Thames River Pollution: A Historical Account

The River Thames has been a source of life for London, providing water and food, trade, and pageantry. However, for hundreds of years, it was also the city's sewer. In the absence of widespread sewage systems, domestic and factory waste seeped into the groundwater, and London's tributaries to the Thames became dumps. In 1858, the sewage clogging the Thames caused a Great Stink, and by the mid-1800s, as London's population grew, the river's pollution problem reached a crisis point. Despite improvements in water quality since, the Thames continues to face pollution issues, with high levels of microplastics, bacteria, and viruses found in recent years.

Industrial and domestic waste

The River Thames was once declared "biologically dead" due to the high levels of pollution it endured, especially from industrial and domestic waste. During the Victorian era, all kinds of waste, including industrial, household, and untreated sewage, ended up in the Thames. The river was used as a dumping ground for waste from factories, slaughterhouses, and other industrial activities, which put a strain on the ageing and inadequate sewer system. This waste included high-temperature wastewater, suspended solid particles, acids, alkalis, and other soluble substances.

The problem of pollution in the Thames reached a head in the mid-1800s as London's population grew to above 2.5 million. The introduction of flushing toilets meant that more water was flushed into the sewers, along with the associated effluent. The increased adoption of flushing toilets, as well as the wider use of factories, meant that the volume of domestic and industrial waste flowing straight into the river increased significantly.

In addition to industrial waste, there was also a large amount of domestic waste ending up in the Thames. By 1857, about 250 tons of faeces were discharged into the river every day. The combination of human waste and industrial effluent created a foul smell, known as the "'Great Stink'" in 1858, which attracted the attention of government members. The hot weather during this time exacerbated the smell, and the river was described as having turned into a "'dark light brown liquid with a very smelly smell'.

The pollution in the Thames had serious health consequences, with three outbreaks of cholera before the Great Stink being blamed on the river's pollution. The river was also declared unsafe for drinking, and the water was described as containing harmful substances such as arsenic and lead. The Natural History Museum declared the Thames biologically dead in 1957, and the bombings during World War II further worsened the situation by damaging sewers and causing sewage to spill into the river.

However, there have been successful restoration initiatives throughout the late 19th and 20th centuries, and the Thames is now considered one of the cleanest rivers in the world. These initiatives involved improving sewage treatment, implementing regulations, and investing in wastewater treatment infrastructure.

Sewage systems

Before the widespread adoption of sewage systems, domestic and factory waste would often seep into the groundwater or flow through the streets. Many of the tributaries that fed into the Thames became dumping grounds. The River Fleet, for instance, was known as the Fleet Ditch and was described by author Jonathan Swift in 1810 as containing:

> Sweepings from Butchers Stalls, Dung, Guts and Blood,

> Drown’d Puppies, stinking Sprats, all drench’d in Mud,

> Dead Cats and Turnip-Tops come tumbling down the Flood.

As London's population grew to over 2.5 million in the mid-1800s, the problems of pollution in the Thames worsened. The city's ageing and inadequate sewer system emptied directly into the Thames, and the miasma from the effluent was thought to transmit contagious diseases. There were three outbreaks of cholera before 1855, which were blamed on the ongoing problems with the river.

In 1855, the chemist Michael Faraday wrote a letter to the editor of The Times, describing the Thames River he had seen on a boat trip:

> The whole river has turned into a dark light brown liquid with a very smelly smell. At this time, the whole river is actually a sewer.

The foul smell, known as the Great Stink, finally prompted action from the government. The Metropolitan Board of Works was established in 1855 and tasked with creating a sewage system that avoided dumping waste into the Thames. Civil engineer Joseph Bazalgette proposed a network of 82 miles of underground brick sewers and pumping stations at Deptford, Crossness, Abbey Mills and Chelsea, which disposed of waste east of the city. Work on high-, mid- and low-level systems for the new Northern and Southern Outfall Sewers started at the beginning of 1859 and lasted until 1875.

While Bazalgette's work ensured that sewage was no longer dumped onto the shores of the Thames and brought an end to the cholera outbreaks, the essential problem of dumping sewage into the river was not solved—it was simply moved further away. In 1878, the passenger steamer Princess Alice sank at the spot where the sewers released their waste into the Thames, and many survivors of the initial collision died after ingesting the polluted water.

In the 1960s, the smell of the Thames in warm weather was again notable, and the Port of London Authority and London County Council set about improving sewage treatment and industrial pollution. New laws were also introduced to stop factories from letting their dirty water flow into the river. Today, more than half of London's sewage sludge is sold in pellet form as fertilizer for agricultural use.

Despite these improvements, because London's sewage system was largely built in the 1800s, storm events can still cause excess sewage to overflow into the Tidal Thames, posing a major threat to water quality. However, there is a possible fix on the horizon: London is currently building a "super sewer" project, called the Thames Tideway Tunnel, which is due for completion in 2025.

Pollution sources

The River Thames has been a source of water and food, a hub for trade, and a place for pageantry for Londoners. However, it was also the city's sewer for hundreds of years.

Sewage

The Metropolitan Board of Works was established in 1855 to create a sewage system that avoided dumping waste into the Thames. Joseph Bazalgette, the chief engineer, designed an ambitious network of 82 miles of underground brick sewers and pumping stations at Deptford, Crossness, Abbey Mills, and Chelsea, which disposed of waste east of the city. However, the fundamental issue of dumping sewage into the river remained, and it was simply moved further away.

In 1858, sewage clogging the Thames caused the "Great Stink", and a century later, parts of the river were declared biologically dead. The expansion of sewage treatment plants beginning in 1960 and limits on industrial discharges have helped clean up the Thames to some extent.

Today, sewage still poses a problem for the Thames, with the river receiving discharges from combined sewer overflows during heavy rains, known as stormwater sewage pollution. London is currently building a "super sewer" project, the Thames Tideway Tunnel, which is due for completion in 2025. It will capture and store the millions of tonnes of raw sewage that currently overflow into the estuary.

Industrial Waste

In the past, the Thames' pH would have been affected by pollution from industries such as power stations, killing all wildlife. Industrial discharges and thermal pollution from heated rainwater runoff continue to impact the river's water quality and wildlife.

Microplastics

Microplastics have been detected in the Thames, and while they do not currently pose a health risk, experiments have shown that they can have detrimental effects on aquatic life, turtles, and birds.

Water quality

The River Thames has historically been London's lifeline, serving as a source of water and food, a trade hub, and a site for pageantry. However, for centuries, it also served as the city's sewer. Before the implementation of widespread sewage systems, domestic and factory waste would seep into the groundwater or flow through the streets, with tributaries of the Thames becoming dumping grounds.

The Metropolitan Board of Works, established in 1855, was tasked with creating a sewage system that avoided dumping waste into the Thames. Joseph Bazalgette, the chief engineer, designed an ambitious network of 82 miles of underground brick sewers and pumping stations. While these sewers are still functional, they merely shifted the issue of sewage dumping further away from the city centre.

In recent times, the Thames has been described as "toxic" by television naturalist Steve Backshall, with Bangor University analysis detecting high levels of norovirus, E. coli, and other potentially harmful bacteria in water samples. High levels of microplastics have also been found in the river, which can have detrimental effects on aquatic life, birds, and turtles.

Climate change is another factor that has impacted the Thames. Rising water temperatures and sea levels, influenced by climate change, can have direct negative consequences on aquatic life and reduce the amount of dissolved oxygen in the water. Additionally, the expansion of sewage treatment plants and limitations on industrial discharges since the 1960s have contributed to the cleanup of the Thames to some extent.

The Thames Tideway Tunnel, also known as the "super sewer" project, is currently under construction in London. Expected to be completed in 2025, it aims to capture and store the millions of tonnes of raw sewage that currently overflow into the estuary, further improving the river's water quality.

Climate change impacts

The River Thames has historically been one of London's most polluted rivers. For hundreds of years, the river served as the city's sewer, with domestic and factory waste seeping into the groundwater and flowing through the streets. The problems of pollution in the Thames reached a head in 1858, when sewage clogging caused the "Great Stink". This prompted the introduction of "Bovril boats", which carried sewage sludge out to the Thames Estuary and North Sea for disposal. However, this only moved the issue further away, and the river continued to be a repository for waste, with leaking cesspits and dumped rubbish.

Today, the Thames is considered one of the cleanest city waterways in the world. This remarkable recovery is due to the efforts of scientists, activists, and local communities, as well as improvements in sewage treatment and infrastructure changes in the 20th century. However, climate change remains a wildcard, and ongoing restoration methods must adapt to account for its effects on the ecosystem.

The influences of climate change are clearly impacting the Tidal Thames, with rising temperatures and sea levels continuing to rise above historical baselines. This will undoubtedly affect the estuary's wildlife, leading to changes in life-history patterns and species ranges. For example, the report by the Zoological Society of London in 2021 documented the return of many long-gone species to the river, including the harbour and grey seal. However, it also noted that the situation for fish is deteriorating slightly in the long term, which could be an indication of pressures on fish populations.

In addition, a long-term increase in nitrate concentrations could threaten water quality. Contaminated sediments continue to enter the river, with heavy metals attached to clay particles in riverbeds harming or killing organisms that consume them. The impact of water-soluble medicines that sewage treatment works are unable to filter out on aquatic life is also unknown.

To address these climate change impacts, the Thames Tideway Tunnel, also known as London's "super sewer", is currently being built and is due for completion in 2025. It is designed to capture more than 95% of the sewage spills that enter the river from London's Victorian sewer system, significantly improving water quality and making it a much healthier environment for wildlife to survive and flourish.

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