What makes it worth attention is the clarity of its design: an L-shaped structure of post-and-wattle fence construction, with vertical posts and downstream braces arranged to exploit the rhythm of the tides rather than fight against them. The whole thing is oriented north to south, with a flood fence running about 24 metres and a longer shore fence extending to 105 metres, forming a mouth that faces upstream. This means it operated as an ebb weir, a type of trap that relies on the retreating tide to strand fish within the enclosure as the water drops. The principle is ancient and elegantly simple, requiring no nets, no boats, and no active pursuit.

The structure dates to the post-medieval period, placing it somewhere after the sixteenth century, though the technique itself has deep roots along Irish estuaries and tidal rivers. Fish weirs of this kind were commonplace features of the Shannon's working landscape, providing a reliable and relatively low-effort harvest of salmon, eels, and other species that moved with the tides. The site was documented by Aidan O'Sullivan in 2000 as part of a wider survey of intertidal archaeology along the estuary, and his 2001 publication records its dimensions and layout in detail. By that point, the structure was already a relic, its posts preserved by the anaerobic conditions of estuarine mud in the way that organic materials so rarely survive on dry land.