" 

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• 

• 

IN REPLY REFER TO:

United States Department of the Interior

NATIONAL PARK SERVICE

INTERMOUNTAIN REGION 

12795 West Alameda Parkway

P.O. Box 25287

Denver, Colorado 80225-0287

IMRO-RSS-COR (1241)

VIA ELECTRONIC MAIL: NO HARD COPY TO FOLLOW

Memorandum

To: Wayne Pullan, Regional Director, Upper Colorado Basin, Bureau of Reclamation 

Kathleen Callister, LTEMP SEIS Project Manager, Bureau of Reclamation

Bill Stewart, Adaptive Management Group Chief, Bureau of Reclamation

From: Kate Hammond, Regional Director

Department of Interior Regions 6, 7, & 8

National Park Service

Subject: National Park Service Comments on the Bureau of Reclamation February 2024 

Supplemental Environmental Impact Statement for the December 2016 Record of

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

The National Park Service (NPS) appreciates the opportunity to provide input on the February 2024 

Public Draft of the "Supplemental Environmental Impact Statement for the December 2016 Record of 

Decision Entitled Glen Canyon Dam Long-Term Experimental and Management Plan (LTEMP/SEIS)

prepared by the Bureau of Reclamation (Reclamation). As a cooperating agency pursuant to the

National Environmental Policy Act (NEPA), NPS also appreciates the opportunity to provide special

expertise and comments on previous drafts and to provide further input on this draft SEIS. NPS

provides the following comments:

Urgency and Timeline:

NPS hopes that this process can stay on track and that Reclamation chooses the most effective

alternative to comply with the 1992 Grand Canyon Protection Act (GCPA) to prevent

irreversible and detrimental impacts to the native fish populations, the federally threatened 

humpback chub and the federally endangered razorback sucker within Grand Canyon National

Park. We commend these efforts to expedite and prioritize this planning process despite the

many other planning priorities in the Colorado River ecosystem.

Completing this process by late spring 2024 is imperative to prevent Smallmouth Bass (SMB) 

establishment below the Glen Canyon Dam (GCD) on national park units, and to protect native

and federally listed fish, (humpback chub and razorback sucker), on park units when river 

temperatures increase in the summer. NPS agrees that Reclamation should act with urgency, 

using the most effective bypass alternatives in June 2024 to mitigate invading populations close

to GCD. NPS has been advised by U.S. Fish and Wildlife Service (USFWS) fisheries experts in 

the Upper Colorado River Basin, who have been working to control SMB populations for over

20 years and watching the impact of this predator on native fish and amphibians in higher 

turbidity waters, that agencies should not delay action and should instead act with the most

1
2

effective tools by this summer. A recent paper from a group of researchers who work in the 

upper basin stated:

o There is substantial overlap in the thermal suitability of river segments for growth of 

warmwater native and nonnative fishes across the basin, and current evidence suggests 

nonnative species have a competitive or predatory advantage over native species in places 

where their ranges overlap (Olden et al. 2006, Johnson et al. 2008). Our analysis demonstrates 

that nonnative species in the basin have responded more strongly to recent river warming than 

native species. Thus, in the absence of effective management interventions, future warming is 

likely to disproportionately benefit nonnative species to the detriment of native species (Dibble 

et. al 2020).

• Currently, this SEIS states that SMB operations would end in 2027. That is assuming that other 

approaches such as a thermal curtain may be available and effective by then. However, given 

uncertainties, NPS recommends extending the timeframe for the SMB operations beyond 2027 

through the lifetime of the original LTEMP, in case other tools (temperature curtain or higher 

Powell elevation) are not available or prove ineffective by 2027. If that happens, and if the 

elevation of Lake Powell falls lower and release temperatures return to over 15.5C, these 

bypass flow tools would need to be continued to address the mandates of the GCPA and the 

Endangered Species Act (ESA).

Non-Bypass Alternative: 

• NPS believes the Non-Bypass alternative does not meet the purpose and need of the SEIS

based on the 2022 evaluation of the USFWS-led multiagency SMB Task Force, the subsequent 

analysis performed in the development of the Reclamation SMB Environmental Assessment 

(EA), and the modeling analysis presented in this LTEMP SEIS document. The need for the 

SEIS is “...to disrupt the establishment of smallmouth bass below Glen Canyon Dam by 

limiting additional recruitment, which could threaten populations of threatened humpback 

chub below the dam”; however, based on SMB population growth modeling (lambda), the 

Non-Bypass alternative is not effective. The purpose of the plan is to prevent the SMB 

population from growing and expanding during summers when dam release water temperatures

are over 15.5C. A lambda less than 1.0 would indicate the alternative is creating conditions for 

the SMB population to decline whereas a lambda greater than one indicates the alternative is 

failing to prevent the growth of the population. This Non-Bypass alternative fails to achieve a 

lambda less than 1 in warmer water summers and instead shows growth of the population with 

a lambda factor of about 1.5-2.0. The current analysis in the plan lumps all the results together 

for both warm and colder water summers, but when these results are split out, it is clear this 

alternative does not perform significantly different from no action, which also fails to stop the 

SMB from reproducing. Reclamation has evidence in this SEIS for dismissal of this alternative 

as it does not meet the published purpose and need.

• Concern regarding significant impacts to downstream resources and recreation. This analysis 

shows that the Non-Bypass tool may have many impacts that would make it incompatible with 

the GCPA’s mandate to protect, mitigate adverse effects to, and improve the natural and 

cultural resources and recreation below the GCD. The Non-Bypass alternative would have 

significant fluctuations from 2,000 cfs up to 27,000 cfs occurring on a weekly basis, potentially 

for up to 26 times throughout the summer. Given the extent of impacts to downstream 

resources below, we believe implementing Non-Bypass flows would not be consistent with the 

intent of the GCPA due to the following: 
3

o Sediment impacts: When the effects of the Non-Bypass alternative are split out for 

those months or years in which the Non-Bypass tool is actually used, they show 

increased sand mass balance and beach erosion and decreases in the frequency of High 

Flow Experiments (HFEs). These effects will decrease the natural aeolian transport 

processes in the canyon, threaten the protection of archeological sites, and reduce the 

area of recreational camping beaches, while also directly impacting the rafting 

recreation with flows lower than what are currently allowed under the 2016 LTEMP 

EIS. 

o Recreation impacts: While the plan currently mentions some impact to recreation from 

the non-bypass flows, it fails to articulate that these flows might occur on a weekly 

basis. For guided boating in the Glen Canyon National Recreation Area (NRA), this 

would likely mean shutting down concessions during those days. While that is similar 

to the impacts of an HFE, an HFE occurs once a year, whereas these may occur more 

than 20 times a summer, which is a more significant impact.

o Impacts to Native Amphibians and invertebrates: The current analysis fails to mention 

impacts to native amphibians. In locations such as the river mile-12 slough, we may 

already be seeing SMB prey upon native salamanders and other amphibians and 

invertebrates, and based on research in other river systems where SMB have invaded, 

these impacts would be likely to increase throughout the system below the dam if 

alternatives fail to prevent the establishment of SMB (Sanderson et al. 2009, Kiesecker 

and Blaustein 1998, Hayes and Jennings 1986; Dill and Cordone 1997). 

o Food base and direct Native Fish Impacts: According to the SEIS routing chart, these 

frequent and large river fluctuations under the non-bypass alternative persist down to 

the Little Colorado River (LCR) and beyond, and may result in desiccation of

macroinvertebrate resources, ultimately impacting food base in the system. These

significant fluctuations during the summer through Marble Canyon would also be likely 

to impact native fish, including the humpback chub aggregation at river mile 30. 

o Rainbow Trout Fishery Impacts: Non-bypass fluctuations are also likely to impact the 

rainbow trout fishery in Lees Ferry which is already at very low population levels and 

facing more stressors than it ever has. This alternative fails to prevent the low dissolved 

oxygen levels and elevated temperatures that occur in the worst 17-20% of the traces 

run in the modeling scenarios, which will increasingly stress the rainbow trout. 

o Ineffective at preventing the establishment of SMB. This alternative also fails to reduce 

the growth and distribution of the warm water invasive fish populations that threaten

native aquatic resources. These types of impacts are what led to the 1995 EIS that 

moved dam operations away from large daily fluctuations to comply with the GCPA. 

NPS encourages Reclamation to consider dismissal of this alternative given its

inconsistency with the intent of the GCPA.

• Engineering constraints and remodeling: The Non-Bypass Alternative was designed with low 

flows down to 2,000 cfs. NPS understands there may be new potential operational restrictions 

of maintaining penstock flows of at least 3,000 cfs or perhaps even 3,500 cfs; If this alternative

is not dismissed then it may require further analysis in the SEIS to show how those guidelines 

may affect the modeled lambdas. 

Further Hydropower Analysis: 

• Bypass alternatives have reasonably low impact levels to hydropower: This document includes 

hydropower value loss estimates that indicate a wide range in fiscal impacts depending on the 

annual conditions, which include reservoir elevation, temperature profile and the distance down 
4

the river that is chosen for the cooling effect based on the distribution of SMB. This analysis 

shows that the maximum impacts from the bypass alternatives would result in about 1-2% of 

hydropower value reduction or about $10-16M. For a measure that may be needed to prevent 

the loss of the native fish species in the Grand Canyon and protect the federally threatened 

humpback chub, this suggests that these bypass alternatives are viable approaches that would 

have minimal value loss and would be consistent with the GCPA mandate to operate the dam in 

a manner to protect, mitigate the adverse effects to, and improve the natural and cultural 

resources and recreation downstream of GCD. 

• Hydropower modeling transparency: NPS understands that much of the hydropower modeling 

in this document was performed by the Grand Canyon Monitoring and Research Center 

(GCMRC). The assumptions and methods appear very clear and transparent, but there has been 

substantial criticism of this work from hydropower interests. NPS understands that much of 

this controversy is because GCMRC adjusted future energy costs to be more realistic. The 

Argus Forward Mid-Market projections for the Palo Verde hub are used by Western Area 

Power Administration (WAPA) and were also used by GCMRC, but because these projections 

include a risk premium, these were adjusted to be more representative of the marginal cost of 

energy by GCMRC using actual prices from February 2000 through November 2023 and the 

Argus Forward Mid-Market projections. NPS encourages Reclamation to continue to use these 

estimates from GCMRC to ensure that cost impacts to hydropower are fairly and objectively 

estimated. NPS understands WAPA will be submitting another cost estimate during this 

comment process using a different method, and hope this estimate is provided with sufficient 

time for review and with a clear and transparent set of assumptions, that it is peer reviewed to 

ensure objectivity, and can be weighed in relation these estimates from GCMRC. To be 

objective information for this SEIS, we hope any new analysis includes similar adjustments to 

the GMCRC analysis to be more representative of the marginal cost of energy using methods to 

correct the Argus Forward Mid-Market projections.

Support for HFE Protocol Adjustments: 

• HFE adjustments will retain the original intent of the LTEMP and comply with the GCPA:

NPS supports and appreciates the adjustments that Reclamation is making to the HFE Protocol 

in this SEIS. These changes will help allow for HFEs to be implemented with a frequency 

close to what was intended in the original LTEMP EIS even when water levels are lower. 

These changes will also shift the HFEs to more natural timing with more occurring between 

April and June under certain circumstance which is closer the historic timing of peak flows and 

more likely to be beneficial to the native species that evolved in this system. NPS appreciates 

Reclamation’s commitment to the intent of the GCPA and to following through on the 

recommendations from GCMRC and the Flow Ad hoc group of the Adaptive Management 

Work Group (AMWG).

Consideration of a Combined Alternative: 

• Possible combination of alternative options: NPS understands that, due to discussions

occurring, it may make sense to combine a suite of alternatives into an umbrella or menuoriented alternative where a particular option could be chosen to fit the conditions of a specific 

year. NPS is not opposed to this approach as it may increase flexibility; however, we would 

strongly suggest that only tools that are able to meet the purpose and need of discontinuing the 

establishment of SMB are combined into an umbrella alternative. This would include the 4 

alternatives that use bypass. If tools do not reduce lambda below 1, then they are not effective 

and should not be considered at this point in the invasion curve. The Non-Bypass alternative, 
5

when lambda results are averaged for the months or years when the tool is actually needed and 

used (when release temperatures are greater than 15.5C) does not reduce lambda below 1, so it 

does not in fact disrupt the establishment of smallmouth bass. For this reason, this alternative 

should not be included. It is critical, particularly in the summer of 2024, to use the most 

effective tools available while SMB is still limited in distribution to Lees Ferry and the most 

eastern portion of Marble Canyon. Many of these tools will be less effective if the population 

expands during this early phase in the invasion curve. NPS recommends prioritizing the use of 

tools that will be the most effective the earliest in the process based on the lambda values. If 

there is the possibility that Reclamation may not choose to use the most effective tool during 

the first year (2024), then this SEIS should include a cost analysis of how much more bypass 

cooling might cost in the 2nd year (2025) if SMB distribution expands further downriver. 

