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Glen Canyon Dam Technical Work Group 

Proposed Science Topics to be considered at the 

GCDAMP Annual Reporting Meeting January 28-29, 2014 

for GCMRC review 

December 16, 2013 

Project A. Sandbars and Sediment Storage Dynamics 

1. Report on progress being made to determine if the new HFE protocol will: 

a. result in net increases in sandbar area and volume; 

b. whether this approach of using repeated floods to build sandbars is sustainable 

with the available sand supply (i.e. tributary inputs); and, 

c. whether multiple high flows conducted over a period of 10 years will result in net 

increases in campable area along the Colorado River? 

d. Will we be able to answer these questions in the timeframe outlined in the HFE 

protocol? (WAPA)

2. Provide some additional information on recent HFEs and sediment: 

a. What are the results of the 2013 HFE? (GCRG)

b. How did the 2013 HFE compare to prior HFEs? (Nevada)

c. What do the recent HFEs tell us about the long-term predictions for sediment in 

the Grand Canyon? (GCRG)

d. The 2013 HFE left behind a lot of sediment. How will that be taken into account 

when a 2014 HFE is considered? (GCRG) This is different from past HFEs, 

leaving so much sediment behind in the channel, what might we expect as a result 

of this? Perhaps less erosion of sand bars (due to higher sediment loads in the 

mainstem or broader footings for the sandbars?) (WAPA)

3. What progress has been made on the work that Gram's has done looking at sand bar 

changes post-HFE? This was presented at a TWG meeting, but has been a work in 

progress. Are there any updates? (WAPA)

4. Were there any benefits to the shaping of 2012 HFE hydrograph (reduced time on peak 

and slower downramp)? Is there any need to further experiment with hydrograph shape in 

order to modify the structure of sand bars built during HFEs to make them more durable? 

(WAPA)

5. Provide a short presentation on how sediment samples are processed. Explain why it 

takes so long to process a season’s worth of sediment samples. Where is the choke point 

for getting samples processed in a timely manner? Is there a way to make the process 

more efficient? (WAPA)
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6. What is being done to develop, analyze, and implement an appropriate flow alternative to 

prevent sediment mass balance loss during flow equalization periods? (GCWC)

7. Clarify sediment flux in the Glen Canyon Reach and develop management 

recommendations to mitigate erosion. (GCWC)

8. Provide a report on the progress in expanding the sediment monitoring below Diamond 

Creek as requested by the Hualapai Tribe. (CRAHG)

Project B. Streamflow, Water Quality, and Sediment Transport in the Colorado River 

Ecosystem 

Project C. Water-Quality Monitoring of Lake Powell and Glen Canyon Dam Releases 

1. What are the differences in water quality of Glen Canyon Dam releases made during 

lower reservoir elevations? Are there any impacts we should expect or be looking for in 

the future based on the potential for continued low reservoir conditions (e.g., nutrients, 

low dissolved oxygen)? (WAPA)

Project D. Mainstem Humpback Chub Aggregation Studies and Metapopulation Dynamics 

1. Provide an update on the aggregation sampling (Project D.1). Are we doing enough to 

understand the relationship between translocations and aggregation populations? Is the 

sampling program safe for the smaller aggregations (are there research impacts)? Are we 

picking up and tracking any movement between aggregations? If the number of fish in 

the aggregations starts to increase, will humpback chub end up returning to the Little 

Colorado River? Is there any evidence of long range movement that would tell us about 

the population structure of chub throughout the canyon when compared to the Little 

Colorado River? (WAPA)

2. Provide an update on determining natal origins of humpback chub at aggregations using 

otolith microchemistry (Project D.2.2). Have any otoliths been run yet? If so, is there any 

indication of mainstem spawning or spawning anywhere but the Little Colorado River? 

