Here is a web site, one of many on the subject:
http://www.coastal.ca.gov/access/pr-access-facts.pdf
The point I am seeing is that once the land was transfered to the government there is no longer any need for a prescriptive easement because the land became public, it is open to visitation. Prescriptive easements applies to access, which the public now has, not the right to have a road to access the land. If that were the case all the the hundreds of roads that have been closed on public land were done illegaly, which I doubt. Furthermore there is no compelling legal need to have road access on the old Moss Mill Road.