The trail head starts at the end of Willow Road, near Beatnix Leatherworks - just climb up and over the steps, then stick to your left (don't follow the hiking sign that points to your right - that is also a lovely hike, but it takes you along the other side of the river, so you'll miss the power station).
Click on the image below if you'd like to see the full "workout" on www.sports-tracker.com - there are a few photos uploaded as well.