Has the antenna array in the Little Colorado River been useful in tracking these 

movement patterns? Will there be any publication of data soon? (WAPA)

Project E. Humpback Chub Early Life History in and Around the Little Colorado River 

1. What are the implications of outmigration of juvenile humpback chub from Little 

Colorado River, especially related to monsoon events (Project E.1)? Does outmigration 

have an impact on recruitment to the adult population or are the long-term dynamics of 

the chub population buffered against these potential mortality events? Are juvenile chub 

survival rates (from JCM) highly affected by monsoon events? If so, what does this mean 

to our ability to make determinations about the impacts of temperature and trout to 

juvenile chub survival? (WAPA)
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2. What are the drivers of good year-classes of humpback chub in the Little Colorado River 

(Project E.3)? Can we predict good year classes based on environmental conditions (e.g., 

Little Colorado River flow, temperature, food availability)? (WAPA)

3. Do HFEs transport juvenile humpback chub downstream and if so, what becomes of 

these fish? Do they survive at some downstream location? Are they moved to 

unfavorable or favorable habitats? Do they find food, or are they eaten by predators? 

Could they contribute to the aggregations? Do they return to the Little Colorado River 

population? A study of the fate of these fish is needed to fully assess the impacts of 

HFEs. (UAMPS/CREDA)

Project F. Monitoring of Native and Nonnative Fishes in the Mainstem Colorado River and 

the lower Little Colorado River 

1. Provide an update on nonnative species observations (rainbow trout, brown trout, striped 

bass, and smallmouth bass) in the mainstem surveys (Projects F.1 and F.2). What 

nonnative species are of paramount concern for the long-term persistence of native fish in 

Grand Canyon and what should we be considering to ensure that the species that are 

established are managed effectively and those that are rare don’t become established?

(WAPA)

2. Provide an update on the rainbow trout monitoring in Glen Canyon (Project F.2). 

i. Provide an update on the large cohort from the 2011 equalization flows. Is 

there an indication that this large cohort adversely affected the fishery by 

competing with larger trout? Is there a decrease in adult trout condition with 

an increase in small trout abundance? 

ii. What was the affect of the Fall 2012 HFE on the Lees Ferry trout fishery and 

why? Did the Fall 2012 HFE affect the survival of the 2013 cohort, condition 

of larger trout, or dispersal (Project H.5), or the foodbase (Project F.7)? Do 

Fall HFE’s have a similar affect on the trout fishery and the foodbase as 

Spring HFEs? What would sequential Fall and Spring HFEs do to the trout 

fishery and foodbase? (IFF)

3. How can we synthesize information being collected by the Juvenile Chub Monitoring 

(JCM) project so we can determine how juvenile chub survival (Project F.3) relates to 

trout abundance (rainbow vs brown; Project F.3), how trout and native fish interact under 

different environmental conditions like river temperature and turbidity (Project G.1), and 

foodbase availability (Project F.7)? What are the driving mechanisms for mainstem 

humpback chub numbers and their recruitment to the adult population at the Little 

Colorado River? (WAPA)

4. Provide an update on the development of a more robust ASMR model or the development 

of an LSMR model (Project F.4)? This is a high priority for the program; please bring us 

up to date on the latest developments of this population modeling. (WAPA)

5. Can we yet describe the utility of the translocation program (Project F.4.3)? How have 

these efforts improved the situation for humpback chub in Grand Canyon? Are these 

efforts increasing recruitment or bolstering numbers in the aggregations? Especially with 
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respect to the Little Colorado River/Chute Falls translocations, what is the definition of 

success with regard to these efforts? (WAPA)

6. Provide an update on results of the Natal Origins of trout study (Project F.6). What were 

the findings from this year? What movement was observed? Has our opinion of how the 

system works changed? Was there substantial production of trout in Marble Canyon the 

last few years (evidence of age 1's in Marble Canyon but little downstream movement 

detected)? For the next few years, based on what we have learned about movement, are 

there any changes that need to be made to the Natal Origins study? Will the large Fall 

2013 sediment input into Marble Canyon have an impact on the large population of trout 

currently in Marble Canyon? Will we be able to detect increased movement downstream 

to the Little Colorado River reach because of a reduction in habitat quality for trout in 

