It is easy to overlook such structures entirely, mistaking them for random debris or the remnants of some forgotten jetty, but their geometry tells a more deliberate story. The weir's two arms, one running 32 metres and the other stretching to 125 metres, were laid out with a specific hydraulic logic that exploited the estuary's rhythms rather than fighting them.

The structure is classified as an ebb weir, meaning it was designed to trap fish as the tide retreated. The mouth of the weir faces upstream, so fish moving with the flood tide would swim freely into the enclosure, then find themselves stranded or funnelled into a confined space as the water pulled back seaward. This was a common and highly effective approach to estuarine fishing in Ireland during the post-medieval period, requiring no boats, no nets, and no great expenditure beyond the labour of driving posts into tidal sediment. The technique is ancient in principle, though the particular form recorded here, with its northeast-southwest orientation and substantial shore fence, belongs to the post-medieval phase of the estuary's working life.