Cwm Dyli hydro-power station is located in the Snowdonia National Park on the southern flank of the Snowdon range. The station was built in 1905 to supply electric power for the then prosperous slate industry. It is Britian's oldest power station, having been in almost continuous operation since it was first commissioned in 1906. In 1987, the station was shut down to allow for a complete refurbishment and uprating of its output from 5 MW to 10 MW. This article gives a short history of the station and describes briefly the ‘new’ station