores a notice, the 

risk of harm remains extremely small. The exposure described in the risk assessments looks at 

collecting and consuming plants from the immediate spray area soon after application, which 

would assume the highest level of the active ingredient is ingested. Because these scenarios do 

not exceed the level of concern, other scenarios that expose collectors to less (through drift for 

example) would be less than that level as well.

126. Workers cannot be counted on to follow the safety instructions and so will injure 

themselves or others by mishandling the herbicides. (108-73)

The mitigation measures, labeling, and OSHA standards cover worker safety. Failure to follow 

proper application direction found on labels includes penalties that may be both civil and criminal 

(per both FIFRA and New Mexico law). In addition, OSHA safety guidelines must be followed or 

penalties can be leveled as well.

Timing

127. Alternatives, Including the Proposed Action Alternatives Considered in Detail 

Alternative B: Integrated Weed Control Strategies Page 35 - The statement is made 

that “Treatments are scheduled to begin in the spring of 2005, and would occur 

during the weed’s growing season.” In fact, excellent control of Siberian elm has 

Final Environmental Impact Statement – Invasive Plant Control Project 341
Appendix 9 • Response to Comments

been achieved with stump painting in late winter before the trees begin to leaf out. 

(92-36)

The Adaptive Strategy is intended to provide as much flexibility as possible for treatments, 

keeping within the bounds set by the FEIS. The specific statement in the DEIS/FEIS describes 

when the first treatments may occur after a decision is made about the project. It is not meant to 

imply that only spring treatments would be implemented.

Watershed Thresholds

128. How will the Forest Service be sure that the limits outlined per watershed will be 

maintained? (Page 108). Where is the baseline for limits, and where does the DEIS 

list safe tolerable limits for the proposed herbicide treatment areas? How will future 

Forest Service personnel be able to determine when or if a limit has been reached? 

Again, record keeping and monitoring are essential here, and the agency has a 

terrible track record in this regard. The DEIS needs to set clear herbicide threshold 

limits for the public to review, and for the future Forest Service personnel to use as 

a basis to determine if they would exceed these threshold limits in future treatments. 

(95-74)

As described in the DEIS/FEIS, thresholds were used to determine a lower limit of concern, 

below which little to no impact to water quality and fish/aquatic systems would be anticipated. 

These thresholds are set as a general trigger to indicate when more analysis may be needed when 

a large amount of treatment is proposed in any one watershed, or implementation would need to 

be modified to keep the acres treated below these estimates. The FEIS has been clarified with 

regard to this point in the “Mitigation” section and Appendix 5. As noted in Appendix 5 and the 

FEIS (pp. 113, 125), the analysis shows that an extremely low risk exists that the project would 

reach water at levels that would cause harm to aquatic systems, given the acres proposed per year 

spread out over the two forests. This is in addition to the label requirements and the other 

mitigation measures in place. The measure that mentions thresholds has, therefore, been removed 

from Table 10. 

Wildlife

129. Wildlife mitigation measures are not adequately described, in particular those 

protecting nesting birds and small mammals during breeding season. Population 

surveys (especially for breeding birds) are required and not discussed. (103-67)

The appropriate guidelines for wildlife management have been applied to this project.

130. Mitigation measure needs to be comprehensive to protect TE species. (109-218)

Appropriate mitigation measures have been applied, in consultation with the USFWS.

131. Consider including buffers as directed by the USFWS guidelines. May have more 

drift caused by the drier climate than guidelines in other moisture climates. (110-

220)

In the FEIS, a buffer has been denoted in Holy Ghost Canyon to protect the holy ghost ipomopsis 

from potential harm caused by use of herbicides (Table 10). Other measures have also been 

incorporated into the FEIS to assure no harm is caused to the holy ghost ipomopsis population by 

any other treatment method as well (e.g. controlled grazing, prescribed fire, etc.)

342 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 9 • Response to Comments

Prevention

132. The analysis needs more description of the various modes of spread. (111-22)

Modes of spread are discussed in the DEIS/FEIS under the purpose and need section. The main 

emphasis of the project is controlling existing populations. Prevention addresses the spread and 

ways to curtail it. The prevention guide (included in the project file) includes information about 

the modes of spread. The DEIS/FEIS explains why prevention as a separate alternative is not 

considered in detail in this analysis. (DEIS p. 34; FEIS pp. 31, 36)).

133. The DEIS fails to address prevention measures. (112-40)

The purpose and need description in the document discusses the context of prevention and 

explains why prevention was not included as an element of this project to control existing 

invasive plants. The use of prevention in the overall integrated management strategy is 

acknowledged as key, but this prevention can occur without being included in the plant control 

effort (DEIS p. 34; FEIS pp. 31, 36).

Procedure

134. Clarify the process for making the decisions: will there be one decision for both 

forests or one for each? (118-226)

The DEIS/FEIS explain the effects of the project as implemented on the two forests. How the 

decision is made (one or two decisions) does not influence the outcome of the analysis and lies 

within the discretion of the responsible officials.

135. We request that a public meeting be held with the decision makers. The intent of the 

meeting is to discuss in more detail the issues raised in the DEIS and in public 

comments. This would include, but not be limited to, assessing local interest in 

helping the Forests with weed management activities. We would prefer the meeting

take place in the near future, but in any case, request that it occur prior to the 

issuance of the final decision. (119-227)

A review of the comments provided during the public comment phase of the process indicates 

that the issues have been clearly defined for the decision makers. In order to avoid the appearance 

of allowing one group greater influence over the decision than others, such a meeting would not 

be appropriate. Once a decision has been made to proceed, the shape of the implementation is 

open to the influence of the public, including specific groups; in particular those who wish to 

participate through volunteering their time to help reduce the invasive plant threat.

136. Criteria for selection of Alternatives (page 41). Criteria used to identify the 

preferred alternative need to be identified. There is some information about 

objectives and priorities, but no listing of criteria could be found. At a minimum, it 

seems that (1) effectiveness, (2) cost, and (3) potential environmental effects must be 

considered as criteria for evaluating the various methods. (115-29)

The DEIS/FEIS describes issues used to develop alternatives, which are also used as factors that 

relate to the decision to make. Because of the complex number of factors involved, the traditional 

single-issue criteria were not used. (DEIS pp. 31-33; FEIS pp. 33-34)

137. The DEIS lacked adequate notice so that not enough people who were interested in 

the project knew about it. (116-34)

Final Environmental Impact Statement – Invasive Plant Control Project 343
Appendix 9 • Response to Comments

Notification followed the laws, regulations and policy of the Forest Service. Additional measures 

were taken that include mailing of a postcard to approximately 500 people who had participated 

during scoping efforts in 2000. Those who requested it were sent a copy of the summary or DEIS. 

Notice of the open houses were posted in the local library branches as well as other places 

(markets, bookstores) where people with an interest might be informed. Newspapers ran public 

announcements.

138. The use of herbicides is inconsistent with President Clinton’s executive order in 

which Federal agencies are instructed to respond to invasive species in an 

“environmentally sound manner.” Contaminating the forest with poisons is not an 

environmentally sound approach to managing noxious weeds. (117-195)

This is not an interpretation of the E.O. that is accepted by the Federal agencies who are charged 

with following its direction.

Purpose

139. As we are sure you are aware, there is a great deal of debate within both the 

scientific and environmental communities about what constitutes an “invasive 

species.” The discussion of this important issue in the DEIS is extremely limited and 

inadequate. On page 16 the DEIS uses Whitson’s definition “plants that interfere 

with management objectives for a given area of land at a given point in time.” This 

definition seems arbitrary and capricious, given the subjectivity with which 

“management objectives” are formulated. (121-231)

The definition of an invasive species is relative to how a particular plant fits into the overall 

desired conditions for an area. It is also defined by law (Noxious Weed Act) (FEIS p. 17). If the 

plant is neutral or furthers the objectives, it is not considered a weed. Invasive plants are weeds 

that have highly developed means of survival and so tend to out-compete and drive out the 

vegetation that is desired. Although many strategies are available to define invasive plants, the 

two forests aligned with the State of New Mexico in order to foster the most cooperative 

environment possible. The adaptive strategy would permit adding other plants to the list, once a 

determination has been made that they are setting back management objectives for a given area.

140. The DEIS lacks oversight in fostering cooperation, coordination and commitment 

with other land management agencies and affected interests. The ability to fight a 

coordinated front would be an improvement if the Proposed Action included 

development or entering into existing agreements with other agencies for the control 

and treatment of weeds. As presented in Appendix 1, there are others that share a 

common interest and goal in preventing the spread of non-native weeds. Assistance 

agreements, Memorandum of Understanding (MOU’s) and Cooperative 

Agreements are in place in other states and in some counties of New Mexico between 

the BLM and Soil and Water Conservation Districts. Agreements between parties 

could result in money and staff being available to cross-administrative boundaries 

for a more effective and coordinated control program. (122-234)

The DEIS discusses those actions the Forest Service officers can use to control invasive plants on 

National Forest System lands. Other actions can also be taken independently from this project, 

such as participation in cooperative weed management units with other land managers. Table 10 

includes a mitigation measure that requires coordination with other potentially affected 

landowners. The importance of coordination among land ownerships is also described in the 

344 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 9 • Response to Comments

“Purpose and Need” section. A memorandum of understanding (MOU) guides how the Forest 

Service cooperates with New Mexico. This MOU has been signed by almost all of the other land 

management agencies/organizations in the state.

141. The DEIS needs to concentrate more on what series of events led to the introduction 

of the invasive species in order to find the cure. Herbicides will make the problem 

worse by furthering the imbalance that caused the weed infestation in the first place. 

(124-50)

The use of herbicides at the level proposed is intended to return the balance back toward the 

native species that are currently being driven out by invasive plants. As part of an integrated 

approach, many other methods would be available to use to encourage the return of native plants 

once the invasives are set back, but the invasive plants are so aggressive that without some level 

of intervention, the natives would not be able to compete and would continue to lose habitat space 

to the invasives.

142. Many of these so called weeds have medicinal value and local herbalists gather 

them. (212-312)

This is noted in the DEIS text. Two species considered invasive elsewhere (St. Johns Wart and 

wild licorice) have been left off the list here (DEIS/FEIS p. 16). A discussion of the cultural uses 

is included in the DEIS/FEIS.

Costs

143. Costs of the project are too high. The benefit of spending $1.3 million to deal with 

only 0.5 percent of the forest is too much. (40-303)

The DEIS/FEIS in Chapter 1 explains the need to act to control the populations of invasive plants 

on the two forests. The costs of controlling these now are less than the eventual costs of doing 

nothing because once the populations reach a certain size, the measures needed to deal with them 

will be even more expensive than those proposed now.

