The change is designed to help revive native fish like razorback sucker, humpback chub, Colorado pikeminnow and bonytail fish. The decline of these fish is attributed to the sediment settling out of the water behind the dam, resulting in water cooler than is ideal for these fish. The biggest concerns about the proposal come from anglers worried about the changes to local trout population on the world class fishery.
The process started in 1992 after the Fish and Wildlife Service concluded the impact of the dam was becoming a threat to the native fish, which prompted USBR to begin a study of which flows would best help the fish. After five years of study, USBR concluded the natural hydrograph that was in place prior to the dam would be the most suitable flow for the fish. A model was put into place to see if the proposed flows were feasible under the conditions and the agency has decided to go forward with the plan, after public consultation.
