River dwelling tribes that number less than a thousand strong worry that when the diversion is through, the river will no longer be navigable and may see some Xingu tributaries dry out for good, impacting their way of life and a key route to the city of Altamira nearby.

FORBES: No End To Brazil's 'Pandora Dam' Drama

So, too, would one operating outside of public navigable airspace, though defining exactly where that lies for UAVs can be complex.

FORBES: Will "Drones" Outflank the Fourth Amendment?