Submerged valley
Baptist Chapel
The Baptist Chapel, now submerged beneath Caban Coch Reservoir. Map Ref SN91070 63929
Read the storyLost beneath the reservoirs • Elan Valley
Elan Valley historical archiveThe Submerged Valley
Beneath the waters lie the remains of homes, churches, work sites and an entire landscape. Discover the stories of the Elan Valley before the reservoirs.
Discover the placesBefore the reservoirs
Lives and places beneath the water
Explore a collection of historic sites submerged, lost or altered by reservoir construction and proposals. These photographs and records preserve the memory of buildings that once stood along the valley floor.
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Map of lost places
Explore historic sites using OS grid references. Select a marker for its details, or click a numbered marker to open links to every nearby place.
25 mapped locations from the database. See the alphabetical OS grid-reference list.
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Places beneath the water
All places are listed alphabetically. Open a place for its history and photographs.
Houses & farms · Claerwen Valley
Bryniago
Former home of John and Elizabeth Price, abandoned for a proposed dam that was never built. Map Ref SN8814 6279.
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Houses & farms
Cwm Coel House
Site of Cwm Coel House, not much to see. Normally under Garreg Ddu. It was a farmhouse with a tall chimney. Map Ref SN9062 6413
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Submerged valley
Cwm Elan House
The estate of Cwm Elan, containing the Elan Valley mansion, was purchased in 1792 by Thomas Grove. It was described then as “10,000 worthless…
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Submerged valley
Cwm Elan Lodge
Cwm Elan Lodge was located in Cwm Elan and is now submerged beneath Garreg Ddu Reservoir. Photos courtesy of Mary Connelly Map Ref SN91071 64315
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Houses & farms
Dol-Faenog House
Dol-Faenog House, now under Pen y Garreg Reservoir. Map Ref SN91580 66820
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Houses & farms
Dol-folau
Dol-folau before the valley was flooded, together with later photographs of the remains when water levels were low. Map Ref SN91331 65648
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Houses & farms · Claerwen Reservoir
Esgair y Gader Cottage
Red-brick cottage normally hidden beneath Claerwen Reservoir, whose remains were exposed at low water in 2026. Map Ref SN 8636 6492.
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Submerged valley
Garreg Ddu
Remains of Garreg Ddu before the dams and what still remains today. Map Ref SN91032 63861
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Rural structures
Garreg Ddu Navvy Huts
Site of Garreg Ddu Navvy Huts. Normally submerged under Caban Coch Reservoir. Map Ref SN
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Houses & farms
Gro Bach
Remains of Gro Bach under Caban Coch Reservoir. Map Ref SN92060 63560
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Houses & farms
Gro Isfa
Remains of Gro Isfa under Caban Coch Reservoir. Map Ref SN92080 63640
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Houses & farms
Gro Uchaf
Gro Uchaf before the valley was flooded. The barn on the right was moved to Clearwen Farm. Map Ref SN91764 63068
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Industrial heritage
Gro Walls
Walls, footpaths and a bridge normally submerged under Caban Coch Reservoir.
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Houses & farms
Lluest Tor-Clawdd House
Small hill farm now submerged by Craig Goch Reservoir. Map Ref SN89560 70400
Read the storyMasons Yard
Industrial heritage
Masons Yard
Masons Yard entry requires research; its existing detail page currently duplicates the Nant Gwyllt Cottages content.
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Submerged valley
Nant Gwyllt Church
Nant Gwyllt Church, submerged under Caban Coch Reservoir. It was a small church. Map Ref SN91809 63939
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Submerged valley
Nant Gwyllt Cottages
Possibly the remains of Nant-gwyllt Cottages, photographed on 10/08/2022. Unfortunately there are no known earlier photographs here from before…
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Submerged valley
Nantgwyllt House
Nantgwyllt House was demolished and now lies under Caban Coch Reservoir. The original house of the Powell family was of grey stone, long and…
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Industrial heritage
Nanty Postdy Bridge
Nanty Postdy Bridge, also known as Horse Bridge. Remains of an old bridge just downstream of Dolymynach Dam, normally submerged under Caban…
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Industrial heritage
Old Construction Shed
Old construction shed near Craig Goch Dam, with the old railway lines still visible. Map Ref SN89220 68716
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Industrial heritage
Old Foot Bridge
Old footbridge under Craig Goch Reservoir, not far from the Hirnant. It is called Pontbren Lloc-ddu and is locally known as Pwll Coon. Photo…
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Houses & farms
Pant y Blodau
Pant y Blodau was a small house, now submerged beneath Caban Coch Reservoir. Map Ref SN91734 62678
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Industrial heritage
Stone Dressing Yard
The Stone Dressing Yard before the valley was flooded. Map Ref SN913 646
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Houses & farms
Ty Nant, Elan Valley
Remains of Ty Nant House under Pen y Garreg Reservoir. Map Ref SN9019 6727
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Ordnance Survey
OS map references (A–Z)
Search by place, bridge, feature or grid reference. Use “Show on map” for entries with a complete reference.
Showing all 30 entries.
| Place / feature | OS grid reference | Notes | Links |
|---|---|---|---|
| Baptist Chapel | SN91070 63929 |
||
| Bryniago | SN8814 6279 |
Not submerged; proposed dam site | |
| Craig Goch construction shed | SN89220 68716 |
||
| Cwm Coel House | SN9062 6413 |
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| Cwm Elan House | SN9101 6463 |
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| Cwm Elan Lodge | SN91071 64315 |
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| Dol-faenog House | SN91580 66820 |
||
| Dol-folau | SN91331 65648 |
||
| Esgair y Gader Cottage | SN8636 6492 |
Claerwen Reservoir | |
| Garreg Ddu | SN91032 63861 |
||
| Garreg Ddu Navvy Huts | Needs checking | Grid reference incomplete in source | View page |
| Gro Bach | SN92060 63560 |
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| Gro Bridge | Needs checking | No reference recorded | View page |
| Gro Footpath | SN91869 63312 |
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| Gro Isfa | SN92080 63640 |
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| Gro Uchaf | SN91764 63068 |
||
| Gro Walls | SN91813 63181 |
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| Lluest Tor-Clawdd House | SN89560 70400 |
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| Masons Yard | Needs checking | Page currently duplicates Nant Gwyllt Cottages; needs verification | View page |
| Nant Gwyllt Church | SN91809 63939 |
||
| Nant Gwyllt Cottages | SN91475 63413 |
||
| Nantgwyllt House | SN915 627 |
6-figure reference | |
| Nanty Postdy Bridge | SN91356 62202 |
Also known as Horse Bridge | |
| Pant y Blodau | SN91734 62678 |
||
| Pontbren Lloc-ddu (Old Foot Bridge) | Needs checking | Grid reference incomplete in source | View page |
| Stone Dressing Yard | SN913 646 |
6-figure reference | |
| Ty Nant House | SN9019 6727 |
||
| Ty Nant Water Bridge 1 | SN90208 67265 |
Lower bridge | |
| Ty Nant Water Bridge 2 | SN90145 67252 |
Upper bridge | |
| Ty Nant Water Spout | Needs checking | View page |
OS references have different precision. Six-figure references locate a 100 m square; eight-figure references a 10 m square; ten-figure references a 1 m square. Positions are plotted at the centre of their squares. References marked “Needs checking” are kept in the database but not plotted until corrected.
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All ruins & lost places →More of the valley's lost history
Browse abandoned farmhouses, sheepfolds and other ruins across the hillsides.