The Grand Canyon Monitoring and Research Center currently functions under a Triennial Work Plan (TWP) which is thoroughly reviewed and vetted both internally within the Center and through the GCDAMP Technical Work Group (TWG) and the Adaptive Management Work Group (AMWG). These advisory panels have been a part of the Glen Canyon Dam adaptive management process since the inception of the GCDAMP. For more information on the adaptive management process, please see the GCDAMP Page.
Physical Resources

GCMRC has on-going monitoring and research focused on river sediment dynamics, long-term monitoring of sediment resources in the Colorado River corridor, and understanding the connectivity of sand resources throughout the system.
Biological Resources

Several GCMRC projects focus on understanding the biological processes of the Colorado River, the effect of dam operations on both native and nonnative species, population dynamics of important species, and the terrestrial-biological interactions.
Socio-Economic and Cultural

GCMRC is also concerned with understanding the socio-economic values of the Colorado River in Grand Canyon, the unique recreational opportunites this environment offers and the cultural significance observed by the Tribal people of this the region.
Administrative History and Guidance That Informs GCMRC Projects
The work plan for fiscal years 2018 to 2020 (FY18-20 TWP) is compromised of eleven active science projects that align with the needs of the GCDAMP stakeholders. Each project described in the FY2018–20 TWP is organized around monitoring and research themes that are associated with the eleven resource goals identified in the LTEMP ROD: archaeological and cultural resources, natural processes, humpback chub, hydropower and energy, other native fish, recreational experience, sediment, tribal resources, rainbow trout fishery, nonnative invasive species, and riparian vegetation (U.S. Department of the Interior, 2016a; Attachment A).
The monitoring and research projects are responsive to guidance provided in the LTEMP ROD, which, in addition to identifying the priority resources, also identifies flow and non-flow experimental actions and compliance obligations for Glen Canyon Dam operations for the 20 years of the LTEMP. Additional guidance comes from the Science Plan developed by GCMRC (VanderKooi and others, 2017) in support of the LTEMP ROD which describes a general strategy for monitoring and research needed in support of implementation of operations and experimental actions.
Projects in the current TWP have been informed by and build upon previous research and monitoring projects that were responsive to guidance vetted through the GCDAMP and the Secretary of Interior’s office. While the LTEMP ROD defines broad resource goals and identifies new experimental actions and compliance requirements, some of the older guidance continues to have relevance for certain aspects of the current science program and continues to influence current research and monitoring directions in a general sense. Among this older guidance, the following documents describe the history of GCDAMP decisions and direction and help maintain continuity with GCDAMP goals as LTEMP is implemented:
- 2001 Glen Canyon Dam Adaptive Management Program draft strategic plan (Glen Canyon Dam Adaptive Management Program, 2001),
- 2007 Strategic Science Plan and Strategic Science Questions (SSQs) (U. S. Geological Survey, 2007),
- 2011 draft Core Monitoring Plan (U. S. Geological Survey, 2011), and
- 2012 AMWG Desired Future Conditions.
Monitoring and research themes described in these and other GCDAMP administrative documents have persisted throughout the life of the GCDAMP and are carried forward into the LTEMP. They include:
(1) recovery of the endangered humpback chub (Gila cypha) and maintenance of populations of other native fish;
(2) maintenance or improvement of the physical template, especially regarding fine sediment;
(3) maintenance of culturally important sites, especially those that are of archaeological and historical significance under the National Historic Preservation Act
(4) maintenance of the food base on which the native fish community depends;
(5) maintenance of a high-quality sport fishery in the Lees Ferry reach; and
(6) maintenance of the native riparian vegetation community.
The various goals, questions, information needs, and desired future conditions developed by GCDAMP committees also recognize the importance of maintaining high quality opportunities and conditions for recreational boaters and campers, and the role played by nonnative riparian vegetation in providing habitat for some desired fauna such as the endangered Southwestern willow flycatcher.
Below are science projects associated with GCMRC work plans.
