Description

The monument consists of the remains of a water channel, dating to the Roman period.

It is believed to have been constructed in conjunction with the Roman exploitation of the gold mines at Dolaucothi, probably in the later 1st and early 2nd centuries AD. It runs for a total of about 10.7 kilometres from its source beside a waterfall in the gorge at Pwll Uffern Cothi, down the southern flank of the Cothi valley to the gold mines near the village of Pumsaint, where it fed a number of tanks and was used for various purposes. It was very skilfully designed with a fall of about 1 in 750 throughout, partly as a result of the need to carry it over the saddle beside Allt Dinbeth, which limited the gradient above this point. The channel hugs the contour of the hillside for most of its route, running some way up side valleys at Cwm Dâr, Pen-twyn and Llwynceiliog as a result. Some parts of its course were probably carried on or supported by timber structures which do not survive. While occasional stretches of rock-cut inner face are visible, nowhere is it possible to calculate the original width and depth of the channel. This is the longest and best-preserved leat from the Roman period in Wales (one of only a handful known in Britain) and an important demonstration of the sophistication of water management by Roman engineers.

Parts of the course have been lost over the years, so that only the better surviving portions have been deemed suitable for scheduling. These stretches were originally designated by separate letters, but subsequent adjustments have now combined some of these. The scheduled portions are as follows: A (SN 71801 46610 to SN 72024 46323); B&C (SN 71633 45924 to SN 71046 45525); D (SN 70987 45426 to SN 70683 45009); E (SN 70643 44945 to SN 70542 44826); F (SN 70387 44663 to SN 70266 44608); G (SN 70123 43906 to SN 69943 43860); H (SN 69818 43912 to SN 69472 43856); J (SN 69628 43391 to SN 68785 43065); K (SN 68737 42951 to SN68216 42700); L (SN 68045 42686 to SN 67916 42614); M (SN 67633 41659 to SN 67227 41112); N (SN 66931 40717 to SN 66705 40011)

The monument is of national importance for its potential to enhance our knowledge of Roman structural engineering and mining technology. The scheduled sections of the monument are generally well-preserved and an important relic both of their Roman construction and of the subsequent development of the local landscape, in which its line often became a key feature. It retains significant archaeological potential, with a strong probability of the presence of both structural evidence and intact associated deposits.

The scheduled area comprises the remains described and areas around them within which related evidence may be expected to survive.

Source: Cadw