Aliso Canyon is a 6.5mi canyon located in Orange County, California in the United States. The canyon is a water gap across the San Joaquin Hills carved out by Aliso Creek, possibly as recently as the last Ice Age. Located in a semi-arid climate, it supports a variety of plant communities – mainly chaparral and coastal sage scrub – and native animals, some endangered.The canyon's northern divide once formed a formidable boundary between the indigenous Acjachemen and Tongva. Many Acjachemen archaeological sites have been found in the canyon. The fertile alluvial soil and grasslands of Aliso Canyon was used for orchards and grazing from Spanish conquest of the region until the early 20th century. Since the 1970s, the canyon has been the centerpiece of Aliso and Wood Canyons Wilderness Park.Aliso Canyon has also suffered environmental damage in recent years. Upstream urban development since the 1950s has increased urban runoff into Aliso Creek, causing severe erosion throughout the valley floor. Pollution has also harmed the area's riparian zones. There have been plans to fix these problems, mainly by constructing drop structures to control erosion.
