It is generally the case that a landowner owns the land up to the water's edge along a non-navigable stream, but not the water itself. In other words, the owner owns the land, but not the water.
If the ownership of the land is held in a partnership with right of survivorship, then when one or more of the partners die, the remaining partners will automatically inherit the deceased partner's share of the property. If the remaining partners are not interested in buying the deceased partner's share, the court may order the sale of the deceased partner's share or the entire property.
In this case, the form of concurrent ownership that applies is a partnership with right of survivorship. This means that the partners own the property together and have the right to inherit each other's share upon death.