A key fish that has lived in the Colorado River for millennia, and whose presence indicates a healthy river, is now up against a threat from a giant dam above.
The humpback chub has long been the focus of successful restoration efforts. But as the waters of Lake Powell sink lower than ever, nonnative predator fish could make their way down through the inner works of Glen Canyon Dam to the river below where they feed on the chub.
Federal, state and tribal agencies are urgently trying to devise a strategy to keep the predators penned up.