GCMRC Education & Outreach
Population Dynamics of Native and Nonnative Fish
Food Web Dynamics
Sediment and Sandbars
Experimental Releases
150th anniversary of J.W. Powell's first Grand Canyon expedition
This photo was taken in 2019
This photo was taken in 2019
Grand Canyon Monitoring and Research Center (GCMRC) publishes a variety of outreach products based on their measurements of the effects of Glen Canyon Dam operation on natural resources of the Colorado River from Glen Canyon Dam to Lake Mead. Check out GCMRC's Home Page for more details.
Podcasts & Videos
Podcasts & Videos
GCMRC scientists contribute to the USGS Ecosystems Misson Area's podcast Outstanding in the Field. You can also find videos we've produced with other partners in the links below.
Fact Sheets
Fact Sheets
GCMRC scientists produce fact sheets to summarize decades of important research into a short, easy to understand format.
Related Content
Filter Total Items: 15
Managing sand along the Colorado River to protect cultural sites downstream of Glen Canyon Dam
The construction of Glen Canyon Dam in northern Arizona has greatly reduced the supply of sand to the Colorado River corridor through Glen Canyon National Recreation Area and Grand Canyon National Park, hereafter referred to as Glen Canyon and Grand Canyon, respectively. This deficit has strongly affected the natural sediment cycle in this iconic landscape and has lowered the availability of windb
Authors
Terri Cook, Amy East, Helen Fairley, Joel B. Sankey
Effects of water temperature, turbidity, and rainbow trout on humpback chub population dynamics
Humpback chub (Gila cypha Miller 1946), found only in the Colorado River Basin, was one of the first species to be given full protection under the Endangered Species Act of 1973. Habitat alterations, such as changes in flow and water temperature caused by dams, and the introduction of nonnative fish have contributed to population declines in humpback chub and other native fish. These habitat alter
Authors
Charles Yackulic, Julia B. Hull
Water clarity of the Colorado River—Implications for food webs and fish communities
The closure of Glen Canyon Dam in 1963 resulted in drastic changes to water clarity, temperature, and flow of the Colorado River in Glen, Marble, and Grand Canyons. The Colorado River is now much clearer, water temperature is less variable throughout the year, and the river is much colder in the summer months. The flow—regulated by the dam—is now less variable annually, but has larger daily fluctu
Authors
Nicholas Voichick, Theodore A. Kennedy, David Topping, Ronald E. Griffiths, Kyrie Fry
Nearshore temperature findings for the Colorado River in Grand Canyon, Arizona: possible implications for native fish
Since the completion of Glen Canyon Dam, Arizona, in 1963, downstream water temperatures in the main channel of the Colorado River in Glen, Marble, and Grand Canyons are much colder in summer. This has negatively affected humpback chub (Gila cypha) and other native fish adapted to seasonally warm water, reducing main-channel spawning activity and impeding the growth and development of larval and j
Authors
Robert P. Ross, William S. Vernieu
A sand budget for Marble Canyon, Arizona: implications for long-term monitoring of sand storage change
Recent U.S. Geological Survey research is providing important insights into how best to monitor changes in the amount of tributary-derived sand stored on the bed of the Colorado River and in eddies in Marble Canyon, Arizona. Before the construction of Glen Canyon Dam and other dams upstream, sandbars in Glen, Marble, and Grand Canyons were replenished each year by sediment-rich floods. Sand input
Authors
Paul E. Grams
Native and nonnative fish populations of the Colorado River are food limited--evidence from new food web analyses
Fish populations in the Colorado River downstream from Glen Canyon Dam appear to be limited by the availability of high-quality invertebrate prey. Midge and blackfly production is low and nonnative rainbow trout in Glen Canyon and native fishes in Grand Canyon consume virtually all of the midge and blackfly biomass that is produced annually. In Glen Canyon, the invertebrate assemblage is dominated
Authors
Theodore A. Kennedy, Wyatt F. Cross, Robert O. Hall, Colden V. Baxter, Emma J. Rosi-Marshall
An experiment to control nonnative fish in the Colorado River, Grand Canyon, Arizona
The humpback chub (Gila cypha) is an endangered native fish found only in the Colorado River Basin. In Grand Canyon, most humpback chub are found in the Little Colorado River and its confluence with the Colorado River. For decades, however, nonnative rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo trutta), which prey on and compete with native fish, have dominated the Grand Canyon fish