Bug Flows: Improving Food Web Health on the Colorado River
Airborne Remote Sensing in Grand Canyon
Is timing really everything? Evaluating Resource Response to Spring Disturbance Flows
River Sediment Dynamics
River Geomorphology and Geomorphic Change
Sediment Storage in Grand Canyon
River Campsites in Grand Canyon National Park
Geospatial Science and Technology
High-Flow Experiments on the Colorado River
Terrestrial Riparian Vegetation Monitoring: How One Square Meter Can Tell the Story of 245 River Miles
Overview of Riparian Vegetation in Grand Canyon
Rainbow Trout Abundance and Movement in the Colorado River in Grand Canyon
Below are data associated with GCMRC-specific projects.
These data will be updated soon - in progress.
Colorado River Eddy Sandbar Dynamics Data
Riparian species vegetation classification data for the Colorado River within Grand Canyon derived from 2013 airborne imagery
Geomorphic Change-Sediment Transport Data for the Little Colorado River, Arizona, USA
Sand classifications along the Colorado River in Grand Canyon derived from 2002, 2009, and 2013 high-resolution multispectral airborne imagery
Below are publications associated with research and projects by the Grand Canyon Monitoring and Research Center (GCMRC). Note that not all of the publications listed here are funded under the Glen Canyon Dam Adaptive Management Program (GCDAMP).
To access all of SBSC's publications, click the link below.
Taxonomic identity, biodiversity, and antecedent disturbances shape the dimensional stability of stream invertebrates
Terrestrial lidar monitoring of the effects of Glen Canyon Dam operations on the geomorphic condition of archaeological sites in Grand Canyon National Park, 2010–2020
Provenance, genotype, and flooding influence growth and resource acquisition characteristics in a clonal, riparian shrub
The influence of drying on the aeolian transport of river-sourced sand
Drought related changes in water quality surpass effects of experimental flows on trout growth downstream of Lake Powell reservoir
Mapping 2-D bedload rates throughout a sand-bed river reach from high-resolution acoustical surveys of migrating bedforms
The hydroclimate niche: A tool for predicting and managing riparian plant community responses to streamflow seasonality
The Colorado River – The science-policy interface
The Grand Caddis hatch of JASM 2022: Trichoptera natural history observations at the Joint Aquatic Sciences Meeting in Grand Rapids, Michigan (USA)
Channel mapping of the Colorado River from Glen Canyon Dam to Lees Ferry in Glen Canyon National Recreation Area, Arizona
Measuring and attributing sedimentary and geomorphic responses to modern climate change: Challenges and opportunities
Field investigation of sub-isokinetic sampling by the US D-96-type suspended-sediment sampler and its effect on suspended-sediment measurements
Predicted Shorelines for High Flows on the Colorado River Application
This application highlights modeled flows of the Colorado River for a discharge of 41,000 cubic feet per second (cfs) that is approximate to recent (2012 - 2018) and future anticipated water releases associated with a High Flow Experiments conducted from Glen Canyon Dam near Page, Arizona. These data are to help visualize the water levels during High Flow Events in relation to othe
APPLICATION - Discharge, Sediment, and Water Quality Monitoring Application
This link launches the Grand Canyon Monitoring and Research Center’s discharge, sediment and water quality monitoring application gateway. Sediment and water quality information can be accessed from here for our on-going monitoring taking place across the Southwest U.S.
APPLICATION - Grand Canyon Sandbar Monitoring
Several applications related to the Grand Canyon Monitoring and Research Center’s long-term sandbar monitoring project can be accessed here, including the sandbar area and volume tool and applications highlighting changes to sandbars as a result of High-Flow Events (HFEs) conducted by Glen Canyon Dam near Page, Arizona.
APPLICATION - Grand Canyon Aquatic Ecology Web Application
This application allows for the exploration of a select set of insect emergence data collected as part of a citizen science project initiated by the Grand Canyon Monitoring and Research Center (GCMRC). Data present in this application relate to a recent BioScience publication from USGS scientists and collaborators that investigated the effects of dam operations on downstream aquatic insects.
Below are news items about GCMRC's science.
- Overview
The Grand Canyon Monitoring and Research Center currently functions under a Triennial Work Plan (TWP) which is thoroughly reviewed and vetted both internally within the Center and through the GCDAMP Technical Work Group (TWG) and the Adaptive Management Work Group (AMWG). These advisory panels have been a part of the Glen Canyon Dam adaptive management process since the inception of the GCDAMP. For more information on the adaptive management process, please see the GCDAMP Page.
