Bonita Creek
What is Bonita Creek Mitigation Site?
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Watershed - A geographic area that shares the same drainage such as a creek or river.

Tributary - A stream that flows into a larger stream or body of water.

Tributary Area - The area drained by a river or body of water.

Wildlife Movement Corridor - A relatively narrow passage through which wildlife moves on a daily and/or seasonal basis.

Culverts - A conduit (channel, pipe) used to enclose a flowing body of water. It may be used to allow water to pass underneath a road, railway, or embankment for example.

Upland Buffer - A protective strip
of native vegetation located between developed land and a lake, stream
or wetland.
History of Bonita Creek

Wetland Bonita Creek is part of the larger San Diego Creek watershed that begins in the San Joaquin Hills to the south and the Santiago Hills to the north. Bonita Creek was originally a natural creek and major tributary that flowed in a southwest direction to San Diego Creek and eventually drained into Upper Newport Bay and the Pacific Ocean. Its tributary area covered about 2,300 acres. The creek also served as a wildlife movement corridor and was an important link between Upper Newport Bay and more extensive habitats to the east of Bonita Creek. Similar to creeks throughout coastal southern California, the area around Bonita Creek consisted of floodplains and wetlands with dense willow woodlands that were used by a variety of birds and wildlife.

Changes to the natural creek began with the construction of Bonita Canyon Dam/Reservoir (at the southern end of the mitigation site). The dam was constructed by The Irvine Company between 1936-1937 as a water supply reservoir for part of the farming and ranching operations in the area. In 1963, the Coyote Canyon Landfill was built just upstream of the reservoir, further encroaching on the natural creek.

As the area around Bonita Creek was developed with agriculture, roadways, houses, and businesses, the creek was forced into a narrow channel that collected runoff from the developed areas. The willow woodland in Bonita Creek became narrow and patchy. While birds and wildlife still used the narrow woodlands, some bird species that required dense and broad areas of willows were not seen as much in Bonita Creek. In addition, culverts that carried the creek water under roadways created substantial barriers to wildlife movement along Bonita Creek. This was especially true at MacArthur Boulevard where the creek flowed under the road through a small, dark, uninviting culvert.

By 1994, Bonita Creek had become a narrow drainage when it was identified by the TCA as a mitigation site for the construction of the SR-73 toll road. The TCA planned and implemented the restoration of Bonita Creek from 1995 to 2001 to re-establish willow woodland, wetland marsh, and upland buffer. Today, Bonita Creek is a premier example of riparian restoration.