There are some sections of loose rock, but overall the trail is in very good condition. This is a fun descent and a good trail to pick up some speed as the trail widens and the terrain is flatter.
You can reach the Big Cienega Trail two different ways. The first is to run the Windy Gap Trail 1.1 miles to the junction of Forest Road 3N07 where the Big Cienega Trail joins shortly above the road. If you want to head uphill on the Big Cienega Trail from here, turn left. If you want to run the Mount Islip Loop
, and the Big Cienega Trail from the other direction, continue straight on the Windy Gap Trail.
When you reach Windy Gap, you need to continue northwest (left) on the connector trail until you reach the junction with the Mount Islip Trail. From this junction, you'll ascend west (left) on the Islip Ridge Trail to the summit of Mount Islip. After enjoying the summit and catching your breath, begin your short descent south where you'll join up with the Islip Ridge Trail. From here, head west (right) down the Islip Ridge Trail.
After descending down the Islip Ridge Trail, you'll finally come to the junction with the Big Cienega Trail, which will lead you back to the Windy Gap Trail. Along the way, you'll have a clear view back east across the Crystal Lake Basin to Windy Gap along the Islip Ridge. This section of trail has very evident fire scars from the 2002 Curve Fire although there are nice patches of Jeffrey and sugar pine and white fir. A seasonal spring with nice wildflowers in summer is crossed about midway. When you reach the junction with the Windy Gap Trail, turn west (right) and continue on the homestretch downhill to the trailhead.
The Crystal Lake Basin provides beautiful 360-degree scenery of alpine flowers, Jeffrey and sugar pines, white fir and patches of manzanita and ceanothus. Nelson bighorn sheep can sometimes be spotted foraging in the high meadow above the spring. Wildfire scars can be seen across the basin left over from the 2002 Curve Fire, a reminder that the San Gabriel Mountains landscape is ever-changing.