Environmental Assessment/Assessment of Effect

August 2006

Bright Angel Creek Trout Reduction Project 

Grand Canyon National Park ● Arizona

Grand Canyon National Park Service 

U.S. Department of the Interior 

Grand Canyon National Park 

Environmental Assessment 

Assessment of Effect

Bright Angel Creek Trout Reduction Project 

Grand Canyon National Park ● Arizona

Summary

This combined Environmental Assessment and Assessment of Effect (EA/AEF) has been prepared in 

compliance with the National Environmental Policy Act (NEPA), as amended, and the National Historic 

Preservation Act (NHPA), as amended. The National Park Service (NPS) intends to follow 36 CFR 

800.8(c), and use the process and documentation required for the preparation of all NEPA documents to 

comply with Section 106 of the NHPA in lieu of the procedures set forth in sections 800.3 through 800.6. 

This EA/AEF evaluates a No Action Alternative (Alternative A), and an action alternative (Alternative B) that 

proposes mechanical removal of non-native fish species (primarily trout) from Bright Angel Creek in Grand 

Canyon National Park. The dual purposes of the project are to benefit endangered humpback chub (Gila cypha) 

and other native fish species in the mainstem Colorado River, and to restore and enhance, to the extent possible, 

the native fish community that once flourished in Bright Angel Creek. To meet these objectives, the preferred 

alternative proposes to reduce populations of non-native brown trout and, coincidentally, rainbow trout in Bright 

Angel Creek by means of a weir (fish trap) installed near the mouth of the creek. Trout would also be removed 

incidental to fish population surveys using electrofishing. The proposed action would begin as early as November 

2006 and continue for five years, with annual monitoring and evaluation of the project. 

Note to Reviewers and Respondents 

This EA/AEF will be on public review for 30 days. You may review the document online at 

http://parkplanning.nps.gov/grca. If you wish to comment on the document, you may post comments online 

at.the same web address, or you may mail comments to the name and address below. Our practice is to make 

comments, including names, home addresses, home phone numbers, and email addresses of respondents, 

available for public review. Individual respondents may request that we withhold their names and/or home 

addresses, etc., but if you wish us to consider withholding this information you must state this prominently at 

the beginning of your comments. In addition, you must present a rationale for withholding this information. 

This rationale must demonstrate that disclosure would constitute a clearly unwarranted invasion of privacy. 

Unsupported assertions will not meet this burden. In the absence of exceptional, documentable 

circumstances, this information will be released. We will always make submissions from organizations or 

businesses, and from individuals identifying themselves as representatives of or officials of organizations or 

businesses, available for public inspection in their entirety. 

Comments must be postmarked or posted online no later than October 2, 2006. Please address comments to:

Joseph F. Alston, Superintendent 

Grand Canyon National Park 

Attention: Office of Planning and Compliance 

P.O. Box 129 / 1 Village Loop 

Grand Canyon, Arizona 86023 

For further information concerning this document, or to obtain a paper or electronic copy of the document, 

contact Rick Ernenwein, Project Planning Leader, at the above address or call (928) 779-6279. 
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CHAPTER 1 – PURPOSE AND NEED FOR ACTION 

INTRODUCTION 

The National Park Service (NPS) proposes to enhance native fish populations and restore natural 

ecosystem values within Bright Angel Creek by reducing the population of non-native brown (Salmo 

trutta) and, coincidentally, rainbow trout (Oncorhynchus mykiss). Bright Angel Creek, a tributary of the 

Colorado River, is located within Grand Canyon National Park (GRCA), Coconino County, Arizona, as 

shown in Figure 1. Trout would be removed from the creek during their spawning season (OctoberJanuary) each year for five years; the effectiveness of the reduction program would be assessed by 

monitoring population changes in the Bright Angel Creek native fish community. 

This combined Environmental Assessment and Assessment of Effect (EA/AEF) has been prepared in 

compliance with the National Environmental Policy Act (NEPA), as amended, (and NPS policies and 

guidance related to NEPA), and with the National Historic Preservation Act (NHPA), as amended. The 

NPS intends to follow 36 CFR 800.8(c), and use the process and documentation required for the 

preparation of all NEPA documents to comply with Section 106 of the NHPA in lieu of the procedures set 

forth in sections 800.3 through 800.6. In compliance with NEPA, this EA/AEF provides the decisionmaking framework that 1) analyzes a reasonable range of alternatives to meet project objectives, 2) 

evaluates potential issues and impacts to Grand Canyon National Park’s resources and values, and 3) 

identifies mitigation measures to lessen the degree or extent of these impacts. This document is also 

tiered to the U.S. Department of the Interior’s (DOI) EA for the Proposed Experimental Releases from 

Glen Canyon Dam and Removal of Non-Native Fish (DOI 2002), which addresses reduction of trout in 

the Colorado River in GRCA. 

PURPOSE AND NEED 

The dual purposes of the proposed action are to benefit endangered humpback chub (Gila cypha) and 

other native fish species in the mainstem Colorado River, and to restore and enhance, to the extent 

possible, the native fish community that once flourished in Bright Angel Creek. Bright Angel Creek 

historically supported large populations of native speckled dace (Rhinichthys osculus), as well as native 

suckers and occasionally chubs (Minckley 1978, Carothers and Minckley 1981). In recent years, the 

creek’s fish community has been dominated by non-native trout (salmonids). Otis (1994) reported 

finding numerous brown trout but very few speckled dace in seven sampling trips in 1992-1993. This 

situation parallels a documented and accelerating decline in native fish populations throughout the 

Colorado River system and in GRCA (Holden and Stalnaker 1975, Valdez and Carothers 1998, Coggins 

et al. 2002, Van Haverbeke and Coggins 2003). Predation by and competition with the large number of 

non-native salmonids in the Colorado River and its tributaries are contributing factors to this decline 

(Valdez and Ryel 1995, Marsh and Douglas 1997, Coggins et al. 2002). However, in recent information 

provided by the Grand Canyon Monitoring and Research Center (GCMRC 2006), it appears that the 

humpback chub population in Grand Canyon may be stabilizing. Bright Angel Creek provides important 

spawning habitat for brown and rainbow trout, which are predators on humpback chub and other native 

fishes (Minckley 1978, Carothers and Minckley 1981, Otis 1994, Marsh and Douglas 1997, Rowell 

2001). Interrupting the annual spawning cycle by removing adult trout as they aggregate in Bright Angel 

Creek is a feasible and potentially effective method for reducing numbers of trout, particularly brown 

trout, to benefit humpback chub and other native fishes. 
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Federal Legislative and Policy Mandates 

The proposed action is consistent with the NPS Management Policies 2001 that require national parks to 

maintain native plants and animals as parts of natural ecosystems, and to remove established populations 

of exotic (i.e., non-native) species. Specifically, NPS Management Policies 2001 call for the eradication 

of exotic species if their control is prudent and feasible and if those species interfere with the perpetuation 

of native species. Total eradication of non-native trout from Bright Angel Creek would be difficult to 

achieve using solely mechanical means; however, populations can be substantially reduced and 

maintained at low levels, thus decreasing competition and predation pressures on speckled dace and other 

native fish. 

The proposed action also conforms to the NPS Organic Act of 1916, which mandates national parks to 

conserve the natural resources found therein and to manage those resources to avoid their impairment. 

Actions designed to protect and restore the native species that comprise the Park’s natural aquatic 

community further the intentions of that Act. Reducing threats to a federally listed species (the 

endangered humpback chub) by reducing mainstem populations of predacious trout is also consistent with 

NPS directives to comply with the Endangered Species Act of 1973, as amended, and with the non-native 

fish control measures in the U.S. Fish and Wildlife Service (USFWS) recovery goals for the humpback 

chub (USFWS 2002a). 

Finally, the proposed action furthers GRCA’s management objectives as articulated in the Park’s 1995 

General Management Plan. Specifically, the project would help the Park meet the following objectives: 

• To the maximum extent possible, restore altered ecosystems to their natural conditions. In 

managing naturalized ecosystems, ensure the preservation of native components through the 

active management of non-native components and processes. 

• Manage ecosystems to preserve critical processes and linkages that ensure the preservation of 

rare, endemic, and specially protected (threatened/endangered) plant and animal species. 

Background 

In GRCA, few systematic studies were conducted on fish populations in the Colorado River and its 

tributaries before Glen Canyon Dam was completed in 1963, and none were conducted before warmwater, non-native fish began to invade the mainstem at the end of the nineteenth century and before trout 

were introduced in the 1920s. Eight native species were indigenous to the system: humpback chub, 

roundtail chub (Gila robusta), bonytail (G. elegans), speckled dace, flannelmouth sucker (Catostomus 

latipinnis), bluehead sucker (Catostomus discobolus), razorback sucker (Xyrauchen texanus), and 

Colorado pikeminnow (Ptychocheilus lucius). Of these eight, speckled dace, flannelmouth sucker, 

bluehead sucker, razorback sucker, and one or more species of chub have been documented from Bright 

Angel Creek (Minckley et al. 1991, Otis 1994, Valdez and Carothers 1998). The endangered humpback 

chub was initially described as a species from a specimen taken near the mouth of Bright Angel Creek 

(Miller 1946). 

Surveys conducted in Grand Canyon in the last 40 years have confirmed that three native species—

roundtail chub, bonytail, and Colorado pikeminnow—have been extirpated from the Park, and a fourth, 

razorback sucker, may be gone as well (Valdez and Carothers 1998). Until recently, the population of 

endangered humpback chub appeared to be in decline (Humpback Chub Ad Hoc Committee 2003, 

Coggins et al. 2003), and biologists were concerned about the remaining three native species. However, 
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in recent information provided by the Grand Canyon Monitoring and Research Center (GCMRC 2006), it 

appears that the humpback chub population in Grand Canyon may be stabilizing. The decline of the 

native fish assemblage in Grand Canyon has been attributed to the radical alteration of the aquatic 

environment by Glen Canyon Dam, and to competition and predation by over 20 species of non-native 

fish, including trout, that have invaded or been introduced into the system (Valdez and Carothers 1998). 

Predation and competition by non-native fish have been implicated in the decline of native fish species 

throughout the Colorado River system, not solely within GRCA (Hawkins and Nesler 1991, Blinn et al. 

1993, Upper Colorado River Endangered Fish Recovery Program 2002). Efforts to reduce and control 

non-native species are continuing in several localities throughout the Colorado River Basin, including the 

mainstem Colorado River in Grand Canyon (U.S. Department of the Interior 2002, Yard and Coggins 

2003). The proposed action would contribute to this multifaceted, system-wide attempt to salvage and 

restore native fish species. 

MANAGEMENT AND PLANNING HISTORY 

The U.S. Forest Service conducted the first known introductions of non-native fish in accessible 

tributaries of the Grand Canyon for a number of years prior to the creation of the national park in 1919 

(Williamson and Tyler 1932 cited in Carothers and Minckley 1981). After the Park was established, the 

NPS introduced various trout species (brook trout [Salvelinus fontinalis], rainbow trout, brown trout) into 

Bright Angel Creek in numerous episodes between 1920 and 1964 (Haden 1992). All stocking of nonnative fish ceased in the Park after 1972, but the Arizona Game and Fish Department (AGFD) continued 

to stock rainbow trout in the Colorado River just upstream of the park boundary into the 1990s. 

According to Sellars (1997), during the years that non-native species were stocked in GRCA waters, 

federal agencies like the NPS were responding to prevailing social values and public demand by giving 

sport fishing a higher priority than preservation of native aquatic communities. This management 

practice was acknowledged during the 1930s to be an “important exception to general [NPS] policy,” but 

it was believed that recreational benefits overruled the biological “disadvantages which are incidentally 

incurred” (Wright et al. 1933 cited in Sellars 1997). Social values began to shift in the mid-twentieth 

century as the scientific community, the public, and government agencies increasingly understood that 

introduced species could disrupt entire ecosystems and lead to the decline and extinction of native 

species. Reflecting the growing public understanding and appreciation of ecological values, the NPS 

became increasingly reluctant to make an “exception to general policy” when it came to sport fishing in 

national parks. That “general policy” was and is rooted in the NPS Organic Act of 1916, the founding 

legislation of the National Park Service. 

NPS management objectives and practices now favor preserving native fish communities over non-native 

sport fisheries where exotic species are not maintained to meet an identified park purpose. The Fish 

Management Plan for GRCA of 1981, referencing the National Park Service Management Policies 

Handbook (1978), stated that management of fish resources shall be “Specifically aimed toward 

preservation or restoration of the full spectrum of native species, including fish” and “no artificial 

stocking of exotic fish species will occur; artificial stocking of fish may be employed only to re-establish 

native species.” Currently, the GRCA Resource Management Plan (1997) identifies the threat posed by 

non-native species to park wildlife resources as a major issue, and states that “In cases where funding and 

personnel levels allow and where success is likely, control measures will reduce alien species 

populations.” 

In 2002-2003, GRCA coordinated with the Grand Canyon Monitoring and Research Center (GCMRC) to 

conduct a feasibility study to determine the efficacy of using a weir in Bright Angel Creek to capture and 

remove brown trout. The study was performed by biologists from SWCA Environmental Consultants 
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(SWCA), under contract to GRCA, with funding from the NPS and the U.S. Bureau of Reclamation 

(USBR). Biologists captured 423 brown trout and 188 rainbow trout during the 64 days of weir operation 

(November 18, 2002-January 21, 2003) (SWCA 2003). Included in the catch was one bluehead sucker. 

After the pertinent data were collected, the rainbow trout and bluehead sucker were released above the 

weir; the brown trout were sacrificed and packed out of Grand Canyon. The study confirmed the 

effectiveness of removing spawning trout from Bright Angel Creek. In a related project, biologists under 

contract to the NPS conducted population surveys in additional Colorado River tributaries (Shinumo, 

Tapeats, Kanab and Havasu Creeks) in 2004 and 2005 to determine baseline fish populations. The 

ultimate purpose of the effort is to restore and conserve the native fish assemblages in those tributaries. 

In 2006, a predator load survey was conducted in Bright Angel Creek that determined the effectiveness of 

using backpack electrofishing as a management tool for population sampling and non-native fish removal. 

(SWCA et al 2006). 

Internal Scoping 

This project was initially discussed among the various groups associated with the Glen Canyon Dam 

Adaptive Management Program (GCDAMP). A feasibility study was conducted as described above, and 

the results further discussed among the GCDAMP groups. A project proposal and environmental 

screening form was reviewed by the park’s Project Review Board and Parkwide Interdisciplinary Team in 

2003. An internal NPS review of the draft EA/AEF was conducted in September 2005. 

Public Scoping 

The details of public scoping are presented in Chapter 4 (Consultation and Coordination). In summary, 

public scoping occurred from December 2003 – January 2004. In addition, this project (along with the 

trout removal project in the mainstem Colorado River) has been a frequent topic of discussion at meetings 

associated with the Glen Canyon Dam Adaptive Management Program, which includes tribes, other 

agencies, and stakeholders interested in the river corridor in the park. 

EA/AEF Distribution 

A letter announcing the availability of the EA/AEF is being distributed to those who responded to the 

public scoping efforts and to the park’s mailing list of agencies, tribes and stakeholders who have 

expressed interest in such projects. Availability of the EA/AEF for public review is also being advertised 

through the NPS Planning, Environment and Public Comment (PEPC) website 

(http://parkplanning.nps.gov/grca), and through a press release. The EA/AEF is available electronically 

at the PEPC website, and can also be obtained in paper or electronic form by contacting the park. 

Agencies and Tribes 

In addition to the agencies and tribes associated with the Glen Canyon Dam Adaptive Management 

Program who continue to be contacted about this project through that program, all applicable agencies, 

tribes and government representatives are being sent letters concerning the availability of this EA/AEF. 

ISSUES AND IMPACT TOPICS 

Issues and impact topics related to this proposal were identified as a result of internal and public scoping 

(see Chapter 4, Consultation and Coordination for more information). During the 30-day public scoping 

period for this project (December 2003 – January 2004), 50 individuals, organizations, and agencies 

provided input. While all comments were carefully considered, some were found to be outside the scope 

of this project (e.g., additional actions to restore Bright Angel Creek not directly related to fish). A 

number of commenters believed that the proposed action had been implemented before the public scoping 

period, some responding to an incorrect date in the scoping letter indicating that the weir would first be 

installed in 2003 when it should have said 2005 (and now it is proposed to be installed in 2006 or 2007). 
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Some commenters also incorrectly appeared to believe that the 2002 feasibility study was the part of the 

proposed action; it was not. Many respondents were interested in trout fishing and did not support 

removing trout from the creek. Others were generally supportive of efforts to enhance and restore the 

creek’s environment. 

. 

Comments that directly affected the alternatives or analysis included: 

• Reducing trout in Bright Angel Creek would result in the loss of a valuable sport fishery. 

• What are the potential impacts to native fish populations? 

• The NPS should consider the economic repercussions. 

• The proposed action, when coupled with trout reduction activities in the Colorado River, may 

result in the eradication of trout in Grand Canyon and the loss of the Lees Ferry sport fishery. 

• Trout will continue to invade Bright Angel Creek from the Colorado River. 

• NPS should consider other trout removal efforts, such as harvest by anglers, alternative 

barrier structures, and piscicides (toxicants). 

Impact Topics Analyzed in This Document 

Aquatic Resources – NEPA calls for an examination of the impacts on the components of affected 

ecosystems, which for this proposed action includes aquatic resources. Impacts to aquatic resources are 

anticipated because it is the intent of the proposal to alter the fish species composition of Bright Angel 

Creek, substantially reducing the abundance of non-native trout to allow for the increase of native fish 

species. The action would have a direct effect on individual non-native fish in the creek’s ecosystem and 

is anticipated to have an indirect effect on native fish species and other aquatic ecosystem components. 

Aquatic resources will be addressed in Chapter 3 of this document. 

Special Status Species – The 1973 Endangered Species Act, as amended (ESA) requires an examination 

of impacts to all federally listed threatened or endangered species for any major action authorized, 

funded, or carried out by a federal agency. In addition, NPS policy requires examination of the impacts to 

state-listed and federal candidate species. Six special status species either are known to occur or may 

occur in the project area and have the potential to be affected by the proposed action. Of these, two 

species are both federally listed by the USFWS and considered Wildlife of Special Concern in Arizona 

(WSCA) by the AGFD. They are humpback chub (Gila cypha) and razorback sucker (Xyrauchen 

texanus). One species, bald eagle (Haliaeetus leucocephalus), is just federally listed, and another two, 

northern leopard frog (Rana pipiens) and osprey (Pandion haliaetus), are state listed. The sixth special 

status species that may be affected, flannelmouth sucker (Catostomus latipinnis), is not listed but is 

considered a Species of Concern by the USFWS. All six species will be addressed in Chapter 3 of this 

document. 

Ethnographic (traditional cultural properties) – Executive Order 13007 requires federal agencies “to 

the extent practicable, permitted by law, and not clearly inconsistent with essential agency functions, (1) 

accommodate access to and ceremonial use of Indian sacred sites by Indian religious practitioners and (2) 

avoid adversely affecting the physical integrity of such sacred sites.” There is a potential for the project 

to affect sacred sites or other traditional cultural properties; therefore, this subject will be further 

evaluated under Cultural Resources in Chapter 3. 

