United States 

Department of

Agriculture

Forest 

Service

Southwestern

Region

Environmental 

Assessment for 

Integrated Treatment of 

Noxious or Invasive 

Plants

Tonto National Forest

Gila, Maricopa, Pinal, and Yavapai Counties, Arizona

For Information Contact: Patti Fenner, Noxious Weed Program Manager

Tonto National Forest Supervisor’s Office, 2324 E. McDowell Road,

Phoenix, AZ 85006

602-225-5200

www.fs.fed.us/r3/tonto/

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

activities on the basis of race, color, national origin, age, disability, and where applicable, sex, 

marital status, familial status, parental status, religion, sexual orientation, genetic information, 

political beliefs, reprisal, or because of all or part of an individual’s income is derived from any 

public assistance program. (Not all prohibited bases apply to all programs.) Persons with 

disabilities who require alternative means of communication of program information (Braille, 

large print, audiotape, etc.) should contact USDA’s TARGET Center at (202) 720-2600 (voice and 

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

Independence Avenue, S.W., Washington, DC. 20250-9410, or call (800) 79503272 (voice) or 

(202) 720-6382 (TDD). USDA is an equal opportunity provider and employer. 

Printed on recycled paper – August 2012

Environmental Assessment for Integrated Treatment of Noxious or Invasive Plants, Tonto NF i

Content

Summary ...................................................................................................................................1

Chapter 1 – Purpose and Need .................................................................................................3

Document Structure ..............................................................................................................3

Background ..........................................................................................................................3

Purpose and Need for Action.................................................................................................5

Consistency with Forest Plan Goals and Objectives.............................................................11

Consistency with Laws and Policies....................................................................................12

Proposed Action..................................................................................................................13

Decision Framework...........................................................................................................16

Public Involvement .............................................................................................................16

Issues..................................................................................................................................17

Chapter 2 – Alternatives, Including the Proposed Action......................................................21

Alternatives ........................................................................................................................64

Mitigation Measures Common to the Proposed Action and Alternative 2 .............................65

Chapter 3 – Affected Environment and Environmental Consequences.................................71

Soil Resources ....................................................................................................................72

Water Quality......................................................................................................................77

Ground Water Quality .........................................................................................................79

Vegetation Communities and Fire Regimes .........................................................................84

Invasive Plants....................................................................................................................94

Endangered, Threatened, Candidate and Sensitive Plant Species..........................................98

Range Management .......................................................................................................... 113

Endangered, Threatened, Proposed, Candidate, and Sensitive Wildlife Species.................. 116

Neotropical Migratory Birds .............................................................................................124

Endangered, Threatened, Proposed, Candidate and Sensitive Fish Species.........................131

Social Concerns................................................................................................................142

Heritage Resources ...........................................................................................................152

Chapter 4 - Consultation and Coordination.........................................................................173

Federal and State Officials and Agencies...........................................................................174

Tribes ...............................................................................................................................175

Others...............................................................................................................................175

Chapter 5 – References....................................................................................177

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF iii

List of Tables Page

1. List of Noxious Plant Species for the Tonto National Forest 7

2. Biocontrol agents’ names and target species 56

3. Typical and maximum herbicide and carrier application rates 64

4. Comparison of alternatives 69

5. Soil Properties 73

6. Effects of various weed control methods on soils 74

7. Potential for surface runoff and leaching for proposed herbicides 81

8. Vegetation types present within the Tonto National Forest, and known weeds 85

9. Effects of various weed control methods on vegetation communities 90

10. Known and potential endangered and sensitive plant species on the Tonto NF 99

11. Threatened, endangered, and sensitive animal species on the Tonto NF 116

12. Migratory bird species of concern in the proposed action and two alternatives 126

13. Endangered, threatened, sensitive, and native fishes of the Tonto NF 132

14. Acceptable daily intake (mg/kg/day) for selected herbicides 148

15. Minority population and persons living below poverty level in Tonto NF area 172
iv Environmental Assessment for Integrated Treatment of Noxious or Invasive Plants, Tonto NF

List of Appendices

A. Invasive Plant Descriptions

B. Definitions of Acronyms and Terms Used in this Document

C. U.S.D.A. Forest Service Guide to Noxious Weed Prevention Practices

D. Soil, Water and Air Best Management Practices

E. Herbicide Safety and Spill Plan

F. Herbicide Risk Assessment Locator

G. Herbicide Project Design Features to Mitigate Potential Effects to Federally-listed and 

Sensitive Plant and Animal Species on the Tonto National Forest

H. Standard Consultation Protocol for Noxious Weed Control

I. Cumulative Effects Project List

J. Biological Assessment/Evaluation

K. Management Indicator Species and Migratory Bird Treaty Act Reports

L. Comments received, Summaries & Responses

M. Biological Opinion

N. Maps

Figure 1. Vegetation type map for the Tonto National Forest

Figure 2. Noxious Weed Occurrences on the Cave Creek Ranger District

Figure 3. Noxious Weed Occurrences on the Globe Ranger District

Figure 4. Noxious Weed Occurrences on the Mesa Ranger District

Figure 5. Noxious Weed Occurrences on the Payson Ranger District

Figure 6. Noxious Weed Occurrences on the Pleasant Valley Ranger District

Figure 7. Noxious Weed Occurrences on the Tonto Basin Ranger District

Figure 8. Herbicide Exclusion Area
EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 1

Summary

The Tonto National Forest (Tonto NF) proposes to conduct control treatments for invasive plants 

throughout the area of the National Forest. The project area is located on approximately 

2.9 million acres in central Arizona and is within the Tonto NF. This action is needed, because of 

the occurrence of noxious weeds on and adjacent to the Forest, whose populations are growing 

exponentially, and to meet the requirements of law, regulations, and policy.

The proposed action is to use the approach of Integrated Vegetation Management to manage

invasive plant species on the Tonto NF. The Forest would use the complete range of methods 

associated with integrated vegetation management to eradicate or contain and control populations 

of invasive species. These control methods include manual/mechanical techniques, 

burning/flaming, cultural methods, biological control agents, and herbicides. Monitoring, 

prevention, education, and cooperation with other land managers are also incorporated into this 

proposal.

In addition to the proposed action, the Forest Service also evaluated the following alternatives:

Alternative 1: No Action (continue ongoing treatments). This alternative allows all previous 

decisions regarding treatment of noxious weeds on the Tonto NF to continue. There are:

manual treatments forestwide, torching areas less than ten acres in size adjacent to roads, 

herbicide use in areas allowed by categorical exclusion (administrative & recreation sites), 

treatment of yellow starthistle and diffuse knapweed by prescribed fire and herbicide at the 

Pleasant Valley Ranger Station, continuation of a burn program for Malta starthistle along SR 

188, and use of herbicides along federal and state highways as approved in a decision notice 

dated May 2004 (U.S.F.S.). No new weed treatments are proposed.

Alternative 2: Integrated Vegetation Management Excluding the Use of Herbicides. This 

alternative provides for use of mechanical, manual, prescribed burning/flaming, cultural and 

biological control agents to manage existing invasive plant populations and to control new 

infestations, as they occur.

Based upon the effects of the alternatives, the responsible official will decide 

• Whether the proposed action would result in significant environmental effects that would 

require the preparation of an Environmental Impact Statement, or if there is a finding of 

no significant impact.

• If significant impacts are not anticipated, the Forest Supervisor will determine whether 

the proposed action will proceed as described above, as modified by an alternative, or not 

at all.

• Mitigation measures and monitoring requirements to be implemented by the Forest 

Service.

• If the project requires a Forest Plan amendment.

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 3

Chapter 1 – Purpose and Need

Document Structure

The Forest Service has prepared this Environmental Assessment in compliance with the National 

Environmental Policy Act (NEPA) and other relevant federal and state laws and regulations. This 

Environmental Assessment discloses the direct, indirect, and cumulative environmental impacts 

that would result from the proposed action and alternatives. The document is organized into four 

parts:

Introduction: The section includes information on the history of the project proposal, the 

purpose of and need for the project, and the agency’s proposal for achieving that purpose 

and need. This section also details how the Forest Service has informed the public of the 

proposal and how the public responded. 

Alternatives, including the Proposed Action: This section provides a more detailed 

description of the agency’s proposed action, as well as alternative methods for achieving 

the stated purpose. These alternatives were developed based on significant issues raised 

by the public and other agencies. This discussion also includes possible mitigation 

measures. Finally, this section provides a summary table of the environmental 

consequences associated with each alternative. 

Environmental Consequences: This section describes the environmental effects of 

implementing the proposed action and other alternatives. This analysis is organized by 

resource area. Within each section, the affected environment is described first, followed 

by the effects of the No Action Alternative that provides a baseline for evaluation and 

comparison of the other alternatives that follow. 

Agencies and Persons Consulted: This section provides a list of preparers and agencies 

consulted during development of the environmental assessment. 

Appendices: The appendices provide more detailed information to support the analyses 

presented in the environmental assessment.

Additional documentation, including more detailed analyses of project-area resources, may be 

found in the project planning record located at the Tonto NF Supervisor’s Office in Phoenix, 

Arizona.

Background

The National Invasive Species Council defines “invasive species” as a species that is 1) nonnative 

(or alien) to the ecosystem under consideration and 2) whose introduction causes or is likely to 

cause economic or environmental harm or harm to human health (Executive Order 13112). A 

native species is a species that (other than one established as a result of an introduction)

historically occurred or currently occurs in an ecosystem (Federal Register, 1999).

Arizona Administrative Codes R3-4-244 & R3-4-245 (Arizona Dept. of Agriculture, 2006) 

regulate certain invasive species in the state: “A noxious weed is defined as any species of plant 

that is detrimental or destructive and difficult to control or eradicate and includes plant organisms 

found injurious to any domesticated, cultivated, native or wild plant.” The former director of 

Arizona’s noxious weed program uses five categories to describe noxious weeds: 1) exotic, 2) 

invasive, 3) competitive, 4) persistent, and 5) aggressive (Northam, 2004).

Invasive weeds were first noticed on the Tonto NF in the mid-to-late 1980s with the discovery of 

yellow starthistle on private land in the community of Young by Francis Cline. Mr. Cline, family 
Chapter 1 – Purpose and Need

4 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

members, and others in the community formed the Tonto Weed Management Area. They have 

enlisted the help of various agencies and organizations as cooperators to provide resources for 

control of weed infestations that have appeared in Pleasant Valley and Gila County. 

Invasive plant control projects on the Tonto NF up to the present time have involved only very 

limited manual grubbing projects and application of herbicides along state and federal highway 

rights-of-way by the Arizona Department of Transportation, until 2003. In the summer of 2003, a 

Noxious Weed Program Manager was hired by the Tonto National Forest. The first large-scale 

project by the Tonto NF was a prescribed burn of Malta starthistle along State Highway 188. This 

infestation was possibly introduced in the mid-1980s, and had already spread significantly 

beyond the right-of-way in 2003. Projects since that time have included a follow-up to this burn, 

additional prescribed burns, weed control projects in Forest campgrounds, use of herbicides along 

federal and state highway rights-of-way, and manual grubbing of weeds in many locations

throughout the Tonto NF. Funding levels have been low and are not expected to increase in the 

near future, despite noxious weeds being one of the four major threats to National Grasslands and 

Forests recognized nationally by the Chief of the Forest Service. The Forest depends upon special 

funding sources and grants to accomplish weed control projects. Volunteers are an important part 

of the Tonto NF’s invasive plant control program.

Control projects of the scale and type conducted by the Tonto NF have not been adequate to 

prevent weed infestations from increasing. The wet winter and spring of 2004 to 2005 resulted in 

a population explosion of Malta starthistle, Saharan mustard, and red brome at lower elevations; 

and yellow starthistle, bull thistle, and diffuse knapweed on the higher elevation ranger districts.

Some wildfires have allowed the invasion of bull thistle (Rodeo-Chediski Fire of 2002), Siberian 

elm, tree of heaven, and Jerusalem thorn (Cave Creek Complex Fire of 2005), Malta starthistle

(Edge Fire of 2005), and black mustard (Willow Fire of 2004).

The Tonto NF has not been intensively surveyed for noxious weeds. Populations of some noxious 

weeds have been known for nearly 30 years and have spread considerably, since they were first 

identified. Others are still being found in small infestations. Opportunities such as funding from 

post-wildfire, long-term rehabilitation projects have been used to complete more extensive 

surveys and control new infestations. Both long-term and Burned Area Emergency Rehabilitation 

(BAER) funds have been used to conduct weed surveys in the areas of the Rodeo-Chediski, 

Picture, Willow, Diamond, Webber, Edge, and Cave Creek fires. ADOT funding has been used to 

conduct surveys along state and federal highways in preparation for highway reconstruction or 

maintenance projects.

Much of the Tonto NF’s efforts in the weed management program have been directed toward 

education and awareness of Forest Service employees, regional Incident Management Teams, 

special interest groups, and the public. The emphasis of these presentations has been prevention 

of weed spread and identification of invasive and noxious weeds on the Forest. The Forest is 

developing relationships with surrounding land managers and other agencies and organizations

that operate within the boundaries of the National Forest to work cooperatively on weed control 

strategies and projects. 

The Tonto NF works cooperatively with two Weed Management Areas on projects within and 

near the National Forest: the Tonto Weed Management Area, based in Young, Arizona, whose 

boundaries are defined by the Tonto Natural Resource Conservation District (NRCD); and the 

Central Arizona Weed Management Area, which encompasses all of Maricopa and some of Pinal 
Chapter 1 – Purpose and Need

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 5

County. In 2004, the Tonto NF assisted in writing a grant for the Tonto Weed Management Area 

to receive an $85,000 Resource Advisory Committee grant to map weeds in Gila County. 

Activities with the Central Arizona Weed Management Area have included field trips, information 

sharing, public education, work on an invasive plant curriculum for elementary schools in central 

Arizona, and contribution of in-kind labor for start-up grants.

The Tonto NF has a close working relationship with the Arizona Department of Transportation 

(ADOT). Forest staff works together with ADOT and communicates regularly on routine roadside 

vegetation maintenance. In 2007, the Tonto NF, ADOT, and the Federal Highway Administration

(FHWA) included noxious weed control specifications in two new highway construction 

contracts, which was a completely new concept according to Bonnie Harper Lore, former

Restoration Ecologist for FHWA (Brady, 2007). Since 2007, noxious weed prevention and control 

clauses have become regular specifications in highway construction contracts that take place 

within the boundary of the Tonto NF.

Purpose and Need for Action

The purpose of the proposed action is to contain, control, or eliminate populations of noxious 

weeds and invasive plants occurring on the Tonto NF and to prevent new infestations from 

becoming established. A list of invasive species to be addressed by this action is included as 

table 1. This action is needed because populations of noxious weeds are growing rapidly on and 

adjacent to the Forest and the requirements of law, regulations, and policy for noxious weeds 

need to be met.

Existing Conditions

Invasive plants can have detrimental effects on the environment and particularly on other species. 

While most infestations on the Tonto NF are at low population levels now, in a short time they 

can grow beyond any control efforts, as evidenced repeatedly in many other places. For example, 

spotted knapweed was introduced into Montana in the 1920s – today it occupies over 7.2 million 

acres in nine states and two Canadian provinces (Beck, 1994). Bunchgrass sites invaded by 

spotted knapweed exhibit increases in soil erosion of 192 percent and higher (Lacey, et al., 1990). 

Invasive exotic species often replace preferred wildlife forage species, forming monocultures 

inhospitable to native wildlife. Plants such as Dalmatian toadflax, Scotch and bull thistles, and 

oxeye daisy are not typically used by any native wildlife species. These invasive plants replace 

native grasses and forbs, which are used by deer, turkey, elk, and many other native wildlife

species. Leafy spurge produces a sap that causes a severe skin rash in humans and is poisonous to 

most grazing animals. Adverse effects of these and other invasive species are described later in 

this document. Control of these plants promotes ecosystem health of forest, range, and aquatic 

habitat by maintaining or improving cover of native forbs, grass, and woody species. This, in 

turn, will prevent loss of wildlife habitat and species diversity. 

Several decades ago very few acres on the Tonto NF were infested by invasive plants; however, 

several invasive plant species have increased dramatically in abundance on the Forest and in 

surrounding areas over the last several years. About twenty years ago, yellow starthistle and 

diffuse knapweed were discovered on private land in the town of Young (Cline, 2004). Today,

there are an estimated 5,000 acres of yellow starthistle in Gila County alone. Thirty years ago, 

there was no Malta starthistle growing along Highway 188. Today, rights-of-way along more than 

25 miles of this highway are covered with this plant, and the infestation extends for 
Chapter 1 – Purpose and Need

6 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

approximately 38,000 acres in Tonto Basin on both sides of Roosevelt Lake. Smaller infestations 

are being found regularly on all lower elevation ranger districts. Malta starthistle has been 

identified growing throughout the Phoenix, Scottsdale, Cave Creek/Carefree, Tempe, Gisela, 

Superior, Apache Junction, Mesa, and Punkin Center, mainly in small localized infestations of 

less than an acre. Fountain grass has been used for ornamental plantings in the greater Phoenix 

metropolitan area, and has naturalized along highways throughout most of the lower elevation 

Districts of the Forest. Buffelgrass is aggressively invading from southern Arizona.

While most infestations of invasive plants on the Tonto NF are currently at relatively low 

population levels, they have the potential to increase beyond any reasonable efforts to control 

them, as evidenced repeatedly in many other places. For example, spotted knapweed was first 

introduced into Montana in the 1920s; but today it occupies over 7.2 million acres in nine states 

and two Canadian provinces (Beck, 1994). Although there are fewer acres of weeds on the 

Tonto NF as compared to many other western forests, weed populations are growing rapidly here. 

History has repeatedly demonstrated that most invasive weed populations do not remain small for 

long. Growth rates can be exponential with an apparent lag time between initial infestation and 

subsequent extensive infestations that are beyond control.

Desired Conditions

The following paragraph describes the desired condition for the Forest at the end of the ten-year 

term of the program:

Existing infestations of invasive exotic plants will be eradicated or controlled through a 

coordinated forestwide approach to Integrated Vegetation Management. New populations are 

detected and treated as they become established. A forestwide approach is effective in controlling 

the spread of noxious weeds and invasive exotic plants, and is coordinated with the efforts of 

municipal, county, state and federal agencies, and weed management areas. Treatment plans take 

into account the latest guidance regarding the protection of public health and ecosystem health, as 

well as the protection and recovery of federally-listed wildlife and plant species. 

Noxious and Invasive Plant Species

Plant species that are invasive on the Tonto NF or those invasive species that grow nearby and are 

likely to infest the Forest over the next ten years are listed in table 1. This list should probably be 

expected to expand in upcoming years.

Nomenclature for these plant species follows Natural Resource Conservation Service, Plants 

National Database at http://plants.usda.gov, with the exception of sweet resinbush, nomenclature 

by Dr. Bertil Nordenstam of Sweden (Nordenstam, 1968; Global Compendium of Weeds, 2007).

For definitions of weed categories, refer to the explanation in the caption of table 1. A specific 

category, the Tonto category, has been included to describe management of invasive weeds that 

are common to the Tonto NF.

Descriptions, origins, locations in Arizona and adverse effects of each species are included in 

chapter 3.
Chapter 1 – Purpose and Need

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 7

Table 1. List of Noxious Plant Species for the Tonto NF

Latin name Common name

AZ Dept. of 

Agriculture 

Weed List*

Animal & 

Plant Health 

Inspection 

Service 

(APHIS) Weed 

List

On neighboring 

states’ weed lists?

Tonto NF 

category**

AZWIPWG 

class ***

Acres on 

the Tonto

NF

Acroptilon repens Russian knapweed P, Res. CA, CO, NM, 

NV,UT A H 2

Aegilops cylindrica Jointed goatgrass P, Res. CA, CO, NM B L 10

Ailanthus altissima Tree of heaven B 100

Alhagi maurorum Camelthorn P, Res. CA, CO, NM, NV, A M 1

Arundo donax Giant reed B H 100

Asphodelus fistulosus Onionweed X NM A L 0

Avena fatua Wild oats CO C M 20,000

Brassica nigra Black mustard B 75

Brassica tournefortii Asian mustard C M  3,000

Bromus catharticus Rescuegrass C 200

Bromus diandrus Ripgut brome C M 5,000

Bromus japonicus Japanese brome C 3,000

Bromus rubens Red brome C H 150,000

Bromus tectorum Downy brome CO C H 100,000

Cardaria draba Globe-podded hoary 

cress P, Res. CA, CO, NM, NV UT A M 0

Cardaria pubescens Hairy white-top P CA, A M 0

Carduus acanthoides Plumeless thistle P CA, CO A 0

Carduus nutans Musk thistle CA, CO, NM, NV, 

UT A M 10
Chapter 1 – Purpose and Need

8 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Cenchrus echinatus Southern sandbur P, Reg. CA, A 0

Cenchrus spinifex Field sandbur P, Reg. CA, A 7

Centaurea 

biebersteinii Spotted knapweed P, Res. CA, CO, NM, NV, UT A M  5

Centaurea diffusa Diffuse knapweed P, Res. CA, NM, NV, UT B M 250

Centaurea melitensis Malta starthistle NM, NV C M 65,000

Centaurea solstitialis Yellow starthistle P, Res. CA, CO, NM, NV, 

UT B H 8000

Ceratocephala 

testiculata Curveseed butterwort A 5

Chondrilla juncea Rush skeletonweed P CA, CO, NV A M 0

Chorispora tenella Blue mustard CA, CO A 250

Cirsium arvense Canada thistle P CA, CO, NM, NV, 

UT A M 8

Cirsium vulgare Bull thistle CO, NM C 20,000

Convolvulus arvensis Field bindweed P, Reg. CA, CO, NM, UT C M 3,000

Dimorphotheca 

cuneata White bietou A 40

Dipsacus fullonum Common teasel CO, NM B 15

Elaeagnus 

angustifolia Russian olive CO, NM A H 2

Elymus repens Quackgrass P, Res. CA, CO, UT B L 5

Eragrostis curvula Weeping lovegrass C L  40,000

Eragrostis 

Lehmanniana Lehmann’s lovegrass C H 50,000

Erysimum repandum Spreading wallflower A 2,000

Euphorbia esula Leafy spurge P CA, CO, NM, NV, 

UT A H 0
Chapter 1 – Purpose and Need

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 9

Euryops subcarnosus Sweet resinbush A H  27

Isatis tinctoria Dyer’s woad P CA, CO, NM, NV, 

UT A 0

Kochia scoparia Kochia A 0

Leucanthemum 

vulgare Oxeye daisy CO A L 3

Linaria dalmatica Dalmatian toadflax P, Res. CA, CO, NM, NV A M  35

Linaria vulgaris Yellow toadflax CO, NM, NV A M 0

Lythrum salicaria Purple loosestrife P CA, CO, NM, NV, 

UT A 0

Melilotus officinalis Yellow sweetclover C M 10,000

Nerium oleander Oleander B 40

Oncosiphon 

piluliferum Globe chamomile B 5

Onopordum 

acanthium Scotch thistle P, Res. CA, CO, NM, NV, UT B L 50

Parkinsonia aculeata Jerusalem thorn A 30

Peganum harmala African rue P CA, CO, NM, NV A 0

Pennisetum ciliare Buffelgrass P, Reg. B H  6,000

Pennisetum setaceum Fountain grass B H  7,000

Pentzia incana Karoo bush A 3

Polygonum 

cuspidatum Japanese knotweed CA, A 0

Potentilla recta Sulfur cinquefoil CO, NV A 0

Pyracantha sp. Pyracantha B

Rhus lancea African sumac B M
Chapter 1 – Purpose and Need

10 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Definitions: *Arizona State Dept. of Agriculture Weed List: P= Prohibited. These weeds are prohibited from entry into the state.

Reg. = Regulated. These weeds may be controlled or quarantined if found within the state, to prevent further infestation. 

Res. = Restricted. These weeds shall be controlled or quarantined if found within the state. 

**Tonto Weed List: Class A weeds are of limited distribution in Arizona, or unrecorded in the state. They pose a serious threat. Management goal is 

eradication. Class B weeds are of limited distribution in Arizona, common in some places in the state. Management goal is to contain their spread, 

decrease population size, then eliminate. Class C weeds have spread beyond our capability to eradicate them. Management goal is to contain spread to 

present size, then decrease the population, if possible. 

***AZ-WIPWG = Arizona Wildland Invasive Plant Working Group rating. (SWEPIC 2005) H = High. These species have severe ecological 

impacts on ecosystems; invasiveness attributes are conducive to moderate to high rates of dispersal and establishment; species are usually widely 

distributed. M = Medium. These species have substantial and apparent ecological impacts on ecosystems; invasiveness attributes are conducive to 

moderate to high rates of dispersal, often enhanced by disturbance; ecological amplitude and distribution range from limited to widespread. L = Low. 

These species have minor yet detectable ecological impacts; invasiveness attributes result in low to moderate rates of invasion; ecological amplitude and 

distribution are generally limited, but the species can be problematic locally.

= Additional designation for some species whose current ecological amplitude and distribution are limited. Species are capable of invading 

unexploited natural communities, based on initial, localized observations or behavior in similar ecosystems/communities elsewhere. 

Salsola kali & S. 

tragus Russian thistle C

Salvia aethiopis Mediterranean sage CA, CO, NV A

Schismus arabicus Arabian schismus C M

Schismus barbatus Mediterranean grass C M

Sinapis arvensis Wild mustard CO B

Tamarix chinensis Five-stamen tamarisk NM C H 

Tamarix parviflora Smallflower tamarisk CO, NM, NV C H 

Tamarix ramosissima Saltcedar CO, NM, NV C H 

Ulmus pumila Siberian elm NM A M

Vinca major Periwinkle B M
Chapter 1 – Purpose and Need

11 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Consistency with Forest Plan Goals and Objectives

The Tonto Land and Resource Management Plan (U.S.F.S., 1985b) was written prior to an 

awareness of the issue of noxious weeds on the Forest. Consequently, there is no language in the 

document that specifically addresses management of noxious weeds and other invasive exotic 

plants. There are, however, broad goals and objectives that directly and indirectly provide a basis 

for development of this project. This action responds to the following goals and objectives 

outlined in the Tonto NF Plan:

Hazard Protection: “Through integrated pest management, manage resources to prevent or 

reduce serious, long lasting hazards.”

Noxious weed infestations can be a hazard to human and animal health. Some species increase 

fire occurrence in ecosystems that are otherwise unadapted to frequent fires thereby subjecting 

forest users in desert areas and residents who live nearby to increased hazard from wildfires. 

Other weeds, such as Russian knapweed and yellow and Malta starthistles, are toxic to horses.

Visual and recreation resource: “Maintain and enhance visual resource values by 

increasing opportunities for a variety of developed and dispersed experiences. Emphasize 

visual quality objectives in all resource planning and management activities.”

Noxious weed infestations detract from visual quality of the landscape by turning diverse and 

interesting landscapes into monocultures of often spiny or poisonous plants. Noxious weeds can 

out-compete native wildflowers thereby eliminating photographic and viewing opportunities. 

Plants such as Malta starthistle can form dense groundcovers in recreation sites, rendering those 

sites inhospitable for camping and picnicking. 

Wildlife habitat: “All resource planning and management activities will be coordinated to 

provide for species diversity and greater wildlife and fish populations through improvement 

of habitat. Ensure that fish and wildlife habitats are managed to maintain viable 

populations of existing native vertebrate species.”

Uncontrolled infestation by noxious weeds reduces biodiversity, displaces plants that are used by 

wildlife for forage and cover, and ultimately causes deterioration of wildlife habitat.

Threatened & endangered species recovery: “Prevent destruction or adverse modification 

of critical habitats for Threatened and Endangered species and manage for a goal of 

increasing population levels that will remove them from federal lists.”

Noxious weeds can devastate riparian and aquatic habitat for federally-listed fish and amphibians 

by increasing water runoff and soil erosion, inducing higher sediment loads in streams, rivers, and 

lakes. Upland species can be affected by changes in fire regime or other ecosystem function 

induced by noxious weeds. 

Restore rangeland: “The goal of the Forest range management program is to bring the 

permitted grazing use in balance with the forage allocated for use by domestic livestock, 

and to have all allotments under appropriate levels of management during the third time 

period (2005 to 2015).
Chapter 1 – Purpose and Need

12 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Improve range forage, watershed & wildlife habitat conditions.”

Noxious weeds out-compete native plants and reduce the amount of forage available to grazing 

livestock. In addition, some noxious weed species contain toxins that can cause death or injury in

grazing animals.

Erosion control, water quality & quantity: “Meet minimum air and water quality 

standards, emphasize improvement of soil productivity, air & water quality, augment water 

supplies when compatible with other resources, and enhance riparian ecosystems.”

Soil stability and watershed values suffer when native plants that have fibrous root systems are 

replaced by noxious weeds with deep tap roots.

Wilderness: “Emphasize a wilderness management program which is interdisciplinary in 

approach, and which is directed towards achieving the intent of the Wilderness Act of 1964

and FSH 2320.”

When noxious weeds invade wilderness areas, they destroy the quality described in the 

Wilderness Act as “untrammeled by man.” Congress also directed that wilderness areas be 

managed in such manner as will leave them “unimpaired for future use.”

Consistency with Laws and Policies

Federal laws and policies have required resource management to prevent degradation of the land 

since the Forest Service was formed. As noxious weeds have become more of an issue 

nationwide, laws and regulations have become more specific to this emerging problem. Listed 

below are the most recent laws, regulations, and policies related to weed management. 

The Forest Service is directed by the Federal Land Policy and Management Act of 1976 to “take 

any action necessary to prevent unnecessary or undue degradation of the [public] lands. (43 USC

1732, Section 302b). Regulations for implementing the National Forest Management Act of 1976

(36 CFR Part 219.27 a.3) provide direction for controlling noxious weeds.

36 CFR 222.8 states that Forest officers “shall cooperate fully with state, county, and federal 

officials in application and enforcement of all laws and regulations relating to ... noxious farm 

weeds.” 

The Public Rangelands Improvement Act of 1978 established a national policy and commitment 

to “manage, maintain, and improve the condition of public rangelands” (43 USC 1711, Section 

2(b)(2).

The Federal Noxious Weed Act of 1974 was updated in 1990 with the passage of the Food, 

Agriculture Conservation and Trade Act, commonly known as the Farm Bill. This Bill directed 

federal agencies to coordinate with state and local governments to contain and control undesirable 

plant species by entering into Memoranda of Understanding and other agreements where 

appropriate. The Farm Bill also directed federal agencies to develop policy direction; Forest 

Service Manual 2080 was issued in November of 1995.
Chapter 1 – Purpose and Need

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 13

In 1998, the Forest Service issued a National Strategy for weed management entitled “Stemming 

the Invasive Tide: Forest Service Strategy for Noxious and Nonnative Invasive Plant 

Management” (U.S. Forest Service, 1998).

In February 1999, President Clinton signed Executive Order 13112, addressing invasive species. 

This order directs federal agencies to prevent introduction and spread of invasive species, to 

cooperate with a newly created Invasive Species Council, and to produce and follow direction

given in an Invasive Species Management Plan. Federal agencies are directed to conduct 

programs to detect and respond rapidly to and control populations of invasive species in a costeffective and environmentally sound manner. Further, agencies are to monitor invasive species, 

restore native plant communities, and promote public education regarding invasive species

(Federal Regulation, 1999).

The Federal Plant Protection Act and implementing regulations and policies, require the Forest 

Service to cooperate with state, county, and other federal agencies in the application and 

enforcement of all laws and regulations relating to management and control of noxious weeds. 

Forest Service policy in FSM 2259.03 states: “Forest officers should place noxious weed 

management emphasis on those areas where cooperative efforts are underway, such as organized 

weed control districts. Within budgetary constraints, the Forest Service shall control, to the extent 

practical, noxious farm weeds on all National Forest System lands. Efforts should be directed to 

those infestations where management actions will be the most effective in preventing or reducing 

the spread of noxious weeds considered to be the greatest threat to economic, environmental, 

social and other values.

The Wilderness Act (Public Law 88-577) mandates that wilderness be managed so its community 

of life is untrammeled by man, its primeval character is retained and its natural conditions are 

preserved. Forest Service policy direction is to maintain wilderness in such a manner that 

ecosystems are unaffected by human manipulation and influences so that plants and animals 

develop and respond to natural forces (FSM 2320.2). The Wilderness Act and its implementing 

regulations (36 CFR 293) do not preclude the use of herbicides in wilderness to maintain the 

natural ecosystem, and the Manual anticipates such use by establishing approval standards at 

FSM 2323.04c. In order to preserve natural conditions and processes in wilderness, it may 

become necessary to remove invasive exotic vegetation. Herbicides are a potential tool for 

controlling invasive species and may represent the appropriate “minimum tool” for

accomplishing this objective.

Federal Clean Water Act, including the National Pollutant Discharge Elimination System

permitting program and its implementing regulations by Arizona Department of Environmental 

Quality. The requirement to obtain NPDES permits for point source discharges from pesticide 

applications to waters of the U.S. stems from a recent decision by the Sixth Circuit Court of 

Appeals, whose mandate goes into effect February 2012.

The proposed action is responsive to these laws and policies. Lack of action against invasive plant 

species is clearly a violation of these laws and policies.

Proposed Action

The Forest Service proposes eradication, containment, and/or control of noxious weed and 

invasive plant species on parts of the Cave Creek, Globe, Mesa, Payson, Pleasant Valley, and 
Chapter 1 – Purpose and Need

14 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Tonto Basin ranger districts. The Tonto NF is located within Gila, Maricopa, Pinal, and Yavapai 

counties, and comprises a total of 2,872,876 acres. Known noxious weed infestations cover only a 

small percentage of the total National Forest acres, but unknown infestations may be found 

anywhere within the nearly three million acres of the Forest. 

Proposed noxious weed treatment measures in this Environmental Assessment are contained in 

the Forest Service’s broad strategy of Integrated Vegetation Management (IVM) (FSM 2080.2), 

which is composed of five elements: prevention and detection, treatment of existing populations, 

monitoring, restoration, and coordination with the public and other management entities. Noxious 

weed treatment methods in this Integrated Vegetation Management approach include: manual, 

mechanical, prescribed burning, cultural, use of biological control agents, and use of herbicides.

Adaptive Management Strategy

Weed infestations are dynamic; even the most complete inventory can never cover all infested 

areas and will quickly be out of date. During the life of this project, invasive plants are likely to 

be introduced to new locations by vehicles, heavy equipment, livestock, wildlife, recreationists, 

and other vectors of spread. It is also likely that additional species of invasive plants not 

identified in table 1 may be discovered on the Forest over the term of the project. Therefore, an 

adaptive management strategy will be used in the proposed invasive plant management program

to provide direction for noxious weed management activities on the Forest. An adaptive 

management strategy allows decision makers to take advantage of new information, as it becomes 

available for improvement of planning and management. The Forest will respond to new 

infestations of invasive weeds by completing site-specific reviews to determine impacts to

proposed, threatened, endangered and sensitive plants, wildlife and fish, as well as the public, 

heritage resources, or plant species of significance to local tribes. New populations of invasive 

plants will be treated as they are found as long as the conditions of this analysis and decision are 

met. Likewise, if a new or improved treatment product is available, the new product may be 

considered for use. Analyses will be done to determine if the effects of new treatments are similar 

to effects disclosed herein. As long as the new treatment activity fits within the range of effects 

analyzed and disclosed in this EA, no further NEPA analysis will be performed. If monitoring 

determines that control beyond the scope of this analysis becomes necessary, further analysis 

under NEPA will be conducted. 

Project Monitoring

Monitoring is the process of collecting information to determine the effectiveness of management 

actions in meeting prescribed objectives. Weed management monitoring on the Tonto NF focuses 

on the density and rate of spread of invasive exotic plant species and the effects these aggressive 

plants have on natural resources. Also of interest is effectiveness of prescribed actions on the 

target plant and responses of desirable vegetation. Monitoring will help determine if our 

prescriptions and activities are accomplishing the goals established for each species (see table 1, 

Tonto NF category column).
Chapter 1 – Purpose and Need

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 15

There will be three types of monitoring, described below:

Implementation Monitoring

Annual monitoring will be conducted by staff on the Tonto NF to verify that actions are taking 

place as described in this environmental document. Monitoring results will be input to the Forest 

Service’s corporate database “FACTS” (Forest Service ACtivity Tracking System) which serves 

as the database of record for Forest Service invasive plant control activities. Monitoring will 

include target species, treatment type, location, acres, timing of actions, and mitigation.

Monitoring will occur prior to and during each prescribed fire and herbicide project, and will 

include weather information and site conditions. 

Monitoring reports will be part of all contracts, and contractors shall be required to report on such 

items as: method used, name and amount of herbicide used, dates sprayed, and situation and 

weather conditions during herbicide application. This information will be included in the Forest’s 

annual reporting in the FACTS database.

Project Effectiveness Monitoring

Monitoring of weed spread and/or suppression will be aided by analysis of an existing Forest 

Service database and GIS layer called National Resource Information System (NRIS) Terra 

Invasives. Before treating any population, the perimeter of the affected area will be mapped and 

infested acres will be calculated. This baseline measurement will be used to document the 

effectiveness of each type of treatment by comparing infested acreages in successive years.

Yearly treatment summaries will be used to assess weed spread. By tracking infested areas, we 

will be able to gauge if our objectives are being met by each treatment.

Mitigation measures for notification of the public and signing of herbicide-treated sites will be 

monitored by periodically contacting individuals or groups concerned with Multiple Chemical 

Sensitivity, those who have submitted comments on this proposal regarding MCS concerns, tribal 

representatives, and others who have expressed concern, to verify the notification program is 

working. 

Monitoring techniques for success of biocontrol agents will be developed with qualified 

professionals from U.S.D.A., Animal and Plant Health Inspection Service (APHIS). Monitoring 

will determine insect establishment success, insect population trends, insect impact on target 

plants, and effects of these biocontrol agents on weed population and density.

Environmental Effects Monitoring

Effects on human health resulting from exposure to daily treatment operations, accidents, and 

long-term exposure will be monitored through documentation of project records, including 

worker and public health complaints. Risk to human health regarding use of herbicides has been 

evaluated in chapter 3 and in Risk Assessments listed in appendix F.

Effects on public access and plant collection will be assessed to determine if design features, best

management practices, and mitigation measures outlined in chapter 3 and Appendices C, D, G, 

and H are working and effective. 

Potential non-target or offsite effects, such as those that may occur from a prescribed fire 

expanding beyond the treatment area, leaching, runoff, or aerial drift in the case of herbicide 
Chapter 1 – Purpose and Need

16 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

treatments, will be analyzed prior to treatment. Best management practices (appendix D) will be 

applied to minimize predicted undesirable environmental effects. Projects will be monitored after 

completion for this type of unintended effect.

Monitoring will be used to determine if biocontrol agents are adversely impacting native plants 

and if biocontrol agents are able to survive and successfully reproduce under the environmental 

conditions of the project area. 

Decision Framework

The Forest Supervisor of the Tonto NF will review the proposed action and alternatives in order 

to make the following decisions:

• Whether the proposed action would result in significant environmental effects that would 

require the preparation of an Environmental Impact Statement or there is a finding of no 

significant impact.

• If significant impacts are not anticipated, the Forest Supervisor will determine whether 

the proposed action will proceed as described above, as modified by an alternative, or not 

at all.

• Mitigation measures and monitoring requirements that will be implemented by the Forest 

Service.

• If the project requires a Forest Plan amendment.

The Environmental Assessment (EA) is not a decision document. The EA displays the results of 

an analysis of the proposed action and alternatives with respect to the key issues as well as the 

ability of those actions to meet the purpose and need. A Decision Notice signed by the Tonto NF

Supervisor will document the decision and rationale for selection.

Public Involvement

The proposal has been listed in the Schedule of Proposed Actions (SOPA) since fall of 2001. 

The proposal was first provided to the public and other agencies for comment in a scoping letter 

on November 26, 2001 (Doc # 1 in project record). Comments from this original scoping were 

retained and included in the current analysis. They were also used to revise the proposed action 

and description of existing conditions. A revised public scoping letter was mailed to 858

individuals, organizations and agencies, and also to legislative representatives on May 25, 2004 

(Doc # 5 in project record). A total of 16 comments were received from scoping in 2001 and 

2004.

Talks have been given to various groups regarding the Tonto NF’s proposal to use integrated 

vegetation management, including the Arizona Native Plant Society, Association of Four-WheelDrive Clubs, Arizona State Horseman’s Association, Superstition Horseman’s Association, Cave 

Creek Saddle Club, Trout Unlimited, Arizona Flycasters, Scottsdale Sportsman’s Club, Arizona 

State University Wildlife Habitat and Ecological Restoration Club, Tonto Weed Management 

Area, Cave Creek Town Council, officials of the Town of Payson, the town of Star Valley, and 

the Gila County Board of Supervisors. The Tonto NF’s Noxious Weed Program Manager also 

participates in meetings of Southwest Vegetation Management Association, Central Arizona 

Weed Management Area, Tonto Natural Resource Conservation District, the Southern Arizona 
Chapter 1 – Purpose and Need

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 17

Buffelgrass Coordination Center, and the Southeastern Arizona Weed Management Area 

(formerly known as the Sweet Resinbush/Pentzia Weed Management Group).

On October 3, 2005, a letter was mailed to the Tonto NF’s tribal mailing list, requesting their 

input in identifying plant species having traditional cultural or religious significance, and/or areas 

being used by tribal members for plant harvesting or collecting, or which would have other 

significance that would merit special consideration during project design and implementation. 

Three tribes responded: Fort McDowell Yavapai Nation, Yavapai-Prescott Indian Tribe, and 

White Mountain Apache Tribe. Fort McDowell Yavapai Nation stated that they supported the 

project providing there were no impacts to acorns and piñyon in the Forest. The Yavapai-Prescott 

Tribe was also supportive of the project, and requested more information on invasive plants and 

their locations. They are providing the Tonto NF a list of plants that are important to them for 

cultural purposes. The White Mountain Apache Tribe replied that the project posed no threat to 

their traditional cultural properties and/or religious sites. If a historical Apache site is located 

when planning a project, the project should cease until the proper authorities are notified.

In order to fully describe the proposed project and solicit input, we met with tribal members from 

the tribes’ cultural resources offices on the following dates:

• March 1, 2006 – Yavapai-Prescott Indian Tribe

• June 21, 2006 – Four southern tribes: Tohono O’odham Nation, Salt River PimaMaricopa Indian Community, Gila River Indian Community, and Ak-Chin Indian 

Community

• July 19, 2006 – Hopi Tribe

Using the comments from the public, other agencies, and tribes (see Issues section), the 

interdisciplinary team developed a list of issues to address.

Issues

All comments received were reviewed by the ID Team to develop a list of issues to address for 

this proposed project. The Team separated the issues into two groups: significant and nonsignificant. Significant issues were defined as those directly or indirectly caused by implementing 

the proposed action. Non-significant issues were identified as those: 1) outside the scope of the 

proposed action; 2) expressing agreement or support of the proposed project; 3) irrelevant to the 

decision to be made; or 4) conjectural and not supported by scientific or factual evidence. 

The Council on Environmental Quality (CEQ) regulations for NEPA require this delineation in 

Section 1501.7, to “identify and eliminate from detailed study the issues which are not significant 

or which have been covered by prior environmental review.” A list of non-significant issues and 

reasons regarding their categorization as non-significant may be found in the Project Record 

(Document # 17). 

The following issues were classed as significant:

1. Toxicity of herbicides to the public and agency employees. Specific concerns included 

on-site posting of treated areas, notification of the public (especially those with multiple 

chemical sensitivity), toxicity of herbicides and surfactants, and use of herbicides other than 

those registered by the Environmental Protection Agency (EPA). 
Chapter 1 – Purpose and Need

18 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Human exposure risks have been evaluated in a series of Risk Assessments developed by 

Syracuse Environmental Research Associates under contract with the Forest Service, which 

are incorporated herein by reference. The evaluation criteria for these effects are the risks to 

human health of herbicide use, the predicted location and size of area to be treated, preferred 

treatment method, and identification of areas where no chemical treatments would be used. 

Two alternatives (No Action and No Herbicides) are responsive to this issue.

2. Toxicity of herbicides to non-target vegetation and wildlife. Effects are described in 

narrative and tabular form through a wildlife specialist’s report, biological assessment and 

evaluation and analysis of effects on management indicator species (MIS) and other wildlife, 

fish and plants. Mitigation measures have been included in the design of all action 

alternatives to minimize exposure to non-target species. Wildlife exposure risks have been 

evaluated in the aforementioned series of Risk Assessments written by Syracuse 

Environmental Research Associates, which are incorporated by reference.

Issues and Concerns Addressed through Project Design

In response to scoping comments, the proposed action was modified and analysis broadened to 

address some of the issues identified. The Tonto NF’s invasive species list was increased 

considerably to include species such as yellow sweetclover and Russian thistle, and also other 

species that are not currently on the Forest but are close to its boundaries. The request by a 

commenter to use species-specific management guidelines led to inclusion of a section on 

treatments discussed by individual weed species. The request to identify how infestations began

led to the section on vectors. Another suggestion was to increase the number of acres that could 

be treated annually. 

A comment that aerial application should be included in the proposed action was considered. The 

need to begin implementation of invasive plant management quickly, and the possibility of 

controversy and delays in a decision that aerial spray application of herbicide would bring, led the 

team to defer this to a separate future analysis. Most infestations do not currently occupy large 

contiguous areas, thereby generally precluding aerial herbicide application. If future weed 

infestations are extensive enough to make aerial herbicide application a feasible control 

technique, an EIS would need to be completed. A comment on the potential for weed-burning 

projects to adversely affect air quality was addressed by mitigative measures that are required for 

any prescribed burn. Comments on the possibility for heavy equipment to bring in additional 

weeds and create unwanted ground disturbance are addressed through mitigation. And finally, 

comments from a community in the Globe area were addressed by excluding herbicide use from a 

portion of the Forest surrounding that community.

Incorporation by Reference

Regulations implementing NEPA provide for the reduction of bulk and redundancy (40 CFR 

1502.21) through incorporation by reference, when the effect will be to reduce the size of 

documents without impeding agency and public review of the action. The following documents 

are incorporated by reference and form the basis for the conclusions related to human health and 

effects to non-target species:
Chapter 1 – Purpose and Need

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 19

Risk Assessments for Aminopyralid, Chlorsulfuron, Clopyralid, Dicamba, Glyphosate, Imazapic, 

Imazapyr, Metsulfuron methyl, Picloram, Sethoxydim, Sulfometuron methyl, and Triclopyr are 

available on the website http://www.fs.fed.us/foresthealth/pesticide/risk.shtml.

Biological Assessment and Evaluation for Environmental Assessment for Management of 

Noxious Weeds and Hazardous Vegetation on Public Roadways on National Forest Service 

System Lands in Arizona (U.S. Forest Service, Southwestern Region, 2004).

Final Environmental Impact Statement for the Integrated Treatment of Noxious Invasive Weeds 

on the Coconino, Kaibab, and Prescott national forests (U.S. Forest Service, 2004, Feb.).

Environmental Assessment for the Invasive Exotic Plant Management Program. Coronado 

National Forest (U.S.F.S. Coronado NF, 2004).

Recommended Protection Measures for Pesticide Applications in Region 2 of the U.S. Fish and 

Wildlife Service (USFWS, 2007a).

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 21

Chapter 2 – Alternatives, Including the 

Proposed Action

The Proposed Action: Integrated Vegetation Management to Treat Weed Infestations

The Forest Service proposes eradication, containment, and/or control of noxious weed and 

invasive plant species on parts of the Cave Creek, Globe, Mesa, Payson, Pleasant Valley, and 

Tonto Basin ranger districts. The Tonto NF is within Gila, Maricopa, Pinal, and Yavapai 

counties, and comprises a total of 2,872,876 acres. Known noxious weed infestations cover only a 

small percentage of acreage on the Tonto National Forest; however, unknown infestations may be 

found anywhere within the nearly three million acres of the Forest thereby increasing the overall 

total of infested acreage. 

This project will be reviewed after ten years. If weed control beyond the scope of this analysis 

becomes necessary, further analysis under NEPA will be conducted. 

Proposed noxious weed treatment measures are a part of a broad strategy of Integrated Vegetation 

Management (IVM) (FSM 2080.2), which is composed of five elements:

Prevention and Detection

• Conduct fire management activities in such a manner that noxious weeds are not 

introduced or spread during fire suppression or prescribed burn projects.

• Educate the public, employees, and permittees to identify and report noxious weeds.

• Ensure all contractors and permittees operating on the National Forest understand and 

comply with the Forest’s Noxious Weed Policy.

• Conduct weed surveys, as funding allows.

Treatment of existing populations

• Implement an integrated vegetation management strategy using cultural, physical, 

mechanical, biological, or chemical methods of control. New populations are treated 

as they are found, and as long as the conditions of this analysis and decision are met, 

no further NEPA analysis will be performed.

Monitoring

• Monitor effectiveness of control methods annually for five years following treatment.

• Monitor all known populations at least every three years, noting density and area of 

infestation.

Restoration

• In areas where there are large infestations of an invasive species, where treatment 

would result in expanses of bare ground, restore native vegetation following 

treatment. Restoration efforts would mainly involve erosion control and planting of 

native species. Restoration may also be needed after large disturbance events such as 

floods or fire, to prevent invasive plants from establishing.

Coordination, cooperation and education

• Continue ongoing cooperation efforts with other agencies and landowners, and 

encourage new cooperative efforts as appropriate. These efforts should include lands 

of all ownerships and jurisdictions to ensure overall weed control.

• Partner with the State of Arizona Department of Transportation and other road 

management agencies to cooperate on control of invasive exotic species and ensure 
Chapter 2 – Alternatives

22 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

mulches and seed mixes are weed free, including coordination of this treatment plan 

with the ongoing statewide plan for treatment of invasive exotic plants in state and 

federal highway rights-of-way. Ensure invasive plant surveys are conducted for new 

highway construction early in the planning process. Work with ADOT and other road 

management agencies to ensure weeds found are treated to prevent spread during 

construction.

• Continue to develop and implement educational and public awareness materials.

Most of these elements require only administrative action to accomplish. This proposed action 

evaluates treatment and restoration of sites with noxious weed infestations. Noxious weed 

treatment methods in this Integrated Vegetation Management approach include:

Manual – hand pulling and using hand tools to selectively remove noxious weeds from 

native plant communities. These treatments are effective in controlling new infestations of 

many weeds; however, they are very labor-intensive and may be ineffective on some types of 

weeds such as deep-rooted species or ones with fibrous roots. This control method will be 

used on up to 400 acres each year.

Mechanical – Using motorized equipment to mow, clip, or till. Many mechanical treatments 

are expensive. This control method will be used on up to 500 acres each year.

Prescribed Burning – Burning is an inexpensive and often effective method to remove large 

quantities of seed of annual weeds. It can be used effectively, in combination with other 

treatments, as an integral part of multi-year strategy, especially for annual weeds. This 

control method will be used on up to 2,000 acres each year.

Cultural – Seeding with plants that prevent infestation by invasive plants. Establishment of

desirable plants is essential to preventing areas of bare ground created by construction or 

other activities from being vulnerable to infestation of weeds. Fertilizers or mycorrhizal 

inoculants may be included in some revegetation projects to increase establishment success. 

This method will be used on up to 2,000 acres each year.

Biological – Use grazing animals, approved insects and pathogens to control weeds. 

Biological treatments are typically used when the objective is control and not eradication. 

The biological agent and the weed co-exist to the extent that spread of the weed is limited.

Once biological control agents, such as insects or plant pathogens are released, they may 

cover a large number of acres, if there is a continuous infestation of their target weed plant. If 

grazing animals are used for biocontrol, impacts of the action will either be evaluated in a 

new analysis or authorized according to an existing grazing permit. 

Herbicidal – Application of approved chemicals to noxious weeds. Herbicides would be used 

to treat up to 9,000 acres per year (about 0.3 percent of the National Forest. Actual acreage of 

treatment would probably be much less, as it would be limited by funding each year. Annual 

weed management efforts will be coordinated with treatment efforts undertaken by other 

federal, state and local governments, and Weed Management Areas. The majority of 

treatments will occur along roads and other travel corridors. 

Twelve herbicides and carriers (or additives) are proposed for use: aminopyralid, 

chlorsulfuron, clopyralid, dicamba, glyphosate, imazapic, imazapyr, metsulfuron methyl, 

picloram, sethoxydim, sulfometuron methyl, and triclopyr. These herbicides have been 
Chapter 2 – Alternatives

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 23

approved for use on the three northern forests in Arizona (Coconino, Kaibab, and

Prescott) and/or on rights-of-way on federal and state highways in all national forests in 

Arizona. 

Plant Treatment by Species

Characteristics of each species are discussed in detail in appendix A. Refer to table 1 for 

classification of each species, in the following discussion.

Russian knapweed

Acroptilon repens

Cultural control/Use of prescribed fire:

Seeding competitive, perennial grass species after Russian knapweed has been stressed by other 

control measures is essential (Beck, 2012). Cultural control is most effective when combined with 

mechanical and/or chemical control techniques.

Mechanical/hand control:

This plant’s perennial growth habit and deep-rooting system render hand or mechanical removal 

methods fairly useless, when not used in combination with herbicides. 

Herbicidal control:

A single control strategy, such as mowing or herbicide application, usually is not sufficient. 

Russian knapweed is best controlled with a selective, post-emergent herbicide; however, 

herbicides alone will not control Russian knapweed. They should be used in combination with 

cultural or mechanical/hand controls, such as mowing and seeding with perennial grasses. Some 

tillage may be needed prior to seeding to overcome the allelopathic effects of the knapweed 

(Beck, 2012). Herbicides that could damage grasses should not be used, because competition 

from grasses is known to stress Russian knapweed (Beck, 2012). Chlorsulfuron and metsulfuron 

control this species, but only if applied during the bloom or post bloom stage. A surfactant should 

always be used.

Biological control:

In North America, Russian knapweed is relatively free of parasites and is not extensively attacked 

by generalist feeders (Carpenter & Murray, undated a). Only two biological control agents have 

been approved for release on Russian knapweed; Subanguina picridis, a gall-forming nematode, 

and Aceria acroptiloni, a gall-forming mite.

Tonto NF Goals & Strategy:

Russian knapweed occurs in very few locations on the Tonto NF. It is classified as an “A” 

species, one that poses a serious threat to ecosystems. Infestations will be eradicated when found, 

using combinations of the tools above. To date, Russian knapweed infestations have been 

removed manually. Since this species is a deep-rooted perennial plant, this method has been 

rather ineffective in permanently removing the infestation. One infestation at an old mill site was 

treated by scraping the surface soil to a depth of 2 feet and burying the displaced soil in a deep 

pit. This was extremely expensive and is only financially feasible for treating special status sites

when extra funding is available. Also, this method of treatment would probably not be 

appropriate in most wildland situations where the goal is to retain as much native vegetation and 

ground cover as possible.
Chapter 2 – Alternatives

24 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Jointed goatgrass

Aegilops cylindrica

Jointed goatgrass is often a weed of wheat fields; therefore, most control measures discussed in 

scientific literature are related to agronomic situations rather than control in wildland settings.

Cultural control/Use of prescribed fire: Cattle that have eaten jointed goatgrass-infested hay, or 

have grazed on this plant scatter viable seed on rangelands through their manure. Studies have 

found 75 percent of jointed goatgrass seed that has passed through a cow’s rumen is still viable 

(Lyon, et al., 2007). Thus, using weed-free feed for livestock on the National Forest is important.

Burning during the soft boot stage, or after flowering, but prior to seed maturity, can be used to 

eliminate a season’s seed crop. Burning often promotes germination of the following year’s crop 

of goatgrass, creating the need for a follow-up plan the year after the burn (CDFA, 2005).

Mechanical/hand control: Mowing can be an effective method of reducing seed production of 

jointed goatgrass; however, timing is critical. Mowing should occur after flowering, but before 

goatgrass seeds reach the soft boot stage. Early mowing will result in new tiller growth and late 

mowing will only spread viable seed. Tillage may be utilized in certain situations. Hand pulling 

or hoeing small infestations is effective, if the roots are pulled and air-dried (CDFA, 2005).

Herbicidal control: No herbicides have been found that are selective for jointed goatgrass in 

cropland situations, including wheat. In rangeland, nonselective herbicides may be used on small 

infestations. Sethoxydim is an herbicide that controls annual and perennial grasses and may be 

effective for treating jointed goatgrass. Herbicide should be applied after tillering and prior to 

flowering (CDFA, 2005).

Biological control: There are no biological control methods available for jointed goatgrass 

(Callihan & Miller, 1999). Grazing is not an effective tool, since grazing animals serve to spread 

the infestation through survival of viable seed in their manure. 

Tonto NF Goals & Strategy: This plant is classified as a “B” species. The goal is to contain its 

spread, reduce the population, and then eliminate it. Only one site has been treated on the Forest. 

In 2009, an ADOT contractor sprayed an infestation in the right-of-way of State Route 87 north 

of Payson. Monitoring conducted in 2010 determined this treatment was successful.

Tree of Heaven

Ailanthus altissima

Cultural control/Use of prescribed fire: Establishing a thick cover of trees (preferably native

and non-invasive) or grass sod will help shade out and discourage establishment of Ailanthus

seedlings. However, Ailanthus usually crowds out and replaces native trees, and fire serves only 

to increase sprouting.

