Comments on Glen Canyon Dam LTEMP DSEIS, EIS No. 20240024. Page 1

25 March 2024

SENT VIA ELECTRONIC MAIL

US Department of the Interior

Bureau of Reclamation

Attn: LTEMP SEIS Project Manager 

Upper Colorado Basin Region

125 South State Street, Room 8100

Salt Lake City, UT 84138

LTEMPSEIS@usbr.gov

RE: Glen Canyon Dam Long-Term Experimental and Management Plan Draft 

Supplemental Environmental Impact Statement to Address the Threat of 

Smallmouth Bass Below Glen Canyon Dam, EIS No. 20240024.

LTEMP SEIS Project Manager:

The Center for Biological Diversity, Sierra Club Grand Canyon Chapter, Living Rivers 

and Colorado Riverkeeper, and Great Basin Water Network (“Conservation Groups”) provide 

the following comments on the Bureau of Reclamation’s (“BOR”) “Draft Supplemental 

Environmental Impact Statement for the December 2016 Record of Decision Entitled Glen 

Canyon Dam Long-Term Experimental and Management Plan.” 89 Fed. Reg. 02676-77 (Feb 9,

2024).

Attached and incorporated by reference to these comments are our March 10, 2023 

comments on “Glen Canyon Dam/Smallmouth Bass Flow Options Draft Environmental 

Assessment,” and our November 3, 2023 comments on “Scoping for Supplemental 

Environmental Impact Statement for the December 2016 Record of Decision Entitled Glen 

Canyon Dam Long-Term Experimental and Management Plan.” 88 Fed. Reg. 68667-69 (Oct. 4 

2023).

As we stated in those comments, this is an emergency. Operation of Glen Canyon Dam’s 

penstocks, by passing warm water and warmwater invasive fish through the dam, is causing an 

ongoing and worsening invasion of non-native predator fish in the Colorado River. This 

threatens to decimate humpback chub’s last large source population at the confluence of the 

Little Colorado River, thereby jeopardizing the entire species. “Rapid response” measures to 

control invasive fish population expansion below the dam are failing. This expansion is enhanced 

by BOR’s ongoing, multi-year failure to enact conservation measures in the 2016 LTEMP 
Comments on Glen Canyon Dam LTEMP DSEIS, EIS No. 20240024. Page 2

Biological Opinion to modify the dam with fish exclusion devices to prevent entrainment1and 

eliminate nursery habitats for invasive fish downstream.

We again urge immediate action to manage flows below 16 degrees Celsius (60.8 degrees 

Fahrenheit) to prevent further smallmouth bass production and concurrent immediate action to 

(1) install fish exclusion devices on Glen Canyon Dam to prevent further passage of warmwater

invasive fish through the dam, (2) modify the 12-mile slough to prevent further warmwater

invasive fish reproduction and population expansion below the dam, and (3) augment sediment

to increase turbidity and reduce smallmouth bass predation downstream of the dam. This remains

a critical issue this year as researchers expect that due to aridification this year will again see less

than expected runoff into the system despite average snowfall.

2

Conservation groups again urge BOR to plan now for the survival and recovery of the 

Grand Canyon’s endangered fish in the context of the climate-inevitable deadpool and 

obsolescence of Glen Canyon Dam and Lake Powell. Conservation groups urge BOR to plan a 

phased decommissioning of Glen Canyon Dam that (1) maintains the relatively intact native 

fishery in the Grand Canyon upstream of Pearce Ferry Rapid; and, in the short and long terms, 

(2) prevents warmwater predator fish from invading the Grand Canyon from upstream or

downstream of the dam site and Pearce Ferry, and (3) facilitates the restoration of the Colorado

River’s naturally warm, turbid flows through the Grand Canyon.

I. The Conservation Groups

The Center for Biological Diversity is a national, non-profit conservation organization 

dedicated to protecting and recovering endangered species and the habitats upon which they 

depend for their survival. The Center has 1.7 million members and supporters, including 

members who use and enjoy the Grand Canyon the Colorado River for recreation, natural 

history, spiritual renewal, photography, art, wildlife observation and scientific study. The Center 

has been involved in the preservation of threatened and endangered species and their habitats in 

the Grand Canyon region for decades including protection of the Grand Canyon’s aquifers. 

Those species include the federally threatened humpback chub, the endangered razorback sucker, 

the endangered southwestern willow flycatcher, and the threatened Mexican spotted owl. Those 

habitats include the Colorado River, its springs and connected streams, and terrestrial habitats 

within and adjacent to Grand Canyon National Park’s boundaries. 

The Sierra Club’s mission is “to explore, enjoy, and protect the wild places of the earth; 

to practice and promote the responsible use of the earth’s ecosystems and resources; and to 

educate and enlist humanity to protect and restore the quality of the natural and human 

environments.” The Grand Canyon (Arizona) Chapter was formed in 1965 in order to focus 

attention on stopping dams in Grand Canyon. Our work to protect the Colorado River and Grand 

Canyon National Park continues today. Our 13,000 members and supporters have a significant 

interest in the health of the Colorado River and the species that depend upon it.

1

Entrainment means passage of fish from Lake Powell through Glen Canyon Dam into the Colorado River

downstream.

2 https://subscriber.politicopro.com/article/eenews/2024/03/13/researchers-expect-underperforming-springrunoff-for-colorado-river-00146742
Comments on Glen Canyon Dam LTEMP DSEIS, EIS No. 20240024. Page 3

Living Rivers is a non-profit corporation dedicated to the preservation, protection, and 

restoration of rivers and watersheds in the Colorado Plateau. Living Rivers works to ensure the 

long-term health and viability of human, animal, and plant species, as well as environmental 

quality threatened by mining and oil and gas operations in the region—with a principal focus of 

reestablishing a free-flowing Colorado River through Glen and Grand Canyons. Colorado 

Riverkeeper is a licensed organizational member of Waterkeeper Alliance, which is a global 

movement of advocates working to protect rivers, streams, and coastlines around the world, 

including, through Colorado Riverkeeper, the Colorado River. 

The Great Basin Water Network (GBWN) was formed to protect the water resources of 

Nevada and Utah for residents, animal and plants in the Great Basin and Colorado River Basin. 

The Network promotes effective water conservation programs and locally sustainable uses to 

ensure that water remains accessible for all living things.

II. Modeling Suggests “Cool Mix” and “Cool Mix Flow Spike” Are the Only

Alternatives that Prevent Smallmouth Bass Population Growth in the

Colorado River’s Mainstem

Conservation groups support the “Cool Mix” and “Cool Mix Flow Spike” alternatives 

because, per USGS modeling, these are the only two alternatives that will inhibit smallmouth 

bass (SMB) reproduction and population growth within the mainstem of the Colorado River 

downstream of Glen Canyon Dam through 2027. DSEIS at Figure 1, Appendix A. However, as 

detailed below, neither of these alternatives alone provide sufficient measures for protecting the 

humpback chub and its critical habitat. 

That modeling projects that all other alternatives will result in some amount of SMB 

reproduction and population growth by 2027. Id. This will result in ongoing SMB expansion 

further modifying adversely designated critical habitat for humpback chub, and heightening 

chances that SMB invasion will decimate the humpback chub’s Little Colorado River 

population. Id.

III. Additional Measures are Needed Because None of the Alternatives Will

Prevent Smallmouth Bass Population Growth in Tribuaries or Side Channels

Whose Water Temperatures Don’t Change with Mainstem River Water

Temperature

Conservation groups note that none of the DSEIS alternatives will prevent SMB (or other 

warmwater invasive fish) reproduction and population growth within portions of tributary 

streams or side channels that are accessible to those fish and whose temperatures are unaffected 

or minimally affected by mainstem water temperature changes. 

Absent measures to stop dam entrainment and modify side channel habitats that enable 

warm water fish reproduction, the “Cool Mix” and “Cool Mix Flow Spike” alternatives may 

slow and limit but will not stop adverse modification of designated critical habitat for Grand 

Canyon’s endangered fish. 
Comments on Glen Canyon Dam LTEMP DSEIS, EIS No. 20240024. Page 4

BOR cannot omit analysis and disclosure under NEPA or ESA of the effects of 

warmwater invasive fish entertainment, as it has and is likely to continue to facilitate expansion 

on nonnative fish populations within side channels (for example, the “slough”) and/or tributary 

streams whose water temperatures are relatively unaffected by mainstream water temperature 

changes.

IV. Smallmouth Bass Have Likely Reached the Little Colorado River

Since 1 July 2022, when juvenile SMB were originally detected below Grand Canyon, 

SMB have expanded downstream from Glen Canyon Dam at an average rate of about four miles 

per month. Federal reports of invasive fish surveillance in Grand Canyon National Park show

that, as of October 2023, SMB had been detected as far downstream as River Mile 47, about 14 

miles upstream of the Little Colorado River (at mile 61.5) and the largest remaining source 

population of humpback chub on earth.3 Given an expansion rate of four river miles per month, 

SMB populations can reasonably be expected to have expanded downstream to the Little 

Colorado River as of February of 2024, and to take refuge and begin reproducing this year in its 

relatively warm tributary waters. We note too the same monitoring shows that other warmwater 

invasive fish, like green sunfish have been widespread in the vicinity of the Little Colorado 

River. Id. 

BOR’s failure in the DSEIS to analyze and disclose the rate and severity of downstream 

expansion of warmwater invasive fish resulting from entrainment, despite those data being at 

BOR’s fingertips, and its failure to discuss those data and trends in the context of threats posed to 

the Little Colorado River population of humpback chub is evasive, and it violates NEPA.

