Thanks to CREDA/UAMPS representatives for taking the time to carefully review our FY2015 Annual 

Report to the Bureau of Reclamation. Responses from GCMRC are provided after each question in bold.

Scott VanderKooi – January 27, 2016

GCMRC ANNUAL REPORT – FY 15

CREDA/UAMPS INITIAL QUESTIONS/COMMENTS – January 13, 2016

1) Project 2, page 9, how did the GCMRC sampling compare with the Utah & AZ Water Science 

Centers sampling? Were they compared for calibration? 

Response: All sampling done by all USGS science centers involved in this project are conducted 

using the same USGS methods.

2) Project 2: This project mentions water quality as an included parameter; however, this is a very 

limited data set including only physical measurements. Are there efforts to track chemical 

quality of water as it transits the canyon, e.g. nitrogen, phosphorus, etc.? If so, where do these 

values appear and what are the trends?

Response: Episodic chemical and nutrient samples are collected by the USGS (these are 

funded from other sources) but no efforts have been made to track how the chemistry of the 

water or nutrient loads change through the canyon. 

3) Project 2: How does any relationship between turbidity and suspended solids change during 

transit spatially and temporally? What are the implications to sight-feeding predators (trout) 

and algae of any change in the relationship between turbidity and suspended solids?

Response: For the sake of brevity here, we direct you to the 2014 publication by Voichick and 

Topping (available at: https://pubs.er.usgs.gov/publication/sir20145097) and the 2015 

publication by Hall and others (available at: 

http://onlinelibrary.wiley.com/doi/10.1002/lno.10031/abstract) for responses to these 

questions.

4) Project 3: Do the sandbar volume data provide any help in determining differences in volume 

due to down ramp rates? If not, what project does this?

Response: The annual sandbar monitoring does not isolate the effect of ramp rates. Higher 

rates of erosion have been observed to be associated with higher average releases (Hazel et 

al., 2010). However, we have completed experimental studies to specifically examine the 

effect of downramp rate on sandbar erosion (Alvarez and Schmeeckle, 2012). This study 

concluded that downramp rate, by itself, did not significantly affect erosion rates. Erosion 

amount and rate were controlled by the range of fluctuations and the number or frequency of 

fluctuations (i.e. more fluctuating cycles per day would be expected to cause more erosion). 

5) Project 3: What is the spatial trend of sandbar volume relative to HFEs, i.e. throughout the 

canyon? 
Response: Deposition has occurred at sandbars throughout Marble and Grand Canyons. Some 

differences among reaches and research into sandbar variability will be discussed at annual 

reporting meeting. 

6) Project 3: Is this project capable of distinguishing sandbar volume changes due to dam 

operations following an HFE from changes due to other factors, e.g., campers, upgradient flow, 

etc.?

Response: See answer to question 4, above.

7) Project 3: Are there plans to develop sandbar data for the rest of the river corridor 

commensurate with those collected in Marble Canyon?

Response: There are more sites in Marble Canyon, but there are monitoring sites throughout 

the river corridor. Data from throughout the river corridor will be discussed at annual 

reporting meeting.

8) Project 3, page 13, 1st full paragraph, “vegetation expansion is responsible for net long-term 

decline in open areas”. Same paragraph,” post-HFE erosion decreases in campsite areas” Is this 

due to ramping or is it due to weather erosion?

Response: Most erosion of sandbars results from erosion by the Colorado River. Erosion by 

local hillslope runoff is important at a few sites.

9) Project 3, page 13, 2nd full paragraph weather stations are available to determine erosionary 

effects of weather pre & post storms as a possible cause to erosion. Scour should have occurred 

similarly for increased sandbars proportionally unless the delta of flow is buffered due to checks 

in the river. To have 50% of the sand bars maintain their increase after 3 months makes me 

believe it may be something different than scour due to ramping. This could also be caused by 

flooding from side channels causing localized flow changes. It might be good to ask for a pattern 

of which sandbars maintain vs. erode in relation to location in the system.

Response: Downstream variability in sandbar response and causes for variability in sandbar 

behavior are being researched (see Grams and Mueller talks at annual reporting meeting).

10) Project 3, page 15, 2nd full paragraph, why is an unsupervised classification method being used?

