Mustang Waterpark offers the family the best values Mustang Waterpark, Pony Pools and Slides are located in a campground 10 miles east of the nearest town, Arroyo Grande, on the Central Coast of California. the water attractions are nestled on oak studded hills, overlooking beautiful Lopez Lake, far from traffic and stress. they offer affordable family fun for all ages. Make Mustang Waterpark part of your best family vacation ever.