V. BOR’s Operation of Glen Canyon Dam’s Penstocks is Jeopardizing the

Listed Fish, By Facilitating (1) Entrainment and Reproduction of

Warmwater Invasive Fish, Causing an Ongoing, Worsening, and

Uncontrolled Invasion of Warmwater Nonnative Fish into the Colorado

River Downstream and Adverse Modification of Critical Habitat, and (2)

Entrainment of Bonytail, Causing Harassment, Potential Mortality and

Unauthorized Take.

a. Entrainment and Reproduction of Warmwater Invasive Fish

Conservation groups hereby incorporate by reference our March 10, 2023 comments on 

the “Glen Canyon Dam/Smallmouth Bass Flow Options Draft Environmental Assessment” and 

our November 3, 2023 comments on “Scoping for Supplemental Environmental Impact 

Statement for the December 2016 Record of Decision Entitled Glen Canyon Dam Long-Term 

Experimental and Management Plan.” 88 Fed. Reg. 68667-69 (Oct. 4 2023).

3

Invasive Fish Surveillance, Grand Canyon National Park GCDAMP - TWG, November 8, 2023. Available 

at: https://www.usbr.gov/uc/progact/amp/twg/2023-11-08-twg-meeting/20231108-

InvasiveFishSurveillanceGrandCanyonNationalPark-508-UCRO.pdf
Comments on Glen Canyon Dam LTEMP DSEIS, EIS No. 20240024. Page 5

Those comments describe “an emergency situation for humpback chub” whereby the

passage of warm water and smallmouth bass from near the surface of Lake Powell through 

penstocks of Glen Canyon Dam into the Colorado River is facilitating an ongoing, expanding 

warmwater fish invasion that threatens the survival and recovery of humpback chub. Once 

established, a reproducing population of smallmouth bass in the Grand Canyon would be 

impossible to suppress, particularly in tributary streams and warm side channels whose 

temperatures cannot be controlled via dam releases. Predation by bass would reduce the number 

and reproductive success of the largest remaining population of humpback chub at the Little 

Colorado River. This outcome would jeopardize humpback chub, sharply increase extinction 

risk, and would be catastrophic for humpback chub recovery efforts overall.

Those comments describe regulations implementing the ESA which define to “jeopardize 

the continued existence of” as “to engage in an action that reasonably would be expected, 

directly or indirectly, to reduce appreciably the likelihood of both the survival and recovery of a 

listed species in the wild by reducing the reproduction, numbers, or distribution of that species.” 

50 C.F.R. § 402.02. The comments further describe how, in this instance, pursuant to the ESA, 

the BOR must ensure that operations of Glen Canyon Dam are not likely to jeopardize the 

continued existence of humpback chub, result in the destruction or adverse modification of its 

critical habitat in Glen Canyon National Recreation Area or Grand Canyon National Park, or 

directly or indirectly reduce its reproduction, numbers, or distribution.

Since conservation groups’ March 10 and November 3, 2023 comments, BOR’s actions 

and inaction have caused the nonnative warmwater fish invasion to worsen rather than improve, 

where:

• BOR’s operation of the Glen Canyon Dam’s penstocks is causing, on an ongoing basis,

an invasion of nonnative warmwater predator fish by transporting warm water above 16

degrees Celsius and warmwater invasive fish from Lake Powell into the Colorado River.

This is facilitating the ongoing establishment, reproduction, and downstream expansion

of warmwater invasive fish populations into and immediately upstream of designated

critical habitat for razorback sucker, humpback chub, and humpback chub’s last large

source population at the Little Colorado River;

• Smallmouth bass populations have expanded an average of four river miles per month

downstream of Glen Canyon Dam since juvenile SMB were first recorded downstream of

the dam on 1 July 2022. As of October of 2023, SMB were recorded as far downstream

as mile 47; given downstream expansion of four miles per month, SMB can be expected

to have arrived at the Little Colorado River in February of 2024 and to take refuge and

reproduce in its relatively warm waters this year;

• Populations of some warmwater invasive species, like and including SMB, may be

impossible to control if they become established, and could eliminate the humpback

chub’s last large source population at the Little Colorado River. Researchers estimate that

long-term reductions in smallmouth populations require nearly 70% removal of young of

year for at least ten consecutive years. This type of intensive, long-term smallmouth bass

management is likely not physically possible in GCNRA and GCNP.
Comments on Glen Canyon Dam LTEMP DSEIS, EIS No. 20240024. Page 6

• The warmwater fish invasion owes in large part to BOR’s chronic failure and refusal to

implement required conservation measures. Conservation measures to protect humpback

chub and razorback sucker from warmwater invasive fish, as set forth in the Biological

Opinion for the Glen Canyon Dam Long-Term Experimental and Management Plan

(LTEMP Bi-Op) and relied on to support the incidental take statement, either aren’t being

implemented by BOR, or aren’t working;

o BOR has failed, and continues to fail, to implement conservation measures that

the 2016 Biological Opinion for the Glen Canyon Dam Long-Term Experimental

and Management Plan (LTEMP Bi-op) presumed would prevent the introduction

and downstream expansion of warmwater invasive fish into the Colorado River.

This includes BOR’s ongoing failure in Grand Canyon to (1) construct barriers on

the dam that prevent the passage of warmwater invasive fish, (2) eliminate sidechannel nursery habitat below the dam, like the “12-mile slough,” and (3) manage

river temperatures and flows to prevent spawning and reproduction of smallmouth

bass; and

o In the absence of measures to prevent warmwater fish from passing through Glen

Canyon Dam, “rapid response” conservation measures to control resultant

warmwater fish invasion with chemical and mechanical eradication are failing.

Despite detection and removal with chemical and mechanical treatments of 345

smallmouth bass from the Lee’s Ferry reach in October of 2022, NPS reported

667 smallmouth bass (SMB) in one portion of the Lee’s Ferry reach by August

2023, including dozens of young-of-year bass, and thousands of green sunfish,

which have become established throughout Grand Canyon. Agency monitoring

reports show downstream expansion of smallmouth bass in 2023 below the Paria

River; and

o Glen Canyon Dam discharge temperatures in 2023, as in 2022, remained above 16

degrees Celsius from early summer, thereby likely facilitating spawning,

reproduction and expansion of smallmouth bass populations below the dam in

locations beyond just the 12-mile slough.

Imminent and ongoing downstream expansion of warmwater invasive fish populations 

caused by BOR’s operation of Glen Canyon Dam’s penstocks is adversely modifying designated 

critical habitat and, with resultant predation, threatens to decimate humpback chub’s last core 

source population at the Little Colorado River. FWS’ determination of non-jeopardy in the 2016 

LTEMP Bi-Op is predicated on assumptions that do not include dam operations causing the now 

ongoing, worsening, and uncontrolled invasion of warmwater invasive fish into the Colorado 

River upstream and within designated critical habitat for humpback chub and razorback sucker. 

b. Entrainment of Bonytail

A federally endangered bonytail documented by federal biologists in the 12-Mile Slough 

was presumably entrained in Glen Canyon Dam after being stocked in into Lake Powell at 
Comments on Glen Canyon Dam LTEMP DSEIS, EIS No. 20240024. Page 7

Wahweap Bay, perhaps in October of 2022.4 Further entrainment of bonytail is possible given 

the ongoing presence and apparent reproduction of bonytail in Lake Powell. We note that Utah 

Division of Wildlife Resources’ Lake Powell larval fish sampling in 2022 was confirmed by the 

Larval Fish Laboratory at Colorado State University to have detected two bonytail protolarvae at 

lake miles 122 and 123.

VI. High Flow Experiments

Conservation groups generally support modifying HFE protocols to time HFEs in late 

spring and early summer, which more closely reflects the timing of historical high flows 

resulting from snowmelt in the Rocky Mountains. BOR should refrain from HFE experiments 

pending modification of Glen Canyon Dam penstocks with fish exclusion devices and other 

measures to ensure against further entrainment of warmwater invasive fish, and to prevent 

“flushing” warmwater invasive fish already in the Colorado River farther downstream into 

designated critical habitat for humpback chub and razorback sucker.

VII. Concurrent with the SEIS, BOR Must Immediately Advance Conservation

Measures to Prevent Nonnative Fish Entrainment and Expansion in the

Colorado River

The ongoing warmwater fish invasion now resulting from BOR’s Glen Canyon Dam 

operations and BOR’s failure since the 2016 LTEMP Bi-Op to implement conservation measures 

to prevent warmwater invasive fish from passing through the dam warrants BOR immediately

advance modifications to Glen Canyon Dam that (1) prevent passage of warmwater fish from 

Lake Powell into the Colorado River in the first place, and (2) augment sedimentation and 

increase turbidity sufficient to reduce or inhibit predation of humpback chub by smallmouth bass 

and other warmwater invasive fish.

Thus, in addition to the SEIS, BOR must immediately and concurrently initiate action to:

• Modify the dam with fish exclusion devices to prevent entrainment of warmwater

invasive fish; and

• Modify the 12-mile slough to prevent warmwater invasive fish reproduction;

BOR must also immediately and concurrently initiate action to augment sediment and 

increase turbidity downstream of the dam in order to reduce smallmouth bass predation. The 

2015 Biological Assessment for LTEMP, which preceded the 2016 Biological Opinion,

acknowledged that the failure of LTEMP to provide methods to manage river temperature and 

sediment effectively excluded from LTEMP “the most important potential conservation tools” 

for humpback chub in the Grand Canyon. It states:

Methods to actively manage temperature releases from Glen Canyon Dam sediment

4

See, for example: " Field Notes: Young Bonytail Found in Lake Powell." Available at: 

https://coloradoriverrecovery.org/blog/field-notes-young-bonytail-found-in-lake-powell/
Comments on Glen Canyon Dam LTEMP DSEIS, EIS No. 20240024. Page 8

augmentation below the Paria River are not included in the Long-Term Experimental

Management Program (LTEMP), for Glen Canyon Dam. Inclusion of infrastructure 

options including these were eliminated from detailed study in the LTEMP alternatives 

for a variety of reasons. We mention them here because these methods may still represent 

the most important potential conservation tools that could be used for the long-term 

conservation of HBC in Grand Canyon and the concepts should not be lost.5

VIII. BOR and FWS Must Consider Climate Change, Regional Aridification,

Declining Colorado River Flows and Lake Powell Elevations, That All

Contribute to Warmwater Fish Invasion Downstream of Glen Canyon Dam,

As Part of the Degraded Baseline Conditions in Consultation for Humpback

Chub and Razorback Sucker

The ESA mandates that all the impacts of the agency’s discretionary activities on listed 

species, such as BOR’s operation of Glen Canyon Dam, be assessed as an effect, not as part of 

the environmental baseline, in determining jeopardy. This principle was reaffirmed during the 

rulemaking process for the 2019 revisions to the 402 consultation regulations. 84 Fed. Reg. 

