In cooperation with the Glen Canyon Dam Adaptive Management Program 

Science Plan for Future Experimental 

Beach/Habitat-Building Flows Released from Glen 

Canyon Dam 

By Melis, T.S., Hamill, J.F., Andersen, M.E., Fairley, H.C., Topping, D.J, Draut, A.E., Rubin, D.M., Wright, S.A., 

Ralston, B.E., Kennedy, T.A., Coggins, L.G., Vernieu, W.S., Cross, W., Hall, R., and Rosi-Marshall, E. 

Technical Work Group 

Review Draft: August 15, 2007 

U.S. Department of the Interior 

U.S. Geological Survey 
ii

U.S. Department of the Interior 

DIRK KEMPTHORNE, Secretary 

U.S. Geological Survey 

Mark D. Myers, Director 

U.S. Geological Survey, Reston, Virginia 2007 

Revised and reprinted: 2007 

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Suggested citation: 

By Melis, T.S., Hamill, J.F., Andersen, M.E., Fairley, H.C., Topping, D.J, Draut, A.E., Rubin, D.M., 

Wright, S.A., Ralston, B.E., Kennedy, T.A., Coggins, L.G., Vernieu, W.S., Cross, W., Hall, R., and 

Rosi-Marshall, E.., 2007, Science plan for future experimental beach/habitat-building flows 

released from Glen Canyon Dam: U.S. Geological Survey, Grand Canyon Monitoring and 

Research Center, 87 p. 

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endorsement by the U.S. Government. 

Although this report is in the public domain, permission must be secured from the individual 

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iii

 Contents 

Introduction, Background, and Overview...................................................................................................................... 1

Introduction ..................................................................................................................................................................... 1 

Background ..................................................................................................................................................................... 3

Recommended Sediment Triggering,Magnitude, and Duration of a Future BHBF Test ................................... 6

Integrating Research and Monitoring for a Future BHBF Test ............................................................................ 11

Proposals for the Experimental Studies................................................................................................................... 12 

Experimental Study Descriptions .................................................................................................................................. 20

References Cited.............................................................................................................................................................. 56

Appendix A ........................................................................................................................................................................ 65 

Appendix B ........................................................................................................................................................................ 76 

Appendix C......................................................................................................................................................................... 85

Figures 

1. The Colorado River ecosystem encompasses the river corridor that extends from the forebay of 

Glen Canyon Dam to the western boundary of Grand Canyon National Park, Arizona........................... 2 

2. Flow chart for evaluating future BHBF test results intended to test the concept of "flow only" 

operational treatments combined with tributary sand supplies below Glen Canyon Dam to 

rebuild sandbar habitats and enhance related resources ........................................................................... 9 

3. Potential effects of a BHBF test on invertebrate production............................................................................... 40 

Tables 

1. Scientific questions related to AMWG information needs that will be addressed by the BHBF 

Science Plan........................................................................................................................................................ 13 

2. Summary of proposed studies and estimated costs associated with a future integrated 

beach/habitat-building flows (BHBF) test...................................................................................................... 15 

3. Locations of various project components for experimental study 1.C............................................................... 30 

4. Established vegetation sites and corresponding experimental study 1.C sandbar sites by river 

mile ........................................................................................................................................................................ 36 

5. Logistical support requirements for proposed experimental studies................................................................. 54 
1

Science Plan for Future Experimental 

Beach/Habitat-Building Flows Released from Glen 

Canyon Dam 

By Melis, T.S., Hamill, J.F., Andersen, M.E., Fairley, H.C., Topping, D.J, Draut, A.E., Rubin, D.M., 

Wright, S.A., Ralston, B.E., Kennedy, T.A., Coggins, L.G., Vernieu, W.S., Cross, W., Hall, R., and 

Rosi-Marshall, E. 

Introduction 

This science plan describes proposed monitoring and research activities to be conducted 

by the U.S. Geological Survey’s (USGS) Grand Canyon Monitoring and Research Center 

(GCMRC) in the event that the Secretary of the Interior approves the release of another 

beach/habitat-building flows (BHBF) test from Glen Canyon Dam in the future. The GCMRC 

has responsibility for scientific monitoring and research efforts for the Glen Canyon Dam 

Adaptive Management Program (GCDAMP). Established in 1997, the GCDAMP is a federally 

authorized initiative to ensure that the primary mandate of the Grand Canyon Protection Act of 

1992 (GCPA; title XVIII, secs. 1801–1809, of Public Law 102-575) is met through a strategy of 

adaptive ecosystem assessment and management. The GCPA recognized the need to address the 

impacts to the downstream ecosystem resulting from the ongoing operation of Glen Canyon 

Dam. As a result, the GCDAMP was established, in part, to provide for long-term research and 

monitoring of downstream resources. The scientific information obtained by the GCMRC and its 

cooperators is used by the GCDAMP as the basis for recommendations for dam operations and 

management actions. Because of the lengthy lead time required to plan and execute a BHBF test, 

the Adaptive Management Work Group (AMWG)—the Federal Advisory Committee within the 

GCDAMP that provides recommendations to the Secretary of the Interior on the operation of 

Glen Canyon Dam—recommended that the GCMRC develop this science plan in anticipation of 

a future BHBF test. This plan is designed to build upon existing understanding to inform 

managers about the efficacy of using BHBF tests to rebuild not only sandbars but also to benefit 

related resources in Marble and Grand Canyons through flood disturbance. Although this plan is 

not intended to be a complete and comprehensive long-term experimental plan, it might be 

integrated, as one of several subcomponents, into any future longer term experimental plan for 

evaluating the influence of one or more BHBF tests over a decadal timeframe. 

As defined by the 1995 Operation of Glen Canyon Dam Final Environmental Impact 

Statement (EIS), a BHBF test is a release of water from Glen Canyon Dam that is at least 10,000 

cubic feet per second (cfs) greater than allowable peak discharge (30,000 cfs) but not greater 

than 45,000 cfs (U.S. Department of the Interior, 1995). The EIS termed these experimental 

releases beach/habitat-building flows because they were intended to, at least in part, mimic 

predam floods that previously maintained sandbars and related habitat throughout the Colorado 

River ecosystem (CRE)—the Colorado River corridor from just below Glen Canyon Dam to the 
2

western boundary of Grand Canyon National Park (fig. 1). For the purpose of this science plan, 

these non-emergency high-flow dam releases shall be referred to as BHBFs or BHBF tests. 

Owing to their magnitude, BHBF tests are considered to be bypasses or spills because they 

exceed normal powerplant capacity. To date, only two such tests (1996 and 2004) have been 

implemented to evaluate the degree to which beaches and sandbars can be rebuilt and maintained 

using this flow-only management strategy in combination with downstream sand supplies from 

tributaries below the dam. 

Rebuilding and maintaining sandbars in the CRE in the postdam era requires the periodic 

release of high flows from the dam to transfer sand from the channel into eddy-sandbar 

environments (Schmidt and others, 1999a). In transferring sand to shorelines, BHBFs are known 

to form nearshore habitats, such as backwaters (Goeking and others, 2003) that may serve as 

nursery areas for fish. Off-channel habitats have been shown to support Colorado River native 

fishes in reaches of the Colorado River other than Grand Canyon (Mueller, 2006). Owing to the 

higher flow velocities that occur during BHBF tests, these operations may also disadvantage 

nonnative fish (Minckley and Meffe, 1987), which are of concern because they compete with 

native species such as the endangered humpback chub (Gila cypha) for food and prey on young 

native fish (Minckley and Meffe, 1987; Minckley and Deacon, 1991; Lynch and others, 1996; 

Figure 1. The Colorado River ecosystem encompasses the river corridor that extends from the 

forebay of Glen Canyon Dam to the western boundary of Grand Canyon National Park, Arizona. 
3

Tyus and Saunders, 2000). Shoreline sandbar deposits that are built during BHBF tests are also 

sources of sand that can be transported by wind to areas upslope; this windborne sand may 

protect archaeological resources from weathering and erosion. Sandbars are used extensively as 

recreational campsites by backcountry visitors such as whitewater rafters and backpackers, and 

BHBF tests help to conserve and maintain open sand area for camping. Conservation of sand 

resources, endangered humpback chub, and cultural resources found in the Colorado River 

ecosystem are primary goals of the Glen Canyon Dam Adaptive Management Program (U.S. 

Department of the Interior, 1995; Patten and others, 2001). 

Although this science plan primarily focuses on potential experimental studies associated 

with a future BHBF test, the plan also addresses concerns expressed by GCDAMP participants 

about issues related to future high-flow experimental research, particularly associated costs and 

benefits. Appendix A presents the issues of concern identified by GCDAMP participants, 

relevant information about these issues gathered during the science-planning process, and an 

assessment of each issue prepared by GCMRC scientists. Efforts have also been made in 

appendix A to identify the pros and cons of a future BHBF test, especially related to the duration 

of a future BHBF test. Because the degree to which native humpback chub might be affected by 

BHBF tests is of particular interest to managers, information about factors influencing future 

fishery studies tied to BHBF testing is presented in appendix B. Appendix C describes an 

additional monitoring project proposed by the GCMRC to be undertaken in June of each year to 

determine how native and nonnative fishes use sandbar-controlled habitats and to measure the 

extent of these habitats at the onset of higher summer flows. 

Background 

The most pressing question that sediment researchers have been asked to address for the 

GCDAMP is if it is possible to rebuild and maintain sandbar habitats in the Colorado River 

ecosystem over the long term solely through the manipulation of Glen Canyon Dam releases. 

The GCMRC Strategic Science Plan (2007–11) articulates the question as follows: Is there a 

“flow-only” operation that will rebuild and maintain sandbar habitats over decadal timescales? 

This question is the primary strategic science question driving sediment studies that justifies 

future BHBF testing. Determining if it is possible to maintain sandbars using dam releases is 

particularly relevant because about 94% of the predam sand supply is now trapped above Glen 

Canyon Dam in Lake Powell (Wright and others, 2005). 

Despite continual advances in the understanding of the physical dynamics of the 

Colorado River ecosystem that have accrued since the GCDAMP’s inception a decade ago, 

existing information and models are not yet capable of determining if it is possible to rebuild and 

maintain sand resources over the long term solely through the manipulation of dam releases. 

Scientists have concluded that answering the question will require a commitment to at least one 

future BHBF test. However, it is more likely that answering the question will require an ongoing 

program of BHBF tests implemented at perhaps the same frequency as annual average to aboveaverage new sand is provided to the system by Colorado River tributaries. The rationale for 

conducting experiments under sediment-enriched conditions has been documented in several 

peer-reviewed outlets, including Webb and others (1999), Topping and others (2000a), Rubin 

and Topping (2001), Rubin and others (2002), Schmidt and others (2004), Wright and others 

(2005), Hazel and others (2006), Topping and others (2006a), and Melis and others (2007). 

The sediment-related data that researchers propose to collect for a future BHBF test will 

facilitate comparison with data collected during the two previous BHBF tests conducted in 1996 
4

and 2004. Proposed experimental studies will also generate new data that can be compared to 

previous tests on the physical processes regulating sandbar erosion and deposition during BHBF 

testing, sediment deposition at archaeological sites and camping areas, ecosystem flux 

measurements related to organic tributary inputs, effects of flood disturbance on vegetation, and 

formation of backwater habitats used by native and nonnative fishes. These comparisons are 

required to determine whether greater and more geographically extensive sandbar rebuilding is 

possible with a future BHBF test than occurred during the 1996 and 2004 tests. The data are also 

needed to determine if consecutive BHBF tests in the future might cause sand to accumulate 

through time to reverse erosion documented after the closure of Glen Canyon Dam in 1963. The 

results may have implications for native fish survival, cultural resource preservation, and habitat 

enhancement benefits for other high-priority aspects of the Colorado River ecosystem. Fully 

answering the strategic sediment science question posed above will also require additional data 

that will likely only be collected during future monitoring activities. Therefore, fully resolving 

whether it is possible to rebuild and maintain sand resources over the long term solely through 

the manipulation of dam releases will require a commitment to both experimental BHBF testing 

integrated with consistent long-term monitoring.

2004 High Flow Findings 

In September 2002, the U.S. Department of the Interior (DOI) approved implementation 

of new BHBF testing tied to triggering thresholds linked to sand inputs from the Paria River 

(U.S. Department of the Interior, 2002). This experimental strategy was adopted in response to 

new findings about CRE sediment-transport behavior that indicated the annual sand input from 

tributaries was not accumulating over multiyear periods under the modified low fluctuating flow 

(MLFF) alternative, also known as Record of Decision operations (Wright and others, 2005). As 

a result, the 2002 experiment focused on evaluating how effectively BHBF tests might be used to 

move new sand provided by tributaries up onto shorelines before it was transported downstream 

and exported to Lake Mead. The sand input trigger was specifically targeted to be a volume of 

sand from the Paria River that, on average, would occur about every other year. Significant sand 

inputs to Marble Canyon occurred during September–November 2004 and exceeded the 

sediment trigger. Approval of a supplemental environmental assessment (U.S. Department of the 

Interior, 2004) paved the way for the BHBF test that began on Sunday, November 21, 2004. The 

2004 experiment was the only BHBF test conducted as a result of the Paria sediment trigger, but 

it marked a major step forward in efforts to answer the strategic sediment question. 

During the 2004 experiment, a net transfer of channel sand into eddies resulted in an 

increase in sandbar total area and volume in the upper half of Marble Canyon (Topping and 

others, 2006a). Further downstream, where sand was less abundant, the experiment resulted in 

the net transfer of sand out of eddies (Topping and others, 2006a). Scientists also confirmed that 

substantial increases in total eddy-sandbar area and volume are only possible during high-flow 

releases conducted under the sand-enriched conditions that follow large tributary floods (Rubin 

and others, 2002; Topping and others, 2006a). In the future, more sand than the 800,000 to 

1,000,000 metric-tons of sand available during the 2004 BHBF test will be required to achieve 

increases in total eddy-sandbar area and volume throughout all of Marble and Grand Canyons 

(Topping and others, 2006a). At present, scientists cannot estimate how much more sand may be 

required to rebuild and maintain sand habitats; the amount of sand will certainly depend upon 

what resource managers might desire in terms of future sandbar conditions. 
5

Because tributary inputs of sand larger than those that preceded the 2004 BHBF test are 

relatively rare, it is not considered feasible to achieve significant systemwide rebuilding of 

sandbars with a single BHBF test. Rather, the most promising strategy for rebuilding sandbars 

systemwide over the long term may be to follow each average to above-average tributary input 

of sand with a short-duration BHBF test (Topping and others, 2006a). Under such a “sand 

banking” scenario, each subsequent BHBF test is presumed to build upon the results of the 

previous one, potentially resulting in cumulative increases in systemwide sandbar area and 

volume over decadal time scales. However, this strategy is only feasible if the intervening 

powerplant releases do not completely erode the sand deposited in sandbars during previous 

BHBF tests. The challenge is to determine whether or not there exists a combination of BHBF 

tests and fluctuating flows that can rebuild and maintain sandbars with only about 6% to 10% of 

the sand that was available to the system in the predam era. Since theory and monitoring data 

have shown that fluctuating flows transport more sand than equivalent-volume steady flows, 

intervening releases with the least amount of fluctuation will have the highest probability of 

maintaining the sandbar building achieved during future BHBF tests. Hence, there is a long-term 

need for monitoring sandbar changes throughout any future period that might include repeated 

BHBF tests under multiple sand enrichment scenarios (perhaps at least over a decade). Such 

monitoring will be needed to completely answer the core science question for sediment. 

Four methods for achieving the required sand monitoring were recommended to the 

GCDAMP Technical Work Group (TWG) in 2007. While the recommended monitoring 

protocols are not experimental by themselves, they provide the majority of the information to 

fully evaluate future BHBF tests by allowing scientists to determine whether or not future 

tributary sand inputs are being conserved in a sustainable manner. This science plan assumes that 

sufficient long-term sediment monitoring will occur during 2008 and beyond, which will 

supplement BHBF test evaluations, to allow scientists to investigate the effects of dam 

operations that occur after and between any additional future tests. 

Earlier studies (e.g., Hereford and others, 1996; Draut and others, 2005) showed that 

many prehistoric cultural sites found in Grand Canyon are not only built on Colorado River flood 

deposits but also are buried by windborne sand derived from river-deposited sediment that has 

helped to preserve them over time. Results following the 2004 BHBF test confirmed that high 

flows released under sand-enriched conditions can increase the nearshore source areas for 

windborne sand, leading to increases in the rate of sand transported toward some locations in 

Grand Canyon that contain cultural resources (Draut and Rubin, 2006). Another hypothesis that 

is being evaluated is whether or not increased sand transport by wind and backfilling of gullies 

and deflated areas with aeolian sand may potentially reduce the rate of erosion and increase the 

preservation potential of these sites. 

Monitoring of the Colorado River fish community occurred before and after the 

November 2004 BHBF test; however, the monitoring results were confounded by storm-induced 

flooding of the Little Colorado River that transpired between the two sampling events. Native 

fish numbers were reduced in the post-event sampling, but the significance of this finding is not 

clear because turbidity changed dramatically between the two sampling events. Turbidity will 

alter how fish respond to various types of sampling gear and may also reduce the ability of 

researchers to capture fish. Further, displacement of fishes, especially native fishes, in 

southwestern rivers following a flood may not have a negative effect on the native fish 

community, and may, in fact, be a hydrologic change to which they are well adapted (Valdez and 

others, 2001; Brouder, 2001). For example, the 1996 BHBF test had little effect on the 
6

distribution, abundance, or movement of native fishes and temporarily reduced densities of some 

nonnative fish species (Valdez and others, 2001). 

Summary of Key Findings from the 2004 BHBF Test 

• Although substantially more sand was present in suspension in upper Marble Canyon during 

the 41,500 cfs 2004 BHBF test than during the 45,000 cfs 1996 BHBF test, there was less 

sand in suspension further downstream during the 2004 BHBF than during the 1996 BHBF 

(Topping and others, 2006a). 

• During the 2004 BHBF test, the net transfer of channel sand into eddies resulted in an 

increase in sandbar total area and volume in the upper half of Marble Canyon. Further 

downstream, where sand was less abundant, the response of eddy sandbars during the 2004 

BHBF test was similar to that observed throughout Marble and Grand Canyons during the 

1996 BHBF test: a net transfer of sand out of eddies occurred (Topping and others, 2006a). 

• Substantial increases in total eddy-sandbar area and volume (such as those observed in the 

upper half of Marble Canyon following the 2004 BHBF test) are only possible during BHBF 

testing conducted under the sand-enriched conditions that follow large tributary floods 

(Rubin and others, 2002; Topping and others, 2006a). 

• After the 2004 BHBF test, where substantial flood sediment still remained until the 

subsequent spring windy season, windborne sand transport was significantly greater than in 

the previous spring given comparable wind conditions (Draut and Rubin, 2006). 

• Numbers of fish sampled following the 2004 BHBF test were lower than those sampled 

before the test, but the conditions under which the fish were sampled in the two periods was 

not comparable, limiting the ability of researchers to draw conclusions about the response of 

fish to the high-flow event. 

Recommended Sediment Triggering, Magnitude and Duration of a Future 

BHBF Test 

Sand Triggering 

Following the 2004 BHBF test, the sand input trigger was reevaluated by the GCMRC 

and the Science Planning Group (SPG). In developing long-term experimental options, the SPG 

suggested that the 2002 sediment trigger be revised to include measured and modeled sand inputs 

from the Little Colorado River (LCR) and other lesser tributaries in addition to the Paria River 

(U.S. Geological Survey, 2006). The SPG-proposed sediment trigger would allow a BHBF test 

to occur when 0.5 million metric tons of sand are introduced by the Paria River and retained 

above river mile (RM) 30 and an additional “weighted” 0.5 million metric tons of sand are 

delivered by the Paria and Little Colorado Rivers, or sources that enter the ecosystem annually in 

between these two primary tributaries, and are retained upstream of Diamond Creek (RM 226). 

To calculate the weighted input, sand from the Paria River is given full value and sand from the 

LCR and other sources is valued at 50% of the actual sand input. Thus, depending on how much 
7

of the sand is derived from the Paria River, a future BHBF test could be triggered with an input 

of 1.0 to 1.5 million metric tons of sand. The rationale for revising the sand input trigger is that it 

allows experimentation under enriched sand conditions that might occur below Marble Canyon 

during periods when the Paria River inputs alone may not equal the earlier trigger, but weights 

the Paria River inputs over downstream inputs to prevent BHBFs tests from occurring at times 

when the Marble Canyon has not had any annual sand inputs. Under the SPG-suggested revised 

triggering criteria, long-term implementation of repeated BHBF experiments might occur more 

frequently than under the original 2002 triggering criteria. Sediment scientists suggest that the 

proposed change would likely facilitate a more rapid evaluation of whether or not cumulative 

sandbar deposition occurs on a systemwide basis through time. 

Peak Flow Magnitude 

Consistent with the 1995 EIS (U.S. Department of the Interior, 1995), as well as previous 

BHBFs in 1996 and 2004, future tests should be conducted in the range of 41,500 to 45,000 cfs, 

or possibly higher when Lake Powell storage is high enough to reach the spillway gate 

elevations, to promote the most robust conservation of sand at higher elevations along the river 

banks. Replication of the 2004 peak magnitude of 41,500 cfs during a future BHBF test has the 

most likelihood for supporting comparative analyses intended to determine the potential for 

using sand-enriched BHBFs to build and maintain sandbar habitats.

Peak Flow Duration and the Lag Time Phenomenon 

The concept of replicating the 2004 BHBF test hydrograph (i.e., replicating the 

hydrograph of that portion of the 2004 experiment consisting of the rising limb, peak, and 

recession of the November 2004 BHBF test) was discussed extensively among cooperating 

sediment scientists at the 2005 knowledge assessment workshop convened by the GCMRC with 

stakeholders. The 2004 BHBF test hydrograph was designed using sandbar simulations for a 

subset of eddies under a scenario of 45,000 cfs peak magnitude and sand concentrations that 

were measured in the postdam era. These simulations and data collected in conjunction with the 

1996 BHBF test were used to select 60 hours as duration of the peak flow for the 2004 BHBF, 

which was much shorter than the 168-hour test that occurred in 1996. The 2004 peak magnitude 

was limited to 41,500 cfs because one of the eight units at Glen Canyon Dam was undergoing 

maintenance. 

Replicating the 2004 BHBF hydrograph in a future test with sand-enriched conditions 

would allow scientists to determine if the locally robust and consistent sandbar-building 

responses that occurred in upper Marble Canyon as the result of the 2004 BHBF test can be 

repeated. Scientists will also examine the downstream progression of sandbar building during the 

next BHBF test conducted under locally sand-enriched conditions. By reproducing the 2004 test 

hydrograph when sand-enriched conditions exist during a future BHBF test, scientists will also 

be able to evaluate if there are cumulative benefits to sandbar conservation in lower Marble 

Canyon and Grand Canyon each time a sand-enriched BHBF test occurs. 

