Unfortunately when people have different views on a matter people can get rather passionate. Don't let some people turn you off with their strong response to your view, as you shared your view with us.
We all love the river, and we want to see it healthy. Whitewater boaters want to see the river healthy as you do. American Whitewater is one of the primary organizations that whitewater boaters are involved with, and the health of fish and river life is one of their primary goals. The relationship between boathers and fishermen has been a rocky one, but we are all seeking the same goal.
I'm in Dayton, OH and we recently had an example of the same battle here. There was a lowhead dam that had created a pond, and those who enjoy fishing were upset about it's removal. Unfortunately the primary advocate for removal of the dam lost his life in the dam, as well as his wife. The dam was removed, and since that time the health and variety of fish at this location has exploded. You can read a news article here: River life thriving after removal of low Englewood Dam
There was no whitewater park with this project, it was just performed to remove a dangerous dam and restore health to the river.
What you see as far as the silt and mud when the lake went down is part of the damage that dams cause. Because there's no flow to keep that moving, it just settles in to create muck. In the long run that damages the fish, creating an environment that is only friendly to certain types of fish. With a project to remove a dam they will remediate that, and it will be established as a healthy stream. It may be more seasonal in it's flow, but the fish will be healthier.
We all really are on the same side, it just takes time to understand each other's viewpoint and that maybe something other than what we have always known can be better.