Response: “unsupervised” means that the classification is done with an automated computer 

program. There is still ground truthing and inspection of how well it works. This is the most 

efficient way to classify imagery when possible. Because the images are high quality, the 

method works well for vegetation. 

11) Project 3, page 15, 3rd full paragraph, why is something being manually edited?

Response: Sand is more difficult to classify with strictly automated methods. Manual editing is 

done to ensure accuracy.
12) Project 3, page 18, 1st full paragraph, this is another example of stable beach increases for 6 

months of duration.

Response: Downstream variability in sandbar response and causes for variability in sandbar 

behavior are being researched (see Grams and Mueller talks at annual reporting meeting).

13) Project 3, page 19, 2nd full paragraph, how about comparing storage locations against each other 

over time? That would make it easier to facilitate discussion about management choices of 

WHICH beaches should be prioritized, to the extent possible. As river bed/bottom scours, mean 

surface elevation drops because flow equals area times velocity.

Response: We are investigating causes of spatial variability in sandbar response (Erich Mueller 

talk at annual reporting meeting). Scour of sand from the river bed does not typically result in 

a commensurate drop in water surface elevation in Grand Canyon. Water surface elevations 

are determined by the bed at channel controls, which in Grand Canyon are the rapids with 

very coarse bed material that does not frequently change. Thus, scour of sand from the bed 

would typically be compensated by decrease in mean velocity to maintain continuity. 

14) Project 3, page 20, A.4, “bedload contributes more to total load than previously thought”, 

meaning sediment on floor is causing a higher surface elevation, increasing erosion along the 

river’s edge. We have asked in various forums about the possibility of looking at non-flow 

related tools to improve camping beaches. Please consider the potential of using a suction 

dredge to blow sand up on beaches. Has this been considered in the past?

Response: Bedload will be discussed at meeting. See above response on relation between bed 

scour (or aggradation) on water surface elevations. I’m not aware of the history of discussion 

on dredging as a potential management action. Whether or not this would be a desirable 

action would have to be a subject for discussion among stakeholders.

15) Project 4, How does dam operations affect archeological sites that should have been built 

above the food stage 45K cfs. Aeolian transport would have provided protection to historical 

sites long before dam was installed.

Response: There are two key components of the aeolian transport equation: wind (prevailing 

direction and intensity) and sediment (supply). The former is not affected by dam operations 

but the latter is affected. Dam operations affect sediment supply in terms of where sand gets 

deposited, how much sand is deposited, the elevation of those deposits, and so forth. Dam 

operations also affect vegetation growth patterns, which in turn influence both the 

availability of sand for transport and whether it can be transported from one location to 

another (i.e., vegetation can form a barrier to aeolian transport of sediment). If a site was 

formerly protected by wind-blown sand but the source of that sand is diminished, either 

because sand bars are not being replenished or increased vegetation hinders movement of 

sand by wind, the site will progressively erode over time at rates faster than would be the 

case if the sediment supply to the site was maintained. 

What about investigating wind patterns from weather stations in the canyon to determine 

Aeolian transport effects?
Response: Monitoring weather parameters in relation to sediment supply and examining how 

these factors interact to affect archaeological site condition is an important component of 

Project 4. We currently have four weather stations deployed throughout the canyon 

specifically for this purpose.

16) Project 4, page 32, top of the page, I read this to say there really isn’t anything different pre & 

post dam on Aeolian transport, this conflicts with Section 5, second bullet point #3 in the section 

below (same page). 

Response: This conclusion is premature and probably incorrect. We know that not all riverderived sand (RDS) comes directly from channel margin deposits or from sand bars below the 

45k flow elevation; much river-derived sand was also derived from deposits of pre-dam floods 

at higher elevations. Therefore it is not surprising that not all mapped RDS units are 

necessarily larger or more active when located adjacent to channel segments with high ratios 

of MCS to MCV. We do believe, however, that vegetation plays an important role in 

determining whether sand is transported from the active channel to higher elevations (where 

most archaeological sites occur). In project 4, we are examining the relationships between 

sediment supply and vegetation as they affect the condition of archaeological sites from a 

variety of different angles. It is premature to draw any broad conclusion about these 

relationships at this early stage of the study.

