Some Arse brought POISON IVY into Grand Canyon National Park and the shores of the Colorado River! So if you're in the 80% susceptible, BRING TECNU SOAP to wash AM and PM.

I was 13 days on the Colorado River and neither NPS nor the not-cheap Outfitter warned me, or carried a quart bottle of Tecnu soap liquid from Amazon!

12 days of constant itching, painful arm and leg rashes,  soaks in the 36f river,  lousy nights sleep in a hot Summer small nylon tent to keep the rattlesnakes away,  and 120f IN THE SHADE scorching days,,, 13 !! Never Ever again in the Summer. Period.

Suggest You raft in Spring or Autumn INSTEAD.
And bring or buy Tecnu concentrated liquid soap as a regular washing soap additive,  especially in coastal CALIFORNIA and the Sierra FOOTHILLS to about 6000ft elevation!