Environment Ontario Legacy, Vol 11, No. 3 January 1983. Pg. 33
In 1981 seven adult salmon were caught in the Thames River and many more were sighted as far as 100 km upriver from London. They were the first of 50,000 yearling salmon (parr) seeded in the Thames in 1979 by the Thames Migratory Fish Committee.
The last commercial catch of salmon in the Thames was registered 161 years ago, in 1821 . After that, it took two outbreaks of Asiatic cholera in 1840 and 1850 to convince the authorities that a sewage system was necessary. Westminster draped in sheets soaked in disinfectants to hide the river’s stench helped too.
The sewage works of the time did not include treatment. By 1950, the Thames was anaerobic again and devoid of life.
Thames’ water quality was only improved after construction of sewage treatment plants at Beckton, Crossness and other places.
These plants improved the water quality to such a degree that a variety of less sensitive fresh water and marine species returned by themselves to the Thames Estuary. Eventually in 1979 re-stocking with salmon could be attempted.
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