Cultural Resources

144. Please document site-specific conflicts, if any, between culturally important plants 

and invasive plants. We suspect such conflicts are minimal and that imagined

conflicts are used to justify the project. (123-230)

The DEIS/FEIS discusses the impacts of no action to traditional use plants (DEIS pp. 16, 67, 144, 

145 and 166). The FEIS expands somewhat on this discussion to clarify the point that invasive 

plants can reduce the diversity of plants and so the availability of culturally important plants. In 

particular, where invasive plants affect culturally important plants near roads, where people go to 

find them, there would be a reduction in their availability. Although admittedly limited, these 

impacts can be avoided if invasive plant treatments are pursued. (FEIS pp. 149)

Emphasize Objectives

145. The DEIS needs to focus on the goal of what we want in place of the invasive plants, 

not simply getting rid of them. (125-55)

The Forests agree that an important goal of invasive plant control is knowing the desired 

vegetation objectives for a given site. The “Purpose and Need” section and “Vegetation” section 

Final Environmental Impact Statement – Invasive Plant Control Project 345
Appendix 9 • Response to Comments

describe the vegetation condition that is desired for each type of vegetation on the two forests. 

Chapter 3 describes the current condition and the effects of doing nothing to that condition, as 

well as the effects of taking action.

146. The purpose needs to be clarified to state that time is of the essence in order to meet 

the agency objectives to not only deal with the problem on its own land, but also 

deal with it so adjacent land owners do not suffer from inaction. (126-194)

The “Purpose and Need” describes the reason for taking some plant control actions. Chapter 3 

describes the impacts of taking no action as well as taking one of the three possible action 

alternatives. One of the purpose statements mentions being a good neighbor.

147. The Forest Service, after all, is supposed to be developing management objectives 

that reflect public option and the Forest Service has made no attempt to determine 

what members of the affected communities want classified as invasive. We are 

particularly concerned with the classification of the Russian olive, saltcedar, and 

Siberian elm as riparian invasive species. In a recent article in La Jicarita News 

(November 2003) David Theodoropoulous, a conservation biologist and author of 

“Invasion Biology, Critique of a Pseudoscience,” is quoted as saying that “hysteria” 

guides land management agencies and the academic community as well in making 

these decisions. He goes on to say that categorizing certain species as “native, alien, 

invasive, and aggressive” is “subjective, superficial, and entirely unbiological.” The 

article also documents the controversy in the Galisteo watershed regarding the use 

of Arsenal to eradicate saltcedar and quotes Jan-Willem Jansens of Earthworks: 

“[W]e have tinkered so much with our landscapes and waterways, saltcedar is one 

of the only species that can grow in the basin.” He categorizes this as “symptom 

mitigation,” which does not get at the heart of the problem. We suggest that the 

same may be true of our forest waterways. (127-232)

The management objectives are found in places such as the Forest Plan, which is developed 

through a public process. Other objectives are set through ESA recovery plans, such as one for 

willow flycatcher. Local needs are considered through other policy statements, such as the 

Northern New Mexico policy. Saltcedar has well documented ability to overrun a riparian area 

with ecological effects, such as reducing diversity from multi-species, multi-storied cover to a 

single species, monoculture. Although it may use water at a similar rate as native tree species 

along streambanks, its deeper root system means it can move away from the bank and displace 

grass and shrub species that do not require as much water, thus drying out the upland as well. In 

addition, along the bank, the density of saltcedar is much higher than native species for a given 

site and so tend to use more water.

148. We would like a diverse plant community, perhaps grasses and legumes, perhaps 

shrubs and trees, that is tolerant of climactic extremes, is stable requiring little 

maintenance, and optimally provides productive return. (128-233)

The objectives for a particular site will vary, but in general, this objective of diversity is shared 

across the Forests for a given potential plant community.

Saltcedar Objectives

149. Rio Grande banks were not taken over by a foreign type. Saltcedar has spread on 

land disturbed by farming and construction, and in river basins of controlled and 

346 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 9 • Response to Comments

depleted rivers. Cottonwood seedlings are dominant in flood plains, but often rivers 

do not have enough water or land to make a flood plain. Saltcedar evaporation rates 

are not significantly different from cottonwood. (211-311)

The DEIS/FEIS describe the need to control saltcedar on forest lands. Saltcedar affects areas 

along rivers and streams, primarily on banks where it displaces native cottonwood and willow. 

Research noted in the DEIS indicates that individual saltcedar may take similar amounts of water 

as cottonwood and willow, however, the high density within saltcedar stands means that for a 

given acre, saltcedar takes up more water than the same acre in native vegetation. Another impact 

occurs to upland areas close to riparian habitats because of the deep root system that can displace 

grasses and shrubs (DEIS/FEIS p. 15).

Technical Advice

Corrections and Clarifications

150. Page 30 the petition mentioned was not from CAPE. More than 1,000 people. I 

collected the names. Not CAPE.

(129-491)

The FEIS has been revised.

151. Page 8 of the DEIS contains “Environmental Consequences Summary” however it 

fails to document the basis for the statements regarding no significant consequences. 

NEPA requires that such statements be supported and disclosed. (130-39)

The summary relies on information in the DEIS/FEIS as source.

152. Under E02. 07b, there is a reference to MTST, but this is not explained in the key. Is 

this a typographical error, or an oversight in the Weed Name and 9 Abbreviation 

list? (131-400)

The FEIS has been corrected to include this abbreviation.

153. In addition, we suggest that the acreage (45) of knapweeds be broken out by type; 

control methods needed for Russian knapweed are very different than those which 

can be used for spotted knapweed (Page 18). (133-402)

The “Purpose and Need” section of the DEIS does not break out the specific treatment method for 

each species of knapweed. This section is outlining the reason some action is needed. In the 

treatment appendix that describes individual treatment units, the various knapweeds are proposed 

for treatment by a method appropriate to specific species.

154. Page 35, Herbicides - Imazapic and imazapyr should also be included in this list, 

particularly since they are both very low toxicity herbicides. Also, the statement is 

made that “Herbicide mixtures may only be used when there are no known 

synergistic effects such that the toxicity of the mixture is not greater than either 

herbicide used alone. “ However, in the Appendix, it is stated that the possibility of 

such an increased effect is highly unlikely. This seems inconsistent, and perhaps it 

should specify that such effects have only been observed with the use of picloram 

mixtures. (134-406)

Imazapic and imazapyr have been added to the list in the FEIS.

Final Environmental Impact Statement – Invasive Plant Control Project 347
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155. Page 37, Manual Methods - The statement is made that “If enough root mass is 

removed, the plant may be destroyed. “ This is not generally true of the rhizomatous 

plants and creeping perennials, such as Johnson grass and Canada thistle. Trying to 

remove the root is likely to leave bits and pieces behind, which will actually multiply 

the number of plants rather than eliminate the original one. (135-407)

The DEIS/FEIS notes under “Manual Methods” that this method would be most often applied to 

small populations of herbaceous weeds that spread primarily by seeds rather than through root 

sprouts.

156. Page 37, Controlled Grazing - This is generally a good discussion of grazing 

impacts, but it should be mentioned that although goats “appear to effectively 

reduce” seeds in their digestive tracts, it only takes a few seeds to begin a new 

population of an invasive plant, particularly when planted with fertilizer packets. 

(136-408)

It is noted in the DEIS/FEIS under “Controlled Grazing” that animals should be confined to a 

restricted area for an appropriate length of time after moving from an infested area when there is 

a concern that viable weed seeds may be spread through the animals’ feces.

157. Alternative D: Herbicides Only Page 41, Adaptive Strategy - This gives the 

impression that it is always possible to dig out invasive plants. For some species, that 

may be impossible; some put roots down 15-40 feet in depth, and cutting may even 

result in several plants growing from one (e.g., Russian knapweed). Using a lower 

application rate may be inconsistent with label 4 specifications. (137-409)

This discussion belongs in the Adaptive Strategy, which is a peer header, not subheader of 

Alternative D. The intent of the example is to provide a case where minimal effort would be 

needed to deal with a weed population (assuming that the species in question can be control with 

the manual method described). It is not intended to imply this would be the only method used. 

The paragraph continues with another example of adaptive management in response to 

monitoring and is not intended to imply that all spring applications would be changed to fall 

treatments. The format of this section has been corrected in the FEIS to clarify that this applies to 

all alternatives.

158. Page 43, near the bottom - “For example, a Priority 1 weed species (Canada thistle) 

if the size of the infestation is more than can be hand pulled (more than 2 acres).” As 

a creeping perennial, Canada thistle would be next to impossible to hand-pull with 

effective results. We are unaware of any case in which the Canada thistle has been 

effectively removed with hand pulling. Pulling would simply leave many, many bits 

of roots to re-sprout. We recommend you use another example like spotted 

knapweed. (138-411)

This example will be changed to reflect the suggestion.

159. Page 43, Table 9 - We suggest the following revision: “Examples include nonherbicide methods or herbicides and/or application methods having very low risk.” 

There are several other places in the document where adding this phrase would also 

be appropriate. (139-412)

The text of the FEIS has been revised to clarify this point.

348 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 9 • Response to Comments

160. Affected Environment and Environmental Consequences Page 72, bottom, under 

Environmental Consequences-Vegetation, Alternative B - The statement is made 

that “It is expected that at least the grasses or other early seral plants would recover 

within treated areas within the first growing season. With drought conditions in 

New Mexico, good grass recovery may take several years on dry sites, although if 

the site has not been degraded for too long, partial recovery might occur within a 

year or two with rainfall at the right time. In fact, however, it is more likely that 

native weeds would move in first, followed by the grasses, assuming the invasive 

plants were kept under control. Perhaps this could be modified to read, “It is 

expected that at least the grasses or other early seral plants would begin to recover 

within treated areas within the first growing season. (140-413)

The FEIS has been revised to clarify this point.

161. Page 106, under Fish and Aquatic Resources, Environmental Consequences - This 

discussion, with respect to “worst [Note: corrected spelling needed] case analysis” 

for picloram seems to go to an extreme that would never occur. We question 

whether it contributes to the impact assessment (Appendix 5). The amount of 

picloram that would be used would be so limited (or should be, since it is not needed 

for controlling more than a couple of species) that it would seem to make this whole 

discussion questionable. (141-414)

This comment refers to the worst case scenario used to evaluate risk to the aquatic environment. 