The GCMRC and its science cooperators recently evaluated the limitations and benefits 

of a shorter duration peak at 41,500 cfs. Exact predictions about the outcome of a BHBF test 

with a shorter duration are not possible at this time without field experimentation because current 

sediment models have limited utility for estimating sandbar responses over long reaches, and 

there are many factors to consider related to peak-flow duration and peak magnitudes for BHBF 

experiments. While the main recommendation from scientists at present is to use the same 
8

hydrograph for the next test as was used in 2004, they also acknowledge that a future BHBF test 

lasting not less than 30 hours might also result in sandbar building benefits and would also 

advance learning about a BHBF and sediment dynamics.In table A.2 of appendix A, the 

GCMRC compares the pros and cons associated with a 60-hour versus 30-hour peak high-flow 

test duration. 

Because physics dictates that mass is conserved, flood waves in a wet channel travel 

downstream at a higher velocity than the water (Lighthill and Whitman, 1955). Additionally, the 

water travels much faster than the sand in suspension. Thus, depending on the longitudinal 

distribution of sand in the river, substantial lags may develop between a BHBF flood wave and 

the sand in transport, with the flood wave greatly leading the suspended sand. During the 2004 

BHBF test, this disparity in travel time between the flood wave and the water and new sand input 

from the Paria River was as much as 27 hours by the time the flow peak reached Diamond 

Creek, more that 240 river miles below Glen Canyon Dam. Evaluation of the flow and sediment 

data from the 2004 test clearly showed that once the peak had moved ahead of the new sand 

supply in upper Marble Canyon, it essentially became another test of the 1996 BHBF test (under 

depleted sand conditions), except with even less sand available in downstream reaches owing to 

continued sand export between 1996 and 2004. 

Fall dam releases that preceded the 2004 BHBF test (5,000 to 10,000 cfs daily range) 

were very effective in limiting downstream sand transport between September and late 

November 2004. However, because these releases caused most of the new sand to be stockpiled 

in the upper section of Marble Canyon, the flood wave’s higher velocity took it downstream of 

the new sand supply by the time the flood reached lower Marble Canyon and beyond. As a 

result, sediment scientists now suggest the need to evaluate some period of normal dam 

operations following the input of new sand to allow some redistribution of new sand before 

conducting a future BHBF test. Allowing the sand to be redistributed before a BHBF test might 

produce more optimal sandbar building than occurred during the 2004 test. The hypothesis to test 

here is that a more uniformly distributed new sand supply will be more evenly transferred to 

eddy sandbars throughout this critical upper Canyon reach as the fast-moving flood wave 

propagates downstream. If the results from replicating the 2004 hydrograph under sand-enriched 

conditions in the spring following one to several months of downstream sand transport under 

1996 Record of Decision operations are as positive as those measured in 2004, then this 

approach may be interpreted as being a sustainable strategy for longer term habitat rebuilding 

and maintenance (see fig. 2). Positive in this case means that the next BHBF test produces more 

uniformly distributed sandbar responses under conditions of more uniformly distributed sand 

supply downstream, and, in the longer term, deposition progresses farther downriver with 

successive BHBFs as upriver eddies become filled. 

Seasonal Timing Considerations for a Future BHBF Test 

Sediment Inputs and Hydrology 

The optimal timing of a future BHBF test is dependent on the timing of tributary floods 

and sand inputs as well as flow releases from the dam, which are in turn dependent on variations 
9

Figure 2. Flow chart for evaluating future BHBF test results intended to test the concept of “flow 

only” operational treatments combined with tributary sand supplies below Glen Canyon Dam to 

rebuild sandbar habitats and enhance related resources. If available sand can be increased 

Yes 

No

No

Conduct replicated1 BHBF test under 

sand triggering – measure changes in 

eddy-sandbar area and volume for the 

next test whenever it occurs 

Measure changes in eddy-sandbar area 

and volume during approved 

intervening dam operations 

ASK: Do gains from BHBF 

testing exceed loss(es) during 

intervening operations? 

ASK: Are gains in eddy-sandbar 

area and volume meeting stated 

management objectives (desired 

future conditions)? 

Evaluate options for increasing 

available sand, such as changing 

intervening operations and/or 

mechanical sand augmentation to 

achieve desired future conditions 

Yes

Conduct additional 

studies (such as modeling 

simulations) to optimize 

BHBF timing, frequency, 

and hydrograph shape & 

continue sand monitoring 

1 Replication implies use of a similar BHBF test hydrograph to 

November 2004, recognizing that it is impossible to replicate the 

exact initial conditions (i.e. tributary sand inputs are controlled by 

nature). Replication of the hydrograph allows for more direct 

comparison between tests and also serves as a monitoring tool to 

help evaluate whether or not sand resources are improving. 
10

in upper Colorado River Basin hydrology. As a result, the optimal timing for a BHBF test in one 

year may not be the same as in another year. In general, the optimal timing is when the most new 

tributary-derived sand is available throughout the system. Historically, the largest Paria River 

sand inputs have occurred during the late summer and fall thunderstorm season. For the Little 

Colorado River, large sand inputs may occur during the late summer and fall thunderstorm 

season as well as during springtime floods. The rate at which the tributary-derived sand is 

exported downstream to Lake Mead is dependent on the availability of the new sand and flow 

releases from the dam. Under moderate and higher dam releases, the export rate can be quite 

high, which may constrain the time available for the new sand to be used for BHBF tests (Rubin 

and others, 2002). The majority of sand in a moderate input is predicted to be lost within days (at 

discharges of >35,000 cfs), weeks (at discharges of ~25,000 cfs), or months (at discharges of 

~15,000 cfs); however, at discharge rates of 10,000 cfs or less, sand is retained for periods of 

months to years (Rubin and others, 2002). As discussed previously, under moderate or higher 

dam releases, the new sand will only be available for BHBF tests if such a release occurs shortly 

after new sand enters the river ecosystem. Under lower dam releases, the new sand will be 

available for BHBF tests that occur well after new sand enters the river ecosystem. 

In terms of the availability of sand, the optimal timing of BHBF tests will vary from year 

to year. For example, during periods of wet hydrology and high dam releases, when export rates 

are expected to be high, the optimal time to conduct a BHBF test would likely be within days or 

weeks of large tributary inputs such as during late fall for typical Paria inputs. Conversely, 

during periods of dry hydrology and low volume dam releases, when export rates are expected to 

be lower, it may be optimal to wait until later in the winter or early spring, a delay which may 

allow sand from the Paria and Little Colorado Rivers to both accumulate throughout the various 

sediment input seasons and be more evenly distributed throughout reaches of interest (e.g., 

Marble and eastern Grand Canyons). Finally, export rates are dependent on the amount of 

fluctuation and the total volume; thus, the amount of diurnal flow fluctuation will affect the 

amount of sand available and the optimal timing of a future BHBF test (i.e., less daily 

fluctuations lead to more retention and thus more flexibility in experimental BHBF timing). 

Biology 

Consideration of the life cycles and current life histories of many Colorado River 

organisms leads the GCMRC to recommend a BHBF test in March. This timing is before the 

flowering of the nonnative tamarisk (Tamarix ramosissima), and so would reduce the potential 

for increasing its distribution. Native fishes historically experienced high flows in most years 

closer to the summer solstice; however, in the current environment, a June flood flow would be 

less desirable because of the potential to reduce survival among an already limited number of 

native fishes, especially humpback chub. Humpback chub and other native species likely are 

adapted to surviving high flows, but their current numbers are lower than the historical Grand 

Canyon population and mainstem water temperatures are colder, so conducting a high flow 

earlier in the year, in March, is less likely to reduce survivorship, especially among younger year 

classes. A March high flow could support increases in the numbers of native fishes if it creates 

additional habitats where young native fish can find refuge from predation and benefit from 

warmer water temperatures that encourage growth. A March BHBF is expected to have moderate 

to low impact on the production of algae and diatoms between the dam and Lees Ferry and, as a 

result, should not limit the availability of these food sources for nonnative and native fishes. 

Rather, a March BHBF has the potential to crop off senescent or dead algae and encouraging 
11

fresh, new growth as increased solar radiation is available from March through October as 

opposed to the remainder of the year. 

Cultural Resources 

From the standpoint of the cultural resources component of this experiment, the optimal 

timing for future a BHBF test is late winter or early spring (late February through early April). In 

terms of effects to archaeological sites, this timing maximizes the potential of newly formed 

high-elevation sand deposits to be retained and subsequently redistributed by wind above the 

41,000–45,000 cfs level. Previous research (Draut and Rubin 2006, 2007) has shown that the 

April through June period typically has the highest wind transport potential, but in order for this 

potential to have maximum utility for affecting archaeological sites, a sufficiently large portion 

of the newly formed sandbars must be retained as dry sand at higher elevations before the start of 

the spring windy season. Large fluctuations following a BHBF test have the potential to rapidly 

rework new sandbars and reduce the overall supply of dry sand available for subsequent 

transport by wind. Therefore, the optimal time to rebuild sandbars with a BHBF test would be 

just before the onset of the spring windy season and before the onset of higher fluctuating flow 

regimes that typically occur in response to seasonally driven increased power demands (i.e., 

during the period following the high fluctuating flows of winter and before the high fluctuations 

of summer). In terms of native plants important to Native American people, a late winter or early 

spring BHBF test is most likely to improve conditions for propagation and growth of native 

riparian species while limiting the potential spread of certain exotics, such as tamarisk. 

Integrating Research and Monitoring for a Future BHBF Test 

Previous BHBF tests, in 1996 and 2004, consisted of several physical, biological, and 

sociocultural studies; however, these studies were not fully coordinated to achieve objectives for 

integrating data and interpretive results. Developing a more integrated research and monitoring 

program is a major goal of the GCMRC during the next phase of its strategic science initiative 

(Strategic Science Plan for FY 2007–11). Several science planning meetings between GCMRC 

scientists and cooperators in 2006 resulted in a more integrated study plan than those associated 

with previous BHBF tests. For instance, sediment studies have been more closely integrated 

between suspended-sediment flux measurements, eddy sandbar and flow and sand deposition 

measurements, and modeling activities. Further, sociocultural elements and objectives related to 

the fate of new sandbars following a BHBF test, particularly with respect to secondary aeolian 

transport into archaeological sites (tied to better meteorological data), have been integrated into 

the core sediment study plan (see linked elements of experimental studies 1.A, 1.B, and 1.C). In 

this way, studies 1.A and 1.C become more than merely an accounting scheme for sandbars and 

sediment transport, while study 1.B emphasizes sediment process research intended to further 

modeling of beach dynamics and sand transport. 

Links between sediment and biological studies are also highlighted. In response to 

discussions among GCMRC scientists and with GCDAMP stakeholders, the GCMRC is 

proposing to add an additional monitoring project that will incorporate biological and physical 

habitat elements. Because this project is proposed to be implemented every year, whether or not 

a BHBF test is conducted, it is presented in this document as appendix C. Conducting this 

additional monitoring at the beginning of June each year will provide baseline data on the 

condition and variability of backwater habitats each year, including how these habitats are or are 
12

not used by fishes, to allow for comparison with years in which a BHBF test is conducted. This 

science plan also proposes to closely coordinate the study of riparian vegetation dynamics with 

sandbar sedimentology and fine-sediment flux data (see experimental study 2). Efforts to explore 

how BHBFs affect lower trophic levels (experimental study 3) has several study components, 

each of which is intended to interface with sediment project components. In particular, 

experimental study 3 is concerned with the fate of organics, the tributary derived debris (wood, 

seeds, and other organic materials) that enters the ecosystem with sediment inputs, and its 

movement through the river corridor. Previous studies have documented that much of this 

organic carbon becomes mixed within new sandbar deposits and may persist in buried beaches 

for extended periods, but none of the previous research has been linked to whole system carbon 

budgets. This information will be critical for ultimately measuring the effect of BHBF tests on 

inputs, retention, and export of organic matter that fuels river food webs. 

The Grand Canyon fish community is actively monitored annually and these data will be 

used to help evaluate the impacts of a future BHBF test on this resource. Scientists at the 

GCMRC are actively working on additional methods to further evaluate the fish community 

before and after a future BHBF test, including additional analysis in the form of occupancy 

modeling and tagging/tracking methods (see appendix B). Experimental study 4 describes 

proposed assessment of the rainbow trout early life stages and the potential transport of this 

species in response to BHBF flows. Finally, experimental study 5 attempts to document changes 

in Lake Powell and resultant downstream quality of water; data that are intended to inform 

productivity studies associated with experimental study 3. 

Proposals for the Experimental Studies 

This science plan describes the suite of additional research and monitoring activities 

thought to be desirable, feasible, and necessary to interpret and understand how conducting a 

future BHBF test during sand-enriched conditions affects key downstream resources. The 

experimental studies presented in this plan are designed to explore and possibly answer a number 

of scientific questions related to priority information needs identified by the Adaptive 

Management Work Group (table 1). In some cases, current technologies and methods were found 

to be inadequate for answering some priority questions, such as predicting the influence of a 

future BHBF test on native fish populations. As mentioned earlier, appendix B identifies ongoing 

monitoring and research activities associated with various resources, the challenges that 

confronted scientists in attempting to develop this BHBF science plan, and other considerations 

that influenced the selection of the experimental studies identified here. 

The experimental studies presented in this science plan also recognize that resource 

responses are driven not only by the physical effects of the BHBF tests but also by interrelation 

among resources. As a result, this science plan integrates the evaluation of the high-flow effects 

across multiple resources. 

The experimental studies identified below are in addition to or represent an expansion of 

ongoing research and monitoring activities typically included in the GCMRC’s annual work 

plans. The implementation of research and monitoring activities associated with proposed 

experimental studies will represent a substantial undertaking by the GCMRC, cooperators, and 

contractors. To adjust to the increased workload that occurs in any year when a BHBF test takes 

place, the GCMRC proposes to (1) increase the activities of existing contractors and cooperators, 

(2) add additional onsite contractors to the degree feasible and affordable, and (3) temporarily 

add technical staff to existing projects. In the area of sediment monitoring, certain annual sand 
13

Table 1. Scientific questions related to AMWG information needs that will be addressed by the 

BHBF Science Plan 

 SEDIMENT 

• Is there a “flow-only” operation that will rebuild and maintain sandbar habitats over decadal timescales? 

• What is the minimum duration for BHBF tests needed to build and maintain sandbars under sand 

enrichment? 

• Do sandbars deposited by BHBF tests contribute to preservation of archaeological sites in the river 

corridor? 

• How do post-BHBF flows affect the persistence of sandbars and related backwater habitats? 

HUMPBACK CHUB 

• Do BHBF tests result in creation of nearshore habitats (i.e., backwaters) that can offer physical benefits to 

humpback chub and other native fishes? 

• Do BHBF tests affect the distribution and movement of nonnative fishes? 

CULTURAL RESOURCES 

• Do sandbars deposited by BHBF tests contribute to preservation of archaeological sites in the river 

corridor? 

• Do BHBF tests contribute to added stability or erosion of archaeological sites located in close proximity to 

the river? 

• How does the abundance and distribution of native and nonnative riparian species important to Native 

American tribes change in response to a future BHBF test? 

OTHER PRIORITY ISSUES 

• Rainbow trout: How will a BHBF affect spawning, survival of early life history stages of rainbow trout in 

the Lees Ferry reach? Will a BHBF stimulate downstream migration of age-1 RBT? 

• Food base: How will a future BHBF test affect food production and availability for rainbow trout in the 

Lees Ferry reach? What are the effects of BHBF tests on aquatic food production? How do these effects 

impact native fishes? 

• Lake Powell: Will the next BHBF test result in higher nutrient releases and shrinking of the hypolimnion? 

Will the operation of the river outlet works and the penstocks at capacity measurably alter Lake Powell 

hydrodynamics or stratification, or alter release water quality? 

• Riparian vegetation: Are open patches more susceptible to exotic species colonization and establishment 

than sites with existing vegetation following a disturbance?

• Kanab ambersnail: Will the next BHBF test reduce habitat at Vaseys Paradise in a way that impacts the 

ambersnail population? 

• Camping beaches associated with sandbars: Can the next BHBF test increase campable areas at sandbars 

on a sustainable basis? 
14

mapping activities (annual replication of reach-scale channel mapping and systemwide overflight 

for digital imagery if this quadrennial protocol coincides with the year of BHBF testing) are 

proposed by the GCMRC to be delayed by 1 year after the next BHBF is tested. When essential, 

new agreements and contracts would also be established for appropriate periods to accomplish 

the new research related to a future BHBF test. Clearly, the additional personnel, equipment, and 

supply costs associated with a future BHBF test will require additional funding. 

A description of each proposed experimental study, including the program goals and 

management objectives each study is designed to advance and the projected cost of each activity 

follows. Each study description includes a section that identifies links to other studies that are 

designed to promote integrated, cross-disciplinary science collaborations and outcomes. 

These studies are briefly summarized along with estimated costs in table 2. 
15

Table 2. Summary of proposed studies and estimated costs associated with a future integrated beach/habitat-btest. 

BHBF Related 

Experimental 

Studies 

Goal Associated with Study Hypotheses Costs Yea

1. SEDIMENT AND CULTURAL STUDIES 1.A – Sand Budgeting 1.B – Sandbar Depositional Rates 

1.A – Sand Budgeting: (1) reach-based accounting of input vs. export during a future BHBF test, (2) longitudinal patterns of erosion and deposition of sand, and (3) changes in sediment grain size related to enrichment/depletion of sand 1.B – Sandbar Deposition Rates: improve understanding of time evolution of eddy sandbars and rate of deposition or erosion of eddy sandbars during a future BHBF test to determine optimal BHBF peak duration necessary to achieve management goals. 

1.A – Sand Budgeting: A future BHBF test with sand enrichment similar to the 2004 test will result in bar building comparable to that observed during the 2004 BHBF test. If true, then sand budget will be positive between river-miles 0 and 30 for the period bracketing the tributary inputs of sand and the next BHBF test. If reaches downstream from river-mile 30 are sand-enriched relative to the 2004 test, then bar building in these reaches will be greater than was observed in these reaches during the 2004 test and the sand budgets in these reaches will also be more positive than in 2004. 1.B – Sandbar Deposition Rates: Sand deposition rates during a future BHBF test are regulated by (1) interaction of the flow field with the antecedent bed topography and (2) the upstream sand supply. At a given location and for a given BHBF hydrograph, sandbars grow over time if upstream sand supply is sufficiently large; conversely, if upstream sand supply is insufficient, then 

1.A – $31

1.B – $9
16

1.C – Sandbar Fate: Topographic and Grain-size Responses 2.C – Sandbar Fate: Effects of new Sand Deposits at Cultural Sites 3.C – Sandbar Fate: Changes in Campable Area 

1.C – Sandbar Fate: (1) determine if BHBF testing conducted under sediment-enriched conditions can maintain/sustain eddy sandbars and associated campsite area, and (2) whether increased aeolian flux of sand from larger sandbars produced during a future sand-enriched BHBF test can maintain downwind (but upslope) archaeological sites 

sandbars will erode. 1.C – Sandbar Fate: a future BHBF test under sand enrichment like those before the 2004 test results in bar building and low-elevation gully infilling comparable to that observed during 2004 test. 2.C – If reaches downstream from river-mile 30 are more sand-enriched compared to pre2004-test conditions, then bar building and gully infilling in these reaches will be greater than was observed in these reaches during the 2004 test. 3.C – Larger, dry sandbars will result in increased aeolian flux of sand to downwind dune fields (some of which contain archaeological sites), thereby increasing the preservation potential of some sites. 

1.C – $49

2. RIPARIAN VEGETATION STUDIES 

2. – Native/nonnative diversity and richness – Compare native/nonnative diversity in established and reworked depositional environments along a hydrological gradient following a future BHBF test. 

2. – Hypothesis 1: Native/nonnative species richness ratios are the same across all habitats and surface elevations up to 60,000 csf. Alternative hypothesis: The ratio between native/nonnative richness and cover at sites with established vegetative communities will not change following disturbance because resource availability is limited by the presence of existing species. Bare areas will 

2. – $4
17

have ratios of native/nonnative richness and cover values similar to those of established sites. Surface elevation will not have an affect on native/nonnative richness and cover values. Alternative hypothesis: The ratio between native/nonnative richness and cover at sites with established vegetative communities will shift toward an increase in nonnative richness and cover because of the increased nutrient availability associated with the experimental BHBF disturbance. Native/nonnative richness and cover ratios will change by surface elevation with nonnative species decreasing with increasing surface elevations in relation to available soil nutrients. Bare areas will favor nonnative species across all surface elevations. 

3. AQUATICS FISH AND FOOD STUDIES 3.A – Lower Trophic Levels 4. A – Rainbow Trout Studies – 

3.A – Lower Trophic Levels: To determine whether or not a future BHBF test has a neutral, negative, or positive effect on the quantity and quality of food available for invertebrates, and ultimately fishes. 4.A. – To determine how a future BHBF test affect spawning, survival of early life history 

3.A – Lower Trophic Levels: To determine whether or not a short-duration BHBF test in spring initially scours the river bottom causing reductions in algal biomass, but the new algal community is of higher quality, more productive, and is assimilated more efficiently by invertebrate consumers, leading to an increase in annual invertebrate production. 4.A. – Hypotheses that will be evaluated are: (1) a future BHBF test will scour redds 

3.A – $14

4.A – $4
18

Early Life History 4.B – Rainbow Trout Studies - Displacement Appendix C. Spring Backwater Monitoring 

stages of rainbow trout in the Lees Ferry reach, and potential for simulating downstream migration of age-1 fish. 4.B – The goals of this experimental study are: (1) to determine if a BHBF test causes displacement of rainbow trout from the Lees Ferry reach into Marble Canyon and eastern Grand Canyon; (2) to determine if such displacement is experienced differentially among different length fish; and (3) to provide a platform for Grand Canyon scientists to develop skills with acoustic technologies that can be applied to answering questions about native and nonnative fish movement and distribution and sampling efficiencies.

App. C – The goal of this project is to 

increase knowledge of the physical characteristics of backwater habitats and their use by the fish community. 

(spawning nests) but the effect on the juvenile population will be limited because of compensatory survival responses, and (2) a BHBF test will alter the distribution of age-1 fish in the Lees Ferry reach resulting in either higher mortality or migration out of the reach. 4.B – A future BHBF test will result in displacement young rainbow trout from the Lees Ferry reach into Marble Canyon and eastern Grand Canyon. This trout redistribution will be inversely related to the size of fish.App. C. – This project will allow for an assessment of the area and volume of these habitats that is available in years with and without a BHBF, testing whether BHBFs create additional backwater habitats that can be used by fishes. The project also allows for evaluation of whether these habitats are used by native fishes before the summer solstice. . 

4.B – $70

App. C – 

$103,490 

5. LAKE POWELL 
19

5. – Influence of a future BHBF test on Lake Powell Water Quality 

5. – Determine how a future BHBF test will alter QW in tailwaters of GCD and Lake Powell fore bay 

5. – Determine whether or not a future BHBF test will result in higher nutrient releases and shrinking of the hypolimnion. 

