Ancient Monuments

History on the Ground

This site is entirely user-supported. See how you can help.

Former Dam of Cwmcarn Canal Reservoir

A Scheduled Monument in Abercarn, Caerphilly (Caerffili)

More Photos »
Approximate Location Map
Large Map »

If Google Street View is available, the image is from the best available vantage point looking, if possible, towards the location of the monument. Where it is not available, the satellite view is shown instead.


Latitude: 51.6352 / 51°38'6"N

Longitude: -3.1249 / 3°7'29"W

OS Eastings: 322243

OS Northings: 193536

OS Grid: ST222935

Mapcode National: GBR J0.82PX

Mapcode Global: VH6DN.S5B8

Entry Name: Former Dam of Cwmcarn Canal Reservoir

Scheduled Date: 19 December 1996

Source: Cadw

Source ID: 3493

Cadw Legacy ID: MM259

Schedule Class: Water Supply and Drainage

Category: Dam

Period: Post Medieval/Modern

County: Caerphilly (Caerffili)

Community: Abercarn

Built-Up Area: Abercarn

Traditional County: Monmouthshire


The monument consists of a dam, a barrier of concrete or earth built across a river to create a reservoir of water for industrial usage, dating to the 18th century. The Cwmcarn canal reservoir was built in around 1792 to provide water for the Monmouthshire Canal's Crumlin Arm. The earth dam was 128m long and 10.7m high. The dam burst catastrophically on 14 July 1875, resulting in devastation of the valley below and the loss of 13 lives.

The monument is of national importance for its potential to enhance our knowledge of 18th canal dam with well-preserved remains visible in section, and as the site of a major engineering disaster which informed future practice. 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. A dam 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.

Source: Cadw

Other nearby scheduled monuments is an independent online resource and is not associated with any government department. All government data published here is used under licence. Please do not contact for any queries related to any individual ancient or schedued monument, planning permission related to scheduled monuments or the scheduling process itself. is a Good Stuff website.