The West Coast garter snake (Thamnophis validus), also known commonly as Kennicott's water snake, is a species of snake in the subfamily Natricinae of the family Colubridae.

T. validus is found in the Mexican states of Baja California Sur, Chihuahua, Guerrero, Jalisco, and Sonora.

[2] Nota bene: A trinomial authority in parentheses indicates that the subspecies was originally described in a genus other than Thamnophis.

The subspecific name isabelleae is in honor of the American wildlife artist Isabelle Hunt Conant, the wife of the American herpetologist Roger Conant.

This article relating to Natricinae is a stub.