5. – $1

6. LOGISTICAL SUPPORT 

6. – Provide efficient and expert logistical support to all aspects of the GCMRC science team during a future BHBF test; collaborate with the NPS to establish an informative public outreach plan to ensure the safety of recreational users of the Colorado River. 

6. – N/A 6. – $7

ANTICIPATED CONSERVATION MEASURES  - Kanab Ambersnail Habitat  - Archaeological Sites (yet to be determined by the GCDAMP and key agencies) Public Outreach Activities (yet to be determined by the GCDAMP) 

KAS – habitat at Vaseys Paradise Arch Site Mitigation – Glen Canyon site (cost of mitigating potential impacts to the Glen Canyon site is included in the FY08 archaeological site treatment budget ) 

Public Outreach Activities (included in Logistical Support budget; estimated at 

$15,000 for Year 1, none for Year 2) 

N/A N/A N/A 

KAS – $

Cultural Si

See 

Public Outre

See 

YEAR 1 AND YEAR 2 TOTALS: $1,409

YEAR 1 AND YEAR 2 COMBINED TOTAL BUDGET: 
20

Part 2: Experimental Study Descriptions 

Experimental Study 1.A: Reach-scale changes in the fine-sediment 

mass balance and grain size during a future BHBF test 

Duration 

20 months 

Principal Investigators 

David Topping, U.S. Geological Survey BRD, Southwest Biological Science Center, Grand 

Canyon Monitoring and Research Center and David M. Rubin, U.S. Geological Survey GD, 

Western Coastal and Marine Geology 

Geographic Scope 

River miles 0 through 226

Project Goal(s) 

This project documents the following: (1) reach-based sediment budgeting during a future BHBF 

test, (2) longitudinal patterns of net erosion and deposition of sand, and (3) temporal and spatial 

changes in sediment grain size related to enrichment/depletion of sediment during a future BHBF 

test. 

Need for Project 

Detailed measurements of sediment flux and grain size are required to evaluate whether a future 

BHBF test conducted under sand-enriched conditions can be used to maintain/sustain eddy 

sandbars in the Colorado River ecosystem. These data are also required for continued 

development/verification of predictive physically based sediment-transport models. 

Strategic Science Question(s)

4.1 Is there a “Flow-Only” operation (i.e., a strategy for dam releases, including 

managing tributary inputs with BHBFs, without sediment augmentation) that will rebuild 

and maintain sandbar habitats over decadal time scales? 

Working Hypotheses 

Future BHBF testing conducted under magnitudes and longitudinal distributions of sand 

enrichment similar to those that existed before the 2004 BHBF test will result in sandbar 

building comparable to that observed during the 2004 BHBF test. If this is the case, the sand 

budget computed under this project will be positive between river miles 0 and 30 for the period 

bracketing the tributary inputs of sand and a future BHBF test. If reaches downstream from river 

mile 30 are sand enriched relative to their condition before the 2004 BHBF test, then sandbar 
21

building in these downstream reaches will be greater than was observed in these reaches during 

the 2004 BHBF test. 

Methods 

Hydrodynamic, sediment transport, grain size, temperature, conductivity, and turbidity data are 

to be collected at five locations (Lees Ferry gaging station, river mile 30, river mile 61, Grand 

Canyon gaging station, and above Diamond Creek gaging station) and on two Lagrangian river 

trips (tracking the water between river miles 0 and 226). Suspended-sediment data are collected 

using both conventional and laser-acoustic methodologies. Stage, discharge, and water-quality 

data are to be collected using standard USGS methodologies. Similar work conducted during the 

1996 and 2004 BHBF tests and 2000 low summer steady flow experiment is described in 

Konieczki and others (1997), Rubin and others (1998, 2002), Topping and others (1999, 2000a, 

2000b, 2006a, 2006b), Rubin and Topping (2001), and Hazel and others (2006). Analyses as 

described in Rubin and others (1998) and Topping and others (1999, 2006b) of sedimenttransport and sand grain-size data and analyses of reach-based sand budgets will be used to 

evaluate the results of a future BHBF test relative to the BHBF tests conducted in 1996 and 

2004. If the working hypotheses are supported by these analyses, then rebuilding and 

maintenance of sandbars might be possible through a future BHBF test conducted under sandenriched conditions. If the working hypotheses are rejected by these analyses, then flow and nonflow strategies in addition to or other than BHBF tests may be needed to restore and maintain 

sandbars in the Colorado River ecosystem (i.e., further constraint of operations, sediment 

augmentation, or a combination of both (see fig. 1.2)). 

Links/Relationship to Other Projects 

This project builds on the large quantity of previous published work on sediment transport, 

erosion, and deposition in the Colorado River ecosystem downstream from Glen Canyon Dam. It 

is also linked to several BHBF-related physical, sociocultural, and biological projects, including 

experimental studies 1.B (Studies of eddy-sandbar hydrodynamics, sediment transport, and 

bathymetry during a future BHBF test), 1.C (Response of sandbars and selected cultural sites to a 

future BHBF test conducted under sediment-enriched conditions), 2 (Evaluate effect of a future 

BHBF test on riparian plant community development at multiple surface elevations and 

depositional environments), and 3 (BHBF testing effects on lower trophic levels in the CRE). 

Work conducted under this project will also be used by the ongoing project of the USGS’s Lew 

Coggins, Scott Wright, and Nick Voichick relating fish-catch rates to suspended-sediment 

concentration and grain size. 

Information Needs Addressed 

The project will directly address multiple information needs, for example, as follows: 

EIN 8.1.1 How do fine sediment abundance, grain-size, and distribution in the main 

channel below 5,000 cfs change in response to an experiment performed under the 

Record of Decision, unanticipated event, or other management action? 
22

EIN 8.3.1 How does fine sediment abundance, grain-size, and distribution, within eddies 

below 5,000 cfs change in response to an experiment performed under the Record of 

Decision, unanticipated event, or other management action? 

RIN 8.5.2 What is the reach-scale variability of fine-sediment storage throughout the 

main channel? 

RIN 8.1.3, RIN 8.2.1, RIN 8.3.1, RIN 8.5.6 What fine sediment abundance and 

distribution, by reach, is desirable to support GCDAMP ecosystem goals? [Note: 

Definition of “desirable” will be derived from targets for other resources and managers 

goals.] 

RIN 7.3.1 Develop simulation models for Lake Powell and the Colorado River to predict 

water quality conditions under various operating scenarios, supplant monitoring efforts, 

and elucidate understanding of the effects of dam operations, climate, and basin 

hydrology on Colorado River water quality.

Products/Reports 

Several peer-reviewed journal article(s) and/or USGS report(s) will be produced based on the 

findings of a future BHBF test within 12–24 months of the next BHBF test. 

Costs by Year (specific fiscal years are not shown here, although FY 2007 costs are used 

for cost estimating purposes) 

FUNDING PROPOSAL 

Experimental Study 1.A: Reach scale changes in the fine-sediment mass balance and grain size 

during a future BHBF test (Sand Budgeting) 

 Year 1 Year 2 

GCMRC Personnel Costs (19.1% Burden) $30,000 $30,000 

GCMRC Project Related Travel / Training (19.1% Burden) $7,000 $5,000 

GCMRC Operations / Supplies / Publishing (19.1% Burden) $12,000 $15,000 

GCMRC Equipment Purchase / Replacement (19.1% Burden) - - 

AMP Logistical Support (19.1% Burden) $110,000 - 

Outside GCMRC & Contract Science Labor (19.1%) - $26,000 

Cooperative / Interagency Agreements (6.09% Burden) $118,200 - 

Project Sub-total $277,200 $76,000 

DOI Customer Burden (Combined 6.09% and/or 19.1%) $37,567 $14,516 

Project Total (Gross) $314,767 $90,516 

Percent Outsourced (includes 50% logistical support) 62% 34%
23

Experimental Study 1.B: Studies of eddy-sandbar hydrodynamics, 

sediment transport, and bathymetry during a future BHBF test 

Duration 

20 months 

Principal Investigators 

Scott Wright, U.S. Geological Survey WRD, California Water Science Center; Mark 

Schmeeckle, Arizona State University; and Matt Kaplinski, Northern Arizona University 

Geographic Scope 

Middle Marble Canyon around Eminence (river mile 45) 

Project Goal(s) 

The goal of this project is to improve our understanding of the time evolution of eddy sandbars 

during a future BHBF test. Knowledge of the rate of deposition or erosion of eddy sandbars 

during a future BHBF test will assist in the determination of the optimal BHBF hydrograph 

shape for a given sand-supply condition to achieve sandbar resource management goals, while 

minimizing negative impacts to other resources (e.g., hydropower). 

Need for Project 

The development of predictive capabilities for the evolution of eddy sandbars, a primary 

recommendation of the August 2006 sediment protocol evaluation panel (Wohl and others, 

2006), has been limited by a lack of information on hydrodynamics, sediment transport, and 

bathymetry during a BHBF test. The lack of predictive capability has in turn limited our ability 

to provide definitive recommendations related to experimental BHBF peak discharge and 

duration. The existing eddy model (Wiele and others, 1996; Wiele, 1998) has been tested only 

with before and after bathymetry downstream from the Little Colorado River following floods in 

1993. Also, initial investigations of eddy hydrodynamics and sediment transport during the 

November 2004 BHBF test indicated that some of the assumptions in the existing model are not 

supported by the data (Wright and Gartner, 2006). Thus, detailed data are needed on eddy 

hydrodynamics and morphology during a future BHBF test, if we are to improve our predictive 

capabilities and thus improve our ability to identify future BHBF test characteristics that most 

effectively rebuild and maintain available sand resources and related habitats. 

Strategic Science Question(s) 

4.1-1 Is there a “Flow-Only” operation (i.e. a strategy for dam releases, including 

managing tributary inputs with BHBFs, without sediment augmentation) that will rebuild 

and maintain sandbar habitats over decadal time scales? 

4.1-1a What are the short-term responses of sandbars to BHBFs? 
24

4.1-1b What is the rate of change in eddy storage (erosion) during time intervals between 

BHBFs? 

4.1-1c What are the effects of ramping rates on sediment transport and sandbar stability? 

Working Hypotheses 

Sand deposition rates in eddies during a future BHBF test are regulated by (1) the interaction of 

the flow field with the antecedent bed topography and (2) the upstream sand supply. At a given 

location for a given BHBF hydrograph, an eddy sandbar will grow over time if the upstream 

sand supply is sufficiently large; conversely, if the upstream sand supply is insufficient, an eddy 

sandbar will erode over time. 

Methods 

This project collects hydrodynamic, sediment transport, bathymetric, and load-cell data at several 

eddy sandbars in middle Marble Canyon in order to improve our understanding of eddy-sandbar 

hydrodynamics and evolution during a future BHBF test. 

We will use two separate methods to collect information on (1) the detailed temporal evolution 

of eddy sandbars at a sparse spatial resolution, and (2) the detailed spatial structure of 

hydrodynamics, sediment transport, and bathymetry at a sparse temporal scale. Ideally, sites 

throughout Marble and Grand Canyons would be studied during a single BHBF but this is not 

logistically feasible. As a compromise, sites in middle Marble Canyon will be studied because 

(1) results from the November 2004 BHBF test indicate that eddies in this reach may provide 

varied responses and (2) there are several eddy sandbars close to each other that have been 

studied previously as part of the Northern Arizona University long-term sandbar monitoring and 

the Integrated Fine-Sediment Team (FIST) projects. 

The detailed temporal evolution of eddy sandbars at a sparse spatial resolution will be measured 

by deploying an array of load sensors in three eddy sandbars in the reach around river mile 45 

(Eminence). The load sensors proposed for use here were used successfully for this purpose in 

Grand Canyon during the 1996 BHBF test (Carpenter, 1996) and for monitoring the infilling of 

spawning gravels with fine sediment (see http://www.rickly.com/ss/scoursensor.htm for a 

product description). The study team proposes to bury three to four load sensors within each 

eddy sandbar at different elevations to capture deposition or erosion that occurs during the rising 

limb, peak, and falling limb of the experimental BHBF hydrograph. 

The detailed spatial structure of hydrodynamics, sediment transport, and bathymetry at a sparse 

temporal scale will be measured with a sonar system and an acoustic doppler current profiler 

(ADCP) using automated shore-based boat position tracking. The study area is within a FIST 

project reach, so the survey control is already established. The team will map the eddy sandbars 

where the load sensors are deployed as frequently as possible under the logistical constraints. At 

minimum, we plan to obtain a map of each eddy sandbar before a future BHBF test, during the 

rising limb, on the peak, during the falling limb, and after a future BHBF test. The ability to get 

multiple maps during a given segment will depend on the timing of the next experimental BHBF 

(i.e., mapping will only be possible during daylight hours) and the peak duration. Each survey 

will result in a bathymetric map of the eddy sandbar and a map of the time-averaged 3-

dimensional velocity structure of the eddy. Additionally, the team will collect sediment samples 
25

and attempt to calibrate the acoustic backscatter from the ADCP to suspended-sand 

concentration (we have had success with this in the past; see Topping and others, 2006b). If 

successful, we will further develop maps of time-averaged suspended-sand concentration within 

each eddy for each survey, which, when combined with the velocity maps, will allow us to 

generate maps of the time-averaged flux of suspended-sand within the eddy. 

Links/Relationship to Other Projects 

This project is linked closely to previous and ongoing work related to numerical modeling eddysandbar morphology. The data acquired through this initiative have the potential to significantly 

enhance ongoing and potential future developments of numerical models of eddy-sandbar 

responses to high-flow releases from the dam. The project is also linked to several other 

experimental BHBF-related physical, sociocultural, and biological projects by providing 

sediment transport data, eddy-sandbar bathymetry, and eddy-sandbar hydrodynamics and 

morphology, including experimental study 1.A (Reach-scale changes in the fine-sediment mass 

balance and grain size during a future BHBF test), experimental study 1.C (Response of sandbars 

and selected cultural sites to a future BHBF test conducted under sediment-enriched conditions), 

experimental study 2 (Evaluate effect of a future BHBF test on riparian plant community 

development at multiple surface elevations and depositional environments), and experimental 

study 3 (BHBF Testing effects on lower trophic levels in the Colorado River ecosystem). 

Information Needs Addressed 

The project will directly address several experimental and research information needs, as 

follows: 

EIN 8.3.1 How does fine sediment abundance, grain-size, and distribution, within eddies 

below 5,000 cfs change in response to an experiment performed under the Record of 

Decision, unanticipated event, or other management action? 

EIN 8.4.1 How does fine sediment abundance, grain-size, and distribution, within eddies 

between 5,000 to 25,000 cfs change in response to an experiment performed under the 

Record of Decision, unanticipated event, or other management action? 

RIN 8.5.1 What elements of Record of Decision operations (upramp, downramp, 

maximum and minimum flow, MLFF, HMF, and BHBF) are most/least critical to 

conserving new fine-sediment inputs, and stabilizing sediment deposits above the 25,000 

cfs stage? 

RIN 7.3.1 Develop simulation models for Lake Powell and the Colorado River to predict 

water quality conditions under various operating scenarios, supplant monitoring efforts, 

and elucidate understanding of the effects of dam operations, climate, and basin 

hydrology on Colorado River water quality. 
26

Products/Reports 

One or more peer-reviewed journal article(s) or USGS report(s) will be produced during a 12 to 

24 month period following the a future BHBF test on findings from this study. 

Costs by Year (specific fiscal years are not shown here, although FY 2007 costs are used 

for cost estimating purposes) 

FUNDING PROPOSAL 

Experimental Study 1.B: Studies of eddy-sandbar hydrodynamics, sediment transport, and 

bathymetry during a future BHBF test (Sandbar Deposition Rates) 

 Year 1 Year 2 

GCMRC Personnel Costs (19.1% Burden) - - 

GCMRC Project Related Travel / Training (19.1% Burden) $1,000 $2,000 

GCMRC Operations / Supplies / Publishing (19.1% Burden) $11,000 $2,000 

GCMRC Equipment Purchase / Replacement (19.1% Burden) - - 

AMP Logistical Support (19.1% Burden) $17,000 - 

Outside GCMRC & Contract Science Labor (19.1%) - - 

Cooperative / Interagency Agreements (6.09% Burden) $52,820 $74,779 

Project Sub-total $81,820 $78,779 

DOI Customer Burden (Combined 6.09% and/or 19.1%) $8,756 $5,318 

Project Total (Gross) $90,576 $84,097 

Percent Outsourced (includes 50% logistical support) 75% 95%
27

Experimental Study 1.C: Response of sandbars and selected cultural 

sites to a future BHBF test 

Duration 

20 months 

Principal Investigators 

Joe Hazel, Matt Kaplinski, and Rod Parnell, Northern Arizona University; David Topping, U.S. 

Geological Survey BRD, Southwest Biological Science Center, Grand Canyon Monitoring and 

Research Center; David Rubin and Amy Draut, U.S. Geological Survey GD, Western Coastal 

and Marine Geology; and Jack Schmidt, Utah State University 

Geographic Scope 

Numerous fan-eddy complexes, with associated campsites, and selected cultural sites between 

river miles 0 and 226. 

Project Goal(s) 

The principal goal of this project is to determine whether a future BHBF test conducted under 

sediment-enriched conditions can be used to rebuild/maintain eddy sandbars and associated 

campsites in the Colorado River ecosystem. This goal is to be achieved during a future BHBF 

test through: (1) evaluation of whether sandbars throughout the Colorado River ecosystem gain 

or lose sand above and below the stage associated with a discharge of 8,000 cfs and (2) 

comparison of the topographic response of sandbars with those observed during two previous 

BHBF tests conducted in 1996 and 2004. Secondary objectives of this project include further 

evaluation of whether: (1) sediment deposited in arroyo mouths can offset/reduce gully erosion 

(Yeatts, 1996) and (2) enlarged sandbars produced during the next BHBF test result in increased 

aeolian transport of sand upslope into archaeological sites, thereby offsetting/reducing wind 

deflation and rill erosion of sediment in and around these sites (Draut and Rubin, 2006). 

Need for Project 

This project is required to document whether a future BHBF test conducted under sedimentenriched conditions can be used to rebuild/maintain eddy sandbars, and associated campsites and 

add sand to archaeological sites in the Colorado River ecosystem. 

Strategic Science Question(s) 

4.1 Is there a “Flow-Only” operation (i.e. a strategy for dam releases, including 

managing tributary inputs with BHBFs, without sediment augmentation) that will rebuild 

and maintain sandbar habitats over decadal time scales? 

4.1a What are the short-term responses of sandbars to BHBFs? 

4.1b What is the rate of change in eddy storage (erosion) during time intervals between 

BHBFs? 
28

2.1 Do dam controlled flows increase or decrease rates of erosion at archaeological sites 

and TCP sites, and if so, how? 

2.3 If flows contribute to archaeological site/TCP erosion, what are the optimal flows for 

minimizing impacts to these cultural resources? 

3.9 How do varying flows positively or negatively affect campsite attributes that are 

important to visitor experience? 

Working Hypotheses 

A future BHBF test conducted under magnitudes and longitudinal distributions of sand 

enrichment similar to those before the 2004 BHBF test will result in sandbar rebuilding and lowelevation gully infilling comparable to that observed during the 2004 BHBF test. If reaches 

downstream from river mile 30 are sand enriched relative to their condition before the 2004 

BHBF test, then sandbar building and gully infilling in these downstream reaches will be greater 

than was observed in these reaches during the 2004 BHBF test. In addition, if the sandbars 

produced during a future BHBF test are (1) larger during the subsequent spring windy season 

than in the spring windy season preceding the next BHBF test and are (2) dry during the spring 

windy season following the next BHBF test, then the aeolian flux of sand derived from these 

sandbars will be greater than it was before this test (as observed by Draut and Rubin, 2006). 

Methods 

This project will collect and analyze topographic, bathymetric, sedimentologic (grain size), 

campable area, meteorological, geomorphic, and aeolian sand-transport data at fan-eddy 

complexes and selected cultural sites. Analyses similar to those described in Rubin and others 

(1998), Hazel and others (1999, 2006), Schmidt and others (1999b), Topping and others (1999, 

2006a), and Draut and Rubin (2005, 2006, 2007) of sandbar topographic response, sandbar 

stratigraphy, grain-size data, aeolian sand-transport data, and aeolian topographic response at 

cultural sites will be used to evaluate the results of a future BHBF test relative to the two 

previous BHBF tests conducted in 1996 and 2004. If the working hypotheses are supported by 

these analyses, then rebuilding and maintenance of sandbars might be possible through release of 

additional BHBF tests that are also implemented under sand-enriched conditions. Furthermore, if 

the working hypothesis specific to the aeolian sand-transport component of this project is 

supported by these analyses, preservation of certain archaeological sites might be increased 

through a strategy of repeated BHBF tests in the future under sand-enriched conditions. If the 

working hypotheses are rejected by these analyses, then additional flow and non-flow treatments 

(i.e., further constraints on dam operations, sediment augmentation, or a combination of both) in 

association with any future BHBF testing may be needed to rebuild and maintain sandbars 

throughout the Colorado River ecosystem. 

Geomorphic mapping, scour-chain installation, and associated interpretive work will be 

conducted using established methods by scientists from Utah State University (Schmidt and 

others, 1999). Topographic and multibeam bathymetric surveys will be collected before and after 

a future BHBF test using established methods by scientists from Northern Arizona University 

(Hazel and others, 1999, 2000, in review; Kaplinski and others, 2000, 2007, in review). These 

data will be collected at numerous fan-eddy complexes located throughout Marble and Grand 

Canyons and at selected cultural sites. Analog cameras will be used at 28 selected sandbars and 
29

cultural sites to document the topographic evolution (by fluvial and aeolian processes of these 

sites during and after a future BHBF test. River-based arroyos associated with selected cultural 

sites will also be surveyed as part of this study (See table 2 for locations of various project 

components.) 

Previous work has shown that the grain size of the underwater part of eddy-sandbar surfaces is 

the most important regulator of sand transport in the Colorado River over multiyear timescales 

(Topping and others, 2005) and that the coarsening of the channel bed and sandbar surfaces 

reduces the subsequent export of sand from the system (Rubin and others, 1998; Topping and 

others, 2007). Grain size on the riverbed and on sandbar surfaces will be studied using an 

underwater microscope (Chezar and Rubin, 2004; Rubin and others, 2006, 2007) and digital 

image processing (Rubin, 2004). Grain size in flood deposits on sandbars will be measured by 

sampling vertical profiles (Rubin and others, 1998) and using standard lab analyses. Sedimentary 

structures in flood deposits will be examined by installation and excavation of scour chains, by 

trenching, and by inspection of natural cut banks. 

Weather instrument stations will measure wind, rainfall, and aeolian sand transport at the 

targeted cultural sites listed below. These instruments were deployed during February and March 

2007, with the exception of the Malgosa site (river mile 57.9) and Basalt (river mile 70), where 

equipment would be deployed before a future BHBF test occurred. This part of this project will 

build on the findings of Draut and Rubin’s 2003–06 study on the role of aeolian sediment in the 

preservation of cultural sites (Draut and others, 2005; Draut and Rubin, 2005, 2006, 2007), 

specifically the finding from the 2004 BHBF test that high-flow releases in the CRE can increase 

wind-blown transport of sand toward some of the aeolian deposits that contain archaeological 

material, thereby increasing their preservation potential. 
30

Table 3. Locations of various project components for experimental study 1.C (* Individual study 

sites are associated with one or more archaeological sites. All river miles are generalized to 

protect the confidentiality of archaeological site locations). 

