The salmon are, without a doubt, present in the river itself, check the counts. I really think you'll be much more successful fishing the river, although not much success is being had there either. The salmon are in the river for sure, just don't give up and try every promising looking spot of water. When you walk away from a hole on a river you can't think "there aren't any fish in there" (because there probably are lol) you should think "I did something wrong, I'll switch my tactics and timing next time".
They are definitely there, just keep switching it up and eventually you'll get success. I'm not sure how well you would do fishing for salmon off a dock in a lake, really best bet is probably the river itself.