Speak with Ashyo at the Pools of Purity and observe his ritual.
Have a look at that!
<Ashyo motions at the massive waterfall to the north.>
This must be the water supply for the whole valley!
Think about it, <name>: the pandaren use this water to grow vegetables the size of a house. Where could it come from? What is so special about it?
The elders among my people know a technique for speaking with the water and divining the future. Perhaps this same technique can provide insight into the water's source...
It's worth a shot at least!