Marble Canyon? (WAPA)

7. Provide an update on what is happening with trout/chub numbers and the triggering 

criteria for the 2011 Biological Opinion. (CRAHG) Should the criteria be updated with 

new numbers, such as the brown trout numbers? Are these reasonable practical numbers 

that relate to effects on humpback chub in the mainstem? Describe the relationship of the 

trout numbers in the Biological Opinion to what the trout population would be in the 

entire Little Colorado River reach (density, total population) and how that relates to 

previous Little Colorado River reach population numbers (e.g. removal numbers and 

population estimates from previous removal efforts in Coggins et al. 2011). (WAPA) 

8. Provide a clarification of the latest GCMRC foodbase fact sheet (Kennedy et al. 2013):

a. Kennedy et al. makes the following statement in their fact sheet on page 4: 

If increased native fish production is desired in Marble and Grand Canyons, 

other management actions could be considered. For example, hydroelectric 

power generation from Glen Canyon Dam causes large daily changes to the 

Colorado River’s discharge and lowers algae production relative to more stable 

discharges (Robert Hall, Jr., and others, unpub. data, 2013). Thus, stabilizing the 

discharge regime could lead to increased algae production at downstream sites, 

which may in turn have positive effects on invertebrate and fish production.

b. But previously, it is stated that algal production decreases from Glen to Marble 

Canyon and is even lower in Grand Canyon (Hall and others, 2010), because the 

higher suspended sediment load reduces light penetration. The foodbase at RM61 

and below (where all the humpback chub and other native fish are located) is 

primarily detritus based, not algae based. 

c. So wouldn’t taking steps to increase algae production with more stable discharges 

from Glen Canyon Dam have a positive effect only on invertebrates and fish 

production in Glen and upper Marble Canyons? Aren’t these areas dominated by 

rainbow trout and not by native fish? 

d. If so, wouldn’t a more stable flow regime actually end up having a negative effect 

on humpback chub and other native fish in Marble and Grand Canyons due to 

increased competition and predation by rainbow trout? 

e. Are there other strategies that might be discussed, such as nutrient augmentation 

in critical reaches of the river, which might increase food base productivity even 
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in the more turbid portions of Marble and Grand Canyons where native fish are 

predominately found? (WAPA)

Project G. Interactions between Native Fish and Nonnative Trout 

1. Provide update on evaluating the effects of trout predation and competition on humpback 

chub (Project G.1). What is the primary driving force for juvenile chub mortality 

(temperature, predation by rainbow and/or brown trout, cannibalism, etc.)? Does turbidity 

reduce the predation pressure on juvenile humpback chub? (WAPA)

2. Provide an update from the Fall 2013 brown trout mainstem removal trip. How do 

removals of trout in Bright Angel Creek by the National Park Service relate to mainstem 

removals of brown trout by GCMRC (Project G.2)? How do these removal efforts affect 

humpback chub and observations of brown trout in the Little Colorado River reach? Are 

we near the 2011 Biological Opinion trigger for brown trout removal in the Little 

Colorado River reach? What do we expect to see with the mainstem brown trout 

removals at Bright Angel Creek over next few years? (WAPA)

3. How much more do we need to know about the chub and trout to know enough to be sure 

the chub will remain viable and the trout will do well but not be out of control? What 

studies still need to be done to get to these answers? (GCRG)

Project H. Understanding the Factors Limiting the Growth of Large Rainbow Trout in 

Glen and Marble Canyons 

1. Have we learned anything more about the trout strain at Lees Ferry (Project H.1)? Are 

these fish capable of growing BIG, or are they now genetically “stuck“ in a more 

moderate size class? (WAPA)

2. Provide an update on the tailwater synthesis project (Project H.4). What have been the 

major findings with regard to environmental conditions, invertebrates species found, and 

their abundances in tailwaters similar to Glen Canyon? What is working in those 

tailwaters that is not working in Glen Canyon? (IFF)

Project I. Riparian Vegetation Studies: Response Guilds as a Monitoring Approach, and 

Describing the Effects of Tamarisk Defoliation on the Riparian Community 

Downstream of Glen Canyon Dam 

1. How does monitoring tamarisk beetle defoliation and arthropod/pollinator abundance 

relate to GCDAMP goals and information needs? How does this relate to management 

actions at Glen Canyon Dam? Provide a review of riparian vegetation-related science 

questions and information needs identified by the GCDAMP. Identify those areas that 

Project I is helping the GCDAMP resolve those science questions and information needs.

