A brief account, covering the thirty or so years from the turn of the ninteenth century, when dramatic industrial development took place in the Conway valley of North Wales, in the the area of Dolgarrog. The introduction of hydro-electricity and aluminium production had been easy to accomplish, the damming of two upland lakes providing a reliable water source. On the 2nd of November 1925 the dam at Llyn Eigiau failed, destroying the tiny hamlet of Porth Llwyd with the loss of sixteen souls. Subsequent investigations and inquest led to parlimentary intervention and a new act regarding the design, construction and maintenance of dams.