Most visitors to Holycross come for the abbey itself, a restored Cistercian foundation on the north bank of the river in County Tipperary. Few pause to consider what is happening in the water just beyond its walls, where a set of low stone structures still regulate the flow of the Suir to the northeast, east, and southeast of the monastic complex.

The oldest documentary trace of these features comes from the Civil Survey of 1654 to 1656, a vast Cromwellian-era land assessment compiled to establish ownership and value across Ireland following the upheaval of the 1640s wars. That survey records 'fower Eele fishings' in the vicinity of Holycross Abbey, a phrase that points directly to the economic importance of managed eel fisheries here. A regulating weir is a low barrier built across a river to control water levels and direct fish into traps or channels, and eel weirs of this kind were once a standard feature of Irish monastic and manorial economies. The fact that three stone examples survive in close proximity, all visible on the Ordnance Survey six-inch map, is a measure of how durable these structures can be, and of how thoroughly the fishery was once organised around this stretch of the Suir.