Lake Mill was the first of the Cwmorthin mechanised slate mills, probably being built in the early 1860s by the Cwmorthin Slate Co. In 1900 it contained 21 saws and dressing machines, and was driven by a 28HP steam engine; it may at first have had a waterwheel. It was dismantled after 1902, and a tramway built in the 1920s ran diagonally through the site. The remains of the footing show that the mill was 97 metres long by 13 metres wide.
W J Crompton, RCAHMW, 4 December 2008.