Redden, 82, has rejected three federal government plans for operating hydropower dams on the Columbia and Snake rivers without causing undue harm to salmon and steelhead on the endangered species list.
In August, the Portland-based judge rejected the government's "biological opinion" for the third time, ordering the National Oceanic and Atmospheric Administration to submit a new plan no later than Jan. 1, 2014.
In an email to attorneys on the case Tuesday, he said he would step down prior to the filing of the 2014 plan.
It's not clear how soon he will retire, though he said in his email that he wants to give another judge time to review the history of the case before another plan is filed.
Attorneys say they wouldn’t be surprised if he stepped down before year end. Redden’s office couldn’t be reached for comment.
The announcement wasn't a surprise, given Redden's age and earlier signals that he would step down.
But it's a significant change in a case that affects both electricity ratepayers and the Northwest's storied runs of wild salmon.
Redden's stern oversight has helped prompt more fish-friendly spill over dams, at the expense of power generation, federal government accords with Northwest tribes and millions more in federal spending on habitat improvements.
Redden has been on the federal bench since 1980, after serving as a Democrat in the Oregon Legislature and as state attorney general and treasurer.
Salmon advocates see Redden as a champion for threatened runs. Critics say he's demanded too much from the government, stretching the legal requirements of the Endangered Species Act.
Nicole Cordan, policy and legal director for Save Our Wild Salmon in Portland, said Redden is "an amazing man and an amazing judge." But Cordan said she doesn't expect a change in legal direction from a new judge:
"I have all the faith that any other judge in the Portland district is going to do the exact same thing."