P.O. Box 40340, Tucson, AZ 85717 

Via electronic mail 

A#n. LTEMP SEIS Project Manager 

US Bureau of ReclamaAon 

Upper Colorado River Basin Region 

125 South State Street, Room 8100 

Salt Lake City, UT 84138 

 25 March 2024 

Re: DraP Supplemental Environmental Impact Statement for the Glen Canyon Dam Long-Term 

Experimental and Management Plan 

Dear Project Manager,

For the past nearly quarter of a century, Wild Arizona’s Grand Canyon Wildlands Council (GCWC) 

has vigorously and creaAvely pursued its goals by serving as an environmental stakeholder in 

the Glen Canyon Dam AdapAve Management Program, and we are inAmately familiar with the 

environmental, cultural, and economic trade-offs of Glen Canyon Dam management on the 

Colorado River ecosystem (CRE) downstream. GCWC staff and our nearly 2500 members,

supporters and volunteers visit, recreate, conduct research and restoraAon projects, and 

volunteer in Grand Canyon and the CRE. 

In this document, we provide comments to ReclamaAon in response to the Federal Register 

noAce dated February 9, 2024 (h#ps://www.federalregister.gov/documents/

2024/02/09/2024-02676/environmental-impact-statements-noAce-of-availability). We 

previously provided comments and suggesAons on the first iteraAon of the Glen Canyon Dam 

Smallmouth Bass Environmental Assessment (SMB EA) for the Long Term Experimental and 

Management Plan (LTEMP) early in 2023, and again in fall 2023 during scoping for this LTEMP 

SEIS. We expect that ReclamaAon will include consideraAon of those comments and 

suggesAons, in addiAon to those provided here to this DraP LTEMP Supplemental EIS. 

Overview 

Virtually all of the substanAve environmental comments received by ReclamaAon during

scoping and in the previous SMB EA recognized the urgent need for acAon with regards to the 

on-going invasion of highly predatory smallmouth bass (SMB) downstream in Glen Canyon. That 

invasion is taking place primarily because southwestern aridificaAon is reducing water levels in 

Lake Powell, leading to warmer water releases downstream and condiAons that allow SMB and 

other piscivorous non-naAve fish to survive and reproduce in the Glen Canyon Dam tailwaters. 

Based on much knowledge of SMB impacts on naAve fish populaAons in the upper Colorado 

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River Basin and elsewhere, this invasion poses extreme threats to the existence and condiAon of 

naAve fish populaAons in Grand Canyon, parAcularly those of Threatened Humpback Chub. 

We expect ReclamaAon to use the results of this SEIS to respond immediately and vigorously to 

the SMB invasion by integraAng diverse measures across mulAple Ame scales to reduce or 

eliminate SMB and prevent other non-naAve piscivorous species establishment downstream 

from Glen Canyon Dam. 

As stated in the DraP SEIS, “...reducAons in water temperature combined with changes in flow

velocity may be vital tools that can be used to disrupt smallmouth bass from successfully 

spawning and establishing a populaAon.” Consequently, ReclamaAon’s purpose with this SEIS is 

to idenAfy methods to prevent this from happening by proposing mulAple release (flow) opAons 

from the dam that cool the river below 160C and introduce unfavorable flow velociAes for SMB 

spawning. 

The second issue addressed among all the alternaAves is revision of the annual sediment 

accounAng period and HFE implementaAon window. High flow events are essenAal for 

conservaAon of fine sediment mass balance, and springAme is the period when such floods 

occurred in pre-dam Ame. Because many naAve species and ecological processes are Amed with 

springAme, rather than autumn, high flows, GCWC strongly endorses revision of the sediment 

accounAng period and implementaAon window, which benefit not only the naAve species, but 

also other resources Aed to sandbars and sediment availability, including river running 

recreaAon—by rejuvenaAng camping beaches immediately prior to the summer recreaAon 

season. But such policy revisions will not protect river sandbars if, as occurred in 2023, a 

springAme flood is followed by conAnuously elevated summer flows. SpringAme high flow

events should be the norm, not the excepAon, for conservaAon of sediment mass balance. 

