The Tees Estuary (north-east England) has been industrialised since the ninteenth century and used for the disposal of industrial and domestic waste. Its physical nature has been changed by canalisation and dredging. In 1970 a number of water quality objectives were established by the Northumbrian River Board and local industry, and during the 1970's water quality improved. Classification analysis identifies 3 faunal associations within the estuary. The seaward end of the estuary has a typical estuarine fauna, and the middle reaches are dominated by an abundant fauna tolerant of organic pollution. Species diversity and abundance increased between 1979 and 1985 with the penetration of marine fauna into the estuary and increase in abundance in the middle reaches.
