GCDAMP Goal 12: Maintain a high-quality monitoring, research, and 

adaptive management program 

AMWG Requested Project - Low steady summer flows – data and 

research compilation, synopsis and synthesis

Start Date 

January 2008 

End Date 

September 2010 (conducted in phases with specific end dates) 

Principal Investigator(s) 

Barbara Ralston, lead coordinator, cooperators involved in Low Steady Summer Flows (LSSF) data 

collection, GCMRC’s Data Acquisition Storage and Analysis Group. 

Geographic Scope 

Entire Colorado River ecosystem corridor from forebay of Glen Canyon Dam to upper Lake Mead 

Project Goals/Tasks 

The overall goal of this project is to develop a synthesis of the effects of the 2000 LSSF 

Experiment on the Colorado River ecosystem. The tasks involved in reaching the final goal can 

be broken into three phases: 

• Phase I. – Status of reports/data and synopsis - Identify data and products 

associated with the 2000 LSSF experiment; synopsize the results of the individual 

projects; 

• Phase II. Data evaluation and identification of secondary analyses - Evaluate 

individual datasets and provide recommendations for further analysis resulting in 

integration of resource responses to operations; 

• Phase III. Synthesis - Use integrated analysis results to develop a synthesis of the 

effects of the 2000 LSSF Experiment on the Colorado River ecosystem. 

• Phase IV. Publication – Publication of secondary analysis is special volume of 

journal or USGS circular or other publishing source. 

The project outcome is intended to provide managers, and others interested in resource 

management, with information about how multiple resources respond to a series of flows that 

varied in duration from several days to several months and in magnitude from 8k cfs to 31k cfs. 

Need for Project

The Adaptive Management Working Group (AMWG) identified in August 2007 that there was a 

need to produce a summary document of the effects of the LSSF Experiment (implemented in 

spring and summer 2000) on resources. The managers requested this summary project so that 

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the results could be used by managers as they implement long-term experiments associated with 

the Glen Canyon Dam EIS currently under development by the Bureau of Reclamation. 

The data collected in association with the 2000 experiment were in the areas of sediment 

transport and storage, mainstem and shoreline temperature, small-bodied fish sampling, longterm monitoring methods development for mainstem fishes, vegetation change, and recreational 

aspects of the varied flows. To date several of the data collection efforts have resulted in data 

reports or journal publications, while others projects remain incomplete, lacking a final report. 

The lack of a unifying document regarding the flow experiment may be perceived as an 

impediment to learning and applying this knowledge in an adaptive management setting. It is for 

this reason that a summary document is being proposed that synopsizes individual resource 

response and considers collective resource responses within an ecosystem framework. 

Strategic Science Questions 

Hypothetically, the Low Steady Summer Flow Experiment affected multiple resources and 

similarly, there are multiple Strategic Science Questions (SSQs) that pertain to the flow 

experiment. The summary project will investigate whether and to what degree these SSQs were 

addressed by the 2000 LSSF experiment. Those SSQs most pertinent to the LSSF experiment 

are listed below. 

SSQ 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 restore and maintain sandbar habitats over 

decadal time scales? 

SSQ 5-1. How do dam release temperatures, flows (average and fluctuating component), meteorology, 

canyon orientation and geometry, and reach morphology interact to determine mainstem and nearshore 

water temperatures throughout the CRE? 

SSQ 4-2. How important are backwaters and vegetated shoreline habitats to the overall growth and 

survival of YoY and juvenile native fish? Does the long-term benefit of increasing these habitats 

outweigh short-term potential costs (displacement and possibly mortality of young humpback chub) 

associated with high flows? 

SSQ 1-7. Which tributary and mainstem habitats are most important to native fishes and how can these 

habitats best be made useable and maintained? 

SSQ 2-1. Do dam controlled flows affect (increase or decrease) rates of erosion and vegetation growth at 

archaeological sites and TCP sites, and if so, how? 

