I havent done this since 2002, but it was $10 for a permit to haul out a truckload of wood from the gifford pinchot. in fact, $10 per truckload of firewood or floral greens, rocks or soil, whatever. Gathered alot of lava rock. we could not cut live trees, only dead standing or dead falls, and I think there was a 24" d maximum sizelimit- some good reasoning about fire control by woody debris removal- historically it would have burned from many areas regularly, with frequent low intensity fires. with fire suppression, fuel builds up, so that when it does go its catastrophic. so firewood permits help keep that in check.
there werent any 'requirements" beyond the $10 permit. that and meeting Mt.goat's requirements should do it.
I posted in the lumber thread a few more thoughts about firewood. frankly, its far more sensible ttrr spend another 200 bucks and get an alsakan mill, 350 get a good 3/4 to 1" bandsaw, and make a table then slab up beams and posts, make 1" boards, whatever. value added - triple the time of making firewood for 15x the returns.
it pays for the beer.