The River Tees was once one of the most polluted in Britain. In 1970, over 500 tonnes of waste were being discharged into it every day. This caused the water temperature to rise, with a corresponding decrease in the dissolved oxygen it contained. Not surprisingly, such conditions were detrimental for wildlife survival in the river.
In 1972, plans were drawn up to tackle the problem. A gradual decline in heavy industries and a tightening of discharge permits began the decline in water pollution and Teessides image as a dirty area has changed. Much of the land once used by heavy industry has been reclaimed and developed for new business, public recreation and leisure. Between 1990 and 2001, water quality of the Tees Estuary improved dramatically and migratory fish have returned gradually to the River Tees due to recent improvements to intercept and treat domestic sewage and industrial discharges.
Wildlife in general thrives throughout the Tees Corridor and many areas are now being managed specifically for biodiversity. For further information, see the links below to Tees Valley Wildlife Trust, Environment Agency and Natural England.