Authors
Lewis G. Coggins,, Michael D. Yard
Three experimental high-flow releases from Glen Canyon Dam, Arizona— Effects on the downstream Colorado River ecosystem
Three high-flow experiments (HFEs) were conducted by the U.S. Department of the Interior at Glen Canyon Dam, Arizona, in March 1996, November 2004, and March 2008. Also known as artificial or controlled floods, these scheduled releases of water above the dam's powerplant capacity were designed to mimic pre-dam seasonal flooding on the Colorado River. The goal of the HFEs was to determine whether h
Authors
Theodore S. Melis, Paul E. Grams, Theodore A. Kennedy, Barbara E. Ralston, Christopher T. Robinson, John C. Schmidt, Lara M. Schmit, Richard A. Valdez, Scott A. Wright
The effects of Glen Canyon Dam operations on early life stages of rainbow trout in the Colorado River
The Lees Ferry reach of the Colorado River-a 16-mile segment from Glen Canyon Dam to the confluence with the Paria River-supports an important recreational rainbow trout (Oncorhynchus mykiss) fishery. In Grand Canyon, nonnative rainbow trout prey on and compete for habitat and food with native fish, such as the endangered humpback chub (Gila cypha). Experimental flow fluctuations from the dam duri
Authors
Josh Korman, Theodore S. Melis
Status and Trends of Resources Below Glen Canyon Dam Update - 2009
The protection of resources found in Glen Canyon National Recreation Area and Grand Canyon National Park, Arizona, emerged as a significant public concern in the decades following the completion of Glen Canyon Dam in 1963. The dam, which lies about 15 miles upstream from the park, altered the Colorado River's flow, temperature, and sediment-carrying capacity, resulting over time in beach erosion,
Authors
John F. Hamill
Status and trends of the Grand Canyon population of Humpback Chub
The Colorado River Basin supports one of the most distinctive fish communities in North America, including the federally endangered humpback chub (Gila cypha). One of only six remaining populations of this fish is found in Grand Canyon, Arizona. U.S. Geological Survey scientists and their cooperators are responsible for monitoring the Grand Canyon population. Analysis of recently collected data in
Authors
Matthew E. Andersen
Science Activities Associated with Proposed 2008 High-Flow Experiment at Glen Canyon Dam
Grand Canyon National Park lies approximately 15 miles downriver from Glen Canyon Dam, which was built on the Colorado River just south of the Arizona-Utah border. Because the dam stops most sediment moving downstream, its presence has resulted in erosion and shrinkage of river sandbars in Grand Canyon. Fewer and smaller sandbars mean smaller camping beaches for visitors to use, continued erosion
Authors
John Hamill
Related Content
- Publications
Filter Total Items: 15
Managing sand along the Colorado River to protect cultural sites downstream of Glen Canyon Dam
The construction of Glen Canyon Dam in northern Arizona has greatly reduced the supply of sand to the Colorado River corridor through Glen Canyon National Recreation Area and Grand Canyon National Park, hereafter referred to as Glen Canyon and Grand Canyon, respectively. This deficit has strongly affected the natural sediment cycle in this iconic landscape and has lowered the availability of windb
AuthorsTerri Cook, Amy East, Helen Fairley, Joel B. SankeyEffects of water temperature, turbidity, and rainbow trout on humpback chub population dynamics
Humpback chub (Gila cypha Miller 1946), found only in the Colorado River Basin, was one of the first species to be given full protection under the Endangered Species Act of 1973. Habitat alterations, such as changes in flow and water temperature caused by dams, and the introduction of nonnative fish have contributed to population declines in humpback chub and other native fish. These habitat alterAuthorsCharles Yackulic, Julia B. HullWater clarity of the Colorado River—Implications for food webs and fish communities
The closure of Glen Canyon Dam in 1963 resulted in drastic changes to water clarity, temperature, and flow of the Colorado River in Glen, Marble, and Grand Canyons. The Colorado River is now much clearer, water temperature is less variable throughout the year, and the river is much colder in the summer months. The flow—regulated by the dam—is now less variable annually, but has larger daily fluctuAuthorsNicholas Voichick, Theodore A. Kennedy, David Topping, Ronald E. Griffiths, Kyrie FryNearshore temperature findings for the Colorado River in Grand Canyon, Arizona: possible implications for native fish
