GM396

Canal Aqueduct over the River Twrch, Ystalyfera  

08/11/1978  

Designated  

Powys  

Ystradgynlais  

277278  

209239  

Water Supply and Drainage  

Aqueduct  

Post Medieval/Modern  

The following provides a general description of the Scheduled Ancient Monument. The monument consists of the remains of an aqueduct, dating to the industrial period. This is the largest of the aqueducts which carried part of the original Swansea Canal, and it spans the Afon Twrch. The fast flowing nature of the river necessitated a weir to be built below the aqueduct to protect the piers and also to serve as a feeder. The total span of the aqueduct, which is built entirely of stone, is 21m. The monument is of national importance for its potential to enhance our knowledge of industrial engineering and technology. It retains significant archaeological potential, with a strong probability of the presence of associated archaeological features and deposits. The structure itself may be expected to contain archaeological information concerning chronology and building techniques, together with a strong probability of environmental evidence. Aqueducts may be part of a larger cluster of monuments and their importance can further enhanced by their group value. The scheduled area comprises the remains described and areas around them within which related evidence may be expected to survive.