Visitor Experience – The NPS Organic Act of 1916 and the NPS Management Policies 2001 direct 

national parks to provide for public enjoyment, including recreational opportunities. Reducing trout 

populations in Bright Angel Creek would affect angling for trout in that stream, one of the recreational 
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opportunities currently available in GRCA. Visitor experience will be addressed in Chapter 3 of this 

document. 

Impact Topics Dismissed from Further Analysis 

The NPS reviewed the topics listed below and determined that the impacts, if any, for these topics will be 

at a minor level or less in degree so the topics have been dismissed from detailed analysis in this 

document, for the reasons stated. 

Cultural Resources – Consideration of impacts on cultural resources is required by the National Historic 

Preservation Act of 1966, as amended; Archeological Resources Protection Act of 1979; Native American 

Graves Protection and Repatriation Act of 1990; NPS Management Policies 2001; and other federal 

statutes, policies, and guidelines. In addition, NEPA regulations at 40 CFR 1508.27 require that the 

intensity of potential impacts be evaluated in terms of potential adverse effects on archaeological and 

other cultural resources, including historic properties listed on or eligible for inclusion in the National 

Register of Historic Places. The direct effects of the project are confined within Bright Angel Creek and 

the Colorado River as defined for the area of effect; there are no known historic properties within the 

creek or river that may be affected by the project, so those cultural resources will not be further evaluated 

in Chapter 3. 

Floodplains – Executive Order 11988 requires federal agencies to examine potential risk and impacts of 

placing facilities within floodplains. The proposed action would take place within Bright Angel Creek; 

however, it would not involve any alteration of the stream channel or existing streamflow patterns, and 

would therefore not affect the Bright Angel Creek floodplain. 

Indian Trust Resources – Under DOI Secretarial Order 3175 and DOI Environmental Compliance 

Memorandum 95-2, agencies of the department are required to consider the effects of their actions on 

Indian trust assets, which are defined as legal interests in property held in trust by the federal government 

for the benefit of Indian tribes or individuals. Examples of such assets include lands, mineral rights, 

hunting and fishing rights, and water rights. There are no Indian trust resources at GRCA. Therefore, the 

project would have no effects on Indian trust resources, and this subject will not be further analyzed in 

Chapter 3. 

Wetlands – Executive Order 11990 requires federal agencies to avoid impacts on wetlands where 

possible. In addition, NEPA regulations at 40 CFR 1508.27 require that the intensity of potential impacts 

be evaluated in terms of potential adverse effects on wetlands. Some wetland areas do occur along Bright 

Angel Creek; however, no activities associated with the proposed action would encroach upon them or 

alter their values or functions. 

Special Status Species - While some special status species known or likely to occur in Coconino County, 

Arizona, will be analyzed in this document in Chapter 3, most will not. The majority of federally listed 

and candidate species and most state-listed species in Coconino County would not be affected by the 

proposed action. Either they do not occur in or near the project area, or potentially suitable habitat for 

them is not present within the area potentially affected. (See Table A-1 and Table A-2 in Appendix A for 

complete lists of federal and state special status species.) 

Four federally listed species are known to occur or may occur in Bright Angel Canyon but would not be 

affected by the proposed action. 1) Endangered Kanab ambersnail (Oxyloma haydeni kanabensis) is 

known from only two localities in Grand Canyon, neither of which is within 25 miles of the project area; 
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however, potentially suitable habitat is present in springs emanating from limestone and sandstone 

formations in upper Bright Angel Canyon. No project activity would take place in spring habitats, nor 

would any resulting changes in the creek’s fish assemblage affect Kanab ambersnails if they were present. 

2) Threatened Mexican spotted owls (Strix occidentalis lucida) nest in the upper reaches of the canyon, 

but no work would take place within 0.5 mi of a Protected Activity Center (PAC). The level of human 

activity and sound associated with the proposed action would be too low to disturb nesting owls. 3) 

Endangered southwestern willow flycatchers (Empidonax traillii extimus ) may visit riparian habitat along 

Bright Angel Creek during spring and fall migrations, but that habitat is not suitable for nesting 

flycatchers. Removing trout from the creek may result in a slight (below detectable levels) increase in 

flying aquatic insects that could potentially benefit foraging flycatchers. The intensity of that potential 

indirect, beneficial impact would be negligible at most. 4) California Condor is federally listed as 

endangered, but is an experimental, nonessential population in Arizona and treated as a threatened species 

in GRCA. Several condors have become habituated to human presence in the Park and visit Phantom 

Ranch and the Bright Angel Campground looking for food. They may approach project personnel. If that 

should happen, the biologists would follow NPS-approved procedures (see the “Mitigation Measures” 

section of Chapter 2). It is unlikely that the proposed action would affect California condors. 

A fifth species, American peregrine falcon (Falco peregrinus anatum), was removed from the federal 

endangered species list in 1999, but the Park will continue to treat it as a listed species through August 

2004 (5 years after delisting). Peregrine falcons are also categorized as WSCA. They are known to nest 

near Bright Angel Canyon and forage throughout the region. No activity associated with the proposed 

action has the potential to adversely affect this species. Peregrine falcons may benefit indirectly from a 

potential slight increase in the availability of insects because insectivorous birds, such as swifts and 

swallows, form an important component of this species’ prey base.

Two additional WSCA species are known to or may occur in Bright Angel Canyon but would not be 

adversely affected by the proposed action. They are western red bat (Lasiurus blossevillii) and spotted 

bat (Euderma maculatum). These bats are insectivorous and could benefit if the propped action results in 

an increase in available insects. As with southwestern willow flycatchers and peregrine falcons, any such 

benefit would be negligible at best. 

Environmental Justice – Executive Order 12898 requires federal agencies to identify and address 

disproportionately high and adverse human health or environmental effects on minority and low-income 

populations. In the past, some of the fish killed in trout removal efforts in the park have been used by 

local Indian tribes as fertilizer for gardens or farms; however, this is a potentially beneficial effect, so it is 

not an environmental justice concern. This topic was dismissed from further analysis because each 

alternative would affect everyone equally and would not disproportionately impact minority or lowincome populations. 

 

Ecologically Critical Areas, Wild and Scenic Rivers, or other unique natural resources – NEPA 

regulations at 40 CFR 1508.27 require that the intensity of potential impacts be evaluated in terms of 

potential adverse effects on ecologically critical areas, wild and scenic rivers, or other unique natural 

resources. No such resources or special designations occur in the proposed project area. The proposed 

action would not compromise the eligibility of Bright Angel Creek for future designation as a Wild and 

Scenic River, nor would it compromise the future designation of any portion of GRCA as wilderness 

under the Wilderness Act of 1964. The proposed action would take place within the cross-canyon 

corridor, which was excluded from the Park’s Final Wilderness Recommendation (1993) as either 

proposed or potential wilderness. 
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Prime and Unique Farmland –NEPA regulations at 40 CFR 1508.27 require that the intensity of 

potential impacts be evaluated in terms of potential adverse effects on prime and unique farmlands. 

Prime farmland is defined as soil that particularly produces general crops such as common foods, forage, 

fiber, and oil seed; unique farmland produces specialty crops such as fruits, vegetables and nuts. No such 

farmlands occur in the project vicinity or would be affected by the project. 

Possible conflicts between the proposal and land use plans, policies, or controls for the area 

concerned - NEPA regulations at 40 CFR 1502.16 require that potential land use conflicts be addressed if 

they occur. The proposed project area is entirely within the boundaries and jurisdiction of GRCA, which 

is managed according to the Park’s General Management Plan of 1995. The proposed action is fully 

consistent with the management objectives set forth in that plan. 

Urban Quality and Design of the Built Environment – NEPA regulations at 40 CFR 1502.16 require 

that urban quality and design of the built environment be considered if they are potentially affected. No 

urban areas occur in the vicinity of the proposed action, and the built environment in the Phantom Ranch 

area would not be affected by a temporary weir structure in Bright Angel Creek. 

Energy Requirements and Conservation Potential – NEPA regulations at 40 CFR 1502.16 require that 

energy requirements or conservation potential be considered if they are potentially affected. 

Implementation of the proposed action would not affect any energy resources within the park. 

Public Safety – NEPA regulations at 40 CFR 1508.27 require that the intensity of potential impacts be 

evaluated in terms of potential adverse effects on public health and safety. The proposed action involves 

electrofishing, which does have a slight potential to harm crew and park visitors. However, with the 

appropriate application of the mitigation measures listed in Chapter 2 for the use of electrofishing 

equipment, no impacts to public safety are expected. 

Geologic Resources – No ground-disturbing activities would take place as part of the proposed action. 

Project personnel, when entering and exiting the creek, would use unvegetated, stony banks whenever 

possible to minimize streambank erosion. With this mitigation measure in place, the proposed action is 

expected to have a negligible impact on soils or other geologic resources. 

Water Resources – The Clean Water Act of 1972 requires consideration of impacts on jurisdictional 

waters of the United States and the potential for polluting surface waters. The proposed action would not 

divert or deplete streamflow or modify stream channel morphology. A U.S. Army Corps of Engineers 

404 permit would, therefore, not be necessary. The proposed action does not involve the use of any 

contaminants in or around Bright Angel Creek. Biologists wading in the water during weir operations 

and electrofishing may stir up bottom sediments, temporarily and locally increasing turbidity at a 

negligible level. The streambed of Bright Angel Creek, however, is largely armored with gravel, cobbles, 

and boulders, with little fine-grained sediment that can be easily suspended. Even short-term effects to 

water quality would be negligible. 

Air Quality – As a federally mandated Class I area under the Clean Air Act, GRCA receives stringent 

protection against increases in air pollution and further degradation of air quality-related values. Section 

118 of the Act requires all federal facilities to comply with existing federal, state, and local air pollution 

control laws and regulations. Impacts to park air quality or regional air quality are not expected from the 

proposed action because no equipment used would generate emissions and no activities would result in 

airborne dust. The scope of this project does not require consultation with the State of Arizona regarding 

air quality. 
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Soundscapes – The NPS has a mandate (NPS Management Policies 2001) to protect, maintain, or restore 

a park’s natural soundscape in a condition unimpaired by inappropriate or excessive noise sources. 

Operation of the weir would generate no noise, and the backpack electrofisher used for the population 

survey in Bright Angel Creek would be powered by noiseless batteries. As a result, there would be no 

effect from the proposed action on the Park’s soundscape. 

Terrestrial Biological Resources –NPS Management Policies 2001, the 1995 General Management 

Plan, and other NPS and park policies provide for the protection of the Park’s naturally occurring biotic 

communities. Activities associated with the proposed action would not contribute detectably to current 

levels of streamside use by visitors. Travel between upstream or downstream portions of Bright Angel 

Creek would be via the established trail adjacent to the stream. Biologists entering and leaving Bright 

Angel Creek as part of electrofishing operations would choose routes that avoid streamside vegetation to 

minimize trampling. Any incidental impact to riparian vegetation would therefore be negligible. The 

level of noise and human activity associated with the proposed action would be low and no terrestrial 

wildlife habitats would be altered; therefore, it is unlikely that terrestrial wildlife would be disturbed at 

more than a negligible level as a result of the project. 

Invasive Exotic Species – Executive Order 13112 on Invasive Species directs federal agencies to use 

relevant programs and authorities to prevent the introduction of invasive species; to provide for their 

control; and to minimize the economic, ecological, and human health impacts that invasive species cause. 

In keeping with this directive, all equipment (including personal gear like waders) associated with the 

proposed action would be cleaned prior to use to ensure that no invasive species are introduced into the 

project area. Project personnel would be instructed to look for non-native New Zealand mudsnails 

(Potamopyrgus antipodarum) in particular and to ensure that none are brought into the area or transported 

from one location to another. With this mitigation measure in place, the proposed action is not expected 

to aid in the spread of invasive exotic species. 

Socioeconomic Resources –The primary economic beneficiary of sport fishing at Bright Angel Creek is 

Xanterra Parks and Resorts, the concessioner that manages the lodge at Phantom Ranch and provides 

transportation by mule in and out of the Canyon. Xanterra expects no loss of revenue as a result of the 

proposed action (Streik 2004). Phantom Ranch operates at full or near-full occupancy year-round, with 

demand for its limited accommodations exceeding supply. While some people do visit the Bright Angel 

Creek area principally or solely to fish, and would not book mule rides or over-night accommodations if 

sport fishing were to diminish, they constitute a very small minority of Xanterra’s clientele park-wide. 

Diminishment of the Bright Angel Creek sport fishery would also have a negligible effect on the sale of 

fishing licenses and trout stamps in the state. In-state anglers likely fish at other locations and would 

continue to purchase licenses. Out-of-state visitors who buy licenses for use only at Bright Angel Creek 

account for an insignificant proportion of total licenses sold in Arizona each year. Xanterra stopped 

selling fishing licenses at Phantom Ranch several years ago due to the low level of interest. The trout 

removed from the creek would not be handled in such a way that they could be used for food; in any case, 

there would normally not be enough collected at any one time to be a commercial food source, and there 

are policy issues with any consideration of commercial fishing in a park. Since there is less than a minor 

impact expected for any entity, this topic is dismissed from further analysis. 

Park Operations – The NPS would outsource most of the work associated with the proposed project, but 

some support would be required from park personnel and equipment to transport fish remains out of the 

project area and to transport large gear in and out of the Canyon. Park rangers would help biologists 

educate visitors about the purpose of the action and provide routine support and law enforcement. 

Housing or other accommodations would be necessary in the Phantom Ranch area for the biologist(s) 
Bright Angel Creek Trout Reduction Project Chapter 1 

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operating the weir and electrofishing. These services are expected to have minor or negligible effects on 

park operations, so this topic will not be analyzed further. 

Wilderness – Bright Angel Creek is located in the Cross-Canyon Corridor, which is not included in the 

park’s recommended or potential wilderness. Although this is not analyzed throughout this document, 

there will be minor beneficial impacts to wilderness character from the preferred alternative because it 

enhances the natural conditions of Bright Angel Creek and the Colorado River. However, helicopter 

flights may rarely be needed in support of the actions in Bright Angel Creek. A Minimum Requirements 

Analysis (MRA) will be prepared for any needed helicopter support to mitigate effects to areas adjacent to 

the Cross-Canyon Corridor that are recommended for wilderness designation. Effects to wilderness are 

therefore expected to be minor or negligible, so will not be analyzed further. 
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CHAPTER 2 – ALTERNATIVES 

INTRODUCTION 

This chapter describes two alternatives. They are Alternative A: No Action and Alternative B: 

Mechanical Removal (Preferred Alternative). Alternatives considered but eliminated from further study 

are described as well. The predicted impacts of Alternatives A and B are summarized in Table 1 at the 

end of this chapter and analyzed in Chapter 3. Finally, Table 2 provides a summary of the alternatives 

and how well each alternative meets project objectives. 

DESCRIPTION OF ALTERNATIVES 

Alternative A – No Action 

Under this alternative no changes would be made to the existing environment. Trout and other non-native 

fish from the mainstem of the Colorado River and its tributaries would continue to be allowed to spawn in 

Bright Angel Creek without human interference. This alternative would not address the purpose and need 

identified in Chapter 1 of this document. 

Alternative B – Mechanical Removal (Preferred Alternative) 

Alternative B is the NPS preferred alternative and is the proposed undertaking for §106 compliance. All 

actions described in the preferred alternative are consistent with the approved 1995 general management 

plan and related park documents. Under Alternative B, trout would be mechanically removed from 

Bright Angel Creek using 1) a weir to capture them as they move upstream into the creek to spawn 

(Figure 2), and 2) electrofishing and dip netting to capture additional trout in the stream. The 

effectiveness of the reduction program would be assessed by monitoring population changes in the Bright 

Angel Creek fish community. This alternative is based upon a feasibility study conducted November 

2002 through January 2003, which determined that using a weir was successful at removing trout from 

Bright Angel Creek (SWCA 2003), and a non-native fish population survey in March 2006 which 

determined the effectiveness of using backpack electrofishing as a management tool in Bright Angel 

Creek (SWCA 2006). 

Trout Removal by Weir 

A weir is a fence-like barrier erected across a stream (Figure 2). Water flows through the structure, but 

fish above a certain size are diverted to a trap. Beginning as early as November 2006, the weir would be 

installed in November of each year and operated for approximately 70 consecutive days throughout the 

trout spawning season (November-January). At the end of this period, the weir would be removed. The 

most likely location for the weir would be in the creek downstream of Phantom Ranch near the footbridge 

by the NPS river ranger station. This unobtrusive site worked well during the feasibility study, but other 

suitable locations may be selected where stream depths are appropriate. The reduction efforts would 

continue annually for five years, with annual monitoring and evaluation of the project. 

The weir would be operated to capture all large-bodied fish moving upstream. Speckled dace, a smallbodied native fish, would be able to pass through the weir so would not be captured. Fish would be 

handled and processed according to the procedures developed by the Arizona Game and Fish Department 

for conducting fisheries research in Grand Canyon (Ward 2002). Only qualified biologists would handle 
Bright Angel Creek Trout Reduction Project Chapter 2 

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13 

and tag fish. All captured fish would be identified as to species, counted, measured, inspected for 

reproductive condition, and scanned for the presence of PIT tags (passive integrated transponders). 

Untagged native fish would be injected with a PIT tag. All trout would be examined for an adipose fin 

clip, indicating the presence of a PIT tag. Data would be recorded on standardized data sheets. 

Native fish species would be released above the weir, but all trout would be euthanized. All euthanization 

would be performed in a humane manner consistent with policy and law (e.g., the Animal Welfare Act). 

Stomachs of a sub-sample of trout would be removed and preserved for later analysis to ascertain food 

habits. The non-native fish carcasses would be preserved and transported out of the Canyon. The fish 

remains would be made available for such uses as garden composting, but final disposition of the 

carcasses would be determined after consultation with Native American tribes. 

At least one biologist would be present at all times during weir operations to perform the following tasks: 

1) ensure that the weir is operating properly, 2) check and remove fish from the trap as frequently as 

necessary, 3) clear away accumulated debris, 4) ensure that no other wildlife or non-target fish species are 

negatively affected by the weir, 5) remove the weir should a flooding event or safety issue occur, and 6) 

answer any inquiries from park visitors about the purpose and need for the weir. Three biologists would 

conduct the electrofishing effort (see below). A report assessing the effectiveness of the effort would be 

prepared each year. 

Fish Community Response Monitoring 

To determine the effects of trout reduction on the fish community in Bright Angel Creek, population 

changes in that community would be monitored annually. Two approaches would be used: 1) Population 

estimates of fish species present in the creek would be determined using electrofishing and the depletion 

survey method; and 2) a weir would be placed in the creek during the spring to capture and census native 

flannelmouth and bluehead suckers moving into Bright Angel Creek to spawn. 

