GCMRC Updates 

• 2009 Temperature and Sediment Conditions 

 Mainstem river temperatures peaked at about 18° C at Diamond Creek in late 

July. Temperatures at this location have been similar for the past 4 years, which is lower 

than the peak temperatures of approximately 19° to 20° C reached in the 2000-2005 

period. Mainstem temperature at Lees Ferry is currently about 11° C and will likely peak 

at approximately 13° C in October or November. This is also similar to the past 4 years 

and lower than the 2006 peak temperature at Lees Ferry of 16° C. 

Mass-balance sand budgets have been computed for the period beginning immediately 

after the November 2004 high flow extending through April 2009 for 5 mainstem 

reaches: (1) Upper Marble Canyon (0-30 mile), (2) Lower Marble Canyon (30-61 mile), 

(3) Eastern Grand Canyon (61-87 mile), (4) Central Grand Canyon (87-166 mile), and (5) 

Western Grand Canyon (166-225 mile). These computations show that the sand budget 

leading up to the 2008 high flow was positive (net sand accumulation) in all five reaches 

and was still positive following the high flow. Thus, there was more sand in storage 

following the 2008 high flow than following the 2004 high flow. Between the 2008 high 

flow and April 2009, net sand export occurred in four out of the five mainstem reaches. 

Tributary sediment inputs were small in 2008 and, to date, have been negligible in 2009. 

Multiple moderate tributary input events or a single large input would be required to 

move the system to a condition of significant positive sand mass balance. 

The high-resolution sediment-transport data used to construct these sediment budgets is 

posted on the GCMRC website: http://www.gcmrc.gov/products/other_data/gcmrc.aspx. 

• Integrated flow, temperature, and sediment modeling update 

Wright and others have completed a new “shifting rating curve” model for 

simulating the fate of tributary sand inputs in the mainstem Colorado River below Glen 

Canyon Dam. This model is described in a paper that was submitted to the journal Water 

Resources Research in July 2009. The modeling team is prepared to begin using this 

model to evaluate and compare predicted sand export and accumulation for alternative 

operating scenarios. This work will require cooperation with TWG members in selecting 

and providing hourly input hydrographs. The following generalized scenarios have been 

proposed for evaluation: (1) fluctuating daily flows with variable monthly release 

volume, (2) steady daily flows with variable monthly release volume, (3) fluctuating 

daily flows with steady monthly release volume, (4) steady daily flows with steady 

monthly release volume. We expect that each of these scenarios will be evaluated for a 

range of annual release volumes, e.g. the 2009 actual release volume, 2010 projected 

most probable release volume, etc. 

• HFE Reporting Update, Schedule for Completion 

Most of the 2008 HFE reports are currently being drafted by GCMRC scientists and 

cooperators. A handout will be distributed at the September TWG meeting that lists the 

working titles of the various reports along with the lead authors. 

GCMRC Updates 18 Sept. 2009 pg. 1 
Several of the reports have already been completed and are through USGS peer review 

(eddy modeling and data related to Aeolian sand transport, as well as rainbow trout 

movements). Summaries of the HFE reports shall be included in the FY 2009 annual 

reports that the GCMRC intends to develop this fall for all of the 2009 monitoring and 

research projects. The final results of the 2008 HFE projects will be presented during the 

week of January 11, 2010 at the Annual reporting meeting. 

Synthesis of all HFE results from the 1996, 2004 and 2008 testing is beginning in fall 

2009 and is scheduled to be completed in 2010. The HFE synthesis team is being led by 

Schmidt and Valdez. The synthesis of HFE results will provide information intended to 

inform HFE planning in FY 2011 relative to longer term sediment and flow testing. 

• Senior Ecologist Update 

"AQUATIC SUB-MODEL – Under guidance of the senior ecologist (Walters), GCMRC 

scientists and science cooperators have developed a preliminary ecosystem model using 

Ecopath/Ecosim software, for evaluation of impacts of foodbase changes related to exotic 

invasions, changes in water quality and nutrient loading from Lake Powell, and control of 

exotic predators like rainbow trout. Many of the inputs for this model remain highly 

uncertain, and a workshop among cooperating scientists is scheduled for March 2010 to 

refine them. We will attempt to provide clear and testable alternative hypotheses for the 

recent rainbow trout decline in the Lees Ferry reach, and to incorporate data from NSE in 

assessment of food web changes in the CR reach near the LCR. A second workshop in 

April 2010 is proposed by GCMRC with the senior ecologist and interested stakeholders 

to review the outcome of the aquatics modeling meeting in March. 

