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San Joaquin Marsh and Wildlife Sanctuary

San Joaquin Marsh and Wildlife Sanctuary



Public Access: Yes

Conservation status: Not Identified as Protected

Adjacent Land Use: Residential - high density

Approximate natural buffer width: No Natural Buffer

Other information: Since the initial restoration of the San Joaquin Marsh in 1996, the number of residents in Irvine has increased from ~127,000 to 267,000. This population rise subsequently increased urbanization of surrounding land, which impacted the volume of pollutants entering the San Diego Creek and Newport Back Bay.

Is there any other information that should be conveyed regarding your nomination of this wetland? The San Joaquin Marsh is also home to a variety of RTE species such as the Least Bell's Vireo, Long Eared Owl and Western Pond Turtle!

The San Joaquin Marsh and Wildlife Sanctuary is a 300-acre coastal freshwater treatment wetland comprised of a series of pond and riverine systems located in Irvine, California. It was originally developed for the purpose of recreational duck hunting but was restored in the late 1990's to a more natural habitat with the intention of improving local water quality. The marsh effectively removes aquatic pollutants from the San Diego Creek via natural biogeochemical processes. This subsequently enhances habitat quality and biological diversity for the downstream ecologically sensitive marine habitat of the Upper Newport Bay. Routine monitoring of water quality, sediment composition, vegetation and wildlife has provided data and insight into best management practices for freshwater treatment wetlands in a region deplete of these crucial natural resources. The marsh has become a refuge for wildlife in an otherwise heavily urbanized southern California region and is home to over 200 bird species, some of which are species of special concern in California.

As a pioneer of constructed treatment wetland technology in the region, the San Joaquin Marsh attracts various agencies and researchers who are interested in implementing this technology elsewhere. The Irvine Ranch Water District in partnership with Sea and Sage Audubon Society hosts academic programs to engage the community in natural history and ecological education. Over twelve miles of trails traverse habitats ranging from coastal sage scrub to shallow open water ponds to riparian forests, which attracts visitors for both recreation and scientific research. Currently, researchers from the University of California Irvine, Concordia University, Chapman University and various local high schools are utilizing this wetland system in order to understand the biogeochemical processes within coastal freshwater systems.

Exemplary Ecosystem Services:

  • Maintains ecological connectivity/cohesion
  • Aesthetic/cultural heritage value/ provisioning
  • Recreation (birdwatching, ecotourism)
  • Storm abatement
  • Flood storage/mitigation
  • Water quality improvement
  • Education


Approximate size: 121

General wetland characterization: Inland Open Fresh Water

Adjacent Water Bod(ies): Stream

Name of body of water: San Diego Creek

Surficial Geology: The surficial geology of the region that contains the San Joaquin Marsh is considered young alluvial valley deposits (

Soils: Chino Silty Clay Loam


Dominant flora: Mulefat, Bulrush, Cattails, Willows, Sycamore, Coyote Brush

Unique flora: Opuntia spp. (Beavertail Cactus), Yerba Mansa, coast live oak

Dominant fauna: Coyote, Desert Cottontail, Common side-blotched lizard, Alligator lizard, California Ground Squirrel, Great Blue Heron, Snowy Egrets

Rare fauna: American White Pelican, White -Tailed Kite, Osprey, Mexican Free-tailed Bat


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