The population surveys would require multiple, consecutive passes of defined reaches of stream using a 

backpack electrofisher such as the Smith-Root LR24. The number and locations of the reaches have yet 

to be determined, but initial efforts would be focused between the mouth of Bright Angle Creek and the 

confluence with Phantom Creek. These population surveys would include two 5-day episodes of 

electrofishing in November-January and two 5-day episodes in April-May. 

An electrofisher would introduce a mild electrical current into the water, causing fish to swim toward the 

anode of the shocker where they would be scooped up with dip nets. Captured fish would be held in livewells (porous tanks) located in the creek outside the depletion reach. Three or four passes would be 

needed to complete the survey. After each pass, all fish captured in that pass would be counted by species 

and the data recorded for later statistical analysis. The population estimates derived by this method would 

be compared over multiple years to obtain information about population changes through time. 

Additional data collected during the electrofishing would include the length and condition of each fish 

captured. All fish except speckled dace would be scanned for the presence of PIT tags, and untagged 

native fish other than speckled dace would be injected with a new PIT tag. All trout would be examined 

for an adipose fin clip. Native fish would be returned to the creek; all trout and other non-native fish 

would be euthanized. Stomachs of a sub-sample of trout would be removed and preserved for later 

analysis. The carcasses would be disposed of as previously described. 
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Bright Angel Creek Trout Reduction Project Chapter 2 

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To monitor spawning flannelmouth and bluehead suckers moving into Bright Angel Creek, biologists 

would install the weir at the same location identified for the trout reduction effort. For 45 days, from late 

March to mid-May, all large-bodied fish moving upstream would be captured in the weir (speckled dace 

would pass through). Captured fish would be removed, identified, measured, inspected for reproductive 

condition, and scanned for the presence of PIT tags. Native fish not previously tagged would be injected 

with PIT tags. Native species would be released above the weir. Trout would be euthanized and disposed 

of as previously described 

ALTERNATIVES CONSIDERED AND DISMISSED 

Chemical Removal 

This alternative would eliminate trout in Bright Angel Creek by means of chemical euthanization. In the 

late fall, during the trout spawning period, as many native fish as possible would be removed from the 

entire length of the creek using backpack electrofishers and dip nets. The captured native fish would be 

kept alive in off-channel containers. Antimycin, a piscicide (agent to kill fish), would then be added to 

stream sections covering the length of Bright Angel Creek, thus destroying all remaining fish as it spread 

downstream. Potassium permanganate (KmnO4) would be used to neutralize the toxicant before it 

entered the Colorado River. The fish carcasses would be collected using a block net, packed out by mule, 

and disposed of on the South Rim. The native fish held in off-channel containers would then be replaced 

into the creek, and some stocking of native fish species would be done to ensure population stability. 

Bright Angel Creek would be chemically treated only once. In subsequent years, a weir placed near the 

mouth of the creek would prevent additional trout from moving into the stream during their spawning 

period. 

The use of antimycin (available commercially under the label Fintrol) was considered for this project 

because it has been used successfully in several national parks (e.g., Rocky Mountain National Park, 

Great Smoky Mountains National Park, Crater Lake National Park) as well as on numerous other federal 

lands. It has been shown to be an effective and largely environmentally benign1

 method to remove fish 

from streams for over 30 years. It was eliminated from detailed study in this assessment for the following 

reasons: 

• Other national parks have closed the treated stream to recreational use for several days during 

application of antimycin. While this piscicide has not been shown to be harmful to humans, 

allowing public access to a creek containing a known toxicant and fish carcasses raises public 

health and aesthetic issues. Closing Bright Angel Creek would mean closing the North Kaibab 

Trail (the heavily used cross-canyon corridor of GRCA), two campgrounds, and possibly 

Phantom Ranch, a concession-operated lodge. This would be disruptive to park visitors and 

contracted concession operations. Not closing the trail between Roaring Springs and the 

Colorado River would present difficulties as well. The trail closely parallels Bright Angel Creek 

and ensuring that no one in that 9-mile reach approached the creek over the period of treatment 

would be a formidable task. 

 

1

 Antimycin is an antibiotic that kills fish by inhibiting cellular respiration. It loses its toxicity quickly, within a few hours, 

leaving no residue. In both field and laboratory applications, it has had no short-term or long-term effects on other vertebrates 

(amphibians, reptiles, birds, mammals), phytoplankton (microscopic aquatic plants), or macrophytes (large aquatic plants). 

Antimycin has been shown to kill phytoplankton (microscopic fresh-water shrimp and shrimp-like organisms (e.g., Gammarus)) 

and aquatic insects, but populations of these organisms have recovered to pre-treatment or near pre-treatment levels within 

several (Grisak and Marotz 2003). 
Bright Angel Creek Trout Reduction Project Chapter 2 

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16 

• Antimycin’s efficacy in Bright Angel Creek is unclear. This piscicide loses effectiveness quickly 

in streams with high gradients, and is less effective in cold and alkaline waters (pH over 8.5). 

Bright Angel Creek is a relatively high-gradient stream; it is cold in the winter during the trout 

spawn; and its pH often exceeds 8.5. Tests would have to be performed to determine if antimycin 

would be effective in this environment. 

• Use of a piscicide to effect removal of non-native fish would be a more intrusive, elaborate, and 

costly procedure than mechanical removal. It would directly affect more attributes of the Bright 

Angel Creek aquatic community, requiring more complex ecosystem monitoring before and after 

treatment to assess impact to macroinvertebrates and other resources. 

Increased Angling 

NPS rangers at Phantom Ranch report a substantial decrease in fishing in Bright Angel Creek over the last 

10-15 years (Sjors 2004). Bag and size limits for trout at Bright Angel Creek were eliminated some years 

ago to encourage removal of trout, yet angling pressure remains low, with the annual number of 

fishermen ranging between 75 and 200 (Kassovic 2004). Interest has been so low, the concessioner at 

Phantom Ranch stopped selling fishing licenses six years ago (Streik 2004). Given the difficult access to 

the fishery (an arduous 14-mile round-trip hike or mule ride), limited availability of overnight 

accommodations, and the fact that no catch limits are imposed now, it is difficult to conceive of 

incentives that would increase angling to the point of substantially reducing trout populations. 

Dewatering or Other Flow Modification 

Bright Angel Creek is not a regulated stream. No means are available to modify stream flow to 

disadvantage non-native fish (e.g., dewater redds to expose and desiccate trout eggs). 

Alternative Fish Barrier Structure 

An alternative was considered that would divide Bright Angel Creek by means of a seasonal fish barrier. 

The upstream portion of the creek would be managed for native fish, and the downstream portion would 

be managed for trout. This alternative was rejected because maintaining a trout fishery and allowing trout 

to spawn in the lower reach of the creek would not meet one of the purposes of the proposed action to 

reduce mainstem trout populations to benefit endangered humpback chub and other native fish in the 

mainstem. 

MITIGATION MEASURES 

To minimize potential impacts on visitor experience, native fish, human safety, and other resources, the 

following measures would be implemented as part of the preferred alternative. 

General Measures 

• Biologists would be sensitive to public perception and be prepared to explain weir and 

electrofishing activities to any visitor who expresses interest. 

• Care would be taken when entering and exiting the creek to minimize impact to streambanks and 

riparian vegetation and wildlife. Unvegetated, stony banks would be used whenever possible to 

minimize erosion. 
Bright Angel Creek Trout Reduction Project Chapter 2 

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• All project personnel would be familiar with and strictly adhere to research permit guidelines and 

limitations. 

• The NPS will conduct discussions and consultations concerning this project with other agencies 

and tribes through multiple venues, including the Glen Canyon Dam Adaptive Management 

Program. Consultation under Section 106 of the NHPA concerning this project with all tribes 

will be completed before a decision is made concerning this project. 

 

• If any cultural resources are discovered during the project, including any ethnographic resources/ 

traditional cultural properties, a park cultural resource specialist will be contacted immediately. 

All work in the immediate vicinity of the discovery will stop until the resources can be identified 

and documented and appropriate consultation and mitigation strategy is developed, if necessary, 

in accordance with the stipulations in the 1995 Programmatic Agreement among the NPS, the 

Arizona State Historic Preservation Officer, and the Advisory Council on Historic Preservation 

regarding the General Management Plan, Environmental Impact Statement, Grand Canyon 

National Park, Arizona. 

 

Fish Handling Measures 

To minimize stress and injury to fish, capture techniques would follow Ward (2002), including: 

• Be respectful of all fish regardless of size and species. 

• Minimize the time that fish are out of the water. 

• Change water [in holding containers] frequently when fish must be held for more than a few 

minutes or if fish surface for air. Remember that handling stress increases as water temperature 

increases. 

• No more than 8-10 fish in a holding container at one time. 

• Watch straps, lapel badges and jewelry can damage fish. 

• Do not hold fish tightly around the throat and avoid touching the gills. 

• Rinse all sunscreen or lotions from hands prior to handling fish. 

• Always wet hands and equipment such as nets and fish boards before use. Dry hands and 

equipment cause damage to fish skin by removing coatings that protect fish from disease. 

Equipment such as length boards and scales become hot in the sun and can damage fish if not 

wetted prior to use. 

Electrofishing Measures 

Electrofishing would be performed in a manner that minimizes harm to native fish and ensures the safety 

of project personnel and the public. 
Bright Angel Creek Trout Reduction Project Chapter 2 

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18 

• All personnel involved in electrofishing would be trained in the safe and proper use of the 

backpack electrofisher to be used (e.g., Smith-Root LR24). The equipment would be kept in 

good working order, and all personnel would wear appropriate protective gear. 

• A temporary sign would be posted at the reach being electrofished, warning people to stay out of 

the creek in that location (the electrical field extends only a few feet from the anode). The sign 

would include a brief explanation of the project. 

• The minimum voltage would be used, sufficient to attract fish, but not enough to injure them. 

Biologists would observe the condition of captured fish. If signs of injury or handling stress are 

noted (dark bands on the body and longer recovery times), the settings for the electrofishing unit 

would be adjusted. 

• Fish would be removed from the electrical field immediately. Each fish would be completely 

revived before releasing it into the live-well. Care would be taken not to crowd fish in the livewell, and holding time would be minimized. Trout would be kept separate from smaller, preysized native fish to avoid predation. 

Other Measures 

• In the unlikely event that a humpback chub (or even more unlikely, a razorback sucker) should be 

captured in the weir, it would be dealt with according to established protocols for handling 

endangered fish in Grand Canyon. If caught, individual endangered fish would be released into 

the creek upstream of the weir after being measured and PIT-tagged (if not already tagged). 

• Project personnel would be instructed not to interact with California condors, bald eagles or 

osprey, and to immediately contact the appropriate Park staff if a condor, bald eagle or osprey 

appears in close proximity to project operations. If a condor, eagle or osprey is observed in the 

area, project personnel will note its behavior and report it to the Park biologist. Fish carcasses 

would be handled in such a way as not to attract condors, eagles or osprey. 

• All project equipment (including personal gear like waders) would be cleaned prior to use to 

ensure that no invasive exotic species are introduced into the project area. Project personnel 

would be instructed to look for non-native New Zealand mudsnails in particular and to ensure that 

none are brought into the area or transported from one location to another. 

CALIFORNIA CONDOR 

• Prior to the start of the project, the park would contact personnel monitoring California condor 

locations and movement to determine condor status in or near the project. 

• If a condor occurs at the project site, operations would cease until it leaves on its own or until 

permitted personnel employ techniques resulting in the condor leaving. 

• Project workers and supervisors would be instructed to avoid interaction with condors and to 

contact the appropriate park or Peregrine Fund personnel immediately if and when condor(s) 

occur at the project site. 

• The project site would be cleaned up at the end of each work day (i.e., trash disposed of, scrap 

materials picked up) to minimize the likelihood of condors visiting the site. Park condor staff may 

complete a site visit to ensure adequate clean-up measures. 

• If condor nesting activity is known within 0.5 mile of the project area, then light and heavy 

construction would be restricted during the active nesting season, if viable nests persist. The 
Bright Angel Creek Trout Reduction Project Chapter 2 

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19 

active nesting season is February 1 to October 15, or until young are fully fledged. These dates 

may be modified based on the most current information, in consultation with the park biologist 

and the USFWS. 

BALD EAGLE 

• Biologist and biological technicians will be instructed to refrain from interacting with any eagles 

that may be present 

• If an eagle is observed in the area, biologists and technicians will notes its behavior and report it 

to the Park biologist. 

• All fish will be disposed of in such a manner as to avoid creating an attractant to eagles. 

HUMPBACK CHUB 

• If any humpback chub or other listed fish species are encountered in the weir or as a result of 

electroshocking, all operations will cease and the Park will reinitiate consultation. 

ENVIRONMENTALLY PREFERRED ALTERNATIVE 

The environmentally preferred alternative is determined by applying the criteria suggested in NEPA and 

further articulated in Council on Environmental Quality (CEQ) guidelines (1981). According to those 

guidelines, “the environmentally preferred alternative is the alternative that will promote the national 

environmental policy as expressed in NEPA’s Section 101.” That policy is to: 

• Fulfill the responsibilities of each generation as trustee of the environment for succeeding 

generations; 

• Assure for all generations safe, healthful, productive, and esthetically and culturally pleasing 

surroundings; 

• Attain the widest range of beneficial uses of the environment without degradation, risk of health 

of safety, or other undesirable and unintended consequences; 

• Preserve important historic, cultural and natural aspects of our national heritage and maintain, 

wherever possible, an environment that supports diversity and variety of individual choice; 

• Achieve a balance between population and resource use that will permit high standards of living 

and a wide sharing of life’s amenities; and 

• Enhance the quality of renewable resources and approach the maximum attainable recycling of 

depletable resources. 

Alternative B (the preferred alternative) is also the environmentally preferred alternative. Overall, it more 

fully meets the above criteria than does Alternative A. Alternative B would meet the project’s purpose 

and objectives to enhance the natural environment of the creek, resulting in beneficial impacts to GRCA’s 

native aquatic resources in both Bright Angel Creek and the Colorado River. It is also expected to benefit 

a federally listed species, the endangered humpback chub, although at a minor or negligible level. 

Alternative A, on the other hand, would proliferate the unnatural aspects of the environment that 

Alternative B seeks to correct, creating adverse effects on the creek’s environment and humpback chub. 
Bright Angel Creek Trout Reduction Project Chapter 3 

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Table 1. Comparative summary of environmental impacts. 

Impact Topic Alternative A - No Action Alternative B – Mechanical Removal 

(Preferred Alternative) 

Aquatic Resources The fish assemblage in Bright Angel Creek 

would continue to be dominated by non-native 

species. Native fish in the creek would be 

adversely affected, directly by continued 

predation and indirectly by competition for 

food resources and possibly habitat. Impacts 

would be moderate, local, and long term. 

Impacts on native fish in the mainstem are 

likely to be minor, direct (predation) and 

indirect (competition), adverse, regional, and 

long term. The intensity of impact would 

likely be minor because the number of trout 

that spawn in the creek appears to be small 

compared to the total trout population in the 

mainstem. 

A more natural native fish assemblage would be 

restored in Bright Angel Creek. These beneficial 

changes to the creek’s natural aquatic ecosystem 

would be moderate, local, and long term (as long as 

the trout reduction program is in place). Impacts on 

non-native trout species in the creek would be 

moderate (not “major” because the impact would be 

largely local) and adverse. Impacts to native fish in 

the mainstem are expected to be minor, direct and 

indirect, beneficial, and regional. Impacts to nonnative trout in the mainstem would be minor, direct, 

adverse, and regional. The duration of these effects 

would depend on the duration of the action. The 

potential impact from capturing (handling and 

electrofishing) native fish would be negligible, direct, 

adverse, local, and short term. Utilization of 

appropriate fish handling and electrofishing protocols 

would mitigate potential adverse impacts. 

Special Status 

Species 

 

Humpback 

Chub 

Current levels of predation by and competition 

with trout would continue, resulting in minor, 

direct, adverse, regional, and long-term impact. 

Fewer trout would be present in the Colorado River 

system to compete with and prey on humpback chub, 

resulting in a minor, indirect, beneficial, and regional 

impact on the species. The duration of the impact 

would depend on the duration of the action. The 

potential effect of capturing a humpback chub in the 

weir would be negligible, direct, adverse, local, and 

short term. Utilization of appropriate fish handling 

protocols would mitigate potential adverse impacts. 

Razorback 

Sucker 

No effect or, at most, a negligible adverse 

effect because individuals are unlikely to be 

present. 

It is unlikely that this species would benefit by a 

reduction in trout in the Bright Angel Creek area 

because individuals are unlikely to be present. The 

remote possibility of capturing a razorback sucker in 

the weir would result in negligible, direct, adverse, 

local, and short-term impacts on the species. 

Utilization of appropriate fish handling protocols 

would mitigate potential impacts. 

Flannelmouth 

Sucker 

Impacts would be the same as for humpback 

chub except more young flannelmouth suckers 

would be present in and near Bright Angel 

Creek and would therefore be more vulnerable 

to predation by trout in that area. 

Impacts would be the same as for humpback chub 

except young flannelmouth suckers are more likely to 

be present in and near Bright Angel Creek and would 

likely receive more beneficial effects from trout 

removal in that area. 

Northern 

Leopard Frog 

Trout may compete with and prey on northern 

leopard frogs if the frogs occur in the Bright 

Angel Creek drainage. Given the uncertainty 

of the frog’s presence, the low population 

number if the frog is present, and the lack of 

information about possible predation by trout, 

this alternative is likely to have no effect or, at 

most, a negligible, direct, adverse, local, and 

short-term effect. 

If this species is present in Bright Angel Creek, the 

reduction of trout may benefit them indirectly by 

increasing the availability of food and reducing 

predation pressure. Effects would be negligible. The 

duration of impact would depend on the duration of 

the action. The impact of electrofishing would likely 

be negligible, direct, adverse, local, and short term. 
Bright Angel Creek Trout Reduction Project Chapter 3 

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21 

Bald Eagle Availability of trout for food in Bright Angel 

Creek and the mainstem would remain at 

current levels, resulting in minor, indirect, 

beneficial, regional, long-term impact. 

The reduction of spawning trout in Bright Angel 

Creek would reduce food availability for bald eagles 

at that location, eventually causing any eagles who 

frequent the area to relocate. The effects would be 

minor, indirect, adverse, and local. The duration of 

impact would depend on the duration of the action. 

The reduction in food availability for bald eagles in 

the mainstem is expected to be negligible. 

Osprey Same as for bald eagle. Same as for bald eagle. 

Visitor Experience No effect. Angling in Bright Angel Creek 

would still be available as a recreational 

opportunity in GRCA. 

The quality of recreational fishing in Bright Angel 

Creek would diminish, reducing recreational 

opportunities at GRCA by a small degree. Few 

visitors to the Park would be aware of the loss of the 

fishery. The impacts to visitor experience at GRCA 

would therefore be minor, indirect, adverse, and local. 

The duration of the impact would depend on the 

duration of the action but is likely to be long term. 

Impacts on the aesthetic qualities of Bright Angel 

Creek and intrusions to visitor experience from project 

operations would be negligible, direct, adverse, and 

short term. 

