On Thursday, five organizations filed a federal lawsuit charging that the bureau and Interior Department are in violation of the Endangered Species Act, Grand Canyon Protection Act and the National Environmental and Policy Act because of what they call their failure to protect the most prominent of those native fish species - the humpback chub.

"The humpback chub's decline is just another example of the federal government's complete disregard for native wildlife and the irreplaceable habitat they represent," Robin Silver, board chair of the Center for Biological Diversity, said in a statement.

Bureau of Reclamation officials declined comment on the suit Thursday, citing the pending litigation.

"We are aware of the lawsuit and are preparing for whatever may occur," said bureau spokeswoman Stacey Carroll.

Congress passed the Grand Canyon Protection Act in 1992 to reverse the decline of native fish species in the canyon. The Glen Canyon adaptive management plan was adopted three years later to guide the Bureau of Reclamation in implementing recovery guidelines set by the Fish and Wildlife Service.

The focus of those efforts has been a series of flow test experiments from Glen Canyon Dam that were designed to push more sediment downstream in a bid to create sandbars and backwaters that serve as habitat for the fish. But those tests have largely failed to deliver the desired results.

A report released last fall by the U.S. Geological Survey concluded that efforts to restore the Colorado River below the dam to something close to its natural state "have not produced the hoped-for restoration and maintenance" of endangered fish species.

According to the study, three of the Grand Canyon's original native fish species - the roundtail chub, bonytail chub and Colorado pikeminnow - have been eliminated. The humpback chub population has declined between 30 percent and 60 percent.

"To date, the negative impacts of Glen Canyon Dam continue to lead to the continual decline of the humpback chub," said David Wegner of the Glen Canyon Institute. "Clearly the adaptive management program, as being implemented by the federal government, is not working."

In response to an earlier lawsuit filed by the Grand Canyon Trust, the U.S. Fish and Wildlife Service announced earlier this week it will begin a process to review and update its recovery goals for the humpback chub in 2007.

jbaird@sltrib.com