View report page

Class 3: These rivers may support coarse fish but they are not fit for use for public water
supply or high grade industrial use and may not be fit for irrigation or for supplying
cooling water for industry.
Class 4: These rivers cannot be used for public water supply, by agriculture for irrigation
or by industry for process water. They are not pleasant for people who live or
work by them or who use them for recreation.
The Report states that there are some 5,000 municipal sewage treatment works in England
and Wales serving over four-fifths of the population; under 20 per cent of these serve populations
of over 10,000. The works discharge mainly to rivers and in a few places to estuaries, the most
notable being the Thames which receives vast quantities of effluent. However, the Report cites
evidence that about 60 per cent of local authorities' sewage effluents fail to reach the standard
recommended by the Royal Commission on Sewage Disposal for no more than 30 m.g/l (30 p.p.m.)
of suspended solids and 20 m.g/l for B.O.D. (20 p.p.m.)
For centuries river estuaries have been regarded as being in the same category as the sea
in being able to absorb large quantities of pollution. The vast quantity of sewage sludge which
has been discharged a few miles from the shore for many years is testimony to the capacity of the
sea to receive large amounts of wastes without significant effect and a few special studies have
confirmed that at suitable sites, enormous dilution is readily available and biological purification
takes place. It is estimated that some five million cubic metres of domestic sewage is piped to
the sea every day.
However, some effluents have of late been discharged without treatment, which has resulted
in very severe pollution specially in or near mouths of rivers. The 1958 Ministry of Housing and
Local Government Survey found that tidal rivers to the then seaward limits were more polluted
than either non-tidal rivers or canals. As the information was less complete than for rivers, the
following figures should be taken only as a general indication of the state of tidal rivers and
estuaries in 1958.

The Working Party on Sewage Disposal says there are some badly polluted estuaries in the
conurbations - the Mersey, Tees, Tyne, Wear, Humber, Severn, Usk and Ribble. The only major
estuary not significantly polluted is the Solway Firth, containing the Esk and Eden estuaries.
In the Humber estuary the main cause of pollution is the pollution load brought down by the
rivers Ouse and Trent. The Tees, it is said, receives 500 untreated discharges and the Tyne
receives sewage and trade waste through 270 outfalls. On the Welsh Coast of the Severn estuary
there are 90 outfalls discharging sewage and trade waste from 1.1 million people (40 per cent of
of the population of Wales). The Severn and the Thames estuaries are used for the disposal of
sludge by sludge vessels. In the case of the Thames estuary, some five million tons of digested
sludge are dumped each year without creating a sea floor "desert".
(b) Toxic Wastes
The Technical Committee on the Disposal of Toxic Solid Wastes (6) found there was no
satisfactory definition of the word "toxic" but as the pollution prevention Acts spoke of "poisonous,
noxious and polluting matter" they did not try to distinguish precisely between these words
and took it that "poisonous" and "toxic" were almost synonymous in common or everyday use.
As this paper is restricted to marine pollution, a brief outline as to how the inshore tipping
of toxic waste may create ultimate river pollution is appropriate. There would be no pollution due
to solid waste tipped dry were it not for rain. If the tip itself, the toxic wastes in it and the
surrounding land are all permeable, then the rain fall should percolate vertically downwards.
The water reaching the waste should in fact be no more than the rainfall minus the evapotranspiration
for the area. If it is more, the percolate will eventually reach an impermeable layerand
find its way via surface drainage to a stream. Opportunity for dilution and oxidation varies according
to local geology and is limited in some circumstances. Because of this, detectable
pollution of streams occurs more frequently than pollution of underground water sources. Detectable
pollution will most likely be found in watercourses close to tips and grazing lands during the
wettest period of the year, i.e. November to March. This could be a major hazard, since about one
third of Britain's drinking water supplies is abstracted from underground sources and a further
third comes from lowland river systems-