44,976, 44,978 (“discretionary activities . . . that are part of the proposed action but for which no 

change is proposed” are to be analyzed “as part of the effects of the action, even those operations 

that the Federal agency proposes to keep the same.”).

Establishing an environmental baseline that fails to consider factors harming the species 

or degrading the species’ habitat violates the ESA. See, e.g., Am. Rivers & Ala. Rivers All. v. 

FERC, 895 F.3d 32, 46-47 (D.C. Cir. 2018) (holding Fish and Wildlife Service acted arbitrarily 

in establishing a baseline that failed to consider degradation caused by power plant); Nat’l 

Wildlife Fed’n v. Nat’l Marine Fisheries Serv., 524 F.3d 917, 929 (9th Cir. 2008) (finding that a 

biological opinion violated ESA where it did not “incorporate degraded baseline conditions into 

its jeopardy analysis.”). 

Here, BOR and FWS must consider in the context of consultation the observed and 

predicted future climate change, regional aridification, Colorado River flow declines, declines in 

Lake Powell surface elevations, and resulting transport of warm water and warmwater invasive 

fish from Lake Powell into the Colorado River as degraded environmental baseline conditions 

that are degrading designated critical habitat for humpback chub and razorback sucker. 

IX. Department of the Interior Agencies Must Plan Now for Endangered Species

Survival and Recovery Amidst Climate-inevitable Minimum Power Pool,

Dead Pool, Obsolescence of Glen Canyon Dam and Lake Powell, and A

Warm Colorado River Through Grand Canyon. This Should Include

Developing Replacement Power and Planning a Phased Decommissioning of

Glen Canyon Dam.

BOR and its sister agencies (NPS, USFWS) must undertake planning now to ensure the 

survival, and recovery of threatened and endangered fish in the context of minimum power pool, 

5

 LTEMP Biological Assessment at D-4.
Comments on Glen Canyon Dam LTEMP DSEIS, EIS No. 20240024. Page 9

dead pool, and a warm Colorado River flowing through Grand Canyon. Worsening greenhouse 

gas pollution, regional warming, aridification, and Colorado River flow declines provide little 

assurance that, in the long term, sufficient water will be available to maintain Lake Powell levels 

to ensure critical cold water flows from Glen Canyon Dam to protect fish can be achieved. BOR 

and its sister agencies’ duty to “carry out programs for the conservation”—i.e., recovery of listed 

species, should compel planning now to ensure for the survival and recovery of threatened and 

endangered fish. 

This must include planning for the climate inevitable obsolescence of Glen Canyon Dam 

and Lake Powell, and, in that context, it must provide for replacement power, a phased 

decommissioning of the dam, and associated engineering solutions that will exclude non-native 

fish invasion, maintain Grand Canyon as a native fish stronghold in the Colorado River system, 

and provide for the survival and recovery of endangered fish in the mainstem of the Colorado 

River in Glen Canyon National Recreation Area and Grand Canyon National Park. 

Thank you for your consideration of these comments. Please do not hesitate to contact us 

with questions.

Sincerely,

Taylor McKinnon

Southwest Director

Center for Biological Diversity

P.O. Box 1178

Flagstaff, AZ 86002-1178

(801) 300-2414

tmckinnon@biologicaldiversity.org

John Weisheit

Conservation Director

Living Rivers & Colorado Rivekeeper

PO Box 466

Moab, UT 84532

(435) 260-2590

Sandy Bahr

Chapter Director Executive Director

Sierra Club - Grand Canyon Chapter

514 W. Roosevelt St. 

Phoenix, AZ 85003 

(602) 253-8633 

sandy.bahr@sierraclub.org
Comments on Glen Canyon Dam LTEMP DSEIS, EIS No. 20240024. Page 10

Kyle Roerink

Executive Director

Great Basin Water Network

PO BOX 75

Baker, NV 89311

kyleroerink@greatbasinwater.org

Attachments:

March 10, 2023 comments on “Glen Canyon Dam/Smallmouth Bass Flow Options Draft 

Environmental Assessment.”

November 3, 2023 comments on “Scoping for Supplemental Environmental Impact Statement 

for the December 2016 Record of Decision Entitled Glen Canyon Dam Long-Term Experimental 

and Management Plan.” 88 Fed. Reg. 68667-69 (Oct. 4 2023).
Comments on Glen Canyon Dam/Smallmouth Bass Flow Options Draft EA Page 1

10 March 2023

SENT VIA ELECTRONIC MAIL

Responsible Officials

US Department of the Interior

Bureau of Reclamation

Upper Colorado Basin Region

125 South State Street, Room 8100

Salt Lake City, UT 84138

gcd_smb_ea@usbr.gov

RE: Glen Canyon Dam/Smallmouth Bass Flow Options Draft Environmental Assessment

Responsible Officials:

The Center for Biological Diversity, Sierra Club Grand Canyon Chapter, Living Rivers and 

Colorado Riverkeeper, and Great Basin Water Network (“Conservation Groups”) provide the following 

comments on the Bureau of Reclamation’s (“BOR”) “Glen Canyon Dam/Smallmouth Bass Flow Options 

Draft Environmental Assessment.”

The Center for Biological Diversity is a national, non-profit conservation organization dedicated 

to protecting and recovering endangered species and the habitats upon which they depend for their 

survival. The Center has 1.7 million members and supporters, including members who use and enjoy the 

Grand Canyon the Colorado River for recreation, natural history, spiritual renewal, photography, art, 

wildlife observation and scientific study. The Center has been involved in the preservation of threatened 

and endangered species and their habitats in the Grand Canyon region for decades including protection of 

the Grand Canyon’s aquifers. Those species include the federally threatened humpback chub, the 

endangered razorback sucker, the endangered southwestern willow flycatcher, and the threatened 

Mexican spotted owl. Those habitats include the Colorado River, its springs and connected streams, and 

terrestrial habitats within and adjacent to Grand Canyon National Park’s boundaries. 

The Sierra Club’s mission is “to explore, enjoy, and protect the wild places of the earth; to 

practice and promote the responsible use of the earth’s ecosystems and resources; and to educate and 

enlist humanity to protect and restore the quality of the natural and human environments.” The Grand 

Canyon (Arizona) Chapter was formed in 1965 in order to focus attention on stopping dams in Grand 

Canyon. Our work to protect the Colorado River and Grand Canyon National Park continues today. Our 

13,000 members and supporters have a significant interest in the health of the Colorado River and the 

species that depend upon it.

Living Rivers is a non-profit corporation dedicated to the preservation, protection, and restoration 

of rivers and watersheds in the Colorado Plateau. Living Rivers works to ensure the long-term health and 

viability of human, animal, and plant species, as well as environmental quality threatened by mining and 

oil and gas operations in the region—with a principal focus of reestablishing a free-flowing Colorado 

River through Glen and Grand Canyons. Colorado Riverkeeper is a licensed organizational member of 
Comments on Glen Canyon Dam/Smallmouth Bass Flow Options Draft EA Page 2

Waterkeeper Alliance, which is a global movement of advocates working to protect rivers, streams, and 

coastlines around the world, including, through Colorado Riverkeeper, the Colorado River. 

The Great Basin Water Network (GBWN) was formed to protect the water resources of the Great 

Basin for residents, animal and plants. The Network promotes effective water conservation programs 

including economic incentives for water smart-practices as opposed to multi-million dollar projects that 

would burden urban taxpayers while leaving rural communities in jeopardy.

1. Introduction: This is An Emergency Situation for Humpback Chub

The passage of warm water and smallmouth bass from near the surface of Lake Powell through 

still-unscreened penstocks of Glen Canyon Dam, into the Colorado River, threatens the survival and 

recovery of humpback chub. Once established, a reproducing population of smallmouth bass in the Grand 

Canyon would be impossible to suppress. Predation by bass would reduce the number and reproductive 

success of the largest remaining population of humpback chub at the Little Colorado River. This outcome 

would jeopardize humpback chub, sharply increase extinction risk, and would be catastrophic for 

humpback chub recovery efforts overall.

BOR must avoid that outcome. To do so, BOR must analyze, select, and implement alternative(s) 

and flow regime(s) that (1) maximally prevent, rather than only disrupt, smallmouth bass reproduction in 

Grand Canyon, and that (2) maximally safeguard against resultant predation of humpback chub and other 

endangered, threatened, and native fish. This requires selecting flow alternatives A and B. Legal mandates

are many and clear for BOR to select flow regimes to maximally protect the humpback chub. BOR lacks

a legal mandate to prioritize flow regimes for hydropower. BOR’s analysis, selection, and implementation 

of flow regimes must advance actions maximally beneficial to the survival and recovery of federally 

listed fish to avoid jeopardy to humpback chub. Failure to do so will jeopardize humpback chub.

More broadly, BOR and its sister agencies (NPS, USFWS) must undertake planning now to 

ensure the survival, and recovery of threatened and endangered fish in the context of minimum power 

pool, dead pool, and a warm Colorado River flowing through Grand Canyon. Worsening greenhouse gas 

pollution, regional warming, aridification, and Colorado River flow declines provide little assurance that, 

in the long term, sufficient water will be available to maintain Lake Powell levels and cold water flows 

from Glen Canyon Dam. BOR and its sister agencies’ duty to “carry[] out programs for the 

conservation”—i.e., recovery of listed species, should compel planning now to ensure for the survival and 

recovery of threatened and endangered fish. This planning must consider ways to avoid, minimize, or offset impacts from warm Colorado River water flowing through Grand Canyon due to increasing risks of

long-term minimum power pool and dead pool behind Glen Canyon Dam . 16 U.S.C. § 1536(a)(l).