Mechanical/manual control: Young seedlings may be pulled or dug up, preferably when soil is 

moist. Care must be taken to remove the entire plant including all roots and fragments, as these

will almost certainly regrow. Root suckers appear similar to seedlings, but are connected to a preexisting lateral root and may be nearly impossible to remove effectively by hand or with 

mechanical equipment (Swearingen & Pannill, 2005).
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EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 25

Cutting alone is usually counterproductive because Ailanthus responds by producing large 

numbers of stump sprouts and root suckers. However, for small infestations, repeated cutting of 

sprouts over time can exhaust the plants’ reserves of carbohydrates and may be successful, if 

continued for many years or where heavy shade exists. Initial cutting should be in early summer 

in order to impact the tree when its root reserves are lowest.

Herbicidal control: The most effective method of Ailanthus control seems to be through the use 

of herbicides, which may be applied as a foliar (to the leaves), basal bark, cut stump, or hack and 

squirt treatment (Swearingen, 2005).

Biological control: There are currently no approved biological control methods for Ailanthus.

Tonto NF Goals & Strategy: Elimination of Ailanthus requires diligence due to its abundant 

seed production, high seed germination rate, and vegetative reproduction. Regardless of the 

method selected, treated areas should be rechecked one or more times a year and any new suckers 

or seedlings treated (cut, sprayed, or pulled) as soon as possible, especially before they are able to 

rebuild root reserves. Targeting large female trees for control will help reduce spread of Ailanthus 

by seed (Swearingen & Pannill, 2005). One infestation growing along U.S. Hwy. 60 between the 

towns of Superior and Miami was treated by cut stump herbicide application. This project met 

with limited success. Apparently either a stronger concentration of herbicide is needed, or 

repeated applications. While many trees were successfully treated, a number of them sprouted 

from the base and will need retreatment.

This is a “C” species – management strategy is to contain spread and decrease the population, if 

possible. The main reason for this classification is that it is a popular ornamental plant in 

communities within the Forest boundary, such as Globe/Miami, Superior, and Payson. Residents 

are unlikely to kill or remove these trees that provide shade for their houses and yards. Removal 

efforts on the Tonto NF will emphasize detection of outlier infestations--such as a small number 

of saplings near the confluence of Pinal Creek and the Salt River--and eliminating them. 

Camelthorn

Alhagi maurorum

Cultural control/Use of prescribed fire: Cultural control methods that can be used to prevent 

introduction of this aggressive species include: use of weed-free hay on the National Forest, 

cleaning heavy equipment before it is brought in for any ground-disturbing type of work, and 

preventing livestock from eating the plant and transporting the seed to the Forest via manure.

Mechanical/hand control: Because of its deep and extensively branched root system, 

mechanical treatments do not control camelthorn (ADOT, 2005).

Herbicidal control: Herbicides provide the best means of control. When using herbicides, 

different chemicals should be used each year to prevent the establishment of an herbicideresistant population (ADOT, 2005)

Biological control: There are currently no biological control agents approved for control of 

camelthorn (Coconino NF & San Francisco Peaks Weed Management Area, 2001)

Tonto NF Goals & Strategy: Camelthorn is an “A” species on the Tonto’s list. Infestations will 

be treated quickly to eradicate them before they can establish. Once this plant establishes, it is 

extremely difficult to eradicate.
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26 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Several years ago, ADOT successfully treated a large infestation of camelthorn north of Globe. 

No follow-up has occurred for the last five years, and the camelthorn is beginning to come back. 

Owing to its extensive root system, this plant is persistent and will need repeated herbicide 

applications and monitoring. In 2010 a single camelthorn plant was discovered growing in the 

median of SR 260 near Christopher Creek. ADOT’s contractor treated this plant with herbicide;

monitoring over the next 6 months has detected no sprouting and the plant appears to be dead.

Herbicide use can be limited by treating individual plants whenever they appear.

Giant reed

Arundo donax

Cultural control/Use of prescribed fire: Prescribed burning, either alone or combined with 

herbicide applications, may be effective if conducted after flowering. 

Mechanical/hand control: Mechanical/hand control (e.g., repeated mowing) may be somewhat 

effective, but any small fragments of root left in the soil may lead to re-establishment.

Herbicidal control: Areas infested with giant reed are best restored through chemical means.

The most effective timing is post-flowering and pre-dormancy, when plants are translocating 

nutrients into the root system (Hoshovsky, 1986). Systemic herbicides, such as glyphosate (e.g., 

Rodeo), or imazapyr (Habitat) may be applied to clumps of giant reed after flowering, either as a 

cut stump treatment or as a foliar spray (Benton, et al., 2005). 

Biological Control: No biological control agents have been introduced for giant reed.

Tonto NF Goals & Strategy: Like tree of heaven, this species is commonly planted in some of 

the communities that lie within the boundaries of the Tonto NF. There are many established small 

populations of this plant in Camp Verde, Superior, and Globe. Arundo is not an extremely 

aggressive invader. It is possible that after a scouring flood that removes large amounts of 

Phragmites spp. from along the Verde River, Arundo may become established in its place. These

species occupy similar niches in riparian communities; however, Arundo can live on drier sites.

Forest Service river rangers working on the Coconino and Prescott NFs have been trained, so they 

are able to distinguish between the two species. They are currently working to remove several 

Arundo infestations on the Coconino and Prescott NFs along the Verde River upstream of the 

Tonto NF. They have mapped several infestations on the Tonto NF section of the Verde River. 

The Tonto NF will be participating in this program of Arundo control along the state’s only two

Wild and Scenic rivers: the Verde River and Fossil Creek

Onionweed

Asphodelus fistulosus

Cultural control/Use of prescribed fire: This plant is sometimes sold as an ornamental. An 

education outreach effort with partners to check local nurseries periodically and request the 

owner to remove it from sale would prevent potential infestations coming from private lands near 

the Forest.

Mechanical/hand control: Pulling the plant is usually not effective. The top breaks off, leaving 

the tuberous roots underground. Plants must be dug up by the roots (Arizona-Sonora Desert 

Museum, 2005).

Herbicidal control: Herbicides are the best method of control for onionweed.
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EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 27

Biological control: There are no approved biological control agents available for onionweed.

Tonto NF Goals & Strategy: Onionweed is an “A”species; management goal is to detect new 

infestations early and eradicate them. APHIS has an active program to educate landowners in 

areas that have had infestations in the past, and to conduct surveys for this plant. It will be the 

Tonto NF’s strategy to cooperate with APHIS in any survey or control efforts on or near the 

Forest.

Wild oats

Avena fatua

Cultural control/Use of prescribed fire: Appropriately timed (cool season) grazing by 

herbivores may provide control.

Mechanical/hand control: Mowing may be useful in certain circumstances in controlling wild 

oats. Researchers in annual grasslands in California used selective herbicides to remove annual 

weedy grasses, followed by mowing and seeding of native bunchgrasses along roadsides (Bugg,

et al., 1991). They were successful in initial stages of replacing weedy annual grasses with native 

perennial bunchgrasses. Bugg and associated researchers projected that restoration of native 

vegetation along roadsides would greatly reduce maintenance and herbicide costs.

Herbicidal control: Some herbicides may be effective for control; however, herbicide-resistant 

strains of wild oats exist because of routine spraying under cropland conditions (Friesen, et al.,

2000).

Biological control: Biocontrol of wild oats, one of the world's most serious weeds, is largely 

unexplored. One study investigated crown rust disease as a potential control agent for wild oats 

on San Clemente Island. The result showed that application of crown rust lowers the competitive 

ability of wild oats, while raising that of Stipa, a native grass. Crown rust may be an effective 

biocontrol agent when used in a suite of management tools (Sands, et al., 2000). Development of 

crown rust as a tool for control of wild oats is not likely to occur within the next several years.

Tonto NF Goals & Strategy: Wild oats are extremely widespread on the Tonto NF and 

neighboring forests. Our goal is to prevent new infestations by requiring any seed to be used for 

revegetation to be free of species on the Tonto NF’s weed list. Seed mixes for revegetation will 

emphasize native perennial grasses, including cool-season growers that should out-compete wild 

oats over the long term.

Black mustard

Brassica nigra

Cultural control/Use of prescribed fire: Prevention of new infestations by state lab testing of all 

seed mixes introduced on the Forest will be key to controlling spread of black mustard.

Mechanical/hand control: Manual methods are effective for small infestations.

Herbicidal control: Herbicides can be used for controlling black mustard. They are best used 

during the rosette stage.

Biological control: Biological control using microfauna is not an option, since there are several 

mustard crop plants that would probably also be susceptible. Biocontrol using livestock is a 

possible treatment option for the winter/early spring season when invasive mustards are growing.
Chapter 2 – Alternatives

28 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Tonto NF Goals & Strategy: Most black mustard infestations on the Forest were planted with

revegetation seed mixes that predate the Tonto NF’s current seed testing policy. New infestations 

will be prevented by requiring lab-testing for all seed used in revegetation projects. Existing 

infestations, which are in disturbed areas, will be removed.

Asian mustard

Brassica tournefortii

Cultural control/Use of prescribed fire: Establishment of a dense cover of grasses appears to 

suppress growth of Asian mustard. Prescribed burning may reduce seed survival, but hard seed 

coats allow some seeds to escape harm from the fire. Prolonged seed longevity in the soil can 

bring stem densities up to pre-burn levels within one or two growing seasons, depending upon 

winter/spring rainfall.

Mechanical/hand control: Manual methods are effective for small infestations.

Herbicidal control: Early winter/spring growth of this annual allows effective herbicide control

without affecting native plants that grow later in the season (Sanders & Minnich, 2005).

Biological control: As with black mustard, biological control using microfauna or disease is not 

a likely option, due to the relationship of this plant to numerous crop plants. Placement of 

livestock in areas with high densities of Asian mustard in the winter/early spring period when 

most other plants are not growing is a viable option.

Tonto NF Goals & Strategy: The Tonto NF’s strategy for this species is to control it beginning 

from its farthest extent away from disturbed sites, limiting it to its previous habitat of disturbed 

roadsides. The Tonto NF will work cooperatively with the Arizona Department of Transportation 

to identify priority sites for treatment along state and federal highways on the Forest. New 

construction sites will be monitored closely, and new infestations of Asian mustard will be treated 

before they are allowed to go to seed. The long-term goal is to eliminate it from disturbed areas, 

such as roadsides. One site along State Route 188 has been reduced in density by using manual 

treatment by a Department of Corrections crew. Several full days were needed by the DOC crew

to remove only a couple of acres of this plant.

Red brome, rescuegrass, downy brome, Japanese brome, ripgut brome

Bromus rubens, B. catharticus, B. tectorum, B. japonicus, B. diandrus

Cultural control/Use of prescribed fire: For higher elevations, maintaining good range 

condition, with a good groundcover of perennial grasses will prevent extensive infestations of 

brome grasses. Post-fire soil inoculation with local species of mycorrhizae is a promising 

experimental technique that could both stabilize soil and prevent germination of the large-seeded 

brome grasses (Warren, 2007).

Mechanical/hand control: Mowing along rights-of-way may be a practical treatment, if done 

prior to flowering and seed-set.

Herbicidal control: Some herbicides are effective on these brome grasses, which can be targeted 

without damage to many other plants, since they grow very early in the year when most other 

plants are still dormant.
Chapter 2 – Alternatives

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 29

Biological control: Grazing by domestic animals during winter and early spring may remove 

these grasses from the Sonoran Desert where they potentially can create a fire hazard. They are 

particularly abundant after wet winters – thus, livestock may be brought in during December 

through early to mid-February to graze. Some work is being done to investigate the use of 

naturally-occurring fungal and bacterial seed bank pathogens to control annual bromes.

Development of technically and economically feasible harvesting and application techniques is 

the subject of research at the Shrub Sciences Laboratory of the Forest Service Rocky Mountain 

Research Station in Provo, Utah (Meyer, 2011).

Tonto NF Goals & Strategy: These annual grasses are extremely widespread on the Tonto NF 

and in Arizona. They are included in the Tonto NF noxious weed list, so populations can be 

selected for treatment when this will achieve a strategic objective.

Globe-podded hoary cress, hairy white-top

Cardaria draba, C. pubescens

Cultural control/Use of prescribed fire: Fire is not an effective treatment since Cardaria

species are known to expand after fire. Fire appears to stimulate root budding of lateral roots.

Mechanical/hand control: Mechanical/hand control is not effective, since these plants are 

deeply rooted species. If it is pursued diligently over several years, so above-ground parts are not 

allowed to replenish root reserves, control of small infestations is possible.

Herbicidal control: Herbicides are the surest method of control but must be re-applied over 

several years to obtain results. The most effective timing of application is the bud to early flower 

stage. Chlorsulfuron, sulfometuron, and glyphosate have all been used with good results (CDFA,

2005).

Biological control: There are no biological controls approved for these species. Cattle and sheep 

may graze them with no ill effects.

Tonto NF Goals & Strategy: This plant is uncommon on the Tonto NF. Small infestations will

be eradicated when they are discovered.

Plumeless thistle

Carduus acanthoides

Cultural control/Use of prescribed fire: Good range management is an effective tool to 

decrease the possibility of infestation by this thistle and most other thistles.

Mechanical/hand control: Well-timed mowing, during early flowering will prevent seed 

production, but re-sprouting from the base may occur. Control using hand tools is effective on 

very small populations prior to seed maturity (Remalay, 2005). Soil disturbance should be 

minimized to prevent seeds germinating in the soil.

Herbicidal control: Several herbicides are effective for control of plumeless thistle. 

Chlorsulfuron, dicamba, clopyralid, glyphosate, picloram, or combinations of these herbicides 

provide excellent control (CDFA, 2005).

Biological control: The thistle head weevil (Rhinocyllus conicus) infests a number of genera in 

the thistle tribe, including species of Carduus, Cirsium and Onopordum. The larvae of thistle 
Chapter 2 – Alternatives

30 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

crown weevil (Trichosirocalus horridus) feed on the growing tips of the thistle rosette, and adult 

weevils slightly defoliate plants. Larvae of thistle crown fly (Cheilosia corydon) damage leaves, 

stems and crowns of plumeless thistle. This insect can also lower total seed production and can 

kill the plant, if it infests the roots. 

Goats seem to prefer thistle flowers to leaves. Seeds ingested by goats and other ruminants are 

nearly all digested and are not viable.

Tonto NF Goals & Strategy: Plumeless thistle is an “A” species on the Tonto NF. New 

infestations will be eradicated.

Musk thistle

Carduus nutans

Cultural control/Use of prescribed fire: Open areas are susceptible to infestation by thistles. 

Construction sites and roadsides should be checked for this and other thistle species. Good range 

management is also important, as for plumeless thistle.

Mechanical/hand control: Control using hand tools is effective on small populations, prior to 

seed maturity (Remalay, 2005). Soil disturbance should be minimized to prevent seeds on the soil 

from germinating.

Herbicidal control: Herbicides need to be applied during the rosette stage or prior to flowering 

(Remaley, 2005b). The same herbicides that are named above for plumeless thistle control are 

also effective on musk thistle (CDFA, 2005).

Biological control: Two weevils introduced from Europe (Rhinocyllus conicus and 

Trichosirocalus horridus) have been used to control musk thistle.

Tonto NF Goals & Strategy: Musk thistle is an “A” species – new infestations receive the 

highest priority for eradication. When musk thistle was first discovered on the Tonto NF, a large 

effort was expended to manually remove all plants that were found. Repeated surveys in Robert’s 

Draw north of Payson have turned up additional small infestations. Robert’s Draw is the only 

known site where musk thistle grows on the Tonto NF.

Southern & Field sandbur

Cenchrus echinatus, C. spinifex

Cultural control/Use of prescribed fire: Requirements for routine cleaning of equipment 

brought in for fire suppression or used for construction projects will prevent new infestations.

Flaming is effective, if done prior to seed set. Flaming is not necessarily total burning of the 

plant. Flaming is application of fire to green plants, effectively killing them by bursting cells. It is 

usually done with propane torches.

Mechanical/hand control: Tillage is effective only when plants are small. It may possibly 

increase seed germination by burying seeds on the soil surface that have not already germinated 

due to light-inhibition. Even relatively deep tillage is not effective in controlling sandbur, as seeds 

can germinate from a depth of four inches. 

Repeated mowing prior to flowering will reduce, but not eliminate seed production. Mowing is 

most effective at the boot stage of development. Disturbance by road maintenance activities is 
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EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 31

liable to spread the bur-like seeds of these two grasses. Agencies who mow rights-of-way along 

SR 188, U.S. 60, and roads through Globe will be made aware of the location of field sandbur

infestations known in these areas, in order to take measures to avoid spreading seeds with mowers 

and other heavy equipment.

Herbicidal control: Chemical control can be very effective. There are currently no known cases 

of herbicide resistance in Cenchrus species, even though they commonly grow near crop fields.

Biological control: There are no biological controls for sandbur.

Tonto NF Goals & Strategy: There is currently only one known sandbur infestation on the 

Tonto NF. It was found near extensive patches of sandbur on the Fort Apache Reservation, on 

State Route 188 north of Globe, shortly before a highway reconstruction project. It has not been 

found now that the highway project has been completed, but it very likely will show up 

somewhere in the general vicinity, since no measures were taken to prevent its spread. Treatment 

of this plant must be coordinated with our neighbors on the reservation before any treatment on 

the Forest would be effective. Our goal is to eliminate this plant from the right-of-way on 

Highway 188 and prevent new infestations. 

Diffuse knapweed

Centaurea diffusa

Cultural control/Use of prescribed fire: The use of fire has demonstrated mixed results for 

managing diffuse knapweed. Fire followed by vigorous grass regrowth can reduce knapweed 

stands; however, crown resprouts and increased seedling germination may eliminate any benefits 

from burning. 

Mechanical/hand control: Hand pulling of small infestations of diffuse knapweed has shown 

considerable success. Since resprouting from the crown can occur, the entire plant must be 

removed. Hand pulling must be repeated 2 to 4 times a year and is easiest when the plants have 

begun to bolt in the late spring and the soil is still moist. Hand pulling of large infestations is 

labor intensive and may not always be feasible.

Herbicidal control: Herbicides can be used to control existing stands of diffuse and spotted 

knapweeds and substantially reduce seed production; however, since the seed of both species is 

viable in the soil for up to seven years, retreatment will be necessary. Long-term reductions in the 

seed bank must be the goal for effective knapweed management with herbicides (CDFA, 2005).

Applying the correct herbicide to newly emerged plants following a burn is an effective approach.

Biological control: There are 12 insects established in the western U.S. that attack diffuse 

knapweed. These insects are most effectively used in combinations that affect different life stages 

of the thistle. 

The gall-forming flies Urophora affinis and U. quadrifasciata are seedhead feeders, but do not 

significantly adversely affect seed production of diffuse knapweed. Chaetorellia acrolophi, the 

peacock fly, three weevils, Bangasternus fausti, Larinus obtusus, and Larinus minutus, the fly 

Terellia virens, and the moth Metzneria paucipunctella feed on seedheads. L. minutus may be 

especially damaging, as one larva can destroy the entire contents of a seedhead, along with any 

other insects that are in that seedhead. L. obtusus prefers spotted knapweed. L. minutus is 

established in Arizona. Roots are damaged by the larvae of the buprestid beetle Sphenoptera 
Chapter 2 – Alternatives

32 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

jugoslavica, the weevil Cyphocleonus achates, and the moths Pterolonche inspersa and Agapeta 

zoegana. 

Two fungal pathogens are not yet cleared as biocontrol agents, but show promise for effective 

control of diffuse knapweed: Puccinia jaceae attacks the leaves, and Sclerotinia sclerotiorum

attacks the crowns (Piper & Story 2004). 

Tonto NF Goals & Strategy: This plant is quite widespread in the community of Pleasant Valley 

and there are many patches of it on the National Forest on the Pleasant Valley Ranger District. 

Containment and eventual eradication are the goal for this species. The Tonto NF will work with 

the Tonto Weed Management Area and the community of Young to prevent spread of the 

infestation to new locations. Known patches on the Forest will be treated by one or more of the 

methods above each year, and employees will be educated to identify and report new infestations 

they find during the course of their duties. When possible, new areas will be surveyed. 

Spotted knapweed

Centaurea stoebe

Cultural control/Use of prescribed fire: Revegetation with desirable plants creates competition 

that stresses spotted knapweed. Together with other control methods, this can be part of an 

effective treatment program.

Mechanical/hand control: Small infestations of spotted knapweed can be controlled by 

persistent hand-pulling done prior to seed set. Care must be taken to remove the entire crown and 

taproot, as it can regrow from the base. Gloves should be worn when working with spotted 

knapweed.

Herbicidal control: Control of spotted knapweed infestations using three chemical herbicides 

(2,4-D, clopyralid, and picloram) has been reported effective (Carpinelli, 2005). This project 

proposes use of clopyralid and picloram, among others listed for use in the proposed action.

Biological control: A variety of natural enemies are used as biological control agents for large 

infestations of spotted knapweed. Most biocontrol techniques use insect larvae to damage the 

root, stem, leaf, or flower. Two species of seed head flies, Urophora affinis and U. 

quadrifasciata, are well-established on spotted knapweed in other areas. The larvae of these 

species reduce seed production by as much as 50 percent by feeding on spotted knapweed seed 

heads and causing the plant to form galls (Carpinelli, 2005). There are three species of weevils 

that are seedhead feeding agents. They are Larinus minutus, Larinus obtusus and Bangasternus 

fausti, which feed on spotted knapweed and have been released in Arizona. Three moth species 

(Agapeta zoegana, Pelochrista medullana, and Pterolonche inspersa) and a weevil

(Cyphocleonus achates) that feed on spotted knapweed roots have also been released in the U.S.

(Carpinelli, 2005). The collective stress on the plant caused by these insects reduces seed 

production and may lead to reduced competitiveness.

Long-term grazing by sheep and goats has been found to control spotted knapweed (Carpinelli,

2005). 

Tonto NF Goals & Strategy: Spotted knapweed is an “A” species – any new infestations are to 

be eradicated before they have a chance to spread. The Payson Ranger District found this weed 

growing in their parking lot in 2009. They successfully treated it with application of the herbicide 

Milestone. Monitoring shows it has not returned. A very small infestation was identified at the 
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EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 33

Payson materials pit at the north end of Payson, in 2008. Heavy equipment was used to dig a 

large deep hole, where topsoil scraped to a depth of 4 to 6 inches from the knapweed site was 

deposited and covered with clean soil. Subsequent monitoring of this site has not detected any 

recurrences (Fenner, 2011).

Malta starthistle

Centaurea melitensis

This species is currently not on the state’s list of regulated plants. Creation and enforcement of a 

weed-free hay order will go a long way toward preventing new infestations. It is possible this 

weed is growing on agricultural fields on private lands within the Forest boundary. The Forest 

will attempt to work with these private landowners to treat Malta starthistle infestations on “both 

sides of the fence.”

Cultural control/Use of prescribed fire: Managing for high quality range condition will prevent 

large areas of open space available for infestation by starthistle. 

Burning, when used prior to herbicide application, serves three purposes – it eliminates a large 

number of seeds; stimulates seeds in the soil to germinate, and removes an overstory that would 

prevent herbicide from reaching newly germinated seedlings. DiTomaso recommends late 

spring/early summer flaming for yellow starthistle, before seed set (DiTomaso & Johnson, 2006).

Yellow starthistle is a close relative of Malta starthistle; both are cool-season annual forbs. 

Managers should not be discouraged when there are still abundant Malta starthistle crops 

germinating after a few years of treatment. Seeds live for ten years in the soil and by encouraging 

germination; the seedbank is worn down more quickly. Any treatment methods are necessarily 

long term with this annual plant. DiTomaso reports that burning of yellow starthistle for one year 

reduced the seed crop by 75 percent, but this was not sufficient to reduce the infestation. Two 

consecutive years of burning further reduced the seed bank. After three consecutive years of 

prescribed burning, the yellow starthistle seedbank was reduced by 99 percent, and cover of 

yellow starthistle was reduced by 91 percent. DiTomaso also recommended use of herbicides the 

year following a prescribed burn for starthistle control.

Mechanical/hand control: Mechanical methods, including pulling, grazing, mowing, burning, 

and cultivation, can be used over a period of several years to deplete seed banks and manage 

infestations (Donaldson & Raffert, 1986).

Hand pulling is effective for small populations. Once plants have shed seed in a location, it must 

be revisited several times each year, for 7 to 10 years, to pull seedlings.

Mowing, if done at the correct time of year, can be a part of the integrated weed management 

plan for Malta starthistle. Roadsides with dense infestations should be mowed at early flowering, 

in order to avoid scattering seeds during the fruiting stage. Mowing should be used carefully, as it 

is likely to spread the infestation and make it much worse, if done during the time of year when 

seedheads are mature or if proper procedures to prevent spread are followed. These procedures 

include beginning mowing in uninfested areas and moving toward infested areas, and thoroughly 

washing equipment after running it through sites known to have Malta starthistle. Mowing is not 

an optimal treatment, as a Malta starthistle plant will produce a flower very near its base early in 

the plant’s life. This flower is at ground level, below where mowers will cut; therefore even 

mown plants will produce at least some seed.
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34 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Herbicidal control: Herbicides selective for broadleaf weeds are desirable, since Malta 

starthistle often grows in rights-of-way in close association with native perennial grasses. ADOT 

has used clopyralid + chlorsulfuron along Highway 188 to control Malta starthistle; aminopyralid 

has also been used by ADOT and the Tonto NF. These are both very effective herbicides for the 

starthistles.

Biological control: Scientists are studying biological controls in the hopes of finding an insect or 

disease that will help reduce Malta starthistle populations. The beetle, Lasioderma 

haemorrhoidale, which feeds on seed heads, was introduced unintentionally from the 

Mediterranean region, but does not appear to adequately control the weed. Research completed in 

2001 suggests that the rust, Puccinia centaurea, holds some promise for control. It is specific to 

Malta starthistle, and does not infect yellow starthistle or bachelor’s button (Centaurea cyanus). 

The research suggests that heavy, early infection with the rust tends to suppress further growth 

and reproduction of Malta starthistle, although further research is needed to confirm these 

findings (Donaldson & Rafferty, 1986). Eustenopus villosus has been observed feeding on Malta

starthistle. APHIS may want to investigate the utility of this weevil for helping to control the 

large Malta starthistle infestation in Tonto Basin.

Tonto NF Goals & Strategy: The Tonto NF, in partnership with ADOT, has used prescribed 

burning in the summer/early fall, combined with follow-up applications of herbicide in the winter 

and early spring to reduce infestations along Highway 188 on the Tonto Basin RD. Flaming and 

grubbing have been used on small infestations on the Payson, Cave Creek and Globe RDs, and in 

the town of Payson.

Many infestations of this plant are too large (hundreds of acres) to be treated manually. Some 

infestations that have been manually removed have returned even larger in successive years.

Partnering with neighboring landowners is essential for effective treatment of Malta starthistle, 

since it is an annual plant that spawns large numbers of easily dispersed seed. Strategy for this 

weed involves removal from heavy-traffic areas, such as along roads and highways, combined 

with locating the outer edge of the infestation and treating “from the outside in,” and also finding 

and treating spot infestations, while they are still small. This strategy can be likened to that of 

fighting a large fire – containment, combined with special attention to “hot spots” scattered 

outside the perimeter of the main infestation.

Yellow starthistle

Centaurea solstitialis

Cultural control/Use of prescribed fire: Burning can provide control, if implemented before 

seed is produced (CDFA, 2005; DiTomaso & Johnson, 2006). See discussion above about use of 

prescribed fire for Malta starthistle.

Mechanical/hand control: Mowing is most effective when plants are cut below the lowest 

branches and 2 to 5 percent of the total population of seed heads is in bloom. Mowing too early 

can result in increased seed production (CDFA, 2005).

Herbicidal control: Clopyralid, picloram and aminopyralid are the most effective herbicides for 

fall season control of yellow starthistle. Unlike most post emergence herbicides, they provide 

both foliar and soil activity (DiTomaso, 2001). All starthistles are highly susceptible to the 

herbicide clopyralid (CDFA, 2005). 
Chapter 2 – Alternatives

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 35

Biological control: Six biological control agents of yellow starthistle have been imported from 

Europe and are well established in the western United States. Of these, the most effective are the 

hairy weevil (Eustenopus villosus) and the false peacock fly (Chaetorellia succinea). These 

insects attack the flower/seed head, and directly or indirectly reduce seed production by 43 to 76

percent. They do not, by themselves, provide sustainable management of starthistle, but can be an 

important component of an integrated approach (DiTomaso, 2001). The hairy weevil has been 

introduced on the Coconino NF in 2006 and 2007. The weevil Larinus curtis was introduced to 

yellow starthistle infestations on the Coconino NF in 2006. APHIS is also working to establish 

the agent Eustenopus villosus in Arizona.

High intensity, short-duration grazing by sheep, goats, or cattle can be implemented during the 

period when plants have developed flowering stems, but not when spiny heads are present.

Tonto NF Goals & Strategy: Yellow starthistle is a “B” species, as it is very common on private 

lands and is becoming a common weed on the Payson and Pleasant Valley RDs. As such, our 

goal is to contain its spread, pushing it back toward the areas of oldest and densest infestation. 

New spots will be aggressively treated. It is also our strategy to partner with local landowners and 

towns in combating this prolific weed. This species has been successfully treated with the 

herbicide Milestone (active ingredient aminopyralid) in the Payson and Star Valley areas. Due to 

recent successes in treating infestations in the area of Star Valley and Houston Creek, the staff on 

the Tonto NF is cautiously optimistic this species may eventually be eliminated on the Forest,

providing we are able to enlist private landowners to control their infestations.

Curveseed butterwort

Ceratocephala testiculata

Cultural control/Use of prescribed fire: This plant is an invader of open, disturbed areas, so 

maintenance of good ground cover is important. Effects of fire are unknown.

Mechanical/hand control: This is a very small plant, which makes manual control difficult. It 

grows close to the ground, which makes mechanical control measures such as mowing 

impractical.

Herbicidal control: Broadleaf herbicides with adjuvants to allow the herbicide to penetrate the 

hairy plant surface are effective.

Biological control: There are no known biocontrol agents for this plant.

Tonto NF Goals and Strategy: Curveseed butterwort is an “A” species, and should be controlled 

soon after it is found. Only very small infestations have been found to date (less than 0.01 acre) 

on the Payson Ranger District. Employees and volunteers should be educated to recognize this 

plant, so that new infestations can be quickly controlled.

Rush skeletonweed

Chondrilla juncea

Cultural control/Use of prescribed fire: Proper grazing management will prevent creation of 

large disturbed areas that are open to new infestations (CDFA, 2005).

Mechanical/hand control: Hand pulling can be effective, even though this plant has extensive 

carbohydrate reserves in its roots, if it is done a few times each growing season (Sheley, et al., 
Chapter 2 – Alternatives

36 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

1999). However, rush skeletonweed seedlings may form shoot buds from root fragments as young 

as 2 weeks old, and 95 to 100 percent of 5 to 7 week-old seedlings can regenerate from root 

fragments (Cuthbertson, 1972). 

Mowing reduces seed production, and over time, may reduce the plant’s ability to send up new 

rosettes from adventitious root buds (WSNWCB, 2007).

Herbicidal control: Once established, rush skeletonweed is extremely difficult to control using 

herbicides, primarily due to the difficulty of translocating herbicides into its extensive root 

system. Since 1944, trials have been conducted on rush skeletonweed with practically every new 

herbicide to come on the market. Of several herbicides tested for rush skeletonweed control in 

Washington in 1964, only picloram and dicamba were "acceptably effective." These herbicides 

provided most consistent results when applied in the fall (Zouhar, 2003a). Spring application of 

picloram and metsulfuron methyl have successfully treated rosettes and bolting plants. 

Glyphosate also works well, but is non-selective.

Biological control: Several organisms including insects, viral particles, and fungi, have been 

intensively studied as potential biological control agents for rush skeletonweed. The first effective 

biological control program for rush skeletonweed, involving several control agents, was 

established in Australia in the 1960s. These agents include the gall mite (Eriophyes chondrillae), 

the gall midge (Cystiphora schmidti), and the rust fungus (Puccinia chondrillina); the latter being 

the most effective (Zouhar, 2003a). The rust has multiple generations per year and has 

demonstrated success in California. This is the first example of an exotic fungus successfully 

used in biocontrol of a weedy plant (CDFA, 2005). Use of these biological agents is complex, and 

must fit in with an overall treatment program that includes other treatment methods.

Tonto NF Goals & Strategy: Chondrilla juncea is an “A” species – any plants observed will be 

documented and treated as quickly as possible.

Blue mustard

Chorispora tenella

Cultural control/Use of prescribed fire: Blue mustard is often dispersed as a seed contaminant. 

Following the protocol of having all seed lots checked for seeds on the TontoNF’s weed list by a 

state-approved lab prior to use could save much time and money later in removal of new 

infestations.

Mechanical/hand control: Cultivation is effective for control. Blue mustard can also be 

controlled by mowing, if done during early flowering. Small infestations can be hand pulled fairly 

easily, as it has a shallow taproot (CDFA, 2005).

Herbicidal control: Blue mustard is known primarily as a weed in grain crops. As such, it has 

evolved to become tolerant and somewhat resistant to typical 2,4-D use rates (CDFA, 2005). 

Herbicides that are effective against blue mustard include chlorsulfuron, dicamba, glyphosate, 

and sulfometuron. Most herbicide treatments work best when blue mustard is in the rosette stage.

Biological control: There are no approved biological controls for blue mustard at this time.

Tonto NF Goals & Strategy: This is an “A” species that has not yet been documented on the 

Tonto NF. Any new infestations are to be recorded, then eradicated.
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EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 37

Canada thistle

Cirsium arvense

Cultural control/Use of prescribed fire: Early season burning can stimulate its growth, so 

prescribed burns should be scheduled for late in the growing season.

Mechanical/hand control: Mechanical/hand control methods must be repeated often to wear out 

the carbohydrate root reserves. Small infestations can be eradicated with hand-pulling, if done 

repeatedly during over a growing season and over a period of several years.

Herbicidal control: Systemic herbicides that are translocated to the plants’ roots are most 

effective. Repeated applications at a site are probably necessary, due to the long life of seeds in 

the soil (Thunhorst & Swearingen, 2005).

Biological control: The larvae of a native North American insect, the painted lady butterfly 

(Cynthia cardui) defoliates thistle (Moore, 1975). Three insects have been introduced and are 

available commercially: the Canada thistle stem weevil (Ceutorhynchus litura), whose larvae feed 

on new leaf, stem, root crown and root tissue; Canada thistle bud weevil (Larinus planus), whose 

larvae feed on the seed head while adults feed on the foliage; and the thistle stem gall fly 

(Urophora cardui), whose larvae develop within the stem, thereby interrupting nutrient flow in 

the plant (Morishita, 2003).

Two pathogenic rust fungi have been tested for Canada thistle control. Sclerotinia sclerotiorum

affects the roots and crown; studies show it can cause death to 20 to 80 percent of new shoots 

(Graham, et al., 2003.). This fungus is not specific to Canada thistle. Another rust fungus that has 

been found to be specific to Canada thistle is Puccinia punctiformis, an obligate rust fungus 

parasite. It reduces flowering and vegetative reproduction (Morishita, 2003).

Tonto NF Goals & Strategy: Canada thistle is uncommon on the Tonto NF. All infestations 

should be controlled when found, using a combination of treatments listed above. In the summer 

of 2009, a newly discovered infestation of Canada thistle was treated with the herbicide 

Milestone. Follow-up monitoring in 2010 and 2011 showed some success, but continued control 

measures will be needed for several years.

Bull thistle

Cirsium vulgare

Cultural control/Use of prescribed fire: Since bull thistle is adapted to move into an area 

following burns, prescribed burns are not the best tool to use for control. Flaming of individual 

plants, with no soil surface disturbance may serve to kill plants and prevent them from maturing 

to produce seed. Ground disturbance, including heavy grazing by wildlife or domestic livestock 

increases vulnerability of a site to infestation by bull thistle and other thistles, as well. 

Competition by native perennial grasses is one deterrent to infestation by thistles.

Mechanical/hand control: Cutting and bagging flower and seed-heads prior to seed 

development, then using a spade to sever the taproot on the plant will kill the plant and remove 

any developing seeds.

Herbicidal control: Herbicides that are specific for broadleaved weeds are good tools for bull 

thistle control. When bull thistle is in the rosette stage, aminopyralid, clopyralid, dicamba, or 

picloram are good herbicide choices. After bolting begins, metsulfuron or chlorsulfuron are best. 
Chapter 2 – Alternatives

38 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

For bull thistle that grows in floodplains and along streambanks, herbicides rated for aquatic 

application will be used. 

Biological control: Using a combination of microfauna that attack different life stages of the 

plant, combined with seeding with native grasses, is a proven effective technique to control 

thistles. The seedhead weevil Rhinocyllus conicus prefers thistles of the genus Carduus, but will 

also attack other Cirsium species that are native species. The weevil Trichosirocalus horridus has 

larvae that feed on growing points of rosettes and developing shoots. Beck (1999) recommends 

integrating use of herbicides with insect biological control for the best results. This is best done 

by releasing insects into the center of an infestation, and using herbicides around the perimeter. 

Tonto NF Goals & Strategy: Bull thistle is a “C” species on the Tonto NF. Forest strategy is to 

treat high priority sites first, such as meadows and streamsides of Canyon Creek, by removing 

flowers/seedheads and grubbing rosettes throughout the summer and fall. Many volunteer groups 

have been recruited for this project, and ranger district Youth Conservation Crews (YCC) crews 

have worked on Canyon Creek as one of their summer projects. Bull thistle growing in some 

campground areas has been effectively treated with glyphosate and aminopyralid herbicides. 

In addition, disturbed areas, such as areas that have been burned, logged, or had pile burning will 

be surveyed for presence of bull thistle seedlings as soon as possible after the disturbance, in 

order to control bull thistle before it has a chance to produce seed. The Forest is doing trials of 

inoculating with mycorrhizae and/or seeding burn piles to find a cost-effective technique to 

prevent new bull thistle infestations in forest areas where thinning has been done.

Field bindweed

Convolvulus arvensis

Cultural control/Use of prescribed fire: Field bindweed is normally associated with old 

homesteads, roads, or other disturbed areas. Infestations that occur in these situations can be 

limited to the old disturbance by avoiding new ground disturbance in those sites, and good 

management practices to retain a good vegetative ground cover.

Mechanical/hand control: Hoeing or hand pulling may be helpful, but may also encourage the 

germination of dormant seeds or further promote vegetative growth by breaking up and spreading 

the plant (Morishita, et al., 1990).

Herbicidal control: Glyphosate is among the most effective herbicides for field bindweed. Most 

investigators recommend spraying during first bloom, when root carbohydrate reserves are at 

their lowest. Full-grown vines have a large leaf surface area to absorb the herbicide, and during 

vigorous above-ground growth, the plant is moving sugars to the roots and root buds. Dicamba 

and picloram have also been used for field bindweed control (Lyons, 1998).

Biological control: Two biocontrol agents, the bindweed gall mite (Aceria malherbae) and 

bindweed moth (Tyta luctuosa) are cleared for release in the U.S. It is unknown at this time, 

however, if related genera, such as Calystegia are susceptible to attack (CDFA, 2005). The 

bindweed moth has been released in Arizona (CDFA, 2005). 

Tonto NF Goals & Strategy: Field bindweed is a “C” species on the Tonto NF. It has not been a 

problem weed in wildland situations, but may be locally abundant on disturbed sites, or

historically disturbed sites. It has low priority for treatment, compared with other much more 

invasive weeds such as the starthistles and knapweeds. If it appears to be moving into undisturbed 
Chapter 2 – Alternatives

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 39

sites or is otherwise a local problem, it will be treated. Populations in disturbed areas will be 

treated as the opportunity arises.

Bride’s bouquet, white bietou

Dimorphotheca cuneata

Cultural control/Use of prescribed fire: Since catclaw acacia is the most abundant perennial 

plant growing in the area of the white bietou, and it is a native invasive plant, planting of other 

desirable plants after removal of the white bietou is an important part of an integrated strategy to 

remove the bietou.

Flaming can be used to kill individual plants. It is not known if they resprout from the crown.

Mechanical/hand control: Removal using hand tools is a viable option for keeping this invasive 

plant in check.

Herbicidal control: Spot treatment with backpack herbicide sprayers will target this species and 

not affect other species growing in the area. 

Biological control: There are no studies or records of biological control agents for this species.

Tonto NF Goals & Strategy: The one infestation on the Forest will be contained within an area 

of approximately 40 acres or less by working inward from the western edge. Treatment of this 

species is a low priority at this time.

Common teasel

Dipsacus fullonum

Cultural control/Use of prescribed fire: Spot burning or flaming of individual plants will 

provide effective control, when used with other tools.

Mechanical/hand control: Hand pulling or use of sharp spades are methods that work well when 

used in combination with other methods for small infestations, such as those on the Tonto NF. 

Areas that have been controlled using this method should be checked later in the year for sprouts. 

Near the end of the growing season, flowering stalks can be cut and removed from the site. If this 

is done after full bud stage, the plant does not send up more flowering stalks. 

Herbicidal control: Glyphosate and triclopyr applied before bolting have been effective control 

measures (WDNR, 2004). In riparian areas, herbicides must be labeled for aquatic use.

Biological control: There are currently no approved biological control agents for teasel.

Tonto NF Goals & Strategy: There are few teasel infestations on the Forest that are known at 

this time. Eradication is a realistic goal. Isolated infestations will be treated as they are found. A 

combination of manual removal, burning and herbicides is an effective treatment for common 

teasel (WDNR, 2004).

Russian olive

Elaeagnus angustifolia

Cultural control/Use of prescribed fire: The recommended method of control is prescribed 

burning combined with chemical control (Tu, 2003). 
Chapter 2 – Alternatives

40 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Mechanical/hand control: Saplings and sprouts can be removed with hand tools when the soil is 

moist (Tu, 2003).

Herbicidal control: Foliar and basal bark applications of glyphosate, imazapyr, and triclopyr are 

effective, especially for young trees. For mature trees, recommended application methods are cutstump, hacking and frilling (using an axe to make shallow cuts in a pattern around the entire 

trunk, then applying herbicide into the cuts), and girdling with injection of herbicide. 

Biological control: No biocontrol agents are known for this species. 

Tonto NF Goals & Strategy: Any plants found should be a high priority for treatment, as this 

species is not found on the Forest now.

Quackgrass

Elymus repens

Most of the literature about control methods for this species involves crop situations. There is 

little published material on its control in wildlands.

Cultural control/Use of prescribed fire: Burning combined with use of herbicides has been 

reported to be effective to control spread of quackgrass (Batcher, 2002). Burning on a repeated or 

biennial schedule for several years has been effective in eradicating quackgrass in some situations 

(Howe, 1995).

Mechanical/hand control: Tillage is used in cropland situations, and may be an option for 

heavily infested roadsides, when combined with other methods.

Herbicidal control: Haase reported that the use of herbicides was extremely effective in 

controlling quackgrass (Batcher, 2002). Chemicals he used were Roundup (glyphosate) and 

Fusilade (fluazifop), which is a grass-specific herbicide. He noted that spraying done early 

enough in the season (quackgrass is a cool-season grower), will not affect warm-season grasses.

Biological control: There is no information on approved biocontrol agents for quackgrass.

Tonto NF Goals & Strategy: Infestations along roads should be limited to a narrow zone, and 

then eliminated. Spot infestations away from major highways should be eradicated, if small 

(under one acre) and contained (work to remove plants from outer edges of the site toward the 

inside) if large (over one acre).

Weeping and Lehmann’s lovegrass

Eragrostis curvula & E. Lehmanniana

Cultural control/Use of prescribed fire: Prevention of more introductions is the best method to 

manage infestation of these nonnative grasses. All seed that is to be used on National Forest land 

should be inspected by a certified seed-testing lab for both of these lovegrass species. 

Mechanical/hand control: Treatments such as chopping or mowing only mimic grazing by 

animals, which lovegrasses are well-adapted to withstand.

Herbicidal control: Use of herbicides is probably the most effective method to remove extensive 

stands of lovegrasses. This must be balanced against possible damage to other vegetation and 

creation of open ground, open to colonization by other, possibly worse invasive species, or 
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EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 41

accelerated erosion. Herbicides that would control Eragrostis would also kill native grass species. 

Some off-target kill may be avoided by timing of herbicide application. Eragrostis is a coolseason grower, where most associated perennial grass species are not; however, spraying during 

the cool season could damage existing native cool-season grasses.

Biological control: There are no documented biological control agents for Eragrostis.

Tonto NF Goals & Strategy: Both Eragrostis species are “C” species on the Tonto NF. They are 

extremely widespread due to past practices of including them in revegetation seed mixes. Current 

strategy is to not introduce additional infestations by requiring all seed mixes used on the Forest, 

to be checked for presence of Eragrostis seeds. If it is accidentally introduced, immediate 

measures will be taken to eradicate new populations.

One pilot project on the Payson RD is using permitted cattle to concentrate grazing use on 

weeping lovegrass that was seeded after the Dude Fire, and encourage growth of native perennial 

grasses. Monitoring is ongoing.

Leafy spurge

Euphorbia esula

Because of its persistent nature and ability to regenerate from small pieces of root, leafy spurge is 

extremely difficult to eradicate. 

Cultural control/Use of prescribed fire: Requirement for weed-free feed for all livestock 

brought onto the National Forest would help to prevent new infestations of leafy spurge 

(Lajeunesse, et al., 1999). There are no immediate plans in this Region for such an order.

Requiring clean equipment brought in for fire suppression and other ground-disturbing activities 

will also prevent this weed from infesting the Tonto NF.

Burning prior to herbicide application allows easier visibility and better targeting of herbicide 

application, with removal of the overstory foliage.

Mechanical/hand control: Pulling by hand is ineffective, even for small patches, because of the 

extensive root system. 

Herbicidal control: Several systemic herbicides have been found to be effective if applied when 

the flowers and seeds are developing, or later in the season, when the plants are moving nutrients 

downward into the roots. Preliminary research suggests that chemical treatment in the fall 

followed by a spring burn to reduce seed germination may be an effective strategy for reducing 

leafy spurge infestations (Thunhorst & Swearingen, 2005).

Biological control: The U.S. Department of Agriculture has shown success using six natural 

enemies of leafy spurge imported from Europe. These include a stem and root-boring beetle 

(Oberea erythrocephala), four root-mining flea beetles (Aphthona spp.) and a shoot-tip gall 

midge (Spurgia esulae) (Thunhorst & Swearingen, 2005).

Sheep will graze leafy spurge; the initial effect may be an increase in stem densities by removal 

of apical dominance and stimulation of growth of root buds, but continued summer-long grazing 

over three years may reduce leafy spurge density dramatically. Effects to associated species with 

this management technique should also be considered. Grazing of this intensity should be 

reserved for densely infested problem areas only.
Chapter 2 – Alternatives

42 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

A combination of sheep grazing with use of the flea beetle Aphthona has been successful when

sheep are allowed to graze in the spring, removed during egg laying period of the beetle, and then 

put back into the pasture for grazing in the fall. 

Fall grazing by goats, followed by application of herbicides allows the herbicide to work on 

newly growing sprouts of the plant that have been stimulated to grow by the grazing (Lajeunesse,

et al., 1999). 

Tonto NF Goals & Strategy: Any individuals or small infestations found are a very high priority 

for treatment, using herbicides.

Spreading wallflower

Erysimum repandum

Cultural control/Use of prescribed fire: This plant is adapted to invading disturbed sites in full 

sun; thus cultural vegetation management techniques that increase ground cover of native plants 

will serve to help prevent its invasion. There is no information on whether seeds of this plant are 

resistant to fire. 

Mechanical/hand control: Small infestations of this small annual mustard can be easily handpulled. This should be done before seed set so that disturbance of the plant does not scatter seed.

Herbicidal control: A variety of herbicides will control this plant, but must be applied in the 

short time between when it germinates and when it flowers, in the winter/early spring.

Biological control: There are no known biocontrol agents for this plant.

Tonto NF Goals and Strategy: Spreading wallflower is common on the Agua Fria National 

Monument, which lies on the western boundary of the Tonto NF. The Tonto NF’s portion of the 

grassland should be managed for adequate groundcover to prevent invasion. Prescribed burning 

and grazing practices should be carefully applied to maintain native groundcover. Spreading 

wallflower is an “A” species on the Tonto NF.

Sweet resinbush

Euryops subcarnosus ssp. vulgaris

Cultural control/Use of prescribed fire: Prescribed burning has been tried to treat sweet 

resinbush. Burns were unsuccessful due to lack of fuels to carry the fire (Schalau, 2001). 

Mechanical/hand control: Hand grubbing of very small infestations on the Tonto NF has 

completely controlled some of them. Hand removal of resinbush at Sabino Canyon has been 

effective at reducing the population to very low levels (Schewel, 2007). Manual removal of the 

Tonto NF’s infestation near the Miami cemetery often results in proliferation of seedlings the 

following season.

Herbicidal control: Recent aerial application of hexazinone to an infestation near Safford, 

Arizona has achieved some success (McReynolds, 2005). An infestation at the Santa Rita 

Experimental Range was treated with a combination of mechanical and herbicide treatments that 

greatly reduced sweet resinbush species composition and density (Howery, et al., 2003). An 

infestation at Cottonwood has been treated for five consecutive years with herbicides, and the 

population is declining. 
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EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 43

Biological control: There are no biocontrol agents approved for use on sweet resinbush.

Tonto NF Goals & Strategy: Our goal is eradication for all infestations, using a combination of 

manual removal and herbicides. Sprouting of seedlings after either manual or herbicidal removal 

of mature plants is common. Monitoring and follow-up treatments are necessary for any type of 

resinbush treatment.

Dyer’s woad

Isatis tinctoria

Cultural control/Use of prescribed fire: Prevention and early detection are very important, 

especially since this plant spreads very rapidly once it infests a site.

Mechanical/hand control: Mowing is not effective, since dyer’s woad sprouts from the crown. 

Hand pulling may work well to reduce small infestations – it is most easily pulled after bolting 

and before seed set. It is necessary to follow up for several years, due to the seedbank in the soil. 

Longevity of seed in the soil is unclear, but experience has shown it is at least several years 

(CDFA, 2005). It is most easily visible before seed set, with distinctive bright yellow flowers. 

There is only a four-week window between flowering and seed set, so it is critical to have crews 

available at that specific time. The fleshy taproot must be removed, or plants will resprout. 

Pulling should be scheduled for two to three times each season, for several years.

Herbicidal control: Herbicides such as metsulfuron are economical, if used during the seedling 

to rosette stages. On roadsides, chlorsulfuron may be applied pre-emergence or post-emergence to 

seedlings and rosettes (CDFA, 2005). 

Biological control: The native rust Puccinia thlaspeos is a recently discovered biocontrol agent 

(CDFA, 2005). This is a non-specific pathogen, but has been distributed to various states with 

dyer’s woad. The rust is systemic in its activity. Severely infected plants produce few to no seeds; 

seedlings and rosettes are often killed.

Tonto NF Goals & Strategy: Our strategy is prevention, since this weed is currently not known 

to be on the Tonto NF. Dyer’s woad is an “A” species, so Forest personnel should be trained to 

recognize this plant, immediately report it and eradicate it when located. 

Kochia

Kochia scoparia

Cultural control/Use of prescribed fire: Kochia is a common invader of disturbed sites. 

Preventive measures include requirement of weed-free seed (inspected for the Tonto NF list, 

which includes Kochia), inspection of newly-disturbed sites such as road construction sites, and 

early removal. 

Mechanical/hand control: Tillage of infested roadsides is an effective tool for treatment (Hager, 

2001). Cutting plants before flower production is effective in reducing seed production. 

Herbicidal control: Application of the herbicides glyphosate or dicamba is a recommended 

control method (Hager, 2001). There are many biotypes of Kochia resistant to triazine, 2,4-D or 

dicamba. If herbicides are used, different ones should be used each time in any given location. 

Biological control: There are no known biological control agents for use on Kochia.
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44 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Tonto NF Goals & Strategy: Kochia is rare on the Tonto NF. Our goal is eradication. 

Oxeye daisy

Leucanthemum vulgare

Cultural control/Use of prescribed fire: Areas that are cultivated should be revegetated with 

desirable native seed. Deep mulching (3 to 4 inches deep) with rice straw has eradicated oxeye 

infestations in California. This is a very intensive treatment - one straw bale covers approximately 

100 square feet. Since bright seedheads can attract flower picking, it is necessary to post signs 

where people may be gathering the flowers. The seedheads shed seeds easily. 

This plant is commonly sold as an ornamental for higher elevation gardens. Addition of this 

species to the Arizona Department of Agriculture Prohibited weed list would provide legislation 

to prevent it from being imported and sold in the state. 

Mechanical/hand control: Hand removal can be effective, if the population is small (less than 

0.25 acre). Shallow cultivation (less than six inches) only spreads roots. Deeper cultivation 

exposes roots to desiccation. Subsequent shallow cultivations can be used to kill seedlings. 

Cultivating large areas of soil leaves seedlings open to invasion by other invasive species. 

Herbicidal control: Picloram, imazapyr, sulfometuron methyl, and dicamba are effective at label 

concentration when applied in the early flowering stages. These herbicides persist in the soil. 

Oxeye daisy is moderately resistant to 2,4-D and dicamba, and these herbicides can damage nontarget species (Alvarez, n.d.).

Biological control: As of 1998, no biological control agents had been approved for oxeye daisy 

(Olson & Wallander, 1999).

Tonto NF Goals & Strategy: Complete eradication of a large population can be difficult because 

of the small size of the plant, abundant seed production, and longevity of seed in the soil. At this 

time, no large infestations have been documented on the Tonto NF; therefore, priority should be 

given to eradicating small infestations.

Dalmatian toadflax, Yellow toadflax

Linaria dalmatica, Linaria vulgaris

Cultural control/Use of prescribed fire: Education for identification of toadflax and routine 

requirement for clean equipment for wildfires and construction projects will help prevent 

infestations brought in from outside the National Forest.

Mechanical/hand control: Large, deep root systems of toadflax do not make it a candidate for 

burning or mowing. Hand pulling before seed set each year can be an effective control method. 

This must be repeated for up to ten years to completely eradicate an infestation (Carpenter & 

Murray, 1998). 

Herbicidal control: Herbicide treatment is an important tool for controlling toadflax. Herbicides 

should be applied during flowering, when carbohydrate reserves in the roots are at their lowest 

(Carpenter & Murray, 1998). The herbicides glyphosate, dicamba, and picloram are effective for 

controlling toadflax.

Biological control: Six insect species have been approved by the USDA-APHIS-PPQ for release 

as biological control agents for both toadflax species. These are: Brachypterolus pulicarius, a 
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EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 45

shoot and flower-feeding beetle, Calophasia lunula, a defoliating moth, Eteobalea serratella and 

E. intermediella, small root-boring moths, and Gymnaetron antirrhini, a seed-eating weevil 

(Carpenter & Murray, 1998). APHIS has found Mecinus janthinus, the stem-mining weevil to be 

very successful in the Pacific Northwest. This agent has been released in Arizona for control of 

Dalmatian toadflax. The Coconino NF is currently experiencing some success with use of the 

stem-mining weevil.

Grazing does not control either species of toadflax, as they are not palatable (Carpenter & 

Murray, 1998).

Tonto NF Goals & Strategy: Our goal is eradication. Toadflax populations are mostly limited in

size and extent at this time. Most known sites are in locations where herbicides can be used, such 

as in the median of State Route 87. This site is being treated with both RoundUp and Milestone 

herbicides. RoundUp appears very effective at treating this species. Manual removal of the 

Dalmatian toadflax infestation at the Payson District Ranger Station has been ongoing for many 

years and has been largely ineffective. More recent use of herbicides containing glyphosate and 

aminopyralid have been much more successful in reducing density of this infestation.

Purple loosestrife

Lythrum salicaria

Cultural control/Use of prescribed fire: Prevention and early detection are good tools, since 

this species is very visible and distinctive. River rangers should be trained to recognize this weed.

Mechanical/hand control: Hand-removal is recommended for small populations and isolated 

stems. The entire rootstock must be pulled out since regeneration from root fragments is possible 

(Bende, 2001). 

Herbicidal control: Broadleaf chemicals are effective in treating this species. Spraying should be 

done after peak bloom. It is critical that this be followed up the same growing season and for 

several years since some plants will be missed, new seedlings may sprout from the seed bank, and 

a few plants may survive the herbicide application (Bender, 2001). Glyphosate and dicamba are 

recommended (Bender, 2001). 

Biological control: Four insects have been approved and are being used by APHIS for control of 

purple loosestrife: a root-mining beetle (Hylobius transversovittatus), a flower-feeding beetle 

(Nanophytes marmoratus), and two leaf-eating weevils (Galerucella calmariensis and G. pusilla) 

(Crisp, 2000).

Tonto NF Goals & Strategy: Purple loosestrife is an “A” species on the Tonto NF. Our goal is 

prevention or eradication. Large populations extending over three acres or more are difficult if 

not impossible to completely eradicate using presently known methods (Bender, 2001); therefore 

any new sitings are a high priority for eradication. 

Yellow sweetclover

Melilotus officinalis

Cultural control/Use of prescribed fire: Seed mixes should be checked for presence of 

sweetclover seed. 

