San Joaquin Marsh


Site San Joaquin Marsh

Map Tustin USGS 7.5' quadrangle

Location The San Joaquin Marsh is located within the City of Irvine, Orange County, one half mile east of Upper Newport Bay.

Contacts City of Irvine, Community Development Department, (714) 724-6411

University of California Natural Reserve System, San Joaquin Freshwater Marsh Reserve, (714) 824-6031

Sea & Sage Audubon Society, (714) 261-7963

Approximate Wetland Habitat Acreage 492
Approximate Historic Acreage The San Joaquin Marsh is a remnant of an extensive marsh and riparian system that existed along the Santa Ana River and San Diego Creek. No acreage specified.

Ownership Owner Acres Source

Univeristy of California 202 3

Private 378 3,6


Land Use Designation The Marsh is designated Conservation and Open Space in the City of Irvine's General Plan and Zoning Ordinance. It is designated Preservation Area in the Conservation Open Space Element.
Onsite Use The San Joaquin Marsh is the largest coastal freshwater marsh in Southern California. Campus Drive bisects the Marsh. The area west of Campus Drive makes up the San Joaquin Marsh Reserve, managed by the University of California Natural

Reserve System (UCNRS). UCNRS uses the Reserve for education and research. East of Campus Drive 30 acres of freshwater effluent ponds are protected by the San Joaquin Wildlife Sanctuary. The local chapter of the National Audubon Society operates a visitors center on the Irvine Ranch Water District's (IRWD) lands and provides educational programs. The IRWD sewage treatment facility is located on the eastern edge of the marsh.

Historic Use A portion of the Marsh was used for agriculture in the 1920's and 30's. 202 acres have been managed by the University of California Natural Reserve System since 1970. Ponds were managed for waterfowl hunting from the 1950's until 1988.
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The Irvine Ranch Water District's wastewater treatment plant was constructed with in the marsh in the 1960's.

Adjacent Use The Marsh is surrounded by urban development including a golf course to the east, a business/office area to the north, residential development to the west and UC Irvine to the south. Salt marshes and Upper Newport Bay Ecological Reserve lie to the west. The IRWD wastewater treatment facility is located on the eastern edge of the marsh adjacent to San Diego Creek. In San Diego Creek, adjacent to the marsh, the sediment is mined for its sand.
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Adjacent Historic Use San Diego Creek was dammed from 1936 to 1963 to protect the salt ponds at the upper reach of Upper Newport Bay. From 1954 to 1961 a landfill was in operation between the Marsh and Upper Newport Bay.


Tidal Influence The Marsh was once contiguous with Upper Newport Bay and subject to limited tidal action. Today, there is no tidal ciruclation, because San Diego Creek is leveed along the marsh. In 1993 a plank dam was installed just down stream from the southwestern corner of the marsh eliminating tidal action in San Diego Creek adjacent to the marsh.
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Watershed Area Water shed of San Diego Creek is 105 square miles. Watershed for the marsh is urban run-off from development to the south and west.

Tributaries and Flow Tributary Flow Source

San Diego Creek San Diego Creek is channelized and leveed adjacent to the marsh. Only a limited amount of water enters the marsh through managed culverts. The creek is perennial; winter flows can exceed 100 cfs and summer flows average 16 cfs. 1, 3, 6
Dams A sediment control plank dam was installed in San Diego Creek downstream from the marsh in 1993.

Other Sources Urban runoff, rainfall, water pumped from shallow dewatering wells and groundwater pumped from a deep well.


General According to the Regional Water Quality Control Board (RWQCB) 1991 general water quality problems at the Marsh include a reduced area of open water and increasing salinities. Orange County Environmental Management Agency found high concentrations of nitrate (15.3 mg-N/L) in 1995. Water quality is categorized as intermediate. The list identified the following areas of water quality concern; threats to rare and endangered species, increasing salinity, and heavy metal concentrations. Beneficial uses are mun, rec1, rec2, warm, biol, wild and rare.
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Dissolved Oxygen (DO) Not specified.

Water Salinity 1991- Water sources for the marsh are primarily freshwater. Salinities vary due to soil salinity and ground water intrusion. Salinities of 1 to 11 ppt were reported from the small pond near the deep well in July and UC Reserve ponds in January.
Sediment Over the past 200 years, the sedimentation rates averaged .02 inches per year.


Soil The Marsh is underlain by Pleistocene terrace deposits and recent alluvium. Soils found are: Omni clay, Chino silty clay loam, Thapto-histic fluvaquents, Balcom clay loam, Alo clay and Tidal flats.

Habitat Acres Vegetation Source
Seasonal ponds 127 1990 - swamp timothy*, alkali bulrush, fivehook bassia*, sweet clover*, prickly lettuce*, mustard*, Russian thistle* and foxtail chess* are present. 3
Tule Marsh 145 1990 - dominated by cattail and California tule 6
Seasonal wet meadow 33 1990 - pickleweed, saltbush, cattail and curly dock* are present. 3, 6
Willow-woodland/mulefat scrub 73 1990 - dominated by Gooding's willow, arroyo willow and mule fat. 3
Uplands 114 1990 - includes levees and roads, and ruderal area in the northeastern corner 3


Birds 1995 - 75 species of birds identified on Dec 31, including 49 water-associated birds and 7 special status species. 1990 - survey in April and June identified 12 special status species.
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Fish Not specified.

Benthic Invertebrates Not specified.

Insect Not specified.

