The Mahnkelon Waterworks is a large impoundment dam system located in The Floodplain of Mahnkelon. The dam straddles the river Elon. It is used to supply the arid areas of Kourna with fresh water through an artificial irrigation system of many miles of pipework.
The Rilohn Refuge (mission) leads you to and through the Mahnkelon Waterworks. After having done this mission, the Waterworks are explorable. Since there are no Droughts then anymore, it is easier to explore it afterwards than during the mission.