View report page

213
River Pollution
Modified by industrial discharges rainfall, nevertheless, exerts
the greatest influence upon the quality of river water and, as one
would expect, the higher the rainfall the more able is the river to
stand pollutants. During 1970, total rainfall at 24.49 inches was
almost 20% higher than for last year but this was still 1.32 inches
less than the average for the previous 5 years.
Prevention of pollution in the River Thames and the tidal
reaches of its tributaries is the responsibility of the Port of London
Authority. In London, however, sewage and its disposal, amounting
to a daily dry flow of approximately 500 million gallons from
an area of 500 square miles serving a population of 7 millions, is
under the control of the Greater London Council and, after treatment
at the northern and southern outfalls at Beckton and Crossness
respectively, the resultant sewage effluent is discharged into the
Thames. It is then considered by various authorities to be a
pollutant which, on occasions, gives rise to complaints.
Daily samples of river water and their analyses, which have been
carried out by the G.L.C. and their predecessors since 1893, indicated
that during the latter half of the current year the Thames had
been appreciably affected by two events. In the July/September
quarter the daily average flow over Teddington weir was only one
half that for 1969 and the strike of local government manual
workers at the beginning of November which led to the discharge
from some works of a poorer quality effluent. In the Greenwich
and Woolwich Reaches of the Thames the effect was to produce
a considerable deterioration of the condition of the river water at
low tide. Increased pollution loads were prevented from producing
offensive and putrid conditions by the nitrate content of the goodquality
effluents discharged from the Crossness and Beckton outfalls
which acted as a reserve of oxygen.
Improvement in the ability of the tidal Thames to support marine
life is such that, since 1967, some 55 species of fish have been
identified as inhabiting that stretch of water between Richmond
and Gravesend which 15 years ago supported none. Recently a
2|- lb. sea trout was caught as far up-stream as Teddington Lock.
No complaints regarding pollution were made to this department
during 1970, a fact which owes much to the co-operation of the
P.L.A. and the G.L.C.'s Scientific Advisor.
Storm Flooding
As with 1969, no storm flooding occurred during the current year
and consequently, in this respect, no requests for assistance were
received.