The analysis is described in Appendix 5 as a way to determine the potential for affecting aquatic 

systems as a result of project activities, and in turn, to demonstrate the potential risk to aquatic 

systems. The following assumptions were made:

o That all invasive populations were to be treated only with herbicides (Alt. D);

o The choice of picloram as the herbicide to be used on all treated acres was intended to 

define the herbicide with the highest risk quotient to aquatics;

o All acres would be treated in a 1-year timeframe, rather than the 5- to 10-year timeframe 

outlined in the proposed action;

o Delivery rates of herbicide (picloram) were segregated by potential for runoff by defining 

those soils/sites where the highest potential exists versus sites with a lower potential;

o Two flow rates were utilized to define the greatest potential for dilution (high flow–

spring) of delivered herbicide and lesser levels of dilution (low flow–fall). 

This modeling approach was selected for several reasons, but mainly because it was successfully 

used in other invasive plant environmental impact statements, such as completed on the Bitterroot 

National Forest in Montana.

The approach contributes the following to the analysis:

o It establishes a baseline that all other alternatives can be compared against.

o It defines (under the assumptions used) that the risk to aquatics is very low under the 

preferred alternative, the timeframe under which these treatments are proposed to occur, 

and locations of those treatments with respect to proximity to potentially affected aquatic 

resources.

o It defines watershed areas where risk to the aquatic environment is greatest given the 

limitation of streamflow as a diluting factor for that herbicide that potentially could be 

Final Environmental Impact Statement – Invasive Plant Control Project 349
Appendix 9 • Response to Comments

delivered (Ponil and Upper Jemez) and offers to the decision maker an evaluation of risk 

for their consideration in the decisionmaking process

o It helps to validate the preferred treatment method, the timing of that treatment (spring 

versus fall for Ponil and Upper Jemez), and the extent of treatment on an annual basis 

within those watershed areas where risk to aquatics may be a concern. 

As noted in the FEIS, the approach also forms the basis for determining that risk of harm is 

extremely low, as long as all applications are conducted within the scope of legal requirements 

(applied according to label directions, etc) and other required mitigation. 

162. Page 107, bottom paragraph, Alternatives B and D - The statement is made that 

“Risks tend to be lower on well-vegetated forests and rangeland where soil 

infiltration is typically greater than precipitation.” This sentence should be clarified. 

(142-416)

The sentence has been changed in the FEIS to reflect this suggestion.

163. Page 109, Cumulative Impacts - If the “Herbicide applications on-going by the 

Forest Service, as well as by others, can potentially have cumulative effects on 

aquatic resources,” it would suggest those herbicides are not being applied 

appropriately. Properly applied herbicides for invasive plant control (i.e., applied 

when rain is unlikely, applied in accordance with the label, and applied with low 

impact methods) should have little or no chance of reaching aquatic resources, due 

to natural breakdown, adsorption by soil (e.g., glyphosate), and absorption by the 

plants. (143-417)

This comment suggests a strong rationale for the proposition that herbicide application should not 

result in a cumulative effect if applied appropriately (timing, proximity to water, etc.). However, 

the uncertainty of actions by others can not be overlooked. The FEIS has been augmented with 

the following:

“The potential cumulative effect to aquatic resources will be minimized by proper 

application procedures, such as – applied when rain is unlikely, applied in accordance 

with label direction and using low impact application methods. This will greatly reduce 

the likelihood of the applied herbicide reaching the aquatic system.” (FEIS p. 114)

164. Page 119, Water Resources. Environmental Consequences - Again, we recommend 

adding imazapic and imazapyr to this list. (144-418)

These active ingredients have been added to this discussion in the FEIS.

165. Page 144, Heritage Resources. Environmental Consequences. Alternative B. 

Archeological Resources - The statement is made that “In general, herbicides do not 

have the resident time of pesticides. . .” Did the writer intend “residue” instead of 

“resident”? Also, herbicides are pesticides; did the writer intend to refer to 

“insecticides”? If so, this would be an incorrect statement, since there are 

insecticides with a half-life of two days (e. g. Monitor), much lower than many 

herbicides. We recommend removing the statement altogether since it does not 

appear to contribute to the discussion. (145-420)

The correction is made in the FEIS with the term persistence used instead of “resident.”

350 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 9 • Response to Comments

166. Page 161, Livestock Grazing. Environmental Consequences. Cumulative Effects -

There are numerous cases in which livestock have probably been the major 

contributor to the spread of invasive plants—e. g. , mesquite (in much of the 

Southwest), musk thistle (on the Mescalero Apache Reservation), to name just two. 

It would be more accurate to state that “It is unknown to what extent livestock 

contribute to the spread of weed seed in the allotments, but they likely add to other 

sources of weed spread by. . .” (146-421)

The DEIS/FEIS recognize that livestock are probably a minor contributing factor in the spread of 

weed seed in the allotments (DEIS pp 157, 161; FEIS pp. 163, 167), but notes that livestock 

grazing had not been found to be a major contributor to the spread of weeds within affected range 

allotments. The overall trends indicate that human activity along roads, trails, and recreation 

areas, along with disturbance at oil and gas well pads and the movement of seed or other 

vegetative propagules by water along riparian corridors were the major contributors. It also notes 

that this human activity (livestock grazing) can include the hauling of livestock on trailers, which 

could contribute to the spread of weeds if the vehicle comes from an infested area or drives 

through an infested area.

167. Page 169, Social-Economics. Environmental Consequences, Alternatives B, C, and 

D—Experience has shown that it may be difficult to get volunteers back on the 

regular and continuous basis needed to hand remove invasive plants. (147-422)

In the FEIS, additional discussion of the likelihood of volunteer efforts was included. Experience 

has shown the difficulty of engaging long-term volunteer efforts, but the possibility remains open.

168. Page 170, Table 52 - Vinegar is not a labeled herbicide and would not be a 

concentrated enough formulation of acetic acid to kill most invasive plants. The 

testing done has indicated a 10 percent acetic acid solution at minimum, or twice 

that of off-the-shelf vinegar, is needed for those species that could be controlled with 

acetic acid. If this is to be a discussed method of control, then the potential for 

changing soil pH should be mentioned somewhere in the text. (148-423)

This comment pertains to the last line of Table 52 on DEIS page 170. The FEIS has been changed 

to reflect this concern. The entry for vinegar has been clarified to note it would be more properly 

referred to as acetic acid if concentrations exceed 8 percent. The use of acetic acid has not 

undergone a Forest Service risk assessment (or EPA registration as an herbicide) and so is not 

available for use by the Forest Service. In order to use it, the effects to safety, soils, etc., would 

need to be assessed. The adaptive strategy proposed in the action alternatives would be a suitable 

mechanism to conduct this assessment.

As noted in the comment, the potential effects to soil pH resulting from application of acetic acid 

as an “herbicide” to areas of invasive plants may or may not be considered a detrimental effect. 

Since vinegar/acetic acid are not proposed for use at this time, they are not included in the details 

of the effects analysis. The context of the mention of acetic acid in this part of the DEIS/FEIS is 

for economic analysis comparison.

169. Page 174, Human Health and Safety. Environmental Consequences. Alternatives B 

and D - The risks to the general population are very low. Only if someone were to 

walk or drive into the spray zone during or immediately after herbicide application 

would they be likely to have any contact with the herbicides in the quantities and 

Final Environmental Impact Statement – Invasive Plant Control Project 351
Appendix 9 • Response to Comments

locations being used, or for that matter, even to be aware that spraying was being 

done. (149-424)

The FEIS has been clarified to reflect the evaluations found in the respective risk assessments.

170. Page 175, same section - The EXTOXNET Web site states that studies have shown 

that picloram has a half-life of 20 to 300 days, not 3 years, as stated here. (150-425)

The reference to half-life and persistence have been reviewed in the FEIS and text was clarified 

where possible. The passage cited in the comment refers to the duration that picloram remains 

active in soil, not simply its half-life.

171. According to the EXTOXNET Web site, of the 15 studies reviewed, 12 showed a 

half-life of 90 days; only 3 showed greater than 90 days, and that was under arid 

conditions, as previously mentioned. (151-426)

The reference to half-life and persistence have been reviewed in the FEIS and text was clarified 

where appropriate. As noted in the risk assessments, the variability in half-life makes if difficult 

to rely on a single number.

172. Page 176, Alternative C (No herbicides) - There is a potential of injury to staff from 

fire. This should probably be discussed in more detail covering smoke inhalation, 

burning, etc. (152-427)

The FEIS has been updated with a discussion of the health risks of using fire as a weed control 

method.

173. Page 197, Appendix 1 - Past, Present, and Future Weed Control Activities - The 

organizations mentioned here are more correctly referred to as “Cooperative Weed 

Management Areas,” or CWMAs. Below, under San Juan County, the Pulling 

Together Grants are not from the U. S. Fish and Wildlife Service (USFWS), but 

from the National Fish and Wildlife Foundation, or NFWF. (153-428)

The FEIS Appendix 1 has been changed to reflect these corrections.

174. Page 216, Siberian elm - Some Siberian elm have, in fact, grown taller than 40 feet 

in New Mexico; there are trees that are approaching 50 to 70 feet. It would also be 

useful to mention that densities as high as 5,000 stems per acre have been counted in 

a riparian restoration project in Tijeras in Bernalillo County (Ciudad Soil and 

Water Conservation District [SWCD]). (154-429)

Text in Appendix 2 has been revised to include this information.

175. Page 217, Yellow Starthistle - Yellow Starthistle quickly establishes monocultures, 

even in ungrazed and undisturbed areas, since it comes up before native plants in 

the spring. (155-430)

Text in Appendix 2 has been revised to include this information. 

176. Page 221, Clopyralid methyl - This is an incorrect name. Clopyralid is not a methyl 

formulation. It is a monoethanolamine or triethylamine salt. (156-431)

The header and text in Appendix 3 of the FEIS have been corrected. 

352 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 9 • Response to Comments

177. Page 225, Hexazinone - We recommend the removal of hexazinone from 

consideration since it is not the preferred herbicide for any of the invasive species. 

(157-432)

Hexazinone has a completed risk assessment that discusses the risks of using this herbicide. 

Although as noted in the risk assessment, it is generally used for conifer release, there may be 

instances when it is most effective on an invasive plant found on the two forests and so may be 

appropriate to use where it can be effective.

178. Page 228, Imazapyr - It should be mentioned that imazapyr is “rain-fast” in two 

hours. Also, since imazapyr is used at extremely low concentrations (e. g. , 1 percent 

Arsenal for foliar applications), only those applicators actually mixing the herbicide 

would be at risk. (158-433)

The FEIS has been revised to include more information from the risk assessments.

