The Tryweryn flooding or Tryweryn drowning (Welsh: Boddi Tryweryn), refers to the flooding of the rural community of Capel Celyn to the north west of Bala in Gwynedd, Wales, in the Afon Tryweryn valley. The village and other parts of the valley were flooded in 1965 to create a reservoir, Llyn Celyn, in order to supply Liverpool and Wirral with water for industry.