2. The Department of the Interior and Bureau of Reclamation Have Multiple Statutory Mandates to 

Manage Colorado River Flows to Protect Grand Canyon’s Endangered Fish and Grand Canyon 

National Park’s Natural and Cultural Values. Hydropower is “Incident” and Subservient to 

Conservation Mandates.

The Department of Interior (DOI) and BOR have multiple statutory mandates to manage flows 

from Glen Canyon Dam to protect, improve, and mitigate adverse impacts to federally endangered species 

and the natural and cultural values for which Grand Canyon National Park and Glen Canyon National 

Recreation Area were established. Because hydropower cannot be prioritized above other purposes, and 

because it is explicitly “incident” to flows for other purposes, BOR has both the authority and obligation 

to manage Glen Canyon Dam to effectively conserve water and natural resources without the additional 

burden of prioritizing the provision of hydropower from the dam. 
Comments on Glen Canyon Dam/Smallmouth Bass Flow Options Draft EA Page 3

The Secretary, acting through the Director of the National Park Service, must “promote and 

regulate the use of the National Park System by means and measures that conform to the fundamental 

purpose of the System units, which purpose is to conserve the scenery, natural and historic objects, and 

wild life in the System units and to provide for the enjoyment of the scenery, natural and historic objects, 

and wild life in such manner and by such means as will leave them unimpaired for the enjoyment of 

future generations.” 54 U.S.C. § 100101(a). 

Further, and as discussed in more detail later as it relates humpback chub, Section 7 of the 

Endangered Species Act requires that“[e]ach Federal agency shall, in consultation with and with the 

assistance of [the Services], insure that any action authorized, funded, or carried out by such agency . . . is 

not likely to jeopardize the continued existence of any endangered or threatened species or result in the 

destruction or adverse modification” of designated critical habitat. 16 U.S.C. § 1536(a)(2). The 

regulations implementing the ESA define to “jeopardize the continued existence of” as “to engage in an 

action that reasonably would be expected, directly or indirectly, to reduce appreciably the likelihood of 

both the survival and recovery of a listed species in the wild by reducing the reproduction, numbers, or 

distribution of that species.” 50 C.F.R. § 402.02.2

Here, pursuant to the ESA, the BOR must ensure that flow regimes from Glen Canyon Dam are 

not likely to jeopardize the continued existence of humpback chub, result in the destruction or adverse 

modification of its critical habitat in Grand Canyon National Park, or directly or indirectly reduce its 

reproduction, numbers, or distribution. 

The Grand Canyon Protection Act of 1992 (GCPA) specifies that Glen Canyon Dam “shall” be 

operated in a manner that is protective of Grand Canyon National Park and Glen Canyon National 

Recreation Area:

“The Secretary shall operate Glen Canyon Dam... in such a manner as to protect, mitigate 

adverse impacts to, and improve the values for which Grand Canyon National Park and Glen 

Canyon National Recreation Area were established, including, but not limited to natural and 

cultural resources and visitor use.” (Grand Canyon Protection Act (GCPA) (1992), Section 

1802(a)) 

Here, pursuant to the GCPA, BOR must operate Glen Canyon Dam to protect, improve, and 

mitigate impacts to humpback chub and the riverine ecosystem upon which it depends, and for which 

Grand Canyon National Park was established in part to protect. 

Upon its passage, GCPA’s House sponsor George Miller explained, “In the name of more electric 

power production mindless and unnecessary damage is being inflicted every day on the resources of the 

Grand Canyon, one of the most precious park resources in the world... the daily operation of Glen Canyon 

dam to produce hydroelectric power was wreaking havoc on the beaches and wildlife habitat at the 

bottom of Grand Canyon.”

Upon its passage, GCPA’s Senate sponsor John McCain explained, “widely fluctuating water 

releases from the dam, primarily for the maximum generation of hydroelectric peaking power, are 

contributing to the irreversible erosion of river beaches. It is critical to recognize that river beaches are not 

merely convenient resting spots for river rafters, hikers, and Grand Canyon campers. The beaches are 

extremely valuable biological resources which support riparian vegetation and diverse forms of wildlife. 

They are precious and fragile ecosystems which are as vital a part of the canyon as a view from the South 

rim and just as deserving of protection.” 
Comments on Glen Canyon Dam/Smallmouth Bass Flow Options Draft EA Page 4

The GCPA specifically mentions compliance with the Colorado River Storage Project Act of 

1956 (Public Law 84‐485) (CRSP), the law that authorized the construction of Glen Canyon Dam, in 

reference to water:

“The Secretary shall implement this section in a manner fully consistent with and subject to the 

Colorado River Compact, the Upper Colorado River Basin Compact, the Water Treaty of 1944 

with Mexico, the decree of the Supreme Court in Arizona v. California, and the provisions of the 

Colorado River Storage Project Act of 1956 and the Colorado River Basin Project Act of 1968 

that govern allocation, appropriation, development, and exportation of the waters of the Colorado 

River basin.” 

GCPA Sec. 1802(b).

Regarding hydropower, GCPA only discusses the need to replace Glen Canyon Dam’s power 

with other power supplies. Through the GCPA, “the values for which Grand Canyon National Park and 

Glen Canyon National Recreation Area were established” were prioritized above Glen Canyon Dam’s 

hydropower production:

“The Secretary of Energy in consultation with the Secretary of the Interior and with 

representatives of the Colorado River Storage Project power customers, environmental 

organizations and the States of Arizona, California, Colorado, Nevada, New Mexico, Utah and 

Wyoming shall identify economically and technically feasible methods of replacing any power 

generation that is lost through adoption of long-term operational criteria for Glen Canyon Dam as 

required by Section 1804 of this title. The Secretary shall present a report of the findings, and 

implementing draft legislation, if necessary, not later than two years after adoption of long-term 

operating criteria. The Secretary shall include an investigation of the feasibility of adjusting 

operations at Hoover Dam to replace all or part of such lost generation. The Secretary shall 

include an investigation of the modifications or additions to the transmission system that may be 

required to acquire and deliver replacement power.”

GCPA, Sec. 1809.

Hydropower generation is “incident” to other purposes set forth in the Colorado River Storage 

Project Act of 1956 (Public Law 84‐485), the act which authorized Glen Canyon Dam. The Secretary of 

the Interior was authorized to “construct, operate, and maintain” Glen Canyon Dam: 

“. . . for the purposes, among others, of regulating the flow of the Colorado River, storing water 

for beneficial consumptive use, making it possible for the States of the Upper Basin to utilize, 

consistently with the provisions of the Colorado River Compact, the apportionments made to and 

among them in the Colorado River Compact and the Upper Colorado River Basin Compact, 

respectively, providing for the reclamation of arid and semiarid land, for the control of floods, 

and for the generation of hydroelectric power, as an incident of the foregoing purposes...” 

43 U.S.C. §620 (emphasis added).

The DOI and BOR have a clear responsibility to use Glen Canyon Dam to manage water 

according to the obligations in CRSP and GCPA. Because hydropower cannot be prioritized above other 

purposes under CRSP and GCPA, BOR has the authority and duty to manage Glen Canyon Dam to 

effectively conserve water and natural resources without the additional burden of providing hydropower 

from the dam. 
Comments on Glen Canyon Dam/Smallmouth Bass Flow Options Draft EA Page 5

Because of this, we recommend that BOR add to the description of the Colorado River Storage 

Project (CRSP) Act (April 11, 1956) in the EA at I-5 the following: The purpose of the storage projects is 

for water storage, flow regulation, and flood control, with hydroelectric power “as an incident of” the 

other purposes.

BOR and DOI must fulfill the Secretary of Interior’s obligation to operate the dam “in such a 

manner as to protect, mitigate adverse impacts to, and improve” Grand Canyon, and to operate the dam in 

such a way that does not reduce the reproduction, numbers, or distribution of federally threatened 

humpback chub. 

3. BOR’s Operation of Glen Canyon Dam Must Prevent Jeopardy of Federally Threatened Humpback 

Chub and Reductions of its Reproduction, Numbers, or Distribution. Failure by BOR to Prevent a 

Reproducing Smallmouth Bass Population in the Colorado River of Glen, Marble, or Grand Canyons, 

or to Select an Alternative(s) or Flow Regime(s) Maximally Preventative of Small Mouth Bass 

Reproduction and Reductions in Humpback Chub Reproduction, Numbers, or Distribution, Will 

Jeopardize Humpback Chub in Violation of the Endangered Species Act

As relevant here, Section 7 of the ESA requires that “[e]ach Federal agency shall, in consultation 

with and with the assistance of [the Services], insure that any action authorized, funded, or carried out by 

such agency . . . is not likely to jeopardize the continued existence of any endangered or threatened 

species or result in the destruction or adverse modification” of designated critical habitat. 16 U.S.C. § 

1536(a)(2). To “jeopardize the continued existence of” means “to engage in an action that reasonably 

would be expected, directly or indirectly, to reduce appreciably the likelihood of both the survival and 

recovery of a listed species in the wild by reducing the reproduction, numbers, or distribution of that 

species.” 50 C.F.R. § 402.02.2 

This “mandate applies to every discretionary agency action—regardless of the expense or burden 

its application might impose.” Nat’l Ass’n of Home Builders v. Defs. of Wildlife, 551 U.S. 644, 671 

(2007) (emphasis added).

