Serpent's Skull in Eberron
3 long rectangular pools of water near the lake. After spending most of the day here the explorers determined that this was a water treatment facility that processed the waste water of the city before sending it down stream. When fully operational, the facility could also be used to manage the outflow of the lake to maintain a constant water level.
Discovered on Zor, the 19th of Vult 1102YK