| Agua Tibia Wilderness | |
|---|---|
 Sunrise over the Agua Tibia Wilderness | |
  Map of the United States Show map of California Agua Tibia Wilderness (the United States) Show map of the United States | |
| Location | San Diego andRiverside counties,California, United States |
| Nearest city | Temecula, California |
| Coordinates | 33°25′15″N116°59′09″W / 33.4208650°N 116.9858598°W /33.4208650; -116.9858598[1] |
| Area | 17,961 acres (72.69 km2)[2] |
| Established | January 5, 1975 (1975-01-05) |
| Governing body | U.S. Forest Service,USDA Bureau of Land Management |
Agua Tibia Wilderness (ATW) is a 17,961-acre (72.69 km2) protected area inRiverside andSan Diego counties, in theU.S. state ofCalifornia. It is mostly within the Palomar Ranger District of theCleveland National Forest.[3] The area was originally protected as the Agua Tibia Primitive Area until January 1975 when it was added to theNational Wilderness Preservation System with the passage ofPublic Law 93-632 by theUnited States Congress.[2] Between its inception and 1984, the ATW was San Diego County's only officially designated wilderness area.[4] The Spanish name, Agua Tibia, translates aswarm water.
Its approximate boundaries are:[5]
There are no permanent streams in the ATW. The highest landform is Agua Tibia Mountain with an elevation of 4,779 feet (1,457 m).[6]
Though the summer climate is hot, with limited shade and no water sources, there were no fires in the ATW for 110 years. In the last two decades, there have been four fires including thePalomar Mountain Fire (1987), the Vail Fire (1989), the Agua Tibia Fire (2000), and thePoomacha Fire (2007).[5] Its pollution exposure is monitored within theSan Diego Air Basin.[7]
The Agua Tibia Wilderness is home to rare andendemic plants. These include:
The Agua Tibia Research Natural Area (ATRNA), located within the wilderness, comprises 480 acres (190 ha) of bigcone Douglas-fir—canyon live oak forest. The area was set aside for the study of this forest type in thePeninsular Range province and with emphasis on forest succession, long-range ecological changes and the effects of resource management practices. Bigcone Douglas-fir (Pseudotsuga macrocarpa) is arelict species and isendemic to Southern California. This population on the ATRNA is unique for its relatively great age, size, genetic purity, placement near the southern extent of the species' range, and for its remoteness and lack of disturbance by man. Other notable plants in the research area are Laguna linanthus (Linanthus orcuttii ssp. pacificus) and Hall's monardella (Monardella macrantha ssp. hallii). Both are listed as 1B by theCalifornia Native Plant Society's Rare Plant Program.[8][9]
According to a U.S. government geologist writing in 1915, "Near the southern base of Agua Tibia Mountain and 25 miles in a direct line north of west fromWarner Hot Springs, warm water (agua tibia), issues along afault zone that is parallel to the one in Warner Valley. The water rises with a temperature of 92 °F (33 °C) in a marshy area that covers perhaps an acre. It is conducted from a board-curbed pool to tubs in a near-by house, for bathing and laundry use. Bubbles continually rise in the pool and the water is distinctly sulphureted...This water is essentially primary saline in character, being a soft water of moderate mineralization."[10]
