The River Avon in Wiltshire is a classic English chalk stream, globally recognized for its exceptional biodiversity and rich fly-fishing heritage. It flows across Salisbury Plain, passing near the iconic Stonehenge, and is celebrated for its clear, stable waters and abundant aquatic life. The river system, including its tributaries like the Nadder, Wylye, Bourne, and Ebble, contains more species of wild fish than any other river in Britain. It is a designated Special Area of Conservation, underscoring its ecological importance for habitats like stream water-crowfoot and species including Desmoulin's whorl snail.