RT & Others,
I don't believe there is any law or regulation that prohibits running a jet sled of any size on the Skook or most other rivers. Designated navigable waterways are regulated by the Coast Guard. Other waterways, rivers, and lakes in WA are regulated by county governments. We have a number of small lakes that have restrictions such as 5 mph speed limits or no combustion engines allowed. But the vast majority of waterways are not regulated. Common sense and courtesy are the limiting factors. And in this case, they didn't limit.
As for the physical suitability of the Skook to jet sledding, I remarked that I was surprised they even made it up the river, altho I don't know how far they really went. The Skook is littered with log jams and sweepers. So navigate around them you might think. However, the channel width is 50' or less in many places, and seldom equals or exceeds 70'. My sled is 16', and I don't think I could turn it around under power in most parts of this stream, because the shallow water would require this to be done with the boat on step, and at that speed, the turning radius is greater than the channel width. At an idle, I'm not sure if there is enough water deep enough to turn the boat, even with the vastly lower turning radius. Couple that with the assorted sweepers and log jams and you've got a river that isn't suited to motorboat travel.
I wonder if the guys who did this were just curious to see if it could be done.
Jetskis, anyone?
Sincerely,
Salmo g.