Table 2. Summary of Alternatives and Extent to Which Each Alternative Meets Project Objectives 

Alternative A – No Action Alternative B – Mechanical Removal (Preferred 

Alternative) 

Trout from the mainstem Colorado River would continue to be 

allowed to spawn in Bright Angel Creek without human 

interference. 

Trout would be mechanically removed from Bright Angel 

Creek using 1) a weir to capture them as they move upstream 

into the creek to spawn, and 2) electrofishing and dip netting 

to capture additional trout in the stream during monitoring of 

fish populations. 

Objective 1: Benefit the endangered humpback chub and other native fish species in the mainstem Colorado River. 

Alternative A: Does not meet objective, as it would continue 

to allow trout to spawn in the creek and serve as predators to 

native fish in the creek and river.

Alternative B: Meets the objective by mechanically reducing 

the number of the non-native predator species, and by not 

allowing the non-native species to spawn in the creek and 

move into the river where they can serve as predators on the 

native species.

Objective 2: Restore and enhance, to the extent possible, the native fish community that once flourished in Bright Angel 

Creek. 

Alternative A: Does not meet objective, as non-native fish 

will continue to spawn and impact the creek ecosystem. 

Alternative B: Meets objective, taking steps to reduce the 

non-native fish in the creek, through mechanical removal, and 

to impede their ability to spawn in the creek. 
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CHAPTER 3 – AFFECTED ENVIRONMENT AND 

ENVIRONMENTAL CONSEQUENCES 

INTRODUCTION 

This chapter describes the present condition (i.e., affected environment) within the project area and the 

changes (i.e., environmental consequences) that can be expected from implementing the proposed action 

or taking no action at this time. The No-Action Alternative (Alternative A) sets the environmental 

baseline for comparing the effects of the proposed action. The environmental effects, or changes from the 

baseline condition, described in this chapter are organized by relevant issue, or impact topic. Impact 

topics define the scope of the environmental concerns for the proposed action; in this case the impact 

topics identified during scoping are Aquatic Resources, Special Status Species, Cultural Resources and 

Visitor Experience (see Chapter 1). 

METHODOLOGY 

The analysis of issues that have been determined relevant and the corresponding conclusions found in this 

chapter are based on information obtained through park staff knowledge of the resources and site, review 

of existing literature and park archives, and professional judgment. As required by NEPA regulations, 

potential impacts associated with an implemented action are described in terms of type (direct, indirect, 

beneficial, adverse), context (site-specific, local, state, or regional), intensity (negligible, minor, moderate, 

or major), and duration (short-term, lasting less than 5 years, or long-term, lasting more than 5 years). 

Because definitions of intensity vary by impact topic, intensity definitions are provided separately for 

each impact topic analyzed in this EA. NEPA regulations also require an evaluation of cumulative 

impacts, and NPS policy requires an evaluation of potential “impairment” of park resources. 

CUMULATIVE IMPACT DEFINITION AND POTENTIAL CONTRIBUTING 

PROJECTS 

Cumulative impact is defined as the impact that results from the incremental effects of the proposed 

action when added to other past, present, and reasonably foreseeable future actions regardless of what 

agency (federal or non-federal) or person undertakes such other actions. Cumulative impacts can result 

from individually minor, but collectively significant actions, taking place over a period of time (40 CFR 

1508.7). Other past, ongoing, or foreseeable future actions that could impact Bright Angel Creek’s 

aquatic community or trout populations in the Colorado River are described below. 

Tamarisk Management and Tributary Restoration. NPS crews are removing tamarisk (Tamarix sp.) 

and other non-native plants from along Bright Angel Creek as part of the Park’s ongoing Tamarisk 

Management and Tributary Restoration Project (Makarick 2004). The purpose of the project is to restore 

more natural conditions in the Park’s side canyons and to prevent any further loss or degradation of the 

existing native animal and plant life by halting the spread of this highly invasive exotic plant (GRCA 

2002a). Eradication methods include manual removal, herbicide lance injection, hack and squirt, cut 

stump, and basal barks herbicide application (see GRCA 2002a for an explanation of these procedures). 

Seeding of native plant species will follow the removal effort. Because of the invasive characteristics of 

tamarisk, and a nearby source of new incursions (tamarisk is well established in the mainstem canyon), it 

is likely that repeated treatments will be needed over time. 

Removing tamarisk may result in a short-term increase in sedimentation (turbidity) in Bright Angel Creek 

due to an increase in soil erosion along the banks of the creek during the period when the tamarisk have 
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been removed and the new native seeds are taking hold (Makarick 2004). Stream flow may increase 

slightly over the long term due to a reduction in water consumption by tamarisk. The Tamarisk 

Management and Tributary Restoration Project underwent NEPA analysis in 2002 (GRCA 2002a), which 

resulted in a Finding of No Significant Impact (GRCA 2002b). 

Upgrade Corridor Area Fire Protection. Construction activities are taking place in Bright Angel 

Canyon as GRCA upgrades the existing water distribution system connected to the transcanyon pipeline. 

Fire protection systems are being added to several structures at Roaring Springs, Cottonwood Camp, and 

Phantom Ranch to diminish the risk of loss from structural fires. Construction activities include some 

trenching in the Phantom Ranch area. No impacts to Bright Angel Creek are anticipated (GRCA 2003a). 

The Upgrade Corridor Area Fire Protection project underwent NEPA analysis in 2003 (GRCA 2003a), 

which resulted in a Finding of No Significant Impact (GRCA 2003b). 

Diversions from Roaring Springs for Consumptive Use. Since 1967, water has been diverted from 

Bright Angel Creek flow (specifically Roaring Springs) to meet the consumptive needs of developed 

areas in GRCA. This water is delivered to the North Rim, Phantom Ranch, Indian Garden, and the South 

Rim by way of the transcanyon pipeline. In 2002, the U.S. Bureau of Reclamation (USBR) estimated that 

a maximum flow of 1.74 cubic feet per second (cfs)2

 was diverted to meet park water demands (USBR 

2002). That depletion represents approximately 5% of Bright Angel Creek’s mean annual flow of 35 cfs. 

Discharge in the creek is highly variable, however, so the percentage of diverted flow also varies, 

amounting to less than 0.4% of discharge for the highest-flow month on record (i.e., 501 cfs in May 1941) 

and more than 13% for the lowest-flow month on record (i.e., 13.2 cfs in July 1972) (Slack et al. 1993). 

Using baseline data from 1999, a water supply appraisal completed in 2002 predicted that water use in the 

Park could double by the year 2050 (USBR 2002). Depletions from Roaring Springs may increase in line 

with these long-term projections; however, changes in demand over short periods is difficult to predict. 

Visitation to GRCA increased by over 700% between 1949 and 1999, but growth is not necessarily linear. 

Visitation actually decreased by over 9% between 1999 and 2003 (NPS data). No significant increase in 

water diversion from Bright Angel Creek is planned at this time. 

The effects of the ongoing depletion of streamflow on Bright Angel Creek’s aquatic ecosystem vary, with 

the potential for impact greatest when runoff is low. Reduced flow results in reduced stream width, 

velocity, and depth, and increased water temperature and specific conductivity. An instream flow habitat 

simulation model run in 1984 indicated that an increase in depletion of up to 30% would have no 

substantial adverse effects on aquatic insects and fish in the creek (Usher et al. 1984). 

Grand Canyon Monitoring and Research Center Trout Reduction Efforts. In January 2003, 

GCMRC began implementing a science plan consisting of 2 years of experimental releases from Glen 

Canyon Dam combined with mechanical removal of trout from a 9.5-mile reach of the Colorado River 

(GCMRC 2003a). One of the purposes of the plan is to improve survival and recruitment in juvenile 

humpback chub by reducing non-native trout populations in the river. The experimental dam-release 

scenarios include non-native fish suppression flows in January-March 2003 and 2004. These high daily 

fluctuating flows (5,000-20,000 cfs) are designed to disrupt trout reproductive activities in the mainstem, 

desiccate eggs and fry, and displace fingerlings. The second component, mechanical removal, calls for 

removing trout by electrofishing between River Mile (RM) 56.2 and RM 65.7, near the LCR confluence. 

Removal efforts consist of six depletion trips each year, three in January-March and three in JulySeptember (Coggins and Yard 2003). Current plans call for a total of 24 depletion trips over 4 years 

(2003-2006). In the three trips conducted in January-March 2003, biologists report removing 6,703 

 

2

 The estimated 1.74 cfs comprises 1.56 cfs for the South Rim, 0.16 cfs for the North Rim, and 0.02 cfs for Phantom Ranch. 

(USBR 2002).
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rainbow trout and 130 brown trout in 355 hours of electrofishing (Coggins and Yard 2003). It is 

premature at this point to evaluate the effects of the effort. The combined program of dam releases and 

trout removal underwent NEPA analysis in 2002, which resulted in a Finding of No Significant Impact 

(DOI 2002). 

Feasibility Study to Determine the Efficacy of Using a Weir in Bright Angel Creek to Capture 

Brown Trout. In November 2002-January 2003, a study was conducted to test the effectiveness of using 

a weir in Bright Angel Creek to capture spawning trout. The study was performed by biologists from 

SWCA Environmental Consultants under contract to the NPS. During the 64 days of weir operation, 423 

brown trout were captured and sacrificed, and 188 rainbow trout were captured and released above the 

weir (SWCA 2003). It is believed that the majority of the brown trout attempting to spawn in Bright 

Angel Creek that winter were intercepted, resulting in a major impact on the aquatic fauna in Bright 

Angel Creek, at least for the short term. The long-term and regional (mainstem) effects are more difficult 

to assess. 

Restoring Native Fish Habitat in Grand Canyon National Park. In February 2004, GRCA initiated a 

2-year feasibility study for non-native fish control in key tributaries (initially Shinumo, Tapeats, and 

Kanab Creeks ) in GRCA. The goal of the project is to determine the potential for restoring native fish 

populations in these streams. Two winter trips are being conducted each year (2004-2005) to survey for 

species composition, distribution, and abundance, and to remove the non-native fish captured during the 

sampling. Abundance estimates will be used to assess the efficiency of non-native fish removal and to 

assess the short- and long-term reinvasion rate of non-native fish. The resulting information will form the 

basis of a management plan for controlling non-native fishes in these, and possibly other, tributaries. 

IMPAIRMENT OF PARK RESOURCES OR VALUES 

The following is quoted from the National Park Service’s Upgrade Corridor Area Fire Protection 

Environmental Assessment (GRCA 2003a): 

In addition to determining the environmental consequences of implementing the alternatives, 

National Park Service policy (Management Policies 2001, §1.4.4) requires analysis of potential 

effects to determine whether actions would impair park resources. 

The fundamental purpose of the national park system, established by the Organic Act and 

reaffirmed by the General Authorities Act, as amended, begins with a mandate to conserve park 

resources and values. National Park Service managers must always seek ways to avoid, or to 

minimize to the greatest degree practicable, adverse impacts on park resources and values. 

However, the laws do give the National Park Service the management discretion to allow 

impacts to park resources and values when necessary and appropriate to fulfill the purposes of 

a park, as long as the impact does not constitute impairment of the affected resources and 

values. Although Congress has given the National Park Service the management discretion to 

allow certain impacts within parks, that discretion is limited by the statutory requirement that 

the National Park Service must leave park resources and values unimpaired, unless a 

particular law directly and specifically provides otherwise. The prohibited impairment is an 

impact that, in the professional judgment of the responsible National Park Service manager, 

would harm the integrity of park resources or values, including the opportunities that otherwise 

would be present for the enjoyment of those resources or values. An impact to any park 

resource or value may constitute impairment. An impact would be more likely to constitute 

impairment to the extent that it affects a resource or value whose conservation is: 
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• necessary to fulfill specific purposes identified in the establishing legislation or proclamation of 

the park; 

• key to the natural or cultural integrity of the park; or 

• Identified as a goal in the park’s general management plan or other relevant NPS planning 

documents. 

Impairment could result from National Park Service activities in managing the park, visitor 

activities, or activities undertaken by concessioners, contractors, and others operating in the 

park. 

The potential for impairment is discussed in the Conclusion section at the end of each impact topic in 

Chapter 3. 

Section 106 of the National Historic Preservation Act 

In this environmental assessment/assessment of effect, impacts to cultural resources are described in 

terms of type, context, duration, and intensity, which is consistent with the regulations of the Council on 

Environmental Quality (CEQ) that implement the National Environmental Policy Act (NEPA). These 

impact analyses are intended, however, to comply with the requirements of both NEPA and §106 of the 

National Historic Preservation Act (NHPA). In accordance with the Advisory Council on Historic 

Preservation’s regulations implementing §106 of the NHPA (36 CFR Part 800, Protection of Historic 

Properties), impacts to historic properties and ethnographic resources were identified and evaluated by (1) 

determining the area of potential effects; (2) identifying cultural resources present in the area of potential 

effects that were either listed in or eligible to be listed in the National Register of Historic Places; (3) 

applying the criteria of adverse effect to affected cultural resources either listed in or eligible to be listed 

in the National Register; and (4) considering ways to avoid, minimize or mitigate adverse effects. 

Under the Advisory Council’s regulations a determination of either adverse effect or no adverse effect 

must also be made for affected National Register eligible cultural resources. An adverse effect occurs 

whenever an impact alters, directly or indirectly, any characteristic of a cultural resource that qualify it for 

inclusion in the National Register (e.g. diminishing the integrity of the resource’s location, design, setting, 

materials, workmanship, feeling, or association). Adverse effects also include reasonably foreseeable 

effects caused by the preferred alternative that would occur later in time, be farther removed in distance or 

be cumulative (36 CFR Part 800.5, Assessment of Adverse Effects). A determination of no adverse effect 

means there is an effect, but the effect would not diminish in any way the characteristics of the cultural 

resource that qualify it for inclusion in the National Register. 

PROJECT AREA 

The proposed project area encompasses Bright Angel Creek and environs in GRCA, Coconino County, 

Arizona (Figure 1). The mouth of the creek is at Latitude 36°06'11", Longitude 112°05'44". A perennial 

stream, Bright Angel Creek originates on the North Rim, drains an area of 101 sq mi, and flows 

approximately 17.6 mi before converging with the Colorado River (Slack et al. 1993, Otis 1994). About 

9 mi upstream of the confluence, a 9-ft waterfall acts as a barrier to upstream movement of fish. Stream 

flow is contributed by: (a) numerous springs, with Angel and Roaring Springs being the largest; (b) four 

perennial tributaries (Phantom, Ribbon, Wall, and Transept Creeks); and (c) one intermittent tributary 

(Manzanita Creek). Discharge averaged 35 cfs over the 50-year period of record (1924-1973) at a U.S. 

Geological Survey (USGS) stream gauge (USGS 2004). Measurements of discharge taken by park 

hydrologists in 1992-1994 averaged 27.8 cfs (GRCA 1994). Elevation of the creek ranges from over 
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8,000 ft on the North Rim; 5,200 ft at Roaring Springs; 4,400 ft at the barrier waterfall; to 2,400 ft at the 

mouth. Bright Angel Creek is considered a moderately high-gradient stream, dropping an average of 421 

ft/mi (Slack et al. 1993). Substrate is heterogeneous, ranging from boulders to silt; however, boulders, 

cobbles, and gravel dominate (Otis 1994). Water quality is dolomitic, with high levels of calcium and 

magnesium and low levels of sulfate. Riparian biotic communities, dominated by cottonwood (Populus 

fremontii), coyote willow (Salix exigua), tamarisk (Tamarix ramosissima), and baccharis (Baccharis

spp.), are found along the creek banks. 

Most activities related to the proposed action would take place in the Phantom Ranch area, near the 

confluence of Bright Angel Creek and the Colorado River. This area is located within the popular CrossCanyon Corridor, a trail system that links the developed area on the South Rim with the developed area 

on the North Rim. Access from either rim is difficult, requiring a descent by foot or mule of 

approximately 5,000 ft elevation change from the South Rim and nearly 6,000 ft from the North Rim. 

The shortest route, the South Kaibab Trail, is about 6.5 miles long. The North Kaibab Trail is about 14 

miles long. Facilities in the Phantom Ranch area include a concession-operated lodge, an NPS 

campground (Bright Angel), a ranger station, sewage treatment plant and various support facilities. 

Together the campground and the lodge can accommodate approximately 170 over-night visitors. A 

second campground (Cottonwood) is located 7 miles north up Bright Angel Canyon from Phantom 

Ranch. 

In addition to Bright Angel Creek, the area of potential impact includes the reach of Colorado River 

within the range of individual fish that also occupy (or could potentially occupy) Bright Angel Creek. 

The delimitations of this reach are not known with any precision, but brown trout and flannelmouth 

sucker, for example, are known to move many miles in a relatively short time, often as a function of 

spawning activity (Valdez and Carothers 1998). It is likely that at least some of the brown trout that 

frequent the LCR inflow area (RM 57.0–RM 65.4; Valdez and Ryel 1994) spawn in Bright Angel Creek; 

therefore, the area of potential effect in the Colorado River is here defined as 30 mi upstream and 30 mi 

downstream of Bright Angel Creek. One of the nine tagged brown trout that were caught in Bright Angel 

creek during the feasibility study was tagged in the mainstem above the Little Colorado River (SWCA 

2003). 

AQUATIC RESOURCES 

Affected Environment 

The aquatic ecosystem of Bright Angel Creek and the Colorado River includes various microscopic 

organisms, diatoms (small attached algae), Cladophora (large filamentous green algae), aquatic 

macroinvertebrates (e.g., midges, blackflies, snails, worms), and fish. Algae are primary producers at the 

base of the aquatic food web, which means they use the energy from sunlight to convert carbon dioxide to 

organic matter (photosynthesis). Primary producers are a source of food for aquatic macroinvertebrates 

and fish, and macroinvertebrates are a food source for fish. Brown and rainbow trout also consume small 

fish as part of their diet. The proportion of algae, aquatic plants, macroinvertebrates, fish, and 

miscellaneous food stuffs and debris that make up a fish’s typical diet varies by species, food availability, 

and other factors. Significant impacts to food web structure can occur when top predators, like brown 

trout, are removed, or when the abundance of fish changes substantially. 
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Native Fish 

The three native fish typically found in Bright Angel Creek are speckled dace, bluehead sucker, 

and flannelmouth sucker. All three species currently share that habitat with non-native species, 

primarily brown and rainbow trout. The flannelmouth sucker is described in the “Special Status 

Species” section; humpback chub, a native species found in the mainstem and the LCR, is also 

described in the “Special Status Species” section. Speckled dace and bluehead sucker are 

described below. 

Speckled Dace. This is a small (up to 4 inches), short-lived species found in the Colorado River 

and in tributaries in GRCA. This species is widely distributed and reported as locally abundant in 

the upper reaches of the Colorado River, particularly in tributary mouths (Valdez and Carothers 

1998). Minckley (1978) reported them from all tributaries he investigated but found that the 

distribution was “essentially the reverse of large rainbow trout.” In one year of monthly sampling 

in Bright Angel Creek (May 1976 through June 1977), Minckley reported speckled dace to be the 

most common species captured (n=246, or 54% of total). Some evidence suggests a marked 

decline in speckled dace abundance in the creek since the 1970s. Otis (1994) recorded very few 

of these fish during the same months when Minckley reported the highest abundances (MarchSeptember). Otis captured only 13 individuals in over 1,000 trap-hours. 

