Steelhead caught in Lake Mendocino

Could there be lake "steelhead" in lake mendo?  Like in lake sonoma.  Residual stock from before the dam that still run upstream to spawn, but use the lake like the ocean. I don't know how big the north fork is there (is it the north fork?).  Rainbows and steelhead sure are interesting fish.  They do it all.

There are multiple tributaries to the the Lake other than Cold Creek.  The East Fork watershed is pretty big, around 100 sq. miles.