Fish biologists are keeping a close eye on a small but very important backwater channel three miles below the Glen Canyon Dam.
That’s where the Minus-12-Mile Slough branches off the Colorado River’s mainstem, curving around an island on the river’s shady left bank where it turns shallow and warm. The slough’s tepid waters provide prime spawning habitat for nonnative warm-water species like the smallmouth bass.
Hungry bass are top of mind for those committed to the wellbeing of the river’s natural ecosystem. Their presence can mean life or death for natives like the threatened humpback chub and endangered razorback sucker.
Last spring scientists and managers decided it was time to intervene. Together, the National Park Service and the Bureau of Reclamation began a massive effort to dig out the slough in hopes of making it cold and deep once more.
Over the course of several months, crews excavated thousands of pounds of sediment and cobble. Using a barge, heavy machinery, and a tugboat named Miss Jeanie, workers successfully deepened and reshaped the channel so cool water could come rushing through once more.
Today, increased waterflow and decreased temperatures are coming together to deter the bass and help native chubs, razorbacks, and flannelmouth suckers thrive.
Scientists continue to monitor the area. Theirs is an ongoing effort, as drier conditions and decreased flows can mean proliferation of fish like bass, and bad news for native species that have called the Colorado home for millions of years. For now though, the outlook in the slough is promising.
This episode of Earth Notes is brought to you in part by Pink Jeep Tours, written by Svea Conrad, and produced by KNAU and the Sustainable Communities Program at Northern Arizona University.
