And also hydrogen. By placing a small nuclear reactor on the moon, we could produce oxygen for breathing and hydrogen for fuel by breaking down the water. Perfect for a mars mission, with a lunar launch pad with a fraction of earth's gravity to escape.
Since each pound of material costs $10,000 to rocket out of earth's gravitational pull, the discovery of large amounts of water resource on the moon is worth trillions of dollars, if not quadrillions of dollars, as a launch point to other planets.
I dunno man. I saw Space 1999. Not a pretty picture.
;)
A nuclear reactor is not needed. Photovoltaic cells that can be manufactured on the surface from available materials will be enough to produce oxygen through electolysis from metal oxides in the regolith. You will not need hydrogen for fuel because of the abundant aluminum oxide, which can be used as rocket fuel. Also, you can use magnetic accelerators to acheive escape velocity, given the lack of an atmosphere.