Formal Section 7 consultation may result in the issuance of a biological opinion, however, 

“[c]onsulting with the [Fish and Wildlife Service] alone does not satisfy an agency’s duty under the

Endangered Species Act.” Res. Ltd. v. Robertson, 35 F.3d 1300, 1304 (9th Cir. 1994). The BOR would 

violate the ESA if it approves or implements an action in reliance on a legally flawed biological opinion 

or fails in its approval or implementation decision “to discuss information that would undercut the 

[biological] opinion’s conclusion.” Ctr. for Biological Diversity v. U.S. BLM, 698 F.3d 1101, 1127-28 

(9th Cir. 2012); see also WildEarth Guardians v. Steele, 545 F. Supp. 3d 855, 881 (D. Mont. 2021) 

(“Ignoring information that would undercut the [biological] opinion’s conclusions violates the [agency’s] 

obligation under § 7 of the ESA.”).

The ESA and section 7 consultation regulations mandate that biological opinions incorporate a 

comprehensive, aggregative approach to the effects analysis. The longstanding

regulatory definition for “effects of the action” includes direct, indirect, and interrelated threats that are 

added to the environmental baseline in order to determine jeopardy. 50 C.F.R. § 402.02. The Ninth 

Circuit has held that a species may be jeopardized even “if there is no appreciable reduction of survival 

odds” because “a species can often cling to survival even when recovery is far out of reach.” Nat’l 

Wildlife Fed’n v. Nat’l Marine Fisheries Serv., 524 F.3d 917, 931 (9th Cir. 2008). 

The regulations recognize that “reducing the reproduction” of a species may jeopardize the 

species’ survival or recovery. 50 C.F.R. § 402.02. Thus, Fish and Wildlife Service “must analyze effects 

on recovery as well as effects on survival.” Nat’l Wildlife Fed’n, 524 F.3d at 932. Under the ESA, 
Comments on Glen Canyon Dam/Smallmouth Bass Flow Options Draft EA Page 6

“[r]ecovery means improvement in the status of listed species to the point at which listing is no longer 

appropriate under the criteria set out in section 4(a)(1) of the Act.” 50 C.F.R. § 402.02. 

The ESA mandates that all the impacts of the agency’s discretionary activities on listed species, 

such as BOR’s operation of Glen Canyon Dam, be assessed as an effect, not as part of the environmental 

baseline, in determining jeopardy. This principle was reaffirmed during the rulemaking process for the 

2019 revisions to the 402 consultation regulations. 84 Fed. Reg. 44,976, 44,978 (“discretionary activities . 

. . that are part of the proposed action but for which no change is proposed” are to be analyzed “as part of 

the effects of the action, even those operations that the Federal agency proposes to keep the same.”).

Establishing an environmental baseline that fails to consider factors harming the species or 

degrading the species’ habitat violates the ESA. See, e.g., Am. Rivers & Ala. Rivers All. v. FERC, 895 

F.3d 32, 46-47 (D.C. Cir. 2018) (holding Fish and Wildlife Service acted arbitrarily in establishing a 

baseline that failed to consider degradation caused by power plant); Nat’l Wildlife Fed’n v. Nat’l Marine 

Fisheries Serv., 524 F.3d 917, 929 (9th Cir. 2008) (finding that a biological opinion violated ESA where 

it did not “incorporate degraded baseline conditions into its jeopardy analysis.”).

As a result, in order for the Bureau of Reclamation to meet the requirements of the ESA, it must 

engage in consultation with the Service to “insure” that the proposed actions, including existing 

operations, are “not likely to jeopardize” the continued existence of listed species. 16 U.S.C. § 1536(a)(2). 

a. The fate of the Little Colorado River humpback chub population is critical to the species’ 

overall survival and recovery.

The Little Colorado River population of humpback chub is the species’ largest remaining 

population. More than 90% of humpback chub exist in Grand Canyon; the majority of these comprise the 

Little Colorado River population. Its size, reproductive success, and its role as a source population for 

translocations and dispersal make it critically important to the overall survival and recovery of humpback 

chub as a species. The importance of the Little Colorado River population is heighted further by the

tenuous, declining, and uncertain status of remaining Upper Basin humpback chub populations.

Only five populations of humpback chub persist in the Colorado River basin. Four small and 

tenuous populations are in the upper Colorado River basin (Black Rocks, Westwater Canyon, 

Desolation/Gray Canyons, and Cataract Canyon) and one in lower basin population in the Grand Canyon, 

comprised primarily of fish in the Little Colorado River.1 The U.S. Fish and Wildlife Service now 

considers a sixth upper basin population in Dinosaur National Monument to be functionally extirpated.2 

The Little Colorado River at and upstream of the Colorado River confluence harbors the largest 

remaining population of humpback chub in the Colorado River Basin, and the most important remaining 

habitat its survival and recovery. This reach of the Little Colorado River provides eight miles of 

designated critical habitat3and 11 miles of occupied habitat (inclusive of critical habitat).4

1 Humpback Chub (Gila cypha) 5-Year Review: Summary and Evaluation. 2017. U.S. Fish and 

Wildlife Service Mountain-Prairie Region Lakewood, Colorado. At 3.

2

Id.

3 U.S. Fish and Wildlife Service. 2017. Species status assessment for the Humpback Chub (Gila 

cypha). U.S. Fish and Wildlife Service, Mountain-Prairie Region (6), Denver, CO. At 64.

4 Van Haverbeke, David, Kirk Young, Dennis Stone and Michael Pillow. 2017. Mark-Recapture 

and Fish Monitoring Activities in the Little Colorado River in Grand Canyon from 2000 to 2016. 

U.S. Fish and Wildlife Document: USFWS-AZFWCO-FL-16-02. At 11. Accessed 12 Nov 
Comments on Glen Canyon Dam/Smallmouth Bass Flow Options Draft EA Page 7

The importance of the Little Colorado River population to the humpback chub’s overall survival 

and recovery is heightened by the comparatively tenuous and uncertain status of the four remaining upper 

basin populations. In contrast to long-term declining humpback chub populations in the Upper Basin, 

which are comprised by a total of perhaps only 3600 individual fish,5the Little Colorado River is 

considered to be the “core” population of humpback chub in the Grand Canyon;6this population 

reproduces successfully and is stable and self-sustaining with 11,500 to 12,000 individuals.7In the Upper 

Basin, the U.S. Fish and Wildlife notes that the Black Rocks and Westwater Canyon populations 

“declined through 2007,” that “declines have potentially been arrested,” but that “there is uncertainty 

about this hypothesis.”8 The “abundance estimate data is insufficient to reach any reliable conclusion 

about the trajectory of the Desolation/Gray canyons population” and that “the Cataract Canyon population 

is small and the trajectory of adult numbers is unclear.”9 

In addition to being the largest remaining population of humpback chub world, the Little 

Colorado River population is a source population that supports dispersal into the mainstem Colorado 

River and translocations establishing new populations in service of survival and recovery.10 Humpback 

chub in Grand Canyon are potadromous (fish that do not migrate to the ocean at any time during their life 

cycle); adults migrate from the Colorado to the Little Colorado River in the spring to spawn; young 

humpback chub then rear in the Little Colorado River and emigrate out of the Little Colorado River by 

seasonal flood events, likely thereby populating several small aggregations of humpback chub in the 

mainstem Colorado River where reproduction is for the most part absent.11 In addition to dispersal, the 

Little Colorado River population is the source population for translocation efforts in Grand Canyon. The 

U.S. Fish and Wildlife Service’s 2017 Species Status Assessment for the Humpback Chub (Gila cypha)

states:

A total of 2,971 juvenile Humpback Chub were translocated from the lower LCR [Little Colorado 

River] to above Chute Falls (RK 16.2) during 2003–2015 (citation omitted); many have survived 

and remained in the reach, and ripe and spent fish indicate that spawning is taking place (Stone 

2019: 

http://gcdamp.com/images_gcdamp_com/7/7a/VanHaverbeke_et_al_2017_USFWS_Mark_recap

ture_and_fish_monitoring_activies_in_the_LCR_2000-2016.pdf

5 U.S. Fish and Wildlife Service. 2017. Species status assessment for the Humpback Chub (Gila 

cypha). U.S. Fish and Wildlife Service, Mountain-Prairie Region (6), Denver, CO. At 101.

6

Id at ix.

7

Id.

8

Id.

9

Id.

10 Van Haverbeke, David, Kirk Young, Dennis Stone and Michael Pillow. 2017. MarkRecapture and Fish Monitoring Activities in the Little Colorado River in Grand Canyon from 

2000 to 2016. U.S. Fish and Wildlife Document: USFWS-AZFWCO-FL-16-02. At 10. 

Accessed 12 Nov 2019: 

http://gcdamp.com/images_gcdamp_com/7/7a/VanHaverbeke_et_al_2017_USFWS_Mark_recap

ture_and_fish_monitoring_activies_in_the_LCR_2000-2016.pdf

11 Id.
Comments on Glen Canyon Dam/Smallmouth Bass Flow Options Draft EA Page 8

2016). A total of 1,650 juvenile Humpback Chub were translocated from the LCR [Little 

Colorado River] to lower Havasu Creek during 2011–2015 (see section 4.5, Table 15); many have 

survived and remained in the tributary, and young unmarked fish found in 2014, 2015, and 2016 

indicate that successful reproduction has taken place (citation omitted).12

Taken together, the health and stability of the Little Colorado River population and success of 

translocations have yielded an expansion of humpback chub populations over the past decade in the 

Lower Basin that undergirded the recommendation to downlist the chub from endangered to threatened 

status.13 

b. Establishment of a smallmouth bass population in the Colorado River of Grand Canyon 

because of Glen Canyon Dam operations would jeopardize humpback chub by reducing the 

reproduction, numbers, and distribution of the Chub’s Little Colorado River population.