SSQ 3-9. How do varying flows positively or negatively affect campsite attributes that are important to 

visitor experience? 

Links/Relationships to Other Projects

Because much of the biological data collected in 2000, in association with the LSSF, represent a 

single growing season or single cohort, data from subsequent years could be used to understand 

the effects of a single year on recruitment signals or species compositions in subsequent surveys. 

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These LSSF data would be linked to monitoring data from fisheries and vegetation collected 

since 2000, including the using retrospective analysis of imagery to assess change through time. 

The sediment response throughout the duration of the project can be incorporated into the current 

shoreline study project to understand the relationship of reworking eddy sand supply and 

available shoreline habitats through remote sensing analysis. In the same vein, water 

temperature data collected in 2000 is applicable to current water temperature modeling efforts 

for shoreline habitats. Lastly, recreational aspects associated with downstream travel and 

visitation could be interpreted under the current Colorado River Management Plan to determine 

how similar flows, if they occur in the future, might affect recreational experiences. 

Information Needs Addressed 

Information needs that pertain to work done during the LSSF are focused on Experimental 

Information Needs for each resource. Specific Information Needs that focus on adaptive 

management and that are pertinent to the proposed project are: 

IN 12.1. Develop information that can be used by the TWG, in collaboration with GCMRC, to establish 

current and target levels for all resources within the GCDAMP as called for in the GCDAMP strategic 

plan. 

RIN 12.3.1. As necessary, investigate the most effective methods to integrate and synthesize resource 

data. 

General Methods 

As a part of the 1994 biological opinion associated with the operations of Glen Canyon Dam, the 

Fish and Wildlife Service provided reasonable and prudent alternatives (RPAs). One element of 

the RPAs directed the Bureau of Reclamation to initiate a program of experimental dam releases 

consisting of high steady spring flows and low steady summer flows. The intention of these 

experimental releases was to reduce the risk of further jeopardizing endangered native fishes. 

A plan of flows was developed by SWCA Environmental Consultants, Inc. (SWCA, 2000). The 

plan divides the flows into three time periods: March-May (high flows of 21k cfs with a 31k cfs 

spike), June- September (steady flows of 8k cfs, ending with a 31k cfs spike), and OctoberFebruary (8k cfs flows). The flows that were implemented in spring of 2000 were slightly 

different in that the high flows in the spring were slightly lower discharge of 17,500 rather than 

21,000, and the duration of the flows was shorter by approximately a month (Fig 1). 

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GCD Hydrograph from March - December 2000

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3/1/20004/1/20005/1/20006/1/20007/1/20008/1/20009/1/2000

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Discharge

Figure 1. Hydrograph from March – December 2000 including discharge pattern associated with Low 

Steady Summer Flow Experiment 

Data collected around these flows focused on physical resources (sediment, water temperature), 

biological resources (aquatic productivity, fisheries, vegetation), and cultural resources 

(recreation, economics). SWCA (2000) provided some hypotheses regarding the benefits and 

risks to abiotic and biotic resources relative to each flow period (Table 1). It is proposed that 

these hypotheses form the basis for data consolidation, synopsis, secondary analysis and 

subsequent synthesis. 

Table 1. Hypothesized effects of flows on physical and biological resources 

Benefits/risks to 

Resources 

Period I: MarchMay Period II: JuneSeptember Period III: October - 

February 

Benefit to Physical 

resources/habitat 

-scour backwaters 

-May spike flow mobilize 

and store sands and 

sediment 

-store sand and sediment in 

river channel 

-expand campable beach area 

-September spike flow 

resuspend and store sand 

from summer tributary inputs 

Risks to physical 

resources/habitat 

-export sediment, reduce 

campsite areas 

-September spike export sand 

and sediment instead of 

storing it. 

