Sorry,
Maybe its the top photo quality, but I see a lot of faint bluish areas that may very well be reflective indication of very slight topography features.. I thus see many drainage swales/paths there on otherwise "relatively" flat landscape (2d issues?) in many places.
I see this effect on the immediate north flank of the bunker and then in the 2nd pic I note no trees in the same shaped area.. now going up from the upper right of the pond.. see the tree shadows?
What is perhaps more indicative of potential drainage problems is the access road cutting from center to upper right to the water tank. Looks like this road path in first pic turned into a tree canopy lane in second pic and in 3rd pic its now open.. perhaps to provide easement for the underground water supply piping?
I can imagine the water tank sidewalls are only partially above ground, that is fairly common construction/design for those type things. Also, very likely the pump station lines/pumps are routinely purged to ground before and after maintenance.
Simple point from above is that the past marshy area - now pond is right in the physical center of this course & small road bounded drainage basin! Very rational why it could be intermitttently wet!
After finally seeing this aerial, why are y'all in such a snit about the stupid pond? Looks like in the past one could freely hit into the bunker in two and easily get out of there in three and still make par.. can't do that with the water there!
What a waste of discussion group mind power. Maybe the "GCA.COM Restorationeers" are full of shit too!