Lewis Creek Trail is a 19.6 mile out and back trail located near Dunlap, CA and is rated as difficult. The trail is primarily used for hiking and is accessible from June until October.
I managed to go only one fifth of the way on the Lewis Creek Trail (~2 miles), mostly because I had to head back home. (Started really late...11:00 am!). The trail is pretty steep, at least for the first 2 miles. Be prepared for a very fast heartbeat! Parts of the trail have no shade, so it can get hot. Very nice views of the canyons. If you go in the summer, make sure you have lots of water! Also, there are flying insects occasionally (not mosquitos), so insect repellent is a good idea.