GRANTS PASS — The federal judge overseeing efforts to balance salmon against dams in the Columbia Basin has told federal dam operators their latest effort does not appear to be any better than two previous failed plans, and he will take over the process rather than send it back to them a third time.

U.S. District Judge James Redden wrote parties in the long-running case to come to court Wednesday prepared to answer tough questions, such as whether the plans for running dams on the Columbia and Snake rivers so they don’t harm salmon were based on the best available science, a demand of the Endangered Species Act.

The judge wrote that the plan appears to rely heavily on $1.5 billion worth of habitat improvement projects, hatchery reforms, predator control and dam modifications, with no assurance Congress will pay for them or that they will help salmon.

On the upper Snake River in Idaho, the federal agencies don’t appear willing to consider significant change to the status quo of running dams the dams, the judge added.

Redden said he may appoint a panel of experts to independently evaluate the biological analysis of the dam operations plan, known as a biological opinion, in addition to the evaluation done by NOAA Fisheries, the federal agency in charge of salmon recovery.

The agencies that operate 24 federal hydroelectric dams and irrigation projects in Oregon, Washington and Idaho have acknowledged that the dams would lead to salmon extinction without mitigation. As required by the Endangered Species Act, they offered $1.5 billion worth of projects to make up for them.

The projects include habitat improvements, hatchery reforms, predator control, and modifications to some dams so that young salmon slide over them while migrating to the ocean, rather than having to navigate spillways — but no significant change in how much water goes through turbines.

NOAA Fisheries, the federal agency in charge of salmon recovery, has found that the plan will lead to salmon recovery.

But the state of Oregon, Indian tribes, and conservation groups have raised serious doubts. The plan was developed by the Bonneville Power Administration, which sells the power produced by the dams, the U.S. Army Corps of Engineers and the U.S. Bureau of Reclamation, which operate the dams.

NOAA Fisheries spokesman Brian Gorman characterized the letter as a way to be sure all parties are prepared for the issues that will be addressed in the Wednesday hearing, rather than a warning.

Earthjustice attorney Steve Mashuda, who represents the conservation groups that brought the lawsuit, agreed the judge wants answers to issues that remain in doubt.

“There is nothing new in this plan, certainly not enough to see these stocks recover,” Mashuda said.

The judge noted that if he vacates the biological opinion, dam operators could be liable for illegally killing threatened and endangered salmon and steelhead, known as a “taking” under the Endangered Species Act.

Redden also reminded the parties that he wants to see an analysis of removing four dams on the lower Snake River, a last-chance option adamantly opposed by the Bush administration that was not included in the current plan.