Nearshore thermal gradients of the Colorado River near the Little Colorado River confluence, Grand Canyon National Park, Arizona, 2010

Ross, Rob; Grams, Paul E.

Abstract:

Construction and operation of Glen Canyon Dam has dramatically impacted the flow of the Colorado River through Glen, Marble, and Grand Canyons. Extremes in both streamflow and water temperature have been suppressed by controlled releases from the dam. Trapping of sediment in Lake Powell, the reservoir formed by Glen Canyon Dam, has also dramatically reduced the supply of suspended sediment entering the system. These changes have altered the riverine ecosystem and the habitat of native species, including fish such as the endangered humpback chub (Gila cypha). Most native fish are adapted to seasonally warm water, and the continuous relatively cold water released by the dam is one of the factors that is believed to limit humpback chub growth and survival. While average mainstem temperatures in the Colorado River are well documented, there is limited understanding of temperatures in the nearshore environments that fish typically occupy. Four nearshore geomorphic unit types were studied between the confluence of the Colorado and Little Colorado Rivers and Lava Canyon in the summer and fall of 2010, for study periods of 10 to 27 days. Five to seven sites were studied during each interval. Persistent thermal gradients greater than the 0.2 °C accuracy of the instruments were not observed in any of the sampled shoreline environments. Temperature gradients between the shoreline and mainstem on the order of 4 °C, believed to be important to the habitat-seeking behavior of native or nonnative fishes, were not detected.

Genre:

USGS Numbered Series

ProdID:

70044254

Citation Author:

Ross, Rob; Grams, Paul E.

Citation Contributing Office:

Southwest Biological Science Center

Citation Datum:

North American Datum 1983

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Citation Language:

English

Citation Larger Work Title:

Citation LatN:

37.5

Citation LatS:

Citation LonE:

110

Citation LonW:

114.5

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Citation Phsyical Description:

Report: v, 65 p.; Appendix B workbook files

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Citation Publisher:

U.S. Geological Survey

Citation Series:

Open-File Report

Citation Series Code:

OFR

Citation Series Number:

2013-1013

Citation Search Results Text:

Nearshore thermal gradients of the Colorado River near the Little Colorado River confluence, Grand Canyon National Park, Arizona, 2010; 2013; OFR; 2013-1013; Ross, Rob; Grams, Paul E.

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Citation Volume:

Citation Year:

2013

Type:

citation/reference

Text:

Nearshore thermal gradients of the Colorado River near the Little Colorado River confluence, Grand Canyon National Park, Arizona, 2010; 2013; OFR; 2013-1013; Ross, Rob; Grams, Paul E.