the location of one of the world's largest cities, London, on its banks. As early as 

 1620, the bishop of London expressed in a sermon the hope that "the cleaning of the 

 river. . . will follow in good time." A century and a half later. Tobias Smollett wrote 

 in Humphrey Clinker. "If I would drink water, 1 must quaff the maukish contents of 

 an open aqueduct exposed to all manner of defilement; or swallow that which comes 

 from the River Thames, impregnated with all the filth of London and Westminster — 

 human excrement is the least offensive part of the concrete, which is composed of all 

 the drugs, minerals, and poisons used in mechanics and manufacture, enriched with 

 the putrefying carcasses of beast and man; and mixed with the scouring of all the 

 wash-tubs, kennels, and common sewers, within the bills of mortality." 



The Thames was still a good fishing river in the 18th century; large numbers of 

 salmon could still be caught. For exmaple, 1 30 were sent to market on a single day in 

 1766. As far as is known, the last salmon was caught in 1833, and by 1850 all 

 commercial fishing had ceased. 



Nothing was done to the river despite the fact that the condition of the Thames in 

 central London had become so vi4e in the mid-l9th century that sheets soaked in 

 disinfectant were hung in the houses of Parliament in an attempt to counteract the 

 stench. This culminated in 1 858 with a smell at Westminister so overpowering that its 

 control became of great personal interest to the members of Parliament. In that year, 

 work was started on the construction of intercepting sewers to carry the sewage from 

 central London to Barking on the north and to Crossness on the south side of the 

 estuary. 



As recently as 1957-58, Wheeler'-^ concluded that from the region of Gravesend 

 upstream for some 68 km there was no evidence of fish life (with the single exception 

 of eels, which were found in the upper reaches of this area). This was a period in 

 which there were extremely low dissolved oxygen concentrations and, at times, 

 anaerobic conditions in the river. 



During 1964 and 1965, reports of fish impingement (caught on intake pipe screens) 

 on the cooling water intake streams at the newly commissioned steam electric power 

 station at West Turrock indicated that some fish were returning to the river. As a 

 consequence, the Central Electricity Generating Board made arrangements to collect 

 fish caught on screens at the power stations in the London area. Between 1967 and 

 December 1973, a total of 68 species of fish were captured at power generating 

 stations on the intake screens. Of these, 18 were freshwater fish, and 43 were of 

 marine origin. Doxat" reports over 90 species of fish have been found in the Thames 

 tideway area in recent years. A serious effort is now being considered to restore the 

 salmon run to the Thames, i"* 



The Thames furnishes some very useful background information to consider in the 

 restoration of damaged ecosystems. Even though England was scientifically one of 

 the most enlightened places in the world during the period of the industrial revolu- 

 tion, little substantive data exist on the condition of the Thames before degradation 

 began, except for records for some of the commercially valuable species, and some 

 subjective evaluations of the quality of the water. 



Little seems to be known about the lower organisms present before degradation 

 began or even the higher organisms considered then to have no particular economic 

 value. Since ecology is a relatively new science which really began to flourish only in 

 the last part of this century, measurements of various rate processes (such as carbon 

 fixation, recruitment rates for various species, etc.) are totally unknown. In short, 

 most of the measurements considered important by contemporary ecologists are 

 unavailable for both terrestrial and aquatic ecosystems in which the degradation 

 process began with industrialization. Who knows much about the ecology of the 

 Ohio River before the locks and dams were installed? 



225 