Physical ResourcesGCMRC has on-going monitoring and research focused on river sediment dynamics, long-term monitoring of sediment resources in the Colorado River corridor, and understanding the connectivity of sand resources throughout the system.
Biological ResourcesSeveral GCMRC projects focus on understanding the biological processes of the Colorado River, the effect of dam operations on both native and nonnative species, population dynamics of important species, and the terrestrial-biological interactions.
Socio-Economic and CulturalGCMRC is also concerned with understanding the socio-economic values of the Colorado River in Grand Canyon, the unique recreational opportunites this environment offers and the cultural significance observed by the Tribal people of this the region.
Administrative History and Guidance That Informs GCMRC Projects
The work plan for fiscal years 2018 to 2020 (FY18-20 TWP) is compromised of eleven active science projects that align with the needs of the GCDAMP stakeholders. Each project described in the FY2018–20 TWP is organized around monitoring and research themes that are associated with the eleven resource goals identified in the LTEMP ROD: archaeological and cultural resources, natural processes, humpback chub, hydropower and energy, other native fish, recreational experience, sediment, tribal resources, rainbow trout fishery, nonnative invasive species, and riparian vegetation (U.S. Department of the Interior, 2016a; Attachment A).
The monitoring and research projects are responsive to guidance provided in the LTEMP ROD, which, in addition to identifying the priority resources, also identifies flow and non-flow experimental actions and compliance obligations for Glen Canyon Dam operations for the 20 years of the LTEMP. Additional guidance comes from the Science Plan developed by GCMRC (VanderKooi and others, 2017) in support of the LTEMP ROD which describes a general strategy for monitoring and research needed in support of implementation of operations and experimental actions.
Projects in the current TWP have been informed by and build upon previous research and monitoring projects that were responsive to guidance vetted through the GCDAMP and the Secretary of Interior’s office. While the LTEMP ROD defines broad resource goals and identifies new experimental actions and compliance requirements, some of the older guidance continues to have relevance for certain aspects of the current science program and continues to influence current research and monitoring directions in a general sense. Among this older guidance, the following documents describe the history of GCDAMP decisions and direction and help maintain continuity with GCDAMP goals as LTEMP is implemented:
- 2001 Glen Canyon Dam Adaptive Management Program draft strategic plan (Glen Canyon Dam Adaptive Management Program, 2001),
- 2007 Strategic Science Plan and Strategic Science Questions (SSQs) (U. S. Geological Survey, 2007),
- 2011 draft Core Monitoring Plan (U. S. Geological Survey, 2011), and
- 2012 AMWG Desired Future Conditions.
Monitoring and research themes described in these and other GCDAMP administrative documents have persisted throughout the life of the GCDAMP and are carried forward into the LTEMP. They include:
(1) recovery of the endangered humpback chub (Gila cypha) and maintenance of populations of other native fish;
(2) maintenance or improvement of the physical template, especially regarding fine sediment;
(3) maintenance of culturally important sites, especially those that are of archaeological and historical significance under the National Historic Preservation Act
(4) maintenance of the food base on which the native fish community depends;
(5) maintenance of a high-quality sport fishery in the Lees Ferry reach; and
(6) maintenance of the native riparian vegetation community.
The various goals, questions, information needs, and desired future conditions developed by GCDAMP committees also recognize the importance of maintaining high quality opportunities and conditions for recreational boaters and campers, and the role played by nonnative riparian vegetation in providing habitat for some desired fauna such as the endangered Southwestern willow flycatcher.
- Science
Below are science projects associated with GCMRC work plans.