Some speckled dace inhabit tributaries year-round, apparently taking shelter under substrate 

through the winter. Others move into the mainstem in the winter, possibly to avoid large 

aggregations of spawning trout (Minckley 1978, Valdez and Carothers 1998). Its preferred 

habitat is fast moving water over rocky substrate. Spawning occurs in tributaries and possibly the 

mainstem, primarily in April-May. Their diet consists of algae, organic detritus, and small 

macroinvertebrates (Valdez and Carothers 1998). The small size of this fish makes it vulnerable 

to predation even as an adult. 

Bluehead Sucker. Bluehead suckers are generally large (up to 17 inches), long-lived fish. They 

are widely distributed in GRCA but occur only in small numbers. During 1976-1977, bluehead 

suckers accounted for only 7% (n=32) of fish captured in Bright Angel Creek (Minckley 1978). 

Otis (1994) observed five adult and small numbers of larval bluehead suckers in 1992-1993. 

These fish reside in fast moving water over a rocky substrate throughout the Colorado River 

system. They occupy mainstem habitats in GRCA but are more abundant in tributaries and 

tributary inflow areas. Spawning usually occurs from early spring through early summer 

(primarily April-May) in GRCA tributaries, including Bright Angel Creek (Minckley 1978, Otis 

1994). The bluehead sucker is an omnivorous benthic (bottom) feeder, scraping diatoms, algae, 

aquatic invertebrates, and detritus from rocky substrate (Valdez and Carothers 1998). Larval and 

juvenile bluehead suckers are vulnerable to predation by trout. 

Non-native Fish 

Recent studies indicated that two introduced species are common in Bright Angel Creek: brown 

trout and rainbow trout (Otis 1994). Brook trout, cutthroat trout, and cutthroat hybrids have been 

reported in the past as well. In Grand Canyon, trout are found in the mainstem Colorado River 

and in several cold-water tributaries. Based on annual monitoring data, trout populations in the 

system are estimated to have increased four- to six-fold in the last decade (GCMRC data cited in 

USFWS 2002b). Negative interactions between trout and native fish species include predation 

and competition. Predation by brown and rainbow trout has been well documented (see below). 
Bright Angel Creek Trout Reduction Project Chapter 3 

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Competition for resources, including food and habitat (space), is more difficult to document, but 

dietary and habitat overlap does exist between trout and native fish, particularly humpback chub 

(Valdez and Carothers 1998). The overwhelming biomass of trout in the Colorado River may 

exhaust resources and crowd out native fish in some habitats. 

Brown Trout. Brown trout are a large salmonid species (can exceed 20 inches) generally 

associated with cold water habitats. In GRCA, they reside year-round in both the mainstem 

Colorado River and in tributaries, including Bright Angel Creek. The mainstem population is 

more restricted in distribution than rainbow trout, occurring primarily between the RM 62.5 (the 

LCR) and RM 150, with the largest numbers near the Bright Angel Creek inflow (Valdez and 

Ryel 1995, Speas et al. 2003). A recent study estimates their mainstem population at 84,000 

individuals (Speas et al. 2003). Spawning usually occurs in fall to early winter. Brown trout 

prefer to spawn in streams and tributaries, so mainstem reproduction is unlikely. Bright Angel 

Creek is believed to be the primary spawning grounds for brown trout in GRCA, although 

individuals in reproductive condition have been captured in other tributaries, including nearby 

Clear Creek (Valdez and Carothers 1998). The proportion of the total adult brown trout 

population that spawns in Bright Angel Creek is unknown, but 423 brown trout were captured in 

the Bright Angel Creek weir during their spawning run in 2003. 

Aquatic invertebrates usually make up the majority of the food base for brown trout, but these 

fish also consume terrestrial invertebrates, small fish, fish eggs, and Cladophora (Carothers and 

Minckley 1981, Marsh and Douglas 1997). Compared to rainbow trout, brown trout are more 

piscivorous (Valdez and Carothers 1998). Valdez and Ryel (1995) found fish in over 18% of 

brown trout stomachs in mainstem sampling, and Marsh and Douglas (1997) found fish in 20% of 

brown trout stomachs from the LCR. Valdez and Ryel (1995) estimated that 10,000 adult brown 

trout could reasonably consume 759,200 subadult humpback chub annually. 

Brown trout dominate the fish assemblage in Bright Angel Creek (Otis 1994). This is a fairly 

recent development. In 1976-1977, brown trout accounted for only 0.4% of fish captured in 

Bright Angel Creek, while rainbow trout accounted for 39% (Minckley 1978). The remaining 

fish captured were native species. In 1992-1993, brown trout accounted for 81% streamwide 

(Otis 1994). Concurrently, the abundance of native speckled dace in Bright Angel Creek declined 

from common in the 1970s to rare in the 1990s (Otis 1994). Thus, there is a positive correlation 

between the decline in abundance of native speckled dace in Bright Angel Creek and the 

increased dominance of piscivorous brown trout. In the mainstem Colorado River, predation by 

brown trout on the endangered humpback chub is a major management concern. Predation by 

brown trout has been documented, and brown trout numbers are increasing in the reach of river 

where humpback chub are most abundant (Valdez and Ryel 1995). 

Rainbow Trout. Rainbow trout are a large salmonid species (can exceed 20 inches) that prefer 

swift cool water over a silt-free rocky substrate. Like brown trout, rainbow trout are residents of 

both the mainstem Colorado River and suitable tributaries. Spawning usually occurs between late 

fall and early spring, peaking in December-January. Rainbow trout reproduce in the mainstem 

Colorado River and in several cold-water tributaries, including Bright Angel Creek. The 

proportion of the total rainbow trout population that spawn in Bright Angel Creek is unknown, 

but the fact that only 188 rainbow trout were captured in the Bright Angel Creek weir in 

November to mid-January 2003 indicates that the percentage is likely small. In the Colorado 

River system the rainbow trout diet includes Cladophora and diatoms, aquatic invertebrates, 

terrestrial invertebrates, fish, and fish eggs (Valdez and Carothers 1998). GRCA rainbow trout 

are notable for the high occurrence of Cladophora in their diet. 
Bright Angel Creek Trout Reduction Project Chapter 3 

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Rainbow trout is the overwhelmingly dominant fish species in the Colorado River system in 

GRCA, with population estimates between RM 39 and RM 196 of 369,000 individuals (Speas et 

al. 2003). Like brown trout, rainbow trout are known predators on native fishes (Minckley 1978, 

Carothers and Minckley 1981, Maddux et al. 1987, Marsh and Douglas 1997). While their rate of 

predation is generally much lower than that of brown trout, their population size is more than four 

times greater, magnifying the impact. Rainbow trout are opportunistic omnivores (Haden 1992). 

Rates of predation (measured by the occurrence of fish in stomach samples) range from 0.6% in 

the mainstem (Valdez and Ryel 1995) to 16% in the LCR (Marsh and Douglas 1997). Under 

certain conditions, their predation rate can be much higher. In 1970, the diet of rainbow trout 

sampled near Lees Ferry was 66% fish in February and 79% in March (Rathburn 1969). The 

impact of rainbow trout on the native fish community, whether by predation or competition, has 

been documented in Grand Canyon and elsewhere. Speckled dace disappeared from Tapeats 

Creek after rainbow trout were introduced (Miller and Smith 1975). Speckled dace disappeared 

in the fall in Bright Angel Creek due to the presence of spawning rainbow trout (Minckley 1978). 

In Nutrioso Creek in eastern Arizona, predation by rainbow trout on the native Little Colorado 

spinedace was high even in the presence of abundant macroinvertebrate prey (Blinn et al. 1993). 

Researchers found an average of 0.7 spinedace per rainbow trout stomach sampled, and one trout 

was observed to consume four spinedace in 16 hours. 

Environmental Consequences 

Methodology 

The thresholds of change for the intensity of impact on aquatic resources are defined as follows: 

Negligible: Aquatic resources would not be affected or the effects would be at or below the level of 

detection. Changes would be so slight that they would not be measurable or of perceptible 

consequence to aquatic resources. 

Minor: Effects to aquatic resources would be detectable. Effects would be localized and short term. 

There would be little consequence to individuals or populations. Changes to habitat would be short 

term and localized. 

Moderate: Effects to aquatic resources would be readily detectable, localized, and long term, or 

larger scale for short term. There would be consequences to populations. 

Major: Effects to aquatic resources would be obvious, long term, and regional. Substantial 

consequences to populations would occur. 

Alternative A – No Action 

Under this alternative current conditions and trends in species composition, distribution, and abundances 

of aquatic organisms in Bright Angel Creek and adjacent reaches of the Colorado River would continue. 

Non-native trout, particularly brown trout, would continue to dominate the fish assemblage in Bright 

Angel Creek. This would disadvantage native fish in the creek directly by continued predation and 

indirectly by competition for food resources and possibly habitat. The native food web structure 

(including native organisms other than fish) in the aquatic ecosystem would continue to be impacted by 

the dominance of the non-native species. These adverse impacts would be moderate in intensity, local in 

context, and long term in duration. 
Bright Angel Creek Trout Reduction Project Chapter 3 

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Trout spawned in the creek would continue to contribute to predation and competition pressures on native 

fish in the mainstem. Effects would be minor, direct (predation) and indirect (competition), adverse, 

regional, and long term. The intensity of impact would likely be minor because the number of trout that 

spawn in the creek appears to be small compared to the total trout population in the river (i.e., within 30 

mi both upstream and downstream of the Bright Angel Creek inflow). 

There would be no removal of non-native species (i.e., trout), so no adverse impacts to those species. 

Cumulative Impacts 

The combined past, present, and future non-native trout reduction programs in GRCA may result in a 

moderate, indirect, beneficial, and regional effects on native fish in the Colorado River. Most of that 

impact would be attributable to dam operations, which have the potential to disrupt trout spawning on a 

broad scale, and to mechanical trout removal in the mainstem by GCMRC. The impact of dam operations 

is unknown at this time, but GCMRC’s trout reduction program succeeded in removing 6,833 trout from 

the mainstem in 2003. This compares to 611 trout caught in the weir at Bright Angel Creek, also in 2003. 

Potential adverse cumulative effects of handling native fish would be negligible because uniform 

protocols would be applied in all actions to minimize stress and injury to individual fish. These impacts 

would be local and short term. Ongoing water diversions for consumptive use, tamarisk removal, and 

current construction work in Bright Angel Canyon are not expected to contribute significantly to 

cumulative impacts on aquatic resources addressed in this EA. 

Alternative B – Mechanical Removal (Preferred Alternative) 

Substantially reducing the population of brown and rainbow trout in Bright Angel Creek would affect the 

food base in the stream. Brown trout consume large numbers of macroinvertebrates. Removing that 

predatory species is expected to result in an increase in macroinvertebrate populations, including aquatic 

insects like midges and blackflies (Townsend 1996). Due to an increase in macroinvertebrates that graze 

on algae, the abundance of algae and macrophytes (aquatic plants) would likely decrease, at least in the 

short term. 

Under this alternative, the abundance of non-native brown and rainbow trout in Bright Angel Creek 

would decrease significantly. Based upon the 2002 feasibility study and 2006 population study (SWCA 

2002 and 2006), several hundred non-native trout may be removed annually (a moderate intensity adverse 

impact on those species because impacts would be largely local, and affect a very small percentage of the 

trout population in the Colorado River; also see discussion of cumulative impacts for Alternative B 

below). The reduction of spawning trout in the winter would be noticeable immediately. The resident 

populations of trout in the upstream reaches of the creek would be reduced more gradually with repeated 

electrofishing operations. In the absence of predation and competition from trout, populations of resident 

native fish (speckled dace and bluehead suckers) are expected to increase over time. Eventually, native 

fish species would once again dominate the Bright Angel Creek aquatic environment, and other 

components of the system (primary producers and macroinvertebrates) would adjust to the evolving 

changes. Impacts on Bright Angel Creek’s natural ecosystem values, including native fish species, would 

be moderate, direct and indirect, beneficial, and local. Impacts on non-native trout species would be 

moderate (because the impact would be largely local) and adverse. The duration of the impact would 

depend on the duration of the action. If the trout reduction program is terminated, non-native trout would 

eventually re-invade from the mainstem, and the system would revert to existing conditions. 
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With the reduction of trout spawning in Bright Angel Creek, predation and competition pressures would 

be reduced on native fish in the mainstem, including the young bluehead suckers and flannelmouth 

suckers spawned in Bright Angel Creek. With fewer trout in the inflow area and for several miles 

upstream and downstream, early life stages of these fish (from eggs to juveniles) should have an increased 

survival rate. (See also discussions of effects on humpback chub and flannelmouth sucker in the “Special 

Status Species” section below.) Impacts to native fish in the mainstem are expected to be minor, direct 

(predation) and indirect (competition), beneficial, and regional. The duration of the impact would depend 

on the duration of the action. 

Bluehead suckers would be captured, processed (measured and tagged), and released at the weir during 

the spring spawning run. They are also likely to be captured by electrofishing during the population 

surveys. To minimize potential stress and injury to the fish from either handling or electrofishing, 

established protocols would be followed (see fish handling and electrofishing procedures in the 

“Mitigation Measures” section of Chapter 2). The potential impact from handling bluehead suckers (and 

any other large native fish) would be negligible, direct, adverse, local, and short term. 

Cumulative Impacts 

The combined past, present, and future non-native trout reduction programs in GRCA may result in a 

moderate, indirect, beneficial, and regional effects on native fish in the Colorado River. Most of that 

impact would be attributable to dam operations, which have the potential to disrupt trout spawning on a 

broad scale, and to mechanical trout removal in the mainstem by GCMRC. The impact of dam operations 

is unknown at this time, but GCMRC’s trout reduction program succeeded in removing 6,833 trout from 

the mainstem in 2003. This compares to 611 trout caught in the weir at Bright Angel Creek, also in 2003. 

Potential adverse cumulative effects of handling native fish would be negligible because uniform 

protocols would be applied in all actions to minimize stress and injury to individual fish. These impacts 

would be local and short term. Ongoing water diversions for consumptive use, tamarisk removal, and 

current construction work in Bright Angel Canyon are not expected to contribute significantly to 

cumulative impacts on aquatic resources addressed in this EA. 

Conclusions 

Alternative A - No Action. Under this alternative, the fish assemblage in Bright Angel Creek would 

continue to be dominated by non-native species, particularly brown trout. Allowing trout to continue to 

spawn in Bright Angel Creek and to dominate the creek’s ecosystem is expected to adversely affect native 

fish in the creek, directly by continued predation and indirectly by competition for food resources and 

possibly habitat. These adverse impacts would be moderate, local, and long term. Impacts on native fish 

in the mainstem are likely to be minor, direct (predation) and indirect (competition), adverse, regional, 

and long term. The intensity of impact would likely be minor because the number of trout that spawn in 

the creek appears to be small compared to the total trout population in the area. 

Because there would be no major, adverse impacts to a resource or value whose conservation is (1) 

necessary to fulfill specific purposes identified in the establishing legislation or proclamation of GRCA; 

(2) key to the natural or cultural integrity of the Park or to opportunities for enjoyment of the Park; or (3) 

identified as a goal in the Park’s general management plan or other relevant NPS planning documents, 

there would be no impairment of the Park’s resources or values. 

Alternative B – Mechanical Removal (Preferred Alternative). This alternative is expected to restore 

more natural abundances of native fish species (particularly speckled dace and bluehead sucker) in Bright 

Angel Creek. These beneficial changes to the creek’s natural aquatic ecosystem would be moderate in 
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intensity (i.e., readily detectable, localized, and long term as long as the trout reduction program is in 

place). The effects on non-native trout in Bright Angel Creek would be moderate (because local) and 

adverse. Impacts to native fish in the mainstem are expected to be minor, direct (predation) and indirect 

(competition), beneficial, and regional. Impacts to non-native trout in the mainstem would be minor, 

adverse, and regional. The duration of the impact would depend on the duration of the action. The 

potential impact from capturing bluehead suckers (and any other large native fish) would be negligible, 

direct, adverse, local, and short term. 

Because there would be no major, adverse impacts to a resource or value whose conservation is (1) 

necessary to fulfill specific purposes identified in the establishing legislation or proclamation of GRCA; 

(2) key to the natural or cultural integrity of the Park or to opportunities for enjoyment of the Park; or (3) 

identified as a goal in the Park’s general management plan or other relevant NPS planning documents, 

there would be no impairment of the Park’s resources or values. 

SPECIAL STATUS SPECIES 

Affected Environment 

Six special status species either are known to occur or may occur in the project area and have the potential 

to be affected by the proposed action (Table 3). 

Table 3. Special status species either known to occur or may occur in the project area and have the potential to 

be affected by the proposed action. 

Common Name Scientific Name Status Project Vicinity Occurrence 

Humpback chub Gila cypha E, WSCA Occurs in the Colorado River, including the Bright 

Angel Creek inflow area. May occur in Bright 

Angel Creek. 

Razorback sucker Xyrauchen 

texanus 

E, WSCA May occur in the Colorado River and in Bright 

Angel Creek. May be extirpated. 

Flannelmouth sucker Catostomus 

latipinnis 

SC Occurs in the Colorado River. Spawns in Bright 

Angel Creek in the spring. 

Northern leopard frog Rana pipiens WSCA May occur in Bright Angel Canyon. 

Bald eagle Haliaeetus 

leucocephalus

T In winter, forages along the Colorado River and 

tributaries, including Bright Angel Creek. 

Osprey Pandion 

haliaetus 

WSCA In winter, forages along the Colorado River and 

tributaries, including Bright Angel Creek. 

Key: E = federally listed as endangered under the Endangered Species Act (ESA); T = federally listed as threatened under the 

ESA; SC = not federally or state listed but considered a Species of Concern by the USFWS; WSCA = listed as Wildlife of 

Special Concern in Arizona by the AGFD. 

Humpback Chub 

The humpback chub was federally listed as endangered in 1967 (32 FR 4001), with critical habitat 

designated in 1994 (59 FR 13374). In Grand Canyon, critical habitat extends from about RM 35 to about 

RM 209. This species is also listed as WSCA. Ten aggregations have been identified in Grand Canyon 

(Valdez and Ryel 1995). The two largest are in the LCR and in the mainstem near the LCR inflow (RM 

57.0-65.4). A small aggregation is located in the Bright Angel Creek inflow area (RM 83.8-92.2). Only 

one humpback chub record exists for Bright Angel Creek (“near Phantom Ranch”), but Miller (1946) 
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presumed the fish was caught in the Colorado River at or near the mouth of Bright Angel Creek. 

