21 GCA § 20104
In Streams
View official PDF ↗An island, or accumulation of land, formed in a stream which is not navigable, belongs to the owner of the shore on that side where the island or accumulation is formed, or, if not formed on one side only, to the owners of the shore on the two sides, divided by an imaginary line drawn through the middle of the river.
Reconstructed from the Guam Code Annotated. For the authoritative version, see the official PDF.