You've got the right idea fishing streamers. And, yes, dark flies as LadyFisher suggested. Dark and Big so the fish can see it.
Stoneflies, larger nymphs.
Also, work the water by inches. By that I mean work every bit of the water because fish can only see a few inches with that type of discoloration and swift water movement. Work in a grid, if possible, like tic tac toe, maybe 6 inch or so increments so you'll gradually put the fly right to them.