Below are additional technical comments on how NPS recommends that data be organized and specific 

areas where additional citations or analysis is needed:

Averaging problem in the analysis of the modeling

• Not all resources are being compared the same way and this may cause inconsistent 

comparisons that underestimate the impacts of some alternatives on some resources. NPS’

understanding of the modeling is that there were 30 traces used; approximately 6 of the traces 

had years where release temperatures were greater than 15.5C and about 24 traces where 

temperatures stayed below 15.5C. Resources were analyzed to look at the effects of the 

alternative as averaged over all traces. Since the alternatives have tools that are only used in 

months where the temperature exceeds 15.5C, averaging across all the traces means we are 

averaging out the actual effects with 83% of the runs that didn’t use the tool. That would mean 

we are only really seeing about 1/5 of the impact, rather than the actual impact that would be 

experienced if the future was actually a trace where release temperature was hotter. In years 

where these tools aren’t needed, the costs and impacts of the tools is zero because this would be

no action. For hydropower, the analysis broke out the effects for the months where the tools 

were used to show the real impact of use of those tools in Table 3-26. NPS believes this to be 

the correct way to look at all impacts. In comparison, this same type of table should be used to 

assess these impacts in the months or years when the tools are actually used:

o Lambda for SMB population growth: this should be expressed in table form similar to 

3-26, as an average lambda for the months in which the tools are used (when temp > 

15.5C). This should be considered as months because even years that the tools are used 

may vary significantly if the tool is only used for one month vs. when it is used for 5

months; however, GCMRC may have reasons why they believe year might be more 

appropriate. In either circumstance, NPS would strongly suggest not doing this by 

trace, which would lump together 4 years when in fact the tool might only be used in 

one year of the four. 

o Frequency and Duration of HFEs: NPS recommends this be in table form, again broken 

out for the years when the tools are used only because in the years they aren’t used, it 

would look and function exactly like no action. Currently, the way it is presented, it 

looks like there are no differences in HFEs amongst the alternatives, but NPS thinks 

that when this is split out clearly based on the years the tools are used, it will show 

some marked differences. 

o Sand Mass Balance and Beach Building metrics: both need to be split out for the 

months or at least the years in which the tools are used (temp>15.5C), which would 

show the full effects of the alternatives on these metrics. GCMRC may have to advise 

whether months or years would be more appropriate, and if years whether those should 

start and end July 1 because of the HFE accounting window. 
6

o Dissolved Oxygen: NPS recommends this data and graph be broken out to show the 

effects to dissolved oxygen for the years in which the tools are used, otherwise this is

mostly comparing the effects of no action to no action. NPS believes there will be a

more distinct difference that will emerge on the alternatives with bypass cooling versus 

those without. Again, that is a fair way to compare similar to the hydropower table 3-26, 

because we don’t actually experience the average of the traces in the future, rather, it is

only the future trace that occurs. 

Other modeling presentation issues

• Representative Summer-Long Releases for each Alternative: In chapter 2, NPS sees the need 

for a graph showing the alternative releases for the entire summer (May1-Oct 31) using a 

representative trace with higher release temperatures where the tools are used for most of the 

summer. Currently you are only showing a representative week, but there are important 

differences with frequencies and timing of these flows throughout the summer. For the 

alternatives with flow spikes that would show the 3 spikes occurring from June to mid-July. 

For the Non-Bypass our understanding is that might show 26 fluctuations between May to 

October. We think that it is not clear to most readers how frequent these flows might be 

occurring in a hot summer. The graphs in 3.2.1 appear to show monthly volumes over time, 

but not the actual spikes. 

• Lambda graphic: Currently, this graphic is in an appendix and since it is the most important 

modeling result it should be moved to the main text. It needs some reformatting as its very 

confusing. The labels should be moved below the axis, the thick lines where most of the results 

are falling needs a tick off to the side (is it 90%, 92%, 95%?) and should be a dot rather than a 

line like the other locations. Again, this graphic would be much more useful if it showed only 

the traces in which temperature exceeds 15.5C as those are the traces in which the tools are 

used. Also as suggested above, a table format presentation with the breakout for the months 

where 15.5 was exceeded with average lambda values would be even more useful. 

• Trace graphs to accompany lambda graph: Another two graphs that would be very useful to be 

presented in the same section accompanying the lambda values would one with the Lake 

Powell elevation over years and one with the release temperature over years showing all 30 

traces. This would illustrate how many traces did not exceed 15.5C and explain why based on 

reservoir levels. That is an important part to relay. Again, current graphs in section 3.2.1 

appear to show the averaging of all the traces for temperature and lake Powell elevation but 

seeing the 30 individual traces and seeing them right next to the lambda graph would be much 

more useful for comprehension of what is happening. 

• Improved Routing map in Figure 2-6: This routing map for the Non-Bypass should be relabeled 

as the term “collapsing trough” is a bit subjective. We actually don’t see the trough collapsing 

by the LCR, it appears to still be a trough at that point. It would be helpful to have stage on the 

right axis (we think that was intended but it shows as all zeros on the right axis) and a gridded

and more clear set of labels and tics on the left-hand axis so we can tell what the minimum 

flows actually are at the LCR. On the X axis it would be helpful to have time, because one of 

the assertions of the Non-Bypass alternative is that it won’t desiccate invertebrates because its 

dropping at night but as that wave propagates down it won’t be at night but may be in direct 

sunlight in august daytime temperatures. 

• Sediment graphics showing HFEs: NPS recommends breaking these out to show representative 

trace years in which fall season HFEs occurred vs. those with spring HFEs, as well as for those 

in which other tools were used (the flow spikes vs. Non-Bypass fluctuations vs. those without

any). Currently, these graphics are misleading both in terms of the averaging problem (stated 
7

above) but also it makes it looks like there will be two HFEs a year. This may create concerns 

for some stakeholders thinking that HFE frequency is increasing when in fact the frequency 

may decrease slightly from the original LTEMP using the modeling assumptions. We suspect 

if this is broken out, the frequency of HFEs would decrease the most under Non-Bypass in the 

years when that tool is used. 

Issues in need of more updated references or additional analysis considerations

• Fully incorporating the implications of the lambda results

o In both Table 2.12 (impact summary table) and section 3.5 (aquatic resources) the 

lambda modeling results treated separately and almost as if they are an unrelated issue 

with respect to effects of the alternatives to native and non-native fish. Those results are 

the best available science for whether the alternative actually meets the purpose and 

need to either: (1) control the growth and expansion of the warmwater invasive fish 

populations or not, and (2) minimize impacts of predation on native fish populations or 

not. Those results are not fully interpreted when they are presented and aren’t carried 

through into the subsections to relay the potential impacts of the alternatives in 

comparison to no action and each other. For example, the lambda results show that cool 

mix is keeping lambda well under 1.0 in the warmest years, whereas no action has 

lambdas well over 1.0 or even over 2.0 in those warmest years. NPS recommends this

be interpreted to explain that these results indicate smallmouth bass and other 

warmwater invasive populations would decline under “Coolmix” and native fish would 

then not face increasing predation, whereas under no action, smallmouth bass and other 

warmwater invasive populations would increase and possibly double each year. After a 

time delay, native fish would be subject to an expanding wave of predation from these 

fish that would likely impact them at the population level. The most important place to 

fully incorporate these results is on pages 3-133 and 3-134 for the effects of NonBypass alternatives in terms of how SMB and GSF populations would expand and 

impact HBC and RBS under no action and Non-Bypass.

• Updating non-native information from 2018-2024 in section 3.5

o Much of the non-native presence and distribution information is cited before 2018.

Given the increased river temperatures and presumed entrainment in the last few years, 

NPS recommends inclusion of literature from 2018-2024 including information 

presented at the GCMRC Annual Review Meetings. NPS can supply an appendix to the 

2019 NPS Expanded Aquatic Non-native Species Management Plan to help, and the 

Annual Review Meeting (ARM) information should be readily available from GMCRC. 

GCMRC can also provide access to a shared non-native database and new mapping 

information for the distributions of non-native fish that should be used in this document, 

particularly for smallmouth bass, green sunfish, walleye and brown trout. NPS will 

provide a presentation from the last AMWG that summarizes much of that data and

provides details of NPS’ rapid response efforts.

• Food base implications from Non-Bypass alternative

o The food base impacts in the plan need improvement and input from GCMRC. The plan 

currently seems to conclude the Non-Bypass fluctuations from 2000 cfs to 27000 cfs 

that might occur every week throughout the summer for over 20 times a summer would 

have little to no impact on food base. These findings are inconsistent with findings of

the effects from past HFEs or from past “bugflows” where altered flows, even when

occurring only once a year, have shown marked impacts that were positive or negative 
 

 

 

 

 

 

 

 

 

 

 

flows wouldn't 

, they don't involve the drop before the increase, and 

• 

Reclamation's 's efforts 

to macroinvertebrates or gross primary production (GPP). The plan states that these

Non-Bypass desiccate macroinvertebrates because they are short and at

night, citing Blinn 1999. Blinn 1999, looked at effects in early spring from the 1996 

Beach Building Flow when temperatures at night were much lower and the frequency of

the flow was only once that year. These Non-Bypass flows would occur repeatedly 

throughout the summer up to over 20 times during much hotter months. Also, the

fluctuations do not collapse much by the LCR, so the fluctuation would propagate

through Marble Canyon during the day, which would be in hot temperatures in direct

sunlight. There may also be some impacts to macroinvertebrates and the food base

from the flow spikes or from spring HFEs; however, the frequency of those spikes is 

limited to 3 per year the timing of

those corresponds well with natural pre-dam spring peak flows and that should be noted

in the plan. Given the preponderance of studies that indicate natural timed flows are

better for many organisms that evolved with that timing (see Poff et al 1997, Poff and 

Matthews 2013, etc.), NPS requests analysis in the SEIS of timing of flows in relation 

to natural and historical flow regime. 

Rainbow trout population effects from Non-Bypass alternative

o Several sections of the plan conclude that rainbow trout population would not likely be

affected by the Non-Bypass fluctuations despite expected increased mortality in young 

rainbow trout. The conclusion appears to be based primarily on the Korman 2011 study 

that found compensatory responses to flows that impact rainbow trout reproduction. 

However, the current rainbow trout population is at a much lower population than any 

of the data points that Korman 2011 considered with fewer total reproducing fish. There

are also major stressors on the population, including occasional high river temperatures 

(which vary with alternative), low dissolved oxygen situations (which vary with 

alternative), increased brown trout predation and competition, and the potential for

significantly increased predation from warm water predators (which varies with 

alternative). Also, the health of the trout population is a recent concern this spring 

(2024), which may have to do with some impacts from these stressors. NPS

recommends these factors be taken into consideration, as assuming a compensatory 

response no longer seems like a reliable conclusion. 

NPS appreciates the close coordination between the agencies within the Department of the Interior. 

This collaboration has been exceptional and NPS appreciates staff to integrate

the best available science into this analysis and continued coordination for SMB response. 

Reclamation has truly risen to the challenge presented by these rapidly changing conditions.

Thank you for the opportunity to comment on this important and expedited process. Please contact Rob 

Billerbeck, NPS Colorado River Program Coordinator, at 303-987-6789 or rob_p_billerbeck@nps.gov 

if you have any questions on these comments or wish to discuss further.

Kate Hammond 

Regional Director

Department of Interior Regions 6, 7, & 8

National Park Service

8
9

Cc:

Rob Billerbeck, Colorado River Coordinator, National Park Service, DOI Regions 6, 7, & 8 

Ed Keable, Superintendent Grand Canyon National Park

Michelle Kerns, Superintendent Glen Canyon National Recreation Area

Enclosure 1: NPS Technical Comment Matrix
10

Literature Cited

Blinn, D.W. J.P. Shannon, K.P. Wilson, C. O'Brien, and P.L. Benenati. 1999. Response of benthos and 

organic drift to a controlled flood. Pages 259-272 in The Controlled Flood in Grand Canyon, edited by 

R.H. Webb, J.C. Schmidt, G.R. Marzolf, and R.A. Valdez. Geophysical Monograph 110, American 

Geophysical Union, Washington, D.C.

Dibble, K., C. Yackulic, T. Kennedy, K. Bestgen, J. Schmidt, 2020, “Water storage decisions will 

determine the distribution and persistence of imperiled river fishes” https://doi.org/10.1002/eap.2279

Dill, W.A., and A.J. Cordone. 1997. History and status of introduced fishes in California, 1871-1996. 

California Department of Fish and Game Fish Bulletin, volume 178.

Hayes, M.P., and M.R. Jennings. 1986. Decline of ranid frog species in western North America: are 

bullfrogs (Rana catesbeiana) responsible? Journal of Herpetology 20(4):490-059.

Johnson, B. M., P. J. Martinez, J. A. Hawkins, and K. R. Bestgen. 2008. Ranking predatory threats by 

nonnative fishes in the Yampa River, Colorado, via bioenergetics modeling. North American Journal 

of Fisheries Management 28: 1941–1953.

Kiesecker JM, Blaustein AR (2008) Effects of introduced bullfrogs and smallmouth bass on 

microhabitat use, growth, and survival of native red–legged frogs (Rana aurora).

Conservation Biology 12(4): 776–787, http://dx.doi.org/10.1111/j.1523-1739.1998.97125.x

Korman, J., and T. S. Melis. 2011. The Effects of Glen Canyon Dam Operations on Early Life Stages 

of Rainbow Trout in the Colorado River: US Geological Survey Fact Sheet 2011– 3002. Internet 

website: http://pubs.usgs.gov/fs/2011/3002/.

Olden, J. D., N. L. Poff, and K. R. Bestgen. 2006. Life-history strategies predict fish invasions and 

extirpations in the Colorado River Basin. Ecological Monographs 76: 25–40.

Poff, N.L., J. Allan, M. Bain, J. Karr, K. Prestegaard, B. Richter, R. Sparks, and J. Stromberg. 1997. 

The Natural Flow Regime: A paradigm for river conservation and restoration. BioScience, Volume 47, 

Issue 11, December 1997, Pages 769–784, https://doi.org/10.2307/1313099

Poff, N.L., and Matthews, J.H. 2013. Environmental flows in the Anthropocence: past progress and 

future prospects. Current Opinion in Environmental Sustainability 5: 6, 667-675. 

https://doi.org/10.1016/j.cosust.2013.11.00

Sanderson BL, Barnas KA, Wargo Rub AM (2009) Nonindigenous species of the Pacific Northwest:

An overlooked risk to endangered salmon? BioScience 59(3): 245–256,

http://dx.doi.org/10.1525/bio.2009.59.3.9
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1.1 1 NPS J Balsom

In the opening section, please edit to recognize that the 

Colorado River meanders through many more rocks types than 

sandstone. The river cuts through sandstone cliffs in the 15 

miles below Glen Canyon Dam, and quickly downcuts through 

the entirety of the Grand Canyon strata, from limestone 

through schist and granite.

1.1 1 NPS J Balsom

2nd paragraph .... Reclamation and NPS, not just Reclamation, 

developed LTEMP. It is correct in the 4th paragraph but not 

the 2nd.

1.2 1-4 NPS J Balsom

2nd complete paragraph references LTEMP FEIS also 

includes a proposal ... Should this not reference the current 

SEIS?