Mechanical/hand control: Pulling or grubbing with hand tools will remove this species.
Chapter 2 – Alternatives

46 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Herbicidal control: Herbicides that control broadleaf species could work on sweetclover. Its use 

as a crop or cover plant for many years has probably lent it resistance to some herbicides.

Biological control: As this is a crop plant, there are no biological controls being developed for 

treatment.

Tonto NF Goals & Strategy: This plant is not a priority weed to control; only locally important

infestations will be treated. Most effort will be to prevent introduction of more sweetclover in 

seed mixes and control it when the opportunity arises.

Oleander

Nerium oleander

Cultural control/Use of prescribed fire: Burning is definitely not recommended, as the smoke 

from burning oleander is toxic.

Mechanical/hand control: Plants may be mechanically removed, if care is taken to remove the 

crown.

Herbicidal control: A combination of mechanical trimming plus use of herbicide, either as a 

spray or cut stump for larger plants is probably the most effective control method. Heavy 

trimming over a period of time would serve to reduce root carbohydrate reserves and also reduce 

the amount of herbicide that is required.

Biological control: There are no known biocontrol agents that control oleander. Its common use 

as an ornamental plant will preclude development of this type of control.

Tonto NF Goals & Strategy: Our goal is eradication.

Globe chamomile

Oncosiphon piluliferum

Cultural control/Use of prescribed fire: It may be possible to discourage use of this plant as an 

ornamental, which seems to be how it has been introduced and subsequently naturalized into 

wildlands. There is very limited literature on control methods for globe chamomile. It grows 

densely along rights-of-way, lending it to control by burning or use of broad-leaf specific 

herbicides.

Mechanical/hand control: Globe chamomile normally grows in dense patches for long 

distances. Pulling would not be effective unless very small patches were found. Tilling along 

roadsides may be effective, but could also prepare the ground for infestation by other invasive 

weeds.

Herbicidal control: There is limited information on specific herbicides that control globe 

chamomile in the U.S. Various broadleaf herbicides would probably be effective. This plant is a 

pest in Western Australia, where herbicide trials have been conducted (Rayner, 2009).

Biological control: There is no information on biological control agents for globe chamomile.

Tonto NF Goals & Strategy: Our goal is to contain, with eradication possible. This weed is 

newly discovered, but has spread through the town of Cave Creek and along I-17 north to New 
Chapter 2 – Alternatives

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 47

River extremely rapidly. In the near future it will be a serious invasive threat to the Tonto NF’s 

southwest corner.

Jerusalem thorn

Parkinsonia aculeata

Cultural control/Use of prescribed fire: Jerusalem thorn appears to be well-adapted to fire, as a 

one or two-tree planting grew quickly to a few acres after the Cave Creek Complex Fire burned 

through a recreation residence where a single tree had been planted. As the plant usually grows in 

the Sonoran desert, fire is not a management option. 

Mechanical/hand control: Very young trees may be removed using a tool called a weed wrench, 

which levers the tree out of the soil. Saplings quickly develop deep root systems, so this is not an 

option for trees more than one or two years old. 

Herbicidal control: Jerusalem thorn is a good candidate for basal bark or cut stump herbicide 

control. This technique has been used successfully by Dr. Ed Northam in field trials (Northam, 

2009).

Biological control: There are no known biocontrol agents for this species.

Tonto NF Goals and Strategy: Our goal is to eradicate this species on the Forest. This will be a 

continuing project, as there is a seedbank in the greater Phoenix area that continually disperses to 

the north. However, presence of this plant is uncommon and it could be completely removed from 

the Forest.

Scotch thistle

Onopordum acanthium

Cultural control/Use of prescribed fire: Good range management for a groundcover of 

perennial grasses provides competition that can stress thistles. 

Mechanical/hand control: As with bull thistle, any method that severs the root and removes the 

flower/seed head will kill the plant and prevent it from reproducing or sprouting. 

Herbicidal control: Aminopyralid, clopyralid, dicamba, and picloram are recommended 

herbicides for control of Scotch, bull, and musk thistles in the rosette stage. Metsulfuron and 

chlorsulfuron are most effective when plants have begun to bolt.

Biological control: The seedhead weevil Rhinocyllus conicus has been used in neighboring states 

to control a variety of introduced invasive thistles, including Scotch thistle. It is not host-specific, 

and will also feed on native thistles (Beck, 1999). 

Tonto NF Goals & Strategy: Maintaining properly-grazed pastures is key to preventing 

infestations of this and other thistles from invading many acres of rangeland. Our goal is 

eradication upon discovery of new infestations. 

African rue

Peganum harmala

Cultural control/Use of prescribed fire: Prevention by maintaining healthy native vegetation is 

the best cultural control method. Burning is not an option, since it sprouts vigorously following 

fire.
Chapter 2 – Alternatives

48 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Mechanical/hand control: Hand pulling of small infestations can be effective, if it is repeated 

multiple times each year. Cultivation and mowing are not options, as the plant sprouts from its 

crown following disturbance. 

Herbicidal control: Glyphosate and metsulfuron have been found to be effective herbicides for 

control of African rue (Peachey, 2007). Triclopyr or triclopyr + imazapyr were found to be 80

percent effective in New Mexico (Davison & Wargo, 2001). The Extension Service in Nevada 

recommends that any control effort needs to be planned for a minimum of 3 years and multiple 

applications to kill African rue (Davison & Wargo, 2001).

Biological control: There are no known biological control agents for African rue. Grazing is not 

an option, as this plant is poisonous to most species. 

Tonto NF Goals & Strategy: Our goal is prevention. African rue is an “A” species, meaning any 

new infestation is high priority for eradication. 

Buffelgrass

Pennisetum ciliare

Cultural control/Use of prescribed fire: Burning stimulates growth of buffelgrass, so prescribed 

burning is not recommended. Burning may be a good tool to use in combination with use of 

herbicides, to remove the bulk of decadent growth that could prevent good herbicide contact with 

growing leaves.

Mechanical/hand control: Most mechanical/hand control methods simulate grazing, a treatment 

to which buffelgrass is well adapted. A group in southern Arizona has had much success with 

removal by digging the plants out by the root and removing them, being careful to bag and 

remove all of the seeds and flowers.

Herbicidal control: Herbicides are an option, but buffelgrass has a history of developing 

resistance to herbicides (ADOT, 2005). Glyphosate-based herbicides have proven very effective.

Biological control: There is no known biological control agent for either buffelgrass or fountain 

grass.

Tonto NF Goals & Strategy: This species will be managed with a containment strategy, 

combined with working along rights-of-way to eliminate it. The Forest has been using 

Department of Correction’s crews, volunteers and force accounts to manually remove a large

infestation north of Gonzales Pass, on the Mesa RD. The infestation is spreading rapidly despite 

this effort. Herbicides will be used in the interest of cost-effectiveness, with an eye to preventing 

resistance by varying herbicide active ingredient that is used.

Fountain grass

Pennisetum setaceum

Cultural control/Use of prescribed fire: As with buffelgrass, burning is not recommended, 

except in combination with use of herbicides.

Mechanical/hand control: Small infestations may be managed by uprooting plants by hand and 

destroying the inflorescences in order to prevent seed dispersal. Removal by hand may need to be 

repeated several times per year. Fountain grass is much more difficult to remove by hand than is 

buffelgrass.
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EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 49

Herbicidal control: The long-lived seeds of fountain grass make its control extremely difficult. 

Extensive infestations of fountain grass are probably best controlled with the help of herbicides, 

especially those with some systemic activity. Pre-emergent herbicides are necessary to control 

plants in areas with high seedling recruitment (Lovich, undated).

Biological control: There is no known biological control agent for either Pennisetum species.

Tonto NF Goals & Strategy: The management strategy for this species is the same as for 

buffelgrass. Manual removal is fairly effective, but expensive. Herbicide application on some 

sites along state highways resulted only in setting back mature plants for a year. The herbicide 

used was not a sufficiently concentrated solution of glyphosate. A combination of manual 

removal and/or burning, followed up with herbicides is an effective treatment method.

Karoo bush

Pentzia incana

One karoo bush infestation on the Forest is limited to one disturbed area north of Oak Flat. The 

other is in association with sweet resinbush near Miami. It is unlikely infestations will occur 

elsewhere on the Forest, as both populations were planted long ago and no others have been 

identified.

Cultural control/Use of prescribed fire: Good land management practices that limit bare 

ground in that area will prevent spread of the existing infestation. 

Vegetation is sparse in the area where Pentzia grows, so that flaming individual plants during the 

non-fire season would not pose a hazard to other vegetation. It is not known if Pentzia sprouts 

from roots after it is burned.

Mechanical/hand control: Our existing infestations can be treated by hand pulling or grubbing 

with hand tools. 

Herbicidal control: Spot herbicide applications using broadleaf herbicides would probably be 

effective.

Biological control: There is no known biological control agent for karoo bush.

Tonto NF Goals & Strategy: This plant is not very invasive. The only two documented 

infestations of Karoo bush on the Tonto NF are fairly small. They have hardly spread from where 

they were planted 70 years ago. Our goal is to contain populations to the small area where they 

now grow. These sites are a low priority for treatment.

Japanese knotweed

Polygonum cuspidatum

Cultural control/Use of prescribed fire: Education of nursery dealers and discouraging use of 

this plant as an ornamental would prevent infestations that would most likely come from 

naturalized plantings on private land. 

Mechanical/hand control: Very small infestations can be controlled by thorough grubbing of all

rhizomes and roots. The entire root system must be removed, since resprouting can occur from 

long rhizomes. A Pulaski or pick-mattock is useful for digging out mature clumps, while hand 

pulling works well for small plants in moist areas. The plant material should be removed, dried 
Chapter 2 – Alternatives

50 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

and burned, if possible. Mowing or cutting plant shoots is ineffective alone. However, mowing 

followed by herbicide treatments will provide some control (CDFA, 2005).

Herbicidal control: Established infestations are better controlled with either cut-stem or foliarapplied herbicides. Glyphosate (may need aquatic formulation, since this species is most likely to 

be found in riparian situations), or triclopyr have been found to kill Japanese knotweed. Imazapyr 

and dicamba are other herbicides that are effective.

Biological control: There are currently no registered biological control agents for use on 

Japanese knotweed. Grazing may be an effective strategy to prevent establishment. It has been 

observed that Japanese knotweed will not establish where grazing pressure is high; however, 

heavy grazing may also select for other undesirable weedy species (CDFA, 2005).

Tonto NF Goals & Strategy: This species will be eradicated where found. Prevention of 

infestations will be accomplished by education of nurseries and the public on northern ranger 

districts, where this plant would grow readily. 

Sulfur cinquefoil

Potentilla recta

Cultural control/Use of prescribed fire: Prescribed burning alone is not recommended, but this 

could be effective when used in combination with herbicides and seeding of native species. 

Seeding with native perennial grasses helps to stress sulfur cinquefoil in an integrated vegetation 

management program that also uses other tools.

Mechanical/hand control: Manual control may remove small infestations, if care is taken to

completely remove root crowns (Endress & Parks, 2004). Mowing is not an effective control 

method (Endress & Parks, 2004).

Herbicidal control: Selective herbicides are the most effective means to control large 

infestations. On dry land, picloram is preferred because its residual activity will inhibit new plants 

from establishing (Endress & Parks, 2004). 

Biological control: There are no available biocontrol agents for sulfur cinquefoil. 

Tonto NF Goals & Strategy: Sulfur cinquefoil is an “A” species – eradication of new 

infestations is our goal.

Pyracantha

Pyracantha sp.

Cultural control/Use of prescribed fire: Pyracantha seems to move into riparian communities 

from nearby ornamental plantings. The best way to prevent infestation is to prevent special use 

permittees with homes on the National Forest from planting it. Education of urban interface 

homeowners may also help prevent new infestations.

Mechanical/hand control: Pyracantha can be uprooted using a weed wrench or other tool that 

uses leverage to pull the roots out of the ground.

Herbicidal control: Some broadleaf herbicides would probably be effective to remove 

pyracantha.
Chapter 2 – Alternatives

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 51

Biological control: There are no available biocontrol agents for pyracantha.

Tonto NF Goals & Strategy: Our goal is eradication. There are very few known infestations.

African sumac

Rhus lancea

Cultural control/Use of prescribed fire: As is the case with pyracantha, African sumac seems to 

move into riparian communities from nearby ornamental plantings. The best way to prevent 

infestation is to prevent special use permittees with homes on the National Forest from planting it. 

Education of urban interface homeowners may also help prevent new infestations.

Mechanical/hand control: Saplings and small trees can be pulled with a weed wrench or similar 

tool. Even small saplings have deep taproots and can be very difficult to hand pull.

Herbicidal control: There is very little information on herbicides that would be effective for 

control of African sumac. Various broadleaf herbicides may need to be tested to find the most 

effective one.

Biological control: There are no available biocontrol agents for African sumac.

Tonto NF Goals & Strategy: Our goal is eradication. There are currently few known 

infestations.

Russian thistle

Salsola kali, Salsola tragus

Cultural control/Use of prescribed fire: Practices that will prevent large infestations include 

using clean fill dirt for projects, cleaning equipment for fire suppression and ground-disturbing 

projects, and inspection of staging areas and other work sites.

Mechanical/hand control: Small infestations can be hand pulled. 

Herbicidal control: Control is usually with non-selective or broadleaf herbicides at the seedling 

stage. It must be repeated often through the summer, as new plants continually germinate.

Biological control: Research into a potential biological control agent for S. tragus, Salsola rust 

(Uromyces salsolae), has been conducted. Salsola rust appears to attack only S. tragus plants; it is 

not a threat to crops and has not yet been found on native plants (Hasan, et al., 2001).

Tonto NF Goals & Strategy: Our goal is to limit this plant to disturbed rights-of-way, and 

ensuring that maturing revegetation replaces these populations over time. When it is found early 

in new construction sites, it should be eradicated. 

Mediterranean sage

Salvia aethiopis

Cultural control/Use of prescribed fire: Maintenance of a good cover of perennial plants will 

slow spread of this plant once it has established.

Mechanical/hand control: Small infestations can be dug out if the root is cut 2 to 3 inches below 

the ground to prevent sprouting (CDFA, 2005). Mowing is not an effective tool.
Chapter 2 – Alternatives

52 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Herbicidal control: Dicamba has been reported to control Mediterranean sage. Plants should be 

treated after bolting but before seed are produced. The hairy nature of the leaf surface may reduce 

herbicide efficacy and a surfactant should be included (CDFA, 2005).

Biological control: Some biocontrol agents have been used in the northwest: the European crown 

boring weevil, Phrydiuchus tau, was introduced in 1969, and populations are established in 

Idaho, Oregon, and California (Graham & Johnson, 2004). Seed production was slowed and 

population density of Mediterranean sage was reduced, but the weevil populations were slow to 

establish, and they alone will not control the spread of Mediterranean sage. Another species, 

Stagmatophora pomposella has been tested, with limited success. The caterpillar stage of the 

moth is effective only on the first-year rosette, and there is no impact on mature plants (WA

State, 1999).

Tonto NF Goals & Strategy: This plant is unknown on the Tonto NF at this time. Education on 

identification of this species will help us to practice early detection and eradicate any new 

infestations as they appear. 

Mediterranean grass

Schismus arabicus, S. barbatus

Cultural control/Use of prescribed fire: Fire promotes growth of Schismus species. At 

elevations higher than the Sonoran Desert, encouragement of a good ground cover of perennial 

grasses or soil crust species would serve to limit spread of Schismus species.

Mechanical/hand control: Manual control is impractical, since the plants are so small. Removal 

of the extensive mat of roots near the surface results in significant surface disturbance during 

manual removal, which promotes additional weed establishment, and ultimately improves the site 

for Schismus. 

Herbicidal control: Herbicides can provide some control, but the very small leaf and stem size 

do not absorb much herbicide, and often non-target species are affected more. 

Biological control: As with mechanical treatments, removal by grazing animals at moderate to 

intense levels only tends to increase the relative presence of alien annual grasses. A black smut, 

Ustilago aegyptica, has been noted on Schismus. It destroys the spikelets. It is not abundant 

enough to actually provide any control of this annual grass, but it presents possibilities for further 

research.

Tonto NF Goals & Strategy: This is a “C” species. There may be some strategic locations where 

the Forest wishes to contain this species. Grazing focused during early spring or selective 

herbicides may help control this annual grass.

Wild mustard

Sinapis arvensis

Cultural control/Use of prescribed fire: Routine requirement for clean equipment for wildfires 

and construction projects, and testing of seed for revegetation projects will help prevent 

infestations brought in from outside the National Forest.

Mechanical/hand control: Pulling small infestations before seed set is an effective treatment.
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EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 53

Herbicidal control: Wild mustard is most commonly treated as a crop weed; thus it has become 

resistant to some herbicides. Those herbicides recommended for control are the sulfonylurea 

herbicides such as chlorsulfuron, sulfometuron methyl, and metsulfuron methyl. 

Biological control: There are no known biological control agents for wild mustard. Their 

development is unlikely, since wild mustard is closely related to many crop plants.

Tonto NF Goals & Strategy: Our goal is to limit this plant to the immediate roadside and work 

to eradicate it from wildlands. Its main habitat is agricultural sites on private lands.

Saltcedar

Tamarix parviflora, Tamarix chinensis, T. ramosissima

Management of saltcedar (also known as tamarisk or tamarix) requires a long-term commitment 

to prevent reinfestation. Removal or destruction of the root crown is critical in saltcedar control. 

A variety of methods have been used in the management of saltcedar, including mechanical, 

chemical, and biological. The most effective management probably involves a combination of 

these. 

Cultural control/Use of prescribed fire: Fire has been used with some success with saltcedar; 

however, resprouting normally occurs after fire since it is fire-adapted. Flooding can be used to 

control saltcedar if root crowns remain submerged for at least three months (Muzika & 

Swearingen, 2005b).

Mechanical/hand control: Mechanical techniques include hand-pulling, digging, root-cutting, 

use of weed eaters, axes, machetes, and bulldozers. Removal by hand tools is generally 

recommended for small infestations of saplings under one-inch basal diameter. Root-cutting and 

bulldozing may be effective but are costly, labor intensive, and may cause extensive damage to 

soils and lead to resprouting, or invasion by other undesirable invasive species. 

Herbicidal control: For extensive infestations of saltcedar, chemical control has been shown to 

be the most effective method. Cautious use of herbicides aids in restoration of saltcedar-infested 

sites by allowing repopulation by native plant species. Systemic herbicides are recommended for 

saltcedar management and application methods include foliar sprays, cut stump treatments, basal 

bark treatments, and aerial sprays. Because tamarisk (saltcedar) usually grows in or adjacent to 

streams, wetlands, and other waterways; it is important to use products registered for aquatic 

application.

Biological control: No biological control of saltcedar is proposed. Various biocontrol agents are 

being used in other states; these agents may find their own way to saltcedar infestations in 

Arizona. In 2005, the U.S. Fish and Wildlife Service agreed that releases of the saltcedar leaf 

beetle Diorhabda elongata could be made at sites in Texas, New Mexico, Colorado, Wyoming, 

Utah, Nevada, and California, with the proviso that releases were located more than 200 miles 

from where Southwestern willow flycatchers nest in saltcedar trees, and certain other conditions

(USDA/APHIS, 2005).

Tonto NF Goals & Strategy: Management goals are to contain the infestation on the upper Salt 

River to the main channel, limiting its spread up tributaries; over the long term to eradicate 

saltcedar from the Verde River, and remove it from the many small tributaries across the Forest 

where it grows in small populations. Preserves along the reach of Cave Creek below the National 

Forest are being treated intensively for eradication of saltcedar. Saltcedar is rare along upper 
Chapter 2 – Alternatives

54 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Cave Creek and does not grow in dense stands on the lower part of Cave Creek on the National 

Forest. Removal efforts on County and private preserves downstream will be futile unless the 

National Forest also acts to control our populations. Our long-term goal is to eradicate saltcedar

from the Cave Creek drainage and its tributaries. Achieving this goal will require continual 

maintenance, as saltcedar seed sources are common throughout central Arizona.

Southwestern willow flycatchers currently use the thickets of saltcedar at the inflows of the Salt 

River and Tonto Creek into Roosevelt Lake. Rising lake levels as a result of the raising of 

Roosevelt Dam may cause these thickets to die off, or cause them to shift upstream. It is doubtful

if native riparian tree species could survive with the greatly fluctuating water levels that result 

from operations of the dam. Thus, the Tonto NF does not propose to conduct saltcedar control 

projects within the flood pool of Roosevelt Lake, or below 2,151 feet in elevation around the 

perimeter of the lake. Management of these saltcedar populations will be to limit their spread 

upstream beyond the area influenced by changing lake levels. 

The Tonto NF will refrain from removing saltcedar from the Gleason Flat area on the Upper Salt 

River, a site considered suitable for nesting Southwestern willow flycatchers (Beatty, 2009). The 

upstream end of Horseshoe Reservoir is also habitat for the Southwestern willow flycatcher. With 

radically fluctuating lake levels, saltcedar has become established in the same area as cottonwood 

and willow, and in recent years the Southwestern willow flycatcher has nested in saltcedar (Todd 

Willard, 2006). In the long term, the flycatcher may possibly benefit from removal of saltcedar, if 

a sustainable cottonwood/willow vegetation community is still possible, due to the high 

flammability of saltcedar thickets. Since flycatchers are nesting in saltcedar that has become 

established within the flood pool of Horseshoe Lake, this project does not propose control of 

saltcedar within that flood pool or below 2,026 feet in elevation around the perimeter of the lake.

As with the Salt River saltcedar infestations, management of saltcedar on the Verde River will be 

to limit its spread upstream beyond the area influenced by changing lake levels. 

Siberian elm

Ulmus pumila

Cultural control/Use of prescribed fire: Fire will kill seedlings, but not mature trees (Wieseler, 

2005). 

Mechanical/hand control: Seedlings can be controlled mechanically or by hand. Shallow 

girdling will starve the tree for food from the top to the roots. The tree will die slowly over a 

period of years. If the tree is girdled too deeply, cutting into the xylem, the top of the tree will die 

and the roots will react by producing numerous sprouts (Wieseler, 2005). 

Herbicidal control: Larger trees are better controlled using cut stump herbicide applications 

(Wieseler, 2005). Glyphosate and triclopyr are recommended (Wieseler, 2005).

Biological control: There are no methods for biological control of Siberian elm.

Tonto NF Goals & Strategy: This is an “A” species – any new infestation should be treated 

aggressively.
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EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 55

Periwinkle

Vinca major

Cultural control/Use of prescribed fire: As periwinkle acts to crowd out native riparian species, 

it should be controlled and replaced with native plants where feasible.

Mechanical/hand control: Hand removal is labor-intensive, but can be effective if all roots and 

stolons are carefully removed. This is best accomplished by working from the outer edges, 

pulling the periwinkle back in on itself to prevent further spread between removal sessions. This 

also allows native vegetation to recolonize where periwinkle has been removed. This removal 

method requires many repeated treatments in order to permanently remove the Vinca. Mowing or 

cutting is not recommended, as it encourages sprouting.

Herbicidal control: Glyphosate works well if plants are first cut then sprayed immediately 

afterward. Cutting with a weed whip breaks through the waxy cuticle, allowing better penetration 

of the herbicide. In Ramsey Canyon, a five percent glyphosate solution provided 100 percent 

control. A surfactant is recommended (Drewitz, undated).

Biological control: Biocontrol agents have not been tested for Vinca.

Tonto NF Goals & Strategy: This plant is not extremely invasive, and it does not occur in many 

locations on the Tonto NF. Strategy is to remove it where opportunities exist, normally on or near 

old homesteads. Time should not be spent controlling this species, unless it is spreading to 

undisturbed lands or replacing native riparian species. Where Vinca populations are so extensive 

that removal would leave areas of bare ground, vegetation will be treated with herbicide while 

leaving roots intact to hold the soil in place. Revegetate the site as practicable, or include erosion 

control structures/devices as part of the project if needed.

Biocontrol Agents Proposed for use

Table 2. Biocontrol agents’ names and target species

Scientific 

Name of 

Biocontrol 

Agent

Common 

Name of 

Biocontrol 

Agent

Target 

Species 

Common 

Name

Target 

Species 

Scientific 

Name

Notes

Agapeta 

zoegana

moth Spotted 

knapweed

Centaurea 

biebersteinii

First released in the United States in 

1984. Has been released in Arizona, 

California, Colorado, Idaho, 

Minnesota, Montana, Nebraska, 

Nevada, North Dakota, Oregon, South 

Dakota, Utah, Washington, Wisconsin, 

and Wyoming. The moth has 

established in these states.

Determined to be host-specific to 

mainly Centaurea stoebe and a few 

closely related Centaurea species 

(Muller, et al., undated).
Chapter 2 – Alternatives

56 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Scientific 

Name of 

Biocontrol 

Agent

Common 

Name of 

Biocontrol 

Agent

Target 

Species 

Common 

Name

Target 

Species 

Scientific 

Name

Notes

Bangasternu

s fausti

Flower 

weevil

Spotted 

knapweed, 

diffuse 

knapweed

Centaurea 

biebersteinii, 

Centaurea 

diffusa

First released in the United States in 

1991. The weevil has been released in 

California, Colorado, Idaho, 

Minnesota, Montana (established), 

Nebraska (established), Oregon 

(established), South Dakota, 

Washington, and Wyoming. Also

released in Arizona. Studies conducted 

on host specificity determined that this 

weevil feeds only on a small number of 

species restricted to the genus 

Centaurea (Maddox and Sobhian, 

1987).

Bangasternu

s orientalis

Yellow 

starthistle 

bud weevil

Yellow and 

Malta 

starthistles

Centaurea 

solstitialis, 

C. melitensis

Releases were made in California. 

Washington. Idaho, and Oregon in 

1985 and it became established in all 

states in 1989. Widely distributed in 

starthistle-infested areas of the western 

United States, particularly California, 

Oregon, Washington and Idaho 

(Wilson, et al., 2003). Studies 

conducted on host specificity 

determined that this weevil feeds only 

on a small number of species restricted 

to the genus Centaurea (Maddox and 

Sobhian, 1987).

Cyphocleonu

s achates

weevil Spotted 

knapweed,

diffuse 

knapweed

Centaurea 

biebersteinii,

Centaurea 

diffusa

First released in the United States in 

1987. Has been released in Arizona, 

California, Colorado, Idaho, 

Minnesota, Montana, Nebraska, 

Nevada, Oregon, South Dakota, Utah, 

Washington, and Wyoming as part of a 

program to control spotted and diffuse 

knapweed. Populations are established 

in Colorado, Montana, and Wyoming, 

and individuals have been recovered in 

Oregon. It has also become established 

in Minnesota. The final report on 

testing of this agent for host specificity 

determined that C. achates is restricted 

to a few species of closely related 

Centaurea and all possible hosts that 

occur in North America are introduced 

weeds (Stinson, 1987).
Chapter 2 – Alternatives

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 57

Scientific 

Name of 

Biocontrol 

Agent

Common 

Name of 

Biocontrol 

Agent

Target 

Species 

Common 

Name

Target 

Species 

Scientific 

Name

Notes

Eustenopus 

villosus

Yellow 

starthistle 

hairy weevil

Yellow and 

Malta 

starthistles

Centaurea 

solstitialis, 

C. melitensis

Widely distributed in starthistleinfested areas of the western United 

States, particularly California, Oregon, 

Washington, and Idaho. (Wilson, et al.,

2003), Introduced on Coconino NF 

2008, 2009.

Larinus 

minutus

weevil Spotted 

knapweed, 

diffuse 

knapweed

Centaurea 

biebersteinii, 

Centaurea 

diffusa

Cleared and first released in the United 

States in 1991. The weevil has been 

released in Arizona, California, 

Colorado, Idaho, Minnesota, Montana 

(established), Nebraska, Oregon 

(established), South Dakota, Utah, 

Washington (established), and 

Wyoming (estab.). L.minutus has been 

demonstrated to have a limited host 

range with a preference for Centaurea 

species in the subgenera which occur 

naturally in Europe (Jordan, 1995). A 

study in 1990 determined that L. 

minutus would be an effective control 

for diffuse and spotted knapweed, 

would be target-specific, and would 

have no adverse effects on other 

organisms or the environment (Groppe, 

1990). 

Larinus 

obtusus

weevil Spotted 

knapweed, 

diffuse 

knapweed

Centaurea 

biebersteinii, 

Centaurea 

diffusa

Approved and first released in 1993 in 

the United States. This weevil has been 

released in Idaho, Minnesota, Montana 

(established), Nebraska, Oregon, and 

Washington Also released in Arizona.

The testing report that recommended 

introduction of L. obtusus to North 

America found that this biocontrol 

agent had a host plant range limited to 

species in the subgenera Acrolophus

and Jacea, and no native plants were at 

risk (Groppe, 1992).
Chapter 2 – Alternatives

58 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Scientific 

Name of 

Biocontrol 

Agent

Common 

Name of 

Biocontrol 

Agent

Target 

Species 

Common 

Name

Target 

Species 

Scientific 

Name

Notes

Mecinus 

janthinus

Stemmining 

weevil

Dalmatian 

toadflax

Linaria 

dalmatica

Approved for release in the U.S. in 

1995. An EA completed for release of 

this weevil in 1996 (Hennessey, 1996).

Introduced on Coconino NF in 2008 & 

2009. Studies of this agent in the 

Rocky Mtn. area demonstrated no 

evidence of nontarget herbivory at any 

site (Breiter, et al., 2007).

Sphenoptera 

jugoslavica

buprestid 

beetle

Diffuse 

knapweed

Centaurea 

diffusa

First released in the U.S. in 1979. Also

released in Arizona, Colorado, Idaho, 

Montana, Nebraska, Nevada, Oregon, 

South Dakota, Utah, Washington, and 

Wyoming. Established in Colorado, 

Idaho, Montana, Oregon, South 

Dakota, Washington, and Wyoming, 

and is being collected for redistribution 

in Colorado, Montana, Oregon, and 

Washington.

Urophora 

affinis

seed head 

flies

Spotted 

knapweed, 

diffuse 

knapweed

Centaurea 

biebersteinii, 

Centaurea 

diffusa

First released in the United States in 

1971. Released in Arizona, California, 

Colorado, Idaho, Michigan, Minnesota, 

Montana, Nebraska, Nevada, North 

Dakota, Oregon, South Dakota, Utah, 

Washington, Wisconsin, and 

Wyoming. Populations are established 

in all of these states but Nevada.

Urophora 

quadrifasciat

a

seed head 

flies

Spotted 

knapweed, 

diffuse 

knapweed 

Centaurea 

biebersteinii, 

Centaurea 

diffusa

Approved for release in 1988. Has been 

released and established in Arizona, 

California, Colorado, Idaho, Michigan, 

Minnesota, Montana, Nebraska, North 

Dakota, South Dakota, Utah, 

Washington, Wisconsin, and 

Wyoming. Establishment has been 

confirmed in Indiana, Maryland, New 

York, Pennsylvania, Vermont, New 

Hampshire, Massachusetts, Rhode 

Island, Connecticut, and New Jersey
Chapter 2 – Alternatives

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 59

Scientific 

Name of 

Biocontrol 

Agent

Common 

Name of 

Biocontrol 

Agent

Target 

Species 

Common 

Name

Target 

Species 

Scientific 

Name

Notes

Urophora 

stylata

Seedhead 

gall fly

Bull thistle Cirsium 

vulgaris

First released in Maryland and 

Washington in 1983. This was 

followed by releases in Colorado, 

Oregon, Montana, and California. Now 

established in the western United 

States, with 60 to 90% of bull thistle 

seed heads infested in some areas (Kok 

& Gassmann, 2002).

Herbicide Descriptions

The following herbicides are proposed for use on the Tonto NF. In addition to extensive testing 

and approval by Environmental Protection Agency (EPA), risk assessments have been prepared 

by the Forest Service for all of these proposed herbicides. The Forest Service risk assessments 

may be found at http://www.fs.fed.us/foresthealth/pesticide/risk.shtml. These human health and 

ecological risk assessments evaluate the probability that a given pesticide use might impose harm 

on humans or other species in the environment. It is the same process used for regulation of food, 

medicine, cosmetics, and other chemicals (U.S.F.S., 2005, Oct.).

The Environmental Protection Agency (EPA) is responsible for regulating the sale and use of 

pesticides, including herbicides, in the United States and ensuring that all pesticides can be used 

without causing adverse effects to humans or the environment.

In carrying out its responsibility, the EPA requires and reviews an extensive set of scientifically 

sound (80 to 120 chemistry, toxicology, exposure, and environmental) studies for each pesticide 

prior to marketing and use. EPA scientists review these studies to determine if the pesticide, when 

used according to the proposed pesticide’s use directions and restrictions, would cause potential 

adverse effects to humans or the environment, including wildlife, plants and animals.

Aminopyralid is a new chemical registered for control of broadleaf weeds on rangeland. It was 

developed specifically for the control of noxious and invasive weed species in rangeland, 

pastures, and industrial vegetation management sites. It is a new active ingredient that is effective 

at low rates as compared to currently registered herbicides with the same mode of action, 

including 2,4-D, clopyralid, triclopyr, picloram and dicamba. It was accepted for evaluation under 

the EPA’s Reduced Risk Pesticide program in October 2004, based upon data and risk 

assessments presented for toxicological, ecotoxicological, and environmental fate effects. 

Aminopyralid is a broadleaf weed herbicide that provides systemic, post-emergence control of 

noxious and invasive annual, biennial, and perennial weed species. It can provide residual 

control, thus reducing the need for re-treatment. Aminopyralid works by moving systemically 

throughout the plant to deregulate plant growth metabolic pathways affecting the growth process 

of the plant (Durkin, 2007). This disruption of plant growth processes, by binding of 

aminopyralid at receptor sites normally used by the plant’s natural growth hormones, results in 

control and death of susceptible plant species. Half-life in the soil averages 34.5 days. (The halflife of an herbicide is the period of time required for the active ingredient to decompose to onehalf of that which was applied.) Field tests demonstrate limited movement in the soil profile. No 
Chapter 2 – Alternatives

60 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

degradation metabolites of concern have been produced in any studies. This herbicide is 

dissipated in the soil by aerobic microbial degradation. The rate of breakdown depends upon soil 

moisture and soil temperature. Aminopyralid may be used to treat starthistles, Canada thistle, 

biennial thistles, knapweeds, teasel, and oxeye daisy. It is approved for use along state and federal 

highways through the Tonto NF (U.S.F.S., May 2004, Section 18 amendment).

Chlorsulfuron is registered for general use and is used to control many broadleaf weeds and 

some annual grasses. Some weeds might become resistant to chlorsulfuron after extended use. 

This herbicide prevents the target plant from producing an essential amino acid that controls cell 

division and has a half-life in the soil of 30 to 90 days depending on pH (Klotzbach & Durkin, 

2004a). Chlorsulfuron tends to leach into soils with a textural range from sand to silt loam and 

degrades more rapidly at higher temperatures with adequate moisture contents. It is broken down 

to smaller compounds by soil microorganisms. This herbicide is being used by ADOT to manage 

weeds along state and federal highways on the Tonto NF. Chlorsulfuron may be used to treat bull, 

musk and Scotch thistles, and dyer’s woad.

Clopyralid is a selective post-emergence herbicide controlling broadleaf species in the sunflower, 

legume, and smartweed family. This herbicide affects the target weed by mimicking the plant 

hormone auxin and causes uncontrolled plant growth and eventual death. It has an average halflife in the soil of 20 days, ranging from 15 to 287 days depending upon soil type and climatic 

conditions (Infoventures, 1995a). It is degraded primarily by microbial metabolism. Once applied 

to the ground, it rapidly disassociates and does not bind strongly with soil particles, which results 

in clopyralid having a high potential to contaminate ground or surface water. Commercial 

formulations of clopyralid are approximately 41 percent clopyralid and 59 percent inert 

ingredients (water, isopropyl alcohol, and a surfactant). This herbicide is being used by ADOT to 

manage weeds along state and federal highways on the Tonto NF. Clopyralid has also been used 

by the Prescott NF to treat resin bush in 2003 and 2004 near the town of Cottonwood. It may also 

be used to treat biennial thistles, Canada thistle, diffuse knapweed, Mediterranean sage, Russian 

knapweed, spotted knapweed, yellow starthistle, and Malta starthistle.

Dicamba is considered a general use herbicide for forestry, rangeland and rights-of-way uses. It 

is a selective herbicide used to control broadleaf weeds, brush, and vines. It affects target plants 

by regulating growth. About half of this product is broken down by microbial activity in 10 to 35 

days once applied. Breakdown is slower with low soil moisture and low temperatures. The main 

metabolite of dicamba breakdown in soil is 3,6-dichlorosalicylic acid (Infoventures, 1995c). 

Dicamba is highly mobile in the soil and does have the potential to contaminate ground or surface 

water. This herbicide is very versatile in weed control and has been proven successful in 

treatment of biennial thistles, Canada thistle, dyer’s woad, leafy spurge, rush skeletonweed, 

spotted knapweed, sulfur cinquefoil, and yellow and Malta starthistles. There are no records of 

dicamba having been used on the Tonto NF in the past. It is approved for use along state and 

federal highways on National Forests in Arizona (U.S.F.S., May 2004).

Glyphosate is a broad-spectrum, nonselective herbicide used for control of annual and perennial 

plants including grasses, sedges, broadleaf weeds, and woody plants. This herbicide is used on a 

variety of crops and its method of action is to inhibit amino acid and protein synthesis (Durkin, 

2011a). It is moderately persistent in the soil and has an estimated half-life of 30 to 50 days. 

Glyphosate is strongly absorbed in most soils and normally does not leach out of the profile. 

Microbes are primarily responsible for the breakdown of this herbicide in the environment. 

Glyphosate has been successful in controlling Canada thistle, cheatgrass, leafy spurge, spotted 
Chapter 2 – Alternatives

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 61

knapweed, Dalmatian toadflax, yellow and Malta starthistles, buffelgrass and fountain grass. It 

appears that this product was used to some degree for reforestation site preparation in the 1970s 

and early 1980s on the Coconino NF and North Kaibab RD. Records on the Kaibab NF indicate 

that Roundup (glyphosate) and Dowpon M were used to treat about 2,000 acres to control 

unwanted vegetation prior to planting. Glyphosate is approved for use along state and federal

highways on National Forests in Arizona (U.S.F.S., May 2004).

EPA initially registered (licensed) the first glyphosate product in 1973. In 1993 and in subsequent 

years, EPA’s program to systematically re-evaluate the safety of all registered pesticides 

determined that glyphosate continues to meet EPA's safety standards provided it is used according 

to label directions. Products formulated with glyphosate are approved for use in the U.S. with 

aerial, ground, and hand-held applicators on certain food crops such as corn, industrial and forest 

land, and aquatic sites for control of terrestrial and aquatic weeds. Glyphosate products are also

approved for use on home lawns and gardens. Glyphosate herbicides are used extensively in the 

U.S. and many other countries. 

After a rigorous analysis of extensive sets of studies for each herbicide, EPA determined that 

glyphosate herbicide products can be used according to label directions without causing 

unreasonable adverse effects to humans or the environment. Risks to humans and wildlife animals 

are below EPA’s levels of concern; however, there are risks to nearby non-target plants, which can 

be effectively managed with proper application measures (EPA, 2009).

Imazapic is a selective herbicide for both pre- and post-emergent control of some annual and 

perennial grasses and broadleaf weeds. It affects plants by inhibiting the production of amino 

acids that ultimately reduces cell growth (Durkin & Follansbee, 2004b). Its half-life in the soil is 

120 days, and it is considered moderately persistent. The primary mechanism of degradation is 

through microbial action. It does not volatilize when applied. Imazapic is known to be effective in 

control of Canada thistle, leafy spurge, and cheatgrass. Imazapic is approved for use along state 

and federal highways on National Forests in Arizona (U.S.F.S., May 2004).

Imazapyr is also a broad-spectrum herbicide that can be applied pre- or post-emergence. It is 

appropriate to use this herbicide on rangelands, forestlands and rights-of-way, although cropland 

use is excluded. Imazapyr is absorbed by the leaves and roots and moves rapidly through the 

plant. It acts by accumulating in the meristem region and disrupting protein synthesis by 

interfering with cell growth and DNA synthesis (Durkin, 2011c). Unlike most other herbicides 

proposed for use by the forests, it can remain active in soil for six months to two years

(Infoventures, 1995d). It has a strong affinity to bind to soils and rarely moves beyond the top 

few inches of the soil. As such, it has a low potential for leaching to ground water, but may reach 

surface water during storm events over recently treated land. Sunlight and microorganisms break 

down Imazapyr. Little is lost to evaporation. Imazapyr is approved for use along state and federal 

highways on National Forests in Arizona (U.S.F.S., May 2004). Habitat, an imazapyr-based 

herbicide is being used by the Coconino and Prescott NFs in cut-stump treatment of saltcedar 

along the Upper Verde River, with very good results.

EPA initially registered (licensed) the first imazapyr product in 1985. In 2006 and in subsequent 

years, EPA’s program to systematically re-evaluate the safety of all registered pesticides 

determined that imazapyr continues to meet EPA's safety standards provided it is used according 

to label directions. Products formulated with imazapyr are approved for use in the U.S. with 

aerial, ground, and hand-held applicators on certain food crops such as corn, industrial and forest 
Chapter 2 – Alternatives

62 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

land, and aquatic sites for control of terrestrial and aquatic weeds. This herbicide is used 

extensively in the U.S. and many other countries (EPA, 2009).

Metsulfuron methyl is used to control brush and certain unwanted woody plants, annual and 

perennial broadleaf weeds, and annual grassy plants. This herbicide has a half life of 120 to 180 

days and affects plants by inhibiting cell division in the roots and shoots, thereby stopping growth

(Klotzbach & Durkin, 2004b). Generally, soil microorganisms break down this herbicide into 

nontoxic products, although chemical hydrolysis can also break it down (Infoventures, 1995e). 

Metsulfuron methyl dissolves easily in water and can leach through the soil to contaminate 

ground water, but this situation is confined to soils that are either sandy or porous. This herbicide 

has been proven successful in control of biennial thistles, Canada thistle, dyer’s woad, Russian 

knapweed, and whitetop. Metsulfuron methyl is approved for use along state and federal

highways on National Forests in Arizona (U.S.F.S., May 2004).

Picloram is considered a “Restricted Use” herbicide and, as such, can only be sold and used by a 

licensed pesticide applicator. This classification is due to this herbicide’s mobility in water 

combined with the sensitivity of many crops that can be damaged with the use of picloram. It is 

used to control broadleaf plants, brush, conifers, and broadleaf trees. It interferes with the weed’s 

ability to make proteins and nucleic acids and is broken down to carbon dioxide by sunlight and 

microorganisms (Durkin, 2011). The half-life of picloram is 90 days and it dissolves easily in 

water. This herbicide works well in control of biennial thistles, Canada thistle, Dalmatian 

toadflax, diffuse knapweed, dyer’s woad, leafy spurge, Mediterranean sage, oxeye daisy, rush 

skeletonweed, Russian knapweed, Scotch thistle, spotted knapweed, sulfur cinquefoil, whitetop, 

and yellow and Malta starthistles. A combination of his herbicide and tebuthiuron was used on the 

Kaibab NF in the mid 1980s to control piñyon and juniper trees on 15,000 acres of rangeland 

(U.S.F.S., Feb 2004). This decision was short lived, and the program was suspended in 1984,

when the Forest was enjoined from further applications of herbicides. Picloram is now approved 

for use along state and federal highways on National Forests in Arizona (U.S.F.S., May 2004).

Sethoxydim is a general use herbicide for control of annual and perennial grasses. Sethoxydim is 

easily absorbed by plant roots and foliage and transported through the xylem and phloem to the 

meristematic tissues of the plant (WSSA, 1994). It kills grasses by preventing the synthesis of 

lipids, which leads to failure of cell membrane integrity. This results in a cessation of shoot and 

rhizome growth, leading to necrosis and death of shoot meristems and rhizome buds and 

ultimately plant death. It has an average half life in soils of four to five days, but this can range 

from a few hours to 25 days. Sethoxydim is water soluble and does not bind strongly with soils, 

so it can be highly mobile. It is degraded readily by light and microbial metabolism. Rapid 

degradation generally limits extensive movement in the environment. Sethoxydim is not highly 

volatile (Tu, et al., 2001). This herbicide works well to control bromes, quackgrass, and wild oats. 

Sethoxydim is now approved for use along state and federal highways on National Forests in 

Arizona (U.S.F.S., May 2004).

Sulfometuron methyl is considered a general use registered herbicide. It is applied to control 

annual and perennial grasses, as well as broadleaf weeds. Sulfometuron methyl stops plant 

growth by inhibiting cell division in the growing tips, roots, and shoots of target plants

(Klotzbach & Durkin, 2004c). This herbicide has a half life of about 30 days and is broken down 

to carbon dioxide by microorganisms, sunlight, and chemical hydrolysis. Sulfometuron methyl is 

insoluble in water. In acidic soils it has a low potential for movement; whereas in alkaline soils, 

where it is close to ground water, it has some potential for movement (Infoventures, 1995f).
Chapter 2 – Alternatives

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 63

Sulfometuron methyl is approved for use along state and federal highways on National Forests in 

Arizona (U.S.F.S., May 2004).

Triclopyr is a pyridine and works by disrupting plant growth. It is absorbed by green bark, 

leaves, and roots and moves to the meristem of the plant. It is active in soil, and is rapidly broken 

down by microbes, particularly in warm climates. It has a half life in the soil of 30 to 90 days; the 

ester and amine salt formations convert to an acid, which degrades into carbon dioxide, a 

relatively nontoxic salt and organic matter through microbial action (Durkin, 2011b). Triclopyr 

has a moderate-to-low solubility in water and normally binds to clay and organic matter, so its 

potential to contaminate ground water is slight. Triclopyr is effective in the treatment of saltcedar, 

tree of heaven, Russian olive, and Siberian elm. Triclopyr is approved for use along state and 

federal highways on National Forests in Arizona (U.S.F.S., May 2004).

Surfactants are commonly used in herbicide formulations to ensure even distribution and 

improve absorption or permeation of the herbicide into the plant, or to prevent herbicide drift. 

Surfactants play a key role in the effectiveness of an herbicide formulation. Information on the 

types of surfactants used and the toxicity of surfactants can be limited since pesticide 

manufacturers consider these formulations to be proprietary information which does not require 

coverage under FIFRA as do pesticide active ingredients.

Table 3. Typical and maximum application rates for herbicides and carriers (in pounds 

active ingredient per acre)

* This application rate is provided in ounces of active ingredient per acre.

Herbicide/ Carrier Rangeland Forestland Facilities Right-ofWay

Recreation

/Administration Riparian

Aminopyralid 0.078 to 0.11 0.078 to 0.11 0.078 to

0.11 0.078 to 0.11 0.078 to 0.11 0

Chlorsulfuron* 0.75 to 3 0.75 to 3 0.75 to 3 0.75 to 3 0.75 to 3 0.75 to 3

Clopyralid 0.25 to 0.5 0.25 to 0.5 0.25 to 0.5 0.25 to 0.5 0.25 to 0.5 0.25 to 0.5

Dicamba 2 to 4 2 to 4 2 to 8 2 to 4 2 to 4 2 to 4

Glyphosate 1 to 4 2 to 4 2 to 4 2 to 4 2 to 4 2 to 4

Imazapyr 1 to 1.5 1 to 1.5 1 to 1.5 1 to 1.5 1 to 1.5 1 to 1.5

Metsulfuron methyl 0.5 to .75 0.5 to 1.8 0.5 to 1.8 0.5 to 1.8 0.5 to 1.8 0.5 to 1.8

Picloram 1 to 2 1 to 2 2 to 3 2 to 3 1 to 2 1 to 2

Sethoxydim 4.3 to 7.2 4.3 to 7.2 4.3 to 7.2 4.3 to 7.2 4.3 to 7.2 4.3 to 7.2

Sulfometuron 

methyl 2 to 9 2 to 6 2 to 9 2 to 9 2 to 9 2 to 9

Triclopyr 1.5 to 2 3 to 6 4 to 9 4 to 9 1.5 to 2 4 to 8

Imazapic .03 to .06 .03 to .06 .03 to .06 .03 to .06 .03 to .06 0

Carriers

Mineral Oil 2 to 4 4 to 8 2 to 8 2 to 14 2 to 4 2 to 4

Vegetable Oil 2 quarts 2 quarts 2 quarts 2 quarts 2 quarts 2 quarts

Methylated Seed Oil 1 to 2 pints 1 to 2 pints 1 to 2 pints 1 to 2 pints 1 to 2 pints 1 to 2 

pints
Chapter 2 – Alternatives

64 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Alternatives

Alternative 1 – No Action

This alternative allows all previous decisions regarding treatment of noxious weeds on the Tonto 

NF to continue. These actions include: 

 Continuation of a prescribed burning program to prevent spread of Malta starthistle along 

Highway 188 from the junction with the Beeline Highway to Cholla Recreation Site 

(U.S.F.S., Tonto NF, 10/2004). 

 Treatment of yellow starthistle and diffuse knapweed with prescribed fire, grubbing, and 

herbicides at the Pleasant Valley Ranger Station Administrative Site (U.S.F.S., Tonto NF,

3/2004).

 Use of hand tools and hand-pulling to remove weeds forestwide (U.S.F.S., Tonto NF,

2005b).

 Use of prescribed fires less than 10 acres in size, within 50 feet of Forest System Roads 

(U.S.F.S., Tonto NF, 2005b).

 Use of herbicides along all federal and state highways through the Tonto NF. Herbicides 

may be sprayed with ground-based equipment on rights-of-way, and 200 feet beyond the 

right-of-way onto National Forest system land (U.S.F.S., May 2004).

 Use of herbicides in sites covered by Categorical Exclusions, that is to say administrative 

and recreation sites.

Under this alternative, the Forest’s weed management program will be limited to manual weed 

removal, use of prescribed fire only in blocks of 10 acres or smaller, and along a portion of 

Highway 188, and use of herbicides and prescribed fire at the Pleasant Valley Ranger Station 

horse pasture. Prescribed burns greater than 10 acres in size and herbicides will not be used 

(although some “housekeeping” uses may be categorically excluded from documentation at 

administrative and recreation sites), and no mechanical, cultural, or biological weed control 

measures will be used.

Up to 200 acres per year would be treated by manual control, up to 1,000 acres would be treated 

with herbicides under projects already approved, up to 2,000 acres could be treated with 

prescribed burning under existing project documentation, and up to 300 acres could be treated 

with herbicides at administrative or recreation sites. 

The No Action alternative is required by law. It addresses both Issues 1 and 2 as described above 

in the Issues section, but does not fulfill the purpose and need to effectively address the 

introduction and spread of invasive plants according to Forest Service policy and law. 

Alternative 2

This alternative provides for use of all integrated vegetation management tools, as described 

under the proposed action, except the use of herbicides would be excluded. Mechanical, manual, 

prescribed burning and cultural control methods would be used to manage existing invasive plant 

populations and to control new infestations as they occur. Mechanical methods would include 

mowing, or using equipment to cut tops off invasive plants. Up to 2,000 acres of mechanical 

treatments would be conducted. Manual methods would include cutting off seedheads and 

severing taproots, digging, or pulling plants. Up to 400 acres per year could be treated by manual 

control. Cultural control methods would be used to improve ground cover and heal disturbed 
Chapter 2 – Alternatives

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 65

ground locations, to reduce vulnerability of sites to new weed infestations. Acres treated by 

cultural control methods would be approximately the same as for the proposed action, or up to 

2,000 acres. Acreage of mechanical and prescribed burn treatments would be increased from the 

proposed action, in an attempt to meet objectives of the program. Up to 2,000 acres would be 

treated by mechanical methods, and up to 2,000 acres would be treated with prescribed fire. 

Monitoring would be conducted to assess effectiveness of treatments. Surveys would be 

conducted to locate new weed infestations. Education, prevention, and cooperation would occur 

as described under the proposed action. 

This action was developed to address concerns for effects of chemical herbicides on non-target 

species and human health (both issues 1 and 2 in the Issues section above). 

Mitigation Measures Common to the Proposed Action and 

Alternative 2

In response to public comments on the proposal, mitigation measures were developed to ease 

some of the potential impacts the various alternatives may cause. 

• Invasive species populations would be treated only after the area has been evaluated and 

surveyed for federally-listed and sensitive plant and animal species. Field surveys will be 

conducted within occupied and potential habitat for sensitive species. The scope of the 

survey will be dependent on the type of treatment proposed, but will be sufficient to 

provide for the identification and protection of sensitive species within the project area. 

Individuals and populations of sensitive plants will be flagged or otherwise identified so 

they can be avoided during treatment. If necessary, a buffer zone of sufficient size will be 

established to protect sensitive species from mechanical disturbance or spray drift.

• Heritage resources will be identified and protected from any ground disturbing activities.

• Spray trucks, all-terrain-vehicles (ATVs), tractor-mounted mowers and other equipment 

used for invasive plant management will not be used in such a way that would increase 

erosion. Steep or highly erodible slopes will be avoided, and soil disturbance will be 

minimized.

• Heavy equipment will not be used within 30 feet of any stream bank. Handheld or ATVmounted equipment will be used within this zone.

• Prevention measures prescribed in appendix C will be followed during agency activities 

to the degree possible to minimize invasive plant introduction and spread on the Forest. 

This is the single most effective and least expensive weed management option available.

• The only biological control agents that would be considered for use would be those 

selective for the target species, and approved by the APHIS for use on that species. No 

biological control agents will be used to control saltcedar.

• If restoration of treated areas includes establishing new plants, this would be 

accomplished by broadcast seeding of native species or non-persistent, nonnative cover 

crops.

• All seed used for revegetation will be checked for presence of the Tonto NF’s list of 

invasive species, in addition to routine weed seed testing performed by seed companies.

• All sites treated for invasive species will be monitored and retreated as necessary.

Monitoring is a follow-up part of each treatment activity. Baseline monitoring to 

determine existing conditions will occur prior to treatment.
Chapter 2 – Alternatives

66 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Mitigation Measures Involving the Use of Herbicides

The application of herbicides is tightly controlled by state and federal agencies. The Forest 

Service is required to follow all state and federal laws and regulations concerning the use of 

herbicides. The following measures will be followed for the proposed action:

• Herbicides will be used when it is determined that they offer the most practical, timely 

and economical method for control, and/or that they are an integral part of an integrated 

treatment strategy.

• All applicable state and federal laws, including herbicide label requirements will be 

followed.

• Projects will be supervised by a Forest Service certified applicator, who will be 

responsible for ensuring safe storage, handling, application, and disposal of herbicides.

• Herbicides will be applied only by ground-based equipment, including hand painting or 

daubing, backpack sprayers, and spray units on ATVs or trucks.

• Picloram will not be used where the water table is within 40 inches of the surface, or 

where soil permeability would be conducive to water contamination.

• Persons involved in mixing, loading, and applying herbicides will be required to wear 

appropriate personal protective equipment as required on the label.

• Areas used for mixing herbicides and cleaning equipment shall be located where spillage 

will not run into surface waters or result in ground water contamination.

• Best Management Practices (BMPs) will be followed.

• All requirements of a Safety and Spill Plan (appendix E) will be followed

• Forest Supervisor approval of the Pesticide Use Proposal (Form FS 2100-2) will be 

necessary for the application of any herbicide, unless this authority has been delegated to 

the District Ranger. Use of herbicides in wilderness areas or wilderness study areas 

requires approval by the Regional Forester as per Forest Service Manual 2151.04a.

• Treatment areas will be signed to alert the public of the herbicide application.

• Landowners within one-half mile of the area to be treated with herbicide will be notified 

before the project is undertaken.

• Mitigation measures prescribed for federally-listed and sensitive species (see appendix G) 

will be followed.

Permits and Agency Approvals Required 

The following permits or authorizations will be required for individual actions:

• Prior to burning, a burn permit will be obtained from Arizona Department of 

Environmental Quality.

• A concurrence or a biological opinion will be requested from the U.S. Fish and Wildlife 

Service on the biological assessment, addressing listed threatened, endangered, and 

proposed species, if the biological assessment and evaluation makes a “May Affect” 

determination. Subsequent actions will conform to Terms and Conditions of a Biological 

Opinion.

• Some situations may require concurrence from the Arizona State Historic Preservation 

Officer regarding identification, evaluation, and determination of effect of the project on 

heritage resources.
Chapter 2 – Alternatives

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 67

• A discharge permit either through the Arizona Department of Environmental Quality or 

the Corps of Engineers is required prior to application of any herbicide within navigable 

waters.

• Obtain any necessary permit from APHIS prior to release of biological control agents.

Any agent to be used will have undergone extensive testing and have been approved by 

APHIS for use in the state of Arizona. A permit must be obtained from APHIS before

biological control agents can be transported across state boundaries.

• Although biological control agents may be collected and released within the state without 

a permit from APHIS, the Arizona Department of Agriculture should be consulted for 

any regulations relating to movement of these agents inside the state. 

If herbicides are to be used, at least one certified applicator will be on the project site to supervise 

others. This person will have training and certifications in use of herbicides, as required by Forest 

Service manual and state law.

The proposed action and alternatives 1 and 2 are compared in table 4.
Chapter 2 - Alternatives

68 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Table 4. Comparison of alternatives

Proposed Action Alternative 1 Alternative 2

Meets the 

purpose and 

need for the 

action

Yes. Authorizes the most effective 

treatments for all invasive species 

across the Forest

No. Invasive species would not 

be effectively managed.

