Hancock Forest Management announced in Autumn 2011 that they will be implementing a new policy of charging non-motorized recreational users for a permit to use Hancock Forest lands. Within King County, the two forest areas that require separate permits each are:
The permits are $75 for each forest, available on the Hancock website below:
Hancock Forest Management's Recreation Access Program website
To purchase a permit, go to the site above and click on the appropriate forest on the left-hand side, then click on the appropriate type of permit (probably "Non-motorized Recreation Access Permit for Individuals"). You will be asked to agree to a waiver of liability (you can read it ahead of time here) and to the Rules and Regulations (below) before buying the permit, and payment is accepted through PayPal only. Hancock FM will then send you an email with a link to your permit, which you then print out and carry with you on your ride, along with photo ID. They also suggest printing a second copy and putting it on your windshield if parked near a trailhead. I suggest printing a few backup copies as well, in case of damage.
Rules and Regulations - Snoqualmie Forest <-- linked from this page
Rules and Regulations - White River Forest <-- linked from this page
Hancock's FAQ - Non-motorized access