The vulnerability of impoundments has been dramatically demonstrated throughout their history and the need for regulation of these structures within Great Britain was identified by the jury at the inquest into the Dale Dyke Dam failure, which occurred 150 years ago, in 1864. No legislation was brought forward at that time. Over sixty years passed and again the issue of dam safety was brought back to the attention of the British public as there were two catastrophic structural failures which occurred within a short space of time in 1925. A cascade failure, involving two dams impacted Dolgarrog in North Wales, killing 16 people and a dam failure in Skelmorlie, North Ayrshire, Scotland killed 5 people.

These failures led to the introduction of the Reservoirs (Safety Provisions) Act in 1930, which was subsequently updated as The Reservoirs Act 1975. However, this legislation does not apply in Northern Ireland.

There are two references in the Northern Ireland Statute book to reservoir safety. One is contained in Article 33 of the Drainage (Northern Ireland) Order 1973. The other is in Article 297 of the Water and Sewerage Services (Northern Ireland) Order 2006. This legislation enables the making of ‘regulations with respect to the construction, inspection, maintenance and repair of reservoirs and dams’, however, no such regulations have ever been brought forward. There is, therefore, no regulation of reservoir safety in Northern Ireland, which means that it is left to the discretion of owners and operators under common law, (that is law developed by judges as the outcome of legal cases).

DARD Rivers Agency is the competent authority for implementation of the EU Floods Directive and the Preliminary Flood Risk Assessment (PFRA) which was completed in December 2010, and identified reservoir failure as a potentially significant flood source within Northern Ireland.

The lack of regulation means that the likelihood of dam failure is impossible to determine, as there is no overall view of the condition of the reservoir stock. Rivers Agency, therefore, began the process of understanding this risk by first quantifying the potential impacts of total dam failure. The PFRA mapped dam breach inundation and identified that approximately 66,000 people who reside in reservoir breach inundation areas would be impacted if a total failure of the 156 reservoirs were to occur. While it is accepted that this is a hugely unrealistic situation it was the only way of quantifying the potential hazard, given that no condition data was available. Forty five of the reservoirs identified are the responsibility of Northern Ireland Water, the body which delivers public water and sewerage services. Although not regulated, these structures are generally maintained within the spirit of the 1975 Act.
There have been no recorded deaths caused by reservoir failure in Northern Ireland but there have been a number of dam incidents. In the absence of reservoir regulation and, with the information on the potential impact of failure, the NI Executive agreed in late 2010 that the Minister for Agriculture and Rural Development should bring forward reservoir safety legislation.


The purpose of the policy is to create a legal and administrative framework for regulating reservoir safety. The key features of the policy proposals, which were developed through engagement and communication with key stakeholders, are:

  • That all reservoirs with a capacity of 10,000m3 or more would be regarded as controlled reservoirs and would be registered with the Reservoirs Authority.
  • DARD would act as the Reservoir Authority and would be responsible for enforcing the provisions under the legislation.
  • The reservoir manager is the responsible for reservoir safety.
  • A risk based approach should be introduced for all controlled reservoirs. Initially this would primarily be an impact designation, based on the consequence of reservoir failure.
  • Each reservoir which falls within the scope of a controlled reservoir would be assigned a risk designation according to whether it poses a threat to human life, the environment, cultural heritage and economic activity.
  • Each controlled reservoir would be subject to a proportionate supervision and inspection regime, depending on its risk designation.
  • Construction and alteration of controlled reservoirs should be undertaken under the supervision of appropriately experienced and qualified engineers.
  • Independent, qualified Civil Engineers, drawn from a panel appointed by the Department, would provide technical expertise when undertaking construction, supervision and inspection roles under the framework.
  • There should be provisions for the review of risk designation decision, independent appeal, dispute resolution and enforcement, including offences and penalties.
  • There should be a number of miscellaneous provisions, including emergency powers and powers of entry.

The policy proposals were subject to a twelve week public consultation which finished on 1 June 2012.

Legislative progress

The Reservoirs Bill was introduced in the NI Assembly on 20 January 2014, and moved to Second Stage on 4 February 2014. The Second Stage provides the opportunity for the general principles of the Bill to be debated, however, the detail is not discussed, nor can amendments be introduced. Following the debate, the Assembly voted on the Bill, which then moved to the Committee Stage. The Agriculture and Rural Development Committee began scrutiny of Bill in February and heard evidence from the Institution of Civil Engineers, NI Water, private owners, fishing clubs and the Department. The Report on the Reservoirs Bill was ordered to be printed on 24 June 2014 and it states that the Committee ‘had no concerns with the major principle of the Bill in that it is designed to protect people, the environment, economic and cultural assets from the consequences of a dam failure and the reservoir flooding.’

The report also outlined a number of concerns expressed during the scrutiny process, the absence of data on the physical condition of the dam structures and therefore the inability to quantify the cost of bringing them to an acceptable standard. The Committee was also concerned that the term ‘high risk’ would cause undue unease to those who live and work below such structures when in reality the reservoir manager could be compliant with the legislation with all reasonable steps taken to ensure the safety of the impoundment.

The Committee accepted the views of some witness that reservoir engineers may be overly risk adverse and apply the precautionary principle, and this could result in higher costs than necessary. To allay these fears a number of amendments to the legislation are proposed which in effect give the Department an oversight role of reservoir engineers. At Committee there was much discussion about the frequency of Supervising Engineers visits and in particular if the minimum standard proposed could be relaxed in order to reduce the cost burden on reservoir managers. A number of amendments were proposed but these were not agreed by the Committee and will be debated in the Assembly at the next stage of the legislative process. The Committee spent considerable time exploring the possible cost of compliance and heard evidence from private individuals and third sector organisations about the hardship this may cause.

In order to address these concerns and to ensure that the safety of reservoirs is ultimately regulated the Department proposed a grant scheme to assist with the initial requirements of the new legislation. In addition a ‘pause’ was also introduced into the Bill, which in essence only makes the initial inspection a legal requirement. The reoccurring aspects of the regulatory regime can only be commenced by a vote in the Assembly and this will be subject to satisfactory assurance being provided on the likely cost impact on reservoir managers based on the condition information gleaned from the initial inspection reports.

Robust safety regime

The necessity of a robust reservoir safety regime is beginning to be understood amongst those who own or operate these structures in Northern Ireland. The proposed legislation will enable assurance to be provided to the wider community that this risk of a reservoir failure is being properly managed.
The current position in Northern Ireland is that, reservoir safety is the responsibility of the owners or managers under common law. The new legislation will not change this fundamental principle but it will introduce a regulated system of proportionate management that should ensure structures are in reasonable condition and, therefore in the event of a failure, this may control or limit reservoir managers’ liability.

David Porter is the Director of Operations at Rivers Agency and current Chairman of the Institution of Civil Engineers in Northern Ireland.

The work described in this paper is the result of close cooperation between officials of DARD Rivers Agency and the Institution of Civil Engineers (ICE) Northern Ireland reservoir safety advisory panel. From Rivers Agency I would like to thank Kieran Brazier, Mary McKeown, Quinton Campbell and David Henderson for their input. The ICE panel consisted of William Gowdy, Alan Cooper, David McKillen, Stephen Orr, Donal Ryan and Richard Kirk.