This is a pen stock mill, where the water is dropped vertically down a shaft, before being forced through a small pipe with great force to spin a turbine that drove millstones above. It is not known when such mills were first developed.
This one depends on the reservoir for its water supply, so might have been used from the Nabataean period onwards. Pen stock mills are typically used in the Islamic periods for grinding grain, although this example might have been used for crushing ore.
Location of the water-powered mill