I have hunted the Gifford Pinchot National Forest, by first approving with fish and game as part of a gold dredging in a designated area. Along with a letter of intent sent to the ranger and accompanied with the gold and fish pamphlet I was allowed to also use a detector to search for gold. It has expired and frankly too much bother. I would just make sure I had the gold pamphlet and try along the bank of the Columbia below the high water line. I have hunted state land at the top of larch mountain in the old picnic area. There is another old picnic area north of the Honer Camp west of larch mt.