Its exact position has never been confirmed, which gives it an odd status among recorded monuments: documented, assigned a reference number, and yet geographically unresolved. A fish weir, in this context, would have been a structure of stone or timber built out into a river to channel fish into a trap or net, a commonplace piece of medieval infrastructure that was nonetheless central to the economic and dietary life of any religious or manorial settlement depending on it.

The weir enters the record through the 1654 to 1656 Civil Survey of Limerick, one of the great administrative surveys carried out under Cromwellian rule to catalogue Irish land ownership and its features. The entry for the parish of Abbeyowney describes a manor town with the privilege of a Court Leet and Court Baron, and notes that the River Muilcherne, the older name for the Mulkear, ran through the town and carried with it a stone bridge, a mill, and two fishing weirs. That passage, quoted in Robert Simington's 1938 edition of the survey, confirms that a pair of weirs existed here in the mid-seventeenth century. Whether they were already medieval survivals by that point, or more recent constructions, is not stated. The Ordnance Survey's six-inch map of 1840 shows a weir in the area, which may have been built on the site of, or incorporating the remains of, the earlier structure. The second weir was possibly located approximately 120 metres to the east, and cartographers have suggested that two islands visible on the 25-inch OS map of 1900 may mark the positions of both.

The site sits south of Owney Abbey, itself a medieval Augustinian foundation in the townland of Abington. For anyone visiting, the abbey ruins are the more legible presence; the weir, by contrast, requires patience and a degree of informed looking. The Mulkear is a working river in a farmed landscape, and physical traces of early water management can be easy to overlook or misread. Consulting the historic OS maps beforehand, particularly the 1840 six-inch and 1900 twenty-five-inch editions, both freely available through the OSi historical mapping viewer, gives the best chance of orientating yourself to where the weirs are thought to have stood.