March 23, 2024 

Kathleen Callister 

Bill Stewart 

LTEMP SEIS Project Managers 

125 South State Street 

Suite 800 

Salt Lake City, UT 84138 

Dear Ms. Callister and Mr. Stewart, 

We, as the GCDAMP Recreational Fishing Representatives, appreciate the opportunity to provide 

comments on the Glen Canyon Dam Long Term Experimental and Management Plan Supplemental 

Environmental Impact Statement (SEIS). We are grateful that the Bureau of Reclamation has expedited 

the timeline for this SEIS as the threat posed to the system by smallmouth bass and other warm water 

species demands immediate action. 

Our GCDAMP members have been very involved in the smallmouth bass ad hoc meetings, Technical 

Work Group, and Adaptive Management Work Group meetings where we have provided feedback 

throughout the process on the options presented to address the threat to the protected native fish, as well 

as to the blue ribbon rainbow trout fishery below Glen Canyon Dam. We appreciate the detailed 

descriptions of the five options proposed in the SEIS, and understand that they represent the best thinking 

from experts on strategies to utilize flow and water temperature to address the risk posed to the system by 

these warm water predators. We also value the hard work done by staff to research and assess the 

potential impact to all of the identified resources resulting from each of the proposed actions in this SEIS. 

The devastating effect of smallmouth bass and other warm water species on the native fish populations in 

the Upper Basin is a tremendous historical example inspiring urgency and underscores the importance of 

meaningful actions to protect the river from this threat below Glen Canyon Dam. It is clear that you have 

taken those lessons to heart in the creation of this SEIS. 

There seems a clear understanding that mitigation to reduce or eliminate the threat of smallmouth bass 

and other warm water species below Glen Canyon Dam is critical, and will require the implementation of 

the most effective strategies identified in the SEIS as well as a set of other strategies outside the scope of 

this document. As such, the no action alternative is in our judgment an unacceptable alternative. 

We understand that as the SEIS document is written, it is designed to provide managers with the greatest 

degree of flexibility in addressing this warm water threat. While we absolutely agree with that logic and 

understand that lake levels, dam operations, and conditions on the river are difficult to predict, we feel 

that some of the alternatives are better suited for smallmouth bass suppression and pose less adverse 

impacts on the resources in and along the river. 

In seeking the ability to utilize multiple alternatives as part of the SEIS, that assumes the responsibility 

and ability to effectively determine the impact of any chosen action to reduce or eliminate smallmouth 

bass and other warm water species. How that is to be measured and accomplished is not described in this 

document, and must be included in order to effectively choose the best option. 

For example, during the short term actions being undertaken by the National Park Service while the SEIS 

is under review, all smallmouth bass and other warm water species are being removed from the river. 

Besides being an unsustainable, impractical method for controlling these species, electrofishing as 

currently being practiced during these actions, does not provide managers with an effective tool to 

measure the population of these fish to know with greater certainty how many of the targeted species are 
present in the river system, or their estimated numbers in certain key hot spots in the river. For effective 

management, it is crucial to know the age distribution, numbers in each year-class, and the origin of any 

particular year-class of fish to know if they are entrained fish, or if they were born in specific locations in 

the river. 

This information is critical in determining the effectiveness of any of the options chosen, and essential to 

inform managers if the current strategies are not effective, and additional strategies should be considered. 

There must be funding, personnel, and resources in place to assure the ability to collect systemwide data 

and quickly analyze that data to determine if the chosen action is effective or if refinements are needed to 

the management plan. 

With that being said, of the action alternatives in the SEIS, we believe that the cool mix alternative and 

the cool mix with flow spike are the strategies that will have the greatest impact on smallmouth bass and 

other warm water species. It also provides rainbow trout, an important LTEMP resource, some relief 

during these high temperature and low dissolved oxygen conditions that are currently facing the river. 

What sets the river system below Glen Canyon Dam apart from the Upper Basin, where warm water 

species have devastated the native fish populations, is the longstanding cold water buffer that releases 

from Glen Canyon Dam have provided until recently. While the cool mix strategies would be our first 

choice, in keeping with the importance of cold water as a deterrent to warm water fish predatory species, 

the cold shock and cold shock with flow spike are our next preferred alternatives. 

We are opposed to the non-bypass alternative and do not believe that it has nearly as much potential for 

success in mitigation, and are very concerned about its impact to other resources in the system 

downstream. The tremendous weekly drastic fluctuation from 2,000 cfs to 27,300 cfs, with what amounts 

to essentially warm water releases, will adversely impact the rainbow trout fishery, pose a hardship to 

recreational users of the river, and destabilize the sandbars and banks more than any other alternative. 

