Reservoir Safety Reform
Overview
Click here to view this page in Welsh.
In Wales, there are around 400 registered reservoirs which are regulated under the Reservoirs Act 1975 - the law which sets the minimum safety standards. We have designated over half of these as “high-risk reservoirs” where we think a failure and any subsequent uncontrolled release of water could pose a risk to life.
Reservoir safety is about ensuring the physical structure of a reservoir, its dams and embankments are safe.
Wales has an excellent reservoir safety record. However, the independent review and report published by Prof. Balmforth following the Toddbrook reservoir incident in 2019 is a reminder that we cannot be complacent. Aging dams, increasing demands on water supplies, and the impacts of a changing climate are all prompts for the need to keep our regulatory approach under review.
Wales’ reservoir safety record has been achieved through the fundamental principles of acting on the advice and recommendations of qualified civil engineers who specialise in reservoir safety, underpinned by compliance with the law.
Introduction
In November 2024, the Deputy First Minister and Cabinet Secretary for Climate Change, Environment and Rural Affairs confirmed the Welsh Government’s intention to reform reservoir safety management practices and modernise the Reservoirs Act 1975.
As part of collaboration between Welsh Government, Natural Resources Wales (NRW), the Department for Environment, Food and Rural Affairs (Defra) and the Environment Agency (EA), we are developing and delivering a Reservoir Safety Reform Programme, to address the recommendations set out in the Independent Reservoir Safety Review Report. The programme will be delivered over several years and this information page will keep you updated on our plans and progress.
Programme vision and aims
Our vision is to modernise the regulation of reservoir safety in Wales, to reduce the risk to those who live and work in the communities downstream and the natural environment, and to ensure reservoirs are resilient to future impacts of climate change.
We will do this by:
- engaging with stakeholders to shape our approach
- strengthening the roles and responsibilities for owners and operators to manage their reservoirs in line with the risk they pose
- giving engineers the duties and powers commensurate with their responsibility to recommend actions and to be able to escalate intervention where needed
- fostering a culture of continuous improvement and development of skills across the reservoir community
- working with government to modernise the legislation that underpins the standards we set, to allow current and emerging safety practice to ensure a robust and proportionate safety regime that is agile and fit for the future.
The need for reform
The key drivers for improving the reservoir safety system are:
- the need for legislation which aligns better with modern risk management practices and expectations.
- the recommendations arising from Prof. David Balmforth’s independent reservoir safety review
- climate change - which is increasing the pressures on reservoir infrastructure and demand for reservoirs and water resources.
- the increasing demand for specialist reservoir engineers in the future, and to address the declining numbers of these engineers.
Devolved administrations
Reservoir safety policy is devolved. Our reform programme is focused on Wales, but we are working closely with the UK Government and other devolved administrations and regulators to share knowledge and support a coherent approach across the UK.
You can visit the Environment Agency's Reservoir Safety Reform information page here.
The focus of reform
The responsibility for the safety of reservoirs falls to three distinct target communities:
- Reservoir owners and operators are ultimately responsible for the safety of their reservoirs. They must appoint specialist civil engineers to construct, inspect and supervise their reservoirs and to act on the engineer’s recommendations. Owners and operators should manage their reservoir safely using trained and competent staff as is necessary.
- Qualified civil engineers/ “panel engineers” are appointed to specialist panels by Government to ensure owners have access to a competent engineer to supervise and inspect reservoir construction and operation.
- Enforcement authorities – in Wales, NRW regulates and enforces reservoir safety.
The reform programme will not change this overall three-way approach, but we anticipate there will be changes for each of these communities.
Programme of reforms
Our reform programme in Wales will:
- report updates through these pages at regular intervals.
- establish the reservoir safety practices that are to be underpinned by law and those where guidance may be considered sufficient.
- implement change through stakeholder engagement, consultation, provision of guidance and new legislation to suit timescales appropriate to the Senedd.
May 2025 Update
Public Consultation
We are planning to hold our first public consultation on reservoir safety reforms in autumn 2025. We will be asking your opinion on a range of changes to reservoir safety regulations across England and Wales, including:
- What is in scope for regulation and structures to be excluded
- an improved hazard classification system for reservoirs
- a safety management system for reservoirs
- clearer responsibilities for reservoir owners
- the structure of engineer panels and their responsibilities
- new responsibilities for regulators
New hazard classification
As part of the Reservoir Safety Reform Programme the research and development project “Developing a new hazard classification for reservoir safety for England and Wales” was completed in March 2025.
A mixed disciplinary team of experts in reservoir safety, industry safety and risk management, GIS and economic analysis, together with representative reservoir owners and engineers, have shaped the developments.
