Perhaps Ron Goldfeder has some information on this turntable.

I was visiting the Healdsburg, California area about 10 years ago and stumbled upon a turntable located west of the Russian River, within sight of the bridge crossing the river. What railroad used this turntable, and is it still in place or has it been scrapped or maybe moved elsewhere?

Sorry I can't help on this one. I've only gathered info on ones moved for reuse by museums or tourist lines, with a couple of exceptions where they may be available to such users. Ones just used as bridges or abandoned in place fall outside that area and there are probably many of these.