The River Blackwater drains a heavily urbanised area that has grown rapidly in the past 60 years. For most of its length the quality of the river water is dominated by treated sewage effluent from the series of sewage works that discharge into the river. Considerable efforts have been made in recent years to improve the quality of this effluent, and to prevent pollution incidents which have in the past severely affected fish life in the river.
The biological quality of the water is fairly good and is gradually improving. Biologists regularly sample the riverís quality by measuring levels of polluting chemicals and also for aquatic invertebrates, which act as long-term indicators of water quality. Dragonflies, damselflies and cased caddisflies are used as indicators of organic pollution, but the numbers of all are increasing downstream of Aldershot, a positive sign.
If you see any pollution in the river please call the Environment Agency Hotline on 0800 80 70 60 and be prepared to give an accurate description of where the pollution has been seen and its nature.
The Environment Agency publishes a fact file leaflet on the River Blackwater or visit their website.