The Elorn rises a stone's throw from the moorland of the Monts d'Arree and runs some forty-two kilometres across north Finistere — through Sizun, Landivisiau and Landerneau — to a long estuary opening into the Rade de Brest. It is a modest Breton river of clear, cool, acidic water off the granite uplands, fed by sixteen tributaries and by the Drennec reservoir near its source, which steadies the upper flow as a tailwater below the dam. For all its reputation it rarely exceeds ten metres in width, a small river of easy pools and gentle gradient running through wooded and farmed country. It holds a stable run of Atlantic salmon — a couple of hundred fish in recent years — and beautiful trout that share the lower water. The character is intimate, slow-profiled freestone where the salmon lies are easy to read. Wading is steady on firm rock and gravel.

Wading: Steady footing on a small clear river

On Atlantic trout rivers in Normandy and Brittany, regional studies and on-the-bank experience point to spring mayflies as the main early driver, a strong band of spring and early-summer caddis as channels warm and open, background buzzer life ticking away right through the year, and terrestrials from wooded banks adding important surface food in summer and early autumn, with autumn olives extending sport wherever trout-season rules allow.

Summer-autumn runs, seasonal patterns vary by region