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Cof Cymru: National Historic Assets of Wales · Wales

Former Dam of Cwmcarn Canal Reservoir

Crosskeys, Caerphilly, Wales

The record

Designation
Scheduled monument
Site type
Dam
Period
Post Medieval/Modern
Date of designation
19 December 1996
Community
Crosskeys
Unitary authority
Caerphilly
Country
Wales
Coordinates (centre of the scheduled area)
51.63516, -3.12492
SAM number
MM259
Cadw record number
3493

Slide toward Today to fade the historical sheet and see the modern map underneath.

David Rumsey Map Collection, Stanford Libraries

Shown on 5 historical map sheets, the earliest the 1588 "Ortelius, Abraham: Theatro De La Tierra Universal. 0" (Bayerische Staatsbibliothek, Munich).

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This record in Cadw's own full report ↗

Cadw's description

The following provides a general description of the Scheduled Monument.

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.

Nearby in the register

Other entries of the same register within about three miles of this one, by straight line.

Designated Historic Asset GIS Data, The Welsh Historic Environment Service (Cadw), 2026-09-07, licensed under the Open Government Licence http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/ Cadw, the Welsh Historic Environment Service · Open Government Licence v3.0
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