Charlie, Sorry I was detained by "honey-dos" in advance of my folks coming in to town this weekend. I would have much preferred chasing brookies.
As far as Mannis Branch is concerned, I wonder if maybe you were attacking it from the wrong spot. Take a look at the following .pdf from the 90s (go to page 47). http://www.sdafs.org/meetings/99sdafs/abs99.pdf
Where Mannis Branch enters LR is pretty low in elevation and has a pretty steep gradient. It may be that the brookies were introduced higher up, near the Meigs Mtn Trail. The stream is more manageable at that point. Its not too bad of a hike across from Jakes Creek.