A short, steep Liébana tributary of the Deva, joining the parent river at Ojedo (Cillorigo de Liébana). The Bullón is alpine in character: limestone-and-shale bedrock, plunge-pool-and-pocket structure, the kind of water you fish wading slowly with a short rod. Wild brown trout only. Smaller and faster-falling than the parent Deva, the Bullón colours quickly in heavy rain but clears within hours, so it works well as a follow-on river when the Deva is still off. Best fished from late May through July, when the high meadows above Pesaguero come into their own and the river has dropped back from the snowmelt freshet.
- Limestone