1.5 1-6 NPS J Balsom

end of page, NPS is the only agency not spelled out with 

abbreviation in ( )

1.5 1-7 NPS J Balsom

Under the "NPS administers" paragraph, delete Baaj Nwaajjo 

I'tah Grand canyon National Monument. BLM and FS 

administer those areas

2.3 2-2 NPS

R 

Billerbec

k

Strike the extra 'the' - This document provides detailed 

changes to the both the sediment 

account period and implementation window. 

2.5 2-10 NPS

R 

Billerbec

k

Could add at the bottom that SMB are also likely to prey upon 

the rainbow trout and impact the rainbow trout fishery. 

2.1

2-17 

and 2-

18 NPS

M 

Trammell

First para in section 2.10 states that 'The design of this 

alternative is such that the short-duration, low-flow and highflow releases are largely attenuated by the time the flow wave 

reaches the confluence with the Little Colorado River." but in 

para 2 on page 2-18 it says 'The fluctuations shown in Figure 2-

5 were designed to disrupt the smallmouth bass spawning at 

river mile 61.' If the flows dissipate by the LCR, they can't 

also be designed to disrupt spawning in the same location 

(RM61). Also, as stated in following comment, the trough is 

not in fact attenuated by the time the flow wave reaches the 

LCR (RM 61). Please delete the first quoted sentence above.

2-10

figure 2-

6 2-19 NPS

R 

Billerbec

k

The axis titles on the figure 2-6 are too small to read, and the 

right axis is probably supposed to be stage but says all 0's. 

Objectively, this figure does NOT show the fluctual trough 

dissipating by the LCR. WAPA has been saying it would 

'collapse' by the time the trough reaches the LCR ('collapse is 

in the title of the figure) but this figure appears to show there is 

still a large variation in flow at the LCR, and even at Pumpkin 

Springs, and flows are still dropping below 5000cfs at the LCR. 

The amount of time flows are below 5000 cfs is shown as 

shorter, but it is impossible to tell how long from this figure. 

The scale should be better with a higher resolution, so you can 

actually read the graph. Also we can't tell time of day the 

trough reaches the LCR or Pumpkin Springs, and that is 

important to how the flows impact macroinverts, as impacts are 

higher during daylight hours especially in summer heat. 

please add a figure that shows only a two-day time period or 

add a table to show what hour of day the trough is low. 

LTEMP SEIS

NPS comments - yellow high importance comments we feel strongly need to be addressed, the reddishbrown are the very high importance, most 
2.12

table 2-

1

2-20, 

2-21 NPS

R 

Billerbec

k

The tables 2 1 and 2 2 are incomplete in summarizing 

important effects to GCPA resources and LTEMP goal effects. 

For no action - should restate as stated in the intro that HFEs 

are likely to happen at a lower frequency than was estimated 

in the LTEMP if we remain in lower water conditions under no 

action. Should also state the warmer river and dissolved 

oxygen are likely to negatively impact the rainbow trout fishery 

(this is stated elsewhere in the plan multiple times). For the 

non-bypass alternative it should state that it may have 

negative impacts on native fish because of the spread of warm 

water non-natives (because lambda results are very simliar to 

no action and that is the conclusion for no action). Also see 

new GCMRC report (to be released soon) and presentation 

(Yackulic, C.B., Bair, L.S., Eppehimer, D.E., Salter, G.L., 

Butterfield, B.J., Caster, J.J., Deemer, B.R., Fairley, H., Grams, 

P.E., Kasprak, A., Palmquist, E.C., and Sankey, J.B., 2024, 

Modeling the impacts of Glen Canyon Dam operations on 

Colorado River resources [presentation], LTEMP SEIS 

meeting (virtual), January 31, 2024: Flagstaff, Ariz., US 

Geological Survey, Southwest Biological Science Center, 

Grand Canyon Monitoring and Research Center, 

https://www.usgs.gov/centers/southwest-biological-sciencecenter/science/modeling-impacts-glen-canyon-damoperations), because we expect there would be impacts to 

2.13

table 2-

2 2-25 NPS

R 

Billerbec

k

Please include the key quantitative sediment metrics here in 

this summary for comparision and please split them out for the 

average of the runs where the tools were actually employed 

versus the runs where the tools were not used because 

currently the lumped average results are obscuring the effects 

of the flow spikes (max of 3) and the non-bypass fluctuations 

(every weekend so as many as 26) so we aren't really seeing 

the effects to the sediment that we are certain are there in the 

years when the tool is used. Hydropower has quantiative 

results sumarized here split out finely to understand the 

impacts and that is needed here for sand mass balance, the 

amt of sediment deposited and the frequency and duration of 

HFEs were all modeled - please report all those stats here for 

comparison. This is critically important. The effects of nobypass alterantive for cultural resources and sediment fail to 

include the effect of the large fluctuations themselves. It 

appears that no-bypass may have a lower number of HFEs in 

the runs when it is actually employeed, but that difference is 

being lost when averaged over all 30 runs many of which don't 

use the tool. Also for the Sandbar Model results (figrue 3-22) 

you fail to disclose a very important aspect of that for the alts 

with flow spikes and for the non-bypass that these results are 

limited to only showing building but not erosion using the 

Mueller model. So these results must be interpreted in that 

2.13

table 2-

2 2-25 NPS

R 

Billerbec

k

Please include the lambda statistic in this summary - it is 

critical for quantitive comparision and currently you are only 

reporting quantiative model results for hydropower - you need 

to do so for this - very important edit. The effects of the nobypass alternative for aquatic resource suggest that alternative 

is effective for SMB reduction, but this summary should include 

the lambda and state that its effecitveness is not significantly 

different from no action but is significantly different from the 

bypass alternatives. This is a critical update to this table. 

Otherwise decision makers will not understand that this 

alternative actually fails to reduce the SMB population and 

merely slows population growth. That does apear to be the 

case - its not any more effective than no action, so this 

summary is currently very misleading. Please include lambda 

results in this table, and in the affected environment section 

(not just the appendix) and interpret them with statistical 

signficance. Please see all the edits and refrences below to 

suppport this and then come back to these summaries and edit 

them to fully reflect the information in chap 3 after those 

revisions. 
2.13

table 2-

2 2-26 NPS

R 

Billerbec

k

The effects of no bypass alternative for aquatic resources 

indicate little impact to native fish and don't mention food base. 

Large fluctuations every weekend (up to 26 total compared to 

a max of 3 for flow spikes) would continue down to the LCR 

and even down to Pumpkin Springs with little amelioration 

according to Figure 2-6, so within GRCA that impacts locations 

like the 30 mile aggregation of HBC and native fish in Marble 

canyon. If the fluctations are in late spring or early summer 

they could impact recruitment or survival of yoy for native fish 

or HBC. They may also negatively impact GPP and 

macroinvertebrates. This also fails to state the biggest impact 

to native fish that is stated in the no action - that the SMB will 

prey upon them - if this no-bypass alternative has close to the 

same lambda values as no action (with lambda above 1 in 

most years), then the effects of increasing warmwater nonnatives should also be the same and so that is critical that that 

is stated here in the summary. This is currently stated in a way 

that suggests this language was written before the analysis in 

chp3 and the appendix was submitted based on what is 

intended in the design of this alternative, but it appears this 

table wasn't updated based on the performance of the 

modeling of lambda, which shows its doesn't accomplish the 

goal based on those lambda results - the lambda results show 

performance very comparable to no action - please update 

2.13

table 2-

2 2-26 NPS

R 

Billerbec

k

The effects of no bypass alterantive for aquatic resources 

indicate little impact to rainbow trout and food base. Our 

undestanding is that large fluctions in the past created a large 

boom/bust cycle in rainbow trout and negatively impacted 

rainbow trout (korman et al 2011). Though some other studies 

have shown compensatory effects in rainbow trout to Spring 

HFEs and other disturbance flows, the nonbypass alternative 

would be increasing fluctuations now in a time when rainbow 

trout have a very low population size and are already stressed 

by warm river temperatures, low dissolved oxygen, increased 

predation from brown trout and (given alterantive is showing 

low effectiveness to control SMB), additional predation from 

SMB... so its likely that these combination of factors would 

increase risk that the popultion would not respond with 

sufficient compensatory effects to overcome the negative 

impacts from the non-bypass alternative. Please see all the 

edits and refrences below to suppport this and then come back 

to these summaries and edit them to fully reflect the 

information in chap 3 after those revisions. 

2.13

table 2-

2 2-26 NPS

R 

Billerbec

k

For aquatic resources there is no discussion of aquatic 

parasites, yet page 3-78 points out that warmer temperatures 

are much more likely to increase proliferation of fish parasites, 

so that statement should be included for No Action and NonBypass alternatives in contrast to the bypass cooling 

alternatives.

2.13

table 2-

2 2-26 NPS

M 

Trammell

special status species - northern leopard frog is not listed as 

endangered or threatened. it is a species of concern in 

Arizona (correctly identified elsewhere in the document)
2.13

table 2-

2 2-27 NPS

R 

Billerbec

k

special status species no action this alternative will not 

reduce SMB so SMB is likely to reduce populations of northern 

leopard frog as they feed on tadpoles. no bypass alternative - 

this alternative reduces lambda compared to no-action but 

does not stop SMB population growth based on the lambda 

values, so under this alternative we would expect more impact 

to northern leopard frog from direct predation on tadpoles than 

from the other alternatives. We would direct you toward these 

references from Keisecker and Blaustein 2008 in conservation 

biology https://doi.org/10.1111/j.1523-1739.1998.97125.x 

The introduction of several species of nonnative predatory fish, 

including smallmouth bass (Micropterus dolomieu), may also 

contribute to population declines of ranid frogs (Hayes & 

Jennings 1986). Smallmouth bass are known to prey on larval 

amphibians, including red-legged frog larvae (Scott & 

Crossman 1973;Kruse & Francis 1977; J. M. K., personal 

observation). Historically, smallmouth bass were restricted to 

central and eastern North America, but they have since been 

introduced throughout western North America (Lee et al. 

1980;Minckley & Deacon 1991). Predation by nonnative fish 

can have negative effects on native frog populations (Bradford 

1989;Bradford et al. 1993). Furthermore, exotic fish may exert 

indirect effects by introducing pathogens that can be 

transmitted to amphibians (Blaustein et al. 1994b;Kiesecker & 

2.13

table 2-

2 2-27 NPS

R 

Billerbec

k

tribal resources - no action alternative - because no action 

won't reduce SMB and other warmwater invasive reproduction, 

then there will have to be more rapid response mech and 

chemical treatment to try to address these populations, thus 

increasing fish mortality over time. no bypass alternative - 

because nonbypass won't effectively reduce SMB lambda less 

than 1, then SMB and other warmwater invasive populations 

will continue to expand and there will have to be more rapid 

response mech and chemical treatment to try to address these 

populations, thus increasing fish mortality over the cooling 

alternatives. 

2.13

table 2-

2 2-27 NPS

R 

Billerbec

k

recreation no bypass alternative - non-bypass alternative - 

Currently this is missing the short term impacts to recreational 

camping in marble given large stage change during 

implementation days (will require moving boats on shore 

multiple times). Also doesn't address long term impacts to 

camping in Marble canyon from the sandbar/beach erosion 

and the reduced number of HFEs we would expect from loss of 

sandmass balance reducing chances of triggering HFEs when 

compared to other action alternatives. This also doesn't 

include longterm impacts to recreational rainbow trout fishery 

from the increased predation impacts from warm water 

predators we would expect given the lambda values we expect 

with this alterantive compared to other bypass action 

alternatives. 

3.2.1 3-2 NPS

R 

Billerbec

k

Please change the sentence "Monthly release volumes are 

based on anticipated power demands, forecasted inflows, and 

other factors such as storage equalization between Lake 

Powell and Lake Mead" to say, "Monthly release volumes are 

based on the monthly pattern of the 2016 LTEMP ROD which 

takes into account GCPA resource concerns and anticipated 

power demands, forecasted inflows, and other factors such as 

storage equalization between Lake Powell and Lake Mead". 

The monthly volumes ARE NOT based on only hydropower.

3.2.1 3-3 NPS

R 

Billerbec

k

It says "Long-term and annual release volumes from Lake 

Powell are detailed in the LTEMP FEIS (Department 2016a)." 

but this may be misleading to readers as the LTEMP does not 

set annual releases - annual releases are determined under 

the 2007 Interim Guidelines and the LROC, not by LTEMP.
3.2.1 3-3 NPS

R 

Billerbec

k

It says "Releases can also fluctuate beyond those scheduled 

in accordance with ROD section 1.2B (DOI 2016b)." please 

add these additional words "Releases can also fluctuate 

beyond those scheduled under certain allowed circumstances 

in accordance with ROD section 1.2B (DOI 2016b)."

3.2.2 3-3 NPS

R 

Billerbec

k

Please accept the tracked change shown that left in the text for 

the tempertaure of 15.5 degrees Celsius not 15.6

3-14 NPS

R 

Billerbec

k

This page states "When the high flow is then later released, 

this slug of water is expect to overtake the low flow wave by 

the time it researches river mile 61... " but that does not appear 

to be the case in figure 2-6. There is still a trough present at 

the LCR. Please edit this text as it doesn't appear correct and 

please state what the min and max will be based on that 

routing diagram when it gets to the LCR as well as what time of 

day it would be be hitting by the time it gets there. That would 

be important information grounded in the hydrology modeling. 

The current text is not grounded in the modeling and is 

incorrect.

3.2.2 3-16 NPS

M 

Trammell

under Cumulative Effects - sentence 2 - end of sentence 

'Overall elevation changes in Lake Powell under the action 

alternatives are relatively minor, and water.' '...and water.' 

does not make sense, please correct.

3.2.2

table 3-

12 3-16 NPS

R 

Billerbec

k

The way the # of HFEs statistics have been compiled doesn't 

allow for a fair comparison to hydropower results. They should 

be tabulated for only the years in which the alternative tools 

were used - in the years when temperature was greater than 

15.5 C. This was done in the hydropower section in table 3-25 

and we need apples to apples comparison of effects when the 

alternative tools are actually used. Otherwise for alternatives 

like the non-bypass that are likely reducing the # of HFEs by 

eroding the sand mass balance in the 17% of the runs in which 

the tool is being used, we can't see that effect because its 

being averaged out with the 83% of runs in which the tool 

wasn't used and it was just no action operations. We strongly 

suspect when this is run it will show a markedly lower number 

of HFEs. If that is correct, then those statistics and this big 

impact of that alternative need to be included in that top 

summary table. 