Population estimates made in 2001-2002 for the humpback chub aggregations in and near the LCR 

indicate a significant decline in numbers over the last decade (Van Haverbeke and Coggins 2003, Van 

Haverbeke 2003). GCMRC biologists (2003b) have estimated that the current spawning population is 

probably somewhere between 2,000 and 4,000 age-4 and older fish, possibly a 50% decline since 1990. 

Cited threats to the species include habitat modification, predation by and competition with non-native 

fish species, and parasitic infestation (GCMRC 2003b). Adult humpback chub can reach 20 inches in 

length, and are unlikely to be preyed upon by trout; however, emergent fry, young-of-year, and juvenile 

chub are susceptible to predation in the LCR and the mainstem. 

Humpback chub inhabit the Colorado River and its larger tributaries in canyon-bound reaches 

characterized by deep, swift currents and rocky substrates. Larvae and juvenile fish prefer shallow, lowvelocity nearshore habitats. In Grand Canyon, most humpback chub spawn in the LCR in the spring 

(March-May). Diet consists primarily of aquatic insects, Gammarus (freshwater shrimp), Cladophora, 

Hymenoptera (wasps), cladocerans (water fleas), and detritus (Valdez and Carothers 1998). Adult 

humpback chub feed primarily on suspended material (drift) entrained in eddies, and juveniles favor local 

shoreline production in more sheltered habitats. 

Razorback Sucker 

The razorback sucker was listed as endangered in 1991 (56 FR 54957); critical habitat was designated in 

1994 (59 FR 13374). In Grand Canyon, critical habitat extends from about RM 0 (the Paria River) to 

Hoover Dam. This species is also listed as WSCA. In the lower Colorado River basin, razorback suckers 

are now restricted to Lakes Mohave and Mead, and possibly to the Colorado River and tributaries in 

Grand Canyon. This species is extremely rare in Grand Canyon, with only 10 individuals recorded 

between 1944 and 1990, all adults (Valdez and Carothers 1998). Four of these records were from Bright 

Angel Creek: one fish caught in 1944, and three observed in 1987. No wild razorback suckers have been 

recorded in Grand Canyon since 1990, and the species is likely extirpated or nearly extirpated from the 

area. In 1997, 15 hatchery-raised razorback suckers were released by the Hualapai Tribe into the 

Colorado River at three locations in lower Grand Canyon (Zimmerman and Leibfried 1997). They did 

not persist in the area. 

Razorback suckers prefer slower current and are found in backwaters, side channels, flooded bottomlands, 

pools, and lakes in the Colorado River drainage (AGFD 2002a). No evidence of reproduction in Grand 

Canyon has been recorded. Diet consists primarily of aquatic insect larvae, planktonic crustaceans, 

diatoms, Cladophora, and detritus filtered from bottom sediments. 

Flannelmouth Sucker 

The flannelmouth sucker is considered a species of concern by the USFWS. It is found in the mainstem 

throughout Glen and Grand Canyons and in most of the tributaries, including the Paria River, the Little 

Colorado River (LCR), Bright Angel Creek, Kanab Creek, Shinumo Creek, and Havasu Creek (Valdez 

and Carothers 1998). Tributaries and confluence areas have generally had higher densities of this species 

than the mainstem (Valdez and Ryel 1995). The canyon-wide population of flannelmouth suckers is 

relatively stable (Valdez and Carothers 1998). Predation by rainbow trout on flannelmouth suckers has 

been documented (Marsh and Douglas 1997). Adult suckers can reach 20 inches in length, and are 

unlikely to be preyed upon by trout; however, emergent fry, young-of-year, and juvenile suckers are 

susceptible to predation in spawning tributaries and the mainstem. 
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Flannelmouth suckers typically inhabit shallow, sheltered shorelines as young-of-year and juveniles, and 

the lower end of large, mid-channel cobble riffles in large rivers as adults (Valdez and Carothers 1998). 

Spawning generally occurs March-July and has been reported from the Paria River, the LCR, and 

Shinumo, Bright Angel, Kanab, Havasu, Spencer, and Surprise Canyon Creeks (Otis 1994, Valdez and 

Carothers 1998, AGFD 2001). Mainstem spawning also occurs in the tailwaters of Glen Canyon Dam 

(apparently unsuccessful because of cold water temperatures) and in western Grand Canyon (AGFD 

1996, McKinney et al. 1999). Adult flannelmouth enter Bright Angel Creek only to spawn, remaining in 

the creek 3-6 weeks before returning to the mainstem (Otis 1994). Larval flannelmouth suckers drift 

quickly into the mainstem (Valdez and Carothers 1998). They may also fall prey to trout and other nonnative predators while still in the tributary (Otis 1994). The flannelmouth sucker is predominantly a 

benthic (bottom) feeder, consuming a variety of plant and animal matter (midges, blackflies, Gammarus, 

diatoms, Cladophora, seeds, and organic detritus) it scoops up from bottom sediments. 

Northern Leopard Frog 

The northern leopard frog is listed as WSCA. A few adult frogs and tadpoles have been recorded from at 

least half a dozen sites along the Colorado River or in tributaries between Glen Canyon Dam and Lake 

Mead (Ward 2004). These sites include one in the Bright Angel Creek drainage. Recent surveys 

conducted in 2004 failed to discover Northern Leopard frogs in the Bright Angel Creek drainage (Ward 

2004). Northern leopard frogs utilize springs, streams, and ponds as well as moist terrestrial habitat. 

Breeding takes place in March-May; eggs are deposited on submerged vegetation in shallow water, and 

tadpoles transform to frogs in June-August (Miller et al. 1982). Adult frogs consume small invertebrates; 

tadpoles and froglets feed mostly on algae and other aquatic plants (AGFD 2002b). Predators on the 

species in Grand Canyon likely include fish (including trout), snakes, skunks, and herons. 

Bald Eagle 

The bald eagle was listed as endangered in 1967 (32 FR 4001). In 1995, it was reclassified as threatened 

in the lower 48 states (60 FR 35999), and in 1999, it was proposed for delisting (64 FR 26453). This 

species is also listed as WSCA. Bald eagles do not nest in Grand Canyon, but they are frequent winter 

residents along the Colorado River and in tributaries. Their abundance has been correlated with the 

abundance of spawning trout in Nankoweap Creek (Brown et al. 1989, Brown and Stevens 1992). 

Biologists have conjectured that bald eagles may not have regularly wintered in Grand Canyon until 

increased rainbow trout populations attracted these birds in the mid-1980s (Brown et al. 1989). No 

information is available for the abundance and distribution of bald eagles along the Colorado River in 

Grand Canyon before construction of Glen Canyon Dam; however, this species was not present in early 

post-impoundment winter surveys. The first bald eagles were seen in 1985 at the mouth of Nankoweap 

Creek. At least one bald eagle has been observed recently in Bright Angel Canyon (GRCA 2003a, 

SWCA 2003). While both native and non-native fish probably provide food for bald eagles in Grand 

Canyon, the aggregations of spawning trout are likely the chief source. Bald eagles are unlikely to be 

present in Grand Canyon during the spring when aggregations of native fish spawn. 

Osprey 

The osprey is listed as WSCA by the AGFD. Ospreys winter sparingly along Colorado River in Grand 

Canyon but do not nest there (AGFD 2002c). They have been observed in Bright Angel Canyon during 

the trout spawn (SWCA 2003). Ospreys feed almost exclusively on fish but are also known to prey on 

frogs, snakes, and ducks. 
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Environmental Consequences 

Methodology 

The thresholds of change for the intensity of impact on special status species are defined as follows: 

Negligible: An action that could result in a change to a population or individuals of a species or 

designated critical habitat, but the change would be so small that it would not be of any measurable 

or perceptible consequence. For federally listed species, negligible effect would equate with a “no 

effect” determination in USFWS terms. 

Minor: An action that could result in a change to a population, individuals of a species, or 

designated critical habitat. The change would be measurable but small and localized and of little 

consequence. For federally listed species, an adverse minor effect would equate with a “may effect, 

likely to adversely effect the species of critical habitat”. A beneficial minor effect would equate to 

“may effect, not likely to adversely affect” the species or critical habitat. 

Moderate: An action that would result in some change to a population or individuals of a species or 

designated critical habitat. The change would be measurable and of consequence. For federally 

listed species, an adverse moderate effect would equate with a “may effect, likely to adversely effect 

the species or critical habitat”. A beneficial moderate effect would equate to “may effect, not likely 

to adversely affect” the species or critical habitat. 

Major: An action that would result in a noticeable change to a population or individuals of a species 

or resource or designated critical habitat. For federally listed species, an adverse major effect would 

equate with a “may effect, likely to adversely effect the species or critical habitat” or a jeopardy 

opinion. A beneficial major effect would equate to “may effect, not likely to adversely affect” the 

species or critical habitat. 

Alternative A – No Action 

Humpback Chub. Under the No Action Alternative, humpback chub would continue to be subject to 

current levels of predation by and competition with brown and rainbow trout spawned in Bright Angel 

Creek. Because humpback chub rarely occur in Bright Angel Creek, effects to this species would be felt 

in the mainstem and perhaps within the LCR. Both brown and rainbow trout would continue to exert 

predation and competitive pressures on humpback chub in the Bright Angel Creek Inflow Aggregation. 

Trout (particularly rainbow trout) and humpback chub compete for food resources, relying heavily on 

macroinvertebrates (aquatic insects in particular) in drift, Gammarus, and Cladophora (Valdez and 

Carothers 1998). Brown trout move greater distances than rainbow trout and may pose a threat to 

humpback chub in the LCR area. 

The impact on humpback chub of allowing trout to continue to spawn in Bright Angel Creek would be 

minor in intensity, direct (predation) and indirect (competition), adverse, regional, and long term. The 

intensity of impact would likely be minor because the number of trout that spawn in the creek appears to 

be small compared to the total trout population in the area (see discussion under Aquatic Resources

above). 
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Razorback Sucker. Because of the extreme rarity of razorback suckers in Grand Canyon, and the 

unlikelihood that young razorback suckers small enough to be susceptible to predation are present 

anywhere near Bright Angel Creek, it is unlikely that No Action would have any effect on this species. If 

any individual razorback suckers do persist in the area, they would be large adults and invulnerable to 

predation. At most, adverse impacts would be negligible. 

Flannelmouth Sucker. Like humpback chub, flannelmouth sucker is primarily a resident of the 

mainstem, but unlike humpback chub it also spawns in Bright Angel Creek. Under this alternative, 

resident trout in the creek would continue to pose a threat to young suckers as they hatch and drift to the 

mainstem. The degree to which predation is likely to occur is unknown. It is known, however, that trout 

prey upon young flannelmouth suckers elsewhere in the system (Marsh and Douglas 1997). Potential 

impacts of this alternative on this species would be similar to those on humpback chub. 

Northern Leopard Frog. Under the No Action Alternative, if northern leopard frogs occur in the Bright 

Angel Creek drainage, trout may compete with them for food (algae and small invertebrates). Trout, 

particularly brown trout, may also prey on frog eggs, larvae, and tadpoles. Given the uncertainty of the 

frog’s presence, however, and the low population number if the species is present, as well as the lack of 

information about possible predation by trout, this alternative is likely to have no effect or, at most, a 

negligible, direct, adverse, local, and long-term effect on the species. 

Bald Eagle. Under this alternative, small numbers of bald eagles (apparently only one in recent years) 

would continue to visit Bright Angel Creek in the winter to feed on spawning trout. The number of trout 

available as food for bald eagles in Bright Angel Creek and the mainstem would not diminish as a result 

of this alternative. The impacts of No Action would be indirect, beneficial, regional, and long term. 

Given the relatively small number of trout that spawn in Bright Angel Creek compared to the total 

biomass of trout in the area, the intensity of impact on this species of allowing the spawn to continue 

would be minor at best. 

Osprey – The impacts of this alternative on ospreys would be similar to those on bald eagles. 

 

Cumulative Impacts 

The combined past, present, and future non-native trout reduction programs in GRCA may result in a 

moderate, indirect, beneficial, and regional effect on humpback chub and flannelmouth sucker. Most of 

that impact would be attributable to dam operations and mechanical trout removal in the mainstem (see 

the Cumulative Impact discussion under “Aquatic Resources” above). Potential adverse cumulative 

effects of handling humpback chub and flannelmouth sucker would be negligible because uniform 

protocols would be applied in all actions to minimize stress and injury to individual fish. These impacts 

would be local and short term. Potential cumulative effects, both beneficial and adverse, on razorback 

sucker and northern leopard frog would be negligible at most, local, and short term. The cumulative 

effect of trout reduction efforts on the bald eagle and osprey are likely to be minor in the vicinity of the 

LCR and Bright Angel Creek, with the GCMRC program accounting for most of the impact. The EA for 

that program predicted the long-term impacts on bald eagles to be “measurable,” no more. The Bright 

Angel Creek reduction effort, being of much smaller scale, would add little to the cumulative adverse 

effects on these species. 

Water diversions for consumptive use, tamarisk removal, and current construction work in Bright Angel 

Canyon would not contribute to cumulative impacts on any special status species addressed in this EA. 
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Alternative B – Mechanical Removal (Preferred Alternative) 

Humpback Chub. Under Alternative B, fewer trout would be present in the Colorado River system to 

prey on and compete with humpback chub. This is expected to increase the survivorship of young 

humpback chub in the mainstem (and possibly the LCR), resulting in a potential minor, direct (predation) 

and indirect (competition), beneficial, regional impact on the species. The duration of the impact would 

depend on the duration of the action. If the trout persist in the mainstem, they will eventually resume 

spawning in Bright Angel Creek if the weir operation is terminated. 

Individual humpback chub may enter the weir and be subjected to handling. In that event, established 

protocols would be followed to minimize stress and injury to the fish (see fish handling procedures in the 

“Mitigation Measures” section of Chapter 2). Humpback chub are not expected to be far enough 

upstream in Bright Angel Creek to be affected by electrofishing operations. The potential impact from 

capturing a humpback chub in the weir would be negligible, direct, adverse, local, and short term. 

Razorback Sucker. Because of the extreme rarity of razorback suckers in Grand Canyon, it is unlikely 

that a reduction in trout populations would affect the species. There is a remote possibility that an 

individual adult razorback sucker may enter the weir. In that event, established protocols would be 

followed to minimize stress and injury to the fish. Any potential impact would be negligible, direct, 

adverse, local, and short term. 

Flannelmouth Sucker. The reduction of trout in both Bright Angel Creek and the mainstem would 

benefit flannelmouth suckers by decreasing predation pressures. This may be particularly beneficial for 

emergent fry and drifting larval suckers in the creek and in the Bright Angel inflow area. The resulting 

potential impact would be minor, indirect, beneficial, and regional. As with humpback chub, the duration 

of impact would depend on the duration of the action. 

Flannelmouth suckers would be captured, processed, and released at the weir during the spring spawning 

run. They may also be captured by electrofishing during the depletion surveys. To minimize potential 

stress and injury to the fish from handling and electrofishing, established protocols would be followed 

(see fish handling and electrofishing procedures in the “Mitigation Measures” section of Chapter 2). The 

potential impact from capturing flannelmouth suckers would be negligible, direct, adverse, local, and 

short term. 

Northern Leopard Frog. If northern leopard frogs are present in Bright Angel Creek, the reduction of 

trout in the stream may benefit them by increasing the availability of food and reducing predation 

pressure. These potential beneficial effects would be negligible and indirect. The duration of impact 

would depend on the duration of the action. If northern leopard frogs are present in water being 

electrofished, they may be immobilized. If so, they would be removed immediately from the influence of 

the electrical field and transported to similar habitat outside the depletion reach. Hypothetically, injury 

may occur to an adult frog’s vertebral column because such injury has been observed in fish. However, 

injuries in fish have been correlated with large fish size and the high amperage of boat electrofishers 

(Sharber et al.). Injuries are not expected to be an issue for small animals like leopard frogs, especially at 

the low amperage levels generated by a backpack electrofisher. Electrofishing is an accepted method for 

amphibian surveys, and no spinal injuries have been documented in these animals (USFWS no date). If 

northern leopard frogs are present in Bright Angel Creek, the potential impact of electrofishing and 

handling would be negligible, direct, adverse, local, and short term. 
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Bald Eagle. Under this alternative, trout would become increasing unavailable in Bright Angel Creek as 

a food source for the small number of bald eagles (apparently only one in recent winters) that have been 

observed near the mouth of the creek. Some trout would continue to be available below the weir, 

probably in decreasing numbers each year. The bald eagle(s) accustomed to visiting Bright Angel Creek 

would have ample time to find more productive fishing sites elsewhere within Grand Canyon. The 

potential impact on bald eagles at Bright Angel Creek would be minor, indirect, adverse, and local. The 

duration of impact would depend on the duration of the action. 

Alternative B would also reduce trout abundance to some degree in the river reach several miles upstream 

and downstream of the Bright Angel confluence, thus reducing available food for bald eagles in that area. 

The magnitude of that reduction is unknown with any precision at this time, but it is expected to be a 

small percentage of the total trout population (see the discussion of impacts on non-native fish in the 

“Aquatic Resources” section above). Because this alternative is expected to reduce the overall biomass of 

trout in the Colorado River system by only a small percentage, the reduction in food availability for bald 

eagles in the mainstem is expected to be negligible. 

Osprey. The impacts of this alternative on ospreys would be similar to those on bald eagles. 

Cumulative Impacts 

The combined past, present, and future non-native trout reduction programs in GRCA may result in a 

moderate, indirect, beneficial, and regional effect on humpback chub and flannelmouth sucker. Most of 

that impact would be attributable to dam operations and mechanical trout removal in the mainstem (see 

the Cumulative Impact discussion under “Aquatic Resources” above). Potential adverse cumulative 

effects of handling humpback chub and flannelmouth sucker would be negligible because uniform 

protocols would be applied in all actions to minimize stress and injury to individual fish. These impacts 

would be local and short term. Potential cumulative effects, both beneficial and adverse, on razorback 

sucker and northern leopard frog would be negligible at most, local, and short term. The cumulative 

effect of trout reduction efforts on the bald eagle and osprey are likely to be minor in the vicinity of the 

LCR and Bright Angel Creek, with the GCMRC program accounting for most of the impact. The EA for 

that program predicted the long-term impacts on bald eagles to be “measurable,” no more. The Bright 

Angel Creek reduction effort, being of much smaller scale, would add little to the cumulative adverse 

effects on these species. 

Water diversions for consumptive use, tamarisk removal, and current construction work in Bright Angel 

Canyon would not contribute to cumulative impacts on any special status species addressed in this EA. 

Conclusions 

Alternative A - No Action. This alternative is expected to adversely affect humpback chub and 

flannelmouth sucker by continuing and probably increasing predation and competition pressures from the 

trout that spawn in Bright Angel Creek. Effects would be minor and more likely felt in the mainstem 

Colorado River than in the creek. If northern leopard frogs are present in Bright Angel Creek, No Action 

may adversely affect them for the same reason, although impacts would be negligible at most and 

confined to the creek. Bald eagle and osprey would benefit from the continuing and probably increasing 

availability of trout as prey. 

