Llyn Celyn () is a reservoir constructed between 1960 and 1965 including the highly controversial Tryweryn flooding in the valley of the River Tryweryn in Gwynedd, Wales. This included the forcible removal of the Capel Celyn village residents despite protest and opposition of Welsh MPs. It measures roughly long by wide, and has a maximum depth of . It has the capacity to hold of water. It was originally to be named Llyn Tryweryn Mawr (meaning "great Tryweryn lake"), but in September 1964 Liverpool Corporation agreed to the name change following a letter from the Tryweryn Defence Committee. Construction and opposition Construction of the reservoir for Liverpool Corporation Waterworks involved flooding the village of Capel Celyn and adjacent farmland, a deeply controversial move. Much of the opposition was brought about because the village was a stronghold of Welsh culture and the Welsh language, whilst the reservoir was being built to supply water to Liverpool and parts of the Wirral peninsula, rather than Wales. Liverpool Corporation's Tryweryn Reservoir Bill was presented in Parliament as a private bill in January 1957; by obtaining authority through an Act of Parliament, Liverpool City Council avoided having to gain consent from the Welsh planning authorities. The legislation enabling the development was ultimately passed, despite mass protests in Wales, marches through Liverpool by Capel Celyn residents and their supporters, and the opposition of 35 out of 36 Welsh Members of Parliament, with the 36th (David Llywelyn, Conservative MP for Cardiff North) abstaining. This led to an increase in support for the Welsh nationalist party, Plaid Cymru, in the late 1950s and gave fresh impetus to Welsh devolution. The official opening was held on 28 October 1965. Representatives came from Liverpool City Council, and invitations were sent to all those with family links to the valley. In view of the anticipated protest, there was a strong police presence. The ceremony lasted less than three minutes, as protesters had cut the microphone wires, and the chants of the hundreds of protesters made the speeches inaudible. In October 2005, Liverpool City Council issued a public apology, which read: Operation of reservoir The reservoir was built to help maintain the flow in the River Dee, so that drinking water could be abstracted further downstream as part of the Dee Regulation Scheme. These abstractions include one at Huntington water treatment works in Chester, operated by United Utilities, which supplies water to