Since the completion of Glen Canyon Dam, Arizona, in 1963, downstream water temperatures in the main channel of the Colorado River in Glen, Marble, and Grand Canyons are much colder in summer. This has negatively affected humpback chub (Gila cypha) and other native fish adapted to seasonally warm water, reducing main-channel spawning activity and impeding the growth and development of larval and jAuthorsRobert P. Ross, William S. VernieuA sand budget for Marble Canyon, Arizona: implications for long-term monitoring of sand storage change
Recent U.S. Geological Survey research is providing important insights into how best to monitor changes in the amount of tributary-derived sand stored on the bed of the Colorado River and in eddies in Marble Canyon, Arizona. Before the construction of Glen Canyon Dam and other dams upstream, sandbars in Glen, Marble, and Grand Canyons were replenished each year by sediment-rich floods. Sand inputAuthorsPaul E. GramsNative and nonnative fish populations of the Colorado River are food limited--evidence from new food web analyses
Fish populations in the Colorado River downstream from Glen Canyon Dam appear to be limited by the availability of high-quality invertebrate prey. Midge and blackfly production is low and nonnative rainbow trout in Glen Canyon and native fishes in Grand Canyon consume virtually all of the midge and blackfly biomass that is produced annually. In Glen Canyon, the invertebrate assemblage is dominatedAuthorsTheodore A. Kennedy, Wyatt F. Cross, Robert O. Hall, Colden V. Baxter, Emma J. Rosi-MarshallAn experiment to control nonnative fish in the Colorado River, Grand Canyon, Arizona
The humpback chub (Gila cypha) is an endangered native fish found only in the Colorado River Basin. In Grand Canyon, most humpback chub are found in the Little Colorado River and its confluence with the Colorado River. For decades, however, nonnative rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo trutta), which prey on and compete with native fish, have dominated the Grand Canyon fishAuthorsLewis G. Coggins,, Michael D. YardThree experimental high-flow releases from Glen Canyon Dam, Arizona— Effects on the downstream Colorado River ecosystem
Three high-flow experiments (HFEs) were conducted by the U.S. Department of the Interior at Glen Canyon Dam, Arizona, in March 1996, November 2004, and March 2008. Also known as artificial or controlled floods, these scheduled releases of water above the dam's powerplant capacity were designed to mimic pre-dam seasonal flooding on the Colorado River. The goal of the HFEs was to determine whether hAuthorsTheodore S. Melis, Paul E. Grams, Theodore A. Kennedy, Barbara E. Ralston, Christopher T. Robinson, John C. Schmidt, Lara M. Schmit, Richard A. Valdez, Scott A. WrightThe effects of Glen Canyon Dam operations on early life stages of rainbow trout in the Colorado River
The Lees Ferry reach of the Colorado River-a 16-mile segment from Glen Canyon Dam to the confluence with the Paria River-supports an important recreational rainbow trout (Oncorhynchus mykiss) fishery. In Grand Canyon, nonnative rainbow trout prey on and compete for habitat and food with native fish, such as the endangered humpback chub (Gila cypha). Experimental flow fluctuations from the dam duriAuthorsJosh Korman, Theodore S. MelisStatus and Trends of Resources Below Glen Canyon Dam Update - 2009
The protection of resources found in Glen Canyon National Recreation Area and Grand Canyon National Park, Arizona, emerged as a significant public concern in the decades following the completion of Glen Canyon Dam in 1963. The dam, which lies about 15 miles upstream from the park, altered the Colorado River's flow, temperature, and sediment-carrying capacity, resulting over time in beach erosion,AuthorsJohn F. HamillStatus and trends of the Grand Canyon population of Humpback Chub
The Colorado River Basin supports one of the most distinctive fish communities in North America, including the federally endangered humpback chub (Gila cypha). One of only six remaining populations of this fish is found in Grand Canyon, Arizona. U.S. Geological Survey scientists and their cooperators are responsible for monitoring the Grand Canyon population. Analysis of recently collected data inAuthorsMatthew E. AndersenScience Activities Associated with Proposed 2008 High-Flow Experiment at Glen Canyon Dam
Grand Canyon National Park lies approximately 15 miles downriver from Glen Canyon Dam, which was built on the Colorado River just south of the Arizona-Utah border. Because the dam stops most sediment moving downstream, its presence has resulted in erosion and shrinkage of river sandbars in Grand Canyon. Fewer and smaller sandbars mean smaller camping beaches for visitors to use, continued erosionAuthorsJohn Hamill