In addiAon to the No AcAon alternaAve, the DraP SEIS analyzes five flow-opAon alternaAves

with changes to the HFE protocols across all five:

Cool Mix 

Cool Mix with Flow Spikes 

Cold Shock 

Cold Shock with Flow Spikes 

Non-Bypass Alterna;ve 

ReclamaAon does not idenAfy an agency-preferred alternaAve, and we recognize it is not 

required to do so under the agency’s NEPA handbook. 

In summary of our comments below, GCWC supports a final SEIS alterna:ve that advances

and combines all 4 ‘include-bypass’ flow alterna:ves into a clearly defined experimental and 

adap:ve management framework and we strongly oppose the ‘non-bypass’ alterna:ve. Such 

an experimental and adapAve framework should include specific hypotheses to be tested, data 

collecAon through appropriate monitoring, comprehensive analysis of results, and flexibility to 

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facilitate adapAve design of subsequent flow opAons: star:ng ini:ally with Cool Mix with a 

single Flow Spike—designed as an appropriately :med Spring HFE (in the context of the 

changes to the HFE protocols and with flexibility for repeAAon as fit the availability of sediment 

and water in the system). 

An experimental and adapAve approach is necessary given the urgency and scienAfic 

uncertainty around effecAve control of SMB, Green Sunfish, and other non-naAve piscivores in

this system, and because mulAple flow configuraAons, other non-flow opAons, and altered 

Aming of implementaAon may be needed. IntegraAon of monitoring informaAon, and feedback 

that improves management are crucial to long-term success of this effort, and hopefully will 

help saAsfy the BOR’s SecAon 10 responsibiliAes to species listed under the Endangered Species 

Act.

The Non-Bypass Alterna6ve

The Non-Bypass alterna5ve will have significant nega5ve and unacceptable impacts on mul5ple

resources including loss of sediment and damage to ecological and cultural resources/integrity,

riparian and aqua5c resources, and river based recrea5onal resources, and therefore should be

avoided altogether. Under the Non-Bypass AlternaAve, flows could swing between a low of 

2,000 cfs to a high of over 27,000 cfs. This is contrary to the stated goals of the Grand Canyon 

ProtecAon Act and flies in the face of findings from several decades of research and monitoring,

which both informed the LTEMP ROD and emerged during its implementaAon to date. As we

stated during scoping, analysis of impacts under this alternaAve needed to be conducted across 

mulAple Ame scales in order to be valid representaAons. 

We restate here that impacts from any acAons undertaken should not unfairly burden any one 

group, and such burdens as may arise from such management acAons should be recognized by

ReclamaAon and miAgated, where possible. However, the threats posed by non-na5ve SMB and 

other species invasions are dire and very likely irreversible. Therefore, GCWC does not support 

limitaAons on management acAons to benefit hydroelectric power producAon or downstream 

water delivery that may reduce the effecAveness of the flow management acAons. Such 

limitaAons could ulAmately increase the costs to hydropower and water users by orders of 

magnitude to try to obtain minimal, or even net zero effecAveness in prevenAng exArpaAon and 

exAncAon, with SMB established, because of failure to act immediately with the greatest 

possible effecAveness. The Non-Bypass AlternaAve would be a giant step backwards, waste 

precious Ame, and would seriously hamper the Glen Canyon Dam AdapAve Management 

Program (AMP) and even potenAally its ongoing funding. 

Of addiAonal great concern is the failure of the DraP SEIS to accurately portray the impacts from 

the Non-Bypass AlternaAve on sandbars/camping beaches by staAng that ‘camping 

opportuniAes would be affected to a similar extent as under the other acAon alternaAves.’ This

assessment appears faulty in light of years of evidence showing dramaAc flow fluctuaAons 

adversely affect sediment resources, especially during periods with inadequate sediment mass 

balance in the system. It concludes by summarizing that the Non-Bypass AlternaAve would

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adversely affect whitewater boaAng due to low minimum flows but makes no menAon of its 

impact to camping beaches and therefore sandbars and riparian habitats, along with cultural 

resources. In the context of recreaAon alone, from navigability/safety, to trip management, to 

the quality of the recreaAonal resource and recreaAonal experience, the Non-Bypass AlternaAve

is unacceptable and unworkable. AddiAonally, as two decades of observaAon of SMB in the 

Upper Colorado River basin demonstrate, turbidity does not deter SMB and therefore reliance 

on turbidity but not colder dam releases is likely to prove disastrous for naAve fish downstream,

and threatened Humpback Chub in parAcular. 