Day 

on 

river 

trip 

Sandbar 

topography, 

Campsite area, Scour 

chains 

Bathymetry, 

Underwater 

microscope 

Aeolian 

Sand 

transport 

work* 

Arroyo 

surveys* 

Cameras 

 0 -9 Mile 

 1 3L, 8L, 16L 3L, 16L 2.6R, 8.2R 

 2 22R, 24L, 29L, 30R 22R, 30R 24 16.7R,22.0L, 

24.5L 

 3 32R, 33L, 35L 32R, 35L 30.8L 

 4 41R, 43L, 44L 41R, 43L, 44L 41.3L,44.5R 

 5 45L, 47R, 50R, 51L 45L, 47R, 51L 47.6R, 50.1L 

 6 55R, 56R, 62R 55R, 62R 58, 60 55.9L, ~58L 

 7 65R, 68R 65R, 68R 66, 70 66L, 66R 

 8 70R,72R 70L, 72L 

 9 81L, 84R, 87L, 88R 81.7R,87.6R 

10 119R, 122R, 123R 122R 104.4L, 19.3L, 

123.2R 

11 137L, 139R, 145L 139R 135 137.7R, 145.8R 

12 172L, 183R 172L 172.6R, 183.3L 

13 194L, 202R 194L 194.6L, 202.3L 

14 213L, 220R, 225R 225R 203, 223 213.3R, 225.5L 

15 39 sandbars 22 eddies 29 camera sites 

Links/Relationships to Other Projects 

This integrated sediment project builds on the large quantity of previous published work on 

sediment erosion and deposition in the Colorado River ecosystem downstream from Glen 

Canyon Dam. It is also linked to several other experimental BHBF-related physical, 

sociocultural, and biological projects, including experimental study 1.A (Reach-scale changes in 

the fine-sediment mass balance and grain size during a future BHBF tests), experimental study 

1.B (Studies of eddy-sandbar hydrodynamics, sediment transport, and bathymetry during a future 

BHBF test), experimental study 2 (Evaluate effect of a future BHBF test on riparian plant 

community development at multiple surface elevations and depositional environments), and 

experimental study 3 (BHBF Testing effects on lower trophic levels in the Colorado River 

ecosystem). Bed sediment grain-size data collected as part of this project will be used to help 

interpret shifts through time in the sediment rating-curve data collected as part of experimental 

studies 1.A and 1.B and predicted by many modeling studies. Similarly, grain-size grading of 
31

flood deposits will be compared to temporal changes in suspended-sediment grain size observed 

during high flows (components of experimental studies 1.A and 1.B). 

The subsequent evolution of the post-BHBF backwaters surveyed as part of this project will be 

evaluated in the subsequent fall during the backwater seining trip. Extension of the 

aeolian/archaeological site study supplements ongoing weather monitoring, aeolian transport, 

and gully-erosion monitoring work. It also extends the applications of the Draut and others study 

on the role of aeolian sediment in the preservation of archaeological sites that collected similar 

data from 2003 to 2006, and therefore will provide valuable comparison data between the 2004 

and a future BHBF test. In addition, this study complements ongoing investigations by Joel 

Pederson and Gary O’Brian from Utah State University on geomorphic processes that affect 

gully incision in Colorado River sediment deposits. 

Information Needs Addressed 

The project will directly address multiple effects information needs and research information 

needs, as follows: 

EIN 8.3.1 How does fine sediment abundance, grain-size, and distribution, within eddies 

below 5,000 cfs change in response to an experiment performed under the Record of 

Decision, unanticipated event, or other management action? 

EIN 8.4.1 How does fine sediment abundance, grain-size, and distribution, within eddies 

between 5,000 to 25,000 cfs change in response to an experiment performed under the 

Record of Decision, unanticipated event, or other management action? 

EIN 8.5.1 How does fine sediment abundance, grain-size, and distribution on shorelines 

between 25,000 cfs and the uppermost effects of maximum dam releases change in 

response to an experiment performed under the Record of Decision, unanticipated event, 

or other management action? 

EIN 9.3.1 How do the size, quality, and distribution of camping beaches change in 

response to an experiment performed under the Record of Decision, unanticipated event, 

or other management action? 

EIN 11.1.1 Determine the effects of experimental flows on historic properties. 

RIN 8.5.1 What elements of Record of Decision operations (upramp, downramp, 

maximum and minimum flow, MLFF, HMF, and BHBF) are most/least critical to 

conserving new fine-sediment inputs and stabilizing sediment deposits above the 25,000 

cfs stage? 

RIN 8.5.4 What is the significance of aeolian processes in terrestrial sandbar reworking? 

RIN 11.1.1a What and where are the geomorphic processes that link loss of site integrity 

with dam operations as opposed to dam existence or natural processes? 

RIN 11.1.5 What are appropriate strategies to preserve resource integrity? 

Products/Reports 

Several peer-reviewed journal article(s) and/or USGS report(s) will be produced based on the 

findings of this study within 12 to 24 months of a future BHBF test. 
32

Costs by Year (specific fiscal years are not shown here, although FY 2007 costs are used for 

cost estimating purposes) 

FUNDING PROPOSAL 

Experimental Study 1.C: Responses of sandbars and selected cultural sites to a future BHBF test 

(Sandbar Fate: Topographic and Grain-size Responses) 

 Year 1 Year 2 

GCMRC Personnel Costs (19.1% Burden) - - 

GCMRC Project Related Travel / Training (19.1% Burden) 

$3,000 

 

$3,000 

GCMRC Operations / Supplies / Publishing (19.1% Burden) 

$9,500 

 

$5,000 

GCMRC Equipment Purchase / Replacement (19.1% Burden) 

$10,000 - 

AMP Logistical Support (19.1% Burden) 

$120,000 - 

Outside GCMRC & Contract Science Labor (19.1%) - - 

Cooperative / Interagency Agreements (6.09% Burden) 

$310,100 

 

$119,900 

Project Sub-total 

$452,600 

 

$127,900 

DOI Customer Burden (Combined 6.09% and/or 19.1%) 

$46,103 

 

$8,830 

Project Total (Gross) 

$498,703 

 

$136,730 

Percent Outsourced (includes 50% logistical support) 82% 94%
33

Experimental Study 2: Evaluate effect of a future BHBF test on riparian 

plant community development at multiple surface elevations and 

depositional environments: are open patches more susceptible to exotic 

species colonization and establishment than sites with existing 

vegetation following a disturbance? 

Duration 

24 months 

Principal Investigator 

Barbara Ralston, U.S. Geological Survey BRD, Southwest Biological Science Center, Grand 

Canyon Monitoring and Research Center 

Geographic Scope 

Glen Canyon Dam to lower Marble Canyon (river mile 61) 

Project Goal(s) 

The project goals are to document community compositional changes (native vs. nonnative 

species) in established and newly bare depositional environments across multiple surface 

elevations following a future BHBF test. The project goal addresses a subcomponent of a larger 

question posed in the knowledge assessment (Melis and others, 2006b): To what extent and in 

what respects can BHBF tests (magnitude and frequency) achieve reduction of exotic species? 

Need for Project 

Riparian areas are highly susceptible to exotic species introductions and expansions (Graf, 1978; 

Thébaud and Debussche, 1991; Naiman and others, 2005). Furthermore, the successful 

establishment of an invasive species may be affected by the degree to which a community is 

developed at a site. Two competing hypotheses exist regarding site susceptibility to invasive 

species. Darwin (1859), Elton (1958), Moulton and Pimm, (1983), Case (1990), and Case and 

Bolger (1991) suggest that invasion success decreases as community size and structural 

complexity increase. Stohlgren and others (1998, 1999) postulate the opposite hypothesis, 

arguing that species-rich sites, such as riparian zones, are more susceptible to exotic species 

introductions than upland areas that may have lower species richness. The latter argues for 

temporarily increased resource availability associated with disturbance, while the former argues 

that fewer exploitable habitats are available, thus preventing new species introductions 

(MacArthur and Wilson, 1967; Pimm, 1991). 

In human-impacted systems, determining the relationship between native and nonnative species 

richness and site susceptibility is important for long-term resource management. A high-flow 

event provides a unique opportunity to compare riparian vegetation community composition (i.e., 

native/nonnative ratios) in established vegetation sites subject to disturbance with large bare sites 
34

made available from sediment reworking during a future BHBF test. By comparing established 

and new bare sites at multiple surface elevations, scientists should be able to identify the sites 

that are most susceptible to nonnative species introductions and expansion. Identification of 

susceptible sites provides managers the opportunity to focus resources when considering 

nonnative species control measures following a large disturbance event. 

Strategic Science Question(s) 

4.1. Is there a flow-only operation (i.e., strategy for dam releases, including managing 

tributary inputs with BHBFs without sediment augmentation) that will rebuild and 

maintain sandbar habitats over decadal time scales? 

Working Hypotheses 

Hypothesis 1: Native/nonnative species richness ratios are the same across all habitats and 

surface elevations up to 60,000 csf. 

Alternative hypothesis: The ratio between native/nonnative richness and cover at sites with 

established vegetative communities will not change following disturbance because resource 

availability is limited by the presence of existing species. Bare areas will have ratios of 

native/nonnative richness and cover values similar to those of established sites. Surface elevation 

will not have an affect on native/nonnative richness and cover values. 

Alternative hypothesis: The ratio between native/nonnative richness and cover at sites with 

established vegetative communities will shift toward an increase in nonnative richness and cover 

because of the increased nutrient availability associated with the experimental BHBF 

disturbance. Native/nonnative richness and cover ratios will change by surface elevation with 

nonnative species decreasing with increasing surface elevations in relation to available soil 

nutrients. Bare areas will favor nonnative species across all surface elevations. 

Methods 

Plots established by Kearsley (2006) as a part of riparian vegetation monitoring will be used to 

assess native/nonnative foliar cover. These plots occur at specific river miles (table 4) and 

include data collected from 2001 to 2005. Reassessment of these locations provides an 

opportunity to examine native/nonnative cover and richness ratios across years and relative to a 

large scale disturbance within a year. These plots are also linked to the following surface 

elevations: 8,000, 15,000, 25,000, 35,000, 45,000, and 60,000 cfs. At each location, surveys of 

foliar cover of all species found with four 1 m2 plots located at each surface elevation will be 

recorded. Many of these sites occur in channel margin locations and will likely experience some 

disturbance but would be unlikely to be completely bare following a future BHBF test. 

Percent foliar cover will be determined by using 10 cm grids on 1m frames. Field readers will 

count the number of cross-sectional grid points that coincide with the presence of a given 

species. This is more accurate than field crews estimating percent cover visually. All species 

encountered in a plot will be recorded and those species that have <1% cover will be identified 

as a trace and assigned a value of 0.01. All sites will be visited before a future BHBF test as a 

part of monitoring. Sampling following a future BHBF test will take place in association with 
35

post-flood sandbar monitoring trips, which will occur in mid-summer at the height of plant 

productivity, in the fall in association with regular monitoring, and 1 year following a future 

BHBF test. 

Bare ground sites: Similarly sized plots will be established in newly identified depositional 

environments (e.g., sandbars, return current channels). In most cases, these bare ground sites will 

be the same sites that are identified in experimental study 1.C. Established vegetation plots that 

are close to sandbar survey beaches will be surveyed. Surface elevations will be determined for 

these sites, and data collection will follow that of the established vegetation sites. 

Soil collection: To determine how soil constituents and grain size affect species composition, 

soil samples will be collected at each site and analyzed for available nitrogen, total carbon, and 

particle size. Four soil samples will be taken at each site and at each surface elevation. One 

sample will be taken from the midpoint of each 1 m2

 plot. The sample will be external of the 

plots so as not to disturb the plots. Standing litter will be removed before sampling and sample 

depths will be at least 15 cm. A soil sampler will be used to collect the soil cores. Samples will 

be combined into a single soil sample for each surface elevation per site. Analysis will be 

conducted by an external lab, which is to be determined. Samples will be collected before and 

after a future BHBF test at the established vegetation plots to determine if soil constituents and 

grain sized changed as a result of the BHBF test. 

Analysis: Species cover data from each surface elevation will be pooled to determine total cover 

and richness, as well as richness and cover values for native and nonnative species. 

Native/nonnative values will be compared using a one-way analysis of variance (ANOVA) Ftest. Established and bare ground sites will be compared using Multiple Response Permutation 

Procedures (MRPP) (McCune and Grace, 2002). MRPP is a nonparametric test for the 

hypothesis of no difference between two or more groups; in this case, richness and cover would 

be compared between bare ground and vegetated sites before and after a BHBF. Indicator species 

analysis would also be used to describe which species might distinguish each group, if 

differences exist and, more importantly, identify which species in bare plots may be more 

successful as invaders. Stepwise regression will be used with soil data to determine the effect of 

soil constituents and particle size on native/nonnative cover and richness values. Comparisons 

using MRPP will also be made between sites located above and below the Little Colorado River 

to see how distance may affect compositional differences. 
36

Table 4. Established vegetation sites and corresponding experimental study 1.C sandbar sites 

by river mile (R=river right and L=river left) 

Establish vegetation sites and 

corresponding Study 1.C 

sandbar sites by river mile 

002.7L – 3L 

008.1L – 8L 

035.1L – 35L 

037.7R – 35L 

041.2R – 41R 

043.9L – 43L 

047.0L – 47R 

053.2R – 56R 

056.1R – 56R 

062.0L – 62R 

065.4R – 65R 

068.2R – 68R 

119.9L – 119R 

121.1R – 122R 

122.8L – 123R 

132.8L – 137L 

139.1R – 139R 

143.5R – 145L 

171.5L – 172L 

182.7L – 183R 

193.3R – 194L 

202.3L – 202R 

220.1R – 220R 

Links/Relationships to Other Projects 

This project augments general riparian vegetation monitoring because it incorporates existing 

monitoring locations into data collection efforts. By using surface elevations as site location 

criteria, the project also links species richness and cover to operational effects on riparian 

vegetation across surface elevations. In terms of integrating research across resources, this 

project will produce data that supports experimental study 1.C (Response of sandbars and 

selected culture sites to future BHBF tests) by sampling reworked and bare sandbars and return 

current channel substrates, collecting and analyzing soil samples for grain-size information, and 

identifying plant species components in marsh and riparian habitats. The locations for sampling 

are associated with those sites designated for research associated with sandbar topography, 

campsite area, and scour chains (experimental study 1.C). It also will helps to answer a cultural 

research information need 11.2.3 (Determine acceptable methods to preserve or treat 

traditionally important resources within the Colorado River ecosystem) by providing data 

relevant for improving our understanding of how BHBF tests may affect culturally important 

native plant species composition and distributions relative to invasive nonnative species. 

Information Needs Addressed 

This project directly addresses and experimental information need for M.O. 6.5 associated with 

riparian vegetation. 
37

EIN 6.5.1 How does the abundance and distribution of nonnative species change in 

response to an experiment performed under the Record of Decision, unanticipated event, 

or other management action? 

Costs by Year (specific fiscal years are not shown here, although FY 2007 costs are used 

for cost estimating purposes) 

FUNDING PROPOSAL 

Experimental Study 2: Evaluate effect of future BHBF tests on riparian plant community 

development at multiple surface elevations and depositional environments: are open patches 

more susceptible to exotic species colonization and establishment than sites with existing 

vegetation following a disturbance? (Riparian Vegetation Studies) 

 Year 1 Year 2 

GCMRC Personnel Costs (19.1% Burden) - - 

GCMRC Project Related Travel / Training (19.1% Burden) $3,000 $3,000 

GCMRC Operations / Supplies / Publishing (19.1% Burden) $10,036 $500 

GCMRC Equipment Purchase / Replacement (19.1% Burden) - - 

AMP Logistical Support (19.1% Burden) $8,000 $8,000 

Outside GCMRC & Contract Science Labor (19.1%) - - 

Cooperative / Interagency Agreements (6.09% Burden) $15,800 $16,000 

Project Sub-total $36,836 $27,500 

DOI Customer Burden (Combined 6.09% and/or 19.1%) $4,980 $3,171 

Project Total (Gross) $41,816 $30,671 

Percent Outsourced (includes 50% logistical support) 54% 73%
38

Experimental Study 3: BHBF testing effects on lower trophic levels in 

the Colorado River Ecosystem 

Duration 

19 months 

Principal Investigators 

Theodore Kennedy, U.S. Geological Survey BRD, Southwest Biological Science Center, Grand 

Canyon Monitoring and Research Center; Wyatt Cross and Robert Hall, University of Wyoming; 

and Emma Rosi-Marshall, Loyola University 

Geographic Scope 

Glen Canyon, the confluence of the Little Colorado River, and Diamond Creek (river miles -15 

to 226) 

Project Goal(s) 

To measure how a future BHBF test affects the quantity, quality, and types of food available for 

invertebrates, and ultimately fish 

Need for Project 

Previous food base research has demonstrated that a BHBF test causes short-term reductions in 

primary producer and invertebrate biomass (Blinn and others, 1999; McKinney and others, 

1999). Blinn and others (1999) and McKinney and others (1999) focused on static measures (i.e., 

algal biomass, invertebrate biomass) at a relatively coarse temporal scale (i.e., monthly 

measurements following a BHBF test). Although biomass of algae and invertebrates will be 

temporarily reduced following a BHBF test, it is possible the post-BHBF algal assemblage will 

be faster growing and of higher quality, leading to higher invertebrate growth rates (Note: 

production=biomass*growth). Higher invertebrate growth rates post-BHBF tests could 

compensate for short-term reductions in invertebrate biomass. That is, short-term (i.e., weeks) 

negative effects of a future BHBF test on biomass may be offset by longer term (i.e., months to 

year) increases in invertebrate growth rates, which would result in more food available to higher 

trophic levels. 

A future BHBF test is likely to alter the systemwide carbon budget that we are currently 

constructing. Consequently, we will quantify fluxes of transported organic matter before, during, 

and after the future BHBF experiment. Although these types of measurements have been taken 

during previous BHBF tests, none of the data have been linked to whole-system carbon budgets. 

This information will be critical for ultimately measuring the effect of a future BHBF test on 

inputs, retention, and export of organic matter that fuels river food webs. 

There is evidence that disturbances, such as those that might occur during future a BHBF test, 

lead to an algal assemblage that is dominated by fast-growing and nutritious taxa. Brock and 

others (1999) measured production of algae covered rocks in Glen Canyon before and after the 
39

1996 BHBF test. They demonstrated that rates of net primary production and production to 

respiration ratios were both higher after the BHBF test; although, algal biomass on rocks was 

lower following the BHBF test. They attributed these changes to the removal of detritus and 

senescent algal biomass. Because rapidly growing and young algae are more nutritious than 

senescent algae or detritus, the study by Brock and others (1999) suggests that the post-BHBF 

algal assemblage was of higher quality for invertebrates than the pre-BHBF algal community. 

Numerous studies in Sycamore Creek, a desert stream in southern Arizona, have demonstrated 

that following a scouring flood the algal assemblage shifts towards more nutritious and faster 

growing taxa (i.e., diatoms), invertebrates readily consume these new food resources, and that 

invertebrate biomass rapidly recovers to pre-flood levels (Fisher and others, 1982; Grimm and 

Fisher, 1989; Peterson and others, 1994). 

Working Hypotheses 

Hypothesis 1: A short-duration BHBF test in late winter scours the benthos, causing short-term 

reductions in algal and invertebrate biomass, and results in an overall decrease in annual 

invertebrate production (see fig. 3.1). 

Hypothesis 2: A short-duration BHBF test in late winter scours the benthos, causing reductions 

in algal biomass, but the new successional community of primary producers is of higher quality, 

more productive, and is assimilated more efficiently by invertebrates, leading to no change in 

annual invertebrate production. 

Hypothesis 3: A short-duration BHBF test in late winter initially scours the benthos, causing 

reductions in algal biomass, but the new successional assemblage of primary producers is of 

higher quality, more productive, and is assimilated more efficiently by invertebrate consumers, 

thereby increasing annual invertebrate production (see fig. 3.1). 

Our research will test these competing hypotheses of recovery following a BHBF test. Direct 

measurements of invertebrate and fish growth before and after BHBF testing is intractable. 

However, we may be able to infer how invertebrate or fish growth rates are affected by future 

BHBF tests by measuring indices of growth (ribosomal RNA; Elser and others, 2003) and by 

quantifying invertebrate and fish diets and using literature values to determine the assimilation 

efficiencies of principal food resources. We will also measure whether a BHBF test changes the 

quality (i.e., C:N, C:P) of algal assemblages. Collectively, the proposed research will measure 

how a BHBF test affects the quantity and quality of food available for fishes and whether 

indicators of rainbow trout growth are affected by changes in food resources. 
40

Figure 3. Potential effects of a BHBF test on invertebrate production.

Methods 

We will measure biomass of lower trophic levels (i.e., algal and invertebrate biomass, cover and 

canopy height of submerged aquatic vegetation, organic drift) coupled with dynamic process 

oriented measures (i.e., nutrient content of basal resources, ribosomal RNA of invertebrates and 

fish, open-channel metabolism measurements) to test how a BHBF test affects annual 

invertebrate production. Methods described briefly below are presented in more detail in our 

original food base proposal (Hall and others, 2005). 

We will sample algae, submerged aquatic vegetation, and benthic organic matter with 

appropriate area-specific sampling devices (e.g., Ponar and Hess samplers, rock scrapes, 

modified suction sampler); dried to a constant mass, weighed, ashed in a muffle furnace (at 

450°C); and reweighed to determine total dry mass and organic mass. Dried samples of these 

food base components will also be analyzed for carbon, nitrogen, and phosphorus content 

following standard methodology (CHN analyzer, acid digestion and spectrophotometry, APHA 

1998). Open-channel metabolism in the Glen Canyon reach will be quantified before and after 

the BHBF with continuously deployed Yellow Springs Instruments (YSI) data sondes (with 
41

optical probes) using a two-station diel oxygen change method, corrected for re-aeration (e.g., 

Hall and Tank, 2003; Hall and others, 2005). Downstream in Grand Canyon, we will measure 

metabolism using a one-station technique as part of the food base project (Hall and others, 

unpublished). Metabolism will be measured continuously at Diamond Creek for a period of a 

week before, and several months after, a BHBF test. At the Little Colorado River, metabolism 

will be measured continuously for 1 week before, and 2 weeks after, a future BHBF test. Coarse 

and fine organic drift will be quantified using depth-integrated Miller net and grab samples 

respectively before, during, and after a future BHBF test at each site. Invertebrates will be 

quantified on multiple substrate types (i.e., cliff faces, talus slopes, cobble bars, depositional 

areas) with appropriate area-specific sampling devices (e.g., modified suction sampler, rock 

grabs, Hess sampler, ponar dredge). Dietary analysis will be conducted on invertebrates before 

and on multiple occasions after (days 1, 3, 7, 14, 30) a BHBF test using digital imaging software 

(Image Pro 3.0). Dominant dietary items can be easily identified with this method (e.g., diatoms, 

amorphous detritus, leaves, animal prey; Benke and Wallace, 1980; Hall and others, 2000). 

