Getting to this awesome trail is a challenge. You can access it from the Rinconada Trailhead over the cuesta grade near Santa Margarita Lake. Take the Rinconada Trail (14E30)
to Hi Mountain Road. Take a right at Hi Mountain Road (a well maintained doubletrack truck trail) and follow it to its terminus marked by a turnout. There is a small singletrack trail that continues for about .25 miles to the top of the Big Falls Trail. It is marked by a white Santa Lucia Wilderness sign.
Alternatively, the trail can be accessed by Upper Lopez Canyon Road
. The road is only accessible to high clearance 4x4 vehicles only as there are multiple creek crossings. The trailhead is located at the terminus of the road and is co-located with the Lopez Canyon Trailhead.
This description follows the trail from the top down into Lopez Canyon. The first mile and half is in open grassland with an occasional lone oak tree. For how remote this trail feels, it is very well maintained, brush free, and easy to follow. The trail isn't perfectly buffed out, but a majority of it is rock-free and smooth. The trail then joins a creek and drops into an oak grove. The remaining 1.5 miles are in a dense, shaded oak grove. There are about eight creek crossings total, and after a storm, you'll get your feet wet at each one of them.
The best time to hike this is in the late fall to late spring when the water is flowing and hills are green. It can get really hot on the exposed ridge-line during the summer, and over the course of springtime, the trail will get progressively overgrown. This is a 5 star trail during winter/early spring and a 2 star any other time.