March 24, 2024

Ms. Kathleen Callister

Adaptive Management and Water Quality Division Manager

U.S. Bureau of Reclamation

Electronically submitted to: LTEMPSEIS@usbr.gov

RE: Draft Supplemental Environmental Impact Statement for the Glen Canyon Dam

Long-Term Experimental and Management Plan

Dear Ms. Callister:

The Arizona Game and Fish Department (Department) appreciates the opportunity to provide

input to the Bureau of Reclamation’s (Reclamation) February 9, 2024 Federal Register notice

regarding the Draft Supplemental Environmental Impact Statement for the Glen Canyon Dam

Long-Term Experimental and Management Plan (LTEMP). The Department is aware of the

changing conditions below Glen Canyon Dam, the risk of establishment of warmwater

non-native fish in this section of the Colorado River, and the need to adjust the LTEMP high

flow experiment sediment account window. The Department continues to manage fish and

wildlife resources within the Colorado River watershed and its systems.

Under Title 17 of the Arizona Revised Statutes (ARS), the Department, by and through the

Arizona Game and Fish Commission, has jurisdictional authority and public trust responsibilities

to conserve and protect the state fish and wildlife resources. In addition, the Department manages

threatened and endangered species through authorities of Section 6 of the Endangered Species

Act and the Department’s 10(a)(1)(A) permit. It is the mission of the Department to conserve and

protect Arizona's diverse fish and wildlife resources and manage for safe, compatible outdoor

recreation opportunities for current and future generations. As a cooperating agency on the

development of the SEIS the Department provides the following comments in addition to the

previously submitted comments based on the agency's statutory authorities, public trust

responsibilities, and special expertise related to wildlife resources and wildlife-related recreation

as they relate to the Federal Register notice.

Flow Alternatives to Address High Risk Warmwater Non-native Fish

Higher water temperatures coming through Glen Canyon Dam and the increased risk of fish

entrainment due to low reservoir elevations are the driving factors for establishment of

Smallmouth Bass (SMB) and other high risk non-native fish species downstream of the dam.

Although these factors are a result of the existing water conditions within the Colorado River
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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basin, both release temperature and entrainment can be influenced and managed by operations at

Glen Canyon Dam. As a stakeholder within the Glen Canyon Dam Adaptive Management Work

Group (AMWG), the Department is supportive of the implementation of flow options that

disadvantage high-risk warmwater species, such as SMB.

Within the scoping comments, the Department encouraged Reclamation to plan for flexibility

within the implementation of action alternatives to fit within the adaptive management

framework of the program. While the Department recognizes that this can be a challenge within

compliance documents that are not meant to be determinative (i.e., advocate for one alternative),

it is important to contain options within the Alternatives (e.g., days in which flows should be

implemented, ratios of bypass to powerplant discharge, shape of hydrographs) to either be more

effective in their purpose or reduce impacts to other resources. Additionally, the flow

Alternatives were specifically designed for SMB and may not be as effective for other cool- and

warmwater species. Having a suite of parameters within flow Alternatives that could be

manipulated would allow for a more focused response to a variety of high risk non-native

species, without additional compliance, would be beneficial for adaptive management. In some

cases, the Alternatives could contain more discretionary language to facilitate future

improvements to the Alternative flows or needs established by the GCDAMP.

The inclusion of the predicted SMB population growth rates (lambda values) within Appendix A

is a valuable addition to the draft SEIS. Reclamation should consider incorporating these graphs

and analysis within the main text of the SEIS within the Alternatives’ descriptions. Additionally,

the graphs showing predicted SMB growth rates (lambda) by pool elevation and inflow

developed by Grand Canyon Monitoring and Research Center (GCMRC) that were presented at

the Technical Working Group (TWG) Annual Reporting and the February AMWG meetings

should be included as well. It is evident from this modeling that Alternatives that incorporate

sustained use of bypass (i.e., cool mix) to maintain release temperatures less than 16°C are more

effective at reducing the probability of establishment of SMB with less uncertainty than cold

spikes and alternatives without any bypass. Although this document does not prescribe or

advocate for the use of one Alternative over another, establishing the relative effectiveness of

each to accomplish the stated goal is critical information for the Leadership Team to have when

discussing implementation of experimental or management flows. The Department has concerns

with the inclusion of the non-bypass Alternative within this SEIS. Given the predicted effects

stated within Appendix A, it does not appear to reduce the SMB population growth rate

compared to the No Action Alternative and thus, does not meet the need as established in Section

1.4, nor the the Secretary’s Designee directive from May 2022 AMWG to develop “operational

alternatives that could help prevent cool- and warmwater invasive fish establishment”.

