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The following paragraphs give a general indication of the source of origin of these
samples and of the consultative and advisory duties carried out for the various services
and departments of the Council.
River Thames
The condition of the river flowing as it does through the County of London, is a matter
of great importance to the Council. In addition to effluents from the Council's own
sewage treatment plants, there are sources of pollution from other sewage works,
impure tributaries, trade discharges, and contamination from shipping. To assess the
condition of the water under varying conditions of fresh water and tidal flow, and to
compare the state between seasons of the year and over periods of years, regular weekly
examination are made, involving chemical analysis of water taken from 26 points
over a distance of 80 miles. The area examined extends from the upper limit of the tidal
reaches of the Thames at Teddington to the outer estuary sludge dumping area at Black
Deep.
The condition of the river is worst in the summer because of higher air temperature
and normally reduced fresh water flow, the most critical period being July to September.
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