Canal Aqueduct over Afon Twrch, including weir

The Canal Aqueduct over Afon Twrch, which includes a weir, is a significant structure with a span of 21 meters and a width of 9 meters. It is built from squared rubble stone and features three broad low arches, each measuring 7 meters in span and 2.7 meters in height, with the arch soffits and voussoirs rendered over. A string course runs beneath the deep walling on the canal sides, topped with later 19th-century rock-faced stone coping.

On the downstream side, there are two small triangular cutwaters that rise as triangular piers with two offsets. The upstream side has been reinforced in the 19th century with two large stepped rounded stone piers that cover earlier cutwaters. This side also features a concrete spillway in the center and parapet top courses made of red brick. Beneath the eastern abutment, there is a circular tunnel for the tailrace of a former mill, with stone voussoirs at the entries.

The canal channel is 3.35 meters wide and 1.25 meters deep, with a tow-path on the southern side. The canal bed has been concreted during restoration, and the sides are made of rubble stone, likely rebuilt in 1993-1994. Additionally, there is a cast-iron mounting for a small emptying sluice on the northern side, and the broad concrete overflow in the center has slots for sluice gates on each side.