No, Panning, sluicing or dredging for gold or other minerals is not allowed within streams or other waterways in any state park. REF: https://wdfw.wa.gov/publications/00291/wdfw00291.pdf
The rules are constantly changing. Please refer to the document in the attached link to verify if Flaming Geyser Park allows where you are attempting to accomplish. https://wdfw.wa.gov/publications/01992/
Thanks! Your answer is awaiting moderation.