The Test, Itchen and Meon rivers are chalk stream rivers, one of the rarest habitats on the planet. The Test & Itchen are both classified as Sites of Special Scientific Interest (SSSI), with the Itchen additionally designated as a Special Area of Conservation (SAC). Chalk streams are globally rare, with only around 200 in the world. The unique nature of chalk streams comes from the chalk bedrock aquifer. When the rock is full and can hold no more, water bursts out in the form of springs. It is highly filtered, cool and mineral rich water with a constant flow. These conditions are ideal for the rare chalk stream salmon, a sub species of the Atlantic Salmon, which is now officially endangered.
Chalk streams are typically shallow and very finely balanced river systems whose eco-system is highly sensitive when too much water is removed and the flow decreases. Over-abstraction of water from the rivers, sewage overflows and chemical pollution is now putting these valuable eco-systems – and the salmonids and all aquatic life that depend on them – at risk.