3.3.1

3-18, 

3-19 NPS

R 

Billerbec

k

Under the description of the Basin Fund it says it is used to 

support environmental and salinity funds - is this true as our 

understanding is that for the last 3 or 4 years WAPA has not 

transferred any money from the Basin Fund to environmental 

programs, and is unlikely to do so in the near future. Please 

correct if this is no longer true. Kathy Callister would know the 

most precise answer to this.
3.3.1 3-19 NPS

R 

Billerbec

k

In this paragraph "By bypassing the electrical generators at 

Glen Canyon Dam, the experiment will reduce hydropower 

generation. Accordingly, WAPA will be required to purchase 

replacement power to fulfill its contractual obligations to 

customers. The experiment would markedly increase the 

amount of non-reimbursable costs drawn from the Basin Fund 

and returned to the Treasury." It is unclear which experiment 

is being referred to - I would replace the word 'experiment' 

which is both unclear and not applied to this document, with 

"bypass alternatives". Also the statement that it will markedly 

affect the basin fund is not true under many scenarios for the 

bypass alternatives - it is entirely dependent on the hydrologic 

conditions as to how much the affect would be, so this 

statement is inaccurate and needs to be changed because it 

would only be correct under more severe hydrologies. Please 

make this paragraph consistent with the statement later in the 

plan on p3-27 that says "The action alternatives would have 

financial impacts that would vary to a large extent based on 

reservoir elevation and temperature conditions, as well as 

which river mile is targeted for cooling, based on the 

distribution of smallmouth bass."

3.3.1 3-19 NPS

R 

Billerbec

k

In the discussion of the Basin Fund it would be helpful to 

provide readers perspective that the biggest impact to the 

Basin Fund in recent years has NOT been from bypass 

operations but rather from the level of lake powell - the lower 

levels of powell have significantly impacted hydropower head 

and hydropwer production and revenue - please include a 

statement about this very improtant fact that provides 

perspective to the public. Also paragraph 5 implies that the 

basin fund is used to fund the GCDAMP, and Upper Colorado 

River Recovery Implementation Program - which it no longer 

funds, except for costs (and benefits) from experimental flows.

3.3.1 3-20 NPS

R 

Billerbec

k

It says "WAPA will continue to operate under the emergency 

exception criteria, as stipulated under the 1996 ROD", but I 

thought the 2016 LTEMP ROD replaced the 1996 ROD and I 

think it restated the emergency exception criteria in the 2016 

ROD (could be wrong, but you might want to doublecheck). I 

would guess Rod Smith would know the definitive answer on 

that.

3.3.2 3-21 NPS

R 

Billerbec

k

Under Methodology for GMCRC, it might be important to 

explain how this methodology corrects for overestimation of 

future prices - this sounded from the AMWG Lucas Bair 

presentation like an important difference between this 

methodology and the WAPA methodology that might be 

important for readers to understand. Lucas Bair could provide 

exact language for that.

3.4.1 3-43 NPS

R 

Billerbec

k

The reported durations of hfes are hard to put in context 

without a table that shows the avg duration of HFEs for both 

spring and fall HFEs - please provide that so we can 

completely compare.
3.4.1

figure 3-

22 3-46 NPS

R 

Billerbec

k

Figures 3 18 thru 3 22 all obscure the actual affects of the 

spike flows and the non-bypass alternative because they lump 

together results of 30 runs and show only an average. These 

need to broken out to show the sediment impacts in only the 

years when release temperature was over 15.5C and the tools 

were actually used. This would breakout make these results 

comparable to hydropower results in table 3-25. Without this 

its not a fair comparision. Averaging over all runs is 

problematic because we don't get to experience all of those 

futures - we may either have a future with lower reservoir 

elevations in which case the tools will be used more, or futures 

where the reservoir is higher and the tools aren't used. Those 

divergent futures will have very different results on the number 

of HFEs, the sand mass balance and the beach building and 

can't be lumped together without diluting those impacts. Also 

showing the results of these lumped situations in figures like 3-

22 makes it appear that action action alternatives are doing 

twice as many HFEs as no action and that is not the case. 

That is greatly misleading and we need to separate out these 

graphs to that is more clear to readers. If this graph will be 

used, then it will need to be in addition to graphs that split out 

runs where the tools are used versus where they aren't used 

and to explain a great deal more in the legends. We request 

contrasting in one year each of these strategies for the total 

3.4.1 3-47 NPS

R 

Billerbec

k

Statements like this summary of the non-bypass alternative 

really need quantitative numbers to understand the differences 

- need % differences between alternatives for sand mass 

balance, for beach volumes and for # and durations of HFEs to 

be clearly reported in tables. Without stats its very difficult to 

interpret the level of differences... "Compared to other action 

alternatives, the Non-Bypass Alternative would cause the 

greatest reductions in mass balance starting in Spring 2025. 

This alternative would generally produce the second-smallest 

sandbars, slightly surpassing volumes that would be generated 

under alternatives without flow spikes." The differences need 

to then be relayed quantitatively in the summary table at the 

top of the document - this is very important. That is how it is 

being done for hydropwer and if we have quantitaitve results, 

that should also be done for fish and sediment results.

3.4.1 3-47 NPS

R 

Billerbec

k

What does this mean - "Flow spikes that occur outside of the 

sediment accounting period would increase the likelihood of 

HFE deferral due to increased sediment export." Does this 

mean that flow spikes or nonpbyass flucturations happening 

after hfes in the spring windows (may-july) aren't accounted for 

because of the july 1 reset of sand mass balance? If so, we 

may be masking the loss of a lot of real sediment in each 

summer and that may be why we are seeing a lot less 

differences between alts with spikes and without or those with 

big fluctuations vs. those without. If this is the case we may 

need a true sand mass balance loss stat that is indepened of 

the sediment windows as a measure of what is being exported 

over the whole summer to compare between alternatives. And 

in the Summary seciton , we really need clearly quantitative 

results - for instance how much more sand mass balance was 

lost in a year where flow spikes or non-bypass flucutations 

were used when compared to coolmix or coldshock with no 

spikes. That would be a very useful number to see. How 

many HFEs of what duration were run with those same 

comparisons -we are quite confident there will be some clear 

differences if you make those explicit comparisions and show 

probabilities.
3.5.1 3-48 NPS 

L.Tennan

t

Strike the 'and' and add a comma after backwaters - "along 

shorelines, and in backwaters, and tributary mouths. The 

aquatic food base for fishes also includes vertebrates, such as 

other fishes, which should be added to the first sentence under 

the "Aquatic Food Base" title.

3-54 NPS 

L.Tennan

t

Differences in parasite density and abundance between the 

Little Colorado River and Colorado River are also caused by 

differences in salinity, not just temperature. The salinity in the 

LCR may actually work as a prophylactic for fishes. See Ward, 

D. L. (2012). Salinity of the Little Colorado River in Grand 

Canyon confers anti-parasitic properties on a native fish. 

Western North American Naturalist, 72(3), 334-338. 

Temperatures in the Colorado River (especially in the last few 

years) have allowed for parasites to complete their life cycles. 

3-55 NPS 

L.Tennan

t

Strike out 'two other native fish species' so the sentence 

should read, "In addittion, the flannelmouth sucker and 

bluhead sucker,....". When two other native fish species is 

mentioned, it sounds like two more native fishes other than 

what has been mentioned are goign to be mentioned in the 

senence. The word coexist in the last sentence prior to the 

figure,"....helps to explain why these species can coexist in a 

system...." makes me think that nonnative fish species and 

native fish species are inhabiting the same space peaceably. 

Consider changing the sentence to, "This figure illustrates the 

large overlap in temperature requirements of native and 

nonnative fish species found in the Colorado River and its 

tributaries, which may explain why nonnative and native fish 

species co-habitate a similar environment."

Figure 3-

23 3-55 NPS 

L.Tennan

t

Consider changing the figure title to "Optimal Temperature 

Ranges for Spawning, Egg Incubation,and Growth of Native 

and Nonnative Fishes of the the Colorado River System Below 

Glen Canyon Dam"

3-56 NPS 

L.Tennan

t

Strike out "Of the remaining three species-" from the first 

sentence on page 3-56. Consider changing the sentence to, 

"The Zuni bluehead sucker, Little Colorado sucker, and Little 

Colorado spinedace are endemic to the upper reaches of the 

Little Colorado River. Change mainstream to mainstem in 

sentence, "....have been extirpated from the mainstream 

between....." Change all occurences of mainstream to 

mainstem when referring to the mainstem Colorado River. 

Figure 3-

29 3-56 NPS 

L.Tennan

t

Razorback sucker have been found from Phantom Ranch to 

Pearce Ferry; might have to re-check accounts of speckled 

dace being captured as high up as Glen Canyon Dam, maybe 

from the Paria River downstream. Strike out 'with tributary fish 

being smaller' from sentence, "This species has been reported 

to be as large as..." since it was already mentioned that 

bluehead sucker may be smaller in tributaries. Strike out 

'subspecies, as', from sentence "A related subspecies, the 

Zuni bluehead sucker, occurs in the headwaters of the Little 

Colorado River along with bluehead sucker that is the same 

subspecies species as in the mainstream Colorado River 

(AZGFD 2002a).
3-57 NPS 

L.Tennan

t

Where is the supporting citation for this sentence? "Bluehead 

suckers are found more often in GCNP with warmer dam 

releases." Change capitalization of "Lower" to "lower Colorado 

River" in sentence, "relatively high numbers of individuals 

remain in the Lower Colorado River between Lava Falls Rapid 

(river mile 179) and Lake Mead". Where is more recent 

information from the larval fish studies (which occurs every 

year)? The data from this sentence, "Sampling of the larval fish 

community in the western Grand Canyon between Lava Falls 

and Pearce Ferry collected bluehead sucker larvae throughout 

the analysis area (Albrecht et al. 2014). In this analysis area, 

the bluehead sucker was the most abundant species in the 

larval fish community, composing almost 40 percent of the total 

catch." is ten years old now. 

3-58 NPS 

L.Tennan

t

This sentence, "Smaller tributaries may provide nursery 

grounds for populations of large adjacent rivers (Rinne and 

Magana 2002)." could use some clarity

3-59 NPS 

L.Tennan

t

Add a comma after Paria Rivers in sentence, "Within the 

Grand Canyon, this species may be found in the mainstream 

Colorado River and its tributaries, including the Little Colorado 

and Paria Rivers, and Shinumo, Bright Angel, Kanab, and 

Havasu Creeks."

3-62 NPS 

L.Tennan

t

Under life history: Strike this and replace with Speckled in 

sentence, "This Speckled dace spawns twice, once in spring 

and again in late summer (AZGFD 2002b)" Under Factors 

Affecting....: This sentence, "Although this species is the most 

widely distributed and abundant native fish species in the 

Grand Canyon ecosystem, its abundance and distribution 

could be affected by many of the same factors that affect the 

abundance and distribution of the other native fish in the 

ecosystem, namely altered temperature, flow, and sediment 

regimes and predation by nonnative fish" needs to be 

reconsidered. Speckled Dace may not be the most widely 

distributed or abundant fish species any longer (e.g., 

flannelmouth sucker). Consider changing sentence to, 

"Speckled Dace abundance and distribution could be affected 

by many of the same factors that affect the abundance and 

distribution of the other native fish in the ecosystem, namely 

altered temperature, water flow, sediment regimes, and 

predation by nonnative fish." Under nonnative fish: The three 

species of fish mentioned in this sentence "Among these 

nonnative species, three are largely restricted to Lake Powell 

and/or Lake Mead and are found in the Colorado River and its 

tributaries below Glen Canyon Dam only occasionally; these 

species are black crappie, bluegill, and gizzard shad (Table 3-

30)." are actually becoming increasingly more common to 

Table 3-

30 3-63 NPS 

L.Tennan

t

Brown trout are incredibly abundant from Glen Canyon Dam to 

Lees Ferry; Channel catfish fairly abundant near and in Little 

Colorado River; Bluegill are becoming more abundant and 

captured in electrofishing surveys close to Glen Canyon Dam 

and from the dam to Badger Rapid in Grand Canyon; 

Largemouth bass individuals have been recently captured 

(2022) in Glen Canyon below the dam; Smallmouth bass found 

in increasing numbers in Glen Canyon from the dam to Marble 

Canyon. See R. Billerbeck's comment below please. Also, 

please add updated distribution maps or data tables from 

Katherine Tucker (BOR on detail to GCMRC) or from Melissa 

Trammell at NPS. This table is grossly outdated and 

misleading - sorry but you really need up to date info because 

so much has changed in the last few years. This is very 

important. should be a more effective way to do this broken 

into more relvant sections of the river.

3-64 NPS

R 

Billerbec

k

There is a more recent compilation of non-native occurances 

in the appendix of the NPS Expanded Non-Native Aquatic 

Speces Management Plan EA
3-66 NPS

R 

Billerbec

k 

3-68 NPS

M 

Trammell

first para states SMB may have moved down the LIttle 

Colorado River, but recent conversations with FWS (David 

Ward) and Arizona Game and Fish (indicated there are no 

SMB in the LCR in Grand Canyon, and only one source in the 

drainage which is being actively addressed by removal, thus 

most most SMB originated either in Mead or entrained from 

Powell, until recent reproduction below the Glen Canyon Dam 

beginning in 2022

3-68 NPS

R 

Billerbec

k

first para - "Starting in 2022, many of the bass are smaller, 

indicating that these fish have been produced locally, probably 

in and around the -12-mile slough." Is this conclusion correct 

or should it actually be qualified a bit to state that the majority 

of SMB may have been produced in the slough but many may 

have been entrained as young or spawned in other backwater 

areas including just below the dam... it seems like its very 

possible some were the result of entrainment of small 

individuals passing through the dam given findings upstream 

of the slough 

3-68 NPS

R 

Billerbec

k

This section really needs the graph of lamba from the 

appendix inserted directly into the text here - that is the most 

important data/modeling result in this plan and should be 

directly in the text given its importance for this decision as are 

the hydropower impacts. Also like hydropower we should have 

clear reporting of the statistics, not just a graph. Please add a 

table with the average lambda for all 30 runs for each 

alternative, and a % of runs for which the lambda is greater 

than 1. Those 2 statistics should be in there in a table and 

should also be ported up to the top summary.

