Federal officials say they are generally satisfied with the progress on recovering four native Colorado River fish species, but concerned that the impacts of the 2012 drought could result in some setbacks to the program. Issuing a “sufficient progress”memo, the U.S.

With 2012 shaping up to be at least a near-record drought year in the high country, some of the Colorado River’s endangered native fish could be facing a battle for survival, especially in key tributaries like the Yampa, in northwestern Colorado.

The Upper Colorado River Endangered Fish Recovery Program is lending a high-tech hand to four species of endangered fish on the Western Slope. At the Price-Stubb Diversion Dam on the Colorado River near Rifle, a new “passive integrated transponder” (PIT) tag system is now monitoring the movement of endangered fish that are PIT tagged.

Six reservoirs along the upper Colorado River are releasing water through the Memorial Day weekend to help improve mating habitat for endangered fish. The releases from Granby, Ruedi, Windy Gap, Williams Wolford Mountain, Dillon and Green Mountain reservoirs are designed to replicate spring peak flows on the Colorado before the dams were built.

The completion of the $12.1 million diversion, a 900-foot rock channel that bypasses an 8-foot-high concrete dam that formerly diverted water into the Price-Stubb ditch, removes the last obstacle in the upstream passage for native fish in a 290-mile span of the Colorado River from Lake Powell to Rifle.

Without a name tag hanging on each fish, biologists are reluctant to say exactly how many endangered fish swim in the Colorado River. But research indicates populations of the four endangered fish species — the Colorado pikeminnow, the humpback chub, the razorback sucker and the bonytail chub — are stable or increasing.