5 February 2022 | New Scientist | 23Field notes EnvironmentHow to clean up a river A partnership between farmers, the water
industry and local volunteers may provide the answers to a river
pollution crisis in England, finds Adam Vaughan in Oxfordshire“IT’S depressing. It’s something
we should be able to put right,”
says Mark Purvis, standing next
to a brook feeding the Evenlode,
a river in the Cotswolds area of
southern England that has been
plagued with water pollution in
recent years. “We’ve seen declines
in numbers of fish, insects and
weed growth in the river. And
terrible turbidity [cloudiness]
in summer,” he says.
The Evenlode’s problems
aren’t unique. England’s rivers are
“a mess”, a report by MPs on the
Environmental Audit Committee
(EAC) concluded last month, due to
a lack of funding and monitoring
and what was called “a ‘chemical
cocktail’ of sewage, agricultural
waste, and plastic”. But a special
partnership between local people,
the water industry, farmers and
others means that the Evenlode
could hold the answers to how
the nation can clean up its rivers.
The pressure for action is
growing: on 23 January, around
500 people protested in Oxford
against sewage discharges in
nearby rivers, in the wake of
concerning footage of effluent
flowing from a sewage works
in a catchment area adjacent
to the Evenlode.
Follow the brook upstream
from where Purvis, a local
resident, is standing and you get
to the Milton-under-Wychwood
sewage treatment works, one of 19
such facilities in the river’s
catchment area that have
sometimes struggled to keep
up with a growing population.
There were 96 occasions last year
when untreated sewage spilled
into the brook as the works ran
out of holding capacity, for a
total of 1406 hours.
“It’s a very high-spilling site,”
says Andrew Scott at Thames
Water as he overlooks a concrete
storm tank at the works. TheNew Scientist Video
See video of this report and much more online
youtube.com/newscientistCharlotte Henderson
(above) and an aerial
view of the river (left)DA
VID
ST
OC
K
Over in wheat fields at the
nearby Bruern Estate, farm
manager Matt Childs points to
his efforts to stop that phosphorus
reaching the Evenlode. Fences have
been erected to keep cows and their
dung away from streams where
land is prone to flooding. Most
of the phosphorus is locked in the
soil, so a big focus is keeping that
from reaching waterways around
the 5-square-kilometre farm.
The corners of some fields have
been designated as buffer areas
for flooding, while embankments
have been raised around fields
to keep water in and the soil is
managed to help it retain water,
such as by avoiding tilling in some
fields. A series of ponds have also
been created in one field to filter
phosphorus out of the water.
The estate’s biggest water quality
issue turned out to be leaking
septic tanks – now replaced –
rather than food production.
Water quality can be a low
priority for some farmers due
to how it is regulated, says Childs.
“It’s very much, for me, a personal
thing to do it properly. But you’re
aware if you don’t, there’s not
much of a downside.”
Back at the brook with Purvis,
local volunteers are pursuing
another route to cleaner rivers:getting a better handle on what
is actually happening. Monitoring
of England’s rivers is “outdated,
underfunded and inadequate”,
the EAC said in its recent report.
While community partnerships
like the one in the Evenlode
catchment area have been around
in England since 2013, this is a new,
enhanced version with serious
resourcing: £3 million over five
years from Thames Water. That
means it can provide serious
equipment, such as the £25,000
metal cylinder that Charlotte
Henderson at the charity
Earthwatch pulls out of the
stream. It gauges pH levels,
biological oxygen demand and
faecal matter – and it will soon
broadcast its measurements
online in real time. “It’s about
making the invisible visible
to people,” says Henderson.
Whether such beefed-up
partnerships can be replicated
regionally or nationally remains
to be seen, but Purvis is hopeful
that a cleaner Evenlode is possible.
“I’d like to see this river running
clear through the summer, with
children playing in the river safely,
dogs able to swim without getting
sick and with wonderful wildlife
we should see on all our Cotswold
rivers,” he says. ❚facility is small, old and vulnerable
not just to rainfall, but also to water
“infiltrating” through the ground.
Part of Thames Water’s answer
to this problem is a £1.7 million
upgrade due to take place by 2025,
which should increase the volume
of water the site can process per
second by a third, meaning it
doesn’t need to spill.
The Evenlode’s problem
pollutant is phosphorus, rather
than nitrogen as in some other
rivers. Around two-thirds of the
phosphorus comes from sewage
treatment works, including
Milton-under-Wychwood.
Another 28 per cent comes from
agriculture and land use, such as
cow dung and phosphate-laden
soil that has washed off farms.The Milton-under-
Wychwood sewage
treatment worksNews