In addition and also under the guidance of the senior ecologist, GCMRC has developed 

an Individual Based Model (IBM) for exploring population dynamics of humpback chub 

in more detail, particularly in relation to possible sample biases in the PIT tagging 

program and in relation to recent evidence of increasing HBC rearing in the CR mainstem 

downstream from the LCR. The IBM has shown that there is potentially a severe 

retrospective biases in ASMR reconstructions of HBC recruitment rates, and that the best 

estimate of annual recruitment comes from the ASMR estimation done one year after the 

recruitment occurs. Correcting this problem has demonstrated more clearly that there has 

been a relatively sudden and large increase in HBC recruitment since 2000, but probably 

beginning before the period of natural warming that started in 2003-04. In conjunction 

with estimates of HBC juvenile abundance in the NSE program, it now appears that a 

substantial proportion (up to 30%) of the net recruitment to the HBC adult population 

may soon be coming from mainstem rearing. 

PHYSICAL SUB-MODEL - Progress on upgrading the physical submodel of the Grand 

Canyon ecosystem model has been made in FY 2009. Wright and others have completed 

a new “shifting rating curve” model for simulating the fate of tributary sand inputs in the 

mainstem Colorado River below Glen Canyon Dam. This model is described in a paper 

that was submitted to the journal Water Resources Research in July 2009. Korman and 

Wright are also collaborating, as part of the ecosystem and integrated modeling projects, 

GCMRC Updates 18 Sept. 2009 pg. 2 
on updating the hydrology data for use as dam operations input that drive future 

simulations for sand transport using the new shifting rating curve model.” 

• FY2010 Planned Reports for GCMRC and USBR 

During FY 2010, the GCMRC proposes a large number of USGS reports on a wide 

variety of monitoring and research topics; including the several reports related to the 

2008 High Flow Experiment. 

Physical Science and Modeling Program - 15 technical reports (journal articles, Open 

File and Scientific Investigation Reports) and Fact Sheets related to quality of water 

(turbidity) and sediment sampling methods, as well as sediment transport data and fate of 

backwaters from the 2008 HFE. Synthesis of all physical results from the past three 

HFEs is also scheduled for 2010. 

Sociocultural Program - Three USGS technical reports and a Fact Sheet are anticipated 

on topics related to cultural resources (including virtual shorelines). 

DASA Program - Two USGS Data Series Reports related to digital remotely sensed 

imagery and one Open File Report on mapping of shoreline habitats from remotely 

sensed imagery are anticipated from the DASA Program. 

Biology Program - Three USGS reports are planned. One on the Low Summer Steady 

Flow synthesis, another on the food web research project and a third on the effects of 

water temperature. A fourth report on vegetation synthesis may also be produced in FY 

2010. 

As many as 25 USGS reports are proposed during 2010, making it the most ambitious 

publication year to date. Owing to the large number of reports, the GCMRC management 

team is working with the editorial staff to prioritize the order in which the reports are 

processed through the USGS Fundamental Science Practices for peer review and delivery 

to the Enterprise Publishing Network within the western region of USGS during the year. 

Highest priority in the first quarter of the fiscal year will be on getting the 2008 HFE 

reports completed by January 2010 

• November Workshop: Economics and CMP Planning Discussion 

CMP Review

The draft General Core Monitoring Plan was reviewed by the Science Advisors during 

August 2009. The GCMRC staff is now preparing a revision of the draft plan and 

responses to the SA’s review comments for distribution to the TWG on October 16th. 

The comment period for TWG is proposed to be one month with comments being 

returned on the comment table by November 13th. 

