Approximately 4,500 acres of wilderness and natural open space land. Originally, part of the Juaneno or Acajchemem tribal land, it later was owned by Don Juan Avila, Louis Moulton, The Mission Viejo Company and now is under the jurisdiction of OC Parks. Within the park lands are mature oaks, sycamores, and elderberry trees, two year round streams and over 30 miles of official trails. Many rare and endangered plants and animals make this park their home. This park is designated as a wildlife sanctuary.
OC Parks is currently working to remove approximately 25 acres of invasive Arundo vegetation along a 3.7 mile section of Aliso Creek. This project will also allow for re-propagation of existing native plants, improve water quality, and reduce the risk of flooding and fire. This is one of several projects to completely remove Arundo and other invasive plants from the Aliso Creek watershed.