Southwest Biological Science Center

Glen Canyon Dam Adaptive Management (GCMRC Science)

More information on the science of the Grand Canyon Monitoring and Research Center can be found at: More information about the Glen Canyon Dam Adaptive Management Program (GCDAMP) can be found at the Bureau of Reclamation and the GCDAMP Wiki page. Neither of these sites are US Geological Survey (USGS) websites, so accessing those sites means you will leave the USGS website and will be entering other domains. 

Filter Total Items: 17
Image: A Rainbow Trout Rests Among Cobble Substrate in Panther Creek
Date Published: May 14, 2017

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...

Three participants in the Grand Canyon Youth Program looking at a light trap at night near the Colorado River in Grand Canyon
Date Published: January 18, 2017

Aquatic insects are commonly used to gauge the health of stream and river ecosystems, yet collecting enough samples to adequately characterize a river segment as long as the Colorado River through Grand Canyon (> 250 miles) would be essentially impossible using traditional sampling methods. Since 2012, our group has been collaborating with river guides, private boaters, and educational...

A boat on the Colorado River in front of a rock outcrop containing a concrete structure.
Date Published: January 18, 2017

Algae, phytoplankton, and rooted macrophytes represent the base of many aquatic food webs and are known as primary producers. Through photosynthesis, these organisms convert sunlight energy into chemical energy (i.e., carbon) that in turn fuels the growth of animals such as macroinvertebrates and fish. This project uses high frequency measurements of dissolved oxygen, which is a by-product of...

Brown, sediment-laden water of the Paria River mixes with the clear water of the Colorado River
Date Published: December 30, 2016

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...

A view of the lower Little Colorado River showing the light blue color of the river, riparian grasses, and canyon walls.
Date Published: December 23, 2016

Construction of Glen Canyon Dam has led to large changes in environmental conditions of the downriver Colorado River. Whereas the pre-dam Colorado River experienced large seasonal variation in temperature and discharge and was highly turbid, the post-dam Colorado River is far less variable in terms of temperature and discharge and is frequently clear. Many nonnative fish species had already...

Two USGS researchers on a small boat in the Colorado River sampling aquatic insects with a net.
Date Published: December 23, 2016

Rainbow trout is a desirable sport fish that has been introduced in many locations around the world. Although introductions of rainbow trout and other nonnative fishes provide recreational fishing opportunities, they also pose threats to native fish populations. The Glen Canyon Dam Adaptive Management Program has tasked scientists and managers with identifying management options that allow...

Northern leopard frog floating in the water in Glen Canyon.
Date Published: December 22, 2016

Click on "Science" to go to the SBSC scientist directory. When you click on a scientist's name (you may need to scroll down to see all the names), you will be taken to that scientist's professional page and contact information. 

Colorado River at Basalt Rapids. Foreground shows eddy sandbar and sand dune sediment deposits.
Date Published: December 22, 2016

We study the links among different geomorphic processes that affect river valley landscapes in the Colorado River downstream from Glen Canyon Dam, Arizona. Dam-released flows affect the deposition and retention of sandbars that serve as sources for other sand resources, such as windblown sand dunes, throughout the Colorado River ecosystem. The degree to which the landscapes are differentially...

Four glass containers showing low turbidity water to highly turbid (cloudy) water
Date Published: December 21, 2016

Introduced rainbow trout and brown trout are considered a threat to the endangered humpback chub in the Colorado River in Grand Canyon. These introduced species eat native fish, but impacts are difficult to assess because predation vulnerability depends on the physical conditions under which predation takes place. We studied how predation vulnerability of juvenile humpback chub changes in...

Image taken from above depicting the confluence of the Colorado River and the Little Colorado River.
Date Published: December 20, 2016

Riparian vegetation has increased dramatically along the Colorado River downstream of Glen Canyon Dam since the closure of the dam in 1963. The spatial patterns and temporal rates of vegetation increase occur due to changes in river hydrology, dam operations, and climate. The increase in vegetation, particularly onto otherwise bare sandbars, has impacted recreational, geomorphological,...

Anglers departing the boat dock at Lees Ferry, AZ with canyon walls in the background.
Date Published: December 15, 2016

Economic research at Grand Canyon Monitoring and Research Center is used to determine economic benefits of outdoor recreation in Glen Canyon National Recreation Area below Glen Canyon Dam and in Grand Canyon National Park, as affected by operation of Glen Canyon Dam. This research identifies recreationists’ preferences for attributes associated with their trips, spending that occurs regionally...

USGS researcher on small boat holding the end of a net used to capture insects in the water.
Date Published: December 9, 2016

All aquatic invertebrates drift downstream at some point in their life cycle. Invertebrates may drift to find more preferable habitats, to leave the water during their transition from aquatic larvae to terrestrial adults, or accidentally such as when swept off the river bed by a flood. Regardless, when they enter the drift, invertebrates become particularly susceptible to predation by several...