That's a tricky one. Some don't like to broadcast their spots so they can keep them unknown, pristine and open. I for one don't blame them. I've seen it too many times, an area becomes popular, the Forest Service or BLM wants to map it, people unwittingly help these entities map the areas, then the closures come. Whatever the cause, whether it be overcrowding, noise, dust... ultimately it was the increase in use that caused it. Meet some folks in your area, gain their trust, then keep it.
Look up a friend of mine, Carl Spurgeon, in your neck of the woods. He is about 10 years my senior, and I probably couldn't begin to keep up with him, but he will surely know all of the good riding in Olympia and environs. Rides an ST1300 and a 650 Strom, the latter of which he has taken to the haul road and back.