For rafting flows, the "higher the better" applies... just to not scrape. Thus, everyone applies for May-June permits.
For small rafts and kayaks, lower flows are totally okay. The releases are convenient for weekends and off season runs.
April - Low flow, you'll have the place to yourself. Canadian Geese nesting paradise I've learned.
June - good flows, crowds, and more crowds.
September & August - random medium high flows, few (if any people), fall colors.
Great run for kids and beginner kayakers.
Upper is beautiful mini canyon lots of what look like old growth forest.
Sadly, this place has lost some of it's mystique... with the cabin going up in smoke, and a new road cut into the hill on river left, down to the river. Looks like someones future dream home site... last fall it was just the new scar and a bunch of no trespassing signs. Hopefully they like river runners.