It's Latin name sounds pretty scary -Thamnophis sirtalis infernalis. California Red-sided Gartersnakes are only found on the California Coast from Humboldt County south to Monterey Bay. Peter Baye recently photographed one found along Tenmile River.
They have a toxin in their saliva which can be deadly to their prey. They are not considered harmful to humans but I wouldn't want to be bitten by one. Their bite could cause an adverse reaction. California Red-sided Gartersnakes eat a wide variety of creatures, including Banana Slugs. Gartersnakes are the only known creature that can eat Rough-skinned Newts.
They are great swimmers and will often retreat into the water if threatened. C'Anna Bergman Hill photographed this Red-sided Gartnersnake in a creek on the Stornetta Public Lands.
Thanks to Peter and C'Anna for allowing me to share their photos with you here.