(WAPA)

2. What is being done to develop a Colorado River ecosystem conceptual model that 

couples aquatic and riparian domain processes by integrating river continuum and 

riparian landform/habitat modeling? (GCWC)
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3. Clarify the potential impacts and management alternatives related to the system-wide loss 

of tamarisk. (GCWC)

4. What is being done to develop a model of riparian vegetation development in relation to 

dam operations? (GCWC)

Project J. Monitoring of Cultural Resources at a Small Scale and Defining the Large-Scale 

Geomorphic Context of those Processes 

1. Provide a review of cultural-related science questions and information needs identified by 

the GCDAMP. Identify those areas that Project J is helping the GCDAMP resolve those 

science questions and information needs. (WAPA)

2. What is being done to evaluate the impacts of operations at Glen Canyon Dam on cultural 

resources in Glen, Marble, and Grand Canyons in Projects J.1 and J.2? What are the areas 

of concern and how are tribal values being addressed in the management of cultural 

resources? (WAPA)

3. Have GCMRC report on their cultural resource monitoring program and progress they 

have made toward successful integration of Tribal values into that program. (CRAHG)

4. TEK and Tribal Input: almost every meeting this topic comes up. We sense there is some 

real frustration on the tribal side that they are not getting heard. Could we address this 

issue so it can be satisfactorily resolved for the tribes? (Nevada)

5. Develop a list of species of management concern to the participating Tribes, and use that 

discussion to clarify how to better incorporate traditional ecological knowledge into CRE 

science and management programs. (GCWC)

6. Have Grand Canyon National Park provide a presentation on their monitoring of 

archaeological sites (and other historic properties) that is part of their on-going Colorado 

River management plan. (CRAHG)

7. Have Grand Canyon National Park provide an update report on when the CRAHG may 

be provided an opportunity to review the data recovery report that details the excavations 

that the Museum of Northern Arizona and Grand Canyon National Park performed in 

2010. (CRAHG)

8. Have Glen Canyon National Park Service report on the progress made at the -9 Mile 

terrace site. (CRAHG)

9. Does Lidar work to monitor cultural sites? Should its use be expanded from Glen Canyon 

to other sites in Marble and Grand Canyons? (WAPA)

10. What is the future of the cultural resources program (both GCMRC’s cultural resources 

program and Reclamation’s compliance under the programmatic agreement) within the 

GCDAMP? Recent events might suggest that the cultural resources are losing importance 

in this program, which would be ironic given that the entire GCDAMP is a product of a 

cultural resource value. (CRAHG)

Project K. GCMRC Economist and Support 
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1. Socio-economics. We'd like to meet the new economist and hear about what's in the 

works on that front. (GCRG)

Project L. Independent Reviews and Science Advisors 

1. What is the current role of the science advisors at GCMRC? Are they doing program 

reviews as in the past or have we changed direction? What does GCMRC see as the 

utility of the Science Advisors, what reviews are planned for FY15-16? (WAPA)

2. We have been on a 5-year schedule for peer reviews of the various programs (e.g., PEPs). 

What are the plans for PEPs in FY15-16? (WAPA)

Other: 

1. Provide update on Kanab Ambersnail designation and publications. 

2. The material that is presented at the January knowledge assessment meetings is very 

informative. Let’s not wait to get the power points and presentation materials 

disseminated to our group two months later. Could we identify the documents as 

“Preliminary” and get them on the GCDAMP Wiki site the same day. Later, once they 

are finalized, then “officially” post them on GCMRC’s website. (Nevada)