If the court rules the land is navigable waters the Sorenson heirs should file with the county to have the land taken off their deed and reduce their tax burden.
If it is a river and the family has no right to control the use of it, the land should not be taxed.
This has been an issue in Ohio for some time. Owners of lake front property are taxed for land that has been eroded by lake Erie and is now covered by the lake. Yet the counties still assess taxes on that property that state law says is now the property of the state.
With wetlands and navigable river issues and the USACE involved, you can bet it will be a major mess.