An aqueduct is a construction that controls the flow of water.
Bajor was famous for its aqueducts. Unfortunately, they were damaged by the Cardassians during the Occupation. In 2369, the Enterprise-D arrived at Deep Space 9 to assist in their reconstruction. (TNG: "Birthright, Part I")
A speaker at the Starfleet Admirals' Banquet was to give a talk on Bajoran aqueducts in 2370. (TNG: "Phantasms")
Deck ten of the Enterprise-D was transformed into a aqueduct by the D'Arsay device. (TNG: "Masks")