Spreading Navarretia (Navarretia fossalis) is found in Riverside County, San Diego County; Baja California, Mexico Vernal Pools and vernal swales are the preferred habitat of this small annual. A vigorous population grows in the "J" series of vernal pools near Dillon Road on Otay Mesa, a particularly outstanding, well preserved pool has recently been protected as a mitigation site, and has been fenced.