Bring the family and gallop on out to Mustang Waterpark at Lopez Lake recreation area! Mustang Waterpark offers the family the best values. The Waterpark, Pony Pools and Slides are located in a campground 10 miles east of Arroyo Grande. Our water attractions are nestled on oak-studded hills, overlooking beautiful Lopez Lake, far from traffic and stress. We offer affordable family fun for all ages. Open seasonally, Memorial Day to Labor Day, check the website for more details.