There appears to be a popular misconception that Llyn Trawsfynydd Reservoir was built to provide cooling water for the Nuclear Power Station. (This is stated on many web sites) What insight someone must have had if this was true, because the reservoir appears on the "Popular 1940's OS map on this Geograph site!!!
The dam was built (I believe ) by The North Wales Power Co Ltd in the early 1920's to provide water for the Maentwrog Hyro Electric Station. (I think my Grandfather attended the opening ceromeny in 1928) Does anyone know any history of this project, I think it is still in operation having been modernised , and produces 30mW of electricity.