Unveiling Combined Sewage Overflow (CSO) data in North Wales.
Written by CEO Laura Owen Sanderson.
North Wales, with its picturesque landscapes and pristine water bodies, is known for its natural beauty and thriving ecosystems. However, beneath the surface lies a hidden threat that has been affecting water quality and ecosystem health – sewage Combined Sewer Overflow (CSO) spills. 60,000 hours of sewage pumped into our rivers in 2022.
In this blog, we will delve into the issue of CSO spills in North Wales, explore the data available on these spills, and highlight the need for action to address this environmental challenge.
Understanding CSO Spills:
CSOs are a type of sewer infrastructure that combines stormwater runoff with sewage in a single pipe system. During periods of heavy rainfall or snowmelt, the volume of water in the combined sewer system can exceed its capacity, leading to overflows. To prevent sewage backups and flooding in homes and streets, CSOs are designed to discharge excess water and sewage into nearby water bodies, such as rivers, streams, and coastal waters.
While CSOs are intended to prevent urban flooding, they can have detrimental impacts on water quality and aquatic ecosystems. CSO spills can introduce harmful pathogens, nutrients, and pollutants into water bodies, posing risks to human health, wildlife, and aquatic habitats. In North Wales, CSO spills have been a concern for water quality and environmental conservation efforts.
Unveiling CSO Spill Data in North Wales:
Obtaining accurate and up-to-date data on CSO spills is crucial for understanding the magnitude of the problem and identifying areas that require intervention. In North Wales, there are efforts to monitor and collect data on CSO spills, although the availability and accessibility of this data may vary.
One source of CSO spill data in North Wales is the monitoring conducted by the water and wastewater utility company Dŵr Cymru Welsh Water and Natural Resources Wales. These organizations regularly monitor and report on CSO spills as part of their regulatory requirements. Although particularly in the south Menai Strait catchment there are many un monitored CSOs spilling without any consequence. One of these CSO discharges sits at the top of a failing waterbody identified by the WFD. Each year The Rivers Trust collates this data into a Sewage Map. Here you can monitor the frequency and duration of sewage spills.
The data includes information on the frequency, duration and location of CSO spills.
The top worst offending CSO’s within our catchment in 2022 are:
1) Llangybi Wwtw, Pwllheli (Dwr Cymru Welsh Water). In 2022, this sewer storm overflow spilled 153 times for a total of 2867.75 hours. This CSO is unpermitted.
2) Screened Storm Sewage At Dolwyddelan Wwtw (Dwr Cymru Welsh Water). Permit number: CG0397001 . In 2022, this sewer storm overflow spilled 153 times for a total of 2862.25 hours
3) Cso At Llithfaen Wwtw (Dwr Cymru Welsh Water).Permit number: AB3497ZT. In 2022, this sewer storm overflow spilled 144 times for a total of 2672.25 hours .
4) Cwm Penmachno - Cso (Dwr Cymru Welsh Water). Permit number: CG0163101. In 2022, this sewer storm overflow spilled 143 times for a total of 2641.25 hours .
5) Settled Storm At Beddgelert Waste Water Treatment (Dwr Cymru Welsh Water). Permit number: CG0406401. In 2022, this sewer storm overflow spilled 157 times for a total of 2596.50 hours .
The term "unpermitted" refers to a situation where a CSO discharge occurs without proper authorisation or permit from the relevant regulatory authorities. In Wales this is Natural Resources Wales - NRW. These agencies issue permits that specify the conditions under which CSOs can be operated, including the frequency and duration of discharges, and the quality of the discharged water.
If a CSO discharge occurs without proper authorisation, it is unpermitted, which can result in legal and regulatory consequences, including fines, penalties, and enforcement action by the environmental agencies. Unpermitted CSO discharges are dangerous to rivers because they contribute to water pollution, harm aquatic ecosystems, and pose risks to public health and the environment. North Wales Rivers Trust have today raised the issue of the Llangybi Wwtw in Pwillheli with NRW enforcement team and will keep you updated. We will also be asking Dwr Cymru to respond to this particular reoffending CSO as it made our top 2 list in the previous year.
