CFM,

You know the WDFW players in the region as well as anyone. Ask them. What is the answer? I agree; most chinook in the system anytime are GR hatchery fish. Guessing at an explanation for the closure, two things come to mind. 1) it might be a precaution to ensure hatchery escapement if chinook stack up in that section of the Toutle during low water; and 2) it might be a precaution to obtain natural spawning escapement above the sediment dam if chinook stack up in that section during low water.

Natural spawning in the Toutle apparently remains futile due to the ash, but spawning does occur in Alder Creek - maybe even for chinook although I don't personally know - and I think Elk Creek.

And of course, it could be that there is no biological reason for the regulation. Wouldn't be the first time.

Sincerely,

Salmo g.