Angeles National Forest Locate the trailhead. A handy map to the trailhead found at the end of the road which is not, according to the map, where the trail starts. Grizzly Flat is a short way up the north end of the Dark Canyon trail. The south end starts in Oakwilde, about 4 miles up Arroyo Seco starting near JPL. It is marked with one of those flat, brown stick signs, but rather than simply saying "trail" as they normally do, it is well marked with promises that the trail further on through Dark Canyon is unmaintained and likely to take your life if you try to travel along it. The north end, in contrast, starts about a mile along Big Tujunga, which is reportedly difficult to pass in high water, and doesn't really have a trail along it from the road. It is true that the route is difficult to determine among all the choices for the first section along the creek, but it is easy to find as it heads upward away from the water. From there is is well maintained t...