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67
The Pippard Report, entitled Pollution of the Tidal Thames
and issued towards the end of 1961, contained much useful and
enlightening information on the subject of river pollution and
points out that since the introduction of these new services there
has been a substantial reduction in pollution.
That salmon may once again be able to gain the upper
reaches of the Thames as they did at the beginning of the 19th
century is the hope held out to us by the Water Pollution Research
Laboratory in its report entitled Effects of Polluting Discharges
on the Thames Estuary. Inter alia, the report reveals that during
the summer of 1964 the average oxygen concentration was in the
order of 7 per cent, of the saturation value compared with a
maximum of 30 per cent, expected when the London County
Council's new biological treatment plant at Barking becomes fully
operative.
Since 1893, the County Council have sampled the Northern
and Southern outfalls at high and low tides but in recent years a
scheme has been introduced whereby weekly samples are taken at
22 points from Richmond to Mucking (downstream of Gravesend)
and monthly samples at 29 points from Richmond to the sludgedepositing
area of Black Deep. Examination of water over the
weir at Teddington is made by the Thames Conservancy Board.
Weather during 1964 wa,s unusual in that it was warmer than
recent years, abnormally dry in January and February, wetter
than usual from March to June and exceptionally dry for the rest
of the year. During the summer quarter the average daily flow
at Teddington was 40% less than during 1963 and only ¾ of the
average daily flow for the past ten years. Nevertheless, there
was a very marked decrease of hydrogen sulphide in the water
and that at no point during the summer was a sample devoid of
oxygen, this being the first occasion since 1921 of such an
occurrence. Only 11 samples were reported upon as containing
hydrogen sulphide and in no week was the sulphide consistently
present. Considering that the fresh water flow over Teddington
Weir during the last quarter was the lowest since 1933, the
remarkable improvement in the condition of the river must be
regarded as being due mainly to the enhanced standards of the
discharged effluents at Beckton and Crossness. Unfortunately it
must be stated that although the up-river section showed an
appreciable improvement throughout during the year, the middle
section of some 6 miles which recorded an improvement in 1963