Other Wildlife 1990 - three species of amphibians, 8 species of reptiles and 15 species of mammals were found in the marsh, including racoon, long-tailed weasel, gray fox, bobcat, coyote, pacific tree frog+, southerwestern pond turtle+, and western fence lizard+.
Special Status Species 1995 - California gull, american peregrine falcon, black shouldered kite, northern harrier, white-faced ibis, Cooper's hawk and black-shouldered kite. 1990 - survey also identified the light-footed clapper rail, California least tern, Swainson's hawk, least bittern, tricolored blackbird, pacific tree frog, southerwestern pond turtle and western fence lizard.
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Enhancement Status In 1996 a 6.08 acre mitigation site in the southwestern area of UCNRS was completed, providing open water and emergent marsh. The Irvine Company completed a 17 acre riparian mitigation project west of Campus Drive in 1990.
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In July 1996 the State Coastal Conservancy revised its 1991 plan for the restoration of the UCNRS portion of the marsh. The updated plan calls for increased water supply and open water areas, a new distribution system for threatened seasonal ponds and creation of public trails. IRWD has completed its EIR for a Marsh Water Supply Plan which provides open water and riparian areas in the area of the historic duck ponds on their lands. In addition, IRWD has proposed to reduce nitrates in San Diego Creek by circulation summer low flow creek water through these ponds. In a seperate, earlier plan which has not been implemented the Irvine Company's EIR for marsh enhancement (1995) identifies measures for increased water supply and circulation, a first flush basin, reconfiguration of open water seasonal ponds and planted habitat, and recreational trails.

Watershed Management Three sediment traps have been constructed on San Diego Creek to minimize sediment transport to Upper Newport Bay.
Pressure The San Joaquin Marsh wetland complex has become severely degraded over the past decade. Pressures include: insufficient water inflow to maintain historic habitat types, invasion by non-native plants, segmentation of the marsh by Campus Drive, sedimentation and poor water quality.


1 LSA Associates, Inc., prepared for the City of Irvine. 1995. Draft EIR for San Joaquin marsh enhancement plan. 175 pp. plus appendices.

This EIR was prepared to analyze the environmental impacts associated with implementation of the San Joaquin Marsh Enhancement Plan proposed by the City of Irvine. Issues addressed in the EIR include: impacts to wetlands, groundwater, surface water and soil saturation from the proposed water delivery systems; effects on all critical habitats and species; hydrologic effects of the Plan; land use compatibility; traffic effects; water quality; noise; air quality; cultural resources; soils; visual impacts and human health/vector control. The analysis was based on existing information. NOP comments and a traffic and circulation study are included as appendices. No field studies on the fauna or flora are included.

2 LSA Associates, Inc. 1995. San Joaquin freshwater marsh enhancement plan. 150 pp. plus appendices

The Plan includes information on the history of the marsh, hydrology, groundwater and biological resources, opportunities and constraints, and the Marsh enhancement plan. The Plan incorporates existing information.

3 California Coastal Conservancy prepared for the City of Irvine and the University of California Natural Reserve System. 1991. San Joaquin Freshwater Marsh enhancement plan. 90 pp.

The Plan includes information on soils, vegetation, wildlife, opportunities and constraints, groundwater, water quality, public access and enhancement alternatives. It includes estimated costs for Plan implementation and a management plan. Includes data from a July 1990 field survey for vegetation. Birds and wildlife were surveyed April 2-3 and June 14 -15, 1990.

4 Regional Water Quality Control Board. 1995. Water Quality Control Plan for the Santa Ana River Basin. 200 pp.

The plan includes information on the quality of inland surface waters, coastal waters, reservoirs and lakes and ground water in Orange County. It identifies beneficial uses potentially supported by these waters and provides a plan for their protection.

5 Regional Water Quality Control Board Santa Ana Region. 1995. Water quality assessment.

This information comes from the state's water quality assessment data base and includes the water quality assessment data for estuaries in Orange County. Information is presented for water quality (impaired or threatened), including a brief summary of the problem.

6 Romberg Tiburon Center and Philip Williams and Associates for the California Coastal Conservancy. 1996. San Joaquin freshwater marsh enhancement plan - revised plan for the University of California Natural Resource system. 28 pp.

The plan updates the 1991 Enhancement Plan (see source 3) to reflect changes in project boundaries and biota. The updated plan includes only property managed by UCNRS.

Data on soil type, wildlife and vegetation from the 1991 plan are incorporated by reference.

7 CH2MHill, Addendum to EIR for Irvine Ranch Water District's 'Wetlands Water Supply Project', 1996. Prepared for the Irvine Ranch Water District. 23 pp. plus appendices.

Ammended EIR describes diversion and then return of the water to San Diego Creek after reduction of nutrients (nitrogens) by bioremediation. Also contains a brief introduction on environmental setting, geology, biological resources and hydrology. Included in appendices is a Water Quality Analysis for San Diego Creek and Newport Bay.

8 Wandering Tattler. 1996. Sea & Sage Audubon, Orange Co., CA. 45:6.

Newsletter of the Orange Count Chapter of the National Audubon Society. Bird count is from the 1995 O.C. Coastal Christmas Bird Count.

9 Department of Fish and Game. 1989. Management Plan Upper Newport Bay Ecological Reserve. 265 pp.

Plan outlines management objectives and provides a discussion of relevant information relating to the resources of Newport Bay and relationship to San Joaquin marsh. Includes information on water quality, habitat types, invertebrates, fish, birds and mammals. Fauna species lists are contained in the appendices.



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