A watermill once operating near Ballyorgan in County Limerick has left no trace on the ground, no stone, no millrace, no collapsed wall. Its existence is known entirely because a cartographer recorded it, along with a companion mill on the opposite bank, sometime around the year 1600.

The source is a map of Kilmallock town held in Trinity College Dublin as manuscript TCD MS 1209/62, dating to approximately 1600. On it, two watermills are shown facing one another across the River Loobagh, positioned to the north-east of the walled town of Kilmallock. Kilmallock was at that period one of the most significant urban centres in Munster, a walled medieval town with a strong Anglo-Norman character, and the presence of paired mills on the river beside it speaks to the scale of grain processing that would have supplied such a settlement. A watermill of this era would typically have been a horizontal or vertical wheel mill using diverted river flow to power millstones, an everyday piece of infrastructure that was nonetheless central to the food economy of any town. That two mills operated in close proximity, facing one another across the same watercourse, suggests a well-established and probably busy milling site. The site reference compiled by Caimin O'Brien and uploaded to the national record in September 2019 notes plainly that no surface remains are visible today.

The River Loobagh still runs north-east of Kilmallock, and the town itself retains substantial medieval remains including its walls, a collegiate church, and a Dominican friary, all of which are accessible and well worth examining on any visit to the area. The mill site, however, offers nothing to see at ground level. Its value is archival rather than physical, a reminder that the landscape around a medieval town was as industrially organised as the town itself, and that much of that organisation has simply vanished. For anyone with an interest in historical cartography or in what the 1600 map of Kilmallock actually shows, the Trinity College Dublin manuscript is the place to look.