He was swimming around under some water plants.
My best guess is Taricha torosa based on location
This species of newt was discovered next to a small pond under a log. It was the only one found in the area. It was fairly small (roughly 3.5 inches long).
I saw a small California newt baby, about an inch long, under log, and had smooth skin.
The California newt or orange-bellied newt, with scientific name Taricha torosa, is a newt species endemic to California, in the Western United States.