In part. Since the use of herbicides would 

not be authorized, effective treatment of 

certain invasive plant species would be 

limited and spread of some invasive species 

would not be adequately checked or 

prevented.

Consistent with 

Forest Plan

Yes. Hazardous conditions caused by 

noxious weeds (wildfire, toxic forage 

for animals, etc.) are reduced by using 

an effective suite of control methods;

maintains or enhances the visual 

resource; provides for habitat for 

species diveristy; helps to bring 

rangeland to its highest condition; 

reduces erosion and provides for water 

quality; maintains wilderness character 

of a variety of native species in natural 

habitats.

No. Allows uncontrolled 

spread of invasive species.

Yes. However, reliance on cultural, 

mechanical, and manual methods would 

result in gradual increase in degradation of 

the visual resource, rangeland condition, 

wildlife habitat, and water quality, since 

treatment methods will not be sufficient to 

control some species.

Consistent with 

law, regulation, 

and policy

Yes. Responsive to the Farm Bill of 

1990, Forest Service Manual 2080 & 

2150, Forest Service national strategy, 

and Executive Order 13112.

Not responsive to laws and 

regulations.

Somewhat. Ineffective management results 

in dissatisfaction of cooperators and does not 

effectively prevent an increase in size of 

many invasive plant infestations.

Effect on 

human health –

both public & 

employees

Little effect on human health. Risks 

associated with exposure to herbicides 

will be insignificant to the public.

Minor risk of exposure to workers, 

which will be mitigated by use of 

personal protective equipment and 

training. Risks of burning toxic smoke 

during prescribed burns in areas that 

have been treated by herbicides are 

minimal, compared with risks of 

breathing smoke that occurs during 

wildfires and routine prescribed burns.

Little effect on human health.

Increase in wildfire potential in 

the Sonoran Desert, which 

may lead to indirect effects 

from smoke.

Effects similar to alternative 1. Additional 

slight risk for injury to personnel performing 

prescribed burns and mechanical treatments.
Chapter 3 – Affected Environment and Environmental Consequences

EA for Wildland Fire Use Amendment to the Coronado National Forest LRMP 69

Proposed Action Alternative 1 Alternative 2

Effect on the 

environment –

soil & water 

quality, native 

vegetation, and 

wildlife

Removal of invasive plants, combined 

with restoration where needed, will 

favor the establishment of native 

vegetation and more natural soil and 

water quality conditions. Use of 

herbicides may result in short-term 

presence of herbicides in soil.

Mitigation measures will reduce the risk 

of water contamination. Minor effects to 

non-target vegetation will be minimized 

by project design and mitigated by 

overall increases in plant diversity as 

invasives are reduced. No effects to

federally-listed or sensitive plants or 

animals will be allowed. Herbicide 

exposure risks to wildlife are minimal. 

Long-term restoration of native plant 

communities will increase habitat 

capability in infested areas.

Very small possibility of 

herbicide contamination of 

vegetation, wildlife, soil or 

water. Increases in tap-rooted 

species may increase surface 

runoff in some areas. Increased 

distribution and density of 

annual and perennial exotic 

invasive grasses could increase 

wildfire occurrence, size, and 

impacts. Native plant 

communities could become 

less diverse as species such as 

starthistles and knapweeds 

spread and create 

monocultures in large areas. 

Some federally-listed and 

sensitive plants and animal 

populations may probably 

suffer from habitat 

degradation. This alternative 

results in highest level of 

degradation of forage and 

wildlife habitat. 

Invasive species continue to spread, but not 

as rapidly as in alternative 1. Prevention 

measures proposed will slow introduction of 

invasives, but manual, mechanical and 

prescribed burning alone will not be 

sufficient to control the spread of existing 

populations and new infestations that will 

inevitably occur. As in alternative 1, some 

federally-listed and sensitive plants and 

animal populations will probably suffer from 

habitat degradation. Manual control may 

result in some short-term displacement of 

wildlife, and possibly increased erosion.

Acres treated by 

various 

methods:

Manual: 400

Mechanical: 500

Burning/torching: 2,000

Cultural: 2,000

Biological: will be used

Herbicide: 9,000

Total: 13,900

Manual: 200

Mechanical: 0

Burning/torching: 2,000

Cultural: 0

Biological: will not be used

Herbicide: 1,300

Total: 3,500 

Manual: 400

Mechanical: 2,000

Burning/torching: 2,000

Cultural: 2,000

Biological: will be used

Herbicide: 1,300*

Total: 7,700

* This acreage is based upon previous decisions, as for the “No action” alternative.

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 71

Chapter 3 – Affected Environment and 

Environmental Consequences

This section summarizes the physical, biological, social and economic environments of the 

affected project area and the potential changes to those environments due to implementation of 

the alternatives. It also presents the scientific and analytical basis for the comparison of 

alternatives presented in the chart above.

The analysis area for this environmental assessment is the entire Tonto NF (see map). The Forest 

is comprised of nearly three million acres in parts of four Arizona counties: Gila, Maricopa, Pinal, 

and Yavapai. From northwest to southeast, major mountain ranges include the New River 

Mountains, Pine Mountain, the Mazatzal Mountains, Sierra Anchas, Superstitions, and the Pinals.

Elevations range from 1,260 to 7,914 feet. The Tonto NF includes a wide range of vegetation 

types over this elevation range, and encompasses a major portion of the watersheds of the Salt 

and Verde rivers. Smaller portions of the Forest also include upper reaches of the Agua Fria, New 

River, and Cave Creek watersheds. Major highways bisecting the Forest include the Beeline 

Highway (State Route 87), the Bush Highway that runs along the lower Salt River, north to 

Saguaro Lake and the Beeline, State Route 188 from SR 87 to Globe, State Route 60 from 

Phoenix to Globe and north to the San Carlos Reservation, State Route 70 from Globe west to the 

San Carlos Reservation, State Route 177 south of Superior, State Route 77 from east of Globe 

running south toward Winkelman, State Route 288 from Tonto Basin to Young, and State Route 

88 (the historic Apache Trail) from Highway 60 to Roosevelt Dam.

The two major rivers, the Salt and Verde include two “chains of lakes:” Horseshoe and Bartlett 

on the Verde River; and Roosevelt, Apache, Canyon, and Saguaro on the Salt River. Dams on 

these rivers were constructed for water conservation and flood control; Salt River dams also 

generate electricity. The lakes and rivers are heavily utilized recreation sites for residents of the 

metropolitan area of Phoenix.

The description of the affected environment and disclosure of effects concentrates on not only the 

significant issues generated through scoping but also on the purpose and need of the proposed 

project. This includes such considerations as the capacity of an action to control the spread of 

invasive and noxious weeds, potential health impacts, potential impacts to clean water, and the 

ability of Native Americans to collect plants for traditional purposes if the use of herbicides is 

authorized. In addition, several other key resources are fully analyzed within the scope of this 

environmental analysis, including threatened, endangered and sensitive plant and animal species, 

as well as management indicator plants and animals.

For items within this analysis, the effects assessment consolidates the discussion of the impacts 

where appropriate, and highlights the relationship between local short-term uses of the 

environment and the maintenance as well as enhancement of long-term ecosystem productivity.

Cumulative effects are those that result from the incremental impact of this proposed action and 

alternatives when added to other past, present, and reasonably foreseeable future actions 

regardless of who undertakes those activities (40 CFR 1508.7). The cumulative effects analysis is 

found after the discussion of direct and indirect effects for the major groupings. If none are 

predicted, this is documented. Cumulative effects analysis is keyed to the major issues, purpose 

and need, and the other resource areas disclosed in this chapter, and must: 1) be additive with 

other activities found within the project impact zone, and 2) the effect of the proposed action and 

alternatives must overlap in time and space with these other activities. The project impact zone 
Chapter 3 – Affected Environment and Environmental Consequences

72 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

for this analysis is the land area of the Tonto NF and lands of other ownership adjacent to the 

Tonto NF. It also includes private inholdings and municipal areas such as Payson, Globe, and 

Young, and for some resources, such as human health, the Phoenix metropolitan area. 

Soil Resources

Affected Environment

Geology on the Forest is a highly diverse mixture of igneous rocks (granite, rhyolite, basalt, 

diabase), metamorphic rocks (schist, quartzite), and sedimentary rocks (limestone, sandstone, 

shale, conglomerates). As a consequence, soils are highly diverse. The dominant soils are 

moderately deep to deep, strongly developed, and display a wide range of both internal and 

surface rock fragments. There are, however, significant areas containing shallow soils, many of 

which are poorly developed. Surface textures are mostly loams and sandy loams with a few areas 

having clay loam surfaces. Surface rock fragments typically range from 15 to 65 percent. About 

60 percent of all soils have medium textured subsoils (loamy-skeletal, fine-loamy, coarse-loamy), 

about one-third have fine textured subsoils (clayey-skeletal, fine, very fine), and about 5 percent

are coarse textured (sandy-skeletal, sandy). The finer textured soils tend to occur on slopes less 

than 40 percent, medium textured soils occur on all slopes, while coarse textured soils occur 

either on steep scarp slopes such as the Mogollon Escarpment or along drainages. Soils along 

drainages are highly variable in both texture and rock fragments. About 70 percent of the soils 

have greater than 35 percent rock fragments in the subsoil. The reaction (pH) of the soils varies 

with soil parent material and soil climate. The dominant soils have a neutral reaction (pH 6.6 to 

7.3) but slightly acid soils (pH 6.1 to 6.5) and slightly alkaline soils (pH 7.4 to 7.8) are common. 

A few soils are moderately alkaline (pH 7.9 to 8.4) while strongly acid soils (pH 5.6 to 6.0) are 

rare (U.S.F.S., Tonto NF, 1979; U.S.F.S., Tonto NF, 1985a; & U.S.F.S., Tonto NF, 2005a). Soil 

texture, rock fragments, and pH (among other factors) can influence the movement of herbicides 

through the soil profile. 

Unit of measure for effects to soils is the degree to which each alternative increases or decreases 

soil quality. Soil quality is based on an interpretation of factors that affect the following three 

primary soil functions:

• Soil Hydrologic Function. This function is assessed by evaluating or observing changes 

in surface structure, surface pore space, consistence, bulk density, infiltration or 

penetration resistance using appropriate methods. Increases in bulk density or decreases 

in porosity result in reduced water infiltration, permeability and plant available moisture.

• Soil Stability. Soil erosion is the detachment, transport, and deposition of soil particles by 

water, wind or gravity. Vascular plants, soil biotic crusts, and litter cover are the greatest 

deterrent to surface soil erosion. Visual evidence of surface erosion includes sheets, rills, 

and gullies, pedestalling, soil deposition, erosion pavement, and loss of the surface "A" 

horizon. Erosion models are also used to predict on-site soil loss.

• The current approximate soil condition on the Tonto National Forest shows 1.7 million 

acres Nutrient Cycling. This function is assessed by evaluating the vegetative community 

composition, litter, coarse woody material, root distribution and soil biotic crusts. These 

indicators are considered an important source of soil organic matter, which is essential in 

sustaining long-term soil productivity. It provides a carbon and energy source for soil 

microbes, stores and provides nutrients which are needed for the growth of plants and soil 
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 73

organisms, and provides for cation and anion exchange capacities. Satisfactory - The soil 

indicators (hydrologic function, soil stability, and nutrient cycling) signify that soil 

function is being sustained and the soil is functioning properly and normally. The ability 

of the soil to maintain resource values and sustain outputs is high.

Interpretation of these three factors results in soils being placed in one of three condition classes:

• Satisfactory - The ability of the soil to maintain resource values and sustain outputs is 

high.

• Impaired - The ability of the soil to function properly has been reduced and/or there 

exists an increased vulnerability to degradation

• Unsatisfactory - The soil indicators (hydrologic function, soil stability, and nutrient 

cycling) signify that loss of soil function has occurred

Approximately 1,640,000 acres (60 percent) are in Satisfactory Condition, six hundred 

thousand acres (22 percent) in Impaired Condition, and five hundred thousand acres (18

percent) in Unsatisfactory Condition. Soil conditions that are less than satisfactory are 

because of past management activities including domestic livestock grazing, recreation use 

including OHV activities, and wildfire. At the present time soil quality on the Forest is not 

considered to be significantly affected by the presence of invasive species because of limited 

extent and the relatively short period of time of infestation. However, the spread of invasive 

species could, over time, lead to a decrease in soil quality especially due to increased erosion 

and poor nutrient cycling. Many invasive species are tap-rooted and can affect soils quality in 

areas where bunchgrasses are replaced by these weeds. In other areas, exotic grasses such as 

red brome, buffelgrass, wild oats, and lovegrass can temporarily increase the amount of soil 

cover but also add fine fuels that increase the risk of wildfire and increased soils erosion 

following wildfire.

Table 5: Soil Properties

N. Tonto/Globe TES* TES Crew*

By Soil Family

Sandy-Skeletal/Sandy 3% 8%

Coarse-Loamy 2% 4%

Fine-Loamy 7% 10%

Loamy-Skeletal 55% 45%

Fine 23% 15%

Clayey-Skeletal 10% 19%

By Textural Groups

Coarse (Sandy) 3% 8%

Medium (Loamy) 64% 59%

Fine (Clayey) 33% 34%

By Rock Fragments

Skeletal 68% 72%

Non Skeletal 32% 28%
Chapter 3 – Affected Environment and Environmental Consequences

74 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

N. Tonto/Globe TES* TES Crew*

By Soil Depth

Deep 39% 39%

Moderately Deep & Deep 53% 32%

Shallow 8% 29%

*North Tonto and Globe TES (Terrestrial Ecosystem Survey) data are developed from acreage 

associated with each map unit from the North Tonto and North East Globe TES surveys covering 

982,000 acres. TES Crew data are derived from counts of the number map units developed by the Tonto 

TES crew from their progressive mapping of the remainder of the Tonto NF.

Environmental Consequences

Table 6: Effects of various weed control methods on soils:

Treatment Type and 

Acreage Treatment Description

Manual

Proposed Action – 400 acres

Alternative 1 – 200 acres

Alternative 2 – 400 acres

Most manual treatments involve extremely slight soil disturbance. 

However, some manual treatments, especially hand pulling or 

grubbing can result in soil disturbance around each plant and also 

provides an effective seed bed for germination of weed seed. This 

disturbance is relatively minor, short-term (likely less than one 

year), and of limited extent. The net long-term effects are 

generally positive for weed control, but some localized, shortterm negative effects on soil disturbance may occur. 

Mechanical 

Proposed Action – 500 acres

Alternative 1 – 0 acres

Alternative 2 – 2,000 acres

Most mechanical treatments involve some degree of soil 

disturbance. Most disturbance is short-lived (one to two years) 

and restricted to a realtively few acres (less than 0.1percent) on 

the Forest in the vicinity of weed infestation. Mechanical control 

of rhizomatous species may not be effective in controlling those 

species and could actually result in their spread. Many species are 

difficult to control because of the persistence of large seed banks 

once weeds have become established. The net long-term effects 

are generally positive for weed control but some localized shortterm negative effets on soil disturbance may occur.

Burning/torching

Proposed Action – 2,000

acres

Alternative 1 – 2,000 acres

Alternative 2 – 2,000 acres

Burning can be effective in controlling weeds, especially annual 

weeds. It is especially effective in removing large quantities of 

seeds of annual weeds. Some invasive species are difficult to 

control using fire and fire can also impact non-target species and 

result in increased soil erosion. There may be some short-term 

(one to two years) negative effects on soil disturbance in a few 

areas but the long-term net effect of burning is likely to be 

positive for weed control and soil condition.

Cultural

Proposed Action – 2,000

acres

Alternative 1 – 0 acres

Alternative 2 – 2,000 acres

Cultural practices are designed to establish desirable plants in 

order to prevent infestation by invasive plants. There may be 

some short-term disturbance in areas prepared for seeding 

establishment, but the long-term effect is an expected decrease in 

erosion.
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 75

Treatment Type and 

Acreage Treatment Description

Biological

Proposed Action – Will be 

used

Alternative 1 – Will not be 

used

Alternative 2 – Will be used

Biological controls involve grazing animals, approved insects and 

pathogens to control weeds. The use of biological controls, except 

for grazing animals, would have little to no direct or indirect 

effects on soils. The use of grazing animals, however, could have 

both short and long-term effects on soils. Grazing that is heavy 

enough to control weeds may also severely reduce the cover of 

native plants and lead to increased erosion. The net effect of using 

biological controls, except for grazing animals, is likely to be 

positive. The net effects of grazing animals could be positive with 

strict controls or negative if native vegetation is affected.

Herbicide 

Proposed 

Action – 9,000 acres

Alternative 1 – 1,300 acres

Alternative 2 – 1,300 acres 

Herbicides that selectively target only invasive species and/or are 

used in spot treatments would allow native species to recover

which should reduce soil erosion and enhance nutrient cycling. 

Possible negative effects of herbicide application include the 

potential for decreasing or altering microbial populations in the 

soil profile. Studies on soil organisms show that herbicides could 

cause a temporary shift in soil microbial populations by reducing 

biodiversity and relative biomass of individual species (U.S.F.S.,

Bitterroot NF, 2003). Declining numbers of some macro-organism 

species have been observed at herbicide application test sites. 

These effects, however, are temporary and populations generally 

recover after a few days or weeks (Brady & Weil, 1999). The net 

effects of herbicides would likely be short-term negative effects to 

soil microbes but a long-term positive effect to overall soil 

quality.

Total Acres Treated

Proposed Action – 13,900

acres

Alternative 1 – 3,500 acres

Alternative 2 – 7,700 acres

Comparison of Alternatives

Direct and Indirect Effects

The proposed action is more likely than the other alternatives to limit or reduce the spread of 

invasive plants because more acres per year could be treated and more control methods are 

available (see treatment comparisons in above table). Assuming that native plant communities 

will replace tap-rooted invasives after treatment, soil protection and nutrient cycling should be 

enhanced. Alternative 1 would be the least effective in preventing the spread of invasive plants 

since this alternative would treat the fewest acres and have the fewest methods available for 

treatment. Alternative 2 would be somewhat intermediate in effectiveness. While the proposed 

action has the greatest total area of disturbance, the greatest direct impact to soils is by 

alternative 2, with more acres of mechanical treatment. Alternative 1 would have the least direct 

disturbance to soils.
Chapter 3 – Affected Environment and Environmental Consequences

76 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

The control of exotic annual grasses such as red brome will be difficult under all alternatives 

given the relatively small areas treated annually, ranging from 3,500 acres in alternative 1 to 

13,900 acres in the proposed action, versus the hundreds of thousands of acres that can be

infested during wet winters. Infestations of red brome can lead to unnaturally severe wildfires, 

especially within the Sonoran Desert. These wildfires can cause unnaturally high erosion due to 

loss of ground cover. 

The direct effects of treatments depend on the type and extent of treatment. Physical removal 

(manual and mechanical) will result in localized, short-term disturbance. The most disturbance 

occurs in the proposed action with the least occurring in alternative 1. Burning may result in some 

localized, short-term (one to two years) negative effects; but prescribed burning to manage 

noxious weeds should result in controllable conditions for fire frequency, duration, and intensity 

based on environmental conditions used during implementation, thus resulting in fairly 

predictable ecological effects on soils. The effects of burning are same for all alternatives. The 

direct effect of cultural practices may be some slight, short-term disturbance in areas prepared for 

seeding. The effects are the same in the proposed action and alternative 2 but there would be no 

cultural practices in alternative 1. The use of biological controls (occurring only in the proposed 

action and alternative 2) would have little to no direct effects on soils quality unless grazing 

animals are used. If grazing animals are used heavy grazing could affect non-targeted native 

vegetation. The direct and indirect effect of using herbicides varies. Broadcast treatment by nonselective herbicides could destroy native species at a higher rate than weeds which would create 

more bare soil. On the other hand, herbicides that selectively target only invasive species and/or 

are used in spot treatments would allow native species to recover. Possible negative effects of 

herbicide application and persistence include the potential for decreasing microbial populations or 

altering species composition of microorganisms in the soil profile. Studies of potential impacts on 

soil organisms show that herbicides could cause a temporary shift in soil microbial populations by 

reducing biodiversity and relative biomass of individual species (U.S.F.S., Bitterroot NF, 2003). 

There is potential for inhibiting growth of some micro-organism species. Declining numbers of 

some macro-organism species have been observed at herbicide application test sites. These 

effects, however, are not expected to persist because the negative effects are temporary and 

populations generally recover after a few days or weeks (Brady & Weil, 1999). More acres would 

be treated under the Proposed Action than the other alternatives and the overall negative direct 

effects on soils of this alternative, while small, are slightly greater than the other alternatives.

Cumulative Effects

Other past, present and future activities may potentially contribute to cumulative effects on soil 

quality. Appendix I lists projects that may possibly impact the area. Activities that may affect soil 

quality include road use and construction, vegetation management (primarily fuels reduction), 

range management, fire suppression (primarily fire lines and safety zones), recreation 

management (primarily OHV use), and land and mineral resources. These activities can directly 

affect soil by compaction, displacement, removing protecting vegetation cover, and concentrating 

runoff. These activities can also indirectly affect soils by creating favorable environments for 

establishment and spread of noxious weeds.

Evidence suggests that the probability of cumulative toxic effects on soil biota caused by 

herbicide application is low due to low herbicide application rates, low inherent toxicities of the 

chemicals applied, the low levels at which they are present in soils, and the short duration of 

persistence of residues in soils relative to rotation lengths. Studies of potential impacts on soil 
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 77

organisms show that herbicides could cause a temporary shift in soil microbial populations by 

reducing biodiversity and relative biomass of individual species (U.S.F.S., Bitterroot NF, 2003). 

There is potential for inhibiting growth of some micro-organism species. Declining numbers of 

some macro-organism species have been observed at herbicide application test sites. These 

effects, however, are not expected to persist because the negative effects are temporary and 

populations generally recover after a few days or weeks (Brady & Weil, 1999).

All alternatives have the potential to physically affect soil quality during implementation of 

treatments. Activities can cause short-term localized soil compaction, and remove vegetation and 

litter cover. These effects are short-term (less than two years) and localized (covering less than 

0.5 percent of the forest). 

Water Quality

Affected Environment

Arizona Department of Environmental Quality (ADEQ) had identified ten major watersheds in 

the State of Arizona. The watersheds associated with the Forest are located on the Salt and Verde 

rivers with small portions on the Upper and Middle Gila River. All stream courses are evaluated 

on their ability to meet or “support” state water quality standards using data collected by state and 

federal agencies. These water quality standards vary and are based on the designated use of a 

particular stream. These designated uses include aquatic and wildlife, full or partial body contact 

related to recreation, fish consumption, domestic water source, agricultural irrigation and 

agricultural livestock watering. Many streams will have more than one designation, with the most 

restrictive criteria applied for water that is for domestic water supplies. Some of the tests 

commonly run for water quality are for bacteria (Escherichia coli), turbidity, temperature, 

dissolved oxygen, pH, hardness, and metals. While herbicide constituents are sampled for on a 

project or site specific basis in lakes and streams, they are routinely assessed in wells (ADEQ, 

2009a). The overall assessment for each stream monitored is rated to be “attaining (all or some 

uses),” “not attaining,” “impaired,” or “inconclusive” (ADEQ, 2009b).

The Salt Watershed occupies 6,242 square miles or five percent of the state’s land area. The 

watershed is defined by the Salt River drainage area from its headwaters to Granite Reef Dam, 

excluding the Verde River drainage area. The Salt River drainage area below Granite Reef Dam is 

included in the Middle Gila Watershed. Tonto NF encompasses about 43 percent of this 

watershed, or approximately 2,686 square miles. There are no unique waters (a surface water 

classified as an outstanding state resource) identified within this basin. Principal land uses are 

recreation, grazing and silviculture, with mining centralized in the Miami-Globe area (ADEQ, 

2009b). 

Of the 283 miles of streams assessed on the Tonto NF, 176 miles were classed as attaining water 

quality standards for all or some uses (12 reaches) and the 82 miles (ten reaches) were assessed as 

impaired or not attaining water quality standards for one or more uses. The assessment of the 

remaining stream miles were inconclusive (ADEQ, 2009b). 

Water quality standards for Christopher Creek was assessed as impaired by ADEQ for phosphorus 

and E. coli bacteria. Two reaches of Tonto Creek were assessed as impaired due to low dissolved 

oxygen and exceedences of phosphorus. Five Point Mountain, a tributary to Pinto Creek was 

determined impaired due to copper. Three reaches of Pinto Creek were determined to be “not 
Chapter 3 – Affected Environment and Environmental Consequences

78 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

attaining” water quality standards for some uses due to copper, and one reach was found impaired 

due to selenium. Salt River between Pinal Creek and Roosevelt Dam was found impaired due to 

suspended sediments and another reach of the Salt, between Stewart Mountain Dam and Verde 

River was found to be impaired due to low dissolved oxygen levels (ADEQ, 2009b).

Of the 22,015 lake acres assessed, Saguaro Lake (1025 acres) was assessed as attaining water 

quality standards for some uses. Apache and Canyon lakes (2640 acres) were assessed as 

impaired due to low dissolved oxygen. Roosevelt Lake (18350 acres) was assessed as attaining 

some uses by ADEQ, but was found impaired by EPA for mercury in fish tissue (ADEQ, 2009b).

Perennial waters associated with the Tonto Creek Drainage include Tonto, Horton, Christopher, 

Haigler, Spring, Rye, Slate, Gun, and Greenback creeks and the Tonto Arm of Roosevelt Lake. 

Noxious and invasive weeds found within this fourth code watershed include yellow starthistle, 

Malta starthistle, bull thistle, Russian thistle, sweet resinbush, dalmatian toadflax, Russian 

knapweed, black mustard, Saharan mustard, and wild mustard. 

Other perennial waters associated with Salt River include, Pinal, Pinto, and Cherry Creeks, Salt 

River through the Salt River Wilderness, and the Salt Arm of Roosevelt Lake. Saharan mustard, 

bull thistle, Canada thistle, quackgrass, sweet resinbush, yellow starthistle, diffuse knapweed, 

saltcedar, and tree of Heaven are common weeds in this watershed. Apache, Canyon, and Saguaro 

lakes and Lower Salt River are all located downstream from Roosevelt Lake. Listed weed species 

identified in this watershed include fountain grass, buffelgrass, Malta starthistle, and saltcedar.

The Verde Watershed is roughly 6,624 square miles and represents approximately 6 percent of 

the state’s land area. The Verde River drainage area defines this watershed and about 20 percent 

of it is on the Tonto NF (1,297 square miles). Flows from the Verde River are regulated at two 

reservoirs – Horseshoe and Bartlett lakes. A small portion of the Phoenix Active Management 

Area (AMA) is on the Verde Watershed portion of the Tonto NF (ADEQ, 2009b).

Of the 156 miles of streams in the Verde Watershed located on the Tonto NF that were assessed, 

76 miles were attaining water quality standards for all or some uses (seven reaches) and 70 miles 

(three reaches) were assessed as impaired or not attaining designated uses. Of the 4,355 lake acres 

assessed, Bartlett Lake (2375 acres) was assessed as attaining all uses while Horseshoe 

Reservoir’s assessment was inconclusive (ADEQ, 2009b). Saltcedar is the major invasive plant 

on the Upper Verde. 

On the Tonto NF, the East Verde River between Ellison Creek and American Gulch was assessed 

as impaired due to selenium exceedances while the East Verde reach between American Gulch 

and the Verde River was found impaired due to arsenic and boron. Verde River between West 

Clear Creek and Fossil Creek, about half being on the Tonto NF, was assessed as “not attaining” 

due to turbidity (ADEQ, 2009b).

Perennial streams and lakes located on the Tonto NF within the Verde Watershed include Lower 

Verde and East Verde rivers, Camp, Sycamore, Tangle, Red, Wet Bottom, and Fossil creeks, 

Horseshoe and Bartlett lakes. Noxious and invasive weeds found in the Lower Verde Watershed 

include Malta starthistle, brome grasses, fountain grass, and saltcedar. 

The Upper Gila Watershed occupies 7,354 square miles a little more than 6 percent of the state 

total. The watershed is defined by the Gila River drainage area from New Mexico to Coolidge 

Dam (San Carlos Reservoir). The Tonto NF occupies only 0.01 percent of the total basin area or 
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 79

roughly 98 square miles. There are no perennial or intermittent streams inventoried that are 

within the Tonto NF. None of the stream reaches on the Tonto NF in this watershed were assessed 

(ADEQ, 2009b).

The Middle Gila Watershed is defined by the Gila River area below Coolidge Dam in the east to 

Painted Rock Dam in the west. This does not include the Santa Cruz River and San Pedro River 

drainages and the Salt River above Granite Reef Dam. The Salt River below Granite Reef Dam is 

included in this watershed, instead of the Salt River Watershed, because the water in the Salt 

River normally is diverted at Granite Reef Dam into a system of canals and becomes 

hydrologically disconnected from its natural fluvial system. This watershed occupies 12,249 

square miles or 11 percent of the total land area within the state. Outside the urban Phoenix area, 

livestock grazing is the primary land use. The Tonto NF occupies approximately 552 square miles 

of this basin, about 0.05 percent of the total watershed. Groundwater basins within the Middle 

Gila Watershed include the Phoenix AMA, Agua Fria, and Dripping Springs. There are no unique 

waters identified in these watersheds (ADEQ, 2009b). Over four million people live in this 

watershed, or 60 percent of the state’s population.

Of the 60 miles of streams on the Tonto NF that were assessed in this watershed, 28 miles (two 

reaches) were in full attainment and 17 miles (two reaches) were inconclusive. The remaining 

15 miles, two reaches on Queen Creek, were assessed as impaired due to exceedances of the 

copper standard (ADEQ, 2009b).

Perennial streams within this watershed located on the Tonto NF include Queen Creek, Arnett 

Creek, and Devils Canyon, all located on the Globe and Mesa ranger districts, while New River, 

Bishop Creek, Squaw Creek, Cave Creek, and Seven Springs Wash are on the Cave Creek Ranger 

District. Noxious and invasive weeds identified in this watershed include buffelgrass, wild 

mustard, Malta starthistle, and saltcedar fountain grass, oleander, and sweet resinbush. 

Ground Water Quality

Ground water basins recognized by the Arizona Department of Water Resources are being 

examined by ADEQ for regional ground water quality. Systematic, grid-based random sampling 

of ground water monitoring wells is conducted to investigate potential nonpoint source pollution 

impacts on ground water quality. Currently, none of the Tonto NF basin studies have been 

completed; however, monitoring is continuing in the Tonto, Upper Salt and Lower Salt River 

basins. Samples from some of these wells have shown exceedances in arsenic, fluoride, hardness, 

nitrate, gross alpha (radioactive particles), uranium and total dissolved solids (ADEQ, 2004).

Arizona’s Pesticide Contamination Prevention Program is intended to prevent contamination of 

ground water, soil, and the vadose zone from pesticides used in agriculture. The Ground Water 

Protection List includes a list of 152 active ingredients that have the potential to pollute 

groundwater in Arizona. Another 37 pesticides are on the list of banned pesticides. Twenty-two 

of the 189 pesticides listed or banned have an Aquifer Water Quality Standard, including 

Glyphosate and picloram (listed) and 2,4-D and Silvex (banned). Glyphosate and picloram, are 

listed for use in this proposed action. They are currently approved for use by ADOT along federal 

and state highways including those on the Tonto NF. Glyphosate is currently approved for use in 

“housekeeping” (recreation and administrative sites) on the Tonto NF. Five wells within the 

Tonto NF were monitored for pesticides between 1993 and 2002 with results in all wells below 

the lab detection limit (ADEQ, 2004).
Chapter 3 – Affected Environment and Environmental Consequences

80 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Environmental Consequences

Proposed Action: Integrated Vegetation Management

Direct and Indirect Effects

Under this alternative, hand-grubbing, pulling or mechanical treatment of weeds would occur. 

Mechanical treatments would occur to a lesser extent than under alternative 2 but higher than 

alternative 1. Soil disturbance associated with this activity may contribute in the short term to 

sedimentation in water courses adjacent to the site. Manual treatments would cause less 

disturbance on soils than mechanical treatments, though for both, the long term improvements 

would outweigh the short term effects of the treatments. 

Burning/torching would be used on the same acres in all three alternatives. Again, the long term 

improvements from the treatment would outweigh the short term effects of the treatment.

Cultural treatments (planting native vegetation) is proposed in this alternative as well as 

alternative 2, but not alternative 1. The effects of planting native species would help to control the 

spread of invasive species and provide ground cover which would be a favorable improvement.

Biological treatments are proposed for this alternative and alternative 2 but not alternative 1. The 

biological treatment most likely to affect water quality would be livestock grazing by cattle, 

goats, etc. While the proper timing and intensity of grazing could increase sediment in the 

streams in the short term, the long term effects could be favorable.

Herbicide use is proposed to treat the greatest number of acres in this alternative. Again, while 

removing invasive species over large areas could have a short term effect on soil loss causing an 

increase in sedimentation the overall net result would be better protection of the soils through 

improved groundcover.

Overall, by removing target invasive plants, currently a minor component of forest vegetation, 

and by preventing their spread, native vegetation will be favored that will serve to intercept 

contaminants and sediments creating a more stable watershed. 

Both direct and indirect water quality impacts can result from the use of herbicides to control 

vegetation. Direct adverse effects could result from improper applications for the following 

situations: (1) Waters receive herbicide from spray, drift, or spills; or (2) Large-scale applications 

to impervious surfaces and compacted soils, combined with runoff, could transport herbicides to 

water resources. However, the herbicides proposed for use, based on the mitigation measures and 

BPA’s required for their application, are expected to have little to no negative impact on water 

quality. Utilization of mitigation measures and safety practices (appendices D and G) will further 

reduce the potential adverse effects. To ensure proper application and to avoid problems related 

to runoff, all herbicide applications would be conducted by or under the supervision of a Certified 

Pesticide Applicator. 

The ability of herbicides to leach to ground water depends on several factors including depth to 

ground water, soil depth to bedrock, soil texture, and soil pH. Except for some perennial streams 

and springs, the depth to ground water on the Tonto NF is greater than 40 inches. About ten to 

twenty percent of soils on the Tonto NF are less than 20 inches deep to bedrock. These soils often 

occur along with exposed bedrock. Fractures in bedrock could allow herbicides to reach ground 

water. Herbicide applications to areas with extensive bedrock should be avoided. About ten 
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 81

percent of the soils are coarse textured, occurring mostly on steep slopes or near drainages. These 

soils are more likely to allow leaching of herbicides than finer textured soils. Soil pH can affect 

leaching. The leaching potential for most of the herbicides considered for use is moderate at pH 7, 

but less at pH 6. The dominant soils on the Tonto NF have a neutral reaction (pH 6.6 to 7.3). A 

substantial number, however, have pHs below 6.6 or above 7.3. Leaching potential could be 

higher in soils above a pH of 7.3 so pH should be considered when determining where to apply 

herbicides (U.S.F.S. Tonto NF, 1979; & U.S.D.A. Soil Survey Division Staff, 1993). 

In areas of shallow bedrock, the potential for herbicides leaching through the soil profile and 

reaching water is greatest. However, several mechanisms prevent or retard the migration of 

herbicides through the soil profiles. These mechanisms include chemical precipitation, chemical 

degradation, volatilization, physical and biological degradation, biological uptake, and 

adsorption. Clays and organic matter in the soil adsorb (adhere to) certain organic compounds 

such as herbicides (e.g., glyphosate). As a result, the ability of herbicides to leach through the soil 

column for entry to ground water is reduced significantly.

A soil monitoring study of soil leaching conducted in Montana supports this expectation. For two 

years, soil was monitored for presence of clopyralid and picloram. Clopyralid was applied at 

37 sites. Clopyralid was not detected below two inches at any site 30 days after application. 

Picloram was also monitored at 42 sites and one year after application detected at 16 ppb (parts 

per billion) at 2.1 inches with a trace detected below ten inches (Rice, et al., 1992). Based on the 

results of this study, pesticide use proposed in this document is likely to have little or no effect on 

water quality through soil leaching.

Table 7. Potential for surface runoff and leaching for proposed herbicides (Senseman, 

2007)

Common Name 

of Herbicide

Solubility in Water 

(mg/L) Half Life in Soil Potential for Surface Runoff

Potential for 

Leaching

Aminopyralid ** 2,480 (unbuffered)

20 to 32 Days, 

activity may carry 

over for one year

Moderate only 

on sites with 

high soil clay 

content; 

otherwise low.

Low

Chlorsulfuron 587 (pH 5) – 31,800 

(pH 7) 40 Days Low

Moderate at 

pH 7, but less 

at pH 6

Clopyralid 1,000 (acid) – 300,000 

(salt) 40 Days Low Moderate

Dicamba 4,500 (acid) –

720,000 (salt)

Less than

14 Days* Low Low to Moderate

Glyphosate 15,700 (pH 7) –

900,000 (salt, pH 7) 47 Days Low Low

Imazapic 2,200 120 Days Low Low

Imazapyr 11,272 (pH 7) 25 to 142 Days* Low Low
Chapter 3 – Affected Environment and Environmental Consequences

82 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Common Name 

of Herbicide

Solubility in Water 

(mg/L) Half Life in Soil Potential for Surface Runoff

Potential for 

Leaching

Metsulfuron 

methyl

548 (pH 5) – 2,790 

(pHo7) 30 Days Low

Moderate at 

pH 7, but less 

at pH 6

Picloram 430 90 Days* Moderate High

Sethoxydim *** 4,000 5 to 25 Days

High, but is 

degraded by 

sunlight in 1 to 

several hours

Low, due to 

rapid 

breakdown by 

soil microbes

Sulfometuron 

methyl 10 (pH 5) – 300 (pH 7) 20 to 28 Days Low

Moderate at 

pH 7, but less 

at pH 6

Triclopyr 23 (ester) – 2,100,000 

(salt) 30 Days Not Available Not Available

* May persist significantly longer under conditions of low soil moisture and rainfall and soil types.

** Data for Aminopyralid from Aminopyralid Risk Assessment (Durkin, 2007) 

*** Data for Sethoxydim from Tu, et al., 2001.

The design of this alternative includes streamside buffer zones, described in appendices D and G, 

in which only certain herbicides may be used. Herbicide applications will be limited to spot and 

small scale treatments and will exclude aerial applications. Aquatically labeled formulations of 

glyphosate, imazapyr and triclopyr can be safely applied up to the edge of water. These 

herbicides are short-lived, not translocated through soil, and do not have other properties that 

would prevent safe use within the riparian zone. Chlorsulfuron, clopyralid, dicamba, metsulfuron, 

picloram, sethoxydim, and sulfometuron cannot be safely applied adjacent to water and will not 

be used within the streamside buffer zone. A general permit from Arizona’s Department of 

Environmental Quality will be necessary before any use of herbicide that could reach “waters of 

the U.S.”

The known area infested with invasive plant species (other than brome species and wild oats) 

currently is less than 1 percent of the forest. Consequently, the amount of herbicides needed to 

treat this relatively small area each year is expected to be low. This further reduces the risk of 

surface or ground water contamination. In addition, average annual precipitation on the Tonto NF

is about 20 inches per year with only a few areas receiving more than 25 inches annually. 

Consequently, there is less likelihood of herbicide translocation to ground water with this 

relatively low level of precipitation. 

Cumulative Effects

Other past, present, and future activities that would potentially contribute to cumulative effects to 

water quality in the project area include livestock grazing, off-road vehicle use, dispersed 

recreation and road maintenance. The effect of this proposal, in combination with other activities 

on the forest, would result in little or no significant issues. Since the herbicides considered for use 

in this EA are short-lived, degrade in the environment, and have mitigations and BMPs that will 

reduce the chances of herbicides moving into water, it is concluded that the typical application 

rates proposed under the proposed action will not contribute to any significant cumulative 

impacts to water quality.
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 83

Alternative 1: No Action (continue ongoing treatments)

Direct and Indirect Effects

The No Action alternative would result in an increase in size and density of existing invasive 

plant populations. New populations and new species of invasive exotic plants would become 

established. These increases would cause declines in native grasses and herbs and eventually 

decrease the watershed conditions in the project area. Sheley and Petroff (1999) noted that the 

spread of noxious and invasive weeds influences watershed conditions in several ways including 

a loss of effective ground cover in the form of plants and litter, a corresponding increase in soil 

erosion and sedimentation, and a gradual loss in the productive capacity of the soil. Reduced 

ground cover leads to reduced infiltration which causes less water storage and subsurface flow, 

adversely affecting the quality and quantity of the surface water (Olsen, 2001). If allowed to 

expand, populations of species associated with riparian areas such as saltcedar and giant reed 

would potentially dry up springs and other riparian areas by lowering surface water tables through 

transpiration (U.S.F.S. IITF, 2004). 

Treatments currently used, such as hand pulling and grubbing activities, would increase soil 

disturbance, surface runoff, and sediment yield in small localized areas to nearby streams in the 

short term, while long term effects would show no improvement compared to the other two 

alternatives.

Burning/torching would be used on the same acres in all three alternatives. Again, the long-term 

improvements from the treatment would outweigh the short-term effects of the treatment.

There would be no cultural treatments (planting native vegetation) in this alternative. As 

compared to the other two alternatives, the net loss of the favorable native vegetation would lead 

to an increase in invasive species eventually leading to a decrease in the watershed condition.

Biological treatments are not proposed for this alternative or alternative 2. The biological 

treatment most likely to affect water quality would be livestock grazing by cattle, goats, etc. In 

the short term, there would be less soil disturbance by livestock than in the proposed action, 

However, the biological treatment proposed in the proposed alternative would provide better 

control over the noxious weed populations.

Herbicide use is proposed to treat only 1,300 acres in the two alternatives as compared to 

9000 acres in the proposed action. This will lead to a continued spread of noxious plant 

communities and an overall decline in watershed condition as described above. 

Cumulative Effects

Other past, present and future activities that would potentially contribute to cumulative effects to 

water quality in the project area include livestock grazing, off-road vehicle use, dispersed 

recreation and road maintenance. The effect of this action, in combination with other activities on 

the Forest, would result in little or no significant effects.

Selection of this alternative would result in an increase in erosion and reduction in water quality.

Alternative 2: Integrated Vegetation Management Excluding the Use of Herbicides. 

Direct and Indirect Effects

Alternative 2 involves only non-chemical methods of plant control. Effects to water from the nonherbicide weed control alternative would likely be higher than those shown in the other two 
Chapter 3 – Affected Environment and Environmental Consequences

84 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

alternatives. Weed populations would possibly spread at a slower rate than in alternative 1. 

Increases in soil disturbance, surface runoff, and sediment yield in small localized areas to nearby 

streams in the short term would result from current treatments such as hand pulling and grubbing.

Because this alternative does not include the use of herbicides, there will be no effects to water 

quality from herbicide use. 

Under this alternative, hand-grubbing, pulling or mechanical treatment of weeds would occur. 

Mechanical treatments would occur to a greater extent than in the other alternatives causing more 

disturbance to soils. Soil disturbance associated with this activity may contribute in the short term 

to sedimentation in water courses adjacent to the site. Manual treatments would cause less 

disturbance on soils than mechanical treatments, though for both, the long term improvements 

would outweigh the short term effects of the treatments. 

Burning/torching would be used on the same acres in all three alternatives. Again, the long-term 

improvements from the treatment would outweigh the short term effects of the treatment.

Cultural treatments (planting native vegetation) is proposed in this alternative as well as the 

proposed action. The effects of planting native species would help to control the spread of 

invasive species and provide ground cover which would be a favorable improvement.

Biological treatments are not proposed for this alternative or alternative 1. The biological 

treatment most likely to affect water quality would be livestock grazing by cattle, goats, etc. In 

the short term, there would be less soil disturbance by livestock than in the proposed action, 

However, the biological treatment proposed in the proposed alternative would provide better 

control over the noxious weed populations.

Herbicide use on the forest will be limited to 1,300 acres, under projects previously approved, if 

either alternative 1 or 2 is selected for implementation. The proposed action proposes to use 

herbicides on up to 9,000 acres of weed infestations across the forest annually. This will lead to a 

continued spread of noxious plant communities and an overall decline in watershed condition as 

described above. 

Cumulative Effects

Other past, present and future activities that would potentially contribute to cumulative effects to 

water quality in the project area include livestock grazing, off-road vehicle use, dispersed 

recreation and road maintenance. If this effect, in combination with other activities on the forest, 

would result in significant effects is not known.

Selection of alternative 2 would result in an increase in erosion and reduction in water quality.

Vegetation Communities and Fire Regimes

Affected Environment

Elevations range from 1,260 feet near Granite Reef Dam on the Salt River to 7,914 feet on the 

Mogollon Rim near Promontory Butte. This large difference in elevation has resulted in diverse 

assemblages of plant communities. Ten broad vegetation communities have been identified based 

on data from existing Terrestrial Ecosystems Surveys (TES) (869,238 acres), mapping for various 

forest projects (807,423 acres), and the Arizona Gap Vegetation Program (1,287,771 acres). In 
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 85

some cases the existing Terrestrial Ecosystems Survey data were modified for use in project 

mapping and is included in the acreage for project mapping. The vegetation map is not intended 

to be site-specific and represents grouping of similar vegetation types. Each vegetation polygon 

may contain major inclusions of dissimilar vegetation types (U.S.F.S., Tonto NF, 1979; U.S.F.S.,

Tonto NF, 1985a; U.S.F.S., Tonto NF, 2005a; and U.S.G.S. Biological Resources Division, 1998. 

See map 7 and table 8, below.

Table 8. Vegetation types present within the Tonto National Forest, and known weeds

Terrestrial Ecosystems Acres within 

the Tonto NF

Percent of 

Tonto NF

Total Weed 

Species

Known 

Acres 

Mapped

Streamside Vegetation 49,021 2% 26 653 

Sonoran Desert 771,286 26% 18 865 

Velvet Mesquite Grasslands 359,061 12% 14 97 

Piñyon/Juniper/Oak Woodlands 654,122 22% 25 122 

Alligator Juniper Savannas 85,275 3% 4 1 

Alligator Juniper Woodlands 43,034 1% 5 12 

Chaparral and Chaparral Woodlands 634,685 21% 27 86 

Arizona Cypress Woodlands 23,002 1% 2 1 

Ponderosa Pine Forests 241,602 8% 21 8,228 

Mixed Conifer Forests 61,642 2% 6 12,884 

Private Land/Disturbed Land 22,663 1% 32 49 

Water 19,913 1% 2 25 

Total Area* 2,965,322 10% 23,024 

* Acreage includes some private lands within the boundary of the Tonto National Forest. A map of 

general potential natural vegetation types on the Tonto NF is included in the appendix. Characteristics 

of the vegetation types in the project area are described below, with discussions of their natural fire 

regimes. Weed infestation information is based on data as of December, 2011. Weed totals do not include 

acres of annual grasses which can vary widely from year to year depending on climatic conditions.

Descriptions of fire regimes are general because of fire’s tremendous variability over time and 

space (Whelan, 1995). Nevertheless, fire regime is a useful concept because it brings a degree of 

order to a complicated body of knowledge (Lyon, et. al., 2000).

On the Tonto NF there are five basic fire regimes that exist in varying combinations. They are: 

Coniferous (Ponderosa Pine and Mixed Conifer Forests), Piñyon-Juniper (Pinyon/Juniper/Oak 

Woodlands, Alligator Juniper Woodlands, Arizona Cypress Woodlands), Chaparral and Oak 

Woodlands (Chaparral and Chaparral Woodlands), Grasslands (Velvet Mesquite Grasslands, 

Alligator Juniper Savannas), and Deserts (Sonoran Desert). Fire affects each of these regimes 

differently based on variations in frequency, duration, intensity, and type of fire. The ecological 

effects of fire vary enormously according to the time of year; the quantity, condition, and 

distribution of the fuel; the prevailing climatic conditions; the duration and intensity of the fire, 

the slope, aspect, and elevation; and the type of vegetation and soil.

Streamside Vegetation (no specific fire regime) – This is associated with the stream channels 

that were broad enough to be mapped at the scale of TES mapping (1:24,000). It includes riparian 
Chapter 3 – Affected Environment and Environmental Consequences

86 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

vegetation as well as some upland vegetation found on higher stream terraces. Small, isolated 

areas of riparian vegetation have not been delineated for this project. At present 350 acres of 

noxious weeds have been mapped in this vegetation type and include bull thistle, jointed 

goatgrass, Malta starthistle, quackgrass, Saharan mustard, and yellow starthistle. The extent of 

saltcedar has not been mapped at present but is known to be a dominant vegetation type along 

much of the upper and lower Salt River and grows as scattered trees along the Verde River.

Native trees and forbs still dominate the riparian vegetation growing along the Verde River. 

Saltcedar probably occupies less than five percent of the total canopy of vegetation.

Fire regime – No specific fire regime exists for this vegetation type. The fire regime is often 

influenced by the surrounding upland vegetation type.

Sonoran Desert (deserts fire regime) – These ecosystems are found at the lowest elevation on the 

forest. The key indicator species are giant saguaro (Carnegia gigantea), little-leaf paloverde 

(Parkinsonia microphyllum), creosote bush (Larrea tridentata tridentata), triangle-leaf bursage 

(Ambrosia deltoidea), jojoba (Simmondsia chinensis), pricklypear cactus (Opuntia phaeacantha), 

white brittlebush (Encelia farinosa), flat top buckwheat (Eriogonum fasciculatum), and trace 

amounts of threeawn, (Aristida spp.) and false mesquite (Calliandra eriophylla). The understory 

is normally very sparse with few or no perennial grasses. At present 336 acres of noxious weeds 

have been mapped in this vegetation type including black and wild mustard, buffelgrass, fountain 

grass, brome grasses, Malta starthistle, oleander, Saharan mustard, and sweet resinbush. While the 

extent has not been mapped, annual bromes are known to inhabit large expanses of the Sonoran 

Desert.

Deserts fire regime - Seasonal weather and grazing influence fire potential in deserts 

(Wright & Bailey, 1982). A wet year produces large quantities of grasses and forbs, which 

provide fuel to carry fire. The Sonoran Desert only has enough ground cover to carry fire 

after occasional unusually wet growing seasons (Humphrey, 1974). Thomas (1991) estimates 

that intervals between fires prior to European American Settlement were as short as 3 years in 

some desert grasslands and more than 250 years in dry areas such as the Sonoran Desert.

Regrowth following fire depends on the availability of moisture. If burning is followed by a 

wet season, production of perennial grasses and some forbs may increase (Wright & Bailey,

1982). Studies have shown substantial differences between species and also complex 

interaction among available moisture, grazing, and plant species (Cable, 1967; Wright &

Bailey, 1982). Several studies report increase in exotic annual plants, including red brome 

and filaree, after fire in desert ecosystems; both frequency and intensity of fires may have 

increased since the introduction of these annual plants (Rogers & Steele, 1980; Young &

Evans, 1973).

Velvet Mesquite Grasslands (grasslands fire regime) – These semi-desert grasslands occur

above the Sonoran Desert and below the woodland zone. The key indicator species are velvet 

mesquite (Prosopis velutina), catclaw acacia (Acacia greggii), pricklypear cactus (Opuntia spp.), 

desert ceanothus (Ceanothus greggii), catclaw mimosa (Mimosa aculeaticarpa), shrubby

buckwheat (Eriogonum wrightii), and jojoba. Blue paloverde can be found on the hotter/drier 

parts of this type. Redberry juniper (Juniperus coahuilensis) and turbinella oak (Quercus 

turbinella) may occur on cooler/moister sites. Common graminoids include blue grama 

(Bouteloua gracilis), hairy grama (B. hirsuta), black grama (B. eriopoda), sideoats grama (B. 

curtipendula), curly mesquite (Hilaria belangeri), bush muhly (Muhlenbergia porteri), cane 
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 87

beardgrass (Bothriochloa barbinodis), threeawn, tridens (Tridens spp.), desert stipa 

(Achnatherum speciosum), green sprangletop (Leptochloa dubia), tobosa (Pleuraphis mutica) and 

a variety of forbs. At present three acres of noxious weeds have been mapped in this vegetation 

type and include Malta starthistle, fountain grass, and Russian thistle.

Alligator Juniper Savannas (grasslands fire regime) – These are normally found at the same 

elevation as the piñyon/juniper/oak woodlands and are often intermixed with them. They consist 

of grasslands with scattered alligator junipers. The canopy coverage of juniper is normally less 

than 10 percent. Key herbaceous species include sideoats grama, blue grama, hairy grama, 

threeawn, bottlebrush squirrel tail, mutton bluegrass, and annual bromes. In areas with high 

amounts of clay at the surface, plant composition includes western wheatgrass (Agropyron 

smithii), and vine mesquite (Panicum obtusum). Arizona piñyon pine, Arizona white oak, Emory 

Oak, turbinella, sugar sumac, skunkbush sumac, and desert ceanothus occur only in isolated 

patches or beneath junipers acting as nurse trees. Utah juniper may occur at lower elevations or 

on southern exposures. At present 32 acres of noxious weeds have been mapped in this vegetation 

type and include Canada thistle, jointed goatgrass, and yellow starthistle.

Grasslands fire regime - The fire regime of the grasslands prior to settlement and 

development for agriculture was one of stand-replacing fires on a short return interval, every 

year in some areas (DeBano, et al., 1998; Wright & Bailey, 1982). Prairie fires were often 

vast, burning into the forest margins and preventing tree invasion of grasslands.

Burning maintains dominance by fire-adapted grasses and forbs, maintains the productivity of 

grasslands, and grass quality and availability are improved because the fire removes dead 

plant material and improves access to new growth. Generally, grass yields increase because 

removing cover and darkening the soil surface allows it to warm more quickly and stimulate 

earlier growth. 

Piñyon/Juniper/Oak Woodlands (piñyon-juniper fire regime) – This vegetation type occurs 

above the velvet mesquite grassland zone but below the ponderosa pine zone and is very diverse. 

At lower elevations the overstory is dominated by redberry juniper (Juniperus coahuilensis) and 

turbinella oak. At mid-elevations Arizona piñyon (Pinus fallax) becomes a major overstory 

species and Utah juniper (Juniperus osteosperma) may occur along with redberry juniper and 

turbinella oak. At higher elevations alligator juniper (Juniperus deppeana) replaces the other 

juniper species and is co-dominant with Arizona piñyon, turbinella oak, Emory oak (Quercus 

emoryi) and Arizona white oak (Q. arizonica) Common shrubs include birchleaf mountain 

mahogany (Cercocarpus montanus glaber), skunkbush sumac (Rhus trilobata), sugar sumac (R. 

ovata), desert ceanothus (Ceanothus greggii), shrubby buckwheat, hollyleaf buckthorn (Rhamnus 

crocea), beargrass (Nolina microcarpa), and red barberry (Mahonia haematocarpa). Crucifixion 

thorn (Canotia holacantha) occurs on highly calcareous soils. The cover of trees and shrubs can 

be highly variable ranging from open woodlands with an herbaceous understory to dense stands 

with nearly a closed canopy. Understory grasses can include blue grama, hairy grama, sideoats 

grama, curly mesquite, plains lovegrass (Eragrostis intermedia), cane beardgrass, green 

sprangletop, bottlebrush squirreltail (Elymus elymoides) piñyon ricegrass (Piptochaetium 

fimbriatum), Junegrass (Koeleria macrantha), mutton bluegrass (Poa fendleriana), and threeawns. At present 241 acres of noxious weeds have been mapped in this vegetation type and 

include Malta starthistle, Dalmatian toadflax, diffuse knapweed, jointed goatgrass, Russian 

knapweed, sweet resinbush, and yellow starthistle.
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88 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Prominent overstory species include but are not limited to: piñyon pines, Utah juniper, one seed 

juniper, and alligator juniper. Because of the open nature of piñyon-juniper woodlands, grasses 

and shrubs are prominent in the understory. In pre-settlement times, stand-replacing fires 

probably occurred at average intervals of less than 50 years. Where livestock grazing reduced 

herbaceous fuels, fire occurrence decreased, and piñyon–juniper woodlands expanded. 

Alligator Juniper Woodlands (piñyon-juniper fire regime) – These are normally found at the 

same elevation as the alligator juniper savannas and are often intermixed with them. The canopy 

coverage of overstory trees is greater than 10 percent. Arizona piñyon occurs but is most often 

associated with nurse junipers. Emory oak, Arizona white oak, sugar sumac, skunkbush sumac, 

and desert ceanothus may also occur. Key herbaceous species include sideoats grama, blue grama, 

hairy grama, threeawn, bottlebrush squirrel tail, mutton bluegrass, and annual bromes. Most of 

this vegetation type was formerly an alligator juniper savanna. Grazing pressure and lack of fire 

have allowed junipers and other woodland species to encroach into this type. Most of the junipers 

are less than 50 years old. Herbaceous forage is normally much less than in the alligator juniper 

savanna type. In the past, many areas of alligator juniper woodland have been treated (pushed) 

with management objective to maintain grasslands and to increase available forage. In recent 

years, these treated areas have not been maintained and, as a result, the areas now have dense 

stands of younger junipers. At present, two acres of noxious weeds have been mapped in this 

vegetation type. Yellow starthistle is the only species identified.

