March 25, 2024

via e-mail only

LTEMP SEIS Program Manager

Bureau of Reclamation

125 South State Street, Room 800

Salt Lake City, Utah 84138

LTEMPSEIS@usbr.gov 

Re: Comments on the Draft Supplemental Environmental Impact Statement for the December 2016 

Record of Decision Entitled Glen Canyon Dam Long-Term Experimental and Management Plan

Dear LTEMP SEIS Project Manager:

The Colorado River Basin States’ Representatives (Basin States’ Representatives) submit the following 

comments regarding the Bureau of Reclamation’s (Reclamation) release of the Draft Supplemental 

Environmental Impact Statement (DSEIS) for the December 2016 Record of Decision (ROD) titled “Glen 

Canyon Dam Long-Term Experimental and Management Plan” (89 Fed. Reg. 9147) (LTEMP) published in 

the Federal Register on February 9, 2024.

Glen Canyon Dam Operations and Critical Infrastructure: 

Reclamation has made public statements regarding significant infrastructure concerns associated with 

LTEMP ROD experimental operations at Glen Canyon Dam and releases through the River Outlet Works 

(ROW). The most recent such statement was provided by the Secretary of the Interior’s Acting Designee 

during the February 28-29, 2024 meeting of the Adaptive Management Work Group. While the Basin 

States’ Representatives support Reclamation’s efforts to address the threat of warmwater nonnative 

species, we oppose proposed experimental operations that use the ROW if such operations may 

negatively affect the rights afforded to the Colorado River Basin States through the Law of the River. 

While the DSEIS indicates that the ROW flow releases could be reduced to half tube increments, it is not 

clear what potential impacts may occur if the ROW are used at a reduced rate at any given reservoir 

elevation and for an extended duration. The operation of the ROW for experimental environmental 

flows should be an opportunity to further our understanding of their integrity and vulnerabilities. 

Therefore, thorough inspections and observations should occur before and after potential 

implementation of the flow options, maintenance should be consistent and preventative, and 

experimental flows should not occur if there is a risk that they will cause irreparable damage to the 

ROW.
Re: Basin States’ comments on the Draft SEIS to the 2016 LTEMP ROD

March 25, 2024

Page 2 of 5

Support for Addressing Warmwater Nonnative Species Threats: 

The Basin States’ Representatives support Reclamation’s efforts to address the threat of smallmouth 

bass and other high-risk warmwater nonnative species and see this as an immediate concern. The Basin 

States’ Representatives understand that the flow options discussed in the DSEIS are potential actions to 

assist in the prevention of warmwater nonnative fish species establishment to protect the humpback 

chub, a federally listed species under the Endangered Species Act.

 

While the actions in the DSEIS are experimental in nature and of a limited duration, the long-term 

management of an invasive species is often far more costly than short-term prevention efforts. The 

Basin States’ Representatives would like to see actions taken to address the threat of warmwater 

nonnative fish in the Colorado River ecosystem and maintain that a multi-faceted approach, such as 

potential installation of a fish exclusion device and modification of the -12-mile slough, are necessary.

 

The need for actions to prevent the establishment of warmwater nonnative fish species has been 

acknowledged by the Glen Canyon Dam Adaptive Management Program (GCDAMP). A consensus-based 

document titled “Invasive Fish Species Below Glen Canyon Dam: A Strategic Plan to Prevent, Detect, and 

Respond” (Strategic Plan) was recommended for adoption by the Secretary of the Interior by the 

GCDAMP’s Adaptive Management Work Group in February of 2023. The Strategic Plan as well as the 

“Proposal to Amend the High-Flow Experiment Protocol and other Considerations” (HFE Amendment 

Proposal), are guiding documents from the GCDAMP. The Basin States’ Representatives support 

continued reliance on these reference documents in the DSEIS.

Flow Option Alternatives: 

It is recommended that Reclamation include in the preferred alternative the full array of flow option 

alternatives analyzed in the DSEIS. As the actions are experimental in nature, the use of a range of 

potential flows will allow adaptive management to address changing conditions on the river. The 

implementation of the various flow options would be subject to warmwater nonnative fish population 

size and distribution, hydrology, reservoir elevations, water temperature, and potential impacts to 

infrastructure.

 

While the DSEIS acknowledges the choice in temperature target of 15.5°C (Chapter 3, page 3-70) for the 

flow options was based on observations of smallmouth bass in the Upper Colorado River Basin, the 

Basin States’ Representatives want to acknowledge the potential for smallmouth bass to spawn at 

temperatures as low as 12.5°C in other systems as indicated in Figure 3-23, page 3-55. While many 

factors play into a species spawning success, it is imperative that Reclamation consider this range in 

temperature while evaluating the effectiveness of the proposed actions. If smallmouth bass are found 

to be spawning in the Colorado River at temperatures below the 15.5°C target, flow options should be 

reevaluated and potentially discontinued.
Re: Basin States’ comments on the Draft SEIS to the 2016 LTEMP ROD

March 25, 2024

Page 3 of 5

HFE Sediment Accounting Period and Implementation Window Adjustments: 

The GCDAMP’s HFE Amendment Proposal highlights additional considerations that were not included in 

the DSEIS, including specific language changes to the HFE protocol and additional research questions to 

analyze during the implementation of Spring HFEs. The Basin States’ Representatives would like to see 

the HFE protocol amended to include the proposed changes from the HFE Amendment Proposal and the 

complete updated protocol included in the Final SEIS for clarity regarding the proposed action.

