GREEN RIVER - Water levels at Flaming Gorge Reservoir in southwest Wyoming would fluctuate less between seasons and would tend to be higher overall under a new operating plan for the Flaming Gorge Dam aimed at recovering several endangered fish species in the Green River.

That should maintain, and possible even help improve, the quality and quantity of fish in the world-class fishery, a new environmental study says.

The Bureau of Reclamation is proposing changes to water releases out of Flaming Gorge Dam to aid the recovery of the endangered Colorado pikeminnow, also known as the Colorado squawfish, the razorback sucker, and the bonytail and humpback chubs.

BuRec officials released a final environmental impact statement on the operation of Flaming Gorge Dam last week for public review.

Federal fish biologists say the construction of Flaming Gorge Dam in 1964 disrupted the natural flow of the Green River, trapping sediments that used to flow down river and altering the temperature and chemistry of the water below the dam.

Scientists say because sediment settles out of the water behind the dam, the once warm and muddy Green River now runs cold and clear green, which inhibits the recovery of the four native fish.

The four fish traditionally seek out shallow, warmer backwaters for spawning during high flows, where they don't continually have to fight the current. Because the dam is a peak power facility, when power demands recede and flows are cut back, young fish get stranded and die in off-river habitats.

The BuRec's new plan calls for mimicking nature's historic peak runoff flooding through specific flow releases at the dam. The aim is to stir up sediment, redistribute it and create hundreds of new sandy shores where vegetation can take root and feed fish.

The management document outlines the proposed peak flows, water temperatures and baseflow criteria recommended to protect and assist the recovery of the fish species over the next decade.

For the past four decades, the hydroelectric Flaming Gorge Dam has released more water when needed to meet peak power demands from power users. But officials said the new flows call for releasing water on a schedule that benefits the endangered fish rather than peak electrical demands.

That, in turn, could benefit fisheries on the reservoir, particularly species such as kokanee salmon.

The environmental impact statement said kokanee would be expected to benefit under the new operational plan because reservoir elevations would fluctuate less and would tend to be higher.

The quality of fishing has traditionally gone down in the past after lake levels were quickly lowered to meet peak power demands. The new plan calls for a more gradual flow increase or decrease, according to biologists.

Wary of change

About 80 people attended a meeting starting the environmental impact study in 2000 in Rock Springs to express concerns about possible changes to dam operations.

Sportsmen and residents in attendance told BuRec officials they should worry more about Flaming Gorge Reservoir's world-class fishery than endangered chubs and suckers below the dam.

Anglers worried any changes to the dam's flows could hurt recreationists, the quality of fishing and the commercial marinas that operate in the reservoir. And some contended increasing flows out of the dam to aid fish recovery could eventually lead to the draining of the reservoir.

But the final environmental impact statement said that "decommissioning and removing the dam" was not considered as an alternative because it did not meet the purpose and need of the proposed action.

The Flaming Gorge National Recreation Area attracts about 2 million visitors each year, according to BuRec data. Direct and indirect annual expenditures connected with various uses at the gorge are estimated to average more than $25 million each year.

Southwest Wyoming bureau reporter Jeff Gearino can be reached at (307) 875-5359 or at gearino@trib.com.