The parking area for the trailhead is on the left side of the Washogual River Road, about 0.2 miles north of the trail entrance. There's a nice little trail that leads from the parking area quickly to the nearby Washougal River, which can make a nice cool-off after your run.
The entrance to the trail is vague and you may want to keep the Trail Run Project mobile app
out to locate both the parking area and the start of the trail. Don't be too put off when you immediately encounter a short section of fallen logs. After about a quarter-mile, things clear up and the rest of the trail is well worth the inconvenience.
From there, the trail leads up, up, up on winding singletrack, which keeps you on your toes. Like a tour of the mountain forest traversing 1,000-2,000ft up the side of the mountain. Expect mostly good, smooth singletrack with occasional rocks, roots, and common stream crossings (easy).
Much of the trail is covered with a forest canopy that makes for nice shade as you go. If you're looking for a shorter run, the four-mile mark makes a nice spot to turn around before the steady climbing resumes. Continuing on, the singletrack gets noticeably steeper as it climbs through several series of switchbacks in the final 1.5 miles.
If the trail hasn't been recently brushed, it can be quite overgrown, but just brushy not truly obstructive. In some places you might not be able to see the trail, but just keep going and push the plants out of the way (little rough on exposed legs. NO NETTLES THOUGH).