3-69 NPS

M 

Trammell

Add a sentence on turbidity effects on predation of SMB on 

fish species. Although turbidity has been reported to reduce 

SMB feeding efficiency (Ward and Vaage 2019), evidence 

from the Upper Basin, which is perpetually turbid with values 

usually above 50 FNU and often above 1000 FNU, seems to 

indicate that SMB can survive and thrive at NTU/FNU regularly 

higher than 50 (125 JTU, approx), and have population level 

effects on native fishes (Bestgen and Hill 2016). 

Ward, D.L. and Vaage, B.M., 2019. What environmental 

conditions reduce predation vulnerability for juvenile Colorado 

River native fishes?. Journal of Fish and Wildlife Management, 

10(1), pp.196-205.
3-72 NPS

R 

Billerbec

k

The section on Rainbow trout seems to be outdated - only 

talks about daynamics to about 2018... its missing all the 

dyanmics and pressures that have been occuring in the last 2-

3 years - increased river temperatures, decreased dissolved 

oxygen, increased predation/competitiion. These are 

important context for why the population is so low right now 

and related some of the alternatives that would be like to lower 

river temperature and improve the dissolved oxygen situation. 

Please see the presentations and graphs of rainbow trout from 

the GCMRC Annual Review Meeting proceedings from Jan 23-

25 2024 to get the necessary updated info that shows the 

updated and very low population levels, the information about 

the low dissolved oxygen levels and the increased 

temperatures. Or if needed I'm sure Brian Healy and Josh 

Korman could provide the best data and references. This 

information is critically important as some of the alternatives 

like the non-bypass may reduce rainbow trout recruitment and 

the currently low population level and stressors may prevent a 

compensatory response so your text as well as your analytical 

conclusions need to be updated with the current population 

and dyanmics in Lees Ferry.

3-70, 

74, 75 NPS

R 

Billerbec

k

The sections on cold-water nonnative Species and brown trout 

seems to be outdated - only talks about dynamics to about 

2015 in much of it with incorrect conslusions or up to 2018 with 

the Runge report. There is a lot of new info since then. For 

instance this statement "Because spawning by brown trout in 

the Grand Canyon occurs primarily in tributaries " is now totally 

incorrect. It may have been correct in 2014 but hasn't been 

correct since as we've documented a lot of spawning in Lees 

Ferry since 2015 - that whole paragraph needs to be updated 

with what we've seen from 2015-2024 with current population a 

graphs. Brown trout are no longer 'on the cusp' of recruiting 

locall hatched fish - they have recruited every year since 2016. 

Again - please see the presentations and graphs of rainbow 

trout and brown trout from the GCMRC Annual Review 

Meeting proceedings from Jan 23-25 2024 to get the 

necessary updated info that shows the updated and very low 

population levels of rainbows, the increasing number of 

browns and , the information about the low dissolved oxygen 

levels and the increased temperatures. Or if needed I'm sure 

Brian Healy and Josh Korman could provide the best data and 

references.

3-76 NPS

R 

Billerbec

k

Table 3-31 is probably very outdated. Please get updated 

distribution maps for the LCR from GCMRC or FWS. 

3-78 NPS

R 

Billerbec

k

there are extra characters in this sentence - fix to say improved 

humpback growth and survival I think. For example, the 

temperature of water released from Glen Canyon Dam 

increased during the trout removal study period to 

temperatures that may have improve“ humpback c”ub growth 

and survival

3-79 NPS

M 

Trammell

please add a paragraph that interactions between native fish 

and increasing numbers of SMB and GSF are likely to 

increase, and that these native fish will be subjected to much 

higher predation levels from warm water non-native fish as 

they get established. Increases in smallmouth bass, green 

sunfish, walleye and others would be very likely to greatly 

reduce young native fish survival levels. There is abundant 

evidence from the upper colorado river basin, (Johnson et al. 

2008, Bestgen and Hill 2016, Martinez et al. 2014 and other 

references), that should be stated here to discuss this 

interaction of smb impacting native fish. 
3-78 NPS

R 

Billerbec

k

Given that you draw the conclusion on 3-78 that " these 

warmer temperatures will likely provide more suitable 

conditions for the proliferation of a number of fish 

parasites that could negatively affect native fish species 

(see Figure 3-34)." Then why is isn't this important factor 

addressed in table 2-2. It should state that parasites are much 

more likely to increase under No Action and Non-Bypass than 

under the action alternatives that cool summer temperatures. 

Please be sure this significant aquatic resource issue gets 

included in the table 2-2.

3-79 NPS

R 

Billerbec

k

 p g p 

affected significantly by fluctuating flows is much less likely to 

be true now. Rainbow trout recruitment is likely to be affected, 

as it was prior to the MLFF. Given currently very low 

population size and other stressors from warmer temperatures, 

low do and more predators and competitors, there is much 

greater chance that extreme fluctuating flows such as the nonbypass 2000cfs to 27000cfs will affect the rainbow trout. If you 

look at figure 8 in the korman 2011 paper, you will notice that 

te compensatory response is happening when the reproducing 

population is in the > 2 million eggs part of the stock 

recuitment curve. however the current population size of 

rainbow trout is smaller than the 2006 population size which is 

at the far left of that graph less under a 1 mllion eggs level, so 

its much less likely there would be a compensatory response. 

Please include that figure in this LTEMP SEIS and check with 

GMRC experts like Brian Healy to help interpret why this may 

mean a compensatory response is a lot less likely. this is a 

very important consideration because the non-bypass 

alternative particularly presents this risk to rainbow trout 

population and to the rainbow trout fishery and this risk needs 

to be highlighted in this aquatic resources ipacts section and 

reflected in the table 2-2 summary. The flow spikes and HFEs 

are likely to have less impact because they don't drop as low 

3-80 NPS 

M 

Trammell Typo in middle of first para - ...a fe" brown trou"

3-81 NPS E Omana

Nonnative removals have not occurred in Shinumo Creek 

since 2014. 

3-81 NPS E Omana

This is all very outdated. Removal efforts have continued and 

are ongoing. Published results are in Healy et al. 2018 and 

Healy et al. 2020; annual reports summarize data through 

2022

3-82 NPS

R 

Billerbec

k

The paragraph beginning 'In 2017...' implies that the the 

proposed project of connecting the slough to to mainstem 

Colorado was actually done, which it wasn't. Suggest moving 

the last sentence (as modified below) above the information 

about the proposed connection project. Otherwise, the 

information on green sunfish is good for the time period 

covered, but a lot has happened in the last 3 years that this 

paragraph doesn't talk about. Green sunfish have increased in 

extent significantly in the last 3 years - again Melissa 

Trammell/Emily Omana/Jeff Arnold can provide catch data and 

Katherine Tucker can provide extent maps. Also there is 

information from Barrett Freissen (USU) study in the forebay of 

small green sunfish massing near the dam and good evidence 

to suggest that smaller green sunfish are entraining through 

the dam and you state that elsewhere in the plan. Would be 

good to update this sentence "Despite these efforts, green 

sunfish are regularly captured by fish monitoring efforts in the 

mainstem river." with a few sentences about these more recent 

findings. Melissa Trammell or Jeff Arnold could also provide 

#'s of GSF that were lethally treated during the last two years 

rotenone treatments in the slough. 
2.4 2-4 NPS S. Haas

Would actions be initiated as soon as temperatures hit these 

triggers, or after XX hours above this temp, or after XX days? 

Temps fluctuate throughout the day. Define the trigger more 

specifically. It matters how long the river is at this temp and 

SMB may actually breed when the temp is slightly below 16C. 

Will there be seasonal limits to target just the spawning 

season, or any time the temp trigger is met? We are 

assuming it would be based on temperature projections and 

the operations would be carried out for the full month of when 

the 15.5C temperature trigger is reached, but it should be 

clarifiied

3-84 NPS

M 

Trammell

Under Issue 1: It is possible that 'other mitigations' will not be 

present by 2027, or will not be sufficient to avoid establishment 

of SMB. To clarify this we suggest changing this sentence to 

say 'These alternatives were modeled through 2027, with the 

anticipation that other mitigation factors will be present by 

2027; however, if such factors are not present or insufficient to 

avoid establishment of SMB, implementation of these 

alternatives may be extended past 2027." 

3-85 NPS

R 

Billerbec

k

We have a few specific requests here for how to present the 

SMB lambda modeling results to be comparable to hydropower 

results for fair evaluation of all the alternatives: 1) The lambda 

results in appendix A should be inserted here directly given 

how important these results are to evaluting all the altenratives 

for purpose and need. The hydropower results are direclty in 

the text but hydropower is not part of the purpose and need but 

the efficacy of SMB populatipon reduction is. 2) the figure for 

the results needs some reformatting - the labels should be 

below the axis and the solid lines representing where the 

majority of runs landed should be dot like the other result 

locations. the level at which most of the results are coming out 

needs to be labeled (is it 90%, 92%, 95%? Also the figure 

legend needs to state more clear that lambda below 1 means a 

decreasing SMB population whereas a lamda over one means 

an increasing population and a lamba of 2 means the 

population is doublling. Also you need to state in the figure 

legend what percent of the runs didn't have any release 

temperatures over 15.5C - I suspect is 17% or close to that - 

that is really important to tell because that means that if no 

action and no bypass are maintaining lambda below 1 for 83% 

of the runs that is only because the temperatures never got 

high! so the action part of no bypass is not working to keep 

lambda below 1 for any runs. If that is true you need to 

3-86 NPS

M 

Trammell

the citation (Summit Technologies Inc. 2022) is not included in 

the list of references. please add.

3-86 NPS

R 

Billerbec

k

For no action native fish section, you are missing the biggest 

issue - that these native fish will be subjected to much higher 

predation levels from warm water non-native fish as they get 

established. Increases in smallmouth bass, green sunfish, 

walleye and others would be very likely to greatly reduce 

young native fish survival levels. There is abundant evidence 

from the upper colorado river basin, (Johnson et al. 2008, 

Bestgen and Hill 2016, Martinez et al. 2014 and other 

references), that should be stated here to discuss this 

interaction of smb impacting native fish. This is the most 

important impact so please add a sentence specific to that 

here. Also you should mention that spring HFEs are very 

similar to the natural yearly peak flows that existed pre-dam 

that the native fish evolved with - that is quite an important fact 

when discussing the potential impact of spring HFEs. If native 

fish weren't able to deal with a spring HFE that would be very 

odd since it would the most like the hydrology that they 

experienced every year pre-dam.

Martinez, P., K. Wilson, P. Cavalli, H. 

Crockett, D. Speas, M. Trammell, B. 

Albrecht, and D. Ryden, 2014, Upper 

Colorado River Basin Nonnative and 

Invasive Aquatic Species Prevention and 

Control Strategy . February 2014. 

https://www.fws.gov/Region6Test/generalinformation/programelements/nna/BASINWIDENNFSTRATEG

YFeb2014.pdf. Accessed August 27, 2018. 

and Johnson, B.M., Martinez, P.J., 

Hawkins, J.A. and Bestgen, K.R., 2008. 

Ranking predatory threats by nonnative 

fishes in the Yampa River, Colorado, via 

bioenergetics modeling. North American 

Journal of Fisheries Management, 28(6), 

pp.1941-1953.
3-86 NPS

R 

Billerbec

k

For no action non-native fish section, you are missing the 

biggest issue - that the the non-native fish will increase in 

numbers and expand downstream in years when river 

temperature exceeds 15.5C. You need to provide the no 

action average lambda for the years that exceed 15.5C and 

you will see its generally over 2 meaning the population of 

SMB will more than double each year this happens. This is 

critical to state and to explain - its the biggest and most 

concening effect of no action and its why we are doing this 

SEIS and its not clearly stated in this section. Please add a 

few sentences talking about how Smallmouth bass, green 

sunfish, walleye and other invasive predators have been 

increasing, and predation on native fishes is expected to 

increase as a result, as the invasive predators become 

established. Increases in smallmouth bass, green sunfish, 

walleye and others would be very likely to greatly reduce 

young native fish survival levels (see references in above 

comment). This is the most important impact so please add a 

sentence specific to that here. 

3-88 NPS

R 

Billerbec

k

In the top section of cool mix, you state For river mile 15, 

predicted λ is > 1 for none of the traces in 2024-2027. For river 

mile 61, the model predicted λ is > 1 for none of the traces in 

2024-2027. No uncertainty in model inputs, functional 

relationships, or outputs are described ." While this is correct, 

you need to interpret that because this is one of the most 

important results in the plan. Firstly you should stated the 

inverse, that for all all traces, including all of those where 

release temp was > 15.5C, it kept the lambda less than 1. You 

should provide the average lambda for the years or months 

that exceeded 15.5C and it will show the lambda was < .96. 

You then need to explain that this result is showing that this 

would mean the SMB population would be declining - it would 

get smaller each year. This is versus alternatives like non 

action and non-bypass that have a lambda well over 1, often 

over 2 for years or months where temperature > 15.5C. That 

means those alternatives are allowing the SMB popuation to 

increase and in fact double when lambda > 2. Please 

interpret this result clearly for the public. And again, we can't 

say enought that you need to break out the lambdas for the 

month or years in the traces that exceeded 15.5C, otherwise 

you are avearaging it with the 83% of traces where SMB would 

not be growing anyway. Hydropower broke out their results for 

those years so SMB impacts need to broken out that way as 

3-88 NPS

R 

Billerbec

k

For coolmix native fish section, you are missing the biggest 

issue - that for this alternative there will be much less 

predation from warm water non-native species than no action - 

you talk about the effect on non-natives below it, but you need 

to draw the conclusion in the native fish section that the control 

of non-antives that this alternative would provide will avoid the 

much higher predation that would exist under alternatives that 

do not keep smb lambda under 1 (no action and non-bypass). 

You need to explain that here.