179. Page 230, Picloram - Again, the half-life of picloram is generally accepted to be 20 to 

300 days, with an average half-life of 90 days (EXTOXNET). “Increasing soil 

organic matter increases the absorption of picloram and increases the soil residence 

time” (EXTOXNET). Since most soils in New Mexico are not generally known to 

have a very high proportion of soil organic matter, the longer half-life is improbable 

on the forests, though might be found in bogs. (159-434)

A number of comments discussed the range of data that describe the “half-life” of different 

herbicides. Many of the statements on the half-life showed a wide range. The FEIS has been 

reviewed and clarified the relationship between half-life and persistence with regard to how they 

factor in to the evaluation of potential harm. As noted in the risk assessments, the environmental 

fate of each herbicide depends on a large number of factors, ranging from the actual herbicide 

formulation (acid, ester, etc.), whether the herbicide breakdown occurs in water, soil, or the target

plant; exposure to air, sunlight, soil micro-organisms, soil chemistry (pH) application method, to 

soil conditions (pH, etc.). Different herbicides can be classified in general by their persistence 

(long lasting vs. short lived).

The potential for adverse effect lies with several other factors, however, such as mobility and 

solubility. For example, an herbicide formulation may have a short half-life but moves more 

rapidly through a system because of its solubility. In contrast, an herbicide formulation that has a 

long half-life but that binds to soil because it is insoluble would pose less harm.

As noted in the risk assessments and the FEIS, the number of variables makes predicting for all 

the possible outcomes difficult. However, the way to manage for these possibilities is to use each 

herbicide formulation according to the label directions, which have been developed to assure a 

low risk outcome by incorporating these many factors. For instance, picloram should not be used 

near water because it is both persistent and mobile. 

180. Page 231 - It is a bit misleading to state that “There have been some concerns 

expressed that picloram acts synergistically with 2,4-D or other ingredients to cause 

chronic effects on wildlife. “ The statement provided in EXTOXNET from one 

publication only is that there may be “additive” effects when used with other 

pesticides. If this statement is to be included in the document, a reference should be 

given. There is a reference provided in EXTOXNET. (160-435)

Final Environmental Impact Statement – Invasive Plant Control Project 353
Appendix 9 • Response to Comments

The FEIS has been revised to include more context from the risk assessments. This concern has 

been noted in the risk assessments for both 2,4-D and picloram, specifically related to 

formulations of Tordon 202c and Tordon 75D. Neither of these formulations is used by the Forest 

Service according to the risk assessments.

181. Page 233, Triclopyr - Triclopyr, at 50 percent mixed with water, is also effective in 

killing Siberian elm using cut stump treatment when applied mid summer or fall, 

and in late winter before budding. (162-436)

Siberian elm has been added to the species susceptible to the cut-stump treatment with triclopyr.

182. Page 234 - It should also be mentioned that it is the ethanol in Garlon 3A ® that can 

contribute to eye damage. We recommend that Siberian elm be included in the list 

in the paragraph beginning “On preserves across the U. S. . . (163-437)

The FEIS has been updated to be consistent with the risk assessment. Ethanol is discussed under 

“other ingredients.” Siberian elm has been included with the other species.

183. Page 235 - It should probably be mentioned under what conditions the half-life of 

triclopyr was found to be 314 days (with citation). Again, this is a bit misleading and 

without such an explanation could unnecessarily raise some concerns. (164-438)

The text has been reviewed and revised to clarify this point. As noted in previous responses to 

comments about persistence, the exact half-life of an herbicide can be variable depending on a 

wide number of environmental conditions. These conditions are known for each herbicide and the 

use restrictions are developed taking these conditions into account. 

184. Page 235, bottom - “Grazon ® “ is discussed here. Grazon ® is a picloram and 2,4-D 

formulation and would not appear to be appropriate in a discussion of triclopyr. 

(165-439)

The FEIS has been corrected, assuming Garlon was the intended herbicide formulation name.

185. Page 236, Inert Ingredients - We strongly recommend that you not restrict 

consideration of adjuvants to include only Phase. There are other excellent 

adjuvants, like JLB for basal spraying with Garlon 4; and LI700 may be beneficial 

in some areas. Environmental toxicity data is available on a number of adjuvants. 

There is also toxicity data available on Cide-Kick for aquatic organisms. April 

Fletcher, FWS Pesticide Reviewer, can provide this information via e-mail, or 

request at 505-248-6632. (166-440)

The risk assessments for herbicide formulations takes adjuvants into account on assessing risk 

and so this part of the FEIS has been expanded and clarified to include more of that information. 

186. Page 238, Table 57, under Factors Affecting Hazards of Herbicides - This table is 

somewhat misleading, since the toxicity to wildlife species may, in some cases like 

triclopyr, be less than the LD50 for rats. Triclopyr toxicity as low as 1698 mg/kg is 

reported in some bird species. A more complete table would be beneficial. Toxicity 

data is available in summary form from the British Crop Protection Association EPesticide Guide. (167-441)

This table is under the human risk discussion to describe the potential hazard to people, as 

extrapolated from studies for rats. The risk assessments describe how an RfD is developed by 

354 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 9 • Response to Comments

dividing a dose where no adverse effects are found by factors of 10 to determine the level of 

concern. This has been added to the text. A similar process is used for wildlife to establish a level 

of concern. This has also been expanded in the FEIS with more information from the risk 

assessments for each herbicide.

187. Page 240 - Ethanol is discussed as “an eye irritant and a considerable toxin if 

ingested” with respect to Velpar L, and also Garlon ® . It should be mentioned that 

ethanol is found in alcoholic beverages, and that it is volatile and, thus, not likely to 

remain in the environment for long after dilution and application. (168-442)

The risk assessments have provided a broader context for these discussions. No change was made 

in the text.

188. Isopropyl alcohol, mentioned with reference to Transline, a clopyralid formula, as 

“an approved food additive” (actually, it is a solvent used in preparing flavorings, 

and not commonly an “additive”) is also the reason for potential eye irritation with 

that pesticide. (169-443)

The risk assessments have provided a broader context for these discussions. No change was made 

in the text.

189. Page 241, top of page, under Impurities, Adjuvant and Inert Ingredients in 

Herbicide Formulations - The dyes that are in most herbicide formulations, like 

Arsenal and Roundup Pro, are not in adequate amounts to be even visible after 

mixing with water, and generally, not after application. They are usually added to

ensure that somebody does not think the herbicide is water and drink it. This 

discussion needs to clarify that it is discussing dyes which are added sometimes at 

the time of application to make it easier to determine spray coverage. (170-444)

The text has been clarified in the FEIS.

190. Pages 245-246, under Herbicide Drift - Somewhere in this discussion aromatics 

should probably be mentioned since the aromatic components of herbicides may 

spread beyond the spray drift zone immediately after application. These would be 

present for only a short time due to their volatility. (171-445)

The text in Appendix 3 has been expanded to include more information from the risk 

assessments. Specific description of aromatic properties of specific formulations has not been 

added because the relationship of each proposed herbicide to drift has been covered in the context 

of the risk assessments. 

191. Page 248, under Uncertainty - In the paragraph beginning “Nevertheless, there are 

many reports . . .” it should be mentioned that exposure in cases where alterations 

of the immune system or probable carcinogenesis were suspected was generally a 

result of exposure at excessive levels that neither the general public, nor even staff 

applying the herbicides, would likely encounter in the Forest Service’s applications. 

(172-446)

The text in Appendix 3 has been expanded to provide more information about the analysis of risk. 

The text in this paragraph has been revised to reflect more clearly the conclusions of the risk 

assessments in light of these uncertainties.

Final Environmental Impact Statement – Invasive Plant Control Project 355
Appendix 9 • Response to Comments

192. Page 249, under Wildlife Risk Assessment - It states that “there is no evidence of 

synergistic effects or hormone disruption from any of these chemicals.” Does this 

statement conflict with the prior discussion of combinations of picloram and other 

herbicides resulting in enhanced effects on the liver in animals? Appendix 4 -Effects 

of Nonherbicide Weed Control Methods Page 255, Biological Control - the 

statement that “the testing process for a biological control agent is typically 3 to 4 

years” is misleading. The entire research and testing process may take up to 20 

years for each organism. After researching the organisms in their native land, 

extensive testing is done in the laboratory before they are tested in the field. In

short, it is an extremely time-consuming and expensive process. (173-447)

The reference on page 249 (DEIS) is to the formulations discussed in the risk assessments. The 

earlier reference to combinations of 2,4-D and picloram mentions the lack of evidence that the 

effects are synergistic. The FEIS has been updated to reflect the time it takes to approve a 

biological agent. The Branch Chief of Pest Permit Evaluations for USDA APHIS Plant Protection 

and Quarantine estimated that an average time for research and approval of a new biological 

control organism may be 3 to 4 years, however, he clarified that the range could be as short as 1

year or as long as 20-plus years, depending on the complexity or previous history with the agent. 

The longer timeframes are especially true where there is a lack of host specificity or questionable 

specificity.

193. Page 256, Mechanical - It should be mentioned that mechanical treatment of 

creeping perennials and rhizomatous species would likely enhance, rather than 

control, the plants, since any root parts remaining in the ground could re-sprout. 

(174-448)

The DEIS (pg. 38) mentions that these methods have not been demonstrated to be effective in 

eradicating or substantially reducing weed infestations, and typically require frequent repeat 

treatments. The FEIS has been clarified to reflect this comment (FEIS p. 292).

194. Page 256, under Controlled Grazing - It should be mentioned that horses are not 

very good for controlling weeds, since they tend to select the grasses over the weeds 

and chew them down very close to the ground, decreasing their vigor. Cows, on the 

other hand, wrap their tongues around plants before biting them off and, thus, are 

not as likely to inhibit recovery of native grasses. It should also be mentioned that to 

effectively use livestock to control invasive plants is a very labor-intensive and 

highly managed system, and that simply using livestock is not likely to achieve 

desired results, particularly since many kinds of grazing animals will NOT choose 

the invasive plant over the natives (sheep on leafy spurge being an exception). Also, 

it should be mentioned that quarantining animals before moving them into or out of 

an area is important to prevent spread of invasive plant seeds to non-infested areas 

via feces, and that coats should be checked for weed seeds. (175-449)

Controlled grazing was also discussed in the DEIS/FEIS (DEIS pp. 37, 38; FEIS 39, 40). The 

discussion in that section covers many of the points of the comment.

