On 2 November 1925, the dam at Llyn Eigiau was breached, the resulting flood waters overtopped and destroyed the dam at Coedty before sweeping down the valley, killing 16 people, 6 of them children, and destroying everything in its path. The loss of life would have been higher if a large part of Dolgarrog village had not been watching a cinema show at the Assembly Rooms. An inquest returned a verdict of accidental death on those killed by the disaster. The Eigiau dam was found to have inadequate foundations and poor quality concrete but no further proceedings were ever brought against any individuals or companies involved in the construction or maintenance of the dam.

This photograph depicts the aftermath of the disaster on the Conwy-Llanwrst Road.