Pacific Southwest Region
California, Nevada and Klamath Basin

Critical Habitat Designated for San Diego Ambrosia

Nov 29, 2010

FOR RELEASE:  Nov. 29, 2010

CONTACT: Jane Hendron, U.S. Fish and Wildlife Service 
Phone: (760)431-9440, ext. 205

Critical Habitat Designated for San Diego Ambrosia

CARLSBAD, CA -- The U.S. Fish and Wildlife Service (Service) announced today its final designation of critical habitat for the federally endangered San Diego ambrosia plant (ambrosia pumila).  Approximately 783 acres of land in portions of Riverside and San Diego counties are included as critical habitat.

The Service initially proposed 1,140 acres of land, but excluded 329 acres from the final designation.  Lands identified as essential to the conservation of San Diego ambrosia that are excluded from the final designation are being conserved and managed under the Western Riverside County Multiple Species Habitat Conservation Plan and the San Diego County Multiple Species Conservation Program.

The final economic analysis estimates incremental costs to development in areas designated as critical habitat will be less than $9,000 over the next 20 years (using a 7 percent discount rate).

San Diego ambrosia has a branching root structure that spreads horizontally underground sprouting new stems each year. These stems generally grow 2 to 12 inches high and produce yellowish to greenish-colored flowers from May to October. The plant produces very few seeds, diminishing its ability to spread and colonize unoccupied areas.

The plant is primarily associated with native and nonnative grassland communities, and openings in coastal sage scrub.

A copy of the final rule without the maps is on public view at the Federal Register today – FR public view.  The official copy of the final rule will publish on November 30, 2010. You may also view copies of the final rule, economic analysis, and public comments received on the Internet at

The mission of the U.S. Fish and Wildlife Service is working with others to conserve, protect and enhance fish, wildlife, plants and their habitats for the continuing benefit of the American people. We are both a leader and trusted partner in fish and wildlife conservation, known for our scientific excellence, stewardship of lands and natural resources, dedicated professionals and commitment to public service.

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