 Fish and Wildlife Service alludes to historic populations in Contra Costa County and Santa Clara County.More specifically another source defines the extended historic San Francisco Bay Area range to have extended from Richmond to Palo Alto By the year 1995 the populations of "L. conjugens" had declined to the point where there were only five colonies extant, all of which were within Napa and Solano Counties.Contra Costa Goldfields has been studied extensively with regard to genetic diversity of colonies.