Marin County Parks Open Space Leash Policy: Dogs on leash are welcome to enjoy trails. Dogs are allowed off-leash under strict voice control on fire protection roads. Please follow posted rules.
The highlight of this preserve is the Big Rock Trail, a multiple-use trail that begins at the crest of Lucas Valley Road (at the ”Big Rock”), and eases its way up to the Big Rock Ridge Fire Road. It connects with the Loma Alta Trail that ascends the southern half of the valley.
Portions of both the Big Rock Trail and the fire road along the ridge are trail easements that cross private property, so pay heed to all trail signs posted along the way.
The summit of Big Rock Ridge at 1895 feet is the second highest point in Marin County (after Mount Tamalpais), and views from the top are spectacular.
An alternate route between the valley floor and the ridge is the incredibly steep Luiz Fire Road, but one trip up (or down) this old road will make you truly appreciate the new trail for its beauty and gentle grade.
Directions:
From Highway 101 in San Rafael, take the exit for Lucas Valley Road west approximately 5.5 miles (look for the big rock). The trailhead is on the north side of Lucas Valley Road.
• Parking: Side of the road.
• Fee: None.
• Water: Bring your own.
• Best time of the year to hike: Spring, winter can get muddy and summer is hot with limited shade.
• Degree of difficulty: Moderate
• Distance: 3.7 miles
• Hours of operation: Sunrise to sunset