Well put rowswell.
There are also many coastal cold water streams not lacking water volume equally vacancy of life. There is scientific explanation for this all from water quality samples and the study in effects of acidic deposition. I have been attempting to expose this but have limited success. There is endless finger pointing here but I am confident it is mostly natural and none of the accused users of the resources are to blame.
I have many past posts and started threads on the topic you may find interesting if you search my historic posts.
From my research, invertebrate sampling and water quality testing it appears the situation is improving. It keeps me hopeful anyway.
With respect, I'm unconvinced that the problem rests solely within acidification of rivers. We have lots of very good evidence of large healthy smolts out-migrating into the ocean, only to suffer very high ocean mortality.
Acidification cannot be the casual factor of decline there.
So the problem is multi-faceted - in other words salmon are dying the death of a thousand cuts. Little bit related to habitat (including acidification), and a little bit from not enough food in the food web to feed them when they are in the near estuary ocean where they are most vulnerable, ...and a lot to do with predation from harbour seals, and of course fishing exploitation. Its a complex set of problems, each with their equally complex solutions. But if we don't do something fairly significant soon, there will be nothing left.
Chinook started this strong down cycle in a much more abundant state than steelhead, but are now following precisely the same pattern of decline. Now when you look at steelhead they are almost extinct everywhere, and in rivers where there is NO commercial fishing. Further, in river systems like the Keogh River (an indicator study stream) where we know precisely how many steelhead out-migrated they have disappeared into the abyss....how is that related to acidification? It is not. It has something to do with "ocean survival"...ergo, either predation or lack of food to sustain Chinook and Steelhead as they first out-migrate into the ocean and starve to death.
Could it be that all our BS is just that? BS...because we focus on our pet theories and issues, but fail to step back and look at an ecosystem wide problem and set of solutions to match those problems. Fish live in complex interdependent relationships within a diverse ecosystem. Humans tend to see problems in simplistic singular direction problems because we are most comfortable when we can attach a tag or label to something. That is how we experience and make sense of our world - by attaching labels, not by stepping back to try to make sense of complexity - little wonder we have some difficulty "managing" wildlife that depend on complex ecosystems.
My 2 cents.