The Department recognizes that the flow regimes outlined by the GCMRC and Reclamation to

suppress SMB will disrupt recreational opportunities at Lees Ferry during high flows; however,

they also represent an overall benefit to the LTEMP resource if effective in their suppression of

SMB by maintaining colder water releases below the dam. The Department does appreciate the

inclusion of considerations for mitigating impacts to anglers within each of the alternatives. The

Department continues to recommend Reclamation consider implementing peak flows during

times of lowest use (i.e. weekdays), as feasible, to minimize impacting recreational users, and to
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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provide adequate time for public announcements for recreationalists to adjust plans and minimize

impacts to boating and angling trips.

It should be stressed that although the Department agrees that the mechanisms of the flow

options proposed should disadvantage warmwater species, the efficacy of such actions to elicit

population-level effects on unwanted species is yet unknown. Reliance on flow operations

exclusively to disadvantage warmwater species at Lees Ferry is likely not an effective long-term

strategy, unless paired with other preventative measures. The Department is encouraged by

pursuit of technologies in preventing or limiting entrainment of warmwater fish through Glen

Canyon Dam that Reclamation is exploring, including tailrace trawls and forebay exclusion nets

and/or temperature curtains. These preventative actions, together with the modification of the

slough by the National Park Service are critical components to work in tandem with the flow

alternatives outlined in the SEIS to minimize biological and economic impacts to existing

resources from high risk non-natives.

Sediment Accounting Window

The Department is supportive of the changes to the sediment accounting window proposed

within the SEIS. The Department has long advocated for adjustments to the accounting window

to allow for additional spring high flow events as they fit more closely with natural processes of

rivers. Further, these adjustments will address the changing precipitation conditions within the

basin, which preclude current winter sediment triggers from being met. Changes to the sediment

accounting window are needed to meet sediment resource goals outlined in the LTEMP and are

in the spirit of the adaptive management framework.

The Department has previously expressed concerns with combining flow actions to address SMB

and High Flow Experiments to address beach building by way of the sediment accounting

window within the same SEIS. The Department continues to stress the importance that these

actions should not be considered mutually exclusive because the intended purpose benefits

separate resources goals. Related to this concern, implementation of each should not be

influenced by the other (e.g. cost, impact to water, or hydropower resources). Additionally, the

Department has concerns that the current decision process through the implementation process

does not allow for adequate time to thoroughly discuss, deliberate, and make a determination on

implementation for these actions together or separately. While the draft SEIS establishes new

management options that are needed, this may put additional strain on the decision process.

Thus, the Department continues to recommend Reclamation identify clear guidance that ensures

adequate time for review and coordination of flow experiments to be considered for

implementation.

Dissolved Oxygen

The factors contributing to dissolved oxygen (DO) levels in the Colorado River below Glen

Canyon Dam are complex, and are influenced by conditions in Lake Powell and dynamics below

the dam. In the introduction to water quality on 3-152, the document implies that DO is the

exception to water quality parameters being “highly defined” by the water quality in Lake
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Powell, because of the rapid effect downstream biotic and abiotic processes have on DO within

the water passed through the dam. However, low DO in the Colorado River directly below the

dam (e.g. 5 miles) is directly correlated with DO levels at the level of the penstocks, and low DO

events have been observed in this section of Lees Ferry. The replenishment of DO through

photosynthetic processes only occurs during daylight hours and may not be adequate to provide

refugia from significantly low DO events coming through the dam at night. It is also important to

acknowledge that despite this section being a relatively small area of the Colorado River

ecosystem, it also represents the most important reach of the Rainbow Trout fishery, an LTEMP

resource, to fishing guides and recreational anglers.