Because there would be no major, adverse impacts to a resource or value whose conservation is (1) 

necessary to fulfill specific purposes identified in the establishing legislation or proclamation of GRCA; 
Bright Angel Creek Trout Reduction Project Chapter 3 

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(2) key to the natural or cultural integrity of the Park or to opportunities for enjoyment of the Park; or (3) 

identified as a goal in the Park’s general management plan or other relevant NPS planning documents, 

there would be no impairment of the Park’s resources or values. 

Alternative B – Mechanical Removal (Preferred Alternative). This alternative is expected to benefit 

humpback chub and flannelmouth sucker by reducing predation and competition pressures from the trout 

that spawn in Bright Angel Creek. These effects would be minor and more likely felt in the Colorado 

River than in the creek, with the duration of the impact depending on the duration of the action. The 

potential adverse impact of capturing individual humpback chub, flannelmouth sucker, or razorback 

sucker in the weir would be negligible and short term. Utilization of appropriate fish handling protocols 

would mitigate the impact. Northern leopard frog may benefit from an increase in food availability and 

reduction in predation pressure, but effects are likely to be negligible. The potential adverse impact of 

electrofishing would likely be negligible as well. Bald eagles and ospreys may be adversely affected to a 

minor degree as a result of fewer trout being available for food, particularly in the Bright Angel Creek 

inflow area during the spawn. The duration of impact would depend on the duration of the action. The 

reduction in food availability for bald eagles and ospreys in the mainstem is expected to be negligible. 

Impacts under the Preferred Alternative are primarily beneficial. Because there would be no major, 

adverse impacts to a resource or value whose conservation is (1) necessary to fulfill specific purposes 

identified in the establishing legislation or proclamation of GRCA; (2) key to the natural or cultural 

integrity of the Park or to opportunities for enjoyment of the Park; or (3) identified as a goal in the Park’s 

general management plan or other relevant NPS planning documents, there would be no impairment of 

the Park’s resources or values. 

CULTURAL RESOURCES

Affected Environment

Historic Properties

The project occurs within the Cross Canyon Corridor Historic District. The corridor trails were used 

prehistorically and pass very near many archeological sites of varying size and importance. The trails 

have been surveyed for archeological resources but these surveys are of poor quality. Archeological sites 

near trails often receive some of the greatest impacts from erosion and illicit collection. Phantom Ranch 

contains one well-studied pueblo with a number of features, and human burials have been found nearby. 

The Cross Canyon Corridor Historic District includes 44 buildings and structures and the Bright Angel, 

South Kaibab, North Kaibab and connecting river trails. The Phantom Ranch complex along Bright Angel 

Creek consists of approximately 20 buildings used by both the park concessionaire (Xanterra Parks and 

Resorts) and NPS. The five original stone buildings designed by Mary Jane Colter and constructed in 

1922 comprise the heart of the complex, but several other structures (cabins, dining hall, shower building, 

etc.) contribute to the integrity of the area. Bright Angel Campground is the site of the 1920’s Civilian 

Conservation Corps (CCC). The Transcanyon Telephone Line District is about 18 miles long and 

roughly parallels the Bright Angel and North Kaibab Trails from the South Rim to Roaring Springs, with 

a spur line running 2 miles up the South Kaibab Trail. The line consists of almost 600 metal poles strung 

with copper-weld wire. The poles were installed in 1935, with some modifications made in 1938-1939 to 

provide the Park Service with its own telephone system. 
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These archeological and historic resources are adjacent to but not within the area of potential 

effect, and will not be affected by this project. Therefore, they will not be evaluated further in this 

chapter. 

The Phantom Ranch area has not yet been evaluated as a potential cultural landscape, but the project 

would not affect it if it were found to be eligible for that designation. Therefore, cultural landscapes 

will also not be evaluated further in this chapter. 

Ethnographic Resources 

Ethnographic resources are defined by the NPS as any “site, structure, object, landscape, or natural 

resource feature assigned traditional, legendary, subsistence, or other significance in the cultural 

system of a group traditionally associated with it” (Cultural Resource Management Guidelines [DO28:191]). The lands of Grand Canyon National Park are traditionally affiliated with nine American 

Indian groups: Havasupai, Hopi, Hualapai, Kaibab Band of Paiute Indians, Navajo, Paiute Indian 

Tribe of Utah, White Mountain Apache, San Juan Southern Paiute, and Pueblo of Zuni. The Grand 

Canyon has long been of importance to native cultures and figures prominently in the origin/religious 

beliefs and ceremonial practices of many groups. For example, traditional Hopi and Zuni beliefs hold the 

Grand Canyon as the sacred place from which their ancestors emerged to the present world (NPS 2001). 

Tribal studies of the Colorado River corridor (Neal and Gilpin 2000) identified ethnographic resources 

that occur within GRCA, primarily on the river corridor but in other areas as well. These included 

archeological sites (including rock art sites, trails, and graves), sacred sites, places mentioned in 

traditional history, subsistence areas, boundary line, natural landmarks, minerals, plants, animals and 

water (including springs). Although ethnographic resources significant to Native Americans may be 

present in the project area, no ethnographic resources are known to exist within the vicinity of the project 

site. 

Copies of this EA/AEF will be forwarded to each affiliated tribe for review and comment. If the tribes 

subsequently identify the presence of ethnographic resources within the project area, appropriate 

mitigation measures would be undertaken in consultation with the tribes. 

Environmental Consequences 

Methodology 

The baseline information used to assess impacts to cultural resources is as described in the methodology 

section at the beginning of this chapter and includes park staff knowledge of the resources and site; 

review of existing literature and park studies; information provided by specialists within the National Park 

Service and other agencies; and professional judgment. Detailed information on natural and cultural 

resources in Grand Canyon National Park that is summarized in the 1995 GMP and associated 

Environmental Impact Statement (EIS) was specifically referenced for information on affected resources 

in the project area. 

Because no archeological or historical resources or cultural landscapes will be affected by the project, 

they will not be discussed further. 

Ethnographic Resources. The definitions for levels of impact to ethnographic resources are as follows: 
Bright Angel Creek Trout Reduction Project Chapter 3 

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Negligible: Impact(s) would be barely perceptible and would neither alter resource conditions, 

such as traditional access or site preservation, nor the relationship between the resource and the 

affiliated group’s body of beliefs and practices. There would be no change to a group’s body of 

beliefs and practices. The determination of effect on Traditional Cultural Properties (ethnographic 

resources eligible to be listed in the National Register) for purposes of Section 106 would be no 

adverse effect. 

Minor: Adverse impact - impact(s) would be slight but noticeable and would neither appreciably 

alter resource conditions, such as traditional access or site preservation, nor the relationship 

between the resource and the affiliated group’s body of beliefs and practices. The determination 

of effect on Traditional Cultural Properties (ethnographic resources eligible to be listed in the 

National Register) for purposes of Section 106 would be no adverse effect. 

Beneficial impact - would allow access to and/or accommodate a group’s traditional 

practices or beliefs. The determination of effect on Traditional Cultural Properties (ethnographic 

resources eligible to be listed in the National Register) for purposes of Section 106 would be no 

adverse effect. 

Moderate: Adverse impact - impact(s) would be apparent and would alter resource conditions. 

Something would interfere with traditional access, site preservation, or the relationship between 

the resource and the affiliated group’s body of beliefs and practices, even though the group’s 

practices and beliefs would survive. The determination of effect on Traditional Cultural 

Properties (ethnographic resources eligible to be listed in the National Register) for purposes of 

Section 106 would be adverse effect. 

Beneficial impact - would facilitate traditional access and/or accommodate a group’s 

practices or beliefs. The determination of effect on Traditional Cultural Properties (ethnographic 

resources eligible to be listed in the National Register) for purposes of Section 106 would be no 

adverse effect. 

Major: Adverse impact - impact(s) would alter resource conditions. Something would block or 

greatly affect traditional access, site preservation, or the relationship between the resource and the 

affiliated group’s body of beliefs and practices, to the extent that the survival of a group’s beliefs 

and/or practices would be jeopardized. The determination of effect on Traditional Cultural 

Properties (ethnographic resources eligible to be listed in the National Register) for purposes of 

Section 106 would be adverse effect 

Beneficial impact - would encourage traditional practices and/or accommodate a group’s 

beliefs or practices. The determination of effect on Traditional Cultural Properties (ethnographic 

resources eligible to be listed in the National Register) for purposes of Section 106 would be no 

adverse effect.

Alternative A – No Action 

No known ethnographic resources are being affected in the project area (i.e., negligible impacts). If upon 

review of this EA/AEF or further consultation, any of the affiliated tribes subsequently identify the 

presence of ethnographic resources within the project area, appropriate mitigation measures would be 

undertaken in consultation with the tribes. The location of any ethnographic sites would not be made 

public.

Cumulative Impacts 
Bright Angel Creek Trout Reduction Project Chapter 3 

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No cumulative impacts of consequence are anticipated to ethnographic resources from the several actions 

affecting Bright Angel Canyon and trout populations in GRCA (i.e., negligible cumulative impacts). 

Alternative B – Mechanical Removal (Preferred Alternative) 

No known ethnographic resources are expected to be affected by the preferred alternative in the project 

area (i.e., negligible impacts). If upon review of this EA/AEF or further consultation, any of the affiliated 

tribes subsequently identify the presence of ethnographic resources within the project area, appropriate 

mitigation measures would be undertaken in consultation with the tribes. The location of any 

ethnographic sites would not be made public.

Cumulative Impacts 

No cumulative impacts of consequence are anticipated to ethnographic resources from the several actions 

affecting Bright Angel Canyon and trout populations in GRCA (i.e., negligible cumulative impacts). 

Conclusions 

Alternative A - No Action. This alternative would result in no changes to ethnographic resources in 

GRCA (i.e., negligible impacts). Because there would be no major, adverse impacts to a resource or 

value whose conservation is (1) necessary to fulfill specific purposes identified in the establishing 

legislation or proclamation of GRCA; (2) key to the natural or cultural integrity of the Park or to 

opportunities for enjoyment of the Park; or (3) identified as a goal in the Park’s general management plan 

or other relevant NPS planning documents, there would be no impairment of the Park’s resources or 

values. 

Alternative B – Mechanical Removal (Preferred Alternative). This alternative would result in no 

changes to ethnographic resources in GRCA, and no known ethnographic resources would be affected 

(i.e., negligible impacts). Because there would be no major, adverse impacts to a resource or value 

whose conservation is (1) necessary to fulfill specific purposes identified in the establishing legislation or 

proclamation of GRCA; (2) key to the natural or cultural integrity of the Park or to opportunities for 

enjoyment of the Park; or (3) identified as a goal in the Park’s general management plan or other relevant 

NPS planning documents, there would be no impairment of the Park’s resources or values. 

§106 Summary: After applying the Advisory Council Historic Preservation’s criteria of adverse effects 

(36 CFR Part 800.5, Assessment of Adverse Effects), the National Park Service concludes that 

implementation of the preferred alternative would have no affect on historic properties or on ethnographic 

resources. 

VISITOR EXPERIENCE 

Affected Environment 

The loss of recreational fishing in Bright Angel Creek was a visitor experience-related issue raised during 

scoping for this EA. Anglers have been participating in the sport fishery in the creek since trout were first 

introduced in the 1920s. Public interest was sufficiently high over four decades for the NPS to repeatedly 

stock the creek after recurrent floods wiped out the fishery. Stocking ceased in 1964 after Glen Canyon 

Dam altered conditions in the Colorado, allowing trout to survive and reproduce in the mainstem (Valdez 
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and Carothers 1998). Rainbow trout once dominated the sport fishery, with some stocked brook, brown, 

and cutthroat trout. In recent years, brown trout have dominated the catch, although rainbow trout are still 

common. The proportion of species in the assemblage depends in part on the time of year because brown 

trout spawn somewhat earlier in the winter than do rainbow trout. Fishing in Bright Angel Creek is 

unlimited (no bag or size limits). 

This recreational opportunity has long been popular with a small segment of park visitors, but that 

segment appears to be declining. Quantitative data from a creel census conducted in the winter of 1977-

1978 indicated that an average of 6.3 anglers was counted each day for 20 days (Table 4). In the most 

recent creel census, conducted in the winter of 1989-1990, an average of 4.8 anglers were counted each 

day for 73 days. Popularity of the fishery may have peaked in the 1980s. NPS personnel on-site during 

that period report seeing 20 or more anglers along the creek on the busiest days. In recent years only one 

to three anglers are seen on a typical day, with use highest in spring and fall (Sjors 2004). The total 

annual number of individual anglers has ranged from a low of about 75 to a high of about 200 (Kassovic 

2004). Fishing pressure at Bright Angel Creek has always been relatively low because of the difficult 

access (by foot or mule down long and steep trails), but the reasons for the decline in use over the last 10-

15 years are unclear. They may be related to the shift in the fish assemblage from predominantly rainbow 

trout to predominantly brown trout, to a change in the condition or abundance of trout, or to other factors. 

Table 4. Creel census data from Bright Angel Creek, winter 1977-1978 and 1989-1990. 

1977-1978* 1989-1990** 

Number of creel count days 20 73 

Number of interviews 126 351 

Total hours spent fishing 417.15 1,205.3 

Percentage of anglers catching fish 56% 93% 

Total number of fish caught and kept 121 409 

Total number of fish released 84 3,166 

Catch per person-hour 0.49 2.97 

Hour per angler 3.31 3.43 

Fish per day 10.25 48.97 

Number of fishermen per day 6.3 4.8 

* Source: Carothers and Minckley (1981); last four categories extrapolated from first six categories. 

** Source: Kline at al. (1990); last four categories extrapolated from first six categories. 

Anglers comprise a small percentage of the thousands who visit the Bright Angel Creek area each year 

and a miniscule percentage of the 4-5 million visitors to GRCA. Most people visit GRCA to experience 

one of the premier geologic and scenic wonders of the world. The vast majority remain on the rims, 

enjoying the Canyon’s vistas from numerous viewpoints. Those who venture to the bottom are generally 

interested in hiking, camping, exploring, river running, or reveling in the rugged scenery. They are drawn 

by the adventure, physical challenge, wildlife, and wild character of the place. Sport fishing plays a 

minor role in the full spectrum of recreational activities offered by GRCA. Still, for the few dedicated 

anglers who regularly fish Bright Angel Creek, angling in the spectacular setting at the bottom of Grand 

Canyon is a unique and prized experience. 
Bright Angel Creek Trout Reduction Project Chapter 3 

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44 

Environmental Consequences 

Methodology 

The thresholds of change for the intensity of impact on visitor experience in GRCA are defined as 

follows: 

Negligible: There would be no effects on visitor use and/or experience, or if there are effects 

they would be at the lowest levels of detection. Effects would be short term. Visitors would not 

likely be aware of the effects. 

Minor: Changes in visitor use and/or experience would be detectable, although short term, 

slight, and limited in scope. Some visitors would be aware of the effects. Minor inconveniences 

would occur that would not significantly change most visitor use patterns or degrade the 

experience of most visitors. 

Moderate: Changes in visitor use and/or experience would be readily apparent and likely long 

term. Many visitors would be aware of the changes and would likely express comments about the 

changes. 

Major: Changes in visitor use and/or experience would be apparent and have significant longterm consequences. The use patterns and behaviors of most visitors would be altered. Changes 

would illicit strong opinion from visitors. 

Alternative A – No Action 

This alternative would result in no changes to visitor experience in GRCA. Angling in Bright Angel 

Creek would still be available as a recreational opportunity for visitors to the Phantom Ranch area. 

Cumulative Impacts 

No cumulative impacts of consequence are anticipated to visitor experience from the several actions 

affecting Bright Angel Canyon and trout populations in GRCA. Most construction projects affecting 

Bright Angel Canyon would have short-term adverse impacts and would provide long-term benefits to the 

visitor experience in the area. 

Alternative B – Mechanical Removal (Preferred Alternative) 

Under this alternative, the quality of angling in Bright Angel Creek would be reduced. During the trout 

spawn in winter, the abundance of trout immediately upstream of the weir would diminish compared to 

No Action, although in the first years of the project recreational fishing would still be productive 

downstream of the weir and along the banks of the Colorado River. Over subsequent years, as returning 

trout are eliminated, the quality of angling downstream of the weir would diminish as well. Eventually, 

few trout would be available anywhere in Bright Angel Creek, but some trout would always be available 

in the river. A small portion of visitors to the area would still fish as an incidental part of their 

experience, but fewer individuals would travel to the area solely or principally to fish. The loss of the 
Bright Angel Creek Trout Reduction Project Chapter 3 

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45 

sport fishery would be felt by up to an estimated 200 visitors per year, but for the overwhelming majority 

of the Park’s 4-5 million visitors, the change would go unnoticed. Consequently, the impacts to visitor 

experience at GRCA would be minor, indirect, adverse, and local. The duration of the impacts would 

depend on the duration of the action but is likely to be long term. 

Few visitors to Bright Angel Creek would see the weir. It would be placed in an unobtrusive location 

near the mouth of the creek, out of sight of the main trail. People crossing a footbridge to a public 

restroom and ranger station may notice the structure from the bridge. If anyone approaches the weir and 

expresses interest, the biologist on duty would explain the purpose of the project. Electrofishing 

depletion reaches upstream in the creek would be selected in part with visitor sensibilities in mind. 

Again, project personnel would take time to explain the purpose of the project to any visitor who notices 

the operation and expresses interest. Impacts on the aesthetic qualities of Bright Angel Creek and 

intrusions to visitor experience would be negligible, direct, adverse, and short term. 

Cumulative Impacts 

No cumulative impacts of consequence are anticipated to visitor experience from the several actions 

affecting Bright Angel Canyon and trout populations in GRCA. Most construction projects affecting 

Bright Angel Canyon would have short-term adverse impacts and would provide long-term benefits to the 

visitor experience in the area. 

Conclusions 

Alternative A - No Action. This alternative would result in no changes to visitor experience in GRCA. 

Angling in Bright Angel Creek would still be available as a recreational opportunity in the Park. Because 

there would be no major, adverse impacts to a resource or value whose conservation is (1) necessary to 

fulfill specific purposes identified in the establishing legislation or proclamation of GRCA; (2) key to the 

natural or cultural integrity of the Park or to opportunities for enjoyment of the Park; or (3) identified as a 

goal in the Park’s general management plan or other relevant NPS planning documents, there would be no 

impairment of the Park’s resources or values. 

Alternative B – Mechanical Removal (Preferred Alternative). Only a very small proportion of the 

visitors to GRCA would be aware of the effects of the Preferred Alternative on sport fishing in Bright 

Angel Creek. Most visitor use patterns in the Park would not change. As a result, while impacts on 

visitor experience would be adverse, they would be minor in intensity and local. 
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CHAPTER 4 – CONSULTATION AND COORDINATION 

EXTERNAL SCOPING/PUBLIC INVOLVEMENT 

Public scoping began on December 10, 2003, with letters sent to 283 recipients, including Native 

American tribes, stakeholder groups, agencies, libraries, and private individuals who were likely to be 

interested in, or concerned about, the proposed action (see Appendix B for a copy of the scoping letter). 

