What's at Stake
The humpback chub is a key indicator of the lower Colorado River's health. It is threatened by intensive management of the river system.
The humpback chub was given federal protection three decades ago, but the agencies that regulate the flow of water through the Grand Canyon have refused to alter their practices to benefit the fish.
Earthjustice sued to force altered dam operations and won an initial victory but was rebuffed at the court of appeals.
The U.S. Fish and Wildlife Service took another look at the situation, and its later biological opinion was still inadequate.