The Great Dam

The Great Dam is the lair of the Elder Weirkeeper: beating him opens the strongroom under the crest with a Hubstone, and he drops the Weirkeeper's Anchor, which a Confluence turns into a Mire Anchor. The dam closes a channel of ooze from shore to shore; the guardian sleeps on the crest, and inside the dam lie galleries, water chambers with sluices and hidden rooms. Piles hold, the ooze does not: keep high and breathe at the bubbles.

The sluice chambers open with water: each pit has two wheels — one lets some spans in, the other lets them out; the gate rises when the water stands at the lit mark. The lectern of the chamber names the wheels' measures. The dry bed under the dam lies in the thin air of the basin, but under a vault the air holds: breathe in the alcoves under the body of the dam. The weirkeepers built dams to measure and hold water; the first of them chose to hold the murk itself — and guards the wall to this day.