Arizona Cypress Woodlands (piñyon-juniper fire regime) – This community type is found in 

the same elevation as chaparral vegetation. The key indicator species is Arizona cypress 

(Cupressus arizonica arizonica). There is normally a dense understory of shrubs including 

manzanita, sugar sumac, desert ceanothus, mountain mahogany, banana yucca, hollyleaf 

buckthorn, Wright buckwheat, turbinella oak, Wright silktassel, Arizona piñyon, and Palmer oak 

(Quercus dunnii). The herbaceous layer is normally sparse, producing little forage. Much of this 

vegetation type contains shrubs palatable to livestock and wildlife, including mountain mahogany 

and desert ceanothus. About 40 percent (9,000 acres) of this type burned during the 2004 Willow 

Fire, leaving this area vulnerable to invasion by noxious weeds. At present, no noxious weeds 

have been mapped in this vegetation type. 

Piñyon-juniper fire regime -The impact of fire depends on tree density and the amount of

grass and litter in the stand. Post-fire, piñyon-juniper woodlands present a landscape of dead 

trees and nearly bare soil. Annual plants become established in a few years. These are 

followed by perennial grasses and forbs. Invading plants often include weedy species, 

especially on bare soil. Reestablishment of junipers and shrubs typically takes 4 to 6 years 

and shrubs are replaced by new stands after 40 to 60 years (Barney & Frischnecht, 1974; 

Koniak, 1985).

Chaparral and Chaparral Woodlands (chaparral and oak woodlands fire regime) – Typically 

these types are found at the same elevations as the piñyon/juniper/oak woodlands. The chaparral

type is dominated by low growing shrubs. Overstory trees are sparse or absent. Dominant shrub 

species include, turbinella oak, point leaf and pringle manzanita (Arctostaphylos pungens and A. 

pringlei), silktassel, mountain mahogany, desert ceanothus, skunkbush sumac, Wright silktassel 

(Garrya wrightii), hollyleaf buckthorn and evergreen oaks. Herbaceous vegetation is normally 

sparse. Chaparral woodlands are similar to chaparral, but contain an overstory cover of trees of 

up to about 15 percent. Overstory trees can include Arizona piñyon, redberry juniper, Utah 

juniper, alligator juniper, Emory oak, Arizona white oak, and occasionally ponderosa pine. 
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 89

Chaparral woodlands often occur intermixed with dense piñyon/juniper/oak woodlands. At 

present 63 acres of noxious weeds have been mapped in this vegetation type and include, diffuse 

knapweed, jointed goatgrass, fountain grass, sweet resinbush, tree of heaven, and yellow 

starthistle.

Chaparral and Oak Woodlands fire regime - These regimes often include broad-leafed 

shrub and tree species that are well adapted to fire. These vegetation types are notorious for

frequent, fast moving, stand replacing fires. Both chaparral and oak resprout vigorously after 

fire and also establish from seed. In chaparral, stand-replacing fires occur every 30 to 60 

years. Frequency is reduced in areas where grazing has reduced surface fuels.

Annual and perennial herbs flourish after fire in chaparral, along with seedling and 

resprouting shrubs. Herbs are gradually eliminated as the dense overstory of large shrubs 

matures (DeBano, et al., 1998). Burning at 20 to 30 year intervals maintains a diverse mixture 

of species. If the fire return interval is longer, sprouting species will dominate, reducing plant 

species diversity (Paysen, et al., 2000).

Ponderosa Pine Forest (coniferous fire regime) – This vegetation type occurs above the 

piñyon/juniper/oak woodlands, but below the mixed conifer type. The dominant overstory species 

is ponderosa pine (Pinus ponderosa scopulorum). Other common species include alligator 

juniper, Arizona white oak, and Emory oak. Gambel oak (Quercus gambelii) normally occurs on 

some cooler sites. Arizona piñyon may occur on warmer/drier sites. Other species may include 

pointleaf manzanita, pringle manzanita, mountain mahogany, New Mexico locust (Robinia 

neomexicana), and desert ceanothus. The understory is normally sparse but may include blue 

grama, sideoats grama, mutton bluegrass, and dryspike sedge (Carex foenea), goldenrod 

(Solidago spp.), and a variety of other perennial forbs. At present 165 acres of noxious weeds 

have been mapped in this vegetation type and include bull thistle, jointed goatgrass, Scotch 

thistle, and yellow starthistle. 

Mixed Conifer (coniferous fire regime) – This vegetation type occurs on the highest elevation of 

the Tonto NF. Indicator species present include white fir (Abies concolor), Douglas fir 

(Pseudotsuga menziesii glauca), ponderosa pine, Gambel oak, and New Mexico locust. Arizona 

white oak, Emory oak, alligator juniper, and pointleaf and pringle manzanita may occur on 

warmer/drier areas. The overstory is normally dense and the understory of herbaceous vegetation 

is sparse but may include mutton grass and longtongue muhly (Muhlenbergia longiligula). At 

present, no noxious weeds have been mapped in this vegetation type.

Coniferous fire regime - Important dominant trees include but are not limited to ponderosa 

pine, Southwestern white pine, Douglas fir, and white fir. In past centuries these forests had a 

variety of fire regimes; understory, mixed-severity, and stand replacement. At low elevations, 

understory fires maintained large areas of ponderosa pine and Douglas-fir in an open, parklike structure for thousands of years prior to the 1900s. Fire on these sites increased grass and 

forb production. Pre-settlement mean fire return intervals (the average number of years 

between fires at a given location) range from less than ten years (Arno, 1976) to more than 

300 years (Romme, 1980). Forests with a multistoried structure, including dense thickets of 

young conifers, were more likely to experience stand-replacing fire than open, park-like 

stands. Stand-replacing fires were unusual in ponderosa pine during pre-settlement times but 

are now more common because of increased surface fuels and “ladder” fuels (shrubs and 
Chapter 3 – Affected Environment and Environmental Consequences

90 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

young trees that provide continuous fine material from the forest floor into the crowns of 

dominant trees).

In pre-settlement times, repeated understory fire maintained an open forest with grasses and 

forbs on the forest floor and scattered patches of conifer regeneration. Fires occasionally 

killed large, old trees, creating openings where the exposed mineral soil provided a seedbed 

suitable for pine reproduction (Weaver, 1974). Regenerating stands often produce large 

volumes of browse until the tree canopy closes, 25 or more years after fire.

Environmental Consequences

Table 9: Effects of various weed control methods on vegetation communities

Treatment Type and 

Acreage Description of Treatment

Manual

Proposed Action – 400 acres

Alternative 1 – 200 acres

Alternative 2 – 400 acres

Manual treatments may involve extremely slight disturbance to 

native vegetation. Any disturbance is short-term (likely less than 

one year), and of limited extent. The net long-term effects are 

generaly positive for weed control and benefical to plant 

communities. 

Mechanical 

Proposed Action – 500 acres

Alternative 1 – 0 acres

Alternative 2 – 2000 acres

Many mechanical treatments involve some degree of 

disturbance to surrounding native vegetation. Most disturbance 

is short-lived (one to two years) and restricted to a relatively few 

acres (less than 0.1 percent) on the forest in the vicinity of weed 

infestation. Mechanical control of some rhizomatous species 

may not be effective in controlling those species and could 

actually result in their spread. Other species are difficult to 

control because of the persistence of large seed banks once 

weeds have become established. The net long-term effects are 

generally positive for weed control but some localized increases 

in weed populations.

Burning/torching

Proposed Action – 2,000 

acres

Alternative 1 – 2,000 acres

Alternative 2 – 2,000 acres

Burning can be effective in controlling weeds, especially annual 

weeds. It is especially effective in removing large quantities of 

seeds of annual weeds. Some invasive species are difficult to 

control using fire and fire can also impact non-target species and 

result in increased soil erosion. There may be some short-term 

(one to two years) negative effects on native plants in a few 

areas but the long-term net effect of burning is likely to be 

positive for weed control plant communities.

Cultural

Proposed Action – 2,000

acres

Alternative 1 – 0 acres

Alternative 2 – 2,000 acres

Cultural practices are designed to establish desirable plants in 

order to prevent infestation by invasive plants. There may be 

some short-term disturbance to native vegetation in areas 

prepared for seeding establishment but the long-term effect is an 

expected decrease in weed populations.
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EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 91

Treatment Type and 

Acreage Description of Treatment

Biological

Proposed Action – Will be 

used

Alternative 1 – Will not be 

used

Alternative 2 – Will be used

Biological controls involve grazing animals, approved insects 

and pathogens to control weeds. The use of biological controls, 

except for grazing animals, would have little to no direct on 

native vegetation. The use of grazing animals, however, could 

have both short and long-term effects on vegetation. Grazing 

that is heavy enough to control weeds may also severely reduce 

the cover of native species. The net effect of using biological 

controls, except for grazing animals, is likely to be positive. The 

net effects of grazing animals could be positive with strict 

controls or negative if native vegetation is affected.

Herbicide 

Proposed Action – 9,000

acres

Alternative 1 – 1,300 acres

Alternative 2 – 1,300 acres 

Herbicides that selectively target only invasive species and/or 

are used in spot treatments would allow native species to 

recover which should reduce soil erosion and enhance nutrient 

cycling. Possible negative effects of herbicide application 

include the potential that some non-target species would be 

affected. If negative effects occur they are likely to be localized 

(less than 0.3 percent of the forest) and short-term (one to two 

years) The net effects of herbicides would be some possible 

short-term negative effects to native plants but long-term 

positive effects to plant communities.

Total Acres Treated

Proposed Action – 13,900

acres

Alternative 1 – 3,500 acres

Alternative 2 – 7,700 acres

Comparison of Alternatives

Direct and Indirect Effects

General Effects on Vegetation-The proposed action is more likely than the other alternatives to 

limit or reduce the spread of invasive plants because more acres per year could be treated and 

more control methods are available (see treatment comparisons in above table). Assuming that 

native plant communities will replace tap-rooted invasives after treatment, vegetation 

communities should remain stable or be enhanced. Alternative 1 would be the least effective in 

preventing the spread of invasive plants since this alternative would treat the fewest acres and 

have the fewest methods available for treatment. Alternative 2 would be somewhat intermediate 

in effectiveness. The control of exotic annual grasses such as red brome will be difficult under all 

alternatives given the relatively small areas treated annually, ranging from 3,500 acres in 

alternative 1 to 13,900 acres in the proposed action, versus the hundreds of thousands of acres 

that can be infested during wet winters. Even with the use of herbicides, it may not be possible to 

adequately control non-native annual grasses to significantly reduce fine fuels. Also, it may not 

be possible to stock up cattle numbers quickly enough to adequately control non-native annual 

grasses. Infestation of invasive annual grasses is so extensive on the Tonto NF that herbicide use 

is not practical except in key areas such as highway rights of way. The risk of wildfire caused by 

a buildup of annual grasses will remain high. Infestations of red brome can lead to unnaturally 
Chapter 3 – Affected Environment and Environmental Consequences

92 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

severe wildfires, especially within the Sonoran Desert. These wildfires can cause unnaturally high 

erosion due to loss of ground cover.

The direct effects of treatments depend on the type and extent of treatment. Physical removal 

(manual and mechanical) will result in localized, short-term disturbance. The most disturbance 

occurs in the proposed action with the least occurring in alternative 1. Burning may result in some 

localized, short-term (one to two years) negative effects but prescribed burning to manage 

noxious weeds should result in controllable conditions for fire frequency, duration, and intensity 

based on environmental conditions used during implementation, thus resulting in fairly 

predictable ecological effects on native vegetation. The effects of burning are same for all 

alternatives. The direct effect of cultural practices may be some slight, short-term disturbance in 

areas prepared for seeding. The effects are the same in the proposed action and alternative 2 but 

there would be no cultural practices in alternative 1. The use of biological controls (occurring in 

the proposed action and alternative 2) would have little to no direct effects on native vegetation 

quality unless grazing animals are used. If grazing animals are used heavy grazing could affect 

non-targeted native vegetation. The direct and indirect effect of using herbicides varies. Broadcast

treatment by non-selective herbicides could destroy native species at a higher rate than weeds. On 

the other hand, herbicides that selectively target only invasive species and/or are used in spot 

treatments would allow native species to recover. More acres would be treated under the 

proposed action than the other alternatives and the overall negative direct effects of this 

alternative while small are slightly greater than the other alternatives. The proposed action would 

have the greatest direct negative impact on native vegetation because of a greater area of 

disturbance associated with treatments, however, the effects to vegetation are likely to be 

temporary (less than two years) and localized (less than 0.5 percent of the forest). Alternative 1

would have the least direct disturbance to native vegetation while alternative 2 would be 

intermediate. 

Effects on Vegetation Communities by Fire Regime - The ecological effects of fire on each fire 

regime vary enormously according to the time of year; the quantity, condition, and distribution of 

the fuel; the prevailing climatic conditions; the duration and intensity of the fire, the slope, aspect, 

and elevation; and the type of vegetation and soil. Given all the variables associated with fire 

regimes, the effects from invasive plants can be widely variable ranging from very minimal to 

very large depending on the magnitude of infestation and overall ecological conditions. Although 

the proposed action is more likely to control invasive weeds than the other alternatives, the effects 

on some fire regimes may not be measurable. 

The Coniferous fire regime (ponderosa pine and mixed conifer forests), with the exception of 

areas burned during the 1990 Dude Fire, may not be measurably affected by the presence of 

invasive weeds at the present time or during the ten-year planning period. Fires are now more 

common because of increased surface fuels and “ladder” fuels (shrubs and young trees that 

provide continuous fine material from the forest floor into the crowns of dominant trees) These 

factors may completely overwhelm the relatively small presence of invasive weeds (less than 

0.1 percent of the type). The area burned in during the Dude Fire has an altered fire regime. The 

area is in an early seral state with the mixed conifer and ponderosa pine vegetation replaced by 

alligator juniper, oaks, and manzanita with an understory of seeded, non-native weeping 

lovegrass. The Dude Fire area represents more than 99 percent of the mapped population of 

weeping lovegrass. In some places, the density weeping lovegrass could lead to an increased risk 

of wildfire, however, in most places within the Dude Fire, the cover of weeping lovegrass in 
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EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 93

decreasing (U.S.F.S., Tonto NF files, Dude Fire photo points 1990 to 2009), being reduced by 

competition with overstory trees and shrubs.

The Piñyon-juniper fire regime (pinyon/puniper/oak woodlands, alligator juniper woodlands, 

Arizona cypress woodlands), is highly diverse (more than 50 Habitat Types occur in the 

Southwest {U.S.F.S., Southwestern Region, 1997}) and the impact of fire depends on tree density 

and the amount of grass and litter in the stand. The effects of invasive weeds can also be highly 

variable ranging from minimal to large. Most areas in most years have only a small presence of 

invasive weeds (less than 0.1 percent of the type); however, in years following wet winters, some 

areas can have a heavy covering of annual grasses, especially red brome which is most likely to 

occur in lower elevation woodlands and areas with bare soil. The presence of annual grass is the 

major factor in altering fire frequency and intensity and it is only minimally affected by 

treatments under different alternatives given the hundreds of thousands of acres potentially 

affected versus a maximum of 13,900 acres treated under the proposed action.

The Chaparral and Oak Woodlands fire regimes (chaparral and chaparral woodlands) are

notorious for frequent, fast moving, stand replacing fires which occur every 30 to 60 years. The 

occurrence of invasive plants is low in these types (less than 0.1 of the area). The main effect of 

invasive plants occurs when surrounding vegetations types become infested with annual grasses 

following wet winters and fire spreads from these types into chaparral as happen in the 2005 Cave 

Creek Complex Fire (Norm Ambos, personal observation). None of the alternatives are likely to 

have more than a minimum effect on the distribution of red brome.

The Grasslands fire regime (velvet mesquite grasslands, alligator juniper savannas), prior to 

settlement, was one of stand-replacing fires on a short return interval, every year in some areas 

(DeBano, et al., 1998; Wright & Bailey, 1982). Prairie fires were often vast, burning into the 

forest margins and preventing tree invasion of grasslands. Burning maintains dominance by fireadapted grasses and forbs, maintains the productivity of grasslands, and grass quality and 

availability are improved because the fire removes dead plant material and improves access to 

new growth. The largest effect on this fire regime is the presences of non-native annual and 

perennial grasses which occur mostly in wet years and can affect hundreds of thousands of acres. 

This can lead to an increase in the current fire frequency which is thought to be much lower than 

the natural frequency. Fires in grasslands generally increase productivity but in some cases, such 

as a hot fire occurring when grasses are drought stressed, can lower productivity. None of the 

alternatives are likely to have more than a minimum effect on the distribution non-native grasses. 

The Desert fire regime (Sonoran Desert) historically was one of long fire return intervals, more 

than 250 years. Seasonal weather and grazing influence fire potential in deserts (Wright & Bailey,

1982). A wet year produces large quantities of grasses and forbs, which provide fuel to carry fire. 

The Sonoran desert only has enough ground cover to carry fire after occasional unusually wet 

growing seasons (Humphrey, 1974). Several studies report increase in exotic annual plants, 

including red brome and filaree, after fire in desert ecosystems; both frequency and intensity of 

fires may have increased since the introduction of these annual plants (Rogers & Steele, 1980; 

Young & Evans, 1973). Most of the dominant plants in the desert communities (palo verde, 

saguaro, and other cacti, for example) are readily killed by fire. The presence of annual grass is 

the major factor in altering fire frequency and intensity and it is only minimally affected by 

treatments under different alternatives given the hundreds of thousands of acres potentially 

affected versus a maximum of 13,900 acres treated under the proposed action. None of the 

alternatives are likely to have more than a minimum effect on the distribution of red brome. Other 
Chapter 3 – Affected Environment and Environmental Consequences

94 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

invasive plants only occupy about 0.1 percent of the Sonoran Desert and are unlikely to alter the 

fire regime on a large scale.

Cumulative Effects

Other past, present and future activities may potentially contribute to cumulative effects on plant 

communities. Appendix I lists projects that may possibly impact the area. Almost all activities 

that have occurred, are occurring, or will occur could potentially impact populations of invasive 

weeds either by introducing seeds or portions of weeds into non-infested areas, creating 

conditions favorable for germination or spread, or by reducing native plants that serve to compete 

with weeds. The primary activities which may affect vegetation include road use and 

construction, vegetation management (primarily fuels reduction), range management, fire 

suppression (primarily fire lines and safety zones), recreation management (primarily OHV use), 

and land and mineral resources. Recreation can disturb soils and create conditions conducive to 

the introduction of invasive species. Recreationists, their vehicles and pets can act as vectors for 

the dispersal of weed seeds from other areas. Likewise, livestock grazing can contribute to the 

introduction and spread of non-indigenous plants by transporting seeds into uninfested sites, 

disturbing the soil and preferentially grazing native plants over weed species (Belsky & Gelbard, 

2000). On areas of the forest where grazing occurs, livestock may continue to contribute to the 

spread of invasive species. Fire suppression may also contribute to the introduction and spread of 

nonnative plants by creating favorable growing conditions and through the transportation of seed 

sources. All the activities listed above have at least some potential to increase the spread of 

invasive plants. All the alternatives can potentially limit or reduce the spread of non-native plants. 

The proposed action would be the most effective in controlling the spread followed by alternative 

2 and then alternative 1.

Invasive Plants

Affected Environment

Plant descriptions, origins, locations in Arizona, and effects on ecosystems can be found in 

appendix A.

Vectors of Spread

Livestock

1. Sheep brought onto driveways from farms in other parts of the state may carry weed 

seeds in their wool, especially since they are not sheared until they reach their summer range 

in the White Mountains (McKinney, 2005). Species such as fountain grass have been 

identified growing in the Heber-Reno Sheep Driveway in a tributary to Sycamore Creek in 

Round Valley, a site not easily accessed by vehicular traffic. Other species common in the 

valley that could be transported are buffelgrass, mustards, various grain seeds and weeds 

common in grain crops. Cattle permits where the herd spends time on lands other than the 

Tonto NF could bring new infestations onto the forest. 

2. Some base properties associated with term grazing permits have acreage devoted to 

raising some type of crop for livestock feed. These fields could have invasive plant 

infestations. If the crop is harvested and fed only on the private land, the weeds could be 

dispersed thru the manure of the livestock that have been fed and turned back onto the 

National Forest. If livestock are allowed access to the crop fields, they could transport weed
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EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 95

seeds and plant parts to other areas in their feet and on their coats. If the crop is harvested and 

baled for subsequent feeding in other areas, such as the National Forest, weed seeds can be 

scattered and trampled into the ground at the feeding site.

3. Forest Service livestock can also spread new infestations in the same way, if they are fed 

weed-infested hay.

4. Equipment brought in to do range improvement work can be contaminated with weed

seeds and plant parts, and spread weeds to project sites.

5. Recreational stock, or any animals brought in to do contract packing jobs for any type of 

project can bring weed seeds and plant parts in their feet, on their coats, or as manure, if they 

have eaten non-weed-free feed before coming onto the National Forest. Any feed brought in 

for them that is not weed-free can spread new weed infestations.

6. Picketed pack stock can remove vegetation from a campsite, leaving it open to noxious 

weed infestation. Also, any livestock concentration area, if in the vicinity of known 

infestations of weeds is vulnerable to invasion by those weeds.

7. If a pasture is known to have an infestation of noxious weeds, livestock can spread the 

infestation to new sites if they are in the pasture during the season when the plant is 

producing seeds.

Recreation

1. Recreational vehicles, such as two or four-wheel drive vehicles, ATVs, bicycles, or 

motorcycles can bring weed seeds and plant parts onto the forest from other sources. They 

can also spread existing infestations into new sites. ATVs commonly drive in the right-ofway along Hwy 188. Much of this right-of-way has had a Malta starthistle infestation for 

several years. When ATVs move from the right-of-way onto the forest road network, they are 

quite likely to spread Malta starthistle throughout the entire Tonto Basin.

2. Hikers can bring weed seeds in on their clothing, bootlaces, pack/camping/hunting 

equipment, or pets. These infestations are most easily found at trailheads, along trails, and at 

major trail destinations. But hikers are not confined to trails, so an infestation spread by this 

means can attain a large size before it is ever detected.

Road Construction and Maintenance

1. Road grading equipment can spread weed infestations along forest roads and highways, if 

it works from areas with infestations and grades into “clean” areas.

2. Fill dirt brought in can be a source of weeds. Also excess dirt removed from work sites 

can spread existing infestations elsewhere.

3. Revegetation seed mixes can contain noxious weed seeds. Containerized plants brought 

in from outside the project area can also contain weeds.

4. Mulch used to stabilize new road cuts can contain weed seeds.

5. Newly cleared areas created during road construction are especially vulnerable to new 

infestations from weeds growing near the project area. There are no existing plant 

populations to compete with any weed seeds that are blown in or brought in by other means.

6. Dirty equipment may bring in noxious weed plant parts and seeds.

Fire Management Activities

1. Equipment brought in to fight fires may bring weed seeds and plant parts to burned areas 

that are especially susceptible to infestation. This includes the entire gamut of vehicle types 
Chapter 3 – Affected Environment and Environmental Consequences

96 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

that are brought into areas of fire management activities: all types of trucks, ATVs, water 

tenders, office and other special use trailers for Incident Command Posts and fire camps, 

dozers, forklifts and other heavy equipment, and helicopters.

2. Fire staging areas may be established in or near existing infestations.

3. Hot Shot Bases and crew quarters may be infested with weeds that are transported to fires 

on fire fighters’ clothing and boots.

4. Post-fire seed mixes or mulch may be contaminated with noxious weeds.

5. Prescribed fire, if conducted in areas in poor vegetation condition, may cause an even

further decline in condition. This can leave areas such as perennial grasslands open to 

invasion and ultimate conversion to annual grasslands. Once this happens, it can be very 

difficult, if not impossible to reverse the situation and change back to a perennial grassdominated vegetation type.

Forest Management

1. Trucks and other equipment brought in to harvest timber or fuelwood may be 

contaminated with noxious weeds. This applies to both commercial and personal sales.

2. Prescribed burning of slash piles may leave them open to infestation of weeds from 

existing infestations in the vicinity.

3. Post-sale revegetation may bring in noxious weeds.

Wildlife

1. Wildlife may spread infestations to new sites if the infestations are growing in heavily 

used sites such as bedding or fawning grounds.

2. Wildlife such as elk can heavily graze meadows or riparian areas, leaving them open to 

infestation from nearby noxious weeds.

Lands

1. The Forest Service could acquire lands that have noxious weed infestations.

2. The Forest Service could trade lands where there are noxious weed infestations. By doing 

so, we would lose the ability to control the weeds.

Mining

1. Equipment brought in from off-site can bring in new infestations of weeds.

2. Large areas that have been laid bare are susceptible to infestation by noxious weeds.

Natural Vectors

1. Some weeds are adapted to disperse seeds using the wind. These plants either have light 

fluffy seeds that are easily airborne, or the entire plant breaks off when mature and “tumbles,” 

scattering seed along its path. Russian thistle and Saharan mustard are two examples of 

“tumbleweeds.” While tumbleweeds are usually blown across fairly level ground or downhill, 

dust devils are able to move weed propagules to higher elevations. 

2. Weeds that grow in riparian areas often have seeds that are transported by water. When 

deposited in fresh silt on a drainage, the seed germinates.
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 97

3. Some weeds are palatable to wildlife. Seeds may be eaten in addition to vegetative plant 

parts. These seeds may even require a “scarification” process, or treatment of the tough seed 

coat with an acid, in order to germinate.

Environmental Consequences

Proposed Action: Integrated Vegetation Management

Direct and Indirect Effects

The proposed action most completely fulfills the need for control of invasive species on the 

forest. All of the integrated vegetation management tools are available for creation of long-term 

treatment strategies of all types of weeds. Multiple-year treatments will be required, as for the 

other alternatives. 

Hand-pulling, small-scale mechanized treatments and small-scale prescribed burns will continue 

to be treatments of choice for small infestations. Volunteer groups are ideal for participation in 

this type of treatment, both to remove early-detected/small infestations, and to educate their 

members. 

Larger prescribed burns and flaming (use of fire to sear plants, such that water within their cells 

boils thereby destroying the cells and killing the plant) can be used for larger infestations that are 

spreading rapidly, such as Malta and yellow starthistle. These techniques are most effective when 

used in combination with herbicide applications. We should be able to confine Malta starthistle to 

boundaries given in the weed description section, and gradually beat back the infestation to 

smaller and smaller areas through time. Some revegetation may be necessary in areas where the

infestation has become especially dense.

Perennial weeds with extensive root systems that contain large amounts of carbohydrate reserves 

will be treated more effectively with systemic herbicides.

Cultural treatments such as seeding with native species in large areas that have been treated with 

one of the control methods will serve to provide vegetative competition for invasive plants. This 

will help to prevent their germination, as some of them require abundant sunlight to germinate.

Established root systems of neighboring plants will take up soil moisture, making it less available 

for invasive plants.

Biological control methods will work only for larger infestations, and will be used in conjunction 

with other control methods. As populations of target invasive plants decline, biocontrol agent 

populations also decline and there is a lag time for the biocontrol to “catch up” to have a serious 

impact on invasive plants as populations rebound. This method is best used to weaken and reduce 

very large infestations.

All of the above methods will need to take place over a period of many years to achieve results of 

containment or eradication. 

Cumulative Effects

Most other ongoing actions have the potential to bring new invasive weeds onto the forest from 

remote sources, or to spread existing infestations. Implementation of the proposed action should 
Chapter 3 – Affected Environment and Environmental Consequences

98 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

allow the Tonto NF to keep on top of new infestations with ongoing education programs, and to 

treat them quickly with the best available method.

Alternative 1: No Action (continue ongoing treatments)

Direct and Indirect Effects

Under current management, weed infestations will be expected to continue to grow out of control. 

Cumulative Effects

Since most other ongoing actions have potential to bring or spread weeds, the Tonto NF would 

suffer from increasing acres and species of invasive plant infestations every year. Existing 

treatments are not keeping up with the spread of existing infestations. Some rural communities, 

such as Young and Tonto Basin would be particularly impacted by the uncontrolled spread of 

invasive species on the National Forest, since it would negate any efforts they took to treat their 

private lands for infestations. 

Alternative 2: Integrated Vegetation Management Excluding the Use of Herbicides

Direct and Indirect Effects

Under this alternative, larger prescribed burns and biological control would be allowed. This 

alternative would slow the rate of spread of some weed species. However, because many 

infestations would not be completely controlled or eliminated with the types of control allowed 

under this alternative, long-term expansion of noxious weeds into suitable habitat would be 

expected. Some species with large potential for expansion (such as starthistles) or with extensive 

root systems (such as camelthorn and Russian knapweed) would not be controlled with tools this 

alternative provides.

Burning and mechanical treatments, the main methods available for large-scale treatment of 

infestations, may affect non-target species after several years of repeated treatment. These 

methods are usually fairly non-species specific, so may require extensive restoration after 

treatment. 

Effects due to biocontrol would be the same as for the proposed action.

Cumulative Effects

Without the use of herbicides, the Tonto NF would be missing a very effective tool for managing 

spreading infestations in a cost-effective manner. As for alternative 1, weed infestations would 

grow, but not as rapidly.

Endangered, Threatened, Candidate and Sensitive Plant Species

Affected Environment

Plant lists used for this report are the January 2007 U.S. Forest Service Southwestern Region 

Sensitive Plant List (U.S.F.S., 2007), and the U.S. Fish and Wildlife website (USFWS, 2011a). 

The project area contains populations of 27 and federally-listed and sensitive plant species. While 

no threatened or candidate species are found within the project area, two endangered species are 
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 99

present: Arizona cliffrose and Arizona hedgehog. Of the total number of sensitive species, two 

species listed in the table below have never been found on the forest, but are on the Forest Service 

Region 3 Sensitive Plants List. They should be on the survey list for any project proposal due to 

their proximity to and potential occurrence on the forest. 

Table 10. Known and potential endangered and sensitive plant species that are known or 

suspected to occur on the Tonto National Forest

 

1 T = Threatened , E = Endangered, S = Sensitive species according to Forest Service Region 3 listing.

Scientific 

Name

Common 

Name Status1 Watershed/Location

Weeds in 

Habitat (Yes, 

No, Unknown)

Invasive 

Species in or 

near Habitat

Ehinocereus 

triglochidiatus 

var. arizonicus 

Arizona 

hedgehog E

Queen Creek, Upper 

Salt/ Top of the World, 

Superstitions, Apache 

Peak

Yes Malta 

starthistle

Purshia 

subintegra

Arizona 

cliffrose E Verde/Horseshoe Dam, Chalk Mountain Yes Malta starthistle

Abutilon 

parishii

Pima Indian 

mallow S

Superstitions, possibly 

near Mercury Mine in 

Mazatzals

Unknown Fountain grass, 

oleander

Actaea 

arizonica

Arizona 

bugbane S Salt River/ Sierra Anchas Unknown

Agave 

delamateri

Tonto Basin 

agave

S Tonto, Salt/Tonto 

Basin, Deer Cr. Yes Brome spp.

Agave 

murpheyi

Hohokam 

agave

S Salt/

Tonto Basin Yes Brome spp.

Arenaria 

aberrans

Mt. 

Dellenbaugh 

Sandwort

S Yavapai & Gila 

Counties. Rare. Unknown

Carex 

chihuahuensis

Chihuahuan 

sedge S Upper Salt/ Reynolds Creek Unknown

Carex ultra Giant sedge S Verde/ Tangle Cr,

Verde River Unknown

Yellow 

sweetclover, 

Arundo, 

saltcedar

Cirsium parryi

ssp.

mogollonicum

Mogollon 

thistle S Unknown Unknown

Erigeron 

anchana

Mogollon 

fleabane S

Upper Salt, Verde/ 

possible face of 

Mogollon Rim

Unknown Yellow 

starthistle
Chapter 3 – Affected Environment and Environmental Consequences

100 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Erigeron 

piscaticus

Fish Creek 

fleabane S Salt River/ Fish Creek Unknown

Eriogonum 

ripleyii

Ripley’s wild 

buckwheat S Verde/Horseshoe, 

Chalk Mtn Yes

Malta 

starthistle, red 

brome

Heuchera 

eastwoodiae

Eastwood 

alum root S

Salt, Verde, Tonto/ 

Tonto Creek, Houston 

Creek, Pine Creek, and 

Parker Creek, First 

Water Canyon, Devil’s 

Chasm, Workman 

Creek 

Unknown

Heuchera 

glomerulata

Arizona 

alum root S Upper Salt, Gila/ Pinal Mtns Unknown

Lotus 

alamosanus

Alamos deer 

vetch S Salt, Queen Cr/ Superstition Mtns. Unknown

Lotus mearnsii 

var. 

equisolensis

Horseshoe 

Deer Vetch S Horseshoe/Lime Creek area

Yes

Malta 

starthistle, red 

brome

Mabrya 

acerifolia

mapleleaf 

false 

snapdragon

S

Lower Salt, Queen Cr/ 

Horse Mesa Dam road, 

Fish Creek Hill, 

Goldfield Mountains, 

Canyon Lake, Hewitt 

Ridge Canyon, Fish 

Creek Canyon, La 

Barge Canyon, Bluff 

Spring Canyon, Peralta 

Canyon, and Tortilla 

Creek.

Unknown

Packera 

neomexicana 

var. toumeyi

Toumey 

groundsel S Pinal Mountains Unknown

Penstemon 

nudiflorus

Flagstaff 

beardtongue S Tonto Cr/ Buckhead Mesa Unknown

Perityle 

gilensis var. 

gilensis

Gila rock 

daisy S

Not known to grow on 

the Tonto NF. It does 

grow on the Coconino 

NF near the Mogollon 

Rim, which abuts the 

Tonto NF

Unknown

Perityle 

gilensis var. 

salensis

Salt River 

rock daisy S Salt River Canyon cliffs Unknown

Perityle 

saxicola

Fish Creek 

rock daisy S Salt/Fish Creek Unknown
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 101

Sources for information: USFWS, 2011a; Lutch, 2000; USFS SW Region, 2007.

Of the 29 species that are considered special status taxa, 9, or roughly 31 percent, are documented 

to have weeds within or adjacent to known populations. Brome grasses and probably other exotic 

cool-season annual grasses are known to grow throughout the Sonoran Desert where regionallylisted agaves grow. Agave species do not normally weather wildfire well, which exotic grass 

species are adapted to and tend to bring to the Sonoran Desert. 

Arizona Hedgehog Cactus Echinocereus triglochidiatus var. Arizonicus

Federal: Endangered

This robust perennial cactus occurs on the Tonto NF in the vicinity of Highway 60 from Top of 

the World to Pinto Creek, on Apache Peak north of Globe, and in the southeastern corner of the 

Superstition Wilderness. It has dark green cylindroid stems that occur as single stems, or more 

frequently, clusters of stems. Flowers are bright red or crimson. It occurs within Interior 

Chaparral and Madrean Evergreen Woodland communities at elevations ranging from 3,300 to 

5,700 feet. Preferred habitat is found on parent materials of igneous origin, primarily Schultze 

Granite and Apache Leap Tuff (Dacite); plants occurring on the Pinal schist and Pioneer 

formations are found only in proximity to the preferred parent materials and where the formations 

are expressed as exposed bedrock (AZGFD, 2003). No critical habitat has been identified for this 

species. 

Primary threats include collection, mining, off-highway vehicle creation of unauthorized roads 

and trails, and road construction.

Arizona Cliffrose Purshia subintegra Federal: Endangered

Arizona Cliffrose is a perennial shrub, growing from 3 to 6 feet tall and generally wider than tall.

As a genus, cliffroses are morphologically variable and this can create identification problems 

when P. subintegra occur in proximity to P. stansburiana (e.g., Verde Valley and Horseshoe 

areas). This species is restricted to nutrient-deficient, calcareous limy-tuff soils derived from

Tertiary lacustrine deposits. Crucifixion-thorn is the most common plant associate. 

Subpopulations at the Horseshoe Lake site occur at elevations between 2,100 and 2,700 feet. No 

critical habitat was identified or designated for this taxon at the time of listing. Listing occurred 

Phlox amabilis Arizona 

phlox S Tonto Cr./ Christopher Creek Unknown

Polygala 

rusbyi

Hualapai 

milkwort S

With endangered 

cliffrose, 

Horseshoe/Lime Creek 

area

Unknown

Rumex 

orthoneurus

Blumers 

dock S Sierra Anchas Unknown

Salvia amissa Aravaipa 

sage

S Upper Salt/ Devil’s 

Chasm, PB Creek Unknown

Thelypteris 

puberula var. 

sonorensis

Aravaipa 

woodfern S Near Roosevelt Lake,Four Peaks area Unknown
Chapter 3 – Affected Environment and Environmental Consequences

102 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

under the former genus Cowania. A Recovery Plan was developed for this species in 1994. It did 

not address the threat of invasive species.

Monitoring conducted in the early 1990s showed seedlings of this species to be rare and also 

extremely slow-growing. They typically germinate in April, and have the driest months of the 

year (May and June) to become established. Deer were observed to contribute as much to 

browsing of Arizona cliffrose plants as domestic livestock under the annual spring grazing season 

that was used at that time. The cliffrose population on Chalk Mountain was never affected by 

cattle, probably because of the difficult footing and sparse vegetation on that topographic feature. 

Malta starthistle infestations in the Horseshoe area have been identified and mapped in close 

vicinity to the endangered Arizona cliffrose vegetation assemblage, which includes three other 

local endemic sensitive plant species: Ripley wild buckwheat, Horseshoe deer vetch, and 

Hualapai milkwort. The Cave Creek Complex Fire of 2005 only stopped short of burning through 

these species’ habitat because the white substrate in which they grow does not support a dense 

vegetative groundcover. However, a fairly recent Malta starthistle infestation may expand to the 

white Tertiary lakebed sediment where these endangered and sensitive species grow (Fenner, 

personal observations).

Pima Indian Mallow Abutilon parishii Status: Sensitive

This herbaceous perennial is presently known from 84 populations in 17 mountain ranges. Its 

occurrence in Arizona is primarily within the south-central and southeastern part of the state. This 

species has a woody base and herbaceous branches that can grow up to three feet tall from a 

woody rootstock. One aid to identification is the presence of dead stems up to one meter high, 

with empty fruit capsules that persist throughout the winter. This species occurs in mesic 

situations in full sun within higher elevation Sonoran Desert scrub, desert grassland, and Sonoran 

deciduous riparian forest. Typical localities are on rocky hillsides, cliff bases, lower side slopes 

and ledges of canyons among rocks and boulders. Slopes can exceed 45 degrees. It can occur on 

flat secondary terraces in riparian zones, but typically not in canyon bottoms. The majority of the 

Arizona populations are in the Santa Catalina Mountains. There are two documented locations of 

this plant on the Tonto NF: near the Mercury Mine in the Mazatzal Mountains (AZGFD, 2000a), 

and on the south shore of Canyon Lake, near the Apache Trail. The first locality is questionable. 

It was based on a collection by Eastwood in 1929, but there is confusion in field notes as to 

collection site location. This identification needs verification. It is disjunct from the Tucson area 

populations and is in questionable habitat. Van Devender searched the area in September, 1991,

and did not find appropriate habitat (AGFD, 2000a). A voucher specimen for the second location 

is in the Tonto NF herbarium.

Two populations in Mexico were eliminated after wildfire carried by the exotic invasive plant 

buffelgrass, as reported by C. D. Bertelsen to Arizona Game & Fish Department in 2000

(AZGFD, 2000a).

Arizona Bugbane Actaea arizonica Status: Sensitive

This herbaceous perennial occurs in central Arizona, and is the only species of this genus in 

Arizona. It was originally listed as a candidate species for federal listing under the name 

Cimicifuga arizonica. After the Conservation Strategy for Arizona bugbane was approved in 

1999 (U.S.F.S. et al., 1998), U.S. Fish & Wildlife Service removed this species from its 

Candidate list (Federal Register, 2000).
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EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 103

Plants average three to six feet in height with large, long-petioled lower leaves and small sessile 

upper leaves. Small white petal-less flowers clustered on flower stalks make this plant very 

conspicuous when in bloom. This species occurs within moist, forested areas near perennial 

streams, intermittent streams or seeps between 6,000 and 8,300 feet in elevation. Rich fertile soils

high in humus are typical. Surrounding vegetation is generally mixed conifer with an understory 

of deciduous shrubs and trees that is often dense and shady. This species is often the dominant 

understory species where found. It appears that a high level of humidity is typical at many of the 

Arizona populations. The distribution of Arizona bugbane includes Bill Williams Mountain, Oak 

Creek, West Fork of Oak Creek, and West Clear Creek (AZGFD, 1999).

The only known populations on the Tonto NF are associated with Workman Creek and Cold 

Springs Canyon in the Sierra Ancha Mountains. Potential habitat exists in unsurveyed areas in the 

Sierra Anchas. Arizona Game and Fish Department’s plant abstract for Arizona bugbane

summarizes information to date on locations of this plant (AZGFD, 2008).

Tonto Basin Agave Agave delamateri Status: Sensitive

This is a large suckering agave with very tall, open, unfruited flower stalk and a dense rosette. 

The flower stalk has a few lateral branches that are perpendicular to the main stalk. It is usually 

found on south and southwest facing slope edges and atop benches, occasionally on northeast 

facing gentle slopes. It occupies cobbly and gravelly, deep and well-drained soils at elevations 

from 2,300 to 5,100 feet, and is often associated with prehistoric sites. About 90 clones are 

known from Young, Arizona to San Carlos Reservoir, foothills of Mazatzal and Sierra Ancha 

Mountains, the Sunflower area, and near Oak Creek. The greatest concentration of sites occurs 

along the south end of Tonto Creek near the northwest end of Roosevelt Lake in Tonto Basin

(AZGFD, 2003b). 

Hohokam Agave Agave murpheyi Status: Sensitive

This agave has a dense rosette with a short terminal spine. It has a branched flower stalk, but 

flowers abort and bulbils develop at the nodes. Agave murpheyi does not resemble any other 

agaves in its area. It is found in south-central Arizona in Sonoran Desert. It is found on gentle 

bajada slopes, benches or terraces above major drainages with prehistoric habitations and/or 

agricultural sites (that suggest tending), typically from 1,300 to 2,400 feet. It requires welldrained soil. There are about 60 known sites in Arizona (AZGFD, 2003c).

Mt. Dellenbaugh Sandwort Arenaria aberrans Status: Sensitive

This plant is a small perennial forb (growing to six inches in height) that is endemic to Arizona. It 

grows in north to north-central Arizona, with populations in Coconino, Mohave, Yavapai, and 

possibly Gila counties (AZGFD, 2004a). It occurs in oak and pine forests, and also among 

junipers at elevations from 5,500 to 9,000 feet. It flowers May to July, with small white fivepetalled flowers. It appears to grow in rocky habitats of ridges and canyon rims. 

Chihuahuan Sedge Carex chihuahuensis Status: Sensitive

This grass-like perennial is one of 50 species of Carex in Arizona. It is known from southeastern 

Arizona, New Mexico, and Mexico. It blooms from April to August at elevations from 3,600 to 

7,200 feet. It typically occupies north and northwest-facing slopes in wet soils in streambeds, wet 

meadows, cienegas, marshy areas, shallower draws in pine-oak forest and riparian woodland. It is 
Chapter 3 – Affected Environment and Environmental Consequences

104 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

often associated with pine oak forests and riparian woodlands. This sedge is known to occur in 

the Chiricahuas, Huachucas, Pinalenos, Santa Catalinas, San Luis Mountains, Rincons, 

Atascosas, Santa Ritas, and along the Santa Cruz River and San Bernardino Valley. It has been 

documented along Reynolds and Cherry creeks in the Sierra Ancha Mountains on the Tonto NF

(AZGFD, 2004b, Tonto NF herbarium).

Arizona Giant Sedge Carex ultra Status: Sensitive

This herbaceous perennial is one of approximately 50 species of Carex known from Arizona. It 

has the appearance of a bulrush, but is actually a large sedge with round, stout, erect culms (up to 

three to seven feet tall). It flowers late March through September and grows from 2,000 to 6,000 

feet in elevation. It often occurs on southeast-facing, shaded exposures in moist soil near 

perennially wet springs and streams. It is typically found in wet alluvial soil, sand and gravels, 

associated with aquatic/riparian woodlands or oak-piñyon woodlands. This species occurs in 

single patches in the Chiricahuas, Dragoons, Galiuros, Santa Ritas, Atascosa Mountains, 

Hieroglyphic Mountains, Aravaipa Canyon, and the Huachucas (several patches). There are two 

documented occurrences on the Tonto NF, both on the Cave Creek RD: along Tangle Creek 

(AZGFD, 2000b) and in Sycamore Creek just above its confluence with the Verde River. 

Mogollon Thistle Cirsium parryi spp. Mogollonicum Status: Sensitive

This short-lived perennial is one of thirteen species of Cirsium in Arizona. It was first discovered 

in 1987. Aids to identification include white corollas, margins nearly entire in mature leaves, and 

spinulose ciliate margins in leaves below head-bearing branches. It can reach a height of 

40 inches, has poorly developed spines and flowers that occur singly or several in a cluster. The 

stem branches only near the apex. It blooms from July through September and is pollinated by 

insects. Habitats include moist to very moist soils in the riparian understory of perennial streams 

at approximately 7,200 feet elevation. Coniferous forest surrounds the only known population in 

Arizona. The only locality known for this species is in Dane Spring Canyon near the Mogollon 

Rim on the Coconino NF. Barb Phillips, a botanist knowledgeable about this species, suspects it 

on the face of the Mogollon Rim on the Tonto NF (AZGFD, 2005a).

Mogollon Fleabane Erigeron anchana Status: Sensitive

This herbaceous perennial, also known as Sierra Ancha fleabane, occurs in central Arizona at 

elevations between 3,500 and 7,000 feet. This species forms a thick taproot with several crowded, 

thick caudex branches, with a total plant height of less than six inches. Erigeron anchana is the 

largest of the Erigeron pringlei complex. This plant blooms May through July (also noted 

through November) and inhabits rock crevices and ledges on boulders and vertical rock faces 

usually in canyons. It occurs at various exposures on igneous and metamorphic granites, in 

chaparral, piñyon-juniper and pine-oak forests. Its total range includes the Sierra Ancha, Mazatzal 

and Mescal mountains, and Pine Creek in northern Gila County. Occurrence records include 

Tonto Creek and Houston Creek on the Payson Ranger District (RD), Pine Creek on Tonto 

Natural Bridge State Park, and Parker Creek, First Water Canyon, Devil’s Chasm, Workman 

Creek, and one population at the south end of Sierra Ancha Experimental Forest all in the Sierra 

Ancha Mountains (AZGFD, 2003f).
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 105

Fish Creek Fleabane Erigeron piscaticus Status: Sensitive

This annual fleabane occurs in central Arizona and is one of at least 29 species of Erigeron 

occurring in Arizona. Aids to identification include the lack of lobed leaves and the presence of 

only sparse hairs on the upper stem. It flowers from spring through fall and occurs between 2,250 

and 3,500 feet in elevation. This plant typically occupies sandy alluvium substrates in canyon 

bottoms associated with riparian habitats near perennial streams. There are only four collections 

for this species in Arizona: two from Turkey Creek and Aravaipa Creek in Graham County and 

two from Fish Creek in the Superstition Mountains (Mesa RD of the Tonto NF). A survey at all 

of these sites in 1990 did not locate any plants (AZGFD, 2001a), but because it is an annual it 

may not emerge in some years. The last time this species was seen and collected was in 1979 by 

Peter Warren (AZGFD, 2001a).

Ripley’s Wild Buckwheat Eriogonum ripleyi Status: Sensitive

This woody perennial is known from central to northwestern Arizona. It is a mat-forming subshrub that grows 2 to 8 inches tall with numerous branches. It can be distinguished from other 

species in this genus in that it is low and heavily branched with short linear leaves. It flowers 

April through June and occurs at elevations from 2,000 to 6,000 feet. This species inhabits 

heavily calcareous soils in Sonoran Desert scrub and piñyon-juniper woodland. Known localities 

include Maricopa, Yavapai, Coconino, and Mojave Counties. Locations on the Tonto NF include 

populations near Horseshoe Lake and Chalk Mountain. The Horseshoe Lake and Cottonwood 

(Coconino NF) populations each have thousands of plants (AZGFD, 1997).

Eastwood Alum Root Heuchera eastwoodiae Status: Sensitive

This is a distinctive perennial herb in the Saxifragaceae family, with a rosette of rounded leaves 

with heart-shaped bases growing from a woody root crown. It is found only in central Arizona 

from 3,480 up to about 7,874 feet elevation, occupying moist slopes in ponderosa pine forests and 

canyons. It blooms from May to August. Plants reach heights of 20 inches; small flowers are 

yellowish green, often without petals. Leaves are dark green, roundish, finely haired and 

scalloped. Basal leaves occur on long leaf stalks. It is one of seven species of Heuchera in 

Arizona. Collection records include Oak Creek, West Fork of Oak Creek, Chevelon Creek, and 

Hunter Creek in the Bradshaw Mountains and the Verde Valley. On the Tonto NF, this plant has 

been observed along Christopher Creek and Barnhardt Pass on the Payson RD, along Reynolds 

Creek on the Pleasant Valley RD, and on Lime Creek and at the north end of the New River 

Mountains on the Cave Creek RD (AZGFD, 2005b). There is a specimen in the Tonto NF

herbarium taken from Big Pine Flat on the Tonto Basin RD.

Arizona Alum Root Heuchera glomerulata Status: Sensitive

This herbaceous perennial occurs in southeastern Arizona and New Mexico. It flowers from May 

to August at 4,000 to 9,000 feet in elevation. It is found on north-facing shaded rocky slopes, near 

seeps, springs, and riparian areas, often in humus soil. It is typically associated with oak and pine 

woodlands, ponderosa pine, and mixed conifer vegetative communities. Arizona Alum Root is 

known to occur in one locality on the Tonto NF, in the Pinal Mountains south of Globe, Arizona.

Other records in the state include the Pinaleno and Galiuro Mountains, and southern Apache, 

Greenlee and Navajo counties (AZGFD, 2004c). The most knowledgeable individual on this 

species (Elvander, 1992) notes that this “is a very difficult genus, highly variable at many levels 
Chapter 3 – Affected Environment and Environmental Consequences

106 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

and needing much additional research. It occasionally interbreeds with H. novomexicana in 

Greenlee, southern Apache, and southern Navajo counties and may be of hybrid origin.”

Alamos Deer Vetch Lotus alamosanus Status: Sensitive

This herbaceous perennial occurs primarily in southern Arizona and Mexico. It is a semi-aquatic 

plant that forms mats, clumps or carpets along streams. Stems are slender and numerous, 

somewhat sprawling and can be up to a foot high. This wetland obligate blooms in April and May 

at elevations between 3,500 to 5,500 feet and is restricted to stream banks in canyons. It is known

to occur under both open canopies and partial shade and exists in mud, damp to wet soil or sand,

in springs, seeps or streams. Occurrences in Arizona include the Nogales RD of the Coronado NF

in Santa Cruz County and the Superstition Mountains on the Mesa RD of the Tonto NF (Lutch,

2000).

Horseshoe Deer Vetch Lotus mearnsii var. equisolensis Status: Sensitive

This plant grows on white powdery gypseous limestone of Tertiary lakebed sediment where it 

occurs with several other rare plants adapted to this specialized habitat. However, unlike the other 

plants with which it grows, Horseshoe deer vetch is known only from the Horseshoe Reservoir 

area. It is low-growing, with yellow flowers borne on long stems, with a palmate cluster of fuzzy 

grey-green leaves in the axil of each flowering stem. Pods are up to an inch in length (Lutch,

2000).

Maple leaf False Snapdragon Mabrya acerifolia Status: Sensitive

This herbaceous perennial vine/forb is in the snapdragon family (Scrophulariaceae) and has white 

to greenish-white five-lobed tubular flowers. Leaves are dark green, downy, sticky and heart- or 

kidney-shaped. This plant grows prostrate, up to ten inches in length. It inhabits shaded cliffs and 

rock ledges from 1,800 to 3,350 feet elevation. It is a mat-forming plant with brittle stems. Stems 

often hang down from moist rock ledges. This species was formerly considered Maurandya 

acerifolia and earlier references are to this genus. This plant is known only from south-central 

Arizona. The type locality is from Fish Creek Canyon and most occurrence records are from side 

canyons of the Salt River. Locations in the Arizona Game and Fish Department Heritage Data 

Management System (AZGFD, 2005c) include occurrences along the Horse Mesa Dam Road 

(Salt River), in the Goldfield Mountains, Canyon Lake, and numerous localities in the 

Superstition Mountains including Hewitt Ridge Canyon, Fish Creek Canyon, Fish Creek Hill, La 

Barge Canyon, Bluff Spring Canyon, Peralta Canyon, and Tortilla Creek. 

Toumey groundsel Packera neomexicana var. toumeyi Status: Sensitive

This is a plant of infrequent occurrence in the Chiricahua, Huachuca, Santa Catalina, and Pinal 

mountains. It occurs mostly in pine forest at 5,200 to 9,200 feet in elevation. At the full species 

level, Packera neomexicana is perhaps the most abundant Packera in the southwest region. It is 

widespread in New Mexico, Colorado, Arizona, and Mexico (Rickett, 1970). The variety toumeyi 

is only found in Arizona. It grows to a height of from 2 to 28 inches; leaves are tomentose on the 

underside and hairless on the top; basal leaves are often purple on the underside (AZGFD, 

2004d). It has been documented in several locations on the Tonto NF: mostly in ponderosa pine 

forest between Young and Punkin Center, with one Tonto NF herbarium specimen from the Pinal 

Mountain Road on the Globe RD. 
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EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 107

Flagstaff Penstemon or Beardtongue Penstemon nudiflorus Status: Sensitive

This herbaceous perennial is known only from north-central Arizona. The type specimen is from 

Flagstaff (1884). It is found in dry ponderosa pine forests in mountainous regions south of the 

Grand Canyon at 4,500 to 7,000 feet in elevation. It blooms in the summer and is generally 

uncommon. It may be expected on dry soils of neutral pH. Many of the species in this genus are 

browsed. It is known to be associated with cinder hill type soils around Sunset Crater and Wild 

Bill Hill on the Coconino NF. The species occurs in Coconino, Gila, Mohave, and Yavapai 

counties. There is one occurrence for this species from the Tonto NF. It was collected in 1938 on 

Buckhead Mesa on the Payson RD. Other occurrences are known from the Coconino and Prescott 

NFs, with two locations southwest of Show Low (Lutch, 2000).

Gila Rock Daisy Perityle gilensis var. gilensis Status: Sensitive

This is a small perennial that grows on cliff faces, ledges, and rock outcrops. Based on 

information available to date, it is similar in appearance and growth form to P. gilensis var. 

salensis as described below. Information about this variety (as compared to var. salensis) is 

lacking. One study (Powell, 1973) hypothesized that geographical and morphological evidence 

indicates that var. gilensis originated from var. salensis via migration down the Salt River Canyon 

and through the establishment of autopolyploidy. It also noted distributional evidence and leaf 

morphology suggest that P. saxicola evolved from P. gilensis var. salensis as probably did P. 

gilensis var. gilensis. However, the only locality in Arizona in the Arizona Game and Fish HDMS 

database is a location on the Coconino NF near the face of the Mogollon Rim. More information 

is necessary to determine the status of this species on the Tonto NF.

Salt River Rock Daisy Perityle gilensis var. salensis Status: Sensitive

Like P. gilensis var. gilensis, this small perennial grows near seeps on cliff faces, ledges, and rock 

outcrops at 3,000 to 4,000 feet elevation. Plants typically reach heights of 12 to 28 inches and 

have a sprawling growth form. It has dark green leaves and yellow flowers are born on rather 

stout stems. It flowers in the spring and fall. This is a variety of the more common Perityle 

gilensis var. gilensis, and can be distinguished by its long, extremely narrow leaves. It is also 

geographically separated from the typical variety. The type locality is on sandstone with a northfacing aspect. This plant is known only from the type locality on the San Carlos Indian 

Reservation on the Salt River between Showlow and Globe, but it is expected to occur in the Salt 

River Canyon downstream on the Tonto NF (Lutch, 2000).

Fish Creek Rock Daisy Perityle saxicola Status: Sensitive

This herbaceous perennial occurs in central Arizona at elevations between 2,000 and 3,500 feet. It 

is woody at the base, has herbaceous branches and can reach a height of 16 inches. It produces 

yellow flowers and sets seed from May to June. This plant grows from cracks and crevices on 

cliff faces, large boulders and rocky outcrops in canyons and on buttes composed of Barnes 

conglomerate and Mescal limestone. Habitats are very xeric and plants are often associated with 

east and northeast exposures in Arizona Upland Division of Sonoran Desert scrub. Many of the 

species of Perityle are edaphically restricted and are local endemics. This plant is known from 

Gila and Maricopa counties in Arizona. It is considered “locally common” at the Tonto National 

Monument, occurs on the Tonto NF near Roosevelt Dam, and in the Sierra Ancha Mountains 

above Horse Camp Creek. It is suspected throughout the Superstition Mountains (AZGFD, 

2004e). 
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108 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Arizona Phlox Phlox amabilis Status: Sensitive

This is a perennial low-growing plant in the Polemoniaceae family, with a taproot and thick, 

oblong leaves. It has conspicuous pink, wedge-shaped petal lobes with rounded tips (or slightly 

notched tips.). It flowers annually from March to May. Growth habits noted for this species 

include woody subshrub, woody shrub, and herbaceous forb/herb. The locality on the Tonto NF is 

in an opening in a ponderosa pine forest. This plant is endemic to central Arizona, and is known 

to occur in or near Prescott and Payson, Arizona. It has been collected in the vicinity of 

Christopher Creek on the Payson RD of the Tonto NF, and at several locations on the Prescott NF

(AZGFD, 2005e).

