Cowlitzfisherman,
Checked in my office about the mechanical current by pass on the cowlitz.. It was used on the upper section as a way to get smolts into a fish holding area so they would not go over a spillway and smash against the concrete at the bottom. What happens after the smolts get into the holding area I'm not sure but I know you must know the situation up there. If you have never been up to Rocky Reach Dam on the Columbia you should. They still have the smolt pilot plant runing as far as I know. I've also heard that they plan to go even further on the Cowlitz with by pass project and it will be big bucks to do so. The cost for Rocky Reach full project is at or over 60 million dollars but that's a lot bigger dam than those on the Cowlitz.