About Us

San Joaquin Marsh Reserve protects some of the last remnants of wetlands that once covered much of Orange County’s flood plain. Located in an ancient river-cut channel at the head of Newport Bay, the reserve supports a variety of wetland habitats, including marshlands, shallow ponds, and channels confined by earthen dikes. Dry upland habitats with a remnant coastal sage scrub community rise on the margins of the reserve. The marsh is a critical stopping place for 100 migratory bird species using the Pacific Flyway. Altogether, more than 200 bird species (20 nesting) have been sighted in the reserve, including two resident endangered bird species: the light-footed clapper rail and the California least tern. The marsh is located within a ten-minute walk from UC Irvine, making it convenient for day use by faculty and numerous students.  

Ongoing Ecological Projects

Vector control, water quality improvement, and restoration of coastal sage scrub and wetland habitats.

Field Courses

Each year hundreds of university students in conservation biology, freshwater biology, environmental ethics, and other disciplines visit the reserve on class field trips; dozens more use the site for field studies and independent study projects.

Public Outreach

Environmental education programs for local elementary/ secondary schools; regional hiking and bike trail along the southern edge of the reserve; public tours of the reserve.

Selected Research

Habitat use and movements of coyotes in a Southern California urban environment. Effects of black sage on herbivore predation of purple needlegrass. Parasitoids and population ecology of the harlequin bug.
Wetlands production and fluxes of methane and other gases.
Pollen analysis of San Joaquin Marsh Holocene sediment. Special Research of National Significance North American Carbon Program: Determining California’s Carbon Budget

Reserve Facts


City of Irvine, Orange County; 75 km (45 mi.) southeast of Los Angeles, 30 km (20 mi.) west of the Santa Ana Mountains; 2 km (1.25 mi.) upstream from Upper Newport Bay, adjacent to the Irvine campus.


No on-site housing or laboratory facilities, but the reserve is adjacent to the UC Irvine campus.


Plant List
Herbarium and vascular plant collections vouchering the plant checklist; publications of reserve-based research.


Staff reserve manager on campus


82 hectares (202 acres)


2 to 3 m (7 to 10 ft.)

Average Precipitation

30 cm (12 in.) per year.

Average Temperatures

September maximum: 29 ºC (86 ºF)
January minimum: 4 ºC (40 ºF)
Annual mean: 17 ºC (62 ºF)