Check out where the Blaeberry enters the Columbia river. You can park just off the trans-canada highway by the bridge over the Blaeberry river. Its a bit of a walk from there but worth it. Another spot is the Bluewater Rec area that isnt too far. You can also find fish in the Blaeberry itself, but the Columbia is best for numbers. Also Kinbasket lake can be good where streams dump in. I grew up there and Sept/Oct was one of my favourite times. Make sure to bring a heavy set up and lots of BIG white bunny style flies. The kokanee might be starting their run, but the bulls will probably be feeding on whitefish/suckers primarily. Wouldnt hurt to bring flies with some red on them, but not necessary in my opinion. Lots of bulls up to and around 10 lbs in there. Might be some rainbows, but I've always only been able to catch them in the spring.
Have fun, it's a gem of an area!