Another source of data is citizen science initiatives that conduct independent monitoring of water bodies and raise awareness about CSO spills. These efforts often rely on public participation in data collection, observation, and reporting of CSO spills, which can help to fill data gaps and engage local communities in environmental stewardship. We have two water quality citizen science initiatives launching in 2023. In order to take part join our newsletter and look out for updates.
Challenges and Impacts of CSO Spills:
CSO spills pose several challenges and impacts in North Wales. One of the key challenges is the potential for water pollution, as sewage and pollutants from CSO spills can harm aquatic life, degrade water quality, and threaten public health. Nutrient enrichment from CSO spills can also contribute to eutrophication, leading to oxygen depletion, fish kills, and loss of biodiversity in affected water bodies.
Furthermore, CSO spills can affect recreational activities such as swimming, fishing, and boating, and can have economic implications for tourism, fisheries, and local businesses. CSO spills can also undermine efforts to achieve water quality targets and comply with environmental regulations, which can have legal and reputational consequences for responsible parties.
The Need for Action:
Given the potential risks and impacts of CSO spills, it is imperative to take action to address this environmental challenge in North Wales. This requires collaborative efforts among stakeholders, including water and wastewater utility companies, government agencies, environmental organizations, local communities, and citizens.
Some key actions that can be taken include:
1) Improving CSO monitoring and reporting: Ensuring that accurate and up-to-date data on CSO spills are collected, reported, and made publicly accessible can help to inform decision-making and prioritise interventions.
2) Investing in infrastructure upgrades: Upgrading and expanding sewage treatment infrastructure. This is imperative and has to be addressed urgently. Although the cost is great estimated at 36 billion in Wales, it is no doubt imperative as we reach breaking point.
As a freshwater conservation charity with a critical eye, we would also like to address some of the limiting factors in the data recently released from 2022. While the data sheds light on the issue of CSO spills in the region, it is essential to challenge the prevailing narrative and consider potential limitations and complexities associated with interpreting such data.
Data Interpretation Challenges:
Interpreting CSO sewage data can be complex and nuanced. The data may reflect the frequency, duration, volume, and location of CSO spills, but it may not necessarily capture the full context of the situation. For instance, high CSO spill data in a particular area may be influenced by factors such as the age and condition of the sewer infrastructure, local topography, and weather patterns.
Long-term Planning Challenges:
It is estimated that replacing the Welsh CSO system alone would be around £36 billion. Addressing the issue of CSO spills requires long-term planning and investment in infrastructure upgrades. However, implementing such measures may not be straightforward. Factors such as funding constraints, regulatory requirements, and competing priorities may impact the timeline and feasibility of infrastructure upgrades.
Additionally, there may be challenges associated with identifying suitable locations for infrastructure upgrades, considering factors such as land availability, environmental impact assessments, and community acceptance. Decisions related to infrastructure upgrades may require careful consideration of various social, economic, and environmental factors, which can complicate the decision-making process.
Balancing Environmental and Economic Interests:
Another challenge in addressing CSO spills is striking a balance between environmental and economic interests. While reducing CSO spills is an imperative goal, it will require significant investments in infrastructure upgrades and operational changes, which can have financial implications for water and wastewater utility companies and every household in Wales.
In some cases, utility companies may argue that the costs of infrastructure upgrades may outweigh the potential benefits in terms of environmental outcomes. But we believe the sewage / water infrastructure is no longer fit for purpose, does not meet the needs for a growing population and is harmful to the aquatic system.
Moving forward, North Wales Rivers Trust is committed to working towards sustainable solutions for environmental challenges and campaigning for improvements in infrastructure, legislation and enforcement of polluters who do not stick to their legal obligations. Sign up to our newsletter and we will keep you updated on our pursuit for tighter enforcemnet, stricter legislation and accountability and investment in a system that is no longer fit for purpose.