https://www.nps.gov/voya/planyourvisit/permitsandreservations.htm
There is a list of sites considered flooded and temporary closed on the voyagers website effective May 19th – June 1st. I would guess with the continued rise of the lakes the effective dates will be extended and additional campsites added.
I have a site for June 8th thru the 12th on rainy which is currently not on the list. We have not cancelled at this point but are leaning that way even if the site is not closed by the park due to additional hazards created by the high water.