At one end was a gatehouse. The tank outlets were connected with a power pump and a turbine that was used to open the gates of the outflow pipe. The  diameter outflow conduit extended  into the harbor from the northern end of Moon Island.
The description describes a system with a gatehouse, a power pump, a turbine, and an outflow pipe connected to a tank outlet. The outflow conduit extends into the harbor from the northern side of Moon Island.