The lowest water gate sump at Mile Five was a cavernous stone pit, forty arm-lengths square and thirty arm-lengths deep, designed to catch heavy gravel and river sand before the current reached the navigation channel. For thirty years, the Trade ring had claimed the sump was ‘irreparably cracked by earthquakes’ and couldn’t be cleared without risking the collapse of the entire riverbank.
Tomas and Nessa dropped the slimy iron rungs of the access shaft, their boots coated in dripping green pondweed. At the bottom of the pit, beneath four feet of sluggish water, lay the true secret of the delta’s thirty-year blockade.
“Look at the stacked timber frame timbers,” Nessa said, shining her bullseye lantern against the wall of the water chute. “These aren’t fallen logs or river debris. These are twelve-inch square white oak baulks, notched, pegged, and mortised together like the frame of a warehouse. Look at the adze marks on the face of the wood.”
Tomas knelt in the cold water, his scarred hand tracing the deep, clean cuts of a carpenter’s broad-axe. “They didn’t abandon the channel because it silted up. They built a dam inside the sump to ensure the silt backed up into the commercial reach.”