Integrated Flow Op6ons/Experiments Adap6ve Management Alterna6ve

GCWC strongly supports integraAng all 4 ‘with bypass’ flow alternaAves as experiments into an 

AdapAve Management AlternaAve in an experimental framework, consistent with the LTEMP,

the GCPA, and the AMP, that includes specific hypotheses to be tested, data collecAon through 

appropriate monitoring, comprehensive analysis of results, and flexibility to facilitate adapAve

design of subsequent flow experiments: star5ng ini5ally with the Cool Mix with a single Flow 

Spike—designed as an appropriately 5med Spring HFE (assessed in the context of the proposed 

changes to the HFE protocols in this DraP SEIS, and with flexibility for repeAAon as fits the 

availability of sediment and water in the system). The monitoring and analysis associated with 

this AlternaAve should also include informaAon around interacAons with nonflow and other 

acAons intended to prevent establishment and expansion of SMB and other non-naAve

piscivorous species, including synergisAc or conflicAng effects of acAons and their Aming. We 

are concerned that mulAple Spike Flows conducted outside of the HFE protocols and HFE 

implementaAon planning/assessment have the potenAal to increase the risk of reducing 

sediment mass balance and water availability for triggering spring HFE implementaAon and/or 

reduce sandbar gains from a prior HFE. 

GCWC strongly supports the most flexible adapAve management approach possible for 

controlling or eliminaAng smallmouth bass (SMB) and other warmwater non-naAve fish and 

crayfish in this river ecosystem. All possible strategies for limiAng or controlling the 

establishment of reproducing populaAons of these highly piscivorous non-naAve species should

remain on the table and available to the river ecosystem managers. In parAcular, GCWC 

supports rigorous, effecAve, and rapidly-reported monitoring to ensure knowledge is gained,

and an acAve (where possible, proacAve) approach to management. The many large 

uncertainAes regarding success of limiAng or control of SMB and other non-naAve aquaAc 

species require that every opAon must be available to resolve these invasions, both upstream 

and downstream of the dam. 

HFE Protocol 

Grand Canyon Wildlands Council strongly supports modifying the high flow experiment (HFE) 

sediment accounAng and implementaAon schedule to improve chances of implemenAng

springAme HFEs, whenever possible. As we have recommended since 2011 and as we all saw in 

2023, Aming high flows from the dam at periods when flooding naturally (spring and early 

summer) in this river ecosystem has tremendously advantages, beneficially increasing or 

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improving shoreline habitat quality, recreaAonal camping beach area, and water and 

hydroelectric power producAon planning. ConducAng HFEs in late autumn, as has generally 

been the pracAce since 2000, is not only ecologically wasteful (sandbars erode back over the 

winter months), but also adds to the uncertainty of water availability in the criAcal early and 

mid-summer months and the remainder of the water year. AdopAng the proposed changes in 

sediment accounAng for a one-year Ameframe and implementaAon Aming whenever possible in

springAme are essenAal steps to move this important ecosystem towards the goals of the 

NaAonal Park Service and the Grand Canyon ProtecAon Act (1992), on which the LTEMP is 

founded.

Lastly regarding HFEs, and like Grand Canyon River Guides, many of the NaAve American Tribes,

and others, GCWC conAnues to urge ReclamaAon to revisit the HFE decision-making about its 

Planning and ImplementaAon (PI) team membership. More comprehensive involvement is 

criAcal to realizing the spirit of the 1992 Grand Canyon ProtecAon Act to adapAvely manage 

Glen Canyon Dam “in such a manner as to protect, miAgate adverse impacts to, and improve 

the values for which Grand Canyon NaAonal Park and Glen Canyon NaAonal RecreaAon Area 

were established”. The PI Team needs to include the voices of all AMP stakeholders, as we have 

previously requested. 

