Not Dangerous (Non-poisonous) - This snake does not have venom that is dangerous to most humans.
Gartersnakes have toxins in their saliva which can be deadly to their prey and their bite might produce an unpleasant reaction in humans, but they are not considered dangerous to humans.
The species Thamnophis sirtalis - Common Gartersnake, has the largest distribution of any gartersnake, ranging from the east coast to the west coast and north into Canada, farther north than any other species of snake in North America.
This subspecies, Thamnophis sirtalis infernalis - California Red-sided Gartersnake, is endemic to California, ranging from Humboldt County south, along the coast ranges (excluding much of the San Francisco peninsula) and east of the San Francisco Bay along the central and south coasts to San Diego County.