Filter Total Items: 21Bug Flows: Improving Food Web Health on the Colorado River
Native and desired nonnative fish downstream of Glen Canyon Dam are food limited—meaning that if more or larger invertebrate food items were available, there would be more and larger fish. Aquatic insects have complex life cycles that include egg, larvae, and pupal stages that are aquatic while adults have wings and are typically terrestrial. Aquatic insects are a fundamental component of river...Airborne Remote Sensing in Grand Canyon
A high-resolution image collection in 2021 will be the most recent in a rich archive of aerial imagery that is used to track changes of the Colorado River in the Grand Canyon. Imagery will be acquired from an airplane in Grand Canyon National Park along the Colorado River corridor and the Little Colorado River starting Memorial Day weekend and continuing through the first week of June 2021. This...Is timing really everything? Evaluating Resource Response to Spring Disturbance Flows
Glen Canyon Dam has altered ecological processes of the Colorado River in Grand Canyon. Before the dam was built, the Colorado River experienced seasonable variable flow rates, including springtime flooding events. These spring floods scoured the river bottom and enhanced natural processes that sustained the Colorado River ecosystem. Since the dam’s construction in 1963, springtime floods have...River Sediment Dynamics
Sediment controls the physical habitat of river ecosystems. Changes in the amount and areal distribution of different sediment types cause changes in river-channel form and river habitat. The amount and type of sediment suspended in the water column determines water clarity. Understanding sediment transport and the conditions under which sediment is deposited or eroded from the various...River Geomorphology and Geomorphic Change
River channels and their adjacent floodplains are ever evolving in form and composition in response to changing patterns of streamflow, the quantity and size of supplied sediment, and feedbacks with the riparian and aquatic ecosystems. Changes in channel form affect aquatic and riparian habitats, which are important for plants, animals, and insects. Erosion and deposition of river channels and...Sediment Storage in Grand Canyon
The sandbars exposed along the shoreline of the Colorado River represent only a small fraction of the sand deposits in Grand Canyon, most of which are on the bed of the river in eddies and the channel. Current management practice includes efforts to maintain and build sandbars by releasing high flows from Glen Canyon Dam that are timed to coincide with periods of fine-sediment supply from...River Campsites in Grand Canyon National Park
Sandbars have been used as campsites by river runners and hikers since the first expeditions to the region more than 100 years ago. Sandbar campsites continue to be an important part of the recreational experience for the more than 25,000 hikers and river runners that visit the Colorado River corridor each year. Because the Colorado River is dominated by bedrock cliffs and steep talus slopes...Geospatial Science and Technology
The U.S. Geological Survey’s Southwest Biological Science Center, and more specifically, its River Ecosystem Science branch which includes the Grand Canyon Monitoring and Research Center (GCMRC), is a preeminent science group that has more than 20 years of experience of providing high-quality, detailed science to resource managers and stakeholders primarily concerned with the effects of dam...High-Flow Experiments on the Colorado River
Glen Canyon Dam has altered flow and fine sediment (sand, silt, and clay) dynamics of the Colorado River in Grand Canyon. Before the dam, the Colorado River experienced highly variable flows and carried a large amount of sediment through Grand Canyon, which maintained sandbars (highly valued camping areas in Grand Canyon) and provided sand that protected archeological and cultural sites from...Terrestrial Riparian Vegetation Monitoring: How One Square Meter Can Tell the Story of 245 River Miles
The goal of Grand Canyon Monitoring and Research Center’s (part of the Southwest Biological Science Center) riparian vegetation monitoring program is to assess changes and trends in plant species composition and cover and relate those changes to Glen Canyon Dam operations, river hydrology, climate, and geomorphology. Monitoring is done by annual field-data collection on plant cover and diversity...Overview of Riparian Vegetation in Grand Canyon
Riparian areas are conspicuous belts of dense, green vegetation along streams and rivers, and can be considered “ribbons of life”. Despite covering less than 2 percent of the land area in the southwestern U.S., riparian areas tend to have high species diversity and population density, making them valuable to managers, scientists, and the public. These unique ecosystems act as a link between dry...Rainbow Trout Abundance and Movement in the Colorado River in Grand Canyon
Just below Glen Canyon Dam on the Colorado River is a very popular Blue Ribbon trout fishery known for its rainbow trout. However, approximately 78 miles downstream, near were the Little Colorado River flows into the Colorado River, is a population of endangered humpback chub. The introduced rainbow trout can negatively affect native humpback chub by competing with them for food (immature black... - Data
Below are data associated with GCMRC-specific projects.
These data will be updated soon - in progress.
