Here are some friendly tips to help you and your dogs enjoy Marin County parks and open spaces:

Dogs in County Parks:  Leashed dogs are permitted at all Marin County parks except McNear's Beach and Stafford Lake.  Dogs are permitted off-leash but under direct, immediate control at portions of McKinnis Park and Upton Beach at the north end of Stinson Beach.  

Dogs on County Open Space Lands:  Marin County's regulations permit only three dogs per individual on open space lands.  Dogs are permitted on open space lands when restrained by a 6' (maximum) leash.  Dogs may be off leash on maintained fire roads only when under direct, immediate control of a responsible person.  Please be sure to check for more details of dog-friendly rules here.  

Dogs in Federal Park Lands:  There are many trails and some beaches within the Golden Gate National Recreation Area (GGNRA) that allow off-leash dogs.  Due to constant changes in park regulations, please be sure to check on current rules for off-leash policy here. 

Best Places to Hike with your Dog:

Indian Tree Open Space Preserve, Novato: If the weather is hot, these trails are probably the best choice. Walking through cool, shaded woodlands of oak keeps you and your four-legged friend cool. At the top, you can also expect a cool place because it is often foggy. Dogs are allowed off-leash on fire roads - watch horses!  
Directions: Take the DeLong Avenue Exit from U.S.101. It becomes Diablo Avenue. Turn left on Hill Road and take a right on Indian Valley Road. Drive all the way to the end, park the car on this road and walk left at the spur road marked “Not a through street” at the south of Old Ranch Road. Cross Arroyo Avichi Creek right at the entrance. 

Gary Giacomini Open Space Preserve, Woodacre: In the lower areas you will find the old-growth redwoods; the higher you walk the grassier it gets. For a fun route park at the intersection of Redwood Canyon Drive and start your hike at the nearby trailhead.

Terra Linda/Sleepy Hollow Divide Open Space Preserve: from the ridge, you have a wonderful view of the turquoise-roofed Marin County Civic Center in San Rafael and the bay and hills of Solano County. You can either climb up to the ridge or use the highest entrance on the ridge.
Directions: Drive to the very end of Ridgewood Drive and step over that low-locked gate.

Dog-Friendly Parks by Community:

Fairfax:  Cascade Canyon Open Space Preserve

Mill Valley:  Mount Tamalpais State Park, Bayfront Park

Novato: Mount Burdell Open Space Preserve, Dogbone Meadow Dog Park, Deer Island Open Space Preserve 

San Anselmo:  Loma Alta Open Space Preserve, Sorich Ranch Park

San Rafael: Fields of Dogs, San Pedro Mountain Open Space Preserve, Santa Venetia Marsh Open Space Preserve