An eel weir was a fixed structure, typically a low barrier or arrangement of wicker traps set into a river, designed to intercept migrating eels as they moved downstream. Today, the site sits on dry land, the river having long since retreated, and nothing at all remains above ground to indicate what was once there.

The disappearance of the weir is largely a consequence of engineering rather than time. In the mid-nineteenth century, the Office of Public Works carried out drainage works along the Inny, narrowing the channel considerably as part of a broader programme of river improvement that reshaped watercourses across the midlands. The effect at Ballycorkey was to strand the old weir location entirely, leaving it disconnected from the water it once relied upon. The 1837 map places the weir immediately beside the site of Ballycorkey Castle, a proximity that hints at the economic relationship between a fortified residence and the productive river management that would have supplied it. Ballycorkey Bridge stands about 140 metres to the northeast, still in use and still marking the crossing that gave the area its orientation long before the drainage works altered the landscape.