Ribosomal RNA analysis will be conducted on dominant invertebrates and fishes as a proxy for 

growth rate and condition (Elser and others, 2003). 

Tasks 

1. Measure how a BHBF test alters the carbon budget for the CRE. 

• Measure the composition, biomass, and nutrient content of basal resources (algae, 

submerged aquatic vegetation, benthic organic matter) 

• Quantify whole system metabolism, a measure of primary production and resource 

consumption 

• Prior to BHBF, quantify standing mass of leaf litter between 20-41k cfs stage elevation 

• Measure organic drift during BHBF 

2. Measure how a BHBF test affects invertebrate biomass and production 

• Quantify invertebrate composition, abundance, and biomass 

• Quantify invertebrate diets and growth indicators (i.e., ribosomal RNA) 

3. Measure impact of a BHBF test on growth and condition indices (i.e., ribosomal RNA) for 

rainbow trout in Lees Ferry (in collaboration with Korman and others) 

We will compare the above measures before and after a future BHBF test, and again in the 

following year at the same time when no BHBF test occurs. Frequent measurements before and 

after a BHBF test (i.e., -7d, -1d, +1d, +3d, +7d, +14d), coupled with ongoing quarterly sampling 

at the Little Colorado River confluence and monthly sampling at Glen Canyon and Diamond 

Creek, will allow us to measure the short- and long-term effects of a BHBF test on food quantity 

and quality. 

Links/Relationships to Other Projects 

This project is linked to experimental study 1.B (Studies of eddy-sandbar hydrodynamics, 

sediment transport, and bathymetry during future a BHBF test). We will share transported 
42

sediment samples and analyze them for both sediment and organic matter and determine what 

affect a BHBF test has on organic matter transport. 

Strategic Science Question(s) 

Experimental effects information needs (EIN) addressed by the proposed research include: 

EIN 1.1.1 How does primary productivity for the reach between Glen Canyon Dam and 

the Paria River change in response to an experiment performed under the Record of 

Decision, unanticipated event, or other management action? 

EIN 1.2.1 How do benthic invertebrates in the reach between Glen Canyon Dam and the 

Paria River change in response to an experiment performed under the Record of 

Decision, unanticipated event, or other management action? 

EIN 1.3.1 How does primary productivity in the Colorado River ecosystem below the 

Paria River change in response to an experiment performed under the Record of 

Decision, unanticipated event, or other management action? 

EIN 1.4.1 How do benthic invertebrates in the Colorado River ecosystem below the 

Paria River change in response to an experiment performed under the Record of 

Decision, unanticipated event, or other management action? 

EIN 1.5.1 How does drift in the Colorado River ecosystem change in response to an 

experiment performed under the Record of Decision, unanticipated event, or other 

management action? 

Costs by Year (specific fiscal years are not shown here, although FY 2007 costs are used 

for cost estimating purposes) 

FUNDING PROPOSAL 

Experimental Study 3.: BHBF testing effects on lower trophic levels in the Colorado River 

Ecosystem 

 Year 1 Year 2 

GCMRC Personnel Costs (19.1% Burden) - - 

GCMRC Project Related Travel / Training (19.1% Burden) $2,000 - 

GCMRC Operations / Supplies / Publishing (19.1% Burden) $13,500 - 

GCMRC Equipment Purchase / Replacement (19.1% Burden) $25,000 $5,000 

AMP Logistical Support (19.1% Burden) $23,800 - 

Outside GCMRC & Contract Science Labor (19.1%) - - 

Cooperative / Interagency Agreements (6.09% Burden) $66,000 - 

Project Sub-total $130,300 $5,000 

DOI Customer Burden (Combined 6.09% and/or 19.1%) $16,301 $955 

Project Total (Gross) $146,601 $5,955 

Percent Outsourced (includes 50% logistical support) 60% 0%
43

Experimental Study 4.A: Effects of future BHBF tests on rainbow trout 

early life stage survival, and the distribution, mortality, and potential 

downstream movement of age-1 fish in the Lees Ferry reach

Duration 

10 months 

Principal Investigator 

J. Korman, Ecometric, Inc., Vancover, BC Canada (GCMRC cooperator) 

Geographic Scope 

Glen Canyon Dam to Lees Ferry (river miles -15 to 0) 

Project Goal(s) 

This project seeks to determine how a future BHBF test affects spawning, survival of early life 

history stages of rainbow trout in the Lees Ferry reach, and potential for stimulating downstream 

migration of age-1 fish. Hypotheses that will be evaluated are: (1) a future BHBF test will scour 

redds (spawning nests) but the effect on the juvenile population will be limited because of 

compensatory survival responses, and (2) a BHBF test will alter the distribution of age-1 fish in 

the Lees Ferry reach resulting in either higher mortality or migration out of the reach. 

Need for Project 

The size of the adult population of rainbow trout in the Lees Ferry reach is very likely regulated 

by the survival rate and dynamics of early life stages (Houde, 1987). This experimental BHBF 

project would increase our understanding of these dynamics and therefore contribute to better 

management of the Lees Ferry trout fishery. Trout from Lees Ferry may migrate downstream and 

have negative effects on native fish (Korman and others, 2005; L. Coggins, unpublished data). 

The extent of downstream migration may be density dependent (Close and Anderson, 1992), a 

normal ontogenetic habitat shift (Elliott, 1986), and/or stimulated by high flows (Heggenes and 

Traaen, 1988; Jensen and Johnsen, 1999; Mitro and others, 2003). A better understanding of the 

dynamics of the Lees Ferry population and the effects of a BHBF test therefore has implications 

for the control of trout densities downstream. 

Strategic Science Question(s) 

To what extent could predation impacts by nonnative fish be mitigated by higher 

turbidities or dam controlled high-flow releases? 

To what extent is the adult population of rainbow trout controlled by survival rates during 

incubation and age-0/juvenile rearing stages, or by changes in growth and maturation in 

the adult population influencing egg deposition? 

Do rainbow trout immigrate from Glen to Marble and eastern Grand Canyons, and if so, 

during what life stages? 
44

Working Hypotheses 

We predict that: (1) redd numbers will be reduced by a future BHBF test because of scour; (2) 

the ratio of fry to redds will be similar to other years (2006=Record of Decision flows, 

2003/4=experimental flows) because of strong compensatory mechanisms that occur shortly after 

emergence (Elliott, 1994); and (3) distribution of age-1 fish in Lees Ferry fish will be different 

after the BHBF because there will be a reduction in abundance owing to mortality or 

downstream movement (Korman and others, 2005; L. Coggins, GCMRC, unpublished data). To 

evaluate these hypotheses we will compare: (1) the number of redds before and after the BHBF 

test to compute the potential loss of redds because of high flows; (2) the ratio of the density of 

newly emerged fry to the total number of redds constructed with ratios determined in 2003, 

2004, and 2006 (Korman and others, 2005); and (3) compare the abundance and distribution of 

age-1 fish before and after the BHBF test. It may be possible to determine whether mortality or 

movement was the cause for change in abundance, when age-1 fish are tagged as part of the 

GCMRC sonic telemetry program (experimental study 4.B). 

Methods 

The existing 2007 budget for the Rainbow Trout Early Life Stage Survival (RTELSS) project 

supports five redd surveys and one age-0 survey, a substantial reduction in effort from previous 

years because of funding constraints (Korman and others, 2005). The proposed BHBF test 

component would require: (1) five additional redd surveys to provide a more accurate and 

detailed estimate of redd numbers and timing of spawning; (2) three additional juvenile fish 

surveys to compute the age-0 to redd ratio (July sample) and to describe the change in abundance 

and distribution of age-1 fish (before and after BHBF sample); (3) support for physical modeling 

to develop a depth and velocity map for a range of discharges for the entire Lees Ferry reach. 

The currently supported juvenile fish survey is scheduled to occur in the late fall and provides an 

annual index of age-0 abundance (altering the timing of this survey disrupts the time series). 

With regards to item (3) above, as fish grow they use deeper and faster habitats (Gaudin, 2001). 

Current age-0 surveys have been restricted to generally quite slow water (but sometimes deep) 

that is broadly distributed along the shoreline in the Lees Ferry reach. However, larger age-0 fish 

and age-1 fish appear to concentrate in the limited number of shorelines with faster water where 

food availability is higher (Korman and Yard, unpublished data). We need to sample these 

habitat types in order to provide a representative description of how high flows change 

abundance and distribution. The physical model would allow us to design a representative 

sampling regime for age-1 fish and scale-up density samples to estimate age-1 population size 

before and after a BHBF. Predictions of depth and velocity in Lees Ferry reach would also be 

useful for assessing redd scour, which we will evaluate in the field by before-after mapping of 

redds as part of our regular survey, and burial of existing spawning areas with sand (as 

apparently occurred at 6 and 8 mile sandbars as a result of the 1996 BHBF test). Data collected 

from past RTELSS efforts, and a complete topographical map of the Lees Ferry reach developed 

by the GCMRC would be integrated in an existing 2D hydrodynamic modeling framework 

developed by the USGS. 
45

Links/Relationships to Other Projects 

It is important to determine how the food web dynamics influence the density and growth of 

rainbow trout in the Lees Ferry reach. Downstream migration of trout from the Lees Ferry reach 

resulting from a BHBF test will be studied by the GCMRC. Trout captured as part of the 

proposed study will be used as part of GCMRC’s downstream movement assessment (see 

experimental study 4.B). These data will be very useful for interpreting downstream 

movement/mortality. 

Information Needs Addressed 

RIN 4.2.7 What dam release patterns most effectively maintain the Lees Ferry rainbow 

trout trophy fishery while limiting rainbow trout survival below the Paria River? 

Costs by Year (specific fiscal years are not shown here, although FY 2007 costs are used 

for cost estimating purposes) 

FUNDING PROPOSAL 

Experimental Study 4.A: Effects of future BHBF tests on rainbow trout early life stage survival, 

and the distribution, mortality and potential downstream movement of age-1 fish in the Lees Ferry 

reach (Rainbow Trout Studies - Early Stages) 

 Year 1 Year 2 

GCMRC Personnel Costs (19.1% Burden) - - 

GCMRC Project Related Travel / Training (19.1% Burden) - - 

GCMRC Operations / Supplies / Publications (19.1% Burden) $3,000 - 

GCMRC Equipment Purchase / Replacement (19.1% Burden) - - 

AMP Logistical Support (19.1% Burden) $2,000 - 

Outside GCMRC & Contract Science Labor (19.1%) - - 

Cooperative / Interagency Agreements (6.09% Burden) $35,000 - 

Project Sub-total $40,000 - 

DOI Customer Burden (Combined 6.09% and/or 19.1%) $3,087 - 

Project Total (Gross) $43,087 - 

Percent Outsourced (includes 50% logistical support) 90% 0%
46

Experimental Study 4.B: Evaluate effects of a future BHBF test on adult 

rainbow trout distribution in Glen and Marble Canyons 

Duration 

19 months

Principal Investigator 

M.E. Andersen, U.S. Geological Survey, Grand Canyon Monitoring and Research Center 

Geographic Scope 

Glen and Marble Canyons (river miles -15 to 61) 

Project Goal(s) 

The goals of this experimental study are: (1) to determine if a BHBF test causes displacement of 

rainbow trout approximately 108 mm total length and larger from the Lees Ferry reach into 

Marble Canyon and eastern Grand Canyon; (2) to determine if such displacement is experienced 

differentially among different length fish; and (3) to provide a platform for Grand Canyon 

scientists to develop skills with acoustic technologies that can be applied to answering questions 

about native and nonnative fish movement and distribution and sampling efficiencies. 

Need for Project 

Native fishes of the Colorado River evolved in a system with a seasonally variable hydrograph, 

with winter base flows as low as ~1,000 cfs and annual spring floods routinely exceeding 

100,000 cfs, and with other large floods often occurring during the summer and early fall 

(Topping and others, 2003). Although a BHBF of ~40,000 cfs would likely not disadvantage 

these native species, it is commonly observed in other systems that a naturally flashy hydrograph 

can disadvantage nonnative species (Meffe, 1984). It is currently unclear whether a moderate 

high-flow event of ~40,000 cfs could affect the nonnative fish community of the Colorado River 

and provide a management tool. During the BHBF test of 1996, Valdez and Cowdell (1996) 

observed an increase in catch rates of rainbow trout <152 mm total length in the Little Colorado 

River inflow reach of the Colorado River. They hypothesized that displacement of fish from 

Lees Ferry and Glen Canyon into Grand Canyon by the BHBF test was likely responsible for 

these increased catch rates. They did not, however, observe any changes in the catch rates of 

other species of the nonnative fish community. After the 2004 BHBF test, Korman (pers. com.) 

observed a decrease in the catch rates of juvenile trout in Lees Ferry, which supports the Valdez 

and Cowdell (1996) hypothesis of displacement in 1996 but, again, direct observation of the fate 

of fish could not be made. Currently, we do not know if short-duration BHBF tests displace 

young trout from Lees Ferry and cannot infer this from experiments using abundance indices 

alone. This experimental study would employ the additional technology of acoustic telemetry to 

make direct observations of movement patterns of rainbow trout greater than approximately 108 

mm total length during a future BHBF test. This information in combination with relativeabundance measures will allow for stronger inference to be drawn about the fate of rainbow trout 
47

greater than approximately 108 mm total length during a future BHBF test. This experimental 

study also provides an opportunity for scientists to gain skills and experience with acoustic 

technologies that may prove important for addressing broader questions about Lees Ferry trout 

dispersal, movement dynamics, and sampling efficiency of other native and nonnative fish 

species in the Grand Canyon. Information and experience gained in this study is potentially 

useful in evaluating and structuring future telemetry-based observations of native fishes dispersal 

associated with a BHBF in downstream sections (e.g., near the Little Colorado River confluence) 

of the Colorado River. 

Strategic Science Question(s) 

1.3 Do rainbow trout immigrate from Glen to Marble and eastern Grand Canyons, and, if 

so, during what life stages? 

1.4 Can long-term decreases in the abundance of rainbow trout in Marble and eastern 

Grand canyons be sustained with a reduced level of effort of mechanical removal or will 

recolonization from tributaries and from downstream and upstream of the removal reach 

require that mechanical removal be an ongoing management action? 

3.2 To what extent could predation impacts by nonnative fish be mitigated by higher 

turbidity or dam-controlled high-flow releases? 

Working Hypotheses 

A future BHBF test will result in displacement of young rainbow trout from the Lees Ferry reach 

into Marble Canyon and eastern Grand Canyon. This trout redistribution will be inversely related 

to the size of fish. 

Methods 

This experimental study will use abundance indices and sonic technologies to evaluate the 

possible age-specific displacement of rainbow trout larger than approximately 108 mm total 

length from the Lees Ferry reach during a future BHBF test. Abundance indices will be 

established for adult and juvenile rainbow trout before and after the BHBF test for comparison. 

Before the BHBF, the GCMRC will execute a trout sampling trip following the protocol 

developed by the Arizona Game and Fish Department (AZGFD) for long-term monitoring of 

adult trout in Lees Ferry (Speas and others, 2002). The post-BHBF evaluation of adult trout 

abundance will include the use of AZGFD catch-rate information from reoccurring long-term 

rainbow trout monitoring in the Lees Ferry reach. Additional electrofishing catch-rate 

information collected by Ecometric, Inc. (experimental study 4.A) will be used for abundance 

comparisons of pre- and post-BHBF juvenile trout abundance. In combination, these catch data 

will be used to infer changes in the abundance of adult and juvenile rainbow trout associated 

with a future BHBF test. 

Relative-abundance indices will be combined with direct observations of location and movement 

from acoustic telemetry to draw inferences about the effects of a future BHBF test on the Lees 

Ferry trout population. The Colorado River upstream of Lees Ferry will be divided into three 

strata: upper (river mile -15 to -10), middle (river mile -10 to -5), and lower (river mile -5 to 0). 

Ten fish of age 1, 2, and 3 will be collected from each strata and tagged via intraperitoneal 
48

implantation for a total sample size of 90 implanted individuals. The minimum size fish 

implanted with a transmitter will be 108 mm total length. With the appropriate acoustic 

transmitter, this represents a tag to fish body weight ratio of 12%, which has been demonstrated 

to have little to no affect on swim performance of juvenile hatchery-reared rainbow trout (Brown 

and others, 1999). Tagged fish will be held in net pens for 24 hours to allow recovery from 

surgeries. Recovery of all fish will be evaluated and individuals recovering poorly will be 

removed from the experiment. Fish will be released in their river stratum of origin. Released fish 

will be manually tracked daily for 1week to evaluate movement patterns and longer term 

response to surgeries. We expect to observe a dispersal pattern after release that stabilizes over 

the period of tracking. Movement downstream of Lees Ferry will be detected with five acoustic 

receiver gates. These will be deployed at Lees Ferry, Marble Canyon Bridge, Badger Creek, river 

mile 30, and river mile 60. Fish in the Lees Ferry reach will then be tracked for an additional 3 

days to assure data accuracy of the stationary receiver gates. A post-BHBF electrofishing 

sampling protocol will be employed 1 week after the BHBF test to detect changes in the relative 

abundance of trout in the Lees Ferry trout fishery. 

Caveats on expected study findings: To clarify how this study will address the strategic science 

questions listed above and the information needs listed below, note that this study will not 

answer all questions associated with rainbow trout emigration from the Lees Ferry reach because 

it will only be observing movement of fish larger than approximately 108 mm TL. However, it 

will potentially provide insight into whether or not larger size classes of rainbow trout are 

vulnerable to BHBF related displacement. In addition, the study will provide insight into the 

vulnerability of rainbow trout larger than approximately 108 mm TL to displacement associated 

with a BHBF. This is information is clearly related to potential management actions that might 

be considered under strategic science questions 1.4 and 3.2. Additionally, this study will provide 

only a partial answer to RIN 4.2.1 (below) as the fish under study will be greater than 

approximately 108 mm total length and observed movement will be associated with a BHBF. 

Therefore, no direct information will be acquired on smaller sizes of rainbow trout nor associated 

with routine dam operations. This study will not determine the most effective way (RIN 4.2.2) to 

detect emigration of rainbow trout from the Lees Ferry reach. However, it will provide insight 

into how well a combination of catch-rate metrics and telemetry will perform for rainbow trout 

greater than approximately 108 mm total length. This study will only partially address RIN 4.2.3 

since it will be mainly focused on a specific hydrologic event (i.e., a BHBF) and the emigration 

rate of rainbow trout larger than approximately 108 mm total length. 

Links/Relationships to Other Projects 

This experimental study has direct linkage to experimental study 4.A, the long-term Lees Ferry 

trout monitoring effort, the FY 2007 sonic tag/gear efficiency evaluation, the FY 2007 

warmwater nonnative fish research, and future native fish research. Experimental studies 4.A and 

4.B are interrelated because of data and logistics sharing. Conducting these studies in concert 

will strengthen the inferences drawn from each about the fate of age-1 trout in the Lees Ferry 

reach as relates to a BHBF test. This study also relies on Lees Ferry long-term trout monitoring 

data collected by the AZGFD on relative abundance of adult trout in the Lees Ferry reach after a 

future BHBF test. Additionally, this study provides a platform for Grand Canyon scientists to 

gain valuable experience using sonic technologies to address a broader set of biological question. 

The experience gained from a future BHBF study will be employed in ongoing investigations of 
49

gear efficiencies and warmwater nonnative fish. These tools are also expected to be invaluable 

for future investigations of native fish in the Grand Canyon ecosystem. 

Information Needs Addressed 

The experimental study will generally address the following research information needs (RIN): 

RIN 4.2.1 What is the rate of emigration of rainbow trout from the Lees Ferry reach? 

RIN 4.2.2 What is the most effective method to detect emigration of rainbow trout from 

the Lees Ferry reach? 

RIN 4.2.3 How is the rate of emigration of rainbow trout from the Lees Ferry reach to 

below the Paria River affected by abundance, hydrology, temperature, and other 

ecosystem processes? 

Products/Reports 

A peer-reviewed journal article and/or USGS report will be produced based on the findings of 

this study. 

Costs by Year (specific fiscal years are not shown here, although FY 2007 costs are used 

for cost estimating purposes) 

FUNDING PROPOSAL 

Experimental Study 4.B: Evaluate effects of a future BHBF test on adult rainbow trout distribution 

in Glen and Marble Canyons (Rainbow Trout Studies - Adult Distribution) 

 Year 1 Year 2 

GCMRC Personnel Costs (19.1% Burden) $6,525 $3,875 

GCMRC Project Related Travel / Training (19.1% Burden) $1,575 - 

GCMRC Operations / Supplies / Publications (19.1% Burden) $42,185 $2,795 

GCMRC Equipment Purchase / Replacement (19.1% Burden) - - 

AMP Logistical Support (19.1% Burden) - - 

Outside GCMRC & Contract Science Labor (19.1%) - - 

Cooperative / Interagency Agreements (6.09% Burden) $10,000 $1,000 

Project Sub-total $60,285 $7,670 

DOI Customer Burden (Combined 6.09% and/or 19.1%) $10,213 $1,335 

Project Total (Gross) $70,498 $9,005 

Percent Outsourced (includes 50% logistical support) 17% 13%
50

Experimental Study 5: Evaluate effects of a future BHBF test on water 

quality of Lake Powell and Glen Canyon Dam releases 

Principal Investigator 

William S. Vernieu, U.S. Geological Survey, Southwest Biological Science Center, Grand 

Canyon Monitoring and Research Center 

Geographic Scope 

Lake Powell forebay to upstream limit of the hypolimnion (~Oak Canyon, 90 km above the 

dam), Glen Canyon Dam, and the tailwaters to Lees Ferry 

Project Goal(s) 

The goal of this experimental study is to determine how the addition of jet tube and full 

powerplant releases from the dam will alter water quality in the Glen Canyon Dam tailwaters and 

the hydrodynamics and stratification patterns in Lake Powell. This effort will entail installation 

of an additional water-quality multiparameter sonde (MPS) at the ring follower gates in the dam, 

the inlet port of the river outlet works, and may include another MPS located below Glen 

Canyon Dam at a point where full mixing of combined discharges is achieved. In addition to the 

regularly scheduled monthly profiling in the Glen Canyon Dam forebay, additional monitoring 

locations will be added to include the upstream extent of the hypolimnion, between 45 and 90 

km above the dam. Additional surveys of these locations will take place immediately before and 

immediately after a future BHBF test. During a future BHBF test, additional chemical samples 

will be taken in the dam, at Lees Ferry, and at the river outlet works depth in the reservoir before 

and after a BHBF test. 

Need for Project 

Use of the river outlet works, 30 m below the penstocks, draws water from deeper layers of the 

reservoir than normal powerplant releases. This water is cooler, has higher concentrations of 

dissolved minerals and nutrients, and has lower concentrations of dissolved oxygen. 