17) Project 4, page 32, last paragraph, how can there be a realistic comparison of photographic 

comparisons given the duration between when the first and last 2 sets were taken as well as the 

fact that they are from one perspective.

Response: Use of repeat photography to document ecological change is a well-established 

method that has been in use by scientists for well over a hundred years (a succinct description 

of this method and its history can be found at the following link: 

http://pubs.usgs.gov/fs/2007/3046/fs2007-3046.pdf). We are comparing images taken of the 

river corridor prior to the existence of the dam with current conditions. There are literally 

hundreds of views captured in the collection of photographs we are using for this study; many 

of them show both upstream and downstream views from the same position and many of the 

views are overlapping. 

How much of this is due to vegetation infestation, or image distortion due to vegetation 

blocking views of the single perspective? 

Response: The degree to which new vegetation growth covers formerly open aeolian source 

deposits or has created barriers that now hinder aeolian transport of sediment is one of the 

key questions we are trying to answer in this study. In terms of the “single perspective” issue, 

many of the images overlap one another (many views are also taken looking both upstream 

and down from the same position) so if a view of an area is blocked in one image, it is often 

visible in another. However, not every square inch of the river corridor has been 

photographed, so it is not possible to evaluate sediment source supply conditions at every site 

of interest; however, we expect to obtain a good representative sample using this approach.

18) Project 5, page 39, bottom of the page, Cloudy days affect algae (food base). Unless this project 

is going to get into weather modification, how is this relevant?
Response: This kind of perspective (cloud cover > hydropeaking) is valuable and absolutely 

critical to informed discussions about adaptive management experimentation.

19) Project 5: Foodbase data demonstrated that prey availability and size limit the maximum size of 

rainbow trout in Glen Canyon and drift data show that prey availability is playing a role in trout 

growth rates among sites and seasons. What is being proposed that hasn’t already been 

studied?

Response: Prior studies have not explicitly evaluated how prey size affects maximum size of 

rainbow trout. Also, the model that was developed to evaluate effects of prey availability and 

size can be used to evaluate how trout size responds to different idealized prey scenarios. This 

is a useful tool for scientists and managers that did not previously exist.

20) Project 6.4: Fish community monitoring has attempted to track and record presence and 

abundance of native and nonnative fish; yet, we discovered a thriving population of green 

sunfish in the Lees Ferry reach. What factor or factors may have contributed to this apparent 

sudden influx of this nonnative warmwater fish? Are there efforts underway to determine if 

there is a relationship between use of HFEs which bypass generators and infuse large amounts 

of water and the sudden influx of the sunfish (and possibly other warmwater nonnatives) from 

Lake Powell? What is the seasonality of fish distributions in the Lake Powell forebay or the 

reservoir level changes that might be contributing to the introduction? 

Response: The green sunfish population found in Glen Canyon in 2015 was detected because 

of the nonnative fish monitoring program currently in place. This detection allowed for quick 

action to eliminate this invasive species from the -12 mile slough. Green sunfish are quick to 

mature and highly fecund thus a few individuals can invade new areas and produce a large 

numbers of offspring quickly if conditions are favorable as they were in Glen Canyon. This 

seems a more likely scenario, as opposed to large numbers of green sunfish being passed 

through the dam, given that almost all individuals were found in one relatively discrete 

location rather than throughout Glen Canyon. Other species like walleye and striped bass get 

passed through the dam in small numbers and are detected in our monitoring. As described 

above, we believe this event was due to a small number of individuals finding the right habitat 

and conditions to reproduce and have high survival rates of young rather than a sudden influx 

of nonnatives. It should be noted, however, that low reservoir levels may allow more fish to 

be entrained and passed through the dam. There is not currently an effort to correlate HFEs 

with the detection of nonnative fishes in Glen Canyon. A number of factors make the turbines 

the more likely route of bypass of nonnative fishes rather than the jet tubes. The intakes for 

the jet tubes are deeper in the reservoir making conditions less favorable for fish to be 

entrained. Additionally, the duration of HFEs is short (96 h) and the volume of water bypassed 

by the jet tubes is small relative to that moved through the turbines during these events and

throughout the remainder of the year. We are unaware of any monitoring of the seasonality 

of fish distributions in the Lake Powell forebay.

21) Project 8, page 62, section 8.1, did water temperatures result in lower harvest rates?

