In a letter Friday to Redden, the Justice Department said top officials in the Obama administration want a delay of up to two months to "more fully understand all aspects" of the plan.
Redden heard arguments in March in a long-running dispute over how to balance Columbia Basin energy and utility needs with imperiled salmon and steelhead.
Environmentalists have argued that salmon populations cannot recover without removing some dams, especially the migration bottleneck to Idaho created by four dams on the Lower Snake River in Washington state.
Redden told the NOAA Fisheries Service at the March 6 hearing that their plan for balancing endangered salmon runs against electricity production on 14 federal Columbia Basin hydroelectric dams still needs work, particularly in the area of habitat improvement.
Federal agencies have acknowledged that the dams threaten the survival of fish, but said that extensive habitat restoration, changes in salmon hatchery operations and plans to let more water pass through Columbia and Snake River dams should mitigate the problem.
The National Oceanic and Atmospheric Administration submitted a 10-year plan last year after others were rejected by Redden. Officials said the plan, called a biological opinion or bi-op, would help fish passing through the dams survive. Environmentalists sued, saying the plan did too little to restore salmon populations.
Todd True, an attorney representing the National Wildlife Federation and other environmental groups, called the delay request encouraging.
Witt Anderson, a spokesman for the U.S. Army Corps of Engineers in Portland, said the delay would give officials of the new administration time to familiarize themselves with all the issues in the complex case. Jane Lubchenco, the new administrator of NOAA, was among those attending high-level meetings on the case in recent days.
