SDCL § 43-17-5: Accretions to bank of river or stream belong to owner of bank subject to existing right-of-way.

Where from natural causes, land forms by imperceptible degrees upon the bank of a river or stream, navigable or not navigable, either by accumulation of material or by the recession of the stream, such land belongs to the owner of the bank, subject to any existing right-of-way over the bank.