A web search turned up:
"A Meandered river is one in which adjacent land owners own the land above the high water mark. Land below the high water mark is public, giving citizens the right to explore sandbars at leisure without worry of trespassing. Land above that level is usually private, and should not be utilized by people navigating streams except when portaging around an obstruction."
http://www.iowadnr.gov/portals/idnr/uploads/riverprograms/meanderedmap.pdf
I see a potential problem here. What is the "high water mark"? Would the water level of 2008 flood be used for the as the "high water mark" and thus the "public boundary"?
I think a rational view is if you are between the banks of the waterway, you are obeying the meandering stream guidelines. Ox bows (old river beds now disconnected) would be a situation I would try to avoid.