The structure is documented, named, and even partially mapped, yet its precise location has never been identified. That quiet gap between the historical record and the physical landscape is what makes the Eel weir of Callaghbeolane an oddly compelling subject, less a monument than a ghost that left paperwork behind.

The weir appears in the 1654 to 1656 Civil Survey of County Limerick, one of the great administrative surveys carried out in the aftermath of the Cromwellian conquest, which catalogued land ownership across Ireland in extraordinary detail. A fish weir, in this context, would have been a fixed structure of timber, stone, or wicker built across a river channel to trap fish, particularly eels, as they moved with the current. The Callaghbeolane weir was apparently substantial enough to be divided between two sets of owners. The southern half belonged to Sir Nicholas Comyn, Sir Geoffrey Gallway, and George Creagh fiz Richard of Limerick, while the northern half was held by the Earl of Thomond. The survey notes that the weir sat close to what is now Athlunkard Bridge, with the River Shannon to the east and the lands of Longford, in County Clare, as a further boundary marker. Beyond the written survey, the weir also appears on the Down Survey map of St Patrick's Parish, a 17th-century cartographic project associated with William Petty, which is held at the National Library of Ireland as MS 718. The map shows a structure crossing the Shannon at Corbally, though translating that sketch into a ground-level location has so far proved impossible.

Visitors to the area will find no physical trace of the weir today. The stretch of the Shannon near Athlunkard Bridge is accessible on foot via the riverside paths at Corbally, and the bridge itself offers a reasonable vantage point over the water. What remains is really an exercise in reading the landscape against the documentary record: standing at the riverbank and understanding that the divisions of ownership, the Earl of Thomond on one side, Limerick merchants on the other, once played out across a working structure in the current below. The Down Survey map, the starting point for any serious investigation, can be consulted through the National Library of Ireland's online catalogue.