I try to plant mine close to the low water level. That's worked for me, and none of the iris died.
Afterthought: On second thought, the iris I planted was fully grown, and not just the tubers. I would plant the iris tubers just like the instructions suggested.
Here's a 2 yo summer "normal" water level batch.
![[Linked Image from i.imgur.com]](https://i.imgur.com/AKYHtNV.jpeg)