This trail enters the Goat Rocks Wilderness so wilderness rules apply.
Five miles south of WA 12 on Forest Road 21, you'll see a small side road to the left numbered 2110. Take this road to the second switchback (about half a mile) where there is parking for perhaps five vehicles max.
The trailhead has a wilderness registry you should use and is clearly marked.
The trail itself begins by heading straight south for a fifth of a mile into the valley. It then turns east and descends to be level with the creek at the only point the trail actually meets the creek. It then continues east, entering huge old-growth forest and the Goat Rocks Wilderness.
After climbing through the dense forest with minimal views, you'll be rewarded by clear views over the beautiful lake from the old moraine. The trail continues down to the north (left) past a nice camping spot to the water's edge.