We went hiking at Wilder Ranch State Park north of Santa Cruz yesterday.
The most scenic part of the park is between CA 1 (the coast road) and
the Pacific Ocean. Bicyclists and hikers are allowed in this part of the
park, but signs where the trails begin ban equestrians. It was so nice
to be on a hike where you don't have to dodge the droppings of
irresponsible equestrians that would probably not leave their dog's poop
on someone's lawn, but see nothing wrong with destroying trails that are
used by others.

The mountain bikers that passed us were unfailingly polite, calling out
"on your left" so we would know that they were there.

Trails east of CA 1 do allow horses, and you can imagine the mess.

There's work underway to expand mountain bike access to more state
parks, while at the same time restricting equestrian access to sensitive
areas. This is something we all should be working for.