The launch of the 2022 sewage map has hammered home a sad truth about the prolific issue of sewage pollution here in the River Trent and all of its tributaries. Every river in the Trent catchment is affected by the 30,638 spills lasting for a total of over 155,000 hours in 2022.
Turning the tide on decades of freshwater biodiversity loss is a challenge that cannot be tackled without addressing the unacceptable amount of sewage and other pollution entering our rivers. Sewage pollution introduces faecal bacteria, excess nutrients, antibiotic-resistant strains, pathogens and microplastics to a ‘chemical cocktail’ of pollutants in our rivers.
Alongside agricultural, urban and industrial pollution, sewage has contributed to a reduction in water quality to the point that aquatic life is in dramatic decline and swimming in our rivers and seas is, at times, a risk to human health. Last monitored in 2019, no river in England is in good overall health and only 14% achieve good ecological health.
Data from the sewage map highlights a 19% decline in sewage spills in England and Wales compared to 2021 – a drop the Environment Agency attributed to lower levels of rainfall. Low flows increase the concentration of pollutants often with grave consequences for wildlife.
Understanding the issue – what is causing sewage pollution in our rivers?
Sewage enters our rivers via Stormwater Sewer Overflows (SSOs). Sometimes these are also referred to as CSOs. SSOs have been designed as a pressure release valve. When overwhelmed, sewage is discharged into freshwater bodies, preventing spillages via household and industrial drains. Discharges from monitored SSOs each come with a permitted discharge proportionate to the waterbody. Nonetheless, the 30,000+ spills here in the Trent and 234,000+ in England and Wales, suggest that their use is greater than it should be. Discharges often fall within generous legal permits, despite their detrimental impact on wildlife which all, to some extent, depends on good water quality.
Sewer systems are overwhelmed for a number of reasons. A particular issue is posed by Combined Sewer (CS)drainage network. CS belong to an outdated combination of rain and foul water drainage. Commonly implemented up until the early 2000’s, this pipe system channels both stormwater run-off and raw sewage through a single pipe towards wastewater treatment facilities. During extreme rainfall, flooding or snowmelt, the mixed water is filtered marginally and then enters the watercourse.
The data, however, shows that sewage discharges persist in drought conditions. Last year, England saw six consecutive months of below average rainfall. Continued Combined Sewer Overflow (CSO) discharges during this period reveal that SSOs are no longer emergency valves that help cope with extreme events; they now reduce pressure from a system that is overwhelmed at capacity far too frequently. In 2022, 20 SSOs in the Trent catchment exceeded 100 spills a year and some sewers discharged for over 4,000 hours.
Poor land management, urban planning, drainage and flushing habits add to the issue. Research reveals that a 1% increase of paved areas in urban settings can increase the flood peak by 3%, thereby putting further pressure on existing, outdated infrastructure. New developments also add unbudgeted sewage to a system running at capacity, while blockages caused by ‘unflushables’, including wet wipes, sanitary towels, nappies, cooking oils, not only add microplastics and other pollutants, they also encourage the use of SSOs, as foul water may be blocked from reaching treatment works.
What the data is telling us
The Environment Agency requires water companies to monitor SSOs. Currently 91% of sewers are equipped with sensors measuring the duration and frequency of each discharge. The data is compiled annually and submitted to the Environment Agency. The self-reported data features on the sewage map and provides an insight into underperforming SSOs, as well as, their unacceptably high levels of discharging.
It does not provide clarity on the volume of water entering the waterbody, or its ecological impact. The submitted data also does not specify whether the discharge falls into legal permits, nor does it cover all CSOs, as some locations continue to be unmonitored by the ten reporting water companies.
How are rivers in the Trent affected by sewage?
Trent Rivers Trust works within seven catchments which all drain into the river Trent. Each catchment plays a unique role in the river system and while always detrimental, the impact of sewage has different impacts for wildlife and communities and different places.
Staffordshire Trent Valley
This part of the Trent catchment forms the start of the Trent’s journey to the Humber Estuary. Rising in Biddulph Moor in the Staffordshire Moors, the Trent quickly descends into Stoke-on-Trent, where the river is hit by urban pollutants and shortcomings in sewage infrastructure. Other tributaries including the Penk, Blithe and Sow play a similar role, as pollution carried into the Trent in its headwaters will have a knock-on effect further downstream.
Vulnerable to sewage pollution, due to the widespread use of infrastructure mixing rainwater and sewage in these urban areas, the Trent and its early tributaries suffer from pollution early on. Significant modifications to the river also mean that the river is less likely to cope with the excess nutrients introduced by sewage.
Buxton treatment works saw over 100 sewage spills in 2022, while Abbey Bromley saw 1,000+ hours of discharge draining into Mires Brook.
Tame, Anker and Mease
Flowing through Birmingham, Burton-on-Trent, Tamworth, Wolverhampton and Nuneaton, water quality in the Tame, Anker and Mease catchment is marked by urban heavyweights, as well as, pressures from agriculture. With sewage being associated with urban clusters, these tributaries add pressure on the Trent early on. The twin challenge of heavy modification and pollution strips rivers of coping mechanisms, whilst leaving the watercourse exposed to a host of pollutants.
