Ickstream Steel -
While it is the case that the Baker River steelhead are extinct (at least for all practical purposes) it remains moot whether there was consistent steelhead (or other anadromous fish) production above Diablo.

Most that have look at the stream channel in that reach concluded that there were likely velocity barriers in the canyon that effective end upstream migration. Now I could see that at rare times flows might fall into a area that might allow migrating fish to pass but such situations would likely happen so rarely that support an anadromous population over multiple generations would not have been possible (however such a situation may account for how rainbows and bull trout eached the upper watershed). The verbal records from the period daming also seem support that salmon did not reach the Ross Lake country.

I would not have been surprised that the resident rainbow trout population would produce some smolts but those returning adults would not have been able to return to those headwater reaches.

Tight lines
Curt