Williamson Rock is under a temporary closure to all recreational uses, including climbing, pursuant to a ruling by the U.S. Fish and Wildlife Service that the area is critical habitat for the endangered yellow-legged mountain frog. Efforts by the non-profit organization Friends of Williamson Rock, in conjunction with the U.S. Forest Service, are underway to regain climbing access to Williamson. For information on the status of these efforts, and to learn how you can help, contact the Friends of Williamson Rock: http://williamsonrock.org
Description
Although 5.11b/c is the official guidebook rating, the difficulty is highly dependent on the climber's height. I've heard 6-foot-tall climbers call the route 5.9. It all depends on what footholds you have to use to reach the crux crimp: the shorter you are, the worse the footholds (and the better your technique must be).
Location
This is the route to the immediate right of Mushroom (5.8) (2 routes to the right of "Shroomin'').