Another aspect of the SEIS that is of great importance to the health of the river ecology, the maintenance 

of beaches for recreational use, and cultural resource protection is the high flow experiment (HFE) 

protocol. GCDAMP recreational fishing representatives, along with other stakeholders advocating for a 

healthier river system, have long sought a change to the sediment accounting window and hope to 

increase the possibility of more spring HFEs than have occurred under the present accounting window 

system. We strongly support changes to the sediment accounting window and the resultant possible 

inclusion of more spring HFEs to benefit the river system. While we understand that there are limited 

water resources, the purpose of HFEs and flows designed to help control smallmouth bass are both 

important to river health. The timing for flows to benefit sediment transport and build beaches, and flows 

that will best inhibit smallmouth bass may very well be at different times. It is important that managers 

plan for water deliveries to meet those two very different demands. 

Besides the flow options proposed in the SEIS, it is critical that managers continue to address conditions 

in Lake Powell and in the river to implement actions outside the scope of the SEIS as they are needed to 

deal with this threat. As an example of such a strategy, we are pleased to see that plans are underway to 

begin channelization of the upper and lower slough that is currently a haven for smallmouth bass and 

other warm water species that could threaten native fish downstream. 

Actions and funding to develop and install devices to reduce entrainment of warm water fish through 

Glen Canyon Dam from Lake Powell is a critical step in this battle and must continue as quickly as 

practical. In addition, we support efforts to provide the ability to deliver cold water more effectively to the 

river whether that involves means to develop power generating capabilities on the existing bypass tubes, 

or creating new, deeper bypasses to minimize the dead pool in Lake Powell and prolong the release of 
cold water during potentially warmer climate times well into the future. In the development of these new 

designs, if there are ways to address the increasing concerns about poor nutrient and dissolved oxygen 

levels to the river, that would certainly be worthwhile. 

A deep and colder Lake Powell benefits native fish by providing cold water releases into the river that 

results in a cold water buffer that impedes warm water predatory species. It also benefits the rainbow trout 

fishery at Lees Ferry. Actions by the Basin states to come to terms with realistic water allocations to a 

river system that currently does not satisfy all of their water demands is essential. Greater water 

conservation effort by citizens of all Basin states will put any snowpack gains to the system to best use. 

To highlight our concerns and recommendations: 

1. There must be funding, personnel, and resources in place to assure the ability to collect systemwide 

data and quickly analyze that data to determine if the chosen action is effective or if refinements are 

needed to the management plan. 

2. We oppose the no action alternative and the non-bypass alternative. 

3. We believe that the cool mix and the cool mix with flow spike are the likely most effective 

alternatives. We would also support the cold shock and cold shock with flow spike alternatives as 

means of delivering colder water to the system. Colder water below Glen Canyon Dam has proven 

effective in deterring warm water fish predators, and would provide benefits to the rainbow trout 

fishery currently under stress from warmer, low dissolved oxygen conditions during the likely months 

of implementation. 

4. We are in full support of changes proposed to the sediment accounting window to allow for the 

possibility of more spring HFEs in the future. Implementation of HFEs provides for another critical 

need of the river system and must remain separate from smallmouth bass control flows. 

5. Additional funding and actions to address the smallmouth bass and other warm water fish predator 

threat are critical. They include but are not limited to: channelization of the upper and lower slough to 

increase cold water flow through this warm water habitat, devices to mitigate for warm water fish 

entrainment through Glen Canyon Dam from Lake Powell, strategies to increase cold water delivery 

capabilities to the river such as: adding power capability to the bypass tubes to allow them to be 

utilized outside of experimental windows, lowering water release points from Lake Powell to reduce 

the dead pool and prolong cold water delivery to the river, and if possible address low dissolved 

oxygen and poor nutrient delivery in the process. 

6. Basin states must come to terms with realistic water allocations in a river system that is delivering 

less water. In addition, more robust water conservation efforts need to be enacted in the Basin states. 

We are grateful for the speed with which this SEIS document was created, while providing pertinent 

details of each alternative and the likely impacts to resources. The work of your team will allow managers 

the ability to apply the best of these alternatives to address this threat as quickly as possible. 

Sincerely, 

Jim Strogen, Recreational Fishing AMWG Representative 

Rod Buchanan, Recreational Fishing AMWG Alternate Representative 

Bill Persons, Recreational Fishing TWG Representative 

Bill Davis, Recreational Fishing TWG Alternate Representative