These were upstream from the RV park. Two possibilities. Either the kids dump them in the river to turn it funny colors and confuse the tourists, or they stick their heads in the water and then lather this stuff in, for a quickie dye job.

I feel real pity for whatever teenagers live here. They must be bored out of their skulls. Later on I saw a group of them exit the lodge, and prowl into the woods upriver, right around this spot. That explains the jarring quantity of litter concentrated here.