Columbia is tough to fish but if you want to go there go to the fly shop in Castlegar and get as much info as possible.
Elk river is great!!! Same thing. Go to one of the fly shops in Fernie. They're gonna wanna guide you though.
Stop at the Crowsnest for a day. Awesome river too. Go to the Crowsnest Angler.
It's possible to fish the creek mouths of Kootenay Lake from shore in Kaslo and Woodbury. Also can catch Kokanee of the wall below Ainsworth.
From Kaslo drive up the road to New Denver (Slocan Lake). Along the way there are creeks to fish as well you will pass Fish Lake and Bear Lake. You can fish a bobber and worm or maggots at those lakes and catch panfry-18" rainbows.
Once in New Denver and Silverton on Slocan lake you can fish the creek mouths in each town. Every year someone catches a 20 lb rainbow and a 20 lb dolly from shore. Beautiful camping and swimming lake. At night you can toss a worm on the bottom and catch big burbs which are referred to as ling out there.
Continue along the road South along Slocan lake until you get to the South Slocan junction. From there you can turn left to Nelson (Kootenay lake) or Castlegar (Arrow Lake and the Columbia). Lots of creek mouths to fish from shore on arrow lake too.
You can't do it all in 5 - 7 days but whatever route you take in whatever order, there's tons of great shore fishing along the way.
Have a few fish frys and enjoy the beautiful country. You can't go wrong heading West. Only problem is choosing where to go.
Been fishing the area for 40 years.
Grew up there.
Cheers