Cooperative Fish and Wildlife Research Units Program: Utah
Education, Research and Technical Assistance for Managing Our Natural Resources

Utah Project

Characterizing the fish assemblage of the Lake Powell forebay: identifying the potential for non-native fish escapement and entrainment into Glen Canyon Dam and potential for establishment in the Glen, Marble, and Grand Canyon.

October 2021 - September 2023


Participating Agencies

  • Bureau of Recalmation

As lake elevation in Lake Powell (UT-AZ) continues to decline to historically low levels, near-surface waters are approaching the penstock elevation (3,470 feet above sea level) of Glen Canyon Dam. These conditions may make it easier for the non-native fish assemblage to escape through the penstocks and make it downstream of Lake Powell into Glen Canyon, Marble Canyon, and Grand Canyon. If so, these non-native fishes could threaten native fishes downstream of Glen Canyon Dam. Non-native fishes have been captured below the dam in the tailwater area and downstream to Lee’s Ferry, some (e.g., green sunfish Lepomis cyanellus) may be reproducing naturally in the slough below the dam but likely would have originated from Lake Powell, and other captured fishes (e.g., smallmouth bass Micropterus dolomieu, walleye Sander vitreus) also have the potential to have escaped.