Between mile marker 24 and 25, in the east side of Highway 4, is a triangular parking lot. From there you hike down to the bottom of the canyon on a user-friendly gravel and dirt train. After crossing a bridge over the stream, the trail becomes a mix of footpath, rocks and wet patches where water seeps from higher up. That hike is higher up than the walk down.
As far as a rating goes, it wasn't worth the hike. The water temperature, and algae on some of the rocks, sort of killed it for me. Maybe the water is hotter other times of the year. I can understand how body temperature water might be acceptable in cold weather. How about a score of 3.5? Pretty place, though. But watch for poison ivy.