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- Ogden Reservoir - Greater Manchester
- Ogden Reservoir (Lancashire) - Lancashire
- Ogston Reservoir - Derbyshire
- Old Ford- Greater London
- Oldbury Reservoir - Warwickshire
- Olton Reservoir - West Midlands
- Orchardleigh Lake - Somerset
- Ormesby Broad - Norfolk
- Ormesby Little Broad - Norfolk
- Oulston Reservoir - North Yorkshire
- Oulton Broad - Norfolk
Read more about this topic: Lakes Of England, Lakes Larger Than 5 Hectares