I hate to say it, but how many places can people really go tubing in Western Washington? I think it's a good use for that part of the river and I don't think it will hurt the fish other than scaring them.
I’d like to see commercial tubers and paddle board outfits be responsible for bi-weekly trash cleanup during their operating seasons on sections of the rivers the use for business. Attach it as a condition for their use permit.
Wow, I fished the Snoqualmie starting in the early 70’s and can’t begin to remember how many steelhead we got between Plums Landing and Fall City. I think I caught my last one ten or twelve years ago just below the Raging river on a cold day in January. I understand your angst over the tubers, but long before they arrived the fishery was pretty much gone. And it isn’t coming back. There’s over two million people living in King County today. Frankly, I hope more of them go tubing and fewer take up fly fishing.