3-88 NPS

R 

Billerbec

k

For coolmix native fish section, you are missing the biggest 

issue - that for this alternative there will be much less 

predation from warm water non-native species than no action - 

you talk about the effect on non-natives below it, but you need 

to draw the conclusion in the native fish section that the control 

of non-natives that this alternative would provide will avoid the 

much higher predation that would exist under alternatives that 

do not keep smb lambda under 1 (no action and non-bypass). 

You need to explain that here.
3-88 NPS

R 

Billerbec

k

For coolmix non-native fish section, you are missing the 

biggest issue - that this alternrative will not have growth of 

warm water invasive fish like SMB, GSF and walleye - those 

species would DECLINE with an avg lamdba <1 for years or 

months where relase temp exceeds 15.5C. That is in great 

contrast to no action and non-bypass that would have 

incresing populations in those years. Please state that clearly 

as well as how this altenative reduces predation pressure on 

native fish.

3-89 NPS

R 

Billerbec

k

Where you state "However, since smallmouth bass have been 

detected mainly in the Glen Canyon reach, implementation of 

this alternative could still be effective at reducing the likelihood 

of successful spawning of smallmouth bass where most fish 

have been found as of the end of 2023." It should also be 

stated that this is a reason not to delay the use of this tool, 

because if its not implemented in 2024, then the range of warm 

water invasives is likely to expand further and this tool would 

then be less effective.

3-90 NPS

R 

Billerbec

k

For cool mix native fish and non-native fish sections, again the 

obvious most important impact of controlling the SMB and 

other warm water fish needs to be stated hear and the average 

lambda for years or months that exceed 15.5C should be 

stated. The biggest impact on native fish is that their young 

won't be preyed upon by expanding warm water invasive fish. 

The biggest impact on non-native fish is that they won't be 

expanding and in in fact their populations will be decreasing 

over time. It should also be noted that flow spikes are very 

much like the naturally timed peak flows that were there every 

predam in May and June that the native fish evolved with. 

3-91 NPS

R 

Billerbec

k

Once again where you state "For river mile 61, the model 

predicted λ is > 1 for 0 percent of the traces in 2024 but is 

predicted to be > 1 for 10 percent of the traces evaluated by 

2027 ." you need to interpret this result for the public and you 

should state the inverse - under what conditions is it keeping 

lambda < 1. You also need to talk about not all traces, but 

what percentage of the traces where release temps > 15.5C. 

Those are the important years where the tools are needed. 

And again in the native fish section, you need to state the 

obvious effect that if warmwater non-natives aren't expanding 

as much as under no action that this alternative will have more 

successful native fish reproduction over time. This is so 

important to state and explain here as it is the reason these 

alternatives are even being considered. Please add it.

3-91 NPS

R 

Billerbec

k

for cold shock with flow spike - where you talk about lambda 

values, you need the average lambda for the years where 

release temp > 15.5C provided, you should again state the 

inverse of the way you do- when does it keep lambda < 1 

because that is our goal, and you need to interpret and explain 

that that means the warm water invasive fish populations 

would be decreasing rather than increaseing. Again needs to 

be contrasted with no action and non-bypass where lambdas 

in those years is well over 1 and often well over 2. 

3-93 NPS

R 

Billerbec

k

for cold shock with flow spike native fish and non-native fish 

you need to include the most important effects - that compared 

to no action or nonbypass young native fish under this 

alternative would not be subjected to increasing predation from 

expanding populations of SMB, GSF, that are likely under no 

action and non bypass. This is the most important effect and 

needs to be clearly stated and interpreted in these sections
3-94 NPS

R 

Billerbec

k

Where you state "The Non-Bypass Alternative consists of 

weekly flow spikes" you need to clarify more and distinguish 

from flow spikes in the other alternatives. These aren't just 

flow spikes - it’s a quick drop to 2000cfs followed by a flow 

spike - this matters because that drop increases that chances 

of impacting native fish. While an increase from a flow spike in 

spring is like a natural spring peak flow, this drop followed by 

an increase is not. This is important. Also you need to state 

how many of these are occuring under the warmer traces - 

when is the max# happening in a summer. The flow spikes for 

the other alternatives are limited to 3. These could occur 

much more - could be that they would occur every weekend 

May-Oct - I think that would 26 times - if that is occuring the 

traces, you need to state that because its VERY VERY 

different from the flow spikes in teh other alternatives. That is 

a huge frequency of a flow that would be likely to impact a lot 

of resources. That is NOT clear in any way from this text to 

the average reader. Please make it very clear.

3-94 NPS

R 

Billerbec

k

Where you state For river mile 15, predicted λ is 1 for none 

of the traces in 2024 but is predicted to be > 1 for 17 percent 

of the

traces evaluated by 2027. For river mile 61 (confluence with 

the Little Colorado River), the model predicted λ is > 1 for 3 

percent of the traces in 2024 but is predicted to be > 1 for 17 

percent of the traces evaluated by 2027. " This needs to be 

reported as the average lambda for the years where river temp 

exceed 15.5C. That is important since that only occured in 

about 17% of the traces. You need to state that is where the 

17% is coming from - its the traces where the river gets hot, 

that this tool doesn't work - just like no action. if you are 

averaging to include all the traces where this tool wasn't 

needed you are not showing its effect. If you do it this way, it 

will show that lambda is over 1 for all the years where we 

needed to try to control the SMB populations. You need to 

explain that its not working to prevent increase and expansion 

of SMB. This is the most critical result of this whole plan and 

its not intepreted here - you need to explain it. If this 

alternative is failing to make SMB less than one, then the SMB 

and other warm water populations will expand and impact 

native fish at very close to the levels that would occur uner no 

action. That is not clearly stated in the summary of this plan or 

in this section and you have to relay that information fairly 

3-95 NPS

R 

Billerbec

k

Where you state "For frequency, releases would be weekly to 

keep bass from successfully renesting. " you should again 

state how many of these possible in a summer - from my count 

it ran from May 1-Oct 31 that would be 26 times - that is huge 

and important to provide. If its less than that given the 

occurances in the traces then just provide the average and 

max in years that have temps over 15.5C.

3-95 NPS 

R 

Billerbec

k

For the native and nonnative fish sections of the non-bypass, 

you are missing the most important effects. Based on the 

lambda modeling, this alternative will experience growth and 

expansion of SMB, GSF under years where temps are > 15.5C 

and there will be effects to young native fish from increasing 

predation from these warmwater invasives. This is not 

reflected in the text and its the most imprtant conclusion. The 

effects here to native and non-native should be decribed as 

very simliar to no-action based on the lambda modeling. This 

is critical since this alternative may have negative impacts to 

other resources, yet is not controlling SMB and preventing it 

from increasing and spreading. This needs to be clearly stated 

on this page as an impact to native fish and as the effect to the 

non-native fish population and contrasted with the alternatives 

that do control SMB. 
3-95 NPS 

R 

Billerbec

k

Where you state "The native Colorado River Basin fish 

evolved in a highly variable flow environment, and 

assessments of how juvenile humpback chub use different 

habitats or their survival rates did not vary during a transition 

from fluctuating to steady flows below the Little Colorado River 

(Gerig et al.2014)." but again we would point out that these 

aren't just flow spikes or hfes that might resemble a natural 

spring peak... these are fluctations that start with a quick drop 

to 2000cfs followed by a big flow spike and these would occur 

at a very high freuqency of every weekend and could occur all 

the way from May-Oct - which might be a max of 26 times - if 

that is occuring in any of the traces, you need to state that 

because its VERY VERY different from the flow spikes in the 

other alternatives and very different from a natural spring 

peak. We don't feel like these references or this analysis is 

complete. We would ask for more input from GCMRC on the 

effects on native fish in marble canyon from these flows. 

Particularly the 30 mile aggregation of humpback chub of 

concern for us with these 26 big fluctations throughout the 

summer. The waves from these fluctuations do not really 

substantially ameliorate by the time they reach the LCR, or 

even Pumpkin springs according to the figure included.

3-95 NPS 

R 

Billerbec

k

In the non-native fish section of non-bypass, it talks about the 

mechanism for how this *MIGHT* work but doesn't include and 

discuss the modeling results for SMB lambda, that suggest it 

doesn't work to reduce lambda below 1. The lambda values 

need to included and talked about here. Also when discussing 

the mechanism for how the flucutations might impact, it states 

"For smallmouth bass, rising water would flush solar-warmed 

shoreline nest areas with water at the temperature of main 

river, potentially causing nest desertion and halting embryo 

development if the main river temperatures are significantly 

lower." it says that the temperature difference is what might 

make this work, but we would stress that this tool will only be 

used when river temps are over 15.5C and warmer. So the 

main river temperatures would NOT be significantly lower 

unless bypass was used. Again, this is really important to 

provide some clear interp here or more info on how much of a 

temperature difference is needed. It seems to us this 

statement indicates why flow spikes paired with bypass cooling 

might have this effect more than this tool that is used instead 

of bypass. Please try to evaluate these effects for the flow 

spike alterantives and explain the mechanism there like you do 

here. 

3-95 NPS 

R 

Billerbec

k

We are very concerned that it doesn't appear these very 

frequenct fluctuations with a drop to 2000 then a spike that 

may be used up to 26 times a summer don't appear like they 

dissipate by river mile 30 where an aggregation of HBC has 

persisted for many years. We will like impact to the humpback 

there and in the upper parts of Marble canyon that would be 

effected by these fluctuations to be fully addressed. 

3-96 NPS

R 

Billerbec

k

The effects to rainbow trout discussed here at the top of this 

page appear to us to be correct, but they don't match your 

conclusions on the previous section specific to trout or in the 

summary of effects at the top of the plan. These conclusions 

are right and need to be used to update the other sections. 

This section shoudl also note that this non-bypass alternative 

would be likely to expertince more low DO events and more 

warm river temperatures that will continue to stress what is 

already a low population level of rainbow trout that is in poor 

health condition whereas the bypass alternatives would reduce 

the temperature and low DO stressors for the rainbow trout.
3-96 NPS

R 

Billerbec

k

For the discussion on no bypass effects to aquatic food base, 

1) we are concerned that this section uses a reference (Blinn 

et al 1999) that study that evaluated an early spring high flow 

and that information is is likely not applicatable to these flows 

that are drop much lower and run throughout the whole 

summer. The argument that the dessication is occuring at 

night is problematic given that the dessication would occur 

during the hottest parts of the summer when temperatures are 

much higher at night than during the 1996 spring flow that 

Blinn considered in this paper. 2) Also with the propagation of 

the fluctations downstream it won't be at night by the time the 

fluctuation propagates to the LCR and from figure 2-6 it looks 

like it doesn't dissipate very much by the time it gets there so it 

will be happening in daylight in july/aug heat down further. 3) 

Again, we would highlight that these fluctuations go low before 

they go high and the frequency and timing are very different 

than a natural spring peak flow - these are occuring every 

weekend, potentially all summer so possibly as many as 26 

times. The bug flow experiments in the last few years lasted 

only a few weeks but showed definite changes to 

macroinvertebrastes, so it seems very challenging to believe 

that we would conclude these have no impacts. 4) this 

section seems very incomplete/incorrect regarding food 

base/macroinvert effects and you need input from Ted 

3-97 NPS

R 

Billerbec

k

You state that "Previous flow experiments below GCD to 

interrupt rainbow trout spawning caused mortality of rainbow 

trout eggs and fry, but recruitment did not decline because of 

compensatory survival of the remaining young rainbow trout 

(Korman et al. 2011)." but Korman's work was at time of a 

much larger and healtheir population of rainbow trout. As we 

commented on p 3-79, given current rainbow trout population 

size, and given current health and stressors (low DO, high 

temp, increasing preadtors), this work is likely not applicable to 

this situation. Please see our comments up on 3-79 and 

please contact Brian Healy from GCMRC for more perspective 

on why comprensatory response is unlikely

3-97 NPS

R 

Billerbec

k

This statement needs more qualification "The five alternatives 

each have the potential to disrupt smallmouth bass spawning 

by either desiccating or inundating nesting areas, creating 

unsuitable water temperatures, or both ." As you say just 

above this the lambda values for the bypass options are below 

one, but for the non-bypass its not showing that it performs 

differently from no action - again you have to get lambda 

values for the summers in which temperature > 15.5C and see 

what % of those non-bypass and no action are able to keep 

lambda less than one - I think it will be zero or nearly zero. 

these statements that indicate non-bypass actually controls 

smb are inaccurate, so please edit and qualify those wtih the 

modeling results. 
3-97 NPS

R 

Billerbec

k

You state "Generally, the five alternatives are not expected to 

have a negative population-wide effect on native fish, as these 

species have adapted to a large range of flows and 

temperatures in the Colorado River. However, all alternatives 

assume that establishment of smallmouth bass will have 

impacts on native fish populations, which is consistent with the 

recommendations of the Smallmouth Bass Ad Hoc Group 

report (2023). " You need to add these two statements 

together - because if smallmouth bass will have impacts on 

native fish populations, then that first sentence is not true - the 

alternatives that don't control SMB (avg lambda in years > 

15.5C) such as no action and no bypass will have a big 

negative impact on native fish compared to the alternatives 

that use bypass and control SMB. Or if you look at in 

comparision to no action then the no bypass will have the 

same negative impacts as no action but the bypass altenraives 

will have a positive impact on native fish by comparision.

3-97 NPS

R 

Billerbec

k

You state, "These alternatives are not expected to have longterm negative effects on rainbow trout in the Lees Ferry 

reach ." but see the comments above about how the rainbow 

trout popuation in a very different situation then it was for 

Korman's 2011 study and how assuming compensatory 

response may not be appropriate. Also alternatives that don't 

control SMB will likely have added predation affecting rainbow 

trout at the population level - that may be an important impact 

to add.

3-105-

106 NPS B Holton

You include only three amphibian species in the riparian zone. 

Change to 5 documented amphibian species, which includes 

native lowland leopard frog (Rana yavapaiensis) in western 

GRCA and tiger salamander( Ambystoma mavortium) in the 

Glen Canyon reach. A single isolated population of lowland 

leopard frog exists in a perennial side canyon in western 

GRCA. This population is of unique genetic value, and subject 

to deleterious effects from aquatic invasive species, such as 

predatory fish and crayfish. Northern leopard frogs (Rana 

pipiens) are functionally extinct in GRCA in the riparian zone in 

the post dam era, but exist in small pockets on the northern 

rims of GRCA. Northern and lowland leopard frogs are both AZ 

Species of Special Concern, and habitat suitability models 

have been created for GRCA in anticipation for future 

reintroduction and population supplementation efforts. 

