Llyn Traffwll is a 91 acre natural lake located, in Anglesey, Wales. Located midway between the villages of Rhosneigr and Valley it lies less than a kilometre south of the A55 North Wales Expressway. It is one of the largest natural lake on the island with Llyn Alaw and Llyn Cefni both being reservoirs.[1] Along with the surrounding smaller lakes it is a Site of Special Scientific Interest[2] and is adjacent to the Valley Wetlands RSPB site. Formerly (starting in 1866) the lake was used to supply water to Holyhead by the Holyhead Water Company,[3] and to aid water management a small dam was built which still exists.[4]
In late 2019 it was reported that a 300 acre Photovoltaic power station called Parc Solar Traffwl was planned to be constructed near the lake.[5] The Welsh language novel Madam Wen, Arwes yr Ogof, written by William David Owen, is set by the lake.[6]