Section 7 of the ESA requires that “[e]ach Federal agency shall, in consultation with and with the 

assistance of [the Services], insure that any action authorized, funded, or carried out by such agency . . . is 

not likely to jeopardize the continued existence of any endangered or threatened species or result in the 

destruction or adverse modification” of designated critical habitat. 16 U.S.C. § 1536(a)(2). To “jeopardize 

the continued existence of” means “to engage in an action that reasonably would be expected, directly or 

indirectly, to reduce appreciably the likelihood of both the survival and recovery of a listed species in the 

wild by reducing the reproduction, numbers, or distribution of that species.” 50 C.F.R. § 402.02.2

Here, BOR’s operation of Glen Canyon Dam, by passing warm water and smallmouth bass from 

Lake Powell into the Colorado River downstream, threatens jeopardy of humpback chub by facilitating 

the establishment of smallmouth bass populations that will reduce the reproduction, numbers, and 

distribution of humpback chub. 

There is little evidence to suggest that the failure to prevent the establishment and reproduction of 

a smallmouth bass between the Little Colorado River and Glen Canyon Dam would not decimate the 

Little Colorado River population’s recruitment and overall size. To the contrary, abundant information 

indicates that humpback chub are vulnerable to predation by smallmouth bass generally,14 that survival 

and recovery requires habitat with few nonnative predators so that young survive and recruit into selfsustaining populations,

15 that smallmouth bass predation has likely decimated breeding populations of 

humpback chub in the Yampa river,16 and that the Little Colorado River population of humpback chub 

may be particularly prone to predation by non-native fish should a population become established in 

Grand Canyon.17 

12 U.S. Fish and Wildlife Service. 2017. Species status assessment for the Humpback Chub (Gila 

cypha). U.S. Fish and Wildlife Service, Mountain-Prairie Region (6), Denver, CO. 

13 Humpback Chub (Gila cypha) 5-Year Review: Summary and Evaluation. 2017. U.S. Fish and 

Wildlife Service Mountain-Prairie Region Lakewood, Colorado. At 13, 15.

14 U.S. Fish and Wildlife Service. 2017. Species status assessment for the Humpback Chub (Gila 

cypha). U.S. Fish and Wildlife Service, Mountain-Prairie Region (6), Denver, CO. At 24.

15 Id at iiv.

16 Id at 116.

17 Marsh, P.C., and M.E. Douglas. 1997. Predation by introduced fishes on endangered Humpback 

Chub and other native species in the Little Colorado River, Arizona. Transactions of the American 

Fisheries Society 126: 343–346.
Comments on Glen Canyon Dam/Smallmouth Bass Flow Options Draft EA Page 9

c. BOR should select “Cool Mix with Flow Spikes” and “Cool Mix” options (Flow Options B 

and A) to maximally prevent (rather than just disrupt) small mouth bass reproduction and 

establishment and to avoid jeopardy under the Endangered Species Act.

The emergency facing humpback chub demands BOR heed the flow recommendations of 

scientists who, informed by years of research and adaptive management, have carefully developed plans 

to experimentally manage federally listed and native fish with Glen Canyon Dam flow various regimes. 

Those actions must not be delayed. The proposed action should explicitly prioritize the actions that are 

likely to achieve the purpose and need of the EA: the “Cool Mix with Flow Spikes” and “Cool Mix” 

options (Flow Options B and A). 

BOR must prevent smallmouth bass reproduction and safeguard Grand Canyon’s fish species, 

several of which rely on Grand Canyon and its tributaries to sustain their populations. Environmental 

flow actions like this are the safest way to ensure a healthy Colorado River in Grand Canyon without 

potentially harmful and less effective chemical treatments or electrofishing. 

Importantly, drought should not be used as an excuse to postpone or cancel any flow management 

action that would benefit native fish or redistribute sediment in Grand Canyon. In 2021 and again in 2022, 

a High Flow Experiment (HFE) was skipped despite U.S. Geological Survey scientists reporting the 

proper conditions for a 192 hour (8 day) HFE for the first time ever under LTEMP, and while sandbar 

size was the lowest in ten years. BOR decided not to implement the HFE because of “concerns about pool 

elevation and the Basin Fund, although there would have been a positive effect on sediments especially 

given the unprecedented drought conditions.” This is despite the acknowledgement that HFEs do not 

affect annual water release volumes. Again, we point to the Grand Canyon Protection Act, which is clear 

about the mandate to “operate Glen Canyon Dam... in such a manner as to protect, mitigate adverse 

impacts to, and improve” Grand Canyon. 

Flow spikes, which are likely to improve the effectiveness of the proposed action, should be 

employed every time there is enough sediment to ensure that beaches and sandbars will be improved, and 

never when sediment models predict detrimental impacts to sediment resources. Since sediment resources 

are favorable in 2023, a flow spike should absolutely be implemented with the Cool Mix (Flow Option B 

- Cool Mix with Flow Spikes) during the spring or summer of 2023.

BOR should implement Flow Options A and B because they are likely to “disrupt or prevent

spawning of smallmouth bass and other nonnative, invasive warmwater fish species.” EA at 3-7

(emphasis added). BOR should not rely on Flow Options C and D because, instead of preventing 

spawning, these flows are only designed to disrupt spawning, and are only likely to “result in population 

decreases” for fish that “are spawning at the time of these releases.” EA at 3-7. 

To be clear: Flow Options C and D risk decimating the Little Colorado River population and 

jeopardy to humpback chub overall by failing to prevent spawning of smallmouth bass. BOR, to ensure 

against jeopardy, must select alternatives and flow regimes that maximally prevent smallmouth bass 

spawning and reproduction, and that in turn maximally safeguard the humpback chub’s Little Colorado 

River population. 

For these reasons, we urge that BOR select and implement actions that are likely to achieve the 

purpose and need of the EA by preventing smallmouth bass spawning: the “Cool Mix with Flow Spikes” 

and “Cool Mix” options (Flow Options B and A). Flow Spikes should be employed every time there is 

enough sediment to ensure that beaches and sandbars will be improved, and never when sediment models 

predict detrimental impacts to sediment resources. In order to implement flow spikes during 2023 and in 
Comments on Glen Canyon Dam/Smallmouth Bass Flow Options Draft EA Page 10

other years when sediment is optimal, BOR must time dam maintenance activities to ensure that flow 

through the dam is not reduced when a flow spike is needed to protect Grand Canyon resources.

d. Given the likelihood that the establishment of smallmouth bass populations would reduce 

the reproduction, numbers, and distribution of humpback chub in Grand Canyon, failure of 

BOR’s dam operations to prevent the establishment of smallmouth bass populations or to 

select alternative(s) maximally preventative (rather than just disruptive) of the smallmouth 

bass reproduction will jeopardize humpback chub, in violation of the Endangered Species 

Act. 

BOR must avoid jeopardy to the Grand Canyon population of the humpback chub through 

consultation. Courts have recognized Fish and Wildlife Service’s duty to consider project impacts on 

listed species on scales smaller than the entire population designated through ESA listing or recovery 

planning. See Wild Fish Conservancy v. Salazar, 628 F.3d 513, 529 (9th Cir. 2010); Gifford Pinchot Task 

Force v. U.S. Fish and Wildlife Service, 378 F.3d 1059 (9th Cir. 2004), amended by 387 F.3d 968 (9th 

Cir. 2004). In Wild Fish Conservancy, the court invalidated a biological opinion that failed to consider the 

decline of an isolated bull trout sub-population in Icicle Creek on the species as a whole. 629 F.3d at 525-

29. The biological opinion there evaluated a project’s impacts to the Icicle Creek sub-population, 

considered “the smallest local population in the Wenatchee River core area and the most vulnerable to 

extirpation.” Id. at 526. Despite this sub-population experiencing long-term negative population trends, 

the Service concluded the project would not be expected to reduce the likelihood of survival and recovery 

of the larger Columbia River interim recovery unit. Id. The court invalidated the biological opinion, 

finding that because the Icicle Creek sub-population was important to the Wenatchee River core area, a 

relative stronghold for bull trout in the upper Columbia River area, a decline in this population could 

harm recovery. Id. at 528- 29. The court held that the Service failed to articulate a rational connection 

between the facts found and the no-jeopardy conclusion made. Id. at 529. 

Similarly, in Gifford Pinchot Task Force, plaintiffs challenged the validity of several biological 

opinions alleging that they failed to consider local impacts from logging projects on the Northern spotted 

owl. 378 F.3d at 1075. The court stressed the importance of considering local impacts, stating that 

“[f]ocusing solely on a vast scale can mask multiple site-specific impacts that, when aggregated, do pose 

a significant risk to a species.” Id. (citation omitted). Here, BOR and FWS must consider the local 

impacts to the Grand Canyon population of humpback chub from the proposed dam operations in their 

ESA section 7 consultation. 

4. BOR Must Immediately Analyze and Implement Screens and Other Dam Modifications to Prevent 

Passage of Non-native Predator Fish through Glen Canyon Dam. BOR’s Failure to Prevent Passage 

of Non-native Predator Fish through Glen Canyon Dam Violates the Endangered Species Act.

BOR should immediately analyze and then implement screening upstream of Glen Canyon Dam 

or dam modifications to prevent future exotic species passage through the dam. Powell reservoir is likely 

to fluctuate around its current level into the future, continuing the risk of allowing more warm water nonnative fish in Grand Canyon, and the proposed action could also act to draw more nonnative fish through 

the dam. EA at 3-8. One possibility to prevent this is upstream screening. Because it will take some time 

to analyze the feasibility of this action, BOR should begin to study it now. By facilitating the passage of 

non-native predator fish from Lake Powell into the Colorado River through Grand Canyon, BOR’s 

ongoing operations of Glen Canyon Dam in the absence of preventative screening or other dam 

modifications threatens humpback chub and other native fish.
Comments on Glen Canyon Dam/Smallmouth Bass Flow Options Draft EA Page 11

5. Pursuant to the Endangered Species Act’s Section 7(a)(1), Department of the Interior Agencies Must 

Plan Now for Endangered Species Survival and Recovery Amidst Climate Inevitabilities of Minimum 

Power Pool, Dead Pool, and A Warm Colorado River Through Grand Canyon.

