The Bureau of Reclamation says it has finished its environmental review plan to help the humpback chub and other protected fish in northern Arizona.
The agency says the completion of the environmental review allows it to release cooler water from Lake Powell to combat the spawning of non-native smallmouth bass that thrive in warm water.
It will start releasing the water Tuesday, July 9.
It is the latest move in a battle to keep the invasive bass and green sunfish at bay in an area of the Colorado River below the Glen Canyon Dam.
The predatory fish have been able to move downstream as water levels have dropped and the water released from Glen Canyon has warmed.
Previous efforts approved by federal environmental regulators included releasing chemicals that can kill fish.
