The Porcía runs from western Asturian slate country down toward the coast at Llanes province. The upper reaches are step-pool slate pocket water, steep and spate-responsive. The descent is rapid and the water amber-colored from its slate origins throughout. The middle Porcía opens slightly into partly-confined pool-riffle on cobble emerging from slate. The pools have been fished for generations; they're marked and known by local tradition. The river maintains its spate character — quick to rise, quick to fall, responsive to weather — throughout its course. The wading demands attention in the upper sections; the middle reaches become more approachable.

Wading: Slick wet slate ledges

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.