Somewhere beneath or within the landscape here lies the buried evidence of a horizontal-wheeled water mill, a type of early milling technology in which a wheel set flat in the water, rather than upright, was turned directly by the force of a channelled stream. Simple in construction and requiring no complex gearing, these mills were widespread in early medieval Ireland and represent one of the more quietly significant technological presences in the Irish countryside. At Knockrour, no surface trace of this one remains.

What is known comes from a single discovery made in 1927 by J.P. O'Conlon. He found the remains of a lidded penstock and a plank-lined headrace, the two key structural elements of a horizontal mill's water-management system. The penstock is the enclosed channel that accelerates water before it strikes the wheel; the headrace is the broader channel that feeds water towards it. That both were lined or lidded with timber suggests reasonable preservation at the time of their uncovering, though the record of the find, cited by the mill historian Colin Rynne in 1988, is brief. Whether the timbers were examined, dated, or removed is not recorded in what survives of the account.