San Diego Creek
|San Diego Creek|
|- left||La Cañada Wash, San Joaquin Wash, Bonita Creek|
|- right||Bee Canyon Wash, Peters Canyon Wash|
|Source||Santa Ana Mountains|
|- location||El Toro, Lake Forest|
|- elevation||700 ft (213 m)|
|Mouth||Upper Newport Bay|
|- location||Near University of California Irvine|
|- elevation||0 ft (0 m)|
|Length||15 mi (24 km)|
|Basin||112.2 sq mi (291 km2)|
|Discharge||for Campus Drive at Irvine, CA|
|- average||61 cu ft/s (2 m3/s)|
|- max||43,500 cu ft/s (1,232 m3/s)|
|- min||0 cu ft/s (0 m3/s)|
San Diego Creek is a 16-mile (26 km) waterway flowing into Upper Newport Bay in central Orange County in the U.S. state of California. Its basin covers 112.2 square miles (291 km2) in parts of eight cities, including Irvine, Tustin, and Costa Mesa. The main tributary of the northeast-flowing creek is Peters Canyon Wash, joining a few miles above its mouth. San Diego Creek has been extensively channelized for flood control, but also provides important aquatic and riparian habitat both along its course and in its estuary at Upper Newport Bay.
The watershed is heavily urbanized with master planned residential and commercial development, although there are also large amounts of open space, nearly 15,700 acres (64 km2). Agriculture and high-tech industrial areas also feature prominently in the basin. The El Toro Marine Corps Air Base, which is being converted into the Orange County Great Park, lies along the tributary Agua Chinon Creek. Interstate 5 and Interstate 405 run southeast-northwest through the watershed, which borders that of Santiago Creek on the northeast, the Santa Ana River on the northwest, and Aliso Creek on the southeast.
San Diego Creek rises in the foothills of the Santa Ana Mountains near residential communities of El Toro, and Lake Forest. Most of its upper course is culverted under subdivisions of El Toro and Irvine. It flows northeast, fed by tributaries from northern Laguna Canyon and from the Santa Ana Mountains to the north of the creek. After crossing under Interstate 405 near the Verizon Wireless Amphitheater, the creek enters an artificial channel and receives Serrano Creek via an underground culvert on the right bank. Directly after the confluence, it passes under California State Route 133. It then flows northeast in a nearly straight course through East Irvine and the City of Irvine, receiving Agua Chinon Creek, Bee Canyon Wash, and the Marshburn Channel from the right. All these tributaries originate in the Santa Ana Mountains and are channelized for most of their lengths through Irvine. A few miles past the confluence with Marshburn Channel, San Diego Creek receives its main tributary, Peters Canyon Creek, on the right bank. The creek begins at Peters Canyon Reservoir in the Santa Ana Mountains and runs about 10 miles (16 km) south-southwest. Although historically it was a smaller tributary, due to present-day flood control purposes, the channel of Peters Canyon is wider than the channel of San Diego Creek when they join.
At the confluence with Peters Canyon Creek, San Diego Creek turns abruptly southwest, flowing underneath Interstate 405 for the second time. After flowing beneath the highway, San Diego Creek enters a series of slackwater pools, known as the San Joaquin Marsh, in the San Joaquin Wildlife Sanctuary. The partially man-made marsh stretches approximately 1.4 miles (2.3 km) to where San Diego Creek turns abruptly westward. The creek receives Bonita Creek on the left bank just a few hundred yards upstream frow where it empties into Upper Newport Bay, which eventually discharges into the Pacific Ocean.
The dry-season flow of San Diego Creek consists mainly of urban and agricultural drainage runoff. According to the Environmental Protection Agency, average dry-season flow at the mouth is 8 to 15 cubic feet per second (0.23 to 0.42 m3/s), whereas wet-season runoff can range from 800 to 9,000 cubic feet per second (23 to 255 m3/s). The average annual flow is about 61 cubic feet per second (1.7 m3/s), 44,200 acre feet (0.0545 km3) per year. An all-time highest flow of 43,500 cubic feet per second (1,230 m3/s) was recorded on December 6, 1997.
|Year||Streamflow (cfs and m3/s)|
|1978||9,080 cubic feet per second (257 m3/s)|
|1979||6,400 cubic feet per second (180 m3/s)|
|1983||15,500 cubic feet per second (440 m3/s)|
|1984||7,100 cubic feet per second (200 m3/s)|
|1985||3,040 cubic feet per second (86 m3/s)|
At Culver Drive, near the Irvine city center, 32 peaks were recorded. The largest five flows are given, in ascending order:
|Year||Streamflow (cfs and m3/s)|
|1952||4,040 cubic feet per second (114 m3/s)|
|1979||5,550 cubic feet per second (157 m3/s)|
|1978||6,300 cubic feet per second (180 m3/s)|
|1969||6,700 cubic feet per second (190 m3/s)|
|1983||10,400 cubic feet per second (290 m3/s)|
At Lane Road, which is well upstream of Culver Drive several miles below the headwaters of San Diego Creek, only three peaks were recorded:
|Year||Streamflow (cfs and m3/s)|
|1974||2,360 cubic feet per second (67 m3/s)|
|1975||4,000 cubic feet per second (110 m3/s)|
|1976||1,035 cubic feet per second (29.3 m3/s)|
San Joaquin Marsh
The San Joaquin Marsh is a long and narrow, approximately 500-acre (2.0 km2) man-made wetland that occupies the lower 1.4 miles (2.3 km) of the San Diego Creek stream course. About 150 to 300 feet (46 to 91 m) wide, it is separated into a series of ponds by low rock dams, which also regulate streamflow. The marsh utilizes an ancient, perhaps once abandoned, river channel that discharges into Upper Newport Bay. Roughly 100 migratory bird species currently use the marsh as a resting area, 20 nesting bird species are found, and a total of 200 different bird species have been cataloged. The marsh serves an important function cleaning the creek's polluted water before it flows into the estuary.
