Third week might be a little late....but it all depends on the weather. When fishing the head the fish gather around the river mouths and will head up when there is enough water. The first big rain in august usually gets things happening. It can be early or it can be late, you never know. The Coho should be thick around that time of year. Might even be springs hanging around but if you are looking for trophy fish then the first two weeks of August is prime time at the head. Probably the last two weeks of July and the first week of August are prime time at the mouth. Hakai is probably earlier still. This doesn't mean there won't be fish, just that the odds of big fish being around are greater.