The project has provided key elements to support the RSR reforms:
- a new hazard classification (used to group reservoirs by how likely they are to cause harm)
- a framework for a safety management system, which incorporates current safety management practices with additional good practice from other high risk sectors
- a cost-benefit analysis of the proposed approach – which will inform an impact assessment required for new legislation
The new classification and safety management system are research proposals and are not agreed policies at this stage. Work on the details of the safety management system and how it might work for each class is ongoing. We are using the research to inform policy proposals for the whole safety regime. Public consultation on these proposals is expected in autumn 2025.
The R&D project reports summarise the development of the proposed new classification system, including the research process, key findings, and final proposals and recommendations. The reports will be published following a peer review and approvals process, expected in Spring 2025 on Defra’s Science Search website. This page will be updated when the reports are available.
Hazard classification
The project has developed and tested options for a new hazard classification system and has proposed a system which has four classes related to level of hazard.
The current classification has just 'high risk' and 'not high risk' categories. This would be replaced with a system with four hazard classes from Class 1 (highest risk) to Class 4 (lowest risk). The proposed new classification structure uses a combination of factors - dam height (H), reservoir volume (V), average societal loss of life (ASLL) and damages (other than loss of life). The height and volume are relevant for assessing the potential energy for escaping water and the ASLL and damages are relevant for assessing the downstream consequences.
A method for the classification process has been proposed and is being considered.
The new system has been designed to include smaller raised reservoirs (SRR) between 10,000-25,000 m3.
The research project has also carried out an evaluation of current risk assessment methods, developed a method for reservoir design review and gathered evidence to inform the approach to onsite emergency planning.
A series of recorded presentations hosted on the Environment Agency’s YouTube channel (English only) explain the research and development in more detail. Parts 1, 2 and 3 explain how the new classification has been developed:
New framework for a risk proportionate safety management system
The proposed classification with 4 classes recognising different levels of hazard and consequences will be combined with an improved safety management system with safety management practices tailored to each class.
Developing this framework for the safety management system has focused on improving current practice and adding elements of good practice from other high-hazard sectors. Work on the details of the safety management system, including Reservoir Safety Management Plans (RSMP), and how it might work for each class is ongoing.
Cost benefit analysis
The research provides baseline estimates of the likely costs and benefits for the options considered for the new classification and safety management system. The analysis will be refined later, following consultation and Ministerial decisions on the new system, to inform an impact assessment to accompany new legislation.
The benefits that we are seeking to deliver are:
• reduced risk to life
• reduced risk of damage to property, infrastructure and the environment
• reduced risk of economic disruption
• fair and proportionate regulation of reservoir safety
Records, registers and management systems
We are currently reviewing the management arrangements for reservoir safety. This includes improvements to systems to ensure operation, maintenance, monitoring and surveillance are being effectively delivered. Our review is looking to update the existing records and information keeping requirements to streamline data management practices and improve efficiency, and effectiveness.
During March and April 2025, we held a series of ten focus groups with owners, reservoir engineers and regulators to help develop our policy proposals. Many thanks to those who attended and contributed to these discussions. Constructive feedback was received which we combined with the outputs of a well-attended workshop at the BDS Conference at Keele University in September 2024
We are now collating and analysing these outputs to help refine the proposed Reservoir Safety Management Plans and inform the associated roles and responsibilities of reservoir owners, engineers and regulators.
Modernising the legal framework
We have been considering the options for modernising the legal framework. Options include:
- New primary legislation to replace the Reservoirs Act 1975,
- Retaining the Act and amending it, and
- Using existing powers to bring reservoir safety within the environmental permitting regime.
Our preferred approach is bringing reservoir safety regulation under the environmental permitting regulations but this has not been decided. Over the coming months, there will be opportunities to share your views through stakeholder meetings, and the public consultation in autumn 2025.
The Environmental Permitting (England and Wales) Regulations 2016 provide a modern regulatory framework for safety regimes for other sectors and industries which could be applied to reservoir safety. It has a hierarchy of permitting that includes exemptions, standard permits and bespoke permits, which we could apply to the different hazard classes to deliver a more proportionate approach.
If we use environmental permitting, the reforms can be introduced through regulations rather than needing a new bill in the Senedd, and so the changes could be made to a more predictable timescale.
Environmental permitting will not change the reforms we need to make following the Independent Reservoir Safety Review Report, but it would provide a practical way of modernising the reservoir safety regime.
We intend to involve stakeholders in considering this approach including through the written consultation in autumn 2025.
Get in touch
By email: RSR_Cymru@naturalresourceswales.gov.uk
By phone: 03000 65 3000 (8am to 6pm, Monday to Friday). This is our Customer Contact Centre - please ask to speak to a member of the Reservoir Regulation Team.
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