- no significant risks 

Benefits to biotic 

resources 

-ponded tributary inflows 

as thermal refuges for 

drifting larvae and young 

fish 

-ponded tributary inflows 

ease access for spawning 

native fishes 

-destabilize habitats to 

disadvantage non-natives 

-increased growth and 

survival of young native 

fishes 

-increase autotrophic algal 

and macroinvertebrate 

production 

-possible mainstem hatching 

success 

-spike flows flush non-

-increased survival of 

young native fishes 

-maintain stable winter 

conditions to minimize 

energy expenditure 

-maintain overwinter 

autotrophic production in 

mainstem, shorelines, 

backwaters. 

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-Redistribute nutrients 

-Reset community 

production 

-Spike flows flush 

nonnative fish from 

nearshore habitats 

natives fish from nearshore 

habitats 

Risk to biotic 

resources 

-warm ponded tributaries 

attract nonnative fish 

predators/competitors 

-mainstem reproduction by 

nonnative fishes 

-increased growth and 

survival of nonnative fishes 

-increased infestation of 

parasites and diseases 

-decreased drift of food for 

fish 

-minimize thermal plume at 

30-mile may reduce survival 

of young HBC 

-increased water clarity 

leading to increased 

predation of native fish by 

sight predators 

-possible overwinter 

survival and expansion of 

nonnative fishes 

-possible greater spawning 

success of downstream 

populations of trout 

-increased predation by 

sight feeders 

-decreased drift of food for 

fish. 

Approach: The consolidation, synopsis and subsequent synthesis of data from the 2000 steady 

flows experiment will be approached in phases with each phase resulting in a stand alone 

product. 

Phase I. – Status of reports/data and synopsis (6 months) 

• Identification of plan of studies – There were 25 studies identified in the LSSF plan as 

well as several overflights conducted throughout the period of March through September. 

Determine/describe the scope of each study and how many of the proposed studies were 

executed. 

• Determination of location of data and other deliverables – call P.I.’s to determine status 

of project, location of data, identification of any work that was not done and/or cannot be 

done and consolidating data. 

• Synopsize project results and describe the status of data (metadata report). 

Phase II. Data evaluation and identification of secondary analyses (6 months) 

• Evaluation of data compatibility in collaboration with DASA and resource specialists 

within GCMRC 

• Identification of potential secondary analyses of data including incorporation more recent 

data to provide a longer term analysis of effects. Utilize proposed senior scientist to help 

identify potential and critical secondary analyses. 

• Identification of P.I.’s available for secondary analysis and collaboration determination of 

funding needs and timelines. 

• Development of statements of work for subsequent secondary analysis. 

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Phase III. Synthesis (15 months) 

• Execution of secondary analyses incorporating more recent monitoring data and 

identification of publishing venue for research (e.g., special issue in Ecological 

Applications, American Geophysical Union?). Collaborators identified in Phase II. 

• Incorporation of results into conceptual modeling exercise (e.g., Ecosim/ecopath) for 

ecosystem response analysis. Utilize talents of proposed senior scientist. 

• Writing of results and discussion of secondary analyses and conceptual modeling effort 

• In coordination with editing staff at GCMRC/SBSC, set-up review and complete draft 

manuscripts 

Phase IV. Publication (3 months) 

• In coordination with editing staff at GCMRC/SBSC complete publication of manuscripts 

in target journal or circular.

Products/Reports 

• Phase I. Open file report providing background information about LSSF, synopses of individual 

project, metadata, background information about LSSF. Draft submitted by May 2008; Finalized 

by July 2008. 

• Phase II. Work plans for secondary analysis and data report of data compatibility. 

Statements of work established for secondary analysis. Draft report submitted by October 

2008; Finalized by December 2008. 

• Phase III. Initiation of secondary analysis and collation of finalized manuscripts 

reviewed and ready for submission to target journal or circular for publication. 

Submitted by March 2009. 

• Phase IV. Completed publication of manuscripts. Completed July 2010. 

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