What you have described to date is not all that clear......
Do you know the construction of the bore hole?
Is it open at the bottom? if not does it have a stainless screen or slotted casing construction?
When you hear the rushing water is it when there is no pumping in progress?
What part of the world are you?
At what level does the water sit in the bore hole?
Here in my part of the world one can drill into a limestone cave (on the near coastal strip) which may have an air space in it, bit scary as a driller to see your circulating mud's disappear at a fast rate of knots, then not being able to regain circulation. That said in those situations it does provide quality water for the land owner.
Generally speaking underground rivers don't exist, having said that in some regions there are volcanic pipelines, you may have jagged one of those. Water diviners often speak of underground streams, once again a misnomer, generally refers to an area where the sands are coarser than those adjacent, such that the greatest amount of available water can be extracted from that zone. Of course like all things there are exceptions.
Apart from a good (assumption) supply of water the only viable option I see for what you describe is a down hole heat exchanger for cooling, if you need cooling that is.
Allan