BOR and its sister agencies (NPS, USFWS) must undertake planning now to ensure the survival, 

and recovery of threatened and endangered fish in the context of minimum power pool, dead pool, and a 

warm Colorado River flowing through Grand Canyon. Worsening greenhouse gas pollution, regional 

warming, aridification, and Colorado River flow declines provide little assurance that, in the long term, 

sufficient water will be available to maintain Lake Powell levels and cold water flows from Glen Canyon 

Dam. BOR and its sister agencies’ duty to “carry[] out programs for the conservation”—i.e., recovery of 

listed species, should compel planning now to ensure for the survival and recovery of threatened and 

endangered fish. This planning must consider ways to avoid, minimize, or off-set impacts from warm 

Colorado River water flowing through Grand Canyon due to increasing risks of long-term minimum 

power pool and dead pool behind Glen Canyon Dam. 16 U.S.C. § 1536(a)(l). 

Thank you for your consideration of these comments. Please do not hesitate to contact us with 

questions.

Sincerely,

Taylor McKinnon

Senior Public Lands Advocate

Center for Biological Diversity

P.O. Box 1178

Flagstaff, AZ 86002-1178

(801) 300-2414

tmckinnon@biologicaldiversity.org

John Weisheit

Conservation Director

Living Rivers & Colorado Rivekeeper

PO Box 466

Moab, UT 84532

(435) 260-2590

Sandy Bahr

Chapter Director Executive Director

Sierra Club - Grand Canyon Chapter

514 W. Roosevelt St. 

Phoenix, AZ 85003 

(602) 253-8633 

sandy.bahr@sierraclub.org

Kyle Roerink

Executive Director

PO BOX 75

Baker, NV 89311

kyleroerink@greatbasinwater.org
Scoping Comments on SEIS for the 2016 Glen Canyon Dam LTEMP Page 1

3 November 2023

SENT VIA ELECTRONIC MAIL

US Department of the Interior

Bureau of Reclamation

Attn: LTEMP SEIS Project Manager

Upper Colorado Basin Region

125 South State Street, Room 8100

Salt Lake City, UT 84138

LTEMPSEIS@usbr.gov

RE: Glen Canyon Dam/Smallmouth Bass Flow Options SEIS

LTEMP SEIS Project Manager:

The Center for Biological Diversity, Sierra Club Grand Canyon Chapter, Living Rivers 

and Colorado Riverkeeper, and Great Basin Water Network (“Conservation Groups”) provide 

the following comments on the Bureau of Reclamation’s (“BOR”) “Notice of Intent To Prepare a

Supplemental Environmental Impact Statement for the December 2016 Record of Decision 

Entitled Glen Canyon Dam Long-Term Experimental and Management Plan.” 88 Fed. Reg. 

68667-69 (Oct. 4 2023).

This is an emergency. Operation of Glen Canyon Dam’s penstocks, by passing warm 

water and warmwater invasive fish through the dam, is causing an ongoing and worsening 

invasion of non-native predator fish in the Colorado River. This threatens to decimate humpback 

chub’s last large source population at the confluence of the Little Colorado River, thereby 

jeopardizing the entire species. “Rapid response” measures to control invasive fish population

expansion below the dam are failing. This expansion is enhanced by BOR’s ongoing, multi-year 

failure to enact conservation measures in the 2016 LTEMP Biological Opinion to modify the 

dam with fish exclusion devices to prevent entrainment and eliminate nursery habitats for 

invasive fish downstream.

Conservation Groups urge immediate action to manage flows below 16 degrees Celsius 

to prevent further smallmouth bass production and concurrent immediate action to (1) install fish 

exclusion devices on Glen Canyon Dam to prevent further passage of warmwater invasive fish 

through the dam, (2) modify the 12-mile slough to prevent further warmwater invasive fish 

reproduction and population expansion below the dam, and (3) augment sediment to increase 

turbidity and reduce smallmouth bass predation downstream of the dam. 
Scoping Comments on SEIS for the 2016 Glen Canyon Dam LTEMP Page 2

Conservation groups urge BOR to plan now for the survival and recovery of the Grand 

Canyon’s endangered in the context of the climate-inevitable obsolescence of Glen Canyon Dam 

and Lake Powell. Conservation groups urge BOR to plan a phased decommissioning of Glen 

Canyon Dam that (1) maintains the relatively intact native fishery in the Grand Canyon upstream 

of Pearce Ferry Rapid; and, in the short and long terms, (2) prevents warmwater predator fish 

from invading the Grand Canyon from upstream or downstream of the dam site and Pearce 

Ferry, and (3) facilitates the restoration of the Colorado River’s naturally warm, turbid flows

through the Grand Canyon.

I. The Conservation Groups

The Center for Biological Diversity is a national, non-profit conservation organization 

dedicated to protecting and recovering endangered species and the habitats upon which they 

depend for their survival. The Center has 1.7 million members and supporters, including 

members who use and enjoy the Grand Canyon the Colorado River for recreation, natural 

history, spiritual renewal, photography, art, wildlife observation and scientific study. The Center 

has been involved in the preservation of threatened and endangered species and their habitats in 

the Grand Canyon region for decades including protection of the Grand Canyon’s aquifers. 

Those species include the federally threatened humpback chub, the endangered razorback sucker, 

the endangered southwestern willow flycatcher, and the threatened Mexican spotted owl. Those 

habitats include the Colorado River, its springs and connected streams, and terrestrial habitats 

within and adjacent to Grand Canyon National Park’s boundaries. 

The Sierra Club’s mission is “to explore, enjoy, and protect the wild places of the earth; 

to practice and promote the responsible use of the earth’s ecosystems and resources; and to 

educate and enlist humanity to protect and restore the quality of the natural and human 

environments.” The Grand Canyon (Arizona) Chapter was formed in 1965 in order to focus 

attention on stopping dams in Grand Canyon. Our work to protect the Colorado River and Grand 

Canyon National Park continues today. Our 13,000 members and supporters have a significant 

interest in the health of the Colorado River and the species that depend upon it.

Living Rivers is a non-profit corporation dedicated to the preservation, protection, and 

restoration of rivers and watersheds in the Colorado Plateau. Living Rivers works to ensure the 

long-term health and viability of human, animal, and plant species, as well as environmental 

quality threatened by mining and oil and gas operations in the region—with a principal focus of 

reestablishing a free-flowing Colorado River through Glen and Grand Canyons. Colorado 

Riverkeeper is a licensed organizational member of Waterkeeper Alliance, which is a global 

movement of advocates working to protect rivers, streams, and coastlines around the world, 

including, through Colorado Riverkeeper, the Colorado River. 

The Great Basin Water Network (GBWN) was formed to protect the water resources of 

the Great Basin for residents, animal and plants. The Network promotes effective water 

conservation programs including economic incentives for water smart-practices as opposed to 

multi-million-dollar projects that would burden urban taxpayers while leaving rural communities 

in jeopardy.
Scoping Comments on SEIS for the 2016 Glen Canyon Dam LTEMP Page 3

II. BOR is Operating Glen Canyon Dam in an Ongoing State of Unlawful Jeopardy 

Because Dam Operations Are Causing an Ongoing, Worsening, and Uncontrolled 

Invasion of Warmwater Nonnative Fish into the Colorado River Downstream

Conservation groups hereby incorporate by reference our March 10, 2023 comments on 

the “Glen Canyon Dam/Smallmouth Bass Flow Options Draft Environmental Assessment”

(Attachment 1). 

Those comments describe “an emergency situation for humpback chub” whereby:

The passage of warm water and smallmouth bass from near the surface of Lake Powell 

through still-unscreened penstocks of Glen Canyon Dam, into the Colorado River, 

threatens the survival and recovery of humpback chub. Once established, a reproducing 

population of smallmouth bass in the Grand Canyon would be impossible to suppress. 

Predation by bass would reduce the number and reproductive success of the largest 

remaining population of humpback chub at the Little Colorado River. This outcome 

would jeopardize humpback chub, sharply increase extinction risk, and would be 

catastrophic for humpback chub recovery efforts overall.

Attachment 1 at 2.

The comments describe regulations implementing the ESA which define to “jeopardize 

the continued existence of” as “to engage in an action that reasonably would be expected, 

directly or indirectly, to reduce appreciably the likelihood of both the survival and recovery of a 

listed species in the wild by reducing the reproduction, numbers, or distribution of that species.” 

50 C.F.R. § 402.02. The comments further describe how, in this instance, pursuant to the ESA, 

the BOR must ensure that operations of Glen Canyon Dam are not likely to jeopardize the 

continued existence of humpback chub, result in the destruction or adverse modification of its 

critical habitat in Glen Canyon National Recreation Area or Grand Canyon National Park, or 

directly or indirectly reduce its reproduction, numbers, or distribution.

Since conservation groups’ March 10, 2023 comments, BOR’s actions and inaction have 

caused the nonnative warmwater fish invasion to worsen rather than improve, where:

• BOR’s operation of the Glen Canyon Dam’s penstocks is causing, on an ongoing basis, 

an invasion of nonnative warmwater predator fish by transporting warm water above 16 

degrees Celsius and warmwater invasive fish from Lake Powell into the Colorado River. 

This is facilitating the ongoing establishment, reproduction, and downstream expansion 

of warmwater invasive fish populations into and immediately upstream of designated 

critical habitat for razorback sucker, humpback chub, and humpback chub’s last large

source population at the Little Colorado River; and

• Populations of some warmwater invasive species, like smallmouth bass, may be 

impossible to control if they become established, and could eliminate the humpback 

chub’s last large source population at the Little Colorado River. Researchers estimate that 

long-term reductions in smallmouth populations require nearly 70% removal of young of 
Scoping Comments on SEIS for the 2016 Glen Canyon Dam LTEMP Page 4

year for at least ten consecutive years. This type of intensive, long-term smallmouth bass 

management is likely not physically possible in GCNRA and GCNP.

