I am still in the learning process on this stream / trout fishing thing. The Chattahoochee River the only stream I have ever fished for trout. This is a tailwater fishery, typically 100 - 150 ft. wide of varying depths with lots of trees and other structure in the stream. I understand the upper layer of water is frequently traveling faster than deeper water and you ned to mend upstream fishing a nymph so the fly travels at the same speed as natural foods and materials. BUT, if you are fishing a streamer, imitating a swimming animal, fish, etc., which (at least in my old bald head) be traveling a little faster than the stream if moving down stream, Doesn't letting your surface line pull the streamer faster than the deep water current make sense?