Colorado River Eddy Sandbar Dynamics Data
These data are a compilation of the characteristics of eddy sandbars, eddy sandbar areas and volumes measured between 1990 and 2015, and longitudinal metrics of the Colorado River in Grand Canyon National Park, Arizona. These data were used to evaluate the response of sandbars to controlled floods implemented in 1996, 2004, 2008, 2012, 2013, and 2014. These data were also used to characterize theRiparian species vegetation classification data for the Colorado River within Grand Canyon derived from 2013 airborne imagery
These data are a species-level classification map of riparian vegetation in the Colorado River riparian corridor in Grand Canyon, Arizona, USA. The classification is derived from 0.2 m pixel resolution multispectral aerial imagery acquired in May 2013. The classification spans the riparian zone of the river corridor between Glen Canyon Dam near Page, Arizona, and Lake Mead at Pearce Ferry, ArizonaGeomorphic Change-Sediment Transport Data for the Little Colorado River, Arizona, USA
These data were compiled to accompany flow modeling work on Little Colorado river above the mouth (USGS gage 09402300). The data include topographic data collected by LIDAR and total station in June 2017, high water marks from nine historic floods, and control points and gage structures. Topographic data include ground topography collected by LIDAR and channel bathymetry collected by total stationSand classifications along the Colorado River in Grand Canyon derived from 2002, 2009, and 2013 high-resolution multispectral airborne imagery
These data are remote sensing image-based classification maps of unvegetated river-derived sand along the Colorado River. One map is based on imagery acquired in May 2013 and is a classification of sand located above the wetted river channel in the imagery which was acquired at the approximate contemporary low-flow river discharge of 8,000 cubic feet per second (227 cubic meters per second) and ex - Multimedia
- Publications
Below are publications associated with research and projects by the Grand Canyon Monitoring and Research Center (GCMRC). Note that not all of the publications listed here are funded under the Glen Canyon Dam Adaptive Management Program (GCDAMP).
To access all of SBSC's publications, click the link below.
Filter Total Items: 296Taxonomic identity, biodiversity, and antecedent disturbances shape the dimensional stability of stream invertebrates
The “dimensional stability” approach measures different components of ecological stability to investigate how they are related. Yet, most empirical work has used small-scale and short-term experimental manipulations. Here, we apply this framework to a long-term observational dataset of stream macroinvertebrates sampled between the winter flooding and summer monsoon seasons. We test hypotheses thatTerrestrial lidar monitoring of the effects of Glen Canyon Dam operations on the geomorphic condition of archaeological sites in Grand Canyon National Park, 2010–2020
The U.S. Geological Survey’s Grand Canyon Monitoring and Research Center, in coordination with the Glen Canyon Dam Adaptive Management Program, has monitored the geomorphic condition of select archaeological sites along the Colorado River in Grand Canyon using high-resolution terrestrial light detection and ranging (lidar) topographic surveys. Many of these sites are vulnerable to degradation by nProvenance, genotype, and flooding influence growth and resource acquisition characteristics in a clonal, riparian shrub
PremiseRiparian plants can exhibit intraspecific phenotypic variability across the landscape related to temperature and flooding gradients. Phenotypes that vary across a climate gradient are often partly genetically determined and may differ in their response to inundation. Changes to inundation patterns across a climate gradient could thus result in site-specific inundation responses. PhenotypicThe influence of drying on the aeolian transport of river-sourced sand
Transgression and regression of water levels (stages) have impacted the evolution of aeolian landforms and sedimentary deposits throughout geologic history. We studied this phenomenon over a five-day period of reduced flow on the Colorado River in Grand Canyon National Park, AZ, USA, in March 2021. These transient low flows exposed river-channel sand deposits to the air, causing progressive desiccDrought related changes in water quality surpass effects of experimental flows on trout growth downstream of Lake Powell reservoir
Flows released from reservoirs are often modified to mitigate the negative ecosystem effects of dams. We estimated the effects of two experimental flows, fall-timed floods and elimination of sub-daily variation in flows on weekends, on growth rates of rainbow trout (Oncorhynchus mykiss) in the Colorado River downstream from Glen Canyon Dam. Experimental flow effects were compared to effects of watMapping 2-D bedload rates throughout a sand-bed river reach from high-resolution acoustical surveys of migrating bedforms
