Lands within this State which are returned by the United States as swamp and overflowed lands, and shown as such on approved township plats, shall, as soon as patents are issued therefor by this State, be held to be of the character so returned. Nothing in this section shall be construed to affect the rights of any homestead or preemption settler claiming under the laws of the United States, nor to prejudice the rights of any settler located upon such lands to perfect title to the lands if permitted under existing laws.