On the eve of the Queen’s Diamond Jubilee Pageant, new report explains how increasing sewage pollution to the tidal Thames risks undoing decades of improvements to river water quality.
Report highlights how lack of capacity in Victorian sewerage network was responsible for approximately half of pollution to river between Chiswick and Hammersmith last June, which in total killed 26,000 fish.
10,000 tonnes of sewage-related litter, such as condoms, sanitary products and cotton buds, flushed into the river every year.
Green campaigner Tony Juniper: “The Thames Tunnel is not an optional nicety, it’s a long overdue environmental necessity.”
Wildlife that has returned to the River Thames urgently needs the proposed Thames Tunnel, according to a new Thames Water report, backed by the Environment Agency.
Launched today (29 May) at Fishmongers’ Hall in the City, ‘Why does London’s river need the Thames Tunnel?‘ explains how increasingly frequent discharges of untreated sewage to the tidal Thames are devastating fish populations, and threatening other wildlife, such as birds and insects.
The discharges occur around once a week on average, when London’s Victorian sewerage network fills to capacity, sometimes after as little as 2mm of rainfall. They enter the river via ‘combined sewer overflows’ (CSOs), integral to the design of the network, founded over 150 years ago by Sir Joseph Bazalgette.
Though diluted by rainwater, the sewage washed into the river from homes and businesses is a potent cocktail of pollutants, containing pathogenic bacteria and viruses, as well as pharmaceutical products, petroleum residues, paints, pesticides, plastics, fertilisers, fats, oils and heavy metals.
Tidal effects mean that the discharges can linger in the river for up to three months.
Depleted oxygen levels a killer for fish life
The river is also a vital nursery ground for species fished commercially in the North Sea, such as smelt, sea trout, eel, bass and flounder.
Young fish, vital for species’ long-term survival, are particularly vulnerable to reduced levels of oxygen in the river, caused by the CSO discharges.
The problem is particularly acute during summer months, when warmer temperatures accelerate the depletion of oxygen levels.
Fish exposed to even low levels of ammonia over time become more susceptible to bacterial infections, impeding their growth.
On 6 June 2011, 30mm of rainfall in west London caused more than more than 450,000 cubic metres of sewage (enough to fill 86,000 builder’s skips) to spew into the RiverThames from CSOs between Chiswick and Hammersmith and via Mogden Sewage Treatment Works in Twickenham. This one incident wiped out an estimated 26,000 fish, including species of high conservation value, such as sea trout, eel and smelt.
Sewage-related litter blights the landscape and wildlife
An estimated 10,000 tonnes of sewage-related litter, such as condoms, sanitary towels and cotton buds, is flushed into the River Thames every year via the CSOs.
Not only are these products an unsightly blot on the landscape, often becoming embedded in the foreshore, they never truly disappear. As they gradually break down into smaller pieces, they are injested by worms and other invertebrates, polluting the food chain for fish and birds.
Larger birds and aquatic mammals, such as dolphins and porpoises, can choke to death when they mistake larger items of litter for food.
The commercial benefits of a cleaner river
Aside from their ecological and biodiversity value, healthy fish stocks in the river are economically important too.
Trade in species dependent on the river, such as dover sole, thornback ray and bass, as well as cockles and other shellfish, is a key contributor to the wider economy of the UK.
Speaking at the launch, green campaigner and sustainability specialist Tony Juniper will say:
“The Thames Tunnel is not an optional nicety, it’s an environmental necessity.
“Increasing levels of sewage in the river are a very real threat to the well-being of one of the country’s most important ecological assets and the rich diversity of wildlife it supports. Population growth and the impacts of climate change add to the urgency to solve this problem for the long-term.
“I call on everyone who cares about the river to get behind this long overdue project.”
Mark Lloyd, Chief Executive of the Angling Trust, said: “The very location of London was determined by the great meeting point of marine and freshwater ecology that provided plentiful food to Londoners for thousands of years. The estuary is poised to recover this role, but it cannot do so unless the problem of overflowing sewers is tackled.
“A restored river would provide a massive boost to the angling industry in London and help the sea angling and commercial fisheries of the outer estuary and the North Sea. The only feasible way to achieve this vision, and the most cost-effective, is to build the Thames Tunnel. It should have been built decades ago.
Richard Aylard, Thames Water’s External Affairs and Sustainability Director, said:
“These discharges are the last major source of pollution to the tidal river.
“A lot of hard work and investment, funded by our customers, has made the river a lot cleaner than it was just a few decades ago, but we urgently need the Thames Tunnel to help keep it that way.
“Without the Thames Tunnel, the huge improvements achieved in recent years would be quickly reversed. That’s an unacceptable legacy to hand on to future generations to sort out. ”
Notes to editors
Other speakers at the report’s launch will include Roger De Freitas (from the Hammersmith Society and river clean up charity Thames21), and Jill Goddard (Chief Executive of the Thames Estuary Partnership).
For further information, or to attend the report launch, please contact the Thames Water Press Office (0203 577 4364).