Below the Bilancino dam the Sieve becomes a different river entirely — the reservoir strips out summer's worst heat and turns what was once a warm, sluggish stretch of Mugello water into something a trout can live in year-round. The Tail Water Sieve project has spent nearly two decades rebuilding a self-sustaining population here: sixteen kilometres of regulated water running down past San Piero a Sieve toward the Muccione confluence, split between a fly-and-spinning no-kill zone immediately below the powerhouse and a fly-only stretch further down. It fishes like an argument for dam tailwaters generally — cold, consistent, technical, and, thanks to the release schedule rather than in spite of it, still fishable in the heat of a Tuscan August, when most free-flowing Apennine streams have shrunk to a trickle and their trout have gone looking for shade.

• Sandstone shale