Ric's link above led me to more of the Historical Documents. It seems that on some visits to Niku, water was found, on others (like when the colonists came) none was found. It makes me think of the possibility that if Amelia landed there, she and Fred may not have been able to find any water at all, even digging down.
Then, reading "Bevington's Journal" from Oct. 14, 1937, he writes of "signs of previous habitation". Also, in Maude's account (these are all listed in Historical Documents) he speaks of finding J.W. Jones working in 1937 on Hull and Sydney with a few labourers from Tokelau. It seems like Maude didn't know Jones was there until he came upon him. What I'm getting at is the possibility of undocumented and unauthorized operators in those days visiting the islands including Niku for whatever they could find to make a buck? Or a pound? Like J. W. Jones stopping in at Niku even when the island was supposedly uninhabited? Would they have left signs of habitation as the flyers from the Colorado saw? Maybe this has all been gone over long ago, I'm new here.