Llynoedd Ieuan are located approximately three miles east of Ponterwyd. There are three lakes there - the largest of which measured roughly 540 metres north to south by 150 metres east to west. The smallest of the lakes measures 280 metres north to south by 83 metres east to west. The smallest lake is also the easternmost. Known as Llyn Newydd, it is the 'latest dating of the three reservoirs at Llynnoedd Ieuan.' According to Dyfed Archaeological Trust, the lakes are dammed and associated with supplying water to the mines at Nantycreiau (NPRN 33891) or Castell (NPRN 33822). The lakes or reservoirs are recorded on the first edition of the 6inch OS maps, published in 1891.
Sources: modern and historic OS maps; Dyfed Archaeological Trust database, reference numbers: DAT35928 to DAT35933
M. Ryder, RCAHMW, 4th April 2019