Dumping carcasses is for small streams that lack the returns that the lower rivers witness.
I have partaken in that joyous job and have a good understanding of the reasons why we fertilize streams and the methodology for it.
I am not suggesting that putting fish in a river is not helpful, but if you wanna make an impact, fill your truck box with those carcasses and haul them into the tiny creeks of the upper Chilliwack and then you will be actually bolstering nutrients WHERE they are needed.
When placing fert bags on the chilliwack, we do this many miles up feeder creeks where natural fertilizer is very low.
In the lower reaches you are better to leave carcasses where they are as the ones on shore are doing there part to seed riverside vegatation and provide meals for carrion eaters who actually fertilize via their droppings.
I understand you are trying to do some good GG, but it may be a reversal of what the system needs.
Mother nature suffers from our interventions enough, leaving the carcasses alone is important. Also consider the fisheries guys who do carcass counts as a form of fish counting, this would fak up their job also.