3-106 NPS B Holton

Change Grand Canyon pink rattlesnake to Western 

rattlesnake (Crotalus oreganus). Crotalus viridis is the prairie 

rattlesnake not found in the GC river corridor. 

3-106 NPS B Holton

Include potential impacts to native amphibian species from 

warm water predatory fishes. Predator fish can have adverse 

effects on amphibians at community and population levels 

(Watson and Mullin, 2007). Small-mouth bass significantly 

affected the survivorship of native frogs (eg. red-legged frogs) 

especially when in combination with other predatory aquatic 

invasive species (Kiesecker and Blaustein, 1998). Predatory 

fish have likely rsulted in altered amphibian species 

assemblages and reduce community diversity (Hecnar and 

Mcloskey, 1997). 

3-106 NPS B Holton

Walston, L.J. and Mullin, S.J., 2007. Responses of a pondbreeding amphibian community to the experimental removal of 

predatory fish. The American midland naturalist , 157 (1), pp.63-

73.

3-106 NPS B Holton

Hecnar, S.J. and M'Closkey, R.T., 1997. The effects of 

predatory fish on amphibian species richness and 

distribution. Biological conservation , 79 (2-3), pp.123-131.
3-106 NPS

R 

Billerbec

k

where you state Amphibians tend to use backwaters or 

shallow waters of aquatic and riparian habitats " you should 

also provide literature references for how much warmwater nonnatives like SMB and GSF impact native amphibians. Here is 

literature to consider drawing from to include this important 

effect that will differ among the alternatives: Smallmouth 

bass and green sunfish predation on amphibians

Fish are not the only taxa affected by invasive M. dolomieu; 

mammals, birds, amphibians, reptiles, and invertebrates can 

be impacted as well. M. dolomieu will consume almost any 

prey small enough to ingest including crayfish, rats, mice, 

young waterfowl, frogs, snakes, and salamanders (Sanderson 

et al. 2009). Frog species can be impacted by predation from 

M. dolomieu, although the severity could depend on the 

presence of other invasive species and the life stage of the 

frog (Kiesecker and Blaustein 1998).

Sanderson BL, Barnas KA, Wargo Rub AM (2009) 

Nonindigenous

species of the Pacific Northwest: An overlooked risk to

endangered salmon? BioScience 59(3): 245–256,

http://dx.doi.org/ 10.1525/bio.2009.59.3.9

Kiesecker JM, Blaustein AR (2008) Effects of introduced

bullfrogs and smallmouth bass on microhabitat use, growth,

3-107 NPS B Holton

Under Mammals: Include that GRCA has the highest diversity 

of bat species in all NPS units

3-110 NPS

R 

Billerbec

k

We disagree with the analysis conclusion that "Under the No 

Action Alternative there would be no change to the current 

trajectories for wildlife species that use riparian habitats, 

including invertebrates, amphibians" We would point to the 

references we provided for page 3-106 for the abundant 

literature for SMB and GSF impact amphibian populations. 

Any amphbians in backwater habitats are likely to be impacts if 

SMB and GSF establish along the river. There should 

discussion of that impact for any alternative where the average 

lambda is greater than 1 in months where temperatures 

exceed 15.5C

3-112 NPS

R 

Billerbec

k

For the Non-bypass alterantive, we would request that you add 

in impacts to amphibians from increasing popuatlions of SMB 

and GSF. Based on lambda modeling results, this alternative 

should perform very simliarlly to no action and these 

popuations should expand and impact these species 

throughout the system like they will affect native fish. See 

references above on page 3-106. 

3-112 NPS

R 

Billerbec

k

Again where you state "Alternatives with higher daily 

fluctuations (in particular the Non-Bypass Alternative) would 

have the potential to lower insect production, potentially 

resulting in relatively greater impacts on the northern leopard 

frog." you should add a sentence or two about how alternatives 

that allow warm water non-natives to increase (no action and 

non-bypass) that there would be increased predation on 

northern leopard frogs by SMB and GSF... see above 

references from page 3-106.

3-112 NPS B Holton

include lowland leopard frogs as a special status species and 

include with the comment above indicating likely increased 

predation and lowering survivability with the spread of SMB 

and GSF. 
3-113 NPS

R 

Billerbec

k

Here you conclude that HFEs could displace amphbicans and 

other species, however you don't mention that the non-bypass 

flucutations may do the same thing. But HFEs would occur 

typically once a year and, with the action changes to the HFE 

protocol, 80% of those will be in spring when natural peak 

flows would have occured, but the non-bypass fluctations may 

occur up to 26 times a year throughout the summer so they are 

much more likely to have an impact. Also a much larger and 

important impact is that SMB and GSF may prey upon 

amphibians and have greatly reduced amphibicans where they 

occur. So alternatives which allow SMB and GSF to expand 

(no action and non-bypass) would have negative impacts to 

these amphibian popuations (see refs above for p 3-106). 

3-113 NPS

R 

Billerbec

k

Under special status species, potential impacts to northern 

leopard frogs from alternatives that allow SMB and GSF to 

expand should be mentioned.

3-124-

125 NPA E Omana

Rogers et al. 2023 Razorback Sucker Xyrauchen texanus 

Research and Monitoring in the Colorado River Inflow Area of 

Lake Mead and the Lower Grand Canyon, Arizona and 

Nevada describes a RBS detection at RM 15

3-133 

& 3-

134 NPS

R 

Billerbec

k

MOST IMPORTANT COMMENT The effects of non bypass 

alternative on HBC does not currently address at all its failure 

to control SMB and other warm water non-natives - that is the 

most important effect of this alternative as has comparable 

performance for SMB lambda in the modeling results to no 

action. Therefore you need to have the same impacts listed 

here for the expansion of SMB, GSF and other warm water nonnatives on HBC and RBS throughout the system. This is a 

very important edit- maybe the most important one in this 

whole analysis. Please include the resutls of the SMB lambda 

analysis in this section and fully discuss the immpacts with the 

same text that is in the no action section. It should read, 

"Based on the SMB lambda modeling results, under the NonBypass Alternative, the humpback chub and razorback sucker 

may be subjected to increasing levels of predation and 

competition from nonnative fish, especially smallmouth bass 

and possibly green sunfish and other invasive, aquatic 

species. Although population levels of humpback chub are 

likely the highest since construction of Glen Canyon Dam, 

invasions of nonnative species, especially smallmouth bass, 

could lead to the decline of some population centers of native 

fish species, such as near the mouth of the Little Colorado 

River. Smallmouth bass populations could theoretically expand 

throughout the Colorado River ecosystem below Glen Canyon 
3-135 NPS

R 

Billerbec

k

Again this statement needs to be reconciled. We do think one 

of the five action alterantives will have a population level 

impact on HBC and other native fish - that is the Non-Bypass 

alternative. Based the modeling it will not stop SMB and other 

warm water invasives from growing and expanding and directly 

affecting HBC by preying upon them. So please reconcile 

these statements to reflect that if the atlernative doesn't control 

SMB, then it IS likely to have a population level impact on 

native fish. This is your statement "Generally, the five 

alternatives are not expected to have a negative populationwide effect on native fish, as these species have adapted to a 

large range of flows and temperatures in the Colorado River. 

However, all alternatives do assume that smallmouth bass 

populations will have impacts on native fish populations. These 

alternatives are not expected to have long-term, negative 

effects on the rainbow trout in the Lees Ferry reach ." We 

would suggest rewording it as: "Generally, the four bypass 

alternatives are not expected to have a negative populationwide effect on native fish, as these species have adapted to a 

large range of flows and temperatures in the Colorado River. 

However, all alternatives do assume that smallmouth bass 

populations will have impacts on native fish populations. 

Based that, and the modeling of lambda values for SMB 

populations, the Non-Bypass Alternative may be expected to 

3-148 NPS S Haas

The potential changes in vegetation and sandbar size could be 

substantial depending on the frequency of higher flows and the 

flow stage changes, within and between years - there is a big 

dfference between effects if spike flows occur once versus 

monthly in how sandbars and vegetation would respond to the 

changing water levels. The sand mass could be depleted 

quickly following spike flows, and the non-bypass proposed 

flows especially have the potential to erode beaches quickly, 

which will affect sandbar size and thus vegetation along the 

beaches. If you use a qualitative assessment, you need to 

define what metrics are being used (top of page). 

3-150 NPS S Haas

Under Cumulative Effects it states that all flow options would 

remain within the existing flows outlined in the LTEMP FEIS. 

Page 2-18: Under the Non-Bypass Alternative, flows could 

drop as low as 2,000 cfs and rise as high as approximately 

27,300 cfs. The minimum flows proposed under this alternative 

fall below those developed in the LTEMP ROD (5,000 cfs at 

night and 8,000 cfs during the day). This alternative would 

exceed the maximum daily range of 8,000 cfs analyzed in the 

LTEMP ROD. Modeled ramp rates were slightly outside the 

LTEMP requirements. Actual ramp rates would be within the 

operating range of the LTEMP ROD

3-156 NPS

R 

Billerbec

k

On this page for background please include information this 

year's GCMRC ARM in January about how deam release 

reached critically low dissolved oxygen levels in 2023 with the 

elevated river temperatures - this is critical information to 

include here. Bridget Deemer presented on this and you and 

can and should include that info as background.
figure 3-

35 3-157 NPS

R 

Billerbec

k

This figure isn't very readable and again it would be most 

effective to provide the data for how the alterantives perform 

different for the years in which temperature was over 15.5C. 

That is the way to tease out what the tools actually do - 

otherwise the action is lost in the noise of what is 83% 

performance of no action. We want to know what a tool does 

when its needed and its used, not what what it does when its 

not needed and not used. Having an average value of DO for 

the most biologically critical months for only those months 

where temp was over 15.5C and tools were triggered would 

also be useful in addition to the graph because those values 

can then be quoted in the impact summary at the top of the 

document - please do that as was done for hydropower so we 

can compare all resources equally - compare apples to apples. 

The ame applies to Figure 3-36 and Figure 3-37.

Figure 3-

37 3-161 NPS

R 

Billerbec

k

It appears this table is avearging results across all 30 runs and 

in its current form it is very difficult to understand and tease out 

differences between alternatives. This is not a fair comparison 

to hydropower results that are broken out for the months in 

which the tools in the alternatives are actually used (when 

temp was over 15.5C) in table 3-25. We believe that is only in 

17% of the runs and if you are averaging across all the runs 

then the results we are seeing are mostly averaged with the 

83% of the runs that didn't have DO problems. There 

hydropwer effects are assessed only the the months in which 

temperature was over 15.5C and the bypass tools or nonbypass tool where used. If you assess DO the same way, 

you will show a markedly different set of results that will show 

DO going a lot lower for some alternatives than others. The 

alternatives with bypass will perform decidedly better in the 

years in which those tools are actually needed and actually 

used. This graph doesn't work as currnetly presented to help 

distinguish fairly between altearntives.

Figure 3-

38 3-162 NPS

R 

Billerbec

k

Again - same comment - we don't expect diffeernces between 

alternaties when the different tools that are triggered - when 

temp > 15.5C. When temp is < 15.5C then the alterantives 

don't differ - they all behave like no action. So you need to 

tease that out to for a fair comparison to hydropower results 

that are broken out for the months in which the tools in the 

alternatives are actually used in table 3-25. We believe that is 

only in 17% of the runs and if you are averaging across all the 

runs then the results we are seeing are mostly averaged with 

the 83% of the runs that didn't have DO problems. There 

hydropwer effects are assessed only the the months in which 

temperature was over 15.5C and the bypass tools or nonbypass tool where used. If you assess DO the same way, 

you will show a markedly different set of results that will show 

DO going a lot lower for some alternatives than others. The 

alternatives with bypass will perform decidedly better in the 

years in which those tools are actually needed and actually 

used. This graph doesn't work as currnetly presented to help 

distinguish fairly between altearntives.
3-163 NPs

R 

Billerbec

k

You state "Across all alternatives, 74 percent of the years by 

trace combinations would be likely to have mean DO 

concentrations less than 5 mg/L in the late summer and early 

fall" but this is not the most important result to compare 

between alternatives. all the alterantive behave the same in 

months where temp < 15.5C, they only behave differently in 

months were temp > 15.5C so those are the months you need 

to break out there and provide the average DO levels for each 

alternative under those situations - that is how to compare 

between the how the alternatives peform for this metric.

3-170 NPS

R 

Billerbec

k

This background section on cultural resources fails to explain 

how dam operations affect sediment deposition and how 

aeolian transport of the sediment is what keeps cultural sites 

covered so they are protected from both physical erosion and 

visitor disturance. Please add these paragraphs from pp. 3-

147 and 3-148 from the original LTEMP EIS to explain this 

important dyanmic: There are a number of ways in which dam 

operations may affect cultural resources,

including the periodicity of inundation and exposure, changing 

vegetation cover, streambank

erosion, slumping, and influencing the availability of sediment. 

Direct and repeated

inundation/exposure may affect resources such as the 

Spencer Steamboat, which is in the active

channel (Figure 3.8-1), or Pumpkin Springs, a TCP along the 

bank that is subject to inundation

during high flows (e.g., equalization flows and HFEs). 

