Going to the festival for the first time in 2019. My wife and I will be camping at Illium. I would like to assure here that it’s not that primitive. So what are our options for showers? Seems like I have read something about the High School and also a trailer at another campground. Also that bathing in the river is prohibited. So any info would be appreciated. Already making our packing list in January 
When we camped in Ilium, we didn’t shower in the river, but took water from the river, and did make shift showers in our camp. Also pre fest in TP.
Yes there are showers at the high school. :thumbsup There is a water trailer at the campground, but that is about it. The river is to cold for me to bath in. Really don’t want about 850 people bathing in the river anyway. 
You can always build your own.
When we camped at Mary E, we grabbed showers in town. It’s extra stuff to haul in your back pack, but it’s the only option for hygiene.
We did get in the river, but nobody lasted for more than a couple of minutes. Yes, it’s that cold. (And camp as far from the river as possible. That would be to your “Right”, as you are driving in. That cold water generates cold air at night)…