Although the Alternative flows outlined in this SEIS were not designed to address low DO

concerns, Alternatives which include bypass will mitigate low DO in some capacity, assuming

flows occur during periods of low DO, which are most prominent in the fall. The effect of

Alternatives that utilize bypass on DO is likely understated within the SEIS. This is because the

discharge from the bypass tubes may only marginally affect DO when measured directly below

the turbine outflows (as they are modeled in the SEIS), but could have a much more significant

increase to DO even just hundreds of meters downstream.

Additional Editorial Comments

There are some instances of Lees Ferry being mistakenly described as being at river mile (RM)

15; however, Lees Ferry is traditionally considered at RM 0. This has led to some errors within

the text related to river miles. The modeling for SMB lambdas appears to be done at RM 61 (the

Little Colorado River) and 15 miles below Lees Ferry, which may be contributing to the

confusion. Examples of river miles for Lees Ferry that need to be corrected occur on page 2-1,

2-10, and 3-3, but should be corrected throughout. References of locations further downstream

seem to be in relation to Lees Ferry and are correct (e.g. Little Colorado River at river mile 61,

Pumpkin Springs, RM 213). Additionally, the description of river mile contained within the

Glossary is misstated as “Numbered along the Colorado River from south to north starting with

RM 0.0 at the Southerly International Boundary (SIB) with Mexico. Dam locations are noted at

their respective river miles”. This is incorrect, river miles are listed in reference to Lees Ferry

being 0. River miles upstream of Lees Ferry are denoted as negative river miles (e.g. the slough

at -12 mile)

Figure 3-25 should be updated to include relative abundance from 2016-2023, which is contained

within the Department’s most recent Lees Ferry monitoring annual report (Rogowski et al.

2023). The Department has observed catch per unit effort below one fish/min since 2021, which

falls below the management goal outlined in the Department’s fisheries management plan for

Lees Ferry. It is important that the status of the Rainbow Trout fishery is accurately reported

within the SEIS.

With expansion of Humpback Chub (HBC) into the western Grand Canyon, especially into the

areas previously inundated by Lake Mead, the Department’s perception of suitable or preferred

habitat for this species is being challenged. The information that is contained within the Habitat

section for HBC (pg. 3-118) is based on observations that were made when HBC were relatively
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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rare in the system. As populations have increased the specific habitat that this species was and is

reliant on is broadening. A recently published manuscript by Department staff considers this

change in perspective and may be a beneficial reference for this section (Boyer et al. 2024).

On pg. Reference-31, the reference “Rogowski, D., C. Madonia, K. Manuell, R. Osterhoudt, L.

Winters, and P. Wolters. 2023. Arizona Game & Fish Department, Lees Ferry Long-Term

Monitoring. Grand Canyon Monitoring and Research Center, Flagstaff, Arizona.” does not exist.

The correct citation for the 2022 Lees Ferry annual report is “Rogowski, D., J. Fennell, and D.

Fonken. 2023. Status of the Lees Ferry Trout Fishery 2022. Annual Report, prepared by the

Arizona Game and Fish Department, Research Division, for the US Geological Survey, Grand

Canyon Monitoring and Research Center, Flagstaff, Arizona. Arizona Game and Fish

Department, Phoenix, Arizona”. Additionally, on pg. Preparers-2, Scott Roger's title should be

corrected to "Aquatic Wildlife Program Manager, Region 2”.

Thank you for the opportunity to provide input on the SEIS for the Glen Canyon Dam

Long-Term Experimental and Management Plan. For further coordination, please contact Ryan

Mann at rmann@azgfd.gov or by phone call to 623-236-7538.

Sincerely,

Acting for

Luke Thompson

Habitat, Evaluation, and Lands Branch Chief

AGFD # M24-02091439

Cited:

Boyer, J., Fonken, D., Rogowski, D. 2024. Why new scientific information is important for

native fish conservation: a case study from the humpback chub (Gila cypha) in the Grand

Canyon, U.S.A. Aquatic Conservation: Marine and Freshwater Ecosystems 34 (1): e4075.

Rogowski, D., J. Fennell, and D. Fonken. 2023. Status of the Lees Ferry Trout Fishery 2022.

Annual Report, prepared by the Arizona Game and Fish Department, Research Division, for the

US Geological Survey, Grand Canyon Monitoring and Research Center, Flagstaff, Arizona.

Arizona Game and Fish Department, Phoenix, Arizona