PAGE, Ariz. – The National Park Service (NPS) is initiating a Draft Environmental Assessment (EA) to analyze Glen Canyon National Recreation Area’s (Glen Canyon) proposed Colorado River slough channelization project at River Mile -12.  River Mile -12 is located on the Colorado River three miles below Glen Canyon Dam and 12 miles upriver from Lees Ferry, Ariz. This EA will consider channelizing the slough to help prevent successful reproduction of high-risk, warm-water, non-native fish, particularly smallmouth bass and green sunfish. 

The presence of non-native fish in Glen Canyon, Marble Canyon, and Grand Canyon threatens the populations of native and federally listed fish species, including the humpback chub and razorback sucker, and the rainbow trout sport fishery. Non-native fish are passing through Glen Canyon Dam due to lower Lake Powell surface elevations. Lower lake levels in 2022 and 2023 resulted in higher dam outflow temperatures, leading to smallmouth bass and green sunfish reproduction below the dam. Reducing reproduction in the River Mile -12 Slough could help reduce the likelihood of downstream expansion and establishment in Glen Canyon, Marble Canyon, and Grand Canyon. 

The draft EA is being prepared in compliance with the National Environmental Policy Act (NEPA) to provide a decision-making framework that effectively evaluates potential issues and impacts to the area’s resources and values. The project is currently in the pre-NEPA phase. 

To assist the public in understanding the upcoming proposed action, the NPS is hosting an open house on Tuesday, July 23, 2024, from 6 p.m. to 8 p.m. at the Glen Canyon Headquarters Building, located at 691 Scenic View Dr., Page, Ariz. A second open house will be held near Lees Ferry, Ariz. on Thursday, July 25, from 9 a.m. to 11 a.m. at the Marble Canyon Lodge, located off U.S. Hwy 89A, Marble Canyon, Ariz. Program managers and park scientists will be available to meet with anyone interested to provide information and answer questions about the proposed slough channelization project. 

Formal public comments will be welcome during an upcoming public scoping period to be announced.