• Measures to protect the chub and sucker from warmwater invasive fish, as set forth in the 

Biological Opinion for the Glen Canyon Dam Long-Term Experimental and Management 

Plan (LTEMP Bi-Op), either aren’t being implemented by BOR, or aren’t working;

o BOR has failed, and continues to fail, to implement conservation measures that 

the 2016 Biological Opinion for the Glen Canyon Dam Long-Term Experimental 

and Management Plan (LTEMP Bi-op) presumed would prevent the introduction 

and downstream expansion of warmwater invasive fish into the Colorado River. 

This includes BOR’s ongoing failure in Grand Canyon to (1) construct barriers on 

the dam that prevent the passage of warmwater invasive fish, (2) eliminate sidechannel nursery habitat below the dam, and (3) manage river temperatures and 

flows to prevent spawning and reproduction of smallmouth bass; and

o In the absence of measures to prevent warmwater fish from passing through Glen 

Canyon Dam, “rapid response” conservation measures1to control resultant 

warmwater fish invasion with chemical and mechanical eradication are failing. 

Despite detection and removal with chemical and mechanical treatments of 345 

smallmouth bass from the Lee’s Ferry reach in October of 2022, NPS reported 

667 smallmouth bass (SMB) in one portion of the Lee’s Ferry reach by August 

2023, including dozens of young-of-year bass, and thousands of green sunfish, 

which have become established throughout Grand Canyon. Agency monitoring 

reports show downstream expansion of smallmouth bass in 2023 below the Paria 

River.

o Glen Canyon Dam discharge temperatures in 2023, as in 2022, have remained 

above 16 degrees Celsius since early summer, thereby likely facilitating 

spawning, reproduction and expansion of smallmouth bass populations below the 

dam in locations beyond just the 12 mile slough.

Imminent and ongoing downstream expansion of warmwater invasive fish populations 

caused by BOR’s Glen Canyon Dam operations is adversely modifying designated critical 

habitat and, with resultant predation, threatens to decimate humpback chub’s last core source 

population at the Little Colorado River. FWS’ determination of non-jeopardy in the 2016

LTEMP Bi-Op is predicated on assumptions that do not include dam operations causing the now 

ongoing, worsening, and uncontrolled invasion of warmwater invasive fish into the Colorado 

River upstream and within designated critical habitat for humpback chub and razorback sucker.

III. BOR Must Take Immediate Action to Modify Glen Canyon Dam Operations and 

Flows to Prevent Reproduction of Smallmouth Bass

BOR must expedite actions evaluated in the 2023 Glen Canyon Dam/Smallmouth Bass 

Flow Options Draft Environmental Assessment to manage dam operations in a way that 

1 Attachment 1 at 2. 
Scoping Comments on SEIS for the 2016 Glen Canyon Dam LTEMP Page 5

maintains river temperatures below 16 degrees Celsius and prevents (rather than merely disrupts) 

smallmouth bass reproduction and expansion downstream. We discuss this in our attached March 

2023 comment.

We support revising the sediment accounting window for the LTEMP High Flow 

Experiment (HFE) protocol to favor HFEs timed during the spring or summer and lengthening 

the window so that a spring or summer HFE could occur anytime in the spring or summer. BOR 

should refrain from HFE experiments pending modification of Glen Canyon Dam penstocks with

fish exclusion devices and other measures to ensure against further entrainment of warmwater 

invasive fish, and to prevent “flushing” warmwater invasive fish already in the Colorado River 

farther downstream into designated critical habitat for humpback chub and razorback sucker.

IV. Concurrent with the SEIS, BOR Must Immediately Advance Conservation Measures

to Prevent Nonnative Fish Entrainment and Expansion in the Colorado River

The ongoing warmwater fish invasion now resulting from BOR’s Glen Canyon Dam 

operations and BOR’s failure since the 2016 LTEMP Bi-Op to implement conservation measures 

to prevent warmwater invasive fish from passing through the dam warrants BOR immediately 

advance modifications to Glen Canyon Dam that (1) prevent passage of warmwater fish from 

Lake Powell into the Colorado River in the first place, and (2) augment sedimentation and 

increase turbidity sufficient to reduce or inhibit predation of humpback chub by smallmouth bass 

and other warmwater invasive fish.

Thus, in addition to the SEIS, BOR must immediately and concurrently initiate action to:

• Modify the dam with fish exclusion devices to prevent entrainment of warmwater 

invasive fish;

• Modify the 12 mile slough to prevent warmwater invasive fish reproduction;

BOR must also immediately and concurrently initiate action to augment sediment and 

increase turbidity downstream of the dam in order to reduce smallmouth bass predation. The

2015 Biological Assessment for LTEMP acknowledged that the failure of LTEMP to provide 

methods to manage river temperature and sediment effectively excluded from LTEMP “the most 

important potential conservation tools” for humpback chub in the Grand Canyon. It states:

Methods to actively manage temperature releases from Glen Canyon Dam sediment

augmentation below the Paria River are not included in the Long-Term Experimental

Management Program (LTEMP), for Glen Canyon Dam. Inclusion of infrastructure 

options including these were eliminated from detailed study in the LTEMP alternatives 

for a variety of reasons. We mention them here because these methods may still represent 
Scoping Comments on SEIS for the 2016 Glen Canyon Dam LTEMP Page 6

the most important potential conservation tools that could be used for the long-term

conservation of HBC in Grand Canyon and the concepts should not be lost.2

V. BOR and FWS Must Consider Climate Change, Regional Aridification, Declining 

Colorado River Flows and Lake Powell Elevations, as Contribute to Warmwater Fish 

Invasion Downstream of Glen Canyon Dam, As Degraded Baseline Conditions in 

Consultation for Humpback Chub and Razorback Sucker

The ESA mandates that all the impacts of the agency’s discretionary activities on listed 

species, such as BOR’s operation of Glen Canyon Dam, be assessed as an effect, not as part of 

the environmental baseline, in determining jeopardy. This principle was reaffirmed during the 

rulemaking process for the 2019 revisions to the 402 consultation regulations. 84 Fed. Reg. 

44,976, 44,978 (“discretionary activities . . . that are part of the proposed action but for which no 

change is proposed” are to be analyzed “as part of the effects of the action, even those operations 

that the Federal agency proposes to keep the same.”).

Establishing an environmental baseline that fails to consider factors harming the species 

or degrading the species’ habitat violates the ESA. See, e.g., Am. Rivers & Ala. Rivers All. v. 

FERC, 895 F.3d 32, 46-47 (D.C. Cir. 2018) (holding Fish and Wildlife Service acted arbitrarily 

in establishing a baseline that failed to consider degradation caused by power plant); Nat’l 

Wildlife Fed’n v. Nat’l Marine Fisheries Serv., 524 F.3d 917, 929 (9th Cir. 2008) (finding that a 

biological opinion violated ESA where it did not “incorporate degraded baseline conditions into 

its jeopardy analysis.”). 

Here, BOR and FWS must consider in the context of consultation the observed and 

predicted future climate change, regional aridification, Colorado River flow declines, declines in 

Lake Powell surface elevations, and resulting transport of warm water and warmwater invasive 

fish from Lake Powell into the Colorado River as degraded environmental baseline conditions 

that are degrading designated critical habitat for humpback chub and razorback sucker. 

VI. Department of the Interior Agencies Must Plan Now for Endangered Species 

Survival and Recovery Amidst Climate-inevitable Minimum Power Pool, Dead Pool, 

Obsolescence of Glen Canyon Dam and Lake Powell, and A Warm Colorado River 

Through Grand Canyon. This Should Include Planning a Phased Decommissioning 

of Glen Canyon Dam.

BOR and its sister agencies (NPS, USFWS) must undertake planning now to ensure the 

survival, and recovery of threatened and endangered fish in the context of minimum power pool, 

dead pool, and a warm Colorado River flowing through Grand Canyon. Worsening greenhouse 

gas pollution, regional warming, aridification, and Colorado River flow declines provide little 

assurance that, in the long term, sufficient water will be available to maintain Lake Powell levels 

and cold water flows from Glen Canyon Dam. BOR and its sister agencies’ duty to “carry[] out 

programs for the conservation”—i.e., recovery of listed species, should compel planning now to 

ensure for the survival and recovery of threatened and endangered fish. 
Scoping Comments on SEIS for the 2016 Glen Canyon Dam LTEMP Page 7

This planning must consider ways to avoid, minimize, or off-set impacts from warm 

Colorado River water flowing through Grand Canyon due to increasing risks of long-term 

minimum power pool and dead pool behind Glen Canyon Dam. 16 U.S.C. § 1536(a)(l). This 

must include planning for the climate inevitable obsolescence of Glen Canyon Dam and Lake 

Powell, and in that context provide for a phased decommissioning of the dam and associated 

engineering solutions that will provide for the survival and recovery of endangered fish in the 

mainstem of the Colorado River in Glen Canyon National Recreation Area and Grand Canyon 

National Park. 

Thank you for your consideration of these comments. Please do not hesitate to contact us 

with questions.

Sincerely,

Taylor McKinnon

Southwest Director

Center for Biological Diversity

P.O. Box 1178

Flagstaff, AZ 86002-1178

(801) 300-2414

tmckinnon@biologicaldiversity.org

John Weisheit

Conservation Director

Living Rivers & Colorado Rivekeeper

PO Box 466

Moab, UT 84532

(435) 260-2590

Sandy Bahr

Chapter Director Executive Director

Sierra Club - Grand Canyon Chapter

514 W. Roosevelt St. 

Phoenix, AZ 85003 

(602) 253-8633 

sandy.bahr@sierraclub.org

Kyle Roerink

Executive Director

PO BOX 75

Baker, NV 89311

kyleroerink@greatbasinwater.org