Aliso Canyon

Aliso Canyon is a 6.5-mile (10.5 km) 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. Aliso Canyon is a massive gap through the south-central part of the San Joaquin Hills. The San Joaquin Hills are a small coastal mountain range in Orange County, about 20 miles (32 km) long and 5 miles (8.0 km) wide. The Aliso Canyon is about 6.5 miles (10.5 km) long measured from where it begins near Laguna Niguel Regional Park to its outlet at Laguna Beach. About 800 feet (240 m) deep on average and 1.5 miles (2.4 km) wide at its widest extent, it is one of the largest gaps through the San Joaquin Hills. Others include the Laguna Canyon and the San Juan Creek canyon. The valley has three distinct sections: the first, upstream one is a broad and comparatively shallow stretch 400 feet (120 m) deep and 1.3 miles (2.1 km) wide; the end of this section is marked by a small summit to the south. The second longest stretch is 1.5 miles (2.4 km) wide, 800 to 900 feet (240 to 270 m) deep, and about 4.5 miles (7.2 km) long, stretching from the Wood Canyon Creek confluence to a wastewater treatment plant near the o

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