Streambank erosion, slumping, flowrelated

deposition, and indirect effects of deposition may affect 

cultural resources contained

within terrace contexts in proximity to inundated areas. Fine 

sand or sediment can be blown from

flow-deposited source areas and deposited on cultural sites 

(East et al. 2016) (Figure 3.8-2). The

3-170 NPS

R 

Billerbec

k

Please also include the updated information from the January 

2024 GCMRC ARM from Joel Sankey and Helen Fairley that 

documents how many cultural sites have moved out of the 

'type 1" site condition where aeolian transport is occuring 

freely. This transition has happened largely due to the period 

of no HFEs in the last 5 years. This is an important 

background condition that makes it imperative to have HFEs 

with the frequency orignally planned under the LTEMP EIS - 

so please get their latest info and if needed contact them for 

the interpretation to get a short paragraph about that current 

state.
3-172 NPS

R 

Billerbec

k

You state on page 2 10 that If drought and aridification 

conditions continue, the No Action Alternative could also result 

in the continued trend of fewer and smaller HFE releases" that 

seems correct and should be restated here. Currently this 

section indicates that HFEs will happen just fine under no 

action, but that ignores the fact that HFEs didn't occur between 

2018-2023 even though they were triggered. It would much 

more accurate and fair to say on p 2-10, that in fact under no 

action with a lower Lake Powell elevation and that we would 

expect to have fewer HFEs than LTEMP intendend. This is 

important because the strategy for depositing and retaining 

sediment on beaches and sandbars in the LTEMP was based 

on FREQUENT HFEs. The changes to the HFE protocol to 

expand the window to 1 year will help address this issue an 

maitain a frequency of HFEs to protect the resources that is 

closer to what was originally planned in the LTEMP EIS. See 

page 3-53 and 3-54 in the original LTEMP EIS that explains 

why HFEs need to be conducted frequently. You can include 

a statemetn from the LTEMP EIS p 3-181 that explains why 

you need frequent HFES - it states "... the net effect of high 

flows in building eddy sandbars results from the magnitude 

and the frequency of high flows and the deposition they cause. 

Erosion ensues rapidly after each high flow, and the rate of 

erosion declines thereafter but persists. The longer the time 

3-172 NPS

R 

Billerbec

k

For the Non-Bypass Atlernative on this page, you have some 

impacts, but you miss one of the bigger and important ones of 

this alternative. When the # of HFEs are split out by the years 

that the Non-Bypass tool is actually used, we are pretty sure 

you will see fewer HFEs and shorter HFEs because of the 

erosion of sand mass balance in those year - please look at 

those results and then update this section for the Non-bypass 

to state that fewer HFEs will impact cultural sites by leading to 

less deposition and less aeolian transport and therefore more 

exposure of archeological sites. Ths is a very important 

dyanamic that has been studies by GCMRC for many years 

and its one of the important Grand Canyon Protection Act 

responsibilities that must be addressed. Thank you.

3-173, 

3-174 NPS

R 

Billerbec

k

on this page and on the 3-174 under the summary you state 

"Non-Bypass Alternative - Impacts under the Non-Bypass 

Alternative would be the same as those impacts described for 

the Cool Mix Alternative, including sand bar developmen t" but 

we do not think this is correct. When the # of HFEs are split 

out by the years that the Non-Bypass tool is actually used, we 

are pretty sure you will see fewer HFEs and shorter HFEs 

because of the erosion of sand mass balance in those year - 

please look at those results and then update this section. 

3-

178,3-

179 NPS

R 

Billerbec

k

Where you discuss taking of life, it should be noted that for No 

action and non-bypass that if they do not prevent SMB and 

other warmer water non-natives from growing and expanding 

that other methods, likely more mechanical and chemical 

treatements, may need to be used by other agencies to try to 

control these species.

3-

179,3-

180 NPS

R 

Billerbec

k

As stated above, when sand mass balance and HFEs are 

broken out for the times that Non-Bypass is used, we think we 

you will see that 
3-182 NPS

R 

Billerbec

k

In the paragraph where you state "Recent drought conditions 

and aridification have resulted in warming water temperatures 

below Glen Canyon Dam, which could impact rainbow trout 

energetics and survival (Rogers 2015; Korman et al. 2022)." 

you should do 2 things - 1) copy this statement to the other 

parts of the plan where you talk about rainbow trout, 2) add 

information about the low dissolved oxygen conditions in 2023 

that are also adding a major new stressor to the rainbow trout 

population, and recent information from D. Ragowski and Scott 

Rodger that the health of the rainbow trout this spring is not 

good. For information on the low DO conditions in in 2023 

look at the presentations from Bridget Deemer and Josh 

Korman presented at the January 2024 GCMRC ARM.

3-182 NPS

R 

Billerbec

k

The wording in this paragraph needs to be changed - it current 

reads as if we are encouraging a brown trout recreational 

fishery - the incentivized harvest program is a removal 

program not a recreational fishery program. You state "The 

NPS currently utilizes an incentivized harvest program to 

encourage anglers to catch and keep brown trout in the Lees 

Ferry reach. The program has increased the popularity of 

brown trout fishing since 2016; however, the brown trout 

fishery in this reach is still not highly sought-after. Fishing in 

the remainder of this analysis refers to the rainbow trout 

fishery ." please reword to state this "The NPS currently 

utilizes an incentivized harvest program to encourage anglers 

to remove brown trout in the Lees Ferry reach. The program 

has more participation each year; however, the the number of 

participants is still low, thought the numbers of fish removed by 

this small number of anglers has increased greatly and is 

showing reductions to the population. Fishing in the remainder 

of this analysis refers to the rainbow trout fishery." You can 

find a citation for these statements at the January 2024 

GCMRC ARM presentations.

3-182 NPS

R 

Billerbec

k

Where you state "Most anglers elect no tto fish in the Glen 

Canyon reach during HFE releases." you should also add 

information from 2016 LTEMP to discuss how the larger 

fluctuations on the non-bypass alternative that may occur up to 

26 times a summer resembler the preMLFF flows that existed 

before 1995 and then in sert this pargraph from the 2016 

LTEMP EIS p 3-174 that states "High water levels, as well as 

rapid changes in water levels,

directly affect the safety of wading fishermen due to the 

potential for being swept away by the

river current. The 1995 Glen Canyon Dam EIS (Reclamation 

1995) included a reference to three

drownings that were possibly related to river stage or stage 

change and noted that high flows

(30,000 cfs or more) reduced the safety of wading in the river. 

After the adoption of the MLFF

operating protocol in 1996, ramping rates were restricted, 

which has likely reduced the level of

this risk, as has the reduction of normal high flows to 25,000 

cfs."
3-182 NPS

R 

Billerbec

k

The section for day rafting, boating and camping that starts on 

3-182 you need to add a section about the impacts of larger 

flucutaitons such as those in the non-bypass alternative, 

paritcularly the impacts of flows lower than 5,000 cfs. NPS 

had to warn boaters in sept of 2023 when flows were suddenly 

reduced to 5,000 cfs and NPS recieved many reports of 

motorized boating incidents, primarly broken props. Also NPS 

had to suspend some administration rapid response 

electrofishing efforts becaue it was felt 5,000 cfs created 

unsafe navigability situations in Lees Ferry for motorized craft 

trying to operated at night. Please include in this section 

somewhere text from the 2016 LTEMP about how flucutations 

and lower flows impact recreation boating. Here is the 2016 

text from p. 3-183: "The Bishop study (Bishop et al. 1987) 

further evaluated whitewater boater’s preferences

with respect to levels of daily flow fluctuations. The study, 

which was conducted at a time when

very large fluctuations were common, identified fluctuations in 

excess of 10,000 cfs as being

noticeable and perceived as less natural to canyon visitors. 

High fluctuations, ranging from

3,000 to 25,000 cfs/day, were also noted as contributing to 

issues related to selection of

campsites, time allowed at attractions, mooring and tending of 

3-186 NPS

R 

Billerbec

k

This section on boating and camping in Grand Canyon should 

again include information in the 2016 LTEMP that is very 

relevant about how larger flucutations like those in non-bypass 

option impact camping and how sediment is crucial to maintain 

recreational campsites that should be included or at least 

referenced. Please include "High fluctuations, ranging from

3,000 to 25,000 cfs/day, were also noted as contributing to 

issues related to selection of

campsites, time allowed at attractions, mooring and tending of 

boats, transiting major rapids, and

trip scheduling." from LTEMP p. 183 and these sentences from 

pages 3-179, 3-180 and 3-181 of the LTEMP "The number of 

available campsites and the amount of campsite area

at any particular time are affected by river flow (i.e., fewer 

campsites are available at higher flows, and vice versa). 

Because of their singular importance in supporting river use, 

there have been numerous campsite inventories over the 

years; NPS reported in the CRMP that there are

more than 200 regularly used camping beaches in the GCNP 

planning area. The number and

usability of campsites vary from year to year based on several 

factors, including flow regimes;

vegetation changes; erosion from tributary flooding, wind, or 

recreation use; or closure of sites to

3-190 NPS

R 

Billerbec

k

Where you state, "Reducing the overall rainbow trout 

population could negatively affect the rainbow trout fishery; 

however, these effects are not likely to be significant overall 

due to the short-term nature of flow implementation." We 

disagree. As stated above in many places, this assumption is 

based on the Korman 2011 study that assumes a 

compensatory response from rainbow trout, but the population 

size being so low now and the additional stressors from high 

temrperature, low DO, additional predation and other recent 

poor health indicators suggest it cannot be assumed there 

would be a compensatory response. Also these non-bypass 

large flucutations could occur up to 26 times a summer.
3-191 NPS

R 

Billerbec

k

For impacts to recreation from the non-bypass alterantive in 

Glen Canyon, please include a statements that this alternative 

may have flows every weekend from May-Oct so up to 26 

times a summer if conditions call for it. This would require 

concessions to shut down for those days, which is a much 

great impact than HFEs once a year or flow spikes 2-3 times a 

year. This should be clearly stated in this section as the impact 

could be 20x greater in terms of financial impacts to these 

small businesses.

3-192 NPS S Haas

The non-bypass flow would create flows below 5000cfs that 

would not allow for motor boats during the current motor 

season and would be of such high and low extremes to 

significantly disrupt river users and cause erosion to beaches. 

It appears that flows lower than 5000cfs persist down past the 

LCR and as the flows propigate downstream they will change 

from happening at night into daytime. Analysis of beach 

erosion from extreme high and low flows was not sufficiently 

analyzed in the document. Again sediment metrics need to 

evaluated for the years or months in which the non-bypass 

alterantive is occuring to tease out the actual impacts to 

sediment (erosion and loss of sandmass balance leading to 

less and shorter HFEs) from the large number of these 

flucutations (potentiall up to 26) that may occur in a summer. 

Camping opportunities could be drastically affected due to 

beach erosion and access issues/boat stranding due to the low 

volume. for beach erosoin - again please look at HFE, sand 

mass balance and other sediment stats after they are broken 

out for the years or months this non-bypass tool is used and 

we are pretty sure it will show that this tool is having a marked 

impact on beaches. 

3.12 3-166 NPS Brennan

3.12.1 Affected Environment, first sentence should read "The 

history and importance of Glen Canyon, Marble Canyon, and 

Grand Canyon..."

3.12 NPS Brennan

We do not agree with the assessment for the Non Bypass 

Alternative that “available sediment would be similar to that 

under the No Action Alternative.” Previous studies (Leopold 

and Maddock 1953, Brooks 1958, Howard and Dolan 1981, 

Burkham 1986, and Topping et al. 2000) have shown that riverdeposited sediment supply has been reduced by flow regimes 

that result in continual sediment scour from the river bed thus 

limiting opportunities for sediment deposition on 

archaeological sites via aeolian processes. Flows of 27,300cfs 

occurring at weekly intervals would continue, and we believe 

increase, sediment scour through eastern Grand Canyon and 

particularly in Marble Canyon. *Continuing loss of sediment 

would likely lead to a reduction in HFEs which Sankey et al. 

(2023) have identified as an important “contemporary 

mechanism” (Sankey 2023, presentation for the Glen Canyon 

Dam Adaptive Management Program) for increasing sand 

supply within the river corridor. Sankey et al. (2018) state that 

“Windblown river sand deposited in dunefield archaeological 

sites increase cumulatively when upwind river sandbars are 

resupplied by consecutive annual HFEs.” Loss of sand mass 

through Marble Canyon could limit our ability to supply 

necessary sand to protect archaeological sites.*There is a 

likelihood that the weekly 27,300cfs peak flow could erode, 

and potentially eliminate existing sand bars that serve as 

3.12 NPS Brennan

Other information: East, A.E., Collins, B.D., Sankey, J.B., 

Corbett, S.C., Fairley, H.C., and Caster, J., 2016, ** East, A.E., 

Sankey, J.B., Fairley, H.C., Caster, J.J., and Kasprak, A., 

2017** Kasprak, A., Sankey, J.B. and Butterfield, B.J., 2021. ** 

Mueller, E.R. and Grams, P.E., 2021. **Sankey, J.B., Caster, 

J., Kasprak, A. and East, A.E., 2018. **Sankey, J.B., Caster, J., 

Kasprak, A. and Fairley, H.C., 2022. 
3.12.

1 3-166 NPS Brennan

Two confirmed Paleoindian points, a fragmentary Clovis point, 

and a partial Folsom point have been identified at the Grand 

Canyon.

3.12.

1 3-166 NPS Brennan

Grand Canyon has perhaps the most well know Late Archaic 

material culture within the study area, including the so called 

Split Twig Figurine Complex and Grand Canyon Polychrome 

pictographs. The STFC appears limited to eastern Grand 

Canyon, while the Grand Canyon Polychrome sites are 

focused in western Grand Canyon.

3.12.

1 3-166 NPS Brennan

There is evidence of Early Formative occupation of Grand 

Canyon NP

3.12.

1 1 3-166 NPS Brennan

I don't think I'd use the word 'emerged" to describe the 

presence pf Ancestral Puebloan people.

3.12.

1 1&2 3-166 NPS Brennan

It would be good to acknowledge that Ancestral Puebloan 

people retained their ties to the Canyon and returned for many 

reasons (resources, trade, ceremony, etc).

3.12.

1 3-167 NPS Brennan I am wondering why all your cultural references are for GLCA?

3.12.

1 3-167 NPS Brennan

The Havasupai, Hualapi, Navajo, and Southern Paiute all were 

present in and near the Grand Canyon. Tha Havasupai still 

live within it.

3.12.

1 3-167 NPS Brennan

Grand Canyon also has a significant early EuroAmerican 

History. Why isn't it included? 

3.12.

1 3-167 NPS Brennan

The Grand Canyon has 16 cultural Landscapes, including the 

Canyon itself and the Cross Canyon Corridor (major trails 

between the North and South Rims in the inner canyon)

3.12.

1 3-167 NPS Brennan

Grand Canyon has documented over 500 ethnographic 

resources within the park, including the river and specific 

locations within it. We will never know all such resources due 

to their sensitivity from a tribal perspecitive.