Given the most probable timing of late fall to early spring for a BHBF test, this study is likely to 

occur concurrently with an annual event in the reservoir that has been documented by the Lake 

Powell monitoring program. During this event, an upwelling of the hypolimnion of the reservoir, 

driven by winter underflow density currents, is observed at Glen Canyon Dam and influences 

powerplant releases in the early spring. During a future BHBF test, the operation of the river 

outlet works, combined with full powerplant releases, could evacuate large volumes of this 

hypolimnetic water, causing mixing to deeper layers of the reservoir and reduction of the volume 

of stagnant hypolimnion. For this reason, the BHBF test of 1996 significantly mixed and 

diminished the stagnant water in the hypolimnion (Hueftle and Stevens, 2001). Development of 

stagnation of the hypolimnion can produce hypoxic (low oxygen) conditions in the reservoir, 

which may in turn be discharged below the dam into the tailwaters. 
51

The 2004 BHBF test occurred in November when convective mixing and reduced reservoir 

elevations brought upper lake layers closer to the release structures. Consequently, net releases 

during the 2004 BHBF test were drawn primarily from the surface layers and had little effect on 

hypolimnetic waters. February/March timing for a future BHBF test is more likely to release 

colder, saline, and hypoxic water from the hypolimnion. 

In summary, a future BHBF test has the potential to entrain deeper layers of the reservoir, which 

could cause enhanced mixing of those layers and reduced stagnation and hypoxia. Releases 

downstream may deliver more nutrients to the aquatic ecosystem and the river outlet works 

would re-aerate hypoxic releases. 

Methods 

Existing methodologies associated with the Lake Powell water-quality core monitoring program 

will be used to accomplish the objectives. Additional multiparameter sondes will be calibrated 

and deployed according to past standards. Additional chemical samples will be collected and 

processed with monitoring samples; profiles will be conduced using existing equipment and 

methods. 

Links/Relationships to Other Projects 

Use of the river outlet works is likely to increase the export of nutrients and ions during the 

experimental flows and could alter hypolimnetic mixing patterns and result in the increased 

evacuation of hypolimnetic water. This could provide additional nutrients to the aquatic food 

base in Grand Canyon in the recovery period following the experiment (Parnell and others, 1999; 

Shannon and others, 2001; Stevens and others, 2001; Schmidt and others, 2001). 

Information Needs Addressed 

The following information needs will be addressed by this project: 

RIN 7.3.1.a Determine the status and trends of chemical and biological components of 

water quality in Lake Powell as a function of regional hydrologic conditions and their 

relation to downstream releases. 

RIN 7.3.1.b Determine stratification, convective mixing patterns, and behavior of 

advective currents in Lake Powell and their relation to Glen Canyon Dam operation to 

predict seasonal patterns and trends in downstream releases.

Products/Reports 

A post-experiment report will summarize findings of data collection efforts and a discussion of 

changes to the stratification and water quality in Lake Powell and changes to the water quality of 

the Glen Canyon Dam tailwaters as a result of the experimental action. 
52

Costs by Year (specific fiscal years are not shown here, although FY 2007 costs are used 

for cost estimating purposes) 

FUNDING PROPOSAL 

Experimental Study 5: Evaluate effects of a future BHBF test on water quality of Lake Powell and 

Glen Canyon Dam releases (Lake Powell) 

 Year 1 Year 2 

GCMRC Personnel Costs (19.1% Burden) $11,132 $6,185 

GCMRC Project Related Travel / Training (19.1% Burden) $452 - 

GCMRC Operations / Supplies / Publications (19.1% Burden) $1,200 - 

GCMRC Equipment Purchase / Replacement (19.1% Burden) - - 

AMP Logistical Support (19.1% Burden) $1,427 - 

Outside GCMRC & Contract Science Labor (19.1%) - - 

Cooperative / Interagency Agreements (6.09% Burden) - - 

Project Sub-total $14,211 $6,185 

DOI Customer Burden (Combined 6.09% and/or 19.1%) $2,714 $1,181 

Project Total (Gross) $16,925 $7,366 

Percent Outsourced 0% 0%
53

6. Logistics activities in support of experimental studies 

Scheduling Considerations 

Scheduling a future BHBF test during the spring period poses several considerations for the 

GCMRC Logistics Program. The primary logistical constraints for scheduling a BHBF test in the 

spring are: (1) consideration of scheduling impacts to the existing monitoring program, (2) 

provision of adequate lead time for preparation for the additional demands required to support 

BHBF research, and (3) provision of adequate time to work with the National Park Service on 

permitting activities and public outreach to address safety concerns for backcountry and river 

users during periods of high flows. 

This BHBF science plan requires launching nine motorized research trips (plus an additional 

press trip) and support of research projects in the Glen Canyon reach and upstream of Diamond 

Creek (table 5). Trips are initiated 5 weeks before the high-flow peak and up to 8 weeks after the 

peak flow, encompassing a 3 month time period. During this period in the spring, there are 

typically three major projects scheduled to conduct field research: mainstem fish monitoring 

(two trips), aquatic food base, and sediment-mass balance. The combination of BHBF trips and 

regularly scheduled monitoring trips places a heavy demand on the resources available to the 

GCMRC Logistics Program. The increased demand exceeds the current capacity of the GCMRC 

Logistics Program requiring additional equipment, upgrade of current capacities, and 

coordination of additional external resources. 

Funding must be made available to the logistics program 6 weeks before the scheduled launch of 

the first BHBF trip so that resources are available to support the experimental BHBF trips while 

maintaining adequate support for regularly scheduled monitoring trips. 

Permitting 

The final BHBF science plan will be submitted to the Grand Canyon National Park Research 

Permits Office for review as a project requiring a Research and Collecting Permit. Following 

approval of a Research and Collecting Permit, individual trip permit applications will be 

submitted for each of the nine trips proposed in this science plan. Requests for permit approval 

should occur no less than 6 weeks before the first BHBF research trip launch date. 

Public Outreach 

The GCMRC will collaborate with the National Park Service to establish a public outreach plan 

to inform the public, specifically recreational river and backcountry users, about safety concerns 

because of high flows. In collaboration with the National Park Service, a handout will be 

prepared informing the public on the purpose and effects of a future BHBF test, including a 

hydrograph of the peak flows, which will be distributed to all river and backcountry users who 

may be affected. This plan also includes a budget for an unscheduled press river trip. 

Logistics 

A future BHBF test will require nine motorized trips to support the proposed research activities 

outlined in this plan. Two trips will launch in advance of the BHBF test. Four trips will be 
54

launched before the BHBF test to be stationed at 30 mile, 45 mile, 60 mile, and Phantom Ranch 

to conduct sampling before, during, and after the BHBF test. One trip launches on the initiation 

of the peak flow and the final two trips are conducted post-BHBF test. Additionally, work will 

take place in the Glen Canyon reach between Lees Ferry and Glen Canyon Dam and upstream of 

Diamond Creek at river mile 225. 

Table 5. Logistical support requirements for proposed experimental studies. 

 Project Boats Location Trip Length # Personnel 

Trip 1

 

4b 22’, 1-sport (Achilles) RM 0–225 12 days 6–8 

Trip 2 1c 2-33’,1-22’ (Eyeball), 1-

22’ (Hydro), 1-sport 

(Osprey) 

RM 0–225 18 days 18–20 

Trip 3 1a/3 1-33’, 2-sport (Osprey) RM 61 20 8–12 

Trip 4 1b 1-33’, 1-22’ (Hydro) RM 45 16 6–8 

Trip 5 1a/KAS 

compliance 

1-33’, 1-sport (Osprey) RM30 16 6–8 

Trip 6 1a 1-33’, 1-22’, 1-Sport 

(Achilles) 

RM 87/ Lower 

Lagrangian 

14 6–8 

Trip 7 1a 1-33’, 1-22’ Upper 

Lagrangian 

12 6–8 

Trip 8 1c 2-33’,1-22’ (Eyeball), 1-

22’ (Hydro), 1-sport 

(Osprey) 

RM 0–225 18 18–20 

Trip 9 1c 2-33’ RM 0–225 18 12–14 

Recommended Timeline 

• Final Approval BHBF Test and Hydrograph (date and hour specific) 

• Permitting and Logistical Planning Initiated (6 weeks) 

• First BHBF Research Trip Launches (5 weeks) 

• High Flows initiated (8 weeks) 

• Final Post-BHBF Test Trip Launches 

Estimated Logistics Costs (using FY 2007 costs) 

Experimental studies and associated logistical support activities 

Year 1 projected cost 

(included in study 

budgets) 

1.A Sand Budgeting $110,000

1.B Sandbar Depositional Rates $17,000

1.C Sandbar Fate $120,000

2 Riparian Vegetation Studies $8,000

3.A Lower Trophic Levels $23,800

4.A Rainbow Trout Studies – Early Stages $2,000

4.B Rainbow Trout Studies – Adult Distribution 0

Appx C Spring Backwater Monitoring $12,000

5 Lake Powell 0

TOTAL PROJECTED IN-PROJECT LOGISTICS COSTS: $292,800
55

Costs by Year (specific fiscal years are not shown here, although FY 2007 costs are used 

for cost estimating purposes) 

FUNDING PROPOSAL 

Experimental Study 6. Logistics activities in support of experimental studies - direct costs (not 

included in project estimates) 

 Year 1 Year 2 

GCMRC Personnel Costs (19.1% Burden) $8,000 - 

GCMRC Project Related Travel / Training (19.1% Burden) - - 

GCMRC Operations / Supplies (19.1% Burden) $5,000 - 

GCMRC Equipment Purchase / Replacement (19.1% Burden) $35,000 - 

AMP Logistical Support (19.1% Burden) $15,000 - 

Outside GCMRC & Contract Science Labor (19.1%) - - 

Cooperative / Interagency Agreements (6.09% Burden) - - 

Project Sub-total $63,000 - 

DOI Customer Burden (Combined 6.09% and/or 19.1%) $12,033 - 

Project Total (Gross) $75,033 - 

Percent Outsourced (includes 50% logistical support) 12% 0%
56

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Topping, D.J., Rubin, D.M., and Vierra, L.E., Jr., 2000a, Colorado River sediment transport 1. 

Natural sediment supply limitation and the influence of Glen Canyon Dam: Water Resources 

Research, v. 36, p.515–542. 

Topping, D.J., Rubin, D.M., Nelson, J.M., Kinzel, III, P.J., and Corson, I.C., 2000b, Colorado 

River sediment transport 2. Systematic bed-elevation and grain-size effects of sand supply 

limitation: Water Resources Research, v. 36, p. 543–570. 

Topping, D.J., Schmidt, J.C., and Vierra, L.E., Jr., 2003, Computation and Analysis of the 

Instantaneous-Discharge Record for the Colorado River at Lees Ferry, Arizona -- May 8, 1921, 

through September 30, 2000: U.S. Geological Survey Professional Paper 1677, 118 p. 

Topping, D.J., Rubin, D.M., and Schmidt, J.C., 2005, Regulation of sand transport in the 

Colorado River by changes in the surface grain size of eddy sandbars over multi-year 

timescales: Sedimentology, v.52, p. 1133–1153. 

Topping, D.J., Rubin, D.M., Schmidt, J.C., Hazel, J.E., Jr., Melis, T.S., Wright, S.A., Kaplinski, 

M., Draut, A.E., and Breedlove, M.J., 2006a, Comparison of sediment-transport and barresponse results from the 1996 and 2004 controlled-flood experiments on the Colorado River 

in Grand Canyon: CD-ROM Proceedings of the 8th Federal Inter-Agency Sedimentation 

Conference, Reno, Nevada, April 2–6, 2006, ISBN 0-9779007-1-1. 

Topping, D.J., Wright, S.A., Melis, T.S., and Rubin, D.M., 2006b, High-resolution monitoring of 

suspended-sediment concentration and grain size in the Colorado River using laser-diffraction 

instruments and a three-frequency acoustic system: CD-ROM Proceedings of the 8th Federal 

Inter-Agency Sedimentation Conference, Reno, Nevada, April 2–6, 2006, ISBN 0-9779007-1-

1. 
63

Topping, D.J., Rubin, D.M., and Melis, T.S., 2007, Coupled changes in sand grain size and sand 

transport driven by changes in the upstream supply of sand in the Colorado River: Relative 

importance of changes in bed-sand grain size and bed-sand area: Sedimentary Geology, 24 p., 

doi: 10.1016/j.sedgeo.2007.03.016. 

Tyus, H.M, and Saunders, J.F., III, 2000, Nonnative fish control and endangered fish recovery: 

lessons from the Colorado River: Fisheries v. 9, p. 17–24. 

U.S. Department of the Interior, 1995, Operation of Glen Canyon Dam Final Environmental 

Impact Statement: Salt Lake City, Utah, Bureau of Reclamation, Upper Colorado Region, 337 

p. 

U.S. Department of the Interior, 2002, Proposed experimental releases from Glen Canyon Dam 

and removal of nonnative fish: environmental assessment: Salt Lake City, Utah, Bureau of 

Reclamation, Upper Colorado Region, 112 p., appendices. 

U.S. Department of the Interior, 2004, Supplemental environmental assessment: proposed 

experimental actions for water years 2005–2006 Colorado River, Arizona, in Glen Canyon 

National Recreation Area and Grand Canyon National Park. 

U.S. Geological Survey, 2006, Assessment of the estimated effects of four experimental options 

on resources below Glen Canyon Dam (draft): Flagstaff, Ariz., Southwest Biological Science 

Center, Grand Canyon Monitoring and Research Center. 

Valdez, R.A., Hoffnagle, T.L., McIvor, C.C., McKinney, T., and Leibfried, W.C., 2001, Effects 

of a test flood on fishes of the Colorado River in Grand Canyon, Arizona: Ecological 

Applications, v. 11, no. 3, p. 686–700. 

Valdez, R.A. and Cowdell, B.R., 1996 (unpublished), Effect of Glen Canyon Dam beach/habitatbuilding flows on fish assemblages in Glen and Grand Canyons, Arizona: Project completion 

report. 

Webb, R.H., J.C. Schmidt, G.R. Marzolf, and Valdez, R.A., eds., 1999, The controlled flood in 

Grand Canyon: Washington, D.C., American Geophysical Union, Geophysical Monograph 

Series, v. 110, 367 p. 

Wetzel, R.G., 2001, Limnology, lake and river ecosystems (3d ed.): San Diego, Calif., Academic 

Press, 1006 p. 

Wiele, S.M., Graf, J.B., and Smith, J.D., 1996, Sand deposition in the Colorado River in the 

Grand Canyon from flooding of the Little Colorado River: Water Resources Research, v. 32, 

no. 12, p. 3579–3596. 

Wiele, S.M., 1998, Modeling of flood-deposited sand distributions in a reach of the Colorado 

River below the Little Colorado River, Grand Canyon, Arizona: U.S. Geological Survey 

Water-Resources Investigations Report 97-4168, 15 p. 

Wohl, E., Bennett, J.P., Blum, M.D., Grant, G.E., Hanes, D.M., Howard, A.D., Mueller, D.S., 

Schoellhamer, D.H., and Simoes, F.J., 2006, Protocols Evaluation Program (PEP-SEDS III): 

Flagstaff, Ariz., final report of the Physical Resources Monitoring Peer Review Panel, U.S. 

Geological Survey, Grand Canyon Monitoring and Research Center, 25p., 

[http://www.gcmrc.gov/library/reports/PEP/Wohl2006.pdf]. 
64

Wright, S.A., Melis, T.S., Topping, D.J., and Rubin, D.M., 2005, Influence of Glen Canyon Dam 

operations on downstream sand resources of the Colorado River in Grand Canyon, in Gloss, 

S.P., Lovich, J.E., and Melis, T.S., eds., The state of the Colorado River ecosystem in Grand 

Canyon: U.S. Geological Survey Circular 1282, p. 17–31. 

Wright, S.A., and Gartner, J.W., 2006, Measurements of velocity profiles and suspended 

sediment concentrations in a Colorado River eddy during high flow: CD-ROM Proceedings of 

the 8th Federal Inter-Agency Sedimentation Conference, Reno, Nevada, April 2–6, 2006, 

ISBN 0-9779007-1-1. 

Yeatts, M., 1996, High elevation sand deposition and retention from the 1996 spike flow—an 

assessment for cultural resources stabilization, in Balsom, J.R., and Larralde, S. eds., 

Mitigation and monitoring of cultural resources in response to the experimental habitat 

building flow in Glen and Grand Canyons, Spring 1996: Report submitted the Bureau of 

Reclamation (Grand Canyon Monitoring and Research Center), Flagstaff, Ariz., December 

1996, p. 124–158. 
65

Appendix A. Responses to Issues Raised by Members of the Glen 

Canyon Dam Adaptive Management Program about a Future BHBF Test 

During their meeting on December 5–6, 2006, members of the Glen Canyon Dam Adaptive 

Management Program (GCDAMP) identified issues of concern for the Grand Canyon 

Monitoring and Research Center (GCMRC) to consider and address in planning for a future 

beach/habitat-building flows (BHBF) test. These concerns are summarized below from the 

meeting minutes and are followed by short responses prepared by GCMRC staff and cooperating 

scientists. 

Issue 1: What are the trade-offs between the benefits of a future BHBF test and possible 

negative impacts? 

This is a broad question and one that GCMRC staff worked to address with input from the entire 

science staff. Please see appendix A, table A-1 for a summary of the pros and cons associated 

with a future BHBF test in late winter or early spring. 

Issue 2: If a proposed future test is a new (BHBF) test, then what are the new 

hypotheses? 

The proposal for a future BHBF test is a hybrid of the two previous experiments that have been 

conducted, incorporating key learning from both the 1996 and 2004 BHBF tests. The next 

proposed BHBF intends to return more closely to the original timing of spring (if sufficient sand 

enrichment exists at that time) for such a flow operation as described in the 1995 Operation of 

Glen Canyon Dam Final Environmental Impact Statement (EIS), a timing that attempts to 

approximate the spring flood disturbance regime of the ecosystem that typically occurred before 

the construction of Glen Canyon Dam. As proposed, it would also be a second test of the concept 

of implementing BHBF test within a period when new sand supplies are known to exist in the 

main channel following tributary sand inputs. The 2004 BHBF test revealed that fall sand inputs 

from the Paria River were retained in the upper reaches of Marble Canyon under constrained 

daily dam operations that varied between 5,000 and 10,000 cubic feet per second (cfs). As a 

result, sediment experts determined that the resulting sandbar building using the sand supply was 

restricted to the upper half of Marble Canyon and that the new sand did not have time under that 

60-hour test to be transported to reaches downstream of about river mile 40 or so. 

Analysis of the 2004 results produced a revised hypothesis regarding sand transport. This new 

hypothesis postulates that new sand inputs that enter the ecosystem from the Paria River should 

be allowed some limited time to be transported downstream into lower Marble Canyon under the 

1996 Record of Decision operations. Hence, there is an evolving question about the appropriate 

timing for when a BHBF should optimally be tested and implemented relative to: (1) the 

seasonal timing of when tributary sand typically is introduced to the ecosystem from the Paria 

River (late summer to fall), (2) how the new sand gets distributed downstream through Marble 

and Grand Canyons under Record of Decision operations within the months following inputs, (3) 

whether redistributing the new sand in a more uniform longitudinal pattern downstream before a 

BHBF test results in more uniform and robust sandbar deposition, and (4) the season in which 

historical flood disturbance occurs (spring). 
66

The exact timing a future BHBF test will depend on the magnitude of the sand inputs from the 

tributaries and the magnitudes of releases from the dam. The timing of a BHBF could likely 

occur in spring if sand inputs greatly surpass the proposed trigger for a BHBF and dam releases 

are lower. This would have been the scenario if a BHBF had occurred in spring 2007. However, 

the timing of a BHBF would be much earlier (potentially late fall or winter) to still be above the 

trigger threshold, if sand inputs equal the minimum required by the proposed trigger and are 

accompanied by moderate to high dam releases. 

The science plan for a future BHBF test proposes to have additional studies tied to food base, 

fisheries, and cultural sites. Table 1 identified the science questions that will be addressed in a 

future BHBF test. Specific hypotheses associated with these studies are described in the 

experimental study descriptions included in this BHBF science plan. 

Issue 3: What is the reason behind replicating the 2004 (BHBF test) hydrograph? 

The concept of replicating the 2004 BHBF test hydrograph (i.e., replicating that portion of the 

2004 hydrograph consisting of the rising limb, peak, and recession of the November 2004 BHBF 

test) was discussed extensively among cooperating sediment scientists at the 2005 knowledge 

assessment workshop convened by the GCMRC with stakeholders. The 2004 test hydrograph 

was designed using sandbar simulations for a subset of eddies under a scenario of 45,000 cfs 

peak magnitude and assuming sand concentrations that were measured in the postdam era. This 

information and data collected from the 1996 BHBF test were the basis for choosing 60 hours as 

the duration for the peak flow of a future BHBF test, a much shorter duration than the 168 hours 

tested in 1996. The 2004 BHBF test peak magnitude was limited to 41,500 cfs because one of 

the eight turbine units at Glen Canyon Dam was undergoing maintenance. The concept of 

replication of the 2004 BHBF test hydrograph in a future test is aimed at determining whether or 

not the robust sandbar-building responses that occurred under the 2004 BHBF test will occur 

consistently with sand-enriched conditions. Replication the 2004 BHBF hydrograph during sandenriched conditions also allows scientists to evaluate whether there are incremental, cumulative 

benefits to sandbar conservation in lower Marble Canyon and Grand Canyon reaches each time 

enriched high-flow experiments occur. 

If the results from replicating the 2004 BHBF test hydrograph under sand-enriched conditions in 

the spring (following several months of downstream transport under the 1996 Record of 

Decision operations) are as good or better (more uniformly distributed sandbar responses under 

conditions of more uniformly distributed sand supply downstream) than those measured during 

the 2004 BHBF test, then this approach may be interpreted as being a sustainable strategy for 

longer term habitat restoration and maintenance using only downstream sand supplies. Such a 

replicated, positive result would also indicate that the more natural timing for flood disturbance 

in spring can be accomplished while conserving new sand inputs before they are exported to the 

upper Lake Mead delta. On the other hand, if a different BHBF test hydrograph is used for the 

next test and the results are not as good as 2004 BHBF test results, then the lack of replication 

will make it very difficult to determine whether the response was the result of different BHBF 

test timing and supply conditions or to the different hydrograph. 

Because the 2004 BHBF test hydrograph design was tied to sandbar and eddy simulations made 

using measured channel topography and sediment transport data, and because the 2004 BHBF 
67

test did result in robust sandbar building in the reach where the sand supply was locally enriched 

(upper Marble Canyon), it seems reasonable to return to this hydrograph design for a future 

BHBF test to confirm its effectiveness. 

Issue 4: What would be the pros and cons of a shorter-duration BHBF test peak at 41,500 

cfs (for instance, 30 hours)? 

Discussions among scientists and managers about alternative duration peak flows for future 

BHBF test (i.e., shorter than the 60-hour peak tested in 2004) have been ongoing during recent 

planning activities. There are many factors to consider related to peak-flow duration and peak 

magnitudes for BHBF tests (see appendix A, table A.2). 

