It was created by William Edward Oakeley (of Plas Tan-y-bwlch) as a 21st birthday present for his daughter Mair and as a water supply.

[1] Plas Tan y Bwlch is thought to be the first house in North Wales with electric lighting powered from its own hydro-electric station, which was commissioned in the 1890s.

It ceased to operate soon after 1928, when the public hydro-electric power station at Maentwrog began supplying the area.

[2] In June 2013 a new hydro-scheme, costing £420,000, and similarly tapping the water from Llyn Mair, was opened.

The position of the lake bordered with ancient oak woods and its tranquil appearance makes this a popular picnic site for visitors, and it is also a starting point for a number of local country walks.