Malltraeth Cob

Malltraeth Pool from the embankment with the mountains of the Nantlle Ridge in the background

Date

3 July 2015

Location

Malltraeth, Anglesey

Information

Malltraeth Cob is a 1.6 km long sea embankment forming part of the flood-defence system of Malltraeth Marsh. The latter is a flatland valley 8 km long and 3 km wide lying on either side of the Afon Cefni to the south of Llangefni on Anglesey. The river Cefni itself is 17 km long, starts at Llyn Cefni and empties into the Irish Sea at Malltraeth Sands.

With existing defences having been breached by storms in the 1790s, extensive repair work overseen by Scottish civil engineers Thomas Telford (1757-1834) and John Rennie (1761-1821) was undertaken in the early 19th century, with the current cob being completed in 1812. The river was also canalised and embanked and the draining of the marsh enabled agricultural use of the land as well as the development of the A5 road and the coal mine at Pentre Berw. The Chester and Holyhead Railway was also lain across the reclaimed land, with the viaduct over the river being completed in 1848.

Malltraeth Marsh has been designated a Site of Special Scientific Interest (SSSI) and it includes an RSPB reserve.

Malltraeth Sands

Looking towards Malltraeth village. The village grew up around the maintenance base and workers’ housing created during the early 19th-century flood-defence development.

Malltraeth Sands with the edge of Newborough Forest on the left

One man and his dog

Former tidal door. This was removed from its original location in 2010 and put on display. Telford developed self-acting sluice doors which closed at high tide to prevent flooding and opened again at low tide to allow water in the sluices to flow out.

Malltraeth Cob. The path along the top of the embankment forms part of the Lon Las Cefni cycle route from Newborough to Llyn Cefni.

Malltraeth Cob. The path along the top of the embankment is part of the Anglesey Coastal Path and also forms part of the Lon Las Cefni cycle route from Newborough to Llyn Cefni.

Afon Cefni with the railway viaduct in the distance. The viaduct carrying the Chester and Holyhead Railway (now the North Wales Coast Railway Line) over the Afon Cefni was completed in 1848 and was strengthened in 1966.

Flood relief channel, with the main river lying behind the embankment on the left. The river was canalised and embanked to prevent flooding and is itself tidal. The flow of the side relief channels into which water from the flatland drains is, however, controlled by sluice gates.