| Name | Location | County | Country | Power source | Type | Function | River |
| Slate mill (1), Bwlch Cwmllan Slate Quarry | Bwlch Cwmllan, Betws Garmon | Caernarfonshire | United Kingdom | Water | Watermill | Quarry mill/wheel, Slate mill | Tributary to Cwm Llan |
| Slate mill (2), Bwlch Cwmllan Slate Quarry | Bwlch Cwmllan, Betws Garmon | Caernarfonshire | United Kingdom | Water | Watermill | Quarry mill/wheel, Slate mill | Tributary to Cwm Llan |