Hualapai milkwort Polygala rusbyi Status: Sensitive

This species is known only from central Arizona. It is a narrow endemic, occurring in association 

with Arizona cliffrose, Ripley’s buckwheat, and Horseshoe deer vetch in the Tertiary lakebed 

sediment in the area of Lime Creek and Horseshoe Reservoir, on the Tonto NF. This plant is a low 

sub-shrub two to six inches tall. The plants bloom in April through July. Little is known about the 

biology of this rare plant (Lutch, 2000).

Blumer’s dock Rumex orthoneurus Federal: Sensitive (Proposed, but withdrawn 8/9/99)

This herbaceous perennial is known to occur in Arizona, New Mexico, and Mexico. It is 

characterized by the presence of iris-like rhizomes, succulence of its leaves, lateral leaf veins 

perpendicular to the main vein, and fruiting capsules. Plants have a cluster of large basal leaves, 

which are somewhat succulent and range up to 20 inches long and 7 inches wide. The 

inflorescence is a large narrow panicle occupying the upper half of the stem. Blumer’s dock is 

one of 15 species in this genus in Arizona. This species occurs in riparian habitats at elevations 

between 6,500 and 11,500 feet. Suitable habitats include moist loamy soil adjacent to springs and 

flowing streams in open meadows or meadows with overstories. It is also known to occur in the 

drier headwaters of some areas. Surrounding forested areas are characterized by mixed conifer. It 

typically occurs in open, sunny locations, but can occupy more shaded sites. It is known to occur 

at two locations in the Sierra Anchas on the forest (AZGFD, 2002a).

A Conservation Assessment for Blumer’s dock has been prepared for populations on the Tonto 

NF (Harris & Gobar, 1993). In the 1980s, seed from the Workman and Reynolds creeks’

populations was used to grow plants that were introduced to various canyons in the vicinity of the 

Mogollon Rim, including Bray Creek, Christopher Creek, Canyon Creek, Pine Creek, Tonto 

Creek, Dude Creek, Ellison Creek, See Canyon, Weber Creek, Horton Spring, and Cold Springs 

Canyon. Some of these were damaged by flooding and erosion after the Dude Fire of 1990; 

insects and cattle grazing have impacted other introductions.

Aravaipa Sage Salvia amissa Status: Sensitive

This herbaceous perennial occurs in south-central Arizona at elevations of 1,500 to 5,000 feet. Its 

leaf shape, leaf hairs and elevation distinguish S. amissa from the other 14 Salvia species in 

Arizona. It flowers from July to October and occupies shady canyon bottoms near streams. It 

typically occurs on the floodplain in alluvium, is associated with oak woodland, deciduous 

riparian woodlands, and is commonly found where sycamore, ashes, and willows grow.
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 109

The primary range for the species is in southern Arizona including Aravaipa Creek, Santa 

Catalinas, Galiuros, and Winchester mountains. It was documented in the early 1990s on the 

Tonto NF in Devil’s Chasm and PB Creek in the Sierra Anchas (AZGFD, 2002b).

Aravaipa Woodfern Thelypteris puberula var. sonorensis Status: Sensitive

This rare fern occurs at several localities across central Arizona, including sites in the Four Peaks 

area. It grows in Arizona at elevations from 2,220 to 4,500 feet. There are also populations in 

Arizona’s Aravaipa Canyon, Mexico, and California. Spring development and water diversion 

could damage its localized wetland habitat. The fern’s fronds are large (20 to 51 inches long and 

6 to 12 inches wide). They are light green in color, papery to leathery in texture. The upper 

surface is covered with fine hairs. Stipes or frond stems, are 8 to 12 inches long, pale straw 

colored near the frond, with a pale brown base. The fern is rhizomatous: rhizomes are thick (3 to 

8 mm in diameter), long-creeping, scaly prostrate or underground roots, which produce shoots. 

This species has been identified in granite boulder-strewn riparian habitat, growing in the shade 

of boulders. It emerges with summer rains, and grows into the winter (AZGFD, 2004f).

Environmental Consequences

Habitat of most listed plant species on the Tonto NF has not been surveyed for presence of 

noxious weeds or invasive plants. Surveys for federally-listed and sensitive plants will be 

conducted before any treatments, and treatments will follow adaptive management principles.

Proposed Action: Integrated Vegetation Management

Direct and Indirect Effects

Effects of herbicides to federally-listed and sensitive plants are expected to be negligible, with 

implementation of mitigation measures listed in appendix G. Manual and mechanical treatments 

will be used in buffer areas where herbicides may not be used; there is a slight chance that young 

plants could be mistaken for weeds, trampled, or inadvertently pulled. Presence of a person on the 

project knowledgeable of identification of the listed plant’s characteristics at all life stages will 

minimize this risk.

Prescribed fire will not be used in the vicinity of listed plants, unless a fail-safe barrier exists 

between the project burn and the listed plants.

Biological control agents will have been tested by APHIS for effects to non-target plants prior to 

being permitted in the U.S.

Cumulative Effects

Most activities carried out on the National Forest have some potential to introduce invasive plants 

and/or noxious weeds. Since weeds can degrade habitat, disrupt ecosystem function, or 

outcompete federally-listed or sensitive plant species, it is critical to detect and remove 

infestations quickly before they have the chance to adversely affect protected plant species. 

Implementation of the most aggressive and comprehensive program possible (within budgetary 

constraints) is our best course of action to protect federally-listed and sensitive plants and their 

habitat. This program will include all tools for treatment including herbicides, manual and 

mechanical removal, prescribed fire, cultural treatments, and biological control. A sound 
Chapter 3 – Affected Environment and Environmental Consequences

110 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

prevention program that includes every activity on the forest is an important part of this 

alternative.

Arizona Department of Transportation’s program to manage roadside vegetation using herbicides 

was evaluated and approved by a Decision Notice in 2004. Under this program, rights-of-way 

along federal and state highways within National Forests in Arizona may be treated with 

16 different herbicides: chlorsulfuron, clopyralid, 2,4-D, dicamba, fluroxypyr, glyphosate, 

imazapyr, imazapic, isoxaben, metsulfuron methyl, pendimethalin, picloram, sethoxydim, 

sulfometuron methyl, tebuthiuron, and triclopyr. ADOT expects to use herbicide on less than 

three percent of these rights-of-way annually (5,000 acres), most of this on the northern forests, 

who have the greatest problem with invasive plants. Highways on the Tonto NF that are approved 

for herbicide treatments by ADOT are State Highways 77, 87, 88, 177, 188, 160, 288, and U.S. 

Highways 60 and 70. Under the proposed action, weed infestations that extend beyond the rightof-way + 200 feet will be allowed to be treated by herbicide also, so that rights-of-way will be 

less likely to be reinfested from National Forest lands. Total herbicide use will not be greatly 

increased, as the Tonto NF is proposing annual herbicide use on only about 0.3 percent of its land. 

Most federally-listed or sensitive plants do not grow in or near rights-of-way of these highways. 

One exception is Arizona hedgehog cactus, which grows within the right-of-way of U.S. 

Highway 60, from Top of the World to the east slope of Pinto Creek Canyon. Hedgehog cactus 

has been demonstrated to be susceptible to direct application of a number of herbicides. In testing 

by Frank Crosswhite of the Boyce Thompson Arboretum in 1995, direct application of one-half to 

full maximum label rates of clopyralid and dicamba to species of hedgehog cactus did not affect 

survival, but did have an adverse effect on plant vigor and growth. Direct application of picloram 

and tebuthiuron to another species of hedgehog cactus adversely affected plant survival

(Crosswhite, et al., 1995).

Effects of herbicide to this plant are currently mitigated by conducting survey for these plants and 

maintenance of buffer areas around each one. The Tonto NF’s herbicide proposal includes this 

same buffer area for hedgehog cactus. Invasive plant infestation along U.S. Highway (Hwy) 60 is 

currently at a very low level in the vicinity of the Arizona hedgehog cactus. With ADOT’s current 

program of herbicide application, and also general character of the habitat (granite boulders), 

weed infestations are not expected to grow in Arizona hedgehog habitat.

Road construction and maintenance by ADOT will continue to be potential threats to Arizona 

hedgehog. Mitigation will be needed for any authorized activities in the part of U.S. Hwy. 60 

between Top of the World and Pinto Creek, for the Arizona hedgehog cactus.

Other potential threats listed in the Conservation Assessment and Plan are mining activities and 

removal by collectors.

The unique assemblage of federally-listed and sensitive plants in the Horseshoe Lake/Lime 

Creek/Chalk Mountain area is not currently being impacted by domestic livestock grazing, as 

livestock were removed during the drought in 2000 and have not returned. An Environmental 

Assessment is being conducted, that documents effects of various grazing and non-grazing 

management actions for the Sears-Club/Chalk Mountain Allotment. OHV activity, one of the 

threats listed in the Recovery Plan for Arizona cliffrose, is being addressed by an ongoing 

forestwide travel management program. Both grazing and uncontrolled vehicular traffic can 

easily spread seeds of Malta starthistle into sensitive species habitat. A program to eradicate this 
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 111

weed in the Horseshoe area is essential to continued health of Arizona cliffrose, Ripley’s wild 

buckwheat, Horseshoe deer vetch, and Hualapai milkwort populations. 

Effects of the forest’s grazing program on federally-listed plants are not an issue, as there is no 

permitted grazing in areas where they grow. Many sensitive plants grow in areas not used by 

cattle, such as the Horseshoe/Lime Creek area, bouldery or cliff sites, or inaccessible riparian 

areas. There is a potential for grazing to directly affect some sensitive plants in other areas, or 

indirectly affect them by scattering weed seeds.

Rehab activities after wildfire could affect endangered or sensitive plants if seed mixes applied 

contain weed seeds. The Tonto NF’s program that requires seed lab reports of seed lots to ensure 

they do not contain forest-listed weeds is our mitigation measure to prevent introduction of new 

weeds.

Grazing management on six allotments on the Globe and Tonto Basin ranger districts is being 

evaluated. One proposal is to graze riparian areas, which could affect sensitive plants.

The Tonto NF’s travel management program will open roads that are currently closed, which has 

the potential to affect sensitive species.

Alternative 1: No Action (continue ongoing treatments)

Direct and Indirect Effects

Under current management, invasive plants and noxious weed populations are increasing in size 

and number. With a very limited prescribed burn program, use of housekeeping-type herbicides 

only on administrative sites or recreation areas, and most removal limited to hand-pulling, it is 

very difficult and prohibitively expensive to effectively limit the growth and expansion of weed 

populations. 

Weeds will most likely spread into areas of federally-listed or sensitive plants, where they will 

likely out-compete these plants for soil moisture. Some weeds exhibit allelopathy, which will 

more directly adversely affect sensitive plants by creating an environment where their seedlings 

cannot germinate and establish.

As with the proposed action, physical removal of weeds in the vicinity of protected plants has a 

potential of removing seedlings of protected plants. This can be mitigated by having a person who 

is able to identify seedlings of the protected plants on the project at all times.

Arizona Department of Transportation’s program to manage roadside vegetation will be 

constantly frustrated by reinfestation from adjacent National Forest lands, where weeds will go 

untreated. In some areas, weeds spreading onto the forest from rights-of-way could reach habitat 

of federally-listed or sensitive plants.

Fountain grass has been documented growing in the Superstition Mountains. Buffelgrass also 

grows near this wilderness area. Fire carried by buffelgrass has been documented to cause the 

elimination of two populations of Pima Indian mallow in Mexico (AZGFD, 2000a). It could 

easily happen on the Tonto NF also, if spread of these grasses continues without effective 

removal. Manual removal can be done; however, it is extremely slow and expensive and large 

acreages already infested are not being effectively treated at this time. Manual treatment alone 

would not be sufficient to control these exotic grasses in the future.
Chapter 3 – Affected Environment and Environmental Consequences

112 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

The unique assemblage of plants in the Horseshoe Lake/Lime Creek/Chalk Mountain area will 

probably be infested and adversely affected by Malta starthistle, since manual techniques are not 

currently keeping up with the spread of this invasive plant, and prescribed fire is not an option 

where these sensitive plants grow. The most adverse effect would be that dense infestations of 

weeds would carry a wildfire through the area, decimating populations of the four listed/sensitive 

plants that grow here.

A prescribed burn program that is very limited in scope (burns of ten acres or less, in proximity to 

system roads) will help address incipient weed infestations before they grow beyond roadsides. 

Since many of the sensitive plants do not grow next to system roads, actions such as this may 

prevent weeds from reaching sensitive plant habitat. Where sensitive plants do grow near roads, 

prescribed burning is not an option. 

Cumulative Effects

As with the proposed action, most activities carried out on the National Forest have the potential 

to introduce invasive plants. An aggressive prevention program is essential to try to limit the 

number of weed species. It is critical to prevent establishment of perennial invasive species, since 

they are the ones for which herbicidal treatment is sometimes the only effective tool.

Alternative 2: Integrated Vegetation Management Excluding the Use of 

Herbicides

Direct and Indirect Effects

Effects of implementation of this alternative are much like alternative 1, except larger prescribed 

burns can be used, treatments such as grazing by goats, sheep, and cattle can be implemented, and 

biological control agents can be introduced in sites with sufficient growth of invasive plants to 

sustain them.

As with alternative 1, most treatments are too costly to be used to the extent they will effectively 

diminish weed populations. Treatments such as grazing and prescribed burning will need to be 

used judiciously so that the ground is not disturbed and these practices do not actually bring in 

more weeds or otherwise exacerbate the problem. These practices have the potential to cause 

accelerated erosion and loss of site potential, since they both work through reduction in overall 

groundcover. It would be difficult to target weeds growing in or near habitat of listed or sensitive 

species using either of these treatment methods, without a consequent adverse effect to these 

plants.

As with the Proposed Action and alternative 1, manual or physical removal of weeds is a viable 

option.

We will not be able to permanently remove perennial plants such as camelthorn, Russian 

knapweed, saltcedar, tree of Heaven, and other plants with extensive root systems. These weeds 

grow very well in riparian areas, where some of the listed and sensitive plants are found.

As for alternative 1, the unique assemblage of plants in the Horseshoe Lake/Lime Creek/Chalk 

Mountain area will probably be infested and adversely affected by Malta starthistle, since manual 

techniques are not currently keeping up with the spread of this invasive plant, and prescribed fire 

is not an option where these sensitive plants grow. The most adverse effect would be that dense 
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 113

infestations of weeds would carry a wildfire through the area, decimating populations of the four 

listed/sensitive plants that grow here.

If an effective biocontrol agent is used for Malta starthistle, this alternative may prevent spread of 

the Horseshoe Lake infestation from reaching and adversely affecting sensitive and endangered 

plants in that area.

Cumulative Effects

This action, considered with other ongoing forest actions such as grazing, off-highway vehicle 

use, special use permits for various recreation activities, camping, etc. will most likely result in an 

increase in populations of invasive species. Ineffective treatment of invasive species will allow 

infestations already in or near habitat of listed and sensitive plants to expand. Invasive plants have 

evolved with various characteristics that allow them to out-compete native vegetation. They 

germinate and become established earlier in the spring/winter, thus using up the sometimes scant 

supply of soil moisture and nutrients before native plants are able to germinate. They produce 

copious amounts of seed, which is readily spread by various means, so that weed populations 

grow very rapidly. 

Range Management

Affected Environment

Livestock grazing management activities occur on established active grazing allotments and are 

permitted by the issuance and administration of grazing permits for a ten-year period. Livestock 

are grazed through various management schemes that are intended to provide some level of 

improvement or maintenance of satisfactory soil, water, and vegetation resources. There are 

104 cattle grazing allotments on the Tonto NF. One sheep driveway extends northeast from Mesa 

to the northeast corner of the forest where it enters the Apache-Sitgreaves national forests.

Typical livestock grazing management activities include the following:

• Ranch horses are used to move livestock from one pasture to another.

• Livestock are held for short periods of time in working corrals to facilitate normal 

processing that includes sorting, branding, dehorning, and other practices. The feeding of 

livestock while they are temporarily held in working corrals may include processed feed, 

alfalfa or grass hay.

• Working ranch horses are temporarily held in corrals to facilitate pasture rotations and 

other livestock management practices. The feeding of ranch horses may include 

processed feed, alfalfa or grass hay and grain, such as rolled barley.

• Vehicles and livestock trailers are used to transport feed from areas off the National 

Forest to working corrals on an allotment to facilitate the processing of cattle in corrals 

and other management activities.

• Vehicles and livestock trailers are used to transport livestock to and from other pastures, 

allotments and other lands that are located off the National Forest.

• Vehicles and trailers are used to transport stock water to temporary troughs that may be 

located within a pasture or allotment to manage livestock grazing patterns, especially 

during drought. Stock water sources may be from nearby areas on the National Forest or 

from sources off the National Forest.
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114 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

• Vehicles and ranch horses are used to access an allotment’s range improvements for 

maintenance. Maintenance materials such as replacement wire or steel posts are 

transported to the allotment from sources off the National Forest. Some replacement 

materials may come from areas on the National Forest, such as juniper posts and stays.

• Vehicles and ranch horses are used for range management data collection and monitoring 

by both the Forest Service and permit holder. Ranch horses used for this purpose may be 

temporarily held in corrals on an allotment and will require the transport of livestock 

feed.

Environmental Consequences

Proposed Action: Integrated Vegetation Management

Direct and Indirect Effects

Manual, mechanical, and cultural treatments will cause minimal effects to livestock or range 

management. These treatments are plant specific and have limited impacts on ground cover and 

forage. While people are in the area working, some livestock may be temporarily displaced, but 

the disturbance will be limited in extent and duration. These short-term disturbances to livestock 

would be offset by the forage improvement of removing noxious weeds and the achievement of 

treatment objectives on the management in the project area.

Most treatments using fire will also be small scale with limited non-target impacts. Burn 

treatments that impact a large portion of a pasture may require rest periods for range recovery for 

a season or two afterwards. Cultural treatments could also require that a treated pasture be rested 

for a period of time to provide for establishment of native plants.

We anticipate that biological controls would create no disturbance to livestock or desirable forage 

species. It might limit spread of extensive infestations, thus improving range conditions.

Biocontrol agents could interact with other insects, but they have been extensively tested and 

shown not to have adverse impacts on native insect or plant species. 

Spot treatment of herbicides will not impact livestock management. Resting selected pastures per 

label directions, if applications are of a large scale may occur.

Alternative 1: No Action (continue ongoing treatments)

Direct and Indirect Effects

This alternative would promote the highest loss of range forage, as only up to 0.1 percent of the 

forest would receive weed control treatments annually. Nonnative weeds would spread at the 

fastest rate, because there is very limited additional effort at containment, which leads to the 

greatest loss of habitat. Weed populations would expand exponentially and cause large losses in 

ungulate capacity during the next ten-year period. It would also change the character of the 

riparian ecosystem from fairly fire-resistant to one that is more susceptible to wildfire, through 

spread of fountain grass and saltcedar. Leafy spurge, Russian and diffuse knapweed, cheatgrass, 

starthistles, and biennial thistles would expand and invade previously uninfested grasslands and 

replace palatable, nutritious feed for livestock. 
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 115

Cumulative Effects

Under alternative 1, noxious and invasive weeds would expand from the current population over 

the next ten years. All noxious and invasive weeds would increase in the project area.

Expansion of current noxious and invasive weed populations will also result from the Forest 

Service implementation of numerous ground-disturbing projects including road construction and 

maintenance, timber sale activities, forest restoration projects, prescribed burning, revisions of 

allotment management plans, watershed restoration, road obliteration, and mining. Inclusion of 

weed prevention best management practices in all project planning should reduce the potential of 

new introductions to low levels.

Alternative 2: Integrated Vegetation Management Excluding the Use of Herbicides

Direct and Indirect Effects

This alternative would result in the continuing spread of some weeds, but would not effectively 

treat the majority of weeds. It would treat less than 0.3 percent of the total forest acres.

Mechanical, manual, prescribed burning, biocontrol, and cultural methods would be used. 

Burning is a short-term impact and livestock management can be adapted to accommodate small 

fires, so the effects would be small and, we predict, within the range of normal disturbances. 

Hand pulling and mechanical controls would have a minimal impact to livestock and would be 

beneficial to the habitat by maintaining native plant species. Effects of biocontrol would be the 

same as for the proposed action.

Treatments would not keep up with the rate of weed spread, and the number of acres occupied by 

weeds would increase, so a greater proportion of native forage could be lost than under the 

proposed action.

Cumulative Effects for the Proposed Action and Alternative 2

We anticipate that selection of either of the action alternatives in light of past, present, and 

reasonably foreseeable activities will improve forage conditions for livestock over the next 

10 years, though the degree of improvement depends to a large degree on each action’s ability to 

control weed populations. The proposed action is the only alternative that can achieve control 

objectives on most of the plants found in the project area. 

Cumulative Effects Common to All Alternatives

Overall negative impacts to livestock (range management) that are currently occurring are 

increased disturbance from the growing number of humans living and recreating in the area, and 

long-term drought.

Community growth and development in the Phoenix area and Verde Valley would continue to 

have impacts to the Verde River system as well as increase the number of individuals using the 

project area. Potential effects include reduction in streamflow from increased water usage, 

reduced water quality from increased runoff and sediment input from development in the 

watershed, and impacts to riparian areas from increased recreational activities. Increased 

visitation within the project area could promote the amount of displacement of livestock though 

how much is hard to predict.
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116 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Endangered, Threatened, Proposed, Candidate, and Sensitive 

Wildlife Species

Affected Environment

The diversity of elevational range and vegetation community types on the Tonto NF supports 

complex assemblages of wildlife and plants. This habitat supports over 90 species of mammals, 

60 species of reptiles and amphibians and 300 species of birds. A number of these species have 

been designated as special status species, such as threatened, endangered, proposed, candidate, 

sensitive, and management indicator species. Effects to management indicator species and their 

habitat are discussed in Appendix K, Management Indicator Species Report.

There are four endangered, three threatened, and one candidate terrestrial and aquatic wildlife 

species that are either found or have designated critical habitat in or near the project area. An 

additional 31 species are classed as sensitive and are on the U.S. Forest Service Region 3 list for 

terrestrial and aquatic wildlife.

Table 11. Threatened, endangered, and sensitive animal species on the Tonto NF

Scientific 

Name

Common 

Name Status Watershed/Location Vegetation Type

Known Invasive 

Species in Habitat

Birds

Empidonax 

traillii extimus

Southwestern 

willow 

flycatcher

E

Lower Verde, Upper Salt, 

Tonto/Roosevelt Lake at 

Tonto and Salt inflows, Pinal 

at Inspiration Dam

Riparian

Saltcedar, 

starthistles, bromes, 

yellow sweetclover, 

tree of heaven

Empidonax 

traillii extimus

Critical 

habitat

Verde – Fossil Cr. to upper 

end of Horseshoe Reservoir, 

Tonto Cr. from high water 

level of Roosevelt Lake 

upstream to confluence with 

Rye Cr. Salt River from 

diversion dam upstream to 

Cherry Cr. confluence

Riparian

Saltcedar, 

starthistles, bromes, 

yellow sweetclover, 

tree of heaven

Haliaeetus 

leucocephalus Bald eagle T

Salt & Verde rivers & 

associated reservoirs, Tonto 

Creek. Mature cottonwoods 

and cliffs 

Riparian, 

ponderosa 

pine

Malta starthistle, 

saltcedar, yellow 

sweetclover, tree of 

heaven

Rallus 

longirostris 

yumanensis

Yuma clapper 

rail E

Lower Verde, Lower Salt, 

Tonto Creek inflow at 

Roosevelt Lake

Riparian

Saltcedar, Malta 

starthistle, yellow 

sweetclover

Strix 

occidentalis 

lucida

Mexican 

spotted owl T

Lower Verde, Upper Salt, 

Tonto Cr. Pine/oak and 

mixed conifer areas

Ponderosaoak, mixed 

conifer

Bull thistle, 

starthistles, Canada 

thistle

Strix 

occidentalis 

lucide

Mexican 

spotted owl 

Critical 

habitat

Same as above Same as 

above Same as above
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 117

Scientific 

Name

Common 

Name Status Watershed/Location Vegetation Type

Known Invasive 

Species in Habitat

Coccyzus 

Americanus 

occidentalis1

Yellow-billed 

cuckoo C

Lower Verde, Upper Salt and 

others/ found in areas with 

mature multi-canopied 

riparian stands

Low 

elevation 

Riparian

Saltcedar, 

starthistles, bromes, 

yellow sweetclover, 

tree of heaven

Accipiter 

gentilis

Northern 

goshawk S

Lower Verde, Upper Salt, 

Tonto/ Mogollon Rim, Sierra 

Anchas, Pinal Mtns.

Ponderosaoak, mixed 

conifer

Saltcedar, Malta 

starthistle, 

knapweeds, yellow 

sweetclover

Aechmophorus 

clarkii Clark’s grebe S Coves, backwaters Riparian

Saltcedar, 

starthistles, 

knapweeds, bromes, 

yellow sweetclover

Asturina nitida 

maxima

Northern gray 

hawk S

Upper Salt, Lower Verde/ 

Cherry, Pinal and Cave 

creeks

Low to midelevation 

riparian 

areas

Saltcedar, Malta 

starthistle, tree of 

heaven, yellow 

sweetclover, giant 

reed

Buteo 

albonotatus

Zone-tailed 

hawk S

Upper Salt, Lower Verde/ 

Cherry, Pinal and Cave 

creeks

Low to midelevation 

riparian 

areas

Saltcedar, Malta 

starthistle, tree of 

heaven, yellow 

sweetclover, giant 

reed

Buteogallus 

anthracinus

Common 

blackhawk S All/most drainages with 

mature riparian forests. Riparian

Saltcedar, 

starthistles, 

knapweeds, bromes, 

yellow sweetclover

Falco 

peregrinus 

anatum

American 

peregrine 

falcon

S

All rock escarpments along 

rivers and mountain ranges 

on the forest.

Cliffs Saltcedar, possibly 

others

Pipilo aberti Abert’s 

towhee S

Lower Verde, Upper Salt and 

others found in areas with 

mature multi-canopied 

riparian stands

Low 

elevation 

Riparian

Saltcedar, 

starthistles, bromes, 

yellow sweetclover, 

tree of heaven

Vireo vicinior Gray vireo S Upper and Lower Salt/Upper 

Verde rivers

Desert 

scrub, 

piñyon/

juniper with 

broad leafed 

shrubs, steep 

rocky slopes

Saltcedar, Malta 

starthistle, Saharan 

mustard, 

buffelgrass, 

fountain grass, tree 

of heaven, 

camelthorn

Mammals

Leptonycteris 

curasoae 

yerbabuenae

Lesser longnosed bat E No known locations on the 

forest

Saguaro, 

agave

Saltcedar, Malta 

starthistle, fountain 

and buffelgrasses, 

bromes, Saharan 

mustard
Chapter 3 – Affected Environment and Environmental Consequences

118 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Scientific 

Name

Common 

Name Status Watershed/Location Vegetation Type

Known Invasive 

Species in Habitat

Corynorhinus 

townsendii 

pallescens

Pale 

Townsend’s 

big-eared bat

S Upper and Lower Salt/Upper 

Verde rivers

Desert scrub 

and 

grassland

Starthistles, bromes, 

Mediterranean 

grass, mustards, 

fountain and buffel 

grasses

Euderma 

maculatum Spotted bat S Upper Verde Rocky cliffs 

& riparian

Dalmatian toadflax, 

saltcedar, yellow 

sweetclover, giant 

reed, fountain grass

Eumops perotis 

californicus

Greater 

Western 

mastiff bat

S Upper and Lower Salt/ upper 

Verde rivers

Rocky cliffs 

& riparian

Dalmatian toadflax, 

saltcedar, yellow 

sweetclover, giant 

reed, fountain grass

Idionycteris 

phyllotis

Allen’s bigeared bat S Upper Verde

Mountainou

s wooded 

areas & 

riparian

Saltcedar, Malta 

starthistle, 

knapweeds, yellow 

sweetclover

Lasiurus 

blossevillii

Western red 

bat S Upper and Lower Salt/ Upper 

Verde rivers Riparian 

Dalmatian toadflax, 

saltcedar, yellow 

sweetclover, giant 

reed, fountain grass

Macrotus 

californicus

California 

leaf-nosed bat S Lower Verde/Lower Salt 

rivers

Lowland 

desert scrub

Saltcedar, 

starthistles, bromes, 

yellow sweetclover, 

tree of heaven

Nasua narica White-nosed 

coati S Upper & Lower Salt Riparian

Dalmatian toadflax, 

saltcedar, yellow 

sweetclover, giant 

reed, fountain grass

Nyctinomops 

femorosaccus

Pocketed freetailed bat S Lower Verde/ Lower Salt 

rivers

Rocky cliffs 

& riparian

Dalmatian toadflax, 

saltcedar, yellow 

sweetclover, giant 

reed, fountain grass

Ovis 

canadensis 

canadensis

Rocky 

Mountain 

bighorn

S

Upper Verde & Salt/ 

Mazatzal, Sierra Ancha 

moutain ranges

Ponderosa

oak-mixed 

and rocky 

ridges

Brome grasses, 

mustards, Malta 

starthistle, wild 

oats, giant reed

Ovis 

canadensis 

mexican

Desert 

bighorn S

Upper Verde, Upper & 

Lower Salt/ Superstition, 

Mazatzal, Goldfield, Sierra 

Ancha moutain ranges

Desert 

grassland, 

open, rocky 

ridges

Brome grasses, 

mustards, Malta 

starthistle, wild 

oats, giant reed

Reptiles

Gopherus 

agassizii

Sonoran 

Desert tortoise S

Lower Verde, Lower 

Salt/desert scrub, desert 

grassland in southwestern 

portion of the forest.

Desert scrub

Malta starthistle, 

brome grasses, 

Mediterranean 

grass, mustards, 

fountain grass
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 119

Scientific 

Name

Common 

Name Status Watershed/Location Vegetation Type

Known Invasive 

Species in Habitat

Heloderma 

suspectum Gila monster S Lower Salt, Lower Verde Desert scrub 

& grassland

Malta starthistle, 

brome grasses, 

Mediterranean 

grass, mustards

Phyllorhynchus 

browni lucidus

Maricopa 

leafnose snake S Lower Verde, Lower Salt/ 

rocky or sandy desert Desert scrub

Malta starthistle, 

brome grasses, 

Mediterranean 

grass, mustards

Thamnophis 

eques 

megalops

Mexican 

garter snake S Lower Verde, Lower Salt, Tonto/

Low 

elevation 

Riparian

Yellow 

sweetclover, 

saltcedar, Malta 

starthistle

Thamnophis 

rufipunctatus

Narrowheaded garter 

snake

S

Lower Verde, Upper Salt, 

Tonto/ mid-to-high elevation 

streams

Riparian

Yellow 

sweetclover, 

saltcedar, Malta 

starthistle

Amphibians

Rana 

chiricahuensis

Chiricahua 

leopard frog T

Lower Verde, Tonto Creek, 

Upper Salt River, various 

sites below the Mogollon 

Rim

Riparian, 

stock ponds

Yellow 

sweetclover, 

saltcedar, 

starthistles, tree of 

heaven

Bufo 

microscaphus 

microscaphus

SW (Arizona) 

toad S

Lower Verde, Lower Salt, 

Tonto, Agua Fria. Widely 

distributed in permanent 

pools, rocky streams, and 

canyons. Appearing to select 

for shallow water flowing 

over sandy or rocky bottoms

Late seral 

riparian 

areas within 

desert 

grasslands, 

piñyonjuniper, 

pine-oak 

and 

ponderosa 

pine 

communities

Yellow 

sweetclover, 

saltcedar, Malta 

starthistle, fountain 

grass

Eleutherodactylus augusti 

cactorum

Western 

barking frog S No documented locations on 

the Tonto NF

Juniper/ oak 

woodlands, 

open pine 

forests

N/A

Rana pipiens Northern 

leopard frog S No documented locations on 

the Tonto NF

Permanent 

water in 

grassland, 

chaparral, 

pine forest

N/A
Chapter 3 – Affected Environment and Environmental Consequences

120 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Scientific 

Name

Common 

Name Status Watershed/Location Vegetation Type

Known Invasive 

Species in Habitat

Rana 

yavapaiensis

Lowland 

leopard frog S

All/ up to 6,000’ but 

generally restricted to 

elevations below 3,500’. 

Permanent water with aquatic 

vegetation

Low 

elevation 

riparian

Malta starthistle, 

saltcedar, yellow 

sweetclover, 

fountain grass, 

pyracantha, 

oleander

Invertebrates

Agathon 

arizonicus

Netwing 

midge S Upper Salt/ Workman Cr. Riparian Unknown

Cylloepus 

parkeri

Parker’s riffle 

beetle S Lower Verde/ Roundtree 

Canyon, possibly Tangle Cr. Riparian

Saltcedar, yellow 

sweetclover, 

bromes

Pyrgulopsis 

simplex

Fossil 

springsnail S Fossil Creek Riparian Unknown

Each of the above species is discussed in the Biological Assessment/Evaluation, Appendix J.

Environmental Consequences

Proposed Action: Integrated Vegetation Management

Direct and Indirect Effects

Manual, mechanical, flaming of weeds, and cultural treatments will cause minimal effects to 

wildlife. These treatments are plant specific and have limited impacts on ground cover and habitat 

conditions. While people are in the area working, some wildlife species may be temporarily 

displaced, but the disturbance will be limited in extent and duration. These short-term 

disturbances to wildlife would be offset by the habitat improvement of removing noxious weeds 

and the achievement of treatment objectives on the species found in the project area.

We anticipate that biological controls would create no disturbance to vertebrate animal species or 

desirable forage species. They could interact with other insects, but they have been extensively 

tested and shown not to have adverse impacts on native insect or plant species. Chemical 

treatments are not very disruptive to wildlife either and since applicators are in the area for a 

limited time period, we do not predict any displacement of wildlife resulting from these 

treatments.

A series of risk assessments were written by Syracuse Environmental Research Association on 

herbicides proposed for use in this document (appendix F). The following discussion on herbicide 

effects to wildlife in the project area is based on a comparison to these risk assessments.

The nontarget species hazard analysis summarized laboratory and field study findings that 

evaluated toxicity of the herbicides and carriers to wildlife and aquatic species. In many cases, 

toxicity studies with laboratory animals were used in this risk assessment because of the lack of 

specific wildlife studies. The results of laboratory animal studies are considered to be 

representative of the effects that would occur in similar species in the wild.

Wildlife doses were calculated for a group of wildlife species representative of those typically 

found in areas supporting rangeland, forest land, or riparian vegetation found in the West. These 
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 121

species represent a range of phylogenetic classes, body sizes, and diets for which biological 

parameters are generally available. Typical and extreme acute dose estimates were determined for 

each representative species for each of the three major exposure routes—dermal, ingestion, and 

inhalation. Since the herbicides degrade relatively rapidly and sites are normally treated only once 

per year, no analysis of chronic wildlife dosing was performed. Because the herbicides show little 

tendency to bioaccumulate (although several tend to bioconcentrate in aquatic environments), 

long-term persistence in food chains and subsequent toxic effects were not considered a problem 

and were not examined in the risk assessment.

The results of the risk analysis indicate that potential risks to individual animals are low for most 

of the herbicides. Estimated doses for typical exposures result in a low risk from all herbicides 

and carriers.

Dicamba is moderately toxic to insects at high doses. However, in the field it would only be 

applied in low doses. Triclopyr can be moderately toxic to guinea pig and mice. It does not 

bioaccumulate and the Garlon formulations are considered only slightly toxic. All the other 

herbicides proposed for use have low toxicity.

In summary, for typical exposures, the results of the nontarget species risk analysis indicate that 

all of the herbicides and carriers present a low risk to individual terrestrial animals (U.S. Forest 

Service, 1992).

The above information can be applied to animals found on the Tonto NF covered by this proposal. 

For threatened, endangered and sensitive species (TE&S) and Management Indicator Species

(MIS), under typical exposures, no species are at risk. Though dicamba and triclopyr may have 

adverse impacts on the animals listed above if directly sprayed on the animals, the likelihood of 

this occurring is very low. Dicamba could potentially be used on several weed species, including 

Malta starthistle and spotted knapweed. Triclopyr and imazapyr will be used almost exclusively 

for the treatment of tree of heaven, Russian olive, saltcedar, and Siberian elm. The method of 

application will be cut and daub or injections into the bark, with no broadcast spraying involved. 

The chances of impacting any native wildlife or non-target vegetation by this method of 

application are very remote.

We do not anticipate any adverse impacts on wildlife species from a toxicological standpoint. We 

project that the low incidence of use and prescribed rate below what is recommended from the 

risk assessment will limit the risk to wildlife relating to toxicological impacts.

Most weed populations are small and scattered, so treatments that occur under this alternative will 

be localized. Therefore, treatments would only impact a minor portion of any wildlife species 

population at one time. Less than 0.5 percent of the land area on the Tonto NF would be treated 

with herbicide. As described above, treatments may create a short-term disturbance, while people 

are in the area working. For weeds with large populations, like saltcedar or the starthistles, only a 

portion of the population will be treated at one time, so the impacts on native wildlife are similar 

to some of the small populations of weeds.

Proposed application rates are typically well below the recommended amounts as disclosed in the 

risk assessment. We anticipate that this situation, in combination with the low amounts of 

National Forest to be treated in any given year, would reduce the potential for any toxicological 

problems to very low levels. In fact, successful treatment of invasive species will improve habitat 
Chapter 3 – Affected Environment and Environmental Consequences

122 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

conditions for the TE&S and MIS species. This includes elk, deer, turkey, Mexican spotted owl, 

and pronghorn.

Species’ habitat will be maintained or improved by promoting native vegetation for food and 

cover. Some animals whose habitat have noxious and invasive weeds include, but are not limited 

to, Southwestern willow flycatcher, bald eagle, Mexican spotted owl, Chiricahua leopard frog, 

Mexican garter snake, northern goshawk, common black hawk, and Southwestern river otter. 

Habitat for management indicator species (MIS) will be improved also (see Appendix K, 

Management Indicator Species Report), and any potential for noxious weeds to cause habitat 

fragmentation slowed down or stopped under this alternative, especially for wild turkey, mule 

deer, pronghorn, and elk. All these species depend on diverse, high quality grass or forbs for 

forage. In addition, for those MIS living in riparian habitats such as the Bell’s vireo, summer 

tanager, and hooded oriole, the alternative reduces noxious and invasive weeds to low levels and 

promotes regeneration of native woody plants.

Alternative 1: No Action (continue ongoing treatments)

Direct and Indirect Effects

This alternative would promote the highest loss of wildlife habitat. Nonnative weeds would 

spread at the fastest rate because there is no additional effort at containment, which leads to the 

greatest loss of habitat. Weed populations would expand exponentially and cause large losses in 

ungulate capacity during the next ten-year period. Over time, as weeds spread, tree structure 

along riparian areas could change from cottonwoods, willows, and other associated species to a 

near monoculture of saltcedar. We suspect this would reduce nest areas and forage for species 

found in this ecosystem including yellow-billed cuckoo, leopard frog, and black hawk. It would 

also change the character of the riparian ecosystem from fairly fire-resistant to one that is more 

susceptible to wildfire. Leafy spurge, Russian and diffuse knapweed, cheatgrass, starthistles and 

biennial thistles would expand and invade previously uninfested grasslands and replace palatable, 

nutritious feed for elk, deer, and pronghorn. As starthistle and bull thistle populations expand and 

grow into one another, small mammal populations would diminish, resulting from losses of 

forage and cover. This would invariably reduce the prey base for all raptor species, though of 

particular concern are goshawks and Mexican spotted owl. 

Cumulative Effects

This would allow weeds to expand, precipitate a decline of native plants and decrease the amount 

of wildlife habitat available for threatened, endangered, sensitive, and management indicator 

species. It would reduce food (seeds and forage), habitat diversity, and cover for most animals 

found in habitats associated with the Verde and Salt River drainages. Reduction in plant diversity 

would interrupt insect life cycles, which could decrease food for birds, which would in turn 

adversely affect their predators. Weed invasion is likely to be especially hard on riparian species 

such as Yuma clapper rail, yellow-billed cuckoo, garter snakes, and leopard frog if saltcedar and 

Russian olive invade. This is at least partially due to the fact that many invasive species increase 

fire frequency in riparian areas.

Weed invasion, on top of these impacts, could be a cumulative adverse effect on wildlife 

population size, reproduction, health, and resilience. Some species are more susceptible to 

alterations in habitat, such as springsnails and yellow-billed cuckoo. 
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 123

Alternative 2: Integrated Vegetation Management Excluding the Use of 

Herbicides

Direct and Indirect Effects

This alternative would result in the continuing spread of some weeds, and would not effectively 

treat the majority of weeds. It would treat less than 0.3 percent of the total forest acres.

Mechanical, manual, prescribed burning, and cultural methods would be used. Burning is a shortterm impact and wildlife is adapted to fires so the effects would be small and, we predict, within 

the range of normal disturbances. Hand pulling and mechanical controls would have a very small 

impact to wildlife and would be beneficial to the habitat by maintaining native plant species. 

Treatments would not keep up with the rate of weed spread, and the number of acres occupied by 

weeds would increase, so a greater proportion of wildlife habitat could be lost than under the 

proposed action or alternative 1.

Cumulative Effects for the Proposed Action and Alternative 2

We anticipate that selection of either of the action alternatives in light of past, present, and 

reasonably foreseeable activities will improve habitat for threatened, endangered, and sensitive 

species, as well as management indicator species over the next ten years, though the degree of 

improvement depends to a large degree on each action’s ability to control weed populations. The 

proposed action is the only alternative that can achieve control objectives on most of the plants 

found in the project area. 

Cumulative Effects Common to All Alternatives

Overall negative impacts to wildlife that are currently occurring are habitat fragmentation from 

land development and more roads, increased disturbance from the growing number of humans 

living and recreating in the area, and long-term drought.

Community growth and development in the Phoenix area and Verde Valley would continue to 

have impacts to the Verde River system as well as increase the number of individuals using the 

project area. Potential effects include reduction in streamflow from increased water usage, 

reduced water quality from increased runoff and sediment input from development in the 

watershed, and impacts to riparian areas from increased recreational activities. Increased 

visitation within the project area could promote the amount of displacement of wildlife species 

though how much is hard to predict.

Activities that could cumulatively improve overall habitat conditions of our native wildlife 

include: (1) current control efforts undertaken by the Arizona Department of Transportation 

which is curtailing the expansion of noxious weeds in road corridors under their jurisdiction; (2) 

current efforts on the Tonto NF related to weed control as mentioned above; and (3) the proposed 

control efforts to curb off-road vehicle use within the project area. All three activities will 

improve wildlife habitat, especially in riparian areas, and improve overall survivability of species 

found in this ecosystem.

Other activities that should promote wildlife habitat are the incorporation of Chapter 90 of FSH 

2209.13. This formally adopts adaptive management as a tool for managing grazing. This, as well 

as practicing conservative utilization of forage resources, should improve the herbaceous 

understory and overall habitat conditions on the forest. 
Chapter 3 – Affected Environment and Environmental Consequences

124 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

The reduction of small diameter trees in the ponderosa pine ecosystem within various areas 

throughout the Tonto NF will not only decrease the potential for wildfire, but also improve the 

available forage for native wildlife. This should increase the amount of habitat available for 

management indicator species like elk and turkey as well as improve foraging zones for many 

small mammals. This should increase the prey base for not only raptors, but other species as well.

The Forest Service has acquired instream flow rights for the Verde Wild & Scenic River from 

Beasley Flat downstream 40 miles to the confluence of Red Creek. The Tonto NF is actively 

attempting to acquire instream flow rights on tributaries of both the Salt and Verde rivers. 

Acquisition of additional instream flow rights in the project area would promote such species as 

the Southwestern willow flycatcher, bald eagle, peregrine falcon, river otter, and migrating birds.

The Fort McDowell Indian Water Settlement Act of 1990 authorized the Fort McDowell Indian 

Community, which is immediately downstream of the Tonto NF on the Verde River, to receive 

36,350 acre feet of water per year (Jacobs, 1999). This, in effect, ensures water in the lower Verde 

River.

Neotropical Migratory Birds

Affected Environment and Environmental Consequences

Many of these birds are riparian obligates; therefore, the proposed action, which protects riparian 

habitat, is the optimum choice for this resource. Table 12 lists migratory bird species whose 

populations are of concern and their anticipated response to the Proposed Action, alternative 1, 

and alternative 2. Similar to the discussion above, the Proposed Action should have no direct 

effects to these species and indirect effects should be beneficial. Cumulative effects are also likely 

to be beneficial under the Proposed Action. Alternative 1 will not enhance native habitat and thus 

not improve habitat for migratory birds. Established weeds will continue to spread and degrade 

habitat for these species. Effects on habitat and population trend for these species will depend on 

the severity of the invasion of weeds. For some of the species listed in table 11, invasions could 

negatively impact habitat and population trend. Alternative 2 will improve some habitats by 

limiting the spread of weeds, but the majority of impacted habitats would not be controlled under 

this alternative.
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 125

Table 12. Migratory bird species of concern in Sonoran and Sierra Madre Occidental ecological regions of the Tonto National Forest, 

and estimated trend response to the proposed action and the two alternatives

Species Vegetation 

Type Habitat

Examples of 

Invasive Plant 

Species in or near 

Habitat

Current 

condition/trend 

forestwide

Estimated 

Trend in 

Habitat and 

Population 

Under the 

Proposed 

Action

Estimated 

Trend in 

Habitat and 

Population 

Under 

Alternative 1

Estimated 

Trend in 

Habitat and 

Population 

Under 

Alternative 2

Yellowbilled cuckooLow elevation 

riparian

Cottonwood 

and willow 

with dense 

patches

Saltcedar, tree of 

heaven, mustards, 

fountain grass, 

oleander, giant reed, 

Russian knapweed, 

camelthorn, yellow 

sweetclover, African 

sumac

No 

Change/Stable No change Potential Decrease

Potential 

Decrease

Elf owl

Sonoran 

Desert scrub, 

riparian, 

piñyon/juniper

Cavity nester

Starthistles, Saltcedar, 

tree of heaven, 

mustards, yellow 

sweetclover, African 

sumac, Siberian elm

Static/Increase No change No change No change

Burrowing 

owl

Semi-desert 

grassland, 

grasslands

Nests in 

animal 

burrows in 

open ground

Mustards, Schismus, 

buffelgrass, fountain 

grass, bromes, 

sandbur

Static/Stable No change No change No change

Loggerhead 

shrike

Sonoran 

Desert scrub, 

semi-desert 

grassland

Open areas

Mustards, Schismus, 

buffelgrass, fountain 

grass, bromes, 

sandbur

Static/Decreasing No change No change No change
Chapter 3 – Affected Environment and Environmental Consequences

126 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Species Vegetation 

Type Habitat

Examples of 

Invasive Plant 

Species in or near 

Habitat

Current 

condition/trend 

forestwide

Estimated 

Trend in 

Habitat and 

Population 

Under the 

Proposed 

Action

Estimated 

Trend in 

Habitat and 

Population 

Under 

Alternative 1

Estimated 

Trend in 

Habitat and 

Population 

Under 

Alternative 2

Gray vireo

Piñyon/juniper 

with broadleafed shrubs

Low and tall 

shrubs with a 

tree 

component; 

drier, rocky, 

steep slopes

Bromes, knapweeds, 

starthistles, mustards Static/Stable No change No change No change

Bendire’s 

thrasher

Sonoran 

Desert scrub, 

semi-desert 

grassland

Open habitat 

with large 

cacti, shrubs

Mustards, Schismus, 

buffelgrass, fountain 

grass, bromes, 

sandbur

No 

Change/Stable No change No change No change

Yellow 

warbler Riparian Willows

Saltcedar, tree of 

heaven, giant reed, 

knapweeds, Siberian 

elm, oleander, 

fountain grass

Static/Increase No change Potential 

Decrease

Potential 

Decrease

Blackchinned 

sparrow

Sonoran 

Desert scrub, 

P/J-turbinella 

oak

Dense shrub 

w/ passages

Malta starthistle, 

bromes, Lehmann’s 

lovegrass, Jerusalem 

thorn, buffelgrass, 

Russian thistle

Static/Stable No change No change No change

Lark bunting

Sonoran 

Desert scrub, 

semi-desert 

grassland

Grass cover 

less than 30 

centimeters

Mustards, Schismus, 

buffelgrass, fountain 

grass, bromes, 

sandbur, Jerusalem 

thorn

No 

Change/Stable No change No change No change
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 127

Species Vegetation 

Type Habitat

Examples of 

Invasive Plant 

Species in or near 

Habitat

Current 

condition/trend 

forestwide

Estimated 

Trend in 

Habitat and 

Population 

Under the 

Proposed 

Action

Estimated 

Trend in 

Habitat and 

Population 

Under 

Alternative 1

Estimated 

Trend in 

Habitat and 

Population 

Under 

Alternative 2

Lawrence’s 

goldfinch

Riparian, 

piñyon/juniper

Woodland 

near water

Starthistles, Saltcedar, 

tree of heaven, 

mustards, yellow 

sweetclover, African 

sumac, Siberian elm

Static/Increase No change Potential 

Decrease

Potential 

Decrease

Northern 

goshawk

Ponderosa 

pine

Denser 

portions of

conifer 

stands

Oxeye daisy, 

Dalmatian toadflax, 

biennial thistles, 

Canada thistle, yellow 

starthistle, field 

bindweed, Japanese 

knotweed

No 

Change/Stable No change No change No change

Gray hawk Riparian

Woodlands 

with open 

areas

Starthistles, Saltcedar, 

tree of heaven, 

mustards, yellow 

sweetclover, African 

sumac, Siberian elm

No 

Change/Increase No change Potential Decrease

Potential 

Decrease

Common 

blackhawk Riparian

Mature 

riparian 

woodlands 

with 

permanent 

water

Starthistles, Saltcedar, 

tree of heaven, 

mustards, yellow 

sweetclover, African 

sumac, Siberian elm

Static/Decrease No change Potential 

Decrease

Potential 

Decrease
Chapter 3 – Affected Environment and Environmental Consequences

128 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Species Vegetation 

Type Habitat

Examples of 

Invasive Plant 

Species in or near 

Habitat

Current 

condition/trend 

forestwide

Estimated 

Trend in 

Habitat and 

Population 

Under the 

Proposed 

Action

Estimated 

Trend in 

Habitat and 

Population 

Under 

Alternative 1

Estimated 

Trend in 

Habitat and 

Population 

Under 

Alternative 2

Ferruginous 

hawk

Riparian, 

Sonoran 

Desert scrub, 

semi-desert 

grassland

Varied

Starthistles, Saltcedar, 

tree of heaven, 

mustards, yellow 

sweetclover, African 

sumac, Siberian elm, 

Jerusalem thorn

Static/Increase No change No change No change

Peregrine 

Falcon

Sonoran 

Desert scrub, 

piñyonjuniper, 

chaparral

Cliffs, rocky 

outcroppings 

in open areas

Mustards, bromes, 

Schismus, Jerusalem 

thorn, camelthorn, 

white bietou, 

resinbush

No 

Change/Stable No change No change No change

Flammulated 

Owl

Ponderosa 

pine, mixed 

Conifer

Open 

woodlands 

with brushy 

understory

Oxeye daisy, 

Dalmatian toadflax, 

biennial thistles, 

Canada thistle, yellow 

starthistle, field 

bindweed, curveseed 

butterwort, diffuse 

knapweed, Japanese 

knotweed

Static/Increase No change No change No change

Lucy’s 

warbler

Low elevation 

riparian

Mesquite, 

willow, 

cottonwood 

with dense 

midstory

Giant reed, Jerusalem 

thorn, oleander, tree 

of heaven, Saltcedar, 

fountain grass

Static/Increase No change Potential 

Decrease

Potential 

Decrease
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 129

Species Vegetation 

Type Habitat

Examples of 

Invasive Plant 

Species in or near 

Habitat

Current 

condition/trend 

forestwide

Estimated 

Trend in 

Habitat and 

Population 

Under the 

Proposed 

Action

Estimated 

Trend in 

Habitat and 

Population 

Under 

Alternative 1

Estimated 

Trend in 

Habitat and 

Population 

Under 

Alternative 2

Broad-billed 

hummingbird

Riparian, 

piñyon/juniper

Small tree, 

shrub, vines

Giant reed, Jerusalem 

thorn, oleander, tree 

of heaven, Saltcedar, 

fountain grass, 

knapweeds

Static/Increase No change Potential 

Decrease

Potential 

Decrease

Costa’s 

hummingbird

Sonoran 

Desert scrub

Small dense 

trees or 

shrubs near 

riparian zone 

and 

flowering 

plants

Buffelgrass, bromes, 

mustards, Malta 

starthistle, 

camelthorn, 

Schismus, fountain 

grass, sandbur, 

Jerusalem thorn

No 

Change/Stable No change No change No change

Northern 

beardlesstyrannuletRiparian

Cottonwood 

groves 

adjacent to 

water

Giant reed, Jerusalem 

thorn, oleander, tree 

of heaven, Saltcedar, 

fountain grass

No 

Change/Increase No change Potential Decrease

Potential 

Decrease

Greater 

pewee Riparian Woodland

Giant reed, Jerusalem 

thorn, oleander, tree 

of heaven, Saltcedar, 

fountain grass, teasel

Static/Stable No change Potential 

Decrease

Potential 

Decrease

Purple 

martin

Sonoran 

Desert scrub

Large 

saguaros with 

numerous 

holes in 

denser stands

Mustards, Schismus, 

buffelgrass, fountain 

grass, bromes, 

sandbur, Jerusalem 

thorn

No 

Change/Stable No change No change No change
Chapter 3 – Affected Environment and Environmental Consequences

130 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Species Vegetation 

Type Habitat

Examples of 

Invasive Plant 

Species in or near 

Habitat

Current 

condition/trend 

forestwide

Estimated 

Trend in 

Habitat and 

Population 

Under the 

Proposed 

Action

Estimated 

Trend in 

Habitat and 

Population 

Under 

Alternative 1

Estimated 

Trend in 

Habitat and 

Population 

Under 

Alternative 2

Baird’s 

sparrow

Semi-desert 

grassland

Grass with no 

woody 

canopy

Buffelgrass, bromes, 

mustards, Lehmann’s 

lovegrass

Static/Decrease No change No change No change

Common 

blackhawk

Low and high 

elevation 

riparian

Perennial 

streams with 

tree galleries

Giant reed, Jerusalem 

thorn, oleander, tree 

of heaven, Saltcedar, 

fountain grass

Static/Increase No change Potential 

Decrease

Potential 

Decrease
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 131

Endangered, Threatened, Proposed, Candidate and Sensitive 

Fish Species

Affected Environment

The project area contains five federally-listed fishes (Colorado pikeminnow, razorback sucker, Gila 

topminnow, Gila trout, Gila chub), and one Region 3 Sensitive fish (roundtail chub).

Table 13. Endangered, threatened, sensitive, and native fishes of the Tonto National Forest

Common Name Species Status

Federally Listed 

Desert pupfish Cyprinodon macularius macularius E, WC

Bonytail chub Gila elegans E, WC

Gila chub Gila intermedia E, WC, CH

Woundfin Plagopteris argentissimus E, WC, EXT

Gila topminnow Poeciliopsis occidentalis occidentalis E, WC

Colorado pikeminnow 

(squawfish) Ptychocheilus lucius E, WC, some ENE 

Razorback sucker Xyrauchen texanus E, WC, CH

Spikedace Meda fulgida T, WC, PCH

Gila trout Oncorhynchus gilae gilae T, WC

Loach minnow Tiaroga cobitis T, WC, PCH

Sensitive Fish 

Longfin dace Agosia chrysogaster S

Desert sucker Catostomus clarki S

Sonora sucker Catostomus insignis S

Headwater chub Gila nigra C

Roundtail chub Gila robusta S, WC

* E = Endangered; T = Threatened, C = Candidate, EXT = Extirpated, S = Sensitive; WC = Wildlife of 

Special Concern in Arizona, as determined by Arizona Game and Fish Dept.; ENE = Experimental/Nonessential; CH = Critical Habitat, PCH = Proposed Critical Habitat

Species in table 13 are described below.

Desert Pupfish Cyprinodon macularius macularius Status: Endangered

Desert pupfish once was widespread and abundant in southern Arizona, southeastern California, 

northern Baja California, and Sonora (Minckley, 1973). Its habitat in the lower Gila and Colorado 

River drainages comprised a wide diversity of waters that consisted of the margins of the larger 

lakes and rivers, desert springs, marshes, and tributary streams including the Salt, San Pedro, and 

Santa Cruz rivers. Currently no natural populations of desert pupfish occur in Arizona 

(Quitobaquito pupfish (C. eremus, formerly C. m. eremus) occurs on Organ Pipe Cactus National 

Monument). In California, several populations persist in tributaries to the Salton Sea, and in 

Mexico pupfish exist along the Colorado River Delta and in other nearby wetlands. Several 
Chapter 3 – Affected Environment and Environmental Consequences

132 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

transplanted populations are on private and public lands in Arizona and California, including one 

at Boyce Thompson Arboretum near Superior. Two transplanted populations occur on Tonto NF, 

both on the Mesa Ranger District (Calamusso, 2012).

