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.

This is a small preserve (87 acres), but its story is a perfect example of how many areas that are now open space were spared from development.

As the town of Mill Valley grew in the late ‘60’s, the citizens realized that the surrounding ridges would soon be covered with buildings.

Grassroots activism squelched the plans of several developers, and eventually the County was able to acquire the first 50 acres, which form the eastern half of the preserve.

The southern half of the Alto Bowl Preserve is known as “Horse Hill” and is leased for horse pasturing by the Alto Bowl Horseowners Association.

The sight of horses grazing peacefully on this grassy hillside has been a landmark for decades.

Directions:

• From Hwy 101 in Mill Valley, take the Tiburon Blvd/East Blithedale Ave exit west on East Blithedale Ave, turn right at Camino Alto, turn right at Azalea Drive, turn right at Vasco Drive (becomes Underhill Road), and turn left at Coach Road. Blithedale Ave exit west on East Blithedale Ave, turn right at Camino Alto, turn right at Azalea Drive, turn right at Vasco Drive (becomes Underhill Road), and turn left at Coach Road. MCOSD gate is at the end.

• Leash rule: Dogs are allowed to be off leash as long as they are under voice control.
• Parking: Parking for about 4 vehicles in a narrow roadside pullout
• Fee: None
• Water: Bring your own
• Distance: 2.2 miles
• Best time of year for this hike: Often muddy in winter and early spring
• Degree of difficulty: Easy
• Hours of operation: Sunrise to sunset