The CMP workshop will be convened on December 1st in Phoenix at the Arizona Water 

District Office in conjunction with the socioeconomic workshop on Dec.2-3. This will 

give GCMRC about 10 days to review TWG comments and come to the workshop with 

GCMRC Updates 18 Sept. 2009 pg. 3 
preliminary responses and proposals for further revision of the general plan. The 

objectives of the CMP workshop include: 

1) discuss the elements of the monitoring plan and development of the draft relative to 

the steps outlined in the MRP; 

2) discuss the Science Advisors' review of the draft and the GCMRC responses; 

3) review the current status of the various PEPs related to the proposed projects and 

timeline for implementation; 

4) discuss the GCMRC's responses to TWG comments on the draft general plan; and 

5) seek additional input from TWG on next steps toward implementation of core 

monitoring in future workplans/budgets (recommendation to AMWG for their 

consideration). 

Socioeconomic Workshop

The socioeconomic workshop will occur immediately following the CMP review on 

December 2 and the morning of December 3. 

As described in the prospectus (attached), there will be three parts to the socioeconomic 

workshop: Part I on the morning of Dec. 2 will involve several presentations about past 

and recent socioeconomic studies by various individuals who were involved with those 

efforts. On the afternoon of Dec. 2 there will be a facilitated discussion with TWG 

members about their socioeconomic information needs and priorities. Several external 

economic experts have been invited to listen in and observe the proceedings on Dec. 2, 

and at the end of Part 2 they will try to clarify what they have heard. On the morning of 

Dec. 3 they will present to TWG some preliminary findings and recommendations on 

how the TWG can most effectively proceed with developing highest priority information 

needs for the program. We anticipate that the socioeconomic workshop will conclude by 

noon on Dec. 3. 

• Biological Update 

Fish PEP Implementation

Agency personnel will be reviewing their catch data this fall and winter to evaluate the 

change in monitoring focus recommended by the 2009 Protocol Evaluation Panel for 

Grand Canyon Fishes. The PEP’s final report should be delivered in October. Based on 

the initial summary of recommendations, the following analyses are anticipated: 

1. Mainstem fish monitoring results with one and two trips (AZGFD) 

2. Closed population estimate of humpback chub using only spring and only fall 

capture data (USFWS) 

3. ASMR model runs using only spring and only fall capture data (GCMRC) 

The results of these analyses will be subjected to peer review. Peer-reviewed results will 

be distributed to TWG for discussion in a meeting to review the Grand Canyon fish 

sampling program for fiscal year 2011 (FY 2010 is similar to FY 09 in most cases). The 

2010-11 work plan describes fish monitoring for these two years in greater detail. A 

meeting with TWG to review the implications of the analyses for FY 11 is anticipated for 

February 2010. 

Trout Natal Origins

GCMRC Updates 18 Sept. 2009 pg. 4 
GCMRC personnel have drafted an outline of what a manuscript addressing this subject 

would include. The outline is being reviewed with outside reviewers and the Senior 

Ecologist. At this time we expect that the manuscript will include a literature review, 

documentation of known capture locations and spawning areas, any genetic information 

that may be available, and a discussion of the potential hypotheses regarding where these 

fish may be spawned and how those hypotheses can best be supported or refuted. We 

expect to determine if additional monitoring is needed to answer questions about rainbow 

and brown trout spawning areas based on analysis of possible alternative spawning 

locations. 

Trout Removal Evaluation

AZGFD removed trout from the LCR reach in May 2009. Numbers of rainbow trout 

captured were: 1873 removed (2075 captured and released in control reach). Other nonnative species were removed and their numbers were: 33 bullhead species, 20 brown 

trout, 1 channel catfish, 55 common carp, 566 fathead minnow, 1 plains killifish, 1 red 

shiner. These data have been used to support modeling conducted by Coggins that 

estimates levels of effort necessary to keep the LCR reach rainbow trout population at the 

target 10% level (LGC graph). These estimates of effort are being used in a revision of 

the Nonnative Control Plan. Amount of effort needed to keep the LCR population below 

10% is dependent on the immigration rate into the reach. 

