Correction (I just looked it up) it was probably a king snake -
California represents home base for both the California King Snake
and the California Mountain King Snake. A small population of both species spill over into the Siskiyou Mountains of southern Oregon.
A very colorful thing it was. Looked like an aquatic coral snake in coloration -
but I doubt that it wandered inland 50 miles from the ocean.
Which is good - coral snakes are poisonous, but king snakes are mostly harmless.
The snake disappeared under the house (crawl space) and I never saw it again.