195. Page 257, under Prescribed Burning - Whether prescribed burning will help control 

invasive plants will depend on which plants one is attempting to control. Some, such 

as some invasive grasses and saltcedar, are adapted to and enhanced by burning. In

the case of Yellow Starthistle, some studies have shown that burning 2 years in a 

row at exactly the right time can result in significant control and native plant 

356 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 9 • Response to Comments

restoration. This research was reported at a recent Western Society of Weed Science 

annual conference and should be in their Proceedings. (176-450)

The DEIS (pg. 257) supports the comment, noting that for some species, prescribed burns can 

unexpectedly promote an invasive, such as when their seeds are specially adapted to fire, or when 

they re-sprout vigorously.

196. Appendix 7 - Table 62 - This table is difficult to follow. We recommend that it be 

supplemented with a discussion of the proposed control methods in the discussion of 

species, Appendix 2. (177-451)

A table has been added to the FEIS in Appendix 3 to describe in general the target plants for each 

herbicide (Table 52). Because of the variability of the likely use, however, a more detailed 

description has not been developed. 

197. We note that in the control methods proposed for Siberian elm, both mechanical 

alone and biological control are mentioned. The first is virtually ineffective for 

control of Siberian elm, as re-sprouting will occur even with very small trees, and 

the second, biological control, is not available for Siberian elm. We are also unaware 

of any available biological control for Russian olive. (178-456)

In the analysis for this project, some of the populations within the Jemez River project may have 

been identified as being proposed for biological control. Under a separate decision, they are 

already being treated with herbicidal control, which may be the most effective on Siberian elm 

and Russian olive. Other populations may have been mapped as being a small enough area to try 

manual control first. Each population would be evaluated prior to developing a treatment plan, 

which will take into account the factors of species, size and location of population, and known 

effective methods for control of that species in that situation. For mapping purposes, some of the 

complexes of invasive plants were combined and so would require this next step before 

implementation can occur.

198. And, finally, we are unaware of a biological control organism which has been 

proven to be effective on yellow toadflax, although it is possible that one is being 

developed. (179-457)

Several classical biocontrol agents are available to use against toadflaxes. However, the success 

of these agents remains largely unknown. A defoliating moth (Calophasia lunula), an ovaryfeeding beetle (Brachypterolus pulicarius), and two-seed capsule-feeding weevils (Gymnaetron 

antirrhini and G.netum) have been released in the U.S. and Canada to control all toadflax species. 

Particularly the flowering and seed feeding insects should help decrease seed production. 

A stem-boring weevil (Mecinus janthinus) and a root-boring moth (Eteobalea intermediella) also 

were released in Canada and the U.S. to control all species of toadflax. These species may help to 

control shoots and seed production as well as decrease root vigor, but data are unavailable to 

document their effects. Several of these classical biocontrol agents are available from the 

Colorado Department of Agriculture Insectary in Palisade. Very few published studies are 

available to determine whether grazing by livestock will effect any control of Dalmatian or 

yellow toadflax.

199. With respect to control of Russian knapweed, mechanical and grazing are unlikely 

to result in any control, and are likely to enhance the population, since the plant has 

a very deep (15 feet in 2 years, extending much deeper in time), adventitious root 

Final Environmental Impact Statement – Invasive Plant Control Project 357
Appendix 9 • Response to Comments

system which will result in multiple re-sprouts, increasing density of the infestation. 

(180-458)

Like other creeping perennials, the key to Russian knapweed control is to stress the weed and 

cause it to expend nutrient stores in its root system. An integrated management plan should be 

developed that places continual stress on the weed. Currently, the best management plan includes 

cultural control combined with mechanical and/or chemical control techniques. A single control 

strategy, such as mowing or an herbicide, usually is not sufficient.

While two mowings, 8 weeks apart (first at bud-growth stage), suppressed Russian knapweed 

during that year, the weed recovered vigorously the subsequent season. Perennial grasses 

established in the mowing treatments but much less than in herbicide treatments. Two mowings 

per year for several years may control Russian knapweed better, but further research is needed to 

test this hypothesis. Currently, no biological control is available for this weed.

(Pers. comm. with K.G. Beck, Colorado State University Cooperative Extension weed science 

specialist and professor of weed science, bioagricultural sciences and pest management.)

200. Russian knapweed is a very difficult species to kill, and the most effective method 

which has been found to date for New Mexico is application of Tordon very late in 

the season as the plant begins to look dead. (181-459)

See response to comment 199.

201. Hoary cress is unlikely to be controlled with manual removal and grazing, as well. 

Imazapic is reported to be effective on it, however. (182-460)

Hoary cress is a very difficult weed to control, even using herbicides. Very small infestations may 

be controlled by diligent hand pulling or grubbing. Hand pulling of above ground plant parts is 

ineffective. Successful hand pulling or digging requires complete plant removal within 10 days 

after weed emergence through the growing season for 2 to 4 years. Hand pulling and digging can 

be a useful method for controlling new introductions of white top in riparian areas. Mowing to 

ground level during flowering reduces biomass and seed production, but does not provide longterm control. However, preliminary research results indicate that mowing integrated with 

herbicide use can be effective. Successful management of hoary cress requires integrated weed 

management. Integrated weed management includes combining strategies to prevent the 

movement of these weeds, contain existing infestations and integrating control methods to reduce 

weed infestations to tolerable levels.

202. Canada thistle is unlikely to be controlled with manual removal and grazing due to 

the fact that it is a creeping perennial and any small bit of root remaining in the soil 

will result in re-sprouting. (183-461)

Canada thistle is a creeping perennial that reproduces from vegetative buds in its root system and 

from seed. It is difficult to control because its extensive root system allows it to recover from 

control attempts. Combining control methods is the best form of Canada thistle management. 

Persistence is imperative so the weed is continually stressed, forcing it to exhaust root nutrient 

stores and eventually die.

Canada thistle allocates most of its reproductive energy into vegetative propagation. New shoots 

and roots can form almost anywhere along the root system of established plants. Tillage segments 

roots and stimulates new plants to develop. Shoots emerge from root and shoot pieces about 15 

358 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 9 • Response to Comments

days after disturbance by tillage. Small root pieces, 0.25 inch long by 0.125 inch in diameter, 

have enough stored energy to develop new plants. Also, these small roots can survive at least 100 

days without nutrient replenishment from photosynthesis.

The key principle to Canada thistle control is to stress the plant and force it to use stored root 

nutrients. Canada thistle can recover from almost any stress, including control attempts, because 

of root nutrient stores. Therefore, returning infested land to a productive state occurs only over 

time. Success requires a sound management plan implemented over several years. 

Mechanical control: Mowing hay meadows can be an effective tool if combined with herbicide 

treatments. Mowing alone is not effective unless conducted at 1-month intervals over several 

growing seasons. Always combine mowing with cultural and chemical control. Mowing at hay 

cutting stimulates new Canada thistle shoots to develop from its root system. 

(Pers. comm. with K.G. Beck, Colorado State University Cooperative Extension weed science 

specialist and professor of weed science, bioagricultural sciences and pest management.)

203. There are frequent references to hand-pulling or root plowing Canada thistle, as on 

page 43. Canada thistle is not adversely affected by these treatments, and may 

actually spread using these methods. Timed-interval mowing has proven effective 

along NM 518, NM 75, and NM 73 in containing thistles. The only changes made by 

NMDOT were to set mower height up to 6-8" and to change the timing of the 

regular scheduled mowing. USDA released a study which showed that spraying 

Canada thistle with vinegar at 5 percent acetic acid can be highly effective in 

reducing the tops. (184-462)

See response to comment 202. The study mentioned notes that using vinegar (5 percent acetic 

acid) can be highly effective at removing the tops of Canada thistle, which can deplete root 

reserves if applied repeatedly, and also notes that it works better in young plants. The adaptive 

strategy would not rule out using this method if it can be shown to be as effective as others being 

proposed and if it falls within the sideboards of the FEIS.

204. Root plowing or mowing Russian knapweed will spread the infestation and are not 

effective controls. Russian knapweed can be controlled by hand pulling, and some 

followup monitoring. In areas where smothering is desired, DeWill #5 landscapers 

fabric is an economical material to use, and it could be set in place with pins and 

covered with wood chips to disguise the site. By the time the fabric breaks down, the 

roots of invasive weeds will be starved out. Since the growth form of knapweed 

tends to be a monoculture, this would not have serious impact on native plants. 

(185-463)

Like other creeping perennials, the key to Russian knapweed control is to stress the weed and 

cause it to expend nutrient stores in its root system. An integrated management plan should be 

developed that places continual stress on the weed. Currently, the best management plan includes 

cultural control combined with mechanical and/or chemical control techniques. A single control 

strategy, such as mowing or an herbicide, usually is not sufficient. Russian knapweed forms 

dense, single species stands over time due to competition and allelopathy (biochemicals it 

produces that inhibit the growth of other plants). Tillage may be necessary to overcome the 

residual allelopathic effects of Russian knapweed. Seeding competitive, perennial grass species 

(cultural control) after Russian knapweed has been stressed by other control measures (setup 

treatments) is essential. Setup treatments may include chemical or mechanical methods.

Final Environmental Impact Statement – Invasive Plant Control Project 359
Appendix 9 • Response to Comments

Smothering may be an effective option for small patches of Russian knapweed, although in a 

forest setting, it may not be the preferred method. Roots from a recently established plant expand 

rapidly and may cover up to 12 square yards in two growing seasons.

(Pers. comm. with K.G. Beck, Colorado State University Cooperative Extension weed science 

specialist and professor of weed science, bioagricultural sciences and pest management.)

205. Vinegar at 5 percent acetic acid is effective in killing tops of all thistles, and can 

reduce vigor on Canada thistle roots with repeated top treatments. (USDA Study) 

(186-464)

U.S. Department of Agriculture researchers tested various strengths of vinegar on Canada thistle. 

(Daniels, 2003) They found that either a 5 or 10 percent solution of vinegar burned off the top 

growth of Canada thistle. The plants, however, regrew from the roots. See response to comment 

202. Vinegar at a concentration exceeding 8 percent is labeled as acetic acid. The use of acetic 

acid has not undergone a Forest Service risk assessment (or EPA registration as an herbicide) and 

so is not available for use by the Forest Service. In order to use it, the effects to safety, soils, etc.,

would need to be assessed. The adaptive strategy proposed in the action alternatives would be a 

suitable mechanism to conduct this assessment.

