What makes the site remarkable is not its scale but its age: a single beam of oak, analysed by dendrochronology, the science of dating wood by counting and comparing annual growth rings, returned a date of AD 787, plus or minus nine years. That places the mill firmly in the early Christian period, when Ireland's monastic communities and rural settlements were already running sophisticated grain-processing operations along even modest watercourses.

Excavations carried out in 1996, following an initial recording in 1995, focused on the wheel-house section of what had been a vertical-wheeled mill, the type where the wheel turns on a horizontal axle driven directly by the current, as opposed to the horizontal-wheeled or Norse-type mill more commonly associated with early Ireland. The surviving structural evidence centred on two soleplates, heavy timber beams that formed the basal frame of the wheel-house. The southern soleplate measured nearly three and three-quarter metres in length and still retained three mortises cut into its upper face, the rectangular sockets into which upright framing timbers would once have been fitted. The beam that yielded the dendrochronology date was the flume support, a timber designed to carry the channel directing water onto the wheel. By 1996, the northern soleplate, recorded the previous year while still in its original position, had already shifted. Several other structural timbers had been removed from the site entirely before archaeologists could examine them, and those that remained were found lying in or partly buried within the fill of the tailrace, the channel that carried water away from the wheel after it had done its work. The excavation was directed by Cleary and the findings were published in 1999.