The Ponga arrives into the Sella network from the south, a slate-limestone mixed river with pronounced spate character. The upper reaches are step-pool through mixed lithology; the descent is steep and response immediate. The water carries both limestone clarity and slate amber tones blended. The middle Ponga opens into pool-riffle sequences on cobble; the pools are productive. The river's character maintains its responsive disposition throughout. The wading demands care in the upper step-pool sections, becoming more approachable as the river opens.

Wading: Polished wet limestone slabs at step lips

In the mountain-to-sea trout rivers of Asturias, olives and other mayflies do much of the work in spring whenever levels and colour allow, followed by strong evening caddis and steady buzzer life through early and mid-summer, with terrestrials and mixed surface food from wooded, pastoral banks rounding out the diet whenever flows drop back into safe wading range.