Response: We were not entirely sure if this was referencing the correct section. Section 8.1 is 

about efficacy and impacts of trout removal at Bright Angel Creek. We did have a lower catch 
of brown trout and rainbows at the Bright Angel Creek inflow during the Feb. 2015 sampling 

efforts, but it is difficult to link that to water temperatures. It is likely that the reduced catch 

rates were the result of turbid water conditions during the sampling period. It does appear, 

from the AZGFD catch-per-unit effort data, that trout populations in the area around Bright 

Angel Creek have seen a recent reduction, but the reason for that is unknown. It could be the 

result of the Park Service removal efforts within Bright Angel Creek or due to mainstem water 

temperatures or other factors. We don't believe we can establish a cause and effect 

relationship at this point.

22) Project 9.6: Is this project intended to determine turbidity levels that may constrain trout 

populations and if so, is this really a new idea? Has this been assessed previously? What kind of 

literature review was made to ascertain this before starting? Will there be a separate analysis of 

total suspended solids constraints on trout? Also, what is meant by "constrain rainbow trout 

populations?" If numbers are found, how will these be extrapolated to conditions now occurring 

in the CRE?

Response: These are really good questions. There is a significant body of literature indicating 

that turbidity can exclude rainbow trout from river systems. What is interesting is that the 

levels of turbidity reported in the literature are relatively low, <50 NTU, compared to the 

Colorado River. So the question then becomes how long does the turbidity need to persist to 

impact rainbow trout to the extent that it has the potential to effects populations. This is the 

question we are attempting to answer with our laboratory studies. Once durations and 

magnitudes of turbidity are found in the laboratory we can use that information to look at the 

turbidity record and see if we can link turbidity to trout population fluctuations in the 

mainstem to evaluate it as a fish management tool.

23) Project 9.8: Trout growth in various tailwaters may also be a function of which trout strain exists 

and been studied at the respective tailwater. This factor should be considered when modeling 

bioenergetics.

Response: We attempted to evaluate the growth of various strains of rainbow trout compared 

to Lee’s Ferry rainbow trout in the last workplan. Unfortunately we discovered that we do not 

have adequate facilities to hold large fish for long enough to thoroughly evaluate this 

question. The data that we did collect indicates very little difference in growth among strains 

at small sizes and that food limitations likely overshadow any strain differences.

24) Project 9.10: How will population dynamics from 2014 to 2015 be considered when assessing 

effects of HFEs on trout condition? What new ground will be broken with these results that 

don't already exist in the literature?

Response: Question 1: The rainbow trout population in Glen Canyon is not a static population, 

but rather one that is very dynamic annually with varying densities, size-structure, agestructure, growth, and survival. Therefore, difference observed in the trout response across 

different HFE treatments may be independent of flow or alternatively confounded because of 

the characteristics of the population at that time. In order to test whether or not there is a 

flow effect requires a combination of flow replication across years as well as contrasts made 

between years that do not have accompanying flow treatments. 
Question 2: There is very little information in the current literature to make inferences about 

the seasonal effects related to fall experimental flows on trout population. To date there are 

results published on two spring flows and one fall flow; however, the biological response of 

trout to these seasonal flows were very different. Because of these seasonal differences in 

flow response it has required additional replication as well as a control to make comparisons. 

The reason for the continuation of this project (9.10) was there have been no years since the 

NO fall-marking study was initiated (2012-2014) that there hasn’t been a corresponding HFE 

conducted. Alternatively, when there have been no HFE there has been no extensive fish 

study in place to make inferences in trout response. As stated continuing this study will 

increase the likelihood of having at least one year where flows weren’t conducted in order to 

make a comparison with and without HFE.

25) Project 10.2: It is now apparent that native fish dominate the fish community downstream of 

the LCR yet this area receives disproportionately less attention than upstream of the LCR. 

Should this project attempt to learn what conditions exist downstream of the LCR and compare 

this with areas upstream to see why? 

Response: Project 10.2 is using an across disciplinarian approach to better understand the 

physical factors that may be limiting the distribution and abundance of non-native fish 

particularly trout. This study is not meant to be a native fish habitat study.

Perhaps greater emphasis on maintaining the lower river's fish community conditions could be a 

future goal.