206. Digging rosettes is a waste of time on biennials. Wait and remove the seed heads. 

(187-465)

As suggested in the comment, because biennial thistles reproduce solely from seed, the key for 

successful management is to prevent seed production. Mechanically, this can be accomplished by

severing its root below ground with a shovel or hoe. Mowing can effectively reduce seed output if 

plants are cut when the terminal head is in the late-flowering stage. Gather and burn mowed 

debris to destroy any seed that has developed. Removing seed heads by hand is another method, 

although in a large infestation it may be very timeconsuming. K.G. Beck, Colorado State 

University Cooperative Extension weed science specialist and professor of weed science, 

bioagricultural sciences and pest management.

207. Correct name does not include methyl. (188-461)

The FEIS has been revised with the correct herbicide name.

Other Corrections

208. Page 73 discusses treatments in riparian areas/valley bottoms, but it fails to disclose 

that in fact 1,300 acres in these areas would be treated with herbicides (see Table, 

Page 70). The Page 73 discussion makes it sound like biological controls would be 

the main treatment, however Page 70 documents that herbicides will be a large 

amount of the treatment in these sensitive areas. (189-70)

The text has been clarified to show more exactly that about 1,140 acres of the 2,680 proposed for 

treatment in riparian/bottomlands would be biological methods.

209. Appendix 6 (Chemical Spill Prevention and Cleanup Plan) describes a reporting 

component for managing spills, but does not state to whom the reports shall be 

made. With respect to any discharge in such quantity as may with reasonable 

probability injure or be detrimental to human health, animal or plant life, or 

property, or unreasonably interfere with the public welfare or the use of property, 

360 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 9 • Response to Comments

the New Mexico Environment Department Ground Water Quality Bureau chief 

must be notified, and corrective actions may be required (20.6.2.1203 NMAC). (190-

235)

The Forest Service spill response team works closely with local officials during any emergency 

response. The FEIS has made this more explicit when describing the spill plan.

210. We also recommend that the discussion of the definition of a “weed” be removed; 

invasive plants are not just weeds, they are a serious threat and should be explained, 

as such, without the qualifying statements. (191-403)

The reason for using the terminology is stated in the DEIS/FEIS. Federal guidelines call for 

avoiding jargon and using understandable language, which encourages use of words that readers 

understand. As explained in Chapter 1, the use of the word in this context is well understood to 

the general public and in law (Noxious Weed Act). Finally, as admonished in “Elements of Style 

advised” (Strunk and White): “do not be tempted with a twenty-dollar word when there is a tencenter handy, ready and able.”

211. The methods used should be those which will achieve the best control of the invasive 

plants with the least negative environmental impacts within budget. (192-404)

This comment states one of the underlying purposes of using the adaptive strategy.

212. The best control of Russian knapweed (using picloram) has actually been as the 

plant just goes dormant in the fall, when it already starts looking dead. We 

recommend revising the wording of the statement to reflect such exceptions. (193-

405)

This advice is noted but the level of detail in the FEIS has not been changed. Specific 

implementation recommendations will take this kind of information as well as site-specific weed 

population conditions into account. 

213. Application rates should be consistent with those that have been found to be 

effective yet still permitted under the label. (194-410)

This is the understanding used during the analysis.

214. Page 131, Soil Resources. Alternative B - The mention of “requiring revegetation of 

bare soil where needed following weed control treatments” brings up concerns 

about the potential for using seed that is contaminated with invasive plant seeds. 

This should be discussed somewhere. Natural revegetation methods are generally 

superior to planting seeds, and there are numerous methods for modifying 

situations culturally and mechanically to encourage and support native plant 

restoration. The Soil and Water Conservation Districts are acquainted with many of 

these. (195-419)

This comment pertains to paragraph 5 on page 131 of the DEIS. It is stated in this paragraph that 

revegetating with mulch or seed after weed control on less than 1,000 acres of soil is proposed for 

herbicide treatment on soils with low revegetation potential. 

The criteria used in defining sites with low revegetation potential are based on properties of the 

soil taxa such as soil climate, pH, slope and texture. Often, soil map units with a rating of low are 

limited by soil climate and slope. The following statement has been added to the FEIS (p. 137):

Final Environmental Impact Statement – Invasive Plant Control Project 361
Appendix 9 • Response to Comments

On soils with low revegetation potential, the preferred recovery is natural revegetation. 

Mulching of these sites with certified weed-free straw is preferred to provide surface soil 

cover, which will offer protection from surface soil erosion and encourage natural 

revegetation of the site. Where natural revegetation does not occur, seeding with certified 

weed-free seed would occur.

Non-substantive Comments

General Comments

215. These comments are general in nature, without a clear tie to the project activities 

and their effects and, therefore, are not considered substantive. (900-900)

Alt C Preference

216. These comments provided a preference for Alternative C without supporting 

rationale are placed in this category and considered non-substantive. (1000-1000)

Volunteers

217. Some commenters volunteered to help extract noxious weeds by hand, shovel or 

other means. (93-500)

Volunteer efforts will be an important factor in the invasive plant control efforts of the Forests, 

and so volunteers are welcome.

Commenters

Table 68 displays the individuals/organizations who commented on the DEIS. Timeliness of the 

comment (came during the comment period) and the nature of the comment (substantive or not) 

are also noted in the right-hand columns of the table. Comment letters are found in full in the 

project record.

Table 68. List of People/Organizations who commented on the DEIS

Name Organization Timely Substantive

Alicia Adams Yes Yes

Adonae Anderson Yes No

Marta Ballen Yes No

Carol Bartelt Yes No

Joanie Berde Carson Forest Watch Yes Yes

Robert Berkelo Yes No

Carolyn Beste Yes Yes

Bonnie Bonneau Yes Yes

Sora Brodie Yes Yes

Seth Brown Yes No

Sheena B. Cameron Yes Yes

Nancy Campbell Yes Yes

Margaret Chapman Yes Yes

362 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 9 • Response to Comments

Name Organization Timely Substantive

Abigail Chapman Yes No

Mike Chavez Yes Yes

Rachel Conn Amigos Bravos Yes Yes

Rachel Conn The Weed Committee Yes No

Joseph Craglia Yes No

Frederic de Broeonier Yes No

Ron Dorn Yes Yes

Joan Duncan Yes No

Erica M. Elliott Yes Yes

Arthur Firstenberg Yes Yes

Andy Gold Yes Yes

Rhoda Goldfinger Yes Yes

Gail Haggard Yes No

Jerilou Hammett Yes Yes

Jerilou Hammett Yes Yes

Jewel Hammond Yes No

William (?) Harford Yes No

A Heikaus Yes No

Lois C. Herrmann Yes Yes

Sam Hitt Yes Yes

Sallie Hoops The Weed Committee Yes Yes

Nathan Houchin Yes No

Phoebe Hummel Yes Yes

Joelle Hunt Yes No

Jan-Willem Jansens Earth Works Institute Yes Yes

James J. Johnston Yes No

David P. Johnston Yes Yes

Barbara Jones Yes No

Claudia Kleefeld Yes No

Janet Knisley Yes Yes

Patricia A. Leahan Yes Yes

Judy Lister Native Plant Society of 

New Mexico--Taos 

Chapter

Yes Yes

Joyce Peny Luis Yes No

Phyllis Lutor Yes Yes

Susan MacMullin U.S. Fish and Wildlife 

Service

Yes Yes

Victor Martinez Yes No

Tracy McCallum Yes Yes

Ann McCampbell, MD Multiple Chemical 

Sensitivities Task Force 

of NM

Yes Yes

Final Environmental Impact Statement – Invasive Plant Control Project 363
Appendix 9 • Response to Comments

Name Organization Timely Substantive

Corrie McConahell Yes No

Joan McGrane Yes No

Alex Mexi Yes No

Malka Michelson Yes Yes

Sarah Montgomery Yes No

Jim Nellessen Native Plan Society of 

New Mexico

Yes Yes

David C. Nelson Yes No

Whitney M. Nieman Yes No

Jane Odin Yes No

Brett O'Haver BLM Cuba Office Yes Yes

Susan Ortt Yes No

Daniela Packee Yes No

Markus Pahlow Yes No

Jeannie Pearle Yes Yes

Bob and Carrol Pearson Yes Yes

Casey Peniston Yes Yes

Roger S. Peterson Sierra Club, Northern 

Group, Rio Grande 

Chapter

Yes Yes

Scott Pittman Yes No

Toby Pocock Yes Yes

Sarah L. Reeb Yes Yes

Nicole Romero Yes No

Nancy K. Ruiz Yes No

Julie and John Saiki Yes No

Mark Schiller/Kay Mattews Rio Pueblo/Rio Embudo 

Watershed Protection 

Coalition

Yes Yes

Mark A. Schuetz Yes Yes

Paula Seaton Yes No

Charlene Shildmyer Yes No

Lindsy Solomon Yes Yes

Sheryl Spangler Yes Yes

Stephen Spencer US Dept. of the Interior Yes Yes

Natalie Struck Yes No

Nicole Terry Yes Yes

Julie Terry Yes Yes

Nicole Thibadeau Yes Yes

Lymer L. Trew Yes Yes

David Trew Yes Yes

Ryan Triche Yes No

Jan Walker Yes No

364 Final Environmental Impact Statement – Invasive Plant Control Project
Appendix 9 • Response to Comments

Name Organization Timely Substantive

Robert Weber Yes Yes

Susan Westbrook Yes Yes

Patricia Whalen Yes Yes

Ana Willeum Yes No

Sylvia Williamson Yes Yes

Zachary Wilson Yes No

Sharon O'Neal Wirtz Yes Yes

Michael D. Wirtz Yes No

Marjorie Young Yes No

Samuel Ballen No NA

Gedi Cebas NN Environment Dept. No NA

John Conners No NA

Stuart King No NA

Jim Matison Forest Guardians No NA

Jeanne Simonoff No NA

Willa H. Tanas No NA

Comments Received on the Draft EIS from 

Federal, State, and Local Agencies and Elected Officials

Aside from comments received during regular consultation (ESA and NHPA), three comment 

letters were received from agencies: the Environmental Protection Agency (EPA); one 

consolidated comment letter came from the Department of Interior; and one consolidated 

comment letter came from the New Mexico Environment Department. The EPA rated the project 

as “LO,” or Lack of Objections.” The comments of the other two agencies have been considered 

and described above. Full text of their comment letters are found in the project record.