LSSF Update

 A summary report is being created that is intended to further our understanding 

about the relationships between physical habitat parameters and biological responses 

under steady flow releases from Glen Canyon Dam. From the period of April through 

September 2000, a complex hydrograph was executed to test hypotheses about the 

relationships between river volumes, water temperature and native fish spawning and 

recruitment requirements. The experimental hydrograph was developed in response to a 

recommended and prudent alternative issued by the Fish and Wildlife Service with the 

1994 Biological Opinion associated with the operations of Glen Canyon Dam. The 

experimental flows were to be implemented during minimum delivery water years (WY). 

WY2000 was the first 8.23 m.a.f. year since the signing of the Record of Decision for 

Glen Canyon Dam (DOI, 1996). The decision to implement the experimental flows was 

made in February and March of 2000. It was the first experiment since the 1996 Beach 

Habitat Building Flow (Webb and others, 1999) that releases from Glen Canyon Dam 

were controlled for a period of time greater than a week for experimental purposes. 

 The extended time frame for the experiment was designed to illicit a biological 

response from long-lived native fishes by spanning timeframes of spawning, emergence 

and growth of young of year fishes. Data collection with respect to native and nonnative 

fish response was focused on the steady flow period (June – September) to measure the 

growth and distribution of the rainbow trout in Glen Canyon and the fish community 

downstream of Lees Ferry. The steady flow period with discharges of 8,000 cfs was 

hypothesized to provide warmer mainstem and shoreline water as well as stabilize 

habitat. Colder temperatures and destabilized shoreline habitats associated with 

operations are identified as factors contributing to recruitment decline in humpback chub 

and other native fishes (Minckley, 1991). 

GCMRC Updates 18 Sept. 2009 pg. 5 
 Mainstem water temperatures near the Little Colorado River in 2000 were not 

significantly different from previous fluctuating flow years releasing similar volumes, 

while water temperatures in Western Grand Canyon were warmer than in previous years. 

Wright and others (2008) demonstrated that initial release temperatures influence the 

amount of possible warming in the upper portion of the Colorado River, while volume 

and ambient temperatures affect warming in the western portions of Grand Canyon. 

Measurement of shoreline temperatures near the confluence of the Little Colorado River 

indicate surface temperature reached optimum temperatures for young of year fish 

growth, but the depth of warming along the shoreline is unknown. Temperature probes in 

shoreline habitats indicate that surface temperatures quickly returned to mainstem 

temperature values when the sun was obscured or following sunset. 

 Fish growth data from 2000 seining efforts did not show that the combination of 

steady shorelines and warm water resulted in changes in length frequencies compared 

with previous years. The lack of an observable growth response in fish even in the 

western portions of Grand Canyon, where waters were warmer longer, may be 

attributable to three alternative hypotheses: a. Multiple spawning events adding new 

recruits to sampling sites (Trammell and others, 2002) and kept length frequencies 

stagnant, b. An ontogenetic shift by larger fishes out of backwater-type environments 

and into other environments that are less susceptible to seining nets or other gear types 

(Trammell and others, 2002) resulted in no changes in length frequencies, or c. Predation 

of young fish by non-natives resulted in little changes in length frequency. An updated 

abundance estimates for humpback chub (Coggins and Walters, 2009) suggests that 

recruitment strength began increasing in the mid to late 1990s, and that 1998-2000 year 

cohort may have benefited from the steady flow experiment which may support the first 

two hypotheses. However the authors caution against such a post-hoc evaluation. They 

indicate a lack of confidence that the recruitment time-series are completely 

uncontaminated by ageing error and subsequent retrospective bias as reasons for having 

only limited confidence in this explanation. Alternatively, evaluation of 2000 data with 

historic data and data collected since 2000 for native and nonnative fishes around the 

LCR confluence may lend support the third hypotheses, fish predation, regarding a lack 

of growth response by young fishes. 

 Other resource responses to the hydrograph and the interactions of resources are 

included in the summary report. Notable among these are the response of tamarisk to 

newly available open habitats associated with the steady flow period and following a 

habitat maintenance flow that redistributed sediment (Porter and Kearsley, 2002, Schmidt 

and others, 2007), the tradeoff responses the reduced flows had on camping and rafting 

experiences (Roberts and Bieri, 2001, Jonas and Stewart, 2002), and the economic effect 

of the experiment on the local economy and the broader electrical user group (Hjerpe and 

Kim, 2002, Palmer and others, 2004). A timeline for completion of the report is outlined 

in the attached table. In general, stronger conclusions regarding the experiment on fishes 

and other resources could have been made if more time had been available in the 

planning effort, and if long-term monitoring of resources had been in place prior to the 

experiment to provide more baseline information. 