Non-flow Op6ons 

While the focus on discharge-related opAons is the primary emphasis of this SEIS, mulAple nondischarge-related control measures also are needed, such as measures that reduce throughdam transport of non-naAve fish, tailwater control efforts (including management of the -12L 

Mile Slough), and other methods. We know from the Green, Yampa, and Colorado River reaches 

above Lake Powell that establishment of SMB is a primary factor in populaAon declines of 

humpback chub and other naAve fish species outside of Grand Canyon. The Yampa River 

invasion provides the cauAonary tale of the ecological consequences that arise from failing to 

pursue intervenAon early in the non-naAve fish colonizaAon process (Dr. Rich Valdez, personal 

communicaAon). The costs involved in controlling established SMB through long-term 

management and to keep federally listed naAve fish from jeopardy and the brink of exAncAon 

there, are orders of magnitude greater than the cost of early prevenAon of establishment and 

those goals have proven impossible to obtain. We have also repeatedly heard from our Tribal 

colleagues in the AMP that taking of life in the Colorado River significantly harms indigenous 

cultural integrity and therefore should be avoided when possible. 

Our previously submi#ed analysis of non-flow-related opAons indicated that physical barrier 

screens, in-reservoir nets, floaAng barriers, turbine mortality, and electrofishing appeared to be 

equally easily accomplished and inexpensive short-term (emergency) management acAons. If all 

were to be undertaken simultaneously, these may be the best collecAve strategy considered to 

reduce the likelihood of SMB establishment. In addiAon, we recommend the use of upstream 

curtain barriers and other means of reducing transport of fish through the dam, with 

implementaAon and monitoring at ReclamaAon’s earliest possible Ame frame. 

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It also is essenAal that the -12 Mile Slough be modified to eliminate SMB and other non-naAve

aquaAc predator refuge. The proposed reducAons in size and funcAon of the Slough are a good 

soluAon. However, that process is immersed in recalcitrance based on mis-informaAon to Tribes 

and the bureaucracy of the NaAonal Park Service. The Slough is not a natural feature, but was 

created when fine sediment was flushed from the dam tailwaters in 1965, exposing the cobbles 

there. It is neither ecologically appropriate, nor within the NPS mission to maintain this 

unnatural feature that so deeply threatens the Colorado River ecosystem’s naAve fish 

populaAons. In addiAon, any acAon taken at the Slough can be undone, if the NPS so wishes. 

Therefore, there appear to be no clear reasons for the delays in this important acAon. Please 

move forward swiPly with the plan to modify the Slough to keep it from contribuAng to the 

non-naAve aquaAc species problem.

Another opAon we recommended was propagaAon and release of a large number of mature,

predatory, endangered Colorado River pikeminnow. This opAon would require low cost at a 

medium-to-long-term Ameframe, with medium levels of compliance and low implementaAon 

cost. In addiAon to applying addiAonal pressure to non-naAve fish, this opAon would help 

achieve an essenAal goal of the AMP and GCPA, namely returning a top aquaAc 

predator to the Colorado River ecosystem. Like all AlternaAves and non-flow OpAons, such an 

acAon would require conAnued monitoring, likely in perpetuity. 

We appreciate ReclamaAon’s efforts to develop this SEIS to the Long Term Experimental and 

Management Plan so that we can provide the essenAal tools, nimbleness, and flexibility 

necessary for management of this complex river ecosystem. Thank you for the opportunity to 

provide comments on this DraP SEIS. Please contact us if you have any quesAons about these 

comments, or if we can be of further assistance. 

Thank you,

Kelly Burke, Director

Dr. Larry Stevens, Senior Ecologist 

References Cited: US Bureau of Reclama/on. 2023. Glen Canyon Dam/Smallmouth Bass Flow 

Op/ons DraA Environmental Assessment (EA) Public Comment Analysis Report May 2023. US 

Bureau of Reclama/on Salt Lake City.

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