The interactions between the various flow alternatives designed to disrupt smallmouth bass spawning 

and the proposed adjustment to the HFE sediment accounting period and implementation window are 

not clearly documented in the DSEIS, making it difficult to comment on the cumulative impacts if the 

actions were to occur within the same year. Further analysis should be provided to better inform the 

communication and consultation process as specified in Sections 1.3 and 1.4 in Attachment B of the ROD 

(Communication and Consultation Process) that is further discussed below. This was also a 

recommendation in the GCDAMP’s HFE Amendment Proposal.

 

Since an HFE only alternative was not analyzed, it is difficult to differentiate between potentially shortterm impacts stemming from the combined proposed actions (HFEs and smallmouth bass flows through 

2027) and longer-term impacts (HFEs only from 2027 to 2036). Additional information should be 

provided to differentiate these impacts. 

 

Implementation of Operational Alternatives: 

Meaningful consultation with the States must continue before Reclamation considers implementation of 

any of the alternatives described in the DSEIS. The Basin States’ Representatives request that the 

current Communication and Consultation Process described in the LTEMP ROD continue to be utilized to 

analyze the various flow options, including discussion of their impacts on Glen Canyon Dam operations 

and critical infrastructure, in order to recommend flow experiments to the Secretary of the Interior. The 

Communication and Consultation Process must also consider circumstances when an experiment may 

warrant discontinuation and evaluate the flow options throughout the potential periods of 

implementation.

 

Adequate notice of the timing of a planned flow experiment will be necessary to facilitate consideration 

of potential resource impacts, to coordinate monitoring prior to, during, and following the 

implementation of the flow options, and to address impacts to the Basin Fund and market grid 

reliability. Successful implementation will necessitate reliable temperature models and meetings to 

occur in a timely manner before a potential trigger is hit.
Re: Basin States’ comments on the Draft SEIS to the 2016 LTEMP ROD

March 25, 2024

Page 4 of 5

Monitoring and Offramps: 

Potential conditions for discontinuing the experimental flow options should be informed by the 

monitoring of warmwater nonnative fish species and consideration of the effectiveness of actions. To

ensure decisions are well-informed, adequate analysis and data collection should occur before, during, 

and following a flow experiment. Several factors to consider when evaluating the potential 

discontinuation of warmwater nonnative fish management actions are included in the Strategic Plan 

(see Section 3.4, page 11, titled “Offramps”). This information should be used to inform the 

Communication and Consultation Process.

 

While minimization of predation on humpback chub is the intent behind the experimental flow options, 

it is imperative that potential impacts to humpback chub from the flow options themselves are closely 

monitored. If the experimental flows are found to negatively impact the humpback chub population 

below the current triggers identified in the 2016 Biological Opinion, Reclamation should immediately 

discontinue the use of the flow actions and consider alternative measures.

 

Reservation of Rights: 

Failure of the Basin States’ Representatives to provide specific comments regarding details of the SEIS 

shall not be construed as an admission with respect to any factual or legal issue or a waiver of rights for 

the purposes of any future legal, administrative, or other proceeding. Moreover, the comments herein 

are specific to this SEIS process and should not be interpreted to apply to any other ongoing NEPA 

processes. Finally, the Basin States’ Representatives reserve the right to comment further on SEIS 

documentation as Reclamation proceeds with subsequent phases of the SEIS process.

Conclusion: 

The Basin States’ Representatives appreciate the opportunity to provide comments on the DSEIS to the 

2016 LTEMP ROD and appreciate Reclamation’s efforts. The Basin States’ Representatives are 

supportive of short-term, mid-term, and long-term actions to address warmwater nonnative fish species 

establishment in the Colorado River in an effort to avoid the potential for long-term management of an 

established warmwater nonnative species. These actions, however, must not be taken at the expense of 

compromising the integrity of dam infrastructure. Should there be any questions, please contact us at 

your earliest convenience.

 

[Signatures on next page]
Re: Basin States’ comments on the Draft SEIS to the 2016 LTEMP ROD

March 25, 2024

Page 5 of 5

Clint Chandler

AMWG Representative, Arizona

Ali Effati

AMWG Representative, New Mexico

Jessica Neuwerth

AMWG Representative, California

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Amy Haas

AMWG Representative, Utah

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Michelle Garrison 

AMWG Representative, Colorado

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Charlie Ferrantelli

AMWG Representative, Wyoming

Sara Price

AMWG Representative, Nevada

Colby Pellegrino

Deputy General Manager, 

Southern Nevada Water Authority 

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