It is water that has a high calcium content as it flows over limestone. This will not sustain life and therefore looks clear.
Aah so it is like a used up granite quarry like our own little Guilin which is a dug up quarry that naturally filled itself through rain and became a lake! Thanks for explaining Michael.
As the lime/ calcium rich water flows, it will naturally create levees or dikes impounding the water.
retireediary 
The water looks really clear and I am wondering if this was ever once a volcano – kind of like Crater Lake in USA?
It is water that has a high calcium content as it flows over limestone. This will not sustain life and therefore looks clear.
Aah so it is like a used up granite quarry like our own little Guilin which is a dug up quarry that naturally filled itself through rain and became a lake! Thanks for explaining Michael.
As the lime/ calcium rich water flows, it will naturally create levees or dikes impounding the water.