Entrainment

Entrainment of warmwater nonnative fish through Glen Canyon Dam When the reservoir was cold (<10 °C) and well-mixed, most fishes selected gently sloping habitat such as that found in Wahweap Bay (5 km from GCD), and thus winter entrainment risk is low for most species. When the reservoir was stratified (>20 °C surface temp.) fish were active in the forebay epilimnion within meters of the dam, increasing entrainment when the dam penstock is positioned within the epilimnion, as it was during our study, rather than below the thermocline when the reservoir water level is higher. Smallmouth Bass Micropterus dolomieu) may survive entrainment at rates above 50% at low water levels, with survival expected to decrease as the water level rises, but remaining problematically high across all water levels where entrainment is expected. Other fishes may survive entrainment at higher rates, depending on physiology. Minimizing successful nonnative fish passage through GCD is best achieved through maintenance of water levels higher than those in 2022 and 2023, which would decrease both entrainment and survival of entrainment. [1]

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Updates

Links Temperature Control Page Smallmouth Bass Page Green Sunfish Page Striped Bass Page Projects Friesen, Barrett T., "Invasion Potential of Nonnative Fishes Through a Large Western Dam Into a Prized and Vulnerable Ecosystem" (2024). All Graduate Theses and Dissertations, Fall 2023 to Present. 288. https://digitalcommons.usu.edu/etd2023/288 Presentations and Papers 2024 Hydroacoustic Monitoring 2023 Characterizing the fish assemblage in the Lake Powell forebay and identifying the potential for nonnative fish escapement into the Lower Colorado River Hydroacoustic Fish Distribution Characterizing the fish assemblage in the Lake Powell forebay and identifying the potential for nonnative fish escapement into the Lower Colorado River Glen Canyon Dam Fish Exclusion: Project Overview 2022 Hydroacoustic Fish Distribution Glen Canyon Dam Fish Escapement Options Glen Canyon Dam Fish Escapement Report Characterizing the fish assemblage of the Lake Powell forebay: identifying the potential for nonnative fish escapement through Glen Canyon Dam and into the lower Colorado River Hydroacoustic Fish Distribution - Lake Powell 2022 Characterizing the fish assemblage of the Lake Powell forebay: identifying the potential for nonnative fish escapement through Glen Canyon Dam and into the lower Colorado River Glen Canyon Fish Escapement Options 2021 Existing and Planned Monitoring of Non-Native Aquatic Species in Lake Powell and Below Glen Canyon Dam Lake Powell Fish Monitoring Study 2021 -2024 Other Stuff