I spend quite a bit of time up at the loup canal, it is a snag infested nightmare, and thats why it it a great place for flatheads, you can go through some tackle there but there are definately some big smart flatheads up there, heavy gear is an absolute must have up there with the normal 30 mph current a fish can get sideways and really put a workout on a rod and reel. But if you like big flatheads it can become an addiction fishing that place, I promise there are more than one new state record fish swimming in there,only a matter of time....... anyway sounds like you know the area pretty well, way ahead in the game already! the fishing should be getting hot at harlan here soon for cats, but Ks lakes are usually better and closer for me.