|Cañada de Las Lagunas|
Laguna Canyon near where California State Route 73 crosses it
|- left||El Toro Creek|
|- right||Laurel Canyon Wash, Little Sycamore Canyon, Willow Canyon Wash|
|Source||San Joaquin Hills|
|- elevation||380 ft (116 m)|
|- elevation||0 ft (0 m)|
|Length||7 mi (11 km)|
|Basin||10.5 sq mi (27 km2)|
|Discharge||for Pacific Ocean|
|- average||0 cu ft/s (0 m3/s)|
|- max||2,000 cu ft/s (57 m3/s)|
Laguna Canyon (also called Cañada de las Lagunas, Spanish: Lagoon Canyon, informally Laguna Greenbelt) is a canyon, formerly a water gap, that cuts through the San Joaquin Hills in southern Orange County in the U.S. state of California, directly west of the city of Irvine. The canyon runs steeply northeast-southwest, drained on the east side by San Diego Creek and on the west by Laguna Canyon Creek. Starting as a wide and shallow valley, it narrows to a steep gorge as it nears Laguna Beach. California State Route 133 runs the entire length of the canyon connecting Laguna Beach and Irvine, while California State Route 73 crosses it, running southeast-northwest. A majority of the canyon is located within the Laguna Coast Wilderness; small portions are part of Aliso and Wood Canyons Regional Park and the cities of Irvine, Laguna Beach, Laguna Woods and Aliso Viejo.
Geography and geology
Laguna Canyon is a generally north-south running gorge approximately 8 miles (13 km) long and 1 mile (1.6 km) wide at the broadest points. The city of Irvine lies to the north, Lake Forest and Aliso Viejo to the east, the undeveloped San Joaquin Hills to the west, and Laguna Beach to the south. The drainage divide of the canyon is located near its northern end, separating Laguna Canyon from the San Diego Creek watershed.
California State Route 133, alternatively called the Laguna Canyon Road, winds through Laguna Canyon for the entire length of the gorge. California State Route 73 bisects the gorge east-west. The lower section of the canyon is contained in the Laguna Coast Wilderness, while the upper section is contained in a few smaller wilderness preserves. Some of the lower section has development, but the upper section remains relatively undeveloped. The northernmost extreme of the canyon lies near a residential area that adjoins Interstate 405.
The canyon was most likely formed by San Diego Creek cutting through the rising San Joaquin Hills over a span of about 1.22 million years. At some point, however, the creek changed course, and the water gap it had formed was walled off by the mountains and became a separate watershed. The gradient of the drainage divide separating Laguna Canyon and the San Diego Creek watershed is, however, very small.
Laguna Canyon Creek begins as an ephemeral creek that drops from a mountainside west of the valley floor down into the canyon. It crosses under CA State Route 133 (Laguna Canyon Rd.) and enters a series of box culverts before spilling into a tree-lined channel. It soon passes the Laguna Lakes and receives Little Sycamore Canyon from the right; this creek drains a narrow side canyon which runs about 2 miles (3.2 km) eastward. The creek continues southward, and then passes beneath Laguna Canyon Rd. again and receives Camarillo Canyon, a short and steep tributary, from the right.
The stream then runs south under the twin California State Route 73 bridges and enters an underground culvert beneath an onramp. While in this culvert, Laurel Canyon (which harbors a 100-foot (30 m) waterfall) and larger Willow Canyon join from the right, then about 0.5 miles (0.80 km) later, the creek re-emerges from underground and flows in a riprap lined channel for the next few miles. It receives its major tributary, El Toro Creek, from the left. El Toro Creek, which follows El Toro Road for much of its length, drains parts of Laguna Hills and Aliso Viejo before emptying into Laguna Canyon Creek.
The creek turns sharply west and then back south, then shortly after, is forced into a concrete-lined box culvert that carries it through downtown Laguna Beach (This stretch is also known as Broadway Creek.) It then is diverted completely underground and its channel winds to an outfall at Main Beach, one of the most popular beaches in Laguna Beach.
Laguna Canyon and its side tributaries have received some man-made flood control modifications. These include debris basins at the mouth of nearly every major tributary, stretches of lined or unlined flood control channels, and other structures. The debris basins, sometimes called retention basins, are circular depressions constructed by the Orange County Flood Control Division to slow down flash floods. The upper Laguna Canyon area has a few flood control channels and the lower creek is encased entirely in one; this begins as a riprap channel with an unlined bottom, which transitions to a concrete culvert.
There are few developments within the main canyon, although the El Toro Creek area is primarily residential. There is also some commercial development downstream of State Route 73. Notably, where the creek passes through Laguna Beach, the concrete channel is undersized for the creek's peak flow, which caused it to overflow in the late 1990s.
