Mission of the ESF is to conserve and protect the Elkhorn Slough and it's Watershed. The Elkhorn Slough Foundation's mission is to conserve and restore Elkhorn Slough and its watershed. The slough is California's largest estuary outside of San Francisco Bay. Elkhorn Slough harbors extraordinary biological diversity and encompasses a dynamic working landscape juxtaposed with rich natural habitats. Elkhorn Slough Foundation meets its mission by the direct acquisition and stewardship of key lands and by work with partner organizations and agencies to promote sound scientific research that furthers understanding and conservation.