Reptiles Magazine San Mateo County Planning Commission approves environmental enhancement project for the snake. May 24, 2021 Thamnophis sirtalis tetrataenia), a subspecies of Thamnophis sirtalis that is only known to exist on the San Francisco Peninsula in San Mateo County, got a boost in it habitat May 22 when the San Mateo County Planning Commission approved an environmental enhancement project for the snake. Working with the land conservation agency Peninsula Open Space Trust (POST) and the San Mateo Resource Conservation District, a total of 16.7 acres of the snake’s habitat as well a...