Final Environmental Impact Statement – Invasive Plant Control Project 365

Index

Adaptive Management .........................................................................................1, 4, 29, 35, 42, 63

mitigation measures associated with ......................................................................................... 30

suitablility for weed control....................................................................................................... 29

treatment objectives................................................................................................................5, 43

treatment priorities .....................................................................................................5, 44, 45, 46

Air Quality............................................................................................................................141, 144

Alternative B effects.........................................................................................................143, 144

Alternative C effects.........................................................................................................138, 144

Alternative D effects ............................................................................................................... 144

cumulative effects.................................................................................................................... 145

pollutant sources...................................................................................................................... 142

pollutants

carbon monoxide ..........................................................................................................141, 143

lead ...................................................................................................................................... 141

nitrogen dioxide................................................................................................................... 141

ozone ................................................................................................................................... 141

particulates....................................................................................................................141, 143

sulfur dioxide....................................................................................................................... 143

visibility

airshed classess.................................................................................................................... 142

Class I airsheds.................................................................................................................... 142

Class II airsheds................................................................................................................... 142

Alternatives

additional criteria....................................................................................................................... 46

Alternative A (No Action)................................................................................................3, 35, 36

Alternative B ..............................................4, 35, 41, 76, 111, 137, 144, 157, 177, 178, 181, 291

Alternative C ....................................................................................................4, 35, 41, 138, 183

effectiveness.......................................................................................................................... 99

Alternative D........................................................4, 35, 42, 78, 81, 110, 111, 144, 158, 178, 182

considered but eliminated.....................................................................................................35, 36

considered in detail.................................................................................................................... 35

mitigation measures..............................4, 6, 47, 79, 125, 139, 149, 150, 151, 181, 182, 183, 184

monitoring ................................................................................................................................... 4

monitoring requirements ....................................................................4, 6, 31, 35, 43, 47, 53, 146

American Indian Tribes............................................................................................................... 149

Aquatic Resources................................................................................................................108, 114

cumulative effects.................................................................................................................... 114

effects of action alternatives...............................................................................................60, 111

herbicides......................................................................................................................110, 112

picloram mixing model........................................................................................................ 113

Rio Grande cutthroat trout..................................................................................................... 60

soil erosion .......................................................................................................................... 115

effects of Alternative B

soil erosion .......................................................................................................................... 114

effects of no ation.................................................................................................................... 111

Rio Grande cutthroat trout........................................................................................108, 109, 113

Final Environmental Impact Statement – Invasive Plant Control Project 367
Index

Climate .......................................................................................................................................... 13

Cumulative effects

activities considered .................................................................................................................. 63

defined....................................................................................................................................... 63

other weed control actions......................................................................................................... 64

Decision framework ...................................................................................................................... 31

scope of...................................................................................................................................... 31

Forest Plans................................................................................................................................... 27

amendment, Santa Fe National Forest................................................7, 30, 35, 53, 127, 138, 179

Grazing

cumulative effects.................................................................................................................... 167

domestic livestock ................................................................................................................... 163

effectiveness of Alternative B and D................................................................................... 167

effectiveness of Alternative C ............................................................................................. 167

effects of no acton ............................................................................................................... 166

Herbicides

chemical loading...................................................................................................................... 127

fate of....................................................................................................................................... 125

inert ingredients....................................................................................................................... 280

type

2,4-D.............................................................................................................................167, 251

chlorsulfuron ....................................................................................................................... 253

clopyralid................................................................................37, 124, 206, 234, 235, 241, 255

dicamba ..........................................................................................................37, 124, 136, 257

glyphosate.................................37, 51, 110, 124, 136, 205, 235, 236, 242, 244, 259, 260, 281

hexazione............................................................................................................................. 262

imazapic................................................................................................................................. 37

imazapic............................................................................................................................... 124

imazapic............................................................................................................................... 265

imazapyr................................................................................................................................ 37

imazapyr.............................................................................................................................. 124

imazapyr.............................................................................................................................. 266

metsulfuron methyl.........................................................................................37, 124, 235, 268

picloram...37, 51, 110, 112, 113, 114, 124, 125, 126, 161, 233, 234, 235, 238, 241, 255, 266, 

272, 273, 274, 291, 292, 293

sulfometuron methyl............................................................................................................ 270

triclopyr ..............................................................37, 51, 67, 124, 235, 238, 244, 276, 277, 278

Heritage Resources...................................................................................................................... 146

archaeological sites...........................................................................146, 147, 148, 149, 150, 152

cumulative effects.................................................................................................................... 152

effects of action alternatives.............................................................................146, 150, 151, 152

Alternative B ................................................................................................................150, 151

Alternative C ....................................................................................................................... 152

Alternative D ....................................................................................................................... 152

herbicides............................................................................................................................. 150

effects of no action .................................................................................................................. 149

ethnographic resources.............................................................................146, 147, 148, 151, 152

mitigation measures

368 Final Environmental Impact Statement – Invasive Plant Control Project
Index

programmatic agreement............................................................................6, 77, 146, 150, 151

traditional cultural properties ...................................................................146, 147, 148, 149, 151

Hispanic communities................................................................................................................. 149

Holy Ghost ipomopsis

Alternative B effects.................................................................................................................. 80

effects of action alternatives...................................................................................................... 80

Human health and Safety............................................................................................................. 180

cumulative effects.................................................................................................................... 183

herbicides..........................................................................................................................180, 183

chemically sensitive people................................................................................................. 181

mitigation............................................................................................................................. 182

risk assessments................................................................................................................... 182

worker safety ....................................................................................................................... 182

knapweed................................................................................................................................. 180

leafy spurge ......................................................................................................................180, 216

Hydrologic Unit Codes (HUC).................................................................................................... 119

Indian Trust Assets...................................................................................................................... 149

Irretrievable and Irreversible commitments ................................................................................ 184

Issues............................................................................................................................................. 32

effectiveness.............................................................................................................................. 34

human health and safety............................................................................................................ 33

native vegetation........................................................................................................................ 34

wildlife....................................................................................................................................... 34

Land grant communities.......................................................................................................148, 149

Mitigation measures.......................................................................................31, 35, 43, 77, 80, 114

amphibians................................................................................................................................. 99

aquatic resources ..................................................................................................................... 113

herbicides............................................................................................................................. 112

Best Management Practices....................................................................................................... 47

groundwater............................................................................................................................. 126

herbicides................................................................................4, 40, 112, 125, 126, 139, 181, 182

Heritage Resoruces.................................................................................................................. 151

Heritage Resources.................................................................................................................... 52

tribal notification ................................................................................................................. 151

Holy Ghost ipomopsis............................................................................................................6, 50

Mexican spotted owl ................................................................................................................. 50

sediment................................................................................................................................... 126

Soil Resources......................................................................................................4, 126, 137, 139

BMPs............................................................................................................................125, 137

Southwestern willow flycatcher ................................................................................................ 50

TES wildlife .............................................................................................................................. 51

water.......................................................................................................................................... 51

Water Resources...............................................................................................................115, 126

Municipal watersheds...........................................................................................7, 30, 53, 124, 127

Noxious weed defined................................................................................................................... 16

Permits and Authorizations........................................................................................................... 35

Physiography................................................................................................................................. 13

Proposed Action ............................................................................................................................ 28

Final Environmental Impact Statement – Invasive Plant Control Project 369
Index

Public Involvement........................................................................................................................ 31

DEIS............................................................................................................................................ 3

methods ..................................................................................................................................3, 31

Purpose and Need...................................................................................................................1, 2, 13

Recreation

developed recreation facilities................................................................................................. 153

dispersed activities .................................................................................................................. 153

effects of action alternatives

Alternative B ....................................................................................................................... 157

Alternative C ....................................................................................................................... 157

Alternative C effectiveness.................................................................................................. 158

Alternative D ....................................................................................................................... 158

effects of no action ...............................................................................................2, 156, 220, 255

Representative watersheds............................................................110, 119, 121, 123, 125, 291, 293

Riparian areas/Bottomlands..............................................................................................14, 67, 110

Short-term uses and long-term productivity................................................................................ 184

Social........................................................................................................................................... 169

communities

rural ..................................................................................................................................... 172

urban.................................................................................................................................... 173

cumulative effects.................................................................................................................... 178

economic efficiency .................................................................................................173, 174, 177

effects of action alternatives.............................................................................................174, 177

environmental justice........................................................................................................... 175

effects of the no action alternative....................................................................................174, 178

land grants............................................................................................................................... 169

local economy.............................................................16, 169, 172, 173, 174, 175, 177, 178, 179

population growth.............................................................................................................170, 173

traditional uses......................................................................................................................... 172

Soil Resources............................................................................................................................. 129

conditions................................................................................................................................ 129

cumulative effects.................................................................................................................... 139

effectiveness of Alternative C ................................................................................................. 138

effects of action alternatives.....................................................................126, 137, 138, 139, 140

herbicides..............................................................................................125, 136, 137, 139, 140

soil erosion ............................................................................................................................ 60

effects of Alternative C ........................................................................................................... 138

effects of herbicides..........................................................................................................138, 139

effects of no action ...........................................................................................................133, 140

erosion ......................................................................................................................................... 8

ground cover.......................................................................8, 60, 71, 76, 111, 114, 126, 127, 138

provinces ................................................................................................................................. 129

revegetation potential .............................................................................8, 30, 130, 137, 138, 139

soil erosion hazard................................................................................................................... 130

soil formation .......................................................................................................................... 130

Specialists Reports ........................................................................................................................ 63

Terrestrial Ecosystem Survey (TES or TEU).....................................................7, 54, 129, 130, 138

Traditional communities.......................................................................................................149, 151

370 Final Environmental Impact Statement – Invasive Plant Control Project
Index

Treatments

biological methods ...................................................................................................1, 29, 76, 161

concerns............................................................................................................................32, 39

effectiveness, on weed species.............................................................................................. 39

controlled grazing.......................................................................................................1, 29, 80, 97

controlled grazing, effectiveness, on weed species................................................................... 39

cultural methods...............................................................................................................1, 29, 40

effectiveness................................................................................................................................ 3

herbicides................................................................................................................................1, 29

concerns................................................................................................................................. 32

risk assessments..................................................................................................................... 34

manual methods....................................................................................................1, 28, 76, 96, 97

mechanical methods.............................................................................................................29, 97

prescribed burning..........................................................................................1, 29, 143, 150, 289

Tribal communities.......................................................................................................149, 150, 151

Unavoidable adverse effects........................................................................................................ 184

