That's a great photo - Thank you for including it! I am not an expert in snake identification, but I would ID this as a Common Garter snake, which is our most variably-colored species of garter. There are excellent photos and species-specific notes about all of Oregon's snakes here https://www.dfw.state.or.us/wildlife/living_with/docs/LivingWSnakes.pdf
The garter snake species (and subspecies) are beneficial thanks to eating many organisms that commonly pester yard- and garden-owners, from slugs and worms (when snake is small) up to small rodents (larger adult snakes).