Memories are not confined to those who experience them firsthand. Rather, they can be transmitted and repeated by subsequent generations as prosthetic and moral memories, not linked solely to specific geographic locations but extending to affect and inform contemporary political debates. This paper investigates how and why the 1965 flooding of the village of Capel Celyn in the Tryweryn valley, north Wales is remembered through textual analysis of Welsh literature and popular music. It also highlights the profound impact that struggles over resources can have on social, cultural and political landscapes. The flooding, arguably the most dramatic hydropolitical event in the history of the United Kingdom, created tension between the need to protect cultural identity on the one hand and on the other, the need to provide essential natural resources for industry and urban development. The memory of this event has been sustained in Wales in a number of ways. Visually, graffiti calling on the public to ‘remember Tryweryn’ has become a tangible symbol of Welsh nationalism, and a potent part of the Welsh landscape. In Welsh literature (poems and songs) the memory of Tryweryn has been expressed in terms of loss and shame and the defilement of nature. Politically, Tryweryn provided the context for the rise of Welsh nationalism and devolution and has become a regularly used symbol of a culture under threat. Crucially, the memories now influence and inform contemporary debates around precipitation, drought and any forced removal justified in the name of progress.