The Laguna Canyon area supports mostly native Southern California wildlife, including large mammals such as mountain lions, bobcats, coyotes and mule deer . Like Aliso and Wood Canyons Regional Park to the south, the canyon supports over one hundred species of birds. Some of its endangered species include California Gnatcatcher, Cactus Wren, and Orange-throated whiptail. Except for the Laguna Lakes, the canyon has no fish habitat, and riparian habitat is at a minimal because of extensive modifications to the canyon's waterways and the ephemeral nature of the creeks.
In the canyon, [coastal sage scrub], which is the dominant vegetation cover, typically goes through approximately 25-year cycles, with its peak biodiversity reached in roughly 10 years after the beginning of a new 25-year period. Such periods are typically separated by wildfires, which clear away dead or dying vegetation and leave bare ground for new growth. Another 40 or so plant species constitute the primary vegetation cover in the watershed. The canyon is one of the last remaining sanctuaries for many plants native to Southern California. Although chaparral is the primary vegetation, the canyon also has a wide variety of other plants; approximately one hundred species of plants, most native to California, are found in Laurel and Willow Canyons alone. These include monkey flower, goldenrod, and sagebrush.
Laguna Canyon forms the center section of an approximately 17,500-acre (71 km2) strip of wilderness preserve running northeast-southwest along the Pacific coast. Most of the canyon is covered by Laguna Coast Wilderness, which extends over 6,500 acres (26 km2). It is bordered on the south by Aliso and Wood Canyons Regional Park, and on its north by Crystal Cove State Park. The parks are managed by the County of Orange and the California Department of Fish and Game, while portions of Laguna Coast are also owned by the City of Laguna Beach. Although there is no trail that follows the main canyon (as it is traversed by State Route 133), there are many trails, mostly hiking, that lead up narrow side canyons, as well as a trail that circumnavigates Laguna Lakes. Several connecting trails run east-south towards Aliso and Wood Canyons, providing access between the two watersheds.
Lying to the north of Aliso Canyon, the Laguna Canyon area lay within the tribal boundary of the Tongva, a Native American group whose territory expanded from north-central Orange County well past the San Gabriel River and into the Los Angeles Basin. Aliso Creek, whose watershed borders Laguna Canyon to the east, formed the tribal boundary between the Tongva and Acjachemen.
Laguna Canyon Creek was a seasonal stream but the Laguna Lakes, formed by springs arising from a minor fault zone, stayed year round. A Native American path ran through the canyon to the present-day Laguna Beach area, where they collected abalone and limpets, and fished. The Tongva lived in villages of 50-100 members, in huts made of brushes and tules on a wooden framework. When the Spanish conquistadors arrived in the mid-18th century, they named the canyon "Cañada de las Lagunas", referring to the Laguna Lakes. A land grant, called La Bolsa de San Joaquín, occupied the canyon area up to the 19th century. By 1905, springs in the Laguna Canyon area began to supply water to Laguna Beach.
Before Laguna Canyon became a wilderness park, a housing development was proposed to be built in and around the canyon, tentatively called "Laguna Laurel". The 2,150-acre (8.7 km2) community, which was proposed to contain 3,200 housing units as well as a number of businesses, was canceled in the 1990s after the City of Laguna Beach purchased four of its parcels in order to provide space for a wilderness park, while the City of Irvine purchased one, and Laguna Coast Wilderness Park was opened and dedicated in 1993. Occasionally, the park system (which adjoins Aliso/Wood Canyons Regional Park) is augmented by donations of vacant land. The proposal to stop the development was supported by a crowd of eight thousand in 1989, which gathered in Laguna Canyon in a protest known as the "Walk-In". Several years later, two to three thousand gathered to protest the construction of California State Route 73 (which would cross the canyon), but the highway was built eventually.
In 1993, a massive wildfire burned over 16,000 acres (65 km2) in Laguna Canyon and Laguna Beach, and ranked behind the 1948 Santa Ana Canyon fire as one of the worst fires in Orange County history. The fire was in part caused by strong Santa Ana Winds, which caused flames that rose up to 200 feet (61 m) high.
The canyon is one of the last remaining wild areas in Orange County in a strip of preserves along the San Joaquin Hills about 20 miles (32 km) long and 8 miles (13 km) wide. Recently, State Route 133 has been expanded to four lanes from the original two lanes; the original road is now a one-way southbound. The newly constructed road is mostly parallel to the original road but is closer to Laguna Canyon Creek. Recent construction work at the head of Laguna Canyon near the city of Irvine has leveled some hills on the east side of the canyon, but construction has presently stopped. There are plans to turn the northernmost extreme of the Canyon into a residential development consisting of 590 houses, called Laguna Crossing. It was originally planned to open in 2008 but this date has been moved to 2013. There also has been work on culverts in the northern part of the canyon.
The entirety of the mainstem of Laguna Canyon has been impacted by development, mostly from construction of the state highway but also from buildings in the canyon in the last 3 miles (4.8 km). Most of the remaining wild lands are now found in the side canyons. These modifications have also resulted in bacterial pollution downstream at Main Beach, Laguna Beach. There now are several organizations working on preserving what remains of the canyon; Laguna Canyon Foundation is the most prominent one.
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