One other point which relates to a government decision to not survey a small island in a non-navigable river was made in Whittaker vs. McBride.
In that case the court said that if the United States Government fails to survey an island, and refuses to do so when attention is called to the matter, then no citizen can overrule that decision and proceed to homestead it under the guise that the island should have been surveyed.
In such a case, the rights of the riparian proprietors are to be preferred to the claims of the settler.