The letter was also posted on the GRCA Web site. Public scoping ended on January 12, 2004. 

Comments in the form of e-mails, letters, and phone conversations with park staff were received from 50 

respondents, including 44 individuals, 5 organizations, and 1 state agency (Arizona Game and Fish 

Department). 

In addition to public scoping, results of the 2003 Bright Angel Creek feasibility study and the proposed 

action were presented to stakeholder groups and the scientific community on two occasions. On October 

1, 2003, a presentation was made to a meeting of the Glen Canyon Adaptive Management Program 

Technical Work Group. Representatives of the following groups were in attendance: 

Arizona Department of Water Resources 

Arizona Game and Fish Department 

Colorado River Board of California 

Colorado River Commission of Nevada 

Colorado Water Conservation Board 

EcoPlan Associates 

Federation of Fly Fishers 

Grand Canyon River Guides 

Grand Canyon Trust 

Grand Canyon Wildlands Council 

Hualapai Tribe 

Irrigation and Electrical Districts Association 

New Mexico Interstate Stream Commission 

Northern Arizona University 

Pueblo of Zuni 

Southern Paiute Consortium 

U.S. Bureau of Indian Affairs 

U.S. Bureau of Reclamation 

U.S. Fish and Wildlife Service 

U.S. Geological Survey, Grand Canyon Monitoring and Research Center 

U.S. National Park Service, Glen Canyon National Recreation Area 

U.S. National Park Service, Grand Canyon National Park 

U.S. Western Area Power Administration 

Upper Colorado River Commission 

Utah Associated Municipal Power Service 

Wyoming State Engineer’s Office 

On October 29, 2003, a similar presentation was made at a science symposium sponsored by GCMRC 

(The Colorado River: An Ecosystem Science Symposium, Tucson, Arizona, October 28-30, 2003). 

Feedback from both presentations, as well as public and agency comments received during the scoping 

period, were taken into account when considering alternatives and issues to be analyzed for this 

document. 

AGENCY CONSULTATION 

US Fish and Wildlife Service 

The Park developed a Biological Assessment (December 16, 2003) that was submitted to the Phoenix 

office of the US Fish and Wildlife Service on December 22, 2003. The park requested and obtained 

concurrence that the proposed action (Alternative B) was “not likely to adversely affect” humpback chub 

or California condor. On February 9, 2004, the Park requested formal consultation for the bald eagle. On 

March 2, 2004, the US Fish and Wildlife Service issued a Biological Opinion concluding that the project, 

as proposed, is “not likely to jeopardize the continued existence of the bald eagle.” 

State Historic Preservation Office 

Initiation of consultation with the State Historic Preservation Office occurred on 18 November 2003. 

Review and comment of this EA/AEF will constitute completion of consultation with the SHPO’s office. 
Bright Angel Creek Trout Reduction Project Chapter 4 

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American Indian Tribes 

NPS is initiating consultation with all affiliated tribes (Havasupai, Hopi, Hualapai, Kaibab Band of Paiute 

Indians, Navajo, Paiute Indian Tribe of Utah, White Mountain Apache, Yavapai Apache, San Juan 

Southern Paiute, Moapa Band of Paiute, Las Vegas and Pueblo of Zuni) as part of the review of the 

EA/AEF. A letter with an attached copy of the EA/AEF was distributed to all affiliated tribes for their 

review and comment. 

Other Agencies and Government Representatives

Letters were sent to Arizona Game and Fish Department, members of the Glen Canyon Dam Adaptive 

Management Program and affiliated groups, other local and regional agencies, and government 

representatives announcing the availability of the EA/AEF and inviting comments. 

INTERNAL SCOPING 

Internal scoping was conducted by an interdisciplinary team of professional from Grand Canyon National 

Park. Interdisciplinary team met at the parkwide interdisciplinary team and the project review board. 

ENVIRONMENTAL ASSESSMENT/ASSESSMENT OF EFFECT REVIEW AND LIST 

OF RECIPIENTS 

The Environmental Assessment/Assessment of Effect will be released for public review in August 2006. 

To inform the public of the availability EA/AEF, the NPS is publishing and distributing a press release, a 

letter to various agencies, tribes, and members of the public that responded to the public scoping in 2003-

2004, and a letter to the park’s mailing list for such projects. Copies of the EA/AEF will be provided to 

interested individuals, upon request. Copies of the document will also be available for review at 

www.parkplanning.nps.gov/grca. 

The EA/AEF is open for a 30 day public comment period ending October 2, 2006. During this time, the 

pubic is encouraged to submit their written comments to the National Park Service address provided at the 

beginning of this document. Following the close of the comment period, all public comments will be 

reviewed and analyzed, prior to the release of a decision document. 

PREPARERS AND CONTRIBUTORS: 

This document was developed in stages following the public scoping period. A draft EA/AEF was 

prepared for internal NPS review in 2004-2005. In 2006, the draft EA/AEF was revised based upon the 

internal review comments and this document was prepared for public review. 

CONTRIBUTORS TO EA/AEF 

Grand Canyon National Park 

Jeffrey Cross, former Science Center Director 

R.V. Ward, Park Biologist 

Sara White, former Compliance Officer 

Jill Beshears, Environmental Protection Specialist 

Mary Killeen, Chief, Office of Planning and Compliance 

Jan Balsom, Acting Science Center Director 
Bright Angel Creek Trout Reduction Project Chapter 4 

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PREPARERS OF EA/AEF 

SWCA Environmental Consultants 

William C. Leibfried, Senior Scientist 

Dorothy A. House, NEPA Specialist 

Kevin Serrato, Biologist 

PREPARERS OF EA/AEF 

Grand Canyon National Park 

Rick Ernenwein, Planner, Office of Planning and Compliance 
Bright Angel Creek Trout Reduction Project Selected References 

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SELECTED REFERENCES 

FEDERAL STATUTES 

National Park Service Organic Act of 1916 

Clean Air Act of 1963, as amended (CAA) 

Wilderness Act of 1964 

National Historic Preservation Act of 1966, as amended (NHPA) 

National Environmental Policy Act 1969, as amended (NEPA) 

Clean Water Act of 1972 

Endangered Species Act of 1973, as amended (ESA) 

Archeological Resources Protection Act of 1979 (ARP) 

Native American Graves Protection and Repatriation Act of 1990 (NAGPRA) 

EXECUTIVE ORDERS 

Executive Order 11990 (Wetlands) 

Executive Order 11988 (Floodplain Management) 

Executive Order 12898 (Environmental Justice) 

Executive Order 13007 (Sacred Sites) 

Executive Order 13112 (Invasive Species) 

DEPARTMENT OF THE INTERIOR DIRECTIVES 

Secretarial Order 3175 (Indian Trust Assets) 

Environmental Compliance Memorandum (ECM) 95-2 (Indian Trust Assets) 

NATIONAL PARK SERVICE DIRECTIVES, POLICIES, AND PLANS 

Director’s Order 12 Conservation Planning, Environmental Impact Analysis and Decision Making 

Director’s Order 47 Sound Preservation and Noise Management 

Director’s Order 55 Interpreting the National Park Service Organic Act. 

National Park Service Management Policies Handbook (1978) 

National Park Service management policies 2001 

National Park Service Strategic Plan, FY 2001 – 2005 

GRAND CANYON NATIONAL PARK DOCUMENTS 

Fish Management Plan for Grand Canyon National Park (1981) 
Bright Angel Creek Trout Reduction Project Selected References 

Environmental Assessment/Assessment of Effect 

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50 

Final Wilderness Recommendation (1993) 

Grand Canyon National Park General Management Plan (1995) 

Grand Canyon National Park Resource Management Plan (1997) 

FEDERAL REGISTER PUBLICATIONS 

U.S. Fish and Wildlife Service (USFWS). 1967. Native Fish and Wildlife, Endangered Species. Federal 

Register 32(205):4001. March 11, 1967. 

U.S. Fish and Wildlife Service (USFWS). 1994. Endangered and Threatened Wildlife and Plants: 

Determination of Critical Habitat for Four Colorado River Endangered Fishes; Final Rule. 

Federal Register 59 (54):13374–13400. March 21, 1994. 

U.S. Fish and Wildlife Service (USFWS). 1991. Endangered and Threatened Wildlife and Plants; The 

Razorback sucker, Xyrauchen texanus, determined to be an endangered species. Federal 

Register: Volume 56 (205):54957–54967. October 23, 1991. 

U.S. Fish and Wildlife Service (USFWS). 1995. Endangered and Threatened Wildlife and Plants; Final 

Rule to Reclassify the Bald Eagle From Endangered to Threatened in All of the Lower 48 States. 

Federal Register (133):35999–36010. July 12, 1995. 

U.S. Fish and Wildlife Service (USFWS). 1999. Endangered and Threatened Wildlife and Plants; 

Proposed Rule to Remove the Bald Eagle in the Lower 48 States From the List of Endangered 

and Threatened Wildlife. Federal Register 64(128):36453–36464. July 6, 1999. 
Bright Angel Creek Trout Reduction Project References Cited 

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REFERENCES CITED 

Arizona Game and Fish Department (AGFD). 1996. Ecology of Grand Canyon backwaters. Prepared 

for the Bureau of Reclamation, Upper Colorado Region, Glen Canyon Environmental Studies, 

Flagstaff, Arizona. Cooperative agreement No. 9-FC-40-07940. 

Arizona Game and Fish Department (AGFD). 2001. Catostomus latipinnis. Unpublished abstract 

compiled and edited by the Heritage Data Management System, Arizona Game and Fish 

Department, Phoenix. On-line at: 

 http://www.azgfd.com/wildlife_conservation/edits/hdms_abstracts_fish.html. 

Arizona Game and Fish Department (AGFD). 2002a. Xyrauchen texanus. Unpublished abstract 

compiled and edited by the Heritage Data Management System, Arizona Game and Fish 

Department, Phoenix. On-line at: 

 http://www.azgfd.com/wildlife_conservation/edits/hdms_abstracts_fish.html. 

Arizona Game and Fish Department (AGFD). 2002b. Rana pipiens. Unpublished abstract compiled and 

edited by the Heritage Data Management System, Arizona Game and Fish Department, Phoenix. 

On-line at: 

 http://www.azgfd.com/wildlife_conservation/edits/hdms_abstracts_amphibians.html. 

Arizona Game and Fish Department (AGFD). 2002c. Pandion haliaetus. Unpublished abstract 

compiled and edited by the Heritage Data Management System, Arizona Game and Fish 

Department, Phoenix. On-line at: http://www.azgfd.com/w_c/edits/hdms_abstracts_birds.html. 

Blinn, D.W., C. Runck, D.A. Clark, and J.N. Rinne. 1993. Effects of rainbow trout predation on Little 

Colorado spinedace. Transactions of the American Fisheries Society 122:139–143. 

Brown, B.T., and L.E. Stevens. 1992. Winter abundance, age structure, and distribution of bald eagles 

along the Colorado River, Arizona. The Southwestern Naturalist 37(4):404–435. 

Brown, B.T., R. Mesta, L.E. Stevens, and J. Weisheit. 1989. Changes in winter distribution of bald 

eagles along the Colorado River in Grand Canyon, Arizona. Journal of Raptor Research 

23(3):110–113. 

Carothers, S.W., and C.O. Minckley. 1981. A survey of the aquatic flora & fauna of the Grand Canyon. 

[Submitted to] U.S. Department of the Interior, Water and Power Resources Service, Boulder 

City, Nevada. Department of Biology, Museum of Northern Arizona, Flagstaff. 

Coggins, L., and M. Yard. 2003. Mechanical removal of non-native fishes in the Colorado River in 

Grand Canyon: Update of winter 2003 operations and findings. A report to the Glen Canyon 

Dam Adaptive Management Program. Southwest Biological Science Center, Grand Canyon 

Monitoring and Research Center, Flagstaff, Arizona. 

Coggins, L., M. Yard, and C. Paukert. 2002. Piscivory by non-native salmonids in the Colorado River 

and an evaluation of the efficacy of mechanical removal of non-native salmonids. Grand Canyon 

Monitoring and Research Center, U.S. Geologic Survey, Flagstaff, Arizona. 
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Coggins, L., C. Walters, C. Paukert, and S. Gloss. 2003. An overview of status and trend information for 

the Grand Canyon population of the humpback chub (Gila cypha). Prepared by the Grand 

Canyon Monitoring and Research Center, USGS, Flagstaff, Arizona, for the Glen Canyon Dam 

Adaptive Management Work Group Ad Hoc Committee on Humpback Chub. 

Council on Environmental Quality (CEQ). 1981. Memorandum to agencies: Forty most-asked questions 

concerning CEQ's National Environmental Policy Act regulations. Federal Register 46:18026. 

Department of the Interior (DOI). 2002. Proposed Releases from Glen Canyon Dam and Removal of 

Non-Native Fish. Bureau of Reclamation, National Park Service, U.S. Geological Survey. 

Grand Canyon Monitoring and Research Center (GCMRC). 2003a. Proposed two-year science plan for 

experimental flow treatments and mechanical removal activities in WY’s 2002–2004. Glen 

Canyon Dam Adaptive Management Program. Flagstaff, Arizona. 

Grand Canyon Monitoring and Research Center (GCMRC). 2003b. An overview of status and trend 

information for the Grand Canyon population of the humpback chub, Gila Cypha. Glen Canyon 

Dam Adaptive Management Work Group. Ad Hoc Committee on Humpback chub. Flagstaff, 

Arizona. 

Grand Canyon Monitoring and Research Center (GCMRC). 2006. Grand Canyon Humpback Chub 

Population Stabilizing. U.S. Geological Survey Fact Sheet 2006-3109, July 2006. Flagstaff, 

Arizona. 

Grand Canyon National Park (GRCA). 1981. Fish Management Plan for Grand Canyon National Park. 

Grand Canyon National Park (GRCA). 1994. [Streamflow and water quality data collected 1994–1994 

under the supervision of John Rihs, Grand Canyon National Park geologist. On-file in the Grand 

Canyon National Park Science Center, Grand Canyon, Arizona.] 

Grand Canyon National Park (GRCA). 2002a. Tamarisk management and tributary restoration: 

Environmental assessment. Grand Canyon National Park, Grand Canyon, Arizona. 

Grand Canyon National Park (GRCA). 2002b. Finding of No Significant Impact: Tamarisk 

management and tributary restoration. Grand Canyon National Park, Grand Canyon, Arizona. 

Grand Canyon National Park (GRCA). 2003a. Upgrade corridor area fire protection: Environmental 

assessment. Grand Canyon National Park, Grand Canyon, Arizona. 

Grand Canyon National Park (GRCA). 2003b. Finding of No Significant Impact (FONSI): Upgrade 

corridor area fire protection system, Grand Canyon National Park. Grand Canyon National Park, 

Grand Canyon, Arizona. 

Grand Canyon National Park (GRCA). 2005. Finding of No Significant Impact (FONSI): Construct, 

Rehabilitate and Repair Restrooms Parkwide. Grand Canyon National Park, Grand Canyon, 

Arizona. 

Grisak, G., and B. Marotz. 2003. South Fork Flathead Watershed Westslope Cutthroat Trout 

Conservation Program. Project No. 1991-01903. BPA Report DOE/BP-00005043-1. Bonneville 

Power Administration, Portland, Oregon. 
Bright Angel Creek Trout Reduction Project References Cited 

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Bright Angel Creek Trout Reduction Project Appendix A 

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APPENDIX A 

Special Status Species in Coconino County, Arizona 

Table A-1. Federally listed and candidate species in Coconino County, Arizona.

Common Name Scientific Name Status 

Listed 

Apache (Arizona) trout Oncorhynchus apache Threatened 

Bald eagle Haliaeetus leucocephalus Threatened 

Black-footed ferret Mustela nigripes Endangered 

Brady pincushion cactus Pediocactus bradyi Endangered 

California brown pelican Pelecanus occidentalis californicus Endangered 

California condor Gymnogyps californianus Endangered 

Chiricahua leopard frog Rana chiricahuensis Threatened 

Humpback chub Gila cypha Endangered 

Kanab ambersnail Oxyloma haydeni kanabensis Endangered 

Little Colorado spinedace Lepidomeda vittata Threatened 

Mexican gray wolf Canis lupus baileyi Endangered 

Mexican spotted owl Strix occidentalis lucida Threatened 

Navajo sedge Carex specuicola Threatened 

Razorback sucker Xyrauchen texanus Endangered 

San Francisco Peaks groundsel Senecio franciscanus Threatened 

Sentry milk vetch Astragalus cremnophylax var. cremnophylax Endangered 

Siler pincushion cactus Pediocactus sileri Threatened 

Southwestern willow flycatcher Empidonax traillii extimus Endangered 

Welsh's milkweed Asclepias welshii Threatened 

Gila chub Gila intermedia Proposed 

Endangered 

Candidate

Fickeisen plains cactus Pediocactus peeblesianus var. fickeiseniae Candidate 

Yellow-billed cuckoo Coccyzus americanus Candidate 

Source: U.S. Fish and Wildlife Service (USFWS) Web site: 

https://fw2azes.r2.fws.gov/specmgt.nsf/165ef5cfbf07a3f107256bff0075fc9d?OpenView. 
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Table A-2. Wildlife Species of Concern in Arizona (WSCA) in Coconino County, Arizona. 

Common Name Scientific Name Status 

 

Fish 

Little Colorado sucker Catostomus spp. WSCA 

Humpback chub Gila cypha WSCA 

Roundtail chub Gila robusta WSCA 

Little Colorado spinedace Lepidomeda vittata WSCA 

Apache (Arizona) trout Oncorhynchus apache WSCA

Razorback sucker Xyrauchen texanus WSCA

 

Amphibians 

Plains leopard Frog Rana blairi WSCA

Chiricahua leopard frog Rana chiricahuensis WSCA

Northern leopard frog Rana pipiens WSCA

Lowland leopard frog Rana yavapaiensis WSCA

 

Reptiles 

Mexican garter snake Thamnophis eques megalops WSCA

Narrow-headed garter snake Thamnophis rufipunctatus WSCA

 

Birds 

Northern goshawk Accipiter Gentilis WSCA

Ferruginous hawk Buteo regalis WSCA

Common black-hawk Buteogallus anthracinus WSCA

Belted kingfisher Ceryle alcyon WSCA

Southwestern willow flycatcher Empidonax traillii extimus WSCA

American peregrine falcon Falco peregrinus anatum WSCA

Bald eagle Haliaeetus leucocephalus WSCA

Osprey Pandion haliaetus WSCA

Pine grosbeak Pinicola enucleator WSCA

Mexican spotted owl Strix occidentalis lucida WSCA

 

Mammals 

Houserock Valley chisel-toothed kangaroo rat Dipodomys microps leucotis WSCA

Spotted bat Euderma maculatum WSCA

Western red bat Lasiurus blossevillii WSCA

Hualapai Mexican vole Microtus mexicanus hualpaiensis WSCA

Navajo Mexican vole Microtus mexicanus navaho WSCA

Source: Arizona Game and Fish Department (AGFD) Web site: http://www.azgfd.com/w_c/edits/hdms_species_lists.html).