[3] The Cephisus, a post-glacial river, never had sufficient flow deriving from drainage to establish a clear channel to the Gulf of Euboea.

Today it has been totally drained for agriculture, revealing katabothra, or caves in the karst topography leading down to Lake Yliki as well as Bronze-Age works to stem the flow.

The underground paths to Lake Yliki are now open, causing its level to rise sufficiently to drown all traces of Bronze-age settlement in its valley.

Waters were being tapped from rivers as far away as western Greece through deep tunnels, which take advantage of the difference in altitude.

Pausanias records a Theban tradition that the river Cephissus formerly flowed under a mountain and entered the sea until Heracles blocked the passage and diverted the water into the Orchomenian plain.