Llyn Celyn
E260949
Llyn Celyn is a large reservoir in North Wales, created in the 1960s by flooding the Tryweryn Valley, including the village of Capel Celyn, to supply water to Liverpool.
All labels observed (5)
| Label | Occurrences |
|---|---|
| Llyn Celyn canonical | 11 |
| Llyn Celyn reservoir | 3 |
| Capel Celyn | 1 |
| Llyn Celyn (nearby reservoir) | 1 |
| Llyn Celyn dam | 1 |
How this entity was disambiguated
This entity first appeared as the object of triple T2156723 — resolving that mention is where its identity was fixed. The disambiguator weighed these candidate entities and picked the highlighted one (or “None”, minting a new entity). This is how homonymy is resolved: the same surface form can point to different entities.
NED1
Entity disambiguation (via context triple)
gpt-5-mini-2025-08-07
Target entity: Llyn Celyn Context triple: [Arenig Fawr, overlooks, Llyn Celyn]
-
A.
Garreg Ddu Reservoir
Garreg Ddu Reservoir is a scenic man-made lake in the Elan Valley of mid-Wales, known for its distinctive submerged dam and role in supplying water to the city of Birmingham.
-
B.
Llyn Tegid
Llyn Tegid, also known as Bala Lake, is the largest natural lake in Wales, renowned for its scenic beauty and unique aquatic wildlife.
-
C.
Llyn Dinas
Llyn Dinas is a scenic natural lake in the Snowdonia region of North Wales, popular for walking, photography, and its surrounding mountainous landscapes.
-
D.
Llyn Llydaw
Llyn Llydaw is a glacial lake on the eastern flanks of Snowdon in Snowdonia National Park, Wales, renowned for its scenic mountain setting and association with local legends.
-
E.
Claerwen Reservoir
Claerwen Reservoir is a large upland water reservoir in mid Wales, known for its impressive dam and scenic surroundings within the Elan Valley.
- F. None of above. chosen
- G. Unsure - the case is ambiguous/there is not enough information to decide.
NED2
Entity disambiguation (via description)
gpt-5-mini-2025-08-07
Target entity: Llyn Celyn Target entity description: Llyn Celyn is a large reservoir in North Wales, created in the 1960s by flooding the Tryweryn Valley, including the village of Capel Celyn, to supply water to Liverpool.
-
A.
Garreg Ddu Reservoir
Garreg Ddu Reservoir is a scenic man-made lake in the Elan Valley of mid-Wales, known for its distinctive submerged dam and role in supplying water to the city of Birmingham.
-
B.
Llyn Tegid
Llyn Tegid, also known as Bala Lake, is the largest natural lake in Wales, renowned for its scenic beauty and unique aquatic wildlife.
-
C.
Llyn Dinas
Llyn Dinas is a scenic natural lake in the Snowdonia region of North Wales, popular for walking, photography, and its surrounding mountainous landscapes.
-
D.
Llyn Llydaw
Llyn Llydaw is a glacial lake on the eastern flanks of Snowdon in Snowdonia National Park, Wales, renowned for its scenic mountain setting and association with local legends.
-
E.
Claerwen Reservoir
Claerwen Reservoir is a large upland water reservoir in mid Wales, known for its impressive dam and scenic surroundings within the Elan Valley.
- F. None of above. chosen
Statements (50)
| Predicate | Object |
|---|---|
| instanceOf |
artificial lake
ⓘ
reservoir ⓘ |
| associatedWith |
Welsh nationalism
ⓘ
“Cofiwch Dryweryn” slogan ⓘ |
| associatedWithEvent |
Capel Celyn eviction
ⓘ
Tryweryn flooding ⓘ |
| basinCountry | United Kingdom ⓘ |
| constructionStartDate | 1960 ⓘ |
| country | Wales ⓘ |
| createdBy | Tryweryn reservoir scheme ⓘ |
| createdByFlooding |
Capel Celyn
ⓘ
linked to:
Llyn Celyn
Tryweryn Valley ⓘ |
| elevationAboveSeaLevel | approximately 240 metres ⓘ |
| hasCatchmentArea | approximately 26 square miles ⓘ |
| hasDamHeight | approximately 42 metres ⓘ |
| hasDamLength | approximately 750 metres ⓘ |
| hasDamType | rock-fill dam ⓘ |
| hasMaximumLength | approximately 4 km ⓘ |
| hasMaximumWidth | approximately 1 km ⓘ |
| hasNameMeaning | “Holly Lake” in English ⓘ |
| hasSpillway | concrete spillway ⓘ |
| hasSurfaceArea | approximately 3.25 square kilometres ⓘ |
| hasVolume | approximately 81 million cubic metres ⓘ |
| inception | 1965 ⓘ |
| inflow |
River Tryweryn
ⓘ
linked to:
Afon Tryweryn
|
| languageOfName | Welsh ⓘ |
| locatedIn |
Gwynedd
ⓘ
North Wales ⓘ River Tryweryn basin ⓘ Tryweryn Valley ⓘ
linked to:
Vyrnwy valley
|
| locatedInNationalPark |
Snowdonia National Park
ⓘ
linked to:
Snowdonia
|
| locatedNear |
A4212 road
ⓘ
Bala ⓘ |
| openingDate | 1965 ⓘ |
| operator | Dŵr Cymru Welsh Water ⓘ |
| outflow |
River Tryweryn
ⓘ
linked to:
Afon Tryweryn
|
| ownedBy | Dŵr Cymru Welsh Water ⓘ |
| politicallyControversial | true ⓘ |
| purpose |
regulation of river flow
ⓘ
water supply ⓘ |
| submergedInfrastructure |
chapel at Capel Celyn
ⓘ
farms in Tryweryn Valley ⓘ post office at Capel Celyn ⓘ school at Capel Celyn ⓘ |
| submergedSettlement | Capel Celyn ⓘ |
| suppliesWaterTo |
Liverpool
ⓘ
Wirral ⓘ |
| usedFor |
fishing
ⓘ
hydroelectric power generation ⓘ recreational activities ⓘ |
How these facts were elicited
The pipeline generated the facts above by prompting gpt-5.1 with this entity's name + description and the instruction below.
Instruction
You are a knowledge base construction expert. Given a subject entity and a description of it, return factual statements that you know for the subject as a JSON list of dictionaries(triples), where keys must be "subject", "predicate" and "object". The number of facts may be very high, between 25 to 50 or more, for very popular subjects. For less popular subjects, the number of facts can be very low, like 5 or 10. # Requirements - If you don't know the subject at all, return an empty list. - If the subject is not a named entity, return an empty list. - Include at least one triple where predicate is "instanceOf". - Do not get too wordy. - Separate several objects into multiple triples with one object.
Input
Subject: Llyn Celyn Description of subject: Llyn Celyn is a large reservoir in North Wales, created in the 1960s by flooding the Tryweryn Valley, including the village of Capel Celyn, to supply water to Liverpool.
Referenced by (17)
Full triples — surface form annotated when it differs from this entity's canonical label.
linked to: Llyn Celyn
linked to: Llyn Celyn
linked to: Llyn Celyn
linked to: Llyn Celyn
linked to: Llyn Celyn
linked to: Llyn Celyn
subject linked to:
“Holly Lake” in English
subject linked to:
“Holly Lake” in English