Istivin : City of Shadows.
Located at the base of the Promontory, the Effluvium is a huge drainage pool of porous stone that serves as a natural sump for the city. All of Istivin’s storm drains and sewer channels eventually empty into this collection basin, where the effluent slowly drains and evaporates. The result is a massive pool of foul-smelling, murky brown water. Nothing is known to live in this fetid soup, and hardly a ripple breaks its algae-covered surface. Most of the dozens of drains that empty into the Effluvium are only a few inches in diameter, but some open as wide as 4 feet across, and widen considerably deeper underground. These lead to sewer channels that run beneath Istivin and are always barred by thick iron grates to prevent the egress of sewer dwelling creatures or to keep out those who might use the tunnels for nefarious ends. These grates do not open, and sewer workers enter the drains from elsewhere in the city.