Choose from seven different public campgrounds in the Lake Quinault [1] area. The Forest Service maintains three campgrounds on the south shore of Lake Quinault: Falls Creek (open late May–mid-Sept., $14); Gatton Creek (no water, open late May–mid-Sept., $11); and Willaby (open mid-April–mid-Nov., $14). Willaby is the nicest of these and has a boat ramp.
Olympic National Park [2] campgrounds are more scattered, and all three are open year-round. July Creek ($10) is a walk-in campground on the north shore of the lake. Graves Creek ($10) is near the end of the South Shore Road, 15 miles from the Highway 101 turnoff. The free North Fork Campground is at the end of the North Shore Road. It does not have running water and is not recommended for RVs.
Check out Rain Forest Village Resort (516 S. Shore Rd., 360/288-2535 or 800/255-6936, $25 with water and electric hookups) for serene lakefront RV sites. The property is the only campground by the lake with showers on premises, and it also sports a restaurant and general store.
Another RV option is Quinault River Inn (360/288-2237, $21–25), which is convenient to the gas station and restaurants of Amanda Park.
Links:
[1] http://www.moon.com/destinations/washington/olympic-peninsula-and-the-coast/queets-and-quinault/lake-quinault
[2] http://www.moon.com/destinations/washington/olympic-peninsula-and-the-coast/olympic-national-park