GCMRC Updates 18 Sept. 2009 pg. 6 
Schedule of LSSF Reporting 

Draft completion November 1, 2009 

Draft review (USGS review process) November – January 2010 

Report to TWG during Annual Reporting 

Mtg 

January 2010 

Revision and submit for policy review 

USGS 

February 2010 

Submit to USGS publishing OFR March 2010 

Dissemination to AMP June/July 2010 

GCMRC Updates 18 Sept. 2009 pg. 7 
Literature Cited (LSSF report) 

Coggins, L.G., Jr., and Waters, C.J., 2009, Abundance trends and status of the Little 

Colorado River population of humpback chub; an update considering data from 1989-

2008: U.S. Geological Survey Open-File Report 2009-1075, 18 p. 

Hjerpe, E., and Kim, Y. 2002. Economical impacts of low summer steady flows on 

recreation. Final Report, Northern Arizona University to U.S. Geological Survey, Grand 

Canyon Monitoring and Research Center, Flagstaff, AZ. 

Jonas, L.M., and Stewart, W.P. 2002. An overview of various impacts to Grand Canyon 

river experiences, with a focus on intergroup encounters, flow levels and the 2000 low 

summer steady flow experiment. SWCA, Inc., Environmental Consultants Final Report 

submitted to U.S. Geological Survey, Grand Canyon Monitoring and Research Center, 

Flagstaff, AZ. 

Minckley, W.L. 1991. Native fishes of the Grand Canyon region: an obituary? In 

Marzolf, G.R., ed., Colorado River ecology and dam management: Washington, D.C., 

National Academy Press, p. 124-177. 

Palmer, S. C., Burbidge, C., Patno, H. 2004. The financial impacts of the low summer 

steady flow experiment at Glen Canyon Dam. Final report Western Area Power 

Administration to U.S. Geological Survey, Grand Canyon Monitoring and Research 

Center, Flagstaff, AZ. 

Porter, M.E. and Kearsley, M.J.C. 2002 Response of riparian vegetation to two 

contrasting managed flow regimes of the Colorado River in Grand Canyon, AZ. Final 

report from Northern Arizona University to U.S. Geological Survey, Grand Canyon 

Monitoring and Research Center, Flagstaff, AZ. 

Roberts, C. and Bieri, J., 2001. Impacts of low flow rates on recreational rafting traffic on 

the Colorado River in Grand Canyon National Park. Final report from Northern Arizona 

University to U.S. Geological Survey, Grand Canyon Monitoring and Research Center, 

Flagstaff, AZ. 

Schmidt, J.C., Topping, D.J., Rubin, D.M., Hazel, J.E. Jr., Kaplinski, M., Wiele, S.M., 

and Goeking, S.A. 2007. Streamflow and sediment data collected to determine the effects 

of low summer steady flows and habitat maintenance flows in 2000 on the Colorado 

River between Lees Ferry and Bright Angel Creek. U.S. Geological Survey Open-File 

Report 2007-1268 86 p. 

Trammell, M, R. Valdez, S. Carothers, and R. Ryel. 2002 Effects of a low steady 

summer flow experiment on native fishes of the Colorado River in Grand Canyon, 

Arizona. Final Report to the Grand Canyon Monitoring and Research Center. Flagstaff, 

AZ. 77p. 

U.S. Department of Interior. 1996. Record of Decision, Operation of Glen Canyon Dam: 

Washington, D.C., Office of the Secretary of Interior, 13p. 

GCMRC Updates 18 Sept. 2009 pg. 8 
GCMRC Updates 18 Sept. 2009 pg. 9 

Wright, S.A., Anderson, C.R. and Voichick, N. 2008. A simplified water temperature 

model for the Colorado River below Glen Canyon Dam. River Research and 

Applications. DOI: 10.1002/rra.1179.