Issue 5: Is there a risk of a potential take or impact (of a future BHBF test) on juvenile 

humpback chub? HBC recruitment? 

Assuming a future BHBF test will occur in spring, there appears to be little risk to juvenile 

humpback chub associated with a future BHBF test, given the results of fisheries studies 

conducted in association with the 1996 BHBF experiment in Grand Canyon. The abundance of 

juvenile humpback chub in the mainstem Colorado River is driven, in part, by freshet events in 

the Little Colorado River. Because the proposed timing of a future BHBF test is generally tied to 

late winter or early spring, scientists at the GCMRC expect few freshet events and therefore few 

juvenile humpback chub to be present in the mainstem Colorado River. This alone will reduce 

the number of humpback chub vulnerable to potential displacement or mortality because of a 

future BHBF test. Following extensive sampling to measure abundance of fish before and after 

the spring 1996 BHBF experiment, catch-rate metrics showed insignificant differences before 

and after the experiment for most fish (Valdez and others, 2001). The exceptions were a 

significant decrease in the abundance of small-bodied nonnative fish and a significant increase in 

the abundance of speckled dace. Additionally, results from telemetry and diet work suggest 

minimal behavioral or feeding disruptions of adult humpback chub and flannelmouth sucker 

associated with the spring 1996 BHBF test. Relative abundance of juvenile native fish was also 

estimated before and after the 2004 BHBF test downstream of the Little Colorado River 

confluence (GCMRC unpublished data; Coggins and others, 2005). Unfortunately, the results of 

the fall 2004 study were highly inconclusive owing to elevated turbidity following that 2004 

BHBF test because of flooding activity in the Little Colorado River. These conditions rendered 

catch-rate observations taken before and after the experiment unreliable, which was likely the 

result of changes in sampling gear efficiency. 

The finding that native fish are little affected by high-flow events, which emerged from research 

associated with the 1996 BHBF test, is consistent with theory and other published studies. Meffe 

(1984) found that adapted native fish species tolerated elevated discharge associated with 

freshets better than introduced species. Brouder (2001) found that age-1 native roundtail chub 

increased or remained high in years following a late winter/early spring flood. Indeed, this 

differential tolerance to flooding has been suggested as a nonnative control method (Minckley 

and Meffe, 1987). Although these studies view high discharge events as potential displacement 

mechanisms rather than direct sources of mortality, there is no evidence that humpback chub 

recruitment would be directly hindered by a future BHBF test. On the contrary, one hypothesis is 

that potential humpback chub recruits might enjoy higher survival rates because of increased 
68

food resources (see experimental study 3 description, this plan) and decreased negative 

interaction with nonnative fishes (Valdez and others, 2001). There is presently insufficient data 

to arbitrate among these competing hypotheses, although, it is certainly valid to hypothesize that 

a future BHBF test could hinder recruitment by imposing some direct or indirect mortality 

source. 

Issue 6: Concerns about insufficient funds to address HBC issue (relative to a future 

BHBF test). 

The GCMRC believes that funding is not the major impediment to studying the effects of a 

future BHBF test on humpback chub. The major challenge is attempting to evaluate changes in 

distribution and fate of humpback chub without the appropriate techniques and/or technology to 

field a viable study (see appendix B). 

Issue 7: Will there be negative impacts (from future BHBF testing) to the food base? Will 

it clean or refresh the system? 

We are uncertain about these important questions. While we know that the biomass (a static 

measure) of food base components is temporarily reduced following a future BHBF test, little is 

known about the effect of a future BHBF test on productivity (a dynamic process measure). The 

GCMRC’s working hypothesis included in this BHBF science plan is that after the initial 

reduction in food following a future BHBF test, daily production and turnover of algae, 

invertebrates, and possibly fish are higher than before the BHBF test. This positive response by 

the food base may offset the initial negative effects such that there is little net loss of material 

and productivity when viewed on slightly longer time scales (months to a year). This knowledge 

gap is precisely why at least one additional BHBF test is needed to pin down quantitative 

answers for the important questions raised above. 

Issue 8: What are the impacts (of a future BHBF test) to hydropower and other economic 

interests (i.e., fishing guides and river guides)? 

Comprehensive studies to assess the economic impacts of conducting a future BHBF test have 

not been conducted and, therefore, the full range of economic impacts cannot be definitively 

determined with available information. Based on the recent economic assessment by the Western 

Area Power Administration (WAPA) for the experimental options study (conducted in 2006 by 

the AMWG’s Science Planning Group), there would be some short-term, but significant, 

economic impacts for hydropower in the form of lost revenue generation opportunities (loss of 

potential marketable power because of water bypassing the generators during a future BHBF 

test). There would also be some immediate short-term gains resulting from running the 

generators at full capacity during a future BHBF test, although, the gains would not be sufficient 

to offset future lost opportunity costs. In terms of recreational economic interests, there are likely 

to be short-term impacts to the local fishing guide economy during and probably immediately 

following a future BHBF test. Based on the proposed timing and duration of the event, however, 

and considering the hypothesized response of the aquatic food base over the long term (shortterm decline followed by relatively rapid rebound and potentially increased productivity), the 

economic impact to recreational fishing is uncertain and yet to be studied. Projected economic 

impacts to commercial river runners, on the other hand, are likely to be very minimal to nonexistent, because the proposed timing of a future BHBF test is before the start of the commercial 
69

boating season. The larger question that remains to be determined is whether the combined 

potential economic impacts of conducting a future BHBF test outweigh the potential resource 

benefits and societal value derived from conducting the experiment. The answer to this question 

is critical for assessing the overall economic implications of a BHBF test. The GCDAMP is 

currently lacking up-to-date, comprehensive valuation data to address this larger economic 

question. A more comprehensive study of the economic impacts of conducting a future BHBF 

experiment could be considered during development of the Long Term Experimental Plan. 

Issue 9: BHBF experiments result in a lot of sediment below Diamond Creek, resulting in 

economic concerns for the Hualapai Nation. Additionally, there is an archaeological site 

below Glen Canyon Dam that going to be harmed unless there is a plan for that site. 

In recent years, with the lowering of Lake Mead because of drought and ongoing water 

withdrawal, formerly submerged sand deposits at the head of Lake Mead have become 

increasingly shallow, creating serious challenges for down-lake navigation. Also, the exposure of 

formerly submerged sandbars has cut off access to a formerly popular take-out point at Pierce 

Ferry. The Hualapai Tribe is concerned that a BHBF test could exacerbate these current 

problems by displacing sand from the main channel into areas used as harbors and launch sites 

by their boat operators. At Diamond Creek and other eddies immediately downstream, sand is 

very likely to be transferred into the eddies (this is why the previous 2004 BHBF test built 

sandbars and benefited camping beaches in a reach where new sand inputs were located). 

Assuming the lake remains low, a future BHBF test released into Lake Mead is also likely to 

generate a strong current in the upper part of the lake, which would remobilize some of the 

channel-clogging sediment and help to redefine a clear channel through the sandbars in the upper 

part of the lake, but whether and to what degree sediment would be re-deposited in specific 

shoreline locations used by the Hualapai Nation tour operators, and whether it would have 

negative consequences for these commercial operations, is unknown. What is known with 

certainty is that a future short-term BHBF test will not solve, nor will it significantly exacerbate, 

the long-term issue of sediment build-up in upper Lake Mead with its concomitant implications 

for future navigability. 

The second part of the comment expresses concern about possible negative impacts BHBF test to 

archaeological sites, particularly one site located in the Glen Canyon reach. In 1996, before the 

first BHBF test, the Bureau of Reclamation funded a series of studies to evaluate and mitigate 

potential effects of high-flow experiments on cultural sites in the river corridor. Following 

completion of these compliance-driven studies, the Arizona State Historic Preservation Office 

issued a formal determination of "no adverse effect" for experimental flows up to 60,000 cfs 

(Nancy Coulam, personal comm., December 7, 2006). Recently, a team of archaeologists and 

one geomorphologist from the Navajo Nation Archaeology Department (NNAD) completed a 

geomorphic evaluation of all archaeological sites in the Glen Canyon reach, and they concluded 

that one site (AZ C:2:32) has the potential to be eroded by a future BHBF test. During the 1996 

mitigation work, there was considerable uncertainty as to whether this site was truly cultural, but 

the recent re-evaluation by NNAD confirms that this is a potentially significant archaeological 

site containing deposits dating to the late Archaic period, approximately 3,000 years BP. The 

NNAD archaeologists recommend that a portion of this threatened site adjacent to the river be 

excavated before conducting a future BHBF test. Mitigation of potential BHBF impacts is 

planned to occur in fiscal year 2008, as one component of a larger treatment project being 
70

proposed by the Bureau of Reclamation to address impacts of dam operations on archaeological 

sites. 

Issue 10: Time is constrained by the possibility of one dam unit being down for 

maintenance after March. 

From our understanding of the proposed annual maintenance schedule at Glen Canyon Dam, we 

do not see a problem with having one of the eight turbine units at the dam non-operational 

annually through March during a future BHBF test, although, having eight units fully operational 

would be optimal for sediment studies. A future BHBF test is not currently proposed for later 

than March. 
71

Table A.1. Summary of pros and cons associated with conducting a future BHBF Test. 

GENERAL 

CONCERNS 

PROS CONS UNCERTAINTIES 

GLEN CANYON 

DAM ADAPTIVE 

MANAGEMENT 

PROGRAM 

(GCDAMP) 

RESOURCES 

• Probable sandbar 

restoration and 

conservation of 

related physical 

habitats 

• Probable 

improvement of 

recreational camping 

sites 

• Probable 

enhancement of 

sediment transport 

to and mitigation of 

erosion at some 

archeological sites 

through secondary 

wind deposition 

• Creation of 

backwater habitats 

used by native fishes 

• Mimics seasonal 

flood disturbance to 

river ecosystem 

• Lost hydropower 

capacity and 

revenue owing to 

bypass and 

monthly volume 

re-scheduling 

• Possible impact to 

a cultural site in 

Glen Canyon (to 

be mitigated) 

• Impact to Kanab 

ambersnail habitat 

(endangered 

species) at Vaseys 

Paradise (to be 

mitigated) 

• Increased use of 

motorized 

watercraft during 

Colorado River 

Management Plan 

non-motor season 

in Grand Canyon 

National Park (to 

be mitigated 

through public 

outreach) 

• Aquatic food 

abundance 

• Impacts 

and/or 

benefits to 

humpback 

chub remain 

uncertain 

• Impacts on 

rainbow trout 

fishery 

• Impacts on 

native and 

nonnative 

terrestrial 

vegetation 

SCIENCE 

(Learning by 

Doing) 

• Advances learning 

about options for 

achieving GCDAMP 

goals related to 

sediment, humbback 

chub, food base, 

cultural resources, 

camping beaches, 

and riparian habitat 

• Provides 

information about 

optimal BHBF 

hydrograph design 

to maximize benefit 

and minimize costs 

• Informs interested 

public 

• None • None 
72

• Information transfer 

to other scientists 

and managers 

working on river 

restoration 

EXP BUDGET 

• Credible subset of 

studies can be 

implemented to 

address high-priority 

needs 

• Available 

Experimental 

funding is 

currently 

insufficient to 

implement all 

proposed studies 

• None 

ECONOMIC 

• Infusion of local 

economic activity 

linked to science 

support, etc. 

• Foregone 

hydropower 

capacity in later 

timeframe (to be 

quantified by 

BOR/WAPA) 

• Potential shortterm disruption of 

Lees Ferry angling 

recreation 

• Financial 

impact is not 

yet fully 

quantified 

• Non-use 

values 

derived from 

resource 

effects are not 

known? 

INFLUENCE ON 

ANNUAL WORK 

PLAN 

• Shifts emphasis 

from solely 

monitoring to EXP 

research learning 

activities in a given 

year 

• New information 

will better inform 

GCDAMP process 

• Number of nonexperimental 

planned activities 

will need to be 

delayed/deferred 

• Impacts timing of 

some normal 

monitoring 

activities 

• Full impact 

on a given 

typical annual 

work plan 

schedule is 

not 

completely 

known? 

NO HIGH-FLOW 

EXPERIMENTS 

(BHBF) 

ALTERNATIVE 

(SCIENCE/RESO

URCE 

PERSPECTIVE) 

• Would not impact 

annual work plan 

tasks of monitoring 

• Monitoring data on 

downstream fate of 

new sand supplies 

under modified low 

fluctuating flow 

(MLFF) 

• No hydropower 

impacts 

• No opportunity to 

benefit sand and 

related physical 

habitats (such as 

backwaters that 

may benefit 

juvenile humpback 

chub)

• Already have 

abundant data on 

export of sand 

under MLFF, 

hence little new 

learning would 

occur

• No opportunity to 

learn more about 

• There is great 

uncertainty 

about when 

conditions in 

the future will 

trigger an 

enriched 

high-flow 

experiment 

owing to the 

fact that sand 

inputs from 

the tributaries 

cannot be 

predicted 
73

how BHBFs may 

limit sand export 

under fluctuating 

flows that follow

• Missed 

opportunity to 

gather data on 

BHBFs as related 

to strategic, 

experimental 

questions about 

sand conservation 

and effectiveness 

of BHBFs to meet 

Goal #8 objectives

• BHBFs are 

dependent on 

meeting the 

sediment input 

trigger
74

Table A.2. Comparison of a 60-hour to 30-hour peak duration beach/habitat-building flows 

(BHBF) test at 45,000 cubic feet per second (cfs). 

High-flow peak duration 

at 41,500 cfs 

~ Glen Canyon 

Dam bypass volume 

(Hours) 

PROS CONS 

OPTION A 

60 hours (as determined 

by BHBF model 

simulations and 

recommended by 

sediment scientists) 

~ 93,000 acre feet 

(91 hours) 

• Provides most 

rigorous direct 

comparison with 

2004 BHBF test 

data 

• Maximum sandbar 

restoration 

predicted from 

modeling to occur 

in this timeframe 

• Resulted in net 

positive sand 

balance in 2004 

BHBF test 

• Allows field 

scientists time for 

replicate eddy and 

SS measurements 

• 108 hours shorter 

than 1996 BHBF 

test 

• Greatest influence 

on exporting low 

oxygen from 

hypolimnion of 

Lake Powell 

• Bypass volume is 

larger than 

suggested 

alternatives 

(below) 

• Highest impact on 

hydropower 

• Highest impact on 

recreational users 

OPTION B 

30 hours (alternative 

BHBF test hydrograph) 

~ 56,000 acre feet 

(61 hours) 

• Reduces bypass 

volume 

• Reduced impact 

on hydropower 

• Reduced impact 

on recreational 

users 

• Reduces potential 

export of new sand 

supply relative to 

option A 

• Potentially limits 

benefits to 

downstream 

sandbar restoration 

• Limits data capture 

potential 

• Shorter BHBF 

tests result in less 

influence on 

exporting low 

oxygen from 

hypolimnion of 

Lake Powell 
75

References Cited 

Brouder, M.J., 2006, Effects of flooding on recruitment of roundtail chub, Gila robusta, in a 

southwestern river: The Southwestern Naturalist, v. 46, no. 3, p. 302–310. 

Coggins, L., Yard, M., Persons, B., Van Haverbeke, R, and David, J., 2005, Results of hoopnet 

sampling to examine changes in juvenile humpback chub abundance and size before and after 

the 2004 experimental high flow: presentation to the Adaptive Management Workgroup, 

March 3, 2005, 

[http://www.usbr.gov/uc/rm/amp/amwg/mtgs/05mar02/documents/Attach_07h.pdf]. 

Meffe, G.K., 1984, Effects of abiotic disturbance on coexistence of predator-prey fish 

 Species: Ecology, v. 65, no. 5, p. 1525–1534. 

Minckley, W.L., and Meffe, G.K., 1987, Differential selection for native fishes by flooding in 

streams of the arid American Southwest, in Matthews, W.J., and Heines, D.C., eds., Ecology 

and evolution of North American stream fish communities: Norman, Oklahoma, University of 

Oklahoma Press, p. 93–104. 

Valdez, R.A., Hoffnagle, T.L., McIvor, C.C., McKinney, T., and Leibfried, W.C., 2001, 

 Effects of a test flood on fishes of the Colorado River in Grand Canyon, Arizona: 

 Ecological Applications, v. 11, no. 3, p. 686–700. 
76

Appendix B: Factors Influencing the Design of BHBF Related 

Experimental Studies for Fisheries, Cultural Resources, and Water 

Quality 

Fisheries Studies Associated with a Future BHBF Test 

The use of BHBFs was identified in the 1995 Operation of Glen Canyon Dam Final 

Environmental Impact Statement (EIS) as a strategy to rebuild sediment resources tied to 

physical, nearshore habitats thought to be important to native fish in the mainstem Colorado 

River below Glen Canyon Dam. Short-term experimental releases have previously been reported 

to have limited immediate influence on long-lived fishes (Valdez and others, 2001). It is still 

unclear what role the abundance, size, and distribution of nearshore sandbar features, such as 

backwaters, play in the life history of humpback chub in the Colorado River ecosystem. 

Evaluating complex and multiyear fish responses that might be associated with short-duration, 

BHBF tests that occur infrequently (mostly designed with sediment studies in mind) is difficult. 

Simply put, the capture and enumeration of rare fishes in a large, turbid river are difficult tasks 

that, despite recent advances, continue to be associated with high uncertainty. 

The GCMRC and its cooperators continue to work on this problem and are improving both the 

capture and estimation techniques for the rare native fishes, especially humpback chub. Because 

of the high level of interest in these species, monitoring for humpback chub and other native 

fishes occurs throughout the year (illustrated by the 2007 work plan summarized in table B.1), 

providing a long-term perspective on the status and trends of these populations. Such a sampling 

regimen will bracket a future BHBF test whenever it is scheduled and provide a valuable, longterm perspective on the fate of humpback chub and other native fishes. 
77

Table B.1. Native fish monitoring below Glen Canyon Dam in 2007. 

Project Timing Primary Objective 

Downstream Native Fishes March Monitor native fishes from Lees 

Ferry to Diamond Creek (spring) 

Little Colorado River (LCR) 

Humpback Chub 

April Population estimate of humpback 

chub in the LCR (concurrent 

sample) 

Little Colorado River Lower 

1,200 meters/PIT tag antennae 

April–May Intensive monitoring of 

humpback chub in lowest 1,200 

meters of the LCR/test remote 

PIT tag antennae 

Downstream Native Fishes April Population estimate of humpback 

chub in the mainstem Colorado 

River (concurrent sample) 

Little Colorado River Humpback 

Chub 

May Population estimate of humpback 

chub in the LCR (concurrent 

sample) 

Downstream Native Fishes May Population estimate of humpback 

chub in the mainstem Colorado 

River (concurrent sample) 

Above Chute Falls June Monitor the translocated 

population of humpback chub 

upstream in the LCR 

Warm Water Fishes/Sonic Tags June Monitor channel catfish in lower 

Colorado River/test application of 

sonic tags 

Above Chute Falls June-July Monitor the translocated 

population of humpback chub 

upstream in the LCR 

Downstream Native Fishes March Monitor native fishes from Lees 

Ferry to Diamond Creek 

(autumn) 

Backwater Monitoring September–October Monitor small-bodied fishes in 

nearshore habitats, primarily 

backwater eddies 

Little Colorado River Humpback 

Chub 

September Population estimate of humpback 

chub in the LCR 

Little Colorado River Humpback 

Chub 

October Population estimate of humpback 

chub in the LCR 

Fisheries scientists attempted to evaluate changes in distribution of native and nonnative fishes 

using catch-rate metrics from conventional sampling gear (e.g., hoopnets, electrofishing, etc.) 

used during the 1996 and 2004 BHBF tests. This common strategy was based on the assumption 

that catch-rate (number of fish captured per each unit of sampling effort) is directly proportional 

to fish abundance. However, this assumption will be violated if the efficiency of the sampling 

gear (catchability) is substantially affected by any uncontrollable variables (e.g., temperature, 

turbidity; reviewed by Arreguin-Sanchez, 1996). Therefore, comparisons of catch rate before and 

after an event like a future BHBF test are only valid to infer changes in abundance if it can be 

safely assumed that catchability was equal between the two samples. Violations of this 

assumption are particularly problematic when comparisons are made between only two events, 
78

as opposed to inferring trend in abundance from extensive time-series data where variability in 

catchability can sometimes be taken into consideration. Additionally, catch-rate estimates for 

rare fishes are frequently estimated with low precision. This is clearly illustrated in the results of 

the 1996 BHBF test (Valdez and others, 2001). Careful inspection of these results suggests that 

the statistical power to detect changes in rare species using single event sampling is very low. 

A further problem with this type of study is that displacement does not necessarily imply 

mortality. For instance, even if the decline in catch rate associated with the 2004 BHBF test 

(GCMRC, unpublished data; Coggins and others, 2005) was related to a change in abundance 

rather than a change in catchability, it is unknown whether the change in abundance was because 

of mortality. It is also possible that this change is simply a result of fish using different habitats 

following the 2004 BHBF test or downstream displacement was temporary. Regardless of which 

of these hypotheses is correct, this type of study cannot ultimately provide information on the 

fate of fish associated with a future BHBF test. Therefore, we conclude that new techniques are 

required to answer the recurring question asked by managers, namely: “What is the fate of 

juvenile native fish during a future BHBF test?” 

We propose that direct measurement of individual fish movement, accomplished through 

telemetry studies, would be the most conclusive method for inferring the fate of fish associated 

with a future BHBF test. Telemetry techniques have advanced substantially in the last decade 

and we are considering their use to investigate a host of fisheries-related questions (see section 2, 

experimental study 4.B). However, using telemetry requires substantial training and trial 

applications. We are currently engaged in trials of this technology, and the initial results are 

encouraging. 

Historically, the Lees Ferry reach has provided an ideal environment for the application of new 

technologies, suggesting a high probability of success. This owes, in part, to the ease of logistics, 

the small spatial scale, and the presence of large numbers of study animals (rainbow trout) in a 

relatively clear aquatic environment. Experimental study 4.B proposes to study the effects of a 

BHBF test on the distribution of juvenile and adult rainbow trout in the Lees Ferry reach using 

both indices of abundance and acoustic telemetry (this gear is being studied in 2007; see table 

B.1). A study of this nature has a high probability of success for multiple reasons. One benefit of 

launching this type of study in the Lees Ferry reach is that working with rainbow trout provides 

ample study organisms that can be collected with little effort. This not only promotes the ability 

to detect small experimental effects but also incurs modest logistical costs. Alternatively, 

attempting such a study for humpback chub would likely require a large effort and cost to attain 

enough organisms. This would be difficult given the proposed timing of a BHBF test because 

juvenile humpback chub are at their highest abundance in the mainstem Colorado River during 

and after the monsoon season (middle to late summer) but far fewer fish are expected to be 

available for study in November–March (the likely timing of future BHBF tests). 

The mortality risk associated with telemetry studies on juvenile rainbow trout is less than that for 

juvenile humpback chub because of the broad experience with surgical techniques for juvenile 

salmonids. The GCMRC and associated cooperators have experimented with sonic telemetry 

equipment in the Lees Ferry reach to determine its effectiveness under those specific conditions. 