Nearly all of the original range of desert pupfish has been irretrievably lost due to channelizing, 

damming, and diversion of water. The ecosystem that once supported innumerable numbers of 

pupfish no longer exists, save for a few isolated streams, springs, and wetlands. The continued 

existence of desert pupfish in the wild will depend on the efforts of humans to sustain them in 

habitats that meet their ecological needs. Artificial transplantation into suitable habitats, and 

continued maintenance of those habitats will be required. Even then, the fragmentation of a 

species that once was interconnected across many hundreds of stream miles may result in genetic 

drift and loss of viability of the population.

Bonytail Chub Gila elegans Status: Endangered

Originally found in the main stem of the Colorado River and some of its tributaries as far north as 

Wyoming, bonytail now persists in unknown numbers in some mainstem reservoirs (Mohave and 

Havasu) of the Colorado River, and maintains an apparently declining population in the Colorado

River upstream from the Grand Canyon (Minckley, 1973). Locally, the species was collected 

from the Gila River near San Carlos, in the Salt River at Tempe and at the confluence of the 

Verde River. This species is extinct in the Gila River system. It does not currently occur on Tonto 

NF.

Loss or severe degradation of riverine habitat are primary reasons bonytail have declined. As with 

other big river fishes, their highly specialized adaptation to the harsh and unusual habitats of 

southwestern rivers is best demonstrated by the fact that when that environment changed, they 

decreased from being a common species to one of the rarest.

Gila chub Gila intermedia Status: Endangered

The Gila chub was historically distributed in central and southern Arizona, mostly in small creeks 

and cienegas at less than 4,900 feet in elevation (Minckley, 1973). It now occurs in 24 isolated 

streams or cienegas in the Gila River Basin in central and southern Arizona and northern Sonora. 

The species is now considered extirpated from the waters of New Mexico. The Gila chub is still 

found as a naturally occurring species in Silver Creek, on the Cave Creek RD. Trend on the Tonto 

NF is decreasing. Two streams on the Tonto NF are designated as Critical Habitat by the USFWS.

They are: Mineral Creek on the Globe RD and Silver Creek on the Cave Creek RD. The species has 

been extirpated in Mineral Creek, but remains extant in Silver Creek on BLM lands, just 

downstream of the Tonto NF.

Adult Gila chub are highly secretive in nature and occupy the deeper waters of pools or concealed 

by cover in form of undercut banks, root wads, and instream woody organic debris. This type of 

stream structure is a key habitat component for Gila chub. Smaller individuals inhabit shallower 

stream margins and areas of aquatic vegetation.

The biology of this species is poorly understood. The species displays sexual dimorphism. Female 

chubs reach ten inches in size, but males rarely exceed six inches. Food consists primarily of 

immature and adult aquatic and adult terrestrial insects, which may fall into pools commonly 

inhabited by the species. 
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 133

Gila chub reproduces in late spring to early summer (May through June) in optimal waters 

temperatures of 68 to 75o F. Young of year chub grow rapidly their first summer and reach 

3.5 inches by winter. In a constant temperature spring in southern Arizona, the species has been 

noted to spawn throughout the year. Spawning occurs over aquatic vegetation where eggs are 

broadcast. Gila chub develop brightly orange to red-colored fins during reproductive activity.

Currently, 24 populations of Gila chub exist in the state. Of these nine are of unknown status, six

are considered unstable and threatened, eight are considered stable but threatened, and one is 

considered stable and secure. Groundwater pumping for municipal and irrigation uses, water 

diversions for irrigation, and damming of streams all contribute to drying of springs and reduction 

of streamflow, which are major threat to the species’ persistence. In addition, introduction of 

nonnative, competitive and predatory species, especially green sunfish has negatively impacted the 

Gila chub. One undescribed form of this species in southern Arizona is now extinct due to a 

combination of dam construction and introduction of largemouth bass. 

Woundfin Plagopterus argentissimus Status: Endangered

Woundfin likely occurred in larger streams throughout the lower Colorado River basin.

Specimens were taken from near the confluence of the Salt and Verde rivers, to the mouth of the 

Gila at Yuma, and thence upstream into the Virgin River (Minckley, 1973). It is entirely probable 

that the species occurred further upstream on the Verde, Salt, and Gila rivers.

Currently it is restricted to the Virgin River in Arizona, Nevada, and Utah. Attempts to increase 

its range included transplanting into the Hassayampa, Pariah, and Salt Rivers, and Sycamore 

Creek in the Agua Fria drainage. None were successful. It does not currently occur on Tonto NF.

This species is in jeopardy due to extreme stress caused by alterations in its ecosystem. Nonnative 

fishes have brought disease and parasites, and they compete for food and space and prey on 

young of woundfin. Extremes of water flow and degraded quality contributed to loss of range.

Dams and diverting water from streambeds, and groundwater pumping have caused many areas 

formerly capable of supporting the species to desiccate. Other land uses that result in a decrease 

in the amount of surface water have also contributed to their decline.

Gila topminnow Poeciliopsis occidentalis Status: Endangered

Gila topminnow was formerly widespread and the most common species in the Gila River and its 

tributaries, extending from the confluence with the Colorado up to the Frisco Hot Springs, San 

Francisco drainage, southwestern New Mexico (Minckley, 1973). It was historically also present 

into northern Sonora in the headwaters of the San Pedro and Santa Cruz rivers. The fish currently 

exists in Arizona in less than a dozen scattered populations, generally below 4,900 feet elevation.

Gila topminnow typically inhabits lower elevation (< 4,900 feet) springs, cienegas and small 

streams. It historically inhabited shallow, often vegetated margins of probably most aquatic habitats.

This species is a short lived (ca. one year) member of the live-bearing or Poeciliid family. Eggs are 

fertilized internally and young are born alive. It is a small surface feeding fish, preying on mosquito 

and other aquatic insect larvae, amphipod crustaceans, bottom debris, and aquatic vegetation. Key 

habitat components are springs, cienegas, small streams, slow current, and aquatic vegetation.

The species normally breeds from January to August, peaking in June to July; however, pregnant 

females are present throughout the year with young produced even in winter. Numbers of young 
Chapter 3 – Affected Environment and Environmental Consequences

134 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

vary from 1 up to 25 per brood. Two broods may be developed simultaneously with intervals of 

about a month between broods. At peak breeding season, most females greater than 24 mm standard 

length are pregnant. Sexual dimorphism is present and males become blackened in breeding season.

Individuals may mature in a few weeks to a few months.

Loss of habitat and nonnative, predatory fishes are the major threats to sustainability of the 

species. The introduced (late 1920s to 1930s), more aggressive and predaceous mosquitofish is 

the major nonnative fish threat to the species. In some streams, such as Cave Creek and Seven 

Springs, predation by crayfish is probably the main reason topminnow populations do not persist, 

despite repeated reintroductions. Since the late 1930s and more recently and intensively since 

1980 by the Arizona Game and Fish Department efforts to restore the species to historic range 

have been largely unsuccessful. Of 175 locations stocked, only 17 have established populations; 

these are tenuous at best. Eleven of these are on the Tonto NF (Calamusso, 2012).

Colorado Pikeminnow Ptychocheilus lucius Status: Endangered

The Colorado pikeminnow was once widespread and abundant in the Colorado Basin. Records of 

this species are scarce after the late l940s, with the last specimens collected in Arizona in 1950 in 

the Salt River near the mouth of Cibeque Creek (Minckley, 1973). Populations declined abruptly 

between 1930 to 35 during closure of Hoover Dam and the extreme drought in 1934. The 

pikeminnow exists in Arizona only as repatriated populations. It still occurs naturally in the San 

Juan River, in extreme northwestern New Mexico. On the Tonto NF, it was stocked extensively into 

the Salt and Verde Rivers during the early 1980s. Individuals still persist but the population is not 

considered to be self-sustaining. Pikeminnow populations in these drainages are designated 

“experimental non-essential” (Calamusso, 2012). Waters deeper than three feet with moderate to 

strong currents are preferred habitat. Young inhabit backwaters or various substrate types.

The Colorado pikeminnow was the "top carnivore" in the Colorado River Basin and one of the 

world's largest minnows, reaching lengths of 6 feet and 200 pounds. It was so abundant in the lower 

Colorado in the early 1900s that it was pitchforked from canals, along with razorback sucker in the 

Phoenix area. The species becomes piscivorous at just over one inch in length and becomes 

progressively more so with age. In historic Arizona, it was normally associated with other large 

river fishes (i.e., razorback, bonytail, bluehead, and flannelmouth sucker). Foods of young 

pikemminnow (one inch or less) consist of crustaceans and aquatic diptera. With increasing size 

(two to four inches) more aquatic and terrestrial insects are consumed. Pikeminnow longer than four

inches prefer a diet of fish.

Breeding behavior is unreported, largely due to turbidity during spring runoff. Based on hatchery 

observations, its behavior is probably similar to northern pikeminnow. Larvae appear to drift 

downstream to nursery areas comprised of backwaters and embayments. Breeding parallels spring 

runoff in the upper Colorado River as the hydrograph recedes and water temperatures warm 

(50o F or greater). Spawning aggregations run up to 62 miles to suitable spawning sites, typically 

riffles and shallow runs. Key habitat components are deep riffles and pools.

This species has been declared extirpated in all free-flowing rivers in Arizona. Damming of rivers 

and introduction of nonnative, predaceous species, especially catfish and bass, are and continue to 

be the major threat to the species.
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 135

Razorback sucker Xyrauchen texanus Status: Endangered

Razorback sucker is endemic to the Colorado River basin. It was once widespread and abundant in 

the Colorado Basin (Minckley, 1973). It currently exists on the Tonto NF only as repatriated 

populations in the Verde River. These are not considered to be self-sustaining populations 

(Calamusso, 2012). Habitat is medium to large rivers with swift turbulent waters as well as 

backwaters. Key habitat components are deep riffles and pools. Critical habitat on the Tonto NF

includes all of the Verde River upstream of Horseshoe Dam and the Salt River upstream of the Salt 

River Diversion Dam (Calamusso, 2012).

This species uses a variety of habitat types from mainstem channels to slow backwaters of 

medium and large streams and rivers, sometimes around cover. In impoundments they prefer 

depths of a meter or more over sand, mud or gravel substrates. Adult razorbacks tolerate a wide 

range of temperatures from near freezing to nearly 90o F, with optimum temperatures around 72 

to 77o F (HDMS, 2005).

Spawning occurs from late winter through spring along gravelly shorelines or bays. Major threats 

to the species include habitat alteration, declines in water quality, and direct competition, and 

predation by nonnative fishes. Trend is declining on the Tonto NF.

Spikedace Meda fulgida Status: Threatened

The spikedace was common and locally abundant throughout the upper Gila River basin of 

Arizona and New Mexico (Minckley, 1973). Its distribution was widespread in large and 

moderately sized rivers and streams in Arizona, including the Gila, Salt, and Verde rivers and 

their major tributaries upstream of present day Phoenix, and the Agua Fria, San Pedro, and San 

Francisco river systems. Spikedace now is restricted to less than six percent of the historic range.

In Arizona it occurs in Aravaipa and Eagle creeks, and the Verde River upstream of Tapco (above

the Tonto NF).

The species is found in only one stream, Fossil Creek, on Tonto NF; although the Salt and Verde 

Rivers and Tonto Creek are historical collection sites. Distribution and abundance of spikedace 

has been severely reduced by habitat destruction due to damming, channel alteration and 

downcutting, riparian degradation, water diversion and groundwater pumping. Introduction and 

spread of exotic predatory and competitive fishes also contributed to its decline. Resource 

activities that affect water quality, such as removal of riparian vegetation, sedimentation, or 

control of water levels, can affect spikedace habitat quality, and should be avoided or corrected.

Gila trout Oncorhynchus gilae Status: Threatened

The species was once common in most all upper elevation (above 6,500 feet) tributaries of the Gila

River headwaters and downstream to the mouth of the box canyon, northeast of Cliff, New Mexico

(Minckley, 1973). It also occurred in the headwaters of the San Francisco drainage and in Eagle 

Creek and headwaters of the Verde River, Oak and West Clear creeks, Arizona. Restoration 

activities have increased the number of streams inhabited by Gila trout to nearly a dozen. This 

species is found in one location on the Tonto – Dude Creek. Trend is decreasing and that population 

may be extirpated.

The species occurs in both pool and riffle habitats, with adults more common in the former habitat 

type and young-of-year and juveniles in the latter. Pools with woody debris for cover are optimum 
Chapter 3 – Affected Environment and Environmental Consequences

136 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

habitat for the species. Water temperatures in streams inhabited by Gila trout are generally below 

68o F. Key habitat components are riffles, pools, cold (< 68o F) water, and clean substrates.

Gila trout are generally less than ten inches total length in maximum size in the small, headwater 

habitats. The species feeds as an opportunist on aquatic macroinvertebrates, primarily caddisflies 

and mayflies. The species spawns in spring (April, May, and June) on the descending hydrograph as 

daytime water temperatures reach 46 to 50o F. Gravel cobble substrates are preferred spawning 

sites; fry emerge in about four weeks, and similar to Apache trout, reach two to four inches by the 

end of their first summer. Fecundity is low (75 to 150) eggs per female and year class strength is 

largely dependent upon flow regimes.

Similar to the Apache trout, this native southwestern trout species has been reduced dramatically in 

range. It occurs naturally in only five streams on the Gila National Forest, southwestern New 

Mexico. Introduction of nonnative trout, principally rainbow and brown trout, have resulted in loss 

of purity of populations through hybridization and competitive interactions. Recovery efforts to 

address these threats include replication of all natural populations through barrier construction, 

stream renovations and more recently, hatchery propagation.

Loach minnow Tiaroga cobitis Status: Threatened

Loach minnow was once locally common throughout much of the Gila River system, including 

mainstem and tributaries of the Verde, Salt, San Pedro, San Francisco, and Gila rivers, and the 

East, Middle and West forks of the upper Gila River up to about 7,200 feet elevation (Minckley,

1973). Its present range of occurrence represents about 15 percent of the former range, and 

includes the upper Gila River and its three forks, the San Francisco River, and Aravaipa Creek. 

Loach minnow now occur in Fossil Creek on Tonto and Coconino national forests, where it was 

stocked in 2007 (Calamusso, 2012). There are no historical records of occurrence.

Activities that affect water quality, such as removal of riparian cover, sedimentation, or control of 

water levels, can affect loach minnow habitat quality. Dams and reservoirs appear to eliminate 

loach minnow for many miles upstream and downstream. Spread of exotic predators, especially 

flathead catfish and channel catfish, can also directly reduce loach minnow populations.

Longfin dace Agosia chrysogaster Status: Sensitive

Longfin dace is widespread in the Gila River Basin, Arizona and New Mexico, in the Bill Williams 

River, Arizona, and in the Yaqui, Magdalena, and Sonoyta basins of northern Mexico (Minckley,

1973). Although widely distributed and present in all habitable waters in the Southwest, it is 

reduced in abundance in larger streams and above 4,920 feet elevation. Longfin dace are widely 

distributed on the forest. Trend is stable but may be declining long-term due to nonnative fish 

encroachment.

The longfin dace is a small minnow (< 2.3 to 2.75 inch adult size), normally occurring in schools in 

open waters. The species is highly adapted to the rigors of southwestern streams and rivers. It is 

reported to survive in algae mats during midday loss of surface flow in small streams. Aquatic 

macrophytes along stream margins also are commonly inhabited to reduce exposure to extreme 

thermal conditions (> 86o F). Longfin dace feed on detrital material, filamentous algae, and 

microscopic crustaceans. This species frequents shallow, sandy-bottom glide and run habitats with 
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 137

velocities of less than 2.5 feet/sec. This shallow, sandy, low-velocity water is a key habitat 

component for longfin dace.

Longfin spawn over a long period of time - December through July to September in low elevation 

desert streams and rivers, and from spring to early summer at upper (> 3280 feet) elevations. Spates 

from summer monsoon rains may stimulate multiple spawning during a year. Saucer shaped 

depressions are excavated in fine sand typically along stream margins. These nests, often 

concentrated in clusters, are 6 to 8 inches wide, 1.5 to 2 inches deep with margins above 

surrounding stream substrates. Spawning occurs over these nests, eggs are deposited, young hatch 

in 4 days, young remain in nests until yolk-sacs are absorbed. Growth is rapid, with young spawned 

in the spring reaching 1.75 to 2 inches and capable of spawning the same year.

Longfin is very likely the most common and highly adapted native southwestern cyprinid, 

occupying waters in low hot deserts through mid elevation, canyon-bound streams to upper 

elevation, clear cool creeks in the conifer zone. Recent declines in the upper Verde River population 

appear to result from a combination of habitat change, lack of flooding and introduced, predatory 

fishes such as smallmouth bass. The primary physical threats are drought and diversion and 

pumping of stream aquifers, resulting in loss of surface flow.

Desert sucker Catostomus clarki Status: Sensitive

Desert sucker presently occurs in the Salt and Verde Rivers on the Tonto NF. It occupies low to 

high gradient riffles (0.5 to 2.0 percent gradient) over pebble to cobble substrates containing 

water velocities of 1.1 to 1.5 feet per second (BISON, 2010). Key habitat components are highgradient riffles of moderate to swift velocity current, moderate depth (< 1.6 feet), and over pebble 

to cobble-boulder substrate. The species also inhabits pools with moderate current (Minckley,

1973). 

Breeding generally occurs in riffles; however, it has not been specifically studied. Breeding season is 

late winter (January to February) to early spring (March to April). Threats include introduced species 

and habitat alteration.

Sonora sucker Catostomus insignis Status: Sensitive

Sonora sucker is widespread and abundant in the Gila and Bill Williams’s river drainages in 

Arizona, and the Gila and San Francisco drainages in Southwestern New Mexico. The species is 

widespread and abundant in the Verde and Gila headwaters. Habitat is streams and rivers from 

300 to 3,000 m. in elevation, primarily in pool habitats over sand/gravel substrates (Minckley,

1973).

This fish can attain a size of 2.6 feet and a weight of greater than 4.4 pounds. It was used as food 

by early primitive human populations. Its food habits vary with availability. In one stream, 

Aravaipa Creek, it is principally a carnivore, whereas elsewhere in pool habitats diet consists of 

plant debris, mud, and algae. It has been observed to "suck" cottonwood seeds at the water’s 

surface much like the common carp does. Young often feed in large schools at stream margins on 

micro-crustaceans, protozoans, and other animal and plant groups. Key habitat components are 

pools with sand/gravel substrates for adults and shallow, low velocity riffles and backwaters for 

young.
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138 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

Similar to most slim-bodied suckers, the species spawns in smaller streams over gravel substrates.

Males darken in color and often display extreme tuberculation. Males flank a single, larger 

female. Gametes are emitted with considerable to extreme substrate agitation and fall into gravel 

interstices. Cleaning of gravels occurs much as reported for salmonid species. Breeding season is 

protracted, from as early as January to February at low elevations, to as late as July.

Threats to the species are construction and operation of dams, diversions, groundwater pumping, and 

introduced species.

Headwater chub Gila nigra Status: Candidate

This species occupies upper reaches of tributaries throughout the Colorado River Basin. On the 

Tonto NF, it occurs in upper Tonto Creek and tributaries, the East Verde, upper reaches of Fossil

Creek, and Deadman Creek (tributary to the Verde River) on the Tonto NF (HDMS, 2005;

Calamusso, 2012). It is often found in association with roundtail chub. Headwater chub is most 

commonly a pool inhabitant, with associated cover in the form of undercut banks, root wads and 

boulders, and containing sand/gravel substrates. This type of cover is a key habitat component for 

headwater chub.

Headwater chub is an omnivorous fish, consuming a wide variety of aquatic and terrestrial 

insects. Larger individuals are piscivorous.

Similar to roundtail chub, this species spawns in May when water temperatures reach about 72o F.

Spawning occurs in pool-riffle habitats or in riffles immediately above pools. Fecundity is agedependent, with 5 year-old females producing over 30,000 eggs. Young grow to 2.75 inches in 

their first year. Growth rate appears to be directly proportional to habitat (pool) size.

Introduced, predatory sport fishes are perhaps the greatest threat to the species. Other threats include 

alteration and loss of habitat due to poor land use practices.

Roundtail Chub Gila robusta Status: Sensitive

Roundtail chub are found in moderate to large rivers of the Colorado River Basin. In Arizona, it 

still occurs in the mainstem and tributaries to the Verde and Salt Rivers, although populations 

have declined considerably during the past few decades (Minckley, 1973). On Tonto NF, it 

occurs in the Verde and Salt Rivers and many of their larger tributaries including Ash Creek, 

Cherry Creek, lower reaches of the East Verde, lower reaches of Fossil Creek, Rock Creek, Wet 

Bottom Creek, Salome Creek, Sycamore Wash (tributary to the Verde near Sheep Bridge), and 

the South Fork of Deadman Creek (Calamusso, 2012).

Roundtail chub occupy cool to warm water, mid-elevation streams and rivers where typical adult 

microhabitat consists of pools to eight feet deep adjacent to swifter riffles and runs. Cover is 

usually present and consists of large boulders, tree rootwads, submerged large trees and branches, 

undercut cliff walls, or deep water. Smaller chubs generally occupy shallower, low velocity water 

adjacent to overhead bank cover. Roundtail chub appear to be very selective in their choice of 

pools, as they are commonly found to congregate in certain pools, and are not found in similar, 

nearby pools.

Spawning takes place over gravel substrate. Tolerated water temperatures range up to 80o F.

Young chubs feed on small insects, crustaceans and algal films, while older chubs move into 
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 139

moderate velocity pools and runs to feed on both terrestrial and aquatic insects along with 

filamentous algae. Large roundtail chubs take small fish, and even terrestrial animals such as 

lizards that fall into the water. Roundtail chub breed in early summer, often near beds of 

submergent vegetation or other kinds of cover such as fallen trees and brush, as spring runoff is 

subsiding. Fertilized eggs are randomly scattered over gravel substrate with no parental care.

Individuals up to 20 inches in length and weighing 2 pounds may occur, but typically maximum 

size is between 10 and 16 inches.

The type of habitat seemingly preferred by adult roundtail chub is rapidly disappearing from 

southwestern streams as the very large and old riparian trees are not being replaced. Maintenance 

of natural flow regimes and occasional flooding are apparently important to continued survival of 

local populations. Predation by flathead catfish and smallmouth bass has been implicated in 

elimination of populations.

Environmental Consequences

Proposed Action: Integrated Vegetation Management

Direct and Indirect Effects

Impacts of treatment methods are evaluated based upon their effect on threatened, endangered, 

proposed and sensitive (TEP&S) fish and/or critical habitat (CH). Our analysis indicated there 

would be no direct effects to TEP&S species because aquatic weed treatments are not proposed.

Thus fishes and their habitats would not be impacted.

While weed species cover a relatively small proportion of the Tonto NF, they do occur throughout 

its 2,872,876 acres. Treatments for noxious weed abatement and eradication will take place in 

each Ranger District and across ecotypes ranging from Sonoran Desert to mixed conifer forest.

Watersheds within the project area include: Salt River, Verde River, Agua Fria, New River, and 

Cave Creek. Repeated treatments using various methods would be necessary for most weed 

species because seeds in the soil can be viable for 5, 10 or more years. Therefore, recurring 

treatments would be authorized until the desired control objective is reached. The annual 

combination of methods to be used is expected to vary depending on specific conditions.

The treatments identified under the Proposed Action (manual, mechanical, cultural, chemical) 

will cause minimal effects to fish and their habitats. Some siltation may occur due to actual weed 

treatment and work crews moving on the ground, but this should be insignificant as buffer strips 

of riparian vegetation will impede soil movement toward streams. If no buffer is present the short 

term disturbance and added silt load will be of minor significance over the long term. 

Biological controls are predicted to cause no effect on fishes and watershed within treated areas.

The control of these noxious plants will improve habitat conditions for native fish species that 

will result in higher ground covers and a lowering of the potential for sedimentation into 

perennial streams. However, we anticipate the most important aspect of reaching control 

objectives is the ability to stop the spread of nonnative tree species such as: tree of heaven, 

Russian olive, and saltcedar. Saltcedar is widespread in the Verde River drainage and presents real 

problems in the form of changes to channel morphology, presence of native insects and 

microfauna, fire (and consequent water quality damage), and continuation of a native tree 

community. Treatment of nonnative trees and noxious weeds will accomplish two objectives:

preventing the loss of any additional habitat and improving the regeneration of native willows and 
Chapter 3 – Affected Environment and Environmental Consequences

140 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

other species on the treated acres. Habitat conditions for fishes in this drainage may improve once 

native plant communities expand. Native plant communities will provide a more natural riparian 

component to the riparian community and thus return overall drainage characteristics to a state 

where components evolved in concert with other constituents. Use of weed-free seed mixes and 

mulches would also promote native vegetative growth or inhibit/prevent weed expansion as 

control objectives are met.

All herbicides proposed for use are characterized by relatively low aquatic toxicity under typical 

concentrations (U.S. Forest Service, 1998). All herbicide applications would follow EPA label 

requirements, U.S.D.A. policy, Forest Service direction, and mitigation measures. There would be 

no aerial application of herbicides by either fixed-wing or rotary aircraft and no aquatic 

applications of herbicides. Only herbicides labeled for use adjacent to water would be used within 

riparian zones and areas with shallow ground water. These include aquatically labeled 

formulations of glyphosate, imazapic, imazapyr, and triclopyr. There would be no broadcast 

spraying in riparian zones. All treatments of weed tree species would be either cut stump, or 

straight injection into the bark of the tree.

Burning/torching/flaming is conducted by burning individual plants and does not cause off-site 

impacts that would affect water quality or fish habitat.

Alternative 1: No Action (continue ongoing treatments)

Direct and Indirect Effects 

This alternative would not implement a comprehensive weed program within the project area.

Riparian areas would be impacted by continued expansion of weeds that would result in the 

reduction or loss of native riparian vegetation. Riparian areas along Tonto NF riparian corridors 

would be impacted and may affect overall watershed function. The loss of native riparian 

vegetation could result in long-term alteration of the aquatic habitat by: (1) reducing streambank 

stability that may increase erosion potential and sediment input into the stream channel; (2) 

potentially changing stream channel morphology (e.g., widths and depths) that would reduce 

aquatic habitat diversity; and (3) increasing the probability of reducing/altering the stream 

production of terrestrial and aquatic insects associated with native vegetation and clean riffle 

areas. Also, the probability increases for catastrophic fire hazard in tamarisk and Russian olive 

infested areas. These nonnative plant communities place native, non-fire adapted plant 

communities at risk of destruction or reduction. An indirect impact of this effect would be an 

even quicker expansion of saltcedar since this species is promoted by fire events. Water 

consumption rates are also higher in these nonnative communities and could lead to lower base 

flow. This could lead to a reduction or loss of habitat diversity, spawning habitats, and food 

supply (e.g., aquatic insects) from alteration of aquatic habitat for native TEP&S fishes and 

increased sedimentation in CH (Critical Habitats), which could directly affect spawning success 

and recruitment of TEP&S fishes.

Upland areas also have the potential to be negatively impacted by continued expansion of weeds.

Loss of native vegetation often results in the loss of vegetative ground cover in turn reducing 

infiltration rates, increasing runoff, and soil erosion in affected areas. The spread of weeds could 

also alter the natural fire regime in these uplands (similar to riparian areas) and cause an increased 

probability of catastrophic wildfire events. The potential for increased runoff and soil erosion 
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 141

with subsequent input of sediments, ash, and nutrients into streams could occur and may impact 

TE&S and native fishes and their habitats.

Manual removal of weeds and small scale burning/flaming may increase siltation for the shortterm by movement of crews in and around streams, as for the proposed action.

Implementation of this action would result in the greatest expansion of weeds throughout the 

project area and riparian corridors. The indirect impact of this will be a general deterioration of 

aquatic habitat conditions for TEP&S fish species and/or CH because of degrading riparian and 

watershed conditions.

Weed populations would continue to advance and impact uninfested areas. Effect of these actions 

on fish populations is predicted to be insignificant. 

Cumulative Effects

Under alternative 1, noxious and invasive weeds would expand from the current population over 

the next ten years. All noxious and invasive weeds would increase in the project area.

Invasive tree species and other noxious weeds in riparian areas, together with impacts from 

increased recreational activities effects could result in lowered water tables and decreased water 

quality for fisheries.

Expansion of current noxious and invasive weed populations will also result from the Forest 

Service implementation of numerous ground-disturbing projects including road construction and 

maintenance, timber sale activities, forest restoration projects, prescribed burning, revisions of 

allotment management plans, watershed restoration, road obliteration, and mining. Inclusion of 

weed prevention best management practices in all project planning should reduce the potential of 

new introductions to low levels.

Alternative 2: Integrated Vegetation Management Excluding the Use of Herbicides

Direct and Indirect Effects 

The treatments prescribed in alternative 2 (mechanical, manual, biological, prescribed burning 

and cultural methods) would not be as effective as the Proposed Action in treating noxious weeds 

on forest lands. Weed populations would continue to advance and impact uninfested areas. Effect

of these actions on fish populations is predicted to be insignificant. 

Positive effects of this action on TE&S fish, CH, and native fishes would be minimal.

Cumulative Effects for the Proposed Action and Alternative 2

If any of the action alternatives are selected, the potential exists for the greatest benefit to TE&S 

fishes, CH, and native fishes through large-scale reduction in alien tree species and noxious weed 

infestations.

There would be no direct effects to TE&S fish and/or CH based on the use of mitigation measures 

and best management practices. Continuation of any invasive plant control program would have 

beneficial effects to TEP&S fish and/or CH due to containment and/or control of weeds within 
Chapter 3 – Affected Environment and Environmental Consequences

142 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

roadway corridors. This would prevent, or at least reduce, the potential of these roadways from 

infesting the riparian areas on the forests.

The Forest Service has acquired instream flow rights for the Verde Wild & Scenic River from 

Beasley Flat downstream 40 miles to the confluence of Red Creek. Application for instream flow 

rights has been made on the upper Verde River for the benefit of threatened and endangered 

fishes. Instream flow assessments are being conducted for several tributaries of the Verde River 

and for East Clear Creek with TEP&S fish and/or CH for future application for instream flow 

rights. Acquisition of instream flow rights in the project area would have long-term beneficial 

effects to TEP&S fish and/or CH by maintaining adequate water quantity to sustain populations.

Livestock grazing occurs on many forest allotments, state lands, and private lands. Livestock 

grazing has been excluded along the Verde and Salt Rivers and other drainages for the benefit of 

threatened and endangered fish and/or CH. Range utilization standards and guidelines are in place 

on forest lands and are expected to improve riparian and watershed conditions and would have 

beneficial effects to TEP&S fish species and CH by reducing the potential for sedimentation.

Over the next five years, control of aquatic noxious weeds like Eurasian water milfoil will be 

evaluated. Treatments would occur in occupied habitat of TEP&S fish and/or CH in the project 

area. This project would have an overall beneficial effect to TEP&S fish and/or CH by returning 

aquatic habitat to historic conditions.

Social Concerns

Human Health

Short History of Herbicide Use on the Tonto National Forest

The earliest documented attempts to use herbicides in vegetation management on the Tonto NF

date to the 1930s. There are photographs taken in 1934 and 1936 in files at the Tonto NF

Supervisor’s Office, of a project to control chain-fruit cholla with arsenic pentoxide. Exact 

location is not recorded, but there were probably two sites, at or near Schoolhouse Point and at 

Horrell Experimental Plot on the Globe RD.

In the 1960s, the Forest Service initiated a program to conduct vegetation type conversions from 

chaparral to grassland. The purpose of this was to increase runoff, and consequently increase the 

forest’s ability to provide water for the Phoenix metropolitan area. Arizona had experienced a 

drought during the 1950s, and water officials were concerned that the existing water supply and 

delivery system would not be adequate for the growing metropolis.

As early as 1962, herbicides were being aerially applied to chaparral in the Brushy Basin area 

near Four Peaks. 2,4-D was used in 1962, followed by pentachlorophenol, a defoliant, in 1963

(Tonto NF, 1964).

Several methods were used to remove chaparral vegetation from the Three Bar Experimental 

Watersheds in the 1960s: prescribed burning, grazing by goats, and application of herbicides.

Herbicides were applied both by hand and aerially by helicopter from 1960 to 1969. Herbicides 

used were: 2,4,5-T (aerially applied at the rate of 1.6 lbs/acre), pelleted fenuron (hand applied at 

rates from 3.6 to 18.3 lbs/acre), granular tordon (hand applied at 9.3 lbs/acre), and granular 

Tandex, or karbutilate (hand applied at 4.4 lbs/acre in 1968, and aerially applied at 20 lbs/acre in 

1969) (RMFRES, n.d.).
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EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 143

A report written in 1969 gives a total area of 17,700 acres of chaparral vegetation on the 

Tonto NF that had been treated by fire and/or herbicide to convert it to a grassland vegetation 

type. Sites that were sprayed with herbicides included Brushy Basin near Four Peaks 

(8,000 acres), Kellner and Icehouse canyons and Russell Gulch in the Pinals (2,300 acres), and 

Hutch Mesa, east of Cordes Junction (1,000 acres) (Tonto NF, 1969). In Brushy Basin, 2,4-D, 

2,4,5-T (ester formulations of both) and fenuron were aerially applied by helicopter. Aerially 

applied herbicides were mixed in a carrier of diesel and water (Tonto NF, n.d.).

The Tonto NF, in cooperation with Salt River Project, conducted an experimental program using 

the herbicides 2,4-D, 2,4,5-T and Silvex (2,4,5-TP) to kill chaparral vegetation in the Pinal 

Mountains, south of the town of Globe, Arizona. These herbicides were applied by helicopter to 

watersheds ranging in size from 1,060 to 1,370 acres from 1965 through 1969 (Tonto NF, 1969). 

In June 1969, herbicides from the helicopter drifted over populated areas. Residents of these areas 

near Globe exhibited various physical symptoms ranging from skin rashes to cancer, over the 

ensuing years. In 1970, Billee Shoecraft and 20 other residents of Globe filed suit against Dow 

Chemical, three other chemical companies that manufactured the herbicides that were used, the 

helicopter company, a state agency that helped finance the project, and the U.S. Forest Service 

(Shoecraft, 1971; Trost; 1984, & Doyle, 2004). By 1974, most of the chemical companies and the 

helicopter company settled out of court. In 1981, Dow also settled out of court, with no admission 

of liability.

At the time of the lawsuit, Dow maintained that 2,4,5-T and Silvex were non-toxic to humans or 

animals. Dioxin was a known contaminant of both of these herbicides. Testing conducted at that

time measured only for acute effects, not chronic effects of long-term low dose exposures to 

pesticides. In fact, before the EPA took over registration and approval of pesticides from the U.S.

Department of Agriculture, chemical companies submitted only “scanty data – largely confined to 

acute poisoning effects – to a loosely monitored... system of review that did little original testing, 

that did not routinely rethink a chemical’s registration if new information about harmful effects 

came to light, and that removed a chemical from the market only under extreme pressure” (Trost,

1984). Dioxin is now known to be a carcinogen and teratogen (a substance that can cause birth 

defects) at levels lower than laboratory equipment could detect in the 1960s. A contractor hired 

by EPA to measure dioxin content in technical grade Silvex from two different manufacturers 

reported dioxin content ranged from 0.012 to 0.024 ppm (EPA 1979). Although Silvex 

manufacturers attempted to remove this contaminant, it could not be totally removed. It was not 

until 1979, and after many arguments about exactly what quantity of dioxin contaminant 

produced teratogenic and other adverse health effects, that an order by EPA (EPA, 1979) 

suspended distribution, sale and use of 2,4,5-T and Silvex for forestry, rights-of-way and pasture 

use due to the finding that they posed an imminent hazard to humans and the environment. The 

EPA reported that Silvex (which is always contaminated to some extent by dioxin) caused 

reproductive and oncogenic (cancer causing) effects in test animals. Dioxin was measured in the 

2,4,5-T used at Globe to be 0.5 ppm (Trost, 1984). Dow discontinued manufacture of 2,4,5-T in 

the U.S. in 1983. Today both Silvex and 2,4,5-T are on EPA’s list of banned pesticides 

(Scorecard, 2005).

In 1984, EPA conducted tests of soils and water in the area of the 1969 Globe spray project. The 

EPA found dioxin (2,3,7,8-TCDD) in high concentrations at all three helispots used for mixing 

herbicides during that project. Levels ranged from 43 to 6623 ppt (parts per trillion) (6623 ppt = 

6.623 parts per billion or 0.00623 parts per million). The authors of the paper documenting this 

monitoring reported that the upper value of TCDD found at one of the helispots was the highest 
Chapter 3 – Affected Environment and Environmental Consequences

144 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

level reported at any herbicide use area sampled under the National Dioxin Study (Simanonok & 

Beekley, 1986). In 1984, the Centers for Disease Control advised that soil levels (in residential 

areas) above one part per billion of TCDD could result in an unreasonable risk to human health.

They qualified this statement by stating that this should not be viewed as a universal standard but 

as an operational starting point to analyze each situation. They also stated that soil levels of 

TCDD in pastures where cattle graze might have to be lower because of the potential for 

bioaccumulation (CDC, 1984).

Sediment from Kellner Creek, Icehouse Creek, Pinal Creek, and Blue Tank (a stock tank just 

downstream of the area where the herbicides were applied) were also sampled for TCDD 

(dioxin). At detection limits of 1.0 to 3.0 ppt, TCDD was not detected in any of the sediment 

samples. Wildlife were taken and tissue samples shipped to U.S. EPA laboratories for highresolution testing for TCDD. Species sampled were coyote, black rattlesnake, deer, javelina, 

glossy snake, Gambel’s quail, garter snake, a toad, and leopard frogs. TCDD was not detected in 

any of the animal tissues. They concluded that detectable levels of TCDD persist for at least 

15 years where mixing and loading occurred, but that dioxin was not detected in stream sediment 

or wildlife samples.

In 1991, the Arizona Department of Environmental Quality conducted tests for presence of 

Silvex, 2,3,7,8-TCDD, and isomers of these chemicals in private wells in Kellner Canyon, in 

sediments from Kellner Creek, and in sediments at two helipads used for herbicide mixing during 

the spray operation in 1969. Their tests detected no herbicides or their metabolites in the well 

samples or creek sediments. Silvex and TCDD were detected at the helipads, on ridges above 

Kellner Canyon and Russell Gulch (ADEQ, 1992).

In 1992, the Arizona Department of Environmental Quality repeated tests for presence of Silvex, 

2,4-D, 2,4,5-T and 2,3,7,8-TCDD in sediments of Kellner Canyon, and in the same two private 

wells. They did not detect any of these chemicals, but another dioxin, OCDD was detected in 

both wells and in a sediment sample behind a waterfall in Kellner Canyon. OCDD is a dioxin 

which is several orders of magnitude less toxic than TCDD (ADEQ, 1993).

In response to an inquiry from Representative J.D. Hayworth in 1997, Dr. David Satcher of the 

Agency for Toxic Substances and disease Registry (ATSDR) wrote that his agency had reviewed 

the 1991 through 1993 reports from ADEQ on sampling of sediment and groundwater in the area 

of the 1969 spray project south of Globe. ATSDR agreed with ADEQ that there was no public 

health hazard at that time. The contaminated soil found in 1985 at three helipads was not 

remediated, due to their remote locations (Satcher, 1997). A memo from the Petition Screening 

Committee at the ATSDR in 1997 explained that they did not recommend further evaluation of a 

petition to conduct a public health assessment, due to the fact that residual dioxin in the soil at 

helicopter landing/loading sites seemed to have decreased from 1985 to 1991, and the 

concentration of dioxin in groundwater and in surface water was found to be below levels of 

health concern. This determination was based upon available sampling data (Steward, 1997).

These documents constitute the most recent documentation of herbicide residual monitoring for 

this area.
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 145

Current Use of Herbicides on the Tonto and Lands Surrounding the Tonto 

National Forest 

Use of herbicides on this forest is currently limited to three types of projects: “housekeeping” 

type uses at Administrative and Recreation sites, a small-scale project on the Pleasant Valley 

Ranger Station, and treatment of noxious weeds along federal and state highways that run through 

the forest.

One project has been approved for application of herbicides, in the horse pasture of the Pleasant 

Valley Ranger Station, where a Decision Memo was signed in 2004 for a project to control 

yellow starthistle using prescribed fire, grubbing, and herbicide.

In 2004, a decision was made that allows application of 16 different herbicides within federal and 

state highway rights-of-way through all National Forests in Arizona. Up to 1,000 acres per year 

may be treated on the Tonto NF under this decision (U.S.F.S., May 2004).

Concerns of People with Multiple Chemical Sensitivity

Some users of the Tonto NF are afflicted with a syndrome termed “Multiple Chemical 

Sensitivity” (MCS). About 16 percent of the population has multiple chemical sensitivities;

four percent of these are more serious cases (U.S.F.S., Feb. 2004). To this portion of the 

population, many substances such as cleaning supplies, house paint, new building materials, 

antibiotics, insecticides, and herbicides cause adverse reactions. Since there is no cure for MCS, 

most people create living spaces so they are not exposed to chemicals that would cause a severe 

reaction. This includes living in communities that are not impacted to a great degree by chemical 

use, and living in specially built homes. When chemicals are introduced into or near the living 

areas of MCS-afflicted people, they must often find a chemical-free place to live for a period of 

time. They may take refuge in National Forests to escape a potentially dangerous health situation.

Potential effects of herbicide use to MCS-afflicted individuals from recent projects approved for 

treatments along highways have been mitigated by creation of a toll-free number where they can 

hear a schedule for ADOT’s treatments along highway rights-of-way through Arizona national 

forests. In the four years this protocol has been in effect, there have been no reports of ill effects 

to any people. ADOT has now dropped its toll-free notification number, due to lack of use by the 

public.

Environmental Consequences

The analysis area for this resource is the National Forest and neighboring communities. Human 

health may be directly influenced when people utilize the forest, and activities on the forest may 

have indirect effects on adjacent inhabited areas. Human use of the forest is mainly associated 

with recreation, hunting and fishing, use of grazing allotments, firewood harvest and gathering of 

traditionally used plants. Effects to this resource can be seen in the degree to which human health 

is affected by implementation of the selected action.

Proposed Action: Integrated Vegetation Management 

Direct and Indirect Effects 

Workers who are applying herbicides have the highest exposure to the herbicides. Registration by 

the EPA confers a level of confidence that an herbicide poses low risk to the user. This is 
Chapter 3 – Affected Environment and Environmental Consequences

146 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

adequate for the general public, who routinely purchase and use all of the herbicides that are 

proposed for use by this project, with the exception of picloram, which is a restricted-use 

herbicide and requires certification to purchase and use. The Forest Service is obligated, for the 

protection of its own employees and the general public, to conduct the highest quality risk 

assessment they possibly can, for herbicides that have been registered by EPA.

A considerable body of information from tests on laboratory animals is available for the 

herbicides considered for possible use in controlling noxious weeds. Most of these tests were 

conducted as a requirement for the U.S. Environmental Protection Agency (EPA) for the 

registration process. All of the herbicides proposed for use have been subjected to long-term 

studies that test for general systemic effects, effects on reproductive and developmental toxicity 

(birth defects), mutagenicity (change in genetic material), neurotoxicity (effect upon nerve 

tissue), carcinogenicity (tendency to produce cancer) and immunotoxicity (effect on the immune 

system). NOEL measures (a laboratory-derived maximum amount of active ingredient that 

produces “No Observable Effect Level”) are available for most types of these tests.

Extrapolating a NOEL (No Observable Effect Level) from an animal study to humans is an 

uncertain process. The EPA compensates for the uncertainty by dividing NOELs from test 

animals by a safety factor, typically 100, to derive a Reference Dose (RfD). In other words, the 

human RfD is 1/100th of the NOEL for an animal study. The RfD, also known as the Acceptable 

Daily Intake (ADI) is defined as the daily exposure over a human lifetime (assumed to be 70 

years) at which there is a reasonable certainty of no harm. The dose is expressed as milligrams of 

herbicide per kilogram of body weight per day (mg/kg/day). Acceptable reference doses for 

herbicides in this analysis are displayed in table 14. Toxicity categories are defined by the U.S. 

EPA as follows:

Category I – Highly Toxic-- oral LD50 up to 50 mg/kg

Category II – Moderately Toxic-- oral LD50 between 50 and 500 mg/kg

Category III – Slightly Toxic -- oral LD50 between 500 and 5000 mg/kg

Category IV – Relatively Nontoxic -- oral LD50 greater than 5000 mg/kg

Eight of the herbicides proposed for use fall within the category of “Relatively Nontoxic,” the 

other five are in Category III, “Slightly Toxic.” See table 14 for illustration of toxic amounts, as 

determined by extensive laboratory testing.
Chapter 3 – Affected Environment and Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 147

Table 14. Acceptable daily intake (mg/kg/day) for selected herbicides as compared with

other compounds 

Herbicide Oral LD50 for 

rats (mg/kg) 1 ADI/RfD2 Equivalent human dose

EPA Category of Use 

(for herbicides)

Highly Toxic Category (Category I): LD50 = 0 to 50 mg/kg

Botulinus toxin 0.0000012 *

A taste to a 

teaspoonful

N/A

TCDD (a dioxin) 0.00022 to 0.1 * N/A

Strychnine 16 * N/A

Nicotine 50 * N/A

Moderately Toxic Category (Category II): LD50 = 50 to 500 mg/kg

Paraquat 

(herbicide) 57 0.005

A teaspoonful to 

one ounce

Restricted Use

Pure caffeine 192 * N/A

2,4-D 275 0.3 General Use

Slightly Toxic Category (Category III): LD50 = 500 to 5000 mg/kg

Triclopyr 630 0.05

One ounce to one 

pint

General Use

Clopyralid 3000 0.15 General Use

Dicamba 750 to 3000 0.045 General Use

Sethoxydim 2676 to 5000 0.09 General Use

Aspirin 1500 * N/A

Table salt 3000 * N/A

Picloram 3000 to 5000 0.2 Restricted Use

Relatively Nontoxic (Category IV): LD50 > 5000 mg/kg

Chlorsulfuron 5,545 0.05

More than one 

pint.

General Use

Clopyralid >5,000 0.15 General Use

Glyphosate >5000 2.0 General Use

Imazapic >5,000 0.5 General Use

Imazapyr >5,000 2.5 General Use

Metsulfuron 

methyl >5,000 0.25 General Use

Sulfometuron 

methyl >5,000 0.02 General Use

Aminopyralid >5,000 0.5 General Use

1 Oral LD50 is the dose required to kill 50 percent of test animals.
Chapter 3 – Affected Environment and Environmental Consequences

148 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

2 ADI (Acceptable Daily Intake) and RfD (Reference Dose) = the daily exposure over a human lifetime 

(assumed to be 70 years) at which there is a reasonable certainty of no harm.

* No reference dose is available or established. 

^The EPA classifies herbicides for “general use” or “restricted use.” General use herbicides can be used 

by anyone, and if label directions are followed carefully, there is little chance of harm to humans or the 

environment. Restricted use herbicides are frequently more toxic than general use herbicides or

potentially damaging to the environment. Only certified applicators that receive special training in 

handling and applying herbicides are allowed to purchase and apply restricted use herbicides.

Sources for information in table 14: Botulinus toxin: Univ. of Florida 2011; TCDD: Centre for 

Ecological Sciences Indian Institute of Science, Bangalore, India (2011); Strychnine, Nicotine & 

Paraquat: IPCS, Chemical Safety Information from Intergovernmental Organizations; Caffeine: 

MallinckrodtBaker, Inc; aspirin and table salt: Fisher Scientific; all other chemicals: SERA Risk 

Assessments.

In evaluating the potential impact of herbicides, it must be kept in mind the small amount that is 

typically used on National Forest System lands. This is normally less than two pounds per acre.

Some products are applied at an ounce per acre.

Direct effects for workers are usually those that may occur from direct contact (dermal exposure) 

with an herbicide (Durkin, 2007). Applications will be by backpack and ground based mechanical 

methods, and the area treated per day will be dependent on the specific site and the type of 

application. The proposed noxious weed treatments fall within the typical scenario for herbicide 

use including proposed application rates and acres treated per day per worker in specific risk 

assessments, discussed below. The conditions when an herbicide is applied will affect the 

exposure, and implementation of the mitigation measures covered in appendices D and G will 

reduce possible exposures. Also, using personal protective equipment, as covered in the Safety 

and Spill Plan (Appendix E) will lower exposure of workers by as much as 68 percent (U.S.F.S.,

1992), since most application exposure is through the skin.

Worker doses for the herbicides proposed for use are likely to be well below the RfD if 

reasonable safety precautions are followed. The risks would be further reduced because the 

applicator would likely be exposed for a few weeks per year, at most. The RfD assumes a lifetime 

of daily doses.

In addition, since 1998, updated Human Health and Ecological Risk Assessments have been 

prepared for herbicides commonly used by the Forest Service by an independent company, 

Syracuse Environmental Research Associates, Inc. (SERA). SERA’s Risk Assessments have been

meticulously researched and documented for all of the herbicides proposed for use. Each risk 

assessment uses an extremely thorough literature review of environmental and human effects to 

create a model. In these documents, the process of risk analysis is used to quantitatively evaluate 

the probability that a given pesticide use might impose harm on humans or other species in the 

environment. This model can be used with default settings, which are described in detail, or can 

be modified to portray more closely a specific situation for a Forest Service project. Worksheets 

are filled out on the computer, and the model run to determine whether effects qualify as 

acceptable risks (hazard quotient less than 1.0), or risks that either must be mitigated in some way

or eliminate use of that herbicide for the project. These risk assessments can be obtained on a 

Forest Service web site (http://www.fs.fed.us/foresthealth/pesticide/risk.shtml). A list of SERA 

Risk Assessments is found in appendix F. All of these risk assessments are incorporated by 

reference.
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EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 149

The Risk Assessment has three parts:

• Exposure Analysis. This analysis estimates the range of possible doses to workers, the 

general public, aquatic organisms, etc. A variety of scenarios and exposure pathways are 

examined that could result in dermal and oral exposures.

• Hazard Analysis. Tests and data related to the toxicity of herbicides are reviewed under 

this analysis. Data are reviewed to indicate the doses at which toxic effects occur and, 

conversely, levels at which no toxic effects are seen (NOEL).

• Risk Analysis. Under this analysis, the dose levels calculated in the exposure analysis are 

compared to the NOEL levels to determine the effects of herbicides.

Concern has been raised about the collection and consumption of native herbs, medicinal plants, 

berries, etc., that could be inadvertently sprayed. The main concern appears to center on the 

increased risk of cancer that could result from exposure to low levels of an herbicide. All of the 

herbicides being considered for use have undergone testing for cancer, and all have been 

classified as Group E – chemicals that are conclusively non-carcinogenic, with the exception of 

triclopyr, which is Group D – not classifiable as to carcinogenicity. There are no epidemiology 

studies or case reports that demonstrate or suggest that exposure to any of the herbicides proposed 

for use in this document leads to cancer in humans (Durkin, 2001, 2003a &b; Klotzbach & 

Durkin, 2004a, b & c; Durkin & Bosch, 2004; & Durkin & Follansbee, 2003, 2004a, b & c).

The Environmental Impact Statement for Integrated Treatment of Noxious or Invasive Weeds on 

the Coconino, Kaibab and Prescott national forests, chapter 4, has a comprehensive section on 

herbicide impurities, surfactants, adjuvants, inert ingredients and dyes. It concludes none of these 

will have significant adverse effects on human health in the context, quantities and situations they 

will be used on the National Forests. With the exception of sethoxydim, the herbicides proposed 

in this EA are similar to those listed in the EIS for the Coconino, Kaibab, and Prescott national 

forests. Therefore, this document adopts the discussion in the EIS by reference (U.S.F.S., Feb 

2004).

Most of the herbicides that will be used can cause skin and/or eye irritation, if not washed off 

after contact and if contact occurs before the products have biodegraded.

Studies by the California Environmental Protection Agency, Department of Pesticide Regulation, 

for tribal people who gather plant materials for food, medicinal, ceremonial, or basketry purposes 

show that triclopyr and glyphosate were detectable on buckbrush shoots and manzanita berries at 

36 weeks after spraying (Segawa, et al., 2001). This study showed a low incidence of off-site 

movement of herbicide applied from backpack sprayers, with no residue from these two 

herbicides 80 feet from a treated area. Plants that are harvested by tribal communities will not be 

targets of herbicide applications, but they may be within a limited drift range of 80 feet. Prior to 

treatments being done, information on the timing and location of spraying will be provided upon 

request to individuals who want to avoid these areas. The Tonto NF will work with tribes to 

determine what type of notification each would like for projects involving the use of herbicides.

There is the possibility that a small percentage of the population in Arizona will be hypersensitive 

or allergic to one or more of the herbicides proposed for use. Symptoms exhibited by these 

individuals are caused by specific immunological reactions of the body that are triggered by 

exposure to very low doses of certain chemicals. Allergic or immunologic reactions result when 

the body’s normal immune system defenses overproduce antibodies to specific foreign 
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150 Environmental Assessment for Integrated Treatment of Noxious or Invasive Plants, Tonto NF

substances. Allergenic or hypersensitive reactions occur by different mechanisms than toxicity.

Toxic reactions result when chemical doses become high enough to interfere with normal 

physiological functions of cells and tissues. Individuals who have allergic reactions or 

hypersensitivity are generally aware of their sensitivities and such people would not be permitted 

to work on spray crews. In addition, signing of treatment sites and public notices would be done 

to allow concerned members of the public to avoid any possibility of exposure from the proposed 

herbicide applications.

In summary, the risk or probability of harm to humans from the proposed herbicides applications 

is not completely zero, but it is reasonable to expect that the human health impacts would be 

insignificantly small.

Comparison with Herbicide Projects from the 1960s

In reference to herbicide aerial spray projects that were conducted on the Tonto NF in the mid to 

late 1960s (discussed earlier in this section, “Short History of Herbicide Use on the Tonto NF”), 

several very important things have changed. First of all, the Environmental Protection Agency 

came into being in 1970. The EPA regulates pesticides under authority of the Federal Insecticide, 

Fungicide and Rodenticide Act (FIFRA). FIFRA was amended in 1972, with significant changes 

in how pesticides were to be regulated in the U.S. The 1972 amendment called for registration of 

all pesticide products used in the U.S., regular inspections of manufacturing establishments, the 

ability of the EPA to stop sales of hazardous pesticides, to conduct research on pesticides and 

monitor pesticide use and presence in the environment, and provided for certification of 

applicators and cooperative enforcement with the states. The EPA has banned two of the 

chemicals that were used in these spray projects – 2,4,5-T and Silvex. 2,4-D was also used in the 

1965 to 1969 Pinal Mountain projects, and is one of the most common herbicides used in the U.S. 

today. It is not proposed for use in this project. 

The National Environmental Policy Act of 1969 (NEPA) created a requirement that all federal 

actions were to be evaluated in a process open to public review (see definition of NEPA in 

appendix B). Under NEPA, federal land management agencies must now conduct activities by

formally analyzing the human and environmental consequences, asking the public for comments, 

and notifying the public of decisions.

Cumulative Effects

Over the nearly three million acres of the Tonto NF, a maximum of 9,000 acres (less than a third

of one percent) will be treated with herbicide in any one year. Amount of herbicide that will be 

applied, in comparison with amounts applied in surrounding communities, by homeowners, local 

parks and private lands such as golf courses, is miniscule.

In the greater Phoenix area alone there are nearly 200 golf courses (Golf Publisher Syndications,

2005). In communities around the Globe RD, there are 15. There are four golf courses in Payson.

One study, summarizing a survey of 77 golf courses in 2004, estimated that a total of 

approximately $4.7 million was spent for pesticides ($2.1 million of this was for herbicides) for 

the year 2004 (Schmitz, 2005). Another survey that requested more detailed information about 

types of herbicides used by golf courses in Arizona, was conducted in 1995 by the University of 

Arizona. Forty-seven golf courses responded to this questionnaire. Results showed these 

47 courses used 9,425 pounds (active ingredient) of pre-emergent herbicides, and 3,598 pounds 
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EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 151

(active ingredient) of post-emergent herbicides, for a total of 13,023 pounds active ingredient 

annually (Merrigan, 1996). The most common herbicides used were glyphosate and 2,4-D 

products. Extrapolating these typical application amounts to the 219 golf courses in the 

approximate watershed area of the Tonto NF, 60,127 pounds of herbicide active ingredients 

would be applied in one year.

In 2000, there were 20,140 households in Gila County (Fedstats, 2005). In the 2000 Census, there 

were 1,048,526 households in large cities in the Phoenix metro area (Phoenix, Mesa, Apache 

Junction, Scottsdale, Tempe, and Gilbert). The EPA Annual Report of Pesticide Usage for 2001 

(Kiely, 2004) documents that each household in the U.S. used approximately 1.7 pounds of 

herbicides (active ingredient) that year. Assuming each household only applied the average for 

home and garden use (which is probably an underestimate, since many homes are in rural 

settings), a total of 34,238 pounds of herbicide active ingredient were applied in Gila County in 

2001; 1,782,494 pounds were applied in the Phoenix metro area. Not counting any public 

facilities or agricultural herbicide use, at least 1,876,859 pounds of herbicide active ingredient 

were applied in the area of watersheds of the Tonto NF in 2001. This does not include off-forest 

uses in adjacent communities in Pinal, Yavapai and Maricopa counties. By contrast, if the 

Tonto NF applied herbicides to the maximum acreage of 9,000 acres, the amount of active 

ingredient would range from 4,500 to 18,000 pounds, depending upon herbicide used. It is 

unlikely that 18,000 pounds of active ingredient of herbicides or more would be purchased in any 

one-year period due to practical considerations such as budget constraints.

