Cuyamaca Rancho State Park in Julian, CA, has some dog-friendly areas. Dogs are not allowed on all the trails, so make sure you look out for signage. Pets are allowed on the campgrounds, picnic areas, paved roads, and Cuyamaca Peak Fire Road. The two family camps, Paso Picacho and Green Valley, can be reserved from spring to fall. Green Valley is 4,000 feet above sea leavel and has a beautiful babbling creek running through the middle. Please ensure Fido is leashed at all times.