The water has also been kept at a proper level by lowering the river bar at Galway, and constructing a regulating weir there. At some time the navigation channel in the narrow rocky portions of the lake was deepened, the rocks raised; and by buoying and marking with pillars, rocks, and irons, the steamer’s track, it has been rendered navigable from Galway to Cong, and also to Oughterard, and to within a couple of miles of Maam hotel.
All the marks on the eastern side of our upward course from Galway are coloured white, and those on the western side dark.
It will help to give confidence to our Lady friends, who can almost touch some of these marks, triangles, and gridirons, from the Eglinton, to know that all these rocks were lifted by the present captain of the vessel, who was formerly employed here as a diver.
Sir William R Wilde MD Lough Corrib, its shores and islands: with notices of Lough Mask McGlashan & Gill, Dublin; Longmans, Green, and Co, London 1867
Irish waterways history 