Glen Canyon National Recreation Area To Undertake River Mile 12 Channelization Project

Glen Canyon National Recreation Area has announced plans to begin construction on a slough channelization project at River Mile -12 on the Colorado River. This effort, set to start on March 1, 2025, aims to prevent the reproduction of high-risk, warm water, non-native fish, particularly smallmouth bass and green sunfish. The project is expected to be completed by June, with equipment staging beginning as early as February 26. While river access may be temporarily restricted during staging, further details about potential delays will be posted on the park’s website.

River Mile -12 is located three miles below Glen Canyon Dam and 12 miles upstream from Lees Ferry, Arizona. The presence of non-native fish in Glen Canyon, Marble Canyon, and Grand Canyon threatens native and federally listed fish species such as the humpback chub and razorback sucker, as well as the region’s rainbow trout sport fishery. Recent years of lower Lake Powell elevations have allowed these invasive species to pass through Glen Canyon Dam, with warmer outflow temperatures enabling their reproduction. By modifying the slough, the National Park Service aims to reduce the likelihood of non-native fish expanding further downstream.

The channelization project was analyzed in the Warmwater Nonnative Fish Management Plan/Environmental Assessment (EA), which was open for public comment in September 2024. The park reviewed all feedback before issuing a Finding of No Significant Impact (FONSI), ensuring the project aligns with the National Environmental Policy Act’s requirements.

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This initiative represents an important step in protecting the ecological balance of the Colorado River while preserving the habitat for native species.