Vegetation ..................................................................................................................................... 67

cover types..........................................................................................................67, 68, 70, 77, 79

grasslands .................................................................................................67, 68, 72, 84, 86, 97

mixed conifer............................................................................................67, 70, 72, 85, 90, 91

oak woodlands................................................................................................67, 70, 72, 84, 86

pinyon-juniper ......................................................................................................67, 68, 84, 87

ponderosa pine..............................................................................67, 70, 72, 84, 85, 87, 90, 91

riparian/valley bottoms.......................................................................................................... 70

sagebrush....................................................................................................................67, 72, 84

sagebrush/shrub..................................................................................................................... 68

shrublands.........................................................................................................................67, 68

spurce-fir ..............................................................................................................67, 70, 87, 91

subalpine.....................................................................................................................67, 86, 91

cumulative effects...................................................................................................................... 78

ecological provinces.................................................................................................................. 67

effects of action alternatives.................................................................................................72, 76

Alternative C effectiveness...............................................................................................77, 78

Alternative D effectiveness ................................................................................................... 78

biological............................................................................................................................... 76

herbicides..........................................................................................................................76, 80

special status plants............................................................................................................... 80

traditional use plants.........................................................................................................76, 77

effects of no action ...............................................................................................................70, 71

grasslands .............................................................................................................................. 71

mixed conifer......................................................................................................................... 72

oak woodlands....................................................................................................................... 72

pinyon-juniper ....................................................................................................................... 72

ponderosa pine....................................................................................................................... 72

riparian................................................................................................................................... 72

sagebrush/shrub..................................................................................................................... 71

native ......................................................................................................2, 14, 67, 72, 90, 91, 111

special status plants..............................................................................................................79, 81

Final Environmental Impact Statement – Invasive Plant Control Project 371
Index

Alternative B effects.............................................................................................................. 80

Alternative C effects.............................................................................................................. 81

Alternative D effects.............................................................................................................. 81

effects .................................................................................................................................... 82

Visual Resources......................................................................................................................... 160

effects of action alternatives.................................................................................................... 161

effects of no action .................................................................................................................. 160

Water quality

analysis methods...............................................................................................................108, 119

cumulative effects.................................................................................................................... 127

effects of action alternatives

Alternative C effectiveness.................................................................................................. 127

Alternatives B and D ........................................................................................................... 124

herbicide potential in groundwater...................................................................................... 126

herbicides............................................................................................................................. 125

effects of no action ...........................................................................................................123, 124

Municipal watershed without Forest Plan amendment........................................................ 124

groundwater............................................................................................................................. 123

Headwaters.............................................................................................................................. 119

surface ..................................................................................................................................... 122

uses.......................................................................................................................................... 122

Water Quality

effects of action alternatives

herbicides............................................................................................................................. 126

Weather

precipitation......................................................................................................................122, 129

temperature.............................................................................................................................. 142

Weed

growth predicitons..................................................................................................................... 18

Weed classes

A,B,C defined.......................................................................................................................16, 44

Weed effects

channel stability....................................................................................................................... 122

culturally important plants......................................................................................................... 71

ecological decline ...................................................................................................................... 14

ecosystem diversity ..................................................................................................................... 2

forage......................................................................................................................................... 15

health and safety.......................................................................................................................... 2

Holy Ghost ipomopsis..........................................................................................................15, 79

Local economies........................................................................................................................ 16

monoculture..........................................................................................................................13, 14

native plants..........................................2, 13, 14, 15, 16, 18, 67, 71, 79, 149, 150, 156, 157, 158

native vegetation........................................................................................................................ 15

natural diversity............................................................2, 13, 14, 15, 18, 27, 67, 71, 95, 123, 156

nesting habitat............................................................................................................................ 90

non-commodity uses...........................................................................18, 156, 161, 180, 201, 203

productivity ..................................................................................................................14, 27, 133

quality of wildlife habitat .......................................................................................................... 13

372 Final Environmental Impact Statement – Invasive Plant Control Project
Index

recreation................................................................................................................................... 15

Riparian ..........................................................................................................................67, 70, 71

scenic values...........................................................................................................................2, 15

soil ........................................................................2, 13, 14, 27, 71, 111, 122, 123, 133, 150, 157

soil erosion ...........................................................................................................14, 71, 133, 140

soil holding capacity.................................................................................................................. 14

Soil quality ................................................................................................................................ 14

soil stability ......................................................................................................2, 13, 14, 111, 124

Southwestern willow flycatcher ...........................................................................................14, 90

streams........................................................................................................................14, 122, 123

sustainability.......................................................................................................................13, 179

traditional use plants

chimaja .................................................................................................................................. 16

osha.....................................................................................................................................2, 16

purslane ..............................................................................................................................2, 16

quelites................................................................................................................................... 16

willow.................................................................................................................................2, 16

vegetation .................................................................................................................................. 13

water.............................................................................27, 71, 108, 111, 119, 122, 123, 140, 262

water quality...........................................................................................13, 14, 27, 108, 119, 122

water quantity............................................................................................................................ 15

Wilderness..............................................................................................................2, 15, 156, 157

wildfires................................................................................................................................13, 67

wildlife habitat........................................................................................................................... 15

Weed locations

Jemez Ranger District ............................................................................................................... 64

Jicarilla Ranger District..............................................................................................18, 147, 148

natural gas well heads................................................................................................................ 18

Ponil Fire ..........................................................................................................1, 15, 18, 166, 167

Questa Ranger District .............................................................................................................. 18

Rio Tusas................................................................................................................................... 18

Tres Piedras......................................................................................................3, 18, 64, 201, 205

Valle Vidal .................................................................................................................18, 166, 167

wildfires..................................................................................................................................4, 43

Weed species....................................................................................................................18, 19, 156

African rue................................................................................................................................. 27

Alfombrilla ................................................................................................................................ 27

black henbane.........................................................................................................2, 15, 167, 213

bull thistle.....................................................15, 18, 44, 68, 70, 72, 153, 156, 180, 202, 204, 214

Camelthorn ................................................................................................................................ 27

Canada thistle .............................18, 68, 70, 71, 99, 127, 153, 156, 158, 166, 202, 204, 208, 214

Dalmation Toadflax................................................................................................................. 214

Diffuse knapweed.................................................................................................................... 215

Dyers woad................................................................................................................................ 27

eliminated from project ............................................................................................................. 16

Eurasian watermilfoil ................................................................................................................ 27

field bindweed ........................................................................................................18, 70, 71, 215

halogeton ................................................................................................................................... 27

Final Environmental Impact Statement – Invasive Plant Control Project 373
Index

hoary cress (white top) ...............................................18, 64, 67, 70, 71, 201, 202, 204, 208, 216

hydrilla....................................................................................................................................... 27

jointed goatgrass........................................................................................................................ 27

knapweeds..................................................................................................................18, 127, 180

leafy spurge ......................2, 15, 18, 39, 44, 68, 70, 201, 202, 204, 207, 216, 255, 259, 265, 289

Malta starthistle ......................................................................................................................... 27

musk thistle.........................18, 44, 68, 70, 71, 156, 161, 201, 202, 204, 208, 214, 216, 217, 253

noxious defined ......................................................................................................................... 16

onionweed ................................................................................................................................. 27

perennial pepperweed.....................................................................................18, 68, 71, 204, 217

poison hemlock...............................................................................2, 15, 18, 44, 70, 71, 167, 218

purple loosestrife ....................................................................................................................... 27

Russian knapweed 14, 64, 67, 68, 70, 95, 156, 161, 166, 201, 202, 204, 206, 207, 208, 218, 289

Russian olive ..............2, 3, 14, 16, 18, 45, 64, 67, 70, 71, 72, 124, 127, 203, 206, 207, 218, 219

salt cedar (tamarisk) 2, 3, 14, 18, 39, 45, 64, 67, 70, 71, 72, 77, 90, 97, 108, 111, 124, 127, 156, 

161, 166, 180, 201, 203, 204, 206, 207, 208, 219, 276, 277, 289

Scotch thistle ..........................................................................................................15, 18, 68, 207

Siberian elm........2, 3, 14, 18, 45, 64, 67, 68, 70, 71, 72, 124, 127, 205, 206, 207, 220, 276, 277

spotted knapweed ...............................................................................................................45, 220

teasel.......................................................................................................................................... 27

thistle complexes....................................................................................................................... 18

thistles...................................................................................2, 3, 63, 72, 115, 201, 206, 214, 220

toadflax........................................................................................................................................ 2

toadflaxes............................................................................................................................18, 207

yellow starthistle.......................................................................................................2, 15, 71, 221

yellow toadflax.....................................................................18, 44, 64, 67, 68, 70, 156, 161, 201

Weeds

invasive, non-natives............................................1, 16, 18, 21, 45, 71, 79, 91, 96, 137, 147, 150

policy/direction.......................................................................................................................... 28

Wilderness................................................................................................................................... 156

Wildlife

cumulative effects...................................................................................................................... 99

effects of action alternatives...........................................................................................96, 97, 98

herbicides............................................................................................................................... 98

effects of no action .................................................................................................................2, 95

Management Indicator Species (MIS)....................................................................................... 83

Brewer's sparrow................................................................................................................... 84

effects of action alternatives................................................................................................ 100

hairy woodpecker .................................................................................................................. 85

mourning dove....................................................................................................................... 87

pinyon jay.............................................................................................................................. 86

plain titmouse ........................................................................................................................ 84

red squirrel............................................................................................................................. 85

Rocky Mountain elk .............................................................................................................. 85

Rocky Mountain sheep.......................................................................................................6, 86

neotropical migratory birds....................................................................................................... 93

effects of action alternatives................................................................................................ 104

Threatened, Endangered, and Sensitive animals (TES) .......................................................87, 90

374 Final Environmental Impact Statement – Invasive Plant Control Project
Index

bald eagle............................................................................................................................... 90

black silverspot butterfly ....................................................................................................... 92

boreal owl.............................................................................................................................. 91

effects of action alternatives................................................................................................ 101

goat peak pika........................................................................................................................ 92

interior least tern.................................................................................................................... 91

Jemez Mountain salamander ................................................................................................. 89

Mexican spotted owl.............................................................................................................. 90

New Mexican jumping mouse............................................................................................... 92

northern goshawk .................................................................................................................. 91

Northern leopard frogs .......................................................................................................... 90

peregrine falcon..................................................................................................................... 91

Southwestern river otter ........................................................................................................ 92

Southwestern willow flycatcher ............................................................................................ 90

Swift fox................................................................................................................................ 92

white-tailed ptarmigan......................................................................................................91, 92

yellow-billed cuckoo ............................................................................................................. 92

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