It has two names in Irish tradition, Cor Uí Chriotháin, meaning O'Crehan's Weir, and more recently Davin's Weir, after the family who held it as lessees into the twentieth century. On the Waterford bank, roughly a hundred metres downstream, a small circular tower of apparent nineteenth-century date was built specifically to watch over it, keeping the weir and whatever was caught there under observation. The Ordnance Survey recorded both structures together, naming the crossing Coolnamuck Salmon Weir, and on the Tipperary side there was once a small landing place called Cois Cortha, or Weirside, where the catch could be brought ashore.

The weir's origins stretch back considerably further than its modern names suggest. A survey of the Manor of Carrickmagriffin, conducted in 1415, records 'vj gurgites salmonum' in the manorial waters of the Suir, a Latin phrase interpreted as six salmon weirs, and local tradition holds that this is one of that number. A fish weir of this kind is a fixed structure built across a river channel to trap fish, typically using the current to funnel salmon or other species into a confined space where they can be lifted out. The weir continued working for several centuries after that 1415 survey, right up to 1922, when it came to an abrupt and somewhat dramatic end. Attempts to blow it up in April and May of that year failed, and the lessee Davin eventually dismantled it himself. Whatever the precise circumstances behind those demolition efforts, the structure proved more durable than intended; the Waterford side of the weir remains visible in the river to this day.