Agua Tibia Wilderness (ATW) is a protected area in Riverside and

San Diego San Diego ( , ; ) is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the eighth most populous city in the United States ...

counties, in the

U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its sove ...

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

. It is mostly within the Palomar Ranger District of the

Cleveland National Forest Cleveland National Forest encompasses 460,000 acres (), mostly of chaparral, with a few riparian areas. A warm dry mediterranean climate prevails over the forest. It is the southernmost U.S. National Forest of California. It is administered by ...

. The area was originally protected as the Agua Tibia Primitive Area until January 1975 when it was added to the

National Wilderness Preservation System The National Wilderness Preservation System (NWPS) of the United States protects federally managed wilderness areas designated for preservation in their natural condition. Activity on formally designated wilderness areas is coordinated by the Na ...

with the passage of

Public Law Public law is the part of law that governs relations between legal persons and a government, between different institutions within a state, between different branches of governments, as well as relationships between persons that are of direct ...

93-632 by the

United States Congress The United States Congress is the legislature of the federal government of the United States. It is Bicameralism, bicameral, composed of a lower body, the United States House of Representatives, House of Representatives, and an upper body, ...

. Between its inception and 1984, the ATW was San Diego County's only officially designated wilderness area. The Spanish name, Agua Tibia, translates as ''warm water''. Its approximate boundaries are: * North – SR 79 * East – Arroyo Seco River * South – Fray Creek * West – Pala Road

Environment

There are no permanent streams in the ATW. The highest landform is Agua Tibia Mountain with an elevation of . 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 the

Palomar Mountain Palomar Mountain ( ; es, Monte Palomar ) is a mountain ridge in the Peninsular Ranges in northern San Diego County. It is famous as the location of the Palomar Observatory and Hale Telescope, and known for the Palomar Mountain State Park. His ...

Fire (1987), the Vail Fire (1989), the Agua Tibia Fire (2000), and the Poomacha Fire (2007). Its pollution exposure is monitored within the

Air Basin.

Flora

The Agua Tibia Wilderness is home to rare and

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

plants. These include: * Nevin's barberry ('' Mahonia nevinii'') * Rainbow manzanita ('' Arctostaphylos rainbowensis'') * Round-leaved boykinia ('' Boykinia rotundifolia'') * Vail Lake ceanothus (''

Ceanothus ophiochilus ''Ceanothus ophiochilus'' is a rare species of flowering shrub known by the common name Vail Lake ceanothus, native to Southern California. It was not described until 1991. Distribution The ''Ceanothus ophiochilus'' plant is endemic to Californ ...

'')

Agua Tibia Research Natural Area

The Agua Tibia Research Natural Area (ATRNA), located within the wilderness, comprises of bigcone Douglas-fir—canyon live oak forest. The area was set aside for the study of this forest type in the

Peninsular Range The Peninsular Ranges (also called the Lower California province) are a group of mountain ranges that stretch from Southern California to the southern tip of the Baja California peninsula; they are part of the North American Coast Ranges, which ...

province and with emphasis on forest succession, long-range ecological changes and the effects of resource management practices. Bigcone Douglas-fir ('' Pseudotsuga macrocarpa'') is a

relict A relict is a surviving remnant of a natural phenomenon. Biology A relict (or relic) is an organism that at an earlier time was abundant in a large area but now occurs at only one or a few small areas. Geology and geomorphology In geology, a r ...

species and is

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 the

California Native Plant Society The California Native Plant Society (CNPS) is a California environmental non-profit organization (501(c)3) that seeks to increase understanding of California's native flora and to preserve it for future generations. The mission of CNPS is to con ...

's Rare Plant Program.

References

External links

USDA Forest Service official site

Topo Map

Land Management Plan Strategy

Agua Tibia Wilderness
{{Authority control Wilderness areas of California Cleveland National Forest Protected areas of Riverside County, California Protected areas of San Diego County, California Natural history of the Peninsular Ranges Protected areas established in 1975 1975 establishments in California