The Santa Susana Field Laboratory (SSFL) is located on approximately 2,850 acres in the Simi Hills in Ventura County, California. The Simi Hills are bordered on the east by the San Fernando Valley and to the north by Simi Valley. SSFL is divided into four administrative areas – Area I, Area II, Area III, and Area IV – and two "undeveloped areas." Areas I, III, and IV and the undeveloped areas are owned and operated by the Boeing Company. Area II, consisting of 409.5 acres, along with 41.7 acres in Area I, are owned by the U.S. Government and used by NASA. The U.S. Department of Energy (DOE) has long held a lease on land in Area IV. The links provide a summary of the 60 year history of ownership and operations of the portions of the site known today as Area II and the LOX Plant portion of Area I. These areas have been used primarily for rocket testing.
Three Native American groups occupied Ventura County in the areas surrounding the Simi Hills during late prehistory: the Chumash, the Tongva, and the Tataviam. All were seminomadic hunter-gatherers, while the Chumash and Tongva focused much of their subsistence activities on marine resources, supplementing that with resources available inland.
Burro Flats Painted Cave is a prehistoric archaeological site that is famous for its pictographs (rock art paintings) and petroglyphs (rock art that has been scored or incised into the rock surface). The site also includes evidence of habitation. The Chumash of the Simi Valley and Simi Hills and the Tongva of the San Fernando Valley may both have visited the Burro Flats Painted Cave area. There is speculation that the area may have been an interface between the two groups, and the rock art has been described as suggesting both cultures.
Burro Flats Painted Cave was first occupied from at least A.D. 1100 until ca. A.D. 1810 to 1820, although its occupation may extend back in time to as early as A.D. 900.
After World War II, North American Aviation (NAA) leased and later purchased land in the Simi Hills for rocket engine testing. NAA formed the aerospace company called Rocketdyne, which later merged with Rockwell International Corporation (referred to here as Rockwell. Both the Rockwell and Rocketdyne names were associated with SSFL. In 1954, NAA obtained an adjacent 838-acre area of undeveloped land from Henry Silvernale and Elizabeth Hall. (Property ownership records identify Henry Silvernale and Elizabeth Hall as the earliest recorded owners of the property.) This new parcel included the land that would become Area II, as well as the 41.7 acres in Area I that later would make up the LOX (Liquid Oxygen) plant. These portions subsequently were transferred to the U.S. government.
In December 1958, NAA deeded three parcels of the former Silvernale property to the U.S. Air Force (USAF). Parcels 1 and 2, consisting of 409.5 acres, became the site of USAF Plant 57, now Area II. Parcel 3 was used for USAF Plant 64, now the LOX plant. The Grant Deed also granted legal access for roads.
Since 1954, Area II has been operated by Boeing, Rockwell, and its predecessor, NAA, under USAF facility contracts. In 1973, the USAF Plant 57 (Area II) land was transferred to NASA and the USAF Plant 57 designation was no longer used.
In 1976, the U.S. General Services Administration (GSA) transferred the LOX plant (USAF Plant 64) from the USAF to NASA, but the Air Force retained possession of the structures. Under the terms of a facilities contract, Rockwell administered the LOX plant for NASA. The LOX plant was removed in the early 1970s with the exception of a small weigh station and concrete tank supports.