San Francisco Top Trails

Sierra Azul Open Space Preserve
By David Weintraub
Key Info
0.0 - Take Limekiln Trail northeast
2.3 - Right on Priest Rock Trail
4.8 - Right on Alma Bridge Rd.
5.2 - Back at parking area

Trail Use:
Hike, run, bike
5.2 miles, 2 to 3 hours
Vertical Feet:
1 2 3 4 5 +
Trail Type:
Surface Type:

Dogs allowed, stream, autumn colors, wildflowers, birds, great views, secluded, historic
Excerpted from Top Trails: San Francisco by David Weintraub

SECLUDED ESCAPE: You can't get much more secluded than this in the busy Bay Area. This trip explores the northwest corner of a 15,500-acre preserve, home to a wide variety of plants and animals, some rare, threatened, or endangered. Fall is the best time to visit this area, which bakes under the summer sun.

Finding the Trail
From Hwy. 17 northbound, exit at Alma Bridge Rd., south of Los Gatos. At 0.7 mile, you pass a parking area, right, for Lexington Reservoir. At 1.2 miles, stay right at a fork with the entrance road to Lexington Quarry. Roadside parking is just ahead on the right side of Alma Bridge Rd. The trailhead is at gate SA22, on the southeast side of the road across from this parking area.

From Hwy. 17 southbound, take the Bear Creek Rd. exit south of Los Gatos. After 0.1 mile, you come to a stop sign at a four-way junction. Turn right, cross over Hwy. 17, and turn left to get on Hwy. 17 northbound. Go 0.4 mile to Alma Bridge Rd., turn right and follow the directions above.

Trail Description
From the trailhead, you begin climbing northeast on the Limekiln Trail, a formerly paved road that is part of Lexington Reservoir County Park's trail system. Almost immediately, you come to a fence and a gate marked fire lane. Passing through a gap in the fence, you climb the rough and rocky road on a moderate grade. A creek flows through Limekiln Canyon, which is downhill and left. Still climbing, now on a gentle grade, you follow a winding course up a hillside that drops steeply left.

Now the road turns left and crosses a creek that drains into Limekiln Canyon, named for furnaces used to reduce limestone to lime. A handful of these operated in the canyon from the late 1800s until the 1930s. The road here may be very wet and muddy. This is a landslide-prone area, and there are young manzanita bushes growing atop piles of debris, helping to stabilize the soil. After climbing out of the slide area, the road swings right.

Now you descend into a cool and shady forest. Soon you reach the preserve boundary and begin a moderate-to-steep climb over very rocky ground. Through openings in the trees, left, you can see the Lexington Quarry, a massive rock quarry. With the deep valley and chaparral-clad hills of Limekiln Canyon to your left, you continue your uphill trek. Just beyond a fence and a gate is a junction. Here, the Limekiln Trail continues straight, and the Priest Rock Trail, a dirt road, goes left and right.

You turn right on the Priest Rock Trail. A gentle ascent ends with a short, steep pitch, and now you are on level ground. An unsigned dirt road joins sharply from the left, and then a short trail to a viewpoint departs right.

Crossing under a set of power lines and a tower, the road bends sharply left. A fence is just to the right of the road, and Priest Rock, a modest formation, rises behind it, half hidden in the chaparral. Now the road begins to snake its way downhill, and soon you reach gate SA23 and the preserve boundary. Your road continues into Lexington Reservoir County Park, and you descend on a grade that alternates between gentle, moderate, and steep. Leveling briefly, the road then climbs gently through a possibly wet area. Passing a dirt road, left, you continue winding downhill to the bottom of the Priest Rock Trail. Here, at gate SA21, you turn sharply right to meet paved Alma Bridge Road. Cross it carefully, turn right, and walk northeast along the road shoulder about 0.4 mile to the parking area.

Article © Wilderness Press. All rights reserved.

Published: 4 Oct 2004 | Last Updated: 15 Sep 2010
Details mentioned in this article were accurate at the time of publication


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