Yet here, at the valley’s center, are the remains of this once-lavish city, watered by hidden aqueducts that run for miles from an underground spring.

The fresh water comes from an underground spring source.

The lake salinity increases towards the middle and northern parts due to underground spring waters.

It has been theorised that an underground spring feeds into the loch, maintaining a degree of freshness sufficient to offset its stagnation.

They set up a colony around a well with an underground spring.