This jogged my memory… a year or two ago I spotted a small brook trout that was far lighter in color than the others I could see on the sandy bottom of the pool. I was wondering if it had a type of albinism, but it was more of a pale gray than a yellow shade. Sadly, I was unable to catch it as it spooked under a deep undercut rock ledge which spanned several feet of the stream. Perhaps this was similar to your log jam, and certain fish fade to a lighter shade when they spend most of their time hiding in the dark. I’ve seen brook trout that were slightly lighter in color before, usually in a sandy stream with a light-colored streamed, but this was much more stark.
