March 28, 1806, on Deer Island, above Cowlitz River, Washington.
Black with well-defined narrow back stripe, red blotches on sides, top of head red; in northern part of range black pigment usually extends onto belly; in California, black ends at indistinct light side stripe. Length: 18-51.6 in (45.7-131.1 cm).
Near waterówet meadows, marshes, prairie swales, irrigation and drainage ditches, damp woodland, farms, parks; sea level to 8,000 ft (2,450 m).
Northwestern Oregon and extreme southwestern Washington; coastal California, Humboldt County to San Diego County Valley.
The most commonly encountered snake in many parts of its range.