Response: Results from this study will not preclude this emphasis.

26) Project 12, page 96-97, the report doesn’t appear to prioritize a consult with the tribes for 

culturally important vegetation as first.

Response: Not so. The February 2015 workshop was the start of project 12, and as part of that 

workshop, we discussed and collectively agreed on a list of plants to focus on for the pilot 

study.

It also identified species that were important to 3 or more tribes, but it did not present a 

breakdown of how important each species was. For example, one tribe may rely on a single 

plant for 100% of their ceremonies/medicine/etc., but it wouldn’t have made the list if no other 

tribe valued it according to how this is presented. Is that an accurate interpretation of the 

information?

Response: Yes, this is an accurate understanding. We did not attempt to rank the relative 

importance of any particular plant species in terms of how it is valued by any given tribe, nor 

did we attempt to assess how a given plant was used traditionally. We view this information 

as the prerogative of each tribe to share, if they choose to do so. Instead, we focused on 

identifying a list of plants growing in the riparian zone that were traditionally used by three or 

more tribes, as indicated in tribal reports or existing published literature, with the aim of 

including an array of plants that had cultural value for multiple tribes.
27) Project 12, page 98, last paragraph, same issue with photographic record as before, time

between samples and single perspective.

Response: I am not sure that I fully understand this question but will do my best to answer it. 

Use of repeat photography to document ecological change is a well-established method that 

has been in use by scientists for well over a hundred years (a succinct description of this 

method and its history can be found at the following link: 

http://pubs.usgs.gov/fs/2007/3046/fs2007-3046.pdf). We are comparing images taken of the 

river corridor prior to the existence of the dam with current conditions. There are literally 

hundreds of views captured in the collection of photographs we are using for this study; many 

of them show both upstream and downstream views from the same position and many of the 

views are overlapping. We examine matched images and the field notes of the ecologists and 

botanists who participated in the original photo matching to see what has changed. While 

comparison of just one or a few matched images may not be sufficient to reliably characterize 

landscape-scale changes, the cumulative information derived from comparing hundreds of 

matched images can provide a robust perspective on how plant species distribution and 

abundance has changed over time. 

28) Project 12, page 99, what is the practical impact on HFE planning with the discovery of the 1923 

USGS inscription? 

Response: The inscription is located above the 45K flow level, in an obscure location, so there 

is no foreseeable impact in terms of HFE planning.

29) Project 13, please include narrative and costs associated with peer review 

coordination/economics work done for the LTEMP EIS?

Response: Lucas Bair, economist with GCMRC, coordinated and participated in the LTEMP 

power system and rate payer analysis external review. Lucas Bair also reviewed the economic 

elements of the LTEMP EIS prior to release of the public draft. The time associated with peer 

review coordination/economics work done for the LTEMP EIS was included in the total 

provided to Reclamation for work conducted from June 2014 to June 2015, a total of 128.

30) Project 1, page 113, what is the timing of the project’s review/determination?

Response: The timing of this review has yet to be determined. Reclamation has placed funding 

for this project on hold pending an internal review. GCMRC will decide how to proceed once a 

determination regarding the future of this project has been reached.
31) General, it would be helpful to see a single table showing budget compared to actuals, along 

with beginning carryover amount and ending carryover amount.

Response: A table providing budgeted amounts, spending and amount over/under budget by 

project for FY2015 from our annual report is provided below.

Project Budgeted Amount Actual Spent (Over)/Under Budget

1 $305,097 $136,627 $168,470

2 $1,245,886 $1,201,229 $44,657

3 $1,247,234 $1,210,990 $36,244

4 $331,256 $298,348 $32,908

5 $478,584 $464,985 $13,599

6 $549,829 $516,007 $33,822

7 $1,236,062 $1,133,300 $102,762

8 $139,789 $128,622 $11,167

9 $727,502 $675,121 $52,381

10 $146,018 $167,345 ($21,327)

11 $426,585 $377,656 $48,929

12 $45,676 $23,758 $21,918

13 $173,511 $164,215 $9,296

14 $221,768 $210,678 $11,090

15 $954,412 $642,490 $311,922

16 $1,201,669 $1,247,971 ($46,302)

Total $9,430,878 $8,599,341 $831,537