In some ways I am reminded of land claims in arid regions of the American west. Ownership of relatively small areas around water sources provided control of vast areas with no water.
A lunar colony near a very localized water source would provide effective control of much of the lunar surface. Establish colonies at all of them, and the moon is ours.
They just discovered the the Mares are not the result of meteor collisions, but are internal flows from within the moon as it expanded.