With respect to safety of fire fighters, and toxicity of smoke to employees and the public from 

prescribed and wildfires in sites where herbicides have been applied, there have been several 

articles written recently. Studies conducted of the composition of smoke resulting from both wild 

and prescribed fires in areas that have been treated with a variety of pesticides indicate that, even 

under conditions of smoldering fires, no significant human health risks occur for pesticides 

incorporated into or on forest fuels. In fact, studies have found that naturally occurring chemical 

by-products of combustion are a far greater risk to human health (Bush, et al., 2000).

Alternative 1: No Action (continue ongoing treatments)

Direct and Indirect Effects

Currently human health on the forest is not influenced by either the spread of invasive plant 

species or efforts to control them. Minor skin irritation or allergic reactions may result from 

contact with thorny species. Though some people may be allergic to the pollen produced by 

invasive plants, it is unlikely that invasive plants have been the primary source of seasonal or 

long-term allergies.

Under this alternative, herbicides may still be used in small amounts in campgrounds, 

administrative sites, and Forest Service facilities, as determined in previous decisions. This use 

would be very limited, and sites scheduled for herbicide application would be posted five days 

prior; therefore, there would be minimal exposure to chemically-sensitive people. Prescribed fire 

would be conducted only for very small areas of less than ten acres; smoke production and its 

associated health effects under this alternative would be minimal.

The primary effect of the no action alternative will be the continued spread of invasive plants 

within the forest. This is expected to have little direct effect on human health and safety. In terms 

of indirect effects, an increase in the potential for wildfires can be predicted as buffelgrass, 
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152 Environmental Assessment for Integrated Treatment of Noxious or Invasive Plants, Tonto NF

fountain grass and cool-season annual forbs and grasses continue to spread onto the forest and 

surrounding lands. A more frequent fire occurrence would result in indirect human health effects 

in the form of smoke in the inhabited areas within and around the forest, including the Phoenix 

metropolitan area.

Cumulative Effects

This alternative would probably add very little impact to human health to any other actions that 

are ongoing or likely to occur in the near future.

Alternative 2: Integrated Vegetation Management Except for the use of Herbicides

Direct and Indirect Effects

Impacts to human health and safety from mechanical and cultural treatments are likely to be 

minor. Possible effects include cuts, burns, allergies, and skin irritation to individuals performing 

the work. Skin irritations may result from contact with the sap or spines on the plants. Due to the 

uneven terrain in the vicinity of many of the treatment sites, minor injuries or falls may result.

The use of personal protective equipment such as gloves, long sleeves, and boots should 

minimize this risk. The effects of smoke described under alternative 1 would likely occur under 

this alternative, except that larger prescribed burns would produce more smoke. Effects of this 

would be mitigated by following prescriptions in the burn plan written for each prescribed burn.

Effects to chemically-sensitive people and people gathering vegetation products from the forest

would be basically the same as for alternative 1, except for the increase in acres of prescribed 

burns over that in the proposed action. A larger acreage (5,000 acres versus 2,000 acres in the 

proposed action) would result in more smoke put into the air.

Cumulative Effects

Same as for alternative 1, except increased use of prescribed fire to treat weeds may compete with 

forest health projects for days the Forest Service is allowed to burn and still meet air quality 

standards.

Heritage Resources

Affected Environment

The area of potential effect for heritage resources under this proposed action would be those 

archaeological and historic properties or sites that would be located within areas to be treated to 

control or eliminate noxious weeds.

There are approximately 9,000 recorded heritage sites on the Tonto NF, representing human 

occupation and use of the forest over a period of about 12,000 years. Hundreds more are being 

recorded every year, but it is estimated that these sites represent no more than ten percent of the 

total number present. 

The range of site types on the Tonto NF is extensive and includes everything from surface artifact 

scatters representing temporary activities and sites with buried architectural features to ruined 

surface structures of adobe and stone masonry and standing historic structures. Inventory efforts 
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EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 153

over the last several years have identified weed infestations on or near several of them. 

Inevitably, more will be identified as inventory efforts expand.

The forest also contains a number of heritage sites and places that reflect traditional use by 

neighboring Tribes, particularly the Tonto, White Mountain, and San Carlos Apache Tribes and 

the Fort McDowell Yavapai Nation, and others with historic affiliation to the forest, such as the 

Yavapai-Apache Nation. As with the archaeological and historic sites, only a small percentage of 

these places are recorded and many of the locations are confidential. The Tribes have also 

identified a number of native plants available on the forest that are still used for food, medicine, 

and religious purposes, including Emory oak, piñyon, several agave species, various yuccas, 

sotol, yerba santa, and others. No specific places used for such plant collection were identified 

during scoping for this proposal, but efforts are ongoing to identify these sites through 

consultation with the affiliated tribes and through ethnohistoric research being conducted in 

partnership with the Tribes. Properties or sites having traditional cultural or religious significance 

to Tribes are considered heritage resources by the Forest Service and are accorded the same 

protections under the National Historic Preservation Act (NHPA) as archaeological or historic 

sites.

Environmental Consequences

Native American Plant Gathering Traditions

Proposed Action: Integrated Vegetation Management

Direct and Indirect Effects

Traditional tribal use of native plant species for medicinal and economic purposes is not generally 

considered public information by the practitioners, particularly when such plants and the 

locations where they may be collected or used are involved in sacred practices or ceremonies. 

Some information regarding these practices has been entrusted to the Forest Service only with the 

understanding that it is not disclosed to the public. As a result, such uses and the species involved 

are not discussed extensively here. That being said, in general, the removal of invasive species 

and the restoration of native plant communities will have a beneficial effect for Native American 

plant gathering activities, since traditional uses are, almost by definition, based on native species. 

However, traditional plant gathering sites may have a potential risk of impacts from herbicidal 

and fire-based treatments, if for no other reason than the relatively large scale of operations that 

could be undertaken under the proposed action. Conflicts with traditional practitioners and 

concerns for their safety in and around treatment areas may become important, though plant 

harvesting typically takes place during different seasons than those when herbicidal treatment is 

most effective, so such conflicts will be minimal. However, as more roads are targeted as vectors 

for the spread of invasives and may be closed seasonally or permanently, the potential for conflict 

in the form of denying access could develop.

The potential for impacts to traditional plant resource species from herbicidal treatments depends 

largely on the specificity of the chemical agents being used and the method(s) of application. 

Application of non-specific defoliants or herbicides, for example, may indiscriminately kill 

traditional economic species, but this will be minimized as more information is acquired about 

traditionally important species, allowing treatment planning to be adjusted so as to protect them. 

The potential for effects on the traditional practitioners themselves will depend on the toxicity of 

the chemicals to humans, but, given the chemical agents proposed for use and the mitigation 

measures required for their application, as discussed above, the risks are insignificantly small.
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154 Environmental Assessment for Integrated Treatment of Noxious or Invasive Plants, Tonto NF

Most herbicides proposed for use are in the least toxic category rated by the EPA – “Relatively 

non-toxic.” Some sites will be treated by broadcast sprays from ground vehicles; others will 

receive spot treatments from backpack spray units. In areas of known importance for traditional 

plant gathering, spot treatments could avoid certain plants and target others. Prescribed burns can 

also destroy traditionally used species depending on how they are designed and conducted. 

Properly done, however, prescribed fire can be used to both eradicate weeds and enhance the 

health and recruitment of traditionally important species, several of which are known to return in 

greater abundance after a fire.

While the viability of other medicinal and economic species may or may not be enhanced by fire, 

the reduction of competition with non-native species that can be achieved through the use of fire, 

manual removal, and biological, cultural and mechanical methods will increase the availability of 

species important to the Tribes in those areas where invasion by noxious weeds has taken hold.

Cumulative Effects

Cumulative effect on Native American traditional gathering activities is directly related to historic 

changes in the numbers and distribution of economically or religiously significant plant species. 

While specific changes to gathering sites over the last century or so since the indigenous 

occupants of the forest were relocated to reservations are not currently known, largely because 

such areas have never been fully inventoried or documented, it can be assumed that a variety of 

management activities and land uses have contributed to such change. Logging, grazing, mining, 

reclamation, land exchanges, homesteading, and construction of roads and trails all may have 

contributed to changes in the type, distribution, and access to traditional vegetation resources on 

the forest. Until additional information becomes available, it must be assumed that there has been 

some level of cumulative effect to traditional gathering areas.

The primary potential impact to traditional gathering areas resulting from the treatment of weed 

infestations would be the inadvertent loss of native species that might result from the use of 

prescribed burning or the application of non-specific herbicides. The effects would necessarily 

add to the cumulative effect of all previous use and management of forest vegetative resources. 

Once a stand of traditionally-valued native species is lost, the value of a gathering site is lost. 

Cumulative effects to these resources can thus be seen in terms of both deterioration of individual 

sites by reducing the number and diversity of plants located there and loss of actual numbers of 

sites. However, as long as appropriate safeguards are taken to identify and avoid these potential 

effects, the Proposed Action should not add to the cumulative effect on this resource in any way.

Alternative 1: No Action (continue ongoing treatments)

Direct and Indirect Effects

Because the forest is still in the process of acquiring information, it is not yet known if the 

numbers or distribution of traditional plant gathering sites have been affected by weed 

infestations, but if such infestations are allowed to continue to grow, some displacement and 

replacement, especially of medicinal herb species, will be inevitable, thereby affecting the Tribes’ 

ability to conduct traditional economic or religious activities on the forest. Also, as with the 

proposed action, traditional plant-gathering places can be significantly impacted by both 

herbicidal and fire-based treatment, depending on the specificity of the chemical agents being 

used and the method(s) of application. However, no known or suspected traditional gathering 

sites are located within the few areas identified under this alternative as acceptable for the 
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EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 155

application of herbicidal controls. Otherwise, the direct and indirect effects under this alternative 

are similar to those under the proposed action.

Cumulative Effects

As traditional gathering areas become infested, the potential for deterioration or loss without 

treatment grows over time. The obvious cumulative effect in this case would be to add to the 

historic loss of such areas and restrictions on the ability of Tribal practitioners to continue the use 

of traditional resources. Likewise, fire-based and herbicidal treatments have the potential to 

reduce the number and quality of such areas, but given the restricted use to which either treatment 

would be used under this alternative, the cumulative effect would be negligible.

Alternative 2: Integrated Vegetation Management Excluding Herbicides

Direct and Indirect Effects

Since the only significant difference between this alternative and the proposed action is the 

elimination of herbicidal treatments not already authorized and identified in alternative 1, the 

potential for impacts to traditional uses is reduced accordingly, but since these potential impacts 

are minimal, the effect is not significantly different from that for the proposed action.

Cumulative Effects

Cumulative effects under this alternative would be similar to those under the Proposed Action and 

alternative 1.

Archeological Resources

Affected Environment

Archaeological and historic sites are irreplaceable and individually unique. Their integrity is 

wholly dependent on the contextual relationship between artifacts, architecture, and the 

environment in which they are found. Once this context is disturbed, it cannot be recreated or 

restored. Prehistoric and historic archaeological sites are also, by their very nature, the result of a 

history of effects, the transformation processes of erosion, decay, and other disturbances that have 

reduced them from their original pristine state. Any effect to heritage resources, therefore, is 

cumulative; they cannot grow back and their populations cannot rebound. The effects of 

continued, untreated weed infestation in this context can be relatively minor. The most common 

direct effect is from root growth; it can be argued that invasive species have a potential to disrupt 

and destroy buried cultural deposits through root action. Obviously, native vegetation can also 

result in disturbance of this nature. On the face of it, then, this would seem minor and no different 

from the effects of native vegetative cover, but some of the invasive species of concern tend to 

have deep taproots and thus a greater potential for disruption than many shallow-rooted native 

species. The degree to which a weed infestation creates a significantly greater impact is therefore 

relative, depending on the density and nature of the vegetation and the characteristics of its root 

growth patterns. Often, the primary effect of weed infestation itself is indirect; changing the 

environmental context of prehistoric and historic site by replacing native species with invasives 

can indirectly affect their eligibility for nomination to the National Register of Historic Places by 

lowering their historic integrity. In many cases, the direct effect is negligible and short term 

because weed infestations can come and go and native species can recover or be reintroduced.
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156 Environmental Assessment for Integrated Treatment of Noxious or Invasive Plants, Tonto NF

The same cannot always be said regarding the significant Tribal places used for traditional Native 

American plant-gathering activities. As weed infestations grow and crowd out native species, the 

opportunities to practice traditional gathering will become fewer and fewer until some or all have 

been lost. Because the forest is still in the process of acquiring information, it is not yet known if 

the numbers or distribution of traditional plant gathering sites have been affected by weed 

infestations, but if such infestations are allowed to continue unchecked, some displacement and 

replacement, especially of medicinal herb species, will be inevitable, thereby affecting the Tribes’ 

ability to conduct traditional religious of economic activities on the forest. Nevertheless, 

determining the effect on traditional plant collection sites is situational and depends on the history 

of plant species composition and viability at each location. It is known, however, that some 

traditional gathering sites are associated with forest system roads, many of which pass through 

significant stands of economically or religiously significant species that are collected directly 

along the roadside. Based on the types of treatment proposed, conflicts may arise where such 

roads might be targeted for treatment.

Treatment of weed infestations can be equally situational and highly variable in effect. Some 

large-scale treatments covering many acres and multiple archaeological sites, such as prescribed 

burning, may have no effect at all. In other cases, even where the direct effect of a treatment is 

negligible and short term, such as in the case of hand pulling of small plants, repeated treatments 

may result in the complete disruption of a site’s surface and near-surface cultural deposits. 

Nevertheless, as long as reasonable care is taken in their application, the effects of such 

treatments are considered to be minor in regard to prehistoric and historic archaeological sites. 

For this reason, Region 3 has developed a specific Protocol with specific measures for the 

protection of heritage resources during treatments for noxious weeds. This Protocol has been 

adopted herein as appendix H.

Environmental Consequences

Proposed Action: Integrated Vegetation Management 

Direct and Indirect Effects

Based on thirty years observation of wildfires and prescribed burns, fire-based treatments such as 

those that would be allowed under this alternative cause no significant direct effects to 

archaeological or historic sites (Wood, 2005). The only exception would be those sites identified 

as “fire-sensitive,” particularly historic sites containing or constructed of combustible materials 

such as wood. Such sites are routinely identified and protected whenever prescribed fires are 

planned. Indirect effects may result in an increased risk of erosion from temporary loss of ground 

cover; they are typically limited to artifact displacement and minor damage to surface structures 

during short term erosional episodes resulting from the loss of ground cover. However, this is 

generally a problem only when large areas are denuded as a result of the treatment, which is

unlikely given the relatively limited extent of most infestations on the forest.

Mechanical or manual treatments, even the minor ones such as hand pulling and digging with 

hand tools allowed under the proposed action, probably have the highest potential to impact 

archaeological sites, especially when those sites consist of only surface artifact scatters and buried 

features. Mechanized treatments, especially those with heavy machinery, clearly have the 

potential to disturb the surface of such sites, displacing or damaging artifacts and architectural 

features, though the degree of impact depends on the type of machinery, type and density of 

vegetation, and soil conditions at the time of treatment. Even grubbing and digging up plants,
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EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 157

especially those with deep taproots, with hand tools has the same potential to impact sites. Hand 

pulling of individual plants also has the same potential for impacting sites by displacing surface 

artifacts and disturbing near-surface buried cultural deposits; but generally, depending on the 

plant species and the specific soil conditions on site, for a one-time application of this method, the 

level of impact is considered to be more or less equivalent to the damage done from root growth 

of the many weed species if left untreated.

Herbicide controls, even at the relatively large scale of operation that would be allowed under the 

proposed action, have not been shown historically to impact archaeological and historic sites. 

Indirect effects can result from such actions where defoliants are used to reduce large area 

populations of brush species. As with fire-based treatments, they are typically limited to artifact 

displacement and minor damage to surface structures during short-term erosional episodes 

resulting from the loss of ground cover. However, just as with fire-based treatments, this is 

generally a problem only when large areas are denuded as a result of the treatment, which is 

unlikely given the relatively limited extent of most infestations on the forest.

Biological controls such as live insects or plant pathogens are not expected to have any effect at 

all upon any heritage resources.

Cultural treatments pose a threat to Heritage sites only when they might significantly alter their 

visual or biological context, that is, the vegetative landscape with which they are associated. 

Given the small scale of such treatments as are proposed here and the fact that they will tend to 

repair damage done to that context by the presence of invasives by replacing them with native 

species, such treatments are not expected to have any effect on heritage resource sites.

Targeted grazing by sheep and goats, a combination of biological and mechanical control 

methods, can have little or no effect on heritage resources or it can be devastating to them, 

depending on the intensity and duration of the application. At low intensities, there is little to 

recognize of their passing, but at high intensities these animals can strip areas bare of all 

vegetation, including desired native species, initiate gully erosion from repetitive hoof action, 

displace surface artifacts, disrupt architectural features, and even completely obscure sites under a 

dense mat of fibrous organic waste.

Cumulative Effects

Given that all prehistoric and historic archaeological sites represent a history of cumulative 

effects, any additional effect to such sites necessarily contributes to their overall cumulative 

effect. Because of this sensitivity and the irreplaceability of this resource, archaeological, and 

historic sites are protected from surface disturbing activities by avoidance or mitigation, typically 

by excavation/data recovery. Data recovery results in the destruction of the physical presence of 

the resource; it remains only “on paper” as collected artifacts and recorded information. Every 

site excavated adds to the cumulative loss of this resource. The preferred means of protection, 

therefore, is avoidance since it protects sites from immediate direct impacts and does not add to 

the cumulative effect on the resource as a whole. Indirect effects, primarily in the form of erosion, 

may result even for sites that have been avoided by the primary activities of a project. 

Nevertheless, since most projects are designed with various protections against large-scale 

erosion, this is generally considered only a minor addition to the cumulative effect of all projects 

on heritage resources.
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158 Environmental Assessment for Integrated Treatment of Noxious or Invasive Plants, Tonto NF

The cumulative effects of continued weed infestation are considered to be minor compared to the 

full range of transformation processes that have affected these resources over the course of 

hundreds to thousands of years. Treatment of these infestations, unlike most other potentially 

disturbing activities that are designed to avoid heritage resources, may be called for within actual 

site boundaries.

Mechanical treatments within site boundaries, which would be limited to minimal impact 

procedures under this alternative, are not seen as having any more per-treatment impact than the 

effects of root growth if the weeds are left unchecked. Multiple treatments, however, have the 

potential to result in observable levels of surface disturbance and artifact displacement, but 

careful application of the procedures and employment of appropriate protection measures called 

for in the Heritage Resources Protocol would prevent even repeated treatments from contributing 

appreciably to the cumulative effect. 

Fire-based treatments are among the few that are ever authorized within site boundaries. The 

reason for this is that they have little if any direct effect on most heritage resources; the 

cumulative effect of repeated burning would be minimal at best. Where fire-sensitive sites are 

involved, as long as they are protected during treatment, there is no cumulative effect. If they are 

affected by a fire-based treatment, it is usually the last effect that fire could have; burning them 

again will not constitute further damage. Fire-based treatments do have the potential to alter 

vegetative contexts of sites and produce indirect effects such as erosion, but on the scale of 

treatment proposed under this alternative, even the cumulative effect would be negligible.

Herbicidal treatments have the potential for contributing indirect effects such as erosion only 

from very large-scale application. Given the limited extent of treatment under this alternative, the 

potential for contributing to the cumulative effect to heritage resources is negligible.

Alternative 1: No Action (continue ongoing treatments)

Direct and Indirect Effects

The same potential effects accrue to heritage resources under this alternative as under the 

proposed action. However, the much smaller scale of application for herbicide and prescribed 

burning treatments proposed under this alternative creates essentially no risk for post-treatment or 

indirect effects, such as increased erosion from large-scale removal of canopies and ground cover.

The fire-based treatments such as those that would be allowed under this alternative to control or 

eliminate weeds along SR 188, other system roads on the forest, and on the Pleasant Valley 

Administrative Site evidence no significant direct effects to archaeological or historic sites. The 

only exception would be those sites identified as “fire-sensitive,” particularly historic sites 

containing or constructed of combustible materials such as wood. The only known “firesensitive” sites within the specified treatment area under this alternative are the historic buildings 

that comprise a large part of the Pleasant Valley Administrative Site; these would be protected,

since they are still in use. Indirect effects are also limited to an increased risk of erosion from 

temporary loss of ground cover; again, this is a problem only when large areas are denuded as a 

result of the treatment, which is unlikely given the restrictions on fire use under this alternative.

Herbicide controls at such a limited scale as those that would continue to be allowed under this 

alternative along state highways and in the Pleasant Valley Administrative Site, have not been 

shown historically to impact archaeological and historic sites. Indirect effects from such 
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EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 159

treatments are unlikely, given the small areas defined as acceptable for this form of control under 

this alternative.

Mechanical treatments, even the low-impact manual techniques such as hand pulling and digging 

with hand tools allowed under this alternative, probably have the highest potential to impact 

archaeological sites, especially when those sites consist of only surface artifact scatters and buried 

features. While no mechanized treatments are authorized under this alternative, hand grubbing 

and digging up plants – especially those with deep taproots - with hand tools has the same 

potential to impact sites, though perhaps at a smaller scale. Hand pulling of individual plants also 

has the same potential for impacting sites by displacing surface artifacts and disturbing nearsurface buried cultural deposits but generally, depending on the plant species and the specific soil 

conditions on site, for a one time application of this method, the level of impact is considered to 

be more or less equivalent to the damage done from root growth of the many weed species if left 

untreated and is therefore not significant.

Cumulative Effects

Cumulative effects under this alternative would be similar to those under the Proposed Action.

Alternative 2: Integrated Vegetation Management Excluding Herbicides

Direct and Indirect Effects

Since the only significant difference between this alternative and the proposed action is the 

elimination of any herbicidal treatments not already authorized and identified in alternative 1, the 

potential for impacts to heritage resources is reduced accordingly. However, since archaeological 

and historic sites are not directly impacted in any way by the use of herbicidal treatments, the 

only potential reduction in effect levels lies in the area of indirect effects, as from increased 

erosion. Since those effects are already considered minimal under the proposed action, the overall 

potential for direct and indirect effects from this alternative is not significantly different from that 

for the proposed action.

Cumulative Effects

Cumulative effects under this alternative would be similar to those under the proposed action.

Developed and Dispersed Recreation Including Motorized 

Recreation

Affected Environment

Recreation on the Tonto NF began in the 1800s with the discovery of the Tonto Natural Bridge 

near Payson. Early visitors were using the lower Salt River as a popular recreation site in the 

1890s. By 1920, a full-scale resort hotel had been built on the Verde River at Verde Hot Springs.

As early as 1920, camping, hunting, and fishing activities were popular recreation activities on 

the Tonto NF due to the increased availability of motor vehicles and construction of better roads 

and new campgrounds.

Reclamation activities on the Salt and Verde Rivers brought new recreation opportunities as lakes 

were created behind newly constructed dams. Today, visitors to these areas can enjoy outdoor 
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160 Environmental Assessment for Integrated Treatment of Noxious or Invasive Plants, Tonto NF

recreation facilities and services such as resorts, marinas, hunting and fishing guides, river 

running, horseback riding, off-highway touring, and tube rentals and shuttle services.

There are over 26,000 acres of man-made lakes in the desert portion of the Tonto NF. Roosevelt, 

Apache, Canyon, and Saguaro lakes are on the Salt River. Bartlett and Horseshoe lakes are on the 

Verde River. Seeking refuge from the summer heat, visitors flock to these rivers and lakes, as 

well as the trout streams and cool shades of the tall pines in the Mogollon Rim Country. Each 

year more than 8 million people visit the Tonto NF.

There are over 87 developed recreation sites on the Tonto NF. Each is managed for a variety of 

recreational activities including overnight camping, picnicking, fishing, and boating. Commercial 

and some non-commercial activities in both developed and dispersed recreation areas require a 

special use permit. This includes non-commercial group (groups of 75 or more people) and 

organized recreation events.

Outfitter/guides are required to have a special use permit when operating on Forest System lands.

Along with the permit they are required to work with the forest officer to develop an Operating 

Plan that will guide their use of the lands. Highlighted in the Operating Plan are specific rules for 

operating in wilderness areas, basic field ethics, use of livestock, use of dogs, use of vehicles, 

overnight camping regulations, and campfire use. Operating Plans also inform the outfitter and 

guide of specific special orders pertaining to the areas they will be visiting.

Horseback riding is one of the most popular adventures enjoyed on the Tonto NF. Tonto NF trail 

crews maintain trails from wilderness areas to urban interface boundaries between the forest, 

counties, cities, and towns. During the summer months, outfitter/guides move to the tall pine 

country of the Mogollon Rim, which offers them year-round opportunities for horseback 

vacations and day ride services. 

Mountain biking can be enjoyed year-round on the Tonto NF. High country routes afford 

beautiful views and escape from summer heat. Desert routes provide scenic variety and are well 

used during the winter months. Cyclists are required to ride on designated routes only and are 

encouraged to practice the land ethics included in the Leave No Trace program. There are 

hundreds of miles of roads on the Tonto NF that are suitable for mountain biking. They range 

from fairly-smooth one-lane roads to wheel tracks no longer suited for motor vehicles. Many 

roads have been or are in the process of being closed to motorized vehicles in order to protect 

certain wildlife and vegetation habitats. In many cases, these roads are accessible to bikers.

There is an extensive system of trails in some parts of the forest; however, most are steep and 

rocky and may not be suitable for biking. Many trails are located within designated wilderness 

areas where vehicular access of any type is prohibited.

Lower Salt River Recreation Area

One unique recreation area on the Tonto NF is the Lower Salt River Recreation Area.

Phoenicians seeking a reprieve from the extreme summer heat flock to the cool waters of the 

Lower Salt River to enjoy a day of leisure.

The Lower Salt River is located approximately 16 miles east of Mesa, Arizona. It flows through 

the southern edge of the Tonto NF and the Salt River Indian Reservation near Fort McDowell. It 

is easily accessible as a day trip. A plethora of recreation activities can be enjoyed on this desert 
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EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 161

oasis consisting of 14 miles of navigable waters commencing at Stewart Mountain Dam and 

ending at Granite Reef Dam. It is rated a Class I to II River. The river meanders through a 

Sonoran Desert and riparian landscape and can be navigated year-round by paddling rafts, 

kayaks, or canoes. However, during the summer months thousands of people converge on the 

river to enjoy a day of fishing, floating the river on inner-tubes, and picnicking along the river 

and outer banks.

The season of day-use is typically from late April through late September. Overnight camping is 

allowed in designated recreation sites only from October through March. No motorized boats are 

allowed on the river.

Brome grasses, fountain grass, buffelgrass, saltcedar, and Malta starthistle are known to occur in 

the Lower Salt River Recreation Area.

Motorized Recreation

As the fifth largest forest in the United States and the second most visited forest, the Tonto NF

has heavy motorized usage. The Tonto NF is situated directly north and east of Phoenix, the sixth 

largest city in the United States with approximately 1.5 million people and growing rapidly. The 

Tonto NF hosts a large portion of these people every weekend. Motorized recreation uses include:

hunting, photography, camping, trail riding, scenic driving, wildlife viewing, accessing other 

recreational activities, and just getting away.

The Tonto NF has 3,476 miles of roads authorized for motorized recreation (Tonto NF, 2012). Of 

the Tonto NF’s six ranger districts, four (Cave Creek, Globe, Mesa, and Tonto Basin) limit 

motorized usage to National Forest System roads and trails; however, on the ground management 

has not been possible due to limited funding. The other two ranger districts (Payson and Pleasant 

Valley) allow cross country travel. User-created routes, while not inventoried, account for several 

hundred miles of additional routes. This unmanaged motorized usage has also resulted in large 

areas of intensive use where vegetation is very limited or destroyed. The recent Forest 

Servicewide Travel Management Rule will require all forests to designate roads, trails, and areas 

for motorized usage. The implementation of this Rule will reduce adverse impacts of motorized 

recreation. The Tonto NF is in the process of analyzing a range of travel management plans. This 

analysis is being documented and will be available for public comment.

In addition the Tonto NF has many special use permits that include motorized access and usage 

such as outfitter/guides, “jeep tours,” and off-highway vehicle skill events. These uses are limited 

to system roads and trails. Recreational groups, such as off-highway vehicle clubs/organizations

consisting of groups larger than 75 people, are also required to obtain a permit for activities.

Non-motorized Recreation

The Tonto NF is one of the most-visited forests in the United States, receiving approximately 

5.8 million visitors annually. Elevations on the forest vary from 1,300 feet to nearly 8,000 feet 

and offer year-round recreation opportunities. Most recreationists that visit the non-motorized 

areas of the Tonto NF are residents and visitors of the Phoenix metropolitan area.

Non-motorized recreation areas on the Tonto NF include both Congressionally-mandated 

wilderness and non-wilderness dispersed and developed recreation areas.
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162 Environmental Assessment for Integrated Treatment of Noxious or Invasive Plants, Tonto NF

Non-motorized recreation activities in these areas include photographing, hiking, hunting, fishing, 

camping, wildlife viewing, horseback riding, rafting, kayaking, and canoeing.

The Tonto NF is responsible for the management of seven congressionally designated wilderness 

areas totaling over 589,000 acres. An eighth wilderness that lies on both the Tonto and Prescott

national forests is managed by the Prescott National Forest. In addition, portions of the Verde 

River have been designated by Congress as Arizona’s first and only Wild and Scenic River Area.

These wilderness areas are managed to ensure public enjoyment, while protecting the unique 

natural character of these special places. The primary means of transportation in these 

Congressionally-mandated wilderness areas is by horse, raft, canoe, or foot.

There are 52 trailheads that allow access to 900 miles of National Forest System trails on the 

Tonto NF. Of the 900 miles of trail 618.25 are in wilderness and 281.75 are in non-wilderness 

areas. Many of these trails are used year-round by recreationists seeking a quiet retreat. Dogs are 

allowed in all parts of the Tonto NF; owners are required to adhere to federal, state, and county 

laws and regulations regarding pets in the areas visited.

Environmental Consequences

Proposed Action and Alternatives

The proposed action and alternatives may result in short term closures of roads, trails, or areas to 

treat invasive weeds and prevent spread of those weeds. As the Travel Management Rule is 

implemented and routes and areas are selected to be added to the authorized transportation 

system, they will need to be monitored for invasive weeds.

The proposed action and alternatives could potentially have a short-term effect on non-motorized 

recreation use on the Tonto NF in that recreational use of treated areas could be limited during 

treatments.

Appendix C, Guide to Noxious Weed Prevention Practices, includes measures that will prevent 

introduction and spread of noxious weeds by recreational activities permitted on the forest.

Specially Designated Areas

Affected Environment

Verde Wild and Scenic River

The Verde Wild and Scenic River is a unique and important resource in Arizona. Many people 

visit the Verde for its outstanding recreational opportunities including boating, hunting, fishing, 

birding, hiking, picnicking, and photography.

The Verde River is perennial throughout both the Scenic and Wild River Areas, though flow 

varies considerably during the year. Flows are affected by changes in precipitation, upstream 

diversions, ground-water pumping, and evaporation.

Two Bureau of Reclamation storage reservoirs are located near the Verde River’s terminus on the 

Tonto NF (Horseshoe and Bartlett reservoirs). Water is stored in these reservoirs before being 

discharged into the Salt River for use by downstream municipal, agricultural, and industrial 

entities.
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EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 163

The Verde Wild and Scenic River encompasses 35.7 miles of classified Wild River and 

29.5 miles of classified Scenic River for a total of 65.2 miles of Wild and Scenic River. This area 

encompasses 5,692 acres. Of this 683 acres of the Scenic River are on the Tonto NF. The Wild 

portion encompasses 6,824 acres of which 6,346 are on the Tonto NF.

Virtually the entire Wild River Area is within the Mazatzal Wilderness, which is the largest 

wilderness area (over 250,000 acres) in the Southwest.

The following restrictions apply within this wilderness (including the Verde Wild River Area):

1. The length of stay is no longer than 14 days,

2. group size is limited to 15 persons; and

3. no more than 15 head of livestock are allowed per group.

A maximum number of outfitter/guide permits available and a maximum number of customerdays have also been established in the Tonto Land and Resource Management Plan.

The Verde River can be floated year-round; however, its primary river-running season is during 

March and April. Because the amount of run-off is so unpredictable, a minimum optimal flow 

may provide a primary river-running season of 0 to 30 days. Currently no permit is required for 

private parties to run this river.

The Verde River has not been completely surveyed for presence of invasive plants, but the 

following plants on the Tonto NF noxious weed list are known to occur within the Tonto NF’s 

Wild and Scenic River segments: Dalmatian toadflax, yellow sweetclover, tree of heaven, 

saltcedar, giant reed, Russian thistle, annual brome grasses, wild oats, and fountain grass.

A Comprehensive Management Plan for the Verde Wild and Scenic River was completed by the 

Tonto, Prescott, and Coconino NFs, and a decision signed to implement it in June 2004 (U.S.F.S.,

June 2004).

The Verde Wild and Scenic River Comprehensive River Management Plan Environmental 

Assessment states that “invasive plants would be selectively controlled, focusing on species such 

as saltcedar, which have the greatest impact on native species in both the Wild and Scenic 

sections” (U.S.F.S., June 2004). The Verde Wild and Scenic River Comprehensive River 

Management Plan further states that district rangers are responsible for inventory and mapping of 

invasive vegetation species along the river. It also states that an integrated pest management plan 

that identifies direction and priorities for inventory, management, and monitoring of invasive 

plant species will be initiated in 2006. The Coconino National Forest has begun a control program 

for Arundo and saltcedar on the Upper Verde River (mostly the Scenic reach).

Fossil Creek Wild and Scenic River

Fossil Creek is Arizona’s second and newest designated Wild and Scenic River; of its nearly 

18 mile length from its mouth at the Verde upstream to the confluence of Calf Pen and Sand Rock 

Canyons, 9.3 miles are designated “Wild” and 7.5 miles are designated “Recreational”. From the 

early 1900s until 1999, power was generated by the constant 43 cfs flow of Fossil Springs and a 

system of flumes, a lake and a surge tank. Arizona Public Service shut down the power plants at 

Irving and Childs in 1999; in 2005 the hydropower plants were decommissioned and flow 

restored to the creek (USFWS, 2011b). Fossil Creek was designated Wild and Scenic by 

legislation in 2009 (U.S. Congress, 2009). Fossil Creek forms a portion of the boundary between 
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164 Environmental Assessment for Integrated Treatment of Noxious or Invasive Plants, Tonto NF

the Tonto and Coconino NFs. A coordinated resource management plan is scheduled for 

completion in 2012 (Red Rock Country, 2011).

Arundo has been identified growing in the creek. The Coconino has controlled this invasive reed 

on their side of the creek. There are clumps of Arundo on the Tonto NF side that have not been 

controlled. 

Wilderness

All wilderness areas on the Tonto NF have management plans. Each management plan addresses 

“non-indigenous” plants, a category of plant that includes invasive weeds. All of the Tonto NF’s 

list of invasive plants are nonnative, but not all non-indigenous plants are invasive; thus the 

wilderness plans are describing a much broader category of plants.

Every wilderness management plan states that non-indigenous species can alter natural ecological 

process. Implementation actions to address nonindigenous plants are the same for all plans:

• Nonindigenous plant species not established at the time of the area’s designation as 

wilderness shall not be brought into or introduced into the wilderness.

• Ongoing programs outside the wilderness may continue, so long as there is no invasion of 

nonindigenous plants into wilderness.

• Nonindigenous species now established in the wilderness will be extirpated as the 

opportunity presents itself. Removal methods will be compatible with the wilderness 

resource.

Upper Salt River Canyon Wilderness

A recent survey for invasive plants on the Upper Salt River documented only one kochia plant, 

which was actually on the Fort Apache Reservation, and a few tree of heaven saplings near the 

mouth of Pinal Creek. Saltcedar is a fairly common invasive plant along the entire Salt River

(Fenner, 2005a).

According to the Implementation Plan for the Upper Salt River (dated October 31, 1985) 

management of recreation use on the river, will emphasize those uses which least impact the 

environment.

Four Peaks Wilderness

No weed surveys have been conducted in this wilderness area.

Hellsgate Wilderness

No weed surveys have been conducted in this wilderness area.

Mazatzal Wilderness

No weed surveys have been conducted in this wilderness area.

Pine Mountain Wilderness

No weed surveys have been conducted in this wilderness area.
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EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 165

Salome Wilderness

A management plan for this wilderness was approved by the forest supervisor in 1993.

No weed surveys have been conducted in this wilderness area.

Sierra Ancha Wilderness

A management plan for this wilderness was approved by the forest supervisor in 1993.

No weed surveys have been conducted in this wilderness area. An early management plan for the 

Sierra Ancha Wilderness, written in the early 1970s includes a plant species list. Plants on the 

Tonto NF noxious weed list found at that time are: Russian thistle, field bindweed, black mustard, 

wild oats, Japanese brome, red brome, cheatgrass, and yellow sweetclover. Puncturevine, a weed 

on the state noxious weed list, was also found.

Superstition Wilderness

A management plan for this wilderness was approved by the forest supervisor in 1992.

No weed surveys have been conducted in most of this wilderness area. Fountain grass is invading 

the National Forest from the area of Lost Dutchman’s State Park. As of 2008, this infestation was 

moving up a drainage and was very near the wilderness boundary.

A 1972 Wilderness Management Plan included a list of plant species. Plants on the current Tonto 

NF noxious weed list, that were found in the Superstition Wilderness at that time include: red 

brome, cheatgrass, weeping and Lehmann’s lovegrass, yellow sweetclover, saltcedar, 

Mediterranean grass, and Russian thistle. Puncturevine, a forb on the Arizona state noxious weed 

list was also found.

Sierra Ancha Experimental Forest

The Sierra Ancha Experimental Forest is a field facility of the Rocky Mountain Forest and Range 

Experiment Station. The Station Director in Fort Collins, Colorado, is responsible for all research 

on the Experimental Forest. This 12,820-acre area was designated in its present conformation in 

1938, and has been used for various forest-related research studies, including watershed, 

chaparral, and range management, soils, plant physiology, and animal and plant ecology studies 

(Tonto NF 1932 & 1938). It is now managed under a Memorandum of Understanding with the 

Arizona Board of Regents to share responsibility for the facility with Arizona State University 

(Tonto NF, 1983). Any undertaking regarding treatment of invasive plants would need to be 

coordinated with both Arizona State University and Rocky Mountain (Gottfried, 2005).

Three Bar Wildlife Area and Experimental Watersheds

The Three Bar Wildlife Area, on the east side of the Mazatzals, west of Tonto Basin, was created, 

and excluded from domestic grazing in 1947. The Three Bar Experimental Watersheds (there are 

four of them, each less than 100 acres), within the Wildlife Area, were established and 

instrumented in 1956 by the Rocky Mountain Forest and Range Experiment Station, in order to 

study the ecology and hydrology of the chaparral vegetation type. Their research mission was to 

determine effects of chaparral conversion to grassland on water yield, erosion, and game 

populations. Hydrologic evaluations on the Three-Bar watersheds were discontinued in 1983. The 
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166 Environmental Assessment for Integrated Treatment of Noxious or Invasive Plants, Tonto NF

Three-Bar Wildlife Area remains ungrazed and provides a study site for wildlife studies and for 

monitoring by the Arizona Game and Fish Department (RMFRES, n.d.).

Research Natural Areas

In the 1970s and 80s, the forest selected certain areas for designation as Research Natural Areas 

(RNAs) to contribute to a series that “illustrates or typifies for research or educational purposes 

the important forest and range types in each forest region, as well as other plant communities that 

have special or unique characteristics of scientific interest and importance” (36 CFR 251.23) A 

November 4, 2005, FSM amendment gives “Protection and Management Standards” for these 

areas. FSM 4063.3 (1) states that maintenance of natural ecological processes and conditions are 

the prime consideration in managing RNAs. “To the extent practical, protect RNAs against 

human activities that directly or indirectly modify the integrity of the ecological processes.” More 

specifically, with regard to exotic plants and animal life, “Remove exotic plants or animals to the 

extent practicable. Where pest management activities are prescribed, they shall be as specific as 

possible against target organisms and induce minimal impact to other components of the 

ecosystem. The release of biological control organisms for exotic species control should be 

carefully considered to avoid the introduction of other exotic species” (FSM 4063.3(4).

Buckhorn Mountain RNA was designated in 1988 to provide an example of Arizona chaparral 

for the series of forest and range types in the RNA system. It is 2,810 acres west of Roosevelt 

Lake, near the top of the watershed divide and above the Three Bar Wildlife Area. The area has 

been closed to grazing since 1946, and rough terrain precludes motorized use or fuelwood 

harvest. Two thirds of the area is within the Four Peaks Wilderness (Tonto NF, 1988).

Bush Highway RNA is 488 acres approximately one mile east of the Bush Highway and one 

mile south of the Beeline Highway. It was designated in 1973 by the Chief of the Forest Service 

to represent typical palo verde-cactus shrub vegetation type. It is located within the Sunflower 

Grazing Allotment, which has been grazed by livestock since the 1870s. Although it has not been 

grazed in recent years due to drought, it is not closed to grazing. 

Haufer Wash was selected as an example of relatively undisturbed semi-desert grassland and 

desert scrub vegetation. This 680-acre RNA is located within the fenced Three Bar Wildlife Area, 

and has been excluded from grazing by domestic livestock since the early 1930s. The Decision 

Notice that created this RNA was signed by the Chief on November 17, 1993. A plant survey 

conducted for purposes of environmental assessment in the spring of 1985 identified Malta 

starthistle as being present.

Blue Point Botanical Area is 475 acres located 2 miles upstream of the Salt/Verde River 

confluence, mainly in the Salt River floodplain. The river terrace is occupied by a mesquite 

bosque. Cottonwood, saltcedar, cattail, and arrowweed occupy the floodplain. A 

bursage/saguaro/palo verde community grows in the northern portion of the Botanical Area. The 

grazing allotment that surrounds this area discontinued grazing in 1978, and has now been 

formally closed to grazing. Prior to 1978, it had been heavily grazed by cattle, since the late 19th

century (Tonto NF, 1979). Management objectives are to manage an area where natural processes 

are dominant, enhance rare and endangered species of plants and animals, maintain a high quality 

botanical area, and provide for scientific and educational studies of plants, animals, and 

ecological relationships. Seasonal grazing may be used as a tool to achieve the area’s objectives

(Tonto NF, 1979).
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EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 167

Inventoried Roadless Areas

The Tonto NF has identified six percent of the forest as Inventoried Roadless Areas, 

approximately 170,000 acres. These areas are managed to protect roadless values and 

characteristics and may be considered for recommendation for permanent wilderness designation.

These unique areas provide both motorized and non-motorized recreational opportunities. Since 

these areas may be considered for permanent wilderness designation, the roadless characteristics 

must be maintained along with other possible wilderness characteristics. Proposed road work 

(maintenance, construction, etc.), timber harvesting, or roads associated with minerals is under 

the authority of either the regional forester and/or the Forest Service Chief.

Environmental Consequences

Proposed Action: Integrated Vegetation Management

Direct and Indirect Effects

All wilderness management plans state that control of “non-indigenous” plants will be done using 

methods compatible with the wilderness resource. Prescribed fire is not allowed in wilderness 

areas. Use of herbicides in wilderness areas must be approved by the regional forester. No large 

infestations are known at this time, so control actions are expected to be very limited manual 

methods or spot herbicide applications.

Cumulative Effects

Other activities on the forest are bound to eventually bring in invasive plants. Under the proposed 

action, infestations will be detected and controlled early enough such that extensive treatments 

would not be necessary. Prevention and education are key components of Integrated Vegetation 

Management that are especially appropriate to wilderness areas. Implementation of a weed-free 

hay order would help to prevent new infestations from this vector. 

Alternative 1: No Action (continue ongoing treatments)

Direct and Indirect Effects

The forest will monitor wilderness areas for invasive plants, as funding allows. Any weeds would 

have to be treated by hand. If these weeds are perennial plants, manual control may not be very 

successful, and infestations would grow.

Cumulative Effects

Same as for the proposed action, except manual treatments alone may not be adequate to control 

some invasive species.

Alternative 2: Integrated Vegetation Management, Excluding Use of Herbicides

Direct and Indirect Effects

Effects would be the same as for alternative 1.
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168 Environmental Assessment for Integrated Treatment of Noxious or Invasive Plants, Tonto NF

Wild and Scenic River (and also the Salt River, Evaluated for Designation 

as Wild/Scenic)

Proposed Action: Integrated Vegetation Management

Direct and Indirect Effects

Saltcedar is the main invasive plant growing along both the Salt and Verde rivers. Use of the cutstump herbicide method of control will leave evidence of treatment for up to 3 years following 

treatment.

On the Verde River, removal of saltcedar, which grows as occasional sapling trees within a 

healthy cottonwood/willow riparian community, will not affect visual quality. In fact, control of 

saltcedar on the Verde River will not be evident to the casual river runner.

Most of the Upper Salt River does not have floodplain habitat adequate for development of native 

riparian trees such as cottonwood and willow. High concentrations of salt in this river may also 

be a factor that precludes native riparian trees such as cottonwood and willow from establishing.

Removal of saltcedar would have little positive effect here for releasing habitat for native 

vegetation. Native vegetation along the Salt River is less dense than saltcedar, and also does not 

extend as far from the water’s edge away from the river. Most benefit would be realized from 

making campsites more accessible to boaters. 

Cumulative Effects

Control of saltcedar on either river would need to be coordinated with upstream land managers, in 

order to be successful. 

Removal of saltcedar from both the Upper Salt and Verde rivers will result in a lowered risk of 

wildfire in the riparian area. Southwestern willow flycatchers that nest at the inlet to Horseshoe 

Lake on the Verde River have nested mainly in both saltcedar and in native willows. Removal of 

saltcedar in that area will lessen risk of wildfire in this endangered bird’s nesting habitat.

Removal of saltcedar at the mouths of Tonto Creek and the Salt River into Roosevelt Lake is not 

feasible, due to the fact that it is nesting habitat for the Southwestern willow flycatcher and there 

is no suitable native vegetation there to replace it, if removed. Nesting areas in saltcedar thickets 

are extremely vulnerable to damage or loss from wildfire, but fluctuating lake levels create a 

situation where native riparian trees will not establish and grow to create flycatcher nesting 

habitat. 

A biocontrol agent for control of saltcedar, Diorhabda elongata, has spread into northern Arizona 

from introductions in Utah. This beetle is moving faster than originally thought, is working its 

way down the Virgin and Colorado Rivers, and has now been identified in the Little Colorado 

River. It is probably only a matter of time until it reaches large rivers with saltcedar on the Tonto

NF. It may be prudent to begin a program of removing saltcedar in a slow and controlled fashion 

so that native species can gradually move in to replace them and ecosystems will not suffer undue 

disruption when the beetle arrives.
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EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 169

Alternative 1: No Action (continue ongoing treatments)

Direct and Indirect Effects

Manual removal of saltcedar along rivers is futile due to the nature of saltcedar reproduction and 

extensive root system. Saltcedar growing along the Verde River will become denser, eventually 

crowding out native riparian vegetation. Conditions along the Upper Salt River probably will not 

change.

Cumulative Effects

Current grazing management along the Verde River allows for nesting habitat for all types of 

subtropical migratory birds to develop between scouring flood events. If saltcedar is not removed, 

it provides a seed source that readily seeds new silt bars created by flooding. Dense saltcedar

thickets will increase flammability of riparian vegetation along the river, decreasing native 

riparian vegetation communities.

Alternative 2: Integrated Vegetation Management, Excluding Use of Herbicides

Same effects as for alternative 1.

Research Natural Areas, Blue Point Botanical Area, and the Sierra Ancha 

Experimental Forest

Proposed Action: Integrated Vegetation Management

Direct and Indirect Effects

Since these areas were designated to represent various vegetation communities, it is essential to 

control invasive species, if they are to retain the characteristics for which they were selected. This 

action is the most effective for removal of invasive species in all vegetation types. It allows for 

the best custom-fit of treatments for specific weeds in specific vegetation types.

With an emphasis on early detection, removal of infestations when they are first found and 

hopefully small in size, management actions will have no impact on native vegetation. If 

infestations are not found in a timely manner, restoration with native species will be done.

Cumulative Effects

Studies being conducted in RNAs could be affected by invasive plant management actions. Prior 

to conducting any weed management actions, the Tonto NF will communicate with appropriate 

personnel at Rocky Mountain Forest and Range Experiment Station, to determine if there are any 

ongoing studies in the area that is proposed for treatment. Forest activities within RNAs are 

limited, so cumulative effects are limited to effects of the proposed action and alternatives on 

invasive weed infestations.

Alternative 1: No Action (continue ongoing treatments)

Direct and Indirect Effects

Character of RNAs may be modified by infestations of invasive weeds, rendering the RNAs 

unsuitable as representative areas for various vegetation communities. Current management has 

proven to be inadequate to control some species, such as starthistles and Russian knapweed.
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170 Environmental Assessment for Integrated Treatment of Noxious or Invasive Plants, Tonto NF

Extensive wildfires that have burned large areas of Sonoran Desert in the last few years will 

eventually change the character and species composition of the Sonoran Desert, if management of 

invasive species continues at its current slow pace.

Cumulative Effects

Studies being conducted in RNAs could be affected by invasive plant infestations. On the other 

hand, studies could also be affected by invasive plant management actions, as for the proposed 

action. Cumulative effects are limited, as discussed in the cumulative effects section for the 

proposed action.

Alternative 2: Integrated Vegetation Management Excluding the Use of Herbicides

Direct and Indirect Effects

While this alternative offers more options for controlling invasive plants than alternative 1, there 

are some species of plant that will only respond to herbicidal treatment. Perennial plants may be 

set back by biological controls and actions such as repeated burning, mowing, or grubbing; but 

unless a systemic herbicide kills underground root reserves of carbohydrates, the plant will 

survive. Repetition of these control methods may change the vegetation community, since 

prescribed fire may not target the invasive plant as well as an herbicide might. Also, with fire or 

mechanical control methods, erosion may be increased, resulting in a loss of soil productivity, 

and ultimate change in the plant community.

Cumulative Effects

Same as for alternative 1.

Inventoried Roadless Areas

Environmental Consequences

As with motorized recreation, the proposed action and alternatives may result in short term 

closures of trails or areas to treat invasive weeds and prevent spread of those weeds.

Environmental Justice

Affected Environment

Executive Order 12898, Federal Actions to Address Environmental Justice in Minority 

Populations and Low Income Populations, requires federal agencies to identify and address any 

disproportionate adverse human health or environmental effects of its projects on minority or 

low-income populations. According to this Executive Order, each federal agency must conduct its 

programs, policies, and activities that substantially affect human health or the environment in a 

manner that ensures that such programs, policies, and activities do not have the effect of 

excluding persons or populations from participation in, denying persons or populations the 

benefits of, or subjecting persons or populations to discrimination because of their race, color, 

national origin, or income level.

Executive Order 13045, Protection of Children from Environmental Health Risks and Safety 

Risks, directs federal agencies to identify and assess environmental health risks and safety risks 

that may disproportionately affect children.
Chapter 3 - Environmental Consequences

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 171

Table 15. Minority population and persons living below poverty level in the area of the 

Tonto National Forest

Location Minority persons 

(% of entire population)

Persons living below poverty level 

(% of entire population)

Gila 22.2 17.4

Maricopa 22.6 11.7

Pinal 29.6 16.9

Yavapai 8.1 11.9

State of Arizona 24.5 13.9

United States 22.9 12.4

Environmental Consequences

Proposed Action: Integrated Vegetation Management

Direct and Indirect Effects

Many people in Gila and Pinal Counties live a rural lifestyle; a number of those people have 

livelihoods that depend upon productivity of their land and public lands on which they have 

permits. They are by no means the majority of people in Gila County or of any other county on 

the Tonto NF; but these Executive Orders were enacted to protect minorities such as these.

Inaction on the part of either the Forest Service or adjacent landowners with regard to invasive 

plant control extends the life of invasive plant populations and lowers ecological values on both 

sides of the fence. The proposed action addresses environmental justice for that minority of 

people, whose living is made from public and private land.

Alternative 1: No Action (continue ongoing treatments)

Direct and Indirect Effects

The result of implementing this alternative is that weeds will continue to grow out of control.

Invasive plants will spread onto private lands in spite of private landowners’ efforts to control 

them.

Alternative 2: Integrated Vegetation Management Excluding the Use of Herbicides

Direct and Indirect Effects

This alternative will not effectively suppress spread of some weeds. Effects of implementation of 

this alternative are intermediate between the proposed action and the “No Action” alternative.

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 173

Chapter 4 - Consultation and Coordination

The following Forest Service employees served on the interdisciplinary team to complete the 

analysis for this project:

ID Team Members:

Name Title Responsibility

Patti Fenner Forest Noxious Weed Program 

Manager

ID Team Leader, Invasive plants, 

herbicides, federally-listed plants, effects to 

human health, environmental justice

Norm Ambos Forest Soil Scientist Soils, Vegetation communities

Bob Calamusso Forest Fisheries Biologist Aquatic wildlife species

Emily Garber Forest Special Uses Specialist Special Uses

Karyn Harbour Forest Mineral Specialist Mining activities

Mike 

Henderson

Pleasant Valley Ranger District 

Fuels Program Fire

Connie Lane Recreation/Lands Staff, Globe 

Ranger District Non-motorized recreation, wilderness

Steve Lohr Forest Wildlife Biologist Wildlife

Don Luhrsen Forest Range Program Manager 

(fall 2005 to 2009) Range management

Buck 

McKinney

Forest Range Program Manager 

(through fall 2005) Range management

Kathy Nelson Forest Watershed Assistant Water quality

Vinnie Picard Forest Public Information 

Officer Public involvement plan

Tammy Pike Forest OHV Specialist Motorized recreation, Inventoried Roadless 

Areas

Mike Ross Forest Wildlife Biologist (retired 

2005) Wildlife, federally-listed species

Scott Wood Forest Archeologist Cultural and archaeological resources

Candy Luhrsen Forest Writer-editor
Chapter 4 – Consultation and Coordination

174 EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF

The Forest Service consulted the following individuals, federal, state and local agencies, tribes 

and non-Forest Service persons during the development of this environmental assessment:

Federal and State Officials and Agencies

City of Apache Junction Parks & Rec. Dept.

Town of Carefree

Town of Cave Creek

Town of Fountain Hills

City of Globe

Town of Miami

Town of Payson

Pleasant Valley Community Council

City of Scottsdale

Town of Superior

Tonto Hills Community Association

Chino Winds Natural Resource 

Conservation District

East Maricopa Natural Resource 

Conservation District

Tonto Natural Resource Conservation 

District

Winkelman Natural Resource Conservation 

District

Arizona Assoc. of Conservation Districts

Apache County Development & Community 

Services Dept.

Gila County Board of Supervisors

Gila County Cooperative Extension

Gila County Planning/Zoning

Gila County Sheriff’s Department

Maricopa County Board of Supervisors

Maricopa County Cooperative Extension

Pinal County Board of Supervisors

Verde Natural Resource Conservation 

District

Yavapai County Board of Supervisors

Yavapai County Cooperative Extension

Arizona Assoc. of Counties

Central Arizona Council of Governments

Arizona Dept. of Agriculture

Arizona Commission of Agriculture & 

Horticulture

Arizona Dept. of Environmental Quality

Arizona Game & Fish Department

Arizona House of Representatives

Office of Governor Napolitano

Office of the Attorney General

Office of Senator John Kyl

Office of Senator John McCain

Arizona Dept of Transportation

Arizona State Parks

Arizona State Land Department

Arizona State University

University of Arizona

University of Arizona at NAU

Arizona Office of Tourism

Arizona State Mine Inspector

Arizona State Treasurer

Boyce Thompson Arboretum

Agua Fria National Monument

Animal & Plant Health Inspection Service

Bureau of Indian Affairs

Bureau of Land Management

Bureau of Reclamation

Tonto National Monument

U.S. Army Corps of Engineers

U.S. Fish & Wildlife Service

Federal Highway Administration

International Assoc. of Fish & Wildlife 

Agencies

Arizona Public Service

Central Arizona Project

Salt River Project
Chapter 4 – Consultation and Coordination

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 175

Tribes

Ak-Chin Indian Community

Fort McDowell Yavapai Nation

Gila River Indian Community

Hopi Tribe

Salt River Pima-Maricopa Indian Community

San Carlos Apache Tribe

Tohono O’odham Nation

Tonto Apache Tribe

White Mountain Apache Tribe

Yavapai-Apache Nation

Yavapai-Prescott Indian Tribe

Zuni Pueblo

Others

Scoping list available upon request.

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 177

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Chapter 5 - References

EA for Integrated Treatment of Noxious or Invasive Plants on the Tonto NF 179

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