The wilderness lies in the San Ysidro Mountains, of which Otay Mountain is the highest summit at. The mountain, and its immediate surroundings, are extremely rugged and include steep, often precipitous, canyon walls and hills. The public lands within the Otay Mountain Wilderness are one of the last remaining pristine locations in western San Diego County. Adjacent to the Mexican border, it is internationally known for its diversity of unique and sensitive plants. The area plays a critical role in San Diego's multi-species conservation plan.
Natural history
The San Ysidro Mountains are remnants of a chain of ancient volcanoes from which meta-volcanic soils form, sustaining a diverse chaparral community dominated by chamise, mixed chaparral and coastal sagebrush habitats.
Flora
The world's largest stand of Tecate cypress are found at Otay Mountain Wilderness, as are at least 15 plant species that are candidates for federal listing as threatened or endangered species. In all 37 plant species found on Otay Mountain are listed as sensitive by the California Native Plant Society, at least five, including the Tecate cypress, occur only on Otay Mountain or in the immediate are. Particularly important species include:
The diversity of habitats within the wilderness area maintains a variety of indigenous fauna, including a number of rare or endangered species. The most numerous large animal is the mule deer. Species of special concern on Otay Mountain include:
The arroyo toad, resident of the Tijuana river, is affected by erosion occurring on the Tijuana watershed, within the wilderness area, which causes silting of its habitat.
In the mid 1990s, as part of Operation Gatekeeper, Department of Homeland Security contractors began to build a border wall, and associated access roads. The initial phase of wall building extended from San Diego only as far as the foothills of Otay Mountain. An environmental impact statement carried out prior to a of an environmental law, required to allow construction within the wilderness area, concluded that the workon the border wall would have long term impacts on plant, animal and water courses within the area. Grading and construction of roads in the wilderness area would result in removal of layers of topsoil and delicate, intertwined root systems that protect dry chaparral habitat from erosion. The wall itself disrupts the ability of migratory animals, like the javelina, to roam freely across its natural range. In December 2008 work began to continue the wall's progress through the wilderness area, under the auspices of the Secure Fence Act of 2006.