This paper introduces a method for determining spatially-distributed, 2-D bedload rates using repeat, high-resolution surveys of the bed topography. As opposed to existing methods, bedform parameters and bedload rates are computed from bed elevation profiles interpolated along the local bedform velocities. The bedform velocity fields are computed applying Large-Scale Particle Image Velocimetry, inThe hydroclimate niche: A tool for predicting and managing riparian plant community responses to streamflow seasonality
Habitat suitability is a consequence of interacting environmental factors. In riparian ecosystems, suitable plant habitat is influenced by interactions between stream hydrology and climate, hereafter referred to as “hydroclimate”. We tested the hypothesis that hydroclimate variables would improve the fit of ecological niche models for a suite of riparian species using occurrence data from the westThe Colorado River – The science-policy interface
No abstract available.The Grand Caddis hatch of JASM 2022: Trichoptera natural history observations at the Joint Aquatic Sciences Meeting in Grand Rapids, Michigan (USA)
In a stroke of good luck for aquatic scientists and insect enthusiasts, the May 2022 Joint Aquatic Sciences Meeting (JASM) in Grand Rapids, Michigan coincided with a spectacular hatch of hydropsychid caddisflies. To estimate density, we enumerated caddisflies on 12 polarized window panels on the western face of the DeVos Place, which faced the Grand River. We found an average of 57.8 caddisflies pChannel mapping of the Colorado River from Glen Canyon Dam to Lees Ferry in Glen Canyon National Recreation Area, Arizona
Bathymetric and topographic data were collected from May 2013 to February 2016 along the 15.84-mile reach of the Colorado River spanning from Glen Canyon Dam to Lees Ferry in Glen Canyon National Recreation Area, Arizona. Channel bathymetry was mapped using multibeam and singlebeam echo sounders; subaerial topography was mapped using a combination of ground-based total stations and aerial photograMeasuring and attributing sedimentary and geomorphic responses to modern climate change: Challenges and opportunities
Today, climate change is affecting virtually all terrestrial and nearshore settings. This commentary discusses the challenges of measuring climate-driven physical landscape responses to modern global warming: short and incomplete data records, land use and seismicity masking climatic effects, biases in data availability and resolution, and signal attenuation in sedimentary systems. We identify oppField investigation of sub-isokinetic sampling by the US D-96-type suspended-sediment sampler and its effect on suspended-sediment measurements
Collection of accurate suspended-sediment data using depth-integrating samplers requires that they operate isokinetically, that is, that they sample at the local stream velocity unaffected by the presence of the suspended-sediment sampler. Sub-isokinetic suspended-sediment sampling causes grain-size dependent positive biases in the suspended-sediment concentration measured by the suspended-sedimen - Web Tools
Predicted Shorelines for High Flows on the Colorado River Application
This application highlights modeled flows of the Colorado River for a discharge of 41,000 cubic feet per second (cfs) that is approximate to recent (2012 - 2018) and future anticipated water releases associated with a High Flow Experiments conducted from Glen Canyon Dam near Page, Arizona. These data are to help visualize the water levels during High Flow Events in relation to othe
APPLICATION - Discharge, Sediment, and Water Quality Monitoring Application
This link launches the Grand Canyon Monitoring and Research Center’s discharge, sediment and water quality monitoring application gateway. Sediment and water quality information can be accessed from here for our on-going monitoring taking place across the Southwest U.S.
APPLICATION - Grand Canyon Sandbar Monitoring
Several applications related to the Grand Canyon Monitoring and Research Center’s long-term sandbar monitoring project can be accessed here, including the sandbar area and volume tool and applications highlighting changes to sandbars as a result of High-Flow Events (HFEs) conducted by Glen Canyon Dam near Page, Arizona.
APPLICATION - Grand Canyon Aquatic Ecology Web Application
This application allows for the exploration of a select set of insect emergence data collected as part of a citizen science project initiated by the Grand Canyon Monitoring and Research Center (GCMRC). Data present in this application relate to a recent BioScience publication from USGS scientists and collaborators that investigated the effects of dam operations on downstream aquatic insects.
- News
Below are news items about GCMRC's science.