27 September 2007
Report finds Thames hides health hazards
A major report on Thames river quality suggests people using it
for leisure pastimes face an increased risk of infection each time
heavy rainfall causes untreated sewage to flow into the river.
The City of London Corporation, which commissioned the study
from the Health Protection Agency (HPA), is to lead a drive for
increased water monitoring and explore a pollution early warning
service for Thames leisure users.
The moves are also seen as important in ensuring safe water
standards for international visitors and water sports participants
who might use parts of the Thames for training in the run-up the
London 2012 Olympic Games and Paralympic Games.
The HPA tests carried out over a 90 week period were conducted
at Kew, Barnes and Putney which are popular with rowers, canoeists,
fishing enthusiasts and other leisure users.
They confirmed that the water contained bacteria and viruses
associated with human and / or animal faecal pollution which could
cause gastroenteritis and other infections.
As London’s Port Health Authority, the City Corporation –
supported by the Health Protection Agency – looks after public
health issues along 94 miles of the tidal Thames.
The City Corporation’s top Port Health official Jon Averns said
the report was further vindication of its concern at water quality
issues in the upper river and its determination to try to minimise
risks to users.
Mr Averns, London Port Health Authority Director, said: “It is
clear from the data that following heavy rainfall untreated sewage
enters the river and increases the risk to health of recreational
users of the upper river for as long as two to four days following
such an event.
“Up to now it was thought that the increased risk was for one or
two days. This evidence is very significant.”
Sewage contamination of the Thames occurs when treatment works
are unable to cope with excess surface water following heavy
rainfall. The water is then discharged with raw sewage through a
Combined Sewer Overflow (CSO). A CSO is an open-ended pipe designed
to dispose of overflows when the capital’s sewage system is under
pressure, especially as a result of cloudbursts.
Mr Averns urged a multi-agency approach to publicising,
monitoring and tackling river-borne pollution. Risk must be
minimised by letting users know its extent in good time, he
said.
Dr Susanne Surman-Lee, who led the investigation into the river
water quality for the HPA said: “People using the Thames for
recreation purposes should not be alarmed by these results. They
should however be aware of the possibility of contracting
infections as a result of using the water and should therefore
ensure they wash their hands thoroughly after using the river,
particularly before eating or drinking, and try not to swallow any
water if they should fall in.”
Jon Averns added: “Although the reaches of the river that were
tested will not be used for actual events, it is possible that they
will be used for training in the run-up to the London 2012 Olympic
and Paralympics Games. The City of London wishes to ensure that all
river users and visitors are aware of the potential hazards
associated with river water, and also that all possible measures
are taken to minimise the risks to them.”
The three-year Thames Recreational Users Study is the biggest
and most accurate survey of the presence of microorganisms linked
to faecal pollution in the Thames, and the impacts of heavy rain
and tides. It was undertaken to assess the impact of discharges on
leisure users.
The study also highlighted concern about possible shoreline
contamination in sand and gravel contaminated by river water
containing untreated sewage.
This third and final phase of the study pinpoints a need for
continued sustained water sampling to build data on trends in
various weather conditions which would be used to help predict poor
water quality.
Welcoming the report, the City Corporation’s Port Health and
Environmental Services Committee said the data should be used to
examine the feasibility of an information system to inform the
public in a timely manner of risks associated with tideway usage.
It is expected such a system would be both online and riverbank
based.
Problems have been caused when 19th-century water and sewage
systems become overloaded by the 21st-century London population,
especially during heavy rainfall when sewage treatment works are
overwhelmed with the increased volume of rainwater.
Consequently, sewage-contaminated water pours into the river
from some of the 57 CSOs, causing potential public health threats
and, occasionally, fish-kills.
The report found evidence that
- basic water quality parameters at Kew, Barnes and Putney, did
not meet World Health Organisation (WHO) recommended levels for
recreational use
- water quality improves downstream, from Kew to Barnes and
Putney
- there is an elevated risk to users of the upper tideway of the
Thames for up to four days after combined sewer overflow (CSO)
events
- 91 percent of days when samples were taken high levels of
bacteria including Salmonella and Campylobacter were found, the two
most common causes of food poisoning.
Mr Averns said: “The City has a commitment via its Community
Strategy to have a clean, pleasant, attractive and healthy City. As
London Port Health Authority, the City of London has overall
responsibility for public health issues on the Thames tideway.”
Thames Recreational Users Study - download the full
report or summary here
Summary of the Thames Recreational Users Study –
Final Report with recommendations.
Ends
Note to Editors
- Tests were conducted over 90 weeks between Jan 2005 – Oct
2006.
- The study also assessed whether more river users contracted
infections as a result of using the river. Researchers interviewed
those who reported illness and compared their recent history of
river use with others who had not been ill. 18 river users reported
illness. The study showed those who reported illness were more
likely to have fallen in, swallowed water or received a splash to
their face. However, due to the small number who reported illness,
it was difficult to fully evaluate the results.
- The low number of river users reporting illness could be
explained by the fact that they have built up immunity to some of
the bacteria and viruses in the water due to having been exposed to
them before; or their good state of health due to regular physical
activity.
- Government plans a 30 km tunnel, to be completed by 2019/2020
to intercept discharges from Hammersmith to Beckton. It will
include an early phase side-link from Abbey Mills to Beckton
- Improvements are to be made to major sewage treatment works at
Beckton in north London, Crossness in south London and Mogden in
west London.
- The tunnel will not stretch to Mogden and consequently will not
dispose of the untreated overflow from Mogden sewage treatment
works at times of heavy rain.
The City of London Corporation provides local government
services for the City of London, the financial and commercial heart
of the UK. We are committed to maintaining and enhancing the status
of the business City as the world's leading international financial
and business centre through its policies and services. Our
responsibilities also extend far beyond the City boundaries and
include management of the Barbican Centre, Central Criminal Court
at the Old Bailey, Epping Forest, Hampstead Heath, three wholesale
food markets, as well as acting as the London Port Health
Authority.
Press enquiries:
City of London Press Office:
Martin Cowley: 020 7332 1452 Direct Line: mobile 07990 560 601
London Port Health Authority Director, Jon Averns: 020 7332
1603: mobile 07802527940
Health Protection Agency
London Regional Communications Team: 020 7759 2824