Currently the largest freshwater marsh in Orange County, San Joaquin was originally severely polluted and degraded, and was used at various points as farmland and a duck-hunting area. Before the 1950s and 1960s, San Diego Creek had followed a much shorter, channelized course to the bay, leaving the marsh dry. Agricultural and urban runoff also polluted the site, leaving a remaining trickle of wastewater running through the marsh. In July 2000, the City of Irvine, which owns 300 acres (1.2 km2) of the marsh in the San Joaquin Wildlife Sanctuary, contributed $1.5 million USD to its restoration, also with contributions from the Audubon Society and the State of California. The remaining 200 acres (0.81 km2) belong to the University of California and have been designated as the San Joaquin Freshwater Marsh Reserve.
A spreading ground, currently out of use, borders the marsh on the right bank, and the UC Irvine campus is on the left bank. Geologically, the marsh is an incised meander in the creek, bending southwards. The old diversion channel bypassed the meander, and while that is still in use, it is only used to pass water around the marsh section to relieve flood flows.
From north to south, the named tributaries of San Diego Creek are the La Cañada Channel (flowing from Laguna Canyon), Serrano Creek, Agua Chinon Creek, Bee Canyon Wash, Como Drain, Lyon Drain, Marshburn Channel, Coyote Canyon Channel, Peters Canyon Wash, Barranca Channel, Lane Channel, San Joaquin Wash, Sand Canyon Wash, and Bonita Creek.
The creek also has a few tributaries that provide the outflow for several water supply and flood control reservoirs in the San Joaquin Hills and Santa Ana Mountains. From source to mouth, these are La Cañada Channel (fed by Laguna Reservoir), Bee Canyon (two unnamed reservoirs), Peters Canyon Wash (Peters Canyon Reservoir), San Joaquin Wash (San Joaquin Reservoir) and Sand Canyon Wash (Sand Canyon and Strawberry Valley reservoirs).
The largest sub-tributaries include Borrego Canyon Wash (to Serrano Creek), Round Canyon (to Bee Canyon Wash), Santa Ana-Santa Fe Channel (to Peters Canyon) and Culver Drain (to San Joaquin Wash). There are many other ephemeral watercourses and drains in the watershed, but they are too numerous to list entirely.
||Santa Ana River||Santiago Creek|
|Laguna Canyon||Wood Canyon Creek|
- "San Diego Creek". Geographic Names Information System, U.S. Geological Survey. Retrieved 2009-06-18.
- "Introduction to San Diego Creek Watershed". Watershed and Coastal Resources Division of Orange County. www.ocwatersheds.com. Retrieved 2009-06-18.
- "San Diego Creek Watershed - Reports and Studies". Watershed and Coastal Resources Division of Orange County. www.ocwatersheds.com. Retrieved 2009-06-18.
- "San Diego Creek Watershed - Land Use". Watershed and Coastal Resources Division of Orange County. www.ocwatersheds.com. Retrieved 2009-06-18.
- "San Diego Creek - Watercourses and Elevation Ranges". Watershed and Coastal Resources Division of Orange County. www.ocwatersheds.com. Retrieved 2009-06-18.
- "San Diego Creek Watershed: MWRP Phase 2 and 3 Capacity Expansion Project" (PDF). www.irwd.com. Retrieved 2009-06-18.[dead link]
- Mehta, Seema (July 8, 2000), "Where Farmers Once Grew Crops, a Marsh Is Reborn. Wildlife: The Irvine Co., the Audubon Society and government officials collaborate on a project hailed as a model of public-private partnership", Los Angeles Times.
- "Freshwater flow and seasonal variation". Environmental Protection Agency: Newport Bay Toxics TMDL. epa.gov. Retrieved 2009-06-18.
- "USGS Gage #11048555 on San Diego Creek at Campus Drive". United States Geological Survey. nwis.waterdata.usgs.gov. Retrieved 2009-06-18.
- "USGS Gage #11048500 on San Diego Creek at Culver Drive". United States Geological Survey. nwis.waterdata.usgs.gov. Retrieved 2009-06-18.
- "USGS Gage #11048550 San Diego Creek at Lane Road". United States Geological Survey. nwis.waterdata.usgs.gov. Retrieved 2009-06-18.
- "San Joaquin Freshwater Marsh Reserve". University of California: Natural Reserve System. nrs.ucop.edu. Retrieved 2009-06-18.[dead link]
- Mehta, Seema (8 July 2000). "Where Farmers Once Grew Crops, a Marsh is Reborn". The Los Angeles Times. articles.latimes.com. Retrieved 2009-06-18.
- "San Joaquin Marsh: Southern California Coastal Wetlands Inventory". California Resources Agency. ceres.ca.gov. 1996. Retrieved 2009-06-18.