Initial experimentation in December 2006 was very successful in that experimental sonic tags 

could be readily tracked in the Lees Ferry reach. 
79

Sonic tags will be tested further in 2007, under more demanding conditions, especially in the 

presence of higher turbidities than occur in the Lees Ferry reach. The value of the sonic tag 

technology to the GCDAMP will increase if it can be shown to perform well under the more 

turbid conditions of the Little Colorado River inflow and below Diamond Creek. Investigators 

will also gain expertise with implanting these tags in 2007. If the tags are still detectable in turbid 

conditions, and if investigators achieve good survival rates for fish implanted with the tags 

during 2007 studies, the GCMRC will propose that this technology be used with individual 

humpback chub, subject to regulatory agency approval. The 2007 results, and results in future 

years, will help determine the minimum size of humpback chub that would be proposed for 

tagging and tracking; however, there is general agreement among the cooperators that younger, 

smaller fish are of greatest concern and, therefore, would be most important to track. Specific 

recommendations for use of sonic tag technology, including an associated budget, will be 

prepared, reviewed, and distributed at least 120 days in advance of a proposed future BHBF test. 

The thoughtful review of the GCDAMP Science Advisors clearly articulates the opinion that 

additional work on humpback chub should be a priority associated with future BHBF tests. We 

attempted to highlight the problems and shortcomings associated with fish sampling and 

monitoring connected with past experimental high flows and outline our approach to overcoming 

these issues using telemetry (see above). Subsequently, we have also identified a relatively new 

set of estimation techniques that could also allow better inferences about the effects of BHBF 

tests on humpback chub than index-based methods used in the past. 

Since 2000, much work has been done to characterize change in fish population size, 

distribution, and habitat use in situations where it is not practical to estimate or index abundance 

(Mackenzie and others, 2006). These newly developed techniques hold promise for quantifying 

change in fish density and habitat use before and after an experimental BHBF. The basic idea is 

that rather than comparing abundance indices (such as catch per unit effort) before and after 

some event where the critical assumption of equal capture probability is typically not testable, 

occupancy models estimate not only the proportion of sampling units occupied, but also the 

detection probability. As such, probability of occupancy becomes a comparable state variable 

between, for instance, two time periods. If sampling units are further grouped by a covariate such 

as habitat type, occupancy rates become a measure of habitat use. Finally, since detection 

probability is likely influenced by abundance, methods have also been developed to extract 

abundance. 

We are intrigued by this novel approach because of its potential for monitoring small-bodied 

fish. We plan to analyze several existing datasets, including the data collected in association with 

the 2004 BHBF test, and conduct simulation studies using this technique to evaluate its use in 

estimating fishes before and after any future BHBF test. Pending these evaluations, we may 

propose further sampling to estimate occupancy and associated parameters to better understand 

the effects of experimental high flows on humpback chub. If these methods are shown to be 

applicable for use in Grand Canyon, then we would propose to add a project for occupancy 

estimation for humpback chub in association with a BHBF test. This proposal and associated 

budget would be submitted for consideration at least 120 days before a proposed future BHBF 

test. 
80

Summary of Challenges in Assessing the Effects of a Future BHBF Test on Native Fish 

Populations in the Colorado River in Grand Canyon 

Trends in Fish Abundance in Glen and Grand Canyon 

• Humpback chub abundance in Grand Canyon shows continuing decline through the 1990s, 

based on catch-per-effort (CPE) and tagging assessments. Trends in adult abundance 

observed during the 1990s suggest recruitment of young humpback chub began declining by 

the mid-1980s. The more rare a species, the more difficult it is to monitor (Thompson, 2004). 

• Reductions in daily fluctuations and increased minimum flows beginning in the early 1990s 

likely caused the large increases in rainbow trout in Glen Canyon and in Grand Canyon near 

the Little Colorado River confluence where humpback chub are most abundant. 

• There is considerable uncertainty about the cause of the decline in humpback chub 

recruitment. The timing of the recruitment decline in mid-1980s does not match the timing of 

the rainbow trout increase in mid-1990s, although, increasing numbers of rainbow trout may 

have continued to suppress the humpback chub population. 

Glen Canyon Dam Treatments Targeted at Improving HBC Recruitment 

• The 1996 Biological Opinion for the EIS recommended modifications to Glen Canyon Dam 

operations designed to rebuild some elements of downstream physical habitat for humpback 

chub, including: 

• Seasonally adjusted steady flows to increase shoreline habitat stability and increase 

water temperature to stimulate mainstem spawning and improve juvenile survival 

rates, and 

• Testing of thermal modification of releases from Glen Canyon Dam. 

• The most recent experimental flow treatment recommended by the Glen Canyon Dam 

Adaptive Management Work Group called for increased daily flow fluctuations (5,000–

20,000 cfs) from January–March in 2003 and 2004. The increase in daily fluctuations was 

intended to limit rainbow trout abundance and associated negative interactions with 

humpback chub. 

• BHBFs to rebuild nearshore sandbar habitats were also described as part of the 1996 Record 

of Decision and additional sediment tests were recommended by the GCDAMP as part of 

integrated physical and biology experimentation in 2002. A second BHBF test was then 

conducted in fall 2004 when the Paria River delivered new sand to the ecosystem in Marble 

Canyon. 

• The potential for improving our understanding of the effects of dam operations, particularly 

BHBFs, is limited for the following reasons: 

• Assessments of juvenile abundance based on catch rate metrics (CPE) are difficult to 

interpret because of uncontrollable changes in gear efficiency (catchability), 

particularly for fishes in low abundance and over short time intervals (e.g., BHBF). 

• Tagging assessments are more reliable than CPE data, but there is a long lag (3+ 

years) between the time a change in recruitment occurs and when it can be observed 
81

using the tagging assessment data. The occupancy estimation models being 

investigated by GCMRC and others may be employed to help address earlier life 

stages. 

• Imprecision in all available assessment methods makes it difficult to detect year-toyear differences in recruitment unless they are extremely large. 

• Experimental flows need to be replicated over multiple years to account for 

environmental variability and the limitations in available assessment methodology. 

• The short-term single-year approach to experimental management currently adopted 

by the AMWG greatly reduces the chance of measuring native fish responses and 

does not embrace recommendations from the broader scientific literature on adaptive 

management experimental design. Further, the natural variability of annual sand 

production from the tributaries and other considerations typically means that a future 

BHBF test is likely to occur relatively infrequently under sand-enriched conditions 

and that annual replication is unlikely. 

Evaluating the status and trends of native and nonnative fish populations in Grand Canyon is 

extremely difficult because of sampling logistics and the low abundance of native fishes, 

especially in the early months of the year. Application of stock assessment modeling procedures, 

originally developed for managing commercial fisheries, has been helpful for estimating 

population trends from the historical fisheries data (Coggins and others, 2006), but tagging based 

assessments involve considerable lag time before reliable assessments of recruitment responses 

to management actions are available. However, the sonic tagging of fish being studied by 

GCMRC and cooperators has the potential to provide some short-term information on individual 

fish movements. Tagging will be especially valuable if it proves to be useful in evaluating 

whether native fishes displaced by temporary high flows retain the ability to return to an area 

following the flows. Tagging methods are generally not sufficient to resolve whether declines in 

native fish populations have been caused by the increasing abundance of nonnative fishes, dam 

operations (including BHBFs), or a combination of the two. Our ability to detect fish population 

responses to a future BHBF test is limited in spite of the lessons learned from stock assessment 

modeling and expanded monitoring efforts. Additional methods are needed and are currently 

under development by the GCMRC and cooperating agencies, especially Arizona Game and Fish 

Department. 

Additional Project to Monitor Backwater Habitats

After reviewing earlier iterations of this plan, comments were received from the GCMRC 

Science Advisors and from GCDAMP stakeholders requesting additional monitoring of the fish 

community, especially humpback chub, and fish use of backwater habitats. Despite some of the 

limitations described above, the GCMRC is proposing expanding efforts to monitor backwater 

habitats each year whether a BHBF test is conducted or not. A spring backwater monitoring trip 

has been proposed to respond to the calls for additional monitoring. Because this project is 

proposed to be conducted annually, it is not presented with the other BHBF-specific projects 

presented earlier in this document, but is presented in this document as appendix C. Funding for 

this project is included in this document in case a BHBF test is implemented before this project 

can be included in the annual work plan because of timing, funding, or other restrictions. 
82

Cultural Resources 

A future BHBF test has the potential to change ecosystem dynamics in ways that may affect the 

condition and biophysical attributes of many culturally important resources located in the 

Colorado River corridor, including archaeological sites, traditional cultural properties, and 

individual species of special concern to Native American tribes. Additionally, future BHBF tests 

may alter camping beaches used by park visitors and other ecosystem attributes that influence the 

quality of the visitors’ experience (e.g., navigability of rapids, abundance and distribution of 

rainbow trout). For example, it has been hypothesized that the periodic replenishment of 

sandbars above the level of normal Record of Decision flows reduces crowding and competition 

for campsites, thereby improving the quality of visitor experience. It has also been hypothesized 

that the creation of larger, higher, and drier sandbars as a result of periodic high flows increases 

the available sediment sources for aeolian transport to higher elevations in the ecosystem, 

thereby, potentially offsetting some of the ongoing erosion of archaeological sites caused by 

rainfall run off, social trailing, and surface deflation. 

The science activities described in this plan explicitly integrate several important cultural 

concerns within individual study plans in recognition of the close interrelationship between 

physical and biological processes and resource condition outcomes. Specifically, proposed 

science activities are designed to evaluate the potential effect of a future BHBF test on sediment 

transport and deposition at archaeological sites and consequent effects to the sites’ stability or 

erosion; evaluate the size and distribution of sandbars and open sand area used as camping sites 

and their persistence through time; trout dispersal in response to a future BHBF test; and the 

distribution of native and nonnative riparian species, many of which are culturally important to 

local Native American tribes. 

Most of the proposed BHBF studies are designed to build upon monitoring data that are already 

being collected to assess the rate and extent of changes occurring to the ecosystem under Record 

of Decision operations. For example, in conjunction with developing an ecosystem-based 

approach to monitoring archaeological site condition, the GCMRC has established weather 

monitoring stations and is collecting aeolian transport and gully erosion data at a sample of 

archaeological sites within the Colorado River ecosystem. Data from focused science activities 

proposed as part of this experimental BHBF science plan, (experimental study 1.C) would be 

analyzed in relation to these previously collected monitoring data. Likewise, the GCMRC 

annually collects data on the area, volume, and extent of available campable area at selected 

sandbar sites distributed throughout the Colorado River ecosystem; additional survey data and 

documentation collected in conjunction with a future BHBF test will be analyzed in relation to 

these pre-existing monitoring data. 

This science plan targets a limited set of key questions and issues that have been consistently 

identified by resource managers and GCDAMP stakeholders as being most critical to study 

through implementation of a future BHBF test. A future BHBF test and associated science 

activities are designed to improve understanding of the geomorphic and biological effects of a 

BHBF test conducted under sediment-enriched conditions as they relate to the goal of improving 

the potential for in situ maintenance and protection of culturally valued resources, in keeping 

with the stated intent of the GCDAMP. This information will have direct relevance to ongoing 

resource management and legal compliance issues. 
83

Water Quality 

Any investigation of the dynamics of the Colorado River ecosystem in Grand Canyon must not 

only document and understand the water quality in Grand Canyon itself, but also the water 

quality in Lake Powell, the reservoir created by Glen Canyon Dam. The impoundment of a river 

system in a reservoir alters downstream water quality in many ways (Nilsson and others, 2005). 

The formation of Lake Powell in 1963 was accompanied by reductions in suspended sediment 

and nutrient transport and by changes in seasonal temperatures, discharge levels, and benthic 

community structure of the Colorado River (Paulson and Baker, 1981; Stevens and others, 1997; 

Topping and others, 2000a; 2000b). More recently, reservoir and downstream water quality has 

been affected by reservoir drawdown from a 5-year basinwide drought in the Western United 

States. Water released from Glen Canyon Dam in 2003 and 2004 was the warmest recorded since 

August 1971, when Lake Powell was in its initial filling period (initial filling of the reservoir 

began in 1963 with the closure of Glen Canyon Dam; the reservoir reached full pool of 3,700 ft 

for the first time in 1980). 

Water temperature, nutrient concentrations, turbidity, and other water-quality parameters are of 

interest to managers and scientists because these parameters influence a range of ecosystem 

components, from support of aquatic microorganisms and invertebrates to the behavior of native 

and nonnative fishes. For example, water quality is an important determinant of food-web 

structure in aquatic habitats and abundance of consumers like fish in those food webs (Carpenter 

and Kitchell, 1996; Wetzel, 2001). 

Scientists hypothesize that operational changes associated with any future BHBF tests could 

have significant effects on the quality of water released from Glen Canyon Dam. The 

experimental work proposed in this science plan will measure changes in water-quality 

characteristics for the water leaving the dam and the water in the tailwaters during and 

immediately following a future BHBF testing. 

References Cited 

Arreguin-Sanchez, F., 1996, Catchability: a key parameter for fish stock assessment: Reviews in 

Fish Biology and Fisheries, v. 6, p. 221–242. 

Carpenter, S.R., and Kitchell, J.F., eds. 1996, The trophic cascade in lakes: Cambridge, England, 

Cambridge University Press, 385 p. 

Coggins, L., Yard, M., Persons, B., Van Haverbeke, R., and David, J., 2005, Results of hoopnet 

sampling to examine changes in juvenile humpback chub abundance and size before and after 

the 2004 experimental high flow: Presentation to the Adaptive Management Workgroup, 

March 3, 2005, 

[http://www.usbr.gov/uc/rm/amp/amwg/mtgs/05mar02/documents/Attach_07h.pdf]. 

Coggins, L.G., Pine, W.E., III, Walters, C.J., Van Haverbeke, D.R., Ward, D., Johnstone, H.C., 

2006, Abundance trends and status of the Little Colorado River population of humpback chub: 

North American Journal of Fisheries Management, v. 26, p. 233–245. 

MacKenzie, D.I., Nichols, J.D.,, Royle, J.A., Pollock, K.H., Bailey, L.L., and Hines, J.E., 2006. 

Occupancy estimation and modeling. Elsevier, New York. 
84

Nilsson, C., Reidy, C.A., Dynesius, M., Revenga, C., 2005, Fragmentation and flow regulation 

of the world’s large river systems: Science, v. 308, p. 405–408. 

Paulson, L.J., and Baker, J.R., 1981, Nutrient interactions among reservoirs on the Colorado 

River, in Stephan, H.G., ed., Proceedings of the Symposium on Surface Water Impoundments: 

New York, American Society of Civil Engineers, p. 1648–1656. 

Stevens, L.E., Shannon, J.P., Blinn, D.W., 1997, Colorado River benthic ecology in Grand 

Canyon, Arizona, USA: dam, tributary, and geomorphological influences: Regulated Rivers: 

Research & Management, v. 13, p. 129–149. 

Thompson, W.L., ed., 2004, Sampling rare or elusive species: concepts, designs, and techniques 

for estimating population parameters: Washington, D.C., Island Press. 

Topping, D.J., Rubin, D.M., and Vierra, L.E., Jr., 2000a, Colorado River sediment transport: pt. 

1: natural sediment supply limitation and the influence of Glen Canyon Dam: Water Resources 

Research, v. 36, p.515–542. 

Topping, D.J., Rubin, D.M., Nelson, J.M., Kinzel, III, P.J., and Corson, I.C., 2000b, Colorado 

River sediment transport: pt 2: systematic bed-elevation and grain-size effects of sand supply 

limitation: Water Resources Research, v. 36, p. 543–570. 

Topping, D.J., Rubin, D.M., Schmidt, J.C., Hazel, J.E., Jr., Melis, T.S., Wright, S.A., Kaplinski, 

M., Draut, A.E., and Breedlove, M.J., 2006, Comparison of sediment-transport and barresponse results from the 1996 and 2004 controlled-flood experiments on the Colorado River 

in Grand Canyon: CD-ROM Proceedings of the 8th Federal Inter-Agency Sedimentation 

Conference, Reno, Nevada, April 2–6, 2006, ISBN 0-9779007-1-1. 

Valdez, R.A., Hoffnagle, T.L., McIvor, C.C., McKinney, T., and Leibfried, W.C., 2001, 

 Effects of a test flood on fishes of the Colorado River in Grand Canyon, Arizona: 

 Ecological Applications, v. 11, no. 3, p. 686–700. 

Wetzel, R.G., 2001, Limnology, lake and river ecosystems (3d ed.): San Diego, Calif., Academic 

Press, 1006 p. 
85

Appendix C. Experimental Study: Spring monitoring of biological and 

physical aspects of backwater habitats 

Duration 

Two months annually 

Principal Investigators 

M.E. Andersen, L.G. Coggins, and G.E. Bennett, U.S. Geological Survey, Southwest Biological 

Research Center, Grand Canyon Monitoring and Research Center 

Geographic Scope 

Colorado River in Marble and Grand Canyons 

Project Goal(s) 

The goal of this project is to increase knowledge of backwater and other nearshore habitats and 

their use by the fish community. This project will sample all backwaters present for native and 

nonnative fishes. This project will collect physical data at backwaters where fish are sampled as 

time allows. 

Need for Project 

Backwater habitats in the Colorado River below the Paria River and above Diamond Creek have 

been hypothesized to offer benefits to native fishes, especially endangered humpback chub (Gila 

cypha) (Arizona Game and Fish Department 1996). Current sampling of these habitats is 

conducted in September and October, offering an estimate of the extent of these habitats in the 

fall, as well as an estimate of fish use of these habitats. The current project proposes to also 

sample these habitats beginning on the first of June, developing important information for 

temporal comparisons. This project proposes to increase the amount of physical measurement of 

these habitats to increase the amount of information available regarding the available area and 

volume of these habitats, both in years with and without a BHBF test. This project evaluates fish 

use of available backwaters, but it will also sample other shallow, near shore habitats within the 

available time of approximately 3 weeks to start accumulating data that allow for critical testing 

of the relative value of backwaters for fish. 

Strategic Science Question(s) 

1.1. To what extent are adult populations of native fish controlled by production of young 

fish from tributaries, spawning and incubation in the main stem, survival of young-ofyear (YOY) and juvenile stages in the main stem, or by changes in growth and maturation 

in the adult population as influenced by main stem conditions? 

1.7. Which tributary and mainstem habitats are most important to native fishes and how 

can these habitats best be made useable and maintained? 
86

5.3. To what extent do temperature and fluctuations in flow limit spawning and 

incubation success for native fish? 

5.6. Do the potential benefits of improved rearing habitat (warmer, more stable, more 

backwater and vegetated shorelines, more food) outweigh negative impacts due to 

increases in nonnative fish abundance? 

Working Hypotheses 

Protected backwater habitats are a relatively small portion of the available near shore habitat in 

the Colorado River in Marble and Grand Canyons. Because they are much shallower than the 

mainstem, they warm more than the mainstem during summer months. Because they are warm 

and shallow, they may offer advantages to humpback chub for increased growth because of both 

higher metabolic rates and greater available food (increased primary production). This project 

will allow for an assessment of the area and volume of these habitats that is available, and an 

evaluation of whether these habitats are indeed used by native fishes before the summer solstice. 

Methods 

One important value of this project will be the coordination of biological and physical 

monitoring. Therefore, every effort will be made to sample the fish community and to take 

physical measurements of the habitats at all backwaters encountered. However, field logistics 

may limit this ideal approach. For example, the field scientists may determine that a 

representative subset of habitats will be measured because of the time required to survey sites. 

Final determination of the number of sites to sample and measure will be dependent on field 

conditions and therefore will be the responsibility of the scientists conducting the work. 

The scientists conducting this project will operate from oar-powered rafts. Backwaters 

encountered will be measured for area and volume. Water temperature measurements will be 

taken of each location sampled, including any temperature gradient that may be present. Physical 

data will be used to evaluate modeling of near shore water temperatures in Marble and Grand 

Canyons. 

The project scientists will sample backwaters encountered with seines. Three passes will be 

conducted unless a complete visual inspection can be conducted and reveals that all fish have 

been removed. All fish encountered will be identified to at least the family level; identification to 

species level will be attempted, but non-lethal identification of very young fish in the field can be 

problematic. At least 20% of the fish encountered will be measured when numbers of fish 

captured exceed 100, so as to provide a robust sampling of large aggregations. If 100 or fewer 

fish are captured, all will be measured. 

These data will be stored in the GCMRC database. In years when a BHBF test is not conducted, 

the data will contribute to establishment of a baseline values for available habitat and fish use of 

these habitats. These baseline values can be compared between years to help determine the 

variability in habitats and fishes found in these habitats from year to year. Within years, the data 

collected from this project can be compared to the fall sampling to evaluate changes in habitat 

and/or fish community within a single year. 
87

If the 3 week time frame of this project permits, additional shallow nearshore habitats will be 

measured and sampled to help develop additional hypotheses regarding fish community usage of 

other nearshore habitats in Marble and Grand Canyons. However, the current scope emphasizes 

backwaters. 

Links/Relationship to Other Projects 

This project provides direct comparison to the data from the fall backwater seining trip regarding 

presence/absence of habitats. It also provides a direct comparison to the fish capture data from 

the fall backwater seining trips, allowing for comparison of the number of fish, the size of the 

fish, and the species using these habitats in the two different seasons. As this project continues in 

future years, comparisons between the same seasons in multiple years will be possible. 

Information Needs Addressed 

RIN 2.1.4. What habitats enhance recruitment of native fish in the LCR and mainstem? 

What are the physical and biological characteristics of those habitats? 

Products/Reports 

One or more peer-reviewed journal article(s) or USGS report(s) will be produced based on the 

findings of this study. 

Costs by Year (specific fiscal years are not shown here, although FY 2007 costs are used 

for cost estimating purposes) 

FUNDING PROPOSAL 

Appendix C. Experimental Study: Monitor physical and biological aspects of backwater and other 

nearshore habitats in June (Spring Backwater Monitoring) 

 Year 1 Year 2 

GCMRC Personnel Costs (19.1% Burden) $61,660 $61,660

GCMRC Project Related Travel / Training (19.1% Burden) - - 

GCMRC Operations / Supplies / Publications (19.1% Burden) $1,250 $1,250 

GCMRC Equipment Purchase / Replacement (19.1% Burden) - - 

AMP Logistical Support (19.1% Burden) $24,000 $24,000 

Outside GCMRC & Contract Science Labor (19.1%) - - 

Cooperative / Interagency Agreements (6.09% Burden) - - 

Project Sub-total $86,910 $86,910

DOI Customer Burden (Combined 6.09% and/or 19.1%) $16,580 $16,580

Project Total (Gross) $103,490 $103,490

Percent Outsourced (includes 50% logistical support) 6% 6%

References Cited 

Arizona Game and Fish Department, 1996, Ecology of Grand Canyon backwaters: Bureau of 

Reclamation, Glen Canyon Environmental Studies, Cooperative Agreement 9-FC-40-07940.