Most affected in terms of spill levels exceeding 100 were the River Sence near Coalville, the River Mease near Measham, the Anker near Tamworth and a SSO upstream of Burton-on-Trent. The latter spilled for over 4,000 hours.
Draining from the Peak District, the Derbyshire Derwent is a much-visited river winding via Derby into the Trent. The river that kick-started the industrial revolution, contains multiple barriers to fish migration that are a consequence of harnessing the power of the Derwent. Barriers can mean that fish populations struggle to escape pollution, including sewage.
Three sewers discharge near Belper each discharge more than 100 times into the Derwent. A fourth high frequency spiller near Weston spills into a tributary brook of the Derwent, joining the river in Derby.
Discharges exceeding 1,000 hours affect the river Lathkill near Youlgreave, Bradwell Brook near Bamford, Tideswell Brook, a tributary of the River Wye, Baslow sewage works discharging into the Derwent,and the River Ecclesbourne near Wirksworth and Weston Underwood Brook near Alfreton.
Draining from the Peak District, the Dove is a tributary of the River Trent, with the River Churnet and Manifold as its main tributaries. While this catchment is predominantly rural and thus affected by pressures posed by agriculture, sewage is affecting the river, too. The renowned fishing river is home to nationally important species such as the Atlantic salmon. Yet, pollution, not limited to sewage, puts the survival rates of fish populations, depending on clean spawning grounds at risk.
In 2021, the Dove catchment has seen 83 Storm overflows, 2,247 spills, 14,656 hours with 4 locations seeing sewage spill on more than 100 occasions over the course of one year. These include Henmore and Knieveton Brook near Ashbourne, Froghall and Sudbury. Knieveton and Sudbury SSOs discharged for more than 1,000 hours in the tributaries of the Dove.
The Soar and Wreake are the main rivers in the Soar catchment. Flowing through Leicester, Loughborough and Melton Mowbray, this catchment covers large parts of Leicestershire and Rutland, before draining into the Trent near Long Eaton. Much like elsewhere in the Midlands, the rivers in the Soar catchment have been heavily modified for agricultural and industrial purposes. Their modification reduces their capacity to cope with pollution.
Three locations exceed 100 spills including Billesdon spilling into the River Sence and Whissendine and Somberby each discharging into the nearby brook. A pumping station near Coalville and an unnamed SSO near Wigston discharged for over 1300 hours
The Lower Trent and Erewash
Stretching from the Humber Estuary to the Nottingham- and Derbyshire borderlands, the Lower Trent and Erewash is characterised by agricultural land use and urban clusters, including Nottingham’s National Watersport Centre. Good and bad – whatever the Trent’s flow has been carrying on its journey will be deposited in the estuary or at sea.
According to the map, 288 storm overflows on 5,034 occasions were counted for a total duration of 22,740 hours.
Three sewers recorded spills for over 1,000 hours. These sewers are located in Alverton, the upper reaches of the Erewash near Pinxton and Ilkeston.
Idle and Torne
The Idle and Torne are the final set of tributaries of the River Trent. Flowing through Mansfield, Worksop and Retford, the Idle and Torne and its tributaries are shaped by historic agricultural drainage and redirections, agriculture and urban pressures.
Pollution added during this section of the river is most likely to impact on the ecological health in the Humber Estuary, a vital wildlife habitat and corridor for aquatic and bird species.
Consistent with the rest of the catchment, sewage is prolific, though no location spills more than 100 times or more than 1,000 hours.
Overwhelmed and underinvested – our water infrastructure no longer copes with modern demand, leaving overburdened rivers vulnerable.
Comprehensive, capacity-boosting investment and upgrades to current infrastructure are an obvious and vital step to take. Some of this is already underway, through water companies. Without even further investment, however, we will not see enough improvement in water quality affected by sewage pollution. Not only do we need to further investment from water companies, we need governments to facilitate tighter regulations, enforcement and further investment.
Locally, we need to think about the impact of current and new developments on surface water run-off. We need to be much more ambitious about embedding nature-based solutions, i.e. Sustainable Drainage systems, and consider the impact of additional foul water will have on sewage infrastructure.
What you can do
Talk to your MP about water quality A personalised message explaining why healthy rivers matter and how your patch has been affected by pollution can help facilitate much-needed infrastructure and water quality investment.
Ensure only pee, poo and paper get put down the loo. Nothing else that could cause blockages. Bin it don’t flush.
River-friendly gardens and driveways
You can reduce surface runoff by making outside surfaces as permeable as possible. This not only helps reduce flood risk, but also reduces the burden on outdated sewer systems.
If you see pollution, report it to the Environment Agency incident hotline 0800 80 70 60.
The bigger picture
We cannot forget the bigger picture. Rivers and catchments are deprived of nature-based processes (think urban and rural wetlands and connected floodplains, trees in the right places, water-soaking uplands). Nutrient pollution, in particular, remains a huge issue, with increasingly extreme weather adding more pressure on infrastructure and freshwater ecology. Long-term investment in solutions that not only reduce pollution pressure, but also restore our rivers is needed. We need levelling-up for the Trent, Soar, Derwent and other local rivers.
A climate-proof future can only exist with resilient rivers.