Dogs on a leash are allowed in the Park's day use areas, campground and north beach (north of lifeguard tower 3). Dogs are not allowed on backcountry trails or south beach (south of lifeguard tower 3).
DIRECTIONS
The most direct way of getting to Leo Carrillo from the Conejo Valley is via Westlake Boulevard (CA-23) (aka Decker Canyon) south, which for some is a fun 14 mile drive, but for others, not so much. It is a bit winding, hilly, steep at many junctures. I take this route during daytime hours but coming home I'm not too keen on it. After getting to PCH, turn right and drive 2 1/2 miles to get to Leo Carrillo.
Another more popular, though less direct route is via Kanan Road. Either take Kanan Road straight down to PCH, turn right (west) on PCH about 9 miles to Leo Carrillo, or take Kanan to Encinal Canyon, which is about a 3 mile drive on PCH to Leo Carrillo.
Lastly, if you are in Newbury Park, you can take Potrero Road west to Las Posas down to PCH. In about 11 miles you will reach Leo Carrillo.