i've fished the tiny feeder creeks to the Buckinghorse & Sekanni Chief rivers while up there hunting and have caught tonnes of 'em on a dry fly, weird that you aint gettin them. Also fish a lake just before the Sekanni River, you turn left. (cant remember the name)....from the dock and caught lots. Has rec site there, supposebly large rainbows in there too. Also had good luck on the Moberly & Sukunka.
They're very easy to catch, but keep you line behind your fly/lure or they wont hit.
The Peace and halfway rivers should be good too.