Water

Waste liquid discharges and sludge are disposed of into watercourses and through the sewage system. Organisations with permission to discharge into rivers are subject to conditions laid down by the Environment Agency. Local conditions are taken into account when licenses to discharge are agreed; a fast flowing well-oxygenated river can carry and disperse more pollution than a slow moving river in a valley bottom.

Discharges from an organisation into a water course are known as point source discharges. The biological oxygen demand (BOD) of the water course is calculated so that discharges are diluted sufficiently. However there are often diffuse and unknown discharges entering the water such as fertilisers and pesticides run off from farmland. These may be seasonal and contribute to the overall pollution.

Camelford case