How to save 4x5 images of artwork, slide images of artwork in 1 foot of water?

If possible, you'll want/need to immediately separate the film sheets or strips while still wet, and remove them from any archive sleeves, and store them immersed in room temperature, clean water as you work.

Longer term, you'll need to rewash each film item in clean water, reapply wetting agent or appropriate process-specific final rinse (C-41 final rinse, for instance, contains antifungal and antibacterial agents that will be helpful in future longevity of contaminated film), and dry them before remounting or resleeving in archival sleeves.

If the items weren't stored wet, there is likely to be permanent, irreparable damage because the gelatin that makes up most of a photographic emulsion is also a very powerful adhesive (top quality furniture is assembled with glue made from gelatin).