Ditto the advice above, August is way too early. It is a vicinity of Sept. 15 proposition. Fishing the Skeena system is not cheap, and they feed on the foreign angler. Trips are priced in American dollars, not loonies. There is a licensing regimen up there for guides, which appears to be fairly expensive or limited in quantity. There are also pirates, or unlicensed guides that can be hired, but that can be a hamper if you want to make a public claim to a trophy fish.

That is the big-time for steelheading, and will frustrate the heck out of you if you are not an experienced steelheader and prepared for variable weather and low catch rates. It can easibly be a 1-3 fish per day experience for $450 plus and a lot of places are booked well in advance (or were as recently as 2001 when I was last there, the economic conditions may have changed that.)

You don't say how much steelheading you have done. Due to catch rates, expense, difficulty in booking, and the technical nature of the fishing, the Skeena system is not the place to start, IMO. Fall trips to Great lakes tribs or perhaps the Deschutes in OR are good, cheaper alternatives. On the other hand, if you have been-there, done-that, the Skeena system is a nice graduation trip and offers the chance to a